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-rw-r--r--llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp4
1 files changed, 2 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 07ad65c..fba1ccf 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1481,13 +1481,13 @@ Instruction *InstCombinerImpl::foldICmpTruncConstant(ICmpInst &Cmp,
return new ICmpInst(Pred, Y, ConstantInt::get(SrcTy, C.logBase2()));
}
- if (Cmp.isEquality() && Trunc->hasOneUse()) {
+ if (Cmp.isEquality() && (Trunc->hasOneUse() || Trunc->hasNoUnsignedWrap())) {
// Canonicalize to a mask and wider compare if the wide type is suitable:
// (trunc X to i8) == C --> (X & 0xff) == (zext C)
if (!SrcTy->isVectorTy() && shouldChangeType(DstBits, SrcBits)) {
Constant *Mask =
ConstantInt::get(SrcTy, APInt::getLowBitsSet(SrcBits, DstBits));
- Value *And = Builder.CreateAnd(X, Mask);
+ Value *And = Trunc->hasNoUnsignedWrap() ? X : Builder.CreateAnd(X, Mask);
Constant *WideC = ConstantInt::get(SrcTy, C.zext(SrcBits));
return new ICmpInst(Pred, And, WideC);
}