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CGExpr.cpp
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//===--- CGExpr.cpp - Emit LLVM Code from Expressions ---------------------===//
//
// 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 to emit Expr nodes as LLVM code.
//
//===----------------------------------------------------------------------===//
#include "CGCUDARuntime.h"
#include "CGCXXABI.h"
#include "CGCall.h"
#include "CGCleanup.h"
#include "CGDebugInfo.h"
#include "CGObjCRuntime.h"
#include "CGOpenMPRuntime.h"
#include "CGRecordLayout.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "ConstantEmitter.h"
#include "TargetInfo.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/NSAPI.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/CodeGenOptions.h"
#include "clang/Basic/SourceManager.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/MatrixBuilder.h"
#include "llvm/Support/ConvertUTF.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Transforms/Utils/SanitizerStats.h"
#include <string>
using namespace clang;
using namespace CodeGen;
//===--------------------------------------------------------------------===//
// Miscellaneous Helper Methods
//===--------------------------------------------------------------------===//
llvm::Value *CodeGenFunction::EmitCastToVoidPtr(llvm::Value *value) {
unsigned addressSpace =
cast<llvm::PointerType>(value->getType())->getAddressSpace();
llvm::PointerType *destType = Int8PtrTy;
if (addressSpace)
destType = llvm::Type::getInt8PtrTy(getLLVMContext(), addressSpace);
if (value->getType() == destType) return value;
return Builder.CreateBitCast(value, destType);
}
/// CreateTempAlloca - This creates a alloca and inserts it into the entry
/// block.
Address CodeGenFunction::CreateTempAllocaWithoutCast(llvm::Type *Ty,
CharUnits Align,
const Twine &Name,
llvm::Value *ArraySize) {
auto Alloca = CreateTempAlloca(Ty, Name, ArraySize);
Alloca->setAlignment(Align.getAsAlign());
return Address(Alloca, Ty, Align);
}
/// CreateTempAlloca - This creates a alloca and inserts it into the entry
/// block. The alloca is casted to default address space if necessary.
Address CodeGenFunction::CreateTempAlloca(llvm::Type *Ty, CharUnits Align,
const Twine &Name,
llvm::Value *ArraySize,
Address *AllocaAddr) {
auto Alloca = CreateTempAllocaWithoutCast(Ty, Align, Name, ArraySize);
if (AllocaAddr)
*AllocaAddr = Alloca;
llvm::Value *V = Alloca.getPointer();
// Alloca always returns a pointer in alloca address space, which may
// be different from the type defined by the language. For example,
// in C++ the auto variables are in the default address space. Therefore
// cast alloca to the default address space when necessary.
if (getASTAllocaAddressSpace() != LangAS::Default) {
auto DestAddrSpace = getContext().getTargetAddressSpace(LangAS::Default);
llvm::IRBuilderBase::InsertPointGuard IPG(Builder);
// When ArraySize is nullptr, alloca is inserted at AllocaInsertPt,
// otherwise alloca is inserted at the current insertion point of the
// builder.
if (!ArraySize)
Builder.SetInsertPoint(getPostAllocaInsertPoint());
V = getTargetHooks().performAddrSpaceCast(
*this, V, getASTAllocaAddressSpace(), LangAS::Default,
Ty->getPointerTo(DestAddrSpace), /*non-null*/ true);
}
return Address(V, Ty, Align);
}
/// CreateTempAlloca - This creates an alloca and inserts it into the entry
/// block if \p ArraySize is nullptr, otherwise inserts it at the current
/// insertion point of the builder.
llvm::AllocaInst *CodeGenFunction::CreateTempAlloca(llvm::Type *Ty,
const Twine &Name,
llvm::Value *ArraySize) {
if (ArraySize)
return Builder.CreateAlloca(Ty, ArraySize, Name);
return new llvm::AllocaInst(Ty, CGM.getDataLayout().getAllocaAddrSpace(),
ArraySize, Name, AllocaInsertPt);
}
/// CreateDefaultAlignTempAlloca - This creates an alloca with the
/// default alignment of the corresponding LLVM type, which is *not*
/// guaranteed to be related in any way to the expected alignment of
/// an AST type that might have been lowered to Ty.
Address CodeGenFunction::CreateDefaultAlignTempAlloca(llvm::Type *Ty,
const Twine &Name) {
CharUnits Align =
CharUnits::fromQuantity(CGM.getDataLayout().getPrefTypeAlignment(Ty));
return CreateTempAlloca(Ty, Align, Name);
}
Address CodeGenFunction::CreateIRTemp(QualType Ty, const Twine &Name) {
CharUnits Align = getContext().getTypeAlignInChars(Ty);
return CreateTempAlloca(ConvertType(Ty), Align, Name);
}
Address CodeGenFunction::CreateMemTemp(QualType Ty, const Twine &Name,
Address *Alloca) {
// FIXME: Should we prefer the preferred type alignment here?
