forked from OSchip/llvm-project
477 lines
18 KiB
C++
477 lines
18 KiB
C++
//===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This contains code to emit Aggregate Expr nodes as LLVM code.
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//
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//===----------------------------------------------------------------------===//
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#include "CodeGenFunction.h"
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#include "CodeGenModule.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/AST/StmtVisitor.h"
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#include "llvm/Constants.h"
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#include "llvm/Function.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Intrinsics.h"
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using namespace clang;
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using namespace CodeGen;
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//===----------------------------------------------------------------------===//
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// Aggregate Expression Emitter
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//===----------------------------------------------------------------------===//
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namespace {
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class VISIBILITY_HIDDEN AggExprEmitter : public StmtVisitor<AggExprEmitter> {
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CodeGenFunction &CGF;
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CGBuilderTy &Builder;
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llvm::Value *DestPtr;
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bool VolatileDest;
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public:
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AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool volatileDest)
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: CGF(cgf), Builder(CGF.Builder),
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DestPtr(destPtr), VolatileDest(volatileDest) {
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}
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//===--------------------------------------------------------------------===//
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// Utilities
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//===--------------------------------------------------------------------===//
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/// EmitAggLoadOfLValue - Given an expression with aggregate type that
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/// represents a value lvalue, this method emits the address of the lvalue,
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/// then loads the result into DestPtr.
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void EmitAggLoadOfLValue(const Expr *E);
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void EmitNonConstInit(InitListExpr *E);
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//===--------------------------------------------------------------------===//
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// Visitor Methods
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//===--------------------------------------------------------------------===//
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void VisitStmt(Stmt *S) {
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CGF.ErrorUnsupported(S, "aggregate expression");
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}
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void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
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// l-values.
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void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); }
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void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
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void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
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void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
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void VisitCompoundLiteralExpr(CompoundLiteralExpr *E)
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{ EmitAggLoadOfLValue(E); }
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void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
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EmitAggLoadOfLValue(E);
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}
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// Operators.
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// case Expr::UnaryOperatorClass:
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// case Expr::CastExprClass:
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void VisitImplicitCastExpr(ImplicitCastExpr *E);
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void VisitCallExpr(const CallExpr *E);
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void VisitStmtExpr(const StmtExpr *E);
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void VisitBinaryOperator(const BinaryOperator *BO);
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void VisitBinAssign(const BinaryOperator *E);
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void VisitOverloadExpr(const OverloadExpr *E);
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void VisitBinComma(const BinaryOperator *E);
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void VisitObjCMessageExpr(ObjCMessageExpr *E);
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void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
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EmitAggLoadOfLValue(E);
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}
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void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
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void VisitConditionalOperator(const ConditionalOperator *CO);
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void VisitInitListExpr(InitListExpr *E);
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void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
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Visit(DAE->getExpr());
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}
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void VisitVAArgExpr(VAArgExpr *E);
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void EmitInitializationToLValue(Expr *E, LValue Address);
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void EmitNullInitializationToLValue(LValue Address, QualType T);
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// case Expr::ChooseExprClass:
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};
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} // end anonymous namespace.
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//===----------------------------------------------------------------------===//
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// Utilities
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//===----------------------------------------------------------------------===//
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/// EmitAggLoadOfLValue - Given an expression with aggregate type that
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/// represents a value lvalue, this method emits the address of the lvalue,
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/// then loads the result into DestPtr.
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void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
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LValue LV = CGF.EmitLValue(E);
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assert(LV.isSimple() && "Can't have aggregate bitfield, vector, etc");
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llvm::Value *SrcPtr = LV.getAddress();
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// If the result is ignored, don't copy from the value.
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if (DestPtr == 0)
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// FIXME: If the source is volatile, we must read from it.
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return;
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CGF.EmitAggregateCopy(DestPtr, SrcPtr, E->getType());
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}
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//===----------------------------------------------------------------------===//
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// Visitor Methods
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//===----------------------------------------------------------------------===//
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void AggExprEmitter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
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assert(CGF.getContext().typesAreCompatible(
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E->getSubExpr()->getType().getUnqualifiedType(),
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E->getType().getUnqualifiedType()) &&
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"Implicit cast types must be compatible");
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Visit(E->getSubExpr());
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}
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void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
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RValue RV = CGF.EmitCallExpr(E);
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assert(RV.isAggregate() && "Return value must be aggregate value!");
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// If the result is ignored, don't copy from the value.
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if (DestPtr == 0)
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// FIXME: If the source is volatile, we must read from it.
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return;
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CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
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}
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void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
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RValue RV = CGF.EmitObjCMessageExpr(E);
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assert(RV.isAggregate() && "Return value must be aggregate value!");
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// If the result is ignored, don't copy from the value.
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if (DestPtr == 0)
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// FIXME: If the source is volatile, we must read from it.
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return;
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CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
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}
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void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
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RValue RV = CGF.EmitObjCPropertyGet(E);
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assert(RV.isAggregate() && "Return value must be aggregate value!");
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// If the result is ignored, don't copy from the value.
