From 3e1f87820af92c3df8393039b064d59abe66d525 Mon Sep 17 00:00:00 2001
From: Erik Corry <erik@toit.io>
Date: Wed, 29 Nov 2023 16:46:55 +0100
Subject: [PATCH 1/4] New byte code for branch on not null

---
 src/bytecodes.h                             |  2 ++
 src/compiler/byte_gen.cc                    | 14 ++++++++++++++
 src/compiler/emitter.cc                     |  3 +++
 src/compiler/emitter.h                      |  3 ++-
 src/compiler/propagation/type_propagator.cc | 20 ++++++++++++++++++++
 src/interpreter_run.cc                      | 16 ++++++++++++++++
 tests/strip/throw-test.toit                 |  2 +-
 tools/snapshot.toit                         |  2 ++
 8 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/src/bytecodes.h b/src/bytecodes.h
index 6e72eb7e6..76b0f8b3c 100644
--- a/src/bytecodes.h
+++ b/src/bytecodes.h
@@ -179,9 +179,11 @@ enum BytecodeFormat {
   BYTECODE(BRANCH,                     3, OP_SF, "branch")                     \
   BYTECODE(BRANCH_IF_TRUE,             3, OP_SF, "branch if true")             \
   BYTECODE(BRANCH_IF_FALSE,            3, OP_SF, "branch if false")            \
+  BYTECODE(BRANCH_IF_NOT_NULL,         3, OP_SF, "branch if not null")         \
   BYTECODE(BRANCH_BACK,                5, OP_SB_SB, "branch back")             \
   BYTECODE(BRANCH_BACK_IF_TRUE,        5, OP_SB_SB, "branch back if true")     \
   BYTECODE(BRANCH_BACK_IF_FALSE,       5, OP_SB_SB, "branch back if false")    \
+  BYTECODE(BRANCH_BACK_IF_NOT_NULL,    5, OP_SB_SB, "branch back if not null") \
   BYTECODE(PRIMITIVE,                  4, OP_BU_SU, "invoke primitive")        \
   BYTECODE(THROW,                      2, OP_BU, "throw")                      \
   BYTECODE(RETURN,                     3, OP_BS_BU, "return")                  \
diff --git a/src/compiler/byte_gen.cc b/src/compiler/byte_gen.cc
index 68c72d31d..2b7c46dc2 100644
--- a/src/compiler/byte_gen.cc
+++ b/src/compiler/byte_gen.cc
@@ -241,6 +241,20 @@ void ByteGen::visit_for_control(Expression* expression,
     return;
   }
 
+  if (yes == fallthrough && expression->is_CallBuiltin()) {
+    auto builtin = expression->as_CallBuiltin();
+    if (builtin->target()->kind() == Builtin::IDENTICAL) {
+      bool left_is_null = builtin->arguments()[0]->is_LiteralNull();
+      bool right_is_null = builtin->arguments()[1]->is_LiteralNull();
+      if (left_is_null || right_is_null) {
+        Expression* other = builtin->arguments()[left_is_null ? 1 : 0];
+        visit_for_value(other);
+        __ branch(Emitter::IF_NOT_NULL, no);
+        return;
+      }
+    }
+  }
+
   visit_for_value(expression);
   if (yes == fallthrough) {
     __ branch(Emitter::IF_FALSE, no);
diff --git a/src/compiler/emitter.cc b/src/compiler/emitter.cc
index 79f55ab1f..edb54ee6d 100644
--- a/src/compiler/emitter.cc
+++ b/src/compiler/emitter.cc
@@ -451,6 +451,9 @@ void Emitter::branch(Condition condition, Label* label) {
   } else if (condition == IF_TRUE) {
     op = label->is_bound() ? BRANCH_BACK_IF_TRUE : BRANCH_IF_TRUE;
     stack_.pop();
+  } else if (condition == IF_NOT_NULL) {
+    op = label->is_bound() ? BRANCH_BACK_IF_NOT_NULL : BRANCH_IF_NOT_NULL;
+    stack_.pop();
   } else {
     ASSERT(condition == IF_FALSE);
     op = label->is_bound() ? BRANCH_BACK_IF_FALSE: BRANCH_IF_FALSE;
diff --git a/src/compiler/emitter.h b/src/compiler/emitter.h
index 28ae60a89..40f83c106 100644
--- a/src/compiler/emitter.h
+++ b/src/compiler/emitter.h
@@ -73,7 +73,8 @@ class Emitter {
   enum Condition {
     UNCONDITIONAL,
     IF_TRUE,
-    IF_FALSE
+    IF_FALSE,
+    IF_NOT_NULL,
   };
 
   List<uint8> bytecodes();
diff --git a/src/compiler/propagation/type_propagator.cc b/src/compiler/propagation/type_propagator.cc
index 714a609a4..ce393b79c 100644
--- a/src/compiler/propagation/type_propagator.cc
+++ b/src/compiler/propagation/type_propagator.cc
@@ -1173,6 +1173,13 @@ static TypeScope* process(TypeScope* scope, uint8* bcp, std::vector<Worklist*>&
     }
   OPCODE_END();
 
+  OPCODE_BEGIN(BRANCH_IF_NOT_NULL);
+    stack->pop();
+    uint8* target = bcp + Utils::read_unaligned_uint16(bcp + 1);
+    scope = worklists.back()->add(target, scope, true);
+    stack = scope->top();
+  OPCODE_END();
+
   OPCODE_BEGIN(BRANCH_BACK);
     uint8* target = bcp - Utils::read_unaligned_uint16(bcp + 1);
     return worklists.back()->add(target, scope, false);
@@ -1212,6 +1219,19 @@ static TypeScope* process(TypeScope* scope, uint8* bcp, std::vector<Worklist*>&
     }
   OPCODE_END();
 
+  OPCODE_BEGIN(BRANCH_BACK_IF_NOT_NULL);
+    TypeSet top = stack->local(0);
+    bool can_be_null = top.contains_null(program);
+    stack->pop();
+    uint8* target = bcp - Utils::read_unaligned_uint16(bcp + 1);
+    if (!can_be_null) {
+      // Unconditionally continue at the branch target.
+      return worklists.back()->add(target, scope, false);
+    }
+    scope = worklists.back()->add(target, scope, true);
+    stack = scope->top();
+  OPCODE_END();
+
   OPCODE_BEGIN(INVOKE_LAMBDA_TAIL);
     propagator->ensure_code_failure();
     scope->throw_maybe();
diff --git a/src/interpreter_run.cc b/src/interpreter_run.cc
index 76f349868..980817a9b 100644
--- a/src/interpreter_run.cc
+++ b/src/interpreter_run.cc
@@ -961,6 +961,13 @@ Interpreter::Result Interpreter::run() {
     }
   OPCODE_END();
 
+  OPCODE_BEGIN(BRANCH_IF_NOT_NULL);
+    if (POP() != program->null_object()) {
+      bcp += Utils::read_unaligned_uint16(bcp + 1);
+      DISPATCH(0);
+    }
+  OPCODE_END();
+
   OPCODE_BEGIN(BRANCH_BACK);
     uint8* entry = bcp - Utils::read_unaligned_uint16(bcp + 3);
     bcp -= Utils::read_unaligned_uint16(bcp + 1);
@@ -986,6 +993,15 @@ Interpreter::Result Interpreter::run() {
     }
   OPCODE_END();
 
+  OPCODE_BEGIN(BRANCH_BACK_IF_NOT_NULL);
+    if (POP() != program->null_object()) {
+      uint8* entry = bcp - Utils::read_unaligned_uint16(bcp + 3);
+      bcp -= Utils::read_unaligned_uint16(bcp + 1);
+      CHECK_PREEMPT(entry);
+      DISPATCH(0);
+    }
+  OPCODE_END();
+
   OPCODE_BEGIN(INVOKE_LAMBDA_TAIL);
     B_ARG1(bci_offset)
     Instance* receiver = Instance::cast(STACK_AT(bci_offset + FRAME_SIZE));
diff --git a/tests/strip/throw-test.toit b/tests/strip/throw-test.toit
index 1a06432a0..4602708f8 100644
--- a/tests/strip/throw-test.toit
+++ b/tests/strip/throw-test.toit
@@ -13,7 +13,7 @@ main args:
   compiler := args[1]
   runner := args[2]
 
-  with-tmp-directory: | tmp-dir|
+  with-tmp-directory: | tmp-dir |
     variants := compile-variants --compiler=compiler --tmp-dir=tmp-dir input
 
     non-stripped-snapshot := variants[0]
diff --git a/tools/snapshot.toit b/tools/snapshot.toit
index 042562f26..6eefb69fe 100644
--- a/tools/snapshot.toit
+++ b/tools/snapshot.toit
@@ -886,9 +886,11 @@ BYTE-CODES ::= [
   Bytecode "BRANCH"                     3 OP-SF "branch",
   Bytecode "BRANCH_IF_TRUE"             3 OP-SF "branch if true",
   Bytecode "BRANCH_IF_FALSE"            3 OP-SF "branch if false",
+  Bytecode "BRANCH_IF_NOT_NULL"         3 OP-SF "branch if not null",
   Bytecode "BRANCH_BACK"                5 OP-SB-SB "branch back",
   Bytecode "BRANCH_BACK_IF_TRUE"        5 OP-SB-SB "branch back if true",
   Bytecode "BRANCH_BACK_IF_FALSE"       5 OP-SB-SB "branch back if false",
+  Bytecode "BRANCH_BACK_IF_NOT_NULL"    5 OP-SB-SB "branch back if not null",
   Bytecode "PRIMITIVE"                  4 OP-BU-SU "invoke primitive",
   Bytecode "THROW"                      2 OP-BU "throw",
   Bytecode "RETURN"                     3 OP-BS-BU "return",

From c066f933bb454bfb93aef65a82d0b5ee4e68719c Mon Sep 17 00:00:00 2001
From: Erik Corry <erik@toit.io>
Date: Fri, 1 Dec 2023 10:31:38 +0100
Subject: [PATCH 2/4] Update gold

---
 .../type_propagation/gold/array-do-test.gold  |   6 +-
 .../gold/array-do-test.gold-O2                |   6 +-
 tests/type_propagation/gold/block-test.gold   | 112 +++++-----
 .../type_propagation/gold/block-test.gold-O2  | 112 +++++-----
 .../type_propagation/gold/deltablue-test.gold | 208 ++++++++---------
 .../gold/deltablue-test.gold-O2               | 210 +++++++++---------
 tests/type_propagation/gold/field-test.gold   |  12 +-
 .../type_propagation/gold/field-test.gold-O2  |  12 +-
 tests/type_propagation/gold/finally-test.gold |  82 +++----
 .../gold/finally-test.gold-O2                 |  80 +++----
 tests/type_propagation/gold/global-test.gold  |  14 +-
 .../type_propagation/gold/global-test.gold-O2 |  14 +-
 tests/type_propagation/gold/lambda-test.gold  |  14 +-
 .../type_propagation/gold/lambda-test.gold-O2 |  14 +-
 tests/type_propagation/gold/literal-test.gold |  10 +-
 .../gold/literal-test.gold-O2                 |  10 +-
 tests/type_propagation/gold/local-test.gold   |  30 +--
 .../type_propagation/gold/local-test.gold-O2  |  30 +--
 tests/type_propagation/gold/map-test.gold     |   6 +-
 tests/type_propagation/gold/map-test.gold-O2  |   6 +-
 tests/type_propagation/gold/nlr-test.gold     |  48 ++--
 tests/type_propagation/gold/nlr-test.gold-O2  |  48 ++--
 .../gold/non-local-branch-test.gold           |  36 +--
 .../gold/non-local-branch-test.gold-O2        |  36 +--
 .../gold/non-local-return-test.gold           |  20 +-
 .../gold/non-local-return-test.gold-O2        |  20 +-
 .../gold/null-equals-test.gold                |  10 +-
 .../gold/null-equals-test.gold-O2             |  10 +-
 .../type_propagation/gold/richards-test.gold  | 124 +++++------
 .../gold/richards-test.gold-O2                | 124 +++++------
 tests/type_propagation/gold/spawn-test.gold   |   6 +-
 .../type_propagation/gold/spawn-test.gold-O2  |   6 +-
 tests/type_propagation/gold/time-test.gold    |   4 +-
 tests/type_propagation/gold/time-test.gold-O2 |   4 +-
 tests/type_propagation/gold/try-test.gold     |  22 +-
 tests/type_propagation/gold/try-test.gold-O2  |  22 +-
 .../type_propagation/gold/typecheck-test.gold |  20 +-
 .../gold/typecheck-test.gold-O2               |  18 +-
 38 files changed, 783 insertions(+), 783 deletions(-)

diff --git a/tests/type_propagation/gold/array-do-test.gold b/tests/type_propagation/gold/array-do-test.gold
index eaf2e7dc2..dd4e3676f 100644
--- a/tests/type_propagation/gold/array-do-test.gold
+++ b/tests/type_propagation/gold/array-do-test.gold
@@ -6,16 +6,16 @@ main tests/type_propagation/array-do-test.toit
  12[015] - load local 1
  13[038] - load block 1
  15[058] - invoke virtual do // [{List_}, [block]] -> {Null_}
- 19[089] - return null S3 0
+ 19[091] - return null S3 0
 
 [block] in main tests/type_propagation/array-do-test.toit
  - argument 0: [block]
  - argument 1: {*}
   0[016] - load local 2
   1[053] - invoke static id tests/type_propagation/array-do-test.toit // [{*}] -> {*}
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 id tests/type_propagation/array-do-test.toit
  - argument 0: {*}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/array-do-test.gold-O2 b/tests/type_propagation/gold/array-do-test.gold-O2
index eaf2e7dc2..dd4e3676f 100644
--- a/tests/type_propagation/gold/array-do-test.gold-O2
+++ b/tests/type_propagation/gold/array-do-test.gold-O2
@@ -6,16 +6,16 @@ main tests/type_propagation/array-do-test.toit
  12[015] - load local 1
  13[038] - load block 1
  15[058] - invoke virtual do // [{List_}, [block]] -> {Null_}
- 19[089] - return null S3 0
+ 19[091] - return null S3 0
 
 [block] in main tests/type_propagation/array-do-test.toit
  - argument 0: [block]
  - argument 1: {*}
   0[016] - load local 2
   1[053] - invoke static id tests/type_propagation/array-do-test.toit // [{*}] -> {*}
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 id tests/type_propagation/array-do-test.toit
  - argument 0: {*}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/block-test.gold b/tests/type_propagation/gold/block-test.gold
index ff37d55aa..f12749a79 100644
--- a/tests/type_propagation/gold/block-test.gold
+++ b/tests/type_propagation/gold/block-test.gold
@@ -16,7 +16,7 @@ main tests/type_propagation/block-test.toit
  28[053] - invoke static test-recursion tests/type_propagation/block-test.toit // {Null_}
  31[041] - pop 1
  32[053] - invoke static test-dead tests/type_propagation/block-test.toit // {Null_}
- 35[089] - return null S1 0
+ 35[091] - return null S1 0
 
 test-simple tests/type_propagation/block-test.toit
   0[023] - load smi 0
@@ -27,7 +27,7 @@ test-simple tests/type_propagation/block-test.toit
  13[041] - pop 1
  14[002] - pop, load local S0
  16[053] - invoke static id tests/type_propagation/block-test.toit // [{LargeInteger_|SmallInteger_}] -> {LargeInteger_|SmallInteger_}
- 19[089] - return null S2 0
+ 19[091] - return null S2 0
 
 [block] in test-simple tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -37,7 +37,7 @@ test-simple tests/type_propagation/block-test.toit
   4[025] - load smi 1
   5[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   6[006] - store outer S1
-  8[088] - return S1 1
+  8[090] - return S1 1
 
 test-invokes tests/type_propagation/block-test.toit
   0[029] - load method [block] in test-invokes tests/type_propagation/block-test.toit
@@ -58,24 +58,24 @@ test-invokes tests/type_propagation/block-test.toit
  45[020] - load literal true
  47[038] - load block 1
  49[053] - invoke static invoke tests/type_propagation/block-test.toit // [{True_}, [block]] -> {True_}
- 52[089] - return null S2 0
+ 52[091] - return null S2 0
 
 [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 42
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
  - argument 1: {String_}
   0[016] - load local 2
-  1[088] - return S1 2
+  1[090] - return S1 2
 
 [block] in [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
  - argument 1: {SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 2
+  1[090] - return S1 2
 
 [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -85,13 +85,13 @@ test-invokes tests/type_propagation/block-test.toit
   6[038] - load block 1
   8[053] - invoke static invoke tests/type_propagation/block-test.toit // [{SmallInteger_}, [block]] -> {SmallInteger_}
  11[004] - store local, pop S1
- 13[088] - return S1 2
+ 13[090] - return S1 2
 
 [block] in [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
  - argument 1: {True_}
   0[016] - load local 2
-  1[088] - return S1 2
+  1[090] - return S1 2
 
 [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -101,7 +101,7 @@ test-invokes tests/type_propagation/block-test.toit
   6[038] - load block 1
   8[053] - invoke static invoke tests/type_propagation/block-test.toit // [{True_}, [block]] -> {True_}
  11[004] - store local, pop S1
- 13[088] - return S1 2
+ 13[090] - return S1 2
 
 test-nesting tests/type_propagation/block-test.toit
   0[022] - load null
@@ -119,7 +119,7 @@ test-nesting tests/type_propagation/block-test.toit
  29[041] - pop 1
  30[002] - pop, load local S0
  32[053] - invoke static id tests/type_propagation/block-test.toit // [{Null_|True_|float}] -> {Null_|True_|float}
- 35[089] - return null S3 0
+ 35[091] - return null S3 0
 
 [block] in test-nesting tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -137,7 +137,7 @@ test-nesting tests/type_propagation/block-test.toit
  21[016] - load local 2
  22[005] - load outer S1 // {String_|SmallInteger_}
  24[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
- 27[088] - return S1 1
+ 27[090] - return S1 1
 
 [block] in test-nesting tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -148,7 +148,7 @@ test-nesting tests/type_propagation/block-test.toit
  11[002] - pop, load local S2
  13[005] - load outer S1 // {Null_|True_|float}
  15[053] - invoke static id tests/type_propagation/block-test.toit // [{Null_|True_|float}] -> {Null_|True_|float}
- 18[088] - return S1 1
+ 18[090] - return S1 1
 
 [block] in [block] in test-nesting tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -169,17 +169,17 @@ test-nesting tests/type_propagation/block-test.toit
  26[005] - load outer S3 // [block]
  28[005] - load outer S1 // {True_|float}
  30[053] - invoke static id tests/type_propagation/block-test.toit // [{True_|float}] -> {True_|float}
- 33[088] - return S1 1
+ 33[090] - return S1 1
 
 test-catch tests/type_propagation/block-test.toit
   0[022] - load null
   1[029] - load method [block] in test-catch tests/type_propagation/block-test.toit
-  6[094] - link try 0
+  6[096] - link try 0
   8[038] - load block 4
  10[055] - invoke block S1 // [[block]] -> {False_}
  12[041] - pop 1
- 13[095] - unlink try 0
- 15[096] - unwind
+ 13[097] - unlink try 0
+ 15[098] - unwind
  16[041] - pop 1
  17[022] - load null
  18[029] - load method [block] in test-catch tests/type_propagation/block-test.toit
@@ -200,14 +200,14 @@ test-catch tests/type_propagation/block-test.toit
  50[041] - pop 1
  51[002] - pop, load local S0
  53[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|Null_|float}] -> {String_|Null_|float}
- 56[089] - return null S4 0
+ 56[091] - return null S4 0
 
 [block] in test-catch tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[020] - load literal false
   3[006] - store outer S1
-  5[088] - return S1 1
+  5[090] - return S1 1
 
 [block] in test-catch tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -217,7 +217,7 @@ test-catch tests/type_propagation/block-test.toit
   5[041] - pop 1
   6[020] - load literal woops
   8[053] - invoke static throw <sdk>/core/exceptions.toit // [{String_}] -> {}
- 11[088] - return S1 1
+ 11[090] - return S1 1
 
 [block] in test-catch tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -229,7 +229,7 @@ test-catch tests/type_propagation/block-test.toit
   9[002] - pop, load local S2
  11[020] - load literal 3.2999999999999998224
  13[006] - store outer S1
- 15[088] - return S1 1
+ 15[090] - return S1 1
 
 test-too-few-arguments tests/type_propagation/block-test.toit
   0[029] - load method [block] in test-too-few-arguments tests/type_propagation/block-test.toit
@@ -237,7 +237,7 @@ test-too-few-arguments tests/type_propagation/block-test.toit
   7[022] - load null
   8[022] - load null
   9[053] - invoke static catch <sdk>/core/exceptions.toit // [[block], {Null_}, {Null_}] -> {*}
- 12[089] - return null S2 0
+ 12[091] - return null S2 0
 
 [block] in test-too-few-arguments tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -247,7 +247,7 @@ test-too-few-arguments tests/type_propagation/block-test.toit
  10[040] - pop 2
  12[026] - load smi 42
  14[053] - invoke static id tests/type_propagation/block-test.toit
- 17[088] - return S1 1
+ 17[090] - return S1 1
 
 test-modify-outer tests/type_propagation/block-test.toit
   0[026] - load smi 42
@@ -261,7 +261,7 @@ test-modify-outer tests/type_propagation/block-test.toit
  19[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
  22[002] - pop, load local S0
  24[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
- 27[089] - return null S3 0
+ 27[091] - return null S3 0
 
 [block] in test-modify-outer tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -272,7 +272,7 @@ test-modify-outer tests/type_propagation/block-test.toit
   6[002] - pop, load local S2
   8[020] - load literal hest
  10[006] - store outer S2
- 12[088] - return S1 1
+ 12[090] - return S1 1
 
 test-modify-outer-nested tests/type_propagation/block-test.toit
   0[026] - load smi 42
@@ -286,7 +286,7 @@ test-modify-outer-nested tests/type_propagation/block-test.toit
  19[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
  22[002] - pop, load local S0
  24[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
- 27[089] - return null S3 0
+ 27[091] - return null S3 0
 
 [block] in test-modify-outer-nested tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -301,7 +301,7 @@ test-modify-outer-nested tests/type_propagation/block-test.toit
  21[002] - pop, load local S2
  23[005] - load outer S1 // {String_|SmallInteger_}
  25[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
- 28[088] - return S1 1
+ 28[090] - return S1 1
 
 [block] in [block] in test-modify-outer-nested tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -315,7 +315,7 @@ test-modify-outer-nested tests/type_propagation/block-test.toit
  12[005] - load outer S3 // [block]
  14[020] - load literal hest
  16[006] - store outer S2
- 18[088] - return S1 1
+ 18[090] - return S1 1
 
 test-recursion tests/type_propagation/block-test.toit
   0[029] - load method [block] in test-recursion tests/type_propagation/block-test.toit
@@ -349,47 +349,47 @@ test-recursion tests/type_propagation/block-test.toit
  84[029] - load method [block] in test-recursion tests/type_propagation/block-test.toit
  89[038] - load block 0
  91[053] - invoke static recursive-a-call tests/type_propagation/block-test.toit // [[block]] -> {String_}
- 94[089] - return null S2 0
+ 94[091] - return null S2 0
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 42
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[020] - load literal false
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 87
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[020] - load literal true
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 42
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[020] - load literal hest
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 87
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[020] - load literal fisk
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 test-dead tests/type_propagation/block-test.toit
   0[029] - load method [block] in test-dead tests/type_propagation/block-test.toit
@@ -403,7 +403,7 @@ test-dead tests/type_propagation/block-test.toit
  24[029] - load method [block] in test-dead tests/type_propagation/block-test.toit
  29[038] - load block 0
  31[053] - invoke static ignore tests/type_propagation/block-test.toit // [[block]] -> {Null_}
- 34[089] - return null S2 0
+ 34[091] - return null S2 0
 
 recursive-null tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -413,15 +413,15 @@ recursive-null tests/type_propagation/block-test.toit
  11[038] - load block 0
  13[053] - invoke static recursive-null tests/type_propagation/block-test.toit // [[block]] -> {Null_}
  16[004] - store local, pop S1
- 18[088] - return S1 1
+ 18[090] - return S1 1
  21[016] - load local 2
  22[055] - invoke block S1 // [[block]] -> {Null_|False_|SmallInteger_}
- 24[088] - return S1 1
+ 24[090] - return S1 1
 
 [block] in recursive-null tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 recursive-call tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -429,10 +429,10 @@ recursive-call tests/type_propagation/block-test.toit
   3[082] - branch if false T13
   6[016] - load local 2
   7[053] - invoke static recursive-call tests/type_propagation/block-test.toit // [[block]] -> {True_|SmallInteger_}
- 10[088] - return S1 1
+ 10[090] - return S1 1
  13[016] - load local 2
  14[055] - invoke block S1 // [[block]] -> {True_|SmallInteger_}
- 16[088] - return S1 1
+ 16[090] - return S1 1
 
 recursive-a-null tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -442,10 +442,10 @@ recursive-a-null tests/type_propagation/block-test.toit
  11[038] - load block 0
  13[053] - invoke static recursive-b-null tests/type_propagation/block-test.toit // [[block]] -> {Null_}
  16[004] - store local, pop S1
- 18[088] - return S1 1
+ 18[090] - return S1 1
  21[016] - load local 2
  22[055] - invoke block S1 // [[block]] -> {String_|Null_|SmallInteger_}
- 24[088] - return S1 1
+ 24[090] - return S1 1
 
 recursive-b-null tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -453,12 +453,12 @@ recursive-b-null tests/type_propagation/block-test.toit
   5[038] - load block 0
   7[053] - invoke static recursive-a-null tests/type_propagation/block-test.toit // [[block]] -> {Null_}
  10[004] - store local, pop S1
- 12[088] - return S1 1
+ 12[090] - return S1 1
 
 [block] in recursive-b-null tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 recursive-a-call tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -466,16 +466,16 @@ recursive-a-call tests/type_propagation/block-test.toit
   3[082] - branch if false T13
   6[016] - load local 2
   7[053] - invoke static recursive-b-call tests/type_propagation/block-test.toit // [[block]] -> {String_|SmallInteger_}
- 10[088] - return S1 1
+ 10[090] - return S1 1
  13[016] - load local 2
  14[055] - invoke block S1 // [[block]] -> {String_|SmallInteger_}
- 16[088] - return S1 1
+ 16[090] - return S1 1
 
 recursive-b-call tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[053] - invoke static recursive-a-call tests/type_propagation/block-test.toit // [[block]] -> {String_|SmallInteger_}
-  4[088] - return S1 1
+  4[090] - return S1 1
 
 maybe-throw tests/type_propagation/block-test.toit
   0[053] - invoke static pick tests/type_propagation/block-test.toit // {True_|False_}
@@ -483,29 +483,29 @@ maybe-throw tests/type_propagation/block-test.toit
   6[020] - load literal woops
   8[053] - invoke static throw <sdk>/core/exceptions.toit // [{String_}] -> {}
  11[041] - pop 1
- 12[089] - return null S0 0
+ 12[091] - return null S0 0
 
 id tests/type_propagation/block-test.toit
  - argument 0: {String_|Null_|True_|float|LargeInteger_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 ignore tests/type_propagation/block-test.toit
  - argument 0: [block]
-  0[089] - return null S0 1
+  0[091] - return null S0 1
 
 pick tests/type_propagation/block-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 invoke tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {String_|Null_|True_|float|SmallInteger_}
-  3[088] - return S1 1
+  3[090] - return S1 1
 
 invoke tests/type_propagation/block-test.toit
  - argument 0: {String_|True_|SmallInteger_}
@@ -513,4 +513,4 @@ invoke tests/type_propagation/block-test.toit
   0[016] - load local 2
   1[018] - load local 4
   2[055] - invoke block S2 // [[block], {String_|True_|SmallInteger_}] -> {String_|True_|SmallInteger_}
-  4[088] - return S1 2
+  4[090] - return S1 2
diff --git a/tests/type_propagation/gold/block-test.gold-O2 b/tests/type_propagation/gold/block-test.gold-O2
index 88ef72d6e..865d34459 100644
--- a/tests/type_propagation/gold/block-test.gold-O2
+++ b/tests/type_propagation/gold/block-test.gold-O2
@@ -16,7 +16,7 @@ main tests/type_propagation/block-test.toit
  28[053] - invoke static test-recursion tests/type_propagation/block-test.toit // {Null_}
  31[041] - pop 1
  32[053] - invoke static test-dead tests/type_propagation/block-test.toit // {Null_}
- 35[089] - return null S1 0
+ 35[091] - return null S1 0
 
 test-simple tests/type_propagation/block-test.toit
   0[023] - load smi 0
@@ -27,7 +27,7 @@ test-simple tests/type_propagation/block-test.toit
  13[041] - pop 1
  14[002] - pop, load local S0
  16[053] - invoke static id tests/type_propagation/block-test.toit // [{LargeInteger_|SmallInteger_}] -> {LargeInteger_|SmallInteger_}
- 19[089] - return null S2 0
+ 19[091] - return null S2 0
 
 [block] in test-simple tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -37,7 +37,7 @@ test-simple tests/type_propagation/block-test.toit
   4[025] - load smi 1
   5[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   6[006] - store outer S1
-  8[088] - return S1 1
+  8[090] - return S1 1
 
 test-invokes tests/type_propagation/block-test.toit
   0[029] - load method [block] in test-invokes tests/type_propagation/block-test.toit
@@ -58,24 +58,24 @@ test-invokes tests/type_propagation/block-test.toit
  45[020] - load literal true
  47[038] - load block 1
  49[053] - invoke static invoke tests/type_propagation/block-test.toit // [{True_}, [block]] -> {True_}
- 52[089] - return null S2 0
+ 52[091] - return null S2 0
 
 [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 42
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
  - argument 1: {String_}
   0[016] - load local 2
-  1[088] - return S1 2
+  1[090] - return S1 2
 
 [block] in [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
  - argument 1: {SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 2
+  1[090] - return S1 2
 
 [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -85,13 +85,13 @@ test-invokes tests/type_propagation/block-test.toit
   6[038] - load block 1
   8[053] - invoke static invoke tests/type_propagation/block-test.toit // [{SmallInteger_}, [block]] -> {SmallInteger_}
  11[004] - store local, pop S1
- 13[088] - return S1 2
+ 13[090] - return S1 2
 
 [block] in [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
  - argument 1: {True_}
   0[016] - load local 2
-  1[088] - return S1 2
+  1[090] - return S1 2
 
