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

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//===--- CGClass.cpp - Emit LLVM Code for C++ classes ---------------------===//
//
// 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 classes
//
//===----------------------------------------------------------------------===//
#include "CGDebugInfo.h"
#include "CodeGenFunction.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Frontend/CodeGenOptions.h"
using namespace clang;
using namespace CodeGen;
static CharUnits
ComputeNonVirtualBaseClassOffset(ASTContext &Context,
const CXXRecordDecl *DerivedClass,
CastExpr::path_const_iterator Start,
CastExpr::path_const_iterator End) {
CharUnits Offset = CharUnits::Zero();
const CXXRecordDecl *RD = DerivedClass;
for (CastExpr::path_const_iterator I = Start; I != End; ++I) {
const CXXBaseSpecifier *Base = *I;
assert(!Base->isVirtual() && "Should not see virtual bases here!");
// Get the layout.
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(Base->getType()->getAs<RecordType>()->getDecl());
// Add the offset.
Offset += Layout.getBaseClassOffset(BaseDecl);
RD = BaseDecl;
}
return Offset;
}
llvm::Constant *
CodeGenModule::GetNonVirtualBaseClassOffset(const CXXRecordDecl *ClassDecl,
CastExpr::path_const_iterator PathBegin,
CastExpr::path_const_iterator PathEnd) {
assert(PathBegin != PathEnd && "Base path should not be empty!");
CharUnits Offset =
ComputeNonVirtualBaseClassOffset(getContext(), ClassDecl,
PathBegin, PathEnd);
if (Offset.isZero())
return 0;
llvm::Type *PtrDiffTy =
Types.ConvertType(getContext().getPointerDiffType());
return llvm::ConstantInt::get(PtrDiffTy, Offset.getQuantity());
}
/// Gets the address of a direct base class within a complete object.
/// This should only be used for (1) non-virtual bases or (2) virtual bases
/// when the type is known to be complete (e.g. in complete destructors).
///
/// The object pointed to by 'This' is assumed to be non-null.
llvm::Value *
CodeGenFunction::GetAddressOfDirectBaseInCompleteClass(llvm::Value *This,
const CXXRecordDecl *Derived,
const CXXRecordDecl *Base,
bool BaseIsVirtual) {
// 'this' must be a pointer (in some address space) to Derived.
assert(This->getType()->isPointerTy() &&
cast<llvm::PointerType>(This->getType())->getElementType()
== ConvertType(Derived));
// Compute the offset of the virtual base.
CharUnits Offset;
const ASTRecordLayout &Layout = getContext().getASTRecordLayout(Derived);
if (BaseIsVirtual)
Offset = Layout.getVBaseClassOffset(Base);
else
Offset = Layout.getBaseClassOffset(Base);
// Shift and cast down to the base type.
// TODO: for complete types, this should be possible with a GEP.
llvm::Value *V = This;
if (Offset.isPositive()) {
llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
V = Builder.CreateBitCast(V, Int8PtrTy);
V = Builder.CreateConstInBoundsGEP1_64(V, Offset.getQuantity());
}
V = Builder.CreateBitCast(V, ConvertType(Base)->getPointerTo());
return V;
}
static llvm::Value *
ApplyNonVirtualAndVirtualOffset(CodeGenFunction &CGF, llvm::Value *ThisPtr,
CharUnits NonVirtual, llvm::Value *Virtual) {
llvm::Type *PtrDiffTy =
CGF.ConvertType(CGF.getContext().getPointerDiffType());
llvm::Value *NonVirtualOffset = 0;
if (!NonVirtual.isZero())
NonVirtualOffset = llvm::ConstantInt::get(PtrDiffTy,
NonVirtual.getQuantity());
llvm::Value *BaseOffset;
if (Virtual) {
if (NonVirtualOffset)
BaseOffset = CGF.Builder.CreateAdd(Virtual, NonVirtualOffset);
else
BaseOffset = Virtual;
} else
BaseOffset = NonVirtualOffset;
// Apply the base offset.
llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
ThisPtr = CGF.Builder.CreateBitCast(ThisPtr, Int8PtrTy);
ThisPtr = CGF.Builder.CreateGEP(ThisPtr, BaseOffset, "add.ptr");
return ThisPtr;
}
llvm::Value *
CodeGenFunction::GetAddressOfBaseClass(llvm::Value *Value,
const CXXRecordDecl *Derived,
CastExpr::path_const_iterator PathBegin,
CastExpr::path_const_iterator PathEnd,
bool NullCheckValue) {
assert(PathBegin != PathEnd && "Base path should not be empty!");
CastExpr::path_const_iterator Start = PathBegin;
const CXXRecordDecl *VBase = 0;
// Get the virtual base.
if ((*Start)->isVirtual()) {
VBase =
cast<CXXRecordDecl>((*Start)->getType()->getAs<RecordType>()->getDecl());
++Start;
}
CharUnits NonVirtualOffset =
ComputeNonVirtualBaseClassOffset(getContext(), VBase ? VBase : Derived,
Start, PathEnd);
// Get the base pointer type.
llvm::Type *BasePtrTy =
ConvertType((PathEnd[-1])->getType())->getPointerTo();
if (NonVirtualOffset.isZero() && !VBase) {
// Just cast back.
return Builder.CreateBitCast(Value, BasePtrTy);
}
llvm::BasicBlock *CastNull = 0;
llvm::BasicBlock *CastNotNull = 0;
llvm::BasicBlock *CastEnd = 0;
if (NullCheckValue) {
CastNull = createBasicBlock("cast.null");
CastNotNull = createBasicBlock("cast.notnull");
CastEnd = createBasicBlock("cast.end");
llvm::Value *IsNull = Builder.CreateIsNull(Value);
Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
EmitBlock(CastNotNull);
}
llvm::Value *VirtualOffset = 0;
if (VBase) {
if (Derived->hasAttr<FinalAttr>()) {
VirtualOffset = 0;
const ASTRecordLayout &Layout = getContext().getASTRecordLayout(Derived);
CharUnits VBaseOffset = Layout.getVBaseClassOffset(VBase);
NonVirtualOffset += VBaseOffset;
} else
VirtualOffset = GetVirtualBaseClassOffset(Value, Derived, VBase);
}
// Apply the offsets.
Value = ApplyNonVirtualAndVirtualOffset(*this, Value,
NonVirtualOffset,
VirtualOffset);
// Cast back.
Value = Builder.CreateBitCast(Value, BasePtrTy);
if (NullCheckValue) {
Builder.CreateBr(CastEnd);
EmitBlock(CastNull);
Builder.CreateBr(CastEnd);
EmitBlock(CastEnd);
llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2);
PHI->addIncoming(Value, CastNotNull);
PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()),
CastNull);
Value = PHI;
}
return Value;
}
llvm::Value *
CodeGenFunction::GetAddressOfDerivedClass(llvm::Value *Value,
const CXXRecordDecl *Derived,
CastExpr::path_const_iterator PathBegin,
CastExpr::path_const_iterator PathEnd,
bool NullCheckValue) {
assert(PathBegin != PathEnd && "Base path should not be empty!");
QualType DerivedTy =
getContext().getCanonicalType(getContext().getTagDeclType(Derived));
llvm::Type *DerivedPtrTy = ConvertType(DerivedTy)->getPointerTo();
llvm::Value *NonVirtualOffset =
CGM.GetNonVirtualBaseClassOffset(Derived, PathBegin, PathEnd);
if (!NonVirtualOffset) {
// No offset, we can just cast back.
return Builder.CreateBitCast(Value, DerivedPtrTy);
}
llvm::BasicBlock *CastNull = 0;
llvm::BasicBlock *CastNotNull = 0;
llvm::BasicBlock *CastEnd = 0;
if (NullCheckValue) {
CastNull = createBasicBlock("cast.null");
CastNotNull = createBasicBlock("cast.notnull");
CastEnd = createBasicBlock("cast.end");
llvm::Value *IsNull = Builder.CreateIsNull(Value);
Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
EmitBlock(CastNotNull);
}
// Apply the offset.
