df0fe27b66
any body can spot codegen bugs with volatile, or knows of any in the bug database, let me know. llvm-svn: 72572
543 lines
20 KiB
C++
543 lines
20 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/DeclCXX.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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bool IgnoreResult;
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public:
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AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool v,
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bool ignore)
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: CGF(cgf), Builder(CGF.Builder),
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DestPtr(destPtr), VolatileDest(v), IgnoreResult(ignore) {
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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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/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
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void EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore = false);
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void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false);
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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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void VisitUnaryExtension(UnaryOperator *E) { Visit(E->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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}
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void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
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EmitAggLoadOfLValue(E);
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}
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void VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
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EmitAggLoadOfLValue(E);
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}
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void VisitPredefinedExpr(const PredefinedExpr *E) {
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EmitAggLoadOfLValue(E);
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}
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// Operators.
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void VisitCStyleCastExpr(CStyleCastExpr *E);
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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 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 VisitObjCKVCRefExpr(ObjCKVCRefExpr *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 VisitCXXConstructExpr(const CXXConstructExpr *E);
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void VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E);
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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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EmitFinalDestCopy(E, LV);
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}
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/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
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void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) {
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assert(Src.isAggregate() && "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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if (!Src.isVolatileQualified() || (IgnoreResult && Ignore))
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return;
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// If the source is volatile, we must read from it; to do that, we need
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// some place to put it.
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DestPtr = CGF.CreateTempAlloca(CGF.ConvertType(E->getType()), "agg.tmp");
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}
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// If the result of the assignment is used, copy the LHS there also.
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// FIXME: Pass VolatileDest as well. I think we also need to merge volatile
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// from the source as well, as we can't eliminate it if either operand
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// is volatile, unless copy has volatile for both source and destination..
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CGF.EmitAggregateCopy(DestPtr, Src.getAggregateAddr(), E->getType(),
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VolatileDest|Src.isVolatileQualified());
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}
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/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
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void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) {
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assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc");
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EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(),
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Src.isVolatileQualified()),
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Ignore);
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}
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//===----------------------------------------------------------------------===//
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// Visitor Methods
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//===----------------------------------------------------------------------===//
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void AggExprEmitter::VisitCStyleCastExpr(CStyleCastExpr *E) {
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// GCC union extension
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if (E->getType()->isUnionType()) {
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RecordDecl *SD = E->getType()->getAsRecordType()->getDecl();
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LValue FieldLoc = CGF.EmitLValueForField(DestPtr,
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*SD->field_begin(CGF.getContext()),
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true, 0);
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EmitInitializationToLValue(E->getSubExpr(), FieldLoc);
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return;
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}
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Visit(E->getSubExpr());
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}
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void AggExprEmitter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
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assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
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E->getType()) &&
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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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if (E->getCallReturnType()->isReferenceType()) {
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EmitAggLoadOfLValue(E);
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return;
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}
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RValue RV = CGF.EmitCallExpr(E);
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EmitFinalDestCopy(E, RV);
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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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EmitFinalDestCopy(E, RV);
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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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EmitFinalDestCopy(E, RV);
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}
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void AggExprEmitter::VisitObjCKVCRefExpr(ObjCKVCRefExpr *E) {
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RValue RV = CGF.EmitObjCPropertyGet(E);
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EmitFinalDestCopy(E, RV);
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}
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void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
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CGF.EmitAnyExpr(E->getLHS(), 0, false, true);
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CGF.EmitAggExpr(E->getRHS(), DestPtr, VolatileDest);
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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().hasSameUnqualifiedType(E->getLHS()->getType(),
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E->getRHS()->getType())
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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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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, VolatileDest);
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CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(),
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RValue::getAggregate(AggLoc, VolatileDest));
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}
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else if (LHS.isKVCRef()) {
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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, VolatileDest);
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CGF.EmitObjCPropertySet(LHS.getKVCRefExpr(),
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RValue::getAggregate(AggLoc, VolatileDest));
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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(), LHS.isVolatileQualified());
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EmitFinalDestCopy(E, LHS, true);
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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.EmitVAListRef(VE->getSubExpr());
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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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return;
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}
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EmitFinalDestCopy(VE, LValue::MakeAddr(ArgPtr, 0));
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}
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void
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AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
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llvm::Value *V = DestPtr;
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if (!V) {
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assert(isa<CXXTempVarDecl>(E->getVarDecl()) &&
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"Must have a temp var decl when there's no destination!");
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V = CGF.CreateTempAlloca(CGF.ConvertType(E->getVarDecl()->getType()),
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"tmpvar");
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}
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CGF.EmitCXXConstructExpr(V, E);
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}
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void AggExprEmitter::VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) {
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// FIXME: Do something with the temporaries!
