CGDecl.cpp revision fd00eecad6fa5400cf37269d84361a0551d0e6d3 
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::FileScopeAsm:
69  case Decl::Friend:
70  case Decl::FriendTemplate:
71  case Decl::Block:
72  case Decl::ClassScopeFunctionSpecialization:
73    llvm_unreachable("Declaration should not be in declstmts!");
74  case Decl::Function:  // void X();
75  case Decl::Record:    // struct/union/class X;
76  case Decl::Enum:      // enum X;
77  case Decl::EnumConstant: // enum ? { X = ? }
78  case Decl::CXXRecord: // struct/union/class X; [C++]
79  case Decl::Using:          // using X; [C++]
80  case Decl::UsingShadow:
81  case Decl::UsingDirective: // using namespace X; [C++]
82  case Decl::NamespaceAlias:
83  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
84  case Decl::Label:        // __label__ x;
85  case Decl::Import:
86    // None of these decls require codegen support.
87    return;
88
89  case Decl::Var: {
90    const VarDecl &VD = cast<VarDecl>(D);
91    assert(VD.isLocalVarDecl() &&
92           "Should not see file-scope variables inside a function!");
93    return EmitVarDecl(VD);
94  }
95
96  case Decl::Typedef:      // typedef int X;
97  case Decl::TypeAlias: {  // using X = int; [C++0x]
98    const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
99    QualType Ty = TD.getUnderlyingType();
100
101    if (Ty->isVariablyModifiedType())
102      EmitVariablyModifiedType(Ty);
103  }
104  }
105}
106
107/// EmitVarDecl - This method handles emission of any variable declaration
108/// inside a function, including static vars etc.
109void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
110  switch (D.getStorageClass()) {
111  case SC_None:
112  case SC_Auto:
113  case SC_Register:
114    return EmitAutoVarDecl(D);
115  case SC_Static: {
116    llvm::GlobalValue::LinkageTypes Linkage =
117      llvm::GlobalValue::InternalLinkage;
118
119    // If the function definition has some sort of weak linkage, its
120    // static variables should also be weak so that they get properly
121    // uniqued.  We can't do this in C, though, because there's no
122    // standard way to agree on which variables are the same (i.e.
123    // there's no mangling).
124    if (getContext().getLangOpts().CPlusPlus)
125      if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
126        Linkage = CurFn->getLinkage();
127
128    return EmitStaticVarDecl(D, Linkage);
129  }
130  case SC_Extern:
131  case SC_PrivateExtern:
132    // Don't emit it now, allow it to be emitted lazily on its first use.
133    return;
134  case SC_OpenCLWorkGroupLocal:
135    return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
136  }
137
138  llvm_unreachable("Unknown storage class");
139}
140
141static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
142                                     const char *Separator) {
143  CodeGenModule &CGM = CGF.CGM;
144  if (CGF.getContext().getLangOpts().CPlusPlus) {
145    StringRef Name = CGM.getMangledName(&D);
146    return Name.str();
147  }
148
149  std::string ContextName;
150  if (!CGF.CurFuncDecl) {
151    // Better be in a block declared in global scope.
152    const NamedDecl *ND = cast<NamedDecl>(&D);
153    const DeclContext *DC = ND->getDeclContext();
154    if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
155      MangleBuffer Name;
156      CGM.getBlockMangledName(GlobalDecl(), Name, BD);
157      ContextName = Name.getString();
158    }
159    else
160      llvm_unreachable("Unknown context for block static var decl");
161  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
162    StringRef Name = CGM.getMangledName(FD);
163    ContextName = Name.str();
164  } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
165    ContextName = CGF.CurFn->getName();
166  else
167    llvm_unreachable("Unknown context for static var decl");
168
169  return ContextName + Separator + D.getNameAsString();
170}
171
172llvm::GlobalVariable *
173CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
174                                     const char *Separator,
175                                     llvm::GlobalValue::LinkageTypes Linkage) {
176  QualType Ty = D.getType();
177  assert(Ty->isConstantSizeType() && "VLAs can't be static");
178
179  // Use the label if the variable is renamed with the asm-label extension.
180  std::string Name;
181  if (D.hasAttr<AsmLabelAttr>())
182    Name = CGM.getMangledName(&D);
183  else
184    Name = GetStaticDeclName(*this, D, Separator);
185
186  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
187  llvm::GlobalVariable *GV =
188    new llvm::GlobalVariable(CGM.getModule(), LTy,
189                             Ty.isConstant(getContext()), Linkage,
190                             CGM.EmitNullConstant(D.getType()), Name, 0,
191                             D.isThreadSpecified(),
192                             CGM.getContext().getTargetAddressSpace(Ty));
193  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
194  if (Linkage != llvm::GlobalValue::InternalLinkage)
195    GV->setVisibility(CurFn->getVisibility());
196  return GV;
197}
198
199/// hasNontrivialDestruction - Determine whether a type's destruction is
200/// non-trivial. If so, and the variable uses static initialization, we must
201/// register its destructor to run on exit.
202static bool hasNontrivialDestruction(QualType T) {
203  CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
204  return RD && !RD->hasTrivialDestructor();
205}
206
207/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
208/// global variable that has already been created for it.  If the initializer
209/// has a different type than GV does, this may free GV and return a different
210/// one.  Otherwise it just returns GV.
211llvm::GlobalVariable *
212CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
213                                               llvm::GlobalVariable *GV) {
214  llvm::Constant *Init = CGM.EmitConstantInit(D, this);
215
216  // If constant emission failed, then this should be a C++ static
217  // initializer.
218  if (!Init) {
219    if (!getContext().getLangOpts().CPlusPlus)
220      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
221    else if (Builder.GetInsertBlock()) {
222      // Since we have a static initializer, this global variable can't
223      // be constant.
224      GV->setConstant(false);
225
226      EmitCXXGuardedInit(D, GV, /*PerformInit*/true);
227    }
228    return GV;
229  }
230
231  // The initializer may differ in type from the global. Rewrite
232  // the global to match the initializer.  (We have to do this
233  // because some types, like unions, can't be completely represented
234  // in the LLVM type system.)
