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//===--- CGVtable.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 "clang/AST/CXXInheritance.h"
#include "clang/AST/RecordLayout.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Format.h"
#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.
int64_t NonVirtualOffset;
BaseOffset() : DerivedClass(0), VirtualBase(0), NonVirtualOffset(0) { }
BaseOffset(const CXXRecordDecl *DerivedClass,
const CXXRecordDecl *VirtualBase, int64_t NonVirtualOffset)
: DerivedClass(DerivedClass), VirtualBase(VirtualBase),
NonVirtualOffset(NonVirtualOffset) { }
bool isEmpty() const { return !NonVirtualOffset && !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 relative to the layout class.
int64_t Offset;
OverriderInfo() : Method(0), Offset(0) { }
};
private:
/// MostDerivedClass - The most derived class for which the final overriders
/// are stored.
const CXXRecordDecl *MostDerivedClass;
ASTContext &Context;
/// MostDerivedClassLayout - the AST record layout of the most derived class.
const ASTRecordLayout &MostDerivedClassLayout;
/// BaseSubobjectMethodPairTy - Uniquely identifies a member function
/// in a base subobject.
typedef std::pair<BaseSubobject, const CXXMethodDecl *>
BaseSubobjectMethodPairTy;
typedef llvm::DenseMap<BaseSubobjectMethodPairTy,
OverriderInfo> OverridersMapTy;
/// OverridersMap - The final overriders for all virtual member functions of
/// all the base subobjects of the most derived class.
OverridersMapTy OverridersMap;
/// VisitedVirtualBases - A set of all the visited virtual bases, used to
/// avoid visiting virtual bases more than once.
llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
typedef llvm::DenseMap<BaseSubobjectMethodPairTy, BaseOffset>
AdjustmentOffsetsMapTy;
/// ReturnAdjustments - Holds return adjustments for all the overriders that
/// need to perform return value adjustments.
AdjustmentOffsetsMapTy ReturnAdjustments;
// FIXME: We might be able to get away with making this a SmallSet.
typedef llvm::SmallSetVector<uint64_t, 2> OffsetSetVectorTy;
/// SubobjectOffsetsMapTy - This map is used for keeping track of all the
/// base subobject offsets that a single class declaration might refer to.
///
/// For example, in:
///
/// struct A { virtual void f(); };
/// struct B1 : A { };
/// struct B2 : A { };
/// struct C : B1, B2 { virtual void f(); };
///
/// when we determine that C::f() overrides A::f(), we need to update the
/// overriders map for both A-in-B1 and A-in-B2 and the subobject offsets map
/// will have the subobject offsets for both A copies.
typedef llvm::DenseMap<const CXXRecordDecl *, OffsetSetVectorTy>
SubobjectOffsetsMapTy;
/// ComputeFinalOverriders - Compute the final overriders for a given base
/// subobject (and all its direct and indirect bases).
void ComputeFinalOverriders(BaseSubobject Base,
bool BaseSubobjectIsVisitedVBase,
SubobjectOffsetsMapTy &Offsets);
/// AddOverriders - Add the final overriders for this base subobject to the
/// map of final overriders.
void AddOverriders(BaseSubobject Base, SubobjectOffsetsMapTy &Offsets);
/// PropagateOverrider - Propagate the NewMD overrider to all the functions
/// that OldMD overrides. For example, if we have:
///
/// struct A { virtual void f(); };
/// struct B : A { virtual void f(); };
/// struct C : B { virtual void f(); };
///
/// and we want to override B::f with C::f, we also need to override A::f with
/// C::f.
void PropagateOverrider(const CXXMethodDecl *OldMD,
BaseSubobject NewBase,
const CXXMethodDecl *NewMD,
SubobjectOffsetsMapTy &Offsets);
static void MergeSubobjectOffsets(const SubobjectOffsetsMapTy &NewOffsets,
SubobjectOffsetsMapTy &Offsets);
public:
explicit FinalOverriders(const CXXRecordDecl *MostDerivedClass);
/// getOverrider - Get the final overrider for the given method declaration in
/// the given base subobject.
OverriderInfo getOverrider(BaseSubobject Base,
const CXXMethodDecl *MD) const {
assert(OverridersMap.count(std::make_pair(Base, MD)) &&
"Did not find overrider!");
return OverridersMap.lookup(std::make_pair(Base, MD));
}
/// getReturnAdjustmentOffset - Get the return adjustment offset for the
/// method decl in the given base subobject. Returns an empty base offset if
/// no adjustment is needed.
BaseOffset getReturnAdjustmentOffset(BaseSubobject Base,
const CXXMethodDecl *MD) const {
return ReturnAdjustments.lookup(std::make_pair(Base, MD));
}
/// dump - dump the final overriders.
void dump() {
assert(VisitedVirtualBases.empty() &&
"Visited virtual bases aren't empty!");
dump(llvm::errs(), BaseSubobject(MostDerivedClass, 0));
VisitedVirtualBases.clear();
}
/// 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);
};
#define DUMP_OVERRIDERS 0
FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass)
: MostDerivedClass(MostDerivedClass),
Context(MostDerivedClass->getASTContext()),
MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) {
// Compute the final overriders.
SubobjectOffsetsMapTy Offsets;
ComputeFinalOverriders(BaseSubobject(MostDerivedClass, 0),
/*BaseSubobjectIsVisitedVBase=*/false, Offsets);
VisitedVirtualBases.clear();
#if DUMP_OVERRIDERS
// And dump them (for now).
dump();
// Also dump the base offsets (for now).
for (SubobjectOffsetsMapTy::const_iterator I = Offsets.begin(),
E = Offsets.end(); I != E; ++I) {
const OffsetVectorTy& OffsetVector = I->second;
llvm::errs() << "Base offsets for ";
llvm::errs() << I->first->getQualifiedNameAsString() << '\n';
for (unsigned I = 0, E = OffsetVector.size(); I != E; ++I)
llvm::errs() << " " << I << " - " << OffsetVector[I] << '\n';
}
#endif
}
void FinalOverriders::AddOverriders(BaseSubobject Base,
SubobjectOffsetsMapTy &Offsets) {
const CXXRecordDecl *RD = Base.getBase();
for (CXXRecordDecl::method_iterator I = RD->method_begin(),
E = RD->method_end(); I != E; ++I) {
const CXXMethodDecl *MD = *I;
if (!MD->isVirtual())
continue;
// First, propagate the overrider.
PropagateOverrider(MD, Base, MD, Offsets);
// Add the overrider as the final overrider of itself.
