CGDecl.cpp revision bd0fec9250a783ad67d023e53ab0877a74f0be11
1//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This contains code to emit Decl nodes as LLVM code. 11// 12//===----------------------------------------------------------------------===// 13 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" 26using namespace clang; 27using namespace CodeGen; 28 29 30void CodeGenFunction::EmitDecl(const Decl &D) { 31 switch (D.getKind()) { 32 default: assert(0 && "Unknown decl kind!"); 33 case Decl::ParmVar: 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. 41 return; 42 43 case Decl::Var: { 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); 48 } 49 50 case Decl::Typedef: { // typedef int X; 51 const TypedefDecl &TD = cast<TypedefDecl>(D); 52 QualType Ty = TD.getUnderlyingType(); 53 54 if (Ty->isVariablyModifiedType()) 55 EmitVLASize(Ty); 56 } 57 } 58} 59 60/// EmitBlockVarDecl - This method handles emission of any variable declaration 61/// inside a function, including static vars etc. 62void CodeGenFunction::EmitBlockVarDecl(const VarDecl &D) { 63 if (D.hasAttr<AsmLabelAttr>(getContext())) 64 CGM.ErrorUnsupported(&D, "__asm__"); 65 66 switch (D.getStorageClass()) { 67 case VarDecl::None: 68 case VarDecl::Auto: 69 case VarDecl::Register: 70 return EmitLocalBlockVarDecl(D); 71 case VarDecl::Static: 72 return EmitStaticBlockVarDecl(D); 73 case VarDecl::Extern: 74 case VarDecl::PrivateExtern: 75 // Don't emit it now, allow it to be emitted lazily on its first use. 76 return; 77 } 78 79 assert(0 && "Unknown storage class"); 80} 81 82llvm::GlobalVariable * 83CodeGenFunction::CreateStaticBlockVarDecl(const VarDecl &D, 84 const char *Separator, 85 llvm::GlobalValue::LinkageTypes 86 Linkage) { 87 QualType Ty = D.getType(); 88 assert(Ty->isConstantSizeType() && "VLAs can't be static"); 89 90 std::string Name; 91 if (getContext().getLangOptions().CPlusPlus) { 92 Name = CGM.getMangledName(&D); 93 } else { 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()); 100 else 101 assert(0 && "Unknown context for block var decl"); 102 103 Name = ContextName + Separator + D.getNameAsString(); 104 } 105 106 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()); 111} 112 113void CodeGenFunction::EmitStaticBlockVarDecl(const VarDecl &D) { 114 115 llvm::Value *&DMEntry = LocalDeclMap[&D]; 116 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 117 118 llvm::GlobalVariable *GV = 119 CreateStaticBlockVarDecl(D, ".", llvm::GlobalValue::InternalLinkage); 120 121 // Store into LocalDeclMap before generating initializer to handle 122 // circular references. 123 DMEntry = GV; 124 125 // Make sure to evaluate VLA bounds now so that we have them for later. 126 if (D.getType()->isVariablyModifiedType()) 127 EmitVLASize(D.getType()); 128 129 if (D.getType()->isReferenceType()) { 130 CGM.ErrorUnsupported(&D, "static declaration with reference type"); 131 return; 132 } 133 134 if (D.getInit()) { 135 llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this); 136 137 // If constant emission failed, then this should be a C++ static 138 // initializer. 139 if (!Init) { 140 if (!getContext().getLangOptions().CPlusPlus) 141 CGM.ErrorUnsupported(D.getInit(), "constant l-value expression"); 142 else 143 GenerateStaticCXXBlockVarDeclInit(D, GV); 144 } else { 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; 151 152 GV = new llvm::GlobalVariable(Init->getType(), OldGV->isConstant(), 153 OldGV->getLinkage(), Init, "", 154 &CGM.getModule(), D.isThreadSpecified(), 155 D.getType().getAddressSpace()); 156 157 // Steal the name of the old global 158 GV->takeName(OldGV); 159 160 // 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); 164 165 // Erase the old global, since it is no longer used. 166 OldGV->eraseFromParent(); 167 } 168 169 GV->setInitializer(Init); 170 } 171 } 172 173 // 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); 180 } 181 182 if (const SectionAttr *SA = D.getAttr<SectionAttr>(getContext())) 183 GV->setSection(SA->getName()); 184 185 if (D.hasAttr<UsedAttr>(getContext())) 186 CGM.AddUsedGlobal(GV); 187 188 // We may have to cast the constant because of the initializer 189 // mismatch above. 