235  if (GV->getType()->getElementType() != Init->getType()) {
236    llvm::GlobalVariable *OldGV = GV;
237
238    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
239                                  OldGV->isConstant(),
240                                  OldGV->getLinkage(), Init, "",
241                                  /*InsertBefore*/ OldGV,
242                                  D.isThreadSpecified(),
243                           CGM.getContext().getTargetAddressSpace(D.getType()));
244    GV->setVisibility(OldGV->getVisibility());
245
246    // Steal the name of the old global
247    GV->takeName(OldGV);
248
249    // Replace all uses of the old global with the new global
250    llvm::Constant *NewPtrForOldDecl =
251    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
252    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
253
254    // Erase the old global, since it is no longer used.
255    OldGV->eraseFromParent();
256  }
257
258  GV->setConstant(CGM.isTypeConstant(D.getType(), true));
259  GV->setInitializer(Init);
260
261  if (hasNontrivialDestruction(D.getType())) {
262    // We have a constant initializer, but a nontrivial destructor. We still
263    // need to perform a guarded "initialization" in order to register the
264    // destructor.
265    EmitCXXGuardedInit(D, GV, /*PerformInit*/false);
266  }
267
268  return GV;
269}
270
271void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
272                                      llvm::GlobalValue::LinkageTypes Linkage) {
273  llvm::Value *&DMEntry = LocalDeclMap[&D];
274  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
275
276  // Check to see if we already have a global variable for this
277  // declaration.  This can happen when double-emitting function
278  // bodies, e.g. with complete and base constructors.
279  llvm::Constant *addr =
280    CGM.getStaticLocalDeclAddress(&D);
281
282  llvm::GlobalVariable *var;
283  if (addr) {
284    var = cast<llvm::GlobalVariable>(addr->stripPointerCasts());
285  } else {
286    addr = var = CreateStaticVarDecl(D, ".", Linkage);
287  }
288
289  // Store into LocalDeclMap before generating initializer to handle
290  // circular references.
291  DMEntry = addr;
292  CGM.setStaticLocalDeclAddress(&D, addr);
293
294  // We can't have a VLA here, but we can have a pointer to a VLA,
295  // even though that doesn't really make any sense.
296  // Make sure to evaluate VLA bounds now so that we have them for later.
297  if (D.getType()->isVariablyModifiedType())
298    EmitVariablyModifiedType(D.getType());
299
300  // Save the type in case adding the initializer forces a type change.
301  llvm::Type *expectedType = addr->getType();
302
303  // If this value has an initializer, emit it.
304  if (D.getInit())
305    var = AddInitializerToStaticVarDecl(D, var);
306
307  var->setAlignment(getContext().getDeclAlign(&D).getQuantity());
308
309  if (D.hasAttr<AnnotateAttr>())
310    CGM.AddGlobalAnnotations(&D, var);
311
312  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
313    var->setSection(SA->getName());
314
315  if (D.hasAttr<UsedAttr>())
316    CGM.AddUsedGlobal(var);
317
318  // We may have to cast the constant because of the initializer
319  // mismatch above.
320  //
321  // FIXME: It is really dangerous to store this in the map; if anyone
322  // RAUW's the GV uses of this constant will be invalid.
323  llvm::Constant *castedAddr = llvm::ConstantExpr::getBitCast(var, expectedType);
324  DMEntry = castedAddr;
325  CGM.setStaticLocalDeclAddress(&D, castedAddr);
326
327  // Emit global variable debug descriptor for static vars.
328  CGDebugInfo *DI = getDebugInfo();
329  if (DI &&
330      CGM.getCodeGenOpts().DebugInfo >= CodeGenOptions::LimitedDebugInfo) {
331    DI->setLocation(D.getLocation());
332    DI->EmitGlobalVariable(var, &D);
333  }
334}
335
336namespace {
337  struct DestroyObject : EHScopeStack::Cleanup {
338    DestroyObject(llvm::Value *addr, QualType type,
339                  CodeGenFunction::Destroyer *destroyer,
340                  bool useEHCleanupForArray)
341      : addr(addr), type(type), destroyer(destroyer),
342        useEHCleanupForArray(useEHCleanupForArray) {}
343
344    llvm::Value *addr;
345    QualType type;
346    CodeGenFunction::Destroyer *destroyer;
347    bool useEHCleanupForArray;
348
349    void Emit(CodeGenFunction &CGF, Flags flags) {
350      // Don't use an EH cleanup recursively from an EH cleanup.
351      bool useEHCleanupForArray =
352        flags.isForNormalCleanup() && this->useEHCleanupForArray;
353
354      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
355    }
356  };
357
358  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
359    DestroyNRVOVariable(llvm::Value *addr,
360                        const CXXDestructorDecl *Dtor,
361                        llvm::Value *NRVOFlag)
362      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
363
364    const CXXDestructorDecl *Dtor;
365    llvm::Value *NRVOFlag;
366    llvm::Value *Loc;
367
368    void Emit(CodeGenFunction &CGF, Flags flags) {
369      // Along the exceptions path we always execute the dtor.
370      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
371
372      llvm::BasicBlock *SkipDtorBB = 0;
373      if (NRVO) {
374        // If we exited via NRVO, we skip the destructor call.
375        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
376        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
377        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
378        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
379        CGF.EmitBlock(RunDtorBB);
380      }
381
382      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
383                                /*ForVirtualBase=*/false, Loc);
384
385      if (NRVO) CGF.EmitBlock(SkipDtorBB);
386    }
387  };
388
389  struct CallStackRestore : EHScopeStack::Cleanup {
390    llvm::Value *Stack;
391    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
392    void Emit(CodeGenFunction &CGF, Flags flags) {
393      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
394      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
395      CGF.Builder.CreateCall(F, V);
396    }
397  };
398
399  struct ExtendGCLifetime : EHScopeStack::Cleanup {
400    const VarDecl &Var;
401    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
402
403    void Emit(CodeGenFunction &CGF, Flags flags) {
404      // Compute the address of the local variable, in case it's a
405      // byref or something.
406      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
407                      Var.getType(), VK_LValue, SourceLocation());
408      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
409      CGF.EmitExtendGCLifetime(value);
410    }
411  };
412
413  struct CallCleanupFunction : EHScopeStack::Cleanup {
414    llvm::Constant *CleanupFn;
415    const CGFunctionInfo &FnInfo;
416    const VarDecl &Var;
417
418    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
419                        const VarDecl *Var)
420      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
421
422    void Emit(CodeGenFunction &CGF, Flags flags) {
423      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
424                      Var.getType(), VK_LValue, SourceLocation());
425      // Compute the address of the local variable, in case it's a byref
426      // or something.