OverriderInfo& Overrider = OverridersMap[std::make_pair(Base, MD)];
assert(!Overrider.Method && "Overrider should not exist yet!");
Overrider.Offset = Base.getBaseOffset();
Overrider.Method = MD;
}
}
static BaseOffset ComputeBaseOffset(ASTContext &Context,
const CXXRecordDecl *DerivedRD,
const CXXBasePath &Path) {
int64_t NonVirtualOffset = 0;
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 / 8);
}
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::PropagateOverrider(const CXXMethodDecl *OldMD,
BaseSubobject NewBase,
const CXXMethodDecl *NewMD,
SubobjectOffsetsMapTy &Offsets) {
for (CXXMethodDecl::method_iterator I = OldMD->begin_overridden_methods(),
E = OldMD->end_overridden_methods(); I != E; ++I) {
const CXXMethodDecl *OverriddenMD = *I;
const CXXRecordDecl *OverriddenRD = OverriddenMD->getParent();
// We want to override OverriddenMD in all subobjects, for example:
//
/// struct A { virtual void f(); };
/// struct B1 : A { };
/// struct B2 : A { };
/// struct C : B1, B2 { virtual void f(); };
///
/// When overriding A::f with C::f we need to do so in both A subobjects.
const OffsetSetVectorTy &OffsetVector = Offsets[OverriddenRD];
// Go through all the subobjects.
for (unsigned I = 0, E = OffsetVector.size(); I != E; ++I) {
uint64_t Offset = OffsetVector[I];
BaseSubobject OverriddenSubobject = BaseSubobject(OverriddenRD, Offset);
BaseSubobjectMethodPairTy SubobjectAndMethod =
std::make_pair(OverriddenSubobject, OverriddenMD);
OverriderInfo &Overrider = OverridersMap[SubobjectAndMethod];
assert(Overrider.Method && "Did not find existing overrider!");
// Check if we need return adjustments or base adjustments.
// (We don't want to do this for pure virtual member functions).
if (!NewMD->isPure()) {
// Get the return adjustment base offset.
BaseOffset ReturnBaseOffset =
ComputeReturnAdjustmentBaseOffset(Context, NewMD, OverriddenMD);
if (!ReturnBaseOffset.isEmpty()) {
// Store the return adjustment base offset.
ReturnAdjustments[SubobjectAndMethod] = ReturnBaseOffset;
}
}
// Set the new overrider.
Overrider.Offset = NewBase.getBaseOffset();
Overrider.Method = NewMD;
// And propagate it further.
PropagateOverrider(OverriddenMD, NewBase, NewMD, Offsets);
}
}
}
void
FinalOverriders::MergeSubobjectOffsets(const SubobjectOffsetsMapTy &NewOffsets,
SubobjectOffsetsMapTy &Offsets) {
// Iterate over the new offsets.
for (SubobjectOffsetsMapTy::const_iterator I = NewOffsets.begin(),
E = NewOffsets.end(); I != E; ++I) {
const CXXRecordDecl *NewRD = I->first;
const OffsetSetVectorTy& NewOffsetVector = I->second;
OffsetSetVectorTy &OffsetVector = Offsets[NewRD];
// Merge the new offsets set vector into the old.
OffsetVector.insert(NewOffsetVector.begin(), NewOffsetVector.end());
}
}
void FinalOverriders::ComputeFinalOverriders(BaseSubobject Base,
bool BaseSubobjectIsVisitedVBase,
SubobjectOffsetsMapTy &Offsets) {
const CXXRecordDecl *RD = Base.getBase();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
SubobjectOffsetsMapTy NewOffsets;
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;
bool IsVisitedVirtualBase = BaseSubobjectIsVisitedVBase;
uint64_t BaseOffset;
if (I->isVirtual()) {
if (!VisitedVirtualBases.insert(BaseDecl))
IsVisitedVirtualBase = true;
BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
} else {
BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset();
}
// Compute the final overriders for this base.
// We always want to compute the final overriders, even if the base is a
// visited virtual base. Consider:
//
// struct A {
// virtual void f();
// virtual void g();
// };
//
// struct B : virtual A {
// void f();
// };
//
// struct C : virtual A {
// void g ();
// };
//
// struct D : B, C { };
//
// Here, we still want to compute the overriders for A as a base of C,
// because otherwise we'll miss that C::g overrides A::f.
ComputeFinalOverriders(BaseSubobject(BaseDecl, BaseOffset),
IsVisitedVirtualBase, NewOffsets);
}
/// Now add the overriders for this particular subobject.
/// (We don't want to do this more than once for a virtual base).
if (!BaseSubobjectIsVisitedVBase)
AddOverriders(Base, NewOffsets);
// And merge the newly discovered subobject offsets.
MergeSubobjectOffsets(NewOffsets, Offsets);
/// Finally, add the offset for our own subobject.
Offsets[RD].insert(Base.getBaseOffset());
}
void FinalOverriders::dump(llvm::raw_ostream &Out, BaseSubobject Base) {
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;
uint64_t 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));
}
Out << "Final overriders for (" << RD->getQualifiedNameAsString() << ", ";
Out << Base.getBaseOffset() << ")\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(Base, MD);
Out << " " << MD->getQualifiedNameAsString() << " - (";
Out << Overrider.Method->getQualifiedNameAsString();
Out << ", " << Overrider.Offset << ')';
AdjustmentOffsetsMapTy::const_iterator AI =
ReturnAdjustments.find(std::make_pair(Base, MD));
if (AI != ReturnAdjustments.end()) {
const BaseOffset &Offset = AI->second;
Out << " [ret-adj: ";
if (Offset.VirtualBase)
Out << Offset.VirtualBase->getQualifiedNameAsString() << " vbase, ";
Out << Offset.NonVirtualOffset << " 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(int64_t Offset) {
return VtableComponent(CK_VCallOffset, Offset);
}
static VtableComponent MakeVBaseOffset(int64_t Offset) {
return VtableComponent(CK_VBaseOffset, Offset);
}
static VtableComponent MakeOffsetToTop(int64_t 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));
}
/// getKind - Get the kind of this vtable component.
Kind getKind() const {
return (Kind)(Value & 0x7);
}
int64_t getVCallOffset() const {
assert(getKind() == CK_VCallOffset && "Invalid component kind!");
return getOffset();
}
int64_t getVBaseOffset() const {
assert(getKind() == CK_VBaseOffset && "Invalid component kind!");
return getOffset();
}
int64_t 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, int64_t Offset) {
assert((ComponentKind == CK_VCallOffset ||
ComponentKind == CK_VBaseOffset ||
ComponentKind == CK_OffsetToTop) && "Invalid component kind!");
assert(Offset <= ((1LL << 56) - 1) && "Offset is too big!");
Value = ((Offset << 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;
}
int64_t getOffset() const {
assert((getKind() == CK_VCallOffset || getKind() == CK_VBaseOffset ||
getKind() == CK_OffsetToTop) && "Invalid component kind!");
return 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);
}
/// 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 *, int64_t> 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, int64_t OffsetOffset);
/// getVCallOffsetOffset - Returns the vcall offset offset (relative to the
/// vtable address point) for the given virtual member function.
int64_t 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,
int64_t 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;
}
int64_t 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 0;
}
/// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets.