Value = Builder.CreatePtrToInt(Value, NonVirtualOffset->getType());
Value = Builder.CreateSub(Value, NonVirtualOffset);
Value = Builder.CreateIntToPtr(Value, DerivedPtrTy);
// Just cast.
Value = Builder.CreateBitCast(Value, DerivedPtrTy);
if (NullCheckValue) {
Builder.CreateBr(CastEnd);
EmitBlock(CastNull);
Builder.CreateBr(CastEnd);
EmitBlock(CastEnd);
llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2);
PHI->addIncoming(Value, CastNotNull);
PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()),
CastNull);
Value = PHI;
}
return Value;
}
/// GetVTTParameter - Return the VTT parameter that should be passed to a
/// base constructor/destructor with virtual bases.
static llvm::Value *GetVTTParameter(CodeGenFunction &CGF, GlobalDecl GD,
bool ForVirtualBase) {
if (!CodeGenVTables::needsVTTParameter(GD)) {
// This constructor/destructor does not need a VTT parameter.
return 0;
}
const CXXRecordDecl *RD = cast<CXXMethodDecl>(CGF.CurFuncDecl)->getParent();
const CXXRecordDecl *Base = cast<CXXMethodDecl>(GD.getDecl())->getParent();
llvm::Value *VTT;
uint64_t SubVTTIndex;
// If the record matches the base, this is the complete ctor/dtor
// variant calling the base variant in a class with virtual bases.
if (RD == Base) {
assert(!CodeGenVTables::needsVTTParameter(CGF.CurGD) &&
"doing no-op VTT offset in base dtor/ctor?");
assert(!ForVirtualBase && "Can't have same class as virtual base!");
SubVTTIndex = 0;
} else {
const ASTRecordLayout &Layout =
CGF.getContext().getASTRecordLayout(RD);
CharUnits BaseOffset = ForVirtualBase ?
Layout.getVBaseClassOffset(Base) :
Layout.getBaseClassOffset(Base);
SubVTTIndex =
CGF.CGM.getVTables().getSubVTTIndex(RD, BaseSubobject(Base, BaseOffset));
assert(SubVTTIndex != 0 && "Sub-VTT index must be greater than zero!");
}
if (CodeGenVTables::needsVTTParameter(CGF.CurGD)) {
// A VTT parameter was passed to the constructor, use it.
VTT = CGF.LoadCXXVTT();
VTT = CGF.Builder.CreateConstInBoundsGEP1_64(VTT, SubVTTIndex);
} else {
// We're the complete constructor, so get the VTT by name.
VTT = CGF.CGM.getVTables().GetAddrOfVTT(RD);
VTT = CGF.Builder.CreateConstInBoundsGEP2_64(VTT, 0, SubVTTIndex);
}
return VTT;
}
namespace {
/// Call the destructor for a direct base class.
struct CallBaseDtor : EHScopeStack::Cleanup {
const CXXRecordDecl *BaseClass;
bool BaseIsVirtual;
CallBaseDtor(const CXXRecordDecl *Base, bool BaseIsVirtual)
: BaseClass(Base), BaseIsVirtual(BaseIsVirtual) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
const CXXRecordDecl *DerivedClass =
cast<CXXMethodDecl>(CGF.CurCodeDecl)->getParent();
const CXXDestructorDecl *D = BaseClass->getDestructor();
llvm::Value *Addr =
CGF.GetAddressOfDirectBaseInCompleteClass(CGF.LoadCXXThis(),
DerivedClass, BaseClass,
BaseIsVirtual);
CGF.EmitCXXDestructorCall(D, Dtor_Base, BaseIsVirtual, Addr);
}
};
/// A visitor which checks whether an initializer uses 'this' in a
/// way which requires the vtable to be properly set.
struct DynamicThisUseChecker : EvaluatedExprVisitor<DynamicThisUseChecker> {
typedef EvaluatedExprVisitor<DynamicThisUseChecker> super;
bool UsesThis;
DynamicThisUseChecker(ASTContext &C) : super(C), UsesThis(false) {}
// Black-list all explicit and implicit references to 'this'.
//
// Do we need to worry about external references to 'this' derived
// from arbitrary code? If so, then anything which runs arbitrary
// external code might potentially access the vtable.
void VisitCXXThisExpr(CXXThisExpr *E) { UsesThis = true; }
};
}
static bool BaseInitializerUsesThis(ASTContext &C, const Expr *Init) {
DynamicThisUseChecker Checker(C);
Checker.Visit(const_cast<Expr*>(Init));
return Checker.UsesThis;
}
static void EmitBaseInitializer(CodeGenFunction &CGF,
const CXXRecordDecl *ClassDecl,
CXXCtorInitializer *BaseInit,
CXXCtorType CtorType) {
assert(BaseInit->isBaseInitializer() &&
"Must have base initializer!");
llvm::Value *ThisPtr = CGF.LoadCXXThis();
const Type *BaseType = BaseInit->getBaseClass();
CXXRecordDecl *BaseClassDecl =
cast<CXXRecordDecl>(BaseType->getAs<RecordType>()->getDecl());
bool isBaseVirtual = BaseInit->isBaseVirtual();
// The base constructor doesn't construct virtual bases.
if (CtorType == Ctor_Base && isBaseVirtual)
return;
// If the initializer for the base (other than the constructor
// itself) accesses 'this' in any way, we need to initialize the
// vtables.
if (BaseInitializerUsesThis(CGF.getContext(), BaseInit->getInit()))
CGF.InitializeVTablePointers(ClassDecl);
// We can pretend to be a complete class because it only matters for
// virtual bases, and we only do virtual bases for complete ctors.
llvm::Value *V =
CGF.GetAddressOfDirectBaseInCompleteClass(ThisPtr, ClassDecl,
BaseClassDecl,
isBaseVirtual);
AggValueSlot AggSlot =
AggValueSlot::forAddr(V, Qualifiers(),
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased);
CGF.EmitAggExpr(BaseInit->getInit(), AggSlot);
if (CGF.CGM.getLangOptions().Exceptions &&
!BaseClassDecl->hasTrivialDestructor())
CGF.EHStack.pushCleanup<CallBaseDtor>(EHCleanup, BaseClassDecl,
isBaseVirtual);
}
static void EmitAggMemberInitializer(CodeGenFunction &CGF,
LValue LHS,
llvm::Value *ArrayIndexVar,
CXXCtorInitializer *MemberInit,
QualType T,
unsigned Index) {
if (Index == MemberInit->getNumArrayIndices()) {
CodeGenFunction::RunCleanupsScope Cleanups(CGF);
llvm::Value *Dest = LHS.getAddress();
if (ArrayIndexVar) {
// If we have an array index variable, load it and use it as an offset.
