CGDecl.cpp revision 355bba72ca52c4a70ca3c3802412c03a6ec31f24 
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    DI->setLocation(D.getLocation());
331    DI->EmitGlobalVariable(var, &D);
332  }
333}
334
335namespace {
336  struct DestroyObject : EHScopeStack::Cleanup {
337    DestroyObject(llvm::Value *addr, QualType type,
338                  CodeGenFunction::Destroyer *destroyer,
339                  bool useEHCleanupForArray)
340      : addr(addr), type(type), destroyer(destroyer),
341        useEHCleanupForArray(useEHCleanupForArray) {}
342
343    llvm::Value *addr;
344    QualType type;
345    CodeGenFunction::Destroyer *destroyer;
346    bool useEHCleanupForArray;
347
348    void Emit(CodeGenFunction &CGF, Flags flags) {
349      // Don't use an EH cleanup recursively from an EH cleanup.
350      bool useEHCleanupForArray =
351        flags.isForNormalCleanup() && this->useEHCleanupForArray;
352
353      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
354    }
355  };
356
357  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
358    DestroyNRVOVariable(llvm::Value *addr,
359                        const CXXDestructorDecl *Dtor,
360                        llvm::Value *NRVOFlag)
361      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
362
363    const CXXDestructorDecl *Dtor;
364    llvm::Value *NRVOFlag;
365    llvm::Value *Loc;
366
367    void Emit(CodeGenFunction &CGF, Flags flags) {
368      // Along the exceptions path we always execute the dtor.
369      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
370
371      llvm::BasicBlock *SkipDtorBB = 0;
372      if (NRVO) {
373        // If we exited via NRVO, we skip the destructor call.
374        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
375        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
376        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
377        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
378        CGF.EmitBlock(RunDtorBB);
379      }
380
381      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
382                                /*ForVirtualBase=*/false, Loc);
383
384      if (NRVO) CGF.EmitBlock(SkipDtorBB);
385    }
386  };
387
388  struct CallStackRestore : EHScopeStack::Cleanup {
389    llvm::Value *Stack;
390    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
391    void Emit(CodeGenFunction &CGF, Flags flags) {
392      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
393      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
394      CGF.Builder.CreateCall(F, V);
395    }
396  };
397
398  struct ExtendGCLifetime : EHScopeStack::Cleanup {
399    const VarDecl &Var;
400    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
401
402    void Emit(CodeGenFunction &CGF, Flags flags) {
403      // Compute the address of the local variable, in case it's a
404      // byref or something.
405      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
406                      Var.getType(), VK_LValue, SourceLocation());
407      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
408      CGF.EmitExtendGCLifetime(value);
409    }
410  };
411
412  struct CallCleanupFunction : EHScopeStack::Cleanup {
413    llvm::Constant *CleanupFn;
414    const CGFunctionInfo &FnInfo;
415    const VarDecl &Var;
416
417    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
418                        const VarDecl *Var)
419      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
420
421    void Emit(CodeGenFunction &CGF, Flags flags) {
422      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
423                      Var.getType(), VK_LValue, SourceLocation());
424      // Compute the address of the local variable, in case it's a byref
425      // or something.
426      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
427
428      // In some cases, the type of the function argument will be different from
429      // the type of the pointer. An example of this is
430      // void f(void* arg);
431      // __attribute__((cleanup(f))) void *g;
432      //
433      // To fix this we insert a bitcast here.
434      QualType ArgTy = FnInfo.arg_begin()->type;
435      llvm::Value *Arg =
436        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
437
438      CallArgList Args;
439      Args.add(RValue::get(Arg),
440               CGF.getContext().getPointerType(Var.getType()));
441      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
442    }
443  };
444}
445
446/// EmitAutoVarWithLifetime - Does the setup required for an automatic
447/// variable with lifetime.
448static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
449                                    llvm::Value *addr,
450                                    Qualifiers::ObjCLifetime lifetime) {
451  switch (lifetime) {
452  case Qualifiers::OCL_None:
453    llvm_unreachable("present but none");
454
455  case Qualifiers::OCL_ExplicitNone:
456    // nothing to do
457    break;
458
459  case Qualifiers::OCL_Strong: {
460    CodeGenFunction::Destroyer *destroyer =
461      (var.hasAttr<ObjCPreciseLifetimeAttr>()
462       ? CodeGenFunction::destroyARCStrongPrecise
463       : CodeGenFunction::destroyARCStrongImprecise);
464
465    CleanupKind cleanupKind = CGF.getARCCleanupKind();
466    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
467                    cleanupKind & EHCleanup);
468    break;
469  }
470  case Qualifiers::OCL_Autoreleasing:
471    // nothing to do
472    break;
473
474  case Qualifiers::OCL_Weak:
475    // __weak objects always get EH cleanups; otherwise, exceptions
476    // could cause really nasty crashes instead of mere leaks.
