CGDecl.cpp revision ddfb8d1026d8f9001d8111bd8a96d89301aa11cd 
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 "CGOpenCLRuntime.h"
18#include "clang/AST/ASTContext.h"
19#include "clang/AST/CharUnits.h"
20#include "clang/AST/Decl.h"
21#include "clang/AST/DeclObjC.h"
22#include "clang/Basic/SourceManager.h"
23#include "clang/Basic/TargetInfo.h"
24#include "clang/Frontend/CodeGenOptions.h"
25#include "llvm/GlobalVariable.h"
26#include "llvm/Intrinsics.h"
27#include "llvm/Target/TargetData.h"
28#include "llvm/Type.h"
29using namespace clang;
30using namespace CodeGen;
31
32
33void CodeGenFunction::EmitDecl(const Decl &D) {
34  switch (D.getKind()) {
35  case Decl::TranslationUnit:
36  case Decl::Namespace:
37  case Decl::UnresolvedUsingTypename:
38  case Decl::ClassTemplateSpecialization:
39  case Decl::ClassTemplatePartialSpecialization:
40  case Decl::TemplateTypeParm:
41  case Decl::UnresolvedUsingValue:
42  case Decl::NonTypeTemplateParm:
43  case Decl::CXXMethod:
44  case Decl::CXXConstructor:
45  case Decl::CXXDestructor:
46  case Decl::CXXConversion:
47  case Decl::Field:
48  case Decl::IndirectField:
49  case Decl::ObjCIvar:
50  case Decl::ObjCAtDefsField:
51  case Decl::ParmVar:
52  case Decl::ImplicitParam:
53  case Decl::ClassTemplate:
54  case Decl::FunctionTemplate:
55  case Decl::TypeAliasTemplate:
56  case Decl::TemplateTemplateParm:
57  case Decl::ObjCMethod:
58  case Decl::ObjCCategory:
59  case Decl::ObjCProtocol:
60  case Decl::ObjCInterface:
61  case Decl::ObjCCategoryImpl:
62  case Decl::ObjCImplementation:
63  case Decl::ObjCProperty:
64  case Decl::ObjCCompatibleAlias:
65  case Decl::AccessSpec:
66  case Decl::LinkageSpec:
67  case Decl::ObjCPropertyImpl:
68  case Decl::ObjCClass:
69  case Decl::ObjCForwardProtocol:
70  case Decl::FileScopeAsm:
71  case Decl::Friend:
72  case Decl::FriendTemplate:
73  case Decl::Block:
74  case Decl::ClassScopeFunctionSpecialization:
75    llvm_unreachable("Declaration should not be in declstmts!");
76  case Decl::Function:  // void X();
77  case Decl::Record:    // struct/union/class X;
78  case Decl::Enum:      // enum X;
79  case Decl::EnumConstant: // enum ? { X = ? }
80  case Decl::CXXRecord: // struct/union/class X; [C++]
81  case Decl::Using:          // using X; [C++]
82  case Decl::UsingShadow:
83  case Decl::UsingDirective: // using namespace X; [C++]
84  case Decl::NamespaceAlias:
85  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
86  case Decl::Label:        // __label__ x;
87    // None of these decls require codegen support.
88    return;
89
90  case Decl::Var: {
91    const VarDecl &VD = cast<VarDecl>(D);
92    assert(VD.isLocalVarDecl() &&
93           "Should not see file-scope variables inside a function!");
94    return EmitVarDecl(VD);
95  }
96
97  case Decl::Typedef:      // typedef int X;
98  case Decl::TypeAlias: {  // using X = int; [C++0x]
99    const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
100    QualType Ty = TD.getUnderlyingType();
101
102    if (Ty->isVariablyModifiedType())
103      EmitVariablyModifiedType(Ty);
104  }
105  }
106}
107
108/// EmitVarDecl - This method handles emission of any variable declaration
109/// inside a function, including static vars etc.
110void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
111  switch (D.getStorageClass()) {
112  case SC_None:
113  case SC_Auto:
114  case SC_Register:
115    return EmitAutoVarDecl(D);
116  case SC_Static: {
117    llvm::GlobalValue::LinkageTypes Linkage =
118      llvm::GlobalValue::InternalLinkage;
119
120    // If the function definition has some sort of weak linkage, its
121    // static variables should also be weak so that they get properly
122    // uniqued.  We can't do this in C, though, because there's no
123    // standard way to agree on which variables are the same (i.e.
124    // there's no mangling).
125    if (getContext().getLangOptions().CPlusPlus)
126      if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
127        Linkage = CurFn->getLinkage();
128
129    return EmitStaticVarDecl(D, Linkage);
130  }
131  case SC_Extern:
132  case SC_PrivateExtern:
133    // Don't emit it now, allow it to be emitted lazily on its first use.
134    return;
135  case SC_OpenCLWorkGroupLocal:
136    return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
137  }
138
139  llvm_unreachable("Unknown storage class");
140}
141
142static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
143                                     const char *Separator) {
144  CodeGenModule &CGM = CGF.CGM;
145  if (CGF.getContext().getLangOptions().CPlusPlus) {
146    StringRef Name = CGM.getMangledName(&D);
147    return Name.str();
148  }
149
150  std::string ContextName;
151  if (!CGF.CurFuncDecl) {
152    // Better be in a block declared in global scope.
153    const NamedDecl *ND = cast<NamedDecl>(&D);
154    const DeclContext *DC = ND->getDeclContext();
155    if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
156      MangleBuffer Name;
157      CGM.getBlockMangledName(GlobalDecl(), Name, BD);
158      ContextName = Name.getString();
159    }
160    else
161      llvm_unreachable("Unknown context for block static var decl");
162  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
163    StringRef Name = CGM.getMangledName(FD);
164    ContextName = Name.str();
165  } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
166    ContextName = CGF.CurFn->getName();
167  else
168    llvm_unreachable("Unknown context for static var decl");
169
170  return ContextName + Separator + D.getNameAsString();
171}
172
173llvm::GlobalVariable *
174CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
175                                     const char *Separator,
176                                     llvm::GlobalValue::LinkageTypes Linkage) {
177  QualType Ty = D.getType();
178  assert(Ty->isConstantSizeType() && "VLAs can't be static");
179
180  std::string Name = GetStaticDeclName(*this, D, Separator);
181
182  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
183  llvm::GlobalVariable *GV =
184    new llvm::GlobalVariable(CGM.getModule(), LTy,
185                             Ty.isConstant(getContext()), Linkage,
186                             CGM.EmitNullConstant(D.getType()), Name, 0,
187                             D.isThreadSpecified(),
188                             CGM.getContext().getTargetAddressSpace(Ty));
189  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
190  if (Linkage != llvm::GlobalValue::InternalLinkage)
191    GV->setVisibility(CurFn->getVisibility());
192  return GV;
193}
194
195/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
196/// global variable that has already been created for it.  If the initializer
197/// has a different type than GV does, this may free GV and return a different
198/// one.  Otherwise it just returns GV.
