| //===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===// |
| // |
| // 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 Decl nodes as LLVM code. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CGDebugInfo.h" |
| #include "CodeGenFunction.h" |
| #include "CodeGenModule.h" |
| #include "CGBlocks.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/CharUnits.h" |
| #include "clang/AST/Decl.h" |
| #include "clang/AST/DeclObjC.h" |
| #include "clang/Basic/SourceManager.h" |
| #include "clang/Basic/TargetInfo.h" |
| #include "clang/Frontend/CodeGenOptions.h" |
| #include "llvm/GlobalVariable.h" |
| #include "llvm/Intrinsics.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Type.h" |
| using namespace clang; |
| using namespace CodeGen; |
| |
| |
| void CodeGenFunction::EmitDecl(const Decl &D) { |
| switch (D.getKind()) { |
| case Decl::TranslationUnit: |
| case Decl::Namespace: |
| case Decl::UnresolvedUsingTypename: |
| case Decl::ClassTemplateSpecialization: |
| case Decl::ClassTemplatePartialSpecialization: |
| case Decl::TemplateTypeParm: |
| case Decl::UnresolvedUsingValue: |
| case Decl::NonTypeTemplateParm: |
| case Decl::CXXMethod: |
| case Decl::CXXConstructor: |
| case Decl::CXXDestructor: |
| case Decl::CXXConversion: |
| case Decl::Field: |
| case Decl::IndirectField: |
| case Decl::ObjCIvar: |
| case Decl::ObjCAtDefsField: |
| case Decl::ParmVar: |
| case Decl::ImplicitParam: |
| case Decl::ClassTemplate: |
| case Decl::FunctionTemplate: |
| case Decl::TemplateTemplateParm: |
| case Decl::ObjCMethod: |
| case Decl::ObjCCategory: |
| case Decl::ObjCProtocol: |
| case Decl::ObjCInterface: |
| case Decl::ObjCCategoryImpl: |
| case Decl::ObjCImplementation: |
| case Decl::ObjCProperty: |
| case Decl::ObjCCompatibleAlias: |
| case Decl::AccessSpec: |
| case Decl::LinkageSpec: |
| case Decl::ObjCPropertyImpl: |
| case Decl::ObjCClass: |
| case Decl::ObjCForwardProtocol: |
| case Decl::FileScopeAsm: |
| case Decl::Friend: |
| case Decl::FriendTemplate: |
| case Decl::Block: |
| assert(0 && "Declaration not should not be in declstmts!"); |
| case Decl::Function: // void X(); |
| case Decl::Record: // struct/union/class X; |
| case Decl::Enum: // enum X; |
| case Decl::EnumConstant: // enum ? { X = ? } |
| case Decl::CXXRecord: // struct/union/class X; [C++] |
| case Decl::Using: // using X; [C++] |
| case Decl::UsingShadow: |
| case Decl::UsingDirective: // using namespace X; [C++] |
| case Decl::NamespaceAlias: |
| case Decl::StaticAssert: // static_assert(X, ""); [C++0x] |
| case Decl::Label: // __label__ x; |
| // None of these decls require codegen support. |
| return; |
| |
| case Decl::Var: { |
| const VarDecl &VD = cast<VarDecl>(D); |
| assert(VD.isLocalVarDecl() && |
| "Should not see file-scope variables inside a function!"); |
| return EmitVarDecl(VD); |
| } |
| |
| case Decl::Typedef: { // typedef int X; |
| const TypedefDecl &TD = cast<TypedefDecl>(D); |
| QualType Ty = TD.getUnderlyingType(); |
| |
| if (Ty->isVariablyModifiedType()) |
| EmitVLASize(Ty); |
| } |
| } |
| } |
| |
| /// EmitVarDecl - This method handles emission of any variable declaration |
| /// inside a function, including static vars etc. |
| void CodeGenFunction::EmitVarDecl(const VarDecl &D) { |
| switch (D.getStorageClass()) { |
| case SC_None: |
| case SC_Auto: |
| case SC_Register: |
| return EmitAutoVarDecl(D); |
| case SC_Static: { |
| llvm::GlobalValue::LinkageTypes Linkage = |
| llvm::GlobalValue::InternalLinkage; |
| |
| // If the function definition has some sort of weak linkage, its |
| // static variables should also be weak so that they get properly |
| // uniqued. We can't do this in C, though, because there's no |
| // standard way to agree on which variables are the same (i.e. |
| // there's no mangling). |
| if (getContext().getLangOptions().CPlusPlus) |
| if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage())) |
| Linkage = CurFn->getLinkage(); |
| |
| return EmitStaticVarDecl(D, Linkage); |
| } |
| case SC_Extern: |
| case SC_PrivateExtern: |
| // Don't emit it now, allow it to be emitted lazily on its first use. |
| return; |
| } |
| |
| assert(0 && "Unknown storage class"); |
| } |
| |
| static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D, |
| const char *Separator) { |
| CodeGenModule &CGM = CGF.CGM; |
| if (CGF.getContext().getLangOptions().CPlusPlus) { |
| llvm::StringRef Name = CGM.getMangledName(&D); |
| return Name.str(); |
| } |
| |
| std::string ContextName; |
| if (!CGF.CurFuncDecl) { |
| // Better be in a block declared in global scope. |