 [block] in test-invokes tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -101,7 +101,7 @@ test-invokes tests/type_propagation/block-test.toit
   6[038] - load block 1
   8[053] - invoke static invoke tests/type_propagation/block-test.toit // [{True_}, [block]] -> {True_}
  11[004] - store local, pop S1
- 13[088] - return S1 2
+ 13[090] - return S1 2
 
 test-nesting tests/type_propagation/block-test.toit
   0[022] - load null
@@ -119,7 +119,7 @@ test-nesting tests/type_propagation/block-test.toit
  29[041] - pop 1
  30[002] - pop, load local S0
  32[053] - invoke static id tests/type_propagation/block-test.toit // [{Null_|True_|float}] -> {Null_|True_|float}
- 35[089] - return null S3 0
+ 35[091] - return null S3 0
 
 [block] in test-nesting tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -137,7 +137,7 @@ test-nesting tests/type_propagation/block-test.toit
  21[016] - load local 2
  22[005] - load outer S1 // {String_|SmallInteger_}
  24[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
- 27[088] - return S1 1
+ 27[090] - return S1 1
 
 [block] in test-nesting tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -148,7 +148,7 @@ test-nesting tests/type_propagation/block-test.toit
  11[002] - pop, load local S2
  13[005] - load outer S1 // {Null_|True_|float}
  15[053] - invoke static id tests/type_propagation/block-test.toit // [{Null_|True_|float}] -> {Null_|True_|float}
- 18[088] - return S1 1
+ 18[090] - return S1 1
 
 [block] in [block] in test-nesting tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -169,17 +169,17 @@ test-nesting tests/type_propagation/block-test.toit
  26[005] - load outer S3 // [block]
  28[005] - load outer S1 // {True_|float}
  30[053] - invoke static id tests/type_propagation/block-test.toit // [{True_|float}] -> {True_|float}
- 33[088] - return S1 1
+ 33[090] - return S1 1
 
 test-catch tests/type_propagation/block-test.toit
   0[022] - load null
   1[029] - load method [block] in test-catch tests/type_propagation/block-test.toit
-  6[094] - link try 0
+  6[096] - link try 0
   8[038] - load block 4
  10[055] - invoke block S1 // [[block]] -> {False_}
  12[041] - pop 1
- 13[095] - unlink try 0
- 15[096] - unwind
+ 13[097] - unlink try 0
+ 15[098] - unwind
  16[041] - pop 1
  17[022] - load null
  18[029] - load method [block] in test-catch tests/type_propagation/block-test.toit
@@ -200,14 +200,14 @@ test-catch tests/type_propagation/block-test.toit
  50[041] - pop 1
  51[002] - pop, load local S0
  53[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|Null_|float}] -> {String_|Null_|float}
- 56[089] - return null S4 0
+ 56[091] - return null S4 0
 
 [block] in test-catch tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[020] - load literal false
   3[006] - store outer S1
-  5[088] - return S1 1
+  5[090] - return S1 1
 
 [block] in test-catch tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -217,7 +217,7 @@ test-catch tests/type_propagation/block-test.toit
   5[041] - pop 1
   6[020] - load literal woops
   8[053] - invoke static throw <sdk>/core/exceptions.toit // [{String_}] -> {}
- 11[088] - return S1 1
+ 11[090] - return S1 1
 
 [block] in test-catch tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -229,7 +229,7 @@ test-catch tests/type_propagation/block-test.toit
   9[002] - pop, load local S2
  11[020] - load literal 3.2999999999999998224
  13[006] - store outer S1
- 15[088] - return S1 1
+ 15[090] - return S1 1
 
 test-too-few-arguments tests/type_propagation/block-test.toit
   0[029] - load method [block] in test-too-few-arguments tests/type_propagation/block-test.toit
@@ -237,7 +237,7 @@ test-too-few-arguments tests/type_propagation/block-test.toit
   7[022] - load null
   8[022] - load null
   9[053] - invoke static catch <sdk>/core/exceptions.toit // [[block], {Null_}, {Null_}] -> {*}
- 12[089] - return null S2 0
+ 12[091] - return null S2 0
 
 [block] in test-too-few-arguments tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -245,7 +245,7 @@ test-too-few-arguments tests/type_propagation/block-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/block-test.toit // [[block]] -> {}
  10[004] - store local, pop S1
- 12[088] - return S1 1
+ 12[090] - return S1 1
 
 test-modify-outer tests/type_propagation/block-test.toit
   0[026] - load smi 42
@@ -259,7 +259,7 @@ test-modify-outer tests/type_propagation/block-test.toit
  19[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
  22[002] - pop, load local S0
  24[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
- 27[089] - return null S3 0
+ 27[091] - return null S3 0
 
 [block] in test-modify-outer tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -270,7 +270,7 @@ test-modify-outer tests/type_propagation/block-test.toit
   6[002] - pop, load local S2
   8[020] - load literal hest
  10[006] - store outer S2
- 12[088] - return S1 1
+ 12[090] - return S1 1
 
 test-modify-outer-nested tests/type_propagation/block-test.toit
   0[026] - load smi 42
@@ -284,7 +284,7 @@ test-modify-outer-nested tests/type_propagation/block-test.toit
  19[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
  22[002] - pop, load local S0
  24[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
- 27[089] - return null S3 0
+ 27[091] - return null S3 0
 
 [block] in test-modify-outer-nested tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -299,7 +299,7 @@ test-modify-outer-nested tests/type_propagation/block-test.toit
  21[002] - pop, load local S2
  23[005] - load outer S1 // {String_|SmallInteger_}
  25[053] - invoke static id tests/type_propagation/block-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
- 28[088] - return S1 1
+ 28[090] - return S1 1
 
 [block] in [block] in test-modify-outer-nested tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -313,7 +313,7 @@ test-modify-outer-nested tests/type_propagation/block-test.toit
  12[005] - load outer S3 // [block]
  14[020] - load literal hest
  16[006] - store outer S2
- 18[088] - return S1 1
+ 18[090] - return S1 1
 
 test-recursion tests/type_propagation/block-test.toit
   0[029] - load method [block] in test-recursion tests/type_propagation/block-test.toit
@@ -347,47 +347,47 @@ test-recursion tests/type_propagation/block-test.toit
  84[029] - load method [block] in test-recursion tests/type_propagation/block-test.toit
  89[038] - load block 0
  91[053] - invoke static recursive-a-call tests/type_propagation/block-test.toit // [[block]] -> {String_}
- 94[089] - return null S2 0
+ 94[091] - return null S2 0
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 42
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[020] - load literal false
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 87
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[020] - load literal true
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 42
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[020] - load literal hest
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[026] - load smi 87
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 [block] in test-recursion tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[020] - load literal fisk
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 test-dead tests/type_propagation/block-test.toit
   0[029] - load method [block] in test-dead tests/type_propagation/block-test.toit
@@ -401,7 +401,7 @@ test-dead tests/type_propagation/block-test.toit
  24[029] - load method [block] in test-dead tests/type_propagation/block-test.toit
  29[038] - load block 0
  31[053] - invoke static ignore tests/type_propagation/block-test.toit // [[block]] -> {Null_}
- 34[089] - return null S2 0
+ 34[091] - return null S2 0
 
 recursive-null tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -411,15 +411,15 @@ recursive-null tests/type_propagation/block-test.toit
  11[038] - load block 0
  13[053] - invoke static recursive-null tests/type_propagation/block-test.toit // [[block]] -> {Null_}
  16[004] - store local, pop S1
- 18[088] - return S1 1
+ 18[090] - return S1 1
  21[016] - load local 2
  22[055] - invoke block S1 // [[block]] -> {Null_|False_|SmallInteger_}
- 24[088] - return S1 1
+ 24[090] - return S1 1
 
 [block] in recursive-null tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 recursive-call tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -427,10 +427,10 @@ recursive-call tests/type_propagation/block-test.toit
   3[082] - branch if false T13
   6[016] - load local 2
   7[053] - invoke static recursive-call tests/type_propagation/block-test.toit // [[block]] -> {True_|SmallInteger_}
- 10[088] - return S1 1
+ 10[090] - return S1 1
  13[016] - load local 2
  14[055] - invoke block S1 // [[block]] -> {True_|SmallInteger_}
- 16[088] - return S1 1
+ 16[090] - return S1 1
 
 recursive-a-null tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -440,10 +440,10 @@ recursive-a-null tests/type_propagation/block-test.toit
  11[038] - load block 0
  13[053] - invoke static recursive-b-null tests/type_propagation/block-test.toit // [[block]] -> {Null_}
  16[004] - store local, pop S1
- 18[088] - return S1 1
+ 18[090] - return S1 1
  21[016] - load local 2
  22[055] - invoke block S1 // [[block]] -> {String_|Null_|SmallInteger_}
- 24[088] - return S1 1
+ 24[090] - return S1 1
 
 recursive-b-null tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -451,12 +451,12 @@ recursive-b-null tests/type_propagation/block-test.toit
   5[038] - load block 0
   7[053] - invoke static recursive-a-null tests/type_propagation/block-test.toit // [[block]] -> {Null_}
  10[004] - store local, pop S1
- 12[088] - return S1 1
+ 12[090] - return S1 1
 
 [block] in recursive-b-null tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 recursive-a-call tests/type_propagation/block-test.toit
  - argument 0: [block]
@@ -464,16 +464,16 @@ recursive-a-call tests/type_propagation/block-test.toit
   3[082] - branch if false T13
   6[016] - load local 2
   7[053] - invoke static recursive-b-call tests/type_propagation/block-test.toit // [[block]] -> {String_|SmallInteger_}
- 10[088] - return S1 1
+ 10[090] - return S1 1
  13[016] - load local 2
  14[055] - invoke block S1 // [[block]] -> {String_|SmallInteger_}
- 16[088] - return S1 1
+ 16[090] - return S1 1
 
 recursive-b-call tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[053] - invoke static recursive-a-call tests/type_propagation/block-test.toit // [[block]] -> {String_|SmallInteger_}
-  4[088] - return S1 1
+  4[090] - return S1 1
 
 maybe-throw tests/type_propagation/block-test.toit
   0[053] - invoke static pick tests/type_propagation/block-test.toit // {True_|False_}
@@ -481,29 +481,29 @@ maybe-throw tests/type_propagation/block-test.toit
   6[020] - load literal woops
   8[053] - invoke static throw <sdk>/core/exceptions.toit // [{String_}] -> {}
  11[041] - pop 1
- 12[089] - return null S0 0
+ 12[091] - return null S0 0
 
 id tests/type_propagation/block-test.toit
  - argument 0: {String_|Null_|True_|float|LargeInteger_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 ignore tests/type_propagation/block-test.toit
  - argument 0: [block]
-  0[089] - return null S0 1
+  0[091] - return null S0 1
 
 pick tests/type_propagation/block-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 invoke tests/type_propagation/block-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {String_|Null_|True_|float|SmallInteger_}
-  3[088] - return S1 1
+  3[090] - return S1 1
 
 invoke tests/type_propagation/block-test.toit
  - argument 0: {String_|True_|SmallInteger_}
@@ -511,4 +511,4 @@ invoke tests/type_propagation/block-test.toit
   0[016] - load local 2
   1[018] - load local 4
   2[055] - invoke block S2 // [[block], {String_|True_|SmallInteger_}] -> {String_|True_|SmallInteger_}
-  4[088] - return S1 2
+  4[090] - return S1 2
diff --git a/tests/type_propagation/gold/deltablue-test.gold b/tests/type_propagation/gold/deltablue-test.gold
index e735aad56..d95763af5 100644
--- a/tests/type_propagation/gold/deltablue-test.gold
+++ b/tests/type_propagation/gold/deltablue-test.gold
@@ -3,7 +3,7 @@ main tests/type_propagation/deltablue-test.toit
   5[026] - load smi 10
   7[038] - load block 1
   9[058] - invoke virtual repeat // [{SmallInteger_}, [block]] -> {Null_}
- 13[089] - return null S2 0
+ 13[091] - return null S2 0
 
 [block] in main tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -12,7 +12,7 @@ main tests/type_propagation/deltablue-test.toit
   5[041] - pop 1
   6[026] - load smi 50
   8[053] - invoke static projection-test tests/type_propagation/deltablue-test.toit // [{SmallInteger_}] -> {Null_}
- 11[088] - return S1 1
+ 11[090] - return S1 1
 
 Strength tests/type_propagation/deltablue-test.toit
  - argument 0: {Strength}
@@ -27,12 +27,12 @@ Strength tests/type_propagation/deltablue-test.toit
   8[048] - as class StringSlice_(11 - 13) // {True_}
  10[013] - store field, pop 1
  12[018] - load local 4
- 13[088] - return S1 3
+ 13[090] - return S1 3
 
 Strength.value tests/type_propagation/deltablue-test.toit
  - argument 0: {Strength}
   0[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Strength.next-weaker tests/type_propagation/deltablue-test.toit
  - argument 0: {Strength}
@@ -42,42 +42,42 @@ Strength.next-weaker tests/type_propagation/deltablue-test.toit
   4[082] - branch if false T14
   7[032] - load global var lazy G6 // {Strength}
   9[048] - as class Strength(47 - 48) // {True_}
- 11[088] - return S1 1
+ 11[090] - return S1 1
  14[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  16[025] - load smi 1
  17[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  18[082] - branch if false T28
  21[032] - load global var lazy G5 // {Strength}
  23[048] - as class Strength(47 - 48) // {True_}
- 25[088] - return S1 1
+ 25[090] - return S1 1
  28[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  30[026] - load smi 2
  32[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  33[082] - branch if false T43
  36[032] - load global var lazy G4 // {Strength}
  38[048] - as class Strength(47 - 48) // {True_}
- 40[088] - return S1 1
+ 40[090] - return S1 1
  43[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  45[026] - load smi 3
  47[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  48[082] - branch if false T58
  51[032] - load global var lazy G3 // {Strength}
  53[048] - as class Strength(47 - 48) // {True_}
- 55[088] - return S1 1
+ 55[090] - return S1 1
  58[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  60[026] - load smi 4
  62[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  63[082] - branch if false T73
  66[032] - load global var lazy G2 // {Strength}
  68[048] - as class Strength(47 - 48) // {True_}
- 70[088] - return S1 1
+ 70[090] - return S1 1
  73[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  75[026] - load smi 5
  77[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  78[082] - branch if false T88
  81[032] - load global var lazy G1 // {Strength}
  83[048] - as class Strength(47 - 48) // {True_}
- 85[088] - return S1 1
+ 85[090] - return S1 1
  88[053] - invoke static unreachable <sdk>/core/exceptions.toit // {}
  91[041] - pop 1
 
@@ -86,49 +86,49 @@ REQUIRED tests/type_propagation/deltablue-test.toit
   2[023] - load smi 0
   3[020] - load literal required
   5[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 STRONG-REFERRED tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[025] - load smi 1
   3[020] - load literal strongPreferred
   5[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 PREFERRED tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 2
   4[020] - load literal preferred
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 STRONG-DEFAULT tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 3
   4[020] - load literal strongDefault
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 NORMAL tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 4
   4[020] - load literal normal
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 WEAK-DEFAULT tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 5
   4[020] - load literal weakDefault
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 WEAKEST tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 6
   4[020] - load literal weakest
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 stronger tests/type_propagation/deltablue-test.toit
  - argument 0: {Null_|Strength}
@@ -139,7 +139,7 @@ stronger tests/type_propagation/deltablue-test.toit
   6[009] - load field local 3 // [{Strength}] -> {Null_|SmallInteger_}
   8[063] - invoke lt // [{Null_|SmallInteger_}, {Null_|SmallInteger_}] -> {True_|False_}
   9[048] - as class True_(18 - 20) // {True_}
- 11[088] - return S1 2
+ 11[090] - return S1 2
 
 weaker tests/type_propagation/deltablue-test.toit
  - argument 0: {Null_|Strength}
@@ -150,7 +150,7 @@ weaker tests/type_propagation/deltablue-test.toit
   6[009] - load field local 3 // [{Strength}] -> {Null_|SmallInteger_}
   8[064] - invoke gt // [{Null_|SmallInteger_}, {Null_|SmallInteger_}] -> {True_|False_}
   9[048] - as class True_(18 - 20) // {True_}
- 11[088] - return S1 2
+ 11[090] - return S1 2
 
 weakest tests/type_propagation/deltablue-test.toit
  - argument 0: {Null_|Strength}
@@ -165,12 +165,12 @@ weakest tests/type_propagation/deltablue-test.toit
  13[080] - branch T17
  16[016] - load local 2
  17[048] - as class Strength(47 - 48) // {True_}
- 19[088] - return S1 2
+ 19[090] - return S1 2
 
 Constraint.strength tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
   0[009] - load field local 2 // [{EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_|Strength}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
@@ -180,7 +180,7 @@ Constraint tests/type_propagation/deltablue-test.toit
   2[048] - as class Strength(47 - 48) // {True_}
   4[013] - store field, pop 0
   6[017] - load local 3
-  7[088] - return S1 2
+  7[090] - return S1 2
 
 Constraint.add-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
@@ -190,7 +190,7 @@ Constraint.add-constraint tests/type_propagation/deltablue-test.toit
   6[030] - load global var G7 // {Null_|Planner}
   8[017] - load local 3
   9[058] - invoke virtual incremental-add // [{Null_|Planner}, {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_}
- 13[089] - return null S1 1
+ 13[091] - return null S1 1
 
 Constraint.satisfy tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
@@ -211,7 +211,7 @@ Constraint.satisfy tests/type_propagation/deltablue-test.toit
  29[041] - pop 1
  30[022] - load null
  31[048] - as class EqualityConstraint?(43 - 47) // {True_}
- 33[088] - return S1 2
+ 33[090] - return S1 2
  36[017] - load local 3
  37[017] - load local 3
  38[058] - invoke virtual mark-inputs // [{EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}, {LargeInteger_|SmallInteger_}] -> {Null_}
@@ -239,7 +239,7 @@ Constraint.satisfy tests/type_propagation/deltablue-test.toit
  86[013] - store field, pop 3
  88[014] - load local 0
  89[048] - as class EqualityConstraint?(43 - 47) // {True_}
- 91[088] - return S3 2
+ 91[090] - return S3 2
 
 Constraint.destroy-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint}
@@ -252,18 +252,18 @@ Constraint.destroy-constraint tests/type_propagation/deltablue-test.toit
  14[041] - pop 1
  15[016] - load local 2
  16[058] - invoke virtual remove-from-graph // [{EditConstraint}] -> {Null_}
- 20[089] - return null S1 1
+ 20[091] - return null S1 1
 
 Constraint.is-input tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|StayConstraint}
   0[020] - load literal false
   2[048] - as class True_(18 - 20) // {True_}
-  4[088] - return S1 1
+  4[090] - return S1 1
 
 UnaryConstraint.is-satisfied tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
   0[009] - load field local 34 // [{EditConstraint|StayConstraint}] -> {Null_|True_|False_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 UnaryConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -284,7 +284,7 @@ UnaryConstraint tests/type_propagation/deltablue-test.toit
  20[002] - pop, load local S4
  22[053] - invoke static Constraint.add-constraint tests/type_propagation/deltablue-test.toit // [{EditConstraint|StayConstraint}] -> {Null_}
  25[002] - pop, load local S4
- 27[088] - return S1 3
+ 27[090] - return S1 3
 
 UnaryConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -295,7 +295,7 @@ UnaryConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
   8[020] - load literal false
  10[048] - as class True_(18 - 20) // {True_}
  12[013] - store field, pop 2
- 14[089] - return null S0 1
+ 14[091] - return null S0 1
 
 UnaryConstraint.choose-method tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -318,18 +318,18 @@ UnaryConstraint.choose-method tests/type_propagation/deltablue-test.toit
  29[053] - invoke static stronger tests/type_propagation/deltablue-test.toit // [{Null_|Strength}, {Null_|Strength}] -> {True_|False_}
  32[048] - as class True_(18 - 20) // {True_}
  34[013] - store field, pop 2
- 36[089] - return null S0 2
+ 36[091] - return null S0 2
 
 UnaryConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
  - argument 1: {LargeInteger_|SmallInteger_}
   0[052] - load local, as class, pop 2 - LargeInteger_(22 - 24) // {True_}
-  2[089] - return null S0 2
+  2[091] - return null S0 2
 
 UnaryConstraint.output tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
   0[009] - load field local 18 // [{EditConstraint|StayConstraint}] -> {Null_|Variable}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 UnaryConstraint.recalculate tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -350,7 +350,7 @@ UnaryConstraint.recalculate tests/type_propagation/deltablue-test.toit
  32[016] - load local 2
  33[058] - invoke virtual execute // [{EditConstraint|StayConstraint}] -> {Null_}
  37[041] - pop 1
- 38[089] - return null S0 1
+ 38[091] - return null S0 1
 
 UnaryConstraint.mark-unsatisfied tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -358,7 +358,7 @@ UnaryConstraint.mark-unsatisfied tests/type_propagation/deltablue-test.toit
   1[020] - load literal false
   3[048] - as class True_(18 - 20) // {True_}
   5[013] - store field, pop 2
-  7[089] - return null S0 1
+  7[091] - return null S0 1
 
 UnaryConstraint.inputs-known tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -366,7 +366,7 @@ UnaryConstraint.inputs-known tests/type_propagation/deltablue-test.toit
   0[052] - load local, as class, pop 2 - LargeInteger_(22 - 24) // {True_}
   2[020] - load literal true
   4[048] - as class True_(18 - 20) // {True_}
-  6[088] - return S1 2
+  6[090] - return S1 2
 
 UnaryConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -377,7 +377,7 @@ UnaryConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
   8[020] - load literal false
  10[048] - as class True_(18 - 20) // {True_}
  12[013] - store field, pop 2
- 14[089] - return null S0 1
+ 14[091] - return null S0 1
 
 StayConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {StayConstraint}
@@ -390,11 +390,11 @@ StayConstraint tests/type_propagation/deltablue-test.toit
   6[018] - load local 4
   7[053] - invoke static UnaryConstraint tests/type_propagation/deltablue-test.toit // [{StayConstraint}, {Strength}, {Variable}] -> {StayConstraint}
  10[002] - pop, load local S4
- 12[088] - return S1 3
+ 12[090] - return S1 3
 
 StayConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {StayConstraint}
-  0[089] - return null S0 1
+  0[091] - return null S0 1
 
 EditConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint}
@@ -407,17 +407,17 @@ EditConstraint tests/type_propagation/deltablue-test.toit
   6[018] - load local 4
   7[053] - invoke static UnaryConstraint tests/type_propagation/deltablue-test.toit // [{EditConstraint}, {Strength}, {Variable}] -> {EditConstraint}
  10[002] - pop, load local S4
- 12[088] - return S1 3
+ 12[090] - return S1 3
 
 EditConstraint.is-input tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint}
   0[020] - load literal true
   2[048] - as class True_(18 - 20) // {True_}
-  4[088] - return S1 1
+  4[090] - return S1 1
 
 EditConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint}
-  0[089] - return null S0 1
+  0[091] - return null S0 1
 
 BinaryConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -443,7 +443,7 @@ BinaryConstraint tests/type_propagation/deltablue-test.toit
  25[002] - pop, load local S5
  27[053] - invoke static Constraint.add-constraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint|ScaleConstraint}] -> {Null_}
  30[002] - pop, load local S5
- 32[088] - return S1 4
+ 32[090] - return S1 4
 
 BinaryConstraint.choose-method tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -522,7 +522,7 @@ BinaryConstraint.choose-method tests/type_propagation/deltablue-test.toit
 137[026] - load smi 2
 139[048] - as class LargeInteger_(22 - 24) // {True_}
 141[013] - store field, pop 3
-143[089] - return null S0 2
+143[091] - return null S0 2
 
 BinaryConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -536,7 +536,7 @@ BinaryConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  14[025] - load smi 1
  15[048] - as class LargeInteger_(22 - 24) // {True_}
  17[013] - store field, pop 3
- 19[089] - return null S0 1
+ 19[091] - return null S0 1
 
 BinaryConstraint.is-satisfied tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -548,7 +548,7 @@ BinaryConstraint.is-satisfied tests/type_propagation/deltablue-test.toit
   9[080] - branch T14
  12[020] - load literal false
  14[048] - as class True_(18 - 20) // {True_}
- 16[088] - return S1 1
+ 16[090] - return S1 1
 
 BinaryConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -558,7 +558,7 @@ BinaryConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
   3[053] - invoke static BinaryConstraint.input tests/type_propagation/deltablue-test.toit // [{EqualityConstraint|ScaleConstraint}] -> {Variable}
   6[017] - load local 3
   7[013] - store field, pop 3
-  9[089] - return null S0 2
+  9[091] - return null S0 2
 
 BinaryConstraint.input tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -570,7 +570,7 @@ BinaryConstraint.input tests/type_propagation/deltablue-test.toit
  10[080] - branch T15
  13[009] - load field local 34 // [{EqualityConstraint|ScaleConstraint}] -> {Null_|Variable}
  15[048] - as class Variable(42 - 43) // {True_|False_}
- 17[088] - return S1 1
+ 17[090] - return S1 1
 
 BinaryConstraint.output tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -582,7 +582,7 @@ BinaryConstraint.output tests/type_propagation/deltablue-test.toit
  10[080] - branch T15
  13[009] - load field local 18 // [{EqualityConstraint|ScaleConstraint}] -> {Null_|Variable}
  15[048] - as class Variable(42 - 43) // {True_|False_}
- 17[088] - return S1 1
+ 17[090] - return S1 1
 
 BinaryConstraint.recalculate tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
@@ -603,7 +603,7 @@ BinaryConstraint.recalculate tests/type_propagation/deltablue-test.toit
  28[018] - load local 4
  29[058] - invoke virtual execute // [{EqualityConstraint}] -> {Null_}
  33[041] - pop 1
- 34[089] - return null S2 1
+ 34[091] - return null S2 1
 
 BinaryConstraint.mark-unsatisfied tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -611,7 +611,7 @@ BinaryConstraint.mark-unsatisfied tests/type_propagation/deltablue-test.toit
   1[025] - load smi 1
   2[048] - as class LargeInteger_(22 - 24) // {True_}
   4[013] - store field, pop 3
-  6[089] - return null S0 1
+  6[091] - return null S0 1
 
 BinaryConstraint.inputs-known tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -629,7 +629,7 @@ BinaryConstraint.inputs-known tests/type_propagation/deltablue-test.toit
  17[081] - branch if true T22
  20[010] - pop, load field local 32 // [{Variable}] -> {Null_|EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
  22[048] - as class True_(18 - 20) // {True_|False_}
- 24[088] - return S2 2
+ 24[090] - return S2 2
 
 BinaryConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -643,7 +643,7 @@ BinaryConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  14[025] - load smi 1
  15[048] - as class LargeInteger_(22 - 24) // {True_}
  17[013] - store field, pop 3
- 19[089] - return null S0 1
+ 19[091] - return null S0 1
 
 ScaleConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -669,7 +669,7 @@ ScaleConstraint tests/type_propagation/deltablue-test.toit
  26[000] - load local S7
  28[053] - invoke static BinaryConstraint tests/type_propagation/deltablue-test.toit // [{ScaleConstraint}, {Strength}, {Variable}, {Variable}] -> {ScaleConstraint}
  31[002] - pop, load local S7
- 33[088] - return S1 6
+ 33[090] - return S1 6
 
 ScaleConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -681,7 +681,7 @@ ScaleConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  10[010] - pop, load field local 82 // [{ScaleConstraint}] -> {Null_|Variable}
  12[017] - load local 3
  13[053] - invoke static Variable.add-constraint tests/type_propagation/deltablue-test.toit // [{Null_|Variable}, {ScaleConstraint}] -> {Null_}
- 16[089] - return null S1 1
+ 16[091] - return null S1 1
 
 ScaleConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -693,7 +693,7 @@ ScaleConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  10[010] - pop, load field local 82 // [{ScaleConstraint}] -> {Null_|Variable}
  12[017] - load local 3
  13[053] - invoke static Variable.remove-constraint tests/type_propagation/deltablue-test.toit // [{Null_|Variable}, {ScaleConstraint}] -> {Null_}
- 16[089] - return null S1 1
+ 16[091] - return null S1 1
 
 ScaleConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -707,7 +707,7 @@ ScaleConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
  11[018] - load local 4
  12[011] - store field 3
  14[013] - store field, pop 3
- 16[089] - return null S0 2
+ 16[091] - return null S0 2
 
 ScaleConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -738,7 +738,7 @@ ScaleConstraint.execute tests/type_propagation/deltablue-test.toit
  46[076] - invoke div // [{LargeInteger_|SmallInteger_}, {Null_|LargeInteger_|SmallInteger_}] -> {LargeInteger_|SmallInteger_}
  47[048] - as class LargeInteger_(22 - 24) // {True_}
  49[013] - store field, pop 1
- 51[089] - return null S0 1
+ 51[091] - return null S0 1
 
 ScaleConstraint.recalculate tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -767,7 +767,7 @@ ScaleConstraint.recalculate tests/type_propagation/deltablue-test.toit
  44[018] - load local 4
  45[053] - invoke static ScaleConstraint.execute tests/type_propagation/deltablue-test.toit // [{ScaleConstraint}] -> {Null_}
  48[041] - pop 1
- 49[089] - return null S2 1
+ 49[091] - return null S2 1
 
 EqualityConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
@@ -783,7 +783,7 @@ EqualityConstraint tests/type_propagation/deltablue-test.toit
   9[019] - load local 5
  10[053] - invoke static BinaryConstraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}, {Strength}, {Variable}, {Variable}] -> {EqualityConstraint}
  13[002] - pop, load local S5
- 15[088] - return S1 4
+ 15[090] - return S1 4
 
 EqualityConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
@@ -793,7 +793,7 @@ EqualityConstraint.execute tests/type_propagation/deltablue-test.toit
   5[053] - invoke static BinaryConstraint.input tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}] -> {Variable}
   8[007] - load field 1 // [{Variable}] -> {Null_|LargeInteger_|SmallInteger_}
  10[013] - store field, pop 1
- 12[089] - return null S0 1
+ 12[091] - return null S0 1
 
 Variable tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -825,12 +825,12 @@ Variable tests/type_propagation/deltablue-test.toit
  35[053] - invoke static create-list-literal-from-array_ <sdk>/core/collections.toit // [{LargeArray_|SmallArray_}] -> {List_}
  38[013] - store field, pop 6
  40[018] - load local 4
- 41[088] - return S1 3
+ 41[090] - return S1 3
 
 Variable.value tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
   0[009] - load field local 18 // [{Variable}] -> {Null_|LargeInteger_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Variable.value= tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -839,17 +839,17 @@ Variable.value= tests/type_propagation/deltablue-test.toit
   2[017] - load local 3
   3[017] - load local 3
   4[011] - store field 1
-  6[088] - return S1 2
+  6[090] - return S1 2
 