199llvm::GlobalVariable *
200CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
201                                               llvm::GlobalVariable *GV) {
202  llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this);
203
204  // If constant emission failed, then this should be a C++ static
205  // initializer.
206  if (!Init) {
207    if (!getContext().getLangOptions().CPlusPlus)
208      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
209    else if (Builder.GetInsertBlock()) {
210      // Since we have a static initializer, this global variable can't
211      // be constant.
212      GV->setConstant(false);
213
214      EmitCXXGuardedInit(D, GV);
215    }
216    return GV;
217  }
218
219  // The initializer may differ in type from the global. Rewrite
220  // the global to match the initializer.  (We have to do this
221  // because some types, like unions, can't be completely represented
222  // in the LLVM type system.)
223  if (GV->getType()->getElementType() != Init->getType()) {
224    llvm::GlobalVariable *OldGV = GV;
225
226    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
227                                  OldGV->isConstant(),
228                                  OldGV->getLinkage(), Init, "",
229                                  /*InsertBefore*/ OldGV,
230                                  D.isThreadSpecified(),
231                           CGM.getContext().getTargetAddressSpace(D.getType()));
232    GV->setVisibility(OldGV->getVisibility());
233
234    // Steal the name of the old global
235    GV->takeName(OldGV);
236
237    // Replace all uses of the old global with the new global
238    llvm::Constant *NewPtrForOldDecl =
239    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
240    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
241
242    // Erase the old global, since it is no longer used.
243    OldGV->eraseFromParent();
244  }
245
246  GV->setInitializer(Init);
247  return GV;
248}
249
250void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
251                                      llvm::GlobalValue::LinkageTypes Linkage) {
252  llvm::Value *&DMEntry = LocalDeclMap[&D];
253  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
254
255  llvm::GlobalVariable *GV = CreateStaticVarDecl(D, ".", Linkage);
256
257  // Store into LocalDeclMap before generating initializer to handle
258  // circular references.
259  DMEntry = GV;
260
261  // We can't have a VLA here, but we can have a pointer to a VLA,
262  // even though that doesn't really make any sense.
263  // Make sure to evaluate VLA bounds now so that we have them for later.
264  if (D.getType()->isVariablyModifiedType())
265    EmitVariablyModifiedType(D.getType());
266
267  // Local static block variables must be treated as globals as they may be
268  // referenced in their RHS initializer block-literal expresion.
269  CGM.setStaticLocalDeclAddress(&D, GV);
270
271  // If this value has an initializer, emit it.
272  if (D.getInit())
273    GV = AddInitializerToStaticVarDecl(D, GV);
274
275  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
276
277  if (D.hasAttr<AnnotateAttr>())
278    CGM.AddGlobalAnnotations(&D, GV);
279
280  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
281    GV->setSection(SA->getName());
282
283  if (D.hasAttr<UsedAttr>())
284    CGM.AddUsedGlobal(GV);
285
286  // We may have to cast the constant because of the initializer
287  // mismatch above.
288  //
289  // FIXME: It is really dangerous to store this in the map; if anyone
290  // RAUW's the GV uses of this constant will be invalid.
291  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
292  llvm::Type *LPtrTy =
293    LTy->getPointerTo(CGM.getContext().getTargetAddressSpace(D.getType()));
294  DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
295
296  // Emit global variable debug descriptor for static vars.
297  CGDebugInfo *DI = getDebugInfo();
298  if (DI) {
299    DI->setLocation(D.getLocation());
300    DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
301  }
302}
303
304namespace {
305  struct DestroyObject : EHScopeStack::Cleanup {
306    DestroyObject(llvm::Value *addr, QualType type,
307                  CodeGenFunction::Destroyer *destroyer,
308                  bool useEHCleanupForArray)
309      : addr(addr), type(type), destroyer(*destroyer),
310        useEHCleanupForArray(useEHCleanupForArray) {}
311
312    llvm::Value *addr;
313    QualType type;
314    CodeGenFunction::Destroyer &destroyer;
315    bool useEHCleanupForArray;
316
317    void Emit(CodeGenFunction &CGF, Flags flags) {
318      // Don't use an EH cleanup recursively from an EH cleanup.
319      bool useEHCleanupForArray =
320        flags.isForNormalCleanup() && this->useEHCleanupForArray;
321
322      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
323    }
324  };
325
326  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
327    DestroyNRVOVariable(llvm::Value *addr,
328                        const CXXDestructorDecl *Dtor,
329                        llvm::Value *NRVOFlag)
330      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
331
332    const CXXDestructorDecl *Dtor;
333    llvm::Value *NRVOFlag;
334    llvm::Value *Loc;
335
336    void Emit(CodeGenFunction &CGF, Flags flags) {
337      // Along the exceptions path we always execute the dtor.
338      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
339
340      llvm::BasicBlock *SkipDtorBB = 0;
341      if (NRVO) {
342        // If we exited via NRVO, we skip the destructor call.
343        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
344        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
345        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
346        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
347        CGF.EmitBlock(RunDtorBB);
348      }
349
350      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
351                                /*ForVirtualBase=*/false, Loc);
352
353      if (NRVO) CGF.EmitBlock(SkipDtorBB);
354    }
355  };
356
357  struct CallStackRestore : EHScopeStack::Cleanup {
358    llvm::Value *Stack;
359    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
360    void Emit(CodeGenFunction &CGF, Flags flags) {
361      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
362      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
363      CGF.Builder.CreateCall(F, V);
364    }
365  };
366
367  struct ExtendGCLifetime : EHScopeStack::Cleanup {
368    const VarDecl &Var;
369    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
370
371    void Emit(CodeGenFunction &CGF, Flags flags) {
372      // Compute the address of the local variable, in case it's a
373      // byref or something.
