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c1b58d40e6
Specify external linkage for such globals so that llvm optimizer do not assume there values initialized as zero. llvm-svn: 63636
275 lines
9.7 KiB
C++
275 lines
9.7 KiB
C++
//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
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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 Decl nodes as LLVM code.
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//
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//===----------------------------------------------------------------------===//
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#include "CGDebugInfo.h"
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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/Decl.h"
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#include "clang/AST/DeclObjC.h"
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#include "clang/Basic/SourceManager.h"
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#include "clang/Basic/TargetInfo.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Intrinsics.h"
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#include "llvm/Type.h"
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using namespace clang;
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using namespace CodeGen;
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void CodeGenFunction::EmitDecl(const Decl &D) {
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switch (D.getKind()) {
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default: assert(0 && "Unknown decl kind!");
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case Decl::ParmVar:
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assert(0 && "Parmdecls should not be in declstmts!");
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case Decl::Function: // void X();
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case Decl::Record: // struct/union/class X;
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case Decl::Enum: // enum X;
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case Decl::EnumConstant: // enum ? { X = ? }
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case Decl::CXXRecord: // struct/union/class X; [C++]
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// None of these decls require codegen support.
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return;
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case Decl::Var: {
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const VarDecl &VD = cast<VarDecl>(D);
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assert(VD.isBlockVarDecl() &&
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"Should not see file-scope variables inside a function!");
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return EmitBlockVarDecl(VD);
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}
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case Decl::Typedef: { // typedef int X;
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const TypedefDecl &TD = cast<TypedefDecl>(D);
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QualType Ty = TD.getUnderlyingType();
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if (Ty->isVariablyModifiedType())
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EmitVLASize(Ty);
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}
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}
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}
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/// EmitBlockVarDecl - This method handles emission of any variable declaration
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/// inside a function, including static vars etc.
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void CodeGenFunction::EmitBlockVarDecl(const VarDecl &D) {
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switch (D.getStorageClass()) {
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case VarDecl::Static:
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return EmitStaticBlockVarDecl(D);
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case VarDecl::Extern:
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// Don't emit it now, allow it to be emitted lazily on its first use.
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return;
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default:
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assert((D.getStorageClass() == VarDecl::None ||
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D.getStorageClass() == VarDecl::Auto ||
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D.getStorageClass() == VarDecl::Register) &&
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"Unknown storage class");
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return EmitLocalBlockVarDecl(D);
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}
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}
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llvm::GlobalValue *
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CodeGenFunction::GenerateStaticBlockVarDecl(const VarDecl &D,
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bool NoInit,
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const char *Separator,
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llvm::GlobalValue
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::LinkageTypes Linkage) {
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QualType Ty = D.getType();
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assert(Ty->isConstantSizeType() && "VLAs can't be static");
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const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
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llvm::Constant *Init = 0;
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if ((D.getInit() == 0) || NoInit) {
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Init = llvm::Constant::getNullValue(LTy);
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} else {
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if (D.getInit()->isConstantInitializer(getContext()))
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Init = CGM.EmitConstantExpr(D.getInit(), this);
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else {
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assert(getContext().getLangOptions().CPlusPlus &&
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"only C++ supports non-constant static initializers!");
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return GenerateStaticCXXBlockVarDecl(D);
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}
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}
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assert(Init && "Unable to create initialiser for static decl");
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std::string ContextName;
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if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CurFuncDecl))
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ContextName = FD->getNameAsString();
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else if (isa<ObjCMethodDecl>(CurFuncDecl))
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ContextName = std::string(CurFn->getNameStart(),
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CurFn->getNameStart() + CurFn->getNameLen());
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else
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assert(0 && "Unknown context for block var decl");
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llvm::GlobalValue *GV =
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new llvm::GlobalVariable(Init->getType(), false,
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Linkage,
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Init, ContextName + Separator +D.getNameAsString(),
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&CGM.getModule(), 0, Ty.getAddressSpace());
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return GV;
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}
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void CodeGenFunction::EmitStaticBlockVarDecl(const VarDecl &D) {
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llvm::Value *&DMEntry = LocalDeclMap[&D];
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assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
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llvm::GlobalValue *GV;
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GV = GenerateStaticBlockVarDecl(D, false, ".",
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llvm::GlobalValue::InternalLinkage);
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if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) {
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SourceManager &SM = CGM.getContext().getSourceManager();
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llvm::Constant *Ann =
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CGM.EmitAnnotateAttr(GV, AA,
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SM.getInstantiationLineNumber(D.getLocation()));
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CGM.AddAnnotation(Ann);
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}
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const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
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const llvm::Type *LPtrTy =
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llvm::PointerType::get(LTy, D.getType().getAddressSpace());
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DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
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// Emit global variable debug descriptor for static vars.
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CGDebugInfo *DI = CGM.getDebugInfo();
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if(DI) {
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DI->setLocation(D.getLocation());
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DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
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}
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}
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/// EmitLocalBlockVarDecl - Emit code and set up an entry in LocalDeclMap for a
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/// variable declaration with auto, register, or no storage class specifier.
