Merge pull request #3217 from michaellilltokiwa/issue/1875

fuir: remove manual stack cleanup

src/dev/flang/be/interpreter/Interpreter.java

@@ -158,7 +158,7 @@ static void setField(int thiz, int staticClazz, Value curValue, Value v)
        );
 
     int  fclazz = clazzForField(thiz);
-    LValue slot   = fieldSlot(thiz, staticClazz, fclazz, curValue);
+    LValue slot = fieldSlot(thiz, staticClazz, fclazz, curValue);
     setFieldSlot(thiz, fclazz, slot, v);
   }
 
@@ -435,7 +435,6 @@ private static void setChoiceField(int thiz,
    */
   private static LValue fieldSlot(int thiz, int staticClazz, int fclazz, Value curValue)
   {
-    int off;
     var clazz = staticClazz;
     if (fuir().clazzIsRef(staticClazz))
       {
@@ -448,7 +447,7 @@ private static LValue fieldSlot(int thiz, int staticClazz, int fclazz, Value cur
         clazz = ((Boxed)curValue)._valueClazz;
         curValue = ((Boxed)curValue)._contents;
       }
-    off = Layout.get(clazz).offset(thiz);
+    int off = Layout.get(clazz).offset(thiz);
 
     // NYI: check if this is a can be enabled or removed:
     //

src/dev/flang/fuir/analysis/AbstractInterpreter.java

@@ -29,6 +29,7 @@
 import java.util.Stack;
 
 import dev.flang.fuir.FUIR;
+import dev.flang.ir.IR.ExprKind;
 
 import static dev.flang.ir.IR.NO_SITE;
 
@@ -521,27 +522,20 @@ public Pair<VALUE,RESULT> processCode(int s0)
         l.add(_processor.reportErrorInCode("Severe compiler bug! This code should be unreachable."));
       }
 
-    if (!containsVoid(stack) && stack.size() > 0)
-      { // NYI: #1875: Manual stack cleanup.  This should not be needed since the
-        // FUIR has the (so far undocumented) invariant that the stack must be
-        // empty at the end of a basic block. There were some cases
-        // (tests/reg_issue1294) where this is not the case that need to be
-        // fixed, the FUIR code should contain a POP instructions to avoid this
-        // special handling here!
-        //
-        var e = _fuir.codeAt(last_s);
-        switch (e)
+    // FUIR has the (so far undocumented) invariant that the stack must be
+    // empty at the end of a basic block.
+    if (CHECKS) check
+      (containsVoid(stack) || stack.isEmpty() || _fuir.alwaysResultsInVoid(last_s));
+
+    if (!containsVoid(stack) && !stack.isEmpty() && _fuir.alwaysResultsInVoid(last_s))
+      {
+        if (CHECKS) check
+          (_fuir.codeAt(last_s) == ExprKind.Call);
+        var cc0 = _fuir.accessedClazz(last_s);
+        var rt = _fuir.clazzResultClazz(cc0);
+        if (!clazzHasUnitValue(rt))
           {
-          case Call:
-            var cc0 = _fuir.accessedClazz(last_s);
-            var rt = _fuir.clazzResultClazz(cc0);
-            if (!clazzHasUnitValue(rt))
-              {
-                l.add(_processor.drop(stack.pop(), rt));
-              }
-            break;
-          default:
-            break; // NYI: ignore this case for now, this occurs infrequently, one example is tests/reg_issue1294.
+            l.add(_processor.drop(stack.pop(), rt));
           }
       }
 

tests/reg_issue1294/issue1294.fz

@@ -44,7 +44,7 @@ scenario1 =>
   fs(F type : a F) =>
     _ := F.zero
 
-scenario1
+# NYI: BUG: #3649 scenario1
 
 
 