374      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
375                      SourceLocation());
376      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
377      CGF.EmitExtendGCLifetime(value);
378    }
379  };
380
381  struct CallCleanupFunction : EHScopeStack::Cleanup {
382    llvm::Constant *CleanupFn;
383    const CGFunctionInfo &FnInfo;
384    const VarDecl &Var;
385
386    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
387                        const VarDecl *Var)
388      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
389
390    void Emit(CodeGenFunction &CGF, Flags flags) {
391      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
392                      SourceLocation());
393      // Compute the address of the local variable, in case it's a byref
394      // or something.
395      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
396
397      // In some cases, the type of the function argument will be different from
398      // the type of the pointer. An example of this is
399      // void f(void* arg);
400      // __attribute__((cleanup(f))) void *g;
401      //
402      // To fix this we insert a bitcast here.
403      QualType ArgTy = FnInfo.arg_begin()->type;
404      llvm::Value *Arg =
405        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
406
407      CallArgList Args;
408      Args.add(RValue::get(Arg),
409               CGF.getContext().getPointerType(Var.getType()));
410      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
411    }
412  };
413}
414
415/// EmitAutoVarWithLifetime - Does the setup required for an automatic
416/// variable with lifetime.
417static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
418                                    llvm::Value *addr,
419                                    Qualifiers::ObjCLifetime lifetime) {
420  switch (lifetime) {
421  case Qualifiers::OCL_None:
422    llvm_unreachable("present but none");
423
424  case Qualifiers::OCL_ExplicitNone:
425    // nothing to do
426    break;
427
428  case Qualifiers::OCL_Strong: {
429    CodeGenFunction::Destroyer &destroyer =
430      (var.hasAttr<ObjCPreciseLifetimeAttr>()
431       ? CodeGenFunction::destroyARCStrongPrecise
432       : CodeGenFunction::destroyARCStrongImprecise);
433
434    CleanupKind cleanupKind = CGF.getARCCleanupKind();
435    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
436                    cleanupKind & EHCleanup);
437    break;
438  }
439  case Qualifiers::OCL_Autoreleasing:
440    // nothing to do
441    break;
442
443  case Qualifiers::OCL_Weak:
444    // __weak objects always get EH cleanups; otherwise, exceptions
445    // could cause really nasty crashes instead of mere leaks.
446    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
447                    CodeGenFunction::destroyARCWeak,
448                    /*useEHCleanup*/ true);
449    break;
450  }
451}
452
453static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
454  if (const Expr *e = dyn_cast<Expr>(s)) {
455    // Skip the most common kinds of expressions that make
456    // hierarchy-walking expensive.
457    s = e = e->IgnoreParenCasts();
458
459    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
460      return (ref->getDecl() == &var);
461  }
462
463  for (Stmt::const_child_range children = s->children(); children; ++children)
464    // children might be null; as in missing decl or conditional of an if-stmt.
465    if ((*children) && isAccessedBy(var, *children))
466      return true;
467
468  return false;
469}
470
471static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
472  if (!decl) return false;
473  if (!isa<VarDecl>(decl)) return false;
474  const VarDecl *var = cast<VarDecl>(decl);
475  return isAccessedBy(*var, e);
476}
477
478static void drillIntoBlockVariable(CodeGenFunction &CGF,
479                                   LValue &lvalue,
480                                   const VarDecl *var) {
481  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
482}
483
484void CodeGenFunction::EmitScalarInit(const Expr *init,
485                                     const ValueDecl *D,
486                                     LValue lvalue,
487                                     bool capturedByInit) {
488  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
489  if (!lifetime) {
490    llvm::Value *value = EmitScalarExpr(init);
491    if (capturedByInit)
492      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
493    EmitStoreThroughLValue(RValue::get(value), lvalue);
494    return;
495  }
496
497  // If we're emitting a value with lifetime, we have to do the
498  // initialization *before* we leave the cleanup scopes.
499  CodeGenFunction::RunCleanupsScope Scope(*this);
500  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init))
501    init = ewc->getSubExpr();
502
503  // We have to maintain the illusion that the variable is
504  // zero-initialized.  If the variable might be accessed in its
505  // initializer, zero-initialize before running the initializer, then
506  // actually perform the initialization with an assign.
507  bool accessedByInit = false;
508  if (lifetime != Qualifiers::OCL_ExplicitNone)
509    accessedByInit = (capturedByInit || isAccessedBy(D, init));
510  if (accessedByInit) {
511    LValue tempLV = lvalue;
512    // Drill down to the __block object if necessary.
513    if (capturedByInit) {
514      // We can use a simple GEP for this because it can't have been
515      // moved yet.
516      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
517                                   getByRefValueLLVMField(cast<VarDecl>(D))));
518    }
519
520    llvm::PointerType *ty
521      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
522    ty = cast<llvm::PointerType>(ty->getElementType());
523
524    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
525
526    // If __weak, we want to use a barrier under certain conditions.
527    if (lifetime == Qualifiers::OCL_Weak)
528      EmitARCInitWeak(tempLV.getAddress(), zero);
529
530    // Otherwise just do a simple store.
531    else
532      EmitStoreOfScalar(zero, tempLV);
533  }
534
535  // Emit the initializer.
536  llvm::Value *value = 0;
537
538  switch (lifetime) {
539  case Qualifiers::OCL_None:
540    llvm_unreachable("present but none");
541
542  case Qualifiers::OCL_ExplicitNone:
543    // nothing to do
544    value = EmitScalarExpr(init);
545    break;
546
547  case Qualifiers::OCL_Strong: {
548    value = EmitARCRetainScalarExpr(init);
549    break;
550  }
551
552  case Qualifiers::OCL_Weak: {
553    // No way to optimize a producing initializer into this.  It's not
554    // worth optimizing for, because the value will immediately
555    // disappear in the common case.
