| //===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This contains code to emit Aggregate Expr nodes as LLVM code. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CodeGenFunction.h" |
| #include "CodeGenModule.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/AST/StmtVisitor.h" |
| #include "llvm/Constants.h" |
| #include "llvm/Function.h" |
| #include "llvm/GlobalVariable.h" |
| #include "llvm/Support/Compiler.h" |
| #include "llvm/Intrinsics.h" |
| using namespace clang; |
| using namespace CodeGen; |
| |
| //===----------------------------------------------------------------------===// |
| // Aggregate Expression Emitter |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| class VISIBILITY_HIDDEN AggExprEmitter : public StmtVisitor<AggExprEmitter> { |
| CodeGenFunction &CGF; |
| CGBuilderTy &Builder; |
| llvm::Value *DestPtr; |
| bool VolatileDest; |
| bool IgnoreResult; |
| |
| public: |
| AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool v, |
| bool ignore) |
| : CGF(cgf), Builder(CGF.Builder), |
| DestPtr(destPtr), VolatileDest(v), 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); |
| |
| //===--------------------------------------------------------------------===// |
| // 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 VisitCStyleCastExpr(CStyleCastExpr *E); |
| void VisitImplicitCastExpr(ImplicitCastExpr *E); |
| void VisitCallExpr(const CallExpr *E); |
| void VisitStmtExpr(const StmtExpr *E); |
| void VisitBinaryOperator(const BinaryOperator *BO); |
| void VisitBinAssign(const BinaryOperator *E); |
| void VisitBinComma(const BinaryOperator *E); |
| |
| void VisitObjCMessageExpr(ObjCMessageExpr *E); |
| void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) { |
| EmitAggLoadOfLValue(E); |
| } |
| void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E); |
| void VisitObjCKVCRefExpr(ObjCKVCRefExpr *E); |
| |
| void VisitConditionalOperator(const ConditionalOperator *CO); |
| void VisitInitListExpr(InitListExpr *E); |
| void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { |
| Visit(DAE->getExpr()); |
| } |
| void VisitCXXConstructExpr(const CXXConstructExpr *E); |
| void VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E); |
| |
| void VisitVAArgExpr(VAArgExpr *E); |
| |
| void EmitInitializationToLValue(Expr *E, LValue Address); |
| void EmitNullInitializationToLValue(LValue Address, QualType T); |
| // case Expr::ChooseExprClass: |
| |
| }; |
| } // end anonymous namespace. |
| |
| //===----------------------------------------------------------------------===// |
| // Utilities |
| //===----------------------------------------------------------------------===// |
| |
| /// EmitAggLoadOfLValue - Given an expression with aggregate type that |
| /// represents a value lvalue, this method emits the address of the lvalue, |
| /// then loads the result into DestPtr. |
| void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) { |
| LValue LV = CGF.EmitLValue(E); |
| EmitFinalDestCopy(E, LV); |
| } |
| |
| /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. |
| void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) { |
| assert(Src.isAggregate() && "value must be aggregate value!"); |
| |
| // If the result is ignored, don't copy from the value. |
| if (DestPtr == 0) { |
| if (!Src.isVolatileQualified() || (IgnoreResult && Ignore)) |
| return; |
| // If the source is volatile, we must read from it; to do that, we need |
| // some place to put it. |
| DestPtr = CGF.CreateTempAlloca(CGF.ConvertType(E->getType()), "agg.tmp"); |
| } |
| |
| // If the result of the assignment is used, copy the LHS there also. |
| // FIXME: Pass VolatileDest as well. I think we also need to merge volatile |
| // from the source as well, as we can't eliminate it if either operand |
| // is volatile, unless copy has volatile for both source and destination.. |
| CGF.EmitAggregateCopy(DestPtr, Src.getAggregateAddr(), E->getType(), |
