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

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//===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit Aggregate Expr nodes as LLVM code.
//
//===----------------------------------------------------------------------===//
#include "CodeGenFunction.h"
#include "CGObjCRuntime.h"
#include "CodeGenModule.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/StmtVisitor.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Intrinsics.h"
using namespace clang;
using namespace CodeGen;
//===----------------------------------------------------------------------===//
// Aggregate Expression Emitter
//===----------------------------------------------------------------------===//
namespace {
class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
CodeGenFunction &CGF;
CGBuilderTy &Builder;
AggValueSlot Dest;
/// We want to use 'dest' as the return slot except under two
/// conditions:
/// - The destination slot requires garbage collection, so we
/// need to use the GC API.
/// - The destination slot is potentially aliased.
bool shouldUseDestForReturnSlot() const {
return !(Dest.requiresGCollection() || Dest.isPotentiallyAliased());
}
ReturnValueSlot getReturnValueSlot() const {
if (!shouldUseDestForReturnSlot())
return ReturnValueSlot();
return ReturnValueSlot(Dest.getAddr(), Dest.isVolatile());
}
AggValueSlot EnsureSlot(QualType T) {
if (!Dest.isIgnored()) return Dest;
return CGF.CreateAggTemp(T, "agg.tmp.ensured");
}
void EnsureDest(QualType T) {
if (!Dest.isIgnored()) return;
Dest = CGF.CreateAggTemp(T, "agg.tmp.ensured");
}
public:
AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest)
: CGF(cgf), Builder(CGF.Builder), Dest(Dest) {
}
//===--------------------------------------------------------------------===//
// Utilities
//===--------------------------------------------------------------------===//
/// EmitAggLoadOfLValue - Given an expression with aggregate type that
/// represents a value lvalue, this method emits the address of the lvalue,
/// then loads the result into DestPtr.
void EmitAggLoadOfLValue(const Expr *E);
/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
void EmitFinalDestCopy(QualType type, const LValue &src);
void EmitFinalDestCopy(QualType type, RValue src,
CharUnits srcAlignment = CharUnits::Zero());
void EmitCopy(QualType type, const AggValueSlot &dest,
const AggValueSlot &src);
void EmitMoveFromReturnSlot(const Expr *E, RValue Src);
void EmitArrayInit(llvm::Value *DestPtr, llvm::ArrayType *AType,
QualType elementType, InitListExpr *E);
AggValueSlot::NeedsGCBarriers_t needsGC(QualType T) {
if (CGF.getLangOpts().getGC() && TypeRequiresGCollection(T))
return AggValueSlot::NeedsGCBarriers;
return AggValueSlot::DoesNotNeedGCBarriers;
}
bool TypeRequiresGCollection(QualType T);
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
void VisitStmt(Stmt *S) {
CGF.ErrorUnsupported(S, "aggregate expression");
}
void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
void VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
Visit(GE->getResultExpr());
}
void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
return Visit(E->getReplacement());
}
// l-values.
void VisitDeclRefExpr(DeclRefExpr *E) {
// For aggregates, we should always be able to emit the variable
// as an l-value unless it's a reference. This is due to the fact
// that we can't actually ever see a normal l2r conversion on an
// aggregate in C++, and in C there's no language standard
// actively preventing us from listing variables in the captures
// list of a block.
if (E->getDecl()->getType()->isReferenceType()) {
if (CodeGenFunction::ConstantEmission result
= CGF.tryEmitAsConstant(E)) {
EmitFinalDestCopy(E->getType(), result.getReferenceLValue(CGF, E));
return;
}
}
EmitAggLoadOfLValue(E);
}
void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
void VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
EmitAggLoadOfLValue(E);
}
void VisitPredefinedExpr(const PredefinedExpr *E) {
EmitAggLoadOfLValue(E);
}
// Operators.
void VisitCastExpr(CastExpr *E);
void VisitCallExpr(const CallExpr *E);
void VisitStmtExpr(const StmtExpr *E);
void VisitBinaryOperator(const BinaryOperator *BO);
void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
void VisitBinAssign(const BinaryOperator *E);
void VisitBinComma(const BinaryOperator *E);
void VisitObjCMessageExpr(ObjCMessageExpr *E);
void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
EmitAggLoadOfLValue(E);
}
void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO);
void VisitChooseExpr(const ChooseExpr *CE);
void VisitInitListExpr(InitListExpr *E);
void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
Visit(DAE->getExpr());
}
void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) {
CodeGenFunction::CXXDefaultInitExprScope Scope(CGF);
Visit(DIE->getExpr());
}
void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
void VisitCXXConstructExpr(const CXXConstructExpr *E);
void VisitLambdaExpr(LambdaExpr *E);
void VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E);
void VisitExprWithCleanups(ExprWithCleanups *E);
void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
void VisitOpaqueValueExpr(OpaqueValueExpr *E);
void VisitPseudoObjectExpr(PseudoObjectExpr *E) {
if (E->isGLValue()) {
LValue LV = CGF.EmitPseudoObjectLValue(E);
return EmitFinalDestCopy(E->getType(), LV);
}
CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType()));
}
void VisitVAArgExpr(VAArgExpr *E);
void EmitInitializationToLValue(Expr *E, LValue Address);
void EmitNullInitializationToLValue(LValue Address);
// case Expr::ChooseExprClass:
void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
void VisitAtomicExpr(AtomicExpr *E) {
CGF.EmitAtomicExpr(E, EnsureSlot(E->getType()).getAddr());
}
};
} // end anonymous namespace.
