CGDecl.cpp revision 208600 
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/CharUnits.h"
19#include "clang/AST/Decl.h"
20#include "clang/AST/DeclObjC.h"
21#include "clang/Basic/SourceManager.h"
22#include "clang/Basic/TargetInfo.h"
23#include "clang/CodeGen/CodeGenOptions.h"
24#include "llvm/GlobalVariable.h"
25#include "llvm/Intrinsics.h"
26#include "llvm/Target/TargetData.h"
27#include "llvm/Type.h"
28using namespace clang;
29using namespace CodeGen;
30
31
32void CodeGenFunction::EmitDecl(const Decl &D) {
33  switch (D.getKind()) {
34  case Decl::TranslationUnit:
35  case Decl::Namespace:
36  case Decl::UnresolvedUsingTypename:
37  case Decl::ClassTemplateSpecialization:
38  case Decl::ClassTemplatePartialSpecialization:
39  case Decl::TemplateTypeParm:
40  case Decl::UnresolvedUsingValue:
41    case Decl::NonTypeTemplateParm:
42  case Decl::CXXMethod:
43  case Decl::CXXConstructor:
44  case Decl::CXXDestructor:
45  case Decl::CXXConversion:
46  case Decl::Field:
47  case Decl::ObjCIvar:
48  case Decl::ObjCAtDefsField:
49  case Decl::ParmVar:
50  case Decl::ImplicitParam:
51  case Decl::ClassTemplate:
52  case Decl::FunctionTemplate:
53  case Decl::TemplateTemplateParm:
54  case Decl::ObjCMethod:
55  case Decl::ObjCCategory:
56  case Decl::ObjCProtocol:
57  case Decl::ObjCInterface:
58  case Decl::ObjCCategoryImpl:
59  case Decl::ObjCImplementation:
60  case Decl::ObjCProperty:
61  case Decl::ObjCCompatibleAlias:
62  case Decl::LinkageSpec:
63  case Decl::ObjCPropertyImpl:
64  case Decl::ObjCClass:
65  case Decl::ObjCForwardProtocol:
66  case Decl::FileScopeAsm:
67  case Decl::Friend:
68  case Decl::FriendTemplate:
69  case Decl::Block:
70
71    assert(0 && "Declaration not should not be in declstmts!");
72  case Decl::Function:  // void X();
73  case Decl::Record:    // struct/union/class X;
74  case Decl::Enum:      // enum X;
75  case Decl::EnumConstant: // enum ? { X = ? }
76  case Decl::CXXRecord: // struct/union/class X; [C++]
77  case Decl::Using:          // using X; [C++]
78  case Decl::UsingShadow:
79  case Decl::UsingDirective: // using namespace X; [C++]
80  case Decl::NamespaceAlias:
81  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
82    // None of these decls require codegen support.
83    return;
84
85  case Decl::Var: {
86    const VarDecl &VD = cast<VarDecl>(D);
87    assert(VD.isBlockVarDecl() &&
88           "Should not see file-scope variables inside a function!");
89    return EmitBlockVarDecl(VD);
90  }
91
92  case Decl::Typedef: {   // typedef int X;
93    const TypedefDecl &TD = cast<TypedefDecl>(D);
94    QualType Ty = TD.getUnderlyingType();
95
96    if (Ty->isVariablyModifiedType())
97      EmitVLASize(Ty);
98  }
99  }
100}
101
102/// EmitBlockVarDecl - This method handles emission of any variable declaration
103/// inside a function, including static vars etc.
104void CodeGenFunction::EmitBlockVarDecl(const VarDecl &D) {
105  if (D.hasAttr<AsmLabelAttr>())
106    CGM.ErrorUnsupported(&D, "__asm__");
107
108  switch (D.getStorageClass()) {
109  case VarDecl::None:
110  case VarDecl::Auto:
111  case VarDecl::Register:
112    return EmitLocalBlockVarDecl(D);
113  case VarDecl::Static: {
114    llvm::GlobalValue::LinkageTypes Linkage =
115      llvm::GlobalValue::InternalLinkage;
116
117    // If the function definition has some sort of weak linkage, its
118    // static variables should also be weak so that they get properly
119    // uniqued.  We can't do this in C, though, because there's no
120    // standard way to agree on which variables are the same (i.e.