| VolatileDest|Src.isVolatileQualified()); |
| } |
| |
| /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. |
| void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) { |
| assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc"); |
| |
| EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(), |
| Src.isVolatileQualified()), |
| Ignore); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Visitor Methods |
| //===----------------------------------------------------------------------===// |
| |
| void AggExprEmitter::VisitCStyleCastExpr(CStyleCastExpr *E) { |
| // GCC union extension |
| if (E->getType()->isUnionType()) { |
| RecordDecl *SD = E->getType()->getAsRecordType()->getDecl(); |
| LValue FieldLoc = CGF.EmitLValueForField(DestPtr, |
| *SD->field_begin(CGF.getContext()), |
| true, 0); |
| EmitInitializationToLValue(E->getSubExpr(), FieldLoc); |
| return; |
| } |
| |
| Visit(E->getSubExpr()); |
| } |
| |
| void AggExprEmitter::VisitImplicitCastExpr(ImplicitCastExpr *E) { |
| assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(), |
| E->getType()) && |
| "Implicit cast types must be compatible"); |
| Visit(E->getSubExpr()); |
| } |
| |
| void AggExprEmitter::VisitCallExpr(const CallExpr *E) { |
| if (E->getCallReturnType()->isReferenceType()) { |
| EmitAggLoadOfLValue(E); |
| return; |
| } |
| |
| RValue RV = CGF.EmitCallExpr(E); |
| EmitFinalDestCopy(E, RV); |
| } |
| |
| void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) { |
| RValue RV = CGF.EmitObjCMessageExpr(E); |
| EmitFinalDestCopy(E, RV); |
| } |
| |
| void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) { |
| RValue RV = CGF.EmitObjCPropertyGet(E); |
| EmitFinalDestCopy(E, RV); |
| } |
| |
| void AggExprEmitter::VisitObjCKVCRefExpr(ObjCKVCRefExpr *E) { |
| RValue RV = CGF.EmitObjCPropertyGet(E); |
| EmitFinalDestCopy(E, RV); |
| } |
| |
| void AggExprEmitter::VisitBinComma(const BinaryOperator *E) { |
| CGF.EmitAnyExpr(E->getLHS()); |
| CGF.EmitAggExpr(E->getRHS(), DestPtr, VolatileDest); |
| } |
| |
| void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) { |
| CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest); |
| } |
| |
| void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) { |
| CGF.ErrorUnsupported(E, "aggregate binary expression"); |
| } |
| |
| void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) { |
| // For an assignment to work, the value on the right has |
| // to be compatible with the value on the left. |
| assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(), |
| E->getRHS()->getType()) |
| && "Invalid assignment"); |
| LValue LHS = CGF.EmitLValue(E->getLHS()); |
| |
| // We have to special case property setters, otherwise we must have |
| // a simple lvalue (no aggregates inside vectors, bitfields). |
| if (LHS.isPropertyRef()) { |
| llvm::Value *AggLoc = DestPtr; |
| if (!AggLoc) |
| AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType())); |
| CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest); |
| CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(), |
| RValue::getAggregate(AggLoc, VolatileDest)); |
| } |
| else if (LHS.isKVCRef()) { |
| llvm::Value *AggLoc = DestPtr; |
| if (!AggLoc) |
| AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType())); |
| CGF.EmitAggExpr(E->getRHS(), AggLoc, VolatileDest); |
| CGF.EmitObjCPropertySet(LHS.getKVCRefExpr(), |
| RValue::getAggregate(AggLoc, VolatileDest)); |
| } else { |
| // Codegen the RHS so that it stores directly into the LHS. |
| CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), LHS.isVolatileQualified()); |
| EmitFinalDestCopy(E, LHS, true); |
| } |
| } |
| |
| void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) { |
| llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true"); |
| llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false"); |
| llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end"); |
| |
| llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond()); |