| const NamedDecl *ND = cast<NamedDecl>(&D); |
| const DeclContext *DC = ND->getDeclContext(); |
| if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) { |
| MangleBuffer Name; |
| CGM.getBlockMangledName(GlobalDecl(), Name, BD); |
| ContextName = Name.getString(); |
| } |
| else |
| assert(0 && "Unknown context for block static var decl"); |
| } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) { |
| llvm::StringRef Name = CGM.getMangledName(FD); |
| ContextName = Name.str(); |
| } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl)) |
| ContextName = CGF.CurFn->getName(); |
| else |
| assert(0 && "Unknown context for static var decl"); |
| |
| return ContextName + Separator + D.getNameAsString(); |
| } |
| |
| llvm::GlobalVariable * |
| CodeGenFunction::CreateStaticVarDecl(const VarDecl &D, |
| const char *Separator, |
| llvm::GlobalValue::LinkageTypes Linkage) { |
| QualType Ty = D.getType(); |
| assert(Ty->isConstantSizeType() && "VLAs can't be static"); |
| |
| std::string Name = GetStaticDeclName(*this, D, Separator); |
| |
| const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty); |
| llvm::GlobalVariable *GV = |
| new llvm::GlobalVariable(CGM.getModule(), LTy, |
| Ty.isConstant(getContext()), Linkage, |
| CGM.EmitNullConstant(D.getType()), Name, 0, |
| D.isThreadSpecified(), Ty.getAddressSpace()); |
| GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); |
| if (Linkage != llvm::GlobalValue::InternalLinkage) |
| GV->setVisibility(CurFn->getVisibility()); |
| return GV; |
| } |
| |
| /// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the |
| /// global variable that has already been created for it. If the initializer |
| /// has a different type than GV does, this may free GV and return a different |
| /// one. Otherwise it just returns GV. |
| llvm::GlobalVariable * |
| CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D, |
| llvm::GlobalVariable *GV) { |
| llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this); |
| |
| // If constant emission failed, then this should be a C++ static |
| // initializer. |
| if (!Init) { |
| if (!getContext().getLangOptions().CPlusPlus) |
| CGM.ErrorUnsupported(D.getInit(), "constant l-value expression"); |
| else if (Builder.GetInsertBlock()) { |
| // Since we have a static initializer, this global variable can't |
| // be constant. |
| GV->setConstant(false); |
| |
| EmitCXXGuardedInit(D, GV); |
| } |
| return GV; |
| } |
| |
| // The initializer may differ in type from the global. Rewrite |
| // the global to match the initializer. (We have to do this |
| // because some types, like unions, can't be completely represented |
| // in the LLVM type system.) |
| if (GV->getType()->getElementType() != Init->getType()) { |
| llvm::GlobalVariable *OldGV = GV; |
| |
| GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(), |
| OldGV->isConstant(), |
| OldGV->getLinkage(), Init, "", |
| /*InsertBefore*/ OldGV, |
| D.isThreadSpecified(), |
| D.getType().getAddressSpace()); |
| GV->setVisibility(OldGV->getVisibility()); |
| |
| // Steal the name of the old global |
| GV->takeName(OldGV); |
| |
| // Replace all uses of the old global with the new global |
| llvm::Constant *NewPtrForOldDecl = |
| llvm::ConstantExpr::getBitCast(GV, OldGV->getType()); |
| OldGV->replaceAllUsesWith(NewPtrForOldDecl); |
| |
| // Erase the old global, since it is no longer used. |
| OldGV->eraseFromParent(); |
| } |
| |
| GV->setInitializer(Init); |
| return GV; |
| } |
| |
| void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D, |
| llvm::GlobalValue::LinkageTypes Linkage) { |
| llvm::Value *&DMEntry = LocalDeclMap[&D]; |
| assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); |
| |
| llvm::GlobalVariable *GV = CreateStaticVarDecl(D, ".", Linkage); |
| |
| // Store into LocalDeclMap before generating initializer to handle |
| // circular references. |
| DMEntry = GV; |
| |
| // We can't have a VLA here, but we can have a pointer to a VLA, |
| // even though that doesn't really make any sense. |
| // Make sure to evaluate VLA bounds now so that we have them for later. |
| if (D.getType()->isVariablyModifiedType()) |
| EmitVLASize(D.getType()); |
| |
| // Local static block variables must be treated as globals as they may be |
| // referenced in their RHS initializer block-literal expresion. |
| CGM.setStaticLocalDeclAddress(&D, GV); |
| |
| // If this value has an initializer, emit it. |
| if (D.getInit()) |
| GV = AddInitializerToStaticVarDecl(D, GV); |
| |
| GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); |
| |
| // FIXME: Merge attribute handling. |