121    // there's no mangling).
122    if (getContext().getLangOptions().CPlusPlus)
123      if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
124        Linkage = CurFn->getLinkage();
125
126    return EmitStaticBlockVarDecl(D, Linkage);
127  }
128  case VarDecl::Extern:
129  case VarDecl::PrivateExtern:
130    // Don't emit it now, allow it to be emitted lazily on its first use.
131    return;
132  }
133
134  assert(0 && "Unknown storage class");
135}
136
137static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
138                                     const char *Separator) {
139  CodeGenModule &CGM = CGF.CGM;
140  if (CGF.getContext().getLangOptions().CPlusPlus) {
141    MangleBuffer Name;
142    CGM.getMangledName(Name, &D);
143    return Name.getString().str();
144  }
145
146  std::string ContextName;
147  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
148    MangleBuffer Name;
149    CGM.getMangledName(Name, FD);
150    ContextName = Name.getString().str();
151  } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
152    ContextName = CGF.CurFn->getName();
153  else
154    // FIXME: What about in a block??
155    assert(0 && "Unknown context for block var decl");
156
157  return ContextName + Separator + D.getNameAsString();
158}
159
160llvm::GlobalVariable *
161CodeGenFunction::CreateStaticBlockVarDecl(const VarDecl &D,
162                                          const char *Separator,
163                                      llvm::GlobalValue::LinkageTypes Linkage) {
164  QualType Ty = D.getType();
165  assert(Ty->isConstantSizeType() && "VLAs can't be static");
166
167  std::string Name = GetStaticDeclName(*this, D, Separator);
168
169  const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
170  llvm::GlobalVariable *GV =
171    new llvm::GlobalVariable(CGM.getModule(), LTy,
172                             Ty.isConstant(getContext()), Linkage,
173                             CGM.EmitNullConstant(D.getType()), Name, 0,
174                             D.isThreadSpecified(), Ty.getAddressSpace());
175  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
176  return GV;
177}
178
179/// AddInitializerToGlobalBlockVarDecl - Add the initializer for 'D' to the
180/// global variable that has already been created for it.  If the initializer
181/// has a different type than GV does, this may free GV and return a different
182/// one.  Otherwise it just returns GV.
183llvm::GlobalVariable *
184CodeGenFunction::AddInitializerToGlobalBlockVarDecl(const VarDecl &D,
185                                                    llvm::GlobalVariable *GV) {
186  llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this);
187
188  // If constant emission failed, then this should be a C++ static
189  // initializer.
190  if (!Init) {
191    if (!getContext().getLangOptions().CPlusPlus)
192      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
193    else {
194      // Since we have a static initializer, this global variable can't
195      // be constant.
196      GV->setConstant(false);
197
198      EmitStaticCXXBlockVarDeclInit(D, GV);
199    }
200    return GV;
201  }
202
203  // The initializer may differ in type from the global. Rewrite
204  // the global to match the initializer.  (We have to do this
205  // because some types, like unions, can't be completely represented
206  // in the LLVM type system.)
207  if (GV->getType() != Init->getType()) {
208    llvm::GlobalVariable *OldGV = GV;
209
210    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
211                                  OldGV->isConstant(),
212                                  OldGV->getLinkage(), Init, "",
213                                  0, D.isThreadSpecified(),
214                                  D.getType().getAddressSpace());
215
216    // Steal the name of the old global
217    GV->takeName(OldGV);
218
219    // Replace all uses of the old global with the new global
220    llvm::Constant *NewPtrForOldDecl =
221    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
222    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
223
224    // Erase the old global, since it is no longer used.