 Variable.determined-by tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
   0[009] - load field local 34 // [{Variable}] -> {Null_|EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Variable.mark tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
   0[009] - load field local 50 // [{Variable}] -> {Null_|LargeInteger_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Variable.mark= tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -857,12 +857,12 @@ Variable.mark= tests/type_propagation/deltablue-test.toit
   0[017] - load local 3
   1[017] - load local 3
   2[011] - store field 3
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 Variable.constraints tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
   0[009] - load field local 98 // [{Variable}] -> {Null_|List_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Variable.add-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -871,7 +871,7 @@ Variable.add-constraint tests/type_propagation/deltablue-test.toit
   2[009] - load field local 99 // [{Variable}] -> {Null_|List_}
   4[017] - load local 3
   5[058] - invoke virtual add // [{Null_|List_}, {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_}
-  9[089] - return null S1 2
+  9[091] - return null S1 2
 
 Variable.remove-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -891,7 +891,7 @@ Variable.remove-constraint tests/type_propagation/deltablue-test.toit
  27[017] - load local 3
  28[022] - load null
  29[013] - store field, pop 2
- 31[089] - return null S0 2
+ 31[091] - return null S0 2
 
 [block] in Variable.remove-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -904,7 +904,7 @@ Variable.remove-constraint tests/type_propagation/deltablue-test.toit
   8[020] - load literal true
  10[080] - branch T15
  13[020] - load literal false
- 15[088] - return S1 2
+ 15[090] - return S1 2
 
 Planner tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -912,7 +912,7 @@ Planner tests/type_propagation/deltablue-test.toit
   1[023] - load smi 0
   2[013] - store field, pop 0
   4[016] - load local 2
-  5[088] - return S1 1
+  5[090] - return S1 1
 
 Planner.incremental-add tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -929,8 +929,8 @@ Planner.incremental-add tests/type_propagation/deltablue-test.toit
  16[016] - load local 2
  17[058] - invoke virtual satisfy // [{Null_|EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}, {LargeInteger_|SmallInteger_}] -> {Null_|EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
  21[004] - store local, pop S1
- 23[083] - branch back T11
- 28[089] - return null S2 2
+ 23[084] - branch back T11
+ 28[091] - return null S2 2
 
 Planner.incremental-remove tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -959,8 +959,8 @@ Planner.incremental-remove tests/type_propagation/deltablue-test.toit
  50[062] - invoke eq // [{Strength}, {Strength}] -> {True_|False_}
  51[082] - branch if false T57
  54[080] - branch T62
- 57[083] - branch back T26
- 62[089] - return null S3 2
+ 57[084] - branch back T26
+ 62[091] - return null S3 2
 
 [block] in Planner.incremental-remove tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -976,7 +976,7 @@ Planner.incremental-remove tests/type_propagation/deltablue-test.toit
  14[005] - load outer S7 // {Planner}
  16[017] - load local 3
  17[053] - invoke static Planner.incremental-add tests/type_propagation/deltablue-test.toit // [{Planner}, {*}] -> {Null_}
- 20[088] - return S1 2
+ 20[090] - return S1 2
 
 Planner.new-mark tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -986,7 +986,7 @@ Planner.new-mark tests/type_propagation/deltablue-test.toit
   4[073] - invoke add // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[011] - store field 0
   7[048] - as class LargeInteger_(22 - 24) // {True_}
-  9[088] - return S1 1
+  9[090] - return S1 1
 
 Planner.make-plan tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -1026,9 +1026,9 @@ Planner.make-plan tests/type_propagation/deltablue-test.toit
  69[053] - invoke static Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit // [{Planner}, {Null_|Variable}, {List_}] -> {Null_}
  72[041] - pop 1
  73[041] - pop 1
- 74[083] - branch back T12
+ 74[084] - branch back T12
  79[015] - load local 1
- 80[088] - return S4 2
+ 80[090] - return S4 2
 
 Planner.extract-plan-from-constraints tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -1048,7 +1048,7 @@ Planner.extract-plan-from-constraints tests/type_propagation/deltablue-test.toit
  26[002] - pop, load local S4
  28[015] - load local 1
  29[053] - invoke static Planner.make-plan tests/type_propagation/deltablue-test.toit // [{Planner}, {List_}] -> {Plan}
- 32[088] - return S2 2
+ 32[090] - return S2 2
 
 [block] in Planner.extract-plan-from-constraints tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1064,7 +1064,7 @@ Planner.extract-plan-from-constraints tests/type_propagation/deltablue-test.toit
  18[005] - load outer S1 // {List_}
  20[017] - load local 3
  21[053] - invoke static List.add <sdk>/core/collections.toit // [{List_}, {*}] -> {Null_}
- 24[088] - return S1 2
+ 24[090] - return S1 2
 
 Planner.add-propagate tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -1092,7 +1092,7 @@ Planner.add-propagate tests/type_propagation/deltablue-test.toit
  43[041] - pop 1
  44[020] - load literal false
  46[048] - as class True_(18 - 20) // {True_}
- 48[088] - return S3 3
+ 48[090] - return S3 3
  51[014] - load local 0
  52[058] - invoke virtual recalculate // [{*}] -> {Null_}
  56[002] - pop, load local S6
@@ -1101,10 +1101,10 @@ Planner.add-propagate tests/type_propagation/deltablue-test.toit
  63[017] - load local 3
  64[053] - invoke static Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit // [{Planner}, {Null_|Variable}, {List_}] -> {Null_}
  67[040] - pop 2
- 69[083] - branch back T11
+ 69[084] - branch back T11
  74[020] - load literal true
  76[048] - as class True_(18 - 20) // {True_}
- 78[088] - return S2 3
+ 78[090] - return S2 3
 
 Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -1147,9 +1147,9 @@ Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  76[038] - load block 1
  78[058] - invoke virtual do // [{Null_|List_}, [block]] -> {Null_}
  82[040] - pop 4
- 84[083] - branch back T34
+ 84[084] - branch back T34
  89[015] - load local 1
- 90[088] - return S3 2
+ 90[090] - return S3 2
 
 [block] in Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1162,7 +1162,7 @@ Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  10[005] - load outer S3 // {List_}
  12[017] - load local 3
  13[053] - invoke static List.add <sdk>/core/collections.toit // [{List_}, {*}] -> {Null_}
- 16[088] - return S1 2
+ 16[090] - return S1 2
 
 [block] in Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1183,7 +1183,7 @@ Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  26[017] - load local 3
  27[058] - invoke virtual output // [{*}] -> {Null_|Variable}
  31[053] - invoke static List.add <sdk>/core/collections.toit // [{List_}, {Null_|Variable}] -> {Null_}
- 34[088] - return S1 2
+ 34[090] - return S1 2
 
 Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -1196,7 +1196,7 @@ Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit
  11[009] - load field local 101 // [{Variable}] -> {Null_|List_}
  13[038] - load block 1
  15[058] - invoke virtual do // [{Null_|List_}, [block]] -> {Null_}
- 19[089] - return null S3 3
+ 19[091] - return null S3 3
 
 [block] in Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1214,7 +1214,7 @@ Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit
  18[005] - load outer S4 // {List_}
  20[017] - load local 3
  21[053] - invoke static List.add <sdk>/core/collections.toit // [{List_}, {*}] -> {Null_}
- 24[088] - return S1 2
+ 24[090] - return S1 2
 
 Plan tests/type_propagation/deltablue-test.toit
  - argument 0: {Plan}
@@ -1227,7 +1227,7 @@ Plan tests/type_propagation/deltablue-test.toit
   9[053] - invoke static create-list-literal-from-array_ <sdk>/core/collections.toit // [{LargeArray_|SmallArray_}] -> {List_}
  12[013] - store field, pop 0
  14[016] - load local 2
- 15[088] - return S1 1
+ 15[090] - return S1 1
 
 Plan.add-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {Plan}
@@ -1236,7 +1236,7 @@ Plan.add-constraint tests/type_propagation/deltablue-test.toit
   2[009] - load field local 3 // [{Plan}] -> {Null_|List_}
   4[017] - load local 3
   5[053] - invoke static List.add <sdk>/core/collections.toit // [{Null_|List_}, {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_}
-  8[089] - return null S1 2
+  8[091] - return null S1 2
 
 Plan.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {Plan}
@@ -1244,14 +1244,14 @@ Plan.execute tests/type_propagation/deltablue-test.toit
   5[009] - load field local 3 // [{Plan}] -> {Null_|List_}
   7[038] - load block 1
   9[058] - invoke virtual do // [{Null_|List_}, [block]] -> {Null_}
- 13[089] - return null S2 1
+ 13[091] - return null S2 1
 
 [block] in Plan.execute tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
  - argument 1: {*}
   0[016] - load local 2
   1[058] - invoke virtual execute // [{*}] -> {Null_}
-  5[088] - return S1 2
+  5[090] - return S1 2
 
 chain-test tests/type_propagation/deltablue-test.toit
  - argument 0: {SmallInteger_}
@@ -1305,7 +1305,7 @@ chain-test tests/type_propagation/deltablue-test.toit
  78[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
  79[004] - store local, pop S2
  81[041] - pop 1
- 82[083] - branch back T14
+ 82[084] - branch back T14
  87[041] - pop 1
  88[042] - allocate instance StayConstraint
  90[032] - load global var lazy G3 // {Strength}
@@ -1371,8 +1371,8 @@ chain-test tests/type_propagation/deltablue-test.toit
 200[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
 201[004] - store local, pop S2
 203[041] - pop 1
-204[083] - branch back T119
-209[089] - return null S6 1
+204[084] - branch back T119
+209[091] - return null S6 1
 
 projection-test tests/type_propagation/deltablue-test.toit
  - argument 0: {SmallInteger_}
@@ -1443,7 +1443,7 @@ projection-test tests/type_propagation/deltablue-test.toit
 118[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
 119[004] - store local, pop S2
 121[041] - pop 1
-122[083] - branch back T43
+122[084] - branch back T43
 127[002] - pop, load local S2
 129[026] - load smi 17
 131[053] - invoke static change tests/type_propagation/deltablue-test.toit // [{Null_|Variable}, {SmallInteger_}] -> {Null_}
@@ -1497,7 +1497,7 @@ projection-test tests/type_propagation/deltablue-test.toit
 220[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
 221[004] - store local, pop S2
 223[041] - pop 1
-224[083] - branch back T184
+224[084] - branch back T184
 229[002] - pop, load local S3
 231[027] - load smi 2000
 234[053] - invoke static change tests/type_propagation/deltablue-test.toit // [{Variable}, {SmallInteger_}] -> {Null_}
@@ -1529,8 +1529,8 @@ projection-test tests/type_propagation/deltablue-test.toit
 275[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
 276[004] - store local, pop S2
 278[041] - pop 1
-279[083] - branch back T239
-284[089] - return null S6 1
+279[084] - branch back T239
+284[091] - return null S6 1
 
 change tests/type_propagation/deltablue-test.toit
  - argument 0: {Null_|Variable}
@@ -1553,7 +1553,7 @@ change tests/type_propagation/deltablue-test.toit
  38[041] - pop 1
  39[002] - pop, load local S1
  41[053] - invoke static Constraint.destroy-constraint tests/type_propagation/deltablue-test.toit // [{EditConstraint}] -> {Null_}
- 44[089] - return null S3 2
+ 44[091] - return null S3 2
 
 [block] in change tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1565,4 +1565,4 @@ change tests/type_propagation/deltablue-test.toit
   8[016] - load local 2
   9[005] - load outer S1 // {Plan}
  11[053] - invoke static Plan.execute tests/type_propagation/deltablue-test.toit // [{Plan}] -> {Null_}
- 14[088] - return S1 1
+ 14[090] - return S1 1
diff --git a/tests/type_propagation/gold/deltablue-test.gold-O2 b/tests/type_propagation/gold/deltablue-test.gold-O2
index 3cb158bd3..605842925 100644
--- a/tests/type_propagation/gold/deltablue-test.gold-O2
+++ b/tests/type_propagation/gold/deltablue-test.gold-O2
@@ -3,7 +3,7 @@ main tests/type_propagation/deltablue-test.toit
   5[026] - load smi 10
   7[038] - load block 1
   9[058] - invoke virtual repeat // [{SmallInteger_}, [block]] -> {Null_}
- 13[089] - return null S2 0
+ 13[091] - return null S2 0
 
 [block] in main tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -12,7 +12,7 @@ main tests/type_propagation/deltablue-test.toit
   5[041] - pop 1
   6[026] - load smi 50
   8[053] - invoke static projection-test tests/type_propagation/deltablue-test.toit // [{SmallInteger_}] -> {Null_}
- 11[088] - return S1 1
+ 11[090] - return S1 1
 
 Strength tests/type_propagation/deltablue-test.toit
  - argument 0: {Strength}
@@ -25,12 +25,12 @@ Strength tests/type_propagation/deltablue-test.toit
   5[017] - load local 3
   6[013] - store field, pop 1
   8[018] - load local 4
-  9[088] - return S1 3
+  9[090] - return S1 3
 
 Strength.value tests/type_propagation/deltablue-test.toit
  - argument 0: {Strength}
   0[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Strength.next-weaker tests/type_propagation/deltablue-test.toit
  - argument 0: {Strength}
@@ -39,37 +39,37 @@ Strength.next-weaker tests/type_propagation/deltablue-test.toit
   3[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
   4[082] - branch if false T12
   7[032] - load global var lazy G6 // {Strength}
-  9[088] - return S1 1
+  9[090] - return S1 1
  12[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  14[025] - load smi 1
  15[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  16[082] - branch if false T24
  19[032] - load global var lazy G5 // {Strength}
- 21[088] - return S1 1
+ 21[090] - return S1 1
  24[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  26[026] - load smi 2
  28[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  29[082] - branch if false T37
  32[032] - load global var lazy G4 // {Strength}
- 34[088] - return S1 1
+ 34[090] - return S1 1
  37[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  39[026] - load smi 3
  41[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  42[082] - branch if false T50
  45[032] - load global var lazy G3 // {Strength}
- 47[088] - return S1 1
+ 47[090] - return S1 1
  50[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  52[026] - load smi 4
  54[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  55[082] - branch if false T63
  58[032] - load global var lazy G2 // {Strength}
- 60[088] - return S1 1
+ 60[090] - return S1 1
  63[009] - load field local 2 // [{Strength}] -> {Null_|SmallInteger_}
  65[026] - load smi 5
  67[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  68[082] - branch if false T76
  71[032] - load global var lazy G1 // {Strength}
- 73[088] - return S1 1
+ 73[090] - return S1 1
  76[053] - invoke static unreachable <sdk>/core/exceptions.toit // {}
  79[041] - pop 1
 
@@ -78,49 +78,49 @@ REQUIRED tests/type_propagation/deltablue-test.toit
   2[023] - load smi 0
   3[020] - load literal required
   5[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 STRONG-REFERRED tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[025] - load smi 1
   3[020] - load literal strongPreferred
   5[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 PREFERRED tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 2
   4[020] - load literal preferred
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 STRONG-DEFAULT tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 3
   4[020] - load literal strongDefault
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 NORMAL tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 4
   4[020] - load literal normal
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 WEAK-DEFAULT tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 5
   4[020] - load literal weakDefault
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 WEAKEST tests/type_propagation/deltablue-test.toit
   0[042] - allocate instance Strength
   2[026] - load smi 6
   4[020] - load literal weakest
   6[053] - invoke static Strength tests/type_propagation/deltablue-test.toit // [{Strength}, {SmallInteger_}, {String_}] -> {Strength}
-  9[088] - return S1 0
+  9[090] - return S1 0
 
 stronger tests/type_propagation/deltablue-test.toit
  - argument 0: {Null_|Strength}
@@ -130,7 +130,7 @@ stronger tests/type_propagation/deltablue-test.toit
   4[009] - load field local 3 // [{Strength}] -> {Null_|SmallInteger_}
   6[009] - load field local 3 // [{Strength}] -> {Null_|SmallInteger_}
   8[063] - invoke lt // [{Null_|SmallInteger_}, {Null_|SmallInteger_}] -> {True_|False_}
-  9[088] - return S1 2
+  9[090] - return S1 2
 
 weaker tests/type_propagation/deltablue-test.toit
  - argument 0: {Null_|Strength}
@@ -140,7 +140,7 @@ weaker tests/type_propagation/deltablue-test.toit
   4[009] - load field local 3 // [{Strength}] -> {Null_|SmallInteger_}
   6[009] - load field local 3 // [{Strength}] -> {Null_|SmallInteger_}
   8[064] - invoke gt // [{Null_|SmallInteger_}, {Null_|SmallInteger_}] -> {True_|False_}
-  9[088] - return S1 2
+  9[090] - return S1 2
 
 weakest tests/type_propagation/deltablue-test.toit
  - argument 0: {Null_|Strength}
@@ -152,15 +152,15 @@ weakest tests/type_propagation/deltablue-test.toit
   6[053] - invoke static weaker tests/type_propagation/deltablue-test.toit // [{Strength}, {Strength}] -> {True_|False_}
   9[082] - branch if false T19
  12[017] - load local 3
- 13[088] - return S1 2
+ 13[090] - return S1 2
  16[080] - branch T23
  19[016] - load local 2
- 20[088] - return S1 2
+ 20[090] - return S1 2
 
 Constraint.strength tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
   0[009] - load field local 2 // [{EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_|Strength}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
@@ -169,7 +169,7 @@ Constraint tests/type_propagation/deltablue-test.toit
   1[017] - load local 3
   2[013] - store field, pop 0
   4[017] - load local 3
-  5[088] - return S1 2
+  5[090] - return S1 2
 
 Constraint.add-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
@@ -179,7 +179,7 @@ Constraint.add-constraint tests/type_propagation/deltablue-test.toit
   6[030] - load global var G7 // {Null_|Planner}
   8[017] - load local 3
   9[058] - invoke virtual incremental-add // [{Null_|Planner}, {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_}
- 13[089] - return null S1 1
+ 13[091] - return null S1 1
 
 Constraint.satisfy tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
@@ -197,7 +197,7 @@ Constraint.satisfy tests/type_propagation/deltablue-test.toit
  22[020] - load literal Could not satisfy a required constraint!
  24[053] - invoke static throw <sdk>/core/exceptions.toit // [{String_}] -> {}
  27[041] - pop 1
- 28[089] - return null S0 2
+ 28[091] - return null S0 2
  31[017] - load local 3
  32[017] - load local 3
  33[058] - invoke virtual mark-inputs // [{EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}, {LargeInteger_|SmallInteger_}] -> {Null_}
@@ -224,7 +224,7 @@ Constraint.satisfy tests/type_propagation/deltablue-test.toit
  80[019] - load local 5
  81[013] - store field, pop 3
  83[014] - load local 0
- 84[088] - return S3 2
+ 84[090] - return S3 2
 
 Constraint.destroy-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint}
@@ -237,17 +237,17 @@ Constraint.destroy-constraint tests/type_propagation/deltablue-test.toit
  14[041] - pop 1
  15[016] - load local 2
  16[058] - invoke virtual remove-from-graph // [{EditConstraint}] -> {Null_}
- 20[089] - return null S1 1
+ 20[091] - return null S1 1
 
 Constraint.is-input tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint|StayConstraint}
   0[020] - load literal false
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 UnaryConstraint.is-satisfied tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
   0[009] - load field local 34 // [{EditConstraint|StayConstraint}] -> {Null_|True_|False_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 UnaryConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -265,7 +265,7 @@ UnaryConstraint tests/type_propagation/deltablue-test.toit
  14[002] - pop, load local S4
  16[053] - invoke static Constraint.add-constraint tests/type_propagation/deltablue-test.toit // [{EditConstraint|StayConstraint}] -> {Null_}
  19[002] - pop, load local S4
- 21[088] - return S1 3
+ 21[090] - return S1 3
 
 UnaryConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -275,7 +275,7 @@ UnaryConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
   6[002] - pop, load local S2
   8[020] - load literal false
  10[013] - store field, pop 2
- 12[089] - return null S0 1
+ 12[091] - return null S0 1
 
 UnaryConstraint.choose-method tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -296,17 +296,17 @@ UnaryConstraint.choose-method tests/type_propagation/deltablue-test.toit
  25[007] - load field 4 // [{Null_|Variable}] -> {Null_|Strength}
  27[053] - invoke static stronger tests/type_propagation/deltablue-test.toit // [{Null_|Strength}, {Null_|Strength}] -> {True_|False_}
  30[013] - store field, pop 2
- 32[089] - return null S0 2
+ 32[091] - return null S0 2
 
 UnaryConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
  - argument 1: {LargeInteger_|SmallInteger_}
-  0[089] - return null S0 2
+  0[091] - return null S0 2
 
 UnaryConstraint.output tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
   0[009] - load field local 18 // [{EditConstraint|StayConstraint}] -> {Null_|Variable}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 UnaryConstraint.recalculate tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -327,20 +327,20 @@ UnaryConstraint.recalculate tests/type_propagation/deltablue-test.toit
  32[016] - load local 2
  33[058] - invoke virtual execute // [{EditConstraint|StayConstraint}] -> {Null_}
  37[041] - pop 1
- 38[089] - return null S0 1
+ 38[091] - return null S0 1
 
 UnaryConstraint.mark-unsatisfied tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
   0[016] - load local 2
   1[020] - load literal false
   3[013] - store field, pop 2
-  5[089] - return null S0 1
+  5[091] - return null S0 1
 
 UnaryConstraint.inputs-known tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
  - argument 1: {LargeInteger_|SmallInteger_}
   0[020] - load literal true
-  2[088] - return S1 2
+  2[090] - return S1 2
 
 UnaryConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint|StayConstraint}
@@ -350,7 +350,7 @@ UnaryConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
   6[002] - pop, load local S2
   8[020] - load literal false
  10[013] - store field, pop 2
- 12[089] - return null S0 1
+ 12[091] - return null S0 1
 
 StayConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {StayConstraint}
@@ -362,11 +362,11 @@ StayConstraint tests/type_propagation/deltablue-test.toit
   4[018] - load local 4
   5[053] - invoke static UnaryConstraint tests/type_propagation/deltablue-test.toit // [{StayConstraint}, {Strength}, {Variable}] -> {StayConstraint}
   8[002] - pop, load local S4
- 10[088] - return S1 3
+ 10[090] - return S1 3
 
 StayConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {StayConstraint}
-  0[089] - return null S0 1
+  0[091] - return null S0 1
 
 EditConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint}
@@ -378,16 +378,16 @@ EditConstraint tests/type_propagation/deltablue-test.toit
   4[018] - load local 4
   5[053] - invoke static UnaryConstraint tests/type_propagation/deltablue-test.toit // [{EditConstraint}, {Strength}, {Variable}] -> {EditConstraint}
   8[002] - pop, load local S4
- 10[088] - return S1 3
+ 10[090] - return S1 3
 
 EditConstraint.is-input tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint}
   0[020] - load literal true
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 EditConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {EditConstraint}
-  0[089] - return null S0 1
+  0[091] - return null S0 1
 
 BinaryConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -409,7 +409,7 @@ BinaryConstraint tests/type_propagation/deltablue-test.toit
  17[002] - pop, load local S5
  19[053] - invoke static Constraint.add-constraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint|ScaleConstraint}] -> {Null_}
  22[002] - pop, load local S5
- 24[088] - return S1 4
+ 24[090] - return S1 4
 
 BinaryConstraint.choose-method tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -483,7 +483,7 @@ BinaryConstraint.choose-method tests/type_propagation/deltablue-test.toit
 128[041] - pop 1
 129[026] - load smi 2
 131[013] - store field, pop 3
-133[089] - return null S0 2
+133[091] - return null S0 2
 
 BinaryConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -496,7 +496,7 @@ BinaryConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  12[002] - pop, load local S2
  14[025] - load smi 1
  15[013] - store field, pop 3
- 17[089] - return null S0 1
+ 17[091] - return null S0 1
 
 BinaryConstraint.is-satisfied tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -507,7 +507,7 @@ BinaryConstraint.is-satisfied tests/type_propagation/deltablue-test.toit
   7[020] - load literal true
   9[080] - branch T14
  12[020] - load literal false
- 14[088] - return S1 1
+ 14[090] - return S1 1
 
 BinaryConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -516,7 +516,7 @@ BinaryConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
   1[053] - invoke static BinaryConstraint.input tests/type_propagation/deltablue-test.toit // [{EqualityConstraint|ScaleConstraint}] -> {Variable}
   4[017] - load local 3
   5[013] - store field, pop 3
-  7[089] - return null S0 2
+  7[091] - return null S0 2
 
 BinaryConstraint.input tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -528,7 +528,7 @@ BinaryConstraint.input tests/type_propagation/deltablue-test.toit
  10[080] - branch T15
  13[009] - load field local 34 // [{EqualityConstraint|ScaleConstraint}] -> {Null_|Variable}
  15[048] - as class Variable(37 - 38) // {True_|False_}
- 17[088] - return S1 1
+ 17[090] - return S1 1
 
 BinaryConstraint.output tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -540,7 +540,7 @@ BinaryConstraint.output tests/type_propagation/deltablue-test.toit
  10[080] - branch T15
  13[009] - load field local 18 // [{EqualityConstraint|ScaleConstraint}] -> {Null_|Variable}
  15[048] - as class Variable(37 - 38) // {True_|False_}
- 17[088] - return S1 1
+ 17[090] - return S1 1
 
 BinaryConstraint.recalculate tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
@@ -561,14 +561,14 @@ BinaryConstraint.recalculate tests/type_propagation/deltablue-test.toit
  28[018] - load local 4
  29[058] - invoke virtual execute // [{EqualityConstraint}] -> {Null_}
  33[041] - pop 1
- 34[089] - return null S2 1
+ 34[091] - return null S2 1
 
 BinaryConstraint.mark-unsatisfied tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
   0[016] - load local 2
   1[025] - load smi 1
   2[013] - store field, pop 3
-  4[089] - return null S0 1
+  4[091] - return null S0 1
 
 BinaryConstraint.inputs-known tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -585,7 +585,7 @@ BinaryConstraint.inputs-known tests/type_propagation/deltablue-test.toit
  15[081] - branch if true T20
  18[010] - pop, load field local 32 // [{Variable}] -> {Null_|EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
  20[048] - as class True_(15 - 17) // {True_|False_}
- 22[088] - return S2 2
+ 22[090] - return S2 2
 
 BinaryConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint|ScaleConstraint}
@@ -598,7 +598,7 @@ BinaryConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  12[002] - pop, load local S2
  14[025] - load smi 1
  15[013] - store field, pop 3
- 17[089] - return null S0 1
+ 17[091] - return null S0 1
 
 ScaleConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -619,7 +619,7 @@ ScaleConstraint tests/type_propagation/deltablue-test.toit
  16[000] - load local S7
  18[053] - invoke static BinaryConstraint tests/type_propagation/deltablue-test.toit // [{ScaleConstraint}, {Strength}, {Variable}, {Variable}] -> {ScaleConstraint}
  21[002] - pop, load local S7
- 23[088] - return S1 6
+ 23[090] - return S1 6
 
 ScaleConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -631,7 +631,7 @@ ScaleConstraint.add-to-graph tests/type_propagation/deltablue-test.toit
  10[010] - pop, load field local 82 // [{ScaleConstraint}] -> {Null_|Variable}
  12[017] - load local 3
  13[053] - invoke static Variable.add-constraint tests/type_propagation/deltablue-test.toit // [{Null_|Variable}, {ScaleConstraint}] -> {Null_}
- 16[089] - return null S1 1
+ 16[091] - return null S1 1
 
 ScaleConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -643,7 +643,7 @@ ScaleConstraint.remove-from-graph tests/type_propagation/deltablue-test.toit
  10[010] - pop, load field local 82 // [{ScaleConstraint}] -> {Null_|Variable}
  12[017] - load local 3
  13[053] - invoke static Variable.remove-constraint tests/type_propagation/deltablue-test.toit // [{Null_|Variable}, {ScaleConstraint}] -> {Null_}
- 16[089] - return null S1 1
+ 16[091] - return null S1 1
 
 ScaleConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -656,7 +656,7 @@ ScaleConstraint.mark-inputs tests/type_propagation/deltablue-test.toit
   9[018] - load local 4
  10[011] - store field 3
  12[013] - store field, pop 3
- 14[089] - return null S0 2
+ 14[091] - return null S0 2
 
 ScaleConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -685,7 +685,7 @@ ScaleConstraint.execute tests/type_propagation/deltablue-test.toit
  42[007] - load field 1 // [{Null_|Variable}] -> {Null_|LargeInteger_|SmallInteger_}
  44[076] - invoke div // [{LargeInteger_|SmallInteger_}, {Null_|LargeInteger_|SmallInteger_}] -> {LargeInteger_|SmallInteger_}
  45[013] - store field, pop 1
- 47[089] - return null S0 1
+ 47[091] - return null S0 1
 
 ScaleConstraint.recalculate tests/type_propagation/deltablue-test.toit
  - argument 0: {ScaleConstraint}
@@ -714,7 +714,7 @@ ScaleConstraint.recalculate tests/type_propagation/deltablue-test.toit
  44[018] - load local 4
  45[053] - invoke static ScaleConstraint.execute tests/type_propagation/deltablue-test.toit // [{ScaleConstraint}] -> {Null_}
  48[041] - pop 1
- 49[089] - return null S2 1
+ 49[091] - return null S2 1
 
 EqualityConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
@@ -728,7 +728,7 @@ EqualityConstraint tests/type_propagation/deltablue-test.toit
   5[019] - load local 5
   6[053] - invoke static BinaryConstraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}, {Strength}, {Variable}, {Variable}] -> {EqualityConstraint}
   9[002] - pop, load local S5
- 11[088] - return S1 4
+ 11[090] - return S1 4
 
 EqualityConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
@@ -738,7 +738,7 @@ EqualityConstraint.execute tests/type_propagation/deltablue-test.toit
   5[053] - invoke static BinaryConstraint.input tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}] -> {Variable}
   8[007] - load field 1 // [{Variable}] -> {Null_|LargeInteger_|SmallInteger_}
  10[013] - store field, pop 1
- 12[089] - return null S0 1
+ 12[091] - return null S0 1
 
 Variable tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -768,12 +768,12 @@ Variable tests/type_propagation/deltablue-test.toit
  31[053] - invoke static create-list-literal-from-array_ <sdk>/core/collections.toit // [{LargeArray_|SmallArray_}] -> {List_}
  34[013] - store field, pop 6
  36[018] - load local 4
- 37[088] - return S1 3
+ 37[090] - return S1 3
 
