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llvm / llvm-project / b516dcc998d06c97d874af543489887f7e5a680c / . / clang / lib / CodeGen / CGClass.cpp
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//===--- CGClass.cpp - Emit LLVM Code for C++ classes -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This contains code dealing with C++ code generation of classes
//
//===----------------------------------------------------------------------===//
#include "ABIInfoImpl.h"
#include "CGBlocks.h"
#include "CGCXXABI.h"
#include "CGDebugInfo.h"
#include "CGRecordLayout.h"
#include "CodeGenFunction.h"
#include "TargetInfo.h"
#include "clang/AST/Attr.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Basic/CodeGenOptions.h"
#include "clang/CodeGen/CGFunctionInfo.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Metadata.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Transforms/Utils/SanitizerStats.h"
#include <optional>
using namespace clang;
using namespace CodeGen;
/// Return the best known alignment for an unknown pointer to a
/// particular class.
CharUnits CodeGenModule::getClassPointerAlignment(const CXXRecordDecl *RD) {
if (!RD->hasDefinition())
return CharUnits::One(); // Hopefully won't be used anywhere.
auto &layout = getContext().getASTRecordLayout(RD);
// If the class is final, then we know that the pointer points to an
// object of that type and can use the full alignment.
if (RD->isEffectivelyFinal())
return layout.getAlignment();
// Otherwise, we have to assume it could be a subclass.
return layout.getNonVirtualAlignment();
}
/// Return the smallest possible amount of storage that might be allocated
/// starting from the beginning of an object of a particular class.
///
/// This may be smaller than sizeof(RD) if RD has virtual base classes.
CharUnits CodeGenModule::getMinimumClassObjectSize(const CXXRecordDecl *RD) {
if (!RD->hasDefinition())
return CharUnits::One();
auto &layout = getContext().getASTRecordLayout(RD);
// If the class is final, then we know that the pointer points to an
// object of that type and can use the full alignment.
if (RD->isEffectivelyFinal())
return layout.getSize();
// Otherwise, we have to assume it could be a subclass.
return std::max(layout.getNonVirtualSize(), CharUnits::One());
}
/// Return the best known alignment for a pointer to a virtual base,
/// given the alignment of a pointer to the derived class.
CharUnits CodeGenModule::getVBaseAlignment(CharUnits actualDerivedAlign,
const CXXRecordDecl *derivedClass,
const CXXRecordDecl *vbaseClass) {
// The basic idea here is that an underaligned derived pointer might
// indicate an underaligned base pointer.
assert(vbaseClass->isCompleteDefinition());
auto &baseLayout = getContext().getASTRecordLayout(vbaseClass);
CharUnits expectedVBaseAlign = baseLayout.getNonVirtualAlignment();
return getDynamicOffsetAlignment(actualDerivedAlign, derivedClass,
expectedVBaseAlign);
}
CharUnits
CodeGenModule::getDynamicOffsetAlignment(CharUnits actualBaseAlign,
const CXXRecordDecl *baseDecl,
CharUnits expectedTargetAlign) {
// If the base is an incomplete type (which is, alas, possible with
// member pointers), be pessimistic.
if (!baseDecl->isCompleteDefinition())
return std::min(actualBaseAlign, expectedTargetAlign);
auto &baseLayout = getContext().getASTRecordLayout(baseDecl);
CharUnits expectedBaseAlign = baseLayout.getNonVirtualAlignment();
// If the class is properly aligned, assume the target offset is, too.
//
// This actually isn't necessarily the right thing to do --- if the
// class is a complete object, but it's only properly aligned for a
// base subobject, then the alignments of things relative to it are
// probably off as well. (Note that this requires the alignment of
// the target to be greater than the NV alignment of the derived
// class.)
//
// However, our approach to this kind of under-alignment can only
// ever be best effort; after all, we're never going to propagate
// alignments through variables or parameters. Note, in particular,
// that constructing a polymorphic type in an address that's less
// than pointer-aligned will generally trap in the constructor,
// unless we someday add some sort of attribute to change the
// assumed alignment of 'this'. So our goal here is pretty much
// just to allow the user to explicitly say that a pointer is
// under-aligned and then safely access its fields and vtables.
if (actualBaseAlign >= expectedBaseAlign) {
return expectedTargetAlign;
}
// Otherwise, we might be offset by an arbitrary multiple of the
// actual alignment. The correct adjustment is to take the min of
// the two alignments.
return std::min(actualBaseAlign, expectedTargetAlign);
}
Address CodeGenFunction::LoadCXXThisAddress() {
assert(CurFuncDecl && "loading 'this' without a func declaration?");
auto *MD = cast<CXXMethodDecl>(CurFuncDecl);
// Lazily compute CXXThisAlignment.
if (CXXThisAlignment.isZero()) {
// Just use the best known alignment for the parent.
// TODO: if we're currently emitting a complete-object ctor/dtor,
// we can always use the complete-object alignment.
CXXThisAlignment = CGM.getClassPointerAlignment(MD->getParent());
}
return makeNaturalAddressForPointer(
LoadCXXThis(), MD->getFunctionObjectParameterType(), CXXThisAlignment,
false, nullptr, nullptr, KnownNonNull);
}
/// Emit the address of a field using a member data pointer.
///
/// \param E Only used for emergency diagnostics
Address CodeGenFunction::EmitCXXMemberDataPointerAddress(
const Expr *E, Address base, llvm::Value *memberPtr,
const MemberPointerType *memberPtrType, bool IsInBounds,
LValueBaseInfo *BaseInfo, TBAAAccessInfo *TBAAInfo) {
// Ask the ABI to compute the actual address.
llvm::Value *ptr = CGM.getCXXABI().EmitMemberDataPointerAddress(
*this, E, base, memberPtr, memberPtrType, IsInBounds);
QualType memberType = memberPtrType->getPointeeType();
CharUnits memberAlign =
CGM.getNaturalTypeAlignment(memberType, BaseInfo, TBAAInfo);
memberAlign = CGM.getDynamicOffsetAlignment(
base.getAlignment(), memberPtrType->getMostRecentCXXRecordDecl(),
memberAlign);
return Address(ptr, ConvertTypeForMem(memberPtrType->getPointeeType()),
memberAlign);
}
CharUnits CodeGenModule::computeNonVirtualBaseClassOffset(
const CXXRecordDecl *DerivedClass, CastExpr::path_const_iterator Start,
CastExpr::path_const_iterator End) {
CharUnits Offset = CharUnits::Zero();
const ASTContext &Context = getContext();
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 auto *BaseDecl = Base->getType()->castAsCXXRecordDecl();
// 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(ClassDecl, PathBegin, PathEnd);
if (Offset.isZero())
return nullptr;
llvm::Type *PtrDiffTy =
getTypes().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.
Address
CodeGenFunction::GetAddressOfDirectBaseInCompleteClass(Address This,
const CXXRecordDecl *Derived,
const CXXRecordDecl *Base,
bool BaseIsVirtual) {
// 'this' must be a pointer (in some address space) to Derived.
assert(This.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.
Address V = This;
if (!Offset.isZero()) {
V = V.withElementType(Int8Ty);
V = Builder.CreateConstInBoundsByteGEP(V, Offset);
}
return V.withElementType(ConvertType(Base));
}
static Address
ApplyNonVirtualAndVirtualOffset(CodeGenFunction &CGF, Address addr,
CharUnits nonVirtualOffset,
llvm::Value *virtualOffset,
const CXXRecordDecl *derivedClass,
const CXXRecordDecl *nearestVBase) {
// Assert that we have something to do.
assert(!nonVirtualOffset.isZero() || virtualOffset != nullptr);
// Compute the offset from the static and dynamic components.
llvm::Value *baseOffset;
if (!nonVirtualOffset.isZero()) {
llvm::Type *OffsetType =
(CGF.CGM.getTarget().getCXXABI().isItaniumFamily() &&
CGF.CGM.getItaniumVTableContext().isRelativeLayout())
? CGF.Int32Ty
: CGF.PtrDiffTy;
baseOffset =
llvm::ConstantInt::get(OffsetType, nonVirtualOffset.getQuantity());
if (virtualOffset) {
baseOffset = CGF.Builder.CreateAdd(virtualOffset, baseOffset);
}
} else {
baseOffset = virtualOffset;
}
// Apply the base offset.
llvm::Value *ptr = addr.emitRawPointer(CGF);
ptr = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, ptr, baseOffset, "add.ptr");
// If we have a virtual component, the alignment of the result will
// be relative only to the known alignment of that vbase.
CharUnits alignment;
if (virtualOffset) {
assert(nearestVBase && "virtual offset without vbase?");
alignment = CGF.CGM.getVBaseAlignment(addr.getAlignment(),
derivedClass, nearestVBase);
} else {
alignment = addr.getAlignment();
}
alignment = alignment.alignmentAtOffset(nonVirtualOffset);
return Address(ptr, CGF.Int8Ty, alignment);
}
Address CodeGenFunction::GetAddressOfBaseClass(
Address Value, const CXXRecordDecl *Derived,
CastExpr::path_const_iterator PathBegin,
CastExpr::path_const_iterator PathEnd, bool NullCheckValue,
SourceLocation Loc) {
assert(PathBegin != PathEnd && "Base path should not be empty!");
CastExpr::path_const_iterator Start = PathBegin;
const CXXRecordDecl *VBase = nullptr;
// Sema has done some convenient canonicalization here: if the
// access path involved any virtual steps, the conversion path will
// *start* with a step down to the correct virtual base subobject,
// and hence will not require any further steps.
if ((*Start)->isVirtual()) {
VBase = (*Start)->getType()->castAsCXXRecordDecl();
++Start;
}
// Compute the static offset of the ultimate destination within its
// allocating subobject (the virtual base, if there is one, or else
// the "complete" object that we see).
CharUnits NonVirtualOffset = CGM.computeNonVirtualBaseClassOffset(
VBase ? VBase : Derived, Start, PathEnd);
// If there's a virtual step, we can sometimes "devirtualize" it.
// For now, that's limited to when the derived type is final.
// TODO: "devirtualize" this for accesses to known-complete objects.
if (VBase && Derived->hasAttr<FinalAttr>()) {
const ASTRecordLayout &layout = getContext().getASTRecordLayout(Derived);
CharUnits vBaseOffset = layout.getVBaseClassOffset(VBase);
NonVirtualOffset += vBaseOffset;
VBase = nullptr; // we no longer have a virtual step
}
// Get the base pointer type.
llvm::Type *BaseValueTy = ConvertType((PathEnd[-1])->getType());
llvm::Type *PtrTy = llvm::PointerType::get(
CGM.getLLVMContext(), Value.getType()->getPointerAddressSpace());
CanQualType DerivedTy = getContext().getCanonicalTagType(Derived);
CharUnits DerivedAlign = CGM.getClassPointerAlignment(Derived);
// If the static offset is zero and we don't have a virtual step,
// just do a bitcast; null checks are unnecessary.
if (NonVirtualOffset.isZero() && !VBase) {
if (sanitizePerformTypeCheck()) {
SanitizerSet SkippedChecks;
SkippedChecks.set(SanitizerKind::Null, !NullCheckValue);
EmitTypeCheck(TCK_Upcast, Loc, Value.emitRawPointer(*this), DerivedTy,
DerivedAlign, SkippedChecks);
}
return Value.withElementType(BaseValueTy);
}
llvm::BasicBlock *origBB = nullptr;
llvm::BasicBlock *endBB = nullptr;
// Skip over the offset (and the vtable load) if we're supposed to
// null-check the pointer.
if (NullCheckValue) {
origBB = Builder.GetInsertBlock();
llvm::BasicBlock *notNullBB = createBasicBlock("cast.notnull");
endBB = createBasicBlock("cast.end");
llvm::Value *isNull = Builder.CreateIsNull(Value);
Builder.CreateCondBr(isNull, endBB, notNullBB);
EmitBlock(notNullBB);
}
if (sanitizePerformTypeCheck()) {
SanitizerSet SkippedChecks;
SkippedChecks.set(SanitizerKind::Null, true);
EmitTypeCheck(VBase ? TCK_UpcastToVirtualBase : TCK_Upcast, Loc,
Value.emitRawPointer(*this), DerivedTy, DerivedAlign,
SkippedChecks);
}
// Compute the virtual offset.
llvm::Value *VirtualOffset = nullptr;
if (VBase) {
VirtualOffset =
CGM.getCXXABI().GetVirtualBaseClassOffset(*this, Value, Derived, VBase);
}
// Apply both offsets.
Value = ApplyNonVirtualAndVirtualOffset(*this, Value, NonVirtualOffset,
VirtualOffset, Derived, VBase);
// Cast to the destination type.
Value = Value.withElementType(BaseValueTy);
// Build a phi if we needed a null check.
if (NullCheckValue) {
llvm::BasicBlock *notNullBB = Builder.GetInsertBlock();
Builder.CreateBr(endBB);
EmitBlock(endBB);
llvm::PHINode *PHI = Builder.CreatePHI(PtrTy, 2, "cast.result");
PHI->addIncoming(Value.emitRawPointer(*this), notNullBB);
PHI->addIncoming(llvm::Constant::getNullValue(PtrTy), origBB);
Value = Value.withPointer(PHI, NotKnownNonNull);
}
return Value;
}
Address
CodeGenFunction::GetAddressOfDerivedClass(Address BaseAddr,
const CXXRecordDecl *Derived,
CastExpr::path_const_iterator PathBegin,
CastExpr::path_const_iterator PathEnd,
bool NullCheckValue) {
assert(PathBegin != PathEnd && "Base path should not be empty!");
CanQualType DerivedTy = getContext().getCanonicalTagType(Derived);
llvm::Type *DerivedValueTy = ConvertType(DerivedTy);
llvm::Value *NonVirtualOffset =
CGM.GetNonVirtualBaseClassOffset(Derived, PathBegin, PathEnd);
if (!NonVirtualOffset) {
// No offset, we can just cast back.
return BaseAddr.withElementType(DerivedValueTy);
}
llvm::BasicBlock *CastNull = nullptr;
llvm::BasicBlock *CastNotNull = nullptr;
llvm::BasicBlock *CastEnd = nullptr;
if (NullCheckValue) {
CastNull = createBasicBlock("cast.null");
CastNotNull = createBasicBlock("cast.notnull");
CastEnd = createBasicBlock("cast.end");
llvm::Value *IsNull = Builder.CreateIsNull(BaseAddr);
Builder.CreateCondBr(IsNull, CastNull, CastNotNull);
EmitBlock(CastNotNull);
}
// Apply the offset.
