//===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This contains code to emit Aggregate Expr nodes as LLVM code. // //===----------------------------------------------------------------------===// #include "CodeGenFunction.h" #include "CodeGenModule.h" #include "CGObjCRuntime.h" #include "clang/AST/ASTContext.h" #include "clang/AST/DeclCXX.h" #include "clang/AST/StmtVisitor.h" #include "llvm/Constants.h" #include "llvm/Function.h" #include "llvm/GlobalVariable.h" #include "llvm/Intrinsics.h" using namespace clang; using namespace CodeGen; //===----------------------------------------------------------------------===// // Aggregate Expression Emitter //===----------------------------------------------------------------------===// namespace { class AggExprEmitter : public StmtVisitor { CodeGenFunction &CGF; CGBuilderTy &Builder; AggValueSlot Dest; bool IgnoreResult; ReturnValueSlot getReturnValueSlot() const { // If the destination slot requires garbage collection, we can't // use the real return value slot, because we have to use the GC // API. if (Dest.requiresGCollection()) return ReturnValueSlot(); return ReturnValueSlot(Dest.getAddr(), Dest.isVolatile()); } AggValueSlot EnsureSlot(QualType T) { if (!Dest.isIgnored()) return Dest; return CGF.CreateAggTemp(T, "agg.tmp.ensured"); } public: AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest, bool ignore) : CGF(cgf), Builder(CGF.Builder), Dest(Dest), IgnoreResult(ignore) { } //===--------------------------------------------------------------------===// // Utilities //===--------------------------------------------------------------------===// /// EmitAggLoadOfLValue - Given an expression with aggregate type that /// represents a value lvalue, this method emits the address of the lvalue, /// then loads the result into DestPtr. void EmitAggLoadOfLValue(const Expr *E); /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. void EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore = false); void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false); void EmitGCMove(const Expr *E, RValue Src); bool TypeRequiresGCollection(QualType T); //===--------------------------------------------------------------------===// // Visitor Methods //===--------------------------------------------------------------------===// void VisitStmt(Stmt *S) { CGF.ErrorUnsupported(S, "aggregate expression"); } void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); } void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); } // l-values. void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); } void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); } void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); } void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); } void VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { EmitAggLoadOfLValue(E); } void VisitArraySubscriptExpr(ArraySubscriptExpr *E) { EmitAggLoadOfLValue(E); } void VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) { EmitAggLoadOfLValue(E); } void VisitPredefinedExpr(const PredefinedExpr *E) { EmitAggLoadOfLValue(E); } // Operators. void VisitCastExpr(CastExpr *E); void VisitCallExpr(const CallExpr *E); void VisitStmtExpr(const StmtExpr *E); void VisitBinaryOperator(const BinaryOperator *BO); void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO); void VisitBinAssign(const BinaryOperator *E); void VisitBinComma(const BinaryOperator *E); void VisitObjCMessageExpr(ObjCMessageExpr *E); void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) { EmitAggLoadOfLValue(E); } void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E); void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO); void VisitChooseExpr(const ChooseExpr *CE); void VisitInitListExpr(InitListExpr *E); void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E); void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { Visit(DAE->getExpr()); } void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E); void VisitCXXConstructExpr(const CXXConstructExpr *E); void VisitExprWithCleanups(ExprWithCleanups *E); void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E); void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); } void VisitOpaqueValueExpr(OpaqueValueExpr *E); void