| if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) { |
| SourceManager &SM = CGM.getContext().getSourceManager(); |
| llvm::Constant *Ann = |
| CGM.EmitAnnotateAttr(GV, AA, |
| SM.getInstantiationLineNumber(D.getLocation())); |
| CGM.AddAnnotation(Ann); |
| } |
| |
| if (const SectionAttr *SA = D.getAttr<SectionAttr>()) |
| GV->setSection(SA->getName()); |
| |
| if (D.hasAttr<UsedAttr>()) |
| CGM.AddUsedGlobal(GV); |
| |
| // We may have to cast the constant because of the initializer |
| // mismatch above. |
| // |
| // FIXME: It is really dangerous to store this in the map; if anyone |
| // RAUW's the GV uses of this constant will be invalid. |
| const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType()); |
| const llvm::Type *LPtrTy = LTy->getPointerTo(D.getType().getAddressSpace()); |
| DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy); |
| |
| // Emit global variable debug descriptor for static vars. |
| CGDebugInfo *DI = getDebugInfo(); |
| if (DI) { |
| DI->setLocation(D.getLocation()); |
| DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D); |
| } |
| } |
| |
| unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const { |
| assert(ByRefValueInfo.count(VD) && "Did not find value!"); |
| |
| return ByRefValueInfo.find(VD)->second.second; |
| } |
| |
| llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr, |
| const VarDecl *V) { |
| llvm::Value *Loc = Builder.CreateStructGEP(BaseAddr, 1, "forwarding"); |
| Loc = Builder.CreateLoad(Loc); |
| Loc = Builder.CreateStructGEP(Loc, getByRefValueLLVMField(V), |
| V->getNameAsString()); |
| return Loc; |
| } |
| |
| /// BuildByRefType - This routine changes a __block variable declared as T x |
| /// into: |
| /// |
| /// struct { |
| /// void *__isa; |
| /// void *__forwarding; |
| /// int32_t __flags; |
| /// int32_t __size; |
| /// void *__copy_helper; // only if needed |
| /// void *__destroy_helper; // only if needed |
| /// char padding[X]; // only if needed |
| /// T x; |
| /// } x |
| /// |
| const llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) { |
| std::pair<const llvm::Type *, unsigned> &Info = ByRefValueInfo[D]; |
| if (Info.first) |
| return Info.first; |
| |
| QualType Ty = D->getType(); |
| |
| std::vector<const llvm::Type *> Types; |
| |
| llvm::PATypeHolder ByRefTypeHolder = llvm::OpaqueType::get(getLLVMContext()); |
| |
| // void *__isa; |
| Types.push_back(Int8PtrTy); |
| |
| // void *__forwarding; |
| Types.push_back(llvm::PointerType::getUnqual(ByRefTypeHolder)); |
| |
| // int32_t __flags; |
| Types.push_back(Int32Ty); |
| |
| // int32_t __size; |
| Types.push_back(Int32Ty); |
| |
| bool HasCopyAndDispose = getContext().BlockRequiresCopying(Ty); |
| if (HasCopyAndDispose) { |
| /// void *__copy_helper; |
| Types.push_back(Int8PtrTy); |
| |
| /// void *__destroy_helper; |
| Types.push_back(Int8PtrTy); |
| } |
| |
| bool Packed = false; |
| CharUnits Align = getContext().getDeclAlign(D); |
| if (Align > getContext().toCharUnitsFromBits(Target.getPointerAlign(0))) { |
| // We have to insert padding. |
| |
| // The struct above has 2 32-bit integers. |
| unsigned CurrentOffsetInBytes = 4 * 2; |
| |
| // And either 2 or 4 pointers. |
| CurrentOffsetInBytes += (HasCopyAndDispose ? 4 : 2) * |
| CGM.getTargetData().getTypeAllocSize(Int8PtrTy); |
| |
| // Align the offset. |
| unsigned AlignedOffsetInBytes = |
| llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity()); |
| |
| unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes; |
| if (NumPaddingBytes > 0) { |
| const llvm::Type *Ty = llvm::Type::getInt8Ty(getLLVMContext()); |
| // FIXME: We need a sema error for alignment larger than the minimum of |
| // the maximal stack alignmint and the alignment of malloc on the system. |
| if (NumPaddingBytes > 1) |
| Ty = llvm::ArrayType::get(Ty, NumPaddingBytes); |
| |
| Types.push_back(Ty); |
| |
| // We want a packed struct. |
| Packed = true; |
| } |
| } |
| |
| // T x; |
| Types.push_back(ConvertTypeForMem(Ty)); |
| |
| const llvm::Type *T = llvm::StructType::get(getLLVMContext(), Types, Packed); |
| |
| cast<llvm::OpaqueType>(ByRefTypeHolder.get())->refineAbstractTypeTo(T); |
| CGM.getModule().addTypeName("struct.__block_byref_" + D->getNameAsString(), |
| ByRefTypeHolder.get()); |
| |
| Info.first = ByRefTypeHolder.get(); |
| |
| Info.second = Types.size() - 1; |
| |
| return Info.first; |
| } |
| |
| namespace { |
| struct CallArrayDtor : EHScopeStack::Cleanup { |
| CallArrayDtor(const CXXDestructorDecl *Dtor, |
| const ConstantArrayType *Type, |
| llvm::Value *Loc) |