Address Addr = BaseAddr.withElementType(Int8Ty);
Addr = Builder.CreateInBoundsGEP(
Addr, Builder.CreateNeg(NonVirtualOffset), Int8Ty,
CGM.getClassPointerAlignment(Derived), "sub.ptr");
// Just cast.
Addr = Addr.withElementType(DerivedValueTy);
// Produce a PHI if we had a null-check.
if (NullCheckValue) {
Builder.CreateBr(CastEnd);
EmitBlock(CastNull);
Builder.CreateBr(CastEnd);
EmitBlock(CastEnd);
llvm::Value *Value = Addr.emitRawPointer(*this);
llvm::PHINode *PHI = Builder.CreatePHI(Value->getType(), 2);
PHI->addIncoming(Value, CastNotNull);
PHI->addIncoming(llvm::Constant::getNullValue(Value->getType()), CastNull);
return Address(PHI, Addr.getElementType(),
CGM.getClassPointerAlignment(Derived));
}
return Addr;
}
llvm::Value *CodeGenFunction::GetVTTParameter(GlobalDecl GD,
bool ForVirtualBase,
bool Delegating) {
if (!CGM.getCXXABI().NeedsVTTParameter(GD)) {
// This constructor/destructor does not need a VTT parameter.
return nullptr;
}
const CXXRecordDecl *RD = cast<CXXMethodDecl>(CurCodeDecl)->getParent();
const CXXRecordDecl *Base = cast<CXXMethodDecl>(GD.getDecl())->getParent();
uint64_t SubVTTIndex;
if (Delegating) {
// If this is a delegating constructor call, just load the VTT.
return LoadCXXVTT();
} else if (RD == Base) {
// If the record matches the base, this is the complete ctor/dtor
// variant calling the base variant in a class with virtual bases.
assert(!CGM.getCXXABI().NeedsVTTParameter(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 = getContext().getASTRecordLayout(RD);
CharUnits BaseOffset = ForVirtualBase ?
Layout.getVBaseClassOffset(Base) :
Layout.getBaseClassOffset(Base);
SubVTTIndex =
CGM.getVTables().getSubVTTIndex(RD, BaseSubobject(Base, BaseOffset));
assert(SubVTTIndex != 0 && "Sub-VTT index must be greater than zero!");
}
if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
// A VTT parameter was passed to the constructor, use it.
llvm::Value *VTT = LoadCXXVTT();
return Builder.CreateConstInBoundsGEP1_64(VoidPtrTy, VTT, SubVTTIndex);
} else {
// We're the complete constructor, so get the VTT by name.
llvm::GlobalValue *VTT = CGM.getVTables().GetAddrOfVTT(RD);
return Builder.CreateConstInBoundsGEP2_64(
VTT->getValueType(), VTT, 0, SubVTTIndex);
}
}
namespace {
/// Call the destructor for a direct base class.
struct CallBaseDtor final : EHScopeStack::Cleanup {
const CXXRecordDecl *BaseClass;
bool BaseIsVirtual;
CallBaseDtor(const CXXRecordDecl *Base, bool BaseIsVirtual)
: BaseClass(Base), BaseIsVirtual(BaseIsVirtual) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
const CXXRecordDecl *DerivedClass =
cast<CXXMethodDecl>(CGF.CurCodeDecl)->getParent();
const CXXDestructorDecl *D = BaseClass->getDestructor();
// We are already inside a destructor, so presumably the object being
// destroyed should have the expected type.
QualType ThisTy = D->getFunctionObjectParameterType();
Address Addr =
CGF.GetAddressOfDirectBaseInCompleteClass(CGF.LoadCXXThisAddress(),
DerivedClass, BaseClass,
BaseIsVirtual);
CGF.EmitCXXDestructorCall(D, Dtor_Base, BaseIsVirtual,
/*Delegating=*/false, Addr, ThisTy);
}
};
/// A visitor which checks whether an initializer uses 'this' in a
/// way which requires the vtable to be properly set.
struct DynamicThisUseChecker : ConstEvaluatedExprVisitor<DynamicThisUseChecker> {
typedef ConstEvaluatedExprVisitor<DynamicThisUseChecker> super;
bool UsesThis;
DynamicThisUseChecker(const 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(const CXXThisExpr *E) { UsesThis = true; }
};
} // end anonymous namespace
static bool BaseInitializerUsesThis(ASTContext &C, const Expr *Init) {
DynamicThisUseChecker Checker(C);
Checker.Visit(Init);
return Checker.UsesThis;
}
static void EmitBaseInitializer(CodeGenFunction &CGF,
const CXXRecordDecl *ClassDecl,
CXXCtorInitializer *BaseInit) {
assert(BaseInit->isBaseInitializer() &&
"Must have base initializer!");
Address ThisPtr = CGF.LoadCXXThisAddress();
const auto *BaseClassDecl = BaseInit->getBaseClass()->castAsCXXRecordDecl();
bool isBaseVirtual = BaseInit->isBaseVirtual();
// 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.
Address V =
CGF.GetAddressOfDirectBaseInCompleteClass(ThisPtr, ClassDecl,
BaseClassDecl,
isBaseVirtual);
AggValueSlot AggSlot =
AggValueSlot::forAddr(
V, Qualifiers(),
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased,
CGF.getOverlapForBaseInit(ClassDecl, BaseClassDecl, isBaseVirtual));
CGF.EmitAggExpr(BaseInit->getInit(), AggSlot);
if (CGF.CGM.getLangOpts().Exceptions &&
!BaseClassDecl->hasTrivialDestructor())
CGF.EHStack.pushCleanup<CallBaseDtor>(EHCleanup, BaseClassDecl,
isBaseVirtual);
}
static bool isMemcpyEquivalentSpecialMember(const CXXMethodDecl *D) {
auto *CD = dyn_cast<CXXConstructorDecl>(D);
if (!(CD && CD->isCopyOrMoveConstructor()) &&
!D->isCopyAssignmentOperator() && !D->isMoveAssignmentOperator())
return false;
// We can emit a memcpy for a trivial copy or move constructor/assignment.
if (D->isTrivial() && !D->getParent()->mayInsertExtraPadding())
return true;
// We *must* emit a memcpy for a defaulted union copy or move op.
if (D->getParent()->isUnion() && D->isDefaulted())
return true;
return false;
}
static void EmitLValueForAnyFieldInitialization(CodeGenFunction &CGF,
CXXCtorInitializer *MemberInit,
LValue &LHS) {
FieldDecl *Field = MemberInit->getAnyMember();
if (MemberInit->isIndirectMemberInitializer()) {
// If we are initializing an anonymous union field, drill down to the field.
IndirectFieldDecl *IndirectField = MemberInit->getIndirectMember();
for (const auto *I : IndirectField->chain())
LHS = CGF.EmitLValueForFieldInitialization(LHS, cast<FieldDecl>(I));
} else {
LHS = CGF.EmitLValueForFieldInitialization(LHS, Field);
}
}
static void EmitMemberInitializer(CodeGenFunction &CGF,
const CXXRecordDecl *ClassDecl,
CXXCtorInitializer *MemberInit,
const CXXConstructorDecl *Constructor,
FunctionArgList &Args) {
ApplyAtomGroup Grp(CGF.getDebugInfo());
ApplyDebugLocation Loc(CGF, MemberInit->getSourceLocation());
assert(MemberInit->isAnyMemberInitializer() &&
"Must have member initializer!");
assert(MemberInit->getInit() && "Must have initializer!");
// non-static data member initializers.
FieldDecl *Field = MemberInit->getAnyMember();
QualType FieldType = Field->getType();
llvm::Value *ThisPtr = CGF.LoadCXXThis();
CanQualType RecordTy = CGF.getContext().getCanonicalTagType(ClassDecl);
LValue LHS;
// If a base constructor is being emitted, create an LValue that has the
// non-virtual alignment.
if (CGF.CurGD.getCtorType() == Ctor_Base)
LHS = CGF.MakeNaturalAlignPointeeAddrLValue(ThisPtr, RecordTy);
else
LHS = CGF.MakeNaturalAlignAddrLValue(ThisPtr, RecordTy);
EmitLValueForAnyFieldInitialization(CGF, MemberInit, LHS);
// Special case: if we are in a copy or move constructor, and we are copying
// an array of PODs or classes with trivial copy constructors, ignore the
// AST and perform the copy we know is equivalent.
// FIXME: This is hacky at best... if we had a bit more explicit information
// in the AST, we could generalize it more easily.
const ConstantArrayType *Array
= CGF.getContext().getAsConstantArrayType(FieldType);
if (Array && Constructor->isDefaulted() &&
Constructor->isCopyOrMoveConstructor()) {
QualType BaseElementTy = CGF.getContext().getBaseElementType(Array);
CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
if (BaseElementTy.isPODType(CGF.getContext()) ||
(CE && isMemcpyEquivalentSpecialMember(CE->getConstructor()))) {
unsigned SrcArgIndex =
CGF.CGM.getCXXABI().getSrcArgforCopyCtor(Constructor, Args);
llvm::Value *SrcPtr
= CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(Args[SrcArgIndex]));
LValue ThisRHSLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
LValue Src = CGF.EmitLValueForFieldInitialization(ThisRHSLV, Field);
// Copy the aggregate.
CGF.EmitAggregateCopy(LHS, Src, FieldType, CGF.getOverlapForFieldInit(Field),
LHS.isVolatileQualified());
// Ensure that we destroy the objects if an exception is thrown later in
// the constructor.
QualType::DestructionKind dtorKind = FieldType.isDestructedType();
if (CGF.needsEHCleanup(dtorKind))
CGF.pushEHDestroy(dtorKind, LHS.getAddress(), FieldType);
return;
}
}
CGF.EmitInitializerForField(Field, LHS, MemberInit->getInit());
}
void CodeGenFunction::EmitInitializerForField(FieldDecl *Field, LValue LHS,
Expr *Init) {
QualType FieldType = Field->getType();
switch (getEvaluationKind(FieldType)) {
case TEK_Scalar:
if (LHS.isSimple()) {
EmitExprAsInit(Init, Field, LHS, false);
} else {
RValue RHS = RValue::get(EmitScalarExpr(Init));
EmitStoreThroughLValue(RHS, LHS);
}
break;
case TEK_Complex:
EmitComplexExprIntoLValue(Init, LHS, /*isInit*/ true);
break;
case TEK_Aggregate: {
AggValueSlot Slot = AggValueSlot::forLValue(
LHS, AggValueSlot::IsDestructed, AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased, getOverlapForFieldInit(Field),
AggValueSlot::IsNotZeroed,
// Checks are made by the code that calls constructor.
AggValueSlot::IsSanitizerChecked);
EmitAggExpr(Init, Slot);
break;
}
}
// Ensure that we destroy this object if an exception is thrown
// later in the constructor.
QualType::DestructionKind dtorKind = FieldType.isDestructedType();
if (needsEHCleanup(dtorKind))
pushEHDestroy(dtorKind, LHS.getAddress(), FieldType);
}
/// 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.
bool CodeGenFunction::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 exclude 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()->castAs<FunctionProtoType>()->isVariadic())
return false;
// FIXME: Decide if we can do a delegation of a delegating constructor.
if (Ctor->isDelegatingConstructor())
return false;
return true;
}
// Emit code in ctor (Prologue==true) or dtor (Prologue==false)
// to poison the extra field paddings inserted under
// -fsanitize-address-field-padding=1|2.
void CodeGenFunction::EmitAsanPrologueOrEpilogue(bool Prologue) {
ASTContext &Context = getContext();
const CXXRecordDecl *ClassDecl =
Prologue ? cast<CXXConstructorDecl>(CurGD.getDecl())->getParent()
: cast<CXXDestructorDecl>(CurGD.getDecl())->getParent();
if (!ClassDecl->mayInsertExtraPadding()) return;
struct SizeAndOffset {
uint64_t Size;
uint64_t Offset;
};
unsigned PtrSize = CGM.getDataLayout().getPointerSizeInBits();
const ASTRecordLayout &Info = Context.getASTRecordLayout(ClassDecl);
// Populate sizes and offsets of fields.
SmallVector<SizeAndOffset, 16> SSV(Info.getFieldCount());
for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i)
SSV[i].Offset =
Context.toCharUnitsFromBits(Info.getFieldOffset(i)).getQuantity();
size_t NumFields = 0;
for (const auto *Field : ClassDecl->fields()) {
const FieldDecl *D = Field;
auto FieldInfo = Context.getTypeInfoInChars(D->getType());
CharUnits FieldSize = FieldInfo.Width;
assert(NumFields < SSV.size());
SSV[NumFields].Size = D->isBitField() ? 0 : FieldSize.getQuantity();
NumFields++;
}
assert(NumFields == SSV.size());
if (SSV.size() <= 1) return;
// We will insert calls to __asan_* run-time functions.
// LLVM AddressSanitizer pass may decide to inline them later.
llvm::Type *Args[2] = {IntPtrTy, IntPtrTy};
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, Args, false);
llvm::FunctionCallee F = CGM.CreateRuntimeFunction(
FTy, Prologue ? "__asan_poison_intra_object_redzone"
: "__asan_unpoison_intra_object_redzone");
llvm::Value *ThisPtr = LoadCXXThis();
ThisPtr = Builder.CreatePtrToInt(ThisPtr, IntPtrTy);
uint64_t TypeSize = Info.getNonVirtualSize().getQuantity();
// For each field check if it has sufficient padding,
// if so (un)poison it with a call.
for (size_t i = 0; i < SSV.size(); i++) {
uint64_t AsanAlignment = 8;
uint64_t NextField = i == SSV.size() - 1 ? TypeSize : SSV[i + 1].Offset;
uint64_t PoisonSize = NextField - SSV[i].Offset - SSV[i].Size;
uint64_t EndOffset = SSV[i].Offset + SSV[i].Size;
if (PoisonSize < AsanAlignment || !SSV[i].Size ||
(NextField % AsanAlignment) != 0)
continue;
Builder.CreateCall(
F, {Builder.CreateAdd(ThisPtr, Builder.getIntN(PtrSize, EndOffset)),
Builder.getIntN(PtrSize, PoisonSize)});
}
}
/// EmitConstructorBody - Emits the body of the current constructor.
void CodeGenFunction::EmitConstructorBody(FunctionArgList &Args) {
EmitAsanPrologueOrEpilogue(true);
const CXXConstructorDecl *Ctor = cast<CXXConstructorDecl>(CurGD.getDecl());
CXXCtorType CtorType = CurGD.getCtorType();
assert((CGM.getTarget().getCXXABI().hasConstructorVariants() ||
CtorType == Ctor_Complete) &&
"can only generate complete ctor for this ABI");
// Before we go any further, try the complete->base constructor
// delegation optimization.
if (CtorType == Ctor_Complete && IsConstructorDelegationValid(Ctor) &&
CGM.getTarget().getCXXABI().hasConstructorVariants()) {
EmitDelegateCXXConstructorCall(Ctor, Ctor_Base, Args, Ctor->getEndLoc());
return;
}
const FunctionDecl *Definition = nullptr;
Stmt *Body = Ctor->getBody(Definition);
assert(Definition == Ctor && "emitting wrong constructor body");
// Enter the function-try-block before the constructor prologue if
// applicable.
bool IsTryBody = isa_and_nonnull<CXXTryStmt>(Body);
if (IsTryBody)
EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
incrementProfileCounter(Body);
maybeCreateMCDCCondBitmap();
RunCleanupsScope RunCleanups(*this);
// TODO: in restricted cases, we can emit the vbase initializers of
// a complete ctor and then delegate to the base ctor.