225    OldGV->eraseFromParent();
226  }
227
228  GV->setInitializer(Init);
229  return GV;
230}
231
232void CodeGenFunction::EmitStaticBlockVarDecl(const VarDecl &D,
233                                      llvm::GlobalValue::LinkageTypes Linkage) {
234  llvm::Value *&DMEntry = LocalDeclMap[&D];
235  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
236
237  llvm::GlobalVariable *GV = CreateStaticBlockVarDecl(D, ".", Linkage);
238
239  // Store into LocalDeclMap before generating initializer to handle
240  // circular references.
241  DMEntry = GV;
242
243  // We can't have a VLA here, but we can have a pointer to a VLA,
244  // even though that doesn't really make any sense.
245  // Make sure to evaluate VLA bounds now so that we have them for later.
246  if (D.getType()->isVariablyModifiedType())
247    EmitVLASize(D.getType());
248
249  // If this value has an initializer, emit it.
250  if (D.getInit())
251    GV = AddInitializerToGlobalBlockVarDecl(D, GV);
252
253  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
254
255  // FIXME: Merge attribute handling.
256  if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) {
257    SourceManager &SM = CGM.getContext().getSourceManager();
258    llvm::Constant *Ann =
259      CGM.EmitAnnotateAttr(GV, AA,
260                           SM.getInstantiationLineNumber(D.getLocation()));
261    CGM.AddAnnotation(Ann);
262  }
263
264  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
265    GV->setSection(SA->getName());
266
267  if (D.hasAttr<UsedAttr>())
268    CGM.AddUsedGlobal(GV);
269
270  if (getContext().getLangOptions().CPlusPlus)
271    CGM.setStaticLocalDeclAddress(&D, GV);
272
273  // We may have to cast the constant because of the initializer
274  // mismatch above.
275  //
276  // FIXME: It is really dangerous to store this in the map; if anyone
277  // RAUW's the GV uses of this constant will be invalid.
278  const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
279  const llvm::Type *LPtrTy =
280    llvm::PointerType::get(LTy, D.getType().getAddressSpace());
281  DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
282
283  // Emit global variable debug descriptor for static vars.
284  CGDebugInfo *DI = getDebugInfo();
285  if (DI) {
286    DI->setLocation(D.getLocation());
287    DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
288  }
289}
290
291unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const {
292  assert(ByRefValueInfo.count(VD) && "Did not find value!");
293
294  return ByRefValueInfo.find(VD)->second.second;
295}
296
297/// BuildByRefType - This routine changes a __block variable declared as T x
298///   into:
299///
300///      struct {
301///        void *__isa;
302///        void *__forwarding;
303///        int32_t __flags;
304///        int32_t __size;
305///        void *__copy_helper;       // only if needed
306///        void *__destroy_helper;    // only if needed
307///        char padding[X];           // only if needed
308///        T x;
309///      } x
310///
311const llvm::Type *CodeGenFunction::BuildByRefType(const ValueDecl *D) {
312  std::pair<const llvm::Type *, unsigned> &Info = ByRefValueInfo[D];
313  if (Info.first)
314    return Info.first;
315
316  QualType Ty = D->getType();
317
318  std::vector<const llvm::Type *> Types;
319
320  const llvm::PointerType *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
321
322  llvm::PATypeHolder ByRefTypeHolder = llvm::OpaqueType::get(VMContext);
323
324  // void *__isa;
325  Types.push_back(Int8PtrTy);
326
327  // void *__forwarding;
328  Types.push_back(llvm::PointerType::getUnqual(ByRefTypeHolder));
329
330  // int32_t __flags;
331  Types.push_back(llvm::Type::getInt32Ty(VMContext));
332
333  // int32_t __size;
334  Types.push_back(llvm::Type::getInt32Ty(VMContext));
335
336  bool HasCopyAndDispose = BlockRequiresCopying(Ty);
337  if (HasCopyAndDispose) {
338    /// void *__copy_helper;
339    Types.push_back(Int8PtrTy);
340
341    /// void *__destroy_helper;
342    Types.push_back(Int8PtrTy);
343  }
344
345  bool Packed = false;
346  CharUnits Align = getContext().getDeclAlign(D);
347  if (Align > CharUnits::fromQuantity(Target.getPointerAlign(0) / 8)) {
348    // We have to insert padding.
