llvm-project/clang/lib/AST/Mangle.cpp
Michael Buch cd8f348c69
[clang][Attr] Remove 'literal label' form of AsmLabelAttr (#151858)
This was added purely for the needs of LLDB. However, starting with
https://github.com/llvm/llvm-project/pull/151355 and
https://github.com/llvm/llvm-project/pull/148877 we no longer create
literal AsmLabels in LLDB either. So this is unused and we can get rid
of it.

In the near future LLDB will want to add special support for mangling
`AsmLabel`s (specifically
https://github.com/llvm/llvm-project/pull/149827).
2025-08-04 14:34:45 +01:00

633 lines
21 KiB
C++

//===--- Mangle.cpp - Mangle C++ Names --------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Implements generic name mangling support for blocks and Objective-C.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/Mangle.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/VTableBuilder.h"
#include "clang/Basic/ABI.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Mangler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
void clang::mangleObjCMethodName(raw_ostream &OS, bool includePrefixByte,
bool isInstanceMethod, StringRef ClassName,
std::optional<StringRef> CategoryName,
StringRef MethodName) {
// \01+[ContainerName(CategoryName) SelectorName]
if (includePrefixByte)
OS << "\01";
OS << (isInstanceMethod ? '-' : '+');
OS << '[';
OS << ClassName;
if (CategoryName)
OS << "(" << *CategoryName << ")";
OS << " ";
OS << MethodName;
OS << ']';
}
// FIXME: For blocks we currently mimic GCC's mangling scheme, which leaves
// much to be desired. Come up with a better mangling scheme.
static void mangleFunctionBlock(MangleContext &Context,
StringRef Outer,
const BlockDecl *BD,
raw_ostream &Out) {
unsigned discriminator = Context.getBlockId(BD, true);
if (discriminator == 0)
Out << "__" << Outer << "_block_invoke";
else
Out << "__" << Outer << "_block_invoke_" << discriminator+1;
}
void MangleContext::anchor() { }
enum CCMangling {
CCM_Other,
CCM_Fast,
CCM_RegCall,
CCM_Vector,
CCM_Std,
CCM_WasmMainArgcArgv
};
static bool isExternC(const NamedDecl *ND) {
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))
return FD->isExternC();
if (const VarDecl *VD = dyn_cast<VarDecl>(ND))
return VD->isExternC();
return false;
}
static CCMangling getCallingConvMangling(const ASTContext &Context,
const NamedDecl *ND) {
const TargetInfo &TI = Context.getTargetInfo();
const llvm::Triple &Triple = TI.getTriple();
// On wasm, the argc/argv form of "main" is renamed so that the startup code
// can call it with the correct function signature.
if (Triple.isWasm())
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))
if (FD->isMain() && FD->getNumParams() == 2)
return CCM_WasmMainArgcArgv;
if (!TI.shouldUseMicrosoftCCforMangling())
return CCM_Other;
if (Context.getLangOpts().CPlusPlus && !isExternC(ND) &&
TI.getCXXABI() == TargetCXXABI::Microsoft)
return CCM_Other;
const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND);
if (!FD)
return CCM_Other;
QualType T = FD->getType();
const FunctionType *FT = T->castAs<FunctionType>();
CallingConv CC = FT->getCallConv();
switch (CC) {
default:
return CCM_Other;
case CC_X86FastCall:
return CCM_Fast;
case CC_X86StdCall:
return CCM_Std;
case CC_X86VectorCall:
return CCM_Vector;
}
}
bool MangleContext::shouldMangleDeclName(const NamedDecl *D) {
const ASTContext &ASTContext = getASTContext();
CCMangling CC = getCallingConvMangling(ASTContext, D);
if (CC != CCM_Other)
return true;
// If the declaration has an owning module for linkage purposes that needs to
// be mangled, we must mangle its name.
if (!D->hasExternalFormalLinkage() && D->getOwningModuleForLinkage())
return true;
// C functions with internal linkage have to be mangled with option
// -funique-internal-linkage-names.
if (!getASTContext().getLangOpts().CPlusPlus &&
isUniqueInternalLinkageDecl(D))
return true;
// In C, functions with no attributes never need to be mangled. Fastpath them.
if (!getASTContext().getLangOpts().CPlusPlus && !D->hasAttrs())
return false;
// Any decl can be declared with __asm("foo") on it, and this takes precedence
// over all other naming in the .o file.
if (D->hasAttr<AsmLabelAttr>())
return true;
// Declarations that don't have identifier names always need to be mangled.
if (isa<MSGuidDecl>(D))
return true;
return shouldMangleCXXName(D);
}
void MangleContext::mangleName(GlobalDecl GD, raw_ostream &Out) {
const ASTContext &ASTContext = getASTContext();
const NamedDecl *D = cast<NamedDecl>(GD.getDecl());
// Any decl can be declared with __asm("foo") on it, and this takes precedence
// over all other naming in the .o file.
if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
// If we have an asm name, then we use it as the mangling.