427      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
428
429      // In some cases, the type of the function argument will be different from
430      // the type of the pointer. An example of this is
431      // void f(void* arg);
432      // __attribute__((cleanup(f))) void *g;
433      //
434      // To fix this we insert a bitcast here.
435      QualType ArgTy = FnInfo.arg_begin()->type;
436      llvm::Value *Arg =
437        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
438
439      CallArgList Args;
440      Args.add(RValue::get(Arg),
441               CGF.getContext().getPointerType(Var.getType()));
442      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
443    }
444  };
445}
446
447/// EmitAutoVarWithLifetime - Does the setup required for an automatic
448/// variable with lifetime.
449static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
450                                    llvm::Value *addr,
451                                    Qualifiers::ObjCLifetime lifetime) {
452  switch (lifetime) {
453  case Qualifiers::OCL_None:
454    llvm_unreachable("present but none");
455
456  case Qualifiers::OCL_ExplicitNone:
457    // nothing to do
458    break;
459
460  case Qualifiers::OCL_Strong: {
461    CodeGenFunction::Destroyer *destroyer =
462      (var.hasAttr<ObjCPreciseLifetimeAttr>()
463       ? CodeGenFunction::destroyARCStrongPrecise
464       : CodeGenFunction::destroyARCStrongImprecise);
465
466    CleanupKind cleanupKind = CGF.getARCCleanupKind();
467    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
468                    cleanupKind & EHCleanup);
469    break;
470  }
471  case Qualifiers::OCL_Autoreleasing:
472    // nothing to do
473    break;
474
475  case Qualifiers::OCL_Weak:
476    // __weak objects always get EH cleanups; otherwise, exceptions
477    // could cause really nasty crashes instead of mere leaks.
478    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
479                    CodeGenFunction::destroyARCWeak,
480                    /*useEHCleanup*/ true);
481    break;
482  }
483}
484
485static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
486  if (const Expr *e = dyn_cast<Expr>(s)) {
487    // Skip the most common kinds of expressions that make
488    // hierarchy-walking expensive.
489    s = e = e->IgnoreParenCasts();
490
491    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
492      return (ref->getDecl() == &var);
493  }
494
495  for (Stmt::const_child_range children = s->children(); children; ++children)
496    // children might be null; as in missing decl or conditional of an if-stmt.
497    if ((*children) && isAccessedBy(var, *children))
498      return true;
499
500  return false;
501}
502
503static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
504  if (!decl) return false;
505  if (!isa<VarDecl>(decl)) return false;
506  const VarDecl *var = cast<VarDecl>(decl);
507  return isAccessedBy(*var, e);
508}
509
510static void drillIntoBlockVariable(CodeGenFunction &CGF,
511                                   LValue &lvalue,
512                                   const VarDecl *var) {
513  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
514}
515
516void CodeGenFunction::EmitScalarInit(const Expr *init,
517                                     const ValueDecl *D,
518                                     LValue lvalue,
519                                     bool capturedByInit) {
520  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
521  if (!lifetime) {
522    llvm::Value *value = EmitScalarExpr(init);
523    if (capturedByInit)
524      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
525    EmitStoreThroughLValue(RValue::get(value), lvalue, true);
526    return;
527  }
528
529  // If we're emitting a value with lifetime, we have to do the
530  // initialization *before* we leave the cleanup scopes.
531  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
532    enterFullExpression(ewc);
533    init = ewc->getSubExpr();
534  }
535  CodeGenFunction::RunCleanupsScope Scope(*this);
536
537  // We have to maintain the illusion that the variable is
538  // zero-initialized.  If the variable might be accessed in its
539  // initializer, zero-initialize before running the initializer, then
540  // actually perform the initialization with an assign.
541  bool accessedByInit = false;
542  if (lifetime != Qualifiers::OCL_ExplicitNone)
543    accessedByInit = (capturedByInit || isAccessedBy(D, init));
544  if (accessedByInit) {
545    LValue tempLV = lvalue;
546    // Drill down to the __block object if necessary.
547    if (capturedByInit) {
548      // We can use a simple GEP for this because it can't have been
549      // moved yet.
550      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
551                                   getByRefValueLLVMField(cast<VarDecl>(D))));
552    }
553
554    llvm::PointerType *ty
555      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
556    ty = cast<llvm::PointerType>(ty->getElementType());
557
558    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
559
560    // If __weak, we want to use a barrier under certain conditions.
561    if (lifetime == Qualifiers::OCL_Weak)
562      EmitARCInitWeak(tempLV.getAddress(), zero);
563
564    // Otherwise just do a simple store.
565    else
566      EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true);
567  }
568
569  // Emit the initializer.
570  llvm::Value *value = 0;
571
572  switch (lifetime) {
573  case Qualifiers::OCL_None:
574    llvm_unreachable("present but none");
575
576  case Qualifiers::OCL_ExplicitNone:
577    // nothing to do
578    value = EmitScalarExpr(init);
579    break;
580
581  case Qualifiers::OCL_Strong: {
582    value = EmitARCRetainScalarExpr(init);
583    break;
584  }
585
586  case Qualifiers::OCL_Weak: {
587    // No way to optimize a producing initializer into this.  It's not
588    // worth optimizing for, because the value will immediately
589    // disappear in the common case.
590    value = EmitScalarExpr(init);
591
592    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
593    if (accessedByInit)
594      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
595    else
596      EmitARCInitWeak(lvalue.getAddress(), value);
597    return;
598  }
599
600  case Qualifiers::OCL_Autoreleasing:
601    value = EmitARCRetainAutoreleaseScalarExpr(init);
602    break;
603  }
604
605  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
606
607  // If the variable might have been accessed by its initializer, we
608  // might have to initialize with a barrier.  We have to do this for
609  // both __weak and __strong, but __weak got filtered out above.
610  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
611    llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
612    EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
613    EmitARCRelease(oldValue, /*precise*/ false);
614    return;
615  }
616
617  EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
618}
619
620/// EmitScalarInit - Initialize the given lvalue with the given object.