// 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.
RunCleanups.ForceCleanup();
if (IsTryBody)
ExitCXXTryStmt(*cast<CXXTryStmt>(Body), true);
}
namespace {
/// RAII object to indicate that codegen is copying the value representation
/// instead of the object representation. Useful when copying a struct or
/// class which has uninitialized members and we're only performing
/// lvalue-to-rvalue conversion on the object but not its members.
class CopyingValueRepresentation {
public:
explicit CopyingValueRepresentation(CodeGenFunction &CGF)
: CGF(CGF), OldSanOpts(CGF.SanOpts) {
CGF.SanOpts.set(SanitizerKind::Bool, false);
CGF.SanOpts.set(SanitizerKind::Enum, false);
}
~CopyingValueRepresentation() {
CGF.SanOpts = OldSanOpts;
}
private:
CodeGenFunction &CGF;
SanitizerSet OldSanOpts;
};
} // end anonymous namespace
namespace {
class FieldMemcpyizer {
public:
FieldMemcpyizer(CodeGenFunction &CGF, const CXXRecordDecl *ClassDecl,
const VarDecl *SrcRec)
: CGF(CGF), ClassDecl(ClassDecl), SrcRec(SrcRec),
RecLayout(CGF.getContext().getASTRecordLayout(ClassDecl)),
FirstField(nullptr), LastField(nullptr), FirstFieldOffset(0),
LastFieldOffset(0), LastAddedFieldIndex(0) {}
bool isMemcpyableField(FieldDecl *F) const {
// Never memcpy fields when we are adding poisoned paddings.
if (CGF.getContext().getLangOpts().SanitizeAddressFieldPadding)
return false;
Qualifiers Qual = F->getType().getQualifiers();
if (Qual.hasVolatile() || Qual.hasObjCLifetime())
return false;
if (PointerAuthQualifier Q = F->getType().getPointerAuth();
Q && Q.isAddressDiscriminated())
return false;
return true;
}
void addMemcpyableField(FieldDecl *F) {
if (isEmptyFieldForLayout(CGF.getContext(), F))
return;
if (!FirstField)
addInitialField(F);
else
addNextField(F);
}
CharUnits getMemcpySize(uint64_t FirstByteOffset) const {
ASTContext &Ctx = CGF.getContext();
unsigned LastFieldSize =
LastField->isBitField()
? LastField->getBitWidthValue()
: Ctx.toBits(
Ctx.getTypeInfoDataSizeInChars(LastField->getType()).Width);
uint64_t MemcpySizeBits = LastFieldOffset + LastFieldSize -
FirstByteOffset + Ctx.getCharWidth() - 1;
CharUnits MemcpySize = Ctx.toCharUnitsFromBits(MemcpySizeBits);
return MemcpySize;
}
void emitMemcpy() {
// Give the subclass a chance to bail out if it feels the memcpy isn't
// worth it (e.g. Hasn't aggregated enough data).
if (!FirstField) {
return;
}
uint64_t FirstByteOffset;
if (FirstField->isBitField()) {
const CGRecordLayout &RL =
CGF.getTypes().getCGRecordLayout(FirstField->getParent());
const CGBitFieldInfo &BFInfo = RL.getBitFieldInfo(FirstField);
// FirstFieldOffset is not appropriate for bitfields,
// we need to use the storage offset instead.
FirstByteOffset = CGF.getContext().toBits(BFInfo.StorageOffset);
} else {
FirstByteOffset = FirstFieldOffset;
}
CharUnits MemcpySize = getMemcpySize(FirstByteOffset);
CanQualType RecordTy = CGF.getContext().getCanonicalTagType(ClassDecl);
Address ThisPtr = CGF.LoadCXXThisAddress();
LValue DestLV = CGF.MakeAddrLValue(ThisPtr, RecordTy);
LValue Dest = CGF.EmitLValueForFieldInitialization(DestLV, FirstField);
llvm::Value *SrcPtr = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(SrcRec));
LValue SrcLV = CGF.MakeNaturalAlignAddrLValue(SrcPtr, RecordTy);
LValue Src = CGF.EmitLValueForFieldInitialization(SrcLV, FirstField);
emitMemcpyIR(
Dest.isBitField() ? Dest.getBitFieldAddress() : Dest.getAddress(),
Src.isBitField() ? Src.getBitFieldAddress() : Src.getAddress(),
MemcpySize);
reset();
}
void reset() {
FirstField = nullptr;
}
protected:
CodeGenFunction &CGF;
const CXXRecordDecl *ClassDecl;
private:
void emitMemcpyIR(Address DestPtr, Address SrcPtr, CharUnits Size) {
DestPtr = DestPtr.withElementType(CGF.Int8Ty);
SrcPtr = SrcPtr.withElementType(CGF.Int8Ty);
auto *I = CGF.Builder.CreateMemCpy(DestPtr, SrcPtr, Size.getQuantity());
CGF.addInstToCurrentSourceAtom(I, nullptr);
}
void addInitialField(FieldDecl *F) {
FirstField = F;
LastField = F;
FirstFieldOffset = RecLayout.getFieldOffset(F->getFieldIndex());
LastFieldOffset = FirstFieldOffset;
LastAddedFieldIndex = F->getFieldIndex();
}
void addNextField(FieldDecl *F) {
// For the most part, the following invariant will hold:
// F->getFieldIndex() == LastAddedFieldIndex + 1
// The one exception is that Sema won't add a copy-initializer for an
// unnamed bitfield, which will show up here as a gap in the sequence.
assert(F->getFieldIndex() >= LastAddedFieldIndex + 1 &&
"Cannot aggregate fields out of order.");
LastAddedFieldIndex = F->getFieldIndex();
// The 'first' and 'last' fields are chosen by offset, rather than field
// index. This allows the code to support bitfields, as well as regular
// fields.
uint64_t FOffset = RecLayout.getFieldOffset(F->getFieldIndex());
if (FOffset < FirstFieldOffset) {
FirstField = F;
FirstFieldOffset = FOffset;
} else if (FOffset >= LastFieldOffset) {
LastField = F;
LastFieldOffset = FOffset;
}
}
const VarDecl *SrcRec;
const ASTRecordLayout &RecLayout;
FieldDecl *FirstField;
FieldDecl *LastField;
uint64_t FirstFieldOffset, LastFieldOffset;
unsigned LastAddedFieldIndex;
};
class ConstructorMemcpyizer : public FieldMemcpyizer {
private:
/// Get source argument for copy constructor. Returns null if not a copy
/// constructor.
static const VarDecl *getTrivialCopySource(CodeGenFunction &CGF,
const CXXConstructorDecl *CD,
FunctionArgList &Args) {
if (CD->isCopyOrMoveConstructor() && CD->isDefaulted())
return Args[CGF.CGM.getCXXABI().getSrcArgforCopyCtor(CD, Args)];
return nullptr;
}
// Returns true if a CXXCtorInitializer represents a member initialization
// that can be rolled into a memcpy.
bool isMemberInitMemcpyable(CXXCtorInitializer *MemberInit) const {
if (!MemcpyableCtor)
return false;
FieldDecl *Field = MemberInit->getMember();
assert(Field && "No field for member init.");
QualType FieldType = Field->getType();
CXXConstructExpr *CE = dyn_cast<CXXConstructExpr>(MemberInit->getInit());
// Bail out on non-memcpyable, not-trivially-copyable members.
if (!(CE && isMemcpyEquivalentSpecialMember(CE->getConstructor())) &&
!(FieldType.isTriviallyCopyableType(CGF.getContext()) ||
FieldType->isReferenceType()))
return false;
// Bail out on volatile fields.
if (!isMemcpyableField(Field))
return false;
// Otherwise we're good.
return true;
}
public:
ConstructorMemcpyizer(CodeGenFunction &CGF, const CXXConstructorDecl *CD,
FunctionArgList &Args)
: FieldMemcpyizer(CGF, CD->getParent(), getTrivialCopySource(CGF, CD, Args)),
ConstructorDecl(CD),
MemcpyableCtor(CD->isDefaulted() &&
CD->isCopyOrMoveConstructor() &&
CGF.getLangOpts().getGC() == LangOptions::NonGC),
Args(Args) { }
void addMemberInitializer(CXXCtorInitializer *MemberInit) {
if (isMemberInitMemcpyable(MemberInit)) {
AggregatedInits.push_back(MemberInit);
addMemcpyableField(MemberInit->getMember());
} else {
emitAggregatedInits();
EmitMemberInitializer(CGF, ConstructorDecl->getParent(), MemberInit,
ConstructorDecl, Args);
}
}
void emitAggregatedInits() {
if (AggregatedInits.size() <= 1) {
// This memcpy is too small to be worthwhile. Fall back on default
// codegen.
if (!AggregatedInits.empty()) {
CopyingValueRepresentation CVR(CGF);
EmitMemberInitializer(CGF, ConstructorDecl->getParent(),
AggregatedInits[0], ConstructorDecl, Args);
AggregatedInits.clear();
}
reset();
return;
}
pushEHDestructors();
ApplyAtomGroup Grp(CGF.getDebugInfo());
emitMemcpy();
AggregatedInits.clear();
}
void pushEHDestructors() {
Address ThisPtr = CGF.LoadCXXThisAddress();
CanQualType RecordTy = CGF.getContext().getCanonicalTagType(ClassDecl);
LValue LHS = CGF.MakeAddrLValue(ThisPtr, RecordTy);
for (unsigned i = 0; i < AggregatedInits.size(); ++i) {
CXXCtorInitializer *MemberInit = AggregatedInits[i];
QualType FieldType = MemberInit->getAnyMember()->getType();
QualType::DestructionKind dtorKind = FieldType.isDestructedType();
if (!CGF.needsEHCleanup(dtorKind))
continue;
LValue FieldLHS = LHS;
EmitLValueForAnyFieldInitialization(CGF, MemberInit, FieldLHS);
CGF.pushEHDestroy(dtorKind, FieldLHS.getAddress(), FieldType);
}
}
void finish() {
emitAggregatedInits();
}
private:
const CXXConstructorDecl *ConstructorDecl;
bool MemcpyableCtor;
FunctionArgList &Args;
SmallVector<CXXCtorInitializer*, 16> AggregatedInits;
};
class AssignmentMemcpyizer : public FieldMemcpyizer {
private:
// Returns the memcpyable field copied by the given statement, if one
// exists. Otherwise returns null.
FieldDecl *getMemcpyableField(Stmt *S) {
if (!AssignmentsMemcpyable)
return nullptr;
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(S)) {
// Recognise trivial assignments.
if (BO->getOpcode() != BO_Assign)
return nullptr;
MemberExpr *ME = dyn_cast<MemberExpr>(BO->getLHS());
if (!ME)
return nullptr;
FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
if (!Field || !isMemcpyableField(Field))
return nullptr;
Stmt *RHS = BO->getRHS();
if (ImplicitCastExpr *EC = dyn_cast<ImplicitCastExpr>(RHS))
RHS = EC->getSubExpr();
if (!RHS)
return nullptr;
if (MemberExpr *ME2 = dyn_cast<MemberExpr>(RHS)) {
if (ME2->getMemberDecl() == Field)
return Field;
}
return nullptr;
} else if (CXXMemberCallExpr *MCE = dyn_cast<CXXMemberCallExpr>(S)) {
CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MCE->getCalleeDecl());
if (!(MD && isMemcpyEquivalentSpecialMember(MD)))
return nullptr;
MemberExpr *IOA = dyn_cast<MemberExpr>(MCE->getImplicitObjectArgument());
if (!IOA)
return nullptr;
FieldDecl *Field = dyn_cast<FieldDecl>(IOA->getMemberDecl());
if (!Field || !isMemcpyableField(Field))
return nullptr;
MemberExpr *Arg0 = dyn_cast<MemberExpr>(MCE->getArg(0));
if (!Arg0 || Field != dyn_cast<FieldDecl>(Arg0->getMemberDecl()))
return nullptr;
return Field;
} else if (CallExpr *CE = dyn_cast<CallExpr>(S)) {
FunctionDecl *FD = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
if (!FD || FD->getBuiltinID() != Builtin::BI__builtin_memcpy)
return nullptr;
Expr *DstPtr = CE->getArg(0);
if (ImplicitCastExpr *DC = dyn_cast<ImplicitCastExpr>(DstPtr))
DstPtr = DC->getSubExpr();
UnaryOperator *DUO = dyn_cast<UnaryOperator>(DstPtr);
if (!DUO || DUO->getOpcode() != UO_AddrOf)
return nullptr;
MemberExpr *ME = dyn_cast<MemberExpr>(DUO->getSubExpr());
if (!ME)
return nullptr;
FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
if (!Field || !isMemcpyableField(Field))
return nullptr;
Expr *SrcPtr = CE->getArg(1);
if (ImplicitCastExpr *SC = dyn_cast<ImplicitCastExpr>(SrcPtr))
SrcPtr = SC->getSubExpr();
UnaryOperator *SUO = dyn_cast<UnaryOperator>(SrcPtr);
if (!SUO || SUO->getOpcode() != UO_AddrOf)
return nullptr;
MemberExpr *ME2 = dyn_cast<MemberExpr>(SUO->getSubExpr());
if (!ME2 || Field != dyn_cast<FieldDecl>(ME2->getMemberDecl()))
return nullptr;
return Field;
}
return nullptr;
}
bool AssignmentsMemcpyable;
SmallVector<Stmt*, 16> AggregatedStmts;
public:
AssignmentMemcpyizer(CodeGenFunction &CGF, const CXXMethodDecl *AD,
FunctionArgList &Args)
: FieldMemcpyizer(CGF, AD->getParent(), Args[Args.size() - 1]),
AssignmentsMemcpyable(CGF.getLangOpts().getGC() == LangOptions::NonGC) {
assert(Args.size() == 2);
}
void emitAssignment(Stmt *S) {
FieldDecl *F = getMemcpyableField(S);
if (F) {
addMemcpyableField(F);
AggregatedStmts.push_back(S);
} else {
emitAggregatedStmts();
CGF.EmitStmt(S);
}
}
void emitAggregatedStmts() {
if (AggregatedStmts.size() <= 1) {
if (!AggregatedStmts.empty()) {
CopyingValueRepresentation CVR(CGF);
CGF.EmitStmt(AggregatedStmts[0]);
}
reset();
}
ApplyAtomGroup Grp(CGF.getDebugInfo());
emitMemcpy();
AggregatedStmts.clear();
}
void finish() {
emitAggregatedStmts();
}
};
} // end anonymous namespace
static bool isInitializerOfDynamicClass(const CXXCtorInitializer *BaseInit) {
const Type *BaseType = BaseInit->getBaseClass();
return BaseType->castAsCXXRecordDecl()->isDynamicClass();
}
/// 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();
// Virtual base initializers aren't needed if:
// - This is a base ctor variant
// - There are no vbases
// - The class is abstract, so a complete object of it cannot be constructed
//
// The check for an abstract class is necessary because sema may not have
// marked virtual base destructors referenced.
