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clang-1/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/Support/Compiler.h"
#include "llvm/Intrinsics.h"
using namespace clang;
using namespace CodeGen;
//===----------------------------------------------------------------------===//
// Aggregate Expression Emitter
//===----------------------------------------------------------------------===//
namespace {
class VISIBILITY_HIDDEN AggExprEmitter : public StmtVisitor<AggExprEmitter> {
CodeGenFunction &CGF;
CGBuilderTy &Builder;
llvm::Value *DestPtr;
bool VolatileDest;
bool IgnoreResult;
bool IsInitializer;
bool RequiresGCollection;
public:
AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool v,
bool ignore, bool isinit, bool requiresGCollection)
: CGF(cgf), Builder(CGF.Builder),
DestPtr(destPtr), VolatileDest(v), IgnoreResult(ignore),
IsInitializer(isinit), RequiresGCollection(requiresGCollection) {
}
//===--------------------------------------------------------------------===//
// 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);
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
void VisitStmt(Stmt *S) {
CGF.ErrorUnsupported(S, "aggregate expression");
}
void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
// 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) {
EmitAggLoadOfLValue(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 VisitBinAssign(const BinaryOperator *E);
void VisitBinComma(const BinaryOperator *E);
void VisitObjCMessageExpr(ObjCMessageExpr *E);
void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
EmitAggLoadOfLValue(E);
}
void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
void VisitObjCImplicitSetterGetterRefExpr(ObjCImplicitSetterGetterRefExpr *E);
void VisitConditionalOperator(const ConditionalOperator *CO);
void VisitChooseExpr(const ChooseExpr *CE);
void VisitInitListExpr(InitListExpr *E);
void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
Visit(DAE->getExpr());
}
void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
void VisitCXXConstructExpr(const CXXConstructExpr *E);
void VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E);
void VisitVAArgExpr(VAArgExpr *E);
void EmitInitializationToLValue(Expr *E, LValue Address);
void EmitNullInitializationToLValue(LValue Address, QualType T);
// case Expr::ChooseExprClass:
};
} // 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);
}
/// 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 the result is ignored, don't copy from the value.
if (DestPtr == 0) {
if (!Src.isVolatileQualified() || (IgnoreResult && Ignore))
return;
// If the source is volatile, we must read from it; to do that, we need
// some place to put it.
DestPtr = CGF.CreateTempAlloca(CGF.ConvertType(E->getType()), "agg.tmp");
}
if (RequiresGCollection) {
CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
DestPtr, Src.getAggregateAddr(),
E->getType());
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(DestPtr, Src.getAggregateAddr(), E->getType(),
VolatileDest|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::VisitCastExpr(CastExpr *E) {
if (E->getCastKind() == CastExpr::CK_ToUnion) {
// GCC union extension
QualType PtrTy =
CGF.getContext().getPointerType(E->getSubExpr()->getType());
llvm::Value *CastPtr = Builder.CreateBitCast(DestPtr,
CGF.ConvertType(PtrTy));
EmitInitializationToLValue(E->getSubExpr(),
LValue::MakeAddr(CastPtr, Qualifiers()));
return;
}
// FIXME: Remove the CK_Unknown check here.
