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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 "clang/AST/ASTContext.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;
public:
AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool volatileDest)
: CGF(cgf), Builder(CGF.Builder),
DestPtr(destPtr), VolatileDest(volatileDest) {
}
//===--------------------------------------------------------------------===//
// 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);
void EmitNonConstInit(InitListExpr *E);
//===--------------------------------------------------------------------===//
// 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);
}
// Operators.
// case Expr::UnaryOperatorClass:
// case Expr::CastExprClass:
void VisitCStyleCastExpr(CStyleCastExpr *E);
void VisitImplicitCastExpr(ImplicitCastExpr *E);
void VisitCallExpr(const CallExpr *E);
void VisitStmtExpr(const StmtExpr *E);
void VisitBinaryOperator(const BinaryOperator *BO);
void VisitBinAssign(const BinaryOperator *E);
void VisitOverloadExpr(const OverloadExpr *E);
void VisitBinComma(const BinaryOperator *E);
void VisitObjCMessageExpr(ObjCMessageExpr *E);
void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
EmitAggLoadOfLValue(E);
}
void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
void VisitObjCKVCRefExpr(ObjCKVCRefExpr *E);
void VisitConditionalOperator(const ConditionalOperator *CO);
void VisitInitListExpr(InitListExpr *E);
void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
Visit(DAE->getExpr());
}
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);
assert(LV.isSimple() && "Can't have aggregate bitfield, vector, etc");
llvm::Value *SrcPtr = LV.getAddress();
// If the result is ignored, don't copy from the value.
if (DestPtr == 0)
// FIXME: If the source is volatile, we must read from it.
return;
CGF.EmitAggregateCopy(DestPtr, SrcPtr, E->getType());
}
//===----------------------------------------------------------------------===//
// Visitor Methods
//===----------------------------------------------------------------------===//
void AggExprEmitter::VisitCStyleCastExpr(CStyleCastExpr *E) {
// GCC union extension
if (E->getType()->isUnionType()) {
RecordDecl *SD = E->getType()->getAsRecordType()->getDecl();
LValue FieldLoc = CGF.EmitLValueForField(DestPtr, *SD->field_begin(), true, 0);
EmitInitializationToLValue(E->getSubExpr(), FieldLoc);
return;
}
Visit(E->getSubExpr());
}
void AggExprEmitter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
assert(CGF.getContext().typesAreCompatible(
E->getSubExpr()->getType().getUnqualifiedType(),
E->getType().getUnqualifiedType()) &&
"Implicit cast types must be compatible");
Visit(E->getSubExpr());
}
void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
RValue RV = CGF.EmitCallExpr(E);
assert(RV.isAggregate() && "Return value must be aggregate value!");
// If the result is ignored, don't copy from the value.
if (DestPtr == 0)
// FIXME: If the source is volatile, we must read from it.
return;
CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
}
void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
RValue RV = CGF.EmitObjCMessageExpr(E);
assert(RV.isAggregate() && "Return value must be aggregate value!");
// If the result is ignored, don't copy from the value.
if (DestPtr == 0)
// FIXME: If the source is volatile, we must read from it.
return;
CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
}
void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
RValue RV = CGF.EmitObjCPropertyGet(E);
assert(RV.isAggregate() && "Return value must be aggregate value!");
// If the result is ignored, don't copy from the value.
if (DestPtr == 0)
// FIXME: If the source is volatile, we must read from it.
return;
CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
}
void AggExprEmitter::VisitObjCKVCRefExpr(ObjCKVCRefExpr *E) {
RValue RV = CGF.EmitObjCPropertyGet(E);
assert(RV.isAggregate() && "Return value must be aggregate value!");
// If the result is ignored, don't copy from the value.
if (DestPtr == 0)
// FIXME: If the source is volatile, we must read from it.
return;
CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
}
void AggExprEmitter::VisitOverloadExpr(const OverloadExpr *E) {
RValue RV = CGF.EmitCallExpr(E->getFn(), E->arg_begin(),
E->arg_end(CGF.getContext()));
assert(RV.isAggregate() && "Return value must be aggregate value!");
// If the result is ignored, don't copy from the value.
if (DestPtr == 0)
// FIXME: If the source is volatile, we must read from it.
return;
CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
}
void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
CGF.EmitAnyExpr(E->getLHS());
CGF.EmitAggExpr(E->getRHS(), DestPtr, false);
}
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().typesAreCompatible(
E->getLHS()->getType().getUnqualifiedType(),
E->getRHS()->getType().getUnqualifiedType())
&& "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()) {
// FIXME: Volatility?
llvm::Value *AggLoc = DestPtr;
if (!AggLoc)
AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
CGF.EmitAggExpr(E->getRHS(), AggLoc, false);
CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(),
RValue::getAggregate(AggLoc));
}
else if (LHS.isKVCRef()) {
// FIXME: Volatility?
llvm::Value *AggLoc = DestPtr;
if (!AggLoc)
AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
CGF.EmitAggExpr(E->getRHS(), AggLoc, false);
CGF.EmitObjCPropertySet(LHS.getKVCRefExpr(),
RValue::getAggregate(AggLoc));
} else {
// Codegen the RHS so that it stores directly into the LHS.
CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), false /*FIXME: VOLATILE LHS*/);
if (DestPtr == 0)
return;
// If the result of the assignment is used, copy the RHS there also.
CGF.EmitAggregateCopy(DestPtr, LHS.getAddress(), E->getType());
}
}
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.EmitBlock(LHSBlock);
// Handle the GNU extension for missing LHS.
assert(E->getLHS() && "Must have LHS for aggregate value");
Visit(E->getLHS());
CGF.EmitBranch(ContBlock);
CGF.EmitBlock(RHSBlock);
Visit(E->getRHS());
CGF.EmitBranch(ContBlock);
CGF.EmitBlock(ContBlock);
}
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;
}
if (DestPtr)
// FIXME: volatility
CGF.EmitAggregateCopy(DestPtr, ArgPtr, VE->getType());
}
void AggExprEmitter::EmitNonConstInit(InitListExpr *E) {
const llvm::PointerType *APType =
cast<llvm::PointerType>(DestPtr->getType());
const llvm::Type *DestType = APType->getElementType();
if (E->hadArrayRangeDesignator()) {
CGF.ErrorUnsupported(E, "GNU array range designator extension");
}
if (const llvm::ArrayType *AType = dyn_cast<llvm::ArrayType>(DestType)) {
unsigned NumInitElements = E->getNumInits();
unsigned i;
for (i = 0; i != NumInitElements; ++i) {
llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
Expr *Init = E->getInit(i);
if (isa<InitListExpr>(Init))
CGF.EmitAggExpr(Init, NextVal, VolatileDest);
else
// FIXME: volatility
Builder.CreateStore(CGF.EmitScalarExpr(Init), NextVal);
}
// Emit remaining default initializers
unsigned NumArrayElements = AType->getNumElements();
QualType QType = E->getInit(0)->getType();
const llvm::Type *EType = AType->getElementType();
for (/*Do not initialize i*/; i < NumArrayElements; ++i) {
llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
if (EType->isSingleValueType())
// FIXME: volatility
Builder.CreateStore(llvm::Constant::getNullValue(EType), NextVal);
else
CGF.EmitAggregateClear(NextVal, QType);
}
} else
assert(false && "Invalid initializer");
}
void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
// 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.
// There's a potential optimization opportunity in combining
// memsets; that would be easy for arrays, but relatively
// difficult for structures with the current code.
const llvm::Type *SizeTy = llvm::Type::Int64Ty;
llvm::Value *MemSet = CGF.CGM.getIntrinsic(llvm::Intrinsic::memset,
&SizeTy, 1);
uint64_t Size = CGF.getContext().getTypeSize(T);
const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
llvm::Value* DestPtr = Builder.CreateBitCast(LV.getAddress(), BP, "tmp");
Builder.CreateCall4(MemSet, DestPtr,
llvm::ConstantInt::get(llvm::Type::Int8Ty, 0),
llvm::ConstantInt::get(SizeTy, Size/8),
llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
}
}
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);
CGF.EmitAggregateCopy(DestPtr, GV, E->getType());
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().getCanonicalType(T1).getUnqualifiedType() ==
CGF.getContext().getCanonicalType(T2).getUnqualifiedType()) {
EmitAggLoadOfLValue(E->getInit(0));
return;
}
}
uint64_t NumArrayElements = AType->getNumElements();
QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType();
unsigned CVRqualifier = ElementType.getCVRQualifiers();
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, CVRqualifier));
else
EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, CVRqualifier),
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()->getAsRecordType()->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);
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.
void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr,
bool VolatileDest) {
assert(E && hasAggregateLLVMType(E->getType()) &&
"Invalid aggregate expression to emit");
AggExprEmitter(*this, DestPtr, VolatileDest).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) {
assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
// Aggregate assignment turns into llvm.memmove.
const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
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(LLVMPointerWidth);
Builder.CreateCall4(CGM.getMemMoveFn(),
DestPtr, SrcPtr,
// TypeInfo.first describes size in bits.
llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
llvm::ConstantInt::get(llvm::Type::Int32Ty,
TypeInfo.second/8));
}
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