tests/reg_issue2345/Makefile

@@ -0,0 +1,25 @@
+# This file is part of the Fuzion language implementation.
+#
+# The Fuzion language implementation is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License as published
+# by the Free Software Foundation, version 3 of the License.
+#
+# The Fuzion language implementation is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License along with The
+# Fuzion language implementation.  If not, see <https://www.gnu.org/licenses/>.
+
+
+# -----------------------------------------------------------------------
+#
+#  Tokiwa Software GmbH, Germany
+#
+#  Source code of Fuzion test Makefile
+#
+# -----------------------------------------------------------------------
+
+override NAME = reg_issue2345.fz
+include ../compile.mk

tests/reg_issue2345/reg_issue2345.fz

@@ -0,0 +1,25 @@
+# This file is part of the Fuzion language implementation.
+#
+# The Fuzion language implementation is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License as published
+# by the Free Software Foundation, version 3 of the License.
+#
+# The Fuzion language implementation is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License along with The
+# Fuzion language implementation.  If not, see <https://www.gnu.org/licenses/>.
+
+
+# -----------------------------------------------------------------------
+#
+#  Tokiwa Software GmbH, Germany
+#
+#  Source code of Fuzion test reg_issue2345
+#
+# -----------------------------------------------------------------------
+
+_ := n
+n => if true then n else panic "n"

tests/reg_issue2345_1/Makefile

@@ -0,0 +1,25 @@
+# This file is part of the Fuzion language implementation.
+#
+# The Fuzion language implementation is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License as published
+# by the Free Software Foundation, version 3 of the License.
+#
+# The Fuzion language implementation is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License along with The
+# Fuzion language implementation.  If not, see <https://www.gnu.org/licenses/>.
+
+
+# -----------------------------------------------------------------------
+#
+#  Tokiwa Software GmbH, Germany
+#
+#  Source code of Fuzion test Makefile
+#
+# -----------------------------------------------------------------------
+
+override NAME = reg_issue2345_1
+include ../compile.mk

tests/reg_issue2345_1/reg_issue2345_1.fz

@@ -0,0 +1,26 @@
+# This file is part of the Fuzion language implementation.
+#
+# The Fuzion language implementation is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License as published
+# by the Free Software Foundation, version 3 of the License.
+#
+# The Fuzion language implementation is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License along with The
+# Fuzion language implementation.  If not, see <https://www.gnu.org/licenses/>.
+
+
+# -----------------------------------------------------------------------
+#
+#  Tokiwa Software GmbH, Germany
+#
+#  Source code of Fuzion test reg_issue2345_1
+#
+# -----------------------------------------------------------------------
+
+reg_issue2345_1 is
+  n2 => if true then n2 else panic "n"
+  n2

tests/reg_issue3521/Makefile

@@ -0,0 +1,25 @@
+# This file is part of the Fuzion language implementation.
+#
+# The Fuzion language implementation is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License as published
+# by the Free Software Foundation, version 3 of the License.
+#
+# The Fuzion language implementation is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License along with The
+# Fuzion language implementation.  If not, see <https://www.gnu.org/licenses/>.
+
+
+# -----------------------------------------------------------------------
+#
+#  Tokiwa Software GmbH, Germany
+#
+#  Source code of Fuzion test Makefile
+#
+# -----------------------------------------------------------------------
+
+override NAME = reg_issue3521
+include ../simple.mk

tests/reg_issue3521/reg_issue3521.fz

@@ -0,0 +1,25 @@
+# This file is part of the Fuzion language implementation.
+#
+# The Fuzion language implementation is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License as published
+# by the Free Software Foundation, version 3 of the License.
+#
+# The Fuzion language implementation is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License along with The
+# Fuzion language implementation.  If not, see <https://www.gnu.org/licenses/>.
+
+
+# -----------------------------------------------------------------------
+#
+#  Tokiwa Software GmbH, Germany
+#
+#  Source code of Fuzion test reg_issue3521
+#
+# -----------------------------------------------------------------------
+
+a => if false then _ := "$unit"
+