//===----------------------------------------------------------------------===//
// Utilities
//===----------------------------------------------------------------------===//
/// EmitAggLoadOfLValue - Given an expression with aggregate type that
/// represents a value lvalue, this method emits the address of the lvalue,
/// then loads the result into DestPtr.
void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
LValue LV = CGF.EmitLValue(E);
// If the type of the l-value is atomic, then do an atomic load.
if (LV.getType()->isAtomicType()) {
CGF.EmitAtomicLoad(LV, Dest);
return;
}
EmitFinalDestCopy(E->getType(), LV);
}
/// \brief True if the given aggregate type requires special GC API calls.
bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
// Only record types have members that might require garbage collection.
const RecordType *RecordTy = T->getAs<RecordType>();
if (!RecordTy) return false;
// Don't mess with non-trivial C++ types.
RecordDecl *Record = RecordTy->getDecl();
if (isa<CXXRecordDecl>(Record) &&
(cast<CXXRecordDecl>(Record)->hasNonTrivialCopyConstructor() ||
!cast<CXXRecordDecl>(Record)->hasTrivialDestructor()))
return false;
// Check whether the type has an object member.
return Record->hasObjectMember();
}
/// \brief Perform the final move to DestPtr if for some reason
/// getReturnValueSlot() didn't use it directly.
///
/// The idea is that you do something like this:
/// RValue Result = EmitSomething(..., getReturnValueSlot());
/// EmitMoveFromReturnSlot(E, Result);
///
/// If nothing interferes, this will cause the result to be emitted
/// directly into the return value slot. Otherwise, a final move
/// will be performed.
void AggExprEmitter::EmitMoveFromReturnSlot(const Expr *E, RValue src) {
if (shouldUseDestForReturnSlot()) {
// Logically, Dest.getAddr() should equal Src.getAggregateAddr().
// The possibility of undef rvalues complicates that a lot,
// though, so we can't really assert.
return;
}
// Otherwise, copy from there to the destination.
assert(Dest.getAddr() != src.getAggregateAddr());
std::pair<CharUnits, CharUnits> typeInfo =
CGF.getContext().getTypeInfoInChars(E->getType());
EmitFinalDestCopy(E->getType(), src, typeInfo.second);
}
/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
void AggExprEmitter::EmitFinalDestCopy(QualType type, RValue src,
CharUnits srcAlign) {
assert(src.isAggregate() && "value must be aggregate value!");
LValue srcLV = CGF.MakeAddrLValue(src.getAggregateAddr(), type, srcAlign);
EmitFinalDestCopy(type, srcLV);
}
/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src) {
// If Dest is ignored, then we're evaluating an aggregate expression
// in a context that doesn't care about the result. Note that loads
// from volatile l-values force the existence of a non-ignored
// destination.
if (Dest.isIgnored())
return;
AggValueSlot srcAgg =
AggValueSlot::forLValue(src, AggValueSlot::IsDestructed,
needsGC(type), AggValueSlot::IsAliased);
EmitCopy(type, Dest, srcAgg);
}
/// Perform a copy from the source into the destination.
///
/// \param type - the type of the aggregate being copied; qualifiers are
/// ignored
void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
const AggValueSlot &src) {
if (dest.requiresGCollection()) {
CharUnits sz = CGF.getContext().getTypeSizeInChars(type);
llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity());
CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
dest.getAddr(),
src.getAddr(),
size);
return;
}
// If the result of the assignment is used, copy the LHS there also.
// It's volatile if either side is. Use the minimum alignment of
// the two sides.
CGF.EmitAggregateCopy(dest.getAddr(), src.getAddr(), type,
dest.isVolatile() || src.isVolatile(),
std::min(dest.getAlignment(), src.getAlignment()));
}
/// \brief Emit the initializer for a std::initializer_list initialized with a
/// real initializer list.
void
AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) {
// Emit an array containing the elements. The array is externally destructed
// if the std::initializer_list object is.
ASTContext &Ctx = CGF.getContext();
LValue Array = CGF.EmitLValue(E->getSubExpr());
assert(Array.isSimple() && "initializer_list array not a simple lvalue");
llvm::Value *ArrayPtr = Array.getAddress();
const ConstantArrayType *ArrayType =
Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
assert(ArrayType && "std::initializer_list constructed from non-array");
// FIXME: Perform the checks on the field types in SemaInit.
RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
RecordDecl::field_iterator Field = Record->field_begin();
if (Field == Record->field_end()) {
CGF.ErrorUnsupported(E, "weird std::initializer_list");
return;
}
// Start pointer.
if (!Field->getType()->isPointerType() ||
!Ctx.hasSameType(Field->getType()->getPointeeType(),
ArrayType->getElementType())) {
CGF.ErrorUnsupported(E, "weird std::initializer_list");
return;
}
AggValueSlot Dest = EnsureSlot(E->getType());
LValue DestLV = CGF.MakeAddrLValue(Dest.getAddr(), E->getType(),
Dest.getAlignment());
LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0);
llvm::Value *IdxStart[] = { Zero, Zero };
llvm::Value *ArrayStart =
Builder.CreateInBoundsGEP(ArrayPtr, IdxStart, "arraystart");
CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start);
++Field;
if (Field == Record->field_end()) {
CGF.ErrorUnsupported(E, "weird std::initializer_list");
return;
}
llvm::Value *Size = Builder.getInt(ArrayType->getSize());
LValue EndOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
if (Field->getType()->isPointerType() &&
Ctx.hasSameType(Field->getType()->getPointeeType(),
ArrayType->getElementType())) {
// End pointer.
llvm::Value *IdxEnd[] = { Zero, Size };
llvm::Value *ArrayEnd =
Builder.CreateInBoundsGEP(ArrayPtr, IdxEnd, "arrayend");
CGF.EmitStoreThroughLValue(RValue::get(ArrayEnd), EndOrLength);
} else if (Ctx.hasSameType(Field->getType(), Ctx.getSizeType())) {
// Length.