// Then, increment the value.
llvm::Value *ArrayIndex = CGF.Builder.CreateLoad(ArrayIndexVar);
Dest = CGF.Builder.CreateInBoundsGEP(Dest, ArrayIndex, "destaddress");
llvm::Value *Next = llvm::ConstantInt::get(ArrayIndex->getType(), 1);
Next = CGF.Builder.CreateAdd(ArrayIndex, Next, "inc");
CGF.Builder.CreateStore(Next, ArrayIndexVar);
}
if (!CGF.hasAggregateLLVMType(T)) {
LValue lvalue = CGF.MakeAddrLValue(Dest, T);
CGF.EmitScalarInit(MemberInit->getInit(), /*decl*/ 0, lvalue, false);
} else if (T->isAnyComplexType()) {
CGF.EmitComplexExprIntoAddr(MemberInit->getInit(), Dest,
LHS.isVolatileQualified());
} else {
AggValueSlot Slot =
AggValueSlot::forAddr(Dest, LHS.getQuals(),
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased);
CGF.EmitAggExpr(MemberInit->getInit(), Slot);
}
return;
}
const ConstantArrayType *Array = CGF.getContext().getAsConstantArrayType(T);
assert(Array && "Array initialization without the array type?");
llvm::Value *IndexVar
= CGF.GetAddrOfLocalVar(MemberInit->getArrayIndex(Index));
assert(IndexVar && "Array index variable not loaded");
// Initialize this index variable to zero.
llvm::Value* Zero
= llvm::Constant::getNullValue(
CGF.ConvertType(CGF.getContext().getSizeType()));
CGF.Builder.CreateStore(Zero, IndexVar);
// Start the loop with a block that tests the condition.
llvm::BasicBlock *CondBlock = CGF.createBasicBlock("for.cond");
llvm::BasicBlock *AfterFor = CGF.createBasicBlock("for.end");
CGF.EmitBlock(CondBlock);
llvm::BasicBlock *ForBody = CGF.createBasicBlock("for.body");
// Generate: if (loop-index < number-of-elements) fall to the loop body,
// otherwise, go to the block after the for-loop.
uint64_t NumElements = Array->getSize().getZExtValue();
llvm::Value *Counter = CGF.Builder.CreateLoad(IndexVar);
llvm::Value *NumElementsPtr =
llvm::ConstantInt::get(Counter->getType(), NumElements);
llvm::Value *IsLess = CGF.Builder.CreateICmpULT(Counter, NumElementsPtr,
"isless");
// If the condition is true, execute the body.
CGF.Builder.CreateCondBr(IsLess, ForBody, AfterFor);
CGF.EmitBlock(ForBody);
llvm::BasicBlock *ContinueBlock = CGF.createBasicBlock("for.inc");
{
CodeGenFunction::RunCleanupsScope Cleanups(CGF);
// Inside the loop body recurse to emit the inner loop or, eventually, the
// constructor call.
EmitAggMemberInitializer(CGF, LHS, ArrayIndexVar, MemberInit,
Array->getElementType(), Index + 1);
}
CGF.EmitBlock(ContinueBlock);
// Emit the increment of the loop counter.
llvm::Value *NextVal = llvm::ConstantInt::get(Counter->getType(), 1);
Counter = CGF.Builder.CreateLoad(IndexVar);
NextVal = CGF.Builder.CreateAdd(Counter, NextVal, "inc");
CGF.Builder.CreateStore(NextVal, IndexVar);
// Finally, branch back up to the condition for the next iteration.
CGF.EmitBranch(CondBlock);
// Emit the fall-through block.
CGF.EmitBlock(AfterFor, true);
}
namespace {
struct CallMemberDtor : EHScopeStack::Cleanup {
FieldDecl *Field;
CXXDestructorDecl *Dtor;
CallMemberDtor(FieldDecl *Field, CXXDestructorDecl *Dtor)
: Field(Field), Dtor(Dtor) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
// FIXME: Is this OK for C++0x delegating constructors?
llvm::Value *ThisPtr = CGF.LoadCXXThis();
LValue LHS = CGF.EmitLValueForField(ThisPtr, Field, 0);
CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false,
LHS.getAddress());
}
};
}
static bool hasTrivialCopyOrMoveConstructor(const CXXRecordDecl *Record,
bool Moving) {
return Moving ? Record->hasTrivialMoveConstructor() :
Record->hasTrivialCopyConstructor();
}
static void EmitMemberInitializer(CodeGenFunction &CGF,
const CXXRecordDecl *ClassDecl,
CXXCtorInitializer *MemberInit,
const CXXConstructorDecl *Constructor,
FunctionArgList &Args) {
assert(MemberInit->isAnyMemberInitializer() &&
"Must have member initializer!");
assert(MemberInit->getInit() && "Must have initializer!");
// non-static data member initializers.
FieldDecl *Field = MemberInit->getAnyMember();
QualType FieldType = CGF.getContext().getCanonicalType(Field->getType());
llvm::Value *ThisPtr = CGF.LoadCXXThis();
LValue LHS;
// If we are initializing an anonymous union field, drill down to the field.
if (MemberInit->isIndirectMemberInitializer()) {
LHS = CGF.EmitLValueForAnonRecordField(ThisPtr,
MemberInit->getIndirectMember(), 0);
FieldType = MemberInit->getIndirectMember()->getAnonField()->getType();
} else {
LHS = CGF.EmitLValueForFieldInitialization(ThisPtr, Field, 0);
}
if (!CGF.hasAggregateLLVMType(Field->getType())) {
if (LHS.isSimple()) {
CGF.EmitExprAsInit(MemberInit->getInit(), Field, LHS, false);
} else {
RValue RHS = RValue::get(CGF.EmitScalarExpr(MemberInit->getInit()));
CGF.EmitStoreThroughLValue(RHS, LHS);
}
} else if (MemberInit->getInit()->getType()->isAnyComplexType()) {
CGF.EmitComplexExprIntoAddr(MemberInit->getInit(), LHS.getAddress(),
LHS.isVolatileQualified());
} else {
llvm::Value *ArrayIndexVar = 0;
const ConstantArrayType *Array
= CGF.getContext().getAsConstantArrayType(FieldType);
if (Array && Constructor->isImplicitlyDefined() &&
Constructor->isCopyOrMoveConstructor()) {
llvm::Type *SizeTy
= CGF.ConvertType(CGF.getContext().getSizeType());
// The LHS is a pointer to the first object we'll be constructing, as
// a flat array.
QualType BaseElementTy = CGF.getContext().getBaseElementType(Array);
llvm::Type *BasePtr = CGF.ConvertType(BaseElementTy);
BasePtr = llvm::PointerType::getUnqual(BasePtr);
llvm::Value *BaseAddrPtr = CGF.Builder.CreateBitCast(LHS.getAddress(),
BasePtr);
LHS = CGF.MakeAddrLValue(BaseAddrPtr, BaseElementTy);
// Create an array index that will be used to walk over all of the
// objects we're constructing.
ArrayIndexVar = CGF.CreateTempAlloca(SizeTy, "object.index");
llvm::Value *Zero = llvm::Constant::getNullValue(SizeTy);
CGF.Builder.CreateStore(Zero, ArrayIndexVar);
// If we are copying an array of PODs or classes with trivial copy
// constructors, perform a single aggregate copy.
const CXXRecordDecl *Record = BaseElementTy->getAsCXXRecordDecl();
if (BaseElementTy.isPODType(CGF.getContext()) ||
(Record && hasTrivialCopyOrMoveConstructor(Record,
Constructor->isMoveConstructor()))) {
// Find the source pointer. We knows it's the last argument because
// we know we're in a copy constructor.
unsigned SrcArgIndex = Args.size() - 1;
llvm::Value *SrcPtr
= CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(Args[SrcArgIndex]));
LValue Src = CGF.EmitLValueForFieldInitialization(SrcPtr, Field, 0);
// Copy the aggregate.