VisitVAArgExpr(VAArgExpr *E); void EmitInitializationToLValue(Expr *E, LValue Address, QualType T); void EmitNullInitializationToLValue(LValue Address, QualType T); // case Expr::ChooseExprClass: void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); } }; } // end anonymous namespace. //===----------------------------------------------------------------------===// // Utilities //===----------------------------------------------------------------------===// /// EmitAggLoadOfLValue - Given an expression with aggregate type that /// represents a value lvalue, this method emits the address of the lvalue, /// then loads the result into DestPtr. void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) { LValue LV = CGF.EmitLValue(E); EmitFinalDestCopy(E, LV); } /// \brief True if the given aggregate type requires special GC API calls. bool AggExprEmitter::TypeRequiresGCollection(QualType T) { // Only record types have members that might require garbage collection. const RecordType *RecordTy = T->getAs(); if (!RecordTy) return false; // Don't mess with non-trivial C++ types. RecordDecl *Record = RecordTy->getDecl(); if (isa(Record) && (!cast(Record)->hasTrivialCopyConstructor() || !cast(Record)->hasTrivialDestructor())) return false; // Check whether the type has an object member. return Record->hasObjectMember(); } /// \brief Perform the final move to DestPtr if RequiresGCollection is set. /// /// The idea is that you do something like this: /// RValue Result = EmitSomething(..., getReturnValueSlot()); /// EmitGCMove(E, Result); /// If GC doesn't interfere, this will cause the result to be emitted /// directly into the return value slot. If GC does interfere, a final /// move will be performed. void AggExprEmitter::EmitGCMove(const Expr *E, RValue Src) { if (Dest.requiresGCollection()) { std::pair TypeInfo = CGF.getContext().getTypeInfo(E->getType()); unsigned long size = TypeInfo.first/8; const llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType()); llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size); CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF, Dest.getAddr(), Src.getAggregateAddr(), SizeVal); } } /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) { assert(Src.isAggregate() && "value must be aggregate value!"); // If Dest is ignored, then we're evaluating an aggregate expression // in a context (like an expression statement) that doesn't care // about the result. C says that an lvalue-to-rvalue conversion is // performed in these cases; C++ says that it is not. In either // case, we don't actually need to do anything unless the value is // volatile. if (Dest.isIgnored()) { if (!Src.isVolatileQualified() || CGF.CGM.getLangOptions().CPlusPlus || (IgnoreResult && Ignore)) return; // If the source is volatile, we must read from it; to do that, we need // some place to put it. Dest = CGF.CreateAggTemp(E->getType(), "agg.tmp"); } if (Dest.requiresGCollection()) { std::pair TypeInfo = CGF.getContext().getTypeInfo(E->getType()); unsigned long size = TypeInfo.first/8; const llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType()); llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size); CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF, Dest.getAddr(), Src.getAggregateAddr(), SizeVal); return; } // If the result of the assignment is used, copy the LHS there also. // FIXME: Pass VolatileDest as well. I think we also need to merge volatile // from the source as well, as we can't eliminate it if either operand // is volatile, unless copy has volatile for both source and destination.. CGF.EmitAggregateCopy(Dest.getAddr(), Src.getAggregateAddr(), E->getType(), Dest.isVolatile()|Src.isVolatileQualified()); } /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) { assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc"); EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(), Src.isVolatileQualified()), Ignore); } //===----------------------------------------------------------------------===// // Visitor Methods //===----------------------------------------------------------------------===// void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) { EmitFinalDestCopy(e, CGF.getOpaqueLValueMapping(e)); } void AggExprEmitter::VisitCastExpr(CastExpr *E) { if (Dest.isIgnored() && E->getCastKind() != CK_Dynamic) { Visit(E->getSubExpr()); return; } switch (E->getCastKind()) { case CK_Dynamic: { assert(isa(E) && "CK_Dynamic without a dynamic_cast?"); LValue LV = CGF.EmitCheckedLValue(E->getSubExpr()); // FIXME: Do we also need to handle property references here? if (LV.isSimple()) CGF.EmitDynamicCast(LV.getAddress(), cast(E)); else CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast"); if (!Dest.isIgnored()) CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination"); break; } case CK_ToUnion: { // GCC union extension QualType Ty = E->getSubExpr()->getType(); QualType PtrTy = CGF.getContext().getPointerType(Ty); llvm::Value *CastPtr = Builder.CreateBitCast(Dest.getAddr(), CGF.ConvertType(PtrTy)); EmitInitializationToLValue(E->getSubExpr(), CGF.MakeAddrLValue(CastPtr, Ty), Ty); break; } case CK_DerivedToBase: case CK_BaseToDerived: case CK_UncheckedDerivedToBase: { assert(0 && "cannot perform hierarchy conversion in EmitAggExpr: " "should have been unpacked before we got here"); break; } case CK_GetObjCProperty: { LValue LV = CGF.EmitLValue(E->getSubExpr()); assert(LV.isPropertyRef()); RValue RV = CGF.EmitLoadOfPropertyRefLValue(LV, getReturnValueSlot()); EmitGCMove(E, RV); break; } case CK_LValueToRValue: // hope for downstream optimization case CK_NoOp: case CK_UserDefinedConversion: case CK_ConstructorConversion: assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(), E->getType()) && "Implicit cast types must be compatible"); Visit(E->getSubExpr()); break; case CK_LValueBitCast: llvm_unreachable("should not be emitting lvalue bitcast as rvalue"); break; case CK_Dependent: case CK_BitCast: case CK_ArrayToPointerDecay: case CK_FunctionToPointerDecay: case CK_NullToPointer: case CK_NullToMemberPointer: case CK_BaseToDerivedMemberPointer: case CK_DerivedToBaseMemberPointer: case CK_MemberPointerToBoolean: case CK_IntegralToPointer: case CK_PointerToIntegral: case CK_PointerToBoolean: case CK_ToVoid: case CK_VectorSplat: case CK_IntegralCast: case CK_IntegralToBoolean: case CK_IntegralToFloating: case CK_FloatingToIntegral: case CK_FloatingToBoolean: case CK_FloatingCast: case CK_AnyPointerToObjCPointerCast: case CK_AnyPointerToBlockPointerCast: case CK_ObjCObjectLValueCast: case CK_FloatingRealToComplex: case CK_FloatingComplexToReal: case CK_FloatingComplexToBoolean: case CK_FloatingComplexCast: case CK_FloatingComplexToIntegralComplex: case CK_IntegralRealToComplex: case CK_IntegralComplexToReal: case CK_IntegralComplexToBoolean: case CK_IntegralComplexCast: case CK_IntegralComplexToFloatingComplex: llvm_unreachable("cast kind invalid for aggregate types"); } } void AggExprEmitter::VisitCallExpr(const CallExpr *E) { if (E->getCallReturnType()->isReferenceType()) { EmitAggLoadOfLValue(E); return; } RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot()); EmitGCMove(E, RV); } void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) { RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot()); EmitGCMove(E, RV); } void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) { llvm_unreachable("direct property access not surrounded by " "lvalue-to-rvalue cast"); } void AggExprEmitter::VisitBinComma(const BinaryOperator *E) { CGF.EmitIgnoredExpr(E->getLHS()); Visit(E->getRHS()); } void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) { CodeGenFunction::StmtExprEvaluation eval(CGF); CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest); } void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) { if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI) VisitPointerToDataMemberBinaryOperator(E); else CGF.ErrorUnsupported(E, "aggregate binary expression"); } void AggExprEmitter::VisitPointerToDataMemberBinaryOperator( const BinaryOperator *E) { LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E); EmitFinalDestCopy(E, LV); } void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) { // For an assignment to work, the value on the right has // to be compatible with the value on the left. assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(), E->getRHS()->getType()) && "Invalid assignment"); // FIXME: __block variables need the RHS evaluated first! 