// If the label is an alias for an LLVM intrinsic,
// do not add a "\01" prefix.
if (ALA->getLabel().starts_with("llvm.")) {
Out << ALA->getLabel();
return;
}
// Adding the prefix can cause problems when one file has a "foo" and
// another has a "\01foo". That is known to happen on ELF with the
// tricks normally used for producing aliases (PR9177). Fortunately the
// llvm mangler on ELF is a nop, so we can just avoid adding the \01
// marker.
StringRef UserLabelPrefix =
getASTContext().getTargetInfo().getUserLabelPrefix();
#ifndef NDEBUG
char GlobalPrefix =
llvm::DataLayout(getASTContext().getTargetInfo().getDataLayoutString())
.getGlobalPrefix();
assert((UserLabelPrefix.empty() && !GlobalPrefix) ||
(UserLabelPrefix.size() == 1 && UserLabelPrefix[0] == GlobalPrefix));
#endif
if (!UserLabelPrefix.empty())
Out << '\01'; // LLVM IR Marker for __asm("foo")
Out << ALA->getLabel();
return;
}
if (auto *GD = dyn_cast<MSGuidDecl>(D))
return mangleMSGuidDecl(GD, Out);
CCMangling CC = getCallingConvMangling(ASTContext, D);
if (CC == CCM_WasmMainArgcArgv) {
Out << "__main_argc_argv";
return;
}
bool MCXX = shouldMangleCXXName(D);
const TargetInfo &TI = Context.getTargetInfo();
if (CC == CCM_Other || (MCXX && TI.getCXXABI() == TargetCXXABI::Microsoft)) {
if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))
mangleObjCMethodNameAsSourceName(OMD, Out);
else
mangleCXXName(GD, Out);
return;
}
Out << '\01';
if (CC == CCM_Std)
Out << '_';
else if (CC == CCM_Fast)
Out << '@';
else if (CC == CCM_RegCall) {
if (getASTContext().getLangOpts().RegCall4)
Out << "__regcall4__";
else
Out << "__regcall3__";
}
if (!MCXX)
Out << D->getIdentifier()->getName();
else if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))
mangleObjCMethodNameAsSourceName(OMD, Out);
else
mangleCXXName(GD, Out);
const FunctionDecl *FD = cast<FunctionDecl>(D);
const FunctionType *FT = FD->getType()->castAs<FunctionType>();
const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT);
if (CC == CCM_Vector)
Out << '@';
Out << '@';
if (!Proto) {
Out << '0';
return;
}
assert(!Proto->isVariadic());
unsigned ArgWords = 0;
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
if (MD->isImplicitObjectMemberFunction())
++ArgWords;
uint64_t DefaultPtrWidth = TI.getPointerWidth(LangAS::Default);
for (const auto &AT : Proto->param_types()) {
// If an argument type is incomplete there is no way to get its size to
// correctly encode into the mangling scheme.
// Follow GCCs behaviour by simply breaking out of the loop.
if (AT->isIncompleteType())
break;
// Size should be aligned to pointer size.
ArgWords += llvm::alignTo(ASTContext.getTypeSize(AT), DefaultPtrWidth) /
DefaultPtrWidth;
}
Out << ((DefaultPtrWidth / 8) * ArgWords);
}
void MangleContext::mangleMSGuidDecl(const MSGuidDecl *GD,
raw_ostream &Out) const {
// For now, follow the MSVC naming convention for GUID objects on all
// targets.