CGF.EmitAggregateCopy(LHS.getAddress(), Src.getAddress(), FieldType,
LHS.isVolatileQualified());
return;
}
// Emit the block variables for the array indices, if any.
for (unsigned I = 0, N = MemberInit->getNumArrayIndices(); I != N; ++I)
CGF.EmitAutoVarDecl(*MemberInit->getArrayIndex(I));
}
EmitAggMemberInitializer(CGF, LHS, ArrayIndexVar, MemberInit, FieldType, 0);
if (!CGF.CGM.getLangOptions().Exceptions)
return;
// FIXME: If we have an array of classes w/ non-trivial destructors,
// we need to destroy in reverse order of construction along the exception
// path.
const RecordType *RT = FieldType->getAs<RecordType>();
if (!RT)
return;
CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
if (!RD->hasTrivialDestructor())
CGF.EHStack.pushCleanup<CallMemberDtor>(EHCleanup, Field,
RD->getDestructor());
}
}
/// Checks whether the given constructor is a valid subject for the
/// complete-to-base constructor delegation optimization, i.e.
/// emitting the complete constructor as a simple call to the base
/// constructor.
static bool IsConstructorDelegationValid(const CXXConstructorDecl *Ctor) {
// Currently we disable the optimization for classes with virtual
// bases because (1) the addresses of parameter variables need to be
// consistent across all initializers but (2) the delegate function
// call necessarily creates a second copy of the parameter variable.
//
// The limiting example (purely theoretical AFAIK):
// struct A { A(int &c) { c++; } };
// struct B : virtual A {
// B(int count) : A(count) { printf("%d\n", count); }
// };
// ...although even this example could in principle be emitted as a
// delegation since the address of the parameter doesn't escape.
if (Ctor->getParent()->getNumVBases()) {
// TODO: white-list trivial vbase initializers. This case wouldn't
// be subject to the restrictions below.
// TODO: white-list cases where:
// - there are no non-reference parameters to the constructor
// - the initializers don't access any non-reference parameters
// - the initializers don't take the address of non-reference
// parameters
// - etc.
// If we ever add any of the above cases, remember that:
// - function-try-blocks will always blacklist this optimization
// - we need to perform the constructor prologue and cleanup in
// EmitConstructorBody.
return false;
}
// We also disable the optimization for variadic functions because
// it's impossible to "re-pass" varargs.
if (Ctor->getType()->getAs<FunctionProtoType>()->isVariadic())
return false;
// FIXME: Decide if we can do a delegation of a delegating constructor.
if (Ctor->isDelegatingConstructor())
return false;
return true;
}
/// EmitConstructorBody - Emits the body of the current constructor.
void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
const CXXConstructorDecl *Ctor = cast<CXXConstructorDecl>(CurGD.getDecl());
CXXCtorType CtorType = CurGD.getCtorType();
// Before we go any further, try the complete->base constructor
// delegation optimization.
if (CtorType == Ctor_Complete && IsConstructorDelegationValid(Ctor)) {
if (CGDebugInfo *DI = getDebugInfo())
DI->EmitLocation(Builder, Ctor->getLocEnd());
EmitDelegateCXXConstructorCall(Ctor, Ctor_Base, Args);
return;
}
Stmt *Body = Ctor->getBody();
// Enter the function-try-block before the constructor prologue if
// applicable.
bool IsTryBody = (Body && isa<CXXTryStmt>(Body));
if (IsTryBody)
EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
EHScopeStack::stable_iterator CleanupDepth = EHStack.stable_begin();
// Emit the constructor prologue, i.e. the base and member
// initializers.
EmitCtorPrologue(Ctor, CtorType, Args);
// Emit the body of the statement.
if (IsTryBody)
EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
else if (Body)
EmitStmt(Body);
// Emit any cleanup blocks associated with the member or base
// initializers, which includes (along the exceptional path) the
// destructors for those members and bases that were fully
// constructed.
PopCleanupBlocks(CleanupDepth);
if (IsTryBody)
ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
}
/// EmitCtorPrologue - This routine generates necessary code to initialize
/// base classes and non-static data members belonging to this constructor.
void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
CXXCtorType CtorType,
FunctionArgList &Args) {
if (CD->isDelegatingConstructor())
return EmitDelegatingCXXConstructorCall(CD, Args);
const CXXRecordDecl *ClassDecl = CD->getParent();
SmallVector<CXXCtorInitializer *, 8> MemberInitializers;
for (CXXConstructorDecl::init_const_iterator B = CD->init_begin(),
E = CD->init_end();
B != E; ++B) {
CXXCtorInitializer *Member = (*B);
if (Member->isBaseInitializer()) {
EmitBaseInitializer(*this, ClassDecl, Member, CtorType);
} else {
assert(Member->isAnyMemberInitializer() &&
"Delegating initializer on non-delegating constructor");
MemberInitializers.push_back(Member);
}
}
InitializeVTablePointers(ClassDecl);
for (unsigned I = 0, E = MemberInitializers.size(); I != E; ++I)
EmitMemberInitializer(*this, ClassDecl, MemberInitializers[I], CD, Args);
}
static bool
FieldHasTrivialDestructorBody(ASTContext &Context, const FieldDecl *Field);
static bool
HasTrivialDestructorBody(ASTContext &Context,
const CXXRecordDecl *BaseClassDecl,
const CXXRecordDecl *MostDerivedClassDecl)
{
// If the destructor is trivial we don't have to check anything else.
if (BaseClassDecl->hasTrivialDestructor())
return true;
if (!BaseClassDecl->getDestructor()->hasTrivialBody())
return false;
// Check fields.
for (CXXRecordDecl::field_iterator I = BaseClassDecl->field_begin(),
E = BaseClassDecl->field_end(); I != E; ++I) {
const FieldDecl *Field = *I;
if (!FieldHasTrivialDestructorBody(Context, Field))
return false;
}
// Check non-virtual bases.
for (CXXRecordDecl::base_class_const_iterator I =
BaseClassDecl->bases_begin(), E = BaseClassDecl->bases_end();
I != E; ++I) {
if (I->isVirtual())
continue;
const CXXRecordDecl *NonVirtualBase =
cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
if (!HasTrivialDestructorBody(Context, NonVirtualBase,
MostDerivedClassDecl))
return false;
}
if (BaseClassDecl == MostDerivedClassDecl) {
// Check virtual bases.
for (CXXRecordDecl::base_class_const_iterator I =
BaseClassDecl->vbases_begin(), E = BaseClassDecl->vbases_end();
I != E; ++I) {
const CXXRecordDecl *VirtualBase =
cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
if (!HasTrivialDestructorBody(Context, VirtualBase,
MostDerivedClassDecl))
return false;
}
}
return true;
}
static bool
FieldHasTrivialDestructorBody(ASTContext &Context,
const FieldDecl *Field)
{
QualType FieldBaseElementType = Context.getBaseElementType(Field->getType());
const RecordType *RT = FieldBaseElementType->getAs<RecordType>();
if (!RT)
return true;
CXXRecordDecl *FieldClassDecl = cast<CXXRecordDecl>(RT->getDecl());
return HasTrivialDestructorBody(Context, FieldClassDecl, FieldClassDecl);
}
/// CanSkipVTablePointerInitialization - Check whether we need to initialize
/// any vtable pointers before calling this destructor.
static bool CanSkipVTablePointerInitialization(ASTContext &Context,
const CXXDestructorDecl *Dtor) {
if (!Dtor->hasTrivialBody())
return false;
// Check the fields.
const CXXRecordDecl *ClassDecl = Dtor->getParent();
for (CXXRecordDecl::field_iterator I = ClassDecl->field_begin(),
E = ClassDecl->field_end(); I != E; ++I) {
const FieldDecl *Field = *I;
if (!FieldHasTrivialDestructorBody(Context, Field))
return false;
}
return true;
}
/// EmitDestructorBody - Emits the body of the current destructor.
void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CurGD.getDecl());
CXXDtorType DtorType = CurGD.getDtorType();
// The call to operator delete in a deleting destructor happens
// outside of the function-try-block, which means it's always
// possible to delegate the destructor body to the complete
// destructor. Do so.
if (DtorType == Dtor_Deleting) {
EnterDtorCleanups(Dtor, Dtor_Deleting);
EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false,
LoadCXXThis());
PopCleanupBlock();
return;
}
Stmt *Body = Dtor->getBody();
// If the body is a function-try-block, enter the try before
// anything else.
bool isTryBody = (Body && isa<CXXTryStmt>(Body));
if (isTryBody)
EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
// Enter the epilogue cleanups.