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()) { AggValueSlot Slot = EnsureSlot(E->getRHS()->getType()); CGF.EmitAggExpr(E->getRHS(), Slot); CGF.EmitStoreThroughPropertyRefLValue(Slot.asRValue(), LHS); } else { bool GCollection = false; if (CGF.getContext().getLangOptions().getGCMode()) GCollection = TypeRequiresGCollection(E->getLHS()->getType()); // Codegen the RHS so that it stores directly into the LHS. AggValueSlot LHSSlot = AggValueSlot::forLValue(LHS, true, GCollection); CGF.EmitAggExpr(E->getRHS(), LHSSlot, false); EmitFinalDestCopy(E, LHS, true); } } void AggExprEmitter:: VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) { llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true"); llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false"); llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end"); // Bind the common expression if necessary. CodeGenFunction::OpaqueValueMapping binding(CGF, E); CodeGenFunction::ConditionalEvaluation eval(CGF); CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock); // Save whether the destination's lifetime is externally managed. bool DestLifetimeManaged = Dest.isLifetimeExternallyManaged(); eval.begin(CGF); CGF.EmitBlock(LHSBlock); Visit(E->getTrueExpr()); eval.end(CGF); assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!"); CGF.Builder.CreateBr(ContBlock); // If the result of an agg expression is unused, then the emission // of the LHS might need to create a destination slot. That's fine // with us, and we can safely emit the RHS into the same slot, but // we shouldn't claim that its lifetime is externally managed. Dest.setLifetimeExternallyManaged(DestLifetimeManaged); eval.begin(CGF); CGF.EmitBlock(RHSBlock); Visit(E->getFalseExpr()); eval.end(CGF); CGF.EmitBlock(ContBlock); } void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) { Visit(CE->getChosenSubExpr(CGF.getContext())); } void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) { llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr()); llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType()); if (!ArgPtr) { CGF.ErrorUnsupported(VE, "aggregate va_arg expression"); return; } EmitFinalDestCopy(VE, CGF.MakeAddrLValue(ArgPtr, VE->getType())); } void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) { // Ensure that we have a slot, but if we already do, remember // whether its lifetime was externally managed. bool WasManaged = Dest.isLifetimeExternallyManaged(); Dest = EnsureSlot(E->getType()); Dest.setLifetimeExternallyManaged(); Visit(E->getSubExpr()); // Set up the temporary's destructor if its lifetime wasn't already // being managed. if (!WasManaged) CGF.EmitCXXTemporary(E->getTemporary(), Dest.getAddr()); } void AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) { AggValueSlot Slot = EnsureSlot(E->getType()); CGF.EmitCXXConstructExpr(E, Slot); } void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) { CGF.EmitExprWithCleanups(E, Dest); } void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) { QualType T = E->getType(); AggValueSlot Slot = EnsureSlot(T); EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T), T); } void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) { QualType T = E->getType(); AggValueSlot Slot = EnsureSlot(T); EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T), T); } /// isSimpleZero - If emitting this value will obviously just cause a store of /// zero to memory, return true. This can return false if uncertain, so it just /// handles simple cases. static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) { // (0) if (const ParenExpr *PE = dyn_cast(E)) return isSimpleZero(PE->getSubExpr(), CGF); // 0 if (const IntegerLiteral *IL = dyn_cast(E)) return IL->getValue() == 0; // +0.0 if (const FloatingLiteral *FL = dyn_cast(E)) return FL->getValue().isPosZero(); // int() if ((isa(E) || isa(E)) && CGF.getTypes().isZeroInitializable(E->getType())) return true; // (int*)0 - Null pointer expressions. if (const CastExpr *ICE = dyn_cast(E)) return ICE->getCastKind() == CK_NullToPointer; // '\0' if (const CharacterLiteral *CL = dyn_cast(E)) return CL->getValue() == 0; // Otherwise, hard case: conservatively return false. return false; } void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV, QualType T) { // FIXME: Ignore result? // FIXME: Are