621void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
622  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
623  if (!lifetime)
624    return EmitStoreThroughLValue(RValue::get(init), lvalue, true);
625
626  switch (lifetime) {
627  case Qualifiers::OCL_None:
628    llvm_unreachable("present but none");
629
630  case Qualifiers::OCL_ExplicitNone:
631    // nothing to do
632    break;
633
634  case Qualifiers::OCL_Strong:
635    init = EmitARCRetain(lvalue.getType(), init);
636    break;
637
638  case Qualifiers::OCL_Weak:
639    // Initialize and then skip the primitive store.
640    EmitARCInitWeak(lvalue.getAddress(), init);
641    return;
642
643  case Qualifiers::OCL_Autoreleasing:
644    init = EmitARCRetainAutorelease(lvalue.getType(), init);
645    break;
646  }
647
648  EmitStoreOfScalar(init, lvalue, /* isInitialization */ true);
649}
650
651/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
652/// non-zero parts of the specified initializer with equal or fewer than
653/// NumStores scalar stores.
654static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
655                                                unsigned &NumStores) {
656  // Zero and Undef never requires any extra stores.
657  if (isa<llvm::ConstantAggregateZero>(Init) ||
658      isa<llvm::ConstantPointerNull>(Init) ||
659      isa<llvm::UndefValue>(Init))
660    return true;
661  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
662      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
663      isa<llvm::ConstantExpr>(Init))
664    return Init->isNullValue() || NumStores--;
665
666  // See if we can emit each element.
667  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
668    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
669      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
670      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
671        return false;
672    }
673    return true;
674  }
675
676  if (llvm::ConstantDataSequential *CDS =
677        dyn_cast<llvm::ConstantDataSequential>(Init)) {
678    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
679      llvm::Constant *Elt = CDS->getElementAsConstant(i);
680      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
681        return false;
682    }
683    return true;
684  }
685
686  // Anything else is hard and scary.
687  return false;
688}
689
690/// emitStoresForInitAfterMemset - For inits that
691/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
692/// stores that would be required.
693static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
694                                         bool isVolatile, CGBuilderTy &Builder) {
695  // Zero doesn't require a store.
696  if (Init->isNullValue() || isa<llvm::UndefValue>(Init))
697    return;
698
699  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
700      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
701      isa<llvm::ConstantExpr>(Init)) {
702    Builder.CreateStore(Init, Loc, isVolatile);
703    return;
704  }
705
706  if (llvm::ConstantDataSequential *CDS =
707        dyn_cast<llvm::ConstantDataSequential>(Init)) {
708    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
709      llvm::Constant *Elt = CDS->getElementAsConstant(i);
710
711      // Get a pointer to the element and emit it.
712      emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
713                                   isVolatile, Builder);
714    }
715    return;
716  }
717
718  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
719         "Unknown value type!");
720
721  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
722    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
723    // Get a pointer to the element and emit it.
724    emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
725                                 isVolatile, Builder);
726  }
727}
728
729
730/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
731/// plus some stores to initialize a local variable instead of using a memcpy
732/// from a constant global.  It is beneficial to use memset if the global is all
733/// zeros, or mostly zeros and large.
734static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
735                                                  uint64_t GlobalSize) {
736  // If a global is all zeros, always use a memset.
737  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
738
739
740  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
741  // do it if it will require 6 or fewer scalar stores.
742  // TODO: Should budget depends on the size?  Avoiding a large global warrants
743  // plopping in more stores.
744  unsigned StoreBudget = 6;
745  uint64_t SizeLimit = 32;
746
747  return GlobalSize > SizeLimit &&
748         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
749}
750
751
752/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
753/// variable declaration with auto, register, or no storage class specifier.
754/// These turn into simple stack objects, or GlobalValues depending on target.
755void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
756  AutoVarEmission emission = EmitAutoVarAlloca(D);
757  EmitAutoVarInit(emission);
758  EmitAutoVarCleanups(emission);
759}
760
761/// EmitAutoVarAlloca - Emit the alloca and debug information for a
762/// local variable.  Does not emit initalization or destruction.
763CodeGenFunction::AutoVarEmission
764CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
765  QualType Ty = D.getType();
766
767  AutoVarEmission emission(D);
768
769  bool isByRef = D.hasAttr<BlocksAttr>();
770  emission.IsByRef = isByRef;
771
772  CharUnits alignment = getContext().getDeclAlign(&D);
773  emission.Alignment = alignment;
774
775  // If the type is variably-modified, emit all the VLA sizes for it.
776  if (Ty->isVariablyModifiedType())
777    EmitVariablyModifiedType(Ty);
778
779  llvm::Value *DeclPtr;
780  if (Ty->isConstantSizeType()) {
781    if (!Target.useGlobalsForAutomaticVariables()) {
782      bool NRVO = getContext().getLangOpts().ElideConstructors &&
783                  D.isNRVOVariable();
784
785      // If this value is a POD array or struct with a statically
786      // determinable constant initializer, there are optimizations we can do.
787      //
788      // TODO: We should constant-evaluate the initializer of any variable,
789      // as long as it is initialized by a constant expression. Currently,
790      // isConstantInitializer produces wrong answers for structs with
791      // reference or bitfield members, and a few other cases, and checking
792      // for POD-ness protects us from some of these.
793      if (D.getInit() &&
794          (Ty->isArrayType() || Ty->isRecordType()) &&
795          (Ty.isPODType(getContext()) ||
796           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
797          D.getInit()->isConstantInitializer(getContext(), false)) {
798
799        // If the variable's a const type, and it's neither an NRVO
800        // candidate nor a __block variable and has no mutable members,
801        // emit it as a global instead.
802        if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef &&
803            CGM.isTypeConstant(Ty, true)) {
804          EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
805
806          emission.Address = 0; // signal this condition to later callbacks
807          assert(emission.wasEmittedAsGlobal());
808          return emission;
809        }
810
811        // Otherwise, tell the initialization code that we're in this case.
812        emission.IsConstantAggregate = true;
813      }
814
815      // A normal fixed sized variable becomes an alloca in the entry block,
816      // unless it's an NRVO variable.
817      llvm::Type *LTy = ConvertTypeForMem(Ty);
818
819      if (NRVO) {
820        // The named return value optimization: allocate this variable in the
821        // return slot, so that we can elide the copy when returning this
822        // variable (C++0x [class.copy]p34).
