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llvm-project/clang/lib/CodeGen/CGVTables.cpp

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//===--- CGVTables.cpp - Emit LLVM Code for C++ vtables -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code dealing with C++ code generation of virtual tables.
//
//===----------------------------------------------------------------------===//
#include "CodeGenModule.h"
#include "CodeGenFunction.h"
#include "CGCXXABI.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/RecordLayout.h"
#include "clang/Frontend/CodeGenOptions.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Format.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include <algorithm>
#include <cstdio>
using namespace clang;
using namespace CodeGen;
namespace {
/// BaseOffset - Represents an offset from a derived class to a direct or
/// indirect base class.
struct BaseOffset {
/// DerivedClass - The derived class.
const CXXRecordDecl *DerivedClass;
/// VirtualBase - If the path from the derived class to the base class
/// involves a virtual base class, this holds its declaration.
const CXXRecordDecl *VirtualBase;
/// NonVirtualOffset - The offset from the derived class to the base class.
/// (Or the offset from the virtual base class to the base class, if the
/// path from the derived class to the base class involves a virtual base
/// class.
CharUnits NonVirtualOffset;
BaseOffset() : DerivedClass(0), VirtualBase(0),
NonVirtualOffset(CharUnits::Zero()) { }
BaseOffset(const CXXRecordDecl *DerivedClass,
const CXXRecordDecl *VirtualBase, CharUnits NonVirtualOffset)
: DerivedClass(DerivedClass), VirtualBase(VirtualBase),
NonVirtualOffset(NonVirtualOffset) { }
bool isEmpty() const { return NonVirtualOffset.isZero() && !VirtualBase; }
};
/// FinalOverriders - Contains the final overrider member functions for all
/// member functions in the base subobjects of a class.
class FinalOverriders {
public:
/// OverriderInfo - Information about a final overrider.
struct OverriderInfo {
/// Method - The method decl of the overrider.
const CXXMethodDecl *Method;
/// Offset - the base offset of the overrider in the layout class.
CharUnits Offset;
OverriderInfo() : Method(0), Offset(CharUnits::Zero()) { }
};
private:
/// MostDerivedClass - The most derived class for which the final overriders
/// are stored.
const CXXRecordDecl *MostDerivedClass;
/// MostDerivedClassOffset - If we're building final overriders for a
/// construction vtable, this holds the offset from the layout class to the
/// most derived class.
const CharUnits MostDerivedClassOffset;
/// LayoutClass - The class we're using for layout information. Will be
/// different than the most derived class if the final overriders are for a
/// construction vtable.
const CXXRecordDecl *LayoutClass;
ASTContext &Context;
/// MostDerivedClassLayout - the AST record layout of the most derived class.
const ASTRecordLayout &MostDerivedClassLayout;
/// MethodBaseOffsetPairTy - Uniquely identifies a member function
/// in a base subobject.
typedef std::pair<const CXXMethodDecl *, CharUnits> MethodBaseOffsetPairTy;
typedef llvm::DenseMap<MethodBaseOffsetPairTy,
OverriderInfo> OverridersMapTy;
/// OverridersMap - The final overriders for all virtual member functions of
/// all the base subobjects of the most derived class.
OverridersMapTy OverridersMap;
/// SubobjectsToOffsetsMapTy - A mapping from a base subobject (represented
/// as a record decl and a subobject number) and its offsets in the most
/// derived class as well as the layout class.
typedef llvm::DenseMap<std::pair<const CXXRecordDecl *, unsigned>,
CharUnits> SubobjectOffsetMapTy;
typedef llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCountMapTy;
/// ComputeBaseOffsets - Compute the offsets for all base subobjects of the
/// given base.
void ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
CharUnits OffsetInLayoutClass,
SubobjectOffsetMapTy &SubobjectOffsets,
SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
SubobjectCountMapTy &SubobjectCounts);
typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
/// dump - dump the final overriders for a base subobject, and all its direct
/// and indirect base subobjects.
void dump(llvm::raw_ostream &Out, BaseSubobject Base,
VisitedVirtualBasesSetTy& VisitedVirtualBases);
public:
FinalOverriders(const CXXRecordDecl *MostDerivedClass,
CharUnits MostDerivedClassOffset,
const CXXRecordDecl *LayoutClass);
/// getOverrider - Get the final overrider for the given method declaration in
/// the subobject with the given base offset.
OverriderInfo getOverrider(const CXXMethodDecl *MD,
CharUnits BaseOffset) const {
assert(OverridersMap.count(std::make_pair(MD, BaseOffset)) &&
"Did not find overrider!");
return OverridersMap.lookup(std::make_pair(MD, BaseOffset));
}
/// dump - dump the final overriders.
void dump() {
VisitedVirtualBasesSetTy VisitedVirtualBases;
dump(llvm::errs(), BaseSubobject(MostDerivedClass, CharUnits::Zero()),
VisitedVirtualBases);
}
};
#define DUMP_OVERRIDERS 0
FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass,
CharUnits MostDerivedClassOffset,
const CXXRecordDecl *LayoutClass)
: MostDerivedClass(MostDerivedClass),
MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass),
Context(MostDerivedClass->getASTContext()),
MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) {
// Compute base offsets.
SubobjectOffsetMapTy SubobjectOffsets;
SubobjectOffsetMapTy SubobjectLayoutClassOffsets;
SubobjectCountMapTy SubobjectCounts;
ComputeBaseOffsets(BaseSubobject(MostDerivedClass, CharUnits::Zero()),
/*IsVirtual=*/false,
MostDerivedClassOffset,
SubobjectOffsets, SubobjectLayoutClassOffsets,
SubobjectCounts);
// Get the the final overriders.
CXXFinalOverriderMap FinalOverriders;
MostDerivedClass->getFinalOverriders(FinalOverriders);
for (CXXFinalOverriderMap::const_iterator I = FinalOverriders.begin(),
E = FinalOverriders.end(); I != E; ++I) {
const CXXMethodDecl *MD = I->first;
const OverridingMethods& Methods = I->second;
for (OverridingMethods::const_iterator I = Methods.begin(),
E = Methods.end(); I != E; ++I) {
unsigned SubobjectNumber = I->first;
assert(SubobjectOffsets.count(std::make_pair(MD->getParent(),
SubobjectNumber)) &&
"Did not find subobject offset!");
CharUnits BaseOffset = SubobjectOffsets[std::make_pair(MD->getParent(),
SubobjectNumber)];
assert(I->second.size() == 1 && "Final overrider is not unique!");
const UniqueVirtualMethod &Method = I->second.front();
const CXXRecordDecl *OverriderRD = Method.Method->getParent();
assert(SubobjectLayoutClassOffsets.count(
std::make_pair(OverriderRD, Method.Subobject))
&& "Did not find subobject offset!");
CharUnits OverriderOffset =
SubobjectLayoutClassOffsets[std::make_pair(OverriderRD,
Method.Subobject)];
OverriderInfo& Overrider = OverridersMap[std::make_pair(MD, BaseOffset)];
assert(!Overrider.Method && "Overrider should not exist yet!");
Overrider.Offset = OverriderOffset;
Overrider.Method = Method.Method;
}
}
#if DUMP_OVERRIDERS
// And dump them (for now).
dump();
#endif
}
static BaseOffset ComputeBaseOffset(ASTContext &Context,
const CXXRecordDecl *DerivedRD,
const CXXBasePath &Path) {
CharUnits NonVirtualOffset = CharUnits::Zero();
unsigned NonVirtualStart = 0;
const CXXRecordDecl *VirtualBase = 0;
// First, look for the virtual base class.
for (unsigned I = 0, E = Path.size(); I != E; ++I) {
const CXXBasePathElement &Element = Path[I];
if (Element.Base->isVirtual()) {
// FIXME: Can we break when we find the first virtual base?
// (If we can't, can't we just iterate over the path in reverse order?)
NonVirtualStart = I + 1;
QualType VBaseType = Element.Base->getType();
VirtualBase =
cast<CXXRecordDecl>(VBaseType->getAs<RecordType>()->getDecl());
}
}
// Now compute the non-virtual offset.
for (unsigned I = NonVirtualStart, E = Path.size(); I != E; ++I) {
const CXXBasePathElement &Element = Path[I];
// Check the base class offset.
const ASTRecordLayout &Layout = Context.getASTRecordLayout(Element.Class);
const RecordType *BaseType = Element.Base->getType()->getAs<RecordType>();
const CXXRecordDecl *Base = cast<CXXRecordDecl>(BaseType->getDecl());
NonVirtualOffset += Layout.getBaseClassOffset(Base);
}
// FIXME: This should probably use CharUnits or something. Maybe we should
// even change the base offsets in ASTRecordLayout to be specified in
// CharUnits.
return BaseOffset(DerivedRD, VirtualBase, NonVirtualOffset);
}
static BaseOffset ComputeBaseOffset(ASTContext &Context,
const CXXRecordDecl *BaseRD,
const CXXRecordDecl *DerivedRD) {
CXXBasePaths Paths(/*FindAmbiguities=*/false,
/*RecordPaths=*/true, /*DetectVirtual=*/false);
if (!const_cast<CXXRecordDecl *>(DerivedRD)->
isDerivedFrom(const_cast<CXXRecordDecl *>(BaseRD), Paths)) {
assert(false && "Class must be derived from the passed in base class!");
return BaseOffset();
}
return ComputeBaseOffset(Context, DerivedRD, Paths.front());
}
static BaseOffset
ComputeReturnAdjustmentBaseOffset(ASTContext &Context,
const CXXMethodDecl *DerivedMD,
const CXXMethodDecl *BaseMD) {
const FunctionType *BaseFT = BaseMD->getType()->getAs<FunctionType>();
const FunctionType *DerivedFT = DerivedMD->getType()->getAs<FunctionType>();
// Canonicalize the return types.
CanQualType CanDerivedReturnType =
Context.getCanonicalType(DerivedFT->getResultType());
CanQualType CanBaseReturnType =
Context.getCanonicalType(BaseFT->getResultType());
assert(CanDerivedReturnType->getTypeClass() ==
CanBaseReturnType->getTypeClass() &&
"Types must have same type class!");
if (CanDerivedReturnType == CanBaseReturnType) {
// No adjustment needed.
return BaseOffset();
}
if (isa<ReferenceType>(CanDerivedReturnType)) {
CanDerivedReturnType =
CanDerivedReturnType->getAs<ReferenceType>()->getPointeeType();
CanBaseReturnType =
CanBaseReturnType->getAs<ReferenceType>()->getPointeeType();
} else if (isa<PointerType>(CanDerivedReturnType)) {
CanDerivedReturnType =
CanDerivedReturnType->getAs<PointerType>()->getPointeeType();
CanBaseReturnType =
CanBaseReturnType->getAs<PointerType>()->getPointeeType();
} else {
assert(false && "Unexpected return type!");
}
// We need to compare unqualified types here; consider
// const T *Base::foo();
// T *Derived::foo();
if (CanDerivedReturnType.getUnqualifiedType() ==
CanBaseReturnType.getUnqualifiedType()) {
// No adjustment needed.
return BaseOffset();
}
const CXXRecordDecl *DerivedRD =
cast<CXXRecordDecl>(cast<RecordType>(CanDerivedReturnType)->getDecl());
const CXXRecordDecl *BaseRD =
cast<CXXRecordDecl>(cast<RecordType>(CanBaseReturnType)->getDecl());
return ComputeBaseOffset(Context, BaseRD, DerivedRD);
}
void
FinalOverriders::ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
CharUnits OffsetInLayoutClass,
SubobjectOffsetMapTy &SubobjectOffsets,
SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
SubobjectCountMapTy &SubobjectCounts) {
const CXXRecordDecl *RD = Base.getBase();
unsigned SubobjectNumber = 0;
if (!IsVirtual)
SubobjectNumber = ++SubobjectCounts[RD];
// Set up the subobject to offset mapping.
assert(!SubobjectOffsets.count(std::make_pair(RD, SubobjectNumber))
&& "Subobject offset already exists!");
assert(!SubobjectLayoutClassOffsets.count(std::make_pair(RD, SubobjectNumber))
&& "Subobject offset already exists!");
SubobjectOffsets[std::make_pair(RD, SubobjectNumber)] = Base.getBaseOffset();
SubobjectLayoutClassOffsets[std::make_pair(RD, SubobjectNumber)] =
OffsetInLayoutClass;
// Traverse our bases.