190 // 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); 197 198 // Emit global variable debug descriptor for static vars. 199 CGDebugInfo *DI = getDebugInfo(); 200 if (DI) { 201 DI->setLocation(D.getLocation()); 202 DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D); 203 } 204} 205 206/// BuildByRefType - This routine changes a __block variable declared as T x 207/// into: 208/// 209/// struct { 210/// void *__isa; 211/// void *__forwarding; 212/// int32_t __flags; 213/// int32_t __size; 214/// void *__copy_helper; 215/// void *__destroy_helper; 216/// T x; 217/// } x 218/// 219/// Align is the alignment needed in bytes for x. 220const llvm::Type *CodeGenFunction::BuildByRefType(QualType Ty, 221 uint64_t Align) { 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; 234 } 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); 240} 241 242/// 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. 245void CodeGenFunction::EmitLocalBlockVarDecl(const VarDecl &D) { 246 QualType Ty = D.getType(); 247 bool isByRef = D.hasAttr<BlocksAttr>(getContext()); 248 bool needsDispose = false; 249 unsigned Align = 0; 250 251 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); 257 if (isByRef) 258 LTy = BuildByRefType(Ty, Align); 259 llvm::AllocaInst *Alloc = CreateTempAlloca(LTy); 260 Alloc->setName(D.getNameAsString().c_str()); 261 262 if (isByRef) 263 Align = std::max(Align, unsigned(Target.getPointerAlign(0) / 8)); 264 Alloc->setAlignment(Align); 265 DeclPtr = Alloc; 266 } else { 267 // Targets that don't support recursion emit locals as globals. 268 const char *Class = 269 D.getStorageClass() == VarDecl::Register ? ".reg." : ".auto."; 270 DeclPtr = CreateStaticBlockVarDecl(D, Class, 271 llvm::GlobalValue 272 ::InternalLinkage); 273 } 274 275 if (Ty->isVariablyModifiedType()) 276 EmitVLASize(Ty); 277 } else { 278 if (!DidCallStackSave) { 279 // Save the stack. 280 const llvm::Type *LTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 281 llvm::Value *Stack = CreateTempAlloca(LTy, "saved_stack"); 282 283 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave); 284 llvm::Value *V = Builder.CreateCall(F); 285 286 Builder.CreateStore(V, Stack); 287 288 DidCallStackSave = true; 289 290 { 291 // Push a cleanup block and restore the stack there. 292 CleanupScope scope(*this); 293 294 V = Builder.CreateLoad(Stack, "tmp"); 295 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stackrestore); 296 Builder.CreateCall(F, V); 297 } 298 } 299 300 // Get the element type. 301 const llvm::Type *LElemTy = ConvertTypeForMem(Ty); 302 const llvm::Type *LElemPtrTy = 303 llvm::PointerType::get(LElemTy, D.getType().getAddressSpace()); 304 305 llvm::Value *VLASize = EmitVLASize(Ty); 306 307 // Downcast the VLA size expression 308 VLASize = Builder.CreateIntCast(VLASize, llvm::Type::Int32Ty, false, "tmp"); 309 310 // Allocate memory for the array. 311 llvm::Value *VLA = Builder.CreateAlloca(llvm::Type::Int8Ty, VLASize, "vla"); 312 DeclPtr = Builder.CreateBitCast(VLA, LElemPtrTy, "tmp"); 313 } 314 315 llvm::Value *&DMEntry = LocalDeclMap[&D]; 316 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 317 DMEntry = DeclPtr; 318 319 // 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); 324 } 325 else if (isByRef) { 326 llvm::Value *Loc; 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); 333 } else 334 DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder); 335 } 336 337 // If this local has an initializer, emit it now. 