class VCallAndVBaseOffsetBuilder {
/// 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;
/// 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,
uint64_t RealBaseOffset);
/// AddVCallOffsets - Add vcall offsets for the given base subobject.
void AddVCallOffsets(BaseSubobject Base, uint64_t VBaseOffset);
/// AddVBaseOffsets - Add vbase offsets for the given class.
void AddVBaseOffsets(const CXXRecordDecl *Base, uint64_t OffsetInLayoutClass);
public:
VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass,
const CXXRecordDecl *LayoutClass,
const FinalOverriders *Overriders,
BaseSubobject Base, bool BaseIsVirtual,
uint64_t 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; }
};
void
VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base,
bool BaseIsVirtual,
uint64_t 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.getPrimaryBaseWasVirtual();
uint64_t PrimaryBaseOffset;
// Get the base offset of the primary base.
if (PrimaryBaseIsVirtual) {
assert(Layout.getVBaseClassOffset(PrimaryBase) == 0 &&
"Primary vbase should have a zero offset!");
const ASTRecordLayout &MostDerivedClassLayout =
Context.getASTRecordLayout(MostDerivedClass);
PrimaryBaseOffset =
MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
} else {
assert(Layout.getBaseClassOffset(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);
}
void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base,
uint64_t VBaseOffset) {
const CXXRecordDecl *RD = Base.getBase();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
// Handle the primary base first.
if (PrimaryBase) {
uint64_t PrimaryBaseOffset;
// Get the base offset of the primary base.
if (Layout.getPrimaryBaseWasVirtual()) {
assert(Layout.getVBaseClassOffset(PrimaryBase) == 0 &&
"Primary vbase should have a zero offset!");
const ASTRecordLayout &MostDerivedClassLayout =
Context.getASTRecordLayout(MostDerivedClass);
PrimaryBaseOffset =
MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
} else {
assert(Layout.getBaseClassOffset(PrimaryBase) == 0 &&
"Primary base should have a zero offset!");
PrimaryBaseOffset = Base.getBaseOffset();
}
AddVCallOffsets(BaseSubobject(PrimaryBase, PrimaryBaseOffset),
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;
// OffsetIndex is the index of this vcall 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());
// FIXME: We shouldn't use / 8 here.
int64_t OffsetOffset = OffsetIndex *
(int64_t)Context.Target.getPointerWidth(0) / 8;
// Don't add a vcall offset if we already have one for this member function
// signature.
if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset))
continue;
int64_t Offset = 0;
if (Overriders) {
// Get the final overrider.
FinalOverriders::OverriderInfo Overrider =
Overriders->getOverrider(Base, MD);
/// The vcall offset is the offset from the virtual base to the object
/// where the function was overridden.
// FIXME: We should not use / 8 here.
Offset = (int64_t)(Overrider.Offset - VBaseOffset) / 8;
}
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.
uint64_t BaseOffset = Base.getBaseOffset() +
Layout.getBaseClassOffset(BaseDecl);
AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset), VBaseOffset);
}
}
void VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
uint64_t 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)) {
// FIXME: We shouldn't use / 8 here.
int64_t Offset =
(int64_t)(LayoutClassLayout.getVBaseClassOffset(BaseDecl) -
OffsetInLayoutClass) / 8;
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;
private:
/// VtableInfo - Global vtable information.
CGVtableInfo &VtableInfo;
/// 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 uint64_t 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;
/// Components - The components of the vtable being built.
llvm::SmallVector<VtableComponent, 64> Components;
/// AddressPoints - Address points for the vtable being built.
CGVtableInfo::AddressPointsMapTy AddressPoints;
/// ReturnAdjustment - A return adjustment.
struct ReturnAdjustment {
/// NonVirtual - The non-virtual adjustment from the derived object to its
/// nearest virtual base.
int64_t NonVirtual;
/// VBaseOffsetOffset - The offset (in bytes), relative to the address point
/// of the virtual base class offset.
int64_t VBaseOffsetOffset;
ReturnAdjustment() : NonVirtual(0), VBaseOffsetOffset(0) { }
bool isEmpty() const { return !NonVirtual && !VBaseOffsetOffset; }
};
/// ReturnAdjustments - The return adjustments needed in this vtable.
llvm::SmallVector<std::pair<uint64_t, ReturnAdjustment>, 16>
ReturnAdjustments;
/// 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 uint64_t BaseOffset;
/// 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(uint64_t BaseOffset, uint64_t VtableIndex)
: BaseOffset(BaseOffset), VtableIndex(VtableIndex) { }
MethodInfo() : BaseOffset(0), VtableIndex(0) { }
};
typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
/// MethodInfoMap - The information for all methods in the vtable we're
/// currently building.
MethodInfoMapTy MethodInfoMap;
/// ThisAdjustment - A 'this' pointer adjustment thunk.
struct ThisAdjustment {
/// NonVirtual - The non-virtual adjustment from the derived object to its
/// nearest virtual base.
int64_t NonVirtual;
/// VCallOffsetOffset - The offset (in bytes), relative to the address point,
/// of the virtual call offset.
int64_t VCallOffsetOffset;
ThisAdjustment() : NonVirtual(0), VCallOffsetOffset(0) { }
bool isEmpty() const { return !NonVirtual && !VCallOffsetOffset; }
};
/// ThisAdjustments - The 'this' pointer adjustments needed in this vtable.
llvm::SmallVector<std::pair<uint64_t, ThisAdjustment>, 16>
ThisAdjustments;
/// 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 and the 'this' pointer adjustment base
/// offset.
ThisAdjustment ComputeThisAdjustment(const CXXMethodDecl *MD,
BaseOffset Offset);
/// 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(BaseSubobject Base,
BaseSubobject FirstBaseInPrimaryBaseChain,
uint64_t OffsetInLayoutClass,
FinalOverriders::OverriderInfo Overrider) const;
/// AddMethods - Add the methods of this base subobject and all its
/// primary bases to the vtable components vector.
void AddMethods(BaseSubobject Base, BaseSubobject FirstBaseInPrimaryBaseChain,
uint64_t OffsetInLayoutClass,
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.
void LayoutPrimaryAndSecondaryVtables(BaseSubobject Base,
bool BaseIsVirtual,
uint64_t OffsetInLayoutClass);
/// LayoutSecondaryVtables - Layout the secondary vtables for the given base
/// subobject.
void LayoutSecondaryVtables(BaseSubobject Base, uint64_t OffsetInLayoutClass);
/// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this
/// class hierarchy.
void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
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(CGVtableInfo &VtableInfo, const CXXRecordDecl *MostDerivedClass,
uint64_t MostDerivedClassOffset, bool MostDerivedClassIsVirtual,
const CXXRecordDecl *LayoutClass)
: VtableInfo(VtableInfo), MostDerivedClass(MostDerivedClass),
MostDerivedClassOffset(MostDerivedClassOffset),
MostDerivedClassIsVirtual(MostDerivedClassIsVirtual),
LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
Overriders(MostDerivedClass) {
LayoutVtable();
}
/// dumpLayout - Dump the vtable layout.
void dumpLayout(llvm::raw_ostream&);
};
/// OverridesMethodInBases - Checks whether whether this virtual member
/// function overrides a member function in any of the given bases.