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
CharUnits BaseOffset;
CharUnits BaseOffsetInLayoutClass;
if (I->isVirtual()) {
// Check if we've visited this virtual base before.
if (SubobjectOffsets.count(std::make_pair(BaseDecl, 0)))
continue;
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
BaseOffsetInLayoutClass =
LayoutClassLayout.getVBaseClassOffset(BaseDecl);
} else {
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
CharUnits Offset = Layout.getBaseClassOffset(BaseDecl);
BaseOffset = Base.getBaseOffset() + Offset;
BaseOffsetInLayoutClass = OffsetInLayoutClass + Offset;
}
ComputeBaseOffsets(BaseSubobject(BaseDecl, BaseOffset),
I->isVirtual(), BaseOffsetInLayoutClass,
SubobjectOffsets, SubobjectLayoutClassOffsets,
SubobjectCounts);
}
}
void FinalOverriders::dump(llvm::raw_ostream &Out, BaseSubobject Base,
VisitedVirtualBasesSetTy &VisitedVirtualBases) {
const CXXRecordDecl *RD = Base.getBase();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
// Ignore bases that don't have any virtual member functions.
if (!BaseDecl->isPolymorphic())
continue;
CharUnits BaseOffset;
if (I->isVirtual()) {
if (!VisitedVirtualBases.insert(BaseDecl)) {
// We've visited this base before.
continue;
}
BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
} else {
BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset();
}
dump(Out, BaseSubobject(BaseDecl, BaseOffset), VisitedVirtualBases);
}
Out << "Final overriders for (" << RD->getQualifiedNameAsString() << ", ";
Out << Base.getBaseOffset().getQuantity() << ")\n";
// Now dump the overriders for this base subobject.
for (CXXRecordDecl::method_iterator I = RD->method_begin(),
E = RD->method_end(); I != E; ++I) {
const CXXMethodDecl *MD = *I;
if (!MD->isVirtual())
continue;
OverriderInfo Overrider = getOverrider(MD, Base.getBaseOffset());
Out << " " << MD->getQualifiedNameAsString() << " - (";
Out << Overrider.Method->getQualifiedNameAsString();
Out << ", " << ", " << Overrider.Offset.getQuantity() << ')';
BaseOffset Offset;
if (!Overrider.Method->isPure())
Offset = ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
if (!Offset.isEmpty()) {
Out << " [ret-adj: ";
if (Offset.VirtualBase)
Out << Offset.VirtualBase->getQualifiedNameAsString() << " vbase, ";
Out << Offset.NonVirtualOffset.getQuantity() << " nv]";
}
Out << "\n";
}
}
/// VTableComponent - Represents a single component in a vtable.
class VTableComponent {
public:
enum Kind {
CK_VCallOffset,
CK_VBaseOffset,
CK_OffsetToTop,
CK_RTTI,
CK_FunctionPointer,
/// CK_CompleteDtorPointer - A pointer to the complete destructor.
CK_CompleteDtorPointer,
/// CK_DeletingDtorPointer - A pointer to the deleting destructor.
CK_DeletingDtorPointer,
/// CK_UnusedFunctionPointer - In some cases, a vtable function pointer
/// will end up never being called. Such vtable function pointers are
/// represented as a CK_UnusedFunctionPointer.
CK_UnusedFunctionPointer
};
static VTableComponent MakeVCallOffset(CharUnits Offset) {
return VTableComponent(CK_VCallOffset, Offset);
}
static VTableComponent MakeVBaseOffset(CharUnits Offset) {
return VTableComponent(CK_VBaseOffset, Offset);
}
static VTableComponent MakeOffsetToTop(CharUnits Offset) {
return VTableComponent(CK_OffsetToTop, Offset);
}
static VTableComponent MakeRTTI(const CXXRecordDecl *RD) {
return VTableComponent(CK_RTTI, reinterpret_cast<uintptr_t>(RD));
}
static VTableComponent MakeFunction(const CXXMethodDecl *MD) {
assert(!isa<CXXDestructorDecl>(MD) &&
"Don't use MakeFunction with destructors!");
return VTableComponent(CK_FunctionPointer,
reinterpret_cast<uintptr_t>(MD));
}
static VTableComponent MakeCompleteDtor(const CXXDestructorDecl *DD) {
return VTableComponent(CK_CompleteDtorPointer,
reinterpret_cast<uintptr_t>(DD));
}
static VTableComponent MakeDeletingDtor(const CXXDestructorDecl *DD) {
return VTableComponent(CK_DeletingDtorPointer,
reinterpret_cast<uintptr_t>(DD));
}
static VTableComponent MakeUnusedFunction(const CXXMethodDecl *MD) {
assert(!isa<CXXDestructorDecl>(MD) &&
"Don't use MakeUnusedFunction with destructors!");
return VTableComponent(CK_UnusedFunctionPointer,
reinterpret_cast<uintptr_t>(MD));
}
static VTableComponent getFromOpaqueInteger(uint64_t I) {
return VTableComponent(I);
}
/// getKind - Get the kind of this vtable component.
Kind getKind() const {
return (Kind)(Value & 0x7);
}
CharUnits getVCallOffset() const {
assert(getKind() == CK_VCallOffset && "Invalid component kind!");
return getOffset();
}
CharUnits getVBaseOffset() const {
assert(getKind() == CK_VBaseOffset && "Invalid component kind!");
return getOffset();
}
CharUnits getOffsetToTop() const {
assert(getKind() == CK_OffsetToTop && "Invalid component kind!");
return getOffset();
}
const CXXRecordDecl *getRTTIDecl() const {
assert(getKind() == CK_RTTI && "Invalid component kind!");
return reinterpret_cast<CXXRecordDecl *>(getPointer());
}
const CXXMethodDecl *getFunctionDecl() const {
assert(getKind() == CK_FunctionPointer);
return reinterpret_cast<CXXMethodDecl *>(getPointer());
}
const CXXDestructorDecl *getDestructorDecl() const {
assert((getKind() == CK_CompleteDtorPointer ||
getKind() == CK_DeletingDtorPointer) && "Invalid component kind!");
return reinterpret_cast<CXXDestructorDecl *>(getPointer());
}
const CXXMethodDecl *getUnusedFunctionDecl() const {
assert(getKind() == CK_UnusedFunctionPointer);
return reinterpret_cast<CXXMethodDecl *>(getPointer());
}
private:
VTableComponent(Kind ComponentKind, CharUnits Offset) {
assert((ComponentKind == CK_VCallOffset ||
ComponentKind == CK_VBaseOffset ||
ComponentKind == CK_OffsetToTop) && "Invalid component kind!");
assert(Offset.getQuantity() <= ((1LL << 56) - 1) && "Offset is too big!");
Value = ((Offset.getQuantity() << 3) | ComponentKind);
}
VTableComponent(Kind ComponentKind, uintptr_t Ptr) {
assert((ComponentKind == CK_RTTI ||
ComponentKind == CK_FunctionPointer ||
ComponentKind == CK_CompleteDtorPointer ||
ComponentKind == CK_DeletingDtorPointer ||
ComponentKind == CK_UnusedFunctionPointer) &&
"Invalid component kind!");
assert((Ptr & 7) == 0 && "Pointer not sufficiently aligned!");
Value = Ptr | ComponentKind;
}
CharUnits getOffset() const {
assert((getKind() == CK_VCallOffset || getKind() == CK_VBaseOffset ||
getKind() == CK_OffsetToTop) && "Invalid component kind!");
return CharUnits::fromQuantity(Value >> 3);
}
uintptr_t getPointer() const {
assert((getKind() == CK_RTTI ||
getKind() == CK_FunctionPointer ||
getKind() == CK_CompleteDtorPointer ||
getKind() == CK_DeletingDtorPointer ||
getKind() == CK_UnusedFunctionPointer) &&
"Invalid component kind!");
return static_cast<uintptr_t>(Value & ~7ULL);
}
explicit VTableComponent(uint64_t Value)
: Value(Value) { }
/// The kind is stored in the lower 3 bits of the value. For offsets, we
/// make use of the facts that classes can't be larger than 2^55 bytes,
/// so we store the offset in the lower part of the 61 bytes that remain.
/// (The reason that we're not simply using a PointerIntPair here is that we
/// need the offsets to be 64-bit, even when on a 32-bit machine).
int64_t Value;
};
/// VCallOffsetMap - Keeps track of vcall offsets when building a vtable.
struct VCallOffsetMap {
typedef std::pair<const CXXMethodDecl *, CharUnits> MethodAndOffsetPairTy;
/// Offsets - Keeps track of methods and their offsets.
// FIXME: This should be a real map and not a vector.
llvm::SmallVector<MethodAndOffsetPairTy, 16> Offsets;
/// MethodsCanShareVCallOffset - Returns whether two virtual member functions
/// can share the same vcall offset.
static bool MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
const CXXMethodDecl *RHS);
public:
/// AddVCallOffset - Adds a vcall offset to the map. Returns true if the
/// add was successful, or false if there was already a member function with
/// the same signature in the map.
bool AddVCallOffset(const CXXMethodDecl *MD, CharUnits OffsetOffset);
/// getVCallOffsetOffset - Returns the vcall offset offset (relative to the
/// vtable address point) for the given virtual member function.
CharUnits getVCallOffsetOffset(const CXXMethodDecl *MD);
// empty - Return whether the offset map is empty or not.
bool empty() const { return Offsets.empty(); }
};
static bool HasSameVirtualSignature(const CXXMethodDecl *LHS,
const CXXMethodDecl *RHS) {
ASTContext &C = LHS->getASTContext(); // TODO: thread this down
CanQual<FunctionProtoType>
LT = C.getCanonicalType(LHS->getType()).getAs<FunctionProtoType>(),
RT = C.getCanonicalType(RHS->getType()).getAs<FunctionProtoType>();
// Fast-path matches in the canonical types.
if (LT == RT) return true;
// Force the signatures to match. We can't rely on the overrides
// list here because there isn't necessarily an inheritance
// relationship between the two methods.
if (LT.getQualifiers() != RT.getQualifiers() ||
LT->getNumArgs() != RT->getNumArgs())
return false;
for (unsigned I = 0, E = LT->getNumArgs(); I != E; ++I)
if (LT->getArgType(I) != RT->getArgType(I))
return false;
return true;
}
bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
const CXXMethodDecl *RHS) {
assert(LHS->isVirtual() && "LHS must be virtual!");
assert(RHS->isVirtual() && "LHS must be virtual!");
// A destructor can share a vcall offset with another destructor.
if (isa<CXXDestructorDecl>(LHS))
return isa<CXXDestructorDecl>(RHS);
// FIXME: We need to check more things here.
// The methods must have the same name.
DeclarationName LHSName = LHS->getDeclName();
DeclarationName RHSName = RHS->getDeclName();
if (LHSName != RHSName)
return false;
// And the same signatures.
return HasSameVirtualSignature(LHS, RHS);
}
bool VCallOffsetMap::AddVCallOffset(const CXXMethodDecl *MD,
CharUnits OffsetOffset) {
// Check if we can reuse an offset.
for (unsigned I = 0, E = Offsets.size(); I != E; ++I) {
if (MethodsCanShareVCallOffset(Offsets[I].first, MD))
return false;
}
// Add the offset.
Offsets.push_back(MethodAndOffsetPairTy(MD, OffsetOffset));
return true;
}
CharUnits VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) {
// Look for an offset.
for (unsigned I = 0, E = Offsets.size(); I != E; ++I) {
if (MethodsCanShareVCallOffset(Offsets[I].first, MD))
return Offsets[I].second;
}
assert(false && "Should always find a vcall offset offset!");
return CharUnits::Zero();
}
/// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets.
class VCallAndVBaseOffsetBuilder {
public:
typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
VBaseOffsetOffsetsMapTy;
private:
/// MostDerivedClass - The most derived class for which we're building vcall
/// and vbase offsets.
const CXXRecordDecl *MostDerivedClass;
/// LayoutClass - The class we're using for layout information. Will be
/// different than the most derived class if we're building a construction
/// vtable.
const CXXRecordDecl *LayoutClass;
/// Context - The ASTContext which we will use for layout information.
ASTContext &Context;
/// Components - vcall and vbase offset components
typedef llvm::SmallVector<VTableComponent, 64> VTableComponentVectorTy;
VTableComponentVectorTy Components;
/// VisitedVirtualBases - Visited virtual bases.
llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
/// VCallOffsets - Keeps track of vcall offsets.
VCallOffsetMap VCallOffsets;
/// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets,
/// relative to the address point.
VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
/// FinalOverriders - The final overriders of the most derived class.
/// (Can be null when we're not building a vtable of the most derived class).
const FinalOverriders *Overriders;
/// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the
/// given base subobject.
void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual,
CharUnits RealBaseOffset);
/// AddVCallOffsets - Add vcall offsets for the given base subobject.
void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset);
/// AddVBaseOffsets - Add vbase offsets for the given class.
void AddVBaseOffsets(const CXXRecordDecl *Base,
CharUnits OffsetInLayoutClass);
/// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in
/// chars, relative to the vtable address point.
CharUnits getCurrentOffsetOffset() const;
public:
VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass,
const CXXRecordDecl *LayoutClass,
const FinalOverriders *Overriders,
BaseSubobject Base, bool BaseIsVirtual,
CharUnits OffsetInLayoutClass)
: MostDerivedClass(MostDerivedClass), LayoutClass(LayoutClass),
Context(MostDerivedClass->getASTContext()), Overriders(Overriders) {
// Add vcall and vbase offsets.
AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass);
}
/// Methods for iterating over the components.
typedef VTableComponentVectorTy::const_reverse_iterator const_iterator;
const_iterator components_begin() const { return Components.rbegin(); }
const_iterator components_end() const { return Components.rend(); }
const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; }
const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
return VBaseOffsetOffsets;
}
};
void
VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base,
bool BaseIsVirtual,
CharUnits RealBaseOffset) {
const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase());
// Itanium C++ ABI 2.5.2:
// ..in classes sharing a virtual table with a primary base class, the vcall
// and vbase offsets added by the derived class all come before the vcall
// and vbase offsets required by the base class, so that the latter may be
// laid out as required by the base class without regard to additions from
// the derived class(es).
// (Since we're emitting the vcall and vbase offsets in reverse order, we'll
// emit them for the primary base first).
if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
CharUnits PrimaryBaseOffset;
// Get the base offset of the primary base.
if (PrimaryBaseIsVirtual) {
assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 &&
"Primary vbase should have a zero offset!");
const ASTRecordLayout &MostDerivedClassLayout =
Context.getASTRecordLayout(MostDerivedClass);
PrimaryBaseOffset =
MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
} else {
assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 &&
"Primary base should have a zero offset!");
PrimaryBaseOffset = Base.getBaseOffset();
}
AddVCallAndVBaseOffsets(
BaseSubobject(PrimaryBase,PrimaryBaseOffset),
PrimaryBaseIsVirtual, RealBaseOffset);
}
AddVBaseOffsets(Base.getBase(), RealBaseOffset);
// We only want to add vcall offsets for virtual bases.
if (BaseIsVirtual)
AddVCallOffsets(Base, RealBaseOffset);
}
CharUnits VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const {
// OffsetIndex is the index of this vcall or vbase offset, relative to the
// vtable address point. (We subtract 3 to account for the information just
// above the address point, the RTTI info, the offset to top, and the
// vcall offset itself).
int64_t OffsetIndex = -(int64_t)(3 + Components.size());
CharUnits PointerWidth =
Context.toCharUnitsFromBits(Context.Target.getPointerWidth(0));
CharUnits OffsetOffset = PointerWidth * OffsetIndex;
return OffsetOffset;
}
void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base,
CharUnits VBaseOffset) {
const CXXRecordDecl *RD = Base.getBase();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
// Handle the primary base first.
// We only want to add vcall offsets if the base is non-virtual; a virtual
// primary base will have its vcall and vbase offsets emitted already.
if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) {
// Get the base offset of the primary base.
assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 &&
"Primary base should have a zero offset!");
AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()),
VBaseOffset);
}
// Add the vcall offsets.
for (CXXRecordDecl::method_iterator I = RD->method_begin(),
E = RD->method_end(); I != E; ++I) {
const CXXMethodDecl *MD = *I;
if (!MD->isVirtual())
continue;
CharUnits OffsetOffset = getCurrentOffsetOffset();
// Don't add a vcall offset if we already have one for this member function
// signature.
if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset))
continue;
CharUnits Offset = CharUnits::Zero();
if (Overriders) {
// Get the final overrider.
FinalOverriders::OverriderInfo Overrider =
Overriders->getOverrider(MD, Base.getBaseOffset());
/// The vcall offset is the offset from the virtual base to the object
/// where the function was overridden.
Offset = Overrider.Offset - VBaseOffset;
}
Components.push_back(
VTableComponent::MakeVCallOffset(Offset));
}
// And iterate over all non-virtual bases (ignoring the primary base).
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
if (I->isVirtual())
continue;
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
if (BaseDecl == PrimaryBase)
continue;
// Get the base offset of this base.
CharUnits BaseOffset = Base.getBaseOffset() +
Layout.getBaseClassOffset(BaseDecl);
AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset),
VBaseOffset);
}
}
void
VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
CharUnits OffsetInLayoutClass) {
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
// Add vbase offsets.
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
// Check if this is a virtual base that we haven't visited before.
if (I->isVirtual() && VisitedVirtualBases.insert(BaseDecl)) {
CharUnits Offset =
LayoutClassLayout.getVBaseClassOffset(BaseDecl) - OffsetInLayoutClass;
// Add the vbase offset offset.
assert(!VBaseOffsetOffsets.count(BaseDecl) &&
"vbase offset offset already exists!");
CharUnits VBaseOffsetOffset = getCurrentOffsetOffset();
VBaseOffsetOffsets.insert(
std::make_pair(BaseDecl, VBaseOffsetOffset));
Components.push_back(
VTableComponent::MakeVBaseOffset(Offset));
}
// Check the base class looking for more vbase offsets.
AddVBaseOffsets(BaseDecl, OffsetInLayoutClass);
}
}
/// VTableBuilder - Class for building vtable layout information.
class VTableBuilder {
public:
/// PrimaryBasesSetVectorTy - A set vector of direct and indirect
/// primary bases.
typedef llvm::SmallSetVector<const CXXRecordDecl *, 8>
PrimaryBasesSetVectorTy;
typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
VBaseOffsetOffsetsMapTy;
typedef llvm::DenseMap<BaseSubobject, uint64_t>
AddressPointsMapTy;
private:
/// VTables - Global vtable information.
CodeGenVTables &VTables;
/// MostDerivedClass - The most derived class for which we're building this
/// vtable.
const CXXRecordDecl *MostDerivedClass;
/// MostDerivedClassOffset - If we're building a construction vtable, this
/// holds the offset from the layout class to the most derived class.
const CharUnits MostDerivedClassOffset;
/// MostDerivedClassIsVirtual - Whether the most derived class is a virtual
/// base. (This only makes sense when building a construction vtable).
bool MostDerivedClassIsVirtual;
/// LayoutClass - The class we're using for layout information. Will be
/// different than the most derived class if we're building a construction
/// vtable.
const CXXRecordDecl *LayoutClass;
/// Context - The ASTContext which we will use for layout information.
ASTContext &Context;
/// FinalOverriders - The final overriders of the most derived class.
const FinalOverriders Overriders;
/// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual
/// bases in this vtable.
llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases;
/// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for
/// the most derived class.
VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
/// Components - The components of the vtable being built.
llvm::SmallVector<VTableComponent, 64> Components;
/// AddressPoints - Address points for the vtable being built.
AddressPointsMapTy AddressPoints;
/// MethodInfo - Contains information about a method in a vtable.
/// (Used for computing 'this' pointer adjustment thunks.
struct MethodInfo {
/// BaseOffset - The base offset of this method.
const CharUnits BaseOffset;
/// BaseOffsetInLayoutClass - The base offset in the layout class of this
/// method.
const CharUnits BaseOffsetInLayoutClass;
/// VTableIndex - The index in the vtable that this method has.
/// (For destructors, this is the index of the complete destructor).
const uint64_t VTableIndex;
MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass,
uint64_t VTableIndex)
: BaseOffset(BaseOffset),
BaseOffsetInLayoutClass(BaseOffsetInLayoutClass),
VTableIndex(VTableIndex) { }
MethodInfo()
: BaseOffset(CharUnits::Zero()),
BaseOffsetInLayoutClass(CharUnits::Zero()),
VTableIndex(0) { }
};
typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
/// MethodInfoMap - The information for all methods in the vtable we're
/// currently building.
MethodInfoMapTy MethodInfoMap;
typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
/// VTableThunks - The thunks by vtable index in the vtable currently being
/// built.
VTableThunksMapTy VTableThunks;
typedef llvm::SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
/// Thunks - A map that contains all the thunks needed for all methods in the
/// most derived class for which the vtable is currently being built.
ThunksMapTy Thunks;
/// AddThunk - Add a thunk for the given method.
void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk);
/// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the
/// part of the vtable we're currently building.
void ComputeThisAdjustments();
typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
/// PrimaryVirtualBases - All known virtual bases who are a primary base of
/// some other base.
VisitedVirtualBasesSetTy PrimaryVirtualBases;
/// ComputeReturnAdjustment - Compute the return adjustment given a return
/// adjustment base offset.
ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset);
/// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting
/// the 'this' pointer from the base subobject to the derived subobject.
BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base,
BaseSubobject Derived) const;
/// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the
/// given virtual member function, its offset in the layout class and its
/// final overrider.
ThisAdjustment
ComputeThisAdjustment(const CXXMethodDecl *MD,
CharUnits BaseOffsetInLayoutClass,
FinalOverriders::OverriderInfo Overrider);
/// AddMethod - Add a single virtual member function to the vtable
/// components vector.
void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment);
/// IsOverriderUsed - Returns whether the overrider will ever be used in this
/// part of the vtable.
///
/// Itanium C++ ABI 2.5.2:
///
/// struct A { virtual void f(); };
/// struct B : virtual public A { int i; };
/// struct C : virtual public A { int j; };
/// struct D : public B, public C {};
///
/// When B and C are declared, A is a primary base in each case, so although
/// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this
/// adjustment is required and no thunk is generated. However, inside D
/// objects, A is no longer a primary base of C, so if we allowed calls to
/// C::f() to use the copy of A's vtable in the C subobject, we would need
/// to adjust this from C* to B::A*, which would require a third-party
/// thunk. Since we require that a call to C::f() first convert to A*,
/// C-in-D's copy of A's vtable is never referenced, so this is not
/// necessary.
bool IsOverriderUsed(const CXXMethodDecl *Overrider,
CharUnits BaseOffsetInLayoutClass,
const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
CharUnits FirstBaseOffsetInLayoutClass) const;
/// AddMethods - Add the methods of this base subobject and all its
/// primary bases to the vtable components vector.
void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
CharUnits FirstBaseOffsetInLayoutClass,
PrimaryBasesSetVectorTy &PrimaryBases);
// LayoutVTable - Layout the vtable for the given base class, including its
// secondary vtables and any vtables for virtual bases.
void LayoutVTable();
/// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the
/// given base subobject, as well as all its secondary vtables.
///
/// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
/// or a direct or indirect base of a virtual base.
///
/// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual
/// in the layout class.
void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base,
bool BaseIsMorallyVirtual,
bool BaseIsVirtualInLayoutClass,
CharUnits OffsetInLayoutClass);
/// LayoutSecondaryVTables - Layout the secondary vtables for the given base
/// subobject.
///
/// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
/// or a direct or indirect base of a virtual base.
void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual,
CharUnits OffsetInLayoutClass);
/// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this
/// class hierarchy.
void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
CharUnits OffsetInLayoutClass,
VisitedVirtualBasesSetTy &VBases);
/// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the
/// given base (excluding any primary bases).
void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
VisitedVirtualBasesSetTy &VBases);
/// isBuildingConstructionVTable - Return whether this vtable builder is
/// building a construction vtable.
bool isBuildingConstructorVTable() const {
return MostDerivedClass != LayoutClass;
}
public:
VTableBuilder(CodeGenVTables &VTables, const CXXRecordDecl *MostDerivedClass,
CharUnits MostDerivedClassOffset,
bool MostDerivedClassIsVirtual, const
CXXRecordDecl *LayoutClass)
: VTables(VTables), MostDerivedClass(MostDerivedClass),
MostDerivedClassOffset(MostDerivedClassOffset),
MostDerivedClassIsVirtual(MostDerivedClassIsVirtual),
LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) {
LayoutVTable();
}
ThunksMapTy::const_iterator thunks_begin() const {
return Thunks.begin();
}
ThunksMapTy::const_iterator thunks_end() const {
return Thunks.end();
}
const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
return VBaseOffsetOffsets;
}
/// getNumVTableComponents - Return the number of components in the vtable
/// currently built.
uint64_t getNumVTableComponents() const {
return Components.size();
}
const uint64_t *vtable_components_data_begin() const {
return reinterpret_cast<const uint64_t *>(Components.begin());
}
const uint64_t *vtable_components_data_end() const {
return reinterpret_cast<const uint64_t *>(Components.end());
}
AddressPointsMapTy::const_iterator address_points_begin() const {
return AddressPoints.begin();
}
AddressPointsMapTy::const_iterator address_points_end() const {
return AddressPoints.end();
}
VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
return VTableThunks.begin();
}
VTableThunksMapTy::const_iterator vtable_thunks_end() const {
return VTableThunks.end();
}
/// dumpLayout - Dump the vtable layout.
void dumpLayout(llvm::raw_ostream&);
};
void VTableBuilder::AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) {
assert(!isBuildingConstructorVTable() &&
"Can't add thunks for construction vtable");
llvm::SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD];
// Check if we have this thunk already.
if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) !=
ThunksVector.end())
return;
ThunksVector.push_back(Thunk);
}
typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy;
/// ComputeAllOverriddenMethods - Given a method decl, will return a set of all
/// the overridden methods that the function decl overrides.
static void
ComputeAllOverriddenMethods(const CXXMethodDecl *MD,
OverriddenMethodsSetTy& OverriddenMethods) {
assert(MD->isVirtual() && "Method is not virtual!");
for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(),
E = MD->end_overridden_methods(); I != E; ++I) {
const CXXMethodDecl *OverriddenMD = *I;
OverriddenMethods.insert(OverriddenMD);
ComputeAllOverriddenMethods(OverriddenMD, OverriddenMethods);
}
}
void VTableBuilder::ComputeThisAdjustments() {
// Now go through the method info map and see if any of the methods need
// 'this' pointer adjustments.
for (MethodInfoMapTy::const_iterator I = MethodInfoMap.begin(),
E = MethodInfoMap.end(); I != E; ++I) {
const CXXMethodDecl *MD = I->first;
const MethodInfo &MethodInfo = I->second;
// Ignore adjustments for unused function pointers.
uint64_t VTableIndex = MethodInfo.VTableIndex;
if (Components[VTableIndex].getKind() ==
VTableComponent::CK_UnusedFunctionPointer)
continue;
// Get the final overrider for this method.