| Builder.CreateCondBr(Cond, LHSBlock, RHSBlock); |
| |
| CGF.EmitBlock(LHSBlock); |
| |
| // Handle the GNU extension for missing LHS. |
| assert(E->getLHS() && "Must have LHS for aggregate value"); |
| |
| Visit(E->getLHS()); |
| CGF.EmitBranch(ContBlock); |
| |
| CGF.EmitBlock(RHSBlock); |
| |
| Visit(E->getRHS()); |
| CGF.EmitBranch(ContBlock); |
| |
| CGF.EmitBlock(ContBlock); |
| } |
| |
| void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) { |
| llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr()); |
| llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType()); |
| |
| if (!ArgPtr) { |
| CGF.ErrorUnsupported(VE, "aggregate va_arg expression"); |
| return; |
| } |
| |
| EmitFinalDestCopy(VE, LValue::MakeAddr(ArgPtr, 0)); |
| } |
| |
| void |
| AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) { |
| llvm::Value *V = DestPtr; |
| |
| if (!V) { |
| assert(isa<CXXTempVarDecl>(E->getVarDecl()) && |
| "Must have a temp var decl when there's no destination!"); |
| |
| V = CGF.CreateTempAlloca(CGF.ConvertType(E->getVarDecl()->getType()), |
| "tmpvar"); |
| } |
| |
| CGF.EmitCXXConstructExpr(V, E); |
| } |
| |
| void AggExprEmitter::VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) { |
| // FIXME: Do something with the temporaries! |
| Visit(E->getSubExpr()); |
| } |
| |
| void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) { |
| // FIXME: Are initializers affected by volatile? |
| if (isa<ImplicitValueInitExpr>(E)) { |
| EmitNullInitializationToLValue(LV, E->getType()); |
| } else if (E->getType()->isComplexType()) { |
| CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false); |
| } else if (CGF.hasAggregateLLVMType(E->getType())) { |
| CGF.EmitAnyExpr(E, LV.getAddress(), false); |
| } else { |
| CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, E->getType()); |
| } |
| } |
| |
| void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) { |
| if (!CGF.hasAggregateLLVMType(T)) { |
| // For non-aggregates, we can store zero |
| llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T)); |
| CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T); |
| } else { |
| // Otherwise, just memset the whole thing to zero. This is legal |
| // because in LLVM, all default initializers are guaranteed to have a |
| // bit pattern of all zeros. |
| // FIXME: That isn't true for member pointers! |
| // There's a potential optimization opportunity in combining |
| // memsets; that would be easy for arrays, but relatively |
| // difficult for structures with the current code. |
| CGF.EmitMemSetToZero(LV.getAddress(), T); |
| } |
| } |
| |
| void AggExprEmitter::VisitInitListExpr(InitListExpr *E) { |
| #if 0 |
| // FIXME: Disabled while we figure out what to do about |
| // test/CodeGen/bitfield.c |
| // |
| // If we can, prefer a copy from a global; this is a lot less code for long |
| // globals, and it's easier for the current optimizers to analyze. |
| // FIXME: Should we really be doing this? Should we try to avoid cases where |
| // we emit a global with a lot of zeros? Should we try to avoid short |
| // globals? |
| if (E->isConstantInitializer(CGF.getContext(), 0)) { |
| llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, &CGF); |
| llvm::GlobalVariable* GV = |
| new llvm::GlobalVariable(C->getType(), true, |
| llvm::GlobalValue::InternalLinkage, |
| C, "", &CGF.CGM.getModule(), 0); |
| EmitFinalDestCopy(E, LValue::MakeAddr(GV, 0)); |
| return; |
| } |
| #endif |
| if (E->hadArrayRangeDesignator()) { |
| CGF.ErrorUnsupported(E, "GNU array range designator extension"); |
| } |
| |
| // Handle initialization of an array. |
| if (E->getType()->isArrayType()) { |
| const llvm::PointerType *APType = |
| cast<llvm::PointerType>(DestPtr->getType()); |
| const llvm::ArrayType *AType = |
| cast<llvm::ArrayType>(APType->getElementType()); |
| |
| uint64_t NumInitElements = E->getNumInits(); |
| |
| if (E->getNumInits() > 0) { |