return CreateMemTemp(Ty, getContext().getTypeAlignInChars(Ty), Name, Alloca);
}
Address CodeGenFunction::CreateMemTemp(QualType Ty, CharUnits Align,
const Twine &Name, Address *Alloca) {
Address Result = CreateTempAlloca(ConvertTypeForMem(Ty), Align, Name,
/*ArraySize=*/nullptr, Alloca);
if (Ty->isConstantMatrixType()) {
auto *ArrayTy = cast<llvm::ArrayType>(Result.getElementType());
auto *VectorTy = llvm::FixedVectorType::get(ArrayTy->getElementType(),
ArrayTy->getNumElements());
Result = Address(
Builder.CreateBitCast(Result.getPointer(), VectorTy->getPointerTo()),
VectorTy, Result.getAlignment());
}
return Result;
}
Address CodeGenFunction::CreateMemTempWithoutCast(QualType Ty, CharUnits Align,
const Twine &Name) {
return CreateTempAllocaWithoutCast(ConvertTypeForMem(Ty), Align, Name);
}
Address CodeGenFunction::CreateMemTempWithoutCast(QualType Ty,
const Twine &Name) {
return CreateMemTempWithoutCast(Ty, getContext().getTypeAlignInChars(Ty),
Name);
}
/// EvaluateExprAsBool - Perform the usual unary conversions on the specified
/// expression and compare the result against zero, returning an Int1Ty value.
llvm::Value *CodeGenFunction::EvaluateExprAsBool(const Expr *E) {
PGO.setCurrentStmt(E);
if (const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>()) {
llvm::Value *MemPtr = EmitScalarExpr(E);
return CGM.getCXXABI().EmitMemberPointerIsNotNull(*this, MemPtr, MPT);
}
QualType BoolTy = getContext().BoolTy;
SourceLocation Loc = E->getExprLoc();
CGFPOptionsRAII FPOptsRAII(*this, E);
if (!E->getType()->isAnyComplexType())
return EmitScalarConversion(EmitScalarExpr(E), E->getType(), BoolTy, Loc);
return EmitComplexToScalarConversion(EmitComplexExpr(E), E->getType(), BoolTy,
Loc);
}
/// EmitIgnoredExpr - Emit code to compute the specified expression,
/// ignoring the result.
void CodeGenFunction::EmitIgnoredExpr(const Expr *E) {
if (E->isPRValue())
return (void) EmitAnyExpr(E, AggValueSlot::ignored(), true);
// Just emit it as an l-value and drop the result.
EmitLValue(E);
}
/// EmitAnyExpr - Emit code to compute the specified expression which
/// can have any type. The result is returned as an RValue struct.
/// If this is an aggregate expression, AggSlot indicates where the
/// result should be returned.
RValue CodeGenFunction::EmitAnyExpr(const Expr *E,
AggValueSlot aggSlot,
bool ignoreResult) {
switch (getEvaluationKind(E->getType())) {
case TEK_Scalar:
return RValue::get(EmitScalarExpr(E, ignoreResult));
case TEK_Complex:
return RValue::getComplex(EmitComplexExpr(E, ignoreResult, ignoreResult));
case TEK_Aggregate:
if (!ignoreResult && aggSlot.isIgnored())
aggSlot = CreateAggTemp(E->getType(), "agg-temp");
EmitAggExpr(E, aggSlot);
return aggSlot.asRValue();
}
llvm_unreachable("bad evaluation kind");
}
/// EmitAnyExprToTemp - Similar to EmitAnyExpr(), however, the result will
/// always be accessible even if no aggregate location is provided.
RValue CodeGenFunction::EmitAnyExprToTemp(const Expr *E) {
AggValueSlot AggSlot = AggValueSlot::ignored();
if (hasAggregateEvaluationKind(E->getType()))
AggSlot = CreateAggTemp(E->getType(), "agg.tmp");
return EmitAnyExpr(E, AggSlot);
}
/// EmitAnyExprToMem - Evaluate an expression into a given memory
/// location.
void CodeGenFunction::EmitAnyExprToMem(const Expr *E,
Address Location,
Qualifiers Quals,
bool IsInit) {
// FIXME: This function should take an LValue as an argument.
switch (getEvaluationKind(E->getType())) {
case TEK_Complex:
EmitComplexExprIntoLValue(E, MakeAddrLValue(Location, E->getType()),
/*isInit*/ false);
return;
case TEK_Aggregate: {
EmitAggExpr(E, AggValueSlot::forAddr(Location, Quals,
AggValueSlot::IsDestructed_t(IsInit),
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsAliased_t(!IsInit),
AggValueSlot::MayOverlap));
return;
}
case TEK_Scalar: {
RValue RV = RValue::get(EmitScalarExpr(E, /*Ignore*/ false));
LValue LV = MakeAddrLValue(Location, E->getType());
EmitStoreThroughLValue(RV, LV);
return;
}
}
llvm_unreachable("bad evaluation kind");
}
static void
pushTemporaryCleanup(CodeGenFunction &CGF, const MaterializeTemporaryExpr *M,
const Expr *E, Address ReferenceTemporary) {
// Objective-C++ ARC:
// If we are binding a reference to a temporary that has ownership, we
// need to perform retain/release operations on the temporary.