FinalOverriders::OverriderInfo Overrider =
Overriders.getOverrider(MD, MethodInfo.BaseOffset);
// Check if we need an adjustment at all.
if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) {
// When a return thunk is needed by a derived class that overrides a
// virtual base, gcc uses a virtual 'this' adjustment as well.
// While the thunk itself might be needed by vtables in subclasses or
// in construction vtables, there doesn't seem to be a reason for using
// the thunk in this vtable. Still, we do so to match gcc.
if (VTableThunks.lookup(VTableIndex).Return.isEmpty())
continue;
}
ThisAdjustment ThisAdjustment =
ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider);
if (ThisAdjustment.isEmpty())
continue;
// Add it.
VTableThunks[VTableIndex].This = ThisAdjustment;
if (isa<CXXDestructorDecl>(MD)) {
// Add an adjustment for the deleting destructor as well.
VTableThunks[VTableIndex + 1].This = ThisAdjustment;
}
}
/// Clear the method info map.
MethodInfoMap.clear();
if (isBuildingConstructorVTable()) {
// We don't need to store thunk information for construction vtables.
return;
}
for (VTableThunksMapTy::const_iterator I = VTableThunks.begin(),
E = VTableThunks.end(); I != E; ++I) {
const VTableComponent &Component = Components[I->first];
const ThunkInfo &Thunk = I->second;
const CXXMethodDecl *MD;
switch (Component.getKind()) {
default:
llvm_unreachable("Unexpected vtable component kind!");
case VTableComponent::CK_FunctionPointer:
MD = Component.getFunctionDecl();
break;
case VTableComponent::CK_CompleteDtorPointer:
MD = Component.getDestructorDecl();
break;
case VTableComponent::CK_DeletingDtorPointer:
// We've already added the thunk when we saw the complete dtor pointer.
continue;
}
if (MD->getParent() == MostDerivedClass)
AddThunk(MD, Thunk);
}
}
ReturnAdjustment VTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) {
ReturnAdjustment Adjustment;
if (!Offset.isEmpty()) {
if (Offset.VirtualBase) {
// Get the virtual base offset offset.
if (Offset.DerivedClass == MostDerivedClass) {
// We can get the offset offset directly from our map.
Adjustment.VBaseOffsetOffset =
VBaseOffsetOffsets.lookup(Offset.VirtualBase).getQuantity();
} else {
Adjustment.VBaseOffsetOffset =
VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass,
Offset.VirtualBase).getQuantity();
}
}
Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
}
return Adjustment;
}
BaseOffset
VTableBuilder::ComputeThisAdjustmentBaseOffset(BaseSubobject Base,
BaseSubobject Derived) const {
const CXXRecordDecl *BaseRD = Base.getBase();
const CXXRecordDecl *DerivedRD = Derived.getBase();
CXXBasePaths Paths(/*FindAmbiguities=*/true,
/*RecordPaths=*/true, /*DetectVirtual=*/true);
if (!const_cast<CXXRecordDecl *>(DerivedRD)->
isDerivedFrom(const_cast<CXXRecordDecl *>(BaseRD), Paths)) {
assert(false && "Class must be derived from the passed in base class!");
return BaseOffset();
}
// We have to go through all the paths, and see which one leads us to the
// right base subobject.
for (CXXBasePaths::const_paths_iterator I = Paths.begin(), E = Paths.end();
I != E; ++I) {
BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, *I);
CharUnits OffsetToBaseSubobject = Offset.NonVirtualOffset;
if (Offset.VirtualBase) {
// If we have a virtual base class, the non-virtual offset is relative
// to the virtual base class offset.
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
/// Get the virtual base offset, relative to the most derived class
/// layout.
OffsetToBaseSubobject +=
LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase);
} else {
// Otherwise, the non-virtual offset is relative to the derived class
// offset.
OffsetToBaseSubobject += Derived.getBaseOffset();
}
// Check if this path gives us the right base subobject.
if (OffsetToBaseSubobject == Base.getBaseOffset()) {
// Since we're going from the base class _to_ the derived class, we'll
// invert the non-virtual offset here.
Offset.NonVirtualOffset = -Offset.NonVirtualOffset;
return Offset;
}
}
return BaseOffset();
}
ThisAdjustment
VTableBuilder::ComputeThisAdjustment(const CXXMethodDecl *MD,
CharUnits BaseOffsetInLayoutClass,
FinalOverriders::OverriderInfo Overrider) {
// Ignore adjustments for pure virtual member functions.
if (Overrider.Method->isPure())
return ThisAdjustment();
BaseSubobject OverriddenBaseSubobject(MD->getParent(),
BaseOffsetInLayoutClass);
BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(),
Overrider.Offset);
// Compute the adjustment offset.
BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject,
OverriderBaseSubobject);
if (Offset.isEmpty())
return ThisAdjustment();
ThisAdjustment Adjustment;
if (Offset.VirtualBase) {
// Get the vcall offset map for this virtual base.
VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase];
if (VCallOffsets.empty()) {
// We don't have vcall offsets for this virtual base, go ahead and
// build them.
VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, MostDerivedClass,
/*FinalOverriders=*/0,
BaseSubobject(Offset.VirtualBase,
CharUnits::Zero()),
/*BaseIsVirtual=*/true,
/*OffsetInLayoutClass=*/
CharUnits::Zero());
VCallOffsets = Builder.getVCallOffsets();
}
Adjustment.VCallOffsetOffset =
VCallOffsets.getVCallOffsetOffset(MD).getQuantity();
}
// Set the non-virtual part of the adjustment.
Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
return Adjustment;
}
void
VTableBuilder::AddMethod(const CXXMethodDecl *MD,
ReturnAdjustment ReturnAdjustment) {
if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
assert(ReturnAdjustment.isEmpty() &&
"Destructor can't have return adjustment!");
// Add both the complete destructor and the deleting destructor.
Components.push_back(VTableComponent::MakeCompleteDtor(DD));
Components.push_back(VTableComponent::MakeDeletingDtor(DD));
} else {
// Add the return adjustment if necessary.
if (!ReturnAdjustment.isEmpty())
VTableThunks[Components.size()].Return = ReturnAdjustment;
// Add the function.
Components.push_back(VTableComponent::MakeFunction(MD));
}
}
/// OverridesIndirectMethodInBase - Return whether the given member function
/// overrides any methods in the set of given bases.
/// Unlike OverridesMethodInBase, this checks "overriders of overriders".
/// For example, if we have:
///
/// struct A { virtual void f(); }
/// struct B : A { virtual void f(); }
/// struct C : B { virtual void f(); }
///
/// OverridesIndirectMethodInBase will return true if given C::f as the method
/// and { A } as the set of bases.
static bool
OverridesIndirectMethodInBases(const CXXMethodDecl *MD,
VTableBuilder::PrimaryBasesSetVectorTy &Bases) {
if (Bases.count(MD->getParent()))
return true;
for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(),
E = MD->end_overridden_methods(); I != E; ++I) {
const CXXMethodDecl *OverriddenMD = *I;
// Check "indirect overriders".
if (OverridesIndirectMethodInBases(OverriddenMD, Bases))
return true;
}
return false;
}
bool
VTableBuilder::IsOverriderUsed(const CXXMethodDecl *Overrider,
CharUnits BaseOffsetInLayoutClass,
const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
CharUnits FirstBaseOffsetInLayoutClass) const {
// If the base and the first base in the primary base chain have the same
// offsets, then this overrider will be used.
if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass)
return true;
// We know now that Base (or a direct or indirect base of it) is a primary
// base in part of the class hierarchy, but not a primary base in the most
// derived class.
// If the overrider is the first base in the primary base chain, we know
// that the overrider will be used.
if (Overrider->getParent() == FirstBaseInPrimaryBaseChain)
return true;
VTableBuilder::PrimaryBasesSetVectorTy PrimaryBases;
const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain;
PrimaryBases.insert(RD);
// Now traverse the base chain, starting with the first base, until we find
// the base that is no longer a primary base.
while (true) {
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
if (!PrimaryBase)
break;
if (Layout.isPrimaryBaseVirtual()) {
assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 &&
"Primary base should always be at offset 0!");
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
// Now check if this is the primary base that is not a primary base in the
// most derived class.
if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
FirstBaseOffsetInLayoutClass) {
// We found it, stop walking the chain.
break;
}
} else {
assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 &&
"Primary base should always be at offset 0!");
}
if (!PrimaryBases.insert(PrimaryBase))
assert(false && "Found a duplicate primary base!");
RD = PrimaryBase;
}
// If the final overrider is an override of one of the primary bases,
// then we know that it will be used.
return OverridesIndirectMethodInBases(Overrider, PrimaryBases);
}
/// FindNearestOverriddenMethod - Given a method, returns the overridden method
/// from the nearest base. Returns null if no method was found.
static const CXXMethodDecl *
FindNearestOverriddenMethod(const CXXMethodDecl *MD,
VTableBuilder::PrimaryBasesSetVectorTy &Bases) {
OverriddenMethodsSetTy OverriddenMethods;
ComputeAllOverriddenMethods(MD, OverriddenMethods);
for (int I = Bases.size(), E = 0; I != E; --I) {
const CXXRecordDecl *PrimaryBase = Bases[I - 1];
// Now check the overriden methods.
for (OverriddenMethodsSetTy::const_iterator I = OverriddenMethods.begin(),
E = OverriddenMethods.end(); I != E; ++I) {
const CXXMethodDecl *OverriddenMD = *I;
// We found our overridden method.
if (OverriddenMD->getParent() == PrimaryBase)
return OverriddenMD;
}
}
return 0;
}
void
VTableBuilder::AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
CharUnits FirstBaseOffsetInLayoutClass,
PrimaryBasesSetVectorTy &PrimaryBases) {
const CXXRecordDecl *RD = Base.getBase();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
CharUnits PrimaryBaseOffset;
CharUnits PrimaryBaseOffsetInLayoutClass;
if (Layout.isPrimaryBaseVirtual()) {
assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 &&
"Primary vbase should have a zero offset!");
const ASTRecordLayout &MostDerivedClassLayout =
Context.getASTRecordLayout(MostDerivedClass);
PrimaryBaseOffset =
MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
PrimaryBaseOffsetInLayoutClass =
LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
} else {
assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 &&
"Primary base should have a zero offset!");
PrimaryBaseOffset = Base.getBaseOffset();
PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass;
}
AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset),
PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain,
FirstBaseOffsetInLayoutClass, PrimaryBases);
if (!PrimaryBases.insert(PrimaryBase))
assert(false && "Found a duplicate primary base!");
}
// Now go through all virtual member functions and add them.
for (CXXRecordDecl::method_iterator I = RD->method_begin(),
E = RD->method_end(); I != E; ++I) {
const CXXMethodDecl *MD = *I;
if (!MD->isVirtual())
continue;
// Get the final overrider.
FinalOverriders::OverriderInfo Overrider =
Overriders.getOverrider(MD, Base.getBaseOffset());
// Check if this virtual member function overrides a method in a primary
// base. If this is the case, and the return type doesn't require adjustment
// then we can just use the member function from the primary base.
if (const CXXMethodDecl *OverriddenMD =
FindNearestOverriddenMethod(MD, PrimaryBases)) {
if (ComputeReturnAdjustmentBaseOffset(Context, MD,
OverriddenMD).isEmpty()) {
// Replace the method info of the overridden method with our own
// method.
assert(MethodInfoMap.count(OverriddenMD) &&
"Did not find the overridden method!");
MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD];
MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
OverriddenMethodInfo.VTableIndex);
assert(!MethodInfoMap.count(MD) &&
"Should not have method info for this method yet!");
MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
MethodInfoMap.erase(OverriddenMD);
// If the overridden method exists in a virtual base class or a direct
// or indirect base class of a virtual base class, we need to emit a
// thunk if we ever have a class hierarchy where the base class is not
// a primary base in the complete object.
if (!isBuildingConstructorVTable() && OverriddenMD != MD) {
// Compute the this adjustment.