 Variable.value tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
   0[009] - load field local 18 // [{Variable}] -> {Null_|LargeInteger_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Variable.value= tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -781,17 +781,17 @@ Variable.value= tests/type_propagation/deltablue-test.toit
   0[017] - load local 3
   1[017] - load local 3
   2[011] - store field 1
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 Variable.determined-by tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
   0[009] - load field local 34 // [{Variable}] -> {Null_|EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Variable.mark tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
   0[009] - load field local 50 // [{Variable}] -> {Null_|LargeInteger_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Variable.mark= tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -799,12 +799,12 @@ Variable.mark= tests/type_propagation/deltablue-test.toit
   0[017] - load local 3
   1[017] - load local 3
   2[011] - store field 3
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 Variable.constraints tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
   0[009] - load field local 98 // [{Variable}] -> {Null_|List_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Variable.add-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -812,7 +812,7 @@ Variable.add-constraint tests/type_propagation/deltablue-test.toit
   0[009] - load field local 99 // [{Variable}] -> {Null_|List_}
   2[017] - load local 3
   3[058] - invoke virtual add // [{Null_|List_}, {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_}
-  7[089] - return null S1 2
+  7[091] - return null S1 2
 
 Variable.remove-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {Variable}
@@ -831,7 +831,7 @@ Variable.remove-constraint tests/type_propagation/deltablue-test.toit
  25[017] - load local 3
  26[022] - load null
  27[013] - store field, pop 2
- 29[089] - return null S0 2
+ 29[091] - return null S0 2
 
 [block] in Variable.remove-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -844,7 +844,7 @@ Variable.remove-constraint tests/type_propagation/deltablue-test.toit
   8[020] - load literal true
  10[080] - branch T15
  13[020] - load literal false
- 15[088] - return S1 2
+ 15[090] - return S1 2
 
 Planner tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -852,7 +852,7 @@ Planner tests/type_propagation/deltablue-test.toit
   1[023] - load smi 0
   2[013] - store field, pop 0
   4[016] - load local 2
-  5[088] - return S1 1
+  5[090] - return S1 1
 
 Planner.incremental-add tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -869,8 +869,8 @@ Planner.incremental-add tests/type_propagation/deltablue-test.toit
  16[016] - load local 2
  17[058] - invoke virtual satisfy // [{Null_|EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}, {LargeInteger_|SmallInteger_}] -> {Null_|EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}
  21[004] - store local, pop S1
- 23[083] - branch back T11
- 28[089] - return null S2 2
+ 23[084] - branch back T11
+ 28[091] - return null S2 2
 
 Planner.incremental-remove tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -898,8 +898,8 @@ Planner.incremental-remove tests/type_propagation/deltablue-test.toit
  48[062] - invoke eq // [{Strength}, {Strength}] -> {True_|False_}
  49[082] - branch if false T55
  52[080] - branch T60
- 55[083] - branch back T24
- 60[089] - return null S3 2
+ 55[084] - branch back T24
+ 60[091] - return null S3 2
 
 [block] in Planner.incremental-remove tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -915,7 +915,7 @@ Planner.incremental-remove tests/type_propagation/deltablue-test.toit
  14[005] - load outer S7 // {Planner}
  16[017] - load local 3
  17[053] - invoke static Planner.incremental-add tests/type_propagation/deltablue-test.toit // [{Planner}, {*}] -> {Null_}
- 20[088] - return S1 2
+ 20[090] - return S1 2
 
 Planner.new-mark tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -924,7 +924,7 @@ Planner.new-mark tests/type_propagation/deltablue-test.toit
   3[025] - load smi 1
   4[073] - invoke add // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[011] - store field 0
-  7[088] - return S1 1
+  7[090] - return S1 1
 
 Planner.make-plan tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -963,9 +963,9 @@ Planner.make-plan tests/type_propagation/deltablue-test.toit
  67[053] - invoke static Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit // [{Planner}, {Null_|Variable}, {List_}] -> {Null_}
  70[041] - pop 1
  71[041] - pop 1
- 72[083] - branch back T10
+ 72[084] - branch back T10
  77[015] - load local 1
- 78[088] - return S4 2
+ 78[090] - return S4 2
 
 Planner.extract-plan-from-constraints tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -984,7 +984,7 @@ Planner.extract-plan-from-constraints tests/type_propagation/deltablue-test.toit
  24[002] - pop, load local S4
  26[015] - load local 1
  27[053] - invoke static Planner.make-plan tests/type_propagation/deltablue-test.toit // [{Planner}, {List_}] -> {Plan}
- 30[088] - return S2 2
+ 30[090] - return S2 2
 
 [block] in Planner.extract-plan-from-constraints tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1000,7 +1000,7 @@ Planner.extract-plan-from-constraints tests/type_propagation/deltablue-test.toit
  18[005] - load outer S1 // {List_}
  20[017] - load local 3
  21[053] - invoke static List.add <sdk>/core/collections.toit // [{List_}, {*}] -> {Null_}
- 24[088] - return S1 2
+ 24[090] - return S1 2
 
 Planner.add-propagate tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -1025,7 +1025,7 @@ Planner.add-propagate tests/type_propagation/deltablue-test.toit
  36[053] - invoke static Planner.incremental-remove tests/type_propagation/deltablue-test.toit // [{Planner}, {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_}
  39[041] - pop 1
  40[020] - load literal false
- 42[088] - return S3 3
+ 42[090] - return S3 3
  45[014] - load local 0
  46[058] - invoke virtual recalculate // [{*}] -> {Null_}
  50[002] - pop, load local S6
@@ -1034,9 +1034,9 @@ Planner.add-propagate tests/type_propagation/deltablue-test.toit
  57[017] - load local 3
  58[053] - invoke static Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit // [{Planner}, {Null_|Variable}, {List_}] -> {Null_}
  61[040] - pop 2
- 63[083] - branch back T7
+ 63[084] - branch back T7
  68[020] - load literal true
- 70[088] - return S2 3
+ 70[090] - return S2 3
 
 Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -1079,9 +1079,9 @@ Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  76[038] - load block 1
  78[058] - invoke virtual do // [{Null_|List_}, [block]] -> {Null_}
  82[040] - pop 4
- 84[083] - branch back T34
+ 84[084] - branch back T34
  89[015] - load local 1
- 90[088] - return S3 2
+ 90[090] - return S3 2
 
 [block] in Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1094,7 +1094,7 @@ Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  10[005] - load outer S3 // {List_}
  12[017] - load local 3
  13[053] - invoke static List.add <sdk>/core/collections.toit // [{List_}, {*}] -> {Null_}
- 16[088] - return S1 2
+ 16[090] - return S1 2
 
 [block] in Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1115,7 +1115,7 @@ Planner.remove-propagate-from tests/type_propagation/deltablue-test.toit
  26[017] - load local 3
  27[058] - invoke virtual output // [{*}] -> {Null_|Variable}
  31[053] - invoke static List.add <sdk>/core/collections.toit // [{List_}, {Null_|Variable}] -> {Null_}
- 34[088] - return S1 2
+ 34[090] - return S1 2
 
 Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit
  - argument 0: {Planner}
@@ -1127,7 +1127,7 @@ Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit
   9[009] - load field local 101 // [{Variable}] -> {Null_|List_}
  11[038] - load block 1
  13[058] - invoke virtual do // [{Null_|List_}, [block]] -> {Null_}
- 17[089] - return null S3 3
+ 17[091] - return null S3 3
 
 [block] in Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1145,7 +1145,7 @@ Planner.add-constraints-consuming-to tests/type_propagation/deltablue-test.toit
  18[005] - load outer S4 // {List_}
  20[017] - load local 3
  21[053] - invoke static List.add <sdk>/core/collections.toit // [{List_}, {*}] -> {Null_}
- 24[088] - return S1 2
+ 24[090] - return S1 2
 
 Plan tests/type_propagation/deltablue-test.toit
  - argument 0: {Plan}
@@ -1158,7 +1158,7 @@ Plan tests/type_propagation/deltablue-test.toit
   9[053] - invoke static create-list-literal-from-array_ <sdk>/core/collections.toit // [{LargeArray_|SmallArray_}] -> {List_}
  12[013] - store field, pop 0
  14[016] - load local 2
- 15[088] - return S1 1
+ 15[090] - return S1 1
 
 Plan.add-constraint tests/type_propagation/deltablue-test.toit
  - argument 0: {Plan}
@@ -1167,7 +1167,7 @@ Plan.add-constraint tests/type_propagation/deltablue-test.toit
   2[009] - load field local 3 // [{Plan}] -> {Null_|List_}
   4[017] - load local 3
   5[053] - invoke static List.add <sdk>/core/collections.toit // [{Null_|List_}, {EqualityConstraint|ScaleConstraint|EditConstraint|StayConstraint}] -> {Null_}
-  8[089] - return null S1 2
+  8[091] - return null S1 2
 
 Plan.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {Plan}
@@ -1175,14 +1175,14 @@ Plan.execute tests/type_propagation/deltablue-test.toit
   5[009] - load field local 3 // [{Plan}] -> {Null_|List_}
   7[038] - load block 1
   9[058] - invoke virtual do // [{Null_|List_}, [block]] -> {Null_}
- 13[089] - return null S2 1
+ 13[091] - return null S2 1
 
 [block] in Plan.execute tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
  - argument 1: {*}
   0[016] - load local 2
   1[058] - invoke virtual execute // [{*}] -> {Null_}
-  5[088] - return S1 2
+  5[090] - return S1 2
 
 chain-test tests/type_propagation/deltablue-test.toit
  - argument 0: {SmallInteger_}
@@ -1234,7 +1234,7 @@ chain-test tests/type_propagation/deltablue-test.toit
  74[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
  75[004] - store local, pop S2
  77[041] - pop 1
- 78[083] - branch back T12
+ 78[084] - branch back T12
  83[041] - pop 1
  84[042] - allocate instance StayConstraint
  86[032] - load global var lazy G3 // {Strength}
@@ -1300,8 +1300,8 @@ chain-test tests/type_propagation/deltablue-test.toit
 196[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
 197[004] - store local, pop S2
 199[041] - pop 1
-200[083] - branch back T115
-205[089] - return null S6 1
+200[084] - branch back T115
+205[091] - return null S6 1
 
 projection-test tests/type_propagation/deltablue-test.toit
  - argument 0: {SmallInteger_}
@@ -1369,7 +1369,7 @@ projection-test tests/type_propagation/deltablue-test.toit
 112[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
 113[004] - store local, pop S2
 115[041] - pop 1
-116[083] - branch back T41
+116[084] - branch back T41
 121[002] - pop, load local S2
 123[026] - load smi 17
 125[053] - invoke static change tests/type_propagation/deltablue-test.toit // [{Null_|Variable}, {SmallInteger_}] -> {Null_}
@@ -1423,7 +1423,7 @@ projection-test tests/type_propagation/deltablue-test.toit
 214[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
 215[004] - store local, pop S2
 217[041] - pop 1
-218[083] - branch back T178
+218[084] - branch back T178
 223[002] - pop, load local S3
 225[027] - load smi 2000
 228[053] - invoke static change tests/type_propagation/deltablue-test.toit // [{Variable}, {SmallInteger_}] -> {Null_}
@@ -1455,8 +1455,8 @@ projection-test tests/type_propagation/deltablue-test.toit
 269[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
 270[004] - store local, pop S2
 272[041] - pop 1
-273[083] - branch back T233
-278[089] - return null S6 1
+273[084] - branch back T233
+278[091] - return null S6 1
 
 change tests/type_propagation/deltablue-test.toit
  - argument 0: {Null_|Variable}
@@ -1478,7 +1478,7 @@ change tests/type_propagation/deltablue-test.toit
  36[041] - pop 1
  37[002] - pop, load local S1
  39[053] - invoke static Constraint.destroy-constraint tests/type_propagation/deltablue-test.toit // [{EditConstraint}] -> {Null_}
- 42[089] - return null S3 2
+ 42[091] - return null S3 2
 
 [block] in change tests/type_propagation/deltablue-test.toit
  - argument 0: [block]
@@ -1490,4 +1490,4 @@ change tests/type_propagation/deltablue-test.toit
   8[016] - load local 2
   9[005] - load outer S1 // {Plan}
  11[053] - invoke static Plan.execute tests/type_propagation/deltablue-test.toit // [{Plan}] -> {Null_}
- 14[088] - return S1 1
+ 14[090] - return S1 1
diff --git a/tests/type_propagation/gold/field-test.gold b/tests/type_propagation/gold/field-test.gold
index 3fde47faa..99c4777db 100644
--- a/tests/type_propagation/gold/field-test.gold
+++ b/tests/type_propagation/gold/field-test.gold
@@ -1,6 +1,6 @@
 main tests/type_propagation/field-test.toit
   0[053] - invoke static test-simple tests/type_propagation/field-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 test-simple tests/type_propagation/field-test.toit
   0[042] - allocate instance A
@@ -26,17 +26,17 @@ test-simple tests/type_propagation/field-test.toit
  43[053] - invoke static id tests/type_propagation/field-test.toit // [{Null_|True_}] -> {Null_|True_}
  46[010] - pop, load field local 16 // [{B}] -> {Null_|SmallInteger_}
  48[053] - invoke static id tests/type_propagation/field-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
- 51[089] - return null S3 0
+ 51[091] - return null S3 0
 
 id tests/type_propagation/field-test.toit
  - argument 0: {String_|Null_|True_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 A.x tests/type_propagation/field-test.toit
  - argument 0: {A}
   0[009] - load field local 2 // [{A}] -> {String_|Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 A tests/type_propagation/field-test.toit
  - argument 0: {A|B}
@@ -45,7 +45,7 @@ A tests/type_propagation/field-test.toit
   1[017] - load local 3
   2[013] - store field, pop 0
   4[017] - load local 3
-  5[088] - return S1 2
+  5[090] - return S1 2
 
 B tests/type_propagation/field-test.toit
  - argument 0: {B}
@@ -58,4 +58,4 @@ B tests/type_propagation/field-test.toit
   5[018] - load local 4
   6[053] - invoke static A tests/type_propagation/field-test.toit // [{B}, {True_}] -> {B}
   9[002] - pop, load local S4
- 11[088] - return S1 3
+ 11[090] - return S1 3
diff --git a/tests/type_propagation/gold/field-test.gold-O2 b/tests/type_propagation/gold/field-test.gold-O2
index 3fde47faa..99c4777db 100644
--- a/tests/type_propagation/gold/field-test.gold-O2
+++ b/tests/type_propagation/gold/field-test.gold-O2
@@ -1,6 +1,6 @@
 main tests/type_propagation/field-test.toit
   0[053] - invoke static test-simple tests/type_propagation/field-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 test-simple tests/type_propagation/field-test.toit
   0[042] - allocate instance A
@@ -26,17 +26,17 @@ test-simple tests/type_propagation/field-test.toit
  43[053] - invoke static id tests/type_propagation/field-test.toit // [{Null_|True_}] -> {Null_|True_}
  46[010] - pop, load field local 16 // [{B}] -> {Null_|SmallInteger_}
  48[053] - invoke static id tests/type_propagation/field-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
- 51[089] - return null S3 0
+ 51[091] - return null S3 0
 
 id tests/type_propagation/field-test.toit
  - argument 0: {String_|Null_|True_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 A.x tests/type_propagation/field-test.toit
  - argument 0: {A}
   0[009] - load field local 2 // [{A}] -> {String_|Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 A tests/type_propagation/field-test.toit
  - argument 0: {A|B}
@@ -45,7 +45,7 @@ A tests/type_propagation/field-test.toit
   1[017] - load local 3
   2[013] - store field, pop 0
   4[017] - load local 3
-  5[088] - return S1 2
+  5[090] - return S1 2
 
 B tests/type_propagation/field-test.toit
  - argument 0: {B}
@@ -58,4 +58,4 @@ B tests/type_propagation/field-test.toit
   5[018] - load local 4
   6[053] - invoke static A tests/type_propagation/field-test.toit // [{B}, {True_}] -> {B}
   9[002] - pop, load local S4
- 11[088] - return S1 3
+ 11[090] - return S1 3
diff --git a/tests/type_propagation/gold/finally-test.gold b/tests/type_propagation/gold/finally-test.gold
index 916c45f40..15b709174 100644
--- a/tests/type_propagation/gold/finally-test.gold
+++ b/tests/type_propagation/gold/finally-test.gold
@@ -6,18 +6,18 @@ main tests/type_propagation/finally-test.toit
   8[053] - invoke static test-catchy tests/type_propagation/finally-test.toit // {Null_}
  11[041] - pop 1
  12[053] - invoke static test-nlb-out-of-try tests/type_propagation/finally-test.toit // {Null_}
- 15[089] - return null S1 0
+ 15[091] - return null S1 0
 
 test-is-exception tests/type_propagation/finally-test.toit
   0[053] - invoke static return-is-exception tests/type_propagation/finally-test.toit // {True_|False_}
   3[041] - pop 1
   4[022] - load null
   5[029] - load method [block] in test-is-exception tests/type_propagation/finally-test.toit
- 10[094] - link try 0
+ 10[096] - link try 0
  12[038] - load block 4
  14[055] - invoke block S1 // [[block]] -> {Null_}
  16[041] - pop 1
- 17[095] - unlink try 0
+ 17[097] - unlink try 0
  19[020] - load literal -2
  21[015] - load local 1
  22[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -28,23 +28,23 @@ test-is-exception tests/type_propagation/finally-test.toit
  30[015] - load local 1
  31[004] - store local, pop S7
  33[040] - pop 2
- 35[096] - unwind
+ 35[098] - unwind
  36[002] - pop, load local S0
  38[053] - invoke static id tests/type_propagation/finally-test.toit // [{True_|False_}] -> {True_|False_}
- 41[089] - return null S2 0
+ 41[091] - return null S2 0
 
 [block] in test-is-exception tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 return-is-exception tests/type_propagation/finally-test.toit
   0[029] - load method [block] in return-is-exception tests/type_propagation/finally-test.toit
-  5[094] - link try 0
+  5[096] - link try 0
   7[038] - load block 4
   9[055] - invoke block S1 // [[block]] -> {Null_}
  11[041] - pop 1
- 12[095] - unlink try 0
+ 12[097] - unlink try 0
  14[020] - load literal -2
  16[015] - load local 1
  17[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -53,25 +53,25 @@ return-is-exception tests/type_propagation/finally-test.toit
  20[082] - branch if false T25
  23[002] - pop, load local S3
  25[015] - load local 1
- 26[088] - return S7 0
- 29[096] - unwind
+ 26[090] - return S7 0
+ 29[098] - unwind
  30[041] - pop 1
 
 [block] in return-is-exception tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 test-exception tests/type_propagation/finally-test.toit
   0[053] - invoke static return-exception tests/type_propagation/finally-test.toit // {Null_|Exception_}
   3[041] - pop 1
   4[022] - load null
   5[029] - load method [block] in test-exception tests/type_propagation/finally-test.toit
- 10[094] - link try 0
+ 10[096] - link try 0
  12[038] - load block 4
  14[055] - invoke block S1 // [[block]] -> {Null_}
  16[041] - pop 1
- 17[095] - unlink try 0
+ 17[097] - unlink try 0
  19[020] - load literal -2
  21[015] - load local 1
  22[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -82,23 +82,23 @@ test-exception tests/type_propagation/finally-test.toit
  30[014] - load local 0
  31[004] - store local, pop S7
  33[040] - pop 2
- 35[096] - unwind
+ 35[098] - unwind
  36[002] - pop, load local S0
  38[053] - invoke static id tests/type_propagation/finally-test.toit // [{Null_|Exception_}] -> {Null_|Exception_}
- 41[089] - return null S2 0
+ 41[091] - return null S2 0
 
 [block] in test-exception tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 return-exception tests/type_propagation/finally-test.toit
   0[029] - load method [block] in return-exception tests/type_propagation/finally-test.toit
-  5[094] - link try 0
+  5[096] - link try 0
   7[038] - load block 4
   9[055] - invoke block S1 // [[block]] -> {Null_}
  11[041] - pop 1
- 12[095] - unlink try 0
+ 12[097] - unlink try 0
  14[020] - load literal -2
  16[015] - load local 1
  17[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -107,26 +107,26 @@ return-exception tests/type_propagation/finally-test.toit
  20[082] - branch if false T25
  23[002] - pop, load local S3
  25[014] - load local 0
- 26[088] - return S7 0
- 29[096] - unwind
+ 26[090] - return S7 0
+ 29[098] - unwind
  30[041] - pop 1
 
 [block] in return-exception tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 test-catchy tests/type_propagation/finally-test.toit
   0[053] - invoke static catchy tests/type_propagation/finally-test.toit // {Null_|True_|False_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 catchy tests/type_propagation/finally-test.toit
   0[029] - load method [block] in catchy tests/type_propagation/finally-test.toit
-  5[094] - link try 0
+  5[096] - link try 0
   7[038] - load block 4
   9[055] - invoke block S1 // [[block]] -> {}
  11[041] - pop 1
- 12[095] - unlink try 0
+ 12[097] - unlink try 0
  14[020] - load literal -2
  16[015] - load local 1
  17[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -135,30 +135,30 @@ catchy tests/type_propagation/finally-test.toit
  20[082] - branch if false T25
  23[002] - pop, load local S3
  25[015] - load local 1
- 26[088] - return S7 0
- 29[096] - unwind
+ 26[090] - return S7 0
+ 29[098] - unwind
  30[041] - pop 1
 
 [block] in catchy tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
   1[017] - load local 3
-  2[090] - non-local return 0
-  4[088] - return S1 1
+  2[092] - non-local return 0
+  4[090] - return S1 1
 
 test-nlb-out-of-try tests/type_propagation/finally-test.toit
   0[026] - load smi 4
   2[029] - load method [block] in test-nlb-out-of-try tests/type_propagation/finally-test.toit
-  7[094] - link try 0
+  7[096] - link try 0
   9[038] - load block 4
  11[055] - invoke block S1 // [[block]] -> {Null_}
  13[041] - pop 1
- 14[095] - unlink try 0
+ 14[097] - unlink try 0
  16[018] - load local 4
  17[053] - invoke static id tests/type_propagation/finally-test.toit // [{String_|Null_|SmallInteger_}] -> {String_|Null_|SmallInteger_}
  20[041] - pop 1
- 21[096] - unwind
- 22[089] - return null S2 0
+ 21[098] - unwind
+ 22[091] - return null S2 0
 
 [block] in test-nlb-out-of-try tests/type_propagation/finally-test.toit
  - argument 0: [block]
@@ -166,7 +166,7 @@ test-nlb-out-of-try tests/type_propagation/finally-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/finally-test.toit // [[block]] -> {}
  10[040] - pop 2
- 12[083] - branch back T0
+ 12[084] - branch back T0
  17[016] - load local 2
  18[020] - load literal hest
  20[006] - store outer S1
@@ -180,36 +180,36 @@ test-nlb-out-of-try tests/type_propagation/finally-test.toit
  41[016] - load local 2
  42[022] - load null
  43[006] - store outer S1
- 45[088] - return S1 1
+ 45[090] - return S1 1
 
 [block] in [block] in test-nlb-out-of-try tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[016] - load local 2
-  1[092] - non-local branch {[block] in test-nlb-out-of-try:17}
-  7[088] - return S1 1
+  1[094] - non-local branch {[block] in test-nlb-out-of-try:17}
+  7[090] - return S1 1
 
 [block] in [block] in test-nlb-out-of-try tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
   1[017] - load local 3
   2[005] - load outer S3 // [block]
-  4[090] - non-local return 16
-  6[088] - return S1 1
+  4[092] - non-local return 16
+  6[090] - return S1 1
 
 id tests/type_propagation/finally-test.toit
  - argument 0: {String_|Null_|True_|False_|SmallInteger_|Exception_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 pick tests/type_propagation/finally-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 invoke tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {}
-  3[089] - return null S1 1
+  3[091] - return null S1 1
diff --git a/tests/type_propagation/gold/finally-test.gold-O2 b/tests/type_propagation/gold/finally-test.gold-O2
index fe4d71e6b..be6200a66 100644
--- a/tests/type_propagation/gold/finally-test.gold-O2
+++ b/tests/type_propagation/gold/finally-test.gold-O2
@@ -6,18 +6,18 @@ main tests/type_propagation/finally-test.toit
   8[053] - invoke static test-catchy tests/type_propagation/finally-test.toit // {Null_}
  11[041] - pop 1
  12[053] - invoke static test-nlb-out-of-try tests/type_propagation/finally-test.toit // {Null_}
- 15[089] - return null S1 0
+ 15[091] - return null S1 0
 
 test-is-exception tests/type_propagation/finally-test.toit
   0[053] - invoke static return-is-exception tests/type_propagation/finally-test.toit // {True_|False_}
   3[041] - pop 1
   4[022] - load null
   5[029] - load method [block] in test-is-exception tests/type_propagation/finally-test.toit
- 10[094] - link try 0
+ 10[096] - link try 0
  12[038] - load block 4
  14[055] - invoke block S1 // [[block]] -> {Null_}
  16[041] - pop 1
- 17[095] - unlink try 0
+ 17[097] - unlink try 0
  19[020] - load literal -2
  21[015] - load local 1
  22[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -28,23 +28,23 @@ test-is-exception tests/type_propagation/finally-test.toit
  30[015] - load local 1
  31[004] - store local, pop S7
  33[040] - pop 2
- 35[096] - unwind
+ 35[098] - unwind
  36[002] - pop, load local S0
  38[053] - invoke static id tests/type_propagation/finally-test.toit // [{True_|False_}] -> {True_|False_}
- 41[089] - return null S2 0
+ 41[091] - return null S2 0
 
 [block] in test-is-exception tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 return-is-exception tests/type_propagation/finally-test.toit
   0[029] - load method [block] in return-is-exception tests/type_propagation/finally-test.toit
-  5[094] - link try 0
+  5[096] - link try 0
   7[038] - load block 4
   9[055] - invoke block S1 // [[block]] -> {Null_}
  11[041] - pop 1
- 12[095] - unlink try 0
+ 12[097] - unlink try 0
  14[020] - load literal -2
  16[015] - load local 1
  17[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -53,25 +53,25 @@ return-is-exception tests/type_propagation/finally-test.toit
  20[082] - branch if false T25
  23[002] - pop, load local S3
  25[015] - load local 1
- 26[088] - return S7 0
- 29[096] - unwind
+ 26[090] - return S7 0
+ 29[098] - unwind
  30[041] - pop 1
 
 [block] in return-is-exception tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 test-exception tests/type_propagation/finally-test.toit
   0[053] - invoke static return-exception tests/type_propagation/finally-test.toit // {Null_|Exception_}
   3[041] - pop 1
   4[022] - load null
   5[029] - load method [block] in test-exception tests/type_propagation/finally-test.toit
- 10[094] - link try 0
+ 10[096] - link try 0
  12[038] - load block 4
  14[055] - invoke block S1 // [[block]] -> {Null_}
  16[041] - pop 1
- 17[095] - unlink try 0
+ 17[097] - unlink try 0
  19[020] - load literal -2
  21[015] - load local 1
  22[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -82,23 +82,23 @@ test-exception tests/type_propagation/finally-test.toit
  30[014] - load local 0
  31[004] - store local, pop S7
  33[040] - pop 2
- 35[096] - unwind
+ 35[098] - unwind
  36[002] - pop, load local S0
  38[053] - invoke static id tests/type_propagation/finally-test.toit // [{Null_|Exception_}] -> {Null_|Exception_}
- 41[089] - return null S2 0
+ 41[091] - return null S2 0
 
 [block] in test-exception tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 return-exception tests/type_propagation/finally-test.toit
   0[029] - load method [block] in return-exception tests/type_propagation/finally-test.toit
-  5[094] - link try 0
+  5[096] - link try 0
   7[038] - load block 4
   9[055] - invoke block S1 // [[block]] -> {Null_}
  11[041] - pop 1
- 12[095] - unlink try 0
+ 12[097] - unlink try 0
  14[020] - load literal -2
  16[015] - load local 1
  17[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -107,26 +107,26 @@ return-exception tests/type_propagation/finally-test.toit
  20[082] - branch if false T25
  23[002] - pop, load local S3
  25[014] - load local 0
- 26[088] - return S7 0
- 29[096] - unwind
+ 26[090] - return S7 0
+ 29[098] - unwind
  30[041] - pop 1
 
 [block] in return-exception tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 test-catchy tests/type_propagation/finally-test.toit
   0[053] - invoke static catchy tests/type_propagation/finally-test.toit // {Null_|True_|False_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 catchy tests/type_propagation/finally-test.toit
   0[029] - load method [block] in catchy tests/type_propagation/finally-test.toit
-  5[094] - link try 0
+  5[096] - link try 0
   7[038] - load block 4
   9[055] - invoke block S1 // [[block]] -> {}
  11[041] - pop 1
- 12[095] - unlink try 0
+ 12[097] - unlink try 0
  14[020] - load literal -2
  16[015] - load local 1
  17[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
@@ -135,30 +135,30 @@ catchy tests/type_propagation/finally-test.toit
  20[082] - branch if false T25
  23[002] - pop, load local S3
  25[015] - load local 1
- 26[088] - return S7 0
- 29[096] - unwind
+ 26[090] - return S7 0
+ 29[098] - unwind
  30[041] - pop 1
 
 [block] in catchy tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
   1[017] - load local 3
-  2[090] - non-local return 0
-  4[088] - return S1 1
+  2[092] - non-local return 0
+  4[090] - return S1 1
 
 test-nlb-out-of-try tests/type_propagation/finally-test.toit
   0[026] - load smi 4
   2[029] - load method [block] in test-nlb-out-of-try tests/type_propagation/finally-test.toit
-  7[094] - link try 0
+  7[096] - link try 0
   9[038] - load block 4
  11[055] - invoke block S1 // [[block]] -> {Null_}
  13[041] - pop 1
- 14[095] - unlink try 0
+ 14[097] - unlink try 0
  16[018] - load local 4
  17[053] - invoke static id tests/type_propagation/finally-test.toit // [{String_|Null_|SmallInteger_}] -> {String_|Null_|SmallInteger_}
  20[041] - pop 1
- 21[096] - unwind
- 22[089] - return null S2 0
+ 21[098] - unwind
+ 22[091] - return null S2 0
 
 [block] in test-nlb-out-of-try tests/type_propagation/finally-test.toit
  - argument 0: [block]
@@ -166,7 +166,7 @@ test-nlb-out-of-try tests/type_propagation/finally-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/finally-test.toit // [[block]] -> {}
  10[040] - pop 2
- 12[083] - branch back T0
+ 12[084] - branch back T0
  17[016] - load local 2
  18[020] - load literal hest
  20[006] - store outer S1
@@ -180,33 +180,33 @@ test-nlb-out-of-try tests/type_propagation/finally-test.toit
  41[016] - load local 2
  42[022] - load null
  43[006] - store outer S1
- 45[088] - return S1 1
+ 45[090] - return S1 1
 
 [block] in [block] in test-nlb-out-of-try tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[016] - load local 2
-  1[092] - non-local branch {[block] in test-nlb-out-of-try:17}
-  7[088] - return S1 1
+  1[094] - non-local branch {[block] in test-nlb-out-of-try:17}
+  7[090] - return S1 1
 