bool ConstructVBases = CtorType != Ctor_Base &&
ClassDecl->getNumVBases() != 0 &&
!ClassDecl->isAbstract();
// In the Microsoft C++ ABI, there are no constructor variants. Instead, the
// constructor of a class with virtual bases takes an additional parameter to
// conditionally construct the virtual bases. Emit that check here.
llvm::BasicBlock *BaseCtorContinueBB = nullptr;
if (ConstructVBases &&
!CGM.getTarget().getCXXABI().hasConstructorVariants()) {
BaseCtorContinueBB =
CGM.getCXXABI().EmitCtorCompleteObjectHandler(*this, ClassDecl);
assert(BaseCtorContinueBB);
}
// Create three separate ranges for the different types of initializers.
auto AllInits = CD->inits();
// Find the boundaries between the three groups.
auto VirtualBaseEnd = std::find_if(
AllInits.begin(), AllInits.end(), [](const CXXCtorInitializer *Init) {
return !(Init->isBaseInitializer() && Init->isBaseVirtual());
});
auto NonVirtualBaseEnd = std::find_if(VirtualBaseEnd, AllInits.end(),
[](const CXXCtorInitializer *Init) {
return !Init->isBaseInitializer();
});
// Create the three ranges.
auto VirtualBaseInits = llvm::make_range(AllInits.begin(), VirtualBaseEnd);
auto NonVirtualBaseInits =
llvm::make_range(VirtualBaseEnd, NonVirtualBaseEnd);
auto MemberInits = llvm::make_range(NonVirtualBaseEnd, AllInits.end());
// Process virtual base initializers, if necessary.
if (ConstructVBases) {
for (CXXCtorInitializer *Initializer : VirtualBaseInits) {
SaveAndRestore ThisRAII(CXXThisValue);
if (CGM.getCodeGenOpts().StrictVTablePointers &&
CGM.getCodeGenOpts().OptimizationLevel > 0 &&
isInitializerOfDynamicClass(Initializer))
CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
EmitBaseInitializer(*this, ClassDecl, Initializer);
}
}
if (BaseCtorContinueBB) {
// Complete object handler should continue to the remaining initializers.
Builder.CreateBr(BaseCtorContinueBB);
EmitBlock(BaseCtorContinueBB);
}
// Then, non-virtual base initializers.
for (CXXCtorInitializer *Initializer : NonVirtualBaseInits) {
assert(!Initializer->isBaseVirtual());
SaveAndRestore ThisRAII(CXXThisValue);
if (CGM.getCodeGenOpts().StrictVTablePointers &&
CGM.getCodeGenOpts().OptimizationLevel > 0 &&
isInitializerOfDynamicClass(Initializer))
CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
EmitBaseInitializer(*this, ClassDecl, Initializer);
}
InitializeVTablePointers(ClassDecl);
// And finally, initialize class members.
FieldConstructionScope FCS(*this, LoadCXXThisAddress());
ConstructorMemcpyizer CM(*this, CD, Args);
for (CXXCtorInitializer *Member : MemberInits) {
assert(!Member->isBaseInitializer());
assert(Member->isAnyMemberInitializer() &&
"Delegating initializer on non-delegating constructor");
CM.addMemberInitializer(Member);
}
CM.finish();
}
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 (const auto *Field : BaseClassDecl->fields())
if (!FieldHasTrivialDestructorBody(Context, Field))
return false;
// Check non-virtual bases.
for (const auto &I : BaseClassDecl->bases()) {
if (I.isVirtual())
continue;
const auto *NonVirtualBase = I.getType()->castAsCXXRecordDecl();
if (!HasTrivialDestructorBody(Context, NonVirtualBase,
MostDerivedClassDecl))
return false;
}
if (BaseClassDecl == MostDerivedClassDecl) {
// Check virtual bases.
for (const auto &I : BaseClassDecl->vbases()) {
const auto *VirtualBase = I.getType()->castAsCXXRecordDecl();
if (!HasTrivialDestructorBody(Context, VirtualBase,
MostDerivedClassDecl))
return false;
}
}
return true;
}
static bool
FieldHasTrivialDestructorBody(ASTContext &Context,
const FieldDecl *Field)
{
QualType FieldBaseElementType = Context.getBaseElementType(Field->getType());
auto *FieldClassDecl = FieldBaseElementType->getAsCXXRecordDecl();
if (!FieldClassDecl)
return true;
// The destructor for an implicit anonymous union member is never invoked.
if (FieldClassDecl->isUnion() && FieldClassDecl->isAnonymousStructOrUnion())
return true;
return HasTrivialDestructorBody(Context, FieldClassDecl, FieldClassDecl);
}
/// CanSkipVTablePointerInitialization - Check whether we need to initialize
/// any vtable pointers before calling this destructor.
static bool CanSkipVTablePointerInitialization(CodeGenFunction &CGF,
const CXXDestructorDecl *Dtor) {
const CXXRecordDecl *ClassDecl = Dtor->getParent();
if (!ClassDecl->isDynamicClass())
return true;
// For a final class, the vtable pointer is known to already point to the
// class's vtable.
if (ClassDecl->isEffectivelyFinal())
return true;
if (!Dtor->hasTrivialBody())
return false;
// Check the fields.
for (const auto *Field : ClassDecl->fields())
if (!FieldHasTrivialDestructorBody(CGF.getContext(), 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();
// For an abstract class, non-base destructors are never used (and can't
// be emitted in general, because vbase dtors may not have been validated
// by Sema), but the Itanium ABI doesn't make them optional and Clang may
// in fact emit references to them from other compilations, so emit them
// as functions containing a trap instruction.
if (DtorType != Dtor_Base && Dtor->getParent()->isAbstract()) {
llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap);
TrapCall->setDoesNotReturn();
TrapCall->setDoesNotThrow();
Builder.CreateUnreachable();
Builder.ClearInsertionPoint();
return;
}
Stmt *Body = Dtor->getBody();
if (Body) {
incrementProfileCounter(Body);
maybeCreateMCDCCondBitmap();
}
// 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) {
RunCleanupsScope DtorEpilogue(*this);
EnterDtorCleanups(Dtor, Dtor_Deleting);
if (HaveInsertPoint()) {
QualType ThisTy = Dtor->getFunctionObjectParameterType();
EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false,
/*Delegating=*/false, LoadCXXThisAddress(), ThisTy);
}
return;
}
// If the body is a function-try-block, enter the try before
// anything else.
bool isTryBody = isa_and_nonnull<CXXTryStmt>(Body);
if (isTryBody)
EnterCXXTryStmt(*cast<CXXTryStmt>(Body), true);
EmitAsanPrologueOrEpilogue(false);
// 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. In the Microsoft ABI, we
// always delegate because we might not have a definition in this TU.
switch (DtorType) {
case Dtor_Unified:
llvm_unreachable("not expecting a unified dtor");
case Dtor_Comdat: llvm_unreachable("not expecting a COMDAT");
case Dtor_Deleting: llvm_unreachable("already handled deleting case");
case Dtor_Complete:
assert((Body || getTarget().getCXXABI().isMicrosoft()) &&
"can't emit a dtor without a body for non-Microsoft ABIs");
// Enter the cleanup scopes for virtual bases.
EnterDtorCleanups(Dtor, Dtor_Complete);
if (!isTryBody) {
QualType ThisTy = Dtor->getFunctionObjectParameterType();
EmitCXXDestructorCall(Dtor, Dtor_Base, /*ForVirtualBase=*/false,
/*Delegating=*/false, LoadCXXThisAddress(), ThisTy);
break;
}
// Fallthrough: act like we're in the base variant.
[[fallthrough]];
case Dtor_Base:
assert(Body);
// Enter the cleanup scopes for fields and non-virtual bases.
EnterDtorCleanups(Dtor, Dtor_Base);
// Initialize the vtable pointers before entering the body.
if (!CanSkipVTablePointerInitialization(*this, Dtor)) {
// Insert the llvm.launder.invariant.group intrinsic before initializing
// the vptrs to cancel any previous assumptions we might have made.
if (CGM.getCodeGenOpts().StrictVTablePointers &&
CGM.getCodeGenOpts().OptimizationLevel > 0)
CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
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 (getLangOpts().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);
}
void CodeGenFunction::emitImplicitAssignmentOperatorBody(FunctionArgList &Args) {
const CXXMethodDecl *AssignOp = cast<CXXMethodDecl>(CurGD.getDecl());
const Stmt *RootS = AssignOp->getBody();
assert(isa<CompoundStmt>(RootS) &&
"Body of an implicit assignment operator should be compound stmt.");
const CompoundStmt *RootCS = cast<CompoundStmt>(RootS);
LexicalScope Scope(*this, RootCS->getSourceRange());
incrementProfileCounter(RootCS);
maybeCreateMCDCCondBitmap();
AssignmentMemcpyizer AM(*this, AssignOp, Args);
for (auto *I : RootCS->body())
AM.emitAssignment(I);
AM.finish();
}
namespace {
llvm::Value *LoadThisForDtorDelete(CodeGenFunction &CGF,
const CXXDestructorDecl *DD) {
if (Expr *ThisArg = DD->getOperatorDeleteThisArg())
return CGF.EmitScalarExpr(ThisArg);
return CGF.LoadCXXThis();
}
/// Call the operator delete associated with the current destructor.
struct CallDtorDelete final : EHScopeStack::Cleanup {
CallDtorDelete() {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
const CXXRecordDecl *ClassDecl = Dtor->getParent();
CGF.EmitDeleteCall(Dtor->getOperatorDelete(),
LoadThisForDtorDelete(CGF, Dtor),
CGF.getContext().getCanonicalTagType(ClassDecl));
}
};
// This function implements generation of scalar deleting destructor body for
// the case when the destructor also accepts an implicit flag. Right now only
// Microsoft ABI requires deleting destructors to accept implicit flags.
// The flag indicates whether an operator delete should be called and whether
// it should be a class-specific operator delete or a global one.
void EmitConditionalDtorDeleteCall(CodeGenFunction &CGF,
llvm::Value *ShouldDeleteCondition,
bool ReturnAfterDelete) {
const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
const CXXRecordDecl *ClassDecl = Dtor->getParent();
const FunctionDecl *OD = Dtor->getOperatorDelete();
assert(OD->isDestroyingOperatorDelete() == ReturnAfterDelete &&
"unexpected value for ReturnAfterDelete");
auto *CondTy = cast<llvm::IntegerType>(ShouldDeleteCondition->getType());
// MSVC calls global operator delete inside of the dtor body, but clang
// aligned with this behavior only after a particular version. This is not
// ABI-compatible with previous versions.
ASTContext &Context = CGF.getContext();
bool CallGlobDelete =
Context.getTargetInfo().callGlobalDeleteInDeletingDtor(
Context.getLangOpts());
if (CallGlobDelete && OD->isDestroyingOperatorDelete()) {
llvm::BasicBlock *CallDtor = CGF.createBasicBlock("dtor.call_dtor");
llvm::BasicBlock *DontCallDtor = CGF.createBasicBlock("dtor.entry_cont");
// Third bit set signals that global operator delete is called. That means
// despite class having destroying operator delete which is responsible
// for calling dtor, we need to call dtor because global operator delete
// won't do that.
llvm::Value *Check3rdBit = CGF.Builder.CreateAnd(
ShouldDeleteCondition, llvm::ConstantInt::get(CondTy, 4));
llvm::Value *ShouldCallDtor = CGF.Builder.CreateIsNull(Check3rdBit);
CGF.Builder.CreateCondBr(ShouldCallDtor, DontCallDtor, CallDtor);
CGF.EmitBlock(CallDtor);
QualType ThisTy = Dtor->getFunctionObjectParameterType();
CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false,
/*Delegating=*/false, CGF.LoadCXXThisAddress(),
ThisTy);
CGF.Builder.CreateBr(DontCallDtor);
CGF.EmitBlock(DontCallDtor);
}
llvm::BasicBlock *callDeleteBB = CGF.createBasicBlock("dtor.call_delete");
llvm::BasicBlock *continueBB = CGF.createBasicBlock("dtor.continue");
// First bit set signals that operator delete must be called.
llvm::Value *Check1stBit = CGF.Builder.CreateAnd(
ShouldDeleteCondition, llvm::ConstantInt::get(CondTy, 1));
llvm::Value *ShouldCallDelete = CGF.Builder.CreateIsNull(Check1stBit);
CGF.Builder.CreateCondBr(ShouldCallDelete, continueBB, callDeleteBB);
CGF.EmitBlock(callDeleteBB);
auto EmitDeleteAndGoToEnd = [&](const FunctionDecl *DeleteOp) {
CGF.EmitDeleteCall(DeleteOp, LoadThisForDtorDelete(CGF, Dtor),
Context.getCanonicalTagType(ClassDecl));
if (ReturnAfterDelete)
CGF.EmitBranchThroughCleanup(CGF.ReturnBlock);
else
CGF.Builder.CreateBr(continueBB);
};
// If Sema only found a global operator delete previously, the dtor can
// always call it. Otherwise we need to check the third bit and call the
// appropriate operator delete, i.e. global or class-specific.
if (const FunctionDecl *GlobOD = Dtor->getOperatorGlobalDelete();
isa<CXXMethodDecl>(OD) && GlobOD && CallGlobDelete) {
// Third bit set signals that global operator delete is called, i.e.