ThisAdjustment ThisAdjustment =
ComputeThisAdjustment(OverriddenMD, BaseOffsetInLayoutClass,
Overrider);
if (ThisAdjustment.VCallOffsetOffset &&
Overrider.Method->getParent() == MostDerivedClass) {
// There's no return adjustment from OverriddenMD and MD,
// but that doesn't mean there isn't one between MD and
// the final overrider.
BaseOffset ReturnAdjustmentOffset =
ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
ReturnAdjustment ReturnAdjustment =
ComputeReturnAdjustment(ReturnAdjustmentOffset);
// This is a virtual thunk for the most derived class, add it.
AddThunk(Overrider.Method,
ThunkInfo(ThisAdjustment, ReturnAdjustment));
}
}
continue;
}
}
// Insert the method info for this method.
MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
Components.size());
assert(!MethodInfoMap.count(MD) &&
"Should not have method info for this method yet!");
MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
// Check if this overrider is going to be used.
const CXXMethodDecl *OverriderMD = Overrider.Method;
if (!IsOverriderUsed(OverriderMD, BaseOffsetInLayoutClass,
FirstBaseInPrimaryBaseChain,
FirstBaseOffsetInLayoutClass)) {
Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD));
continue;
}
// Check if this overrider needs a return adjustment.
// We don't want to do this for pure virtual member functions.
BaseOffset ReturnAdjustmentOffset;
if (!OverriderMD->isPure()) {
ReturnAdjustmentOffset =
ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD);
}
ReturnAdjustment ReturnAdjustment =
ComputeReturnAdjustment(ReturnAdjustmentOffset);
AddMethod(Overrider.Method, ReturnAdjustment);
}
}
void VTableBuilder::LayoutVTable() {
LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass,
CharUnits::Zero()),
/*BaseIsMorallyVirtual=*/false,
MostDerivedClassIsVirtual,
MostDerivedClassOffset);
VisitedVirtualBasesSetTy VBases;
// Determine the primary virtual bases.
DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset,
VBases);
VBases.clear();
LayoutVTablesForVirtualBases(MostDerivedClass, VBases);
}
void
VTableBuilder::LayoutPrimaryAndSecondaryVTables(BaseSubobject Base,
bool BaseIsMorallyVirtual,
bool BaseIsVirtualInLayoutClass,
CharUnits OffsetInLayoutClass) {
assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!");
// Add vcall and vbase offsets for this vtable.
VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, LayoutClass, &Overriders,
Base, BaseIsVirtualInLayoutClass,
OffsetInLayoutClass);
Components.append(Builder.components_begin(), Builder.components_end());
// Check if we need to add these vcall offsets.
if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) {
VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()];
if (VCallOffsets.empty())
VCallOffsets = Builder.getVCallOffsets();
}
// If we're laying out the most derived class we want to keep track of the
// virtual base class offset offsets.
if (Base.getBase() == MostDerivedClass)
VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets();
// Add the offset to top.
CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass;
Components.push_back(
VTableComponent::MakeOffsetToTop(OffsetToTop));
// Next, add the RTTI.
Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
uint64_t AddressPoint = Components.size();
// Now go through all virtual member functions and add them.
PrimaryBasesSetVectorTy PrimaryBases;
AddMethods(Base, OffsetInLayoutClass,
Base.getBase(), OffsetInLayoutClass,
PrimaryBases);
// Compute 'this' pointer adjustments.
ComputeThisAdjustments();
// Add all address points.
const CXXRecordDecl *RD = Base.getBase();
while (true) {
AddressPoints.insert(std::make_pair(
BaseSubobject(RD, OffsetInLayoutClass),
AddressPoint));
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
if (!PrimaryBase)
break;
if (Layout.isPrimaryBaseVirtual()) {
// Check if this virtual primary base is a primary base in the layout
// class. If it's not, we don't want to add it.
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
OffsetInLayoutClass) {
// We don't want to add this class (or any of its primary bases).
break;
}
}
RD = PrimaryBase;
}
// Layout secondary vtables.
LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass);
}
void VTableBuilder::LayoutSecondaryVTables(BaseSubobject Base,
bool BaseIsMorallyVirtual,
CharUnits OffsetInLayoutClass) {
// Itanium C++ ABI 2.5.2:
// Following the primary virtual table of a derived class are secondary
// virtual tables for each of its proper base classes, except any primary
// base(s) with which it shares its primary virtual table.
const CXXRecordDecl *RD = Base.getBase();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
// Ignore virtual bases, we'll emit them later.
if (I->isVirtual())
continue;
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
// Ignore bases that don't have a vtable.
if (!BaseDecl->isDynamicClass())
continue;
if (isBuildingConstructorVTable()) {
// Itanium C++ ABI 2.6.4:
// Some of the base class subobjects may not need construction virtual
// tables, which will therefore not be present in the construction
// virtual table group, even though the subobject virtual tables are
// present in the main virtual table group for the complete object.
if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases())
continue;
}
// Get the base offset of this base.
CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl);
CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset;
CharUnits BaseOffsetInLayoutClass =
OffsetInLayoutClass + RelativeBaseOffset;
// Don't emit a secondary vtable for a primary base. We might however want
// to emit secondary vtables for other bases of this base.
if (BaseDecl == PrimaryBase) {
LayoutSecondaryVTables(BaseSubobject(BaseDecl, BaseOffset),
BaseIsMorallyVirtual, BaseOffsetInLayoutClass);
continue;
}
// Layout the primary vtable (and any secondary vtables) for this base.
LayoutPrimaryAndSecondaryVTables(
BaseSubobject(BaseDecl, BaseOffset),
BaseIsMorallyVirtual,
/*BaseIsVirtualInLayoutClass=*/false,
BaseOffsetInLayoutClass);
}
}
void
VTableBuilder::DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
CharUnits OffsetInLayoutClass,
VisitedVirtualBasesSetTy &VBases) {
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
// Check if this base has a primary base.
if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
// Check if it's virtual.
if (Layout.isPrimaryBaseVirtual()) {
bool IsPrimaryVirtualBase = true;
if (isBuildingConstructorVTable()) {
// Check if the base is actually a primary base in the class we use for
// layout.
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
CharUnits PrimaryBaseOffsetInLayoutClass =
LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
// We know that the base is not a primary base in the layout class if
// the base offsets are different.
if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass)
IsPrimaryVirtualBase = false;
}
if (IsPrimaryVirtualBase)
PrimaryVirtualBases.insert(PrimaryBase);
}
}
// Traverse bases, looking for more primary virtual bases.
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
CharUnits BaseOffsetInLayoutClass;
if (I->isVirtual()) {
if (!VBases.insert(BaseDecl))
continue;
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
BaseOffsetInLayoutClass =
LayoutClassLayout.getVBaseClassOffset(BaseDecl);
} else {
BaseOffsetInLayoutClass =
OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl);
}
DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases);
}
}
void
VTableBuilder::LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
VisitedVirtualBasesSetTy &VBases) {
// Itanium C++ ABI 2.5.2:
// Then come the virtual base virtual tables, also in inheritance graph
// order, and again excluding primary bases (which share virtual tables with
// the classes for which they are primary).
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
// Check if this base needs a vtable. (If it's virtual, not a primary base
// of some other class, and we haven't visited it before).
if (I->isVirtual() && BaseDecl->isDynamicClass() &&
!PrimaryVirtualBases.count(BaseDecl) && VBases.insert(BaseDecl)) {
const ASTRecordLayout &MostDerivedClassLayout =
Context.getASTRecordLayout(MostDerivedClass);
CharUnits BaseOffset =
MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
CharUnits BaseOffsetInLayoutClass =
LayoutClassLayout.getVBaseClassOffset(BaseDecl);
LayoutPrimaryAndSecondaryVTables(
BaseSubobject(BaseDecl, BaseOffset),
/*BaseIsMorallyVirtual=*/true,
/*BaseIsVirtualInLayoutClass=*/true,
BaseOffsetInLayoutClass);
}
// We only need to check the base for virtual base vtables if it actually
// has virtual bases.
if (BaseDecl->getNumVBases())
LayoutVTablesForVirtualBases(BaseDecl, VBases);
}
}
/// dumpLayout - Dump the vtable layout.
void VTableBuilder::dumpLayout(llvm::raw_ostream& Out) {
if (isBuildingConstructorVTable()) {
Out << "Construction vtable for ('";
Out << MostDerivedClass->getQualifiedNameAsString() << "', ";
Out << MostDerivedClassOffset.getQuantity() << ") in '";
Out << LayoutClass->getQualifiedNameAsString();
} else {
Out << "Vtable for '";
Out << MostDerivedClass->getQualifiedNameAsString();
}
Out << "' (" << Components.size() << " entries).\n";
// Iterate through the address points and insert them into a new map where
// they are keyed by the index and not the base object.
// Since an address point can be shared by multiple subobjects, we use an
// STL multimap.
std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex;
for (AddressPointsMapTy::const_iterator I = AddressPoints.begin(),
E = AddressPoints.end(); I != E; ++I) {
const BaseSubobject& Base = I->first;
uint64_t Index = I->second;
AddressPointsByIndex.insert(std::make_pair(Index, Base));
}
for (unsigned I = 0, E = Components.size(); I != E; ++I) {
uint64_t Index = I;
Out << llvm::format("%4d | ", I);
const VTableComponent &Component = Components[I];
// Dump the component.
switch (Component.getKind()) {
case VTableComponent::CK_VCallOffset:
Out << "vcall_offset ("
<< Component.getVCallOffset().getQuantity()
<< ")";
break;
case VTableComponent::CK_VBaseOffset:
Out << "vbase_offset ("
<< Component.getVBaseOffset().getQuantity()
<< ")";
break;
case VTableComponent::CK_OffsetToTop:
Out << "offset_to_top ("
<< Component.getOffsetToTop().getQuantity()
<< ")";
break;
case VTableComponent::CK_RTTI:
Out << Component.getRTTIDecl()->getQualifiedNameAsString() << " RTTI";
break;
case VTableComponent::CK_FunctionPointer: {
const CXXMethodDecl *MD = Component.getFunctionDecl();
std::string Str =
PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual,
MD);
Out << Str;
if (MD->isPure())
Out << " [pure]";
ThunkInfo Thunk = VTableThunks.lookup(I);
if (!Thunk.isEmpty()) {
// If this function pointer has a return adjustment, dump it.
if (!Thunk.Return.isEmpty()) {
Out << "\n [return adjustment: ";
Out << Thunk.Return.NonVirtual << " non-virtual";
if (Thunk.Return.VBaseOffsetOffset) {
Out << ", " << Thunk.Return.VBaseOffsetOffset;
Out << " vbase offset offset";
}
Out << ']';
}
// If this function pointer has a 'this' pointer adjustment, dump it.
if (!Thunk.This.isEmpty()) {
Out << "\n [this adjustment: ";
Out << Thunk.This.NonVirtual << " non-virtual";
if (Thunk.This.VCallOffsetOffset) {
Out << ", " << Thunk.This.VCallOffsetOffset;
Out << " vcall offset offset";
}
Out << ']';
}
}
break;
}
case VTableComponent::CK_CompleteDtorPointer:
case VTableComponent::CK_DeletingDtorPointer: {
bool IsComplete =
Component.getKind() == VTableComponent::CK_CompleteDtorPointer;
const CXXDestructorDecl *DD = Component.getDestructorDecl();
Out << DD->getQualifiedNameAsString();
if (IsComplete)
Out << "() [complete]";
else
Out << "() [deleting]";
if (DD->isPure())
Out << " [pure]";
ThunkInfo Thunk = VTableThunks.lookup(I);
if (!Thunk.isEmpty()) {
// If this destructor has a 'this' pointer adjustment, dump it.
if (!Thunk.This.isEmpty()) {
Out << "\n [this adjustment: ";
Out << Thunk.This.NonVirtual << " non-virtual";
if (Thunk.This.VCallOffsetOffset) {
Out << ", " << Thunk.This.VCallOffsetOffset;
Out << " vcall offset offset";
}
Out << ']';
}
}
break;
}
case VTableComponent::CK_UnusedFunctionPointer: {
const CXXMethodDecl *MD = Component.getUnusedFunctionDecl();
std::string Str =
PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual,
MD);
Out << "[unused] " << Str;
if (MD->isPure())
Out << " [pure]";
}
}
Out << '\n';
// Dump the next address point.
uint64_t NextIndex = Index + 1;
if (AddressPointsByIndex.count(NextIndex)) {
if (AddressPointsByIndex.count(NextIndex) == 1) {
const BaseSubobject &Base =
AddressPointsByIndex.find(NextIndex)->second;
Out << " -- (" << Base.getBase()->getQualifiedNameAsString();
Out << ", " << Base.getBaseOffset().getQuantity();
Out << ") vtable address --\n";
} else {
CharUnits BaseOffset =
AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset();
// We store the class names in a set to get a stable order.