 [block] in [block] in test-nlb-out-of-try tests/type_propagation/finally-test.toit
  - argument 0: [block]
   0[022] - load null
   1[017] - load local 3
   2[005] - load outer S3 // [block]
-  4[090] - non-local return 16
-  6[088] - return S1 1
+  4[092] - non-local return 16
+  6[090] - return S1 1
 
 id tests/type_propagation/finally-test.toit
  - argument 0: {String_|Null_|True_|False_|SmallInteger_|Exception_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 pick tests/type_propagation/finally-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 invoke tests/type_propagation/finally-test.toit
  - argument 0: [block]
diff --git a/tests/type_propagation/gold/global-test.gold b/tests/type_propagation/gold/global-test.gold
index 2da328a13..5f5cbd719 100644
--- a/tests/type_propagation/gold/global-test.gold
+++ b/tests/type_propagation/gold/global-test.gold
@@ -1,18 +1,18 @@
 main tests/type_propagation/global-test.toit
   0[053] - invoke static test-simple tests/type_propagation/global-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 X tests/type_propagation/global-test.toit
   0[053] - invoke static foo tests/type_propagation/global-test.toit // {SmallInteger_}
-  3[088] - return S1 0
+  3[090] - return S1 0
 
 Y tests/type_propagation/global-test.toit
   0[053] - invoke static foo tests/type_propagation/global-test.toit // {SmallInteger_}
-  3[088] - return S1 0
+  3[090] - return S1 0
 
 Z tests/type_propagation/global-test.toit
   0[053] - invoke static foo tests/type_propagation/global-test.toit // {SmallInteger_}
-  3[088] - return S1 0
+  3[090] - return S1 0
 
 test-simple tests/type_propagation/global-test.toit
   0[032] - load global var lazy G0 // {SmallInteger_}
@@ -29,13 +29,13 @@ test-simple tests/type_propagation/global-test.toit
  22[041] - pop 1
  23[032] - load global var lazy G2 // {SmallInteger_}
  25[053] - invoke static id tests/type_propagation/global-test.toit // [{SmallInteger_}] -> {SmallInteger_}
- 28[089] - return null S1 0
+ 28[091] - return null S1 0
 
 foo tests/type_propagation/global-test.toit
   0[026] - load smi 42
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 id tests/type_propagation/global-test.toit
  - argument 0: {String_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/global-test.gold-O2 b/tests/type_propagation/gold/global-test.gold-O2
index 2da328a13..5f5cbd719 100644
--- a/tests/type_propagation/gold/global-test.gold-O2
+++ b/tests/type_propagation/gold/global-test.gold-O2
@@ -1,18 +1,18 @@
 main tests/type_propagation/global-test.toit
   0[053] - invoke static test-simple tests/type_propagation/global-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 X tests/type_propagation/global-test.toit
   0[053] - invoke static foo tests/type_propagation/global-test.toit // {SmallInteger_}
-  3[088] - return S1 0
+  3[090] - return S1 0
 
 Y tests/type_propagation/global-test.toit
   0[053] - invoke static foo tests/type_propagation/global-test.toit // {SmallInteger_}
-  3[088] - return S1 0
+  3[090] - return S1 0
 
 Z tests/type_propagation/global-test.toit
   0[053] - invoke static foo tests/type_propagation/global-test.toit // {SmallInteger_}
-  3[088] - return S1 0
+  3[090] - return S1 0
 
 test-simple tests/type_propagation/global-test.toit
   0[032] - load global var lazy G0 // {SmallInteger_}
@@ -29,13 +29,13 @@ test-simple tests/type_propagation/global-test.toit
  22[041] - pop 1
  23[032] - load global var lazy G2 // {SmallInteger_}
  25[053] - invoke static id tests/type_propagation/global-test.toit // [{SmallInteger_}] -> {SmallInteger_}
- 28[089] - return null S1 0
+ 28[091] - return null S1 0
 
 foo tests/type_propagation/global-test.toit
   0[026] - load smi 42
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 id tests/type_propagation/global-test.toit
  - argument 0: {String_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/lambda-test.gold b/tests/type_propagation/gold/lambda-test.gold
index 035a64f30..bac617b85 100644
--- a/tests/type_propagation/gold/lambda-test.gold
+++ b/tests/type_propagation/gold/lambda-test.gold
@@ -2,7 +2,7 @@ main tests/type_propagation/lambda-test.toit
   0[053] - invoke static test-simple tests/type_propagation/lambda-test.toit // {*}
   3[041] - pop 1
   4[053] - invoke static test-arguments tests/type_propagation/lambda-test.toit // {Null_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 test-simple tests/type_propagation/lambda-test.toit
   0[029] - load method [lambda] in test-simple tests/type_propagation/lambda-test.toit
@@ -15,11 +15,11 @@ test-simple tests/type_propagation/lambda-test.toit
  14[053] - invoke static lambda__ <sdk>/core/objects.toit // [{SmallInteger_}, {LargeArray_|SmallArray_}, {SmallInteger_}] -> {Lambda}
  17[014] - load local 0
  18[053] - invoke static Lambda.call <sdk>/core/objects.toit // [{Lambda}] -> {*}
- 21[088] - return S2 0
+ 21[090] - return S2 0
 
 [lambda] in test-simple tests/type_propagation/lambda-test.toit
   0[026] - load smi 42
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 test-arguments tests/type_propagation/lambda-test.toit
   0[029] - load method [lambda] in test-arguments tests/type_propagation/lambda-test.toit
@@ -44,13 +44,13 @@ test-arguments tests/type_propagation/lambda-test.toit
  40[026] - load smi 42
  42[020] - load literal fisk
  44[053] - invoke static Lambda.call <sdk>/core/objects.toit // [{Lambda}, {SmallInteger_}, {String_}] -> {*}
- 47[089] - return null S1 0
+ 47[091] - return null S1 0
 
 [lambda] in test-arguments tests/type_propagation/lambda-test.toit
  - argument 0: {*}
   0[016] - load local 2
   1[053] - invoke static id tests/type_propagation/lambda-test.toit // [{*}] -> {*}
-  4[088] - return S1 1
+  4[090] - return S1 1
 
 [lambda] in test-arguments tests/type_propagation/lambda-test.toit
  - argument 0: {*}
@@ -59,9 +59,9 @@ test-arguments tests/type_propagation/lambda-test.toit
   1[053] - invoke static id tests/type_propagation/lambda-test.toit // [{*}] -> {*}
   4[002] - pop, load local S2
   6[053] - invoke static id tests/type_propagation/lambda-test.toit // [{*}] -> {*}
-  9[088] - return S1 2
+  9[090] - return S1 2
 
 id tests/type_propagation/lambda-test.toit
  - argument 0: {*}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/lambda-test.gold-O2 b/tests/type_propagation/gold/lambda-test.gold-O2
index 035a64f30..bac617b85 100644
--- a/tests/type_propagation/gold/lambda-test.gold-O2
+++ b/tests/type_propagation/gold/lambda-test.gold-O2
@@ -2,7 +2,7 @@ main tests/type_propagation/lambda-test.toit
   0[053] - invoke static test-simple tests/type_propagation/lambda-test.toit // {*}
   3[041] - pop 1
   4[053] - invoke static test-arguments tests/type_propagation/lambda-test.toit // {Null_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 test-simple tests/type_propagation/lambda-test.toit
   0[029] - load method [lambda] in test-simple tests/type_propagation/lambda-test.toit
@@ -15,11 +15,11 @@ test-simple tests/type_propagation/lambda-test.toit
  14[053] - invoke static lambda__ <sdk>/core/objects.toit // [{SmallInteger_}, {LargeArray_|SmallArray_}, {SmallInteger_}] -> {Lambda}
  17[014] - load local 0
  18[053] - invoke static Lambda.call <sdk>/core/objects.toit // [{Lambda}] -> {*}
- 21[088] - return S2 0
+ 21[090] - return S2 0
 
 [lambda] in test-simple tests/type_propagation/lambda-test.toit
   0[026] - load smi 42
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 test-arguments tests/type_propagation/lambda-test.toit
   0[029] - load method [lambda] in test-arguments tests/type_propagation/lambda-test.toit
@@ -44,13 +44,13 @@ test-arguments tests/type_propagation/lambda-test.toit
  40[026] - load smi 42
  42[020] - load literal fisk
  44[053] - invoke static Lambda.call <sdk>/core/objects.toit // [{Lambda}, {SmallInteger_}, {String_}] -> {*}
- 47[089] - return null S1 0
+ 47[091] - return null S1 0
 
 [lambda] in test-arguments tests/type_propagation/lambda-test.toit
  - argument 0: {*}
   0[016] - load local 2
   1[053] - invoke static id tests/type_propagation/lambda-test.toit // [{*}] -> {*}
-  4[088] - return S1 1
+  4[090] - return S1 1
 
 [lambda] in test-arguments tests/type_propagation/lambda-test.toit
  - argument 0: {*}
@@ -59,9 +59,9 @@ test-arguments tests/type_propagation/lambda-test.toit
   1[053] - invoke static id tests/type_propagation/lambda-test.toit // [{*}] -> {*}
   4[002] - pop, load local S2
   6[053] - invoke static id tests/type_propagation/lambda-test.toit // [{*}] -> {*}
-  9[088] - return S1 2
+  9[090] - return S1 2
 
 id tests/type_propagation/lambda-test.toit
  - argument 0: {*}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/literal-test.gold b/tests/type_propagation/gold/literal-test.gold
index 1c013d116..9d1cb7a29 100644
--- a/tests/type_propagation/gold/literal-test.gold
+++ b/tests/type_propagation/gold/literal-test.gold
@@ -4,15 +4,15 @@ main tests/type_propagation/literal-test.toit
   4[053] - invoke static get-string tests/type_propagation/literal-test.toit // {String_}
   7[041] - pop 1
   8[053] - invoke static get-smi-or-string tests/type_propagation/literal-test.toit // {String_|SmallInteger_}
- 11[089] - return null S1 0
+ 11[091] - return null S1 0
 
 get-smi tests/type_propagation/literal-test.toit
   0[026] - load smi 42
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 get-string tests/type_propagation/literal-test.toit
   0[020] - load literal hest
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 get-smi-or-string tests/type_propagation/literal-test.toit
   0[053] - invoke static get-smi tests/type_propagation/literal-test.toit // {SmallInteger_}
@@ -21,6 +21,6 @@ get-smi-or-string tests/type_propagation/literal-test.toit
   5[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
   6[082] - branch if false T13
   9[014] - load local 0
- 10[088] - return S2 0
+ 10[090] - return S2 0
  13[053] - invoke static get-string tests/type_propagation/literal-test.toit // {String_}
- 16[088] - return S2 0
+ 16[090] - return S2 0
diff --git a/tests/type_propagation/gold/literal-test.gold-O2 b/tests/type_propagation/gold/literal-test.gold-O2
index 1c013d116..9d1cb7a29 100644
--- a/tests/type_propagation/gold/literal-test.gold-O2
+++ b/tests/type_propagation/gold/literal-test.gold-O2
@@ -4,15 +4,15 @@ main tests/type_propagation/literal-test.toit
   4[053] - invoke static get-string tests/type_propagation/literal-test.toit // {String_}
   7[041] - pop 1
   8[053] - invoke static get-smi-or-string tests/type_propagation/literal-test.toit // {String_|SmallInteger_}
- 11[089] - return null S1 0
+ 11[091] - return null S1 0
 
 get-smi tests/type_propagation/literal-test.toit
   0[026] - load smi 42
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 get-string tests/type_propagation/literal-test.toit
   0[020] - load literal hest
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 get-smi-or-string tests/type_propagation/literal-test.toit
   0[053] - invoke static get-smi tests/type_propagation/literal-test.toit // {SmallInteger_}
@@ -21,6 +21,6 @@ get-smi-or-string tests/type_propagation/literal-test.toit
   5[062] - invoke eq // [{SmallInteger_}, {SmallInteger_}] -> {True_|False_}
   6[082] - branch if false T13
   9[014] - load local 0
- 10[088] - return S2 0
+ 10[090] - return S2 0
  13[053] - invoke static get-string tests/type_propagation/literal-test.toit // {String_}
- 16[088] - return S2 0
+ 16[090] - return S2 0
diff --git a/tests/type_propagation/gold/local-test.gold b/tests/type_propagation/gold/local-test.gold
index a920e7435..7015317fc 100644
--- a/tests/type_propagation/gold/local-test.gold
+++ b/tests/type_propagation/gold/local-test.gold
@@ -12,7 +12,7 @@ main tests/type_propagation/local-test.toit
  20[053] - invoke static test-loop-break tests/type_propagation/local-test.toit // {Null_}
  23[041] - pop 1
  24[053] - invoke static test-loop-continue tests/type_propagation/local-test.toit // {Null_}
- 27[089] - return null S1 0
+ 27[091] - return null S1 0
 
 test-if tests/type_propagation/local-test.toit
   0[023] - load smi 0
@@ -27,7 +27,7 @@ test-if tests/type_propagation/local-test.toit
  18[004] - store local, pop S1
  20[014] - load local 0
  21[053] - invoke static id tests/type_propagation/local-test.toit // [{SmallInteger_}] -> {SmallInteger_}
- 24[089] - return null S2 0
+ 24[091] - return null S2 0
 
 test-if-else tests/type_propagation/local-test.toit
   0[023] - load smi 0
@@ -47,7 +47,7 @@ test-if-else tests/type_propagation/local-test.toit
  31[004] - store local, pop S1
  33[014] - load local 0
  34[053] - invoke static id tests/type_propagation/local-test.toit // [{String_|True_}] -> {String_|True_}
- 37[089] - return null S2 0
+ 37[091] - return null S2 0
 
 test-if-nested tests/type_propagation/local-test.toit
   0[022] - load null
@@ -76,7 +76,7 @@ test-if-nested tests/type_propagation/local-test.toit
  53[041] - pop 1
  54[014] - load local 0
  55[053] - invoke static id tests/type_propagation/local-test.toit // [{True_|False_|float|SmallInteger_}] -> {True_|False_|float|SmallInteger_}
- 58[089] - return null S2 0
+ 58[091] - return null S2 0
 
 test-if-more-locals tests/type_propagation/local-test.toit
   0[023] - load smi 0
@@ -108,7 +108,7 @@ test-if-more-locals tests/type_propagation/local-test.toit
  57[053] - invoke static id tests/type_propagation/local-test.toit // [{float}] -> {float}
  60[002] - pop, load local S0
  62[053] - invoke static id tests/type_propagation/local-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
- 65[089] - return null S5 0
+ 65[091] - return null S5 0
 
 test-loop-simple tests/type_propagation/local-test.toit
   0[022] - load null
@@ -119,10 +119,10 @@ test-loop-simple tests/type_propagation/local-test.toit
  11[014] - load local 0
  12[053] - invoke static id tests/type_propagation/local-test.toit // [{SmallInteger_}] -> {SmallInteger_}
  15[041] - pop 1
- 16[083] - branch back T1
+ 16[084] - branch back T1
  21[014] - load local 0
  22[053] - invoke static id tests/type_propagation/local-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
- 25[089] - return null S2 0
+ 25[091] - return null S2 0
 
 test-loop-break tests/type_propagation/local-test.toit
   0[022] - load null
@@ -131,7 +131,7 @@ test-loop-break tests/type_propagation/local-test.toit
   5[053] - invoke static pick tests/type_propagation/local-test.toit // {True_|False_}
   8[082] - branch if false T14
  11[080] - branch T19
- 14[083] - branch back T1
+ 14[084] - branch back T1
  19[014] - load local 0
  20[053] - invoke static id tests/type_propagation/local-test.toit // [{SmallInteger_}] -> {SmallInteger_}
  23[041] - pop 1
@@ -148,12 +148,12 @@ test-loop-break tests/type_propagation/local-test.toit
  48[014] - load local 0
  49[053] - invoke static id tests/type_propagation/local-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
  52[041] - pop 1
- 53[083] - branch back T25
+ 53[084] - branch back T25
  58[015] - load local 1
  59[053] - invoke static id tests/type_propagation/local-test.toit // [{SmallInteger_}] -> {SmallInteger_}
  62[002] - pop, load local S0
  64[053] - invoke static id tests/type_propagation/local-test.toit // [{String_}] -> {String_}
- 67[089] - return null S3 0
+ 67[091] - return null S3 0
 
 test-loop-continue tests/type_propagation/local-test.toit
   0[022] - load null
@@ -162,7 +162,7 @@ test-loop-continue tests/type_propagation/local-test.toit
   7[026] - load smi 2
   9[004] - store local, pop S1
  11[080] - branch T14
- 14[083] - branch back T1
+ 14[084] - branch back T1
  19[014] - load local 0
  20[053] - invoke static id tests/type_propagation/local-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
  23[041] - pop 1
@@ -177,21 +177,21 @@ test-loop-continue tests/type_propagation/local-test.toit
  44[080] - branch T51
  47[026] - load smi 42
  49[004] - store local, pop S1
- 51[083] - branch back T25
+ 51[084] - branch back T25
  56[015] - load local 1
  57[053] - invoke static id tests/type_propagation/local-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
  60[002] - pop, load local S0
  62[053] - invoke static id tests/type_propagation/local-test.toit // [{String_|Null_|SmallInteger_}] -> {String_|Null_|SmallInteger_}
- 65[089] - return null S3 0
+ 65[091] - return null S3 0
 
 id tests/type_propagation/local-test.toit
  - argument 0: {String_|Null_|True_|False_|float|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 pick tests/type_propagation/local-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
diff --git a/tests/type_propagation/gold/local-test.gold-O2 b/tests/type_propagation/gold/local-test.gold-O2
index a920e7435..7015317fc 100644
--- a/tests/type_propagation/gold/local-test.gold-O2
+++ b/tests/type_propagation/gold/local-test.gold-O2
@@ -12,7 +12,7 @@ main tests/type_propagation/local-test.toit
  20[053] - invoke static test-loop-break tests/type_propagation/local-test.toit // {Null_}
  23[041] - pop 1
  24[053] - invoke static test-loop-continue tests/type_propagation/local-test.toit // {Null_}
- 27[089] - return null S1 0
+ 27[091] - return null S1 0
 
 test-if tests/type_propagation/local-test.toit
   0[023] - load smi 0
@@ -27,7 +27,7 @@ test-if tests/type_propagation/local-test.toit
  18[004] - store local, pop S1
  20[014] - load local 0
  21[053] - invoke static id tests/type_propagation/local-test.toit // [{SmallInteger_}] -> {SmallInteger_}
- 24[089] - return null S2 0
+ 24[091] - return null S2 0
 
 test-if-else tests/type_propagation/local-test.toit
   0[023] - load smi 0
@@ -47,7 +47,7 @@ test-if-else tests/type_propagation/local-test.toit
  31[004] - store local, pop S1
  33[014] - load local 0
  34[053] - invoke static id tests/type_propagation/local-test.toit // [{String_|True_}] -> {String_|True_}
- 37[089] - return null S2 0
+ 37[091] - return null S2 0
 
 test-if-nested tests/type_propagation/local-test.toit
   0[022] - load null
@@ -76,7 +76,7 @@ test-if-nested tests/type_propagation/local-test.toit
  53[041] - pop 1
  54[014] - load local 0
  55[053] - invoke static id tests/type_propagation/local-test.toit // [{True_|False_|float|SmallInteger_}] -> {True_|False_|float|SmallInteger_}
- 58[089] - return null S2 0
+ 58[091] - return null S2 0
 
 test-if-more-locals tests/type_propagation/local-test.toit
   0[023] - load smi 0
@@ -108,7 +108,7 @@ test-if-more-locals tests/type_propagation/local-test.toit
  57[053] - invoke static id tests/type_propagation/local-test.toit // [{float}] -> {float}
  60[002] - pop, load local S0
  62[053] - invoke static id tests/type_propagation/local-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
- 65[089] - return null S5 0
+ 65[091] - return null S5 0
 
 test-loop-simple tests/type_propagation/local-test.toit
   0[022] - load null
@@ -119,10 +119,10 @@ test-loop-simple tests/type_propagation/local-test.toit
  11[014] - load local 0
  12[053] - invoke static id tests/type_propagation/local-test.toit // [{SmallInteger_}] -> {SmallInteger_}
  15[041] - pop 1
- 16[083] - branch back T1
+ 16[084] - branch back T1
  21[014] - load local 0
  22[053] - invoke static id tests/type_propagation/local-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
- 25[089] - return null S2 0
+ 25[091] - return null S2 0
 
 test-loop-break tests/type_propagation/local-test.toit
   0[022] - load null
@@ -131,7 +131,7 @@ test-loop-break tests/type_propagation/local-test.toit
   5[053] - invoke static pick tests/type_propagation/local-test.toit // {True_|False_}
   8[082] - branch if false T14
  11[080] - branch T19
- 14[083] - branch back T1
+ 14[084] - branch back T1
  19[014] - load local 0
  20[053] - invoke static id tests/type_propagation/local-test.toit // [{SmallInteger_}] -> {SmallInteger_}
  23[041] - pop 1
@@ -148,12 +148,12 @@ test-loop-break tests/type_propagation/local-test.toit
  48[014] - load local 0
  49[053] - invoke static id tests/type_propagation/local-test.toit // [{String_|SmallInteger_}] -> {String_|SmallInteger_}
  52[041] - pop 1
- 53[083] - branch back T25
+ 53[084] - branch back T25
  58[015] - load local 1
  59[053] - invoke static id tests/type_propagation/local-test.toit // [{SmallInteger_}] -> {SmallInteger_}
  62[002] - pop, load local S0
  64[053] - invoke static id tests/type_propagation/local-test.toit // [{String_}] -> {String_}
- 67[089] - return null S3 0
+ 67[091] - return null S3 0
 
 test-loop-continue tests/type_propagation/local-test.toit
   0[022] - load null
@@ -162,7 +162,7 @@ test-loop-continue tests/type_propagation/local-test.toit
   7[026] - load smi 2
   9[004] - store local, pop S1
  11[080] - branch T14
- 14[083] - branch back T1
+ 14[084] - branch back T1
  19[014] - load local 0
  20[053] - invoke static id tests/type_propagation/local-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
  23[041] - pop 1
@@ -177,21 +177,21 @@ test-loop-continue tests/type_propagation/local-test.toit
  44[080] - branch T51
  47[026] - load smi 42
  49[004] - store local, pop S1
- 51[083] - branch back T25
+ 51[084] - branch back T25
  56[015] - load local 1
  57[053] - invoke static id tests/type_propagation/local-test.toit // [{Null_|SmallInteger_}] -> {Null_|SmallInteger_}
  60[002] - pop, load local S0
  62[053] - invoke static id tests/type_propagation/local-test.toit // [{String_|Null_|SmallInteger_}] -> {String_|Null_|SmallInteger_}
- 65[089] - return null S3 0
+ 65[091] - return null S3 0
 
 id tests/type_propagation/local-test.toit
  - argument 0: {String_|Null_|True_|False_|float|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 pick tests/type_propagation/local-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
diff --git a/tests/type_propagation/gold/map-test.gold b/tests/type_propagation/gold/map-test.gold
index 168d716b0..c998ea0a3 100644
--- a/tests/type_propagation/gold/map-test.gold
+++ b/tests/type_propagation/gold/map-test.gold
@@ -1,6 +1,6 @@
 main tests/type_propagation/map-test.toit
   0[053] - invoke static test-simple tests/type_propagation/map-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 test-simple tests/type_propagation/map-test.toit
   0[042] - allocate instance Map
@@ -9,9 +9,9 @@ test-simple tests/type_propagation/map-test.toit
   6[004] - store local, pop S1
   8[009] - load field local 48 // [{Map}] -> {Null_|List_|SmallArray_}
  10[053] - invoke static id tests/type_propagation/map-test.toit // [{Null_|List_|SmallArray_}] -> {Null_|List_|SmallArray_}
- 13[089] - return null S2 0
+ 13[091] - return null S2 0
 
 id tests/type_propagation/map-test.toit
  - argument 0: {Null_|List_|SmallArray_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/map-test.gold-O2 b/tests/type_propagation/gold/map-test.gold-O2
index 168d716b0..c998ea0a3 100644
--- a/tests/type_propagation/gold/map-test.gold-O2
+++ b/tests/type_propagation/gold/map-test.gold-O2
@@ -1,6 +1,6 @@
 main tests/type_propagation/map-test.toit
   0[053] - invoke static test-simple tests/type_propagation/map-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 test-simple tests/type_propagation/map-test.toit
   0[042] - allocate instance Map
@@ -9,9 +9,9 @@ test-simple tests/type_propagation/map-test.toit
   6[004] - store local, pop S1
   8[009] - load field local 48 // [{Map}] -> {Null_|List_|SmallArray_}
  10[053] - invoke static id tests/type_propagation/map-test.toit // [{Null_|List_|SmallArray_}] -> {Null_|List_|SmallArray_}
- 13[089] - return null S2 0
+ 13[091] - return null S2 0
 
 id tests/type_propagation/map-test.toit
  - argument 0: {Null_|List_|SmallArray_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/nlr-test.gold b/tests/type_propagation/gold/nlr-test.gold
index 799e9155d..feb09d08a 100644
--- a/tests/type_propagation/gold/nlr-test.gold
+++ b/tests/type_propagation/gold/nlr-test.gold
@@ -2,19 +2,19 @@ main tests/type_propagation/nlr-test.toit
   0[053] - invoke static test-simple tests/type_propagation/nlr-test.toit // {Null_}
   3[041] - pop 1
   4[053] - invoke static test-try tests/type_propagation/nlr-test.toit // {Null_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 test-simple tests/type_propagation/nlr-test.toit
   0[053] - invoke static always-return tests/type_propagation/nlr-test.toit // {SmallInteger_}
   3[041] - pop 1
   4[053] - invoke static maybe-return tests/type_propagation/nlr-test.toit // {String_|SmallInteger_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 test-try tests/type_propagation/nlr-test.toit
   0[053] - invoke static stop-unwinding tests/type_propagation/nlr-test.toit // {String_|float|SmallInteger_}
   3[041] - pop 1
   4[053] - invoke static stop-unwinding-alternative tests/type_propagation/nlr-test.toit // {String_|True_|float|SmallInteger_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 always-return tests/type_propagation/nlr-test.toit
   0[029] - load method [block] in always-return tests/type_propagation/nlr-test.toit
@@ -28,8 +28,8 @@ always-return tests/type_propagation/nlr-test.toit
  - argument 0: [block]
   0[026] - load smi 42
   2[017] - load local 3
-  3[090] - non-local return 0
-  5[088] - return S1 1
+  3[092] - non-local return 0
+  5[090] - return S1 1
 
 maybe-return tests/type_propagation/nlr-test.toit
   0[029] - load method [block] in maybe-return tests/type_propagation/nlr-test.toit
@@ -37,7 +37,7 @@ maybe-return tests/type_propagation/nlr-test.toit
   7[053] - invoke static invoke tests/type_propagation/nlr-test.toit // [[block]] -> {Null_}
  10[040] - pop 2
  12[020] - load literal hest
- 14[088] - return S1 0
+ 14[090] - return S1 0
 
 [block] in maybe-return tests/type_propagation/nlr-test.toit
  - argument 0: [block]
@@ -47,20 +47,20 @@ maybe-return tests/type_propagation/nlr-test.toit
   7[041] - pop 1
   8[026] - load smi 42
  10[017] - load local 3
- 11[090] - non-local return 0
- 13[088] - return S1 1
+ 11[092] - non-local return 0
+ 13[090] - return S1 1
 
 stop-unwinding tests/type_propagation/nlr-test.toit
   0[026] - load smi 42
   2[029] - load method [block] in stop-unwinding tests/type_propagation/nlr-test.toit
-  7[094] - link try 0
+  7[096] - link try 0
   9[038] - load block 4
  11[055] - invoke block S1 // [[block]] -> {}
  13[041] - pop 1
- 14[095] - unlink try 0
+ 14[097] - unlink try 0
  16[018] - load local 4
- 17[088] - return S6 0
- 20[096] - unwind
+ 17[090] - return S6 0
+ 20[098] - unwind
  21[041] - pop 1
 
 [block] in stop-unwinding tests/type_propagation/nlr-test.toit
@@ -79,27 +79,27 @@ stop-unwinding tests/type_propagation/nlr-test.toit
  22[002] - pop, load local S2
  24[020] - load literal true
  26[006] - store outer S1
- 28[088] - return S1 1
+ 28[090] - return S1 1
 
 [block] in [block] in stop-unwinding tests/type_propagation/nlr-test.toit
  - argument 0: [block]
   0[020] - load literal hest
   2[017] - load local 3
   3[005] - load outer S3 // [block]
-  5[090] - non-local return 16
-  7[088] - return S1 1
+  5[092] - non-local return 16
+  7[090] - return S1 1
 
 stop-unwinding-alternative tests/type_propagation/nlr-test.toit
   0[026] - load smi 42
   2[029] - load method [block] in stop-unwinding-alternative tests/type_propagation/nlr-test.toit
-  7[094] - link try 0
+  7[096] - link try 0
   9[038] - load block 4
  11[055] - invoke block S1 // [[block]] -> {True_}
  13[041] - pop 1
- 14[095] - unlink try 0
+ 14[097] - unlink try 0
  16[018] - load local 4
- 17[088] - return S6 0
- 20[096] - unwind
+ 17[090] - return S6 0
+ 20[098] - unwind
  21[041] - pop 1
 
 [block] in stop-unwinding-alternative tests/type_propagation/nlr-test.toit
@@ -115,7 +115,7 @@ stop-unwinding-alternative tests/type_propagation/nlr-test.toit
  17[002] - pop, load local S2
  19[020] - load literal true
  21[006] - store outer S1
- 23[088] - return S1 1
+ 23[090] - return S1 1
 