// ::delete appears on the callsite.
llvm::Value *CheckTheBitForGlobDeleteCall = CGF.Builder.CreateAnd(
ShouldDeleteCondition, llvm::ConstantInt::get(CondTy, 4));
llvm::Value *ShouldCallGlobDelete =
CGF.Builder.CreateIsNull(CheckTheBitForGlobDeleteCall);
llvm::BasicBlock *GlobDelete =
CGF.createBasicBlock("dtor.call_glob_delete");
llvm::BasicBlock *ClassDelete =
CGF.createBasicBlock("dtor.call_class_delete");
CGF.Builder.CreateCondBr(ShouldCallGlobDelete, ClassDelete, GlobDelete);
CGF.EmitBlock(GlobDelete);
EmitDeleteAndGoToEnd(GlobOD);
CGF.EmitBlock(ClassDelete);
}
EmitDeleteAndGoToEnd(OD);
CGF.EmitBlock(continueBB);
}
struct CallDtorDeleteConditional final : EHScopeStack::Cleanup {
llvm::Value *ShouldDeleteCondition;
public:
CallDtorDeleteConditional(llvm::Value *ShouldDeleteCondition)
: ShouldDeleteCondition(ShouldDeleteCondition) {
assert(ShouldDeleteCondition != nullptr);
}
void Emit(CodeGenFunction &CGF, Flags flags) override {
EmitConditionalDtorDeleteCall(CGF, ShouldDeleteCondition,
/*ReturnAfterDelete*/false);
}
};
class DestroyField final : 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) override {
// Find the address of the field.
Address thisValue = CGF.LoadCXXThisAddress();
CanQualType RecordTy =
CGF.getContext().getCanonicalTagType(field->getParent());
LValue ThisLV = CGF.MakeAddrLValue(thisValue, RecordTy);
LValue LV = CGF.EmitLValueForField(ThisLV, field);
assert(LV.isSimple());
CGF.emitDestroy(LV.getAddress(), field->getType(), destroyer,
flags.isForNormalCleanup() && useEHCleanupForArray);
}
};
class DeclAsInlineDebugLocation {
CGDebugInfo *DI;
llvm::MDNode *InlinedAt;
std::optional<ApplyDebugLocation> Location;
public:
DeclAsInlineDebugLocation(CodeGenFunction &CGF, const NamedDecl &Decl)
: DI(CGF.getDebugInfo()) {
if (!DI)
return;
InlinedAt = DI->getInlinedAt();
DI->setInlinedAt(CGF.Builder.getCurrentDebugLocation());
Location.emplace(CGF, Decl.getLocation());
}
~DeclAsInlineDebugLocation() {
if (!DI)
return;
Location.reset();
DI->setInlinedAt(InlinedAt);
}
};
static void EmitSanitizerDtorCallback(
CodeGenFunction &CGF, StringRef Name, llvm::Value *Ptr,
std::optional<CharUnits::QuantityType> PoisonSize = {}) {
CodeGenFunction::SanitizerScope SanScope(&CGF);
// Pass in void pointer and size of region as arguments to runtime
// function
SmallVector<llvm::Value *, 2> Args = {Ptr};
SmallVector<llvm::Type *, 2> ArgTypes = {CGF.VoidPtrTy};
if (PoisonSize.has_value()) {
Args.emplace_back(llvm::ConstantInt::get(CGF.SizeTy, *PoisonSize));
ArgTypes.emplace_back(CGF.SizeTy);
}
llvm::FunctionType *FnType =
llvm::FunctionType::get(CGF.VoidTy, ArgTypes, false);
llvm::FunctionCallee Fn = CGF.CGM.CreateRuntimeFunction(FnType, Name);
CGF.EmitNounwindRuntimeCall(Fn, Args);
}
static void
EmitSanitizerDtorFieldsCallback(CodeGenFunction &CGF, llvm::Value *Ptr,
CharUnits::QuantityType PoisonSize) {
EmitSanitizerDtorCallback(CGF, "__sanitizer_dtor_callback_fields", Ptr,
PoisonSize);
}
/// Poison base class with a trivial destructor.
struct SanitizeDtorTrivialBase final : EHScopeStack::Cleanup {
const CXXRecordDecl *BaseClass;
bool BaseIsVirtual;
SanitizeDtorTrivialBase(const CXXRecordDecl *Base, bool BaseIsVirtual)
: BaseClass(Base), BaseIsVirtual(BaseIsVirtual) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
const CXXRecordDecl *DerivedClass =
cast<CXXMethodDecl>(CGF.CurCodeDecl)->getParent();
Address Addr = CGF.GetAddressOfDirectBaseInCompleteClass(
CGF.LoadCXXThisAddress(), DerivedClass, BaseClass, BaseIsVirtual);
const ASTRecordLayout &BaseLayout =
CGF.getContext().getASTRecordLayout(BaseClass);
CharUnits BaseSize = BaseLayout.getSize();
if (!BaseSize.isPositive())
return;
// Use the base class declaration location as inline DebugLocation. All
// fields of the class are destroyed.
DeclAsInlineDebugLocation InlineHere(CGF, *BaseClass);
EmitSanitizerDtorFieldsCallback(CGF, Addr.emitRawPointer(CGF),
BaseSize.getQuantity());
// Prevent the current stack frame from disappearing from the stack trace.
CGF.CurFn->addFnAttr("disable-tail-calls", "true");
}
};
class SanitizeDtorFieldRange final : public EHScopeStack::Cleanup {
const CXXDestructorDecl *Dtor;
unsigned StartIndex;
unsigned EndIndex;
public:
SanitizeDtorFieldRange(const CXXDestructorDecl *Dtor, unsigned StartIndex,
unsigned EndIndex)
: Dtor(Dtor), StartIndex(StartIndex), EndIndex(EndIndex) {}
// Generate function call for handling object poisoning.
// Disables tail call elimination, to prevent the current stack frame
// from disappearing from the stack trace.
void Emit(CodeGenFunction &CGF, Flags flags) override {
const ASTContext &Context = CGF.getContext();
const ASTRecordLayout &Layout =
Context.getASTRecordLayout(Dtor->getParent());
// It's a first trivial field so it should be at the begining of a char,
// still round up start offset just in case.
CharUnits PoisonStart = Context.toCharUnitsFromBits(
Layout.getFieldOffset(StartIndex) + Context.getCharWidth() - 1);
llvm::ConstantInt *OffsetSizePtr =
llvm::ConstantInt::get(CGF.SizeTy, PoisonStart.getQuantity());
llvm::Value *OffsetPtr =
CGF.Builder.CreateGEP(CGF.Int8Ty, CGF.LoadCXXThis(), OffsetSizePtr);
CharUnits PoisonEnd;
if (EndIndex >= Layout.getFieldCount()) {
PoisonEnd = Layout.getNonVirtualSize();
} else {
PoisonEnd =
Context.toCharUnitsFromBits(Layout.getFieldOffset(EndIndex));
}
CharUnits PoisonSize = PoisonEnd - PoisonStart;
if (!PoisonSize.isPositive())
return;
// Use the top field declaration location as inline DebugLocation.
DeclAsInlineDebugLocation InlineHere(
CGF, **std::next(Dtor->getParent()->field_begin(), StartIndex));
EmitSanitizerDtorFieldsCallback(CGF, OffsetPtr, PoisonSize.getQuantity());
// Prevent the current stack frame from disappearing from the stack trace.
CGF.CurFn->addFnAttr("disable-tail-calls", "true");
}
};
class SanitizeDtorVTable final : public EHScopeStack::Cleanup {
const CXXDestructorDecl *Dtor;
public:
SanitizeDtorVTable(const CXXDestructorDecl *Dtor) : Dtor(Dtor) {}
// Generate function call for handling vtable pointer poisoning.
void Emit(CodeGenFunction &CGF, Flags flags) override {
assert(Dtor->getParent()->isDynamicClass());
(void)Dtor;
// Poison vtable and vtable ptr if they exist for this class.
llvm::Value *VTablePtr = CGF.LoadCXXThis();
// Pass in void pointer and size of region as arguments to runtime
// function
EmitSanitizerDtorCallback(CGF, "__sanitizer_dtor_callback_vptr",
VTablePtr);
}
};
class SanitizeDtorCleanupBuilder {
ASTContext &Context;
EHScopeStack &EHStack;
const CXXDestructorDecl *DD;
std::optional<unsigned> StartIndex;
public:
SanitizeDtorCleanupBuilder(ASTContext &Context, EHScopeStack &EHStack,
const CXXDestructorDecl *DD)
: Context(Context), EHStack(EHStack), DD(DD), StartIndex(std::nullopt) {}
void PushCleanupForField(const FieldDecl *Field) {
if (isEmptyFieldForLayout(Context, Field))
return;
unsigned FieldIndex = Field->getFieldIndex();
if (FieldHasTrivialDestructorBody(Context, Field)) {
if (!StartIndex)
StartIndex = FieldIndex;
} else if (StartIndex) {
EHStack.pushCleanup<SanitizeDtorFieldRange>(NormalAndEHCleanup, DD,
*StartIndex, FieldIndex);
StartIndex = std::nullopt;
}
}
void End() {
if (StartIndex)
EHStack.pushCleanup<SanitizeDtorFieldRange>(NormalAndEHCleanup, DD,
*StartIndex, -1);
}
};
} // end anonymous namespace
/// 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.
///
/// For a deleting destructor, this also handles the case where a destroying
/// operator delete completely overrides the definition.
void CodeGenFunction::EnterDtorCleanups(const CXXDestructorDecl *DD,
CXXDtorType DtorType) {
assert((!DD->isTrivial() || DD->hasAttr<DLLExportAttr>()) &&
"Should not emit dtor epilogue for non-exported 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 - EnterDtorCleanups");
if (CXXStructorImplicitParamValue) {
// If there is an implicit param to the deleting dtor, it's a boolean
// telling whether this is a deleting destructor.
if (DD->getOperatorDelete()->isDestroyingOperatorDelete())
EmitConditionalDtorDeleteCall(*this, CXXStructorImplicitParamValue,
/*ReturnAfterDelete*/true);
else
EHStack.pushCleanup<CallDtorDeleteConditional>(
NormalAndEHCleanup, CXXStructorImplicitParamValue);
} else {
if (DD->getOperatorDelete()->isDestroyingOperatorDelete()) {
const CXXRecordDecl *ClassDecl = DD->getParent();
EmitDeleteCall(DD->getOperatorDelete(),
LoadThisForDtorDelete(*this, DD),
getContext().getCanonicalTagType(ClassDecl));
EmitBranchThroughCleanup(ReturnBlock);
} else {
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) {
// Poison the vtable pointer such that access after the base
// and member destructors are invoked is invalid.
if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
SanOpts.has(SanitizerKind::Memory) && ClassDecl->getNumVBases() &&
ClassDecl->isPolymorphic())
EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
// We push them in the forward order so that they'll be popped in
// the reverse order.
for (const auto &Base : ClassDecl->vbases()) {
auto *BaseClassDecl = Base.getType()->castAsCXXRecordDecl();
if (BaseClassDecl->hasTrivialDestructor()) {
// Under SanitizeMemoryUseAfterDtor, poison the trivial base class
// memory. For non-trival base classes the same is done in the class
// destructor.
if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
SanOpts.has(SanitizerKind::Memory) && !BaseClassDecl->isEmpty())
EHStack.pushCleanup<SanitizeDtorTrivialBase>(NormalAndEHCleanup,
BaseClassDecl,
/*BaseIsVirtual*/ true);
} else {
EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup, BaseClassDecl,
/*BaseIsVirtual*/ true);
}
}
return;
}
assert(DtorType == Dtor_Base);
// Poison the vtable pointer if it has no virtual bases, but inherits
// virtual functions.
if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
SanOpts.has(SanitizerKind::Memory) && !ClassDecl->getNumVBases() &&
ClassDecl->isPolymorphic())
EHStack.pushCleanup<SanitizeDtorVTable>(NormalAndEHCleanup, DD);
// Destroy non-virtual bases.
for (const auto &Base : ClassDecl->bases()) {
// Ignore virtual bases.
if (Base.isVirtual())
continue;
CXXRecordDecl *BaseClassDecl = Base.getType()->getAsCXXRecordDecl();
if (BaseClassDecl->hasTrivialDestructor()) {
if (CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
SanOpts.has(SanitizerKind::Memory) && !BaseClassDecl->isEmpty())
EHStack.pushCleanup<SanitizeDtorTrivialBase>(NormalAndEHCleanup,
BaseClassDecl,
/*BaseIsVirtual*/ false);
} else {
EHStack.pushCleanup<CallBaseDtor>(NormalAndEHCleanup, BaseClassDecl,
/*BaseIsVirtual*/ false);
}
}
// Poison fields such that access after their destructors are
// invoked, and before the base class destructor runs, is invalid.
bool SanitizeFields = CGM.getCodeGenOpts().SanitizeMemoryUseAfterDtor &&
SanOpts.has(SanitizerKind::Memory);
SanitizeDtorCleanupBuilder SanitizeBuilder(getContext(), EHStack, DD);
// Destroy direct fields.
for (const auto *Field : ClassDecl->fields()) {
if (SanitizeFields)
SanitizeBuilder.PushCleanupForField(Field);
QualType type = Field->getType();
QualType::DestructionKind dtorKind = type.isDestructedType();
if (!dtorKind)
continue;
// Anonymous union members do not have their destructors called.
const RecordType *RT = type->getAsUnionType();
if (RT && RT->getDecl()->isAnonymousStructOrUnion())
continue;
CleanupKind cleanupKind = getCleanupKind(dtorKind);
EHStack.pushCleanup<DestroyField>(
cleanupKind, Field, getDestroyer(dtorKind), cleanupKind & EHCleanup);
}
if (SanitizeFields)
SanitizeBuilder.End();
}
/// 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 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 ArrayType *arrayType,
Address arrayBegin, const CXXConstructExpr *E, bool NewPointerIsChecked,
bool zeroInitialize) {
QualType elementType;
llvm::Value *numElements =
emitArrayLength(arrayType, elementType, arrayBegin);
EmitCXXAggrConstructorCall(ctor, numElements, arrayBegin, E,
NewPointerIsChecked, 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 arrayBase 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,
Address arrayBase,
const CXXConstructExpr *E,
bool NewPointerIsChecked,
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 = nullptr;
// 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::Type *elementType = arrayBase.getElementType();
llvm::Value *arrayBegin = arrayBase.emitRawPointer(*this);
llvm::Value *arrayEnd = Builder.CreateInBoundsGEP(
elementType, 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.
if (CGM.shouldEmitConvergenceTokens())
ConvergenceTokenStack.push_back(emitConvergenceLoopToken(loopBB));
// The alignment of the base, adjusted by the size of a single element,
// provides a conservative estimate of the alignment of every element.
// (This assumes we never start tracking offsetted alignments.)