std::set<std::string> ClassNames;
for (std::multimap<uint64_t, BaseSubobject>::const_iterator I =
AddressPointsByIndex.lower_bound(NextIndex), E =
AddressPointsByIndex.upper_bound(NextIndex); I != E; ++I) {
assert(I->second.getBaseOffset() == BaseOffset &&
"Invalid base offset!");
const CXXRecordDecl *RD = I->second.getBase();
ClassNames.insert(RD->getQualifiedNameAsString());
}
for (std::set<std::string>::const_iterator I = ClassNames.begin(),
E = ClassNames.end(); I != E; ++I) {
Out << " -- (" << *I;
Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n";
}
}
}
}
Out << '\n';
if (isBuildingConstructorVTable())
return;
if (MostDerivedClass->getNumVBases()) {
// We store the virtual base class names and their offsets in a map to get
// a stable order.
std::map<std::string, CharUnits> ClassNamesAndOffsets;
for (VBaseOffsetOffsetsMapTy::const_iterator I = VBaseOffsetOffsets.begin(),
E = VBaseOffsetOffsets.end(); I != E; ++I) {
std::string ClassName = I->first->getQualifiedNameAsString();
CharUnits OffsetOffset = I->second;
ClassNamesAndOffsets.insert(
std::make_pair(ClassName, OffsetOffset));
}
Out << "Virtual base offset offsets for '";
Out << MostDerivedClass->getQualifiedNameAsString() << "' (";
Out << ClassNamesAndOffsets.size();
Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n";
for (std::map<std::string, CharUnits>::const_iterator I =
ClassNamesAndOffsets.begin(), E = ClassNamesAndOffsets.end();
I != E; ++I)
Out << " " << I->first << " | " << I->second.getQuantity() << '\n';
Out << "\n";
}
if (!Thunks.empty()) {
// We store the method names in a map to get a stable order.
std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
for (ThunksMapTy::const_iterator I = Thunks.begin(), E = Thunks.end();
I != E; ++I) {
const CXXMethodDecl *MD = I->first;
std::string MethodName =
PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual,
MD);
MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
}
for (std::map<std::string, const CXXMethodDecl *>::const_iterator I =
MethodNamesAndDecls.begin(), E = MethodNamesAndDecls.end();
I != E; ++I) {
const std::string &MethodName = I->first;
const CXXMethodDecl *MD = I->second;
ThunkInfoVectorTy ThunksVector = Thunks[MD];
std::sort(ThunksVector.begin(), ThunksVector.end());
Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
const ThunkInfo &Thunk = ThunksVector[I];
Out << llvm::format("%4d | ", I);
// If this function pointer has a return pointer adjustment, dump it.
if (!Thunk.Return.isEmpty()) {
Out << "return adjustment: " << Thunk.This.NonVirtual;
Out << " non-virtual";
if (Thunk.Return.VBaseOffsetOffset) {
Out << ", " << Thunk.Return.VBaseOffsetOffset;
Out << " vbase offset offset";
}
if (!Thunk.This.isEmpty())
Out << "\n ";
}
// If this function pointer has a 'this' pointer adjustment, dump it.
if (!Thunk.This.isEmpty()) {
Out << "this adjustment: ";
Out << Thunk.This.NonVirtual << " non-virtual";
if (Thunk.This.VCallOffsetOffset) {
Out << ", " << Thunk.This.VCallOffsetOffset;
Out << " vcall offset offset";
}
}
Out << '\n';
}
Out << '\n';
}
}
// Compute the vtable indices for all the member functions.
// Store them in a map keyed by the index so we'll get a sorted table.
std::map<uint64_t, std::string> IndicesMap;
for (CXXRecordDecl::method_iterator i = MostDerivedClass->method_begin(),
e = MostDerivedClass->method_end(); i != e; ++i) {
const CXXMethodDecl *MD = *i;
// We only want virtual member functions.
if (!MD->isVirtual())
continue;
std::string MethodName =
PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual,
MD);
if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
IndicesMap[VTables.getMethodVTableIndex(GlobalDecl(DD, Dtor_Complete))] =
MethodName + " [complete]";
IndicesMap[VTables.getMethodVTableIndex(GlobalDecl(DD, Dtor_Deleting))] =
MethodName + " [deleting]";
} else {
IndicesMap[VTables.getMethodVTableIndex(MD)] = MethodName;
}
}
// Print the vtable indices for all the member functions.
if (!IndicesMap.empty()) {
Out << "VTable indices for '";
Out << MostDerivedClass->getQualifiedNameAsString();
Out << "' (" << IndicesMap.size() << " entries).\n";
for (std::map<uint64_t, std::string>::const_iterator I = IndicesMap.begin(),
E = IndicesMap.end(); I != E; ++I) {
uint64_t VTableIndex = I->first;
const std::string &MethodName = I->second;
Out << llvm::format(" %4u | ", VTableIndex) << MethodName << '\n';
}
}
Out << '\n';
}
}
static void
CollectPrimaryBases(const CXXRecordDecl *RD, ASTContext &Context,
VTableBuilder::PrimaryBasesSetVectorTy &PrimaryBases) {
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
if (!PrimaryBase)
return;
CollectPrimaryBases(PrimaryBase, Context, PrimaryBases);
if (!PrimaryBases.insert(PrimaryBase))
assert(false && "Found a duplicate primary base!");
}
void CodeGenVTables::ComputeMethodVTableIndices(const CXXRecordDecl *RD) {
// Itanium C++ ABI 2.5.2:
// The order of the virtual function pointers in a virtual table is the
// order of declaration of the corresponding member functions in the class.
//
// There is an entry for any virtual function declared in a class,
// whether it is a new function or overrides a base class function,
// unless it overrides a function from the primary base, and conversion
// between their return types does not require an adjustment.
int64_t CurrentIndex = 0;
const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
if (PrimaryBase) {
assert(PrimaryBase->isDefinition() &&
"Should have the definition decl of the primary base!");
// Since the record decl shares its vtable pointer with the primary base
// we need to start counting at the end of the primary base's vtable.
CurrentIndex = getNumVirtualFunctionPointers(PrimaryBase);
}
// Collect all the primary bases, so we can check whether methods override
// a method from the base.
VTableBuilder::PrimaryBasesSetVectorTy PrimaryBases;
CollectPrimaryBases(RD, CGM.getContext(), PrimaryBases);
const CXXDestructorDecl *ImplicitVirtualDtor = 0;
for (CXXRecordDecl::method_iterator i = RD->method_begin(),
e = RD->method_end(); i != e; ++i) {
const CXXMethodDecl *MD = *i;
// We only want virtual methods.
if (!MD->isVirtual())
continue;
// Check if this method overrides a method in the primary base.
if (const CXXMethodDecl *OverriddenMD =
FindNearestOverriddenMethod(MD, PrimaryBases)) {
// Check if converting from the return type of the method to the
// return type of the overridden method requires conversion.
if (ComputeReturnAdjustmentBaseOffset(CGM.getContext(), MD,
OverriddenMD).isEmpty()) {
// This index is shared between the index in the vtable of the primary
// base class.
if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
const CXXDestructorDecl *OverriddenDD =
cast<CXXDestructorDecl>(OverriddenMD);
// Add both the complete and deleting entries.
MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] =
getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Complete));
MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] =
getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Deleting));
} else {
MethodVTableIndices[MD] = getMethodVTableIndex(OverriddenMD);
}
// We don't need to add an entry for this method.
continue;
}
}
if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
if (MD->isImplicit()) {
assert(!ImplicitVirtualDtor &&
"Did already see an implicit virtual dtor!");
ImplicitVirtualDtor = DD;
continue;
}
// Add the complete dtor.
MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = CurrentIndex++;
// Add the deleting dtor.
MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = CurrentIndex++;
} else {
// Add the entry.
MethodVTableIndices[MD] = CurrentIndex++;
}
}
if (ImplicitVirtualDtor) {
// Itanium C++ ABI 2.5.2:
// If a class has an implicitly-defined virtual destructor,
// its entries come after the declared virtual function pointers.
// Add the complete dtor.
MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Complete)] =
CurrentIndex++;
// Add the deleting dtor.
MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Deleting)] =
CurrentIndex++;
}
NumVirtualFunctionPointers[RD] = CurrentIndex;
}
bool CodeGenVTables::ShouldEmitVTableInThisTU(const CXXRecordDecl *RD) {
assert(RD->isDynamicClass() && "Non dynamic classes have no VTable.");
TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
if (TSK == TSK_ExplicitInstantiationDeclaration)
return false;
const CXXMethodDecl *KeyFunction = CGM.getContext().getKeyFunction(RD);
if (!KeyFunction)
return true;
// Itanium C++ ABI, 5.2.6 Instantiated Templates:
// An instantiation of a class template requires:
// - In the object where instantiated, the virtual table...
if (TSK == TSK_ImplicitInstantiation ||
TSK == TSK_ExplicitInstantiationDefinition)
return true;
// If we're building with optimization, we always emit VTables since that
// allows for virtual function calls to be devirtualized.
// (We don't want to do this in -fapple-kext mode however).
if (CGM.getCodeGenOpts().OptimizationLevel && !CGM.getLangOptions().AppleKext)
return true;
return KeyFunction->hasBody();
}
uint64_t CodeGenVTables::getNumVirtualFunctionPointers(const CXXRecordDecl *RD) {
llvm::DenseMap<const CXXRecordDecl *, uint64_t>::iterator I =
NumVirtualFunctionPointers.find(RD);
if (I != NumVirtualFunctionPointers.end())
return I->second;
ComputeMethodVTableIndices(RD);
I = NumVirtualFunctionPointers.find(RD);
assert(I != NumVirtualFunctionPointers.end() && "Did not find entry!");
return I->second;
}
uint64_t CodeGenVTables::getMethodVTableIndex(GlobalDecl GD) {
MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD);
if (I != MethodVTableIndices.end())
return I->second;
const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
ComputeMethodVTableIndices(RD);
I = MethodVTableIndices.find(GD);
assert(I != MethodVTableIndices.end() && "Did not find index!");
return I->second;
}
CharUnits
CodeGenVTables::getVirtualBaseOffsetOffset(const CXXRecordDecl *RD,
const CXXRecordDecl *VBase) {
ClassPairTy ClassPair(RD, VBase);
VirtualBaseClassOffsetOffsetsMapTy::iterator I =
VirtualBaseClassOffsetOffsets.find(ClassPair);
if (I != VirtualBaseClassOffsetOffsets.end())
return I->second;
VCallAndVBaseOffsetBuilder Builder(RD, RD, /*FinalOverriders=*/0,
BaseSubobject(RD, CharUnits::Zero()),
/*BaseIsVirtual=*/false,
/*OffsetInLayoutClass=*/CharUnits::Zero());
for (VCallAndVBaseOffsetBuilder::VBaseOffsetOffsetsMapTy::const_iterator I =
Builder.getVBaseOffsetOffsets().begin(),
E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) {
// Insert all types.
ClassPairTy ClassPair(RD, I->first);
VirtualBaseClassOffsetOffsets.insert(
std::make_pair(ClassPair, I->second));
}
I = VirtualBaseClassOffsetOffsets.find(ClassPair);
assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!");
return I->second;
}
uint64_t
CodeGenVTables::getAddressPoint(BaseSubobject Base, const CXXRecordDecl *RD) {
assert(AddressPoints.count(std::make_pair(RD, Base)) &&
"Did not find address point!");
uint64_t AddressPoint = AddressPoints.lookup(std::make_pair(RD, Base));
assert(AddressPoint && "Address point must not be zero!");
return AddressPoint;
}
llvm::Constant *CodeGenModule::GetAddrOfThunk(GlobalDecl GD,
const ThunkInfo &Thunk) {
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
// Compute the mangled name.
llvm::SmallString<256> Name;
llvm::raw_svector_ostream Out(Name);
if (const CXXDestructorDecl* DD = dyn_cast<CXXDestructorDecl>(MD))
getCXXABI().getMangleContext().mangleCXXDtorThunk(DD, GD.getDtorType(),
Thunk.This, Out);
else
getCXXABI().getMangleContext().mangleThunk(MD, Thunk, Out);
Out.flush();
const llvm::Type *Ty = getTypes().GetFunctionTypeForVTable(GD);
return GetOrCreateLLVMFunction(Name, Ty, GD, /*ForVTable=*/true);
}
static llvm::Value *PerformTypeAdjustment(CodeGenFunction &CGF,
llvm::Value *Ptr,
int64_t NonVirtualAdjustment,
int64_t VirtualAdjustment) {
if (!NonVirtualAdjustment && !VirtualAdjustment)
return Ptr;
const llvm::Type *Int8PtrTy =
llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy);
if (NonVirtualAdjustment) {
// Do the non-virtual adjustment.