 [block] in [block] in stop-unwinding-alternative tests/type_propagation/nlr-test.toit
  - argument 0: [block]
@@ -126,18 +126,18 @@ stop-unwinding-alternative tests/type_propagation/nlr-test.toit
   8[020] - load literal hest
  10[017] - load local 3
  11[005] - load outer S3 // [block]
- 13[090] - non-local return 16
- 15[088] - return S1 1
+ 13[092] - non-local return 16
+ 15[090] - return S1 1
 
 pick tests/type_propagation/nlr-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 invoke tests/type_propagation/nlr-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {Null_}
-  3[088] - return S1 1
+  3[090] - return S1 1
diff --git a/tests/type_propagation/gold/nlr-test.gold-O2 b/tests/type_propagation/gold/nlr-test.gold-O2
index b97543640..848d946cf 100644
--- a/tests/type_propagation/gold/nlr-test.gold-O2
+++ b/tests/type_propagation/gold/nlr-test.gold-O2
@@ -2,19 +2,19 @@ main tests/type_propagation/nlr-test.toit
   0[053] - invoke static test-simple tests/type_propagation/nlr-test.toit // {Null_}
   3[041] - pop 1
   4[053] - invoke static test-try tests/type_propagation/nlr-test.toit // {Null_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 test-simple tests/type_propagation/nlr-test.toit
   0[053] - invoke static always-return tests/type_propagation/nlr-test.toit // {SmallInteger_}
   3[041] - pop 1
   4[053] - invoke static maybe-return tests/type_propagation/nlr-test.toit // {String_|SmallInteger_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 test-try tests/type_propagation/nlr-test.toit
   0[053] - invoke static stop-unwinding tests/type_propagation/nlr-test.toit // {String_|float|SmallInteger_}
   3[041] - pop 1
   4[053] - invoke static stop-unwinding-alternative tests/type_propagation/nlr-test.toit // {String_|True_|float|SmallInteger_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 always-return tests/type_propagation/nlr-test.toit
   0[029] - load method [block] in always-return tests/type_propagation/nlr-test.toit
@@ -26,8 +26,8 @@ always-return tests/type_propagation/nlr-test.toit
  - argument 0: [block]
   0[026] - load smi 42
   2[017] - load local 3
-  3[090] - non-local return 0
-  5[088] - return S1 1
+  3[092] - non-local return 0
+  5[090] - return S1 1
 
 maybe-return tests/type_propagation/nlr-test.toit
   0[029] - load method [block] in maybe-return tests/type_propagation/nlr-test.toit
@@ -35,7 +35,7 @@ maybe-return tests/type_propagation/nlr-test.toit
   7[053] - invoke static invoke tests/type_propagation/nlr-test.toit // [[block]] -> {Null_}
  10[040] - pop 2
  12[020] - load literal hest
- 14[088] - return S1 0
+ 14[090] - return S1 0
 
 [block] in maybe-return tests/type_propagation/nlr-test.toit
  - argument 0: [block]
@@ -45,20 +45,20 @@ maybe-return tests/type_propagation/nlr-test.toit
   7[041] - pop 1
   8[026] - load smi 42
  10[017] - load local 3
- 11[090] - non-local return 0
- 13[088] - return S1 1
+ 11[092] - non-local return 0
+ 13[090] - return S1 1
 
 stop-unwinding tests/type_propagation/nlr-test.toit
   0[026] - load smi 42
   2[029] - load method [block] in stop-unwinding tests/type_propagation/nlr-test.toit
-  7[094] - link try 0
+  7[096] - link try 0
   9[038] - load block 4
  11[055] - invoke block S1 // [[block]] -> {}
  13[041] - pop 1
- 14[095] - unlink try 0
+ 14[097] - unlink try 0
  16[018] - load local 4
- 17[088] - return S6 0
- 20[096] - unwind
+ 17[090] - return S6 0
+ 20[098] - unwind
  21[041] - pop 1
 
 [block] in stop-unwinding tests/type_propagation/nlr-test.toit
@@ -74,27 +74,27 @@ stop-unwinding tests/type_propagation/nlr-test.toit
  16[038] - load block 0
  18[053] - invoke static invoke tests/type_propagation/nlr-test.toit // [[block]] -> {}
  21[004] - store local, pop S1
- 23[088] - return S1 1
+ 23[090] - return S1 1
 
 [block] in [block] in stop-unwinding tests/type_propagation/nlr-test.toit
  - argument 0: [block]
   0[020] - load literal hest
   2[017] - load local 3
   3[005] - load outer S3 // [block]
-  5[090] - non-local return 16
-  7[088] - return S1 1
+  5[092] - non-local return 16
+  7[090] - return S1 1
 
 stop-unwinding-alternative tests/type_propagation/nlr-test.toit
   0[026] - load smi 42
   2[029] - load method [block] in stop-unwinding-alternative tests/type_propagation/nlr-test.toit
-  7[094] - link try 0
+  7[096] - link try 0
   9[038] - load block 4
  11[055] - invoke block S1 // [[block]] -> {True_}
  13[041] - pop 1
- 14[095] - unlink try 0
+ 14[097] - unlink try 0
  16[018] - load local 4
- 17[088] - return S6 0
- 20[096] - unwind
+ 17[090] - return S6 0
+ 20[098] - unwind
  21[041] - pop 1
 
 [block] in stop-unwinding-alternative tests/type_propagation/nlr-test.toit
@@ -110,7 +110,7 @@ stop-unwinding-alternative tests/type_propagation/nlr-test.toit
  17[002] - pop, load local S2
  19[020] - load literal true
  21[006] - store outer S1
- 23[088] - return S1 1
+ 23[090] - return S1 1
 
 [block] in [block] in stop-unwinding-alternative tests/type_propagation/nlr-test.toit
  - argument 0: [block]
@@ -121,18 +121,18 @@ stop-unwinding-alternative tests/type_propagation/nlr-test.toit
   8[020] - load literal hest
  10[017] - load local 3
  11[005] - load outer S3 // [block]
- 13[090] - non-local return 16
- 15[088] - return S1 1
+ 13[092] - non-local return 16
+ 15[090] - return S1 1
 
 pick tests/type_propagation/nlr-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 invoke tests/type_propagation/nlr-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {Null_}
-  3[088] - return S1 1
+  3[090] - return S1 1
diff --git a/tests/type_propagation/gold/non-local-branch-test.gold b/tests/type_propagation/gold/non-local-branch-test.gold
index 500ce2852..80ee2bf02 100644
--- a/tests/type_propagation/gold/non-local-branch-test.gold
+++ b/tests/type_propagation/gold/non-local-branch-test.gold
@@ -4,7 +4,7 @@ main tests/type_propagation/non-local-branch-test.toit
   4[053] - invoke static test-continue tests/type_propagation/non-local-branch-test.toit // {Null_}
   7[041] - pop 1
   8[053] - invoke static test-nested tests/type_propagation/non-local-branch-test.toit // {Null_}
- 11[089] - return null S1 0
+ 11[091] - return null S1 0
 
 test-break tests/type_propagation/non-local-branch-test.toit
   0[026] - load smi 42
@@ -12,10 +12,10 @@ test-break tests/type_propagation/non-local-branch-test.toit
   7[038] - load block 0
   9[053] - invoke static invoke tests/type_propagation/non-local-branch-test.toit // [[block]] -> {}
  12[040] - pop 2
- 14[083] - branch back T2
+ 14[084] - branch back T2
  19[014] - load local 0
  20[053] - invoke static id tests/type_propagation/non-local-branch-test.toit // [{String_}] -> {String_}
- 23[089] - return null S2 0
+ 23[091] - return null S2 0
 
 [block] in test-break tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
@@ -23,8 +23,8 @@ test-break tests/type_propagation/non-local-branch-test.toit
   1[020] - load literal hest
   3[006] - store outer S1
   5[002] - pop, load local S2
-  7[092] - non-local branch {test-break:19}
- 13[088] - return S1 1
+  7[094] - non-local branch {test-break:19}
+ 13[090] - return S1 1
 
 test-continue tests/type_propagation/non-local-branch-test.toit
   0[026] - load smi 42
@@ -32,10 +32,10 @@ test-continue tests/type_propagation/non-local-branch-test.toit
   7[038] - load block 0
   9[053] - invoke static invoke tests/type_propagation/non-local-branch-test.toit // [[block]] -> {}
  12[040] - pop 2
- 14[083] - branch back T2
+ 14[084] - branch back T2
  19[014] - load local 0
  20[053] - invoke static id tests/type_propagation/non-local-branch-test.toit // [{float}] -> {float}
- 23[089] - return null S2 0
+ 23[091] - return null S2 0
 
 [block] in test-continue tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
@@ -46,19 +46,19 @@ test-continue tests/type_propagation/non-local-branch-test.toit
   6[053] - invoke static pick tests/type_propagation/non-local-branch-test.toit // {True_|False_}
   9[082] - branch if false T19
  12[016] - load local 2
- 13[092] - non-local branch {test-continue:14}
+ 13[094] - non-local branch {test-continue:14}
  19[016] - load local 2
  20[020] - load literal 3.2999999999999998224
  22[006] - store outer S1
  24[002] - pop, load local S2
- 26[092] - non-local branch {test-continue:19}
- 32[088] - return S1 1
+ 26[094] - non-local branch {test-continue:19}
+ 32[090] - return S1 1
 
 test-nested tests/type_propagation/non-local-branch-test.toit
   0[029] - load method [block] in test-nested tests/type_propagation/non-local-branch-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/non-local-branch-test.toit // [[block]] -> {Null_}
- 10[089] - return null S2 0
+ 10[091] - return null S2 0
 
 [block] in test-nested tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
@@ -66,30 +66,30 @@ test-nested tests/type_propagation/non-local-branch-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/non-local-branch-test.toit // [[block]] -> {}
  10[040] - pop 2
- 12[083] - branch back T0
+ 12[084] - branch back T0
  17[022] - load null
- 18[088] - return S1 1
+ 18[090] - return S1 1
 
 [block] in [block] in test-nested tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
   0[016] - load local 2
-  1[092] - non-local branch {[block] in test-nested:17}
-  7[088] - return S1 1
+  1[094] - non-local branch {[block] in test-nested:17}
+  7[090] - return S1 1
 
 id tests/type_propagation/non-local-branch-test.toit
  - argument 0: {String_|float}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 pick tests/type_propagation/non-local-branch-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 invoke tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {Null_}
-  3[089] - return null S1 1
+  3[091] - return null S1 1
diff --git a/tests/type_propagation/gold/non-local-branch-test.gold-O2 b/tests/type_propagation/gold/non-local-branch-test.gold-O2
index 500ce2852..80ee2bf02 100644
--- a/tests/type_propagation/gold/non-local-branch-test.gold-O2
+++ b/tests/type_propagation/gold/non-local-branch-test.gold-O2
@@ -4,7 +4,7 @@ main tests/type_propagation/non-local-branch-test.toit
   4[053] - invoke static test-continue tests/type_propagation/non-local-branch-test.toit // {Null_}
   7[041] - pop 1
   8[053] - invoke static test-nested tests/type_propagation/non-local-branch-test.toit // {Null_}
- 11[089] - return null S1 0
+ 11[091] - return null S1 0
 
 test-break tests/type_propagation/non-local-branch-test.toit
   0[026] - load smi 42
@@ -12,10 +12,10 @@ test-break tests/type_propagation/non-local-branch-test.toit
   7[038] - load block 0
   9[053] - invoke static invoke tests/type_propagation/non-local-branch-test.toit // [[block]] -> {}
  12[040] - pop 2
- 14[083] - branch back T2
+ 14[084] - branch back T2
  19[014] - load local 0
  20[053] - invoke static id tests/type_propagation/non-local-branch-test.toit // [{String_}] -> {String_}
- 23[089] - return null S2 0
+ 23[091] - return null S2 0
 
 [block] in test-break tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
@@ -23,8 +23,8 @@ test-break tests/type_propagation/non-local-branch-test.toit
   1[020] - load literal hest
   3[006] - store outer S1
   5[002] - pop, load local S2
-  7[092] - non-local branch {test-break:19}
- 13[088] - return S1 1
+  7[094] - non-local branch {test-break:19}
+ 13[090] - return S1 1
 
 test-continue tests/type_propagation/non-local-branch-test.toit
   0[026] - load smi 42
@@ -32,10 +32,10 @@ test-continue tests/type_propagation/non-local-branch-test.toit
   7[038] - load block 0
   9[053] - invoke static invoke tests/type_propagation/non-local-branch-test.toit // [[block]] -> {}
  12[040] - pop 2
- 14[083] - branch back T2
+ 14[084] - branch back T2
  19[014] - load local 0
  20[053] - invoke static id tests/type_propagation/non-local-branch-test.toit // [{float}] -> {float}
- 23[089] - return null S2 0
+ 23[091] - return null S2 0
 
 [block] in test-continue tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
@@ -46,19 +46,19 @@ test-continue tests/type_propagation/non-local-branch-test.toit
   6[053] - invoke static pick tests/type_propagation/non-local-branch-test.toit // {True_|False_}
   9[082] - branch if false T19
  12[016] - load local 2
- 13[092] - non-local branch {test-continue:14}
+ 13[094] - non-local branch {test-continue:14}
  19[016] - load local 2
  20[020] - load literal 3.2999999999999998224
  22[006] - store outer S1
  24[002] - pop, load local S2
- 26[092] - non-local branch {test-continue:19}
- 32[088] - return S1 1
+ 26[094] - non-local branch {test-continue:19}
+ 32[090] - return S1 1
 
 test-nested tests/type_propagation/non-local-branch-test.toit
   0[029] - load method [block] in test-nested tests/type_propagation/non-local-branch-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/non-local-branch-test.toit // [[block]] -> {Null_}
- 10[089] - return null S2 0
+ 10[091] - return null S2 0
 
 [block] in test-nested tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
@@ -66,30 +66,30 @@ test-nested tests/type_propagation/non-local-branch-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/non-local-branch-test.toit // [[block]] -> {}
  10[040] - pop 2
- 12[083] - branch back T0
+ 12[084] - branch back T0
  17[022] - load null
- 18[088] - return S1 1
+ 18[090] - return S1 1
 
 [block] in [block] in test-nested tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
   0[016] - load local 2
-  1[092] - non-local branch {[block] in test-nested:17}
-  7[088] - return S1 1
+  1[094] - non-local branch {[block] in test-nested:17}
+  7[090] - return S1 1
 
 id tests/type_propagation/non-local-branch-test.toit
  - argument 0: {String_|float}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 pick tests/type_propagation/non-local-branch-test.toit
   0[026] - load smi 100
   2[053] - invoke static random <sdk>/core/utils.toit // [{SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[026] - load smi 50
   7[063] - invoke lt // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  8[088] - return S1 0
+  8[090] - return S1 0
 
 invoke tests/type_propagation/non-local-branch-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {Null_}
-  3[089] - return null S1 1
+  3[091] - return null S1 1
diff --git a/tests/type_propagation/gold/non-local-return-test.gold b/tests/type_propagation/gold/non-local-return-test.gold
index 00061edbf..3a874765c 100644
--- a/tests/type_propagation/gold/non-local-return-test.gold
+++ b/tests/type_propagation/gold/non-local-return-test.gold
@@ -2,7 +2,7 @@ main tests/type_propagation/non-local-return-test.toit
   0[053] - invoke static test-simple tests/type_propagation/non-local-return-test.toit // {SmallInteger_}
   3[041] - pop 1
   4[053] - invoke static test-continue tests/type_propagation/non-local-return-test.toit // {Null_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 test-simple tests/type_propagation/non-local-return-test.toit
   0[029] - load method [block] in test-simple tests/type_propagation/non-local-return-test.toit
@@ -18,7 +18,7 @@ test-simple tests/type_propagation/non-local-return-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/non-local-return-test.toit // [[block]] -> {}
  10[004] - store local, pop S1
- 12[088] - return S1 1
+ 12[090] - return S1 1
 
 [block] in [block] in test-simple tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
@@ -27,7 +27,7 @@ test-simple tests/type_propagation/non-local-return-test.toit
   7[038] - load block 1
   9[058] - invoke virtual repeat // [{SmallInteger_}, [block]] -> {}
  13[004] - store local, pop S1
- 15[088] - return S1 1
+ 15[090] - return S1 1
 
 [block] in [block] in [block] in test-simple tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
@@ -35,14 +35,14 @@ test-simple tests/type_propagation/non-local-return-test.toit
   2[017] - load local 3
   3[005] - load outer S3 // [block]
   5[005] - load outer S3 // [block]
-  7[090] - non-local return 0
-  9[088] - return S1 1
+  7[092] - non-local return 0
+  9[090] - return S1 1
 
 test-continue tests/type_propagation/non-local-return-test.toit
   0[029] - load method [block] in test-continue tests/type_propagation/non-local-return-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/non-local-return-test.toit // [[block]] -> {String_}
- 10[089] - return null S2 0
+ 10[091] - return null S2 0
 
 [block] in test-continue tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
@@ -51,17 +51,17 @@ test-continue tests/type_propagation/non-local-return-test.toit
   7[038] - load block 1
   9[058] - invoke virtual repeat // [{SmallInteger_}, [block]] -> {}
  13[004] - store local, pop S1
- 15[088] - return S1 1
+ 15[090] - return S1 1
 
 [block] in [block] in test-continue tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
   0[020] - load literal hest
   2[017] - load local 3
-  3[090] - non-local return 1
-  5[088] - return S1 1
+  3[092] - non-local return 1
+  5[090] - return S1 1
 
 invoke tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {String_}
-  3[088] - return S1 1
+  3[090] - return S1 1
diff --git a/tests/type_propagation/gold/non-local-return-test.gold-O2 b/tests/type_propagation/gold/non-local-return-test.gold-O2
index 7f13ffbc9..33bc3fe89 100644
--- a/tests/type_propagation/gold/non-local-return-test.gold-O2
+++ b/tests/type_propagation/gold/non-local-return-test.gold-O2
@@ -2,7 +2,7 @@ main tests/type_propagation/non-local-return-test.toit
   0[053] - invoke static test-simple tests/type_propagation/non-local-return-test.toit // {SmallInteger_}
   3[041] - pop 1
   4[053] - invoke static test-continue tests/type_propagation/non-local-return-test.toit // {Null_}
-  7[089] - return null S1 0
+  7[091] - return null S1 0
 
 test-simple tests/type_propagation/non-local-return-test.toit
   0[029] - load method [block] in test-simple tests/type_propagation/non-local-return-test.toit
@@ -16,7 +16,7 @@ test-simple tests/type_propagation/non-local-return-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/non-local-return-test.toit // [[block]] -> {}
  10[004] - store local, pop S1
- 12[088] - return S1 1
+ 12[090] - return S1 1
 
 [block] in [block] in test-simple tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
@@ -25,7 +25,7 @@ test-simple tests/type_propagation/non-local-return-test.toit
   7[038] - load block 1
   9[058] - invoke virtual repeat // [{SmallInteger_}, [block]] -> {}
  13[004] - store local, pop S1
- 15[088] - return S1 1
+ 15[090] - return S1 1
 
 [block] in [block] in [block] in test-simple tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
@@ -33,14 +33,14 @@ test-simple tests/type_propagation/non-local-return-test.toit
   2[017] - load local 3
   3[005] - load outer S3 // [block]
   5[005] - load outer S3 // [block]
-  7[090] - non-local return 0
-  9[088] - return S1 1
+  7[092] - non-local return 0
+  9[090] - return S1 1
 
 test-continue tests/type_propagation/non-local-return-test.toit
   0[029] - load method [block] in test-continue tests/type_propagation/non-local-return-test.toit
   5[038] - load block 0
   7[053] - invoke static invoke tests/type_propagation/non-local-return-test.toit // [[block]] -> {String_}
- 10[089] - return null S2 0
+ 10[091] - return null S2 0
 
 [block] in test-continue tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
@@ -49,17 +49,17 @@ test-continue tests/type_propagation/non-local-return-test.toit
   7[038] - load block 1
   9[058] - invoke virtual repeat // [{SmallInteger_}, [block]] -> {}
  13[004] - store local, pop S1
- 15[088] - return S1 1
+ 15[090] - return S1 1
 
 [block] in [block] in test-continue tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
   0[020] - load literal hest
   2[017] - load local 3
-  3[090] - non-local return 1
-  5[088] - return S1 1
+  3[092] - non-local return 1
+  5[090] - return S1 1
 
 invoke tests/type_propagation/non-local-return-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[055] - invoke block S1 // [[block]] -> {String_}
-  3[088] - return S1 1
+  3[090] - return S1 1
diff --git a/tests/type_propagation/gold/null-equals-test.gold b/tests/type_propagation/gold/null-equals-test.gold
index 025c57a87..111f4dd25 100644
--- a/tests/type_propagation/gold/null-equals-test.gold
+++ b/tests/type_propagation/gold/null-equals-test.gold
@@ -58,24 +58,24 @@ main tests/type_propagation/null-equals-test.toit
 102[053] - invoke static A tests/type_propagation/null-equals-test.toit // [{A}] -> {A}
 105[062] - invoke eq // [{Null_}, {A}] -> {False_}
 106[053] - invoke static id tests/type_propagation/null-equals-test.toit // [{False_}] -> {False_}
-109[089] - return null S2 0
+109[091] - return null S2 0
 
 obfuscate-null tests/type_propagation/null-equals-test.toit
-  0[089] - return null S0 0
+  0[091] - return null S0 0
 
 A tests/type_propagation/null-equals-test.toit
  - argument 0: {A}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 A.== tests/type_propagation/null-equals-test.toit
  - argument 0: {A}
  - argument 1: {String_|Null_|SmallInteger_|A}
   0[052] - load local, as class, pop 2 - A(40 - 41) // {True_|False_}
   2[020] - load literal hest
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 id tests/type_propagation/null-equals-test.toit
  - argument 0: {String_|True_|False_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/null-equals-test.gold-O2 b/tests/type_propagation/gold/null-equals-test.gold-O2
index f945a1d57..63d19f81e 100644
--- a/tests/type_propagation/gold/null-equals-test.gold-O2
+++ b/tests/type_propagation/gold/null-equals-test.gold-O2
@@ -58,24 +58,24 @@ main tests/type_propagation/null-equals-test.toit
 102[053] - invoke static A tests/type_propagation/null-equals-test.toit // [{A}] -> {A}
 105[062] - invoke eq // [{Null_}, {A}] -> {False_}
 106[053] - invoke static id tests/type_propagation/null-equals-test.toit // [{False_}] -> {False_}
-109[089] - return null S2 0
+109[091] - return null S2 0
 
 obfuscate-null tests/type_propagation/null-equals-test.toit
-  0[089] - return null S0 0
+  0[091] - return null S0 0
 
 A tests/type_propagation/null-equals-test.toit
  - argument 0: {A}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
 
 A.== tests/type_propagation/null-equals-test.toit
  - argument 0: {A}
  - argument 1: {String_|Null_|SmallInteger_|A}
   0[052] - load local, as class, pop 2 - A(35 - 36) // {True_|False_}
   2[020] - load literal hest
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 id tests/type_propagation/null-equals-test.toit
  - argument 0: {String_|True_|False_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/richards-test.gold b/tests/type_propagation/gold/richards-test.gold
index 649dceb35..db2f87c7b 100644
--- a/tests/type_propagation/gold/richards-test.gold
+++ b/tests/type_propagation/gold/richards-test.gold
@@ -1,6 +1,6 @@
 main tests/type_propagation/richards-test.toit
   0[053] - invoke static run-richards tests/type_propagation/richards-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 run-richards tests/type_propagation/richards-test.toit
   0[042] - allocate instance Scheduler
@@ -96,7 +96,7 @@ run-richards tests/type_propagation/richards-test.toit
 171[029] - load method [block] in run-richards tests/type_propagation/richards-test.toit
 176[038] - load block 0
 178[053] - invoke static assert_ <sdk>/core/assert_.toit // [[block]] -> {Null_}
-181[089] - return null S4 0
+181[091] - return null S4 0
 
 [block] in run-richards tests/type_propagation/richards-test.toit
  - argument 0: [block]
@@ -105,7 +105,7 @@ run-richards tests/type_propagation/richards-test.toit
   3[007] - load field 0 // [{Scheduler}] -> {Null_|LargeInteger_|SmallInteger_}
   5[027] - load smi 23246
   8[062] - invoke eq // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  9[088] - return S1 1
+  9[090] - return S1 1
 
 [block] in run-richards tests/type_propagation/richards-test.toit
  - argument 0: [block]
@@ -114,7 +114,7 @@ run-richards tests/type_propagation/richards-test.toit
   3[007] - load field 1 // [{Scheduler}] -> {Null_|LargeInteger_|SmallInteger_}
   5[027] - load smi 9297
   8[062] - invoke eq // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  9[088] - return S1 1
+  9[090] - return S1 1
 
 Scheduler tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -130,7 +130,7 @@ Scheduler tests/type_propagation/richards-test.toit
  12[053] - invoke static List <sdk>/core/collections.toit // [{SmallInteger_}, {Null_}] -> {List_}
  15[013] - store field, pop 2
  17[016] - load local 2
- 18[088] - return S1 1
+ 18[090] - return S1 1
 
 Scheduler.add-idle-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -154,7 +154,7 @@ Scheduler.add-idle-task tests/type_propagation/richards-test.toit
  23[000] - load local S9
  25[053] - invoke static IdleTask tests/type_propagation/richards-test.toit // [{IdleTask}, {Scheduler}, {SmallInteger_}, {SmallInteger_}] -> {IdleTask}
  28[053] - invoke static Scheduler.add-running-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Null_}, {IdleTask}] -> {Null_}
- 31[089] - return null S1 5
+ 31[091] - return null S1 5
 
 Scheduler.add-worker-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -174,7 +174,7 @@ Scheduler.add-worker-task tests/type_propagation/richards-test.toit
  16[023] - load smi 0
  17[053] - invoke static WorkerTask tests/type_propagation/richards-test.toit // [{WorkerTask}, {Scheduler}, {SmallInteger_}, {SmallInteger_}] -> {WorkerTask}
  20[053] - invoke static Scheduler.add-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Packet}, {WorkerTask}] -> {Null_}
- 23[089] - return null S1 4
+ 23[091] - return null S1 4
 
 Scheduler.add-handler-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -192,7 +192,7 @@ Scheduler.add-handler-task tests/type_propagation/richards-test.toit
  12[000] - load local S10
  14[053] - invoke static HandlerTask tests/type_propagation/richards-test.toit // [{HandlerTask}, {Scheduler}] -> {HandlerTask}
  17[053] - invoke static Scheduler.add-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Packet}, {HandlerTask}] -> {Null_}
- 20[089] - return null S1 4
+ 20[091] - return null S1 4
 
 Scheduler.add-device-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -211,7 +211,7 @@ Scheduler.add-device-task tests/type_propagation/richards-test.toit
  14[000] - load local S10
  16[053] - invoke static DeviceTask tests/type_propagation/richards-test.toit // [{DeviceTask}, {Scheduler}] -> {DeviceTask}
  19[053] - invoke static Scheduler.add-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Null_}, {DeviceTask}] -> {Null_}
- 22[089] - return null S1 4
+ 22[091] - return null S1 4
 
 Scheduler.add-running-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -231,7 +231,7 @@ Scheduler.add-running-task tests/type_propagation/richards-test.toit
  17[053] - invoke static Scheduler.add-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Null_}, {IdleTask}] -> {Null_}
  20[010] - pop, load field local 70 // [{Scheduler}] -> {*}
  22[058] - invoke virtual set-running // [{*}] -> {Null_}
- 26[089] - return null S1 5
+ 26[091] - return null S1 5
 
 Scheduler.add-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -259,7 +259,7 @@ Scheduler.add-task tests/type_propagation/richards-test.toit
  34[000] - load local S6
  36[009] - load field local 72 // [{Scheduler}] -> {*}
  38[079] - invoke at_put // [{Null_|List_}, {SmallInteger_}, {*}] -> {*}
- 39[089] - return null S1 5
+ 39[091] - return null S1 5
 
 Scheduler.schedule tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -284,8 +284,8 @@ Scheduler.schedule tests/type_propagation/richards-test.toit
  39[009] - load field local 67 // [{Scheduler}] -> {*}
  41[058] - invoke virtual run // [{*}] -> {*}
  45[013] - store field, pop 4
- 47[083] - branch back T5
- 52[089] - return null S0 1
+ 47[084] - branch back T5
+ 52[091] - return null S0 1
 
 Scheduler.hold-current tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -299,14 +299,14 @@ Scheduler.hold-current tests/type_propagation/richards-test.toit
  10[058] - invoke virtual mark-as-held // [{*}] -> {Null_}
  14[010] - pop, load field local 66 // [{Scheduler}] -> {*}
  16[060] - invoke virtual get link // [{*}] -> {Null_|Packet|TaskControlBlock}
- 19[088] - return S1 1
+ 19[090] - return S1 1
 
 Scheduler.suspend-current tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
   0[009] - load field local 66 // [{Scheduler}] -> {*}
   2[058] - invoke virtual mark-as-suspended // [{*}] -> {Null_}
   6[010] - pop, load field local 66 // [{Scheduler}] -> {*}
-  8[088] - return S1 1
+  8[090] - return S1 1
 
 Scheduler.release tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -317,7 +317,7 @@ Scheduler.release tests/type_propagation/richards-test.toit
   4[014] - load local 0
   5[081] - branch if true T12
   8[014] - load local 0
-  9[088] - return S2 2
+  9[090] - return S2 2
  12[014] - load local 0
  13[058] - invoke virtual mark-as-not-held // [{*}] -> {Null_}
  17[002] - pop, load local S0
@@ -327,10 +327,10 @@ Scheduler.release tests/type_propagation/richards-test.toit
  27[064] - invoke gt // [{Null_|SmallInteger_}, {Null_|SmallInteger_}] -> {True_|False_}
  28[082] - branch if false T38
  31[014] - load local 0
- 32[088] - return S2 2
+ 32[090] - return S2 2
  35[080] - branch T43
  38[009] - load field local 68 // [{Scheduler}] -> {*}
- 40[088] - return S2 2
+ 40[090] - return S2 2
 
 Scheduler.queue tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -342,7 +342,7 @@ Scheduler.queue tests/type_propagation/richards-test.toit
   7[014] - load local 0
   8[081] - branch if true T15
  11[014] - load local 0
- 12[088] - return S2 2
+ 12[090] - return S2 2
  15[009] - load field local 4 // [{Scheduler}] -> {Null_|LargeInteger_|SmallInteger_}
  17[019] - load local 5
  18[015] - load local 1
@@ -361,27 +361,27 @@ Scheduler.queue tests/type_propagation/richards-test.toit
  38[009] - load field local 69 // [{Scheduler}] -> {*}
  40[019] - load local 5
  41[058] - invoke virtual check-priority-add // [{*}, {*}, {Packet}] -> {*}
- 45[088] - return S2 2
+ 45[090] - return S2 2
 
 STATE-NOT-HELD tests/type_propagation/richards-test.toit
   0[026] - load smi 4
   2[058] - invoke virtual ~ // [{SmallInteger_}] -> {SmallInteger_}
-  6[088] - return S1 0
+  6[090] - return S1 0
 
 TaskControlBlock.link tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
   0[009] - load field local 2 // [{TaskControlBlock}] -> {Null_|TaskControlBlock}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 TaskControlBlock.id tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
   0[009] - load field local 18 // [{TaskControlBlock}] -> {Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 TaskControlBlock.priority tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
   0[009] - load field local 34 // [{TaskControlBlock}] -> {Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 TaskControlBlock tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -421,7 +421,7 @@ TaskControlBlock tests/type_propagation/richards-test.toit
  52[048] - as class LargeInteger_(22 - 24) // {True_}
  54[013] - store field, pop 5
  56[000] - load local S7
- 58[088] - return S1 6
+ 58[090] - return S1 6
 
 TaskControlBlock.set-running tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -429,7 +429,7 @@ TaskControlBlock.set-running tests/type_propagation/richards-test.toit
   1[023] - load smi 0
   2[048] - as class LargeInteger_(22 - 24) // {True_}
   4[013] - store field, pop 5
-  6[089] - return null S0 1
+  6[091] - return null S0 1
 