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if (DestPtr == 0)
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// FIXME: If the source is volatile, we must read from it.
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return;
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CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
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}
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void AggExprEmitter::VisitOverloadExpr(const OverloadExpr *E) {
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RValue RV = CGF.EmitCallExpr(E->getFn(), E->arg_begin(),
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E->arg_end(CGF.getContext()));
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assert(RV.isAggregate() && "Return value must be aggregate value!");
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// If the result is ignored, don't copy from the value.
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if (DestPtr == 0)
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// FIXME: If the source is volatile, we must read from it.
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return;
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CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
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}
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void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
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CGF.EmitAnyExpr(E->getLHS());
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CGF.EmitAggExpr(E->getRHS(), DestPtr, false);
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}
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void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
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CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
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}
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void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
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CGF.ErrorUnsupported(E, "aggregate binary expression");
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}
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void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
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// For an assignment to work, the value on the right has
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// to be compatible with the value on the left.
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assert(CGF.getContext().typesAreCompatible(
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E->getLHS()->getType().getUnqualifiedType(),
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E->getRHS()->getType().getUnqualifiedType())
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&& "Invalid assignment");
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LValue LHS = CGF.EmitLValue(E->getLHS());
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// We have to special case property setters, otherwise we must have
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// a simple lvalue (no aggregates inside vectors, bitfields).
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if (LHS.isPropertyRef()) {
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// FIXME: Volatility?
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llvm::Value *AggLoc = DestPtr;
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if (!AggLoc)
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AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType()));
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CGF.EmitAggExpr(E->getRHS(), AggLoc, false);
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CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(),
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RValue::getAggregate(AggLoc));
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} else {
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// Codegen the RHS so that it stores directly into the LHS.
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CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), false /*FIXME: VOLATILE LHS*/);
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if (DestPtr == 0)
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return;
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// If the result of the assignment is used, copy the RHS there also.
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CGF.EmitAggregateCopy(DestPtr, LHS.getAddress(), E->getType());
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}
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}
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void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
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llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
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llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
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llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
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llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
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Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
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CGF.EmitBlock(LHSBlock);
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// Handle the GNU extension for missing LHS.
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assert(E->getLHS() && "Must have LHS for aggregate value");
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Visit(E->getLHS());
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CGF.EmitBranch(ContBlock);
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CGF.EmitBlock(RHSBlock);
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Visit(E->getRHS());
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CGF.EmitBranch(ContBlock);
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CGF.EmitBlock(ContBlock);
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}
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void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
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llvm::Value *ArgValue = CGF.EmitLValue(VE->getSubExpr()).getAddress();
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llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
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if (!ArgPtr)
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CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
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if (DestPtr)
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// FIXME: volatility
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CGF.EmitAggregateCopy(DestPtr, ArgPtr, VE->getType());
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}
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void AggExprEmitter::EmitNonConstInit(InitListExpr *E) {
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if (E->hadDesignators()) {
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CGF.ErrorUnsupported(E, "initializer list with designators");
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return;
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}
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const llvm::PointerType *APType =
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cast<llvm::PointerType>(DestPtr->getType());
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const llvm::Type *DestType = APType->getElementType();
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if (const llvm::ArrayType *AType = dyn_cast<llvm::ArrayType>(DestType)) {
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unsigned NumInitElements = E->getNumInits();
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unsigned i;
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for (i = 0; i != NumInitElements; ++i) {
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llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
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Expr *Init = E->getInit(i);
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if (isa<InitListExpr>(Init))
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CGF.EmitAggExpr(Init, NextVal, VolatileDest);
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else
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// FIXME: volatility
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Builder.CreateStore(CGF.EmitScalarExpr(Init), NextVal);
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}
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// Emit remaining default initializers
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unsigned NumArrayElements = AType->getNumElements();
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QualType QType = E->getInit(0)->getType();
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const llvm::Type *EType = AType->getElementType();
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for (/*Do not initialize i*/; i < NumArrayElements; ++i) {
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llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
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if (EType->isSingleValueType())
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// FIXME: volatility
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Builder.CreateStore(llvm::Constant::getNullValue(EType), NextVal);
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else
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CGF.EmitAggregateClear(NextVal, QType);
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}
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} else
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assert(false && "Invalid initializer");
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}
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void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
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// FIXME: Are initializers affected by volatile?
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if (E->getType()->isComplexType()) {
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CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
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} else if (CGF.hasAggregateLLVMType(E->getType())) {
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CGF.EmitAnyExpr(E, LV.getAddress(), false);
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} else {
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CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, E->getType());
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}
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}
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void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) {
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if (!CGF.hasAggregateLLVMType(T)) {
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// For non-aggregates, we can store zero
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llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T));
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CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T);
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} else {
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// Otherwise, just memset the whole thing to zero. This is legal
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// because in LLVM, all default initializers are guaranteed to have a
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// bit pattern of all zeros.
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// There's a potential optimization opportunity in combining
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// memsets; that would be easy for arrays, but relatively
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// difficult for structures with the current code.