//
// FIXME: This should be looking at E, not M.
if (auto Lifetime = M->getType().getObjCLifetime()) {
switch (Lifetime) {
case Qualifiers::OCL_None:
case Qualifiers::OCL_ExplicitNone:
// Carry on to normal cleanup handling.
break;
case Qualifiers::OCL_Autoreleasing:
// Nothing to do; cleaned up by an autorelease pool.
return;
case Qualifiers::OCL_Strong:
case Qualifiers::OCL_Weak:
switch (StorageDuration Duration = M->getStorageDuration()) {
case SD_Static:
// Note: we intentionally do not register a cleanup to release
// the object on program termination.
return;
case SD_Thread:
// FIXME: We should probably register a cleanup in this case.
return;
case SD_Automatic:
case SD_FullExpression:
CodeGenFunction::Destroyer *Destroy;
CleanupKind CleanupKind;
if (Lifetime == Qualifiers::OCL_Strong) {
const ValueDecl *VD = M->getExtendingDecl();
bool Precise =
VD && isa<VarDecl>(VD) && VD->hasAttr<ObjCPreciseLifetimeAttr>();
CleanupKind = CGF.getARCCleanupKind();
Destroy = Precise ? &CodeGenFunction::destroyARCStrongPrecise
: &CodeGenFunction::destroyARCStrongImprecise;
} else {
// __weak objects always get EH cleanups; otherwise, exceptions
// could cause really nasty crashes instead of mere leaks.
CleanupKind = NormalAndEHCleanup;
Destroy = &CodeGenFunction::destroyARCWeak;
}
if (Duration == SD_FullExpression)
CGF.pushDestroy(CleanupKind, ReferenceTemporary,
M->getType(), *Destroy,
CleanupKind & EHCleanup);
else
CGF.pushLifetimeExtendedDestroy(CleanupKind, ReferenceTemporary,
M->getType(),
*Destroy, CleanupKind & EHCleanup);
return;
case SD_Dynamic:
llvm_unreachable("temporary cannot have dynamic storage duration");
}
llvm_unreachable("unknown storage duration");
}
}
CXXDestructorDecl *ReferenceTemporaryDtor = nullptr;
if (const RecordType *RT =
E->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
// Get the destructor for the reference temporary.
auto *ClassDecl = cast<CXXRecordDecl>(RT->getDecl());
if (!ClassDecl->hasTrivialDestructor())
ReferenceTemporaryDtor = ClassDecl->getDestructor();
}
if (!ReferenceTemporaryDtor)
return;
// Call the destructor for the temporary.
switch (M->getStorageDuration()) {
case SD_Static:
case SD_Thread: {
llvm::FunctionCallee CleanupFn;
llvm::Constant *CleanupArg;
if (E->getType()->isArrayType()) {
CleanupFn = CodeGenFunction(CGF.CGM).generateDestroyHelper(
ReferenceTemporary, E->getType(),
CodeGenFunction::destroyCXXObject, CGF.getLangOpts().Exceptions,
dyn_cast_or_null<VarDecl>(M->getExtendingDecl()));
CleanupArg = llvm::Constant::getNullValue(CGF.Int8PtrTy);
} else {
CleanupFn = CGF.CGM.getAddrAndTypeOfCXXStructor(
GlobalDecl(ReferenceTemporaryDtor, Dtor_Complete));
CleanupArg = cast<llvm::Constant>(ReferenceTemporary.getPointer());
}
CGF.CGM.getCXXABI().registerGlobalDtor(
CGF, *cast<VarDecl>(M->getExtendingDecl()), CleanupFn, CleanupArg);
break;
}
case SD_FullExpression:
CGF.pushDestroy(NormalAndEHCleanup, ReferenceTemporary, E->getType(),
CodeGenFunction::destroyCXXObject,
CGF.getLangOpts().Exceptions);
break;
case SD_Automatic:
CGF.pushLifetimeExtendedDestroy(NormalAndEHCleanup,
ReferenceTemporary, E->getType(),
CodeGenFunction::destroyCXXObject,
CGF.getLangOpts().Exceptions);
break;
case SD_Dynamic:
llvm_unreachable("temporary cannot have dynamic storage duration");
}
}
static Address createReferenceTemporary(CodeGenFunction &CGF,
const MaterializeTemporaryExpr *M,
const Expr *Inner,
Address *Alloca = nullptr) {
auto &TCG = CGF.getTargetHooks();
switch (M->getStorageDuration()) {
case SD_FullExpression:
case SD_Automatic: {
// If we have a constant temporary array or record try to promote it into a
// constant global under the same rules a normal constant would've been
// promoted. This is easier on the optimizer and generally emits fewer
// instructions.
QualType Ty = Inner->getType();
if (CGF.CGM.getCodeGenOpts().MergeAllConstants &&
(Ty->isArrayType() || Ty->isRecordType()) &&
CGF.CGM.isTypeConstant(Ty, true))
if (auto Init = ConstantEmitter(CGF).tryEmitAbstract(Inner, Ty)) {
auto AS = CGF.CGM.GetGlobalConstantAddressSpace();
auto *GV = new llvm::GlobalVariable(
CGF.CGM.getModule(), Init->getType(), /*isConstant=*/true,
llvm::GlobalValue::PrivateLinkage, Init, ".ref.tmp", nullptr,
llvm::GlobalValue::NotThreadLocal,
CGF.getContext().getTargetAddressSpace(AS));
CharUnits alignment = CGF.getContext().getTypeAlignInChars(Ty);
GV->setAlignment(alignment.getAsAlign());
llvm::Constant *C = GV;
if (AS != LangAS::Default)
C = TCG.performAddrSpaceCast(
CGF.CGM, GV, AS, LangAS::Default,
GV->getValueType()->getPointerTo(
CGF.getContext().getTargetAddressSpace(LangAS::Default)));
// FIXME: Should we put the new global into a COMDAT?