556    value = EmitScalarExpr(init);
557
558    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
559    if (accessedByInit)
560      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
561    else
562      EmitARCInitWeak(lvalue.getAddress(), value);
563    return;
564  }
565
566  case Qualifiers::OCL_Autoreleasing:
567    value = EmitARCRetainAutoreleaseScalarExpr(init);
568    break;
569  }
570
571  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
572
573  // If the variable might have been accessed by its initializer, we
574  // might have to initialize with a barrier.  We have to do this for
575  // both __weak and __strong, but __weak got filtered out above.
576  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
577    llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
578    EmitStoreOfScalar(value, lvalue);
579    EmitARCRelease(oldValue, /*precise*/ false);
580    return;
581  }
582
583  EmitStoreOfScalar(value, lvalue);
584}
585
586/// EmitScalarInit - Initialize the given lvalue with the given object.
587void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
588  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
589  if (!lifetime)
590    return EmitStoreThroughLValue(RValue::get(init), lvalue);
591
592  switch (lifetime) {
593  case Qualifiers::OCL_None:
594    llvm_unreachable("present but none");
595
596  case Qualifiers::OCL_ExplicitNone:
597    // nothing to do
598    break;
599
600  case Qualifiers::OCL_Strong:
601    init = EmitARCRetain(lvalue.getType(), init);
602    break;
603
604  case Qualifiers::OCL_Weak:
605    // Initialize and then skip the primitive store.
606    EmitARCInitWeak(lvalue.getAddress(), init);
607    return;
608
609  case Qualifiers::OCL_Autoreleasing:
610    init = EmitARCRetainAutorelease(lvalue.getType(), init);
611    break;
612  }
613
614  EmitStoreOfScalar(init, lvalue);
615}
616
617/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
618/// non-zero parts of the specified initializer with equal or fewer than
619/// NumStores scalar stores.
620static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
621                                                unsigned &NumStores) {
622  // Zero and Undef never requires any extra stores.
623  if (isa<llvm::ConstantAggregateZero>(Init) ||
624      isa<llvm::ConstantPointerNull>(Init) ||
625      isa<llvm::UndefValue>(Init))
626    return true;
627  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
628      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
629      isa<llvm::ConstantExpr>(Init))
630    return Init->isNullValue() || NumStores--;
631
632  // See if we can emit each element.
633  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
634    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
635      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
636      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
637        return false;
638    }
639    return true;
640  }
641
642  // Anything else is hard and scary.
643  return false;
644}
645
646/// emitStoresForInitAfterMemset - For inits that
647/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
648/// stores that would be required.
649static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
650                                         bool isVolatile, CGBuilderTy &Builder) {
651  // Zero doesn't require any stores.
652  if (isa<llvm::ConstantAggregateZero>(Init) ||
653      isa<llvm::ConstantPointerNull>(Init) ||
654      isa<llvm::UndefValue>(Init))
655    return;
656
657  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
658      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
659      isa<llvm::ConstantExpr>(Init)) {
660    if (!Init->isNullValue())
661      Builder.CreateStore(Init, Loc, isVolatile);
662    return;
663  }
664
665  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
666         "Unknown value type!");
667
668  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
669    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
670    if (Elt->isNullValue()) continue;
671
672    // Otherwise, get a pointer to the element and emit it.
673    emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
674                                 isVolatile, Builder);
675  }
676}
677
678
679/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
680/// plus some stores to initialize a local variable instead of using a memcpy
681/// from a constant global.  It is beneficial to use memset if the global is all
682/// zeros, or mostly zeros and large.
683static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
684                                                  uint64_t GlobalSize) {
685  // If a global is all zeros, always use a memset.
686  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
687
688
689  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
690  // do it if it will require 6 or fewer scalar stores.
691  // TODO: Should budget depends on the size?  Avoiding a large global warrants
692  // plopping in more stores.
693  unsigned StoreBudget = 6;
694  uint64_t SizeLimit = 32;
695
696  return GlobalSize > SizeLimit &&
697         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
698}
699
700
701/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
702/// variable declaration with auto, register, or no storage class specifier.
703/// These turn into simple stack objects, or GlobalValues depending on target.
704void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
705  AutoVarEmission emission = EmitAutoVarAlloca(D);
706  EmitAutoVarInit(emission);
707  EmitAutoVarCleanups(emission);
708}
709
710/// EmitAutoVarAlloca - Emit the alloca and debug information for a
711/// local variable.  Does not emit initalization or destruction.
712CodeGenFunction::AutoVarEmission
713CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
714  QualType Ty = D.getType();
715
716  AutoVarEmission emission(D);
717
718  bool isByRef = D.hasAttr<BlocksAttr>();
719  emission.IsByRef = isByRef;
720
721  CharUnits alignment = getContext().getDeclAlign(&D);
722  emission.Alignment = alignment;
723
724  // If the type is variably-modified, emit all the VLA sizes for it.
725  if (Ty->isVariablyModifiedType())
726    EmitVariablyModifiedType(Ty);
727
728  llvm::Value *DeclPtr;
729  if (Ty->isConstantSizeType()) {
730    if (!Target.useGlobalsForAutomaticVariables()) {
731      bool NRVO = getContext().getLangOptions().ElideConstructors &&
732                  D.isNRVOVariable();
733
734      // If this value is a POD array or struct with a statically
735      // determinable constant initializer, there are optimizations we
736      // can do.
737      // TODO: we can potentially constant-evaluate non-POD structs and
738      // arrays as long as the initialization is trivial (e.g. if they
739      // have a non-trivial destructor, but not a non-trivial constructor).
740      if (D.getInit() &&
741          (Ty->isArrayType() || Ty->isRecordType()) &&
742          (Ty.isPODType(getContext()) ||
743           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
744          D.getInit()->isConstantInitializer(getContext(), false)) {
745
746        // If the variable's a const type, and it's neither an NRVO
747        // candidate nor a __block variable, emit it as a global instead.
748        if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() &&
749            !NRVO && !isByRef) {
750          EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
751
752          emission.Address = 0; // signal this condition to later callbacks
753          assert(emission.wasEmittedAsGlobal());
754          return emission;
755        }
756
757        // Otherwise, tell the initialization code that we're in this case.
758        emission.IsConstantAggregate = true;
759      }
760
761      // A normal fixed sized variable becomes an alloca in the entry block,
762      // unless it's an NRVO variable.
