From b6fc629942849133eaf5d8c6eb2e130ed780c5ff Mon Sep 17 00:00:00 2001
From: Maxim Vezenov <mvezenov@gmail.com>
Date: Sat, 21 Dec 2024 00:29:19 +0000
Subject: [PATCH 1/3] hoist binary operations using known induction variables
 to check for overflow

---
 .../noirc_evaluator/src/ssa/ir/instruction.rs |  2 +-
 .../src/ssa/ir/instruction/binary.rs          |  2 +-
 .../src/ssa/opt/loop_invariant.rs             | 24 ++++++++++++++++++-
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
index 23d8b425349..0c8d8affeb1 100644
--- a/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
+++ b/compiler/noirc_evaluator/src/ssa/ir/instruction.rs
@@ -22,7 +22,7 @@ use super::{
     value::{Value, ValueId},
 };
 
-mod binary;
+pub(crate) mod binary;
 mod call;
 mod cast;
 mod constrain;
diff --git a/compiler/noirc_evaluator/src/ssa/ir/instruction/binary.rs b/compiler/noirc_evaluator/src/ssa/ir/instruction/binary.rs
index 81f2f3b1e01..ce65343c7ef 100644
--- a/compiler/noirc_evaluator/src/ssa/ir/instruction/binary.rs
+++ b/compiler/noirc_evaluator/src/ssa/ir/instruction/binary.rs
@@ -294,7 +294,7 @@ impl Binary {
 }
 
 /// Evaluate a binary operation with constant arguments.
-fn eval_constant_binary_op(
+pub(crate) fn eval_constant_binary_op(
     lhs: FieldElement,
     rhs: FieldElement,
     operator: BinaryOp,
diff --git a/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs b/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
index c188ed1f80f..f0f9bacd3ff 100644
--- a/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
+++ b/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
@@ -15,7 +15,7 @@ use crate::ssa::{
         basic_block::BasicBlockId,
         function::Function,
         function_inserter::FunctionInserter,
-        instruction::{Instruction, InstructionId},
+        instruction::{binary::eval_constant_binary_op, Instruction, InstructionId},
         types::Type,
         value::ValueId,
     },
@@ -207,6 +207,7 @@ impl<'f> LoopInvariantContext<'f> {
 
         let can_be_deduplicated = instruction.can_be_deduplicated(self.inserter.function, false)
             || matches!(instruction, Instruction::MakeArray { .. })
+            || matches!(instruction, Instruction::Binary(_))
             || self.can_be_deduplicated_from_upper_bound(&instruction);
 
         is_loop_invariant && can_be_deduplicated
@@ -231,6 +232,27 @@ impl<'f> LoopInvariantContext<'f> {
                     false
                 }
             }
+            Instruction::Binary(binary) => {
+                let operand_type =
+                    self.inserter.function.dfg.type_of_value(binary.lhs).unwrap_numeric();
+
+                let lhs_const =
+                    self.inserter.function.dfg.get_numeric_constant_with_type(binary.lhs);
+                let rhs_const =
+                    self.inserter.function.dfg.get_numeric_constant_with_type(binary.rhs);
+                let (lhs, rhs) = match (
+                    lhs_const,
+                    rhs_const,
+                    self.outer_induction_variables.get(&binary.lhs),
+                    self.outer_induction_variables.get(&binary.rhs),
+                ) {
+                    (Some((lhs, _)), None, None, Some(upper_bound)) => (lhs, *upper_bound),
+                    (None, Some((rhs, _)), Some(upper_bound), None) => (*upper_bound, rhs),
+                    _ => return false,
+                };
+
+                eval_constant_binary_op(lhs, rhs, binary.operator, operand_type).is_some()
+            }
             _ => false,
         }
     }

From ed1c1d21ea36b67b5b0b7d3b79f4f646cc760f85 Mon Sep 17 00:00:00 2001
From: Maxim Vezenov <mvezenov@gmail.com>
Date: Sat, 21 Dec 2024 00:38:43 +0000
Subject: [PATCH 2/3] restrict to add and mul

---
 compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs b/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
index f0f9bacd3ff..4fdd52da871 100644
--- a/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
+++ b/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
@@ -15,7 +15,7 @@ use crate::ssa::{
         basic_block::BasicBlockId,
         function::Function,
         function_inserter::FunctionInserter,
-        instruction::{binary::eval_constant_binary_op, Instruction, InstructionId},
+        instruction::{binary::eval_constant_binary_op, BinaryOp, Instruction, InstructionId},
         types::Type,
         value::ValueId,
     },
@@ -233,6 +233,10 @@ impl<'f> LoopInvariantContext<'f> {
                 }
             }
             Instruction::Binary(binary) => {
+                if !matches!(binary.operator, BinaryOp::Add | BinaryOp::Mul) {
+                  return false;
+                }
+                
                 let operand_type =
                     self.inserter.function.dfg.type_of_value(binary.lhs).unwrap_numeric();
 

From 686506591906e752aa65929d9c5535dab21b7acc Mon Sep 17 00:00:00 2001
From: Maxim Vezenov <mvezenov@gmail.com>
Date: Sat, 21 Dec 2024 00:40:30 +0000
Subject: [PATCH 3/3] fmt

---
 compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs b/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
index 4fdd52da871..0a3c18c1b1e 100644
--- a/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
+++ b/compiler/noirc_evaluator/src/ssa/opt/loop_invariant.rs
@@ -234,9 +234,9 @@ impl<'f> LoopInvariantContext<'f> {
             }
             Instruction::Binary(binary) => {
                 if !matches!(binary.operator, BinaryOp::Add | BinaryOp::Mul) {
-                  return false;
+                    return false;
                 }
-                
+
                 let operand_type =
                     self.inserter.function.dfg.type_of_value(binary.lhs).unwrap_numeric();