assert((E->getCastKind() == CastExpr::CK_NoOp ||
E->getCastKind() == CastExpr::CK_Unknown ||
E->getCastKind() == CastExpr::CK_UserDefinedConversion ||
E->getCastKind() == CastExpr::CK_ConstructorConversion) &&
"Only no-op casts allowed!");
assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
E->getType()) &&
"Implicit cast types must be compatible");
Visit(E->getSubExpr());
}
void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
if (E->getCallReturnType()->isReferenceType()) {
EmitAggLoadOfLValue(E);
return;
}
RValue RV = CGF.EmitCallExpr(E);
EmitFinalDestCopy(E, RV);
}
void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
RValue RV = CGF.EmitObjCMessageExpr(E);
EmitFinalDestCopy(E, RV);
}
void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
RValue RV = CGF.EmitObjCPropertyGet(E);
EmitFinalDestCopy(E, RV);
}
void AggExprEmitter::VisitObjCImplicitSetterGetterRefExpr(
ObjCImplicitSetterGetterRefExpr *E) {
RValue RV = CGF.EmitObjCPropertyGet(E);
EmitFinalDestCopy(E, RV);
}
void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
CGF.EmitAnyExpr(E->getLHS(), 0, false, true);
CGF.EmitAggExpr(E->getRHS(), DestPtr, VolatileDest,
/*IgnoreResult=*/false, IsInitializer);
}
void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
}
void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
CGF.ErrorUnsupported(E, "aggregate binary expression");
}
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");
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()) {
llvm::Value *AggLoc = DestPtr;
if (!AggLoc)
AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(),
RValue::getAggregate(AggLoc, VolatileDest));
} else if (LHS.isKVCRef()) {
llvm::Value *AggLoc = DestPtr;
if (!AggLoc)
AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest);
CGF.EmitObjCPropertySet(LHS.getKVCRefExpr(),
RValue::getAggregate(AggLoc, VolatileDest));
} else {
bool RequiresGCollection = false;
if (CGF.getContext().getLangOptions().NeXTRuntime) {
QualType LHSTy = E->getLHS()->getType();
if (const RecordType *FDTTy = LHSTy.getTypePtr()->getAs<RecordType>())
RequiresGCollection = FDTTy->getDecl()->hasObjectMember();
}
// Codegen the RHS so that it stores directly into the LHS.
CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), LHS.isVolatileQualified(),
false, false, RequiresGCollection);
EmitFinalDestCopy(E, LHS, true);
}
}
void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
CGF.PushConditionalTempDestruction();
CGF.EmitBlock(LHSBlock);
// Handle the GNU extension for missing LHS.
assert(E->getLHS() && "Must have LHS for aggregate value");
Visit(E->getLHS());
CGF.PopConditionalTempDestruction();
CGF.EmitBranch(ContBlock);
CGF.PushConditionalTempDestruction();
CGF.EmitBlock(RHSBlock);
Visit(E->getRHS());
CGF.PopConditionalTempDestruction();
CGF.EmitBranch(ContBlock);
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, LValue::MakeAddr(ArgPtr, Qualifiers()));
}
void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
llvm::Value *Val = DestPtr;
if (!Val) {
// Create a temporary variable.
Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
// FIXME: volatile
CGF.EmitAggExpr(E->getSubExpr(), Val, false);
} else
Visit(E->getSubExpr());
// Don't make this a live temporary if we're emitting an initializer expr.
if (!IsInitializer)
CGF.PushCXXTemporary(E->getTemporary(), Val);
}
void
AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
llvm::Value *Val = DestPtr;
if (!Val) {
// Create a temporary variable.
Val = CGF.CreateTempAlloca(CGF.ConvertTypeForMem(E->getType()), "tmp");
}
CGF.EmitCXXConstructExpr(Val, E);
}
void AggExprEmitter::VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) {
CGF.EmitCXXExprWithTemporaries(E, DestPtr, VolatileDest, IsInitializer);
}
void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
// FIXME: Ignore result?
// FIXME: Are initializers affected by volatile?
if (isa<ImplicitValueInitExpr>(E)) {
EmitNullInitializationToLValue(LV, E->getType());
} else if (E->getType()->isComplexType()) {
CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
} else if (CGF.hasAggregateLLVMType(E->getType())) {
CGF.EmitAnyExpr(E, LV.getAddress(), false);
} else {
CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, E->getType());
}
}
void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) {
if (!CGF.hasAggregateLLVMType(T)) {
// For non-aggregates, we can store zero
llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T));
CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T);
} else {
// Otherwise, just memset the whole thing to zero. This is legal
// because in LLVM, all default initializers are guaranteed to have a
// bit pattern of all zeros.
// FIXME: That isn't true for member pointers!
// 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.EmitMemSetToZero(LV.getAddress(), T);
}
}
void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
#if 0
// FIXME: Disabled while we figure out what to do about
// test/CodeGen/bitfield.c
//
// 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.