349
350    // The struct above has 2 32-bit integers.
351    unsigned CurrentOffsetInBytes = 4 * 2;
352
353    // And either 2 or 4 pointers.
354    CurrentOffsetInBytes += (HasCopyAndDispose ? 4 : 2) *
355      CGM.getTargetData().getTypeAllocSize(Int8PtrTy);
356
357    // Align the offset.
358    unsigned AlignedOffsetInBytes =
359      llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity());
360
361    unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes;
362    if (NumPaddingBytes > 0) {
363      const llvm::Type *Ty = llvm::Type::getInt8Ty(VMContext);
364      // FIXME: We need a sema error for alignment larger than the minimum of
365      // the maximal stack alignmint and the alignment of malloc on the system.
366      if (NumPaddingBytes > 1)
367        Ty = llvm::ArrayType::get(Ty, NumPaddingBytes);
368
369      Types.push_back(Ty);
370
371      // We want a packed struct.
372      Packed = true;
373    }
374  }
375
376  // T x;
377  Types.push_back(ConvertType(Ty));
378
379  const llvm::Type *T = llvm::StructType::get(VMContext, Types, Packed);
380
381  cast<llvm::OpaqueType>(ByRefTypeHolder.get())->refineAbstractTypeTo(T);
382  CGM.getModule().addTypeName("struct.__block_byref_" + D->getNameAsString(),
383                              ByRefTypeHolder.get());
384
385  Info.first = ByRefTypeHolder.get();
386
387  Info.second = Types.size() - 1;
388
389  return Info.first;
390}
391
392/// EmitLocalBlockVarDecl - Emit code and set up an entry in LocalDeclMap for a
393/// variable declaration with auto, register, or no storage class specifier.
394/// These turn into simple stack objects, or GlobalValues depending on target.
395void CodeGenFunction::EmitLocalBlockVarDecl(const VarDecl &D) {
396  QualType Ty = D.getType();
397  bool isByRef = D.hasAttr<BlocksAttr>();
398  bool needsDispose = false;
399  CharUnits Align = CharUnits::Zero();
400  bool IsSimpleConstantInitializer = false;
401
402  bool NRVO = false;
403  llvm::Value *NRVOFlag = 0;
404  llvm::Value *DeclPtr;
405  if (Ty->isConstantSizeType()) {
406    if (!Target.useGlobalsForAutomaticVariables()) {
407      NRVO = getContext().getLangOptions().ElideConstructors &&
408             D.isNRVOVariable();
409      // If this value is an array or struct, is POD, and if the initializer is
410      // a staticly determinable constant, try to optimize it (unless the NRVO
411      // is already optimizing this).
412      if (D.getInit() && !isByRef &&
413          (Ty->isArrayType() || Ty->isRecordType()) &&
414          Ty->isPODType() &&
415          D.getInit()->isConstantInitializer(getContext()) && !NRVO) {
416        // If this variable is marked 'const', emit the value as a global.
417        if (CGM.getCodeGenOpts().MergeAllConstants &&
418            Ty.isConstant(getContext())) {
419          EmitStaticBlockVarDecl(D, llvm::GlobalValue::InternalLinkage);
420          return;
421        }
422
423        IsSimpleConstantInitializer = true;
424      }
425
426      // A normal fixed sized variable becomes an alloca in the entry block,
427      // unless it's an NRVO variable.
428      const llvm::Type *LTy = ConvertTypeForMem(Ty);
429
430      if (NRVO) {
431        // The named return value optimization: allocate this variable in the
432        // return slot, so that we can elide the copy when returning this
433        // variable (C++0x [class.copy]p34).
434        DeclPtr = ReturnValue;
435
436        if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
437          if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
438            // Create a flag that is used to indicate when the NRVO was applied
439            // to this variable. Set it to zero to indicate that NRVO was not
440            // applied.
441            const llvm::Type *BoolTy = llvm::Type::getInt1Ty(VMContext);
442            llvm::Value *Zero = llvm::ConstantInt::get(BoolTy, 0);
443            NRVOFlag = CreateTempAlloca(BoolTy, "nrvo");
444            Builder.CreateStore(Zero, NRVOFlag);
445
446            // Record the NRVO flag for this variable.