MSGuidDecl::Parts P = GD->getParts();
Out << llvm::format("_GUID_%08" PRIx32 "_%04" PRIx32 "_%04" PRIx32 "_",
P.Part1, P.Part2, P.Part3);
unsigned I = 0;
for (uint8_t C : P.Part4And5) {
Out << llvm::format("%02" PRIx8, C);
if (++I == 2)
Out << "_";
}
}
void MangleContext::mangleGlobalBlock(const BlockDecl *BD,
const NamedDecl *ID,
raw_ostream &Out) {
unsigned discriminator = getBlockId(BD, false);
if (ID) {
if (shouldMangleDeclName(ID))
mangleName(ID, Out);
else {
Out << ID->getIdentifier()->getName();
}
}
if (discriminator == 0)
Out << "_block_invoke";
else
Out << "_block_invoke_" << discriminator+1;
}
void MangleContext::mangleCtorBlock(const CXXConstructorDecl *CD,
CXXCtorType CT, const BlockDecl *BD,
raw_ostream &ResStream) {
SmallString<64> Buffer;
llvm::raw_svector_ostream Out(Buffer);
mangleName(GlobalDecl(CD, CT), Out);
mangleFunctionBlock(*this, Buffer, BD, ResStream);
}
void MangleContext::mangleDtorBlock(const CXXDestructorDecl *DD,
CXXDtorType DT, const BlockDecl *BD,
raw_ostream &ResStream) {
SmallString<64> Buffer;
llvm::raw_svector_ostream Out(Buffer);
mangleName(GlobalDecl(DD, DT), Out);
mangleFunctionBlock(*this, Buffer, BD, ResStream);
}
void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD,
raw_ostream &Out) {
assert(!isa<CXXConstructorDecl>(DC) && !isa<CXXDestructorDecl>(DC));
SmallString<64> Buffer;
llvm::raw_svector_ostream Stream(Buffer);
if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) {
mangleObjCMethodNameAsSourceName(Method, Stream);
} else {
assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) &&
"expected a NamedDecl or BlockDecl");
for (; isa_and_nonnull<BlockDecl>(DC); DC = DC->getParent())
(void)getBlockId(cast<BlockDecl>(DC), true);
assert((isa<TranslationUnitDecl>(DC) || isa<NamedDecl>(DC)) &&
"expected a TranslationUnitDecl or a NamedDecl");
if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC))
mangleCtorBlock(CD, /*CT*/ Ctor_Complete, BD, Out);
else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC))
mangleDtorBlock(DD, /*DT*/ Dtor_Complete, BD, Out);
else if (auto ND = dyn_cast<NamedDecl>(DC)) {
if (!shouldMangleDeclName(ND) && ND->getIdentifier())
Stream << ND->getIdentifier()->getName();
else {
// FIXME: We were doing a mangleUnqualifiedName() before, but that's
// a private member of a class that will soon itself be private to the
// Itanium C++ ABI object. What should we do now? Right now, I'm just
// calling the mangleName() method on the MangleContext; is there a
// better way?
mangleName(ND, Stream);
}
}
}
mangleFunctionBlock(*this, Buffer, BD, Out);
}
void MangleContext::mangleObjCMethodName(const ObjCMethodDecl *MD,
raw_ostream &OS,
bool includePrefixByte,
bool includeCategoryNamespace) const {
if (getASTContext().getLangOpts().ObjCRuntime.isGNUFamily()) {
// This is the mangling we've always used on the GNU runtimes, but it
// has obvious collisions in the face of underscores within class
// names, category names, and selectors; maybe we should improve it.
OS << (MD->isClassMethod() ? "_c_" : "_i_")
<< MD->getClassInterface()->getName() << '_';
if (includeCategoryNamespace) {
if (auto category = MD->getCategory())
OS << category->getName();
}
OS << '_';
auto selector = MD->getSelector();
for (unsigned slotIndex = 0,
numArgs = selector.getNumArgs(),
slotEnd = std::max(numArgs, 1U);
slotIndex != slotEnd; ++slotIndex) {
if (auto name = selector.getIdentifierInfoForSlot(slotIndex))
OS << name->getName();
// Replace all the positions that would've been ':' with '_'.