//
// Note that these are complete objects and so we don't need to
// use the non-virtual size or alignment.
CanQualType type = getContext().getCanonicalTagType(ctor->getParent());
CharUnits eltAlignment =
arrayBase.getAlignment()
.alignmentOfArrayElement(getContext().getTypeSizeInChars(type));
Address curAddr = Address(cur, elementType, eltAlignment);
// Zero initialize the storage, if requested.
if (zeroInitialize)
EmitNullInitialization(curAddr, 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 (getLangOpts().Exceptions &&
!ctor->getParent()->hasTrivialDestructor()) {
Destroyer *destroyer = destroyCXXObject;
pushRegularPartialArrayCleanup(arrayBegin, cur, type, eltAlignment,
*destroyer);
}
auto currAVS = AggValueSlot::forAddr(
curAddr, type.getQualifiers(), AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased,
AggValueSlot::DoesNotOverlap, AggValueSlot::IsNotZeroed,
NewPointerIsChecked ? AggValueSlot::IsSanitizerChecked
: AggValueSlot::IsNotSanitizerChecked);
EmitCXXConstructorCall(ctor, Ctor_Complete, /*ForVirtualBase=*/false,
/*Delegating=*/false, currAVS, E);
}
// Go to the next element.
llvm::Value *next = Builder.CreateInBoundsGEP(
elementType, 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);
if (CGM.shouldEmitConvergenceTokens())
ConvergenceTokenStack.pop_back();
EmitBlock(contBB);
}
void CodeGenFunction::destroyCXXObject(CodeGenFunction &CGF,
Address addr,
QualType type) {
const CXXDestructorDecl *dtor = type->castAsCXXRecordDecl()->getDestructor();
assert(!dtor->isTrivial());
CGF.EmitCXXDestructorCall(dtor, Dtor_Complete, /*for vbase*/ false,
/*Delegating=*/false, addr, type);
}
void CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
CXXCtorType Type,
bool ForVirtualBase,
bool Delegating,
AggValueSlot ThisAVS,
const CXXConstructExpr *E) {
CallArgList Args;
Address This = ThisAVS.getAddress();
LangAS SlotAS = ThisAVS.getQualifiers().getAddressSpace();
LangAS ThisAS = D->getFunctionObjectParameterType().getAddressSpace();
llvm::Value *ThisPtr =
getAsNaturalPointerTo(This, D->getThisType()->getPointeeType());
if (SlotAS != ThisAS) {
unsigned TargetThisAS = getContext().getTargetAddressSpace(ThisAS);
llvm::Type *NewType =
llvm::PointerType::get(getLLVMContext(), TargetThisAS);
ThisPtr =
getTargetHooks().performAddrSpaceCast(*this, ThisPtr, ThisAS, NewType);
}
// Push the this ptr.
Args.add(RValue::get(ThisPtr), D->getThisType());
// If this is a trivial constructor, emit a memcpy now before we lose
// the alignment information on the argument.
// FIXME: It would be better to preserve alignment information into CallArg.
if (isMemcpyEquivalentSpecialMember(D)) {
assert(E->getNumArgs() == 1 && "unexpected argcount for trivial ctor");
const Expr *Arg = E->getArg(0);
LValue Src = EmitLValue(Arg);
CanQualType DestTy = getContext().getCanonicalTagType(D->getParent());
LValue Dest = MakeAddrLValue(This, DestTy);
EmitAggregateCopyCtor(Dest, Src, ThisAVS.mayOverlap());
return;
}
// Add the rest of the user-supplied arguments.
const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
EvaluationOrder Order = E->isListInitialization()
? EvaluationOrder::ForceLeftToRight
: EvaluationOrder::Default;
EmitCallArgs(Args, FPT, E->arguments(), E->getConstructor(),
/*ParamsToSkip*/ 0, Order);
EmitCXXConstructorCall(D, Type, ForVirtualBase, Delegating, This, Args,
ThisAVS.mayOverlap(), E->getExprLoc(),
ThisAVS.isSanitizerChecked());
}
static bool canEmitDelegateCallArgs(CodeGenFunction &CGF,
const CXXConstructorDecl *Ctor,
CXXCtorType Type, CallArgList &Args) {
// We can't forward a variadic call.
if (Ctor->isVariadic())
return false;
if (CGF.getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
// If the parameters are callee-cleanup, it's not safe to forward.
for (auto *P : Ctor->parameters())
if (P->needsDestruction(CGF.getContext()))
return false;
// Likewise if they're inalloca.
const CGFunctionInfo &Info =
CGF.CGM.getTypes().arrangeCXXConstructorCall(Args, Ctor, Type, 0, 0);
if (Info.usesInAlloca())
return false;
}
// Anything else should be OK.
return true;
}
void CodeGenFunction::EmitCXXConstructorCall(
const CXXConstructorDecl *D, CXXCtorType Type, bool ForVirtualBase,
bool Delegating, Address This, CallArgList &Args,
AggValueSlot::Overlap_t Overlap, SourceLocation Loc,
bool NewPointerIsChecked, llvm::CallBase **CallOrInvoke) {
const CXXRecordDecl *ClassDecl = D->getParent();
if (!NewPointerIsChecked)
EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, Loc, This,
getContext().getCanonicalTagType(ClassDecl),
CharUnits::Zero());
if (D->isTrivial() && D->isDefaultConstructor()) {
assert(Args.size() == 1 && "trivial default ctor with args");
return;
}
// If this is a trivial constructor, just emit what's needed. If this is a
// union copy constructor, we must emit a memcpy, because the AST does not
// model that copy.
if (isMemcpyEquivalentSpecialMember(D)) {
assert(Args.size() == 2 && "unexpected argcount for trivial ctor");
QualType SrcTy = D->getParamDecl(0)->getType().getNonReferenceType();
Address Src = makeNaturalAddressForPointer(
Args[1].getRValue(*this).getScalarVal(), SrcTy);
LValue SrcLVal = MakeAddrLValue(Src, SrcTy);
CanQualType DestTy = getContext().getCanonicalTagType(ClassDecl);
LValue DestLVal = MakeAddrLValue(This, DestTy);
EmitAggregateCopyCtor(DestLVal, SrcLVal, Overlap);
return;
}
bool PassPrototypeArgs = true;
// Check whether we can actually emit the constructor before trying to do so.
if (auto Inherited = D->getInheritedConstructor()) {
PassPrototypeArgs = getTypes().inheritingCtorHasParams(Inherited, Type);
if (PassPrototypeArgs && !canEmitDelegateCallArgs(*this, D, Type, Args)) {
EmitInlinedInheritingCXXConstructorCall(D, Type, ForVirtualBase,
Delegating, Args);
return;
}
}
// Insert any ABI-specific implicit constructor arguments.
CGCXXABI::AddedStructorArgCounts ExtraArgs =
CGM.getCXXABI().addImplicitConstructorArgs(*this, D, Type, ForVirtualBase,
Delegating, Args);
// Emit the call.
llvm::Constant *CalleePtr = CGM.getAddrOfCXXStructor(GlobalDecl(D, Type));
const CGFunctionInfo &Info = CGM.getTypes().arrangeCXXConstructorCall(
Args, D, Type, ExtraArgs.Prefix, ExtraArgs.Suffix, PassPrototypeArgs);
CGCallee Callee = CGCallee::forDirect(CalleePtr, GlobalDecl(D, Type));
EmitCall(Info, Callee, ReturnValueSlot(), Args, CallOrInvoke, false, Loc);
// Generate vtable assumptions if we're constructing a complete object
// with a vtable. We don't do this for base subobjects for two reasons:
// first, it's incorrect for classes with virtual bases, and second, we're
// about to overwrite the vptrs anyway.
// We also have to make sure if we can refer to vtable:
// - Otherwise we can refer to vtable if it's safe to speculatively emit.
// FIXME: If vtable is used by ctor/dtor, or if vtable is external and we are
// sure that definition of vtable is not hidden,
// then we are always safe to refer to it.
// FIXME: It looks like InstCombine is very inefficient on dealing with
// assumes. Make assumption loads require -fstrict-vtable-pointers temporarily.
if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
ClassDecl->isDynamicClass() && Type != Ctor_Base &&
CGM.getCXXABI().canSpeculativelyEmitVTable(ClassDecl) &&
CGM.getCodeGenOpts().StrictVTablePointers)
EmitVTableAssumptionLoads(ClassDecl, This);
}
void CodeGenFunction::EmitInheritedCXXConstructorCall(
const CXXConstructorDecl *D, bool ForVirtualBase, Address This,
bool InheritedFromVBase, const CXXInheritedCtorInitExpr *E) {
CallArgList Args;
CallArg ThisArg(RValue::get(getAsNaturalPointerTo(
This, D->getThisType()->getPointeeType())),
D->getThisType());
// Forward the parameters.
if (InheritedFromVBase &&
CGM.getTarget().getCXXABI().hasConstructorVariants()) {
// Nothing to do; this construction is not responsible for constructing
// the base class containing the inherited constructor.
// FIXME: Can we just pass undef's for the remaining arguments if we don't
// have constructor variants?
Args.push_back(ThisArg);
} else if (!CXXInheritedCtorInitExprArgs.empty()) {
// The inheriting constructor was inlined; just inject its arguments.
assert(CXXInheritedCtorInitExprArgs.size() >= D->getNumParams() &&
"wrong number of parameters for inherited constructor call");
Args = CXXInheritedCtorInitExprArgs;
Args[0] = ThisArg;
} else {
// The inheriting constructor was not inlined. Emit delegating arguments.
Args.push_back(ThisArg);
const auto *OuterCtor = cast<CXXConstructorDecl>(CurCodeDecl);
assert(OuterCtor->getNumParams() == D->getNumParams());
assert(!OuterCtor->isVariadic() && "should have been inlined");
for (const auto *Param : OuterCtor->parameters()) {
assert(getContext().hasSameUnqualifiedType(
OuterCtor->getParamDecl(Param->getFunctionScopeIndex())->getType(),
Param->getType()));
EmitDelegateCallArg(Args, Param, E->getLocation());
// Forward __attribute__(pass_object_size).
if (Param->hasAttr<PassObjectSizeAttr>()) {
auto *POSParam = SizeArguments[Param];
assert(POSParam && "missing pass_object_size value for forwarding");
EmitDelegateCallArg(Args, POSParam, E->getLocation());
}
}
}
EmitCXXConstructorCall(D, Ctor_Base, ForVirtualBase, /*Delegating*/false,
This, Args, AggValueSlot::MayOverlap,
E->getLocation(), /*NewPointerIsChecked*/true);
}
void CodeGenFunction::EmitInlinedInheritingCXXConstructorCall(
const CXXConstructorDecl *Ctor, CXXCtorType CtorType, bool ForVirtualBase,
bool Delegating, CallArgList &Args) {
GlobalDecl GD(Ctor, CtorType);
InlinedInheritingConstructorScope Scope(*this, GD);
ApplyInlineDebugLocation DebugScope(*this, GD);
RunCleanupsScope RunCleanups(*this);
// Save the arguments to be passed to the inherited constructor.
CXXInheritedCtorInitExprArgs = Args;
FunctionArgList Params;
QualType RetType = BuildFunctionArgList(CurGD, Params);
FnRetTy = RetType;
// Insert any ABI-specific implicit constructor arguments.
CGM.getCXXABI().addImplicitConstructorArgs(*this, Ctor, CtorType,
ForVirtualBase, Delegating, Args);
// Emit a simplified prolog. We only need to emit the implicit params.
assert(Args.size() >= Params.size() && "too few arguments for call");
for (unsigned I = 0, N = Args.size(); I != N; ++I) {
if (I < Params.size() && isa<ImplicitParamDecl>(Params[I])) {
const RValue &RV = Args[I].getRValue(*this);
assert(!RV.isComplex() && "complex indirect params not supported");
ParamValue Val = RV.isScalar()
? ParamValue::forDirect(RV.getScalarVal())
: ParamValue::forIndirect(RV.getAggregateAddress());
EmitParmDecl(*Params[I], Val, I + 1);
}
}
// Create a return value slot if the ABI implementation wants one.
// FIXME: This is dumb, we should ask the ABI not to try to set the return
// value instead.
if (!RetType->isVoidType())
ReturnValue = CreateIRTemp(RetType, "retval.inhctor");
CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
CXXThisValue = CXXABIThisValue;
// Directly emit the constructor initializers.
EmitCtorPrologue(Ctor, CtorType, Params);
}
void CodeGenFunction::EmitVTableAssumptionLoad(const VPtr &Vptr, Address This) {
llvm::Value *VTableGlobal =
CGM.getCXXABI().getVTableAddressPoint(Vptr.Base, Vptr.VTableClass);
if (!VTableGlobal)
return;
// We can just use the base offset in the complete class.
CharUnits NonVirtualOffset = Vptr.Base.getBaseOffset();
if (!NonVirtualOffset.isZero())
This =
ApplyNonVirtualAndVirtualOffset(*this, This, NonVirtualOffset, nullptr,
Vptr.VTableClass, Vptr.NearestVBase);
llvm::Value *VPtrValue =
GetVTablePtr(This, VTableGlobal->getType(), Vptr.VTableClass);
llvm::Value *Cmp =
Builder.CreateICmpEQ(VPtrValue, VTableGlobal, "cmp.vtables");
Builder.CreateAssumption(Cmp);
}
void CodeGenFunction::EmitVTableAssumptionLoads(const CXXRecordDecl *ClassDecl,
Address This) {
if (CGM.getCXXABI().doStructorsInitializeVPtrs(ClassDecl))
for (const VPtr &Vptr : getVTablePointers(ClassDecl))
EmitVTableAssumptionLoad(Vptr, This);
}
void
CodeGenFunction::EmitSynthesizedCXXCopyCtorCall(const CXXConstructorDecl *D,
Address This, Address Src,
const CXXConstructExpr *E) {
const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
CallArgList Args;
// Push the this ptr.
Args.add(RValue::get(getAsNaturalPointerTo(This, D->getThisType())),
D->getThisType());
// Push the src ptr.
QualType QT = *(FPT->param_type_begin());
llvm::Type *t = CGM.getTypes().ConvertType(QT);
llvm::Value *Val = getAsNaturalPointerTo(Src, D->getThisType());
llvm::Value *SrcVal = Builder.CreateBitCast(Val, t);
Args.add(RValue::get(SrcVal), QT);
// Skip over first argument (Src).