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Visit(E->getSubExpr());
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}
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void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
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// FIXME: Ignore result?
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// FIXME: Are initializers affected by volatile?
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if (isa<ImplicitValueInitExpr>(E)) {
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EmitNullInitializationToLValue(LV, E->getType());
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} else 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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// FIXME: That isn't true for member pointers!
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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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CGF.EmitMemSetToZero(LV.getAddress(), T);
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}
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}
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void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
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#if 0
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// FIXME: Disabled while we figure out what to do about
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// test/CodeGen/bitfield.c
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//
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// If we can, prefer a copy from a global; this is a lot less code for long
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// globals, and it's easier for the current optimizers to analyze.
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// FIXME: Should we really be doing this? Should we try to avoid cases where
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// we emit a global with a lot of zeros? Should we try to avoid short
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// globals?
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if (E->isConstantInitializer(CGF.getContext(), 0)) {
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llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, &CGF);
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llvm::GlobalVariable* GV =
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new llvm::GlobalVariable(C->getType(), true,
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llvm::GlobalValue::InternalLinkage,
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C, "", &CGF.CGM.getModule(), 0);
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EmitFinalDestCopy(E, LValue::MakeAddr(GV, 0));
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return;
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}
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#endif
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if (E->hadArrayRangeDesignator()) {
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CGF.ErrorUnsupported(E, "GNU array range designator extension");
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}
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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().hasSameUnqualifiedType(T1, T2)) {
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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 CurInitVal = 0;
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if (E->getType()->isUnionType()) {
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// Only initialize one field of a union. The field itself is
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// specified by the initializer list.
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if (!E->getInitializedFieldInUnion()) {
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// Empty union; we have nothing to do.
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#ifndef NDEBUG
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// Make sure that it's really an empty and not a failure of
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// semantic analysis.
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for (RecordDecl::field_iterator Field = SD->field_begin(CGF.getContext()),
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FieldEnd = SD->field_end(CGF.getContext());
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Field != FieldEnd; ++Field)
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assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
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#endif
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return;
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}
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// FIXME: volatility
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FieldDecl *Field = E->getInitializedFieldInUnion();
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LValue FieldLoc = CGF.EmitLValueForField(DestPtr, Field, true, 0);
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if (NumInitElements) {
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// Store the initializer into the field
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EmitInitializationToLValue(E->getInit(0), FieldLoc);
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} else {
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// Default-initialize to null
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EmitNullInitializationToLValue(FieldLoc, Field->getType());
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}
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return;
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}
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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 (RecordDecl::field_iterator Field = SD->field_begin(CGF.getContext()),
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FieldEnd = SD->field_end(CGF.getContext());
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Field != FieldEnd; ++Field) {
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// We're done once we hit the flexible array member
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if (Field->getType()->isIncompleteArrayType())
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break;
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if (Field->isUnnamedBitfield())
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continue;
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// FIXME: volatility
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LValue FieldLoc = CGF.EmitLValueForField(DestPtr, *Field, false, 0);
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// We never generate write-barries for initialized fields.
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LValue::SetObjCNonGC(FieldLoc, true);
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if (CurInitVal < NumInitElements) {
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// Store the initializer into the field
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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, 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) {
|
|
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)
|
|
.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::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);
|
|
|
|
// 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::Int32Ty,
|
|
TypeInfo.second/8));
|
|
}
|