[llvm] [LICM] Preserve Disjoint flag on OR when hoisting. (PR #140266)

[Philip Reames via llvm-commits]

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@@ -2877,6 +2877,12 @@ static bool hoistBOAssociation(Instruction &I, Loop &L,
     if (auto *I = dyn_cast<Instruction>(Inv))
       I->setFastMathFlags(Intersect);
     NewBO->setFastMathFlags(Intersect);
+  } else if (Opcode == Instruction::Or) {
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preames wrote:

Actually, unless I'm missing something, Reassociate.cpp has the same problem of dropping disjoint flags.  Note that there is the existing OverflowTracking helper, which might serve as a starting place for the API.

https://github.com/llvm/llvm-project/pull/140266