/// Returns the overridden member function, or null if none was found.
static const CXXMethodDecl *
OverridesMethodInBases(const CXXMethodDecl *MD,
VtableBuilder::PrimaryBasesSetVectorTy &Bases) {
for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(),
E = MD->end_overridden_methods(); I != E; ++I) {
const CXXMethodDecl *OverriddenMD = *I;
const CXXRecordDecl *OverriddenRD = OverriddenMD->getParent();
assert(OverriddenMD->isCanonicalDecl() &&
"Should have the canonical decl of the overridden RD!");
if (Bases.count(OverriddenRD))
return OverriddenMD;
}
return 0;
}
void VtableBuilder::ComputeThisAdjustments() {
std::map<uint64_t, ThisAdjustment> SortedThisAdjustments;
// 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;
BaseSubobject OverriddenBaseSubobject(MD->getParent(),
MethodInfo.BaseOffset);
// Get the final overrider for this method.
FinalOverriders::OverriderInfo Overrider =
Overriders.getOverrider(OverriddenBaseSubobject, MD);
// Check if we need an adjustment.
if (Overrider.Offset == (int64_t)MethodInfo.BaseOffset)
continue;
uint64_t VtableIndex = MethodInfo.VtableIndex;
// Ignore adjustments for pure virtual member functions.
if (Overrider.Method->isPure())
continue;
// Ignore adjustments for unused function pointers.
if (Components[VtableIndex].getKind() ==
VtableComponent::CK_UnusedFunctionPointer)
continue;
BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(),
Overrider.Offset);
// Compute the adjustment offset.
BaseOffset ThisAdjustmentOffset =
ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject,
OverriderBaseSubobject);
// Then compute the adjustment itself.
ThisAdjustment ThisAdjustment = ComputeThisAdjustment(Overrider.Method,
ThisAdjustmentOffset);
// Add it.
SortedThisAdjustments.insert(std::make_pair(VtableIndex, ThisAdjustment));
if (isa<CXXDestructorDecl>(MD)) {
// Add an adjustment for the deleting destructor as well.
SortedThisAdjustments.insert(std::make_pair(VtableIndex + 1,
ThisAdjustment));
}
}
/// Clear the method info map.
MethodInfoMap.clear();
// Add the sorted elements.
ThisAdjustments.append(SortedThisAdjustments.begin(),
SortedThisAdjustments.end());
}
VtableBuilder::ReturnAdjustment
VtableBuilder::ComputeReturnAdjustment(BaseOffset Offset) {
ReturnAdjustment Adjustment;
if (!Offset.isEmpty()) {
if (Offset.VirtualBase) {
// Get the virtual base offset offset.
Adjustment.VBaseOffsetOffset =
VtableInfo.getVirtualBaseOffsetIndex(Offset.DerivedClass,
Offset.VirtualBase);
// FIXME: Once the assert in getVirtualBaseOffsetIndex is back again,
// we can get rid of this assert.
assert(Adjustment.VBaseOffsetOffset != 0 &&
"Invalid base offset offset!");
}
Adjustment.NonVirtual = Offset.NonVirtualOffset;
}
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);
// FIXME: Should not use * 8 here.
uint64_t OffsetToBaseSubobject = Offset.NonVirtualOffset * 8;
if (Offset.VirtualBase) {
// If we have a virtual base class, the non-virtual offset is relative
// to the virtual base class offset.
const ASTRecordLayout &MostDerivedClassLayout =
Context.getASTRecordLayout(MostDerivedClass);
/// Get the virtual base offset, relative to the most derived class
/// layout.
OffsetToBaseSubobject +=
MostDerivedClassLayout.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();
}
VtableBuilder::ThisAdjustment
VtableBuilder::ComputeThisAdjustment(const CXXMethodDecl *MD,
BaseOffset Offset) {
ThisAdjustment Adjustment;
if (!Offset.isEmpty()) {
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, 0),
/*BaseIsVirtual=*/true,
/*OffsetInLayoutClass=*/0);
VCallOffsets = Builder.getVCallOffsets();
}
Adjustment.VCallOffsetOffset = VCallOffsets.getVCallOffsetOffset(MD);
}
Adjustment.NonVirtual = Offset.NonVirtualOffset;
}
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())
ReturnAdjustments.push_back(std::make_pair(Components.size(),
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) {
for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(),
E = MD->end_overridden_methods(); I != E; ++I) {
const CXXMethodDecl *OverriddenMD = *I;
const CXXRecordDecl *OverriddenRD = OverriddenMD->getParent();
assert(OverriddenMD->isCanonicalDecl() &&
"Should have the canonical decl of the overridden RD!");
if (Bases.count(OverriddenRD))
return true;
// Check "indirect overriders".
if (OverridesIndirectMethodInBases(OverriddenMD, Bases))
return true;
}
return false;
}
bool
VtableBuilder::IsOverriderUsed(BaseSubobject Base,
BaseSubobject FirstBaseInPrimaryBaseChain,
uint64_t OffsetInLayoutClass,
FinalOverriders::OverriderInfo Overrider) const {
// If the base and the first base in the primary base chain have the same
// offsets, then this overrider will be used.
if (Base.getBaseOffset() == OffsetInLayoutClass)
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.Method->getParent() == FirstBaseInPrimaryBaseChain.getBase())
return true;
VtableBuilder::PrimaryBasesSetVectorTy PrimaryBases;
const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain.getBase();
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.getPrimaryBaseWasVirtual()) {
assert(Layout.getVBaseClassOffset(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) !=
OffsetInLayoutClass) {
// We found it, stop walking the chain.
break;
}
} else {
assert(Layout.getBaseClassOffset(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.Method, 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) {
for (int I = Bases.size(), E = 0; I != E; --I) {
const CXXRecordDecl *PrimaryBase = Bases[I - 1];
// Now check the overriden methods.
for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(),
E = MD->end_overridden_methods(); 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,
BaseSubobject FirstBaseInPrimaryBaseChain,
uint64_t OffsetInLayoutClass,
PrimaryBasesSetVectorTy &PrimaryBases) {
const CXXRecordDecl *RD = Base.getBase();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
uint64_t BaseOffset;
if (Layout.getPrimaryBaseWasVirtual()) {
assert(Layout.getVBaseClassOffset(PrimaryBase) == 0 &&
"Primary vbase should have a zero offset!");
const ASTRecordLayout &MostDerivedClassLayout =
Context.getASTRecordLayout(MostDerivedClass);
BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
} else {
assert(Layout.getBaseClassOffset(PrimaryBase) == 0 &&
"Primary base should have a zero offset!");
BaseOffset = Base.getBaseOffset();
}
// FIXME: OffsetInLayoutClass is not right here.