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llvm::Value *MemSet = CGF.CGM.getIntrinsic(llvm::Intrinsic::memset_i64);
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uint64_t Size = CGF.getContext().getTypeSize(T);
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const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
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llvm::Value* DestPtr = Builder.CreateBitCast(LV.getAddress(), BP, "tmp");
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Builder.CreateCall4(MemSet, DestPtr,
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llvm::ConstantInt::get(llvm::Type::Int8Ty, 0),
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llvm::ConstantInt::get(llvm::Type::Int64Ty, Size/8),
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llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
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}
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}
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void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
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if (E->hadDesignators()) {
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CGF.ErrorUnsupported(E, "initializer list with designators");
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return;
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}
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// FIXME: For constant expressions, call into const expr emitter so
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// that we can emit a memcpy instead of storing the individual
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// members. This is purely for perf; both codepaths lead to
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// equivalent (although not necessarily identical) code. It's worth
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// noting that LLVM keeps on getting smarter, though, so it might
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// not be worth bothering.
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// Handle initialization of an array.
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if (E->getType()->isArrayType()) {
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const llvm::PointerType *APType =
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cast<llvm::PointerType>(DestPtr->getType());
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const llvm::ArrayType *AType =
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cast<llvm::ArrayType>(APType->getElementType());
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uint64_t NumInitElements = E->getNumInits();
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if (E->getNumInits() > 0) {
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QualType T1 = E->getType();
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QualType T2 = E->getInit(0)->getType();
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if (CGF.getContext().getCanonicalType(T1).getUnqualifiedType() ==
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CGF.getContext().getCanonicalType(T2).getUnqualifiedType()) {
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EmitAggLoadOfLValue(E->getInit(0));
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return;
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}
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}
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uint64_t NumArrayElements = AType->getNumElements();
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QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
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ElementType =CGF.getContext().getAsArrayType(ElementType)->getElementType();
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unsigned CVRqualifier = ElementType.getCVRQualifiers();
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for (uint64_t i = 0; i != NumArrayElements; ++i) {
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llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
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if (i < NumInitElements)
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EmitInitializationToLValue(E->getInit(i),
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LValue::MakeAddr(NextVal, CVRqualifier));
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else
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EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, CVRqualifier),
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ElementType);
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}
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return;
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}
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assert(E->getType()->isRecordType() && "Only support structs/unions here!");
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// Do struct initialization; this code just sets each individual member
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// to the approprate value. This makes bitfield support automatic;
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// the disadvantage is that the generated code is more difficult for
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// the optimizer, especially with bitfields.
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unsigned NumInitElements = E->getNumInits();
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RecordDecl *SD = E->getType()->getAsRecordType()->getDecl();
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unsigned NumMembers = SD->getNumMembers() - SD->hasFlexibleArrayMember();
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unsigned CurInitVal = 0;
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bool isUnion = E->getType()->isUnionType();
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// Here we iterate over the fields; this makes it simpler to both
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// default-initialize fields and skip over unnamed fields.
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for (unsigned CurFieldNo = 0; CurFieldNo != NumMembers; ++CurFieldNo) {
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FieldDecl *CurField = SD->getMember(CurFieldNo);
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if (CurField->getIdentifier() == 0) {
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// Initializers can't initialize unnamed fields, e.g. "int : 20;"
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continue;
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}
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// FIXME: volatility
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LValue FieldLoc = CGF.EmitLValueForField(DestPtr, CurField, isUnion,0);
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if (CurInitVal < NumInitElements) {
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// Store the initializer into the field
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// This will probably have to get a bit smarter when we support
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// designators in initializers
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EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc);
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} else {
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// We're out of initalizers; default-initialize to null
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EmitNullInitializationToLValue(FieldLoc, CurField->getType());
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}
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// Unions only initialize one field.
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// (things can get weird with designators, but they aren't
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// supported yet.)
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if (E->getType()->isUnionType())
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break;
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}
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}
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//===----------------------------------------------------------------------===//
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// Entry Points into this File
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//===----------------------------------------------------------------------===//
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/// EmitAggExpr - Emit the computation of the specified expression of
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/// aggregate type. The result is computed into DestPtr. Note that if
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/// DestPtr is null, the value of the aggregate expression is not needed.
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void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr,
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bool VolatileDest) {
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assert(E && hasAggregateLLVMType(E->getType()) &&
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"Invalid aggregate expression to emit");
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AggExprEmitter(*this, DestPtr, VolatileDest).Visit(const_cast<Expr*>(E));
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}
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void CodeGenFunction::EmitAggregateClear(llvm::Value *DestPtr, QualType Ty) {
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assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
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EmitMemSetToZero(DestPtr, Ty);
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}
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void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
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llvm::Value *SrcPtr, QualType Ty) {
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assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
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// Aggregate assignment turns into llvm.memmove.
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const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
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if (DestPtr->getType() != BP)
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DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
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if (SrcPtr->getType() != BP)
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SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
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// Get size and alignment info for this aggregate.
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std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
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// 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));
|
|
}
|