477    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
478                    CodeGenFunction::destroyARCWeak,
479                    /*useEHCleanup*/ true);
480    break;
481  }
482}
483
484static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
485  if (const Expr *e = dyn_cast<Expr>(s)) {
486    // Skip the most common kinds of expressions that make
487    // hierarchy-walking expensive.
488    s = e = e->IgnoreParenCasts();
489
490    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
491      return (ref->getDecl() == &var);
492  }
493
494  for (Stmt::const_child_range children = s->children(); children; ++children)
495    // children might be null; as in missing decl or conditional of an if-stmt.
496    if ((*children) && isAccessedBy(var, *children))
497      return true;
498
499  return false;
500}
501
502static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
503  if (!decl) return false;
504  if (!isa<VarDecl>(decl)) return false;
505  const VarDecl *var = cast<VarDecl>(decl);
506  return isAccessedBy(*var, e);
507}
508
509static void drillIntoBlockVariable(CodeGenFunction &CGF,
510                                   LValue &lvalue,
511                                   const VarDecl *var) {
512  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
513}
514
515void CodeGenFunction::EmitScalarInit(const Expr *init,
516                                     const ValueDecl *D,
517                                     LValue lvalue,
518                                     bool capturedByInit) {
519  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
520  if (!lifetime) {
521    llvm::Value *value = EmitScalarExpr(init);
522    if (capturedByInit)
523      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
524    EmitStoreThroughLValue(RValue::get(value), lvalue, true);
525    return;
526  }
527
528  // If we're emitting a value with lifetime, we have to do the
529  // initialization *before* we leave the cleanup scopes.
530  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
531    enterFullExpression(ewc);
532    init = ewc->getSubExpr();
533  }
534  CodeGenFunction::RunCleanupsScope Scope(*this);
535
536  // We have to maintain the illusion that the variable is
537  // zero-initialized.  If the variable might be accessed in its
538  // initializer, zero-initialize before running the initializer, then
539  // actually perform the initialization with an assign.
540  bool accessedByInit = false;
541  if (lifetime != Qualifiers::OCL_ExplicitNone)
542    accessedByInit = (capturedByInit || isAccessedBy(D, init));
543  if (accessedByInit) {
544    LValue tempLV = lvalue;
545    // Drill down to the __block object if necessary.
546    if (capturedByInit) {
547      // We can use a simple GEP for this because it can't have been
548      // moved yet.
549      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
550                                   getByRefValueLLVMField(cast<VarDecl>(D))));
551    }
552
553    llvm::PointerType *ty
554      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
555    ty = cast<llvm::PointerType>(ty->getElementType());
556
557    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
558
559    // If __weak, we want to use a barrier under certain conditions.
560    if (lifetime == Qualifiers::OCL_Weak)
561      EmitARCInitWeak(tempLV.getAddress(), zero);
562
563    // Otherwise just do a simple store.
564    else
565      EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true);
566  }
567
568  // Emit the initializer.
569  llvm::Value *value = 0;
570
571  switch (lifetime) {
572  case Qualifiers::OCL_None:
573    llvm_unreachable("present but none");
574
575  case Qualifiers::OCL_ExplicitNone:
576    // nothing to do
577    value = EmitScalarExpr(init);
578    break;
579
580  case Qualifiers::OCL_Strong: {
581    value = EmitARCRetainScalarExpr(init);
582    break;
583  }
584
585  case Qualifiers::OCL_Weak: {
586    // No way to optimize a producing initializer into this.  It's not
587    // worth optimizing for, because the value will immediately
588    // disappear in the common case.
589    value = EmitScalarExpr(init);
590
591    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
592    if (accessedByInit)
593      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
594    else
595      EmitARCInitWeak(lvalue.getAddress(), value);
596    return;
597  }
598
599  case Qualifiers::OCL_Autoreleasing:
600    value = EmitARCRetainAutoreleaseScalarExpr(init);
601    break;
602  }
603
604  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
605
606  // If the variable might have been accessed by its initializer, we
607  // might have to initialize with a barrier.  We have to do this for
608  // both __weak and __strong, but __weak got filtered out above.
609  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
610    llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
611    EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
612    EmitARCRelease(oldValue, /*precise*/ false);
613    return;
614  }
615
616  EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
617}
618
619/// EmitScalarInit - Initialize the given lvalue with the given object.
620void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
621  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
622  if (!lifetime)
623    return EmitStoreThroughLValue(RValue::get(init), lvalue, true);
624
625  switch (lifetime) {
626  case Qualifiers::OCL_None:
627    llvm_unreachable("present but none");
628
629  case Qualifiers::OCL_ExplicitNone:
630    // nothing to do
631    break;
632
633  case Qualifiers::OCL_Strong:
634    init = EmitARCRetain(lvalue.getType(), init);
635    break;
636
637  case Qualifiers::OCL_Weak:
638    // Initialize and then skip the primitive store.
