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IRGen: Default to clang's frame pointer elimination settings

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Clang provides options to override that default value.
These options are accessible via the -Xcc flag.

Some Swift functions explicitly disable the frame pointer.

The clang options will not override those.
This commit is contained in:
Arnold Schwaighofer
2020-05-22 12:33:30 -07:00
parent 456775f8b4
commit 20f4ef93de
10 changed files with 57 additions and 77 deletions
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68
lib/IRGen/IRGenModule.cpp
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@@ -90,26 +90,11 @@ static llvm::PointerType *createStructPointerType(IRGenModule &IGM,
return createStructType(IGM, name, types)->getPointerTo(DefaultAS);
};
static clang::CodeGenOptions::FramePointerKind
shouldUseFramePointer(const IRGenOptions &Opts, const llvm::Triple &triple) {
if (Opts.DisableFPElim) {
// General frame pointer elimination is disabled.
// Should we at least eliminate in leaf functions?
// Currently we only do that on arm64 (this matches the behavior of clang).
return Opts.DisableFPElimLeaf
? clang::CodeGenOptions::FramePointerKind::All
: triple.isAArch64()
? clang::CodeGenOptions::FramePointerKind::NonLeaf
: clang::CodeGenOptions::FramePointerKind::All;
}
return clang::CodeGenOptions::FramePointerKind::None;
}
static clang::CodeGenerator *
createClangCodeGenerator(ASTContext &Context, llvm::LLVMContext &LLVMContext,
const IRGenOptions &Opts, StringRef ModuleName,
StringRef PD, const llvm::Triple &triple) {
static clang::CodeGenerator *createClangCodeGenerator(ASTContext &Context,
llvm::LLVMContext &LLVMContext,
const IRGenOptions &Opts,
StringRef ModuleName,
StringRef PD) {
auto Loader = Context.getClangModuleLoader();
auto *Importer = static_cast<ClangImporter*>(&*Loader);
assert(Importer && "No clang module loader!");
@@ -117,7 +102,7 @@ createClangCodeGenerator(ASTContext &Context, llvm::LLVMContext &LLVMContext,
auto &CGO = Importer->getClangCodeGenOpts();
CGO.OptimizationLevel = Opts.shouldOptimize() ? 3 : 0;
CGO.setFramePointer(shouldUseFramePointer(Opts, triple));
CGO.DiscardValueNames = !Opts.shouldProvideValueNames();
switch (Opts.DebugInfoLevel) {
case IRGenDebugInfoLevel::None:
@@ -207,17 +192,17 @@ static void sanityCheckStdlib(IRGenModule &IGM) {
IRGenModule::IRGenModule(IRGenerator &irgen,
std::unique_ptr<llvm::TargetMachine> &&target,
SourceFile *SF, StringRef ModuleName,
StringRef OutputFilename,
SourceFile *SF,
StringRef ModuleName, StringRef OutputFilename,
StringRef MainInputFilenameForDebugInfo,
StringRef PrivateDiscriminator)
: LLVMContext(new llvm::LLVMContext()), IRGen(irgen),
Context(irgen.SIL.getASTContext()),
: LLVMContext(new llvm::LLVMContext()),
IRGen(irgen), Context(irgen.SIL.getASTContext()),
// The LLVMContext (and the IGM itself) will get deleted by the IGMDeleter
// as long as the IGM is registered with the IRGenerator.
ClangCodeGen(createClangCodeGenerator(Context, *LLVMContext, irgen.Opts,
ModuleName, PrivateDiscriminator,
irgen.getEffectiveClangTriple())),
ClangCodeGen(createClangCodeGenerator(Context, *LLVMContext,
irgen.Opts,
ModuleName, PrivateDiscriminator)),
Module(*ClangCodeGen->GetModule()),
DataLayout(irgen.getClangDataLayout()),
Triple(irgen.getEffectiveClangTriple()), TargetMachine(std::move(target)),
@@ -999,28 +984,13 @@ bool swift::irgen::shouldRemoveTargetFeature(StringRef feature) {
return feature == "+thumb-mode";
}
void IRGenModule::setHasFramePointer(llvm::AttrBuilder &Attrs,
bool HasFramePointer) {
if (!HasFramePointer) {
Attrs.addAttribute("frame-pointer", "none");
return;
}
if (IRGen.Opts.DisableFPElimLeaf) {
Attrs.addAttribute("frame-pointer", "all");
return;
}
// We omit frame pointers for leaf functions only for arm64 for now (matching
// clang's behavior).
auto framePointer =
IRGen.getEffectiveClangTriple().isAArch64() ? "non-leaf" : "all";
Attrs.addAttribute("frame-pointer", framePointer);
void IRGenModule::setHasNoFramePointer(llvm::AttrBuilder &Attrs) {
Attrs.addAttribute("frame-pointer", "none");
}
void IRGenModule::setHasFramePointer(llvm::Function *F,
bool HasFramePointer) {
void IRGenModule::setHasNoFramePointer(llvm::Function *F) {
llvm::AttrBuilder b;
setHasFramePointer(b, HasFramePointer);
setHasNoFramePointer(b);
F->addAttributes(llvm::AttributeList::FunctionIndex, b);
}
@@ -1030,10 +1000,6 @@ void IRGenModule::constructInitialFnAttributes(llvm::AttrBuilder &Attrs,
// Add the default attributes for the Clang configuration.
clang::CodeGen::addDefaultFunctionDefinitionAttributes(getClangCGM(), Attrs);
// Add frame pointer attributes.
// FIXME: why are we doing this?
setHasFramePointer(Attrs, IRGen.Opts.DisableFPElim);
// Add/remove MinSize based on the appropriate setting.
if (FuncOptMode == OptimizationMode::NotSet)
FuncOptMode = IRGen.Opts.OptMode;