823        DeclPtr = ReturnValue;
824
825        if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
826          if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
827            // Create a flag that is used to indicate when the NRVO was applied
828            // to this variable. Set it to zero to indicate that NRVO was not
829            // applied.
830            llvm::Value *Zero = Builder.getFalse();
831            llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
832            EnsureInsertPoint();
833            Builder.CreateStore(Zero, NRVOFlag);
834
835            // Record the NRVO flag for this variable.
836            NRVOFlags[&D] = NRVOFlag;
837            emission.NRVOFlag = NRVOFlag;
838          }
839        }
840      } else {
841        if (isByRef)
842          LTy = BuildByRefType(&D);
843
844        llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
845        Alloc->setName(D.getName());
846
847        CharUnits allocaAlignment = alignment;
848        if (isByRef)
849          allocaAlignment = std::max(allocaAlignment,
850              getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
851        Alloc->setAlignment(allocaAlignment.getQuantity());
852        DeclPtr = Alloc;
853      }
854    } else {
855      // Targets that don't support recursion emit locals as globals.
856      const char *Class =
857        D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
858      DeclPtr = CreateStaticVarDecl(D, Class,
859                                    llvm::GlobalValue::InternalLinkage);
860    }
861  } else {
862    EnsureInsertPoint();
863
864    if (!DidCallStackSave) {
865      // Save the stack.
866      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
867
868      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
869      llvm::Value *V = Builder.CreateCall(F);
870
871      Builder.CreateStore(V, Stack);
872
873      DidCallStackSave = true;
874
875      // Push a cleanup block and restore the stack there.
876      // FIXME: in general circumstances, this should be an EH cleanup.
877      EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
878    }
879
880    llvm::Value *elementCount;
881    QualType elementType;
882    llvm::tie(elementCount, elementType) = getVLASize(Ty);
883
884    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
885
886    // Allocate memory for the array.
887    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
888    vla->setAlignment(alignment.getQuantity());
889
890    DeclPtr = vla;
891  }
892
893  llvm::Value *&DMEntry = LocalDeclMap[&D];
894  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
895  DMEntry = DeclPtr;
896  emission.Address = DeclPtr;
897
898  // Emit debug info for local var declaration.
899  if (HaveInsertPoint())
900    if (CGDebugInfo *DI = getDebugInfo()) {
901      if (CGM.getCodeGenOpts().DebugInfo >= CodeGenOptions::LimitedDebugInfo) {
902        DI->setLocation(D.getLocation());
903        if (Target.useGlobalsForAutomaticVariables()) {
904          DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr),
905                                 &D);
906        } else
907          DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
908      }
909    }
910
911  if (D.hasAttr<AnnotateAttr>())
912      EmitVarAnnotations(&D, emission.Address);
913
914  return emission;
915}
916
917/// Determines whether the given __block variable is potentially
918/// captured by the given expression.
919static bool isCapturedBy(const VarDecl &var, const Expr *e) {
920  // Skip the most common kinds of expressions that make
921  // hierarchy-walking expensive.
922  e = e->IgnoreParenCasts();
923
924  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
925    const BlockDecl *block = be->getBlockDecl();
926    for (BlockDecl::capture_const_iterator i = block->capture_begin(),
927           e = block->capture_end(); i != e; ++i) {
928      if (i->getVariable() == &var)
929        return true;
930    }
931
932    // No need to walk into the subexpressions.
933    return false;
934  }
935
936  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
937    const CompoundStmt *CS = SE->getSubStmt();
938    for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
939	   BE = CS->body_end(); BI != BE; ++BI)
940      if (Expr *E = dyn_cast<Expr>((*BI))) {
941        if (isCapturedBy(var, E))
942            return true;
943      }
944      else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) {
945          // special case declarations
946          for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
947               I != E; ++I) {
948              if (VarDecl *VD = dyn_cast<VarDecl>((*I))) {
949                Expr *Init = VD->getInit();
950                if (Init && isCapturedBy(var, Init))
951                  return true;
952              }
953          }
954      }
955      else
956        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
957        // Later, provide code to poke into statements for capture analysis.
958        return true;
959    return false;
960  }
961
962  for (Stmt::const_child_range children = e->children(); children; ++children)
963    if (isCapturedBy(var, cast<Expr>(*children)))
964      return true;
965
966  return false;
967}
968
969/// \brief Determine whether the given initializer is trivial in the sense
970/// that it requires no code to be generated.
971static bool isTrivialInitializer(const Expr *Init) {
972  if (!Init)
973    return true;
974
975  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
976    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
977      if (Constructor->isTrivial() &&
978          Constructor->isDefaultConstructor() &&
979          !Construct->requiresZeroInitialization())
980        return true;
981
982  return false;
983}
984void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
985  assert(emission.Variable && "emission was not valid!");
986
987  // If this was emitted as a global constant, we're done.
988  if (emission.wasEmittedAsGlobal()) return;
989
990  const VarDecl &D = *emission.Variable;
991  QualType type = D.getType();
992
993  // If this local has an initializer, emit it now.
994  const Expr *Init = D.getInit();
995
996  // If we are at an unreachable point, we don't need to emit the initializer
997  // unless it contains a label.
998  if (!HaveInsertPoint()) {
999    if (!Init || !ContainsLabel(Init)) return;
1000    EnsureInsertPoint();
1001  }
1002
1003  // Initialize the structure of a __block variable.
1004  if (emission.IsByRef)
1005    emitByrefStructureInit(emission);
1006
1007  if (isTrivialInitializer(Init))
1008    return;
1009
1010  CharUnits alignment = emission.Alignment;
1011
1012  // Check whether this is a byref variable that's potentially
1013  // captured and moved by its own initializer.  If so, we'll need to
1014  // emit the initializer first, then copy into the variable.
1015  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
1016
1017  llvm::Value *Loc =
1018    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
1019
1020  llvm::Constant *constant = 0;
1021  if (emission.IsConstantAggregate) {
1022    assert(!capturedByInit && "constant init contains a capturing block?");
1023    constant = CGM.EmitConstantInit(D, this);
1024  }
1025
1026  if (!constant) {
1027    LValue lv = MakeAddrLValue(Loc, type, alignment);
1028    lv.setNonGC(true);
1029    return EmitExprAsInit(Init, &D, lv, capturedByInit);
1030  }
1031
1032  // If this is a simple aggregate initialization, we can optimize it
1033  // in various ways.
