1 //===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This contains code to emit Decl nodes as LLVM code.
12 //===----------------------------------------------------------------------===//
14 #include "CGDebugInfo.h"
15 #include "CodeGenFunction.h"
16 #include "CodeGenModule.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/Decl.h"
19 #include "clang/AST/DeclObjC.h"
20 #include "clang/Basic/SourceManager.h"
21 #include "clang/Basic/TargetInfo.h"
22 #include "llvm/GlobalVariable.h"
23 #include "llvm/Intrinsics.h"
24 #include "llvm/Target/TargetData.h"
25 #include "llvm/Type.h"
26 using namespace clang;
27 using namespace CodeGen;
30 void CodeGenFunction::EmitDecl(const Decl &D) {
31 switch (D.getKind()) {
32 default: assert(0 && "Unknown decl kind!");
34 assert(0 && "Parmdecls should not be in declstmts!");
35 case Decl::Function: // void X();
36 case Decl::Record: // struct/union/class X;
37 case Decl::Enum: // enum X;
38 case Decl::EnumConstant: // enum ? { X = ? }
39 case Decl::CXXRecord: // struct/union/class X; [C++]
40 // None of these decls require codegen support.
44 const VarDecl &VD = cast<VarDecl>(D);
45 assert(VD.isBlockVarDecl() &&
46 "Should not see file-scope variables inside a function!");
47 return EmitBlockVarDecl(VD);
50 case Decl::Typedef: { // typedef int X;
51 const TypedefDecl &TD = cast<TypedefDecl>(D);
52 QualType Ty = TD.getUnderlyingType();
54 if (Ty->isVariablyModifiedType())
60 /// EmitBlockVarDecl - This method handles emission of any variable declaration
61 /// inside a function, including static vars etc.
62 void CodeGenFunction::EmitBlockVarDecl(const VarDecl &D) {
63 if (D.hasAttr<AsmLabelAttr>(getContext()))
64 CGM.ErrorUnsupported(&D, "__asm__");
66 switch (D.getStorageClass()) {
69 case VarDecl::Register:
70 return EmitLocalBlockVarDecl(D);
72 return EmitStaticBlockVarDecl(D);
74 case VarDecl::PrivateExtern:
75 // Don't emit it now, allow it to be emitted lazily on its first use.
79 assert(0 && "Unknown storage class");
82 llvm::GlobalVariable *
83 CodeGenFunction::CreateStaticBlockVarDecl(const VarDecl &D,
84 const char *Separator,
85 llvm::GlobalValue::LinkageTypes
87 QualType Ty = D.getType();
88 assert(Ty->isConstantSizeType() && "VLAs can't be static");
91 if (getContext().getLangOptions().CPlusPlus) {
92 Name = CGM.getMangledName(&D);
94 std::string ContextName;
95 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CurFuncDecl))
96 ContextName = CGM.getMangledName(FD);
97 else if (isa<ObjCMethodDecl>(CurFuncDecl))
98 ContextName = std::string(CurFn->getNameStart(),
99 CurFn->getNameStart() + CurFn->getNameLen());
101 assert(0 && "Unknown context for block var decl");
103 Name = ContextName + Separator + D.getNameAsString();
106 const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
107 return new llvm::GlobalVariable(LTy, Ty.isConstant(getContext()), Linkage,
108 llvm::Constant::getNullValue(LTy), Name,
109 &CGM.getModule(), D.isThreadSpecified(),
110 Ty.getAddressSpace());
113 void CodeGenFunction::EmitStaticBlockVarDecl(const VarDecl &D) {
115 llvm::Value *&DMEntry = LocalDeclMap[&D];
116 assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
118 llvm::GlobalVariable *GV =
119 CreateStaticBlockVarDecl(D, ".", llvm::GlobalValue::InternalLinkage);
121 // Store into LocalDeclMap before generating initializer to handle
122 // circular references.
125 // Make sure to evaluate VLA bounds now so that we have them for later.
126 if (D.getType()->isVariablyModifiedType())
127 EmitVLASize(D.getType());
129 if (D.getType()->isReferenceType()) {
130 CGM.ErrorUnsupported(&D, "static declaration with reference type");
135 llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this);
137 // If constant emission failed, then this should be a C++ static
140 if (!getContext().getLangOptions().CPlusPlus)
141 CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
143 GenerateStaticCXXBlockVarDeclInit(D, GV);
145 // The initializer may differ in type from the global. Rewrite
146 // the global to match the initializer. (We have to do this
147 // because some types, like unions, can't be completely represented
148 // in the LLVM type system.)
