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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 "CodeGenModule.h"
#include "CGObjCRuntime.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/StmtVisitor.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Intrinsics.h"
using namespace clang;
using namespace CodeGen;
//===----------------------------------------------------------------------===//
// Aggregate Expression Emitter
//===----------------------------------------------------------------------===//
namespace {
class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
CodeGenFunction &CGF;
CGBuilderTy &Builder;
AggValueSlot Dest;
bool IgnoreResult;
ReturnValueSlot getReturnValueSlot() const {
// If the destination slot requires garbage collection, we can't
// use the real return value slot, because we have to use the GC
// API.
if (Dest.requiresGCollection()) return ReturnValueSlot();
return ReturnValueSlot(Dest.getAddr(), Dest.isVolatile());
}
AggValueSlot EnsureSlot(QualType T) {
if (!Dest.isIgnored()) return Dest;
return CGF.CreateAggTemp(T, "agg.tmp.ensured");
}
public:
AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest,
bool ignore)
: CGF(cgf), Builder(CGF.Builder), Dest(Dest),
IgnoreResult(ignore) {
}
//===--------------------------------------------------------------------===//
// 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(const Expr *E, LValue Src, bool Ignore = false);
void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false);
void EmitGCMove(const Expr *E, RValue Src);
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 *DRE) { EmitAggLoadOfLValue(DRE); }
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 VisitBlockDeclRefExpr(const BlockDeclRefExpr *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 VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *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 VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
void VisitCXXConstructExpr(const CXXConstructExpr *E);
void VisitExprWithCleanups(ExprWithCleanups *E);
void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
void VisitOpaqueValueExpr(OpaqueValueExpr *E);
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); }
};
} // 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);
EmitFinalDestCopy(E, 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)->hasTrivialCopyConstructor() ||
!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 RequiresGCollection is set.
///
/// The idea is that you do something like this:
/// RValue Result = EmitSomething(..., getReturnValueSlot());
/// EmitGCMove(E, Result);
/// If GC doesn't interfere, this will cause the result to be emitted
/// directly into the return value slot. If GC does interfere, a final
/// move will be performed.
void AggExprEmitter::EmitGCMove(const Expr *E, RValue Src) {
if (Dest.requiresGCollection()) {
CharUnits size = CGF.getContext().getTypeSizeInChars(E->getType());
llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType());
llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size.getQuantity());
CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF, Dest.getAddr(),
Src.getAggregateAddr(),
SizeVal);
}
}
/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) {
assert(Src.isAggregate() && "value must be aggregate value!");
// If Dest is ignored, then we're evaluating an aggregate expression
// in a context (like an expression statement) that doesn't care
// about the result. C says that an lvalue-to-rvalue conversion is
// performed in these cases; C++ says that it is not. In either
// case, we don't actually need to do anything unless the value is
// volatile.
if (Dest.isIgnored()) {
if (!Src.isVolatileQualified() ||
CGF.CGM.getLangOptions().CPlusPlus ||
(IgnoreResult && Ignore))
return;
// If the source is volatile, we must read from it; to do that, we need
// some place to put it.
Dest = CGF.CreateAggTemp(E->getType(), "agg.tmp");
}
if (Dest.requiresGCollection()) {
CharUnits size = CGF.getContext().getTypeSizeInChars(E->getType());
llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType());
llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size.getQuantity());
CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
Dest.getAddr(),
Src.getAggregateAddr(),
SizeVal);
return;
}
// If the result of the assignment is used, copy the LHS there also.
// FIXME: Pass VolatileDest as well. I think we also need to merge volatile
// from the source as well, as we can't eliminate it if either operand
// is volatile, unless copy has volatile for both source and destination..
CGF.EmitAggregateCopy(Dest.getAddr(), Src.getAggregateAddr(), E->getType(),
Dest.isVolatile()|Src.isVolatileQualified());
}
/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) {
assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc");
EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(),
Src.isVolatileQualified()),
Ignore);
}
//===----------------------------------------------------------------------===//
// Visitor Methods
//===----------------------------------------------------------------------===//
void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){
Visit(E->GetTemporaryExpr());
}
void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
EmitFinalDestCopy(e, CGF.getOpaqueLValueMapping(e));
}
void
AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
if (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.
// FIXME: This is a band-aid; the real problem appears to be in our handling
// of assignments, where we store directly into the LHS without checking
// whether anything in the RHS aliases.
