[ControlHeightReduction] Use logical and

Use logical instead of bitwise and to combine conditions, to avoid
propagating poison from a later condition if an earlier one is
already false. This avoids introducing branch on poison.

Differential Revision: https://reviews.llvm.org/D125898

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
index 2d1b762..9611342 100644
--- a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
@@ -1981,7 +1981,8 @@ void CHR::addToMergedCondition(bool IsTrueBiased, Value *Cond,
       !isGuaranteedNotToBeUndefOrPoison(Cond))
     Cond = IRB.CreateFreeze(Cond);
 
-  MergedCondition = IRB.CreateAnd(MergedCondition, Cond);
+  // Use logical and to avoid propagating poison from later conditions.
+  MergedCondition = IRB.CreateLogicalAnd(MergedCondition, Cond);
 }
 
 void CHR::transformScopes(SmallVectorImpl<CHRScope *> &CHRScopes) {