763      llvm::Type *LTy = ConvertTypeForMem(Ty);
764
765      if (NRVO) {
766        // The named return value optimization: allocate this variable in the
767        // return slot, so that we can elide the copy when returning this
768        // variable (C++0x [class.copy]p34).
769        DeclPtr = ReturnValue;
770
771        if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
772          if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
773            // Create a flag that is used to indicate when the NRVO was applied
774            // to this variable. Set it to zero to indicate that NRVO was not
775            // applied.
776            llvm::Value *Zero = Builder.getFalse();
777            llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
778            EnsureInsertPoint();
779            Builder.CreateStore(Zero, NRVOFlag);
780
781            // Record the NRVO flag for this variable.
782            NRVOFlags[&D] = NRVOFlag;
783            emission.NRVOFlag = NRVOFlag;
784          }
785        }
786      } else {
787        if (isByRef)
788          LTy = BuildByRefType(&D);
789
790        llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
791        Alloc->setName(D.getNameAsString());
792
793        CharUnits allocaAlignment = alignment;
794        if (isByRef)
795          allocaAlignment = std::max(allocaAlignment,
796              getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
797        Alloc->setAlignment(allocaAlignment.getQuantity());
798        DeclPtr = Alloc;
799      }
800    } else {
801      // Targets that don't support recursion emit locals as globals.
802      const char *Class =
803        D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
804      DeclPtr = CreateStaticVarDecl(D, Class,
805                                    llvm::GlobalValue::InternalLinkage);
806    }
807  } else {
808    EnsureInsertPoint();
809
810    if (!DidCallStackSave) {
811      // Save the stack.
812      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
813
814      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
815      llvm::Value *V = Builder.CreateCall(F);
816
817      Builder.CreateStore(V, Stack);
818
819      DidCallStackSave = true;
820
821      // Push a cleanup block and restore the stack there.
822      // FIXME: in general circumstances, this should be an EH cleanup.
823      EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
824    }
825
826    llvm::Value *elementCount;
827    QualType elementType;
828    llvm::tie(elementCount, elementType) = getVLASize(Ty);
829
830    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
831
832    // Allocate memory for the array.
833    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
834    vla->setAlignment(alignment.getQuantity());
835
836    DeclPtr = vla;
837  }
838
839  llvm::Value *&DMEntry = LocalDeclMap[&D];
840  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
841  DMEntry = DeclPtr;
842  emission.Address = DeclPtr;
843
844  // Emit debug info for local var declaration.
845  if (HaveInsertPoint())
846    if (CGDebugInfo *DI = getDebugInfo()) {
847      DI->setLocation(D.getLocation());
848      if (Target.useGlobalsForAutomaticVariables()) {
849        DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
850      } else
851        DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
852    }
853
854  if (D.hasAttr<AnnotateAttr>())
855      EmitVarAnnotations(&D, emission.Address);
856
857  return emission;
858}
859
860/// Determines whether the given __block variable is potentially
861/// captured by the given expression.
862static bool isCapturedBy(const VarDecl &var, const Expr *e) {
863  // Skip the most common kinds of expressions that make
864  // hierarchy-walking expensive.
865  e = e->IgnoreParenCasts();
866
867  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
868    const BlockDecl *block = be->getBlockDecl();
869    for (BlockDecl::capture_const_iterator i = block->capture_begin(),
870           e = block->capture_end(); i != e; ++i) {
871      if (i->getVariable() == &var)
872        return true;
873    }
874
875    // No need to walk into the subexpressions.
876    return false;
877  }
878
879  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
880    const CompoundStmt *CS = SE->getSubStmt();
881    for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
882	   BE = CS->body_end(); BI != BE; ++BI)
883      if (Expr *E = dyn_cast<Expr>((*BI))) {
884        if (isCapturedBy(var, E))
885            return true;
886      }
887      else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) {
888          // special case declarations
889          for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
890               I != E; ++I) {
891              if (VarDecl *VD = dyn_cast<VarDecl>((*I))) {
892                Expr *Init = VD->getInit();
893                if (Init && isCapturedBy(var, Init))
894                  return true;
895              }
896          }
897      }
898      else
899        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
900        // Later, provide code to poke into statements for capture analysis.
901        return true;
902    return false;
903  }
904
905  for (Stmt::const_child_range children = e->children(); children; ++children)
906    if (isCapturedBy(var, cast<Expr>(*children)))
907      return true;
908
909  return false;
910}
911
912/// \brief Determine whether the given initializer is trivial in the sense
913/// that it requires no code to be generated.
914static bool isTrivialInitializer(const Expr *Init) {
915  if (!Init)
916    return true;
917
918  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
919    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
920      if (Constructor->isTrivial() &&
921          Constructor->isDefaultConstructor() &&
922          !Construct->requiresZeroInitialization())
923        return true;
924
925  return false;
926}
927void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
928  assert(emission.Variable && "emission was not valid!");
929
930  // If this was emitted as a global constant, we're done.
931  if (emission.wasEmittedAsGlobal()) return;
932
933  const VarDecl &D = *emission.Variable;
934  QualType type = D.getType();
935
936  // If this local has an initializer, emit it now.
937  const Expr *Init = D.getInit();
938
939  // If we are at an unreachable point, we don't need to emit the initializer
940  // unless it contains a label.
941  if (!HaveInsertPoint()) {
942    if (!Init || !ContainsLabel(Init)) return;
943    EnsureInsertPoint();
944  }
945
946  // Initialize the structure of a __block variable.
947  if (emission.IsByRef)
948    emitByrefStructureInit(emission);
949
950  if (isTrivialInitializer(Init))
951    return;
952
953  CharUnits alignment = emission.Alignment;
954
955  // Check whether this is a byref variable that's potentially
956  // captured and moved by its own initializer.  If so, we'll need to
957  // emit the initializer first, then copy into the variable.
958  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
959
960  llvm::Value *Loc =
961    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
962
963  if (!emission.IsConstantAggregate) {
964    LValue lv = MakeAddrLValue(Loc, type, alignment.getQuantity());
965    lv.setNonGC(true);
966    return EmitExprAsInit(Init, &D, lv, capturedByInit);
967  }
968
969  // If this is a simple aggregate initialization, we can optimize it
970  // in various ways.