CGF.EmitStoreThroughLValue(RValue::get(Size), EndOrLength);
} else {
CGF.ErrorUnsupported(E, "weird std::initializer_list");
return;
}
}
/// \brief Emit initialization of an array from an initializer list.
void AggExprEmitter::EmitArrayInit(llvm::Value *DestPtr, llvm::ArrayType *AType,
QualType elementType, InitListExpr *E) {
uint64_t NumInitElements = E->getNumInits();
uint64_t NumArrayElements = AType->getNumElements();
assert(NumInitElements <= NumArrayElements);
// DestPtr is an array*. Construct an elementType* by drilling
// down a level.
llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
llvm::Value *indices[] = { zero, zero };
llvm::Value *begin =
Builder.CreateInBoundsGEP(DestPtr, indices, "arrayinit.begin");
// Exception safety requires us to destroy all the
// already-constructed members if an initializer throws.
// For that, we'll need an EH cleanup.
QualType::DestructionKind dtorKind = elementType.isDestructedType();
llvm::AllocaInst *endOfInit = 0;
EHScopeStack::stable_iterator cleanup;
llvm::Instruction *cleanupDominator = 0;
if (CGF.needsEHCleanup(dtorKind)) {
// In principle we could tell the cleanup where we are more
// directly, but the control flow can get so varied here that it
// would actually be quite complex. Therefore we go through an
// alloca.
endOfInit = CGF.CreateTempAlloca(begin->getType(),
"arrayinit.endOfInit");
cleanupDominator = Builder.CreateStore(begin, endOfInit);
CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
CGF.getDestroyer(dtorKind));
cleanup = CGF.EHStack.stable_begin();
// Otherwise, remember that we didn't need a cleanup.
} else {
dtorKind = QualType::DK_none;
}
llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
// The 'current element to initialize'. The invariants on this
// variable are complicated. Essentially, after each iteration of
// the loop, it points to the last initialized element, except
// that it points to the beginning of the array before any
// elements have been initialized.
llvm::Value *element = begin;
// Emit the explicit initializers.
for (uint64_t i = 0; i != NumInitElements; ++i) {
// Advance to the next element.
if (i > 0) {
element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
// Tell the cleanup that it needs to destroy up to this
// element. TODO: some of these stores can be trivially
// observed to be unnecessary.
if (endOfInit) Builder.CreateStore(element, endOfInit);
}
LValue elementLV = CGF.MakeAddrLValue(element, elementType);
EmitInitializationToLValue(E->getInit(i), elementLV);
}
// Check whether there's a non-trivial array-fill expression.
// Note that this will be a CXXConstructExpr even if the element
// type is an array (or array of array, etc.) of class type.
Expr *filler = E->getArrayFiller();
bool hasTrivialFiller = true;
if (CXXConstructExpr *cons = dyn_cast_or_null<CXXConstructExpr>(filler)) {
assert(cons->getConstructor()->isDefaultConstructor());
hasTrivialFiller = cons->getConstructor()->isTrivial();
}
// Any remaining elements need to be zero-initialized, possibly
// using the filler expression. We can skip this if the we're
// emitting to zeroed memory.
if (NumInitElements != NumArrayElements &&
!(Dest.isZeroed() && hasTrivialFiller &&
CGF.getTypes().isZeroInitializable(elementType))) {
// Use an actual loop. This is basically
// do { *array++ = filler; } while (array != end);
// Advance to the start of the rest of the array.
if (NumInitElements) {
element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
if (endOfInit) Builder.CreateStore(element, endOfInit);
}
// Compute the end of the array.
llvm::Value *end = Builder.CreateInBoundsGEP(begin,
llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
"arrayinit.end");
llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
// Jump into the body.
CGF.EmitBlock(bodyBB);
llvm::PHINode *currentElement =
Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
currentElement->addIncoming(element, entryBB);
// Emit the actual filler expression.
LValue elementLV = CGF.MakeAddrLValue(currentElement, elementType);
if (filler)
EmitInitializationToLValue(filler, elementLV);
else
EmitNullInitializationToLValue(elementLV);
// Move on to the next element.
llvm::Value *nextElement =
Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next");
// Tell the EH cleanup that we finished with the last element.
if (endOfInit) Builder.CreateStore(nextElement, endOfInit);
// Leave the loop if we're done.
llvm::Value *done = Builder.CreateICmpEQ(nextElement, end,
"arrayinit.done");
llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
Builder.CreateCondBr(done, endBB, bodyBB);
currentElement->addIncoming(nextElement, Builder.GetInsertBlock());
CGF.EmitBlock(endBB);
}
// Leave the partial-array cleanup if we entered one.
if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator);
}
//===----------------------------------------------------------------------===//
// Visitor Methods
//===----------------------------------------------------------------------===//
void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){
Visit(E->GetTemporaryExpr());
}
void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
EmitFinalDestCopy(e->getType(), CGF.getOpaqueLValueMapping(e));
}
void
AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
if (Dest.isPotentiallyAliased() &&
E->getType().isPODType(CGF.getContext())) {
// For a POD type, just emit a load of the lvalue + a copy, because our
// compound literal might alias the destination.
