[llvm] [InstCombine] Freeze can be avoided if we propagate NUW or NSW (PR #96261)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: AtariDreams (AtariDreams)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/96261.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp (+3-1) 


``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 8fcb3544f682a..ff4c72074312b 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -166,7 +166,9 @@ static Value *foldMulShl1(BinaryOperator &Mul, bool CommuteOperands,
   if (match(Y, m_OneUse(m_Add(m_BinOp(Shift), m_One()))) &&
       match(Shift, m_OneUse(m_Shl(m_One(), m_Value(Z))))) {
     bool PropagateNSW = HasNSW && Shift->hasNoSignedWrap();
-    Value *FrX = Builder.CreateFreeze(X, X->getName() + ".fr");
+    Value* FrX = X;
+    if (!HasNUW && !HasNSW)
+      FrX = Builder.CreateFreeze(X, X->getName() + ".fr");
     Value *Shl = Builder.CreateShl(FrX, Z, "mulshl", HasNUW, PropagateNSW);
     return Builder.CreateAdd(Shl, FrX, Mul.getName(), HasNUW, PropagateNSW);
   }

``````````

</details>


https://github.com/llvm/llvm-project/pull/96261