338 if (const Expr *Init = D.getInit()) { 339 llvm::Value *Loc = DeclPtr; 340 if (isByRef) { 341 bool needsCopyDispose = BlockRequiresCopying(Ty); 342 Loc = Builder.CreateStructGEP(DeclPtr, needsCopyDispose*2+4, "x"); 343 } 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(), 350 D.getType()); 351 } else if (Init->getType()->isAnyComplexType()) { 352 EmitComplexExprIntoAddr(Init, Loc, D.getType().isVolatileQualified()); 353 } else { 354 EmitAggExpr(Init, Loc, D.getType().isVolatileQualified()); 355 } 356 } 357 if (isByRef) { 358 const llvm::PointerType *PtrToInt8Ty 359 = llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 360 361 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); 365 llvm::Value *V; 366 int flag = 0; 367 int flags = 0; 368 369 needsDispose = true; 370 371 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; 377 } 378 379 // FIXME: Someone double check this. 380 if (Ty.isObjCGCWeak()) 381 flag |= BLOCK_FIELD_IS_WEAK; 382 383 int isa = 0; 384 if (flag&BLOCK_FIELD_IS_WEAK) 385 isa = 1; 386 V = llvm::ConstantInt::get(llvm::Type::Int32Ty, isa); 387 V = Builder.CreateIntToPtr(V, PtrToInt8Ty, "isa"); 388 Builder.CreateStore(V, isa_field); 389 390 V = Builder.CreateBitCast(DeclPtr, PtrToInt8Ty, "forwarding"); 391 Builder.CreateStore(V, forwarding_field); 392 393 V = llvm::ConstantInt::get(llvm::Type::Int32Ty, flags); 394 Builder.CreateStore(V, flags_field); 395 396 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) 400 / 8)); 401 Builder.CreateStore(V, size_field); 402 403 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), 407 copy_helper); 408 409 llvm::Value *destroy_helper = Builder.CreateStructGEP(DeclPtr, 5); 410 Builder.CreateStore(BuildbyrefDestroyHelper(DeclPtr->getType(), flag, 411 Align), 412 destroy_helper); 413 } 414 } 415 416 // Handle the cleanup attribute 417 if (const CleanupAttr *CA = D.getAttr<CleanupAttr>(getContext())) { 418 const FunctionDecl *FD = CA->getFunctionDecl(); 419 420 llvm::Constant* F = CGM.GetAddrOfFunction(GlobalDecl(FD)); 421 assert(F && "Could not find function!"); 422 423 CleanupScope scope(*this); 424 425 const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD); 426 427 // 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; 431 // 432 // To fix this we insert a bitcast here. 433 QualType ArgTy = Info.arg_begin()->type; 434 DeclPtr = Builder.CreateBitCast(DeclPtr, ConvertType(ArgTy)); 435 436 CallArgList Args; 437 Args.push_back(std::make_pair(RValue::get(DeclPtr), 438 getContext().getPointerType(D.getType()))); 439 440 EmitCall(Info, F, Args); 441 } 442 443 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); 448 } 449} 450 451/// Emit an alloca (or GlobalValue depending on target) 452/// for the specified parameter and set up LocalDeclMap. 453void 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(); 458 459 llvm::Value *DeclPtr; 460 if (!Ty->isConstantSizeType()) { 461 // Variable sized values always are passed by-reference. 462 DeclPtr = Arg; 463 } else { 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()) { 467 // TODO: Alignment 468 std::string Name = D.getNameAsString(); 469 Name += ".addr"; 470 DeclPtr = CreateTempAlloca(LTy); 471 DeclPtr->setName(Name.c_str()); 472 473 // Store the initial value into the alloca. 474 EmitStoreOfScalar(Arg, DeclPtr, Ty.isVolatileQualified(), Ty); 475 } else { 476 // Otherwise, if this is an aggregate, just use the input pointer. 477 DeclPtr = Arg; 478 } 479 Arg->setName(D.getNameAsString()); 480 } 481 482 llvm::Value *&DMEntry = LocalDeclMap[&D]; 483 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 484 DMEntry = DeclPtr; 485 486 // Emit debug info for param declaration. 487 if (CGDebugInfo *DI = getDebugInfo()) { 488 DI->setLocation(D.getLocation()); 489 DI->EmitDeclareOfArgVariable(&D, DeclPtr, Builder); 490 } 491} 492 493