1034  bool isVolatile = type.isVolatileQualified();
1035
1036  llvm::Value *SizeVal =
1037    llvm::ConstantInt::get(IntPtrTy,
1038                           getContext().getTypeSizeInChars(type).getQuantity());
1039
1040  llvm::Type *BP = Int8PtrTy;
1041  if (Loc->getType() != BP)
1042    Loc = Builder.CreateBitCast(Loc, BP);
1043
1044  // If the initializer is all or mostly zeros, codegen with memset then do
1045  // a few stores afterward.
1046  if (shouldUseMemSetPlusStoresToInitialize(constant,
1047                CGM.getTargetData().getTypeAllocSize(constant->getType()))) {
1048    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
1049                         alignment.getQuantity(), isVolatile);
1050    if (!constant->isNullValue()) {
1051      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
1052      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
1053    }
1054  } else {
1055    // Otherwise, create a temporary global with the initializer then
1056    // memcpy from the global to the alloca.
1057    std::string Name = GetStaticDeclName(*this, D, ".");
1058    llvm::GlobalVariable *GV =
1059      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1060                               llvm::GlobalValue::PrivateLinkage,
1061                               constant, Name, 0, false, 0);
1062    GV->setAlignment(alignment.getQuantity());
1063    GV->setUnnamedAddr(true);
1064
1065    llvm::Value *SrcPtr = GV;
1066    if (SrcPtr->getType() != BP)
1067      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1068
1069    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1070                         isVolatile);
1071  }
1072}
1073
1074/// Emit an expression as an initializer for a variable at the given
1075/// location.  The expression is not necessarily the normal
1076/// initializer for the variable, and the address is not necessarily
1077/// its normal location.
1078///
1079/// \param init the initializing expression
1080/// \param var the variable to act as if we're initializing
1081/// \param loc the address to initialize; its type is a pointer
1082///   to the LLVM mapping of the variable's type
1083/// \param alignment the alignment of the address
1084/// \param capturedByInit true if the variable is a __block variable
1085///   whose address is potentially changed by the initializer
1086void CodeGenFunction::EmitExprAsInit(const Expr *init,
1087                                     const ValueDecl *D,
1088                                     LValue lvalue,
1089                                     bool capturedByInit) {
1090  QualType type = D->getType();
1091
1092  if (type->isReferenceType()) {
1093    RValue rvalue = EmitReferenceBindingToExpr(init, D);
1094    if (capturedByInit)
1095      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1096    EmitStoreThroughLValue(rvalue, lvalue, true);
1097  } else if (!hasAggregateLLVMType(type)) {
1098    EmitScalarInit(init, D, lvalue, capturedByInit);
1099  } else if (type->isAnyComplexType()) {
1100    ComplexPairTy complex = EmitComplexExpr(init);
1101    if (capturedByInit)
1102      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1103    StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile());
1104  } else {
1105    // TODO: how can we delay here if D is captured by its initializer?
1106    EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1107                                              AggValueSlot::IsDestructed,
1108                                         AggValueSlot::DoesNotNeedGCBarriers,
1109                                              AggValueSlot::IsNotAliased));
1110    MaybeEmitStdInitializerListCleanup(lvalue.getAddress(), init);
1111  }
1112}
1113
1114/// Enter a destroy cleanup for the given local variable.
1115void CodeGenFunction::emitAutoVarTypeCleanup(
1116                            const CodeGenFunction::AutoVarEmission &emission,
1117                            QualType::DestructionKind dtorKind) {
1118  assert(dtorKind != QualType::DK_none);
1119
1120  // Note that for __block variables, we want to destroy the
1121  // original stack object, not the possibly forwarded object.
1122  llvm::Value *addr = emission.getObjectAddress(*this);
1123
1124  const VarDecl *var = emission.Variable;
1125  QualType type = var->getType();
1126
1127  CleanupKind cleanupKind = NormalAndEHCleanup;
1128  CodeGenFunction::Destroyer *destroyer = 0;
1129
1130  switch (dtorKind) {
1131  case QualType::DK_none:
1132    llvm_unreachable("no cleanup for trivially-destructible variable");
1133
1134  case QualType::DK_cxx_destructor:
1135    // If there's an NRVO flag on the emission, we need a different
1136    // cleanup.
1137    if (emission.NRVOFlag) {
1138      assert(!type->isArrayType());
1139      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1140      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1141                                               emission.NRVOFlag);
1142      return;
1143    }
1144    break;
1145
1146  case QualType::DK_objc_strong_lifetime:
1147    // Suppress cleanups for pseudo-strong variables.
1148    if (var->isARCPseudoStrong()) return;
1149
1150    // Otherwise, consider whether to use an EH cleanup or not.
1151    cleanupKind = getARCCleanupKind();
1152
1153    // Use the imprecise destroyer by default.
1154    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1155      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1156    break;
1157
1158  case QualType::DK_objc_weak_lifetime:
1159    break;
1160  }
1161
1162  // If we haven't chosen a more specific destroyer, use the default.
1163  if (!destroyer) destroyer = getDestroyer(dtorKind);
1164
1165  // Use an EH cleanup in array destructors iff the destructor itself
1166  // is being pushed as an EH cleanup.
1167  bool useEHCleanup = (cleanupKind & EHCleanup);
1168  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1169                                     useEHCleanup);
1170}
1171
1172void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1173  assert(emission.Variable && "emission was not valid!");
1174
1175  // If this was emitted as a global constant, we're done.
1176  if (emission.wasEmittedAsGlobal()) return;
1177
1178  // If we don't have an insertion point, we're done.  Sema prevents
1179  // us from jumping into any of these scopes anyway.
1180  if (!HaveInsertPoint()) return;
1181
1182  const VarDecl &D = *emission.Variable;
1183
1184  // Check the type for a cleanup.
1185  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1186    emitAutoVarTypeCleanup(emission, dtorKind);
1187
1188  // In GC mode, honor objc_precise_lifetime.
1189  if (getLangOpts().getGC() != LangOptions::NonGC &&
1190      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1191    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1192  }
1193
1194  // Handle the cleanup attribute.