V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment);
}
if (VirtualAdjustment) {
const llvm::Type *PtrDiffTy =
CGF.ConvertType(CGF.getContext().getPointerDiffType());
// Do the virtual adjustment.
llvm::Value *VTablePtrPtr =
CGF.Builder.CreateBitCast(V, Int8PtrTy->getPointerTo());
llvm::Value *VTablePtr = CGF.Builder.CreateLoad(VTablePtrPtr);
llvm::Value *OffsetPtr =
CGF.Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment);
OffsetPtr = CGF.Builder.CreateBitCast(OffsetPtr, PtrDiffTy->getPointerTo());
// Load the adjustment offset from the vtable.
llvm::Value *Offset = CGF.Builder.CreateLoad(OffsetPtr);
// Adjust our pointer.
V = CGF.Builder.CreateInBoundsGEP(V, Offset);
}
// Cast back to the original type.
return CGF.Builder.CreateBitCast(V, Ptr->getType());
}
static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD,
const ThunkInfo &Thunk, llvm::Function *Fn) {
CGM.setGlobalVisibility(Fn, MD);
if (!CGM.getCodeGenOpts().HiddenWeakVTables)
return;
// If the thunk has weak/linkonce linkage, but the function must be
// emitted in every translation unit that references it, then we can
// emit its thunks with hidden visibility, since its thunks must be
// emitted when the function is.
// This follows CodeGenModule::setTypeVisibility; see the comments
// there for explanation.
if ((Fn->getLinkage() != llvm::GlobalVariable::LinkOnceODRLinkage &&
Fn->getLinkage() != llvm::GlobalVariable::WeakODRLinkage) ||
Fn->getVisibility() != llvm::GlobalVariable::DefaultVisibility)
return;
if (MD->getExplicitVisibility())
return;
switch (MD->getTemplateSpecializationKind()) {
case TSK_ExplicitInstantiationDefinition:
case TSK_ExplicitInstantiationDeclaration:
return;
case TSK_Undeclared:
break;
case TSK_ExplicitSpecialization:
case TSK_ImplicitInstantiation:
if (!CGM.getCodeGenOpts().HiddenWeakTemplateVTables)
return;
break;
}
// If there's an explicit definition, and that definition is
// out-of-line, then we can't assume that all users will have a
// definition to emit.
const FunctionDecl *Def = 0;
if (MD->hasBody(Def) && Def->isOutOfLine())
return;
Fn->setVisibility(llvm::GlobalValue::HiddenVisibility);
}
#ifndef NDEBUG
static bool similar(const ABIArgInfo &infoL, CanQualType typeL,
const ABIArgInfo &infoR, CanQualType typeR) {
return (infoL.getKind() == infoR.getKind() &&
(typeL == typeR ||
(isa<PointerType>(typeL) && isa<PointerType>(typeR)) ||
(isa<ReferenceType>(typeL) && isa<ReferenceType>(typeR))));
}
#endif
static RValue PerformReturnAdjustment(CodeGenFunction &CGF,
QualType ResultType, RValue RV,
const ThunkInfo &Thunk) {
// Emit the return adjustment.
bool NullCheckValue = !ResultType->isReferenceType();
llvm::BasicBlock *AdjustNull = 0;
llvm::BasicBlock *AdjustNotNull = 0;
llvm::BasicBlock *AdjustEnd = 0;
llvm::Value *ReturnValue = RV.getScalarVal();
if (NullCheckValue) {
AdjustNull = CGF.createBasicBlock("adjust.null");
AdjustNotNull = CGF.createBasicBlock("adjust.notnull");
AdjustEnd = CGF.createBasicBlock("adjust.end");
llvm::Value *IsNull = CGF.Builder.CreateIsNull(ReturnValue);
CGF.Builder.CreateCondBr(IsNull, AdjustNull, AdjustNotNull);
CGF.EmitBlock(AdjustNotNull);
}
ReturnValue = PerformTypeAdjustment(CGF, ReturnValue,
Thunk.Return.NonVirtual,
Thunk.Return.VBaseOffsetOffset);
if (NullCheckValue) {
CGF.Builder.CreateBr(AdjustEnd);
CGF.EmitBlock(AdjustNull);
CGF.Builder.CreateBr(AdjustEnd);
CGF.EmitBlock(AdjustEnd);
llvm::PHINode *PHI = CGF.Builder.CreatePHI(ReturnValue->getType(), 2);
PHI->addIncoming(ReturnValue, AdjustNotNull);
PHI->addIncoming(llvm::Constant::getNullValue(ReturnValue->getType()),
AdjustNull);
ReturnValue = PHI;
}
return RValue::get(ReturnValue);
}
// This function does roughly the same thing as GenerateThunk, but in a
// very different way, so that va_start and va_end work correctly.
// FIXME: This function assumes "this" is the first non-sret LLVM argument of
// a function, and that there is an alloca built in the entry block
// for all accesses to "this".
// FIXME: This function assumes there is only one "ret" statement per function.
// FIXME: Cloning isn't correct in the presence of indirect goto!
// FIXME: This implementation of thunks bloats codesize by duplicating the
// function definition. There are alternatives:
// 1. Add some sort of stub support to LLVM for cases where we can
// do a this adjustment, then a sibcall.
// 2. We could transform the definition to take a va_list instead of an
// actual variable argument list, then have the thunks (including a
// no-op thunk for the regular definition) call va_start/va_end.
// There's a bit of per-call overhead for this solution, but it's
// better for codesize if the definition is long.
void CodeGenFunction::GenerateVarArgsThunk(
llvm::Function *Fn,
const CGFunctionInfo &FnInfo,
GlobalDecl GD, const ThunkInfo &Thunk) {
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
QualType ResultType = FPT->getResultType();
// Get the original function
const llvm::Type *Ty =
CGM.getTypes().GetFunctionType(FnInfo, /*IsVariadic*/true);
llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
llvm::Function *BaseFn = cast<llvm::Function>(Callee);
// Clone to thunk.
llvm::Function *NewFn = llvm::CloneFunction(BaseFn);
CGM.getModule().getFunctionList().push_back(NewFn);
Fn->replaceAllUsesWith(NewFn);
NewFn->takeName(Fn);
Fn->eraseFromParent();
Fn = NewFn;
// "Initialize" CGF (minimally).
CurFn = Fn;
// Get the "this" value
llvm::Function::arg_iterator AI = Fn->arg_begin();
if (CGM.ReturnTypeUsesSRet(FnInfo))
++AI;
// Find the first store of "this", which will be to the alloca associated
// with "this".
llvm::Value *ThisPtr = &*AI;
llvm::BasicBlock *EntryBB = Fn->begin();
llvm::Instruction *ThisStore = 0;
for (llvm::BasicBlock::iterator I = EntryBB->begin(), E = EntryBB->end();
I != E; I++) {
if (isa<llvm::StoreInst>(I) && I->getOperand(0) == ThisPtr) {
ThisStore = cast<llvm::StoreInst>(I);
break;
}
}
assert(ThisStore && "Store of this should be in entry block?");
// Adjust "this", if necessary.
Builder.SetInsertPoint(ThisStore);
llvm::Value *AdjustedThisPtr =
PerformTypeAdjustment(*this, ThisPtr,
Thunk.This.NonVirtual,
Thunk.This.VCallOffsetOffset);
ThisStore->setOperand(0, AdjustedThisPtr);
if (!Thunk.Return.isEmpty()) {
// Fix up the returned value, if necessary.
for (llvm::Function::iterator I = Fn->begin(), E = Fn->end(); I != E; I++) {
llvm::Instruction *T = I->getTerminator();
if (isa<llvm::ReturnInst>(T)) {
RValue RV = RValue::get(T->getOperand(0));
T->eraseFromParent();
Builder.SetInsertPoint(&*I);
RV = PerformReturnAdjustment(*this, ResultType, RV, Thunk);
Builder.CreateRet(RV.getScalarVal());
break;
}
}
}
}
void CodeGenFunction::GenerateThunk(llvm::Function *Fn,
const CGFunctionInfo &FnInfo,
GlobalDecl GD, const ThunkInfo &Thunk) {
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
QualType ResultType = FPT->getResultType();
QualType ThisType = MD->getThisType(getContext());
FunctionArgList FunctionArgs;
// FIXME: It would be nice if more of this code could be shared with
// CodeGenFunction::GenerateCode.
// Create the implicit 'this' parameter declaration.
CurGD = GD;
CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResultType, FunctionArgs);
// Add the rest of the parameters.
for (FunctionDecl::param_const_iterator I = MD->param_begin(),
E = MD->param_end(); I != E; ++I) {
ParmVarDecl *Param = *I;
FunctionArgs.push_back(Param);
}
StartFunction(GlobalDecl(), ResultType, Fn, FnInfo, FunctionArgs,
SourceLocation());
CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
// Adjust the 'this' pointer if necessary.
llvm::Value *AdjustedThisPtr =
PerformTypeAdjustment(*this, LoadCXXThis(),
Thunk.This.NonVirtual,
Thunk.This.VCallOffsetOffset);
CallArgList CallArgs;
// Add our adjusted 'this' pointer.
CallArgs.add(RValue::get(AdjustedThisPtr), ThisType);
// Add the rest of the parameters.
for (FunctionDecl::param_const_iterator I = MD->param_begin(),
E = MD->param_end(); I != E; ++I) {
ParmVarDecl *param = *I;
EmitDelegateCallArg(CallArgs, param);
}
// Get our callee.
const llvm::Type *Ty =
CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(GD),
FPT->isVariadic());
llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
#ifndef NDEBUG
const CGFunctionInfo &CallFnInfo =
CGM.getTypes().getFunctionInfo(ResultType, CallArgs, FPT->getExtInfo());
assert(CallFnInfo.getRegParm() == FnInfo.getRegParm() &&
CallFnInfo.isNoReturn() == FnInfo.isNoReturn() &&
CallFnInfo.getCallingConvention() == FnInfo.getCallingConvention());
assert(similar(CallFnInfo.getReturnInfo(), CallFnInfo.getReturnType(),
FnInfo.getReturnInfo(), FnInfo.getReturnType()));
assert(CallFnInfo.arg_size() == FnInfo.arg_size());
for (unsigned i = 0, e = FnInfo.arg_size(); i != e; ++i)
assert(similar(CallFnInfo.arg_begin()[i].info,
CallFnInfo.arg_begin()[i].type,
FnInfo.arg_begin()[i].info, FnInfo.arg_begin()[i].type));
#endif
// Determine whether we have a return value slot to use.
ReturnValueSlot Slot;
if (!ResultType->isVoidType() &&
FnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect &&
hasAggregateLLVMType(CurFnInfo->getReturnType()))
Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified());
// Now emit our call.
RValue RV = EmitCall(FnInfo, Callee, Slot, CallArgs, MD);
if (!Thunk.Return.isEmpty())
RV = PerformReturnAdjustment(*this, ResultType, RV, Thunk);
if (!ResultType->isVoidType() && Slot.isNull())
CGM.getCXXABI().EmitReturnFromThunk(*this, RV, ResultType);
FinishFunction();
// Set the right linkage.
CGM.setFunctionLinkage(MD, Fn);
// Set the right visibility.
setThunkVisibility(CGM, MD, Thunk, Fn);
}
void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk,
bool UseAvailableExternallyLinkage)
{
const CGFunctionInfo &FnInfo = CGM.getTypes().getFunctionInfo(GD);
// FIXME: re-use FnInfo in this computation.
llvm::Constant *Entry = CGM.GetAddrOfThunk(GD, Thunk);
// Strip off a bitcast if we got one back.
if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
assert(CE->getOpcode() == llvm::Instruction::BitCast);
Entry = CE->getOperand(0);
}
// There's already a declaration with the same name, check if it has the same
// type or if we need to replace it.
if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() !=
CGM.getTypes().GetFunctionTypeForVTable(GD)) {
llvm::GlobalValue *OldThunkFn = cast<llvm::GlobalValue>(Entry);
// If the types mismatch then we have to rewrite the definition.
assert(OldThunkFn->isDeclaration() &&
"Shouldn't replace non-declaration");
// Remove the name from the old thunk function and get a new thunk.
OldThunkFn->setName(llvm::StringRef());
Entry = CGM.GetAddrOfThunk(GD, Thunk);
// If needed, replace the old thunk with a bitcast.
if (!OldThunkFn->use_empty()) {
llvm::Constant *NewPtrForOldDecl =
llvm::ConstantExpr::getBitCast(Entry, OldThunkFn->getType());
OldThunkFn->replaceAllUsesWith(NewPtrForOldDecl);
}
// Remove the old thunk.
OldThunkFn->eraseFromParent();
}
llvm::Function *ThunkFn = cast<llvm::Function>(Entry);
if (!ThunkFn->isDeclaration()) {
if (UseAvailableExternallyLinkage) {
// There is already a thunk emitted for this function, do nothing.
return;
}
// If a function has a body, it should have available_externally linkage.
assert(ThunkFn->hasAvailableExternallyLinkage() &&
"Function should have available_externally linkage!");
// Change the linkage.