return Address(C, alignment);
}
return CGF.CreateMemTemp(Ty, "ref.tmp", Alloca);
}
case SD_Thread:
case SD_Static:
return CGF.CGM.GetAddrOfGlobalTemporary(M, Inner);
case SD_Dynamic:
llvm_unreachable("temporary can't have dynamic storage duration");
}
llvm_unreachable("unknown storage duration");
}
/// Helper method to check if the underlying ABI is AAPCS
static bool isAAPCS(const TargetInfo &TargetInfo) {
return TargetInfo.getABI().startswith("aapcs");
}
LValue CodeGenFunction::
EmitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *M) {
const Expr *E = M->getSubExpr();
assert((!M->getExtendingDecl() || !isa<VarDecl>(M->getExtendingDecl()) ||
!cast<VarDecl>(M->getExtendingDecl())->isARCPseudoStrong()) &&
"Reference should never be pseudo-strong!");
// FIXME: ideally this would use EmitAnyExprToMem, however, we cannot do so
// as that will cause the lifetime adjustment to be lost for ARC
auto ownership = M->getType().getObjCLifetime();
if (ownership != Qualifiers::OCL_None &&
ownership != Qualifiers::OCL_ExplicitNone) {
Address Object = createReferenceTemporary(*this, M, E);
if (auto *Var = dyn_cast<llvm::GlobalVariable>(Object.getPointer())) {
Object = Address(llvm::ConstantExpr::getBitCast(Var,
ConvertTypeForMem(E->getType())
->getPointerTo(Object.getAddressSpace())),
Object.getAlignment());
// createReferenceTemporary will promote the temporary to a global with a
// constant initializer if it can. It can only do this to a value of
// ARC-manageable type if the value is global and therefore "immune" to
// ref-counting operations. Therefore we have no need to emit either a
// dynamic initialization or a cleanup and we can just return the address
// of the temporary.
if (Var->hasInitializer())
return MakeAddrLValue(Object, M->getType(), AlignmentSource::Decl);
Var->setInitializer(CGM.EmitNullConstant(E->getType()));
}
LValue RefTempDst = MakeAddrLValue(Object, M->getType(),
AlignmentSource::Decl);
switch (getEvaluationKind(E->getType())) {
default: llvm_unreachable("expected scalar or aggregate expression");
case TEK_Scalar:
EmitScalarInit(E, M->getExtendingDecl(), RefTempDst, false);
break;
case TEK_Aggregate: {
EmitAggExpr(E, AggValueSlot::forAddr(Object,
E->getType().getQualifiers(),
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased,
AggValueSlot::DoesNotOverlap));
break;
}
}
pushTemporaryCleanup(*this, M, E, Object);
return RefTempDst;
}
SmallVector<const Expr *, 2> CommaLHSs;
SmallVector<SubobjectAdjustment, 2> Adjustments;
E = E->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
for (const auto &Ignored : CommaLHSs)
EmitIgnoredExpr(Ignored);
if (const auto *opaque = dyn_cast<OpaqueValueExpr>(E)) {
if (opaque->getType()->isRecordType()) {
assert(Adjustments.empty());
return EmitOpaqueValueLValue(opaque);
}
}
// Create and initialize the reference temporary.
Address Alloca = Address::invalid();
Address Object = createReferenceTemporary(*this, M, E, &Alloca);
if (auto *Var = dyn_cast<llvm::GlobalVariable>(
Object.getPointer()->stripPointerCasts())) {
Object = Address(llvm::ConstantExpr::getBitCast(
cast<llvm::Constant>(Object.getPointer()),
ConvertTypeForMem(E->getType())->getPointerTo()),
Object.getAlignment());
// If the temporary is a global and has a constant initializer or is a
// constant temporary that we promoted to a global, we may have already
// initialized it.
if (!Var->hasInitializer()) {
Var->setInitializer(CGM.EmitNullConstant(E->getType()));
EmitAnyExprToMem(E, Object, Qualifiers(), /*IsInit*/true);
}
} else {
switch (M->getStorageDuration()) {
case SD_Automatic:
if (auto *Size = EmitLifetimeStart(
CGM.getDataLayout().getTypeAllocSize(Alloca.getElementType()),
Alloca.getPointer())) {
pushCleanupAfterFullExpr<CallLifetimeEnd>(NormalEHLifetimeMarker,
Alloca, Size);
}
break;
case SD_FullExpression: {
if (!ShouldEmitLifetimeMarkers)
break;
// Avoid creating a conditional cleanup just to hold an llvm.lifetime.end
// marker. Instead, start the lifetime of a conditional temporary earlier
// so that it's unconditional. Don't do this with sanitizers which need
// more precise lifetime marks.