447            NRVOFlags[&D] = NRVOFlag;
448          }
449        }
450      } else {
451        if (isByRef)
452          LTy = BuildByRefType(&D);
453
454        llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
455        Alloc->setName(D.getNameAsString());
456
457        Align = getContext().getDeclAlign(&D);
458        if (isByRef)
459          Align = std::max(Align,
460              CharUnits::fromQuantity(Target.getPointerAlign(0) / 8));
461        Alloc->setAlignment(Align.getQuantity());
462        DeclPtr = Alloc;
463      }
464    } else {
465      // Targets that don't support recursion emit locals as globals.
466      const char *Class =
467        D.getStorageClass() == VarDecl::Register ? ".reg." : ".auto.";
468      DeclPtr = CreateStaticBlockVarDecl(D, Class,
469                                         llvm::GlobalValue
470                                         ::InternalLinkage);
471    }
472
473    // FIXME: Can this happen?
474    if (Ty->isVariablyModifiedType())
475      EmitVLASize(Ty);
476  } else {
477    EnsureInsertPoint();
478
479    if (!DidCallStackSave) {
480      // Save the stack.
481      const llvm::Type *LTy = llvm::Type::getInt8PtrTy(VMContext);
482      llvm::Value *Stack = CreateTempAlloca(LTy, "saved_stack");
483
484      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
485      llvm::Value *V = Builder.CreateCall(F);
486
487      Builder.CreateStore(V, Stack);
488
489      DidCallStackSave = true;
490
491      {
492        // Push a cleanup block and restore the stack there.
493        DelayedCleanupBlock scope(*this);
494
495        V = Builder.CreateLoad(Stack, "tmp");
496        llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
497        Builder.CreateCall(F, V);
498      }
499    }
500
501    // Get the element type.
502    const llvm::Type *LElemTy = ConvertTypeForMem(Ty);
503    const llvm::Type *LElemPtrTy =
504      llvm::PointerType::get(LElemTy, D.getType().getAddressSpace());
505
506    llvm::Value *VLASize = EmitVLASize(Ty);
507
508    // Downcast the VLA size expression
509    VLASize = Builder.CreateIntCast(VLASize, llvm::Type::getInt32Ty(VMContext),
510                                    false, "tmp");
511
512    // Allocate memory for the array.
513    llvm::AllocaInst *VLA =
514      Builder.CreateAlloca(llvm::Type::getInt8Ty(VMContext), VLASize, "vla");
515    VLA->setAlignment(getContext().getDeclAlign(&D).getQuantity());
516
517    DeclPtr = Builder.CreateBitCast(VLA, LElemPtrTy, "tmp");
518  }
519
520  llvm::Value *&DMEntry = LocalDeclMap[&D];
521  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
522  DMEntry = DeclPtr;
523
524  // Emit debug info for local var declaration.
525  if (CGDebugInfo *DI = getDebugInfo()) {
526    assert(HaveInsertPoint() && "Unexpected unreachable point!");
527
528    DI->setLocation(D.getLocation());
529    if (Target.useGlobalsForAutomaticVariables()) {
530      DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
531    } else
532      DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
533  }
534
535  // If this local has an initializer, emit it now.
536  const Expr *Init = D.getInit();
537
538  // If we are at an unreachable point, we don't need to emit the initializer
539  // unless it contains a label.
