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//===------- ItaniumCXXABI.cpp - AST support for the Itanium C++ ABI ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This provides C++ AST support targeting the Itanium C++ ABI, which is
// documented at:
// http://www.codesourcery.com/public/cxx-abi/abi.html
// http://www.codesourcery.com/public/cxx-abi/abi-eh.html
//
// It also supports the closely-related ARM C++ ABI, documented at:
// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf
//
//===----------------------------------------------------------------------===//
#include "CXXABI.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/MangleNumberingContext.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/Type.h"
#include "clang/Basic/TargetInfo.h"
using namespace clang;
namespace {
/// According to Itanium C++ ABI 5.1.2:
/// the name of an anonymous union is considered to be
/// the name of the first named data member found by a pre-order,
/// depth-first, declaration-order walk of the data members of
/// the anonymous union.
/// If there is no such data member (i.e., if all of the data members
/// in the union are unnamed), then there is no way for a program to
/// refer to the anonymous union, and there is therefore no need to mangle its name.
///
/// Returns the name of anonymous union VarDecl or nullptr if it is not found.
static const IdentifierInfo *findAnonymousUnionVarDeclName(const VarDecl& VD) {
const RecordType *RT = VD.getType()->getAs<RecordType>();
assert(RT && "type of VarDecl is expected to be RecordType.");
assert(RT->getDecl()->isUnion() && "RecordType is expected to be a union.");
if (const FieldDecl *FD = RT->getDecl()->findFirstNamedDataMember()) {
return FD->getIdentifier();
}
return nullptr;
}
/// \brief Keeps track of the mangled names of lambda expressions and block
/// literals within a particular context.
class ItaniumNumberingContext : public MangleNumberingContext {
llvm::DenseMap<const Type *, unsigned> ManglingNumbers;
llvm::DenseMap<const IdentifierInfo *, unsigned> VarManglingNumbers;
llvm::DenseMap<const IdentifierInfo *, unsigned> TagManglingNumbers;
public:
unsigned getManglingNumber(const CXXMethodDecl *CallOperator) override {
const FunctionProtoType *Proto =
CallOperator->getType()->getAs<FunctionProtoType>();
ASTContext &Context = CallOperator->getASTContext();
FunctionProtoType::ExtProtoInfo EPI;
EPI.Variadic = Proto->isVariadic();
QualType Key =
Context.getFunctionType(Context.VoidTy, Proto->getParamTypes(), EPI);
Key = Context.getCanonicalType(Key);
return ++ManglingNumbers[Key->castAs<FunctionProtoType>()];
}
unsigned getManglingNumber(const BlockDecl *BD) override {
const Type *Ty = nullptr;
return ++ManglingNumbers[Ty];
}
unsigned getStaticLocalNumber(const VarDecl *VD) override {
return 0;
}
/// Variable decls are numbered by identifier.
unsigned getManglingNumber(const VarDecl *VD, unsigned) override {
const IdentifierInfo *Identifier = VD->getIdentifier();
if (!Identifier) {
// VarDecl without an identifier represents an anonymous union declaration.
Identifier = findAnonymousUnionVarDeclName(*VD);
}
return ++VarManglingNumbers[Identifier];
}
unsigned getManglingNumber(const TagDecl *TD, unsigned) override {
return ++TagManglingNumbers[TD->getIdentifier()];
}
};
class ItaniumCXXABI : public CXXABI {
protected:
ASTContext &Context;
public:
ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }
std::pair<uint64_t, unsigned>
getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const override {
const TargetInfo &Target = Context.getTargetInfo();
TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0);
uint64_t Width = Target.getTypeWidth(PtrDiff);
unsigned Align = Target.getTypeAlign(PtrDiff);
if (MPT->isMemberFunctionPointer())
Width = 2 * Width;
return std::make_pair(Width, Align);
}
CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
const llvm::Triple &T = Context.getTargetInfo().getTriple();
if (!isVariadic && T.isWindowsGNUEnvironment() &&
T.getArch() == llvm::Triple::x86)
return CC_X86ThisCall;
return CC_C;
}
// We cheat and just check that the class has a vtable pointer, and that it's
// only big enough to have a vtable pointer and nothing more (or less).
bool isNearlyEmpty(const CXXRecordDecl *RD) const override {
// Check that the class has a vtable pointer.
if (!RD->isDynamicClass())
return false;
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
CharUnits PointerSize =
Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
return Layout.getNonVirtualSize() == PointerSize;
}
const CXXConstructorDecl *
getCopyConstructorForExceptionObject(CXXRecordDecl *RD) override {
return nullptr;
}
void addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
CXXConstructorDecl *CD) override {}
void addTypedefNameForUnnamedTagDecl(TagDecl *TD,
TypedefNameDecl *DD) override {}
TypedefNameDecl *getTypedefNameForUnnamedTagDecl(const TagDecl *TD) override {
return nullptr;
}
void addDeclaratorForUnnamedTagDecl(TagDecl *TD,
DeclaratorDecl *DD) override {}
DeclaratorDecl *getDeclaratorForUnnamedTagDecl(const TagDecl *TD) override {
return nullptr;
}
std::unique_ptr<MangleNumberingContext>
createMangleNumberingContext() const override {
return llvm::make_unique<ItaniumNumberingContext>();
}
};
}
CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
return new ItaniumCXXABI(Ctx);
}
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