[llvm] 950bc6c - [LoopFuse] Change placeholder from `undef` to `poison` (#131535)

[via llvm-commits]

Author: Pedro Lobo
Date: 2025-03-16T22:44:39Z
New Revision: 950bc6cd77455b1ec1679cf9f125055e2de1910f

URL: https://github.com/llvm/llvm-project/commit/950bc6cd77455b1ec1679cf9f125055e2de1910f
DIFF: https://github.com/llvm/llvm-project/commit/950bc6cd77455b1ec1679cf9f125055e2de1910f.diff

LOG: [LoopFuse] Change placeholder from `undef` to `poison` (#131535)

Use `poison` instead of `undef` as a placeholder for phi entries of
unreachable predecessors.

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/LoopFuse.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Scalar/LoopFuse.cpp b/llvm/lib/Transforms/Scalar/LoopFuse.cpp
index eaf89b23c26f7..5bba3016ba4a1 100644
--- a/llvm/lib/Transforms/Scalar/LoopFuse.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopFuse.cpp
@@ -1968,7 +1968,7 @@ struct LoopFuser {
           PHINode::Create(LCV->getType(), 2, LCPHI->getName() + ".afterFC0");
       L1HeaderPHI->insertBefore(L1HeaderIP);
       L1HeaderPHI->addIncoming(LCV, FC0.Latch);
-      L1HeaderPHI->addIncoming(UndefValue::get(LCV->getType()),
+      L1HeaderPHI->addIncoming(PoisonValue::get(LCV->getType()),
                                FC0.ExitingBlock);
 
       LCPHI->setIncomingValue(L1LatchBBIdx, L1HeaderPHI);