1195  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1196    const FunctionDecl *FD = CA->getFunctionDecl();
1197
1198    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1199    assert(F && "Could not find function!");
1200
1201    const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
1202    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1203  }
1204
1205  // If this is a block variable, call _Block_object_destroy
1206  // (on the unforwarded address).
1207  if (emission.IsByRef)
1208    enterByrefCleanup(emission);
1209}
1210
1211CodeGenFunction::Destroyer *
1212CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1213  switch (kind) {
1214  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1215  case QualType::DK_cxx_destructor:
1216    return destroyCXXObject;
1217  case QualType::DK_objc_strong_lifetime:
1218    return destroyARCStrongPrecise;
1219  case QualType::DK_objc_weak_lifetime:
1220    return destroyARCWeak;
1221  }
1222  llvm_unreachable("Unknown DestructionKind");
1223}
1224
1225/// pushDestroy - Push the standard destructor for the given type.
1226void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1227                                  llvm::Value *addr, QualType type) {
1228  assert(dtorKind && "cannot push destructor for trivial type");
1229
1230  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1231  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1232              cleanupKind & EHCleanup);
1233}
1234
1235void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1236                                  QualType type, Destroyer *destroyer,
1237                                  bool useEHCleanupForArray) {
1238  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1239                                     destroyer, useEHCleanupForArray);
1240}
1241
1242/// emitDestroy - Immediately perform the destruction of the given
1243/// object.
1244///
1245/// \param addr - the address of the object; a type*
1246/// \param type - the type of the object; if an array type, all
1247///   objects are destroyed in reverse order
1248/// \param destroyer - the function to call to destroy individual
1249///   elements
1250/// \param useEHCleanupForArray - whether an EH cleanup should be
1251///   used when destroying array elements, in case one of the
1252///   destructions throws an exception
1253void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1254                                  Destroyer *destroyer,
1255                                  bool useEHCleanupForArray) {
1256  const ArrayType *arrayType = getContext().getAsArrayType(type);
1257  if (!arrayType)
1258    return destroyer(*this, addr, type);
1259
1260  llvm::Value *begin = addr;
1261  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1262
1263  // Normally we have to check whether the array is zero-length.
1264  bool checkZeroLength = true;
1265
1266  // But if the array length is constant, we can suppress that.
1267  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1268    // ...and if it's constant zero, we can just skip the entire thing.
1269    if (constLength->isZero()) return;
1270    checkZeroLength = false;
1271  }
1272
1273  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1274  emitArrayDestroy(begin, end, type, destroyer,
1275                   checkZeroLength, useEHCleanupForArray);
1276}
1277
1278/// emitArrayDestroy - Destroys all the elements of the given array,
1279/// beginning from last to first.  The array cannot be zero-length.
1280///
1281/// \param begin - a type* denoting the first element of the array
1282/// \param end - a type* denoting one past the end of the array
1283/// \param type - the element type of the array
1284/// \param destroyer - the function to call to destroy elements
1285/// \param useEHCleanup - whether to push an EH cleanup to destroy
1286///   the remaining elements in case the destruction of a single
1287///   element throws
1288void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1289                                       llvm::Value *end,
1290                                       QualType type,
1291                                       Destroyer *destroyer,
1292                                       bool checkZeroLength,
1293                                       bool useEHCleanup) {
1294  assert(!type->isArrayType());
1295
1296  // The basic structure here is a do-while loop, because we don't
1297  // need to check for the zero-element case.
1298  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1299  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1300
1301  if (checkZeroLength) {
1302    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1303                                                "arraydestroy.isempty");
1304    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1305  }
1306
1307  // Enter the loop body, making that address the current address.
1308  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1309  EmitBlock(bodyBB);
1310  llvm::PHINode *elementPast =
1311    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1312  elementPast->addIncoming(end, entryBB);
1313
1314  // Shift the address back by one element.
1315  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1316  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1317                                                   "arraydestroy.element");
1318
1319  if (useEHCleanup)
1320    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1321
1322  // Perform the actual destruction there.
1323  destroyer(*this, element, type);
1324
1325  if (useEHCleanup)
1326    PopCleanupBlock();
1327
1328  // Check whether we've reached the end.
1329  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1330  Builder.CreateCondBr(done, doneBB, bodyBB);
1331  elementPast->addIncoming(element, Builder.GetInsertBlock());
1332
1333  // Done.
1334  EmitBlock(doneBB);
1335}
1336
1337/// Perform partial array destruction as if in an EH cleanup.  Unlike
1338/// emitArrayDestroy, the element type here may still be an array type.
1339static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1340                                    llvm::Value *begin, llvm::Value *end,
1341                                    QualType type,
1342                                    CodeGenFunction::Destroyer *destroyer) {
1343  // If the element type is itself an array, drill down.
1344  unsigned arrayDepth = 0;
1345  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1346    // VLAs don't require a GEP index to walk into.
1347    if (!isa<VariableArrayType>(arrayType))
1348      arrayDepth++;
1349    type = arrayType->getElementType();
1350  }
1351
1352  if (arrayDepth) {
1353    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1354
1355    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1356    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1357    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1358  }
1359
1360  // Destroy the array.  We don't ever need an EH cleanup because we
1361  // assume that we're in an EH cleanup ourselves, so a throwing
1362  // destructor causes an immediate terminate.
1363  CGF.emitArrayDestroy(begin, end, type, destroyer,
1364                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1365}
1366
1367namespace {
1368  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1369  /// array destroy where the end pointer is regularly determined and
1370  /// does not need to be loaded from a local.
1371  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1372    llvm::Value *ArrayBegin;
1373    llvm::Value *ArrayEnd;
1374    QualType ElementType;
1375    CodeGenFunction::Destroyer *Destroyer;
1376  public:
1377    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1378                               QualType elementType,
1379                               CodeGenFunction::Destroyer *destroyer)
1380      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1381        ElementType(elementType), Destroyer(destroyer) {}
1382
1383    void Emit(CodeGenFunction &CGF, Flags flags) {
1384      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1385                              ElementType, Destroyer);
1386    }
1387  };
1388
1389  /// IrregularPartialArrayDestroy - a cleanup which performs a
1390  /// partial array destroy where the end pointer is irregularly
1391  /// determined and must be loaded from a local.