540  if (!HaveInsertPoint()) {
541    if (!ContainsLabel(Init))
542      Init = 0;
543    else
544      EnsureInsertPoint();
545  }
546
547  if (isByRef) {
548    const llvm::PointerType *PtrToInt8Ty = llvm::Type::getInt8PtrTy(VMContext);
549
550    EnsureInsertPoint();
551    llvm::Value *isa_field = Builder.CreateStructGEP(DeclPtr, 0);
552    llvm::Value *forwarding_field = Builder.CreateStructGEP(DeclPtr, 1);
553    llvm::Value *flags_field = Builder.CreateStructGEP(DeclPtr, 2);
554    llvm::Value *size_field = Builder.CreateStructGEP(DeclPtr, 3);
555    llvm::Value *V;
556    int flag = 0;
557    int flags = 0;
558
559    needsDispose = true;
560
561    if (Ty->isBlockPointerType()) {
562      flag |= BLOCK_FIELD_IS_BLOCK;
563      flags |= BLOCK_HAS_COPY_DISPOSE;
564    } else if (BlockRequiresCopying(Ty)) {
565      flag |= BLOCK_FIELD_IS_OBJECT;
566      flags |= BLOCK_HAS_COPY_DISPOSE;
567    }
568
569    // FIXME: Someone double check this.
570    if (Ty.isObjCGCWeak())
571      flag |= BLOCK_FIELD_IS_WEAK;
572
573    int isa = 0;
574    if (flag&BLOCK_FIELD_IS_WEAK)
575      isa = 1;
576    V = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), isa);
577    V = Builder.CreateIntToPtr(V, PtrToInt8Ty, "isa");
578    Builder.CreateStore(V, isa_field);
579
580    Builder.CreateStore(DeclPtr, forwarding_field);
581
582    V = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), flags);
583    Builder.CreateStore(V, flags_field);
584
585    const llvm::Type *V1;
586    V1 = cast<llvm::PointerType>(DeclPtr->getType())->getElementType();
587    V = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
588                               CGM.GetTargetTypeStoreSize(V1).getQuantity());
589    Builder.CreateStore(V, size_field);
590
591    if (flags & BLOCK_HAS_COPY_DISPOSE) {
592      BlockHasCopyDispose = true;
593      llvm::Value *copy_helper = Builder.CreateStructGEP(DeclPtr, 4);
594      Builder.CreateStore(BuildbyrefCopyHelper(DeclPtr->getType(), flag,
595                                               Align.getQuantity()),
596                          copy_helper);
597
598      llvm::Value *destroy_helper = Builder.CreateStructGEP(DeclPtr, 5);
599      Builder.CreateStore(BuildbyrefDestroyHelper(DeclPtr->getType(), flag,
600                                                  Align.getQuantity()),
601                          destroy_helper);
602    }
603  }
604
605  if (Init) {
606    llvm::Value *Loc = DeclPtr;
607    if (isByRef)
608      Loc = Builder.CreateStructGEP(DeclPtr, getByRefValueLLVMField(&D),
609                                    D.getNameAsString());
610
611    bool isVolatile =
612    getContext().getCanonicalType(D.getType()).isVolatileQualified();
613
614    // If the initializer was a simple constant initializer, we can optimize it
615    // in various ways.
616    if (IsSimpleConstantInitializer) {
617      llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(),D.getType(),this);
618      assert(Init != 0 && "Wasn't a simple constant init?");
619
620      llvm::Value *AlignVal =
621      llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
622                             Align.getQuantity());
623      const llvm::Type *IntPtr =
624      llvm::IntegerType::get(VMContext, LLVMPointerWidth);
625      llvm::Value *SizeVal =
626      llvm::ConstantInt::get(IntPtr,
627                             getContext().getTypeSizeInChars(Ty).getQuantity());
628
629      const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext);
630      if (Loc->getType() != BP)
631        Loc = Builder.CreateBitCast(Loc, BP, "tmp");
632
633      llvm::Value *NotVolatile =
634        llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), 0);
635
636      // If the initializer is all zeros, codegen with memset.
637      if (isa<llvm::ConstantAggregateZero>(Init)) {
638        llvm::Value *Zero =
639          llvm::ConstantInt::get(llvm::Type::getInt8Ty(VMContext), 0);
640        Builder.CreateCall5(CGM.getMemSetFn(Loc->getType(), SizeVal->getType()),
641                            Loc, Zero, SizeVal, AlignVal, NotVolatile);
642      } else {
643        // Otherwise, create a temporary global with the initializer then
644        // memcpy from the global to the alloca.