initializers affected by volatile? if (Dest.isZeroed() && isSimpleZero(E, CGF)) { // Storing "i32 0" to a zero'd memory location is a noop. } else if (isa(E)) { EmitNullInitializationToLValue(LV, T); } else if (T->isReferenceType()) { RValue RV = CGF.EmitReferenceBindingToExpr(E, /*InitializedDecl=*/0); CGF.EmitStoreThroughLValue(RV, LV, T); } else if (T->isAnyComplexType()) { CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false); } else if (CGF.hasAggregateLLVMType(T)) { CGF.EmitAggExpr(E, AggValueSlot::forAddr(LV.getAddress(), false, true, false, Dest.isZeroed())); } else { CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV, T); } } void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) { // If the destination slot is already zeroed out before the aggregate is // copied into it, we don't have to emit any zeros here. if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(T)) return; 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 { // There's a potential optimization opportunity in combining // memsets; that would be easy for arrays, but relatively // difficult for structures with the current code. CGF.EmitNullInitialization(LV.getAddress(), T); } } void AggExprEmitter::VisitInitListExpr(InitListExpr *E) { #if 0 // FIXME: Assess perf here? Figure out what cases are worth optimizing here // (Length of globals? Chunks of zeroed-out space?). // // If we can, prefer a copy from a global; this is a lot less code for long // globals, and it's easier for the current optimizers to analyze. if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) { llvm::GlobalVariable* GV = new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true, llvm::GlobalValue::InternalLinkage, C, ""); EmitFinalDestCopy(E, CGF.MakeAddrLValue(GV, E->getType())); return; } #endif if (E->hadArrayRangeDesignator()) CGF.ErrorUnsupported(E, "GNU array range designator extension"); llvm::Value *DestPtr = Dest.getAddr(); // Handle initialization of an array. if (E->getType()->isArrayType()) { const llvm::PointerType *APType = cast(DestPtr->getType()); const llvm::ArrayType *AType = cast(APType->getElementType()); uint64_t NumInitElements = E->getNumInits(); if (E->getNumInits() > 0) { QualType T1 = E->getType(); QualType T2 = E->getInit(0)->getType(); if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) { EmitAggLoadOfLValue(E->getInit(0)); return; } } uint64_t NumArrayElements = AType->getNumElements(); QualType ElementType = CGF.getContext().getCanonicalType(E->getType()); ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType(); // FIXME: were we intentionally ignoring address spaces and GC attributes? for (uint64_t i = 0; i != NumArrayElements; ++i) { // If we're done emitting initializers and the destination is known-zeroed // then we're done. if (i == NumInitElements && Dest.isZeroed() && CGF.getTypes().isZeroInitializable(ElementType)) break; llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array"); LValue LV = CGF.MakeAddrLValue(NextVal, ElementType); if (i < NumInitElements) EmitInitializationToLValue(E->getInit(i), LV, ElementType); else EmitNullInitializationToLValue(LV, ElementType); // If the GEP didn't get used because of a dead zero init or something // else, clean it up for -O0 builds and general tidiness. if (llvm::GetElementPtrInst *GEP = dyn_cast(NextVal)) if (GEP->use_empty()) GEP->eraseFromParent(); } return; } assert(E->getType()->isRecordType() && "Only support structs/unions here!"); // Do struct initialization; this code just sets each individual member // to the approprate value. This makes bitfield support automatic; // the disadvantage is that the generated code is more difficult for // the optimizer, especially with bitfields. unsigned NumInitElements = E->getNumInits(); RecordDecl *SD = E->getType()->getAs()->getDecl(); 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.EmitLValueForFieldInitialization(DestPtr, Field, 0); if (NumInitElements) { // Store the initializer into the field EmitInitializationToLValue(E->getInit(0), FieldLoc, Field->getType()); } 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. unsigned CurInitVal = 0; for (RecordDecl::field_iterator Field = SD->field_begin(), FieldEnd = SD->field_end(); Field != FieldEnd; ++Field) { // We're done once