EmitAggLoadOfLValue(E);
return;
}
AggValueSlot Slot = EnsureSlot(E->getType());
CGF.EmitAggExpr(E->getInitializer(), Slot);
}
/// Attempt to look through various unimportant expressions to find a
/// cast of the given kind.
static Expr *findPeephole(Expr *op, CastKind kind) {
while (true) {
op = op->IgnoreParens();
if (CastExpr *castE = dyn_cast<CastExpr>(op)) {
if (castE->getCastKind() == kind)
return castE->getSubExpr();
if (castE->getCastKind() == CK_NoOp)
continue;
}
return 0;
}
}
void AggExprEmitter::VisitCastExpr(CastExpr *E) {
switch (E->getCastKind()) {
case CK_Dynamic: {
// FIXME: Can this actually happen? We have no test coverage for it.
assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
LValue LV = CGF.EmitCheckedLValue(E->getSubExpr(),
CodeGenFunction::TCK_Load);
// FIXME: Do we also need to handle property references here?
if (LV.isSimple())
CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E));
else
CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast");
if (!Dest.isIgnored())
CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination");
break;
}
case CK_ToUnion: {
if (Dest.isIgnored()) break;
// GCC union extension
QualType Ty = E->getSubExpr()->getType();
QualType PtrTy = CGF.getContext().getPointerType(Ty);
llvm::Value *CastPtr = Builder.CreateBitCast(Dest.getAddr(),
CGF.ConvertType(PtrTy));
EmitInitializationToLValue(E->getSubExpr(),
CGF.MakeAddrLValue(CastPtr, Ty));
break;
}
case CK_DerivedToBase:
case CK_BaseToDerived:
case CK_UncheckedDerivedToBase: {
llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: "
"should have been unpacked before we got here");
}
case CK_NonAtomicToAtomic:
case CK_AtomicToNonAtomic: {
bool isToAtomic = (E->getCastKind() == CK_NonAtomicToAtomic);
// Determine the atomic and value types.
QualType atomicType = E->getSubExpr()->getType();
QualType valueType = E->getType();
if (isToAtomic) std::swap(atomicType, valueType);
assert(atomicType->isAtomicType());
assert(CGF.getContext().hasSameUnqualifiedType(valueType,
atomicType->castAs<AtomicType>()->getValueType()));
// Just recurse normally if we're ignoring the result or the
// atomic type doesn't change representation.
if (Dest.isIgnored() || !CGF.CGM.isPaddedAtomicType(atomicType)) {
return Visit(E->getSubExpr());
}
CastKind peepholeTarget =
(isToAtomic ? CK_AtomicToNonAtomic : CK_NonAtomicToAtomic);
// These two cases are reverses of each other; try to peephole them.
if (Expr *op = findPeephole(E->getSubExpr(), peepholeTarget)) {
assert(CGF.getContext().hasSameUnqualifiedType(op->getType(),
E->getType()) &&
"peephole significantly changed types?");
return Visit(op);
}
// If we're converting an r-value of non-atomic type to an r-value
// of atomic type, just emit directly into the relevant sub-object.
if (isToAtomic) {
AggValueSlot valueDest = Dest;
if (!valueDest.isIgnored() && CGF.CGM.isPaddedAtomicType(atomicType)) {
// Zero-initialize. (Strictly speaking, we only need to intialize
// the padding at the end, but this is simpler.)
if (!Dest.isZeroed())
CGF.EmitNullInitialization(Dest.getAddr(), atomicType);
// Build a GEP to refer to the subobject.
llvm::Value *valueAddr =
CGF.Builder.CreateStructGEP(valueDest.getAddr(), 0);
valueDest = AggValueSlot::forAddr(valueAddr,
valueDest.getAlignment(),
valueDest.getQualifiers(),
valueDest.isExternallyDestructed(),
valueDest.requiresGCollection(),
valueDest.isPotentiallyAliased(),
AggValueSlot::IsZeroed);
}
CGF.EmitAggExpr(E->getSubExpr(), valueDest);
return;
}
// Otherwise, we're converting an atomic type to a non-atomic type.
// Make an atomic temporary, emit into that, and then copy the value out.
AggValueSlot atomicSlot =
CGF.CreateAggTemp(atomicType, "atomic-to-nonatomic.temp");
CGF.EmitAggExpr(E->getSubExpr(), atomicSlot);
llvm::Value *valueAddr =
Builder.CreateStructGEP(atomicSlot.getAddr(), 0);
RValue rvalue = RValue::getAggregate(valueAddr, atomicSlot.isVolatile());
return EmitFinalDestCopy(valueType, rvalue);
}
case CK_LValueToRValue:
// If we're loading from a volatile type, force the destination
// into existence.
if (E->getSubExpr()->getType().isVolatileQualified()) {
EnsureDest(E->getType());
return Visit(E->getSubExpr());
}
// fallthrough
case CK_NoOp:
case CK_UserDefinedConversion:
case CK_ConstructorConversion:
assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
E->getType()) &&
"Implicit cast types must be compatible");
Visit(E->getSubExpr());
break;
case CK_LValueBitCast:
llvm_unreachable("should not be emitting lvalue bitcast as rvalue");
case CK_Dependent:
case CK_BitCast:
case CK_ArrayToPointerDecay:
case CK_FunctionToPointerDecay:
case CK_NullToPointer:
case CK_NullToMemberPointer:
case CK_BaseToDerivedMemberPointer:
case CK_DerivedToBaseMemberPointer:
case CK_MemberPointerToBoolean:
case CK_ReinterpretMemberPointer:
case CK_IntegralToPointer:
case CK_PointerToIntegral:
case CK_PointerToBoolean:
case CK_ToVoid:
case CK_VectorSplat:
case CK_IntegralCast:
case CK_IntegralToBoolean:
case CK_IntegralToFloating:
case CK_FloatingToIntegral:
case CK_FloatingToBoolean:
case CK_FloatingCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_ObjCObjectLValueCast:
case CK_FloatingRealToComplex:
case CK_FloatingComplexToReal:
case CK_FloatingComplexToBoolean:
case CK_FloatingComplexCast:
case CK_FloatingComplexToIntegralComplex:
case CK_IntegralRealToComplex:
case CK_IntegralComplexToReal:
case CK_IntegralComplexToBoolean:
case CK_IntegralComplexCast:
case CK_IntegralComplexToFloatingComplex:
case CK_ARCProduceObject:
case CK_ARCConsumeObject:
case CK_ARCReclaimReturnedObject:
case CK_ARCExtendBlockObject:
case CK_CopyAndAutoreleaseBlockObject:
case CK_BuiltinFnToFnPtr:
case CK_ZeroToOCLEvent:
llvm_unreachable("cast kind invalid for aggregate types");
}
}
void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
if (E->getCallReturnType()->isReferenceType()) {
EmitAggLoadOfLValue(E);
return;
}
RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot());
EmitMoveFromReturnSlot(E, RV);
}
void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
EmitMoveFromReturnSlot(E, RV);
}
void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
CGF.EmitIgnoredExpr(E->getLHS());
Visit(E->getRHS());
}
void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
CodeGenFunction::StmtExprEvaluation eval(CGF);
CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest);
}
void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI)
VisitPointerToDataMemberBinaryOperator(E);
else
CGF.ErrorUnsupported(E, "aggregate binary expression");
}
void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
const BinaryOperator *E) {
LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
EmitFinalDestCopy(E->getType(), LV);
}
/// Is the value of the given expression possibly a reference to or
/// into a __block variable?