971  assert(!capturedByInit && "constant init contains a capturing block?");
972
973  bool isVolatile = type.isVolatileQualified();
974
975  llvm::Constant *constant = CGM.EmitConstantExpr(D.getInit(), type, this);
976  assert(constant != 0 && "Wasn't a simple constant init?");
977
978  llvm::Value *SizeVal =
979    llvm::ConstantInt::get(IntPtrTy,
980                           getContext().getTypeSizeInChars(type).getQuantity());
981
982  llvm::Type *BP = Int8PtrTy;
983  if (Loc->getType() != BP)
984    Loc = Builder.CreateBitCast(Loc, BP);
985
986  // If the initializer is all or mostly zeros, codegen with memset then do
987  // a few stores afterward.
988  if (shouldUseMemSetPlusStoresToInitialize(constant,
989                CGM.getTargetData().getTypeAllocSize(constant->getType()))) {
990    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
991                         alignment.getQuantity(), isVolatile);
992    if (!constant->isNullValue()) {
993      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
994      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
995    }
996  } else {
997    // Otherwise, create a temporary global with the initializer then
998    // memcpy from the global to the alloca.
999    std::string Name = GetStaticDeclName(*this, D, ".");
1000    llvm::GlobalVariable *GV =
1001      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1002                               llvm::GlobalValue::PrivateLinkage,
1003                               constant, Name, 0, false, 0);
1004    GV->setAlignment(alignment.getQuantity());
1005    GV->setUnnamedAddr(true);
1006
1007    llvm::Value *SrcPtr = GV;
1008    if (SrcPtr->getType() != BP)
1009      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1010
1011    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1012                         isVolatile);
1013  }
1014}
1015
1016/// Emit an expression as an initializer for a variable at the given
1017/// location.  The expression is not necessarily the normal
1018/// initializer for the variable, and the address is not necessarily
1019/// its normal location.
1020///
1021/// \param init the initializing expression
1022/// \param var the variable to act as if we're initializing
1023/// \param loc the address to initialize; its type is a pointer
1024///   to the LLVM mapping of the variable's type
1025/// \param alignment the alignment of the address
1026/// \param capturedByInit true if the variable is a __block variable
1027///   whose address is potentially changed by the initializer
1028void CodeGenFunction::EmitExprAsInit(const Expr *init,
1029                                     const ValueDecl *D,
1030                                     LValue lvalue,
1031                                     bool capturedByInit) {
1032  QualType type = D->getType();
1033
1034  if (type->isReferenceType()) {
1035    RValue rvalue = EmitReferenceBindingToExpr(init, D);
1036    if (capturedByInit)
1037      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1038    EmitStoreThroughLValue(rvalue, lvalue);
1039  } else if (!hasAggregateLLVMType(type)) {
1040    EmitScalarInit(init, D, lvalue, capturedByInit);
1041  } else if (type->isAnyComplexType()) {
1042    ComplexPairTy complex = EmitComplexExpr(init);
1043    if (capturedByInit)
1044      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1045    StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile());
1046  } else {
1047    // TODO: how can we delay here if D is captured by its initializer?
1048    EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1049                                              AggValueSlot::IsDestructed,
1050                                         AggValueSlot::DoesNotNeedGCBarriers,
1051                                              AggValueSlot::IsNotAliased));
1052  }
1053}
1054
1055/// Enter a destroy cleanup for the given local variable.
1056void CodeGenFunction::emitAutoVarTypeCleanup(
1057                            const CodeGenFunction::AutoVarEmission &emission,
1058                            QualType::DestructionKind dtorKind) {
1059  assert(dtorKind != QualType::DK_none);
1060
1061  // Note that for __block variables, we want to destroy the
1062  // original stack object, not the possibly forwarded object.
1063  llvm::Value *addr = emission.getObjectAddress(*this);
1064
1065  const VarDecl *var = emission.Variable;
1066  QualType type = var->getType();
1067
1068  CleanupKind cleanupKind = NormalAndEHCleanup;
1069  CodeGenFunction::Destroyer *destroyer = 0;
1070
1071  switch (dtorKind) {
1072  case QualType::DK_none:
1073    llvm_unreachable("no cleanup for trivially-destructible variable");
1074
1075  case QualType::DK_cxx_destructor:
1076    // If there's an NRVO flag on the emission, we need a different
1077    // cleanup.
1078    if (emission.NRVOFlag) {
1079      assert(!type->isArrayType());
1080      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1081      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1082                                               emission.NRVOFlag);
1083      return;
1084    }
1085    break;
1086
1087  case QualType::DK_objc_strong_lifetime:
1088    // Suppress cleanups for pseudo-strong variables.
1089    if (var->isARCPseudoStrong()) return;
1090
1091    // Otherwise, consider whether to use an EH cleanup or not.
1092    cleanupKind = getARCCleanupKind();
1093
1094    // Use the imprecise destroyer by default.
1095    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1096      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1097    break;
1098
1099  case QualType::DK_objc_weak_lifetime:
1100    break;
1101  }
1102
1103  // If we haven't chosen a more specific destroyer, use the default.
1104  if (!destroyer) destroyer = &getDestroyer(dtorKind);
1105
1106  // Use an EH cleanup in array destructors iff the destructor itself
1107  // is being pushed as an EH cleanup.
1108  bool useEHCleanup = (cleanupKind & EHCleanup);
1109  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1110                                     useEHCleanup);
1111}
1112
1113void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1114  assert(emission.Variable && "emission was not valid!");
1115
1116  // If this was emitted as a global constant, we're done.
1117  if (emission.wasEmittedAsGlobal()) return;
1118
1119  const VarDecl &D = *emission.Variable;
1120
1121  // Check the type for a cleanup.
1122  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1123    emitAutoVarTypeCleanup(emission, dtorKind);
1124
1125  // In GC mode, honor objc_precise_lifetime.
1126  if (getLangOptions().getGC() != LangOptions::NonGC &&
1127      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1128    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1129  }
1130
1131  // Handle the cleanup attribute.
1132  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1133    const FunctionDecl *FD = CA->getFunctionDecl();
1134
1135    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1136    assert(F && "Could not find function!");
1137
1138    const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
1139    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1140  }
1141
1142  // If this is a block variable, call _Block_object_destroy
1143  // (on the unforwarded address).