645        std::string Name = GetStaticDeclName(*this, D, ".");
646        llvm::GlobalVariable *GV =
647        new llvm::GlobalVariable(CGM.getModule(), Init->getType(), true,
648                                 llvm::GlobalValue::InternalLinkage,
649                                 Init, Name, 0, false, 0);
650        GV->setAlignment(Align.getQuantity());
651
652        llvm::Value *SrcPtr = GV;
653        if (SrcPtr->getType() != BP)
654          SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
655
656        Builder.CreateCall5(CGM.getMemCpyFn(Loc->getType(), SrcPtr->getType(),
657                                            SizeVal->getType()),
658                            Loc, SrcPtr, SizeVal, AlignVal, NotVolatile);
659      }
660    } else if (Ty->isReferenceType()) {
661      RValue RV = EmitReferenceBindingToExpr(Init, /*IsInitializer=*/true);
662      EmitStoreOfScalar(RV.getScalarVal(), Loc, false, Ty);
663    } else if (!hasAggregateLLVMType(Init->getType())) {
664      llvm::Value *V = EmitScalarExpr(Init);
665      EmitStoreOfScalar(V, Loc, isVolatile, D.getType());
666    } else if (Init->getType()->isAnyComplexType()) {
667      EmitComplexExprIntoAddr(Init, Loc, isVolatile);
668    } else {
669      EmitAggExpr(Init, Loc, isVolatile);
670    }
671  }
672
673  // Handle CXX destruction of variables.
674  QualType DtorTy(Ty);
675  while (const ArrayType *Array = getContext().getAsArrayType(DtorTy))
676    DtorTy = getContext().getBaseElementType(Array);
677  if (const RecordType *RT = DtorTy->getAs<RecordType>())
678    if (CXXRecordDecl *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
679      if (!ClassDecl->hasTrivialDestructor()) {
680        // Note: We suppress the destructor call when the corresponding NRVO
681        // flag has been set.
682        llvm::Value *Loc = DeclPtr;
683        if (isByRef)
684          Loc = Builder.CreateStructGEP(DeclPtr, getByRefValueLLVMField(&D),
685                                        D.getNameAsString());
686
687        const CXXDestructorDecl *D = ClassDecl->getDestructor(getContext());
688        assert(D && "EmitLocalBlockVarDecl - destructor is nul");
689
690        if (const ConstantArrayType *Array =
691              getContext().getAsConstantArrayType(Ty)) {
692          {
693            DelayedCleanupBlock Scope(*this);
694            QualType BaseElementTy = getContext().getBaseElementType(Array);
695            const llvm::Type *BasePtr = ConvertType(BaseElementTy);
696            BasePtr = llvm::PointerType::getUnqual(BasePtr);
697            llvm::Value *BaseAddrPtr =
698              Builder.CreateBitCast(Loc, BasePtr);
699            EmitCXXAggrDestructorCall(D, Array, BaseAddrPtr);
700
701            // Make sure to jump to the exit block.
702            EmitBranch(Scope.getCleanupExitBlock());
703          }
704          if (Exceptions) {
705            EHCleanupBlock Cleanup(*this);
706            QualType BaseElementTy = getContext().getBaseElementType(Array);
707            const llvm::Type *BasePtr = ConvertType(BaseElementTy);
708            BasePtr = llvm::PointerType::getUnqual(BasePtr);
709            llvm::Value *BaseAddrPtr =
710              Builder.CreateBitCast(Loc, BasePtr);
711            EmitCXXAggrDestructorCall(D, Array, BaseAddrPtr);
712          }
713        } else {
714          {
715            // Normal destruction.
716            DelayedCleanupBlock Scope(*this);
717
718            if (NRVO) {
719              // If we exited via NRVO, we skip the destructor call.
720              llvm::BasicBlock *NoNRVO = createBasicBlock("nrvo.unused");
721              Builder.CreateCondBr(Builder.CreateLoad(NRVOFlag, "nrvo.val"),
722                                   Scope.getCleanupExitBlock(),
723                                   NoNRVO);
724              EmitBlock(NoNRVO);
725            }
726
727            // We don't call the destructor along the normal edge if we're
728            // applying the NRVO.