AddMethods(BaseSubobject(PrimaryBase, BaseOffset),
FirstBaseInPrimaryBaseChain, OffsetInLayoutClass, 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(Base, MD);
// 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(),
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);
continue;
}
}
// Insert the method info for this method.
MethodInfo MethodInfo(Base.getBaseOffset(), 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.
if (!IsOverriderUsed(Base, FirstBaseInPrimaryBaseChain, OffsetInLayoutClass,
Overrider)) {
const CXXMethodDecl *OverriderMD = Overrider.Method;
Components.push_back(VtableComponent::MakeUnusedFunction(OverriderMD));
continue;
}
// Check if this overrider needs a return adjustment.
BaseOffset ReturnAdjustmentOffset =
Overriders.getReturnAdjustmentOffset(Base, MD);
ReturnAdjustment ReturnAdjustment =
ComputeReturnAdjustment(ReturnAdjustmentOffset);
AddMethod(Overrider.Method, ReturnAdjustment);
}
}
void VtableBuilder::LayoutVtable() {
LayoutPrimaryAndSecondaryVtables(BaseSubobject(MostDerivedClass, 0),
MostDerivedClassIsVirtual,
MostDerivedClassOffset);
VisitedVirtualBasesSetTy VBases;
// Determine the primary virtual bases.
DeterminePrimaryVirtualBases(MostDerivedClass, VBases);
VBases.clear();
LayoutVtablesForVirtualBases(MostDerivedClass, VBases);
}
void
VtableBuilder::LayoutPrimaryAndSecondaryVtables(BaseSubobject Base,
bool BaseIsVirtual,
uint64_t 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, BaseIsVirtual, OffsetInLayoutClass);
Components.append(Builder.components_begin(), Builder.components_end());
// Check if we need to add these vcall offsets.
if (BaseIsVirtual && !Builder.getVCallOffsets().empty()) {
VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()];
if (VCallOffsets.empty())
VCallOffsets = Builder.getVCallOffsets();
}
// Add the offset to top.
// FIXME: We should not use / 8 here.
int64_t OffsetToTop = -(int64_t)(OffsetInLayoutClass -
MostDerivedClassOffset) / 8;
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, Base, OffsetInLayoutClass, PrimaryBases);
// Compute 'this' pointer adjustments.
ComputeThisAdjustments();
// Record the address point.
AddressPoints.insert(std::make_pair(BaseSubobject(Base.getBase(),
OffsetInLayoutClass),
AddressPoint));
// Record the address points for all primary bases.
for (PrimaryBasesSetVectorTy::const_iterator I = PrimaryBases.begin(),
E = PrimaryBases.end(); I != E; ++I) {
const CXXRecordDecl *BaseDecl = *I;
// We know that all the primary bases have the same offset as the base
// subobject.
BaseSubobject PrimaryBase(BaseDecl, OffsetInLayoutClass);
AddressPoints.insert(std::make_pair(PrimaryBase, AddressPoint));
}
// Layout secondary vtables.
LayoutSecondaryVtables(Base, OffsetInLayoutClass);
}
void VtableBuilder::LayoutSecondaryVtables(BaseSubobject Base,
uint64_t 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;
// Get the base offset of this base.
uint64_t RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl);
uint64_t BaseOffset = Base.getBaseOffset() + RelativeBaseOffset;
uint64_t 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),
BaseOffsetInLayoutClass);
continue;
}
// Layout the primary vtable (and any secondary vtables) for this base.
LayoutPrimaryAndSecondaryVtables(BaseSubobject(BaseDecl, BaseOffset),
/*BaseIsVirtual=*/false,
BaseOffsetInLayoutClass);
}
}
void
VtableBuilder::DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
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.getPrimaryBaseWasVirtual()) {
bool IsPrimaryVirtualBase = true;
if (isBuildingConstructorVtable()) {
// Check if the base is actually a primary base in the class we use for
// layout.
// FIXME: Is this check enough?
if (MostDerivedClassOffset != 0)
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());
if (I->isVirtual() && !VBases.insert(BaseDecl))
continue;
DeterminePrimaryVirtualBases(BaseDecl, 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);
uint64_t BaseOffset =
MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
const ASTRecordLayout &LayoutClassLayout =
Context.getASTRecordLayout(LayoutClass);
uint64_t BaseOffsetInLayoutClass =
LayoutClassLayout.getVBaseClassOffset(BaseDecl);
LayoutPrimaryAndSecondaryVtables(BaseSubobject(BaseDecl, BaseOffset),
/*BaseIsVirtual=*/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 (MostDerivedClass == LayoutClass) {
Out << "Vtable for '";
Out << MostDerivedClass->getQualifiedNameAsString();
} else {
Out << "Construction vtable for ('";
Out << MostDerivedClass->getQualifiedNameAsString() << "', ";
// FIXME: Don't use / 8 .
Out << MostDerivedClassOffset / 8 << ") in '";
Out << LayoutClass->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 (CGVtableInfo::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));
}
unsigned NextReturnAdjustmentIndex = 0;
unsigned NextThisAdjustmentIndex = 0;
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() << ")";
break;
case VtableComponent::CK_VBaseOffset:
Out << "vbase_offset (" << Component.getVBaseOffset() << ")";
break;
case VtableComponent::CK_OffsetToTop:
Out << "offset_to_top (" << Component.getOffsetToTop() << ")";
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]";
// If this function pointer has a return adjustment, dump it.
if (NextReturnAdjustmentIndex < ReturnAdjustments.size() &&
ReturnAdjustments[NextReturnAdjustmentIndex].first == I) {
const ReturnAdjustment Adjustment =
ReturnAdjustments[NextReturnAdjustmentIndex].second;
Out << "\n [return adjustment: ";
Out << Adjustment.NonVirtual << " non-virtual";
if (Adjustment.VBaseOffsetOffset)
Out << ", " << Adjustment.VBaseOffsetOffset << " vbase offset offset";
Out << ']';
NextReturnAdjustmentIndex++;
}
// If this function pointer has a 'this' pointer adjustment, dump it.
if (NextThisAdjustmentIndex < ThisAdjustments.size() &&
ThisAdjustments[NextThisAdjustmentIndex].first == I) {
const ThisAdjustment Adjustment =
ThisAdjustments[NextThisAdjustmentIndex].second;
Out << "\n [this adjustment: ";
Out << Adjustment.NonVirtual << " non-virtual";
if (Adjustment.VCallOffsetOffset)
Out << ", " << Adjustment.VCallOffsetOffset << " vcall offset offset";
Out << ']';
NextThisAdjustmentIndex++;
}
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]";
// If this destructor has a 'this' pointer adjustment, dump it.
if (NextThisAdjustmentIndex < ThisAdjustments.size() &&
ThisAdjustments[NextThisAdjustmentIndex].first == I) {
const ThisAdjustment Adjustment =
ThisAdjustments[NextThisAdjustmentIndex].second;
Out << "\n [this adjustment: ";
Out << Adjustment.NonVirtual << " non-virtual";
if (Adjustment.VCallOffsetOffset)
Out << ", " << Adjustment.VCallOffsetOffset << " vcall offset offset";
Out << ']';
NextThisAdjustmentIndex++;
}
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;
// FIXME: Instead of dividing by 8, we should be using CharUnits.