// FIXME: Should we really be doing this? Should we try to avoid cases where
// we emit a global with a lot of zeros? Should we try to avoid short
// globals?
if (E->isConstantInitializer(CGF.getContext(), 0)) {
llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, &CGF);
llvm::GlobalVariable* GV =
new llvm::GlobalVariable(C->getType(), true,
llvm::GlobalValue::InternalLinkage,
C, "", &CGF.CGM.getModule(), 0);
EmitFinalDestCopy(E, LValue::MakeAddr(GV, 0));
return;
}
#endif
if (E->hadArrayRangeDesignator()) {
CGF.ErrorUnsupported(E, "GNU array range designator extension");
}
// Handle initialization of an array.
if (E->getType()->isArrayType()) {
const llvm::PointerType *APType =
cast<llvm::PointerType>(DestPtr->getType());
const 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();
QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType();
// FIXME: were we intentionally ignoring address spaces and GC attributes?
Qualifiers Quals = CGF.MakeQualifiers(ElementType);
for (uint64_t i = 0; i != NumArrayElements; ++i) {
llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
if (i < NumInitElements)
EmitInitializationToLValue(E->getInit(i),
LValue::MakeAddr(NextVal, Quals));
else
EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, Quals),
ElementType);
}
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 *SD = E->getType()->getAs<RecordType>()->getDecl();
unsigned CurInitVal = 0;
if (E->getType()->isUnionType()) {
// 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 = SD->field_begin(),
FieldEnd = SD->field_end();
Field != FieldEnd; ++Field)
assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
#endif
return;
}
// FIXME: volatility
FieldDecl *Field = E->getInitializedFieldInUnion();
LValue FieldLoc = CGF.EmitLValueForField(DestPtr, Field, true, 0);
if (NumInitElements) {
// Store the initializer into the field
EmitInitializationToLValue(E->getInit(0), FieldLoc);
} else {
// Default-initialize to null
EmitNullInitializationToLValue(FieldLoc, Field->getType());
}
return;
}
// Here we iterate over the fields; this makes it simpler to both
// default-initialize fields and skip over unnamed fields.
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
if (Field->getType()->isIncompleteArrayType())
break;
if (Field->isUnnamedBitfield())
continue;
// FIXME: volatility
LValue FieldLoc = CGF.EmitLValueForField(DestPtr, *Field, false, 0);
// We never generate write-barries for initialized fields.
LValue::SetObjCNonGC(FieldLoc, true);
if (CurInitVal < NumInitElements) {
// Store the initializer into the field
EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc);
} else {
// We're out of initalizers; default-initialize to null
EmitNullInitializationToLValue(FieldLoc, Field->getType());
}
}
}
//===----------------------------------------------------------------------===//
// Entry Points into this File
//===----------------------------------------------------------------------===//
/// 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, llvm::Value *DestPtr,
bool VolatileDest, bool IgnoreResult,
bool IsInitializer,
bool RequiresGCollection) {
assert(E && hasAggregateLLVMType(E->getType()) &&
"Invalid aggregate expression to emit");
assert ((DestPtr != 0 || VolatileDest == false)
&& "volatile aggregate can't be 0");
AggExprEmitter(*this, DestPtr, VolatileDest, IgnoreResult, IsInitializer,
RequiresGCollection)
.Visit(const_cast<Expr*>(E));
}
void CodeGenFunction::EmitAggregateClear(llvm::Value *DestPtr, QualType Ty) {
assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
EmitMemSetToZero(DestPtr, Ty);
}
void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
llvm::Value *SrcPtr, QualType Ty,
bool isVolatile) {
assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
// 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.
const llvm::Type *BP =
llvm::PointerType::getUnqual(llvm::Type::getInt8Ty(VMContext));
if (DestPtr->getType() != BP)
DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
if (SrcPtr->getType() != BP)
SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
// Get size and alignment info for this aggregate.
std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
// FIXME: Handle variable sized types.
const llvm::Type *IntPtr =
llvm::IntegerType::get(VMContext, LLVMPointerWidth);
// 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 differnt call here. We use isVolatile to indicate when
// either the source or the destination is volatile.
Builder.CreateCall4(CGM.getMemCpyFn(),
DestPtr, SrcPtr,
// TypeInfo.first describes size in bits.
llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
TypeInfo.second/8));
}
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