static bool isBlockVarRef(const Expr *E) {
// Make sure we look through parens.
E = E->IgnoreParens();
// Check for a direct reference to a __block variable.
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
const VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl());
return (var && var->hasAttr<BlocksAttr>());
}
// More complicated stuff.
// Binary operators.
if (const BinaryOperator *op = dyn_cast<BinaryOperator>(E)) {
// For an assignment or pointer-to-member operation, just care
// about the LHS.
if (op->isAssignmentOp() || op->isPtrMemOp())
return isBlockVarRef(op->getLHS());
// For a comma, just care about the RHS.
if (op->getOpcode() == BO_Comma)
return isBlockVarRef(op->getRHS());
// FIXME: pointer arithmetic?
return false;
// Check both sides of a conditional operator.
} else if (const AbstractConditionalOperator *op
= dyn_cast<AbstractConditionalOperator>(E)) {
return isBlockVarRef(op->getTrueExpr())
|| isBlockVarRef(op->getFalseExpr());
// OVEs are required to support BinaryConditionalOperators.
} else if (const OpaqueValueExpr *op
= dyn_cast<OpaqueValueExpr>(E)) {
if (const Expr *src = op->getSourceExpr())
return isBlockVarRef(src);
// Casts are necessary to get things like (*(int*)&var) = foo().
// We don't really care about the kind of cast here, except
// we don't want to look through l2r casts, because it's okay
// to get the *value* in a __block variable.
} else if (const CastExpr *cast = dyn_cast<CastExpr>(E)) {
if (cast->getCastKind() == CK_LValueToRValue)
return false;
return isBlockVarRef(cast->getSubExpr());
// Handle unary operators. Again, just aggressively look through
// it, ignoring the operation.
} else if (const UnaryOperator *uop = dyn_cast<UnaryOperator>(E)) {
return isBlockVarRef(uop->getSubExpr());
// Look into the base of a field access.
} else if (const MemberExpr *mem = dyn_cast<MemberExpr>(E)) {
return isBlockVarRef(mem->getBase());
// Look into the base of a subscript.
} else if (const ArraySubscriptExpr *sub = dyn_cast<ArraySubscriptExpr>(E)) {
return isBlockVarRef(sub->getBase());
}
return false;
}
void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
// For an assignment to work, the value on the right has
// to be compatible with the value on the left.
assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
E->getRHS()->getType())
&& "Invalid assignment");
// If the LHS might be a __block variable, and the RHS can
// potentially cause a block copy, we need to evaluate the RHS first
// so that the assignment goes the right place.
// This is pretty semantically fragile.
if (isBlockVarRef(E->getLHS()) &&
E->getRHS()->HasSideEffects(CGF.getContext())) {
// Ensure that we have a destination, and evaluate the RHS into that.
EnsureDest(E->getRHS()->getType());
Visit(E->getRHS());
// Now emit the LHS and copy into it.
LValue LHS = CGF.EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store);
// That copy is an atomic copy if the LHS is atomic.
if (LHS.getType()->isAtomicType()) {
CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
return;
}
EmitCopy(E->getLHS()->getType(),
AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
needsGC(E->getLHS()->getType()),
AggValueSlot::IsAliased),
Dest);
return;
}
LValue LHS = CGF.EmitLValue(E->getLHS());
// If we have an atomic type, evaluate into the destination and then
// do an atomic copy.
if (LHS.getType()->isAtomicType()) {
EnsureDest(E->getRHS()->getType());
Visit(E->getRHS());
CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
return;
}
// Codegen the RHS so that it stores directly into the LHS.
AggValueSlot LHSSlot =
AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
needsGC(E->getLHS()->getType()),
AggValueSlot::IsAliased);
// A non-volatile aggregate destination might have volatile member.
if (!LHSSlot.isVolatile() &&
CGF.hasVolatileMember(E->getLHS()->getType()))
LHSSlot.setVolatile(true);
CGF.EmitAggExpr(E->getRHS(), LHSSlot);
// Copy into the destination if the assignment isn't ignored.
EmitFinalDestCopy(E->getType(), LHS);
}
void AggExprEmitter::
VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
// Bind the common expression if necessary.
CodeGenFunction::OpaqueValueMapping binding(CGF, E);
CodeGenFunction::ConditionalEvaluation eval(CGF);
CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
// Save whether the destination's lifetime is externally managed.
bool isExternallyDestructed = Dest.isExternallyDestructed();
eval.begin(CGF);
CGF.EmitBlock(LHSBlock);
Visit(E->getTrueExpr());
eval.end(CGF);
assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!");
CGF.Builder.CreateBr(ContBlock);
// If the result of an agg expression is unused, then the emission
// of the LHS might need to create a destination slot. That's fine
// with us, and we can safely emit the RHS into the same slot, but
// we shouldn't claim that it's already being destructed.