RunCleanupsScope DtorEpilogue(*this);
// If this is the complete variant, just invoke the base variant;
// the epilogue will destruct the virtual bases. But we can't do
// this optimization if the body is a function-try-block, because
// we'd introduce *two* handler blocks.
switch (DtorType) {
case Dtor_Deleting: llvm_unreachable("already handled deleting case");
case Dtor_Complete:
// Enter the cleanup scopes for virtual bases.
EnterDtorCleanups(Dtor, Dtor_Complete);
if (!isTryBody) {
EmitCXXDestructorCall(Dtor, Dtor_Base, /*ForVirtualBase=*/false,
LoadCXXThis());
break;
}
// Fallthrough: act like we're in the base variant.
case Dtor_Base:
// Enter the cleanup scopes for fields and non-virtual bases.
EnterDtorCleanups(Dtor, Dtor_Base);
// Initialize the vtable pointers before entering the body.
if (!CanSkipVTablePointerInitialization(getContext(), Dtor))
InitializeVTablePointers(Dtor->getParent());
if (isTryBody)
EmitStmt(cast<CXXTryStmt>(Body)->getTryBlock());
else if (Body)
EmitStmt(Body);
else {
assert(Dtor->isImplicit() && "bodyless dtor not implicit");
// nothing to do besides what's in the epilogue
}
// -fapple-kext must inline any call to this dtor into
// the caller's body.
if (getContext().getLangOptions().AppleKext)
CurFn->addFnAttr(llvm::Attribute::AlwaysInline);
break;
}
// Jump out through the epilogue cleanups.
DtorEpilogue.ForceCleanup();
// Exit the try if applicable.
if (isTryBody)
ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
}
namespace {
/// Call the operator delete associated with the current destructor.
struct CallDtorDelete : EHScopeStack::Cleanup {
CallDtorDelete() {}
void Emit(CodeGenFunction &CGF, Flags flags) {
const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
const CXXRecordDecl *ClassDecl = Dtor->getParent();
CGF.EmitDeleteCall(Dtor->getOperatorDelete(), CGF.LoadCXXThis(),
CGF.getContext().getTagDeclType(ClassDecl));
}
};
class DestroyField : public EHScopeStack::Cleanup {
const FieldDecl *field;
CodeGenFunction::Destroyer &destroyer;
bool useEHCleanupForArray;
public:
DestroyField(const FieldDecl *field, CodeGenFunction::Destroyer *destroyer,
bool useEHCleanupForArray)
: field(field), destroyer(*destroyer),
useEHCleanupForArray(useEHCleanupForArray) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
// Find the address of the field.
llvm::Value *thisValue = CGF.LoadCXXThis();
LValue LV = CGF.EmitLValueForField(thisValue, field, /*CVRQualifiers=*/0);
assert(LV.isSimple());
CGF.emitDestroy(LV.getAddress(), field->getType(), destroyer,
flags.isForNormalCleanup() && useEHCleanupForArray);
}
};
}
/// EmitDtorEpilogue - Emit all code that comes at the end of class's
/// destructor. This is to call destructors on members and base classes
/// in reverse order of their construction.
void CodeGenFunction::EnterDtorCleanups(const CXXDestructorDecl *DD,
CXXDtorType DtorType) {
assert(!DD->isTrivial() &&
"Should not emit dtor epilogue for trivial dtor!");
// The deleting-destructor phase just needs to call the appropriate
// operator delete that Sema picked up.
if (DtorType == Dtor_Deleting) {
assert(DD->getOperatorDelete() &&
"operator delete missing - EmitDtorEpilogue");
EHStack.pushCleanup<CallDtorDelete>(NormalAndEHCleanup);
return;
}
const CXXRecordDecl *ClassDecl = DD->getParent();
// Unions have no bases and do not call field destructors.
if (ClassDecl->isUnion())
return;
// The complete-destructor phase just destructs all the virtual bases.
if (DtorType == Dtor_Complete) {
// We push them in the forward order so that they'll be popped in
// the reverse order.
for (CXXRecordDecl::base_class_const_iterator I =
ClassDecl->vbases_begin(), E = ClassDecl->vbases_end();
I != E; ++I) {
const CXXBaseSpecifier &Base = *I;
CXXRecordDecl *BaseClassDecl
= cast<CXXRecordDecl>(Base.getType()->getAs<RecordType>()->getDecl());
// Ignore trivial destructors.
if (BaseClassDecl->hasTrivialDestructor())
continue;
EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
BaseClassDecl,
/*BaseIsVirtual*/ true);
}
return;
}
assert(DtorType == Dtor_Base);
// Destroy non-virtual bases.
for (CXXRecordDecl::base_class_const_iterator I =
ClassDecl->bases_begin(), E = ClassDecl->bases_end(); I != E; ++I) {
const CXXBaseSpecifier &Base = *I;
// Ignore virtual bases.
if (Base.isVirtual())
continue;
CXXRecordDecl *BaseClassDecl = Base.getType()->getAsCXXRecordDecl();
// Ignore trivial destructors.
if (BaseClassDecl->hasTrivialDestructor())
continue;
EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup,
BaseClassDecl,
/*BaseIsVirtual*/ false);
}
// Destroy direct fields.
SmallVector<const FieldDecl *, 16> FieldDecls;
for (CXXRecordDecl::field_iterator I = ClassDecl->field_begin(),
E = ClassDecl->field_end(); I != E; ++I) {
const FieldDecl *field = *I;
QualType type = field->getType();
QualType::DestructionKind dtorKind = type.isDestructedType();
if (!dtorKind) continue;
CleanupKind cleanupKind = getCleanupKind(dtorKind);
EHStack.pushCleanup<DestroyField>(cleanupKind, field,
getDestroyer(dtorKind),
cleanupKind & EHCleanup);
}
}
/// EmitCXXAggrConstructorCall - Emit a loop to call a particular
/// constructor for each of several members of an array.
///
/// \param ctor the constructor to call for each element
/// \param argBegin,argEnd the arguments to evaluate and pass to the
/// constructor
/// \param arrayType the type of the array to initialize
/// \param arrayBegin an arrayType*
/// \param zeroInitialize true if each element should be
/// zero-initialized before it is constructed
void
CodeGenFunction::EmitCXXAggrConstructorCall(const CXXConstructorDecl *ctor,
const ConstantArrayType *arrayType,
llvm::Value *arrayBegin,
CallExpr::const_arg_iterator argBegin,
CallExpr::const_arg_iterator argEnd,
bool zeroInitialize) {
QualType elementType;
llvm::Value *numElements =
emitArrayLength(arrayType, elementType, arrayBegin);
EmitCXXAggrConstructorCall(ctor, numElements, arrayBegin,
argBegin, argEnd, zeroInitialize);
}
/// EmitCXXAggrConstructorCall - Emit a loop to call a particular
/// constructor for each of several members of an array.