we hit the flexible array member if (Field->getType()->isIncompleteArrayType()) break; if (Field->isUnnamedBitfield()) continue; // Don't emit GEP before a noop store of zero. if (CurInitVal == NumInitElements && Dest.isZeroed() && CGF.getTypes().isZeroInitializable(E->getType())) break; // FIXME: volatility LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, *Field, 0); // We never generate write-barries for initialized fields. FieldLoc.setNonGC(true); if (CurInitVal < NumInitElements) { // Store the initializer into the field. EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc, Field->getType()); } else { // We're out of initalizers; default-initialize to null EmitNullInitializationToLValue(FieldLoc, Field->getType()); } // If the GEP didn't get used because of a dead zero init or something // else, clean it up for -O0 builds and general tidiness. if (FieldLoc.isSimple()) if (llvm::GetElementPtrInst *GEP = dyn_cast(FieldLoc.getAddress())) if (GEP->use_empty()) GEP->eraseFromParent(); } } //===----------------------------------------------------------------------===// // Entry Points into this File //===----------------------------------------------------------------------===// /// GetNumNonZeroBytesInInit - Get an approximate count of the number of /// non-zero bytes that will be stored when outputting the initializer for the /// specified initializer expression. static uint64_t GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) { if (const ParenExpr *PE = dyn_cast(E)) return GetNumNonZeroBytesInInit(PE->getSubExpr(), CGF); // 0 and 0.0 won't require any non-zero stores! if (isSimpleZero(E, CGF)) return 0; // If this is an initlist expr, sum up the size of sizes of the (present) // elements. If this is something weird, assume the whole thing is non-zero. const InitListExpr *ILE = dyn_cast(E); if (ILE == 0 || !CGF.getTypes().isZeroInitializable(ILE->getType())) return CGF.getContext().getTypeSize(E->getType())/8; // InitListExprs for structs have to be handled carefully. If there are // reference members, we need to consider the size of the reference, not the // referencee. InitListExprs for unions and arrays can't have references. if (const RecordType *RT = E->getType()->getAs()) { if (!RT->isUnionType()) { RecordDecl *SD = E->getType()->getAs()->getDecl(); uint64_t NumNonZeroBytes = 0; unsigned ILEElement = 0; for (RecordDecl::field_iterator Field = SD->field_begin(), FieldEnd = SD->field_end(); Field != FieldEnd; ++Field) { // We're done once we hit the flexible array member or run out of // InitListExpr elements. if (Field->getType()->isIncompleteArrayType() || ILEElement == ILE->getNumInits()) break; if (Field->isUnnamedBitfield()) continue; const Expr *E = ILE->getInit(ILEElement++); // Reference values are always non-null and have the width of a pointer. if (Field->getType()->isReferenceType()) NumNonZeroBytes += CGF.getContext().Target.getPointerWidth(0); else NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF); } return NumNonZeroBytes; } } uint64_t NumNonZeroBytes = 0; for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i) NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF); return NumNonZeroBytes; } /// CheckAggExprForMemSetUse - If the initializer is large and has a lot of /// zeros in it, emit a memset and avoid storing the individual zeros. /// static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E, CodeGenFunction &CGF) { // If the slot is already known to be zeroed, nothing to do. Don't mess with // volatile stores. if (Slot.isZeroed() || Slot.isVolatile() || Slot.getAddr() == 0) return; // If the type is 16-bytes or smaller, prefer individual stores over memset. std::pair TypeInfo = CGF.getContext().getTypeInfo(E->getType()); if (TypeInfo.first/8 <= 16) return; // Check to see if over 3/4 of the initializer are known to be zero. If so, // we prefer to emit memset + individual stores for the rest. uint64_t NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF); if (NumNonZeroBytes*4 > TypeInfo.first/8) return; // Okay, it seems like a good idea to use an initial memset, emit the call. llvm::Constant *SizeVal = CGF.Builder.getInt64(TypeInfo.first/8); unsigned Align = TypeInfo.second/8; llvm::Value *Loc = Slot.getAddr(); const llvm::Type *BP = llvm::Type::getInt8PtrTy(CGF.getLLVMContext()); Loc = CGF.Builder.CreateBitCast(Loc, BP); CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal, Align, false); // Tell the AggExprEmitter that the slot is known zero. Slot.setZeroed(); } /// EmitAggExpr - Emit the computation of the specified expression of aggregate /// type. The result is computed into DestPtr. Note that if DestPtr is null, /// the value of the aggregate expression is not needed. If VolatileDest is /// true, DestPtr cannot be 0. /// /// \param IsInitializer - true if this evaluation is initializing an /// object whose lifetime is already being managed. // // FIXME: Take Qualifiers object. void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot, bool IgnoreResult) { assert(E && hasAggregateLLVMType(E->getType()) && "Invalid aggregate expression to emit"); assert((Slot.getAddr() != 0 || Slot.isIgnored()) && "slot has bits but no address"); // Optimize the slot if possible. CheckAggExprForMemSetUse(Slot, E, *this); AggExprEmitter(*this, Slot, IgnoreResult).Visit(const_cast(E)); } LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) { assert(hasAggregateLLVMType(E->getType()) && "Invalid argument!"); llvm::Value *Temp = CreateMemTemp(E->getType()); LValue LV = MakeAddrLValue(Temp, E->getType()); EmitAggExpr(E, AggValueSlot::forAddr(Temp, LV.isVolatileQualified(), false)); return LV; } void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr, llvm::Value *SrcPtr, QualType Ty, bool isVolatile) { assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex"); if (getContext().getLangOptions().CPlusPlus) { if (const RecordType *RT = Ty->getAs()) { CXXRecordDecl *Record = cast(RT->getDecl()); assert((Record->hasTrivialCopyConstructor() || Record->hasTrivialCopyAssignment()) && "Trying to aggregate-copy a type without a trivial copy " "constructor or assignment operator"); // Ignore empty classes in C++. if (Record->isEmpty()) return; } } // Aggregate assignment turns into llvm.memcpy. This is almost valid per // C99 6.5.16.1p3, which states "If the value being stored in an object is // read from another object that overlaps in anyway the storage of the first // object, then the overlap shall be exact and the two objects shall have // qualified or unqualified versions of a compatible type." // // memcpy is not defined if the source and destination pointers are exactly // equal, but other compilers do this optimization, and almost every memcpy // implementation handles this case safely. If there is a libc that does not // safely handle this, we can add a target hook. // Get size and alignment info for this aggregate. std::pair TypeInfo = getContext().getTypeInfo(Ty); // FIXME: Handle variable sized types. // FIXME: If we have a volatile struct, the optimizer can remove what might // appear to be `extra' memory ops: // // volatile struct { int i; } a, b; // // int main() { // a = b; // a = b; // } // // we need to use a different call here. We use isVolatile to indicate when // either the source or the destination is volatile. const llvm::PointerType *DPT = cast(DestPtr->getType()); const llvm::Type *DBP = llvm::Type::getInt8PtrTy(getLLVMContext(), DPT->getAddressSpace()); DestPtr = Builder.CreateBitCast(DestPtr, DBP, "tmp"); const llvm::PointerType *SPT = cast(SrcPtr->getType()); const llvm::Type *SBP = llvm::Type::getInt8PtrTy(getLLVMContext(), SPT->getAddressSpace()); SrcPtr = Builder.CreateBitCast(SrcPtr, SBP, "tmp"); if (const RecordType *RecordTy = Ty->getAs()) { RecordDecl *Record = RecordTy->getDecl(); if (Record->hasObjectMember()) { unsigned long size = TypeInfo.first/8; const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size); CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr, SizeVal); return; } } else if (getContext().getAsArrayType(Ty)) { QualType BaseType = getContext().getBaseElementType(Ty); if (const RecordType *RecordTy = BaseType->getAs()) { if (RecordTy->getDecl()->hasObjectMember()) { unsigned long size = TypeInfo.first/8; const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size); CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr, SizeVal); return; } } } Builder.CreateMemCpy(DestPtr, SrcPtr, llvm::ConstantInt::get(IntPtrTy, TypeInfo.first/8), TypeInfo.second/8, isVolatile); }