// That's after each slot except that a unary selector doesn't
// end in ':'.
if (numArgs)
OS << '_';
}
return;
}
// \01+[ContainerName(CategoryName) SelectorName]
auto CategoryName = std::optional<StringRef>();
StringRef ClassName = "";
if (const auto *CID = MD->getCategory()) {
if (const auto *CI = CID->getClassInterface()) {
ClassName = CI->getName();
if (includeCategoryNamespace) {
CategoryName = CID->getName();
}
}
} else if (const auto *CD =
dyn_cast<ObjCContainerDecl>(MD->getDeclContext())) {
ClassName = CD->getName();
} else {
llvm_unreachable("Unexpected ObjC method decl context");
}
std::string MethodName;
llvm::raw_string_ostream MethodNameOS(MethodName);
MD->getSelector().print(MethodNameOS);
clang::mangleObjCMethodName(OS, includePrefixByte, MD->isInstanceMethod(),
ClassName, CategoryName, MethodName);
}
void MangleContext::mangleObjCMethodNameAsSourceName(const ObjCMethodDecl *MD,
raw_ostream &Out) const {
SmallString<64> Name;
llvm::raw_svector_ostream OS(Name);
mangleObjCMethodName(MD, OS, /*includePrefixByte=*/false,
/*includeCategoryNamespace=*/true);
Out << OS.str().size() << OS.str();
}
class ASTNameGenerator::Implementation {
std::unique_ptr<MangleContext> MC;
llvm::DataLayout DL;
public:
explicit Implementation(ASTContext &Ctx)
: MC(Ctx.createMangleContext()),
DL(Ctx.getTargetInfo().getDataLayoutString()) {}
bool writeName(const Decl *D, raw_ostream &OS) {
// First apply frontend mangling.
SmallString<128> FrontendBuf;
llvm::raw_svector_ostream FrontendBufOS(FrontendBuf);
if (auto *FD = dyn_cast<FunctionDecl>(D)) {
if (FD->isDependentContext())
return true;
if (writeFuncOrVarName(FD, FrontendBufOS))
return true;
} else if (auto *VD = dyn_cast<VarDecl>(D)) {
if (writeFuncOrVarName(VD, FrontendBufOS))
return true;
} else if (auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
MC->mangleObjCMethodName(MD, OS, /*includePrefixByte=*/false,
/*includeCategoryNamespace=*/true);
return false;
} else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) {
writeObjCClassName(ID, FrontendBufOS);
} else {
return true;
}
// Now apply backend mangling.
llvm::Mangler::getNameWithPrefix(OS, FrontendBufOS.str(), DL);
return false;
}
std::string getName(const Decl *D) {
std::string Name;
{
llvm::raw_string_ostream OS(Name);
writeName(D, OS);
}
return Name;
}
enum ObjCKind {
ObjCClass,
ObjCMetaclass,
};
static StringRef getClassSymbolPrefix(ObjCKind Kind,
const ASTContext &Context) {
if (Context.getLangOpts().ObjCRuntime.isGNUFamily())
return Kind == ObjCMetaclass ? "_OBJC_METACLASS_" : "_OBJC_CLASS_";
return Kind == ObjCMetaclass ? "OBJC_METACLASS_$_" : "OBJC_CLASS_$_";
}
std::vector<std::string> getAllManglings(const ObjCContainerDecl *OCD) {
StringRef ClassName;
if (const auto *OID = dyn_cast<ObjCInterfaceDecl>(OCD))
ClassName = OID->getObjCRuntimeNameAsString();
else if (const auto *OID = dyn_cast<ObjCImplementationDecl>(OCD))
ClassName = OID->getObjCRuntimeNameAsString();
if (ClassName.empty())
return {};
auto Mangle = [&](ObjCKind Kind, StringRef ClassName) -> std::string {
SmallString<40> Mangled;
auto Prefix = getClassSymbolPrefix(Kind, OCD->getASTContext());
llvm::Mangler::getNameWithPrefix(Mangled, Prefix + ClassName, DL);
return std::string(Mangled);
};
return {
Mangle(ObjCClass, ClassName),
Mangle(ObjCMetaclass, ClassName),
};
}
std::vector<std::string> getAllManglings(const Decl *D) {
if (const auto *OCD = dyn_cast<ObjCContainerDecl>(D))
return getAllManglings(OCD);
if (!(isa<CXXRecordDecl>(D) || isa<CXXMethodDecl>(D)))
return {};
const NamedDecl *ND = cast<NamedDecl>(D);
ASTContext &Ctx = ND->getASTContext();
std::unique_ptr<MangleContext> M(Ctx.createMangleContext());
std::vector<std::string> Manglings;
auto hasDefaultCXXMethodCC = [](ASTContext &C, const CXXMethodDecl *MD) {