Out << " -- (" << Base.getBase()->getQualifiedNameAsString();
Out << ", " << Base.getBaseOffset() / 8 << ") vtable address --\n";
} else {
uint64_t 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) {
// FIXME: Instead of dividing by 8, we should be using CharUnits.
Out << " -- (" << *I;
Out << ", " << BaseOffset / 8 << ") vtable address --\n";
}
}
}
}
Out << '\n';
}
}
namespace {
class OldVtableBuilder {
public:
/// Index_t - Vtable index type.
typedef uint64_t Index_t;
typedef std::vector<std::pair<GlobalDecl,
std::pair<GlobalDecl, ThunkAdjustment> > >
SavedAdjustmentsVectorTy;
private:
// VtableComponents - The components of the vtable being built.
typedef llvm::SmallVector<llvm::Constant *, 64> VtableComponentsVectorTy;
VtableComponentsVectorTy VtableComponents;
const bool BuildVtable;
llvm::Type *Ptr8Ty;
/// MostDerivedClass - The most derived class that this vtable is being
/// built for.
const CXXRecordDecl *MostDerivedClass;
/// LayoutClass - The most derived class used for virtual base layout
/// information.
const CXXRecordDecl *LayoutClass;
/// LayoutOffset - The offset for Class in LayoutClass.
uint64_t LayoutOffset;
/// BLayout - Layout for the most derived class that this vtable is being
/// built for.
const ASTRecordLayout &BLayout;
llvm::SmallSet<const CXXRecordDecl *, 32> IndirectPrimary;
llvm::SmallSet<const CXXRecordDecl *, 32> SeenVBase;
llvm::Constant *rtti;
llvm::LLVMContext &VMContext;
CodeGenModule &CGM; // Per-module state.
llvm::DenseMap<const CXXMethodDecl *, Index_t> VCall;
llvm::DenseMap<GlobalDecl, Index_t> VCallOffset;
llvm::DenseMap<GlobalDecl, Index_t> VCallOffsetForVCall;
// This is the offset to the nearest virtual base
llvm::DenseMap<const CXXMethodDecl *, Index_t> NonVirtualOffset;
llvm::DenseMap<const CXXRecordDecl *, Index_t> VBIndex;
/// PureVirtualFunction - Points to __cxa_pure_virtual.
llvm::Constant *PureVirtualFn;
/// VtableMethods - A data structure for keeping track of methods in a vtable.
/// Can add methods, override methods and iterate in vtable order.
class VtableMethods {
// MethodToIndexMap - Maps from a global decl to the index it has in the
// Methods vector.
llvm::DenseMap<GlobalDecl, uint64_t> MethodToIndexMap;
/// Methods - The methods, in vtable order.
typedef llvm::SmallVector<GlobalDecl, 16> MethodsVectorTy;
MethodsVectorTy Methods;
MethodsVectorTy OrigMethods;
public:
/// AddMethod - Add a method to the vtable methods.
void AddMethod(GlobalDecl GD) {
assert(!MethodToIndexMap.count(GD) &&
"Method has already been added!");
MethodToIndexMap[GD] = Methods.size();
Methods.push_back(GD);
OrigMethods.push_back(GD);
}
/// OverrideMethod - Replace a method with another.
void OverrideMethod(GlobalDecl OverriddenGD, GlobalDecl GD) {
llvm::DenseMap<GlobalDecl, uint64_t>::iterator i
= MethodToIndexMap.find(OverriddenGD);
assert(i != MethodToIndexMap.end() && "Did not find entry!");
// Get the index of the old decl.
uint64_t Index = i->second;
// Replace the old decl with the new decl.
Methods[Index] = GD;
// And add the new.
MethodToIndexMap[GD] = Index;
}
/// getIndex - Gives the index of a passed in GlobalDecl. Returns false if
/// the index couldn't be found.
bool getIndex(GlobalDecl GD, uint64_t &Index) const {
llvm::DenseMap<GlobalDecl, uint64_t>::const_iterator i
= MethodToIndexMap.find(GD);
if (i == MethodToIndexMap.end())
return false;
Index = i->second;
return true;
}
GlobalDecl getOrigMethod(uint64_t Index) const {
return OrigMethods[Index];
}
MethodsVectorTy::size_type size() const {
return Methods.size();
}
void clear() {
MethodToIndexMap.clear();
Methods.clear();
OrigMethods.clear();
}
GlobalDecl operator[](uint64_t Index) const {
return Methods[Index];
}
};
/// Methods - The vtable methods we're currently building.
VtableMethods Methods;
/// ThisAdjustments - For a given index in the vtable, contains the 'this'
/// pointer adjustment needed for a method.
typedef llvm::DenseMap<uint64_t, ThunkAdjustment> ThisAdjustmentsMapTy;
ThisAdjustmentsMapTy ThisAdjustments;
SavedAdjustmentsVectorTy SavedAdjustments;
/// BaseReturnTypes - Contains the base return types of methods who have been
/// overridden with methods whose return types require adjustment. Used for
/// generating covariant thunk information.
typedef llvm::DenseMap<uint64_t, CanQualType> BaseReturnTypesMapTy;
BaseReturnTypesMapTy BaseReturnTypes;
std::vector<Index_t> VCalls;
typedef std::pair<const CXXRecordDecl *, uint64_t> CtorVtable_t;
// subAddressPoints - Used to hold the AddressPoints (offsets) into the built
// vtable for use in computing the initializers for the VTT.
llvm::DenseMap<CtorVtable_t, int64_t> &subAddressPoints;
/// AddressPoints - Address points for this vtable.
CGVtableInfo::AddressPointsMapTy& AddressPoints;
typedef CXXRecordDecl::method_iterator method_iter;
const uint32_t LLVMPointerWidth;
Index_t extra;
typedef std::vector<std::pair<const CXXRecordDecl *, int64_t> > Path_t;
static llvm::DenseMap<CtorVtable_t, int64_t>&
AllocAddressPoint(CodeGenModule &cgm, const CXXRecordDecl *l,
const CXXRecordDecl *c) {
CGVtableInfo::AddrMap_t *&oref = cgm.getVtableInfo().AddressPoints[l];
if (oref == 0)
oref = new CGVtableInfo::AddrMap_t;
llvm::DenseMap<CtorVtable_t, int64_t> *&ref = (*oref)[c];
if (ref == 0)
ref = new llvm::DenseMap<CtorVtable_t, int64_t>;
return *ref;
}
bool DclIsSame(const FunctionDecl *New, const FunctionDecl *Old) {
FunctionTemplateDecl *OldTemplate = Old->getDescribedFunctionTemplate();
FunctionTemplateDecl *NewTemplate = New->getDescribedFunctionTemplate();
// C++ [temp.fct]p2:
// A function template can be overloaded with other function templates
// and with normal (non-template) functions.
if ((OldTemplate == 0) != (NewTemplate == 0))
return false;
// Is the function New an overload of the function Old?