 TaskControlBlock.mark-as-not-held tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -439,7 +439,7 @@ TaskControlBlock.mark-as-not-held tests/type_propagation/richards-test.toit
   5[069] - invoke bit and // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   6[048] - as class LargeInteger_(22 - 24) // {True_}
   8[013] - store field, pop 5
- 10[089] - return null S0 1
+ 10[091] - return null S0 1
 
 TaskControlBlock.mark-as-held tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -449,7 +449,7 @@ TaskControlBlock.mark-as-held tests/type_propagation/richards-test.toit
   5[067] - invoke bit or // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   6[048] - as class LargeInteger_(22 - 24) // {True_}
   8[013] - store field, pop 5
- 10[089] - return null S0 1
+ 10[091] - return null S0 1
 
 TaskControlBlock.is-held-or-suspended tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -467,7 +467,7 @@ TaskControlBlock.is-held-or-suspended tests/type_propagation/richards-test.toit
  21[010] - pop, load field local 82 // [{TaskControlBlock}] -> {Null_|LargeInteger_|SmallInteger_}
  23[026] - load smi 2
  25[062] - invoke eq // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
- 26[088] - return S1 1
+ 26[090] - return S1 1
 
 TaskControlBlock.mark-as-suspended tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -477,7 +477,7 @@ TaskControlBlock.mark-as-suspended tests/type_propagation/richards-test.toit
   5[067] - invoke bit or // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   6[048] - as class LargeInteger_(22 - 24) // {True_}
   8[013] - store field, pop 5
- 10[089] - return null S0 1
+ 10[091] - return null S0 1
 
 TaskControlBlock.mark-as-runnable tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -487,7 +487,7 @@ TaskControlBlock.mark-as-runnable tests/type_propagation/richards-test.toit
   4[067] - invoke bit or // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[048] - as class LargeInteger_(22 - 24) // {True_}
   7[013] - store field, pop 5
-  9[089] - return null S0 1
+  9[091] - return null S0 1
 
 TaskControlBlock.run tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -514,7 +514,7 @@ TaskControlBlock.run tests/type_propagation/richards-test.toit
  35[009] - load field local 67 // [{TaskControlBlock}] -> {Null_|HandlerTask|WorkerTask|DeviceTask|IdleTask}
  37[015] - load local 1
  38[058] - invoke virtual run // [{Null_|HandlerTask|WorkerTask|DeviceTask|IdleTask}, {Null_|Packet}] -> {*}
- 42[088] - return S2 1
+ 42[090] - return S2 1
 
 TaskControlBlock.check-priority-add tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -534,7 +534,7 @@ TaskControlBlock.check-priority-add tests/type_propagation/richards-test.toit
  21[064] - invoke gt // [{Null_|SmallInteger_}, {Null_|SmallInteger_}] -> {True_|False_}
  22[082] - branch if false T29
  25[018] - load local 4
- 26[088] - return S1 3
+ 26[090] - return S1 3
  29[080] - branch T44
  32[018] - load local 4
  33[017] - load local 3
@@ -543,7 +543,7 @@ TaskControlBlock.check-priority-add tests/type_propagation/richards-test.toit
  40[048] - as class Packet?(40 - 41) // {True_}
  42[013] - store field, pop 3
  44[017] - load local 3
- 45[088] - return S1 3
+ 45[090] - return S1 3
 
 IdleTask tests/type_propagation/richards-test.toit
  - argument 0: {IdleTask}
@@ -563,7 +563,7 @@ IdleTask tests/type_propagation/richards-test.toit
  14[048] - as class LargeInteger_(22 - 24) // {True_}
  16[013] - store field, pop 2
  18[019] - load local 5
- 19[088] - return S1 4
+ 19[090] - return S1 4
 
 IdleTask.run tests/type_propagation/richards-test.toit
  - argument 0: {IdleTask}
@@ -581,7 +581,7 @@ IdleTask.run tests/type_propagation/richards-test.toit
  14[082] - branch if false T25
  17[009] - load field local 3 // [{IdleTask}] -> {Null_|Scheduler}
  19[053] - invoke static Scheduler.hold-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {Null_|Packet|TaskControlBlock}
- 22[088] - return S1 2
+ 22[090] - return S1 2
  25[009] - load field local 19 // [{IdleTask}] -> {Null_|LargeInteger_|SmallInteger_}
  27[025] - load smi 1
  28[069] - invoke bit and // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
@@ -597,7 +597,7 @@ IdleTask.run tests/type_propagation/richards-test.toit
  43[009] - load field local 3 // [{IdleTask}] -> {Null_|Scheduler}
  45[026] - load smi 4
  47[053] - invoke static Scheduler.release tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {SmallInteger_}] -> {*}
- 50[088] - return S1 2
+ 50[090] - return S1 2
  53[080] - branch T79
  56[017] - load local 3
  57[009] - load field local 20 // [{IdleTask}] -> {Null_|LargeInteger_|SmallInteger_}
@@ -610,7 +610,7 @@ IdleTask.run tests/type_propagation/richards-test.toit
  69[009] - load field local 3 // [{IdleTask}] -> {Null_|Scheduler}
  71[026] - load smi 5
  73[053] - invoke static Scheduler.release tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {SmallInteger_}] -> {*}
- 76[088] - return S1 2
+ 76[090] - return S1 2
 
 DeviceTask tests/type_propagation/richards-test.toit
  - argument 0: {DeviceTask}
@@ -620,7 +620,7 @@ DeviceTask tests/type_propagation/richards-test.toit
   2[048] - as class Scheduler(46 - 47) // {True_}
   4[013] - store field, pop 0
   6[017] - load local 3
-  7[088] - return S1 2
+  7[090] - return S1 2
 
 DeviceTask.run tests/type_propagation/richards-test.toit
  - argument 0: {DeviceTask}
@@ -631,7 +631,7 @@ DeviceTask.run tests/type_propagation/richards-test.toit
   6[081] - branch if true T17
   9[009] - load field local 3 // [{DeviceTask}] -> {Null_|Scheduler}
  11[053] - invoke static Scheduler.suspend-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {*}
- 14[088] - return S1 2
+ 14[090] - return S1 2
  17[009] - load field local 19 // [{DeviceTask}] -> {Null_|Packet}
  19[018] - load local 4
  20[022] - load null
@@ -639,14 +639,14 @@ DeviceTask.run tests/type_propagation/richards-test.toit
  23[009] - load field local 4 // [{DeviceTask}] -> {Null_|Scheduler}
  25[015] - load local 1
  26[053] - invoke static Scheduler.queue tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {Null_|Packet}] -> {*}
- 29[088] - return S2 2
+ 29[090] - return S2 2
  32[080] - branch T47
  35[017] - load local 3
  36[017] - load local 3
  37[013] - store field, pop 1
  39[009] - load field local 3 // [{DeviceTask}] -> {Null_|Scheduler}
  41[053] - invoke static Scheduler.hold-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {Null_|Packet|TaskControlBlock}
- 44[088] - return S1 2
+ 44[090] - return S1 2
 
 WorkerTask tests/type_propagation/richards-test.toit
  - argument 0: {WorkerTask}
@@ -666,7 +666,7 @@ WorkerTask tests/type_propagation/richards-test.toit
  14[048] - as class LargeInteger_(22 - 24) // {True_}
  16[013] - store field, pop 2
  18[019] - load local 5
- 19[088] - return S1 4
+ 19[090] - return S1 4
 
 WorkerTask.run tests/type_propagation/richards-test.toit
  - argument 0: {WorkerTask}
@@ -675,7 +675,7 @@ WorkerTask.run tests/type_propagation/richards-test.toit
   1[081] - branch if true T12
   4[009] - load field local 3 // [{WorkerTask}] -> {Null_|Scheduler}
   6[053] - invoke static Scheduler.suspend-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {*}
-  9[088] - return S1 2
+  9[090] - return S1 2
  12[017] - load local 3
  13[026] - load smi 2
  15[009] - load field local 21 // [{WorkerTask}] -> {Null_|SmallInteger_}
@@ -723,11 +723,11 @@ WorkerTask.run tests/type_propagation/richards-test.toit
  84[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
  85[004] - store local, pop S2
  87[041] - pop 1
- 88[083] - branch back T44
+ 88[084] - branch back T44
  93[010] - pop, load field local 3 // [{WorkerTask}] -> {Null_|Scheduler}
  95[017] - load local 3
  96[053] - invoke static Scheduler.queue tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {Packet}] -> {*}
- 99[088] - return S1 2
+ 99[090] - return S1 2
 
 HandlerTask tests/type_propagation/richards-test.toit
  - argument 0: {HandlerTask}
@@ -737,7 +737,7 @@ HandlerTask tests/type_propagation/richards-test.toit
   2[048] - as class Scheduler(46 - 47) // {True_}
   4[013] - store field, pop 0
   6[017] - load local 3
-  7[088] - return S1 2
+  7[090] - return S1 2
 
 HandlerTask.run tests/type_propagation/richards-test.toit
  - argument 0: {HandlerTask}
@@ -789,7 +789,7 @@ HandlerTask.run tests/type_propagation/richards-test.toit
  87[010] - pop, load field local 5 // [{HandlerTask}] -> {Null_|Scheduler}
  89[015] - load local 1
  90[053] - invoke static Scheduler.queue tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {Null_|Packet}] -> {*}
- 93[088] - return S3 2
+ 93[090] - return S3 2
  96[080] - branch T118
  99[009] - load field local 20 // [{HandlerTask}] -> {Null_|Packet}
 101[019] - load local 5
@@ -799,11 +799,11 @@ HandlerTask.run tests/type_propagation/richards-test.toit
 109[009] - load field local 5 // [{HandlerTask}] -> {Null_|Scheduler}
 111[015] - load local 1
 112[053] - invoke static Scheduler.queue tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {Null_|Packet}] -> {*}
-115[088] - return S3 2
+115[090] - return S3 2
 118[041] - pop 1
 119[009] - load field local 3 // [{HandlerTask}] -> {Null_|Scheduler}
 121[053] - invoke static Scheduler.suspend-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {*}
-124[088] - return S1 2
+124[090] - return S1 2
 
 Packet tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -831,12 +831,12 @@ Packet tests/type_propagation/richards-test.toit
  26[053] - invoke static List <sdk>/core/collections.toit // [{SmallInteger_}, {Null_}] -> {List_}
  29[013] - store field, pop 4
  31[019] - load local 5
- 32[088] - return S1 4
+ 32[090] - return S1 4
 
 Packet.link tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 2 // [{Packet}] -> {Null_|Packet}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.link= tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -846,12 +846,12 @@ Packet.link= tests/type_propagation/richards-test.toit
   3[002] - pop, load local S3
   5[017] - load local 3
   6[011] - store field 0
-  8[088] - return S1 2
+  8[090] - return S1 2
 
 Packet.id tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 18 // [{Packet}] -> {Null_|LargeInteger_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.id= tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -860,17 +860,17 @@ Packet.id= tests/type_propagation/richards-test.toit
   2[017] - load local 3
   3[017] - load local 3
   4[011] - store field 1
-  6[088] - return S1 2
+  6[090] - return S1 2
 
 Packet.kind tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 34 // [{Packet}] -> {Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.a1 tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 50 // [{Packet}] -> {*}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.a1= tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -878,12 +878,12 @@ Packet.a1= tests/type_propagation/richards-test.toit
   0[017] - load local 3
   1[017] - load local 3
   2[011] - store field 3
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 Packet.a2 tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 66 // [{Packet}] -> {Null_|List_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.add-to tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -895,7 +895,7 @@ Packet.add-to tests/type_propagation/richards-test.toit
   6[016] - load local 2
   7[081] - branch if true T14
  10[017] - load local 3
- 11[088] - return S1 2
+ 11[090] - return S1 2
  14[016] - load local 2
  15[014] - load local 0
  16[060] - invoke virtual get link // [{Null_|Packet}] -> {Null_|Packet}
@@ -906,9 +906,9 @@ Packet.add-to tests/type_propagation/richards-test.toit
  27[014] - load local 0
  28[004] - store local, pop S2
  30[041] - pop 1
- 31[083] - branch back T15
+ 31[084] - branch back T15
  36[014] - load local 0
  37[019] - load local 5
  38[061] - invoke virtual set link // [{Null_|Packet}, {Packet}] -> {Packet}
  41[002] - pop, load local S3
- 43[088] - return S2 2
+ 43[090] - return S2 2
diff --git a/tests/type_propagation/gold/richards-test.gold-O2 b/tests/type_propagation/gold/richards-test.gold-O2
index 2ca33c386..cfcafaaf9 100644
--- a/tests/type_propagation/gold/richards-test.gold-O2
+++ b/tests/type_propagation/gold/richards-test.gold-O2
@@ -1,6 +1,6 @@
 main tests/type_propagation/richards-test.toit
   0[053] - invoke static run-richards tests/type_propagation/richards-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 run-richards tests/type_propagation/richards-test.toit
   0[042] - allocate instance Scheduler
@@ -96,7 +96,7 @@ run-richards tests/type_propagation/richards-test.toit
 171[029] - load method [block] in run-richards tests/type_propagation/richards-test.toit
 176[038] - load block 0
 178[053] - invoke static assert_ <sdk>/core/assert_.toit // [[block]] -> {Null_}
-181[089] - return null S4 0
+181[091] - return null S4 0
 
 [block] in run-richards tests/type_propagation/richards-test.toit
  - argument 0: [block]
@@ -105,7 +105,7 @@ run-richards tests/type_propagation/richards-test.toit
   3[007] - load field 0 // [{Scheduler}] -> {Null_|LargeInteger_|SmallInteger_}
   5[027] - load smi 23246
   8[062] - invoke eq // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  9[088] - return S1 1
+  9[090] - return S1 1
 
 [block] in run-richards tests/type_propagation/richards-test.toit
  - argument 0: [block]
@@ -114,7 +114,7 @@ run-richards tests/type_propagation/richards-test.toit
   3[007] - load field 1 // [{Scheduler}] -> {Null_|LargeInteger_|SmallInteger_}
   5[027] - load smi 9297
   8[062] - invoke eq // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
-  9[088] - return S1 1
+  9[090] - return S1 1
 
 Scheduler tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -130,7 +130,7 @@ Scheduler tests/type_propagation/richards-test.toit
  12[053] - invoke static List <sdk>/core/collections.toit // [{SmallInteger_}, {Null_}] -> {List_}
  15[013] - store field, pop 2
  17[016] - load local 2
- 18[088] - return S1 1
+ 18[090] - return S1 1
 
 Scheduler.add-idle-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -148,7 +148,7 @@ Scheduler.add-idle-task tests/type_propagation/richards-test.toit
  13[000] - load local S9
  15[053] - invoke static IdleTask tests/type_propagation/richards-test.toit // [{IdleTask}, {Scheduler}, {SmallInteger_}, {SmallInteger_}] -> {IdleTask}
  18[053] - invoke static Scheduler.add-running-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Null_}, {IdleTask}] -> {Null_}
- 21[089] - return null S1 5
+ 21[091] - return null S1 5
 
 Scheduler.add-worker-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -165,7 +165,7 @@ Scheduler.add-worker-task tests/type_propagation/richards-test.toit
  10[023] - load smi 0
  11[053] - invoke static WorkerTask tests/type_propagation/richards-test.toit // [{WorkerTask}, {Scheduler}, {SmallInteger_}, {SmallInteger_}] -> {WorkerTask}
  14[053] - invoke static Scheduler.add-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Packet}, {WorkerTask}] -> {Null_}
- 17[089] - return null S1 4
+ 17[091] - return null S1 4
 
 Scheduler.add-handler-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -180,7 +180,7 @@ Scheduler.add-handler-task tests/type_propagation/richards-test.toit
   6[000] - load local S10
   8[053] - invoke static HandlerTask tests/type_propagation/richards-test.toit // [{HandlerTask}, {Scheduler}] -> {HandlerTask}
  11[053] - invoke static Scheduler.add-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Packet}, {HandlerTask}] -> {Null_}
- 14[089] - return null S1 4
+ 14[091] - return null S1 4
 
 Scheduler.add-device-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -195,7 +195,7 @@ Scheduler.add-device-task tests/type_propagation/richards-test.toit
   6[000] - load local S10
   8[053] - invoke static DeviceTask tests/type_propagation/richards-test.toit // [{DeviceTask}, {Scheduler}] -> {DeviceTask}
  11[053] - invoke static Scheduler.add-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Null_}, {DeviceTask}] -> {Null_}
- 14[089] - return null S1 4
+ 14[091] - return null S1 4
 
 Scheduler.add-running-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -211,7 +211,7 @@ Scheduler.add-running-task tests/type_propagation/richards-test.toit
  10[053] - invoke static Scheduler.add-task tests/type_propagation/richards-test.toit // [{Scheduler}, {SmallInteger_}, {SmallInteger_}, {Null_}, {IdleTask}] -> {Null_}
  13[010] - pop, load field local 70 // [{Scheduler}] -> {*}
  15[058] - invoke virtual set-running // [{*}] -> {Null_}
- 19[089] - return null S1 5
+ 19[091] - return null S1 5
 
 Scheduler.add-task tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -235,7 +235,7 @@ Scheduler.add-task tests/type_propagation/richards-test.toit
  27[000] - load local S6
  29[009] - load field local 72 // [{Scheduler}] -> {*}
  31[079] - invoke at_put // [{Null_|List_}, {SmallInteger_}, {*}] -> {*}
- 32[089] - return null S1 5
+ 32[091] - return null S1 5
 
 Scheduler.schedule tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -260,8 +260,8 @@ Scheduler.schedule tests/type_propagation/richards-test.toit
  39[009] - load field local 67 // [{Scheduler}] -> {*}
  41[058] - invoke virtual run // [{*}] -> {*}
  45[013] - store field, pop 4
- 47[083] - branch back T5
- 52[089] - return null S0 1
+ 47[084] - branch back T5
+ 52[091] - return null S0 1
 
 Scheduler.hold-current tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -275,14 +275,14 @@ Scheduler.hold-current tests/type_propagation/richards-test.toit
  10[058] - invoke virtual mark-as-held // [{*}] -> {Null_}
  14[010] - pop, load field local 66 // [{Scheduler}] -> {*}
  16[060] - invoke virtual get link // [{*}] -> {Null_|Packet|TaskControlBlock}
- 19[088] - return S1 1
+ 19[090] - return S1 1
 
 Scheduler.suspend-current tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
   0[009] - load field local 66 // [{Scheduler}] -> {*}
   2[058] - invoke virtual mark-as-suspended // [{*}] -> {Null_}
   6[010] - pop, load field local 66 // [{Scheduler}] -> {*}
-  8[088] - return S1 1
+  8[090] - return S1 1
 
 Scheduler.release tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -293,7 +293,7 @@ Scheduler.release tests/type_propagation/richards-test.toit
   4[014] - load local 0
   5[081] - branch if true T12
   8[014] - load local 0
-  9[088] - return S2 2
+  9[090] - return S2 2
  12[014] - load local 0
  13[058] - invoke virtual mark-as-not-held // [{*}] -> {Null_}
  17[002] - pop, load local S0
@@ -303,10 +303,10 @@ Scheduler.release tests/type_propagation/richards-test.toit
  27[064] - invoke gt // [{Null_|SmallInteger_}, {Null_|SmallInteger_}] -> {True_|False_}
  28[082] - branch if false T38
  31[014] - load local 0
- 32[088] - return S2 2
+ 32[090] - return S2 2
  35[080] - branch T43
  38[009] - load field local 68 // [{Scheduler}] -> {*}
- 40[088] - return S2 2
+ 40[090] - return S2 2
 
 Scheduler.queue tests/type_propagation/richards-test.toit
  - argument 0: {Scheduler}
@@ -318,7 +318,7 @@ Scheduler.queue tests/type_propagation/richards-test.toit
   7[014] - load local 0
   8[081] - branch if true T15
  11[014] - load local 0
- 12[088] - return S2 2
+ 12[090] - return S2 2
  15[009] - load field local 4 // [{Scheduler}] -> {Null_|LargeInteger_|SmallInteger_}
  17[019] - load local 5
  18[015] - load local 1
@@ -336,27 +336,27 @@ Scheduler.queue tests/type_propagation/richards-test.toit
  36[009] - load field local 69 // [{Scheduler}] -> {*}
  38[019] - load local 5
  39[058] - invoke virtual check-priority-add // [{*}, {*}, {Packet}] -> {*}
- 43[088] - return S2 2
+ 43[090] - return S2 2
 
 STATE-NOT-HELD tests/type_propagation/richards-test.toit
   0[026] - load smi 4
   2[058] - invoke virtual ~ // [{SmallInteger_}] -> {SmallInteger_}
-  6[088] - return S1 0
+  6[090] - return S1 0
 
 TaskControlBlock.link tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
   0[009] - load field local 2 // [{TaskControlBlock}] -> {Null_|TaskControlBlock}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 TaskControlBlock.id tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
   0[009] - load field local 18 // [{TaskControlBlock}] -> {Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 TaskControlBlock.priority tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
   0[009] - load field local 34 // [{TaskControlBlock}] -> {Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 TaskControlBlock tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -392,14 +392,14 @@ TaskControlBlock tests/type_propagation/richards-test.toit
  44[026] - load smi 3
  46[013] - store field, pop 5
  48[000] - load local S7
- 50[088] - return S1 6
+ 50[090] - return S1 6
 
 TaskControlBlock.set-running tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
   0[016] - load local 2
   1[023] - load smi 0
   2[013] - store field, pop 5
-  4[089] - return null S0 1
+  4[091] - return null S0 1
 
 TaskControlBlock.mark-as-not-held tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -408,7 +408,7 @@ TaskControlBlock.mark-as-not-held tests/type_propagation/richards-test.toit
   3[032] - load global var lazy G0 // {SmallInteger_}
   5[069] - invoke bit and // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   6[013] - store field, pop 5
-  8[089] - return null S0 1
+  8[091] - return null S0 1
 
 TaskControlBlock.mark-as-held tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -417,7 +417,7 @@ TaskControlBlock.mark-as-held tests/type_propagation/richards-test.toit
   3[026] - load smi 4
   5[067] - invoke bit or // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   6[013] - store field, pop 5
-  8[089] - return null S0 1
+  8[091] - return null S0 1
 
 TaskControlBlock.is-held-or-suspended tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -435,7 +435,7 @@ TaskControlBlock.is-held-or-suspended tests/type_propagation/richards-test.toit
  21[010] - pop, load field local 82 // [{TaskControlBlock}] -> {Null_|LargeInteger_|SmallInteger_}
  23[026] - load smi 2
  25[062] - invoke eq // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
- 26[088] - return S1 1
+ 26[090] - return S1 1
 
 TaskControlBlock.mark-as-suspended tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -444,7 +444,7 @@ TaskControlBlock.mark-as-suspended tests/type_propagation/richards-test.toit
   3[026] - load smi 2
   5[067] - invoke bit or // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   6[013] - store field, pop 5
-  8[089] - return null S0 1
+  8[091] - return null S0 1
 
 TaskControlBlock.mark-as-runnable tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -453,7 +453,7 @@ TaskControlBlock.mark-as-runnable tests/type_propagation/richards-test.toit
   3[025] - load smi 1
   4[067] - invoke bit or // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
   5[013] - store field, pop 5
-  7[089] - return null S0 1
+  7[091] - return null S0 1
 
 TaskControlBlock.run tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -478,7 +478,7 @@ TaskControlBlock.run tests/type_propagation/richards-test.toit
  31[009] - load field local 67 // [{TaskControlBlock}] -> {Null_|HandlerTask|WorkerTask|DeviceTask|IdleTask}
  33[015] - load local 1
  34[058] - invoke virtual run // [{Null_|HandlerTask|WorkerTask|DeviceTask|IdleTask}, {Null_|Packet}] -> {*}
- 38[088] - return S2 1
+ 38[090] - return S2 1
 
 TaskControlBlock.check-priority-add tests/type_propagation/richards-test.toit
  - argument 0: {TaskControlBlock}
@@ -497,7 +497,7 @@ TaskControlBlock.check-priority-add tests/type_propagation/richards-test.toit
  19[064] - invoke gt // [{Null_|SmallInteger_}, {Null_|SmallInteger_}] -> {True_|False_}
  20[082] - branch if false T27
  23[018] - load local 4
- 24[088] - return S1 3
+ 24[090] - return S1 3
  27[080] - branch T40
  30[018] - load local 4
  31[017] - load local 3
@@ -505,7 +505,7 @@ TaskControlBlock.check-priority-add tests/type_propagation/richards-test.toit
  34[058] - invoke virtual add-to // [{Packet}, {Null_|Packet}] -> {Packet}
  38[013] - store field, pop 3
  40[017] - load local 3
- 41[088] - return S1 3
+ 41[090] - return S1 3
 
 IdleTask tests/type_propagation/richards-test.toit
  - argument 0: {IdleTask}
@@ -522,7 +522,7 @@ IdleTask tests/type_propagation/richards-test.toit
   9[017] - load local 3
  10[013] - store field, pop 2
  12[019] - load local 5
- 13[088] - return S1 4
+ 13[090] - return S1 4
 
 IdleTask.run tests/type_propagation/richards-test.toit
  - argument 0: {IdleTask}
@@ -539,7 +539,7 @@ IdleTask.run tests/type_propagation/richards-test.toit
  12[082] - branch if false T23
  15[009] - load field local 3 // [{IdleTask}] -> {Null_|Scheduler}
  17[053] - invoke static Scheduler.hold-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {Null_|Packet|TaskControlBlock}
- 20[088] - return S1 2
+ 20[090] - return S1 2
  23[009] - load field local 19 // [{IdleTask}] -> {Null_|LargeInteger_|SmallInteger_}
  25[025] - load smi 1
  26[069] - invoke bit and // [{Null_|LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
@@ -554,7 +554,7 @@ IdleTask.run tests/type_propagation/richards-test.toit
  39[009] - load field local 3 // [{IdleTask}] -> {Null_|Scheduler}
  41[026] - load smi 4
  43[053] - invoke static Scheduler.release tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {SmallInteger_}] -> {*}
- 46[088] - return S1 2
+ 46[090] - return S1 2
  49[080] - branch T73
  52[017] - load local 3
  53[009] - load field local 20 // [{IdleTask}] -> {Null_|LargeInteger_|SmallInteger_}
@@ -566,7 +566,7 @@ IdleTask.run tests/type_propagation/richards-test.toit
  63[009] - load field local 3 // [{IdleTask}] -> {Null_|Scheduler}
  65[026] - load smi 5
  67[053] - invoke static Scheduler.release tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {SmallInteger_}] -> {*}
- 70[088] - return S1 2
+ 70[090] - return S1 2
 
 DeviceTask tests/type_propagation/richards-test.toit
  - argument 0: {DeviceTask}
@@ -575,7 +575,7 @@ DeviceTask tests/type_propagation/richards-test.toit
   1[017] - load local 3
   2[013] - store field, pop 0
   4[017] - load local 3
-  5[088] - return S1 2
+  5[090] - return S1 2
 
 DeviceTask.run tests/type_propagation/richards-test.toit
  - argument 0: {DeviceTask}
@@ -586,7 +586,7 @@ DeviceTask.run tests/type_propagation/richards-test.toit
   6[081] - branch if true T17
   9[009] - load field local 3 // [{DeviceTask}] -> {Null_|Scheduler}
  11[053] - invoke static Scheduler.suspend-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {*}
- 14[088] - return S1 2
+ 14[090] - return S1 2
  17[009] - load field local 19 // [{DeviceTask}] -> {Null_|Packet}
  19[018] - load local 4
  20[022] - load null
@@ -594,14 +594,14 @@ DeviceTask.run tests/type_propagation/richards-test.toit
  23[009] - load field local 4 // [{DeviceTask}] -> {Null_|Scheduler}
  25[015] - load local 1
  26[053] - invoke static Scheduler.queue tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {Null_|Packet}] -> {*}
- 29[088] - return S2 2
+ 29[090] - return S2 2
  32[080] - branch T47
  35[017] - load local 3
  36[017] - load local 3
  37[013] - store field, pop 1
  39[009] - load field local 3 // [{DeviceTask}] -> {Null_|Scheduler}
  41[053] - invoke static Scheduler.hold-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {Null_|Packet|TaskControlBlock}
- 44[088] - return S1 2
+ 44[090] - return S1 2
 
 WorkerTask tests/type_propagation/richards-test.toit
  - argument 0: {WorkerTask}
@@ -618,7 +618,7 @@ WorkerTask tests/type_propagation/richards-test.toit
   9[017] - load local 3
  10[013] - store field, pop 2
  12[019] - load local 5
- 13[088] - return S1 4
+ 13[090] - return S1 4
 
 WorkerTask.run tests/type_propagation/richards-test.toit
  - argument 0: {WorkerTask}
@@ -627,7 +627,7 @@ WorkerTask.run tests/type_propagation/richards-test.toit
   1[081] - branch if true T12
   4[009] - load field local 3 // [{WorkerTask}] -> {Null_|Scheduler}
   6[053] - invoke static Scheduler.suspend-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {*}
-  9[088] - return S1 2
+  9[090] - return S1 2
  12[017] - load local 3
  13[026] - load smi 2
  15[009] - load field local 21 // [{WorkerTask}] -> {Null_|SmallInteger_}
@@ -672,11 +672,11 @@ WorkerTask.run tests/type_propagation/richards-test.toit
  78[073] - invoke add // [{LargeInteger_|SmallInteger_}, {SmallInteger_}] -> {LargeInteger_|SmallInteger_}
  79[004] - store local, pop S2
  81[041] - pop 1
- 82[083] - branch back T42
+ 82[084] - branch back T42
  87[010] - pop, load field local 3 // [{WorkerTask}] -> {Null_|Scheduler}
  89[017] - load local 3
  90[053] - invoke static Scheduler.queue tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {Packet}] -> {*}
- 93[088] - return S1 2
+ 93[090] - return S1 2
 
 HandlerTask tests/type_propagation/richards-test.toit
  - argument 0: {HandlerTask}
@@ -685,7 +685,7 @@ HandlerTask tests/type_propagation/richards-test.toit
   1[017] - load local 3
   2[013] - store field, pop 0
   4[017] - load local 3
-  5[088] - return S1 2
+  5[090] - return S1 2
 
