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[clang][FMV] Fix crash with cpu_specific attribute. #115762

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Merged
merged 4 commits into from
Nov 26, 2024
Merged

[clang][FMV] Fix crash with cpu_specific attribute. #115762

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aff962d
[clang][FMV] Fix crash with cpu_specific attribute.
labrinea Nov 11, 2024
7e61a41
changes from last revision:
labrinea Nov 15, 2024
e0854c2
Retain the original test and add a new one to reproduce the crash.
labrinea Nov 15, 2024
e520544
Merge branch 'main' into cpu-specific-attr
labrinea Nov 25, 2024
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12 changes: 6 additions & 6 deletions clang/lib/CodeGen/CodeGenModule.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4562,15 +4562,17 @@ llvm::Constant *CodeGenModule::GetOrCreateMultiVersionResolver(GlobalDecl GD) {
ResolverName += ".resolver";
}

bool ShouldReturnIFunc =
getTarget().supportsIFunc() && !FD->isCPUSpecificMultiVersion();

// If the resolver has already been created, just return it. This lookup may
// yield a function declaration instead of a resolver on AArch64. That is
// because we didn't know whether a resolver will be generated when we first
// encountered a use of the symbol named after this resolver. Therefore,
// targets which support ifuncs should not return here unless we actually
// found an ifunc.
llvm::GlobalValue *ResolverGV = GetGlobalValue(ResolverName);
if (ResolverGV &&
(isa<llvm::GlobalIFunc>(ResolverGV) || !getTarget().supportsIFunc()))
if (ResolverGV && (isa<llvm::GlobalIFunc>(ResolverGV) || !ShouldReturnIFunc))
return ResolverGV;

const CGFunctionInfo &FI = getTypes().arrangeGlobalDeclaration(GD);
Expand All @@ -4583,7 +4585,7 @@ llvm::Constant *CodeGenModule::GetOrCreateMultiVersionResolver(GlobalDecl GD) {

// For cpu_specific, don't create an ifunc yet because we don't know if the
// cpu_dispatch will be emitted in this translation unit.
if (getTarget().supportsIFunc() && !FD->isCPUSpecificMultiVersion()) {
if (ShouldReturnIFunc) {
unsigned AS = getTypes().getTargetAddressSpace(FD->getType());
llvm::Type *ResolverType =
llvm::FunctionType::get(llvm::PointerType::get(DeclTy, AS), false);
Expand All @@ -4602,11 +4604,9 @@ llvm::Constant *CodeGenModule::GetOrCreateMultiVersionResolver(GlobalDecl GD) {

llvm::Constant *Resolver = GetOrCreateLLVMFunction(
ResolverName, DeclTy, GlobalDecl{}, /*ForVTable=*/false);
assert(isa<llvm::GlobalValue>(Resolver) &&
assert(isa<llvm::GlobalValue>(Resolver) && !ResolverGV &&
"Resolver should be created for the first time");
SetCommonAttributes(FD, cast<llvm::GlobalValue>(Resolver));
if (ResolverGV)
replaceDeclarationWith(ResolverGV, Resolver);
return Resolver;
}

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6 changes: 6 additions & 0 deletions clang/test/CodeGen/attr-cpuspecific.c
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Expand Up @@ -154,6 +154,12 @@ void usages(void) {
CpuSpecificNoDispatch();
// LINUX: @CpuSpecificNoDispatch.ifunc()
// WINDOWS: @CpuSpecificNoDispatch()
//
// Adding another use of CpuSpecificNoDispatch reproduces the
// crash in https://github.com/llvm/llvm-project/issues/115299
CpuSpecificNoDispatch();
// LINUX: @CpuSpecificNoDispatch.ifunc()
// WINDOWS: @CpuSpecificNoDispatch()
OrderDispatchUsageSpecific();
// LINUX: @OrderDispatchUsageSpecific.ifunc()
// WINDOWS: @OrderDispatchUsageSpecific()
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