QualType OldQType = CGM.getContext().getCanonicalType(Old->getType());
QualType NewQType = CGM.getContext().getCanonicalType(New->getType());
// Compare the signatures (C++ 1.3.10) of the two functions to
// determine whether they are overloads. If we find any mismatch
// in the signature, they are overloads.
// If either of these functions is a K&R-style function (no
// prototype), then we consider them to have matching signatures.
if (isa<FunctionNoProtoType>(OldQType.getTypePtr()) ||
isa<FunctionNoProtoType>(NewQType.getTypePtr()))
return true;
FunctionProtoType* OldType = cast<FunctionProtoType>(OldQType);
FunctionProtoType* NewType = cast<FunctionProtoType>(NewQType);
// The signature of a function includes the types of its
// parameters (C++ 1.3.10), which includes the presence or absence
// of the ellipsis; see C++ DR 357).
if (OldQType != NewQType &&
(OldType->getNumArgs() != NewType->getNumArgs() ||
OldType->isVariadic() != NewType->isVariadic() ||
!std::equal(OldType->arg_type_begin(), OldType->arg_type_end(),
NewType->arg_type_begin())))
return false;
#if 0
// C++ [temp.over.link]p4:
// The signature of a function template consists of its function
// signature, its return type and its template parameter list. The names
// of the template parameters are significant only for establishing the
// relationship between the template parameters and the rest of the
// signature.
//
// We check the return type and template parameter lists for function
// templates first; the remaining checks follow.
if (NewTemplate &&
(!TemplateParameterListsAreEqual(NewTemplate->getTemplateParameters(),
OldTemplate->getTemplateParameters(),
TPL_TemplateMatch) ||
OldType->getResultType() != NewType->getResultType()))
return false;
#endif
// If the function is a class member, its signature includes the
// cv-qualifiers (if any) on the function itself.
//
// As part of this, also check whether one of the member functions
// is static, in which case they are not overloads (C++
// 13.1p2). While not part of the definition of the signature,
// this check is important to determine whether these functions
// can be overloaded.
const CXXMethodDecl* OldMethod = dyn_cast<CXXMethodDecl>(Old);
const CXXMethodDecl* NewMethod = dyn_cast<CXXMethodDecl>(New);
if (OldMethod && NewMethod &&
!OldMethod->isStatic() && !NewMethod->isStatic() &&
OldMethod->getTypeQualifiers() != NewMethod->getTypeQualifiers())
return false;
// The signatures match; this is not an overload.
return true;
}
typedef llvm::DenseMap<const CXXMethodDecl *, const CXXMethodDecl*>
ForwardUnique_t;
ForwardUnique_t ForwardUnique;
llvm::DenseMap<const CXXMethodDecl*, const CXXMethodDecl*> UniqueOverrider;
void BuildUniqueOverrider(const CXXMethodDecl *U, const CXXMethodDecl *MD) {
const CXXMethodDecl *PrevU = UniqueOverrider[MD];
assert(U && "no unique overrider");
if (PrevU == U)
return;
if (PrevU != U && PrevU != 0) {
// If already set, note the two sets as the same
if (0)
printf("%s::%s same as %s::%s\n",
PrevU->getParent()->getNameAsString().c_str(),
PrevU->getNameAsString().c_str(),
U->getParent()->getNameAsString().c_str(),
U->getNameAsString().c_str());
ForwardUnique[PrevU] = U;
return;
}
// Not set, set it now
if (0)
printf("marking %s::%s %p override as %s::%s\n",
MD->getParent()->getNameAsString().c_str(),
MD->getNameAsString().c_str(),
(void*)MD,
U->getParent()->getNameAsString().c_str(),
U->getNameAsString().c_str());
UniqueOverrider[MD] = U;
for (CXXMethodDecl::method_iterator mi = MD->begin_overridden_methods(),
me = MD->end_overridden_methods(); mi != me; ++mi) {
BuildUniqueOverrider(U, *mi);
}
}
void BuildUniqueOverriders(const CXXRecordDecl *RD) {
if (0) printf("walking %s\n", RD->getNameAsCString());
for (CXXRecordDecl::method_iterator i = RD->method_begin(),
e = RD->method_end(); i != e; ++i) {
const CXXMethodDecl *MD = *i;
if (!MD->isVirtual())
continue;
if (UniqueOverrider[MD] == 0) {
// Only set this, if it hasn't been set yet.
BuildUniqueOverrider(MD, MD);
if (0)
printf("top set is %s::%s %p\n",
MD->getParent()->getNameAsString().c_str(),
MD->getNameAsString().c_str(),
(void*)MD);
ForwardUnique[MD] = MD;
}
}
for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(),
e = RD->bases_end(); i != e; ++i) {
const CXXRecordDecl *Base =
cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
BuildUniqueOverriders(Base);
}
}
static int DclCmp(const void *p1, const void *p2) {
const CXXMethodDecl *MD1 = *(const CXXMethodDecl *const *)p1;
const CXXMethodDecl *MD2 = *(const CXXMethodDecl *const *)p2;
return (DeclarationName::compare(MD1->getDeclName(), MD2->getDeclName()));
}
void MergeForwarding() {
typedef llvm::SmallVector<const CXXMethodDecl *, 100> A_t;
A_t A;
for (ForwardUnique_t::iterator I = ForwardUnique.begin(),
E = ForwardUnique.end(); I != E; ++I) {
if (I->first == I->second)
// Only add the roots of all trees
A.push_back(I->first);
}
llvm::array_pod_sort(A.begin(), A.end(), DclCmp);
for (A_t::iterator I = A.begin(),
E = A.end(); I != E; ++I) {
A_t::iterator J = I;
while (++J != E && DclCmp(I, J) == 0)
if (DclIsSame(*I, *J)) {
if (0) printf("connecting %s\n", (*I)->getNameAsString().c_str());
ForwardUnique[*J] = *I;
}
}
}
const CXXMethodDecl *getUnique(const CXXMethodDecl *MD) {
const CXXMethodDecl *U = UniqueOverrider[MD];
assert(U && "unique overrider not found");
while (ForwardUnique.count(U)) {
const CXXMethodDecl *NU = ForwardUnique[U];
if (NU == U) break;
U = NU;
}
return U;
}
GlobalDecl getUnique(GlobalDecl GD) {
const CXXMethodDecl *Unique = getUnique(cast<CXXMethodDecl>(GD.getDecl()));
if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(Unique))
return GlobalDecl(CD, GD.getCtorType());
if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Unique))
return GlobalDecl(DD, GD.getDtorType());
return Unique;
}
/// getPureVirtualFn - Return the __cxa_pure_virtual function.
