[llvm] [InstCombine] Explicitly set disjoint flag when converting xor to or. (PR #74229)

[Craig Topper via llvm-commits]

https://github.com/topperc created https://github.com/llvm/llvm-project/pull/74229

None

>From 3f3886fe5a5ba5b67bafdbbde9985aedd083b3dc Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Sat, 2 Dec 2023 23:36:53 -0800
Subject: [PATCH] [InstCombine] Explicitly set disjoint flag when converting
 xor to or.

---
 llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 732a3a13daccc..4f00ce661215d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -315,6 +315,7 @@ Value *InstCombinerImpl::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
     if (DemandedMask.isSubsetOf(RHSKnown.Zero | LHSKnown.Zero)) {
       Instruction *Or =
           BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1));
+      cast<PossiblyDisjointInst>(Or)->setIsDisjoint(true);
       Or->takeName(I);
       return InsertNewInstWith(Or, I->getIterator());
     }