| QualType T1 = E->getType(); |
| QualType T2 = E->getInit(0)->getType(); |
| if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) { |
| EmitAggLoadOfLValue(E->getInit(0)); |
| return; |
| } |
| } |
| |
| uint64_t NumArrayElements = AType->getNumElements(); |
| QualType ElementType = CGF.getContext().getCanonicalType(E->getType()); |
| ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType(); |
| |
| unsigned CVRqualifier = ElementType.getCVRQualifiers(); |
| |
| for (uint64_t i = 0; i != NumArrayElements; ++i) { |
| llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array"); |
| if (i < NumInitElements) |
| EmitInitializationToLValue(E->getInit(i), |
| LValue::MakeAddr(NextVal, CVRqualifier)); |
| else |
| EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, CVRqualifier), |
| ElementType); |
| } |
| return; |
| } |
| |
| assert(E->getType()->isRecordType() && "Only support structs/unions here!"); |
| |
| // Do struct initialization; this code just sets each individual member |
| // to the approprate value. This makes bitfield support automatic; |
| // the disadvantage is that the generated code is more difficult for |
| // the optimizer, especially with bitfields. |
| unsigned NumInitElements = E->getNumInits(); |
| RecordDecl *SD = E->getType()->getAsRecordType()->getDecl(); |
| unsigned CurInitVal = 0; |
| |
| if (E->getType()->isUnionType()) { |
| // Only initialize one field of a union. The field itself is |
| // specified by the initializer list. |
| if (!E->getInitializedFieldInUnion()) { |
| // Empty union; we have nothing to do. |
| |
| #ifndef NDEBUG |
| // Make sure that it's really an empty and not a failure of |
| // semantic analysis. |
| for (RecordDecl::field_iterator Field = SD->field_begin(CGF.getContext()), |
| FieldEnd = SD->field_end(CGF.getContext()); |
| Field != FieldEnd; ++Field) |
| assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed"); |
| #endif |
| return; |
| } |
| |
| // FIXME: volatility |
| FieldDecl *Field = E->getInitializedFieldInUnion(); |
| LValue FieldLoc = CGF.EmitLValueForField(DestPtr, Field, true, 0); |
| |
| if (NumInitElements) { |
| // Store the initializer into the field |
| EmitInitializationToLValue(E->getInit(0), FieldLoc); |
| } else { |
| // Default-initialize to null |
| EmitNullInitializationToLValue(FieldLoc, Field->getType()); |
| } |
| |
| return; |
| } |
| |
| // Here we iterate over the fields; this makes it simpler to both |
| // default-initialize fields and skip over unnamed fields. |
| for (RecordDecl::field_iterator Field = SD->field_begin(CGF.getContext()), |
| FieldEnd = SD->field_end(CGF.getContext()); |
| Field != FieldEnd; ++Field) { |
| // We're done once we hit the flexible array member |
| if (Field->getType()->isIncompleteArrayType()) |
| break; |
| |
| if (Field->isUnnamedBitfield()) |
| continue; |
| |
| // FIXME: volatility |
| LValue FieldLoc = CGF.EmitLValueForField(DestPtr, *Field, false, 0); |
| // We never generate write-barries for initialized fields. |
| LValue::SetObjCNonGC(FieldLoc, true); |
| if (CurInitVal < NumInitElements) { |
| // Store the initializer into the field |
| EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc); |
| } else { |
| // We're out of initalizers; default-initialize to null |
| EmitNullInitializationToLValue(FieldLoc, Field->getType()); |
| } |
| } |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Entry Points into this File |
| //===----------------------------------------------------------------------===// |
| |
| /// EmitAggExpr - Emit the computation of the specified expression of aggregate |
| /// type. The result is computed into DestPtr. Note that if DestPtr is null, |
| /// the value of the aggregate expression is not needed. If VolatileDest is |
| /// true, DestPtr cannot be 0. |
| void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr, |
| bool VolatileDest, bool IgnoreResult) { |
| 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)); |
| } |