729            EmitCXXDestructorCall(D, Dtor_Complete, /*ForVirtualBase=*/false,
730                                  Loc);
731
732            // Make sure to jump to the exit block.
733            EmitBranch(Scope.getCleanupExitBlock());
734          }
735
736          if (Exceptions) {
737            EHCleanupBlock Cleanup(*this);
738            EmitCXXDestructorCall(D, Dtor_Complete, /*ForVirtualBase=*/false,
739                                  Loc);
740          }
741        }
742      }
743  }
744
745  // Handle the cleanup attribute
746  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
747    const FunctionDecl *FD = CA->getFunctionDecl();
748
749    llvm::Constant* F = CGM.GetAddrOfFunction(FD);
750    assert(F && "Could not find function!");
751
752    const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
753
754    // In some cases, the type of the function argument will be different from
755    // the type of the pointer. An example of this is
756    // void f(void* arg);
757    // __attribute__((cleanup(f))) void *g;
758    //
759    // To fix this we insert a bitcast here.
760    QualType ArgTy = Info.arg_begin()->type;
761    {
762      DelayedCleanupBlock scope(*this);
763
764      CallArgList Args;
765      Args.push_back(std::make_pair(RValue::get(Builder.CreateBitCast(DeclPtr,
766                                                           ConvertType(ArgTy))),
767                                    getContext().getPointerType(D.getType())));
768      EmitCall(Info, F, ReturnValueSlot(), Args);
769    }
770    if (Exceptions) {
771      EHCleanupBlock Cleanup(*this);
772
773      CallArgList Args;
774      Args.push_back(std::make_pair(RValue::get(Builder.CreateBitCast(DeclPtr,
775                                                           ConvertType(ArgTy))),
776                                    getContext().getPointerType(D.getType())));
777      EmitCall(Info, F, ReturnValueSlot(), Args);
778    }
779  }
780
781  if (needsDispose && CGM.getLangOptions().getGCMode() != LangOptions::GCOnly) {
782    {
783      DelayedCleanupBlock scope(*this);
784      llvm::Value *V = Builder.CreateStructGEP(DeclPtr, 1, "forwarding");
785      V = Builder.CreateLoad(V);
786      BuildBlockRelease(V);
787    }
788    // FIXME: Turn this on and audit the codegen
789    if (0 && Exceptions) {
790      EHCleanupBlock Cleanup(*this);
791      llvm::Value *V = Builder.CreateStructGEP(DeclPtr, 1, "forwarding");
792      V = Builder.CreateLoad(V);
793      BuildBlockRelease(V);
794    }
795  }
796}
797
798/// Emit an alloca (or GlobalValue depending on target)
799/// for the specified parameter and set up LocalDeclMap.
800void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg) {
801  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
802  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
803         "Invalid argument to EmitParmDecl");
804  QualType Ty = D.getType();
805  CanQualType CTy = getContext().getCanonicalType(Ty);
806
807  llvm::Value *DeclPtr;
808  // If this is an aggregate or variable sized value, reuse the input pointer.
809  if (!Ty->isConstantSizeType() ||
810      CodeGenFunction::hasAggregateLLVMType(Ty)) {
811    DeclPtr = Arg;
812  } else {
813    // Otherwise, create a temporary to hold the value.
814    DeclPtr = CreateMemTemp(Ty, D.getName() + ".addr");
815
816    // Store the initial value into the alloca.
817    EmitStoreOfScalar(Arg, DeclPtr, CTy.isVolatileQualified(), Ty);
818  }
819  Arg->setName(D.getName());
820
821  llvm::Value *&DMEntry = LocalDeclMap[&D];
822  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
823  DMEntry = DeclPtr;
824
825  // Emit debug info for param declaration.
826  if (CGDebugInfo *DI = getDebugInfo()) {
827    DI->setLocation(D.getLocation());
828    DI->EmitDeclareOfArgVariable(&D, DeclPtr, Builder);
829  }
830}
831