EmitAggLoadOfLValue(E);
return;
}
AggValueSlot Slot = EnsureSlot(E->getType());
CGF.EmitAggExpr(E->getInitializer(), Slot);
}
void AggExprEmitter::VisitCastExpr(CastExpr *E) {
switch (E->getCastKind()) {
case CK_Dynamic: {
assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
LValue LV = CGF.EmitCheckedLValue(E->getSubExpr());
// 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: {
assert(0 && "cannot perform hierarchy conversion in EmitAggExpr: "
"should have been unpacked before we got here");
break;
}
case CK_GetObjCProperty: {
LValue LV = CGF.EmitLValue(E->getSubExpr());
assert(LV.isPropertyRef());
RValue RV = CGF.EmitLoadOfPropertyRefLValue(LV, getReturnValueSlot());
EmitGCMove(E, RV);
break;
}
case CK_LValueToRValue: // hope for downstream optimization
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");
break;
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_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_AnyPointerToObjCPointerCast:
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_ObjCProduceObject:
case CK_ObjCConsumeObject:
case CK_ObjCReclaimReturnedObject:
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());
EmitGCMove(E, RV);
}
void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
EmitGCMove(E, RV);
}
void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
llvm_unreachable("direct property access not surrounded by "
"lvalue-to-rvalue cast");
}
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, LV);
}
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 (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->getLHS()))
if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl()))
if (VD->hasAttr<BlocksAttr>() &&
E->getRHS()->HasSideEffects(CGF.getContext())) {
// When __block variable on LHS, the RHS must be evaluated first
// as it may change the 'forwarding' field via call to Block_copy.
LValue RHS = CGF.EmitLValue(E->getRHS());
LValue LHS = CGF.EmitLValue(E->getLHS());
bool GCollection = false;
if (CGF.getContext().getLangOptions().getGCMode())
GCollection = TypeRequiresGCollection(E->getLHS()->getType());
Dest = AggValueSlot::forLValue(LHS, true, GCollection);
EmitFinalDestCopy(E, RHS, true);
return;
}
LValue LHS = CGF.EmitLValue(E->getLHS());
// We have to special case property setters, otherwise we must have
// a simple lvalue (no aggregates inside vectors, bitfields).
if (LHS.isPropertyRef()) {
const ObjCPropertyRefExpr *RE = LHS.getPropertyRefExpr();
QualType ArgType = RE->getSetterArgType();
RValue Src;
if (ArgType->isReferenceType())
Src = CGF.EmitReferenceBindingToExpr(E->getRHS(), 0);
else {
AggValueSlot Slot = EnsureSlot(E->getRHS()->getType());
CGF.EmitAggExpr(E->getRHS(), Slot);
Src = Slot.asRValue();
}
CGF.EmitStoreThroughPropertyRefLValue(Src, LHS);
} else {
bool GCollection = false;
if (CGF.getContext().getLangOptions().getGCMode())
GCollection = TypeRequiresGCollection(E->getLHS()->getType());
// Codegen the RHS so that it stores directly into the LHS.
AggValueSlot LHSSlot = AggValueSlot::forLValue(LHS, true,
GCollection);
CGF.EmitAggExpr(E->getRHS(), LHSSlot, false);
EmitFinalDestCopy(E, LHS, true);
}
}
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 DestLifetimeManaged = Dest.isLifetimeExternallyManaged();
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 its lifetime is externally managed.
Dest.setLifetimeExternallyManaged(DestLifetimeManaged);
eval.begin(CGF);
CGF.EmitBlock(RHSBlock);
Visit(E->getFalseExpr());
eval.end(CGF);
CGF.EmitBlock(ContBlock);
}
void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
Visit(CE->getChosenSubExpr(CGF.getContext()));
}
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, CGF.MakeAddrLValue(ArgPtr, VE->getType()));
}
void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
// Ensure that we have a slot, but if we already do, remember
// whether its lifetime was externally managed.
bool WasManaged = Dest.isLifetimeExternallyManaged();
Dest = EnsureSlot(E->getType());
Dest.setLifetimeExternallyManaged();
Visit(E->getSubExpr());
// Set up the temporary's destructor if its lifetime wasn't already
// being managed.
if (!WasManaged)
CGF.EmitCXXTemporary(E->getTemporary(), Dest.getAddr());
}
void
AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
AggValueSlot Slot = EnsureSlot(E->getType());
CGF.EmitCXXConstructExpr(E, Slot);
}
void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
CGF.EmitExprWithCleanups(E, Dest);
}
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.
