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[CodeGen] Set attributes on resolvers emitted after ifuncs #98832

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merged 3 commits into from
Jul 15, 2024
Merged

[CodeGen] Set attributes on resolvers emitted after ifuncs #98832

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15011e6
[𝘀𝗽𝗿] initial version
MaskRay Jul 14, 2024
a7e1889
.
MaskRay Jul 14, 2024
fd9bdea
fix typo
MaskRay Jul 15, 2024
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17 changes: 11 additions & 6 deletions clang/lib/CodeGen/CodeGenModule.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -721,6 +721,11 @@ void CodeGenModule::checkAliases() {
cast<llvm::GlobalAlias>(Alias)->setAliasee(Aliasee);
}
}
// ifunc resolvers are usually implemented to run before sanitizer
// initialization. Disable instrumentation to prevent the ordering issue.
if (IsIFunc)
cast<llvm::Function>(Aliasee)->addFnAttr(
llvm::Attribute::DisableSanitizerInstrumentation);
}
if (!Error)
return;
Expand Down Expand Up @@ -6106,11 +6111,14 @@ void CodeGenModule::emitIFuncDefinition(GlobalDecl GD) {

Aliases.push_back(GD);

llvm::Type *DeclTy = getTypes().ConvertTypeForMem(D->getType());
llvm::Type *ResolverTy = llvm::GlobalIFunc::getResolverFunctionType(DeclTy);
// The resolver might not be visited yet. Specify a dummy non-function type to
// indicate IsIncompleteFunction. Either the type is ignored (if the resolver
// was emitted) or the whole function will be replaced (if the resolver has
// not been emitted).
llvm::Constant *Resolver =
GetOrCreateLLVMFunction(IFA->getResolver(), ResolverTy, {},
GetOrCreateLLVMFunction(IFA->getResolver(), VoidTy, {},
/*ForVTable=*/false);
llvm::Type *DeclTy = getTypes().ConvertTypeForMem(D->getType());
llvm::GlobalIFunc *GIF =
llvm::GlobalIFunc::create(DeclTy, 0, llvm::Function::ExternalLinkage,
"", Resolver, &getModule());
Expand All @@ -6134,9 +6142,6 @@ void CodeGenModule::emitIFuncDefinition(GlobalDecl GD) {
Entry->eraseFromParent();
} else
GIF->setName(MangledName);
if (auto *F = dyn_cast<llvm::Function>(Resolver)) {
F->addFnAttr(llvm::Attribute::DisableSanitizerInstrumentation);
}
SetCommonAttributes(GD, GIF);
}

Expand Down
9 changes: 4 additions & 5 deletions clang/test/CodeGen/ifunc.c
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Expand Up @@ -58,12 +58,11 @@ extern void hoo(int) __attribute__ ((ifunc("hoo_ifunc")));
// CHECK: call i32 @foo(i32
// CHECK: call void @goo()

// SAN: define internal nonnull {{(noundef )?}}ptr @foo_ifunc() #[[#FOO_IFUNC:]] {

// SAN: define {{(dso_local )?}}noalias {{(noundef )?}}ptr @goo_ifunc() #[[#GOO_IFUNC:]] {

// SAN: define {{(dso_local )?}}noalias {{(noundef )?}}ptr @hoo_ifunc() #[[#HOO_IFUNC:]] {
// SAN: define {{(dso_local )?}}noalias {{(noundef )?}}ptr @hoo_ifunc() #[[#GOO_IFUNC]] {

// SAN: define internal {{(noundef )?}}nonnull ptr @foo_ifunc() #[[#FOO_IFUNC:]] {

// SAN-DAG: attributes #[[#FOO_IFUNC]] = {{{.*}} disable_sanitizer_instrumentation {{.*}}
// SAN-DAG: attributes #[[#GOO_IFUNC]] = {{{.*}} disable_sanitizer_instrumentation {{.*}}
// SAN-DAG: attributes #[[#HOO_IFUNC]] = {{{.*}} disable_sanitizer_instrumentation {{.*}}
// SAN-DAG: attributes #[[#FOO_IFUNC]] = {{{.*}} disable_sanitizer_instrumentation {{.*}}
20 changes: 10 additions & 10 deletions clang/test/CodeGen/kcfi.c
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Expand Up @@ -33,16 +33,6 @@ int call(fn_t f) {
return f();
}

#ifndef __cplusplus
// C: define internal ptr @resolver1() #[[#]] {
int ifunc1(int) __attribute__((ifunc("resolver1")));
static void *resolver1(void) { return 0; }

// C: define internal ptr @resolver2() #[[#]] {
static void *resolver2(void) { return 0; }
long ifunc2(long) __attribute__((ifunc("resolver2")));
#endif

// CHECK-DAG: define internal{{.*}} i32 @{{f3|_ZL2f3v}}(){{.*}} !kcfi_type ![[#TYPE]]
static int f3(void) { return 1; }

Expand All @@ -58,6 +48,16 @@ static int f5(void) { return 2; }
// CHECK-DAG: declare !kcfi_type ![[#TYPE]]{{.*}} i32 @{{f6|_Z2f6v}}()
extern int f6(void);

#ifndef __cplusplus
// C: define internal ptr @resolver1() #[[#]] !kcfi_type ![[#]] {
int ifunc1(int) __attribute__((ifunc("resolver1")));
static void *resolver1(void) { return 0; }

// C: define internal ptr @resolver2() #[[#]] !kcfi_type ![[#]] {
static void *resolver2(void) { return 0; }
long ifunc2(long) __attribute__((ifunc("resolver2")));
#endif

int test(void) {
return call(f1) +
__call((fn_t)f2) +
Expand Down
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