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

[Craig Topper via llvm-commits]

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

>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 1/2] [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 732a3a13dacc..4f00ce661215 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());
     }

>From ea3f27cae64457899efc32afd66a4185f913590a Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Sun, 3 Dec 2023 00:01:22 -0800
Subject: [PATCH 2/2] Update another xor->or transform

---
 llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 7379bdf93169..2e1f3df4858e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -4462,8 +4462,11 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
   Value *M;
   if (match(&I, m_c_Xor(m_c_And(m_Not(m_Value(M)), m_Value()),
-                        m_c_And(m_Deferred(M), m_Value()))))
-    return BinaryOperator::CreateOr(Op0, Op1);
+                        m_c_And(m_Deferred(M), m_Value())))) {
+    auto *Or = BinaryOperator::CreateOr(Op0, Op1);
+    cast<PossiblyDisjointInst>(Or)->setIsDisjoint(true);
+    return Or;
+  }
 
   if (Instruction *Xor = visitMaskedMerge(I, Builder))
     return Xor;