llvm::Constant* getPureVirtualFn() {
if (!PureVirtualFn) {
const llvm::FunctionType *Ty =
llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
/*isVarArg=*/false);
PureVirtualFn = wrap(CGM.CreateRuntimeFunction(Ty, "__cxa_pure_virtual"));
}
return PureVirtualFn;
}
public:
OldVtableBuilder(const CXXRecordDecl *MostDerivedClass,
const CXXRecordDecl *l, uint64_t lo, CodeGenModule &cgm,
bool build, CGVtableInfo::AddressPointsMapTy& AddressPoints)
: BuildVtable(build), MostDerivedClass(MostDerivedClass), LayoutClass(l),
LayoutOffset(lo), BLayout(cgm.getContext().getASTRecordLayout(l)),
rtti(0), VMContext(cgm.getModule().getContext()),CGM(cgm),
PureVirtualFn(0),
subAddressPoints(AllocAddressPoint(cgm, l, MostDerivedClass)),
AddressPoints(AddressPoints),
LLVMPointerWidth(cgm.getContext().Target.getPointerWidth(0))
{
Ptr8Ty = llvm::PointerType::get(llvm::Type::getInt8Ty(VMContext), 0);
if (BuildVtable) {
QualType ClassType = CGM.getContext().getTagDeclType(MostDerivedClass);
rtti = CGM.GetAddrOfRTTIDescriptor(ClassType);
}
BuildUniqueOverriders(MostDerivedClass);
MergeForwarding();
}
// getVtableComponents - Returns a reference to the vtable components.
const VtableComponentsVectorTy &getVtableComponents() const {
return VtableComponents;
}
llvm::DenseMap<const CXXRecordDecl *, uint64_t> &getVBIndex()
{ return VBIndex; }
SavedAdjustmentsVectorTy &getSavedAdjustments()
{ return SavedAdjustments; }
llvm::Constant *wrap(Index_t i) {
llvm::Constant *m;
m = llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext), i);
return llvm::ConstantExpr::getIntToPtr(m, Ptr8Ty);
}
llvm::Constant *wrap(llvm::Constant *m) {
return llvm::ConstantExpr::getBitCast(m, Ptr8Ty);
}
//#define D1(x)
#define D1(X) do { if (getenv("CLANG_VTABLE_DEBUG")) { X; } } while (0)
void GenerateVBaseOffsets(const CXXRecordDecl *RD, uint64_t Offset,
bool updateVBIndex, Index_t current_vbindex) {
for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(),
e = RD->bases_end(); i != e; ++i) {
const CXXRecordDecl *Base =
cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
Index_t next_vbindex = current_vbindex;
if (i->isVirtual() && !SeenVBase.count(Base)) {
SeenVBase.insert(Base);
if (updateVBIndex) {
next_vbindex = (ssize_t)(-(VCalls.size()*LLVMPointerWidth/8)
- 3*LLVMPointerWidth/8);
VBIndex[Base] = next_vbindex;
}
int64_t BaseOffset = -(Offset/8) + BLayout.getVBaseClassOffset(Base)/8;
VCalls.push_back((0?700:0) + BaseOffset);
D1(printf(" vbase for %s at %d delta %d most derived %s\n",
Base->getNameAsCString(),
(int)-VCalls.size()-3, (int)BaseOffset,
MostDerivedClass->getNameAsCString()));
}
// We also record offsets for non-virtual bases to closest enclosing
// virtual base. We do this so that we don't have to search
// for the nearst virtual base class when generating thunks.
if (updateVBIndex && VBIndex.count(Base) == 0)
VBIndex[Base] = next_vbindex;
GenerateVBaseOffsets(Base, Offset, updateVBIndex, next_vbindex);
}
}
void StartNewTable() {
SeenVBase.clear();
}
Index_t getNVOffset_1(const CXXRecordDecl *D, const CXXRecordDecl *B,
Index_t Offset = 0) {
if (B == D)
return Offset;
const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(D);
for (CXXRecordDecl::base_class_const_iterator i = D->bases_begin(),
e = D->bases_end(); i != e; ++i) {
const CXXRecordDecl *Base =
cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
int64_t BaseOffset = 0;
if (!i->isVirtual())
BaseOffset = Offset + Layout.getBaseClassOffset(Base);
int64_t o = getNVOffset_1(Base, B, BaseOffset);
if (o >= 0)
return o;
}
return -1;
}
/// getNVOffset - Returns the non-virtual offset for the given (B) base of the
/// derived class D.
Index_t getNVOffset(QualType qB, QualType qD) {
qD = qD->getPointeeType();
qB = qB->getPointeeType();
CXXRecordDecl *D = cast<CXXRecordDecl>(qD->getAs<RecordType>()->getDecl());
CXXRecordDecl *B = cast<CXXRecordDecl>(qB->getAs<RecordType>()->getDecl());
int64_t o = getNVOffset_1(D, B);
if (o >= 0)
return o;
assert(false && "FIXME: non-virtual base not found");
return 0;
}
/// getVbaseOffset - Returns the index into the vtable for the virtual base
/// offset for the given (B) virtual base of the derived class D.
Index_t getVbaseOffset(QualType qB, QualType qD) {
qD = qD->getPointeeType();
qB = qB->getPointeeType();
CXXRecordDecl *D = cast<CXXRecordDecl>(qD->getAs<RecordType>()->getDecl());
CXXRecordDecl *B = cast<CXXRecordDecl>(qB->getAs<RecordType>()->getDecl());
if (D != MostDerivedClass)
return CGM.getVtableInfo().getVirtualBaseOffsetIndex(D, B);
llvm::DenseMap<const CXXRecordDecl *, Index_t>::iterator i;
i = VBIndex.find(B);
if (i != VBIndex.end())
return i->second;
assert(false && "FIXME: Base not found");
return 0;
}
bool OverrideMethod(GlobalDecl GD, bool MorallyVirtual,
Index_t OverrideOffset, Index_t Offset,
int64_t CurrentVBaseOffset);
/// AppendMethods - Append the current methods to the vtable.
void AppendMethodsToVtable();
llvm::Constant *WrapAddrOf(GlobalDecl GD) {
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
const llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVtable(MD);
return wrap(CGM.GetAddrOfFunction(GD, Ty));
}
void OverrideMethods(Path_t *Path, bool MorallyVirtual, int64_t Offset,
int64_t CurrentVBaseOffset) {
for (Path_t::reverse_iterator i = Path->rbegin(),
e = Path->rend(); i != e; ++i) {
const CXXRecordDecl *RD = i->first;
int64_t OverrideOff