[llvm] [clang] [InstCombine] Set disjoint flag when turning Add into Or. (PR #72702)

[Nikita Popov via cfe-commits]

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@@ -255,8 +255,11 @@ Value *InstCombinerImpl::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
       return I->getOperand(1);
 
     // If the RHS is a constant, see if we can simplify it.
-    if (ShrinkDemandedConstant(I, 1, DemandedMask))
+    if (ShrinkDemandedConstant(I, 1, DemandedMask)) {
+      // Disjoint flag may not longer hold.
+      I->dropPoisonGeneratingFlags();
       return I;
+    }
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nikic wrote:

Rebase mistake?

https://github.com/llvm/llvm-project/pull/72702