CGM.setFunctionLinkage(cast<CXXMethodDecl>(GD.getDecl()), ThunkFn);
return;
}
if (ThunkFn->isVarArg()) {
// Varargs thunks are special; we can't just generate a call because
// we can't copy the varargs. Our implementation is rather
// expensive/sucky at the moment, so don't generate the thunk unless
// we have to.
// FIXME: Do something better here; GenerateVarArgsThunk is extremely ugly.
if (!UseAvailableExternallyLinkage)
CodeGenFunction(CGM).GenerateVarArgsThunk(ThunkFn, FnInfo, GD, Thunk);
} else {
// Normal thunk body generation.
CodeGenFunction(CGM).GenerateThunk(ThunkFn, FnInfo, GD, Thunk);
}
if (UseAvailableExternallyLinkage)
ThunkFn->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);
}
void CodeGenVTables::MaybeEmitThunkAvailableExternally(GlobalDecl GD,
const ThunkInfo &Thunk) {
// We only want to do this when building with optimizations.
if (!CGM.getCodeGenOpts().OptimizationLevel)
return;
// We can't emit thunks for member functions with incomplete types.
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
if (!CGM.getTypes().isFuncTypeConvertible(
cast<FunctionType>(MD->getType().getTypePtr())))
return;
EmitThunk(GD, Thunk, /*UseAvailableExternallyLinkage=*/true);
}
void CodeGenVTables::EmitThunks(GlobalDecl GD)
{
const CXXMethodDecl *MD =
cast<CXXMethodDecl>(GD.getDecl())->getCanonicalDecl();
// We don't need to generate thunks for the base destructor.
if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base)
return;
const CXXRecordDecl *RD = MD->getParent();
// Compute VTable related info for this class.
ComputeVTableRelatedInformation(RD, false);
ThunksMapTy::const_iterator I = Thunks.find(MD);
if (I == Thunks.end()) {
// We did not find a thunk for this method.
return;
}
const ThunkInfoVectorTy &ThunkInfoVector = I->second;
for (unsigned I = 0, E = ThunkInfoVector.size(); I != E; ++I)
EmitThunk(GD, ThunkInfoVector[I], /*UseAvailableExternallyLinkage=*/false);
}
void CodeGenVTables::ComputeVTableRelatedInformation(const CXXRecordDecl *RD,
bool RequireVTable) {
VTableLayoutData &Entry = VTableLayoutMap[RD];
// We may need to generate a definition for this vtable.
if (RequireVTable && !Entry.getInt()) {
if (ShouldEmitVTableInThisTU(RD))
CGM.DeferredVTables.push_back(RD);
Entry.setInt(true);
}
// Check if we've computed this information before.
if (Entry.getPointer())
return;
VTableBuilder Builder(*this, RD, CharUnits::Zero(),
/*MostDerivedClassIsVirtual=*/0, RD);
// Add the VTable layout.
uint64_t NumVTableComponents = Builder.getNumVTableComponents();
// -fapple-kext adds an extra entry at end of vtbl.
bool IsAppleKext = CGM.getContext().getLangOptions().AppleKext;
if (IsAppleKext)
NumVTableComponents += 1;
uint64_t *LayoutData = new uint64_t[NumVTableComponents + 1];
if (IsAppleKext)
LayoutData[NumVTableComponents] = 0;
Entry.setPointer(LayoutData);
// Store the number of components.
LayoutData[0] = NumVTableComponents;
// Store the components.
std::copy(Builder.vtable_components_data_begin(),
Builder.vtable_components_data_end(),
&LayoutData[1]);
// Add the known thunks.
Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
// Add the thunks needed in this vtable.
assert(!VTableThunksMap.count(RD) &&
"Thunks already exists for this vtable!");
VTableThunksTy &VTableThunks = VTableThunksMap[RD];
VTableThunks.append(Builder.vtable_thunks_begin(),
Builder.vtable_thunks_end());
// Sort them.
std::sort(VTableThunks.begin(), VTableThunks.end());
// Add the address points.
for (VTableBuilder::AddressPointsMapTy::const_iterator I =
Builder.address_points_begin(), E = Builder.address_points_end();
I != E; ++I) {
uint64_t &AddressPoint = AddressPoints[std::make_pair(RD, I->first)];
// Check if we already have the address points for this base.
assert(!AddressPoint && "Address point already exists for this base!");
AddressPoint = I->second;
}
// If we don't have the vbase information for this class, insert it.
// getVirtualBaseOffsetOffset will compute it separately without computing
// the rest of the vtable related information.
if (!RD->getNumVBases())
return;
const RecordType *VBaseRT =
RD->vbases_begin()->getType()->getAs<RecordType>();
const CXXRecordDecl *VBase = cast<CXXRecordDecl>(VBaseRT->getDecl());
if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase)))
return;
for (VTableBuilder::VBaseOffsetOffsetsMapTy::const_iterator I =
Builder.getVBaseOffsetOffsets().begin(),
E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) {
// Insert all types.
ClassPairTy ClassPair(RD, I->first);
VirtualBaseClassOffsetOffsets.insert(
std::make_pair(ClassPair, I->second));
}
}
llvm::Constant *
CodeGenVTables::CreateVTableInitializer(const CXXRecordDecl *RD,
const uint64_t *Components,
unsigned NumComponents,
const VTableThunksTy &VTableThunks) {
llvm::SmallVector<llvm::Constant *, 64> Inits;
const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext());
const llvm::Type *PtrDiffTy =
CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
QualType ClassType = CGM.getContext().getTagDeclType(RD);
llvm::Constant *RTTI = CGM.GetAddrOfRTTIDescriptor(ClassType);
unsigned NextVTableThunkIndex = 0;
llvm::Constant* PureVirtualFn = 0;
for (unsigned I = 0; I != NumComponents; ++I) {
VTableComponent Component =
VTableComponent::getFromOpaqueInteger(Components[I]);
llvm::Constant *Init = 0;
switch (Component.getKind()) {
case VTableComponent::CK_VCallOffset:
Init = llvm::ConstantInt::get(PtrDiffTy,
Component.getVCallOffset().getQuantity());
Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
break;
case VTableComponent::CK_VBaseOffset:
Init = llvm::ConstantInt::get(PtrDiffTy,
Component.getVBaseOffset().getQuantity());
Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
break;
case VTableComponent::CK_OffsetToTop:
Init = llvm::ConstantInt::get(PtrDiffTy,
Component.getOffsetToTop().getQuantity());
Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
break;
case VTableComponent::CK_RTTI:
Init = llvm::ConstantExpr::getBitCast(RTTI, Int8PtrTy);
break;
case VTableComponent::CK_FunctionPointer:
case VTableComponent::CK_CompleteDtorPointer:
case VTableComponent::CK_DeletingDtorPointer: {
GlobalDecl GD;
// Get the right global decl.
switch (Component.getKind()) {
default:
llvm_unreachable("Unexpected vtable component kind");
case VTableComponent::CK_FunctionPointer:
GD = Component.getFunctionDecl();
break;
case VTableComponent::CK_CompleteDtorPointer:
GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Complete);
break;
case VTableComponent::CK_DeletingDtorPointer:
GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Deleting);
break;
}
if (cast<CXXMethodDecl>(GD.getDecl())->isPure()) {
// We have a pure virtual member function.
if (!PureVirtualFn) {
const llvm::FunctionType *Ty =
llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
/*isVarArg=*/false);
PureVirtualFn =
CGM.CreateRuntimeFunction(Ty, "__cxa_pure_virtual");
PureVirtualFn = llvm::ConstantExpr::getBitCast(PureVirtualFn,
Int8PtrTy);
}
Init = PureVirtualFn;
} else {
// Check if we should use a thunk.
if (NextVTableThunkIndex < VTableThunks.size() &&
VTableThunks[NextVTableThunkIndex].first == I) {
const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second;
Init = CGM.GetAddrOfThunk(GD, Thunk);
MaybeEmitThunkAvailableExternally(GD, Thunk);
NextVTableThunkIndex++;
} else {
const llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVTable(GD);
Init = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
}
Init = llvm::ConstantExpr::getBitCast(Init, Int8PtrTy);
}
break;
}
case VTableComponent::CK_UnusedFunctionPointer:
Init = llvm::ConstantExpr::getNullValue(Int8PtrTy);
break;
};
Inits.push_back(Init);
}
llvm::ArrayType *ArrayType = llvm::ArrayType::get(Int8PtrTy, NumComponents);
return llvm::ConstantArray::get(ArrayType, Inits);
}
llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTable(const CXXRecordDecl *RD) {
llvm::SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
CGM.getCXXABI().getMangleContext().mangleCXXVTable(RD, Out);
Out.flush();
llvm::StringRef Name = OutName.str();
ComputeVTableRelatedInformation(RD, /*VTableRequired=*/true);
const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext());
llvm::ArrayType *ArrayType =
llvm::ArrayType::get(Int8PtrTy, getNumVTableComponents(RD));
llvm::GlobalVariable *GV =
CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType,
llvm::GlobalValue::ExternalLinkage);
GV->setUnnamedAddr(true);
return GV;
}
void
CodeGenVTables::EmitVTableDefinition(llvm::GlobalVariable *VTable,
llvm::GlobalVariable::LinkageTypes Linkage,
const CXXRecordDecl *RD) {
// Dump the vtable layout if necessary.
if (CGM.getLangOptions().DumpVTableLayouts) {
VTableBuilder Builder(*this, RD, CharUnits::Zero(),
/*MostDerivedClassIsVirtual=*/0, RD);
Builder.dumpLayout(llvm::errs());
}
assert(VTableThunksMap.count(RD) &&
"No thunk status for this record decl!");
const VTableThunksTy& Thunks = VTableThunksMap[RD];
// Create and set the initializer.
llvm::Constant *Init =
CreateVTableInitializer(RD, getVTableComponentsData(RD),
getNumVTableComponents(RD), Thunks);
VTable->setInitializer(Init);
// Set the correct linkage.
VTable->setLinkage(Linkage);
// Set the right visibility.
CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForVTable);
}
llvm::GlobalVariable *
CodeGenVTables::GenerateConstructionVTable(const CXXRecordDecl *RD,
const BaseSubobject &Base,
bool BaseIsVirtual,
llvm::GlobalVariable::LinkageTypes Linkage,
VTableAddressPointsMapTy& AddressPoints) {
VTableBuilder Builder(*this, Base.getBase(),
Base.getBaseOffset(),
/*MostDerivedClassIsVirtual=*/BaseIsVirtual, RD);
// Dump the vtable layout if necessary.
if (CGM.getLangOptions().DumpVTableLayouts)
Builder.dumpLayout(llvm::errs());
// Add the address points.
AddressPoints.insert(Builder.address_points_begin(),
Builder.address_points_end());
// Get the mangled construction vtable name.
llvm::SmallString<256> OutName;
llvm::raw_svector_ostream Out(OutName);
CGM.getCXXABI().getMangleContext().
mangleCXXCtorVTable(RD, Base.getBaseOffset().getQuantity(), Base.getBase(),
Out);
Out.flush();
llvm::StringRef Name = OutName.str();
const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext());
llvm::ArrayType *ArrayType =
llvm::ArrayType::get(Int8PtrTy, Builder.getNumVTableComponents());
// Create the variable that will hold the construction vtable.
llvm::GlobalVariable *VTable =
CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, Linkage);
CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForConstructionVTable);
// V-tables are always unnamed_addr.
VTable->setUnnamedAddr(true);
// Add the thunks.
VTableThunksTy VTableThunks;
VTableThunks.append(Builder.vtable_thunks_begin(),
Builder.vtable_thunks_end());
// Sort them.
std::sort(VTableThunks.begin(), VTableThunks.end());
// Create and set the initializer.
llvm::Constant *Init =
CreateVTableInitializer(Base.getBase(),
Builder.vtable_components_data_begin(),
Builder.getNumVTableComponents(), VTableThunks);
VTable->setInitializer(Init);
return VTable;
}
void
CodeGenVTables::GenerateClassData(llvm::GlobalVariable::LinkageTypes Linkage,
const CXXRecordDecl *RD) {
llvm::GlobalVariable *&VTable = VTables[RD];
if (VTable) {
assert(VTable->getInitializer() && "VTable doesn't have a definition!");
return;
}
VTable = GetAddrOfVTable(RD);
EmitVTableDefinition(VTable, Linkage, RD);
if (RD->getNumVBases()) {
llvm::GlobalVariable *VTT = GetAddrOfVTT(RD);
EmitVTTDefinition(VTT, Linkage, RD);
}
// If this is the magic class __cxxabiv1::__fundamental_type_info,
// we will emit the typeinfo for the fundamental types. This is the
// same behaviour as GCC.
const DeclContext *DC = RD->getDeclContext();
if (RD->getIdentifier() &&
RD->getIdentifier()->isStr("__fundamental_type_info") &&
isa<NamespaceDecl>(DC) &&
cast<NamespaceDecl>(DC)->getIdentifier() &&
cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") &&
DC->getParent()->isTranslationUnit())
CGM.EmitFundamentalRTTIDescriptors();
}
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