Dest.setExternallyDestructed(isExternallyDestructed);
eval.begin(CGF);
CGF.EmitBlock(RHSBlock);
Visit(E->getFalseExpr());
eval.end(CGF);
CGF.EmitBlock(ContBlock);
}
void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
Visit(CE->getChosenSubExpr());
}
void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
if (!ArgPtr) {
CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
return;
}
EmitFinalDestCopy(VE->getType(), CGF.MakeAddrLValue(ArgPtr, VE->getType()));
}
void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
// Ensure that we have a slot, but if we already do, remember
// whether it was externally destructed.
bool wasExternallyDestructed = Dest.isExternallyDestructed();
EnsureDest(E->getType());
// We're going to push a destructor if there isn't already one.
Dest.setExternallyDestructed();
Visit(E->getSubExpr());
// Push that destructor we promised.
if (!wasExternallyDestructed)
CGF.EmitCXXTemporary(E->getTemporary(), E->getType(), Dest.getAddr());
}
void
AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
AggValueSlot Slot = EnsureSlot(E->getType());
CGF.EmitCXXConstructExpr(E, Slot);
}
void
AggExprEmitter::VisitLambdaExpr(LambdaExpr *E) {
AggValueSlot Slot = EnsureSlot(E->getType());
CGF.EmitLambdaExpr(E, Slot);
}
void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
CGF.enterFullExpression(E);
CodeGenFunction::RunCleanupsScope cleanups(CGF);
Visit(E->getSubExpr());
}
void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
QualType T = E->getType();
AggValueSlot Slot = EnsureSlot(T);
EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T));
}
void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
QualType T = E->getType();
AggValueSlot Slot = EnsureSlot(T);
EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T));
}
/// isSimpleZero - If emitting this value will obviously just cause a store of
/// zero to memory, return true. This can return false if uncertain, so it just
/// handles simple cases.
static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
E = E->IgnoreParens();
// 0
if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
return IL->getValue() == 0;
// +0.0
if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E))
return FL->getValue().isPosZero();
// int()
if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) &&
CGF.getTypes().isZeroInitializable(E->getType()))
return true;
// (int*)0 - Null pointer expressions.
if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
return ICE->getCastKind() == CK_NullToPointer;
// '\0'
if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
return CL->getValue() == 0;
// Otherwise, hard case: conservatively return false.
return false;
}
void
AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
QualType type = LV.getType();
// FIXME: Ignore result?
// FIXME: Are initializers affected by volatile?
if (Dest.isZeroed() && isSimpleZero(E, CGF)) {
// Storing "i32 0" to a zero'd memory location is a noop.
return;
} else if (isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) {
return EmitNullInitializationToLValue(LV);
} else if (type->isReferenceType()) {
RValue RV = CGF.EmitReferenceBindingToExpr(E);
return CGF.EmitStoreThroughLValue(RV, LV);
}
switch (CGF.getEvaluationKind(type)) {
case TEK_Complex:
CGF.EmitComplexExprIntoLValue(E, LV, /*isInit*/ true);
return;
case TEK_Aggregate:
CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV,
AggValueSlot::IsDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased,
Dest.isZeroed()));
return;
case TEK_Scalar:
if (LV.isSimple()) {
CGF.EmitScalarInit(E, /*D=*/0, LV, /*Captured=*/false);
} else {
CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
}
return;
}
llvm_unreachable("bad evaluation kind");
}
void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) {
QualType type = lv.getType();
// If the destination slot is already zeroed out before the aggregate is
// copied into it, we don't have to emit any zeros here.
if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type))
return;
if (CGF.hasScalarEvaluationKind(type)) {
// For non-aggregates, we can store the appropriate null constant.
llvm::Value *null = CGF.CGM.EmitNullConstant(type);
// Note that the following is not equivalent to
// EmitStoreThroughBitfieldLValue for ARC types.
if (lv.isBitField()) {
CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv);
} else {
assert(lv.isSimple());
CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true);
}
} else {
// There's a potential optimization opportunity in combining
// memsets; that would be easy for arrays, but relatively
// difficult for structures with the current code.
CGF.EmitNullInitialization(lv.getAddress(), lv.getType());
}
}
void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
#if 0
// FIXME: Assess perf here? Figure out what cases are worth optimizing here
// (Length of globals? Chunks of zeroed-out space?).
//
// If we can, prefer a copy from a global; this is a lot less code for long
// globals, and it's easier for the current optimizers to analyze.
if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
llvm::GlobalVariable* GV =
new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
llvm::GlobalValue::InternalLinkage, C, "");
EmitFinalDestCopy(E->getType(), CGF.MakeAddrLValue(GV, E->getType()));
return;
}
#endif
if (E->hadArrayRangeDesignator())
CGF.ErrorUnsupported(E, "GNU array range designator extension");
AggValueSlot Dest = EnsureSlot(E->getType());
LValue DestLV = CGF.MakeAddrLValue(Dest.getAddr(), E->getType(),
Dest.getAlignment());
// Handle initialization of an array.
if (E->getType()->isArrayType()) {
if (E->isStringLiteralInit())
return Visit(E->getInit(0));
QualType elementType =
CGF.getContext().getAsArrayType(E->getType())->getElementType();
llvm::PointerType *APType =
cast<llvm::PointerType>(Dest.getAddr()->getType());
llvm::ArrayType *AType =
cast<llvm::ArrayType>(APType->getElementType());
EmitArrayInit(Dest.getAddr(), AType, elementType, E);
return;
}
assert(E->getType()->isRecordType() && "Only support structs/unions here!");
// Do struct initialization; this code just sets each individual member
// to the approprate value. This makes bitfield support automatic;
// the disadvantage is that the generated code is more difficult for
// the optimizer, especially with bitfields.
unsigned NumInitElements = E->getNumInits();
RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
// Prepare a 'this' for CXXDefaultInitExprs.