| : Dtor(Dtor), Type(Type), Loc(Loc) {} |
| |
| const CXXDestructorDecl *Dtor; |
| const ConstantArrayType *Type; |
| llvm::Value *Loc; |
| |
| void Emit(CodeGenFunction &CGF, bool IsForEH) { |
| QualType BaseElementTy = CGF.getContext().getBaseElementType(Type); |
| const llvm::Type *BasePtr = CGF.ConvertType(BaseElementTy); |
| BasePtr = llvm::PointerType::getUnqual(BasePtr); |
| llvm::Value *BaseAddrPtr = CGF.Builder.CreateBitCast(Loc, BasePtr); |
| CGF.EmitCXXAggrDestructorCall(Dtor, Type, BaseAddrPtr); |
| } |
| }; |
| |
| struct CallVarDtor : EHScopeStack::Cleanup { |
| CallVarDtor(const CXXDestructorDecl *Dtor, |
| llvm::Value *NRVOFlag, |
| llvm::Value *Loc) |
| : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(Loc) {} |
| |
| const CXXDestructorDecl *Dtor; |
| llvm::Value *NRVOFlag; |
| llvm::Value *Loc; |
| |
| void Emit(CodeGenFunction &CGF, bool IsForEH) { |
| // Along the exceptions path we always execute the dtor. |
| bool NRVO = !IsForEH && NRVOFlag; |
| |
| llvm::BasicBlock *SkipDtorBB = 0; |
| if (NRVO) { |
| // If we exited via NRVO, we skip the destructor call. |
| llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused"); |
| SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor"); |
| llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val"); |
| CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB); |
| CGF.EmitBlock(RunDtorBB); |
| } |
| |
| CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, |
| /*ForVirtualBase=*/false, Loc); |
| |
| if (NRVO) CGF.EmitBlock(SkipDtorBB); |
| } |
| }; |
| } |
| |
| namespace { |
| struct CallStackRestore : EHScopeStack::Cleanup { |
| llvm::Value *Stack; |
| CallStackRestore(llvm::Value *Stack) : Stack(Stack) {} |
| void Emit(CodeGenFunction &CGF, bool IsForEH) { |
| llvm::Value *V = CGF.Builder.CreateLoad(Stack, "tmp"); |
| llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore); |
| CGF.Builder.CreateCall(F, V); |
| } |
| }; |
| |
| struct CallCleanupFunction : EHScopeStack::Cleanup { |
| llvm::Constant *CleanupFn; |
| const CGFunctionInfo &FnInfo; |
| const VarDecl &Var; |
| |
| CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info, |
| const VarDecl *Var) |
| : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {} |
| |
| void Emit(CodeGenFunction &CGF, bool IsForEH) { |
| DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue, |
| SourceLocation()); |
| // Compute the address of the local variable, in case it's a byref |
| // or something. |
| llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress(); |
| |
| // In some cases, the type of the function argument will be different from |
| // the type of the pointer. An example of this is |
| // void f(void* arg); |
| // __attribute__((cleanup(f))) void *g; |
| // |
| // To fix this we insert a bitcast here. |
| QualType ArgTy = FnInfo.arg_begin()->type; |
| llvm::Value *Arg = |
| CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy)); |
| |
| CallArgList Args; |
| Args.push_back(std::make_pair(RValue::get(Arg), |
| CGF.getContext().getPointerType(Var.getType()))); |
| CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args); |
| } |
| }; |
| |
| struct CallBlockRelease : EHScopeStack::Cleanup { |
| llvm::Value *Addr; |
| CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {} |
| |
| void Emit(CodeGenFunction &CGF, bool IsForEH) { |
| CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF); |
| } |
| }; |
| } |
| |
| |
| /// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the |
| /// non-zero parts of the specified initializer with equal or fewer than |
| /// NumStores scalar stores. |
| static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init, |
| unsigned &NumStores) { |
| // Zero and Undef never requires any extra stores. |
| if (isa<llvm::ConstantAggregateZero>(Init) || |
| isa<llvm::ConstantPointerNull>(Init) || |
| isa<llvm::UndefValue>(Init)) |
| return true; |
| if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || |
| isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || |
| isa<llvm::ConstantExpr>(Init)) |
| return Init->isNullValue() || NumStores--; |
| |
| // See if we can emit each element. |
| if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) { |
| for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { |
| llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); |
| if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) |
| return false; |
| } |
| return true; |
| } |
| |
| // Anything else is hard and scary. |
| return false; |
| } |
| |
| /// emitStoresForInitAfterMemset - For inits that |