149 if (GV->getType() != Init->getType()) {
150 llvm::GlobalVariable *OldGV = GV;
152 GV = new llvm::GlobalVariable(Init->getType(), OldGV->isConstant(),
153 OldGV->getLinkage(), Init, "",
154 &CGM.getModule(), D.isThreadSpecified(),
155 D.getType().getAddressSpace());
157 // Steal the name of the old global
160 // Replace all uses of the old global with the new global
161 llvm::Constant *NewPtrForOldDecl =
162 llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
163 OldGV->replaceAllUsesWith(NewPtrForOldDecl);
165 // Erase the old global, since it is no longer used.
166 OldGV->eraseFromParent();
169 GV->setInitializer(Init);
173 // FIXME: Merge attribute handling.
174 if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>(getContext())) {
175 SourceManager &SM = CGM.getContext().getSourceManager();
176 llvm::Constant *Ann =
177 CGM.EmitAnnotateAttr(GV, AA,
178 SM.getInstantiationLineNumber(D.getLocation()));
179 CGM.AddAnnotation(Ann);
182 if (const SectionAttr *SA = D.getAttr<SectionAttr>(getContext()))
183 GV->setSection(SA->getName());
185 if (D.hasAttr<UsedAttr>(getContext()))
186 CGM.AddUsedGlobal(GV);
188 // We may have to cast the constant because of the initializer
191 // FIXME: It is really dangerous to store this in the map; if anyone
192 // RAUW's the GV uses of this constant will be invalid.
193 const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
194 const llvm::Type *LPtrTy =
195 llvm::PointerType::get(LTy, D.getType().getAddressSpace());
196 DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
198 // Emit global variable debug descriptor for static vars.
199 CGDebugInfo *DI = getDebugInfo();
201 DI->setLocation(D.getLocation());
202 DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
206 /// BuildByRefType - This routine changes a __block variable declared as T x
211 /// void *__forwarding;
214 /// void *__copy_helper;
215 /// void *__destroy_helper;
219 /// Align is the alignment needed in bytes for x.
220 const llvm::Type *CodeGenFunction::BuildByRefType(QualType Ty,
222 const llvm::Type *LTy = ConvertType(Ty);
223 bool needsCopyDispose = BlockRequiresCopying(Ty);
224 std::vector<const llvm::Type *> Types(needsCopyDispose*2+5);
225 const llvm::PointerType *PtrToInt8Ty
226 = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
227 Types[0] = PtrToInt8Ty;
228 Types[1] = PtrToInt8Ty;
229 Types[2] = llvm::Type::Int32Ty;
230 Types[3] = llvm::Type::Int32Ty;
231 if (needsCopyDispose) {
232 Types[4] = PtrToInt8Ty;
233 Types[5] = PtrToInt8Ty;
235 // FIXME: Align this on at least an Align boundary, assert if we can't.
236 assert((Align <= unsigned(Target.getPointerAlign(0))/8)
237 && "Can't align more than pointer yet");
238 Types[needsCopyDispose*2 + 4] = LTy;
239 return llvm::StructType::get(Types, false);
242 /// EmitLocalBlockVarDecl - Emit code and set up an entry in LocalDeclMap for a
243 /// variable declaration with auto, register, or no storage class specifier.
244 /// These turn into simple stack objects, or GlobalValues depending on target.
245 void CodeGenFunction::EmitLocalBlockVarDecl(const VarDecl &D) {
246 QualType Ty = D.getType();
247 bool isByRef = D.hasAttr<BlocksAttr>(getContext());
248 bool needsDispose = false;
251 llvm::Value *DeclPtr;
252 if (Ty->isConstantSizeType()) {
253 if (!Target.useGlobalsForAutomaticVariables()) {
254 // A normal fixed sized variable becomes an alloca in the entry block.
255 const llvm::Type *LTy = ConvertTypeForMem(Ty);
256 Align = getContext().getDeclAlignInBytes(&D);
258 LTy = BuildByRefType(Ty, Align);
259 llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
260 Alloc->setName(D.getNameAsString().c_str());
263 Align = std::max(Align, unsigned(Target.getPointerAlign(0) / 8));
264 Alloc->setAlignment(Align);
267 // Targets that don't support recursion emit locals as globals.