auto DefaultCC = C.getDefaultCallingConvention(/*IsVariadic=*/false,
/*IsCXXMethod=*/true);
auto CC = MD->getType()->castAs<FunctionProtoType>()->getCallConv();
return CC == DefaultCC;
};
if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) {
Manglings.emplace_back(getMangledStructor(CD, Ctor_Base));
if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily())
if (!CD->getParent()->isAbstract())
Manglings.emplace_back(getMangledStructor(CD, Ctor_Complete));
if (Ctx.getTargetInfo().getCXXABI().isMicrosoft())
if (CD->hasAttr<DLLExportAttr>() && CD->isDefaultConstructor())
if (!(hasDefaultCXXMethodCC(Ctx, CD) && CD->getNumParams() == 0))
Manglings.emplace_back(getMangledStructor(CD, Ctor_DefaultClosure));
} else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) {
Manglings.emplace_back(getMangledStructor(DD, Dtor_Base));
if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) {
Manglings.emplace_back(getMangledStructor(DD, Dtor_Complete));
if (DD->isVirtual())
Manglings.emplace_back(getMangledStructor(DD, Dtor_Deleting));
}
} else if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(ND)) {
Manglings.emplace_back(getName(ND));
if (MD->isVirtual()) {
if (const auto *TIV = Ctx.getVTableContext()->getThunkInfo(MD)) {
for (const auto &T : *TIV) {
std::string ThunkName;
std::string ContextualizedName =
getMangledThunk(MD, T, /* ElideOverrideInfo */ false);
if (Ctx.useAbbreviatedThunkName(MD, ContextualizedName))
ThunkName = getMangledThunk(MD, T, /* ElideOverrideInfo */ true);
else
ThunkName = ContextualizedName;
Manglings.emplace_back(ThunkName);
}
}
}
}
return Manglings;
}
private:
bool writeFuncOrVarName(const NamedDecl *D, raw_ostream &OS) {
if (MC->shouldMangleDeclName(D)) {
GlobalDecl GD;
if (const auto *CtorD = dyn_cast<CXXConstructorDecl>(D))
GD = GlobalDecl(CtorD, Ctor_Complete);
else if (const auto *DtorD = dyn_cast<CXXDestructorDecl>(D))
GD = GlobalDecl(DtorD, Dtor_Complete);
else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
GD = FD->isReferenceableKernel() ? GlobalDecl(FD) : GlobalDecl(D);
} else
GD = GlobalDecl(D);
MC->mangleName(GD, OS);
return false;
} else {
IdentifierInfo *II = D->getIdentifier();
if (!II)
return true;
OS << II->getName();
return false;
}
}
void writeObjCClassName(const ObjCInterfaceDecl *D, raw_ostream &OS) {
OS << getClassSymbolPrefix(ObjCClass, D->getASTContext());
OS << D->getObjCRuntimeNameAsString();
}
std::string getMangledStructor(const NamedDecl *ND, unsigned StructorType) {
std::string FrontendBuf;
llvm::raw_string_ostream FOS(FrontendBuf);
GlobalDecl GD;
if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND))
GD = GlobalDecl(CD, static_cast<CXXCtorType>(StructorType));
else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND))
GD = GlobalDecl(DD, static_cast<CXXDtorType>(StructorType));
MC->mangleName(GD, FOS);
std::string BackendBuf;
llvm::raw_string_ostream BOS(BackendBuf);
llvm::Mangler::getNameWithPrefix(BOS, FrontendBuf, DL);
return BackendBuf;
}
std::string getMangledThunk(const CXXMethodDecl *MD, const ThunkInfo &T,
bool ElideOverrideInfo) {
std::string FrontendBuf;
llvm::raw_string_ostream FOS(FrontendBuf);
MC->mangleThunk(MD, T, ElideOverrideInfo, FOS);
std::string BackendBuf;
llvm::raw_string_ostream BOS(BackendBuf);
llvm::Mangler::getNameWithPrefix(BOS, FrontendBuf, DL);
return BackendBuf;
}
};
ASTNameGenerator::ASTNameGenerator(ASTContext &Ctx)
: Impl(std::make_unique<Implementation>(Ctx)) {}
ASTNameGenerator::~ASTNameGenerator() {}
bool ASTNameGenerator::writeName(const Decl *D, raw_ostream &OS) {
return Impl->writeName(D, OS);
}
std::string ASTNameGenerator::getName(const Decl *D) {
return Impl->getName(D);
}
std::vector<std::string> ASTNameGenerator::getAllManglings(const Decl *D) {
return Impl->getAllManglings(D);
}