CodeGenFunction::FieldConstructionScope FCS(CGF, Dest.getAddr());
if (record->isUnion()) {
// Only initialize one field of a union. The field itself is
// specified by the initializer list.
if (!E->getInitializedFieldInUnion()) {
// Empty union; we have nothing to do.
#ifndef NDEBUG
// Make sure that it's really an empty and not a failure of
// semantic analysis.
for (RecordDecl::field_iterator Field = record->field_begin(),
FieldEnd = record->field_end();
Field != FieldEnd; ++Field)
assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
#endif
return;
}
// FIXME: volatility
FieldDecl *Field = E->getInitializedFieldInUnion();
LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestLV, Field);
if (NumInitElements) {
// Store the initializer into the field
EmitInitializationToLValue(E->getInit(0), FieldLoc);
} else {
// Default-initialize to null.
EmitNullInitializationToLValue(FieldLoc);
}
return;
}
// We'll need to enter cleanup scopes in case any of the member
// initializers throw an exception.
SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
llvm::Instruction *cleanupDominator = 0;
// Here we iterate over the fields; this makes it simpler to both
// default-initialize fields and skip over unnamed fields.
unsigned curInitIndex = 0;
for (RecordDecl::field_iterator field = record->field_begin(),
fieldEnd = record->field_end();
field != fieldEnd; ++field) {
// We're done once we hit the flexible array member.
if (field->getType()->isIncompleteArrayType())
break;
// Always skip anonymous bitfields.
if (field->isUnnamedBitfield())
continue;
// We're done if we reach the end of the explicit initializers, we
// have a zeroed object, and the rest of the fields are
// zero-initializable.
if (curInitIndex == NumInitElements && Dest.isZeroed() &&
CGF.getTypes().isZeroInitializable(E->getType()))
break;
LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, *field);
// We never generate write-barries for initialized fields.
LV.setNonGC(true);
if (curInitIndex < NumInitElements) {
// Store the initializer into the field.
EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
} else {
// We're out of initalizers; default-initialize to null
EmitNullInitializationToLValue(LV);
}
// Push a destructor if necessary.
// FIXME: if we have an array of structures, all explicitly
// initialized, we can end up pushing a linear number of cleanups.
bool pushedCleanup = false;
if (QualType::DestructionKind dtorKind
= field->getType().isDestructedType()) {
assert(LV.isSimple());
if (CGF.needsEHCleanup(dtorKind)) {
if (!cleanupDominator)
cleanupDominator = CGF.Builder.CreateUnreachable(); // placeholder
CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
CGF.getDestroyer(dtorKind), false);
cleanups.push_back(CGF.EHStack.stable_begin());
pushedCleanup = true;
}
}
// If the GEP didn't get used because of a dead zero init or something
// else, clean it up for -O0 builds and general tidiness.
if (!pushedCleanup && LV.isSimple())
if (llvm::GetElementPtrInst *GEP =
dyn_cast<llvm::GetElementPtrInst>(LV.getAddress()))
if (GEP->use_empty())
GEP->eraseFromParent();
}
// Deactivate all the partial cleanups in reverse order, which
// generally means popping them.
for (unsigned i = cleanups.size(); i != 0; --i)
CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator);
// Destroy the placeholder if we made one.
if (cleanupDominator)
cleanupDominator->eraseFromParent();
}
//===----------------------------------------------------------------------===//
// Entry Points into this File
//===----------------------------------------------------------------------===//
/// GetNumNonZeroBytesInInit - Get an approximate count of the number of
/// non-zero bytes that will be stored when outputting the initializer for the
/// specified initializer expression.
static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
E = E->IgnoreParens();
// 0 and 0.0 won't require any non-zero stores!
if (isSimpleZero(E, CGF)) return CharUnits::Zero();
// If this is an initlist expr, sum up the size of sizes of the (present)
// elements. If this is something weird, assume the whole thing is non-zero.
const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
if (ILE == 0 || !CGF.getTypes().isZeroInitializable(ILE->getType()))
return CGF.getContext().getTypeSizeInChars(E->getType());
// InitListExprs for structs have to be handled carefully. If there are
// reference members, we need to consider the size of the reference, not the
// referencee. InitListExprs for unions and arrays can't have references.
if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
if (!RT->isUnionType()) {
RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
CharUnits NumNonZeroBytes = CharUnits::Zero();
unsigned ILEElement = 0;
for (RecordDecl::field_iterator Field = SD->field_begin(),
FieldEnd = SD->field_end(); Field != FieldEnd; ++Field) {
// We're done once we hit the flexible array member or run out of
// InitListExpr elements.
if (Field->getType()->isIncompleteArrayType() ||
ILEElement == ILE->getNumInits())
break;
if (Field->isUnnamedBitfield())
continue;
const Expr *E = ILE->getInit(ILEElement++);
// Reference values are always non-null and have the width of a pointer.
if (Field->getType()->isReferenceType())
NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
CGF.getTarget().getPointerWidth(0));
else
NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
}
return NumNonZeroBytes;
}
}
CharUnits NumNonZeroBytes = CharUnits::Zero();
for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
return NumNonZeroBytes;
}
/// CheckAggExprForMemSetUse - If the initializer is large and has a lot of
/// zeros in it, emit a memset and avoid storing the individual zeros.
