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Fix WebAssemblySpillPointers crash at O2: move pass before PEI #4

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Merged
PLUTOFX merged 2 commits into from
Feb 28, 2026
Merged

Fix WebAssemblySpillPointers crash at O2: move pass before PEI #4

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b4f738d
Initial plan
Copilot Feb 28, 2026
cc2af38
Fix WebAssemblySpillPointers: move pass from addPreEmitPass to addPos…
Copilot Feb 28, 2026
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1 change: 1 addition & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -70,3 +70,4 @@ pythonenv*
/clang/utils/analyzer/projects/*/RefScanBuildResults
# automodapi puts generated documentation files here.
/lldb/docs/python_api/
build/
1 change: 0 additions & 1 deletion llvm/lib/Target/WebAssembly/WebAssemblySpillPointers.cpp
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Expand Up @@ -46,7 +46,6 @@ class WebAssemblySpillPointers final : public MachineFunctionPass {
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<LiveIntervals>();
AU.addPreserved<LiveIntervals>();
MachineFunctionPass::getAnalysisUsage(AU);
}

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10 changes: 5 additions & 5 deletions llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
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Expand Up @@ -525,6 +525,11 @@ void WebAssemblyPassConfig::addPostRegAlloc() {
// control flow.
disablePass(&MachineBlockPlacementID);

// Spill pointer-typed values to shadow stack for GC.
// This must run before PEI so that frame indices are properly resolved.
if (getOptLevel() != CodeGenOpt::None)
addPass(createWebAssemblySpillPointers());

TargetPassConfig::addPostRegAlloc();
}

Expand Down Expand Up @@ -568,11 +573,6 @@ void WebAssemblyPassConfig::addPreEmitPass() {
addPass(createWebAssemblyRegColoring());
}

// Spill pointer-typed values to shadow stack for GC.
// This must run after register allocation but before explicit locals.
if (getOptLevel() != CodeGenOpt::None)
addPass(createWebAssemblySpillPointers());

// Sort the blocks of the CFG into topological order, a prerequisite for
// BLOCK and LOOP markers.
addPass(createWebAssemblyCFGSort());
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