| /// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar |
| /// stores that would be required. |
| static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc, |
| bool isVolatile, CGBuilderTy &Builder) { |
| // Zero doesn't require any stores. |
| if (isa<llvm::ConstantAggregateZero>(Init) || |
| isa<llvm::ConstantPointerNull>(Init) || |
| isa<llvm::UndefValue>(Init)) |
| return; |
| |
| if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || |
| isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || |
| isa<llvm::ConstantExpr>(Init)) { |
| if (!Init->isNullValue()) |
| Builder.CreateStore(Init, Loc, isVolatile); |
| return; |
| } |
| |
| assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) && |
| "Unknown value type!"); |
| |
| for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { |
| llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); |
| if (Elt->isNullValue()) continue; |
| |
| // Otherwise, get a pointer to the element and emit it. |
| emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i), |
| isVolatile, Builder); |
| } |
| } |
| |
| |
| /// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset |
| /// plus some stores to initialize a local variable instead of using a memcpy |
| /// from a constant global. It is beneficial to use memset if the global is all |
| /// zeros, or mostly zeros and large. |
| static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init, |
| uint64_t GlobalSize) { |
| // If a global is all zeros, always use a memset. |
| if (isa<llvm::ConstantAggregateZero>(Init)) return true; |
| |
| |
| // If a non-zero global is <= 32 bytes, always use a memcpy. If it is large, |
| // do it if it will require 6 or fewer scalar stores. |
| // TODO: Should budget depends on the size? Avoiding a large global warrants |
| // plopping in more stores. |
| unsigned StoreBudget = 6; |
| uint64_t SizeLimit = 32; |
| |
| return GlobalSize > SizeLimit && |
| canEmitInitWithFewStoresAfterMemset(Init, StoreBudget); |
| } |
| |
| |
| /// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a |
| /// variable declaration with auto, register, or no storage class specifier. |
| /// These turn into simple stack objects, or GlobalValues depending on target. |
| void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) { |
| AutoVarEmission emission = EmitAutoVarAlloca(D); |
| EmitAutoVarInit(emission); |
| EmitAutoVarCleanups(emission); |
| } |
| |
| /// EmitAutoVarAlloca - Emit the alloca and debug information for a |
| /// local variable. Does not emit initalization or destruction. |
| CodeGenFunction::AutoVarEmission |
| CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) { |
| QualType Ty = D.getType(); |
| |
| AutoVarEmission emission(D); |
| |
| bool isByRef = D.hasAttr<BlocksAttr>(); |
| emission.IsByRef = isByRef; |
| |
| CharUnits alignment = getContext().getDeclAlign(&D); |
| emission.Alignment = alignment; |
| |
| llvm::Value *DeclPtr; |
| if (Ty->isConstantSizeType()) { |
| if (!Target.useGlobalsForAutomaticVariables()) { |
| bool NRVO = getContext().getLangOptions().ElideConstructors && |
| D.isNRVOVariable(); |
| |
| // If this value is a POD array or struct with a statically |
| // determinable constant initializer, there are optimizations we |
| // can do. |
| // TODO: we can potentially constant-evaluate non-POD structs and |
| // arrays as long as the initialization is trivial (e.g. if they |
| // have a non-trivial destructor, but not a non-trivial constructor). |
| if (D.getInit() && |
| (Ty->isArrayType() || Ty->isRecordType()) && Ty->isPODType() && |
| D.getInit()->isConstantInitializer(getContext(), false)) { |
| |
| // If the variable's a const type, and it's neither an NRVO |
| // candidate nor a __block variable, emit it as a global instead. |
| if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() && |
| !NRVO && !isByRef) { |
| EmitStaticVarDecl(D, llvm::GlobalValue::PrivateLinkage); |
| |
| emission.Address = 0; // signal this condition to later callbacks |
| assert(emission.wasEmittedAsGlobal()); |
| return emission; |
| } |
| |
| // Otherwise, tell the initialization code that we're in this case. |
| emission.IsConstantAggregate = true; |
| } |
| |
| // A normal fixed sized variable becomes an alloca in the entry block, |
| // unless it's an NRVO variable. |
| const llvm::Type *LTy = ConvertTypeForMem(Ty); |
| |
| if (NRVO) { |
| // The named return value optimization: allocate this variable in the |
| // return slot, so that we can elide the copy when returning this |
| // variable (C++0x [class.copy]p34). |
| DeclPtr = ReturnValue; |
| |