 HandlerTask.run tests/type_propagation/richards-test.toit
  - argument 0: {HandlerTask}
@@ -737,7 +737,7 @@ HandlerTask.run tests/type_propagation/richards-test.toit
  87[010] - pop, load field local 5 // [{HandlerTask}] -> {Null_|Scheduler}
  89[015] - load local 1
  90[053] - invoke static Scheduler.queue tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {Null_|Packet}] -> {*}
- 93[088] - return S3 2
+ 93[090] - return S3 2
  96[080] - branch T118
  99[009] - load field local 20 // [{HandlerTask}] -> {Null_|Packet}
 101[019] - load local 5
@@ -747,11 +747,11 @@ HandlerTask.run tests/type_propagation/richards-test.toit
 109[009] - load field local 5 // [{HandlerTask}] -> {Null_|Scheduler}
 111[015] - load local 1
 112[053] - invoke static Scheduler.queue tests/type_propagation/richards-test.toit // [{Null_|Scheduler}, {Null_|Packet}] -> {*}
-115[088] - return S3 2
+115[090] - return S3 2
 118[041] - pop 1
 119[009] - load field local 3 // [{HandlerTask}] -> {Null_|Scheduler}
 121[053] - invoke static Scheduler.suspend-current tests/type_propagation/richards-test.toit // [{Null_|Scheduler}] -> {*}
-124[088] - return S1 2
+124[090] - return S1 2
 
 Packet tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -776,12 +776,12 @@ Packet tests/type_propagation/richards-test.toit
  20[053] - invoke static List <sdk>/core/collections.toit // [{SmallInteger_}, {Null_}] -> {List_}
  23[013] - store field, pop 4
  25[019] - load local 5
- 26[088] - return S1 4
+ 26[090] - return S1 4
 
 Packet.link tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 2 // [{Packet}] -> {Null_|Packet}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.link= tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -789,12 +789,12 @@ Packet.link= tests/type_propagation/richards-test.toit
   0[017] - load local 3
   1[017] - load local 3
   2[011] - store field 0
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 Packet.id tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 18 // [{Packet}] -> {Null_|LargeInteger_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.id= tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -803,17 +803,17 @@ Packet.id= tests/type_propagation/richards-test.toit
   2[017] - load local 3
   3[017] - load local 3
   4[011] - store field 1
-  6[088] - return S1 2
+  6[090] - return S1 2
 
 Packet.kind tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 34 // [{Packet}] -> {Null_|SmallInteger_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.a1 tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 50 // [{Packet}] -> {*}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.a1= tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -821,12 +821,12 @@ Packet.a1= tests/type_propagation/richards-test.toit
   0[017] - load local 3
   1[017] - load local 3
   2[011] - store field 3
-  4[088] - return S1 2
+  4[090] - return S1 2
 
 Packet.a2 tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
   0[009] - load field local 66 // [{Packet}] -> {Null_|List_}
-  2[088] - return S1 1
+  2[090] - return S1 1
 
 Packet.add-to tests/type_propagation/richards-test.toit
  - argument 0: {Packet}
@@ -837,7 +837,7 @@ Packet.add-to tests/type_propagation/richards-test.toit
   4[016] - load local 2
   5[081] - branch if true T12
   8[017] - load local 3
-  9[088] - return S1 2
+  9[090] - return S1 2
  12[016] - load local 2
  13[014] - load local 0
  14[060] - invoke virtual get link // [{Null_|Packet}] -> {Null_|Packet}
@@ -848,9 +848,9 @@ Packet.add-to tests/type_propagation/richards-test.toit
  25[014] - load local 0
  26[004] - store local, pop S2
  28[041] - pop 1
- 29[083] - branch back T13
+ 29[084] - branch back T13
  34[014] - load local 0
  35[019] - load local 5
  36[061] - invoke virtual set link // [{Null_|Packet}, {Packet}] -> {Packet}
  39[002] - pop, load local S3
- 41[088] - return S2 2
+ 41[090] - return S2 2
diff --git a/tests/type_propagation/gold/spawn-test.gold b/tests/type_propagation/gold/spawn-test.gold
index a961239b3..6e68971cd 100644
--- a/tests/type_propagation/gold/spawn-test.gold
+++ b/tests/type_propagation/gold/spawn-test.gold
@@ -12,14 +12,14 @@ main tests/type_propagation/spawn-test.toit
  21[041] - pop 1
  22[020] - load literal hest
  24[053] - invoke static id tests/type_propagation/spawn-test.toit // [{String_}] -> {String_}
- 27[089] - return null S1 0
+ 27[091] - return null S1 0
 
 [lambda] in main tests/type_propagation/spawn-test.toit
   0[026] - load smi 7
   2[053] - invoke static id tests/type_propagation/spawn-test.toit // [{SmallInteger_}] -> {SmallInteger_}
-  5[088] - return S1 0
+  5[090] - return S1 0
 
 id tests/type_propagation/spawn-test.toit
  - argument 0: {String_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/spawn-test.gold-O2 b/tests/type_propagation/gold/spawn-test.gold-O2
index a961239b3..6e68971cd 100644
--- a/tests/type_propagation/gold/spawn-test.gold-O2
+++ b/tests/type_propagation/gold/spawn-test.gold-O2
@@ -12,14 +12,14 @@ main tests/type_propagation/spawn-test.toit
  21[041] - pop 1
  22[020] - load literal hest
  24[053] - invoke static id tests/type_propagation/spawn-test.toit // [{String_}] -> {String_}
- 27[089] - return null S1 0
+ 27[091] - return null S1 0
 
 [lambda] in main tests/type_propagation/spawn-test.toit
   0[026] - load smi 7
   2[053] - invoke static id tests/type_propagation/spawn-test.toit // [{SmallInteger_}] -> {SmallInteger_}
-  5[088] - return S1 0
+  5[090] - return S1 0
 
 id tests/type_propagation/spawn-test.toit
  - argument 0: {String_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/time-test.gold b/tests/type_propagation/gold/time-test.gold
index 5a22be2af..453493ecd 100644
--- a/tests/type_propagation/gold/time-test.gold
+++ b/tests/type_propagation/gold/time-test.gold
@@ -18,5 +18,5 @@ main tests/type_propagation/time-test.toit
  28[027] - load smi 1000
  31[053] - invoke static sleep <sdk>/core/timer.toit // [{SmallInteger_}] -> {Null_}
  34[041] - pop 1
- 35[083] - branch back T1
- 40[089] - return null S1 0
+ 35[084] - branch back T1
+ 40[091] - return null S1 0
diff --git a/tests/type_propagation/gold/time-test.gold-O2 b/tests/type_propagation/gold/time-test.gold-O2
index ef5d7fe7e..004748420 100644
--- a/tests/type_propagation/gold/time-test.gold-O2
+++ b/tests/type_propagation/gold/time-test.gold-O2
@@ -16,5 +16,5 @@ main tests/type_propagation/time-test.toit
  24[027] - load smi 1000
  27[053] - invoke static sleep <sdk>/core/timer.toit // [{SmallInteger_}] -> {Null_}
  30[041] - pop 1
- 31[083] - branch back T1
- 36[089] - return null S1 0
+ 31[084] - branch back T1
+ 36[091] - return null S1 0
diff --git a/tests/type_propagation/gold/try-test.gold b/tests/type_propagation/gold/try-test.gold
index 9df4be64f..7bf78e272 100644
--- a/tests/type_propagation/gold/try-test.gold
+++ b/tests/type_propagation/gold/try-test.gold
@@ -1,46 +1,46 @@
 main tests/type_propagation/try-test.toit
   0[053] - invoke static test-nested tests/type_propagation/try-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 test-nested tests/type_propagation/try-test.toit
   0[053] - invoke static nested tests/type_propagation/try-test.toit // {Null_|SmallInteger_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 nested tests/type_propagation/try-test.toit
   0[022] - load null
   1[029] - load method [block] in nested tests/type_propagation/try-test.toit
-  6[094] - link try 0
+  6[096] - link try 0
   8[038] - load block 4
  10[055] - invoke block S1 // [[block]] -> {Null_}
  12[041] - pop 1
- 13[095] - unlink try 0
+ 13[097] - unlink try 0
  15[018] - load local 4
- 16[088] - return S6 0
- 19[096] - unwind
+ 16[090] - return S6 0
+ 19[098] - unwind
  20[041] - pop 1
 
 [block] in nested tests/type_propagation/try-test.toit
  - argument 0: [block]
   0[022] - load null
   1[029] - load method [block] in [block] in nested tests/type_propagation/try-test.toit
-  6[094] - link try 0
+  6[096] - link try 0
   8[038] - load block 4
  10[055] - invoke block S1 // [[block]] -> {SmallInteger_}
  12[041] - pop 1
- 13[095] - unlink try 0
+ 13[097] - unlink try 0
  15[000] - load local S7
  17[019] - load local 5
  18[006] - store outer S1
  20[041] - pop 1
- 21[096] - unwind
+ 21[098] - unwind
  22[041] - pop 1
  23[022] - load null
  24[004] - store local, pop S1
- 26[088] - return S1 1
+ 26[090] - return S1 1
 
 [block] in [block] in nested tests/type_propagation/try-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[026] - load smi 42
   3[006] - store outer S1
-  5[088] - return S1 1
+  5[090] - return S1 1
diff --git a/tests/type_propagation/gold/try-test.gold-O2 b/tests/type_propagation/gold/try-test.gold-O2
index 9df4be64f..7bf78e272 100644
--- a/tests/type_propagation/gold/try-test.gold-O2
+++ b/tests/type_propagation/gold/try-test.gold-O2
@@ -1,46 +1,46 @@
 main tests/type_propagation/try-test.toit
   0[053] - invoke static test-nested tests/type_propagation/try-test.toit // {Null_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 test-nested tests/type_propagation/try-test.toit
   0[053] - invoke static nested tests/type_propagation/try-test.toit // {Null_|SmallInteger_}
-  3[089] - return null S1 0
+  3[091] - return null S1 0
 
 nested tests/type_propagation/try-test.toit
   0[022] - load null
   1[029] - load method [block] in nested tests/type_propagation/try-test.toit
-  6[094] - link try 0
+  6[096] - link try 0
   8[038] - load block 4
  10[055] - invoke block S1 // [[block]] -> {Null_}
  12[041] - pop 1
- 13[095] - unlink try 0
+ 13[097] - unlink try 0
  15[018] - load local 4
- 16[088] - return S6 0
- 19[096] - unwind
+ 16[090] - return S6 0
+ 19[098] - unwind
  20[041] - pop 1
 
 [block] in nested tests/type_propagation/try-test.toit
  - argument 0: [block]
   0[022] - load null
   1[029] - load method [block] in [block] in nested tests/type_propagation/try-test.toit
-  6[094] - link try 0
+  6[096] - link try 0
   8[038] - load block 4
  10[055] - invoke block S1 // [[block]] -> {SmallInteger_}
  12[041] - pop 1
- 13[095] - unlink try 0
+ 13[097] - unlink try 0
  15[000] - load local S7
  17[019] - load local 5
  18[006] - store outer S1
  20[041] - pop 1
- 21[096] - unwind
+ 21[098] - unwind
  22[041] - pop 1
  23[022] - load null
  24[004] - store local, pop S1
- 26[088] - return S1 1
+ 26[090] - return S1 1
 
 [block] in [block] in nested tests/type_propagation/try-test.toit
  - argument 0: [block]
   0[016] - load local 2
   1[026] - load smi 42
   3[006] - store outer S1
-  5[088] - return S1 1
+  5[090] - return S1 1
diff --git a/tests/type_propagation/gold/typecheck-test.gold b/tests/type_propagation/gold/typecheck-test.gold
index fcd20aff7..63fc25079 100644
--- a/tests/type_propagation/gold/typecheck-test.gold
+++ b/tests/type_propagation/gold/typecheck-test.gold
@@ -4,7 +4,7 @@ main tests/type_propagation/typecheck-test.toit
   4[053] - invoke static test-any tests/type_propagation/typecheck-test.toit // {Null_}
   7[041] - pop 1
   8[053] - invoke static test-throws tests/type_propagation/typecheck-test.toit // {Null_}
- 11[089] - return null S1 0
+ 11[091] - return null S1 0
 
 test-simple tests/type_propagation/typecheck-test.toit
   0[022] - load null
@@ -22,7 +22,7 @@ test-simple tests/type_propagation/typecheck-test.toit
  26[020] - load literal kurt
  28[053] - invoke static is-int tests/type_propagation/typecheck-test.toit // [{String_}] -> {False_}
  31[053] - invoke static id tests/type_propagation/typecheck-test.toit // [{False_}] -> {False_}
- 34[089] - return null S1 0
+ 34[091] - return null S1 0
 
 test-any tests/type_propagation/typecheck-test.toit
   0[020] - load literal true
@@ -36,7 +36,7 @@ test-any tests/type_propagation/typecheck-test.toit
  17[041] - pop 1
  18[020] - load literal hest
  20[053] - invoke static id tests/type_propagation/typecheck-test.toit // [{String_}] -> {String_}
- 23[089] - return null S1 0
+ 23[091] - return null S1 0
 
 test-throws tests/type_propagation/typecheck-test.toit
   0[029] - load method [block] in test-throws tests/type_propagation/typecheck-test.toit
@@ -50,37 +50,37 @@ test-throws tests/type_propagation/typecheck-test.toit
  21[022] - load null
  22[022] - load null
  23[053] - invoke static catch <sdk>/core/exceptions.toit // [[block], {Null_}, {Null_}] -> {*}
- 26[089] - return null S2 0
+ 26[091] - return null S2 0
 
 [block] in test-throws tests/type_propagation/typecheck-test.toit
  - argument 0: [block]
   0[053] - invoke static foo tests/type_propagation/typecheck-test.toit // {SmallInteger_}
   3[048] - as class StringSlice_(11 - 13) // {False_}
-  5[088] - return S1 1
+  5[090] - return S1 1
 
 [block] in test-throws tests/type_propagation/typecheck-test.toit
  - argument 0: [block]
   0[026] - load smi 7
   2[053] - invoke static bar tests/type_propagation/typecheck-test.toit // [{SmallInteger_}] -> {}
-  5[088] - return S1 1
+  5[090] - return S1 1
 
 foo tests/type_propagation/typecheck-test.toit
   0[026] - load smi 42
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 bar tests/type_propagation/typecheck-test.toit
  - argument 0: {SmallInteger_}
   0[052] - load local, as class, pop 2 - StringSlice_(11 - 13) // {False_}
   2[026] - load smi 99
-  4[088] - return S1 1
+  4[090] - return S1 1
 
 is-int tests/type_propagation/typecheck-test.toit
  - argument 0: {String_|Null_|float|SmallInteger_}
   0[016] - load local 2
   1[044] - is class LargeInteger_(22 - 24) // {True_|False_}
-  3[088] - return S1 1
+  3[090] - return S1 1
 
 id tests/type_propagation/typecheck-test.toit
  - argument 0: {String_|True_|False_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1
diff --git a/tests/type_propagation/gold/typecheck-test.gold-O2 b/tests/type_propagation/gold/typecheck-test.gold-O2
index 794ba0132..77463b02f 100644
--- a/tests/type_propagation/gold/typecheck-test.gold-O2
+++ b/tests/type_propagation/gold/typecheck-test.gold-O2
@@ -4,7 +4,7 @@ main tests/type_propagation/typecheck-test.toit
   4[053] - invoke static test-any tests/type_propagation/typecheck-test.toit // {Null_}
   7[041] - pop 1
   8[053] - invoke static test-throws tests/type_propagation/typecheck-test.toit // {Null_}
- 11[089] - return null S1 0
+ 11[091] - return null S1 0
 
 test-simple tests/type_propagation/typecheck-test.toit
   0[022] - load null
@@ -22,7 +22,7 @@ test-simple tests/type_propagation/typecheck-test.toit
  26[020] - load literal kurt
  28[053] - invoke static is-int tests/type_propagation/typecheck-test.toit // [{String_}] -> {False_}
  31[053] - invoke static id tests/type_propagation/typecheck-test.toit // [{False_}] -> {False_}
- 34[089] - return null S1 0
+ 34[091] - return null S1 0
 
 test-any tests/type_propagation/typecheck-test.toit
   0[020] - load literal true
@@ -36,7 +36,7 @@ test-any tests/type_propagation/typecheck-test.toit
  17[041] - pop 1
  18[020] - load literal hest
  20[053] - invoke static id tests/type_propagation/typecheck-test.toit // [{String_}] -> {String_}
- 23[089] - return null S1 0
+ 23[091] - return null S1 0
 
 test-throws tests/type_propagation/typecheck-test.toit
   0[029] - load method [block] in test-throws tests/type_propagation/typecheck-test.toit
@@ -50,23 +50,23 @@ test-throws tests/type_propagation/typecheck-test.toit
  21[022] - load null
  22[022] - load null
  23[053] - invoke static catch <sdk>/core/exceptions.toit // [[block], {Null_}, {Null_}] -> {*}
- 26[089] - return null S2 0
+ 26[091] - return null S2 0
 
 [block] in test-throws tests/type_propagation/typecheck-test.toit
  - argument 0: [block]
   0[053] - invoke static foo tests/type_propagation/typecheck-test.toit // {SmallInteger_}
   3[048] - as class StringSlice_(8 - 10) // {False_}
-  5[088] - return S1 1
+  5[090] - return S1 1
 
 [block] in test-throws tests/type_propagation/typecheck-test.toit
  - argument 0: [block]
   0[026] - load smi 7
   2[053] - invoke static bar tests/type_propagation/typecheck-test.toit // [{SmallInteger_}] -> {}
-  5[088] - return S1 1
+  5[090] - return S1 1
 
 foo tests/type_propagation/typecheck-test.toit
   0[026] - load smi 42
-  2[088] - return S1 0
+  2[090] - return S1 0
 
 bar tests/type_propagation/typecheck-test.toit
  - argument 0: {SmallInteger_}
@@ -76,9 +76,9 @@ is-int tests/type_propagation/typecheck-test.toit
  - argument 0: {String_|Null_|float|SmallInteger_}
   0[016] - load local 2
   1[044] - is class LargeInteger_(19 - 21) // {True_|False_}
-  3[088] - return S1 1
+  3[090] - return S1 1
 
 id tests/type_propagation/typecheck-test.toit
  - argument 0: {String_|True_|False_|SmallInteger_}
   0[016] - load local 2
-  1[088] - return S1 1
+  1[090] - return S1 1

From f39e30f9b225a84e9b8737d2bca13314d887f773 Mon Sep 17 00:00:00 2001
From: Erik Corry <erik@toit.io>
Date: Fri, 1 Dec 2023 11:17:53 +0100
Subject: [PATCH 3/4] Feedback. Fix deMorgan bug. Add test.

---
 src/compiler/propagation/type_propagator.cc   | 11 +++++--
 src/compiler/propagation/type_set.cc          |  2 +-
 tests/type_propagation/default-test.toit      | 13 ++++++++
 tests/type_propagation/gold/default-test.gold | 33 +++++++++++++++++++
 .../type_propagation/gold/deltablue-test.gold |  6 ++--
 .../gold/deltablue-test.gold-O2               | 15 ++++-----
 .../type_propagation/gold/richards-test.gold  |  4 +--
 .../gold/richards-test.gold-O2                |  4 +--
 8 files changed, 70 insertions(+), 18 deletions(-)
 create mode 100644 tests/type_propagation/default-test.toit
 create mode 100644 tests/type_propagation/gold/default-test.gold

diff --git a/src/compiler/propagation/type_propagator.cc b/src/compiler/propagation/type_propagator.cc
index ce393b79c..5b57114e2 100644
--- a/src/compiler/propagation/type_propagator.cc
+++ b/src/compiler/propagation/type_propagator.cc
@@ -1174,10 +1174,17 @@ static TypeScope* process(TypeScope* scope, uint8* bcp, std::vector<Worklist*>&
   OPCODE_END();
 
   OPCODE_BEGIN(BRANCH_IF_NOT_NULL);
+    TypeSet top = stack->local(0);
+    bool can_be_null = top.contains_null(program);
     stack->pop();
     uint8* target = bcp + Utils::read_unaligned_uint16(bcp + 1);
-    scope = worklists.back()->add(target, scope, true);
-    stack = scope->top();
+    if (!can_be_null) {
+      // Unconditionally continue at the branch target.
+      return worklists.back()->add(target, scope, false);
+    } else if (top.size(propagator->words_per_type()) > 1) {
+      scope = worklists.back()->add(target, scope, true);
+      stack = scope->top();
+    }
   OPCODE_END();
 
   OPCODE_BEGIN(BRANCH_BACK);
diff --git a/src/compiler/propagation/type_set.cc b/src/compiler/propagation/type_set.cc
index 6ac098401..3009a6362 100644
--- a/src/compiler/propagation/type_set.cc
+++ b/src/compiler/propagation/type_set.cc
@@ -97,7 +97,7 @@ bool TypeSet::can_be_truthy(Program* program) const {
   Iterator it(*this, TypeSet::words_per_type(program));
   while (it.has_next()) {
     unsigned id = it.next();
-    if (id != null_id || id != false_id) return true;
+    if (id != null_id && id != false_id) return true;
   }
   return false;
 }
diff --git a/tests/type_propagation/default-test.toit b/tests/type_propagation/default-test.toit
new file mode 100644
index 000000000..930e43d10
--- /dev/null
+++ b/tests/type_propagation/default-test.toit
@@ -0,0 +1,13 @@
+main:
+  foo false
+  foo2 false
+
+bar: return true
+
+foo x=bar:
+  if x:
+    print x
+
+foo2 x=true:
+  if x:
+    print x
diff --git a/tests/type_propagation/gold/default-test.gold b/tests/type_propagation/gold/default-test.gold
new file mode 100644
index 000000000..420342166
--- /dev/null
+++ b/tests/type_propagation/gold/default-test.gold
@@ -0,0 +1,33 @@
+main tests/type_propagation/default-test.toit
+  0[020] - load literal false
+  2[053] - invoke static foo tests/type_propagation/default-test.toit // [{False_}] -> {Null_}
+  5[041] - pop 1
+  6[020] - load literal false
+  8[053] - invoke static foo2 tests/type_propagation/default-test.toit // [{False_}] -> {Null_}
+ 11[091] - return null S1 0
+
+foo tests/type_propagation/default-test.toit
+ - argument 0: {False_}
+  0[016] - load local 2
+  1[083] - branch if not null T9
+  4[053] - invoke static bar tests/type_propagation/default-test.toit
+  7[004] - store local, pop S3
+  9[016] - load local 2
+ 10[082] - branch if false T18
+ 13[016] - load local 2
+ 14[053] - invoke static print <sdk>/core/print.toit
+ 17[041] - pop 1
+ 18[091] - return null S0 1
+
+foo2 tests/type_propagation/default-test.toit
+ - argument 0: {False_}
+  0[016] - load local 2
+  1[083] - branch if not null T8
+  4[020] - load literal true
+  6[004] - store local, pop S3
+  8[016] - load local 2
+  9[082] - branch if false T17
+ 12[016] - load local 2
+ 13[053] - invoke static print <sdk>/core/print.toit
+ 16[041] - pop 1
+ 17[091] - return null S0 1
diff --git a/tests/type_propagation/gold/deltablue-test.gold b/tests/type_propagation/gold/deltablue-test.gold
index d95763af5..fe6971f2b 100644
--- a/tests/type_propagation/gold/deltablue-test.gold
+++ b/tests/type_propagation/gold/deltablue-test.gold
@@ -772,10 +772,10 @@ ScaleConstraint.recalculate tests/type_propagation/deltablue-test.toit
 EqualityConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
  - argument 1: {Strength}
- - argument 2: {Null_|Variable}
+ - argument 2: {Variable}
  - argument 3: {Variable}
   0[052] - load local, as class, pop 4 - Strength(47 - 48) // {True_}
-  2[052] - load local, as class, pop 3 - Variable(42 - 43) // {True_|False_}
+  2[052] - load local, as class, pop 3 - Variable(42 - 43) // {True_}
   4[052] - load local, as class, pop 2 - Variable(42 - 43) // {True_}
   6[019] - load local 5
   7[019] - load local 5
@@ -1282,7 +1282,7 @@ chain-test tests/type_propagation/deltablue-test.toit
  43[032] - load global var lazy G0 // {Strength}
  45[000] - load local S6
  47[017] - load local 3
- 48[053] - invoke static EqualityConstraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}, {Strength}, {Null_|Variable}, {Variable}] -> {EqualityConstraint}
+ 48[053] - invoke static EqualityConstraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}, {Strength}, {Variable}, {Variable}] -> {EqualityConstraint}
  51[041] - pop 1
  52[015] - load local 1
  53[023] - load smi 0
diff --git a/tests/type_propagation/gold/deltablue-test.gold-O2 b/tests/type_propagation/gold/deltablue-test.gold-O2
index 605842925..91cfa5dbd 100644
--- a/tests/type_propagation/gold/deltablue-test.gold-O2
+++ b/tests/type_propagation/gold/deltablue-test.gold-O2
@@ -719,16 +719,15 @@ ScaleConstraint.recalculate tests/type_propagation/deltablue-test.toit
 EqualityConstraint tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
  - argument 1: {Strength}
- - argument 2: {Null_|Variable}
+ - argument 2: {Variable}
  - argument 3: {Variable}
-  0[052] - load local, as class, pop 3 - Variable(37 - 38) // {True_|False_}
+  0[019] - load local 5
+  1[019] - load local 5
   2[019] - load local 5
   3[019] - load local 5
-  4[019] - load local 5
-  5[019] - load local 5
-  6[053] - invoke static BinaryConstraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}, {Strength}, {Variable}, {Variable}] -> {EqualityConstraint}
-  9[002] - pop, load local S5
- 11[090] - return S1 4
+  4[053] - invoke static BinaryConstraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}, {Strength}, {Variable}, {Variable}] -> {EqualityConstraint}
+  7[002] - pop, load local S5
+  9[090] - return S1 4
 
 EqualityConstraint.execute tests/type_propagation/deltablue-test.toit
  - argument 0: {EqualityConstraint}
@@ -1211,7 +1210,7 @@ chain-test tests/type_propagation/deltablue-test.toit
  39[032] - load global var lazy G0 // {Strength}
  41[000] - load local S6
  43[017] - load local 3
- 44[053] - invoke static EqualityConstraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}, {Strength}, {Null_|Variable}, {Variable}] -> {EqualityConstraint}
+ 44[053] - invoke static EqualityConstraint tests/type_propagation/deltablue-test.toit // [{EqualityConstraint}, {Strength}, {Variable}, {Variable}] -> {EqualityConstraint}
  47[041] - pop 1
  48[015] - load local 1
  49[023] - load smi 0
diff --git a/tests/type_propagation/gold/richards-test.gold b/tests/type_propagation/gold/richards-test.gold
index db2f87c7b..ffda2485a 100644
--- a/tests/type_propagation/gold/richards-test.gold
+++ b/tests/type_propagation/gold/richards-test.gold
@@ -688,7 +688,7 @@ WorkerTask.run tests/type_propagation/richards-test.toit
  28[013] - store field, pop 1
  30[016] - load local 2
  31[009] - load field local 20 // [{WorkerTask}] -> {Null_|SmallInteger_}
- 33[061] - invoke virtual set id // [{Null_|Packet}, {Null_|SmallInteger_}] -> {SmallInteger_}
+ 33[061] - invoke virtual set id // [{Packet}, {Null_|SmallInteger_}] -> {SmallInteger_}
  36[002] - pop, load local S2
  38[023] - load smi 0
  39[061] - invoke virtual set a1 // [{Packet}, {SmallInteger_}] -> {SmallInteger_}
@@ -745,7 +745,7 @@ HandlerTask.run tests/type_propagation/richards-test.toit
   0[016] - load local 2
   1[082] - branch if false T36
   4[016] - load local 2
-  5[060] - invoke virtual get kind // [{Null_|Packet}] -> {Null_|SmallInteger_}
+  5[060] - invoke virtual get kind // [{Packet}] -> {Null_|SmallInteger_}
   8[025] - load smi 1
   9[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  10[082] - branch if false T26
diff --git a/tests/type_propagation/gold/richards-test.gold-O2 b/tests/type_propagation/gold/richards-test.gold-O2
index cfcafaaf9..7ac4bd6e9 100644
--- a/tests/type_propagation/gold/richards-test.gold-O2
+++ b/tests/type_propagation/gold/richards-test.gold-O2
@@ -639,7 +639,7 @@ WorkerTask.run tests/type_propagation/richards-test.toit
  26[013] - store field, pop 1
  28[016] - load local 2
  29[009] - load field local 20 // [{WorkerTask}] -> {Null_|SmallInteger_}
- 31[061] - invoke virtual set id // [{Null_|Packet}, {Null_|SmallInteger_}] -> {SmallInteger_}
+ 31[061] - invoke virtual set id // [{Packet}, {Null_|SmallInteger_}] -> {SmallInteger_}
  34[002] - pop, load local S2
  36[023] - load smi 0
  37[061] - invoke virtual set a1 // [{Packet}, {SmallInteger_}] -> {SmallInteger_}
@@ -693,7 +693,7 @@ HandlerTask.run tests/type_propagation/richards-test.toit
   0[016] - load local 2
   1[082] - branch if false T36
   4[016] - load local 2
-  5[060] - invoke virtual get kind // [{Null_|Packet}] -> {Null_|SmallInteger_}
+  5[060] - invoke virtual get kind // [{Packet}] -> {Null_|SmallInteger_}
   8[025] - load smi 1
   9[062] - invoke eq // [{Null_|SmallInteger_}, {SmallInteger_}] -> {True_|False_}
  10[082] - branch if false T26

From 8fed9db63c7c623652162677e67982031e30d2fd Mon Sep 17 00:00:00 2001
From: Erik Corry <erik@toit.io>
Date: Fri, 1 Dec 2023 12:30:29 +0100
Subject: [PATCH 4/4] Add O2 gold file

---
 .../gold/default-test.gold-O2                 | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 tests/type_propagation/gold/default-test.gold-O2

diff --git a/tests/type_propagation/gold/default-test.gold-O2 b/tests/type_propagation/gold/default-test.gold-O2
new file mode 100644
index 000000000..a88253d68
--- /dev/null
+++ b/tests/type_propagation/gold/default-test.gold-O2
@@ -0,0 +1,25 @@
+main tests/type_propagation/default-test.toit
+  0[020] - load literal false
+  2[053] - invoke static foo tests/type_propagation/default-test.toit // [{False_}] -> {Null_}
+  5[041] - pop 1
+  6[020] - load literal false
+  8[053] - invoke static foo2 tests/type_propagation/default-test.toit // [{False_}] -> {Null_}
+ 11[091] - return null S1 0
+
+foo tests/type_propagation/default-test.toit
+ - argument 0: {False_}
+  0[016] - load local 2
+  1[083] - branch if not null T4
+  4[016] - load local 2
+  5[082] - branch if false T8
+  8[091] - return null S0 1
+
+foo2 tests/type_propagation/default-test.toit
+ - argument 0: {False_}
+  0[016] - load local 2
+  1[083] - branch if not null T8
+  4[020] - load literal true
+  6[004] - store local, pop S3
+  8[016] - load local 2
+  9[082] - branch if false T12
+ 12[091] - return null S0 1