269 D.getStorageClass() == VarDecl::Register ? ".reg." : ".auto.";
270 DeclPtr = CreateStaticBlockVarDecl(D, Class,
275 if (Ty->isVariablyModifiedType())
278 if (!DidCallStackSave) {
280 const llvm::Type *LTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
281 llvm::Value *Stack = CreateTempAlloca(LTy, "saved_stack");
283 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
284 llvm::Value *V = Builder.CreateCall(F);
286 Builder.CreateStore(V, Stack);
288 DidCallStackSave = true;
291 // Push a cleanup block and restore the stack there.
292 CleanupScope scope(*this);
294 V = Builder.CreateLoad(Stack, "tmp");
295 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
296 Builder.CreateCall(F, V);
300 // Get the element type.
301 const llvm::Type *LElemTy = ConvertTypeForMem(Ty);
302 const llvm::Type *LElemPtrTy =
303 llvm::PointerType::get(LElemTy, D.getType().getAddressSpace());
305 llvm::Value *VLASize = EmitVLASize(Ty);
307 // Downcast the VLA size expression
308 VLASize = Builder.CreateIntCast(VLASize, llvm::Type::Int32Ty, false, "tmp");
310 // Allocate memory for the array.
311 llvm::Value *VLA = Builder.CreateAlloca(llvm::Type::Int8Ty, VLASize, "vla");
312 DeclPtr = Builder.CreateBitCast(VLA, LElemPtrTy, "tmp");
315 llvm::Value *&DMEntry = LocalDeclMap[&D];
316 assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
319 // Emit debug info for local var declaration.
320 if (CGDebugInfo *DI = getDebugInfo()) {
321 DI->setLocation(D.getLocation());
322 if (Target.useGlobalsForAutomaticVariables()) {
323 DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
327 bool needsCopyDispose = BlockRequiresCopying(Ty);
328 Loc = Builder.CreateStructGEP(DeclPtr, 1, "forwarding");
329 Loc = Builder.CreateLoad(Loc, false);
330 Loc = Builder.CreateBitCast(Loc, DeclPtr->getType());
331 Loc = Builder.CreateStructGEP(Loc, needsCopyDispose*2+4, "x");
332 DI->EmitDeclareOfAutoVariable(&D, Loc, Builder);
334 DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
337 // If this local has an initializer, emit it now.
338 if (const Expr *Init = D.getInit()) {
339 llvm::Value *Loc = DeclPtr;
341 bool needsCopyDispose = BlockRequiresCopying(Ty);
342 Loc = Builder.CreateStructGEP(DeclPtr, needsCopyDispose*2+4, "x");
344 if (Ty->isReferenceType()) {
345 llvm::Value *V = EmitReferenceBindingToExpr(Init, Ty).getScalarVal();
346 EmitStoreOfScalar(V, Loc, false, Ty);
347 } else if (!hasAggregateLLVMType(Init->getType())) {
348 llvm::Value *V = EmitScalarExpr(Init);
349 EmitStoreOfScalar(V, Loc, D.getType().isVolatileQualified(),
351 } else if (Init->getType()->isAnyComplexType()) {
352 EmitComplexExprIntoAddr(Init, Loc, D.getType().isVolatileQualified());
354 EmitAggExpr(Init, Loc, D.getType().isVolatileQualified());
358 const llvm::PointerType *PtrToInt8Ty
359 = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
361 llvm::Value *isa_field = Builder.CreateStructGEP(DeclPtr, 0);
362 llvm::Value *forwarding_field = Builder.CreateStructGEP(DeclPtr, 1);
363 llvm::Value *flags_field = Builder.CreateStructGEP(DeclPtr, 2);
364 llvm::Value *size_field = Builder.CreateStructGEP(DeclPtr, 3);
371 if (Ty->isBlockPointerType()) {
372 flag |= BLOCK_FIELD_IS_BLOCK;
373 flags |= BLOCK_HAS_COPY_DISPOSE;
374 } else if (BlockRequiresCopying(Ty)) {
375 flag |= BLOCK_FIELD_IS_OBJECT;
376 flags |= BLOCK_HAS_COPY_DISPOSE;
379 // FIXME: Someone double check this.