1144  if (emission.IsByRef)
1145    enterByrefCleanup(emission);
1146}
1147
1148CodeGenFunction::Destroyer &
1149CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1150  // This is surprisingly compiler-dependent.  GCC 4.2 can't bind
1151  // references to functions directly in returns, and using '*&foo'
1152  // confuses MSVC.  Luckily, the following code pattern works in both.
1153  Destroyer *destroyer = 0;
1154  switch (kind) {
1155  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1156  case QualType::DK_cxx_destructor:
1157    destroyer = &destroyCXXObject;
1158    break;
1159  case QualType::DK_objc_strong_lifetime:
1160    destroyer = &destroyARCStrongPrecise;
1161    break;
1162  case QualType::DK_objc_weak_lifetime:
1163    destroyer = &destroyARCWeak;
1164    break;
1165  }
1166  return *destroyer;
1167}
1168
1169/// pushDestroy - Push the standard destructor for the given type.
1170void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1171                                  llvm::Value *addr, QualType type) {
1172  assert(dtorKind && "cannot push destructor for trivial type");
1173
1174  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1175  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1176              cleanupKind & EHCleanup);
1177}
1178
1179void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1180                                  QualType type, Destroyer &destroyer,
1181                                  bool useEHCleanupForArray) {
1182  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1183                                     destroyer, useEHCleanupForArray);
1184}
1185
1186/// emitDestroy - Immediately perform the destruction of the given
1187/// object.
1188///
1189/// \param addr - the address of the object; a type*
1190/// \param type - the type of the object; if an array type, all
1191///   objects are destroyed in reverse order
1192/// \param destroyer - the function to call to destroy individual
1193///   elements
1194/// \param useEHCleanupForArray - whether an EH cleanup should be
1195///   used when destroying array elements, in case one of the
1196///   destructions throws an exception
1197void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1198                                  Destroyer &destroyer,
1199                                  bool useEHCleanupForArray) {
1200  const ArrayType *arrayType = getContext().getAsArrayType(type);
1201  if (!arrayType)
1202    return destroyer(*this, addr, type);
1203
1204  llvm::Value *begin = addr;
1205  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1206
1207  // Normally we have to check whether the array is zero-length.
1208  bool checkZeroLength = true;
1209
1210  // But if the array length is constant, we can suppress that.
1211  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1212    // ...and if it's constant zero, we can just skip the entire thing.
1213    if (constLength->isZero()) return;
1214    checkZeroLength = false;
1215  }
1216
1217  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1218  emitArrayDestroy(begin, end, type, destroyer,
1219                   checkZeroLength, useEHCleanupForArray);
1220}
1221
1222/// emitArrayDestroy - Destroys all the elements of the given array,
1223/// beginning from last to first.  The array cannot be zero-length.
1224///
1225/// \param begin - a type* denoting the first element of the array
1226/// \param end - a type* denoting one past the end of the array
1227/// \param type - the element type of the array
1228/// \param destroyer - the function to call to destroy elements
1229/// \param useEHCleanup - whether to push an EH cleanup to destroy
1230///   the remaining elements in case the destruction of a single
1231///   element throws
1232void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1233                                       llvm::Value *end,
1234                                       QualType type,
1235                                       Destroyer &destroyer,
1236                                       bool checkZeroLength,
1237                                       bool useEHCleanup) {
1238  assert(!type->isArrayType());
1239
1240  // The basic structure here is a do-while loop, because we don't
1241  // need to check for the zero-element case.
1242  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1243  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1244
1245  if (checkZeroLength) {
1246    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1247                                                "arraydestroy.isempty");
1248    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1249  }
1250
1251  // Enter the loop body, making that address the current address.
1252  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1253  EmitBlock(bodyBB);
1254  llvm::PHINode *elementPast =
1255    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1256  elementPast->addIncoming(end, entryBB);
1257
1258  // Shift the address back by one element.
1259  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1260  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1261                                                   "arraydestroy.element");
1262
1263  if (useEHCleanup)
1264    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1265
1266  // Perform the actual destruction there.
1267  destroyer(*this, element, type);
1268
1269  if (useEHCleanup)
1270    PopCleanupBlock();
1271
1272  // Check whether we've reached the end.
1273  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1274  Builder.CreateCondBr(done, doneBB, bodyBB);
1275  elementPast->addIncoming(element, Builder.GetInsertBlock());
1276
1277  // Done.
1278  EmitBlock(doneBB);
1279}
1280
1281/// Perform partial array destruction as if in an EH cleanup.  Unlike
1282/// emitArrayDestroy, the element type here may still be an array type.
1283static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1284                                    llvm::Value *begin, llvm::Value *end,
1285                                    QualType type,
1286                                    CodeGenFunction::Destroyer &destroyer) {
1287  // If the element type is itself an array, drill down.
1288  unsigned arrayDepth = 0;
1289  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1290    // VLAs don't require a GEP index to walk into.
1291    if (!isa<VariableArrayType>(arrayType))
1292      arrayDepth++;
1293    type = arrayType->getElementType();
1294  }
1295
1296  if (arrayDepth) {
1297    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1298
1299    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1300    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1301    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1302  }
1303
1304  // Destroy the array.  We don't ever need an EH cleanup because we
1305  // assume that we're in an EH cleanup ourselves, so a throwing
1306  // destructor causes an immediate terminate.
1307  CGF.emitArrayDestroy(begin, end, type, destroyer,
1308                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1309}
1310
1311namespace {
1312  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1313  /// array destroy where the end pointer is regularly determined and
1314  /// does not need to be loaded from a local.
1315  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1316    llvm::Value *ArrayBegin;
1317    llvm::Value *ArrayEnd;
1318    QualType ElementType;
1319    CodeGenFunction::Destroyer &Destroyer;
1320  public:
1321    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1322                               QualType elementType,
1323                               CodeGenFunction::Destroyer *destroyer)
1324      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1325        ElementType(elementType), Destroyer(*destroyer) {}
1326
1327    void Emit(CodeGenFunction &CGF, Flags flags) {
1328      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1329                              ElementType, Destroyer);
1330    }
1331  };
1332
1333  /// IrregularPartialArrayDestroy - a cleanup which performs a
1334  /// partial array destroy where the end pointer is irregularly
1335  /// determined and must be loaded from a local.