| if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { |
| if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) { |
| // Create a flag that is used to indicate when the NRVO was applied |
| // to this variable. Set it to zero to indicate that NRVO was not |
| // applied. |
| llvm::Value *Zero = Builder.getFalse(); |
| llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo"); |
| EnsureInsertPoint(); |
| Builder.CreateStore(Zero, NRVOFlag); |
| |
| // Record the NRVO flag for this variable. |
| NRVOFlags[&D] = NRVOFlag; |
| emission.NRVOFlag = NRVOFlag; |
| } |
| } |
| } else { |
| if (isByRef) |
| LTy = BuildByRefType(&D); |
| |
| llvm::AllocaInst *Alloc = CreateTempAlloca(LTy); |
| Alloc->setName(D.getNameAsString()); |
| |
| CharUnits allocaAlignment = alignment; |
| if (isByRef) |
| allocaAlignment = std::max(allocaAlignment, |
| getContext().toCharUnitsFromBits(Target.getPointerAlign(0))); |
| Alloc->setAlignment(allocaAlignment.getQuantity()); |
| DeclPtr = Alloc; |
| } |
| } else { |
| // Targets that don't support recursion emit locals as globals. |
| const char *Class = |
| D.getStorageClass() == SC_Register ? ".reg." : ".auto."; |
| DeclPtr = CreateStaticVarDecl(D, Class, |
| llvm::GlobalValue::InternalLinkage); |
| } |
| |
| // FIXME: Can this happen? |
| if (Ty->isVariablyModifiedType()) |
| EmitVLASize(Ty); |
| } else { |
| EnsureInsertPoint(); |
| |
| if (!DidCallStackSave) { |
| // Save the stack. |
| llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack"); |
| |
| llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave); |
| llvm::Value *V = Builder.CreateCall(F); |
| |
| Builder.CreateStore(V, Stack); |
| |
| DidCallStackSave = true; |
| |
| // Push a cleanup block and restore the stack there. |
| // FIXME: in general circumstances, this should be an EH cleanup. |
| EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack); |
| } |
| |
| // Get the element type. |
| const llvm::Type *LElemTy = ConvertTypeForMem(Ty); |
| const llvm::Type *LElemPtrTy = LElemTy->getPointerTo(Ty.getAddressSpace()); |
| |
| llvm::Value *VLASize = EmitVLASize(Ty); |
| |
| // Allocate memory for the array. |
| llvm::AllocaInst *VLA = |
| Builder.CreateAlloca(llvm::Type::getInt8Ty(getLLVMContext()), VLASize, "vla"); |
| VLA->setAlignment(alignment.getQuantity()); |
| |
| DeclPtr = Builder.CreateBitCast(VLA, LElemPtrTy, "tmp"); |
| } |
| |
| llvm::Value *&DMEntry = LocalDeclMap[&D]; |
| assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); |
| DMEntry = DeclPtr; |
| emission.Address = DeclPtr; |
| |
| // Emit debug info for local var declaration. |
| if (CGDebugInfo *DI = getDebugInfo()) { |
| assert(HaveInsertPoint() && "Unexpected unreachable point!"); |
| |
| DI->setLocation(D.getLocation()); |
| if (Target.useGlobalsForAutomaticVariables()) { |
| DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D); |
| } else |
| DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder); |
| } |
| |
| return emission; |
| } |
| |
| /// Determines whether the given __block variable is potentially |
| /// captured by the given expression. |
| static bool isCapturedBy(const VarDecl &var, const Expr *e) { |
| // Skip the most common kinds of expressions that make |
| // hierarchy-walking expensive. |
| e = e->IgnoreParenCasts(); |
| |
| if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { |
| const BlockDecl *block = be->getBlockDecl(); |
| for (BlockDecl::capture_const_iterator i = block->capture_begin(), |
| e = block->capture_end(); i != e; ++i) { |
| if (i->getVariable() == &var) |
| return true; |
| } |
| |
| // No need to walk into the subexpressions. |
| return false; |
| } |
| |
| for (Stmt::const_child_range children = e->children(); children; ++children) |
| if (isCapturedBy(var, cast<Expr>(*children))) |
| return true; |
| |
| return false; |
| } |
| |
| void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) { |
| assert(emission.Variable && "emission was not valid!"); |
| |
| // If this was emitted as a global constant, we're done. |
| if (emission.wasEmittedAsGlobal()) return; |
| |
| const VarDecl &D = *emission.Variable; |
| QualType type = D.getType(); |
| |
| // If this local has an initializer, emit it now. |
| const Expr *Init = D.getInit(); |
| |
| // If we are at an unreachable point, we don't need to emit the initializer |
| // unless it contains a label. |
| if (!HaveInsertPoint()) { |
| if (!Init || !ContainsLabel(Init)) return; |
| EnsureInsertPoint(); |
| } |
| |
| CharUnits alignment = emission.Alignment; |
| |
| if (emission.IsByRef) { |
| llvm::Value *V; |
| |