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/// These turn into simple stack objects, or GlobalValues depending on target.
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void CodeGenFunction::EmitLocalBlockVarDecl(const VarDecl &D) {
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QualType Ty = D.getType();
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llvm::Value *DeclPtr;
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if (Ty->isConstantSizeType()) {
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if (!Target.useGlobalsForAutomaticVariables()) {
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// A normal fixed sized variable becomes an alloca in the entry block.
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const llvm::Type *LTy = ConvertType(Ty);
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llvm::AllocaInst *Alloc =
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CreateTempAlloca(LTy, D.getIdentifier()->getName());
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unsigned align = getContext().getTypeAlign(Ty);
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if (const AlignedAttr* AA = D.getAttr<AlignedAttr>())
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align = std::max(align, AA->getAlignment());
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Alloc->setAlignment(align >> 3);
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DeclPtr = Alloc;
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} else {
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// Targets that don't support recursion emit locals as globals.
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const char *Class =
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D.getStorageClass() == VarDecl::Register ? ".reg." : ".auto.";
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DeclPtr = GenerateStaticBlockVarDecl(D, true, Class,
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llvm::GlobalValue
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::InternalLinkage);
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}
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if (Ty->isVariablyModifiedType())
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EmitVLASize(Ty);
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} else {
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if (!StackSaveValues.back()) {
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// Save the stack.
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const llvm::Type *LTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
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llvm::Value *Stack = CreateTempAlloca(LTy, "saved_stack");
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llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
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llvm::Value *V = Builder.CreateCall(F);
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Builder.CreateStore(V, Stack);
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StackSaveValues.back() = Stack;
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}
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// Get the element type.
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const llvm::Type *LElemTy = ConvertType(Ty);
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const llvm::Type *LElemPtrTy =
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llvm::PointerType::get(LElemTy, D.getType().getAddressSpace());
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llvm::Value *VLASize = EmitVLASize(Ty);
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// Allocate memory for the array.
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llvm::Value *VLA = Builder.CreateAlloca(llvm::Type::Int8Ty, VLASize, "vla");
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DeclPtr = Builder.CreateBitCast(VLA, LElemPtrTy, "tmp");
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}
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llvm::Value *&DMEntry = LocalDeclMap[&D];
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assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
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DMEntry = DeclPtr;
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// Emit debug info for local var declaration.
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if (CGDebugInfo *DI = CGM.getDebugInfo()) {
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DI->setLocation(D.getLocation());
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DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
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}
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// If this local has an initializer, emit it now.
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if (const Expr *Init = D.getInit()) {
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if (!hasAggregateLLVMType(Init->getType())) {
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llvm::Value *V = EmitScalarExpr(Init);
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Builder.CreateStore(V, DeclPtr, D.getType().isVolatileQualified());
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} else if (Init->getType()->isAnyComplexType()) {
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EmitComplexExprIntoAddr(Init, DeclPtr, D.getType().isVolatileQualified());
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} else {
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EmitAggExpr(Init, DeclPtr, D.getType().isVolatileQualified());
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}
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}
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}
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/// Emit an alloca (or GlobalValue depending on target)
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/// for the specified parameter and set up LocalDeclMap.
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void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg) {
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// FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
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assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
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"Invalid argument to EmitParmDecl");
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QualType Ty = D.getType();
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llvm::Value *DeclPtr;
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if (!Ty->isConstantSizeType()) {
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// Variable sized values always are passed by-reference.
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DeclPtr = Arg;
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} else if (Target.useGlobalsForAutomaticVariables()) {
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// Targets that don't have stack use global address space for parameters.
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// Specify external linkage for such globals so that llvm optimizer do
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// not assume there values initialized as zero.
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DeclPtr = GenerateStaticBlockVarDecl(D, true, ".arg.",
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llvm::GlobalValue::ExternalLinkage);
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} else {
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// A fixed sized single-value variable becomes an alloca in the entry block.
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const llvm::Type *LTy = ConvertType(Ty);
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if (LTy->isSingleValueType()) {
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// TODO: Alignment
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std::string Name = D.getNameAsString();
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Name += ".addr";
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DeclPtr = CreateTempAlloca(LTy, Name.c_str());
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// Store the initial value into the alloca.
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Builder.CreateStore(Arg, DeclPtr,Ty.isVolatileQualified());
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} else {
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// Otherwise, if this is an aggregate, just use the input pointer.
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DeclPtr = Arg;
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}
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Arg->setName(D.getNameAsString());
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}
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llvm::Value *&DMEntry = LocalDeclMap[&D];
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assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
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DMEntry = DeclPtr;
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// Emit debug info for param declaration.
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if (CGDebugInfo *DI = CGM.getDebugInfo()) {
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DI->setLocation(D.getLocation());
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DI->EmitDeclareOfArgVariable(&D, DeclPtr, Builder);
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}
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}
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