ConditionalEvaluation *OldConditional = nullptr;
CGBuilderTy::InsertPoint OldIP;
if (isInConditionalBranch() && !E->getType().isDestructedType() &&
!SanOpts.has(SanitizerKind::HWAddress) &&
!SanOpts.has(SanitizerKind::Memory) &&
!CGM.getCodeGenOpts().SanitizeAddressUseAfterScope) {
OldConditional = OutermostConditional;
OutermostConditional = nullptr;
OldIP = Builder.saveIP();
llvm::BasicBlock *Block = OldConditional->getStartingBlock();
Builder.restoreIP(CGBuilderTy::InsertPoint(
Block, llvm::BasicBlock::iterator(Block->back())));
}
if (auto *Size = EmitLifetimeStart(
CGM.getDataLayout().getTypeAllocSize(Alloca.getElementType()),
Alloca.getPointer())) {
pushFullExprCleanup<CallLifetimeEnd>(NormalEHLifetimeMarker, Alloca,
Size);
}
if (OldConditional) {
OutermostConditional = OldConditional;
Builder.restoreIP(OldIP);
}
break;
}
default:
break;
}
EmitAnyExprToMem(E, Object, Qualifiers(), /*IsInit*/true);
}
pushTemporaryCleanup(*this, M, E, Object);
// Perform derived-to-base casts and/or field accesses, to get from the
// temporary object we created (and, potentially, for which we extended
// the lifetime) to the subobject we're binding the reference to.
for (SubobjectAdjustment &Adjustment : llvm::reverse(Adjustments)) {
switch (Adjustment.Kind) {
case SubobjectAdjustment::DerivedToBaseAdjustment:
Object =
GetAddressOfBaseClass(Object, Adjustment.DerivedToBase.DerivedClass,
Adjustment.DerivedToBase.BasePath->path_begin(),
Adjustment.DerivedToBase.BasePath->path_end(),
/*NullCheckValue=*/ false, E->getExprLoc());
break;
case SubobjectAdjustment::FieldAdjustment: {
LValue LV = MakeAddrLValue(Object, E->getType(), AlignmentSource::Decl);
LV = EmitLValueForField(LV, Adjustment.Field);
assert(LV.isSimple() &&
"materialized temporary field is not a simple lvalue");
Object = LV.getAddress(*this);
break;
}
case SubobjectAdjustment::MemberPointerAdjustment: {
llvm::Value *Ptr = EmitScalarExpr(Adjustment.Ptr.RHS);
Object = EmitCXXMemberDataPointerAddress(E, Object, Ptr,
Adjustment.Ptr.MPT);
break;
}
}
}
return MakeAddrLValue(Object, M->getType(), AlignmentSource::Decl);
}
RValue
CodeGenFunction::EmitReferenceBindingToExpr(const Expr *E) {
// Emit the expression as an lvalue.
LValue LV = EmitLValue(E);
assert(LV.isSimple());
llvm::Value *Value = LV.getPointer(*this);
if (sanitizePerformTypeCheck() && !E->getType()->isFunctionType()) {
// C++11 [dcl.ref]p5 (as amended by core issue 453):
// If a glvalue to which a reference is directly bound designates neither
// an existing object or function of an appropriate type nor a region of
// storage of suitable size and alignment to contain an object of the
// reference's type, the behavior is undefined.
QualType Ty = E->getType();
EmitTypeCheck(TCK_ReferenceBinding, E->getExprLoc(), Value, Ty);
}
return RValue::get(Value);
}
/// getAccessedFieldNo - Given an encoded value and a result number, return the
/// input field number being accessed.
unsigned CodeGenFunction::getAccessedFieldNo(unsigned Idx,
const llvm::Constant *Elts) {
return cast<llvm::ConstantInt>(Elts->getAggregateElement(Idx))
->getZExtValue();
}
/// Emit the hash_16_bytes function from include/llvm/ADT/Hashing.h.
static llvm::Value *emitHash16Bytes(CGBuilderTy &Builder, llvm::Value *Low,
llvm::Value *High) {
llvm::Value *KMul = Builder.getInt64(0x9ddfea08eb382d69ULL);
llvm::Value *K47 = Builder.getInt64(47);
llvm::Value *A0 = Builder.CreateMul(Builder.CreateXor(Low, High), KMul);
llvm::Value *A1 = Builder.CreateXor(Builder.CreateLShr(A0, K47), A0);
llvm::Value *B0 = Builder.CreateMul(Builder.CreateXor(High, A1), KMul);
llvm::Value *B1 = Builder.CreateXor(Builder.CreateLShr(B0, K47), B0);
return Builder.CreateMul(B1, KMul);
}
bool CodeGenFunction::isNullPointerAllowed(TypeCheckKind TCK) {
return TCK == TCK_DowncastPointer || TCK == TCK_Upcast ||
TCK == TCK_UpcastToVirtualBase || TCK == TCK_DynamicOperation;
}
bool CodeGenFunction::isVptrCheckRequired(TypeCheckKind TCK, QualType Ty) {
CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
return (RD && RD->hasDefinition() && RD->isDynamicClass()) &&
(TCK == TCK_MemberAccess || TCK == TCK_MemberCall ||
TCK == TCK_DowncastPointer || TCK == TCK_DowncastReference ||
TCK == TCK_UpcastToVirtualBase || TCK == TCK_DynamicOperation);
}
bool CodeGenFunction::sanitizePerformTypeCheck() const {
return SanOpts.has(SanitizerKind::Null) ||
SanOpts.has(SanitizerKind::Alignment) ||
SanOpts.has(SanitizerKind::ObjectSize) ||
SanOpts.has(SanitizerKind::Vptr);
}
void CodeGenFunction::EmitTypeCheck(TypeCheckKind TCK, SourceLocation Loc,
llvm::Value *Ptr, QualType Ty,
CharUnits Alignment,
SanitizerSet SkippedChecks,
llvm::Value *ArraySize) {
if (!sanitizePerformTypeCheck())
return;
// Don't check pointers outside the default address space. The null check
// isn't correct, the object-size check isn't supported by LLVM, and we can't
// communicate the addresses to the runtime handler for the vptr check.
