[llvm] 8c939f5 - [WebAssembly] Change placeholder from `undef` to `poison` (#131536)

[via llvm-commits]

Author: Pedro Lobo
Date: 2025-03-17T10:48:46Z
New Revision: 8c939f54b4907935a877e75d09ee88bf90401cb4

URL: https://github.com/llvm/llvm-project/commit/8c939f54b4907935a877e75d09ee88bf90401cb4
DIFF: https://github.com/llvm/llvm-project/commit/8c939f54b4907935a877e75d09ee88bf90401cb4.diff

LOG: [WebAssembly] Change placeholder from `undef` to `poison` (#131536)

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

Added: 
    

Modified: 
    llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
index 2d11019291a7a..0e79a13d4ccaa 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -1767,7 +1767,7 @@ void WebAssemblyLowerEmscriptenEHSjLj::handleLongjmpableCallsForWasmSjLj(
     I->eraseFromParent();
 
   // Add entries for new predecessors to phis in unwind destinations. We use
-  // 'undef' as a placeholder value. We should make sure the phis have a valid
+  // 'poison' as a placeholder value. We should make sure the phis have a valid
   // set of predecessors before running SSAUpdater, because SSAUpdater
   // internally can use existing phis to gather predecessor info rather than
   // scanning the actual CFG (See FindPredecessorBlocks in SSAUpdater.cpp for
@@ -1776,7 +1776,7 @@ void WebAssemblyLowerEmscriptenEHSjLj::handleLongjmpableCallsForWasmSjLj(
     for (PHINode &PN : UnwindDest->phis()) {
       for (auto *NewPred : NewPreds) {
         assert(PN.getBasicBlockIndex(NewPred) == -1);
-        PN.addIncoming(UndefValue::get(PN.getType()), NewPred);
+        PN.addIncoming(PoisonValue::get(PN.getType()), NewPred);
       }
     }
   }