///
/// \param ctor the constructor to call for each element
/// \param numElements the number of elements in the array;
/// may be zero
/// \param argBegin,argEnd the arguments to evaluate and pass to the
/// constructor
/// \param arrayBegin a T*, where T is the type constructed by ctor
/// \param zeroInitialize true if each element should be
/// zero-initialized before it is constructed
void
CodeGenFunction::EmitCXXAggrConstructorCall(const CXXConstructorDecl *ctor,
llvm::Value *numElements,
llvm::Value *arrayBegin,
CallExpr::const_arg_iterator argBegin,
CallExpr::const_arg_iterator argEnd,
bool zeroInitialize) {
// It's legal for numElements to be zero. This can happen both
// dynamically, because x can be zero in 'new A[x]', and statically,
// because of GCC extensions that permit zero-length arrays. There
// are probably legitimate places where we could assume that this
// doesn't happen, but it's not clear that it's worth it.
llvm::BranchInst *zeroCheckBranch = 0;
// Optimize for a constant count.
llvm::ConstantInt *constantCount
= dyn_cast<llvm::ConstantInt>(numElements);
if (constantCount) {
// Just skip out if the constant count is zero.
if (constantCount->isZero()) return;
// Otherwise, emit the check.
} else {
llvm::BasicBlock *loopBB = createBasicBlock("new.ctorloop");
llvm::Value *iszero = Builder.CreateIsNull(numElements, "isempty");
zeroCheckBranch = Builder.CreateCondBr(iszero, loopBB, loopBB);
EmitBlock(loopBB);
}
// Find the end of the array.
llvm::Value *arrayEnd = Builder.CreateInBoundsGEP(arrayBegin, numElements,
"arrayctor.end");
// Enter the loop, setting up a phi for the current location to initialize.
llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
llvm::BasicBlock *loopBB = createBasicBlock("arrayctor.loop");
EmitBlock(loopBB);
llvm::PHINode *cur = Builder.CreatePHI(arrayBegin->getType(), 2,
"arrayctor.cur");
cur->addIncoming(arrayBegin, entryBB);
// Inside the loop body, emit the constructor call on the array element.
QualType type = getContext().getTypeDeclType(ctor->getParent());
// Zero initialize the storage, if requested.
if (zeroInitialize)
EmitNullInitialization(cur, type);
// C++ [class.temporary]p4:
// There are two contexts in which temporaries are destroyed at a different
// point than the end of the full-expression. The first context is when a
// default constructor is called to initialize an element of an array.
// If the constructor has one or more default arguments, the destruction of
// every temporary created in a default argument expression is sequenced
// before the construction of the next array element, if any.
{
RunCleanupsScope Scope(*this);
// Evaluate the constructor and its arguments in a regular
// partial-destroy cleanup.
if (getLangOptions().Exceptions &&
!ctor->getParent()->hasTrivialDestructor()) {
Destroyer *destroyer = destroyCXXObject;
pushRegularPartialArrayCleanup(arrayBegin, cur, type, *destroyer);
}
EmitCXXConstructorCall(ctor, Ctor_Complete, /*ForVirtualBase=*/ false,
cur, argBegin, argEnd);
}
// Go to the next element.
llvm::Value *next =
Builder.CreateInBoundsGEP(cur, llvm::ConstantInt::get(SizeTy, 1),
"arrayctor.next");
cur->addIncoming(next, Builder.GetInsertBlock());
// Check whether that's the end of the loop.
llvm::Value *done = Builder.CreateICmpEQ(next, arrayEnd, "arrayctor.done");
llvm::BasicBlock *contBB = createBasicBlock("arrayctor.cont");
Builder.CreateCondBr(done, contBB, loopBB);
// Patch the earlier check to skip over the loop.
if (zeroCheckBranch) zeroCheckBranch->setSuccessor(0, contBB);
EmitBlock(contBB);
}
void CodeGenFunction::destroyCXXObject(CodeGenFunction &CGF,
llvm::Value *addr,
QualType type) {
const RecordType *rtype = type->castAs<RecordType>();
const CXXRecordDecl *record = cast<CXXRecordDecl>(rtype->getDecl());
const CXXDestructorDecl *dtor = record->getDestructor();
assert(!dtor->isTrivial());
CGF.EmitCXXDestructorCall(dtor, Dtor_Complete, /*for vbase*/ false,
addr);
}
void
CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
CXXCtorType Type, bool ForVirtualBase,
llvm::Value *This,
CallExpr::const_arg_iterator ArgBeg,
CallExpr::const_arg_iterator ArgEnd) {
CGDebugInfo *DI = getDebugInfo();
if (DI && CGM.getCodeGenOpts().LimitDebugInfo) {
// If debug info for this class has been emitted then this is the right time
// to do so.
const CXXRecordDecl *Parent = D->getParent();
DI->getOrCreateRecordType(CGM.getContext().getTypeDeclType(Parent),
Parent->getLocation());
}
if (D->isTrivial()) {
if (ArgBeg == ArgEnd) {
// Trivial default constructor, no codegen required.
assert(D->isDefaultConstructor() &&
"trivial 0-arg ctor not a default ctor");
return;
}
assert(ArgBeg + 1 == ArgEnd && "unexpected argcount for trivial ctor");
assert(D->isCopyOrMoveConstructor() &&
"trivial 1-arg ctor not a copy/move ctor");
const Expr *E = (*ArgBeg);
QualType Ty = E->getType();
llvm::Value *Src = EmitLValue(E).getAddress();
EmitAggregateCopy(This, Src, Ty);
return;
}
llvm::Value *VTT = GetVTTParameter(*this, GlobalDecl(D, Type), ForVirtualBase);
llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D, Type);
EmitCXXMemberCall(D, Callee, ReturnValueSlot(), This, VTT, ArgBeg, ArgEnd);
}
void
CodeGenFunction::EmitSynthesizedCXXCopyCtorCall(const CXXConstructorDecl *D,
llvm::Value *This, llvm::Value *Src,
CallExpr::const_arg_iterator ArgBeg,
CallExpr::const_arg_iterator ArgEnd) {
if (D->isTrivial()) {
assert(ArgBeg + 1 == ArgEnd && "unexpected argcount for trivial ctor");
assert(D->isCopyOrMoveConstructor() &&
"trivial 1-arg ctor not a copy/move ctor");
EmitAggregateCopy(This, Src, (*ArgBeg)->getType());
return;
}
llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D,
clang::Ctor_Complete);
assert(D->isInstance() &&
"Trying to emit a member call expr on a static method!");
const FunctionProtoType *FPT = D->getType()->getAs<FunctionProtoType>();
CallArgList Args;
// Push the this ptr.
Args.add(RValue::get(This), D->getThisType(getContext()));
// Push the src ptr.
QualType QT = *(FPT->arg_type_begin());
llvm::Type *t = CGM.getTypes().ConvertType(QT);
Src = Builder.CreateBitCast(Src, t);
Args.add(RValue::get(Src), QT);
// Skip over first argument (Src).