if (Ptr->getType()->getPointerAddressSpace())
return;
// Don't check pointers to volatile data. The behavior here is implementation-
// defined.
if (Ty.isVolatileQualified())
return;
SanitizerScope SanScope(this);
SmallVector<std::pair<llvm::Value *, SanitizerMask>, 3> Checks;
llvm::BasicBlock *Done = nullptr;
// Quickly determine whether we have a pointer to an alloca. It's possible
// to skip null checks, and some alignment checks, for these pointers. This
// can reduce compile-time significantly.
auto PtrToAlloca = dyn_cast<llvm::AllocaInst>(Ptr->stripPointerCasts());
llvm::Value *True = llvm::ConstantInt::getTrue(getLLVMContext());
llvm::Value *IsNonNull = nullptr;
bool IsGuaranteedNonNull =
SkippedChecks.has(SanitizerKind::Null) || PtrToAlloca;
bool AllowNullPointers = isNullPointerAllowed(TCK);
if ((SanOpts.has(SanitizerKind::Null) || AllowNullPointers) &&
!IsGuaranteedNonNull) {
// The glvalue must not be an empty glvalue.
IsNonNull = Builder.CreateIsNotNull(Ptr);
// The IR builder can constant-fold the null check if the pointer points to
// a constant.
IsGuaranteedNonNull = IsNonNull == True;
// Skip the null check if the pointer is known to be non-null.
if (!IsGuaranteedNonNull) {
if (AllowNullPointers) {
// When performing pointer casts, it's OK if the value is null.
// Skip the remaining checks in that case.
Done = createBasicBlock("null");
llvm::BasicBlock *Rest = createBasicBlock("not.null");
Builder.CreateCondBr(IsNonNull, Rest, Done);
EmitBlock(Rest);
} else {
Checks.push_back(std::make_pair(IsNonNull, SanitizerKind::Null));
}
}
}
if (SanOpts.has(SanitizerKind::ObjectSize) &&
!SkippedChecks.has(SanitizerKind::ObjectSize) &&
!Ty->isIncompleteType()) {
uint64_t TySize = CGM.getMinimumObjectSize(Ty).getQuantity();
llvm::Value *Size = llvm::ConstantInt::get(IntPtrTy, TySize);
if (ArraySize)
Size = Builder.CreateMul(Size, ArraySize);
// Degenerate case: new X[0] does not need an objectsize check.
llvm::Constant *ConstantSize = dyn_cast<llvm::Constant>(Size);
if (!ConstantSize || !ConstantSize->isNullValue()) {
// The glvalue must refer to a large enough storage region.
// FIXME: If Address Sanitizer is enabled, insert dynamic instrumentation
// to check this.
// FIXME: Get object address space
llvm::Type *Tys[2] = { IntPtrTy, Int8PtrTy };
llvm::Function *F = CGM.getIntrinsic(llvm::Intrinsic::objectsize, Tys);
llvm::Value *Min = Builder.getFalse();
llvm::Value *NullIsUnknown = Builder.getFalse();
llvm::Value *Dynamic = Builder.getFalse();
llvm::Value *CastAddr = Builder.CreateBitCast(Ptr, Int8PtrTy);
llvm::Value *LargeEnough = Builder.CreateICmpUGE(
Builder.CreateCall(F, {CastAddr, Min, NullIsUnknown, Dynamic}), Size);
Checks.push_back(std::make_pair(LargeEnough, SanitizerKind::ObjectSize));
}
}
uint64_t AlignVal = 0;
llvm::Value *PtrAsInt = nullptr;
if (SanOpts.has(SanitizerKind::Alignment) &&
!SkippedChecks.has(SanitizerKind::Alignment)) {
AlignVal = Alignment.getQuantity();
if (!Ty->isIncompleteType() && !AlignVal)
AlignVal = CGM.getNaturalTypeAlignment(Ty, nullptr, nullptr,
/*ForPointeeType=*/true)
.getQuantity();
// The glvalue must be suitably aligned.
