[LoopFuse] Change placeholder from undef to poison

[pedroclobo]

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

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Pedro Lobo (pedroclobo)

Changes

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

---

Full diff: https://github.com/llvm/llvm-project/pull/131535.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Scalar/LoopFuse.cpp (+1-1)

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);

[llvm-ci]

LLVM Buildbot has detected a new failure on builder clang-cmake-x86_64-avx512-win running on avx512-intel64-win while building llvm at step 4 "cmake stage 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/81/builds/5303

Here is the relevant piece of the build log for the reference

Step 4 (cmake stage 1) failure: 'cmake -G ...' (failure)
'cmake' is not recognized as an internal or external command,
operable program or batch file.