| BlockFieldFlags fieldFlags; |
| bool fieldNeedsCopyDispose = false; |
| |
| if (type->isBlockPointerType()) { |
| fieldFlags |= BLOCK_FIELD_IS_BLOCK; |
| fieldNeedsCopyDispose = true; |
| } else if (getContext().isObjCNSObjectType(type) || |
| type->isObjCObjectPointerType()) { |
| fieldFlags |= BLOCK_FIELD_IS_OBJECT; |
| fieldNeedsCopyDispose = true; |
| } else if (getLangOptions().CPlusPlus) { |
| if (getContext().getBlockVarCopyInits(&D)) |
| fieldNeedsCopyDispose = true; |
| else if (const CXXRecordDecl *record = type->getAsCXXRecordDecl()) |
| fieldNeedsCopyDispose = !record->hasTrivialDestructor(); |
| } |
| |
| llvm::Value *addr = emission.Address; |
| |
| // FIXME: Someone double check this. |
| if (type.isObjCGCWeak()) |
| fieldFlags |= BLOCK_FIELD_IS_WEAK; |
| |
| // Initialize the 'isa', which is just 0 or 1. |
| int isa = 0; |
| if (fieldFlags & BLOCK_FIELD_IS_WEAK) |
| isa = 1; |
| V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa"); |
| Builder.CreateStore(V, Builder.CreateStructGEP(addr, 0, "byref.isa")); |
| |
| // Store the address of the variable into its own forwarding pointer. |
| Builder.CreateStore(addr, |
| Builder.CreateStructGEP(addr, 1, "byref.forwarding")); |
| |
| // Blocks ABI: |
| // c) the flags field is set to either 0 if no helper functions are |
| // needed or BLOCK_HAS_COPY_DISPOSE if they are, |
| BlockFlags flags; |
| if (fieldNeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE; |
| Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()), |
| Builder.CreateStructGEP(addr, 2, "byref.flags")); |
| |
| const llvm::Type *V1; |
| V1 = cast<llvm::PointerType>(addr->getType())->getElementType(); |
| V = llvm::ConstantInt::get(IntTy, CGM.GetTargetTypeStoreSize(V1).getQuantity()); |
| Builder.CreateStore(V, Builder.CreateStructGEP(addr, 3, "byref.size")); |
| |
| if (fieldNeedsCopyDispose) { |
| llvm::Value *copy_helper = Builder.CreateStructGEP(addr, 4); |
| Builder.CreateStore(CGM.BuildbyrefCopyHelper(addr->getType(), fieldFlags, |
| alignment.getQuantity(), &D), |
| copy_helper); |
| |
| llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5); |
| Builder.CreateStore(CGM.BuildbyrefDestroyHelper(addr->getType(), |
| fieldFlags, |
| alignment.getQuantity(), |
| &D), |
| destroy_helper); |
| } |
| } |
| |
| if (!Init) return; |
| |
| // Check whether this is a byref variable that's potentially |
| // captured and moved by its own initializer. If so, we'll need to |
| // emit the initializer first, then copy into the variable. |
| bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init); |
| |
| llvm::Value *Loc = |
| capturedByInit ? emission.Address : emission.getObjectAddress(*this); |
| |
| bool isVolatile = type.isVolatileQualified(); |
| |
| // If this is a simple aggregate initialization, we can optimize it |
| // in various ways. |
| if (emission.IsConstantAggregate) { |
| assert(!capturedByInit && "constant init contains a capturing block?"); |
| |
| llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), type, this); |
| assert(Init != 0 && "Wasn't a simple constant init?"); |
| |
| llvm::Value *SizeVal = |
| llvm::ConstantInt::get(IntPtrTy, |
| getContext().getTypeSizeInChars(type).getQuantity()); |
| |
| const llvm::Type *BP = Int8PtrTy; |
| if (Loc->getType() != BP) |
| Loc = Builder.CreateBitCast(Loc, BP, "tmp"); |
| |
| // If the initializer is all or mostly zeros, codegen with memset then do |
| // a few stores afterward. |
| if (shouldUseMemSetPlusStoresToInitialize(Init, |
| CGM.getTargetData().getTypeAllocSize(Init->getType()))) { |
| Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal, |
| alignment.getQuantity(), isVolatile); |
| if (!Init->isNullValue()) { |
| Loc = Builder.CreateBitCast(Loc, Init->getType()->getPointerTo()); |
| emitStoresForInitAfterMemset(Init, Loc, isVolatile, Builder); |
| } |
| } else { |
| // Otherwise, create a temporary global with the initializer then |
| // memcpy from the global to the alloca. |
| std::string Name = GetStaticDeclName(*this, D, "."); |
| llvm::GlobalVariable *GV = |
| new llvm::GlobalVariable(CGM.getModule(), Init->getType(), true, |
| llvm::GlobalValue::InternalLinkage, |
| Init, Name, 0, false, 0); |
| GV->setAlignment(alignment.getQuantity()); |
| |
| llvm::Value *SrcPtr = GV; |
| if (SrcPtr->getType() != BP) |
| SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp"); |
| |
| Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(), |
| isVolatile); |
| } |
| } else if (type->isReferenceType()) { |
| RValue RV = EmitReferenceBindingToExpr(Init, &D); |