++ArgBeg;
CallExpr::const_arg_iterator Arg = ArgBeg;
for (FunctionProtoType::arg_type_iterator I = FPT->arg_type_begin()+1,
E = FPT->arg_type_end(); I != E; ++I, ++Arg) {
assert(Arg != ArgEnd && "Running over edge of argument list!");
EmitCallArg(Args, *Arg, *I);
}
// Either we've emitted all the call args, or we have a call to a
// variadic function.
assert((Arg == ArgEnd || FPT->isVariadic()) &&
"Extra arguments in non-variadic function!");
// If we still have any arguments, emit them using the type of the argument.
for (; Arg != ArgEnd; ++Arg) {
QualType ArgType = Arg->getType();
EmitCallArg(Args, *Arg, ArgType);
}
EmitCall(CGM.getTypes().getFunctionInfo(Args, FPT), Callee,
ReturnValueSlot(), Args, D);
}
void
CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
CXXCtorType CtorType,
const FunctionArgList &Args) {
CallArgList DelegateArgs;
FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
assert(I != E && "no parameters to constructor");
// this
DelegateArgs.add(RValue::get(LoadCXXThis()), (*I)->getType());
++I;
// vtt
if (llvm::Value *VTT = GetVTTParameter(*this, GlobalDecl(Ctor, CtorType),
/*ForVirtualBase=*/false)) {
QualType VoidPP = getContext().getPointerType(getContext().VoidPtrTy);
DelegateArgs.add(RValue::get(VTT), VoidPP);
if (CodeGenVTables::needsVTTParameter(CurGD)) {
assert(I != E && "cannot skip vtt parameter, already done with args");
assert((*I)->getType() == VoidPP && "skipping parameter not of vtt type");
++I;
}
}
// Explicit arguments.
for (; I != E; ++I) {
const VarDecl *param = *I;
EmitDelegateCallArg(DelegateArgs, param);
}
EmitCall(CGM.getTypes().getFunctionInfo(Ctor, CtorType),
CGM.GetAddrOfCXXConstructor(Ctor, CtorType),
ReturnValueSlot(), DelegateArgs, Ctor);
}
namespace {
struct CallDelegatingCtorDtor : EHScopeStack::Cleanup {
const CXXDestructorDecl *Dtor;
llvm::Value *Addr;
CXXDtorType Type;
CallDelegatingCtorDtor(const CXXDestructorDecl *D, llvm::Value *Addr,
CXXDtorType Type)
: Dtor(D), Addr(Addr), Type(Type) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
CGF.EmitCXXDestructorCall(Dtor, Type, /*ForVirtualBase=*/false,
Addr);
}
};
}
void
CodeGenFunction::EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
const FunctionArgList &Args) {
assert(Ctor->isDelegatingConstructor());
llvm::Value *ThisPtr = LoadCXXThis();
AggValueSlot AggSlot =
AggValueSlot::forAddr(ThisPtr, Qualifiers(),
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased);
EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);
const CXXRecordDecl *ClassDecl = Ctor->getParent();
if (CGM.getLangOptions().Exceptions && !ClassDecl->hasTrivialDestructor()) {
CXXDtorType Type =
CurGD.getCtorType() == Ctor_Complete ? Dtor_Complete : Dtor_Base;
EHStack.pushCleanup<CallDelegatingCtorDtor>(EHCleanup,
ClassDecl->getDestructor(),
ThisPtr, Type);
}
}
void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *DD,
CXXDtorType Type,
bool ForVirtualBase,
llvm::Value *This) {
llvm::Value *VTT = GetVTTParameter(*this, GlobalDecl(DD, Type),
ForVirtualBase);
llvm::Value *Callee = 0;
if (getContext().getLangOptions().AppleKext)
Callee = BuildAppleKextVirtualDestructorCall(DD, Type,
DD->getParent());
if (!Callee)
Callee = CGM.GetAddrOfCXXDestructor(DD, Type);
EmitCXXMemberCall(DD, Callee, ReturnValueSlot(), This, VTT, 0, 0);
}
namespace {
struct CallLocalDtor : EHScopeStack::Cleanup {
const CXXDestructorDecl *Dtor;
llvm::Value *Addr;
CallLocalDtor(const CXXDestructorDecl *D, llvm::Value *Addr)
: Dtor(D), Addr(Addr) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
/*ForVirtualBase=*/false, Addr);
}
};
}
void CodeGenFunction::PushDestructorCleanup(const CXXDestructorDecl *D,
llvm::Value *Addr) {
EHStack.pushCleanup<CallLocalDtor>(NormalAndEHCleanup, D, Addr);
}
void CodeGenFunction::PushDestructorCleanup(QualType T, llvm::Value *Addr) {
CXXRecordDecl *ClassDecl = T->getAsCXXRecordDecl();
if (!ClassDecl) return;
if (ClassDecl->hasTrivialDestructor()) return;
const CXXDestructorDecl *D = ClassDecl->getDestructor();
assert(D && D->isUsed() && "destructor not marked as used!");
PushDestructorCleanup(D, Addr);
}
llvm::Value *
CodeGenFunction::GetVirtualBaseClassOffset(llvm::Value *This,
const CXXRecordDecl *ClassDecl,
const CXXRecordDecl *BaseClassDecl) {
llvm::Value *VTablePtr = GetVTablePtr(This, Int8PtrTy);
CharUnits VBaseOffsetOffset =
CGM.getVTableContext().getVirtualBaseOffsetOffset(ClassDecl, BaseClassDecl);
llvm::Value *VBaseOffsetPtr =
Builder.CreateConstGEP1_64(VTablePtr, VBaseOffsetOffset.getQuantity(),
"vbase.offset.ptr");
llvm::Type *PtrDiffTy =
ConvertType(getContext().getPointerDiffType());
VBaseOffsetPtr = Builder.CreateBitCast(VBaseOffsetPtr,
PtrDiffTy->getPointerTo());
llvm::Value *VBaseOffset = Builder.CreateLoad(VBaseOffsetPtr, "vbase.offset");
return VBaseOffset;
}
void
CodeGenFunction::InitializeVTablePointer(BaseSubobject Base,
const CXXRecordDecl *NearestVBase,
CharUnits OffsetFromNearestVBase,
llvm::Constant *VTable,
const CXXRecordDecl *VTableClass) {
const CXXRecordDecl *RD = Base.getBase();
// Compute the address point.
llvm::Value *VTableAddressPoint;
// Check if we need to use a vtable from the VTT.
if (CodeGenVTables::needsVTTParameter(CurGD) &&
(RD->getNumVBases() || NearestVBase)) {
// Get the secondary vpointer index.
uint64_t VirtualPointerIndex =
CGM.getVTables().getSecondaryVirtualPointerIndex(VTableClass, Base);
/// Load the VTT.
llvm::Value *VTT = LoadCXXVTT();
if (VirtualPointerIndex)
VTT = Builder.CreateConstInBoundsGEP1_64(VTT, VirtualPointerIndex);
// And load the address point from the VTT.
VTableAddressPoint = Builder.CreateLoad(VTT);
} else {
uint64_t AddressPoint =
CGM.getVTableContext().getVTableLayout(VTableClass).getAddressPoint(Base);
VTableAddressPoint =
Builder.CreateConstInBoundsGEP2_64(VTable, 0, AddressPoint);
}
// Compute where to store the address point.
llvm::Value *VirtualOffset = 0;
CharUnits NonVirtualOffset = CharUnits::Zero();
if (CodeGenVTables::needsVTTParameter(CurGD) && NearestVBase) {
// We need to use the virtual base offset offset because the virtual base
// might have a different offset in the most derived class.