1392  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1393    llvm::Value *ArrayBegin;
1394    llvm::Value *ArrayEndPointer;
1395    QualType ElementType;
1396    CodeGenFunction::Destroyer *Destroyer;
1397  public:
1398    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1399                                 llvm::Value *arrayEndPointer,
1400                                 QualType elementType,
1401                                 CodeGenFunction::Destroyer *destroyer)
1402      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1403        ElementType(elementType), Destroyer(destroyer) {}
1404
1405    void Emit(CodeGenFunction &CGF, Flags flags) {
1406      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1407      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1408                              ElementType, Destroyer);
1409    }
1410  };
1411}
1412
1413/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1414/// already-constructed elements of the given array.  The cleanup
1415/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1416///
1417/// \param elementType - the immediate element type of the array;
1418///   possibly still an array type
1419/// \param array - a value of type elementType*
1420/// \param destructionKind - the kind of destruction required
1421/// \param initializedElementCount - a value of type size_t* holding
1422///   the number of successfully-constructed elements
1423void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1424                                                 llvm::Value *arrayEndPointer,
1425                                                       QualType elementType,
1426                                                       Destroyer *destroyer) {
1427  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1428                                                    arrayBegin, arrayEndPointer,
1429                                                    elementType, destroyer);
1430}
1431
1432/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1433/// already-constructed elements of the given array.  The cleanup
1434/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1435///
1436/// \param elementType - the immediate element type of the array;
1437///   possibly still an array type
1438/// \param array - a value of type elementType*
1439/// \param destructionKind - the kind of destruction required
1440/// \param initializedElementCount - a value of type size_t* holding
1441///   the number of successfully-constructed elements
1442void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1443                                                     llvm::Value *arrayEnd,
1444                                                     QualType elementType,
1445                                                     Destroyer *destroyer) {
1446  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1447                                                  arrayBegin, arrayEnd,
1448                                                  elementType, destroyer);
1449}
1450
1451namespace {
1452  /// A cleanup to perform a release of an object at the end of a
1453  /// function.  This is used to balance out the incoming +1 of a
1454  /// ns_consumed argument when we can't reasonably do that just by
1455  /// not doing the initial retain for a __block argument.
1456  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1457    ConsumeARCParameter(llvm::Value *param) : Param(param) {}
1458
1459    llvm::Value *Param;
1460
1461    void Emit(CodeGenFunction &CGF, Flags flags) {
1462      CGF.EmitARCRelease(Param, /*precise*/ false);
1463    }
1464  };
1465}
1466
1467/// Emit an alloca (or GlobalValue depending on target)
1468/// for the specified parameter and set up LocalDeclMap.
1469void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1470                                   unsigned ArgNo) {
1471  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1472  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1473         "Invalid argument to EmitParmDecl");
1474
1475  Arg->setName(D.getName());
1476
1477  // Use better IR generation for certain implicit parameters.
1478  if (isa<ImplicitParamDecl>(D)) {
1479    // The only implicit argument a block has is its literal.
1480    if (BlockInfo) {
1481      LocalDeclMap[&D] = Arg;
1482
1483      if (CGDebugInfo *DI = getDebugInfo()) {
1484        if (CGM.getCodeGenOpts().DebugInfo >=
1485            CodeGenOptions::LimitedDebugInfo) {
1486          DI->setLocation(D.getLocation());
1487          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
1488        }
1489      }
1490
1491      return;
1492    }
1493  }
1494
1495  QualType Ty = D.getType();
1496
1497  llvm::Value *DeclPtr;
1498  // If this is an aggregate or variable sized value, reuse the input pointer.
1499  if (!Ty->isConstantSizeType() ||
1500      CodeGenFunction::hasAggregateLLVMType(Ty)) {
1501    DeclPtr = Arg;
1502  } else {
1503    // Otherwise, create a temporary to hold the value.
1504    llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1505                                               D.getName() + ".addr");
1506    Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
1507    DeclPtr = Alloc;
1508
1509    bool doStore = true;
1510
1511    Qualifiers qs = Ty.getQualifiers();
1512
1513    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1514      // We honor __attribute__((ns_consumed)) for types with lifetime.
1515      // For __strong, it's handled by just skipping the initial retain;
1516      // otherwise we have to balance out the initial +1 with an extra
1517      // cleanup to do the release at the end of the function.
1518      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1519
1520      // 'self' is always formally __strong, but if this is not an
1521      // init method then we don't want to retain it.
1522      if (D.isARCPseudoStrong()) {
1523        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1524        assert(&D == method->getSelfDecl());
1525        assert(lt == Qualifiers::OCL_Strong);
1526        assert(qs.hasConst());
1527        assert(method->getMethodFamily() != OMF_init);
1528        (void) method;
1529        lt = Qualifiers::OCL_ExplicitNone;
1530      }
1531
1532      if (lt == Qualifiers::OCL_Strong) {
1533        if (!isConsumed)
1534          // Don't use objc_retainBlock for block pointers, because we
1535          // don't want to Block_copy something just because we got it
1536          // as a parameter.
1537          Arg = EmitARCRetainNonBlock(Arg);
1538      } else {
1539        // Push the cleanup for a consumed parameter.
1540        if (isConsumed)
1541          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg);
1542
1543        if (lt == Qualifiers::OCL_Weak) {
1544          EmitARCInitWeak(DeclPtr, Arg);
1545          doStore = false; // The weak init is a store, no need to do two.
1546        }
1547      }
1548
1549      // Enter the cleanup scope.
1550      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1551    }
1552
1553    // Store the initial value into the alloca.
1554    if (doStore) {
1555      LValue lv = MakeAddrLValue(DeclPtr, Ty,
1556                                 getContext().getDeclAlign(&D));
1557      EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1558    }
1559  }
1560
1561  llvm::Value *&DMEntry = LocalDeclMap[&D];
1562  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
1563  DMEntry = DeclPtr;
1564
1565  // Emit debug info for param declaration.
1566  if (CGDebugInfo *DI = getDebugInfo()) {
1567    if (CGM.getCodeGenOpts().DebugInfo >= CodeGenOptions::LimitedDebugInfo) {
1568      DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1569    }
1570  }
1571
1572  if (D.hasAttr<AnnotateAttr>())
1573      EmitVarAnnotations(&D, DeclPtr);
1574}
1575