if (AlignVal > 1 &&
(!PtrToAlloca || PtrToAlloca->getAlignment() < AlignVal)) {
PtrAsInt = Builder.CreatePtrToInt(Ptr, IntPtrTy);
llvm::Value *Align = Builder.CreateAnd(
PtrAsInt, llvm::ConstantInt::get(IntPtrTy, AlignVal - 1));
llvm::Value *Aligned =
Builder.CreateICmpEQ(Align, llvm::ConstantInt::get(IntPtrTy, 0));
if (Aligned != True)
Checks.push_back(std::make_pair(Aligned, SanitizerKind::Alignment));
}
}
if (Checks.size() > 0) {
// Make sure we're not losing information. Alignment needs to be a power of
// 2
assert(!AlignVal || (uint64_t)1 << llvm::Log2_64(AlignVal) == AlignVal);
llvm::Constant *StaticData[] = {
EmitCheckSourceLocation(Loc), EmitCheckTypeDescriptor(Ty),
llvm::ConstantInt::get(Int8Ty, AlignVal ? llvm::Log2_64(AlignVal) : 1),
llvm::ConstantInt::get(Int8Ty, TCK)};
EmitCheck(Checks, SanitizerHandler::TypeMismatch, StaticData,
PtrAsInt ? PtrAsInt : Ptr);
}
// If possible, check that the vptr indicates that there is a subobject of
// type Ty at offset zero within this object.
//
// C++11 [basic.life]p5,6:
// [For storage which does not refer to an object within its lifetime]
// The program has undefined behavior if:
// -- the [pointer or glvalue] is used to access a non-static data member
// or call a non-static member function
if (SanOpts.has(SanitizerKind::Vptr) &&
!SkippedChecks.has(SanitizerKind::Vptr) && isVptrCheckRequired(TCK, Ty)) {
// Ensure that the pointer is non-null before loading it. If there is no
// compile-time guarantee, reuse the run-time null check or emit a new one.
if (!IsGuaranteedNonNull) {
if (!IsNonNull)
IsNonNull = Builder.CreateIsNotNull(Ptr);
if (!Done)
Done = createBasicBlock("vptr.null");
llvm::BasicBlock *VptrNotNull = createBasicBlock("vptr.not.null");
Builder.CreateCondBr(IsNonNull, VptrNotNull, Done);
EmitBlock(VptrNotNull);
}
// Compute a hash of the mangled name of the type.
//
// FIXME: This is not guaranteed to be deterministic! Move to a
// fingerprinting mechanism once LLVM provides one. For the time
// being the implementation happens to be deterministic.
SmallString<64> MangledName;
llvm::raw_svector_ostream Out(MangledName);
CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty.getUnqualifiedType(),
Out);
// Contained in NoSanitizeList based on the mangled type.
if (!CGM.getContext().getNoSanitizeList().containsType(SanitizerKind::Vptr,
Out.str())) {
llvm::hash_code TypeHash = hash_value(Out.str());
// Load the vptr, and compute hash_16_bytes(TypeHash, vptr).
llvm::Value *Low = llvm::ConstantInt::get(Int64Ty, TypeHash);
llvm::Type *VPtrTy = llvm::PointerType::get(IntPtrTy, 0);
Address VPtrAddr(Builder.CreateBitCast(Ptr, VPtrTy), getPointerAlign());
llvm::Value *VPtrVal = Builder.CreateLoad(VPtrAddr);
llvm::Value *High = Builder.CreateZExt(VPtrVal, Int64Ty);
llvm::Value *Hash = emitHash16Bytes(Builder, Low, High);
Hash = Builder.CreateTrunc(Hash, IntPtrTy);
// Look the hash up in our cache.
const int CacheSize = 128;
llvm::Type *HashTable = llvm::ArrayType::get(IntPtrTy, CacheSize);
llvm::Value *Cache = CGM.CreateRuntimeVariable(HashTable,
"__ubsan_vptr_type_cache");
llvm::Value *Slot = Builder.CreateAnd(Hash,
llvm::ConstantInt::get(IntPtrTy,
CacheSize-1));
llvm::Value *Indices[] = { Builder.getInt32(0), Slot };
llvm::Value *CacheVal = Builder.CreateAlignedLoad(
IntPtrTy, Builder.CreateInBoundsGEP(HashTable, Cache, Indices),
getPointerAlign());
// If the hash isn't in the cache, call a runtime handler to perform the
// hard work of checking whether the vptr is for an object of the right
// type. This will either fill in the cache and return, or produce a
// diagnostic.
llvm::Value *EqualHash = Builder.CreateICmpEQ(CacheVal, Hash);
llvm::Constant *StaticData[] = {
EmitCheckSourceLocation(Loc),
EmitCheckTypeDescriptor(Ty),
CGM.GetAddrOfRTTIDescriptor(Ty.getUnqualifiedType()),
llvm::ConstantInt::get(Int8Ty, TCK)
};
llvm::Value *DynamicData[] = { Ptr, Hash };
EmitCheck(std::make_pair(EqualHash, SanitizerKind::Vptr),
SanitizerHandler::DynamicTypeCacheMiss, StaticData,
DynamicData);
}
}
if (Done) {
Builder.CreateBr(Done);
EmitBlock(Done);
}
}
/// Determine whether this expression refers to a flexible array member in a
/// struct. We disable array bounds checks for such members.
static bool isFlexibleArrayMemberExpr(const Expr *E) {
// For compatibility with existing code, we treat arrays of length 0 or
// 1 as flexible array members.