380 if (Ty.isObjCGCWeak())
381 flag |= BLOCK_FIELD_IS_WEAK;
384 if (flag&BLOCK_FIELD_IS_WEAK)
386 V = llvm::ConstantInt::get(llvm::Type::Int32Ty, isa);
387 V = Builder.CreateIntToPtr(V, PtrToInt8Ty, "isa");
388 Builder.CreateStore(V, isa_field);
390 V = Builder.CreateBitCast(DeclPtr, PtrToInt8Ty, "forwarding");
391 Builder.CreateStore(V, forwarding_field);
393 V = llvm::ConstantInt::get(llvm::Type::Int32Ty, flags);
394 Builder.CreateStore(V, flags_field);
396 const llvm::Type *V1;
397 V1 = cast<llvm::PointerType>(DeclPtr->getType())->getElementType();
398 V = llvm::ConstantInt::get(llvm::Type::Int32Ty,
399 (CGM.getTargetData().getTypeStoreSizeInBits(V1)
401 Builder.CreateStore(V, size_field);
403 if (flags & BLOCK_HAS_COPY_DISPOSE) {
404 BlockHasCopyDispose = true;
405 llvm::Value *copy_helper = Builder.CreateStructGEP(DeclPtr, 4);
406 Builder.CreateStore(BuildbyrefCopyHelper(DeclPtr->getType(), flag, Align),
409 llvm::Value *destroy_helper = Builder.CreateStructGEP(DeclPtr, 5);
410 Builder.CreateStore(BuildbyrefDestroyHelper(DeclPtr->getType(), flag,
416 // Handle the cleanup attribute
417 if (const CleanupAttr *CA = D.getAttr<CleanupAttr>(getContext())) {
418 const FunctionDecl *FD = CA->getFunctionDecl();
420 llvm::Constant* F = CGM.GetAddrOfFunction(GlobalDecl(FD));
421 assert(F && "Could not find function!");
423 CleanupScope scope(*this);
425 const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
427 // In some cases, the type of the function argument will be different from
428 // the type of the pointer. An example of this is
429 // void f(void* arg);
430 // __attribute__((cleanup(f))) void *g;
432 // To fix this we insert a bitcast here.
433 QualType ArgTy = Info.arg_begin()->type;
434 DeclPtr = Builder.CreateBitCast(DeclPtr, ConvertType(ArgTy));
437 Args.push_back(std::make_pair(RValue::get(DeclPtr),
438 getContext().getPointerType(D.getType())));
440 EmitCall(Info, F, Args);
443 if (needsDispose && CGM.getLangOptions().getGCMode() != LangOptions::GCOnly) {
444 CleanupScope scope(*this);
445 llvm::Value *V = Builder.CreateStructGEP(DeclPtr, 1, "forwarding");
446 V = Builder.CreateLoad(V, false);
447 BuildBlockRelease(V);
451 /// Emit an alloca (or GlobalValue depending on target)
452 /// for the specified parameter and set up LocalDeclMap.
453 void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg) {
454 // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
455 assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
456 "Invalid argument to EmitParmDecl");
457 QualType Ty = D.getType();
459 llvm::Value *DeclPtr;
460 if (!Ty->isConstantSizeType()) {
461 // Variable sized values always are passed by-reference.
464 // A fixed sized single-value variable becomes an alloca in the entry block.
465 const llvm::Type *LTy = ConvertTypeForMem(Ty);
466 if (LTy->isSingleValueType()) {
468 std::string Name = D.getNameAsString();
470 DeclPtr = CreateTempAlloca(LTy);
471 DeclPtr->setName(Name.c_str());
473 // Store the initial value into the alloca.
474 EmitStoreOfScalar(Arg, DeclPtr, Ty.isVolatileQualified(), Ty);
476 // Otherwise, if this is an aggregate, just use the input pointer.
479 Arg->setName(D.getNameAsString());
482 llvm::Value *&DMEntry = LocalDeclMap[&D];
483 assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
486 // Emit debug info for param declaration.
487 if (CGDebugInfo *DI = getDebugInfo()) {
488 DI->setLocation(D.getLocation());
489 DI->EmitDeclareOfArgVariable(&D, DeclPtr, Builder);