///
static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
CodeGenFunction &CGF) {
// If the slot is already known to be zeroed, nothing to do. Don't mess with
// volatile stores.
if (Slot.isZeroed() || Slot.isVolatile() || Slot.getAddr() == 0) return;
// C++ objects with a user-declared constructor don't need zero'ing.
if (CGF.getLangOpts().CPlusPlus)
if (const RecordType *RT = CGF.getContext()
.getBaseElementType(E->getType())->getAs<RecordType>()) {
const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
if (RD->hasUserDeclaredConstructor())
return;
}
// If the type is 16-bytes or smaller, prefer individual stores over memset.
std::pair<CharUnits, CharUnits> TypeInfo =
CGF.getContext().getTypeInfoInChars(E->getType());
if (TypeInfo.first <= CharUnits::fromQuantity(16))
return;
// Check to see if over 3/4 of the initializer are known to be zero. If so,
// we prefer to emit memset + individual stores for the rest.
CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF);
if (NumNonZeroBytes*4 > TypeInfo.first)
return;
// Okay, it seems like a good idea to use an initial memset, emit the call.
llvm::Constant *SizeVal = CGF.Builder.getInt64(TypeInfo.first.getQuantity());
CharUnits Align = TypeInfo.second;
llvm::Value *Loc = Slot.getAddr();
Loc = CGF.Builder.CreateBitCast(Loc, CGF.Int8PtrTy);
CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal,
Align.getQuantity(), false);
// Tell the AggExprEmitter that the slot is known zero.
Slot.setZeroed();
}
/// EmitAggExpr - Emit the computation of the specified expression of aggregate
/// type. The result is computed into DestPtr. Note that if DestPtr is null,
/// the value of the aggregate expression is not needed. If VolatileDest is
/// true, DestPtr cannot be 0.
void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot) {
assert(E && hasAggregateEvaluationKind(E->getType()) &&
"Invalid aggregate expression to emit");
assert((Slot.getAddr() != 0 || Slot.isIgnored()) &&
"slot has bits but no address");
// Optimize the slot if possible.
CheckAggExprForMemSetUse(Slot, E, *this);
AggExprEmitter(*this, Slot).Visit(const_cast<Expr*>(E));
}
LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
assert(hasAggregateEvaluationKind(E->getType()) && "Invalid argument!");
llvm::Value *Temp = CreateMemTemp(E->getType());
LValue LV = MakeAddrLValue(Temp, E->getType());
EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
AggValueSlot::DoesNotNeedGCBarriers,
AggValueSlot::IsNotAliased));
return LV;
}
void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
llvm::Value *SrcPtr, QualType Ty,
bool isVolatile,
CharUnits alignment,
bool isAssignment) {
assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
if (getLangOpts().CPlusPlus) {
if (const RecordType *RT = Ty->getAs<RecordType>()) {
CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
assert((Record->hasTrivialCopyConstructor() ||
Record->hasTrivialCopyAssignment() ||
Record->hasTrivialMoveConstructor() ||
Record->hasTrivialMoveAssignment()) &&
"Trying to aggregate-copy a type without a trivial copy/move "
"constructor or assignment operator");
// Ignore empty classes in C++.
if (Record->isEmpty())
return;
}
}
// Aggregate assignment turns into llvm.memcpy. This is almost valid per
// C99 6.5.16.1p3, which states "If the value being stored in an object is
// read from another object that overlaps in anyway the storage of the first
// object, then the overlap shall be exact and the two objects shall have
// qualified or unqualified versions of a compatible type."
//
// memcpy is not defined if the source and destination pointers are exactly
// equal, but other compilers do this optimization, and almost every memcpy
// implementation handles this case safely. If there is a libc that does not
// safely handle this, we can add a target hook.
// Get data size and alignment info for this aggregate. If this is an
// assignment don't copy the tail padding. Otherwise copying it is fine.
std::pair<CharUnits, CharUnits> TypeInfo;
if (isAssignment)
TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty);
else
TypeInfo = getContext().getTypeInfoInChars(Ty);
if (alignment.isZero())
alignment = TypeInfo.second;
// FIXME: Handle variable sized types.
// FIXME: If we have a volatile struct, the optimizer can remove what might
// appear to be `extra' memory ops:
//
// volatile struct { int i; } a, b;
//
// int main() {
// a = b;
// a = b;
// }
//
// we need to use a different call here. We use isVolatile to indicate when
// either the source or the destination is volatile.
llvm::PointerType *DPT = cast<llvm::PointerType>(DestPtr->getType());
llvm::Type *DBP =
llvm::Type::getInt8PtrTy(getLLVMContext(), DPT->getAddressSpace());
DestPtr = Builder.CreateBitCast(DestPtr, DBP);
llvm::PointerType *SPT = cast<llvm::PointerType>(SrcPtr->getType());
llvm::Type *SBP =
llvm::Type::getInt8PtrTy(getLLVMContext(), SPT->getAddressSpace());
SrcPtr = Builder.CreateBitCast(SrcPtr, SBP);
// Don't do any of the memmove_collectable tests if GC isn't set.
if (CGM.getLangOpts().getGC() == LangOptions::NonGC) {
// fall through
} else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
RecordDecl *Record = RecordTy->getDecl();
if (Record->hasObjectMember()) {
CharUnits size = TypeInfo.first;
llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size.getQuantity());
CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
SizeVal);
return;
}
} else if (Ty->isArrayType()) {
QualType BaseType = getContext().getBaseElementType(Ty);
if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) {
if (RecordTy->getDecl()->hasObjectMember()) {
CharUnits size = TypeInfo.first;
llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
llvm::Value *SizeVal =
llvm::ConstantInt::get(SizeTy, size.getQuantity());
CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
SizeVal);
return;
}
}
}
// Determine the metadata to describe the position of any padding in this
// memcpy, as well as the TBAA tags for the members of the struct, in case
// the optimizer wishes to expand it in to scalar memory operations.
llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty);
Builder.CreateMemCpy(DestPtr, SrcPtr,
llvm::ConstantInt::get(IntPtrTy,
TypeInfo.first.getQuantity()),
alignment.getQuantity(), isVolatile,
/*TBAATag=*/0, TBAAStructTag);
}
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