// FIXME: This is inconsistent with the warning code in SemaChecking. Unify
// the two mechanisms.
const ArrayType *AT = E->getType()->castAsArrayTypeUnsafe();
if (const auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
// FIXME: Sema doesn't treat [1] as a flexible array member if the bound
// was produced by macro expansion.
if (CAT->getSize().ugt(1))
return false;
} else if (!isa<IncompleteArrayType>(AT))
return false;
E = E->IgnoreParens();
// A flexible array member must be the last member in the class.
if (const auto *ME = dyn_cast<MemberExpr>(E)) {
// FIXME: If the base type of the member expr is not FD->getParent(),
// this should not be treated as a flexible array member access.
if (const auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
// FIXME: Sema doesn't treat a T[1] union member as a flexible array
// member, only a T[0] or T[] member gets that treatment.
if (FD->getParent()->isUnion())
return true;
RecordDecl::field_iterator FI(
DeclContext::decl_iterator(const_cast<FieldDecl *>(FD)));
return ++FI == FD->getParent()->field_end();
}
} else if (const auto *IRE = dyn_cast<ObjCIvarRefExpr>(E)) {
return IRE->getDecl()->getNextIvar() == nullptr;
}
return false;
}
llvm::Value *CodeGenFunction::LoadPassedObjectSize(const Expr *E,
QualType EltTy) {
ASTContext &C = getContext();
uint64_t EltSize = C.getTypeSizeInChars(EltTy).getQuantity();
if (!EltSize)
return nullptr;
auto *ArrayDeclRef = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts());
if (!ArrayDeclRef)
return nullptr;
auto *ParamDecl = dyn_cast<ParmVarDecl>(ArrayDeclRef->getDecl());
if (!ParamDecl)
return nullptr;
auto *POSAttr = ParamDecl->getAttr<PassObjectSizeAttr>();
if (!POSAttr)
return nullptr;
// Don't load the size if it's a lower bound.
int POSType = POSAttr->getType();
if (POSType != 0 && POSType != 1)
return nullptr;
// Find the implicit size parameter.
auto PassedSizeIt = SizeArguments.find(ParamDecl);
if (PassedSizeIt == SizeArguments.end())
return nullptr;
const ImplicitParamDecl *PassedSizeDecl = PassedSizeIt->second;
assert(LocalDeclMap.count(PassedSizeDecl) && "Passed size not loadable");
Address AddrOfSize = LocalDeclMap.find(PassedSizeDecl)->second;
llvm::Value *SizeInBytes = EmitLoadOfScalar(AddrOfSize, /*Volatile=*/false,
C.getSizeType(), E->getExprLoc());
llvm::Value *SizeOfElement =
llvm::ConstantInt::get(SizeInBytes->getType(), EltSize);
return Builder.CreateUDiv(SizeInBytes, SizeOfElement);
}
/// If Base is known to point to the start of an array, return the length of
/// that array. Return 0 if the length cannot be determined.
static llvm::Value *getArrayIndexingBound(
CodeGenFunction &CGF, const Expr *Base, QualType &IndexedType) {
// For the vector indexing extension, the bound is the number of elements.
if (const VectorType *VT = Base->getType()->getAs<VectorType>()) {
IndexedType = Base->getType();
return CGF.Builder.getInt32(VT->getNumElements());
}
Base = Base->IgnoreParens();
if (const auto *CE = dyn_cast<CastExpr>(Base)) {
if (CE->getCastKind() == CK_ArrayToPointerDecay &&
!isFlexibleArrayMemberExpr(CE->getSubExpr())) {
IndexedType = CE->getSubExpr()->getType();
const ArrayType *AT = IndexedType->castAsArrayTypeUnsafe();
if (const auto *CAT = dyn_cast<ConstantArrayType>(AT))
return CGF.Builder.getInt(CAT->getSize());
else if (const auto *VAT = dyn_cast<VariableArrayType>(AT))
return CGF.getVLASize(VAT).NumElts;
// Ignore pass_object_size here. It's not applicable on decayed pointers.
}
}
QualType EltTy{Base->getType()->getPointeeOrArrayElementType(), 0};
if (llvm::Value *POS = CGF.LoadPassedObjectSize(Base, EltTy)) {
IndexedType = Base->getType();
return POS;
}
return nullptr;
}
void CodeGenFunction::EmitBoundsCheck(const Expr *E, const Expr *Base,
llvm::Value *Index, QualType IndexType,
bool Accessed) {
assert(SanOpts.has(SanitizerKind::ArrayBounds) &&
"should not be called unless adding bounds checks");
SanitizerScope SanScope(this);
QualType IndexedType;
llvm::Value *Bound = getArrayIndexingBound(*this, Base, IndexedType);
if (!Bound)
return;
bool IndexSigned = IndexType->isSignedIntegerOrEnumerationType();
llvm::Value *IndexVal = Builder.CreateIntCast(Index, SizeTy, IndexSigned);
llvm::Value *BoundVal = Builder.CreateIntCast(Bound, SizeTy, false);
llvm::Constant *StaticData[] = {
EmitCheckSourceLocation(E->getExprLoc()),
EmitCheckTypeDescriptor(IndexedType),
EmitCheckTypeDescriptor(IndexType)
};
llvm::Value *Check = Accessed ? Builder.CreateICmpULT(IndexVal, BoundVal)