| if (capturedByInit) Loc = BuildBlockByrefAddress(Loc, &D); |
| EmitStoreOfScalar(RV.getScalarVal(), Loc, false, alignment.getQuantity(), |
| type); |
| } else if (!hasAggregateLLVMType(type)) { |
| llvm::Value *V = EmitScalarExpr(Init); |
| if (capturedByInit) Loc = BuildBlockByrefAddress(Loc, &D); |
| EmitStoreOfScalar(V, Loc, isVolatile, alignment.getQuantity(), type); |
| } else if (type->isAnyComplexType()) { |
| ComplexPairTy complex = EmitComplexExpr(Init); |
| if (capturedByInit) Loc = BuildBlockByrefAddress(Loc, &D); |
| StoreComplexToAddr(complex, Loc, isVolatile); |
| } else { |
| // TODO: how can we delay here if D is captured by its initializer? |
| EmitAggExpr(Init, AggValueSlot::forAddr(Loc, isVolatile, true, false)); |
| } |
| } |
| |
| void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) { |
| assert(emission.Variable && "emission was not valid!"); |
| |
| // If this was emitted as a global constant, we're done. |
| if (emission.wasEmittedAsGlobal()) return; |
| |
| const VarDecl &D = *emission.Variable; |
| |
| // Handle C++ destruction of variables. |
| if (getLangOptions().CPlusPlus) { |
| QualType type = D.getType(); |
| QualType baseType = getContext().getBaseElementType(type); |
| if (const RecordType *RT = baseType->getAs<RecordType>()) { |
| CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(RT->getDecl()); |
| if (!ClassDecl->hasTrivialDestructor()) { |
| // Note: We suppress the destructor call when the corresponding NRVO |
| // flag has been set. |
| |
| // Note that for __block variables, we want to destroy the |
| // original stack object, not the possible forwarded object. |
| llvm::Value *Loc = emission.getObjectAddress(*this); |
| |
| const CXXDestructorDecl *D = ClassDecl->getDestructor(); |
| assert(D && "EmitLocalBlockVarDecl - destructor is nul"); |
| |
| if (type != baseType) { |
| const ConstantArrayType *Array = |
| getContext().getAsConstantArrayType(type); |
| assert(Array && "types changed without array?"); |
| EHStack.pushCleanup<CallArrayDtor>(NormalAndEHCleanup, |
| D, Array, Loc); |
| } else { |
| EHStack.pushCleanup<CallVarDtor>(NormalAndEHCleanup, |
| D, emission.NRVOFlag, Loc); |
| } |
| } |
| } |
| } |
| |
| // Handle the cleanup attribute. |
| if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) { |
| const FunctionDecl *FD = CA->getFunctionDecl(); |
| |
| llvm::Constant *F = CGM.GetAddrOfFunction(FD); |
| assert(F && "Could not find function!"); |
| |
| const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD); |
| EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D); |
| } |
| |
| // If this is a block variable, call _Block_object_destroy |
| // (on the unforwarded address). |
| if (emission.IsByRef && |
| CGM.getLangOptions().getGCMode() != LangOptions::GCOnly) |
| EHStack.pushCleanup<CallBlockRelease>(NormalAndEHCleanup, emission.Address); |
| } |
| |
| /// Emit an alloca (or GlobalValue depending on target) |
| /// for the specified parameter and set up LocalDeclMap. |
| void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg, |
| unsigned ArgNo) { |
| // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl? |
| assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) && |
| "Invalid argument to EmitParmDecl"); |
| |
| Arg->setName(D.getName()); |
| |
| // Use better IR generation for certain implicit parameters. |
| if (isa<ImplicitParamDecl>(D)) { |
| // The only implicit argument a block has is its literal. |
| if (BlockInfo) { |
| LocalDeclMap[&D] = Arg; |
| |
| if (CGDebugInfo *DI = getDebugInfo()) { |
| DI->setLocation(D.getLocation()); |
| DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder); |
| } |
| |
| return; |
| } |
| } |
| |
| QualType Ty = D.getType(); |
| |
| llvm::Value *DeclPtr; |
| // If this is an aggregate or variable sized value, reuse the input pointer. |
| if (!Ty->isConstantSizeType() || |
| CodeGenFunction::hasAggregateLLVMType(Ty)) { |
| DeclPtr = Arg; |
| } else { |
| // Otherwise, create a temporary to hold the value. |
| DeclPtr = CreateMemTemp(Ty, D.getName() + ".addr"); |
| |
| // Store the initial value into the alloca. |
| EmitStoreOfScalar(Arg, DeclPtr, Ty.isVolatileQualified(), |
| getContext().getDeclAlign(&D).getQuantity(), Ty, |
| CGM.getTBAAInfo(Ty)); |
| } |
| |
| llvm::Value *&DMEntry = LocalDeclMap[&D]; |
| assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); |
| DMEntry = DeclPtr; |
| |
| // Emit debug info for param declaration. |
| if (CGDebugInfo *DI = getDebugInfo()) { |
| DI->setLocation(D.getLocation()); |
| DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder); |
| } |
| } |