EmitCallArgs(Args, FPT, drop_begin(E->arguments(), 1), E->getConstructor(),
/*ParamsToSkip*/ 1);
EmitCXXConstructorCall(D, Ctor_Complete, /*ForVirtualBase*/false,
/*Delegating*/false, This, Args,
AggValueSlot::MayOverlap, E->getExprLoc(),
/*NewPointerIsChecked*/false);
}
void
CodeGenFunction::EmitDelegateCXXConstructorCall(const CXXConstructorDecl *Ctor,
CXXCtorType CtorType,
const FunctionArgList &Args,
SourceLocation Loc) {
CallArgList DelegateArgs;
FunctionArgList::const_iterator I = Args.begin(), E = Args.end();
assert(I != E && "no parameters to constructor");
// this
Address This = LoadCXXThisAddress();
DelegateArgs.add(RValue::get(getAsNaturalPointerTo(
This, (*I)->getType()->getPointeeType())),
(*I)->getType());
++I;
// FIXME: The location of the VTT parameter in the parameter list is
// specific to the Itanium ABI and shouldn't be hardcoded here.
if (CGM.getCXXABI().NeedsVTTParameter(CurGD)) {
assert(I != E && "cannot skip vtt parameter, already done with args");
assert((*I)->getType()->isPointerType() &&
"skipping parameter not of vtt type");
++I;
}
// Explicit arguments.
for (; I != E; ++I) {
const VarDecl *param = *I;
// FIXME: per-argument source location
EmitDelegateCallArg(DelegateArgs, param, Loc);
}
EmitCXXConstructorCall(Ctor, CtorType, /*ForVirtualBase=*/false,
/*Delegating=*/true, This, DelegateArgs,
AggValueSlot::MayOverlap, Loc,
/*NewPointerIsChecked=*/true);
}
namespace {
struct CallDelegatingCtorDtor final : EHScopeStack::Cleanup {
const CXXDestructorDecl *Dtor;
Address Addr;
CXXDtorType Type;
CallDelegatingCtorDtor(const CXXDestructorDecl *D, Address Addr,
CXXDtorType Type)
: Dtor(D), Addr(Addr), Type(Type) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
// We are calling the destructor from within the constructor.
// Therefore, "this" should have the expected type.
QualType ThisTy = Dtor->getFunctionObjectParameterType();
CGF.EmitCXXDestructorCall(Dtor, Type, /*ForVirtualBase=*/false,
/*Delegating=*/true, Addr, ThisTy);
}
};
} // end anonymous namespace
void
CodeGenFunction::EmitDelegatingCXXConstructorCall(const CXXConstructorDecl *Ctor,
const FunctionArgList &Args) {
assert(Ctor->isDelegatingConstructor());
Address ThisPtr = LoadCXXThisAddress();
AggValueSlot AggSlot =
AggValueSlot::forAddr(ThisPtr, Qualifiers(),
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased,
AggValueSlot::MayOverlap,
AggValueSlot::IsNotZeroed,
// Checks are made by the code that calls constructor.
AggValueSlot::IsSanitizerChecked);
EmitAggExpr(Ctor->init_begin()[0]->getInit(), AggSlot);
const CXXRecordDecl *ClassDecl = Ctor->getParent();
if (CGM.getLangOpts().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,
bool Delegating, Address This,
QualType ThisTy) {
CGM.getCXXABI().EmitDestructorCall(*this, DD, Type, ForVirtualBase,
Delegating, This, ThisTy);
}
namespace {
struct CallLocalDtor final : EHScopeStack::Cleanup {
const CXXDestructorDecl *Dtor;
Address Addr;
QualType Ty;
CallLocalDtor(const CXXDestructorDecl *D, Address Addr, QualType Ty)
: Dtor(D), Addr(Addr), Ty(Ty) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
/*ForVirtualBase=*/false,
/*Delegating=*/false, Addr, Ty);
}
};
} // end anonymous namespace
void CodeGenFunction::PushDestructorCleanup(const CXXDestructorDecl *D,
QualType T, Address Addr) {
EHStack.pushCleanup<CallLocalDtor>(NormalAndEHCleanup, D, Addr, T);
}
void CodeGenFunction::PushDestructorCleanup(QualType T, Address 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, T, Addr);
}
void CodeGenFunction::InitializeVTablePointer(const VPtr &Vptr) {
// Compute the address point.
llvm::Value *VTableAddressPoint =
CGM.getCXXABI().getVTableAddressPointInStructor(
*this, Vptr.VTableClass, Vptr.Base, Vptr.NearestVBase);
if (!VTableAddressPoint)
return;
// Compute where to store the address point.
llvm::Value *VirtualOffset = nullptr;
CharUnits NonVirtualOffset = CharUnits::Zero();
if (CGM.getCXXABI().isVirtualOffsetNeededForVTableField(*this, Vptr)) {
// We need to use the virtual base offset offset because the virtual base
// might have a different offset in the most derived class.
VirtualOffset = CGM.getCXXABI().GetVirtualBaseClassOffset(
*this, LoadCXXThisAddress(), Vptr.VTableClass, Vptr.NearestVBase);
NonVirtualOffset = Vptr.OffsetFromNearestVBase;
} else {
// We can just use the base offset in the complete class.
NonVirtualOffset = Vptr.Base.getBaseOffset();
}
// Apply the offsets.
Address VTableField = LoadCXXThisAddress();
if (!NonVirtualOffset.isZero() || VirtualOffset)
VTableField = ApplyNonVirtualAndVirtualOffset(
*this, VTableField, NonVirtualOffset, VirtualOffset, Vptr.VTableClass,
Vptr.NearestVBase);
// Finally, store the address point. Use the same LLVM types as the field to
// support optimization.
unsigned GlobalsAS = CGM.getDataLayout().getDefaultGlobalsAddressSpace();
llvm::Type *PtrTy = llvm::PointerType::get(CGM.getLLVMContext(), GlobalsAS);
// vtable field is derived from `this` pointer, therefore they should be in
// the same addr space. Note that this might not be LLVM address space 0.
VTableField = VTableField.withElementType(PtrTy);
if (auto AuthenticationInfo = CGM.getVTablePointerAuthInfo(
this, Vptr.Base.getBase(), VTableField.emitRawPointer(*this)))
VTableAddressPoint =
EmitPointerAuthSign(*AuthenticationInfo, VTableAddressPoint);
llvm::StoreInst *Store = Builder.CreateStore(VTableAddressPoint, VTableField);
TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(PtrTy);
CGM.DecorateInstructionWithTBAA(Store, TBAAInfo);
if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
CGM.getCodeGenOpts().StrictVTablePointers)
CGM.DecorateInstructionWithInvariantGroup(Store, Vptr.VTableClass);
}
CodeGenFunction::VPtrsVector
CodeGenFunction::getVTablePointers(const CXXRecordDecl *VTableClass) {
CodeGenFunction::VPtrsVector VPtrsResult;
VisitedVirtualBasesSetTy VBases;
getVTablePointers(BaseSubobject(VTableClass, CharUnits::Zero()),
/*NearestVBase=*/nullptr,
/*OffsetFromNearestVBase=*/CharUnits::Zero(),
/*BaseIsNonVirtualPrimaryBase=*/false, VTableClass, VBases,
VPtrsResult);
return VPtrsResult;
}
void CodeGenFunction::getVTablePointers(BaseSubobject Base,
const CXXRecordDecl *NearestVBase,
CharUnits OffsetFromNearestVBase,
bool BaseIsNonVirtualPrimaryBase,
const CXXRecordDecl *VTableClass,
VisitedVirtualBasesSetTy &VBases,
VPtrsVector &Vptrs) {
// 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.
VPtr Vptr = {Base, NearestVBase, OffsetFromNearestVBase, VTableClass};
Vptrs.push_back(Vptr);
}
const CXXRecordDecl *RD = Base.getBase();
// Traverse bases.
for (const auto &I : RD->bases()) {
auto *BaseDecl = I.getType()->castAsCXXRecordDecl();
// 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).second)
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;
}
getVTablePointers(
BaseSubobject(BaseDecl, BaseOffset),
I.isVirtual() ? BaseDecl : NearestVBase, BaseOffsetFromNearestVBase,
BaseDeclIsNonVirtualPrimaryBase, VTableClass, VBases, Vptrs);
}
}
void CodeGenFunction::InitializeVTablePointers(const CXXRecordDecl *RD) {
// Ignore classes without a vtable.
if (!RD->isDynamicClass())
return;
// Initialize the vtable pointers for this class and all of its bases.
if (CGM.getCXXABI().doStructorsInitializeVPtrs(RD))
for (const VPtr &Vptr : getVTablePointers(RD))
InitializeVTablePointer(Vptr);
if (RD->getNumVBases())
CGM.getCXXABI().initializeHiddenVirtualInheritanceMembers(*this, RD);
}
llvm::Value *CodeGenFunction::GetVTablePtr(Address This,
llvm::Type *VTableTy,
const CXXRecordDecl *RD,
VTableAuthMode AuthMode) {
Address VTablePtrSrc = This.withElementType(VTableTy);
llvm::Instruction *VTable = Builder.CreateLoad(VTablePtrSrc, "vtable");
TBAAAccessInfo TBAAInfo = CGM.getTBAAVTablePtrAccessInfo(VTableTy);
CGM.DecorateInstructionWithTBAA(VTable, TBAAInfo);
if (auto AuthenticationInfo =
CGM.getVTablePointerAuthInfo(this, RD, This.emitRawPointer(*this))) {
if (AuthMode != VTableAuthMode::UnsafeUbsanStrip) {
VTable = cast<llvm::Instruction>(
EmitPointerAuthAuth(*AuthenticationInfo, VTable));
if (AuthMode == VTableAuthMode::MustTrap) {
// This is clearly suboptimal but until we have an ability
// to rely on the authentication intrinsic trapping and force
// an authentication to occur we don't really have a choice.
VTable =
cast<llvm::Instruction>(Builder.CreateBitCast(VTable, Int8PtrTy));
Builder.CreateLoad(RawAddress(VTable, Int8Ty, CGM.getPointerAlign()),
/* IsVolatile */ true);
}
} else {
VTable = cast<llvm::Instruction>(EmitPointerAuthAuth(
CGPointerAuthInfo(0, PointerAuthenticationMode::Strip, false, false,
nullptr),
VTable));
}
}
if (CGM.getCodeGenOpts().OptimizationLevel > 0 &&
CGM.getCodeGenOpts().StrictVTablePointers)
CGM.DecorateInstructionWithInvariantGroup(VTable, RD);
return VTable;
}
// If a class has a single non-virtual base and does not introduce or override
// virtual member functions or fields, it will have the same layout as its base.
// This function returns the least derived such class.
//
// Casting an instance of a base class to such a derived class is technically
// undefined behavior, but it is a relatively common hack for introducing member
// functions on class instances with specific properties (e.g. llvm::Operator)
// that works under most compilers and should not have security implications, so
// we allow it by default. It can be disabled with -fsanitize=cfi-cast-strict.
static const CXXRecordDecl *
LeastDerivedClassWithSameLayout(const CXXRecordDecl *RD) {
if (!RD->field_empty())
return RD;
if (RD->getNumVBases() != 0)
return RD;
if (RD->getNumBases() != 1)
return RD;
for (const CXXMethodDecl *MD : RD->methods()) {
if (MD->isVirtual()) {
// Virtual member functions are only ok if they are implicit destructors
// because the implicit destructor will have the same semantics as the
// base class's destructor if no fields are added.
if (isa<CXXDestructorDecl>(MD) && MD->isImplicit())
continue;
return RD;
}
}
return LeastDerivedClassWithSameLayout(
RD->bases_begin()->getType()->getAsCXXRecordDecl());
}
void CodeGenFunction::EmitTypeMetadataCodeForVCall(const CXXRecordDecl *RD,
llvm::Value *VTable,
SourceLocation Loc) {
if (SanOpts.has(SanitizerKind::CFIVCall))
EmitVTablePtrCheckForCall(RD, VTable, CodeGenFunction::CFITCK_VCall, Loc);
else if (CGM.getCodeGenOpts().WholeProgramVTables &&
// Don't insert type test assumes if we are forcing public
// visibility.
!CGM.AlwaysHasLTOVisibilityPublic(RD)) {
CanQualType Ty = CGM.getContext().getCanonicalTagType(RD);
llvm::Metadata *MD = CGM.CreateMetadataIdentifierForType(Ty);
llvm::Value *TypeId =
llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
// If we already know that the call has hidden LTO visibility, emit
// @llvm.type.test(). Otherwise emit @llvm.public.type.test(), which WPD
// will convert to @llvm.type.test() if we assert at link time that we have
// whole program visibility.
llvm::Intrinsic::ID IID = CGM.HasHiddenLTOVisibility(RD)
? llvm::Intrinsic::type_test
: llvm::Intrinsic::public_type_test;
llvm::Value *TypeTest =
Builder.CreateCall(CGM.getIntrinsic(IID), {VTable, TypeId});
Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::assume), TypeTest);
}
}
/// Converts the CFITypeCheckKind into SanitizerKind::SanitizerOrdinal and
/// llvm::SanitizerStatKind.