VirtualOffset = GetVirtualBaseClassOffset(LoadCXXThis(), VTableClass,
NearestVBase);
NonVirtualOffset = OffsetFromNearestVBase;
} else {
// We can just use the base offset in the complete class.
NonVirtualOffset = Base.getBaseOffset();
}
// Apply the offsets.
llvm::Value *VTableField = LoadCXXThis();
if (!NonVirtualOffset.isZero() || VirtualOffset)
VTableField = ApplyNonVirtualAndVirtualOffset(*this, VTableField,
NonVirtualOffset,
VirtualOffset);
// Finally, store the address point.
llvm::Type *AddressPointPtrTy =
VTableAddressPoint->getType()->getPointerTo();
VTableField = Builder.CreateBitCast(VTableField, AddressPointPtrTy);
Builder.CreateStore(VTableAddressPoint, VTableField);
}
void
CodeGenFunction::InitializeVTablePointers(BaseSubobject Base,
const CXXRecordDecl *NearestVBase,
CharUnits OffsetFromNearestVBase,
bool BaseIsNonVirtualPrimaryBase,
llvm::Constant *VTable,
const CXXRecordDecl *VTableClass,
VisitedVirtualBasesSetTy& VBases) {
// If this base is a non-virtual primary base the address point has already
// been set.
if (!BaseIsNonVirtualPrimaryBase) {
// Initialize the vtable pointer for this base.
InitializeVTablePointer(Base, NearestVBase, OffsetFromNearestVBase,
VTable, VTableClass);
}
const CXXRecordDecl *RD = Base.getBase();
// Traverse bases.
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
E = RD->bases_end(); I != E; ++I) {
CXXRecordDecl *BaseDecl
= cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
// Ignore classes without a vtable.
if (!BaseDecl->isDynamicClass())
continue;
CharUnits BaseOffset;
CharUnits BaseOffsetFromNearestVBase;
bool BaseDeclIsNonVirtualPrimaryBase;
if (I->isVirtual()) {
// Check if we've visited this virtual base before.
if (!VBases.insert(BaseDecl))
continue;
const ASTRecordLayout &Layout =
getContext().getASTRecordLayout(VTableClass);
BaseOffset = Layout.getVBaseClassOffset(BaseDecl);
BaseOffsetFromNearestVBase = CharUnits::Zero();
BaseDeclIsNonVirtualPrimaryBase = false;
} else {
const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
BaseOffset = Base.getBaseOffset() + Layout.getBaseClassOffset(BaseDecl);
BaseOffsetFromNearestVBase =
OffsetFromNearestVBase + Layout.getBaseClassOffset(BaseDecl);
BaseDeclIsNonVirtualPrimaryBase = Layout.getPrimaryBase() == BaseDecl;
}
InitializeVTablePointers(BaseSubobject(BaseDecl, BaseOffset),
I->isVirtual() ? BaseDecl : NearestVBase,
BaseOffsetFromNearestVBase,
BaseDeclIsNonVirtualPrimaryBase,
VTable, VTableClass, VBases);
}
}
void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
// Ignore classes without a vtable.
if (!RD->isDynamicClass())
return;
// Get the VTable.
llvm::Constant *VTable = CGM.getVTables().GetAddrOfVTable(RD);
// Initialize the vtable pointers for this class and all of its bases.
VisitedVirtualBasesSetTy VBases;
InitializeVTablePointers(BaseSubobject(RD, CharUnits::Zero()),
/*NearestVBase=*/0,
/*OffsetFromNearestVBase=*/CharUnits::Zero(),
/*BaseIsNonVirtualPrimaryBase=*/false,
VTable, RD, VBases);
}
llvm::Value *CodeGenFunction::GetVTablePtr(llvm::Value *This,
llvm::Type *Ty) {
llvm::Value *VTablePtrSrc = Builder.CreateBitCast(This, Ty->getPointerTo());
return Builder.CreateLoad(VTablePtrSrc, "vtable");
}
static const CXXRecordDecl *getMostDerivedClassDecl(const Expr *Base) {
const Expr *E = Base;
while (true) {
E = E->IgnoreParens();
if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
if (CE->getCastKind() == CK_DerivedToBase ||
CE->getCastKind() == CK_UncheckedDerivedToBase ||
CE->getCastKind() == CK_NoOp) {
E = CE->getSubExpr();
continue;
}
}
break;
}
QualType DerivedType = E->getType();
if (const PointerType *PTy = DerivedType->getAs<PointerType>())
DerivedType = PTy->getPointeeType();
return cast<CXXRecordDecl>(DerivedType->castAs<RecordType>()->getDecl());
}
// FIXME: Ideally Expr::IgnoreParenNoopCasts should do this, but it doesn't do
// quite what we want.
static const Expr *skipNoOpCastsAndParens(const Expr *E) {
while (true) {
if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
E = PE->getSubExpr();
continue;
}
if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
if (CE->getCastKind() == CK_NoOp) {
E = CE->getSubExpr();
continue;
}
}
if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
if (UO->getOpcode() == UO_Extension) {
E = UO->getSubExpr();
continue;
}
}
return E;
}
}
/// canDevirtualizeMemberFunctionCall - Checks whether the given virtual member
/// function call on the given expr can be devirtualized.
static bool canDevirtualizeMemberFunctionCall(const Expr *Base,
const CXXMethodDecl *MD) {
// If the most derived class is marked final, we know that no subclass can
// override this member function and so we can devirtualize it. For example:
//
// struct A { virtual void f(); }
// struct B final : A { };
//
// void f(B *b) {
// b->f();
// }
//
const CXXRecordDecl *MostDerivedClassDecl = getMostDerivedClassDecl(Base);
if (MostDerivedClassDecl->hasAttr<FinalAttr>())
return true;
// If the member function is marked 'final', we know that it can't be
// overridden and can therefore devirtualize it.
if (MD->hasAttr<FinalAttr>())
return true;
// Similarly, if the class itself is marked 'final' it can't be overridden
// and we can therefore devirtualize the member function call.
if (MD->getParent()->hasAttr<FinalAttr>())
return true;
Base = skipNoOpCastsAndParens(Base);
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Base)) {
if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
// This is a record decl. We know the type and can devirtualize it.
return VD->getType()->isRecordType();
}
return false;
}
// We can always devirtualize calls on temporary object expressions.
if (isa<CXXConstructExpr>(Base))
return true;
// And calls on bound temporaries.
if (isa<CXXBindTemporaryExpr>(Base))
return true;
// Check if this is a call expr that returns a record type.
if (const CallExpr *CE = dyn_cast<CallExpr>(Base))
return CE->getCallReturnType()->isRecordType();
// We can't devirtualize the call.
return false;
}
static bool UseVirtualCall(ASTContext &Context,
const CXXOperatorCallExpr *CE,
const CXXMethodDecl *MD) {
if (!MD->isVirtual())
return false;
// When building with -fapple-kext, all calls must go through the vtable since
// the kernel linker can do runtime patching of vtables.
if (Context.getLangOptions().AppleKext)
return true;
return !canDevirtualizeMemberFunctionCall(CE->getArg(0), MD);
}
llvm::Value *
CodeGenFunction::EmitCXXOperatorMemberCallee(const CXXOperatorCallExpr *E,
const CXXMethodDecl *MD,
llvm::Value *This) {
const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
llvm::Type *Ty =
CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(MD),
FPT->isVariadic());
if (UseVirtualCall(getContext(), E, MD))
return BuildVirtualCall(MD, This, Ty);
return CGM.GetAddrOfFunction(MD, Ty);
}
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