} else if (isa<ImplicitValueInitExpr>(E)) {
EmitNullInitializationToLValue(LV);
} else if (type->isReferenceType()) {
RValue RV = CGF.EmitReferenceBindingToExpr(E, /*InitializedDecl=*/0);
CGF.EmitStoreThroughLValue(RV, LV);
} else if (type->isAnyComplexType()) {
CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
} else if (CGF.hasAggregateLLVMType(type)) {
CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV, true, false,
Dest.isZeroed()));
} else if (LV.isSimple()) {
CGF.EmitScalarInit(E, /*D=*/0, LV, /*Captured=*/false);
} else {
CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
}
}
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.hasAggregateLLVMType(type)) {
// For non-aggregates, we can store zero
llvm::Value *null = llvm::Constant::getNullValue(CGF.ConvertType(type));
CGF.EmitStoreThroughLValue(RValue::get(null), lv);
} 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, CGF.MakeAddrLValue(GV, E->getType()));
return;
}
#endif
if (E->hadArrayRangeDesignator())
CGF.ErrorUnsupported(E, "GNU array range designator extension");
llvm::Value *DestPtr = Dest.getAddr();
// Handle initialization of an array.
if (E->getType()->isArrayType()) {
llvm::PointerType *APType =
cast<llvm::PointerType>(DestPtr->getType());
llvm::ArrayType *AType =
cast<llvm::ArrayType>(APType->getElementType());
uint64_t NumInitElements = E->getNumInits();
if (E->getNumInits() > 0) {
QualType T1 = E->getType();
QualType T2 = E->getInit(0)->getType();
if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
EmitAggLoadOfLValue(E->getInit(0));
return;
}
}
uint64_t NumArrayElements = AType->getNumElements();
assert(NumInitElements <= NumArrayElements);
QualType elementType = E->getType().getCanonicalType();
elementType = CGF.getContext().getQualifiedType(
cast<ArrayType>(elementType)->getElementType(),
elementType.getQualifiers() + Dest.getQualifiers());
// 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;
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");
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);
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();
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(DestPtr, Field, 0);
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;
// 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;
// FIXME: volatility
LValue LV = CGF.EmitLValueForFieldInitialization(DestPtr, *field, 0);
// 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)) {
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]);
}
//===----------------------------------------------------------------------===//
// 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.getContext().Target.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.getContext().getLangOptions().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();
llvm::Type *BP = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
Loc = CGF.Builder.CreateBitCast(Loc, BP);
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.
///
/// \param IsInitializer - true if this evaluation is initializing an
/// object whose lifetime is already being managed.
void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot,
bool IgnoreResult) {
assert(E && hasAggregateLLVMType(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, IgnoreResult).Visit(const_cast<Expr*>(E));
}
LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
assert(hasAggregateLLVMType(E->getType()) && "Invalid argument!");
llvm::Value *Temp = CreateMemTemp(E->getType());
LValue LV = MakeAddrLValue(Temp, E->getType());
EmitAggExpr(E, AggValueSlot::forLValue(LV, false));
return LV;
}
void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
llvm::Value *SrcPtr, QualType Ty,
bool isVolatile) {
assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
if (getContext().getLangOptions().CPlusPlus) {
if (const RecordType *RT = Ty->getAs<RecordType>()) {
CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
assert((Record->hasTrivialCopyConstructor() ||
Record->hasTrivialCopyAssignment()) &&
"Trying to aggregate-copy a type without a trivial copy "
"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 size and alignment info for this aggregate.
std::pair<CharUnits, CharUnits> TypeInfo =
getContext().getTypeInfoInChars(Ty);
// 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, "tmp");
llvm::PointerType *SPT = cast<llvm::PointerType>(SrcPtr->getType());
llvm::Type *SBP =
llvm::Type::getInt8PtrTy(getLLVMContext(), SPT->getAddressSpace());
SrcPtr = Builder.CreateBitCast(SrcPtr, SBP, "tmp");
// Don't do any of the memmove_collectable tests if GC isn't set.
if (CGM.getLangOptions().getGCMode() == 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;
}
}
}
Builder.CreateMemCpy(DestPtr, SrcPtr,
llvm::ConstantInt::get(IntPtrTy,
TypeInfo.first.getQuantity()),
TypeInfo.second.getQuantity(), isVolatile);
}
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