static std::pair<SanitizerKind::SanitizerOrdinal, llvm::SanitizerStatKind>
SanitizerInfoFromCFICheckKind(CodeGenFunction::CFITypeCheckKind TCK) {
switch (TCK) {
case CodeGenFunction::CFITCK_VCall:
return std::make_pair(SanitizerKind::SO_CFIVCall, llvm::SanStat_CFI_VCall);
case CodeGenFunction::CFITCK_NVCall:
return std::make_pair(SanitizerKind::SO_CFINVCall,
llvm::SanStat_CFI_NVCall);
case CodeGenFunction::CFITCK_DerivedCast:
return std::make_pair(SanitizerKind::SO_CFIDerivedCast,
llvm::SanStat_CFI_DerivedCast);
case CodeGenFunction::CFITCK_UnrelatedCast:
return std::make_pair(SanitizerKind::SO_CFIUnrelatedCast,
llvm::SanStat_CFI_UnrelatedCast);
case CodeGenFunction::CFITCK_ICall:
case CodeGenFunction::CFITCK_NVMFCall:
case CodeGenFunction::CFITCK_VMFCall:
llvm_unreachable("unexpected sanitizer kind");
}
llvm_unreachable("Unknown CFITypeCheckKind enum");
}
void CodeGenFunction::EmitVTablePtrCheckForCall(const CXXRecordDecl *RD,
llvm::Value *VTable,
CFITypeCheckKind TCK,
SourceLocation Loc) {
if (!SanOpts.has(SanitizerKind::CFICastStrict))
RD = LeastDerivedClassWithSameLayout(RD);
auto [Ordinal, _] = SanitizerInfoFromCFICheckKind(TCK);
SanitizerDebugLocation SanScope(this, {Ordinal},
SanitizerHandler::CFICheckFail);
EmitVTablePtrCheck(RD, VTable, TCK, Loc);
}
void CodeGenFunction::EmitVTablePtrCheckForCast(QualType T, Address Derived,
bool MayBeNull,
CFITypeCheckKind TCK,
SourceLocation Loc) {
if (!getLangOpts().CPlusPlus)
return;
const auto *ClassDecl = T->getAsCXXRecordDecl();
if (!ClassDecl)
return;
if (!ClassDecl->isCompleteDefinition() || !ClassDecl->isDynamicClass())
return;
if (!SanOpts.has(SanitizerKind::CFICastStrict))
ClassDecl = LeastDerivedClassWithSameLayout(ClassDecl);
auto [Ordinal, _] = SanitizerInfoFromCFICheckKind(TCK);
SanitizerDebugLocation SanScope(this, {Ordinal},
SanitizerHandler::CFICheckFail);
llvm::BasicBlock *ContBlock = nullptr;
if (MayBeNull) {
llvm::Value *DerivedNotNull =
Builder.CreateIsNotNull(Derived.emitRawPointer(*this), "cast.nonnull");
llvm::BasicBlock *CheckBlock = createBasicBlock("cast.check");
ContBlock = createBasicBlock("cast.cont");
Builder.CreateCondBr(DerivedNotNull, CheckBlock, ContBlock);
EmitBlock(CheckBlock);
}
llvm::Value *VTable;
std::tie(VTable, ClassDecl) =
CGM.getCXXABI().LoadVTablePtr(*this, Derived, ClassDecl);
EmitVTablePtrCheck(ClassDecl, VTable, TCK, Loc);
if (MayBeNull) {
Builder.CreateBr(ContBlock);
EmitBlock(ContBlock);
}
}
void CodeGenFunction::EmitVTablePtrCheck(const CXXRecordDecl *RD,
llvm::Value *VTable,
CFITypeCheckKind TCK,
SourceLocation Loc) {
assert(IsSanitizerScope);
if (!CGM.getCodeGenOpts().SanitizeCfiCrossDso &&
!CGM.HasHiddenLTOVisibility(RD))
return;
auto [M, SSK] = SanitizerInfoFromCFICheckKind(TCK);
std::string TypeName = RD->getQualifiedNameAsString();
if (getContext().getNoSanitizeList().containsType(
SanitizerMask::bitPosToMask(M), TypeName))
return;
EmitSanitizerStatReport(SSK);
CanQualType T = CGM.getContext().getCanonicalTagType(RD);
llvm::Metadata *MD = CGM.CreateMetadataIdentifierForType(T);
llvm::Value *TypeId = llvm::MetadataAsValue::get(getLLVMContext(), MD);
llvm::Value *TypeTest = Builder.CreateCall(
CGM.getIntrinsic(llvm::Intrinsic::type_test), {VTable, TypeId});
llvm::Constant *StaticData[] = {
llvm::ConstantInt::get(Int8Ty, TCK),
EmitCheckSourceLocation(Loc),
EmitCheckTypeDescriptor(T),
};
auto CrossDsoTypeId = CGM.CreateCrossDsoCfiTypeId(MD);
if (CGM.getCodeGenOpts().SanitizeCfiCrossDso && CrossDsoTypeId) {
EmitCfiSlowPathCheck(M, TypeTest, CrossDsoTypeId, VTable, StaticData);
return;
}
if (CGM.getCodeGenOpts().SanitizeTrap.has(M)) {
bool NoMerge = !CGM.getCodeGenOpts().SanitizeMergeHandlers.has(M);
EmitTrapCheck(TypeTest, SanitizerHandler::CFICheckFail, NoMerge);
return;
}
llvm::Value *AllVtables = llvm::MetadataAsValue::get(
CGM.getLLVMContext(),
llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
llvm::Value *ValidVtable = Builder.CreateCall(
CGM.getIntrinsic(llvm::Intrinsic::type_test), {VTable, AllVtables});
EmitCheck(std::make_pair(TypeTest, M), SanitizerHandler::CFICheckFail,
StaticData, {VTable, ValidVtable});
}
bool CodeGenFunction::ShouldEmitVTableTypeCheckedLoad(const CXXRecordDecl *RD) {
if (!CGM.getCodeGenOpts().WholeProgramVTables ||
!CGM.HasHiddenLTOVisibility(RD))
return false;
if (CGM.getCodeGenOpts().VirtualFunctionElimination)
return true;
if (!SanOpts.has(SanitizerKind::CFIVCall) ||
!CGM.getCodeGenOpts().SanitizeTrap.has(SanitizerKind::CFIVCall))
return false;
std::string TypeName = RD->getQualifiedNameAsString();
return !getContext().getNoSanitizeList().containsType(SanitizerKind::CFIVCall,
TypeName);
}
llvm::Value *CodeGenFunction::EmitVTableTypeCheckedLoad(
const CXXRecordDecl *RD, llvm::Value *VTable, llvm::Type *VTableTy,
uint64_t VTableByteOffset) {
auto CheckOrdinal = SanitizerKind::SO_CFIVCall;
auto CheckHandler = SanitizerHandler::CFICheckFail;
SanitizerDebugLocation SanScope(this, {CheckOrdinal}, CheckHandler);
EmitSanitizerStatReport(llvm::SanStat_CFI_VCall);
CanQualType T = CGM.getContext().getCanonicalTagType(RD);
llvm::Metadata *MD = CGM.CreateMetadataIdentifierForType(T);
llvm::Value *TypeId = llvm::MetadataAsValue::get(CGM.getLLVMContext(), MD);
auto CheckedLoadIntrinsic = CGM.getVTables().useRelativeLayout()
? llvm::Intrinsic::type_checked_load_relative
: llvm::Intrinsic::type_checked_load;
llvm::Value *CheckedLoad = Builder.CreateCall(
CGM.getIntrinsic(CheckedLoadIntrinsic),
{VTable, llvm::ConstantInt::get(Int32Ty, VTableByteOffset), TypeId});
llvm::Value *CheckResult = Builder.CreateExtractValue(CheckedLoad, 1);
std::string TypeName = RD->getQualifiedNameAsString();
if (SanOpts.has(SanitizerKind::CFIVCall) &&
!getContext().getNoSanitizeList().containsType(SanitizerKind::CFIVCall,
TypeName)) {
EmitCheck(std::make_pair(CheckResult, CheckOrdinal), CheckHandler, {}, {});
}
return Builder.CreateBitCast(Builder.CreateExtractValue(CheckedLoad, 0),
VTableTy);
}
void CodeGenFunction::EmitForwardingCallToLambda(
const CXXMethodDecl *callOperator, CallArgList &callArgs,
const CGFunctionInfo *calleeFnInfo, llvm::Constant *calleePtr) {
// Get the address of the call operator.
if (!calleeFnInfo)
calleeFnInfo = &CGM.getTypes().arrangeCXXMethodDeclaration(callOperator);
if (!calleePtr)
calleePtr =
CGM.GetAddrOfFunction(GlobalDecl(callOperator),
CGM.getTypes().GetFunctionType(*calleeFnInfo));
// Prepare the return slot.
const FunctionProtoType *FPT =
callOperator->getType()->castAs<FunctionProtoType>();
QualType resultType = FPT->getReturnType();
ReturnValueSlot returnSlot;
if (!resultType->isVoidType() &&
calleeFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
!hasScalarEvaluationKind(calleeFnInfo->getReturnType()))
returnSlot =
ReturnValueSlot(ReturnValue, resultType.isVolatileQualified(),
/*IsUnused=*/false, /*IsExternallyDestructed=*/true);
// We don't need to separately arrange the call arguments because
// the call can't be variadic anyway --- it's impossible to forward
// variadic arguments.
// Now emit our call.
auto callee = CGCallee::forDirect(calleePtr, GlobalDecl(callOperator));
RValue RV = EmitCall(*calleeFnInfo, callee, returnSlot, callArgs);
// If necessary, copy the returned value into the slot.
if (!resultType->isVoidType() && returnSlot.isNull()) {
if (getLangOpts().ObjCAutoRefCount && resultType->isObjCRetainableType()) {
RV = RValue::get(EmitARCRetainAutoreleasedReturnValue(RV.getScalarVal()));
}
EmitReturnOfRValue(RV, resultType);
} else
EmitBranchThroughCleanup(ReturnBlock);
}
void CodeGenFunction::EmitLambdaBlockInvokeBody() {
const BlockDecl *BD = BlockInfo->getBlockDecl();
const VarDecl *variable = BD->capture_begin()->getVariable();
const CXXRecordDecl *Lambda = variable->getType()->getAsCXXRecordDecl();
const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
if (CallOp->isVariadic()) {
// FIXME: Making this work correctly is nasty because it requires either
// cloning the body of the call operator or making the call operator
// forward.
CGM.ErrorUnsupported(CurCodeDecl, "lambda conversion to variadic function");
return;
}
// Start building arguments for forwarding call
CallArgList CallArgs;
CanQualType ThisType =
getContext().getPointerType(getContext().getCanonicalTagType(Lambda));
Address ThisPtr = GetAddrOfBlockDecl(variable);
CallArgs.add(RValue::get(getAsNaturalPointerTo(ThisPtr, ThisType)), ThisType);
// Add the rest of the parameters.
for (auto *param : BD->parameters())
EmitDelegateCallArg(CallArgs, param, param->getBeginLoc());
assert(!Lambda->isGenericLambda() &&
"generic lambda interconversion to block not implemented");
EmitForwardingCallToLambda(CallOp, CallArgs);
}
void CodeGenFunction::EmitLambdaStaticInvokeBody(const CXXMethodDecl *MD) {
if (MD->isVariadic()) {
// FIXME: Making this work correctly is nasty because it requires either
// cloning the body of the call operator or making the call operator
// forward.
CGM.ErrorUnsupported(MD, "lambda conversion to variadic function");
return;
}
const CXXRecordDecl *Lambda = MD->getParent();
// Start building arguments for forwarding call
CallArgList CallArgs;
CanQualType LambdaType = getContext().getCanonicalTagType(Lambda);
CanQualType ThisType = getContext().getPointerType(LambdaType);
Address ThisPtr = CreateMemTemp(LambdaType, "unused.capture");
CallArgs.add(RValue::get(ThisPtr.emitRawPointer(*this)), ThisType);
EmitLambdaDelegatingInvokeBody(MD, CallArgs);
}
void CodeGenFunction::EmitLambdaDelegatingInvokeBody(const CXXMethodDecl *MD,
CallArgList &CallArgs) {
// Add the rest of the forwarded parameters.
for (auto *Param : MD->parameters())
EmitDelegateCallArg(CallArgs, Param, Param->getBeginLoc());
const CXXRecordDecl *Lambda = MD->getParent();
const CXXMethodDecl *CallOp = Lambda->getLambdaCallOperator();
// For a generic lambda, find the corresponding call operator specialization
// to which the call to the static-invoker shall be forwarded.
if (Lambda->isGenericLambda()) {
assert(MD->isFunctionTemplateSpecialization());
const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
FunctionTemplateDecl *CallOpTemplate = CallOp->getDescribedFunctionTemplate();
void *InsertPos = nullptr;
FunctionDecl *CorrespondingCallOpSpecialization =
CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
assert(CorrespondingCallOpSpecialization);
CallOp = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
}
// Special lambda forwarding when there are inalloca parameters.
if (hasInAllocaArg(MD)) {
const CGFunctionInfo *ImplFnInfo = nullptr;
llvm::Function *ImplFn = nullptr;
EmitLambdaInAllocaImplFn(CallOp, &ImplFnInfo, &ImplFn);
EmitForwardingCallToLambda(CallOp, CallArgs, ImplFnInfo, ImplFn);
return;
}
EmitForwardingCallToLambda(CallOp, CallArgs);
}
void CodeGenFunction::EmitLambdaInAllocaCallOpBody(const CXXMethodDecl *MD) {
if (MD->isVariadic()) {
// FIXME: Making this work correctly is nasty because it requires either
// cloning the body of the call operator or making the call operator forward.
CGM.ErrorUnsupported(MD, "lambda conversion to variadic function");
return;
}
// Forward %this argument.
CallArgList CallArgs;
CanQualType LambdaType = getContext().getCanonicalTagType(MD->getParent());
CanQualType ThisType = getContext().getPointerType(LambdaType);
llvm::Value *ThisArg = CurFn->getArg(0);
CallArgs.add(RValue::get(ThisArg), ThisType);
EmitLambdaDelegatingInvokeBody(MD, CallArgs);
}
void CodeGenFunction::EmitLambdaInAllocaImplFn(
const CXXMethodDecl *CallOp, const CGFunctionInfo **ImplFnInfo,
llvm::Function **ImplFn) {
const CGFunctionInfo &FnInfo =
CGM.getTypes().arrangeCXXMethodDeclaration(CallOp);
llvm::Function *CallOpFn =
cast<llvm::Function>(CGM.GetAddrOfFunction(GlobalDecl(CallOp)));
// Emit function containing the original call op body. __invoke will delegate
// to this function.
SmallVector<CanQualType, 4> ArgTypes;
for (auto I = FnInfo.arg_begin(); I != FnInfo.arg_end(); ++I)
ArgTypes.push_back(I->type);
*ImplFnInfo = &CGM.getTypes().arrangeLLVMFunctionInfo(
FnInfo.getReturnType(), FnInfoOpts::IsDelegateCall, ArgTypes,
FnInfo.getExtInfo(), {}, FnInfo.getRequiredArgs());
// Create mangled name as if this was a method named __impl. If for some
// reason the name doesn't look as expected then just tack __impl to the
// front.
// TODO: Use the name mangler to produce the right name instead of using
// string replacement.
StringRef CallOpName = CallOpFn->getName();
std::string ImplName;
if (size_t Pos = CallOpName.find_first_of("<lambda"))
ImplName = ("?__impl@" + CallOpName.drop_front(Pos)).str();
else
ImplName = ("__impl" + CallOpName).str();
llvm::Function *Fn = CallOpFn->getParent()->getFunction(ImplName);
if (!Fn) {
Fn = llvm::Function::Create(CGM.getTypes().GetFunctionType(**ImplFnInfo),
llvm::GlobalValue::InternalLinkage, ImplName,
CGM.getModule());
CGM.SetInternalFunctionAttributes(CallOp, Fn, **ImplFnInfo);
const GlobalDecl &GD = GlobalDecl(CallOp);
const auto *D = cast<FunctionDecl>(GD.getDecl());
CodeGenFunction(CGM).GenerateCode(GD, Fn, **ImplFnInfo);
CGM.SetLLVMFunctionAttributesForDefinition(D, Fn);
}
*ImplFn = Fn;
}