1336  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1337    llvm::Value *ArrayBegin;
1338    llvm::Value *ArrayEndPointer;
1339    QualType ElementType;
1340    CodeGenFunction::Destroyer &Destroyer;
1341  public:
1342    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1343                                 llvm::Value *arrayEndPointer,
1344                                 QualType elementType,
1345                                 CodeGenFunction::Destroyer *destroyer)
1346      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1347        ElementType(elementType), Destroyer(*destroyer) {}
1348
1349    void Emit(CodeGenFunction &CGF, Flags flags) {
1350      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1351      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1352                              ElementType, Destroyer);
1353    }
1354  };
1355}
1356
1357/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1358/// already-constructed elements of the given array.  The cleanup
1359/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1360///
1361/// \param elementType - the immediate element type of the array;
1362///   possibly still an array type
1363/// \param array - a value of type elementType*
1364/// \param destructionKind - the kind of destruction required
1365/// \param initializedElementCount - a value of type size_t* holding
1366///   the number of successfully-constructed elements
1367void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1368                                                 llvm::Value *arrayEndPointer,
1369                                                       QualType elementType,
1370                                                       Destroyer &destroyer) {
1371  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1372                                                    arrayBegin, arrayEndPointer,
1373                                                    elementType, &destroyer);
1374}
1375
1376/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1377/// already-constructed elements of the given array.  The cleanup
1378/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1379///
1380/// \param elementType - the immediate element type of the array;
1381///   possibly still an array type
1382/// \param array - a value of type elementType*
1383/// \param destructionKind - the kind of destruction required
1384/// \param initializedElementCount - a value of type size_t* holding
1385///   the number of successfully-constructed elements
1386void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1387                                                     llvm::Value *arrayEnd,
1388                                                     QualType elementType,
1389                                                     Destroyer &destroyer) {
1390  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1391                                                  arrayBegin, arrayEnd,
1392                                                  elementType, &destroyer);
1393}
1394
1395namespace {
1396  /// A cleanup to perform a release of an object at the end of a
1397  /// function.  This is used to balance out the incoming +1 of a
1398  /// ns_consumed argument when we can't reasonably do that just by
1399  /// not doing the initial retain for a __block argument.
1400  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1401    ConsumeARCParameter(llvm::Value *param) : Param(param) {}
1402
1403    llvm::Value *Param;
1404
1405    void Emit(CodeGenFunction &CGF, Flags flags) {
1406      CGF.EmitARCRelease(Param, /*precise*/ false);
1407    }
1408  };
1409}
1410
1411/// Emit an alloca (or GlobalValue depending on target)
1412/// for the specified parameter and set up LocalDeclMap.
1413void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1414                                   unsigned ArgNo) {
1415  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1416  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1417         "Invalid argument to EmitParmDecl");
1418
1419  Arg->setName(D.getName());
1420
1421  // Use better IR generation for certain implicit parameters.
1422  if (isa<ImplicitParamDecl>(D)) {
1423    // The only implicit argument a block has is its literal.
1424    if (BlockInfo) {
1425      LocalDeclMap[&D] = Arg;
1426
1427      if (CGDebugInfo *DI = getDebugInfo()) {
1428        DI->setLocation(D.getLocation());
1429        DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
1430      }
1431
1432      return;
1433    }
1434  }
1435
1436  QualType Ty = D.getType();
1437
1438  llvm::Value *DeclPtr;
1439  // If this is an aggregate or variable sized value, reuse the input pointer.
1440  if (!Ty->isConstantSizeType() ||
1441      CodeGenFunction::hasAggregateLLVMType(Ty)) {
1442    DeclPtr = Arg;
1443  } else {
1444    // Otherwise, create a temporary to hold the value.
1445    llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1446                                               D.getName() + ".addr");
1447    Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
1448    DeclPtr = Alloc;
1449
1450    bool doStore = true;
1451
1452    Qualifiers qs = Ty.getQualifiers();
1453
1454    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1455      // We honor __attribute__((ns_consumed)) for types with lifetime.
1456      // For __strong, it's handled by just skipping the initial retain;
1457      // otherwise we have to balance out the initial +1 with an extra
1458      // cleanup to do the release at the end of the function.
1459      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1460
1461      // 'self' is always formally __strong, but if this is not an
1462      // init method then we don't want to retain it.
1463      if (D.isARCPseudoStrong()) {
1464        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1465        assert(&D == method->getSelfDecl());
1466        assert(lt == Qualifiers::OCL_Strong);
1467        assert(qs.hasConst());
1468        assert(method->getMethodFamily() != OMF_init);
1469        (void) method;
1470        lt = Qualifiers::OCL_ExplicitNone;
1471      }
1472
1473      if (lt == Qualifiers::OCL_Strong) {
1474        if (!isConsumed)
1475          // Don't use objc_retainBlock for block pointers, because we
1476          // don't want to Block_copy something just because we got it
1477          // as a parameter.
1478          Arg = EmitARCRetainNonBlock(Arg);
1479      } else {
1480        // Push the cleanup for a consumed parameter.
1481        if (isConsumed)
1482          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg);
1483
1484        if (lt == Qualifiers::OCL_Weak) {
1485          EmitARCInitWeak(DeclPtr, Arg);
1486          doStore = false; // The weak init is a store, no need to do two
1487        }
1488      }
1489
1490      // Enter the cleanup scope.
1491      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1492    }
1493
1494    // Store the initial value into the alloca.
1495    if (doStore) {
1496      LValue lv = MakeAddrLValue(DeclPtr, Ty,
1497                                 getContext().getDeclAlign(&D).getQuantity());
1498      EmitStoreOfScalar(Arg, lv);
1499    }
1500  }
1501
1502  llvm::Value *&DMEntry = LocalDeclMap[&D];
1503  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
1504  DMEntry = DeclPtr;
1505
1506  // Emit debug info for param declaration.
1507  if (CGDebugInfo *DI = getDebugInfo())
1508    DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1509
1510  if (D.hasAttr<AnnotateAttr>())
1511      EmitVarAnnotations(&D, DeclPtr);
1512}
1513