[llvm] be29612 - [NewGVN] Remove returned arg simplification (#161865)

[via llvm-commits]

Author: ManuelJBrito
Date: 2025-10-03T20:52:29+01:00
New Revision: be29612ffceac888f931dc45664f7c42cea9b598

URL: https://github.com/llvm/llvm-project/commit/be29612ffceac888f931dc45664f7c42cea9b598
DIFF: https://github.com/llvm/llvm-project/commit/be29612ffceac888f931dc45664f7c42cea9b598.diff

LOG: [NewGVN] Remove returned arg simplification (#161865)

Replacing uses of the return value with the argument is already handled
in other passes, additionally it causes issues with memory value
numbering when the call is a memory defining intrinsic.
fixes #159918

Added: 
    llvm/test/Transforms/NewGVN/pr159918.ll

Modified: 
    llvm/lib/Transforms/Scalar/NewGVN.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Scalar/NewGVN.cpp b/llvm/lib/Transforms/Scalar/NewGVN.cpp
index 9d4fb79416596..d6b76335dbb9f 100644
--- a/llvm/lib/Transforms/Scalar/NewGVN.cpp
+++ b/llvm/lib/Transforms/Scalar/NewGVN.cpp
@@ -1646,10 +1646,6 @@ NewGVN::performSymbolicPredicateInfoEvaluation(BitCastInst *I) const {
 // Evaluate read only and pure calls, and create an expression result.
 NewGVN::ExprResult NewGVN::performSymbolicCallEvaluation(Instruction *I) const {
   auto *CI = cast<CallInst>(I);
-  if (auto *II = dyn_cast<IntrinsicInst>(I)) {
-    if (auto *ReturnedValue = II->getReturnedArgOperand())
-      return ExprResult::some(createVariableOrConstant(ReturnedValue));
-  }
 
   // FIXME: Currently the calls which may access the thread id may
   // be considered as not accessing the memory. But this is

diff  --git a/llvm/test/Transforms/NewGVN/pr159918.ll b/llvm/test/Transforms/NewGVN/pr159918.ll
new file mode 100644
index 0000000000000..3fad6e66d11ac
--- /dev/null
+++ b/llvm/test/Transforms/NewGVN/pr159918.ll
@@ -0,0 +1,21 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -S -passes=newgvn < %s | FileCheck %s
+
+; Don't use returned argument in memory defining intrinsics.
+define void @wombat(ptr %arg) {
+; CHECK-LABEL: define void @wombat(
+; CHECK-SAME: ptr [[ARG:%.*]]) {
+; CHECK-NEXT:    [[LOAD:%.*]] = load ptr, ptr [[ARG]], align 8
+; CHECK-NEXT:    [[CALL:%.*]] = call ptr @llvm.objc.retain(ptr [[LOAD]])
+; CHECK-NEXT:    store ptr [[CALL]], ptr [[ARG]], align 8
+; CHECK-NEXT:    ret void
+;
+  %load = load ptr, ptr %arg, align 8
+  %call = call ptr @llvm.objc.retain(ptr %load)
+  store ptr %call, ptr %arg, align 8
+  ret void
+}
+
+declare ptr @llvm.objc.retain(ptr returned) #0
+
+attributes #0 = { nounwind }