639    EmitARCInitWeak(lvalue.getAddress(), init);
640    return;
641
642  case Qualifiers::OCL_Autoreleasing:
643    init = EmitARCRetainAutorelease(lvalue.getType(), init);
644    break;
645  }
646
647  EmitStoreOfScalar(init, lvalue, /* isInitialization */ true);
648}
649
650/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
651/// non-zero parts of the specified initializer with equal or fewer than
652/// NumStores scalar stores.
653static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
654                                                unsigned &NumStores) {
655  // Zero and Undef never requires any extra stores.
656  if (isa<llvm::ConstantAggregateZero>(Init) ||
657      isa<llvm::ConstantPointerNull>(Init) ||
658      isa<llvm::UndefValue>(Init))
659    return true;
660  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
661      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
662      isa<llvm::ConstantExpr>(Init))
663    return Init->isNullValue() || NumStores--;
664
665  // See if we can emit each element.
666  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
667    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
668      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
669      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
670        return false;
671    }
672    return true;
673  }
674
675  if (llvm::ConstantDataSequential *CDS =
676        dyn_cast<llvm::ConstantDataSequential>(Init)) {
677    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
678      llvm::Constant *Elt = CDS->getElementAsConstant(i);
679      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
680        return false;
681    }
682    return true;
683  }
684
685  // Anything else is hard and scary.
686  return false;
687}
688
689/// emitStoresForInitAfterMemset - For inits that
690/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
691/// stores that would be required.
692static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
693                                         bool isVolatile, CGBuilderTy &Builder) {
694  // Zero doesn't require a store.
695  if (Init->isNullValue() || isa<llvm::UndefValue>(Init))
696    return;
697
698  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
699      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
700      isa<llvm::ConstantExpr>(Init)) {
701    Builder.CreateStore(Init, Loc, isVolatile);
702    return;
703  }
704
705  if (llvm::ConstantDataSequential *CDS =
706        dyn_cast<llvm::ConstantDataSequential>(Init)) {
707    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
708      llvm::Constant *Elt = CDS->getElementAsConstant(i);
709
710      // Get a pointer to the element and emit it.
711      emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
712                                   isVolatile, Builder);
713    }
714    return;
715  }
716
717  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
718         "Unknown value type!");
719
720  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
721    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
722    // Get a pointer to the element and emit it.
723    emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
724                                 isVolatile, Builder);
725  }
726}
727
728
729/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
730/// plus some stores to initialize a local variable instead of using a memcpy
731/// from a constant global.  It is beneficial to use memset if the global is all
732/// zeros, or mostly zeros and large.
733static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
734                                                  uint64_t GlobalSize) {
735  // If a global is all zeros, always use a memset.
736  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
737
738
739  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
740  // do it if it will require 6 or fewer scalar stores.
741  // TODO: Should budget depends on the size?  Avoiding a large global warrants
742  // plopping in more stores.
743  unsigned StoreBudget = 6;
744  uint64_t SizeLimit = 32;
745
746  return GlobalSize > SizeLimit &&
747         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
748}
749
750
751/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
752/// variable declaration with auto, register, or no storage class specifier.
753/// These turn into simple stack objects, or GlobalValues depending on target.
754void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
755  AutoVarEmission emission = EmitAutoVarAlloca(D);
756  EmitAutoVarInit(emission);
757  EmitAutoVarCleanups(emission);
758}
759
760/// EmitAutoVarAlloca - Emit the alloca and debug information for a
761/// local variable.  Does not emit initalization or destruction.
762CodeGenFunction::AutoVarEmission
763CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
764  QualType Ty = D.getType();
765
766  AutoVarEmission emission(D);
767
768  bool isByRef = D.hasAttr<BlocksAttr>();
769  emission.IsByRef = isByRef;
770
771  CharUnits alignment = getContext().getDeclAlign(&D);
772  emission.Alignment = alignment;
773
774  // If the type is variably-modified, emit all the VLA sizes for it.
775  if (Ty->isVariablyModifiedType())
776    EmitVariablyModifiedType(Ty);
777
778  llvm::Value *DeclPtr;
779  if (Ty->isConstantSizeType()) {
780    if (!Target.useGlobalsForAutomaticVariables()) {
781      bool NRVO = getContext().getLangOpts().ElideConstructors &&
782                  D.isNRVOVariable();
783
784      // If this value is a POD array or struct with a statically
785      // determinable constant initializer, there are optimizations we can do.
786      //
787      // TODO: We should constant-evaluate the initializer of any variable,
788      // as long as it is initialized by a constant expression. Currently,
789      // isConstantInitializer produces wrong answers for structs with
790      // reference or bitfield members, and a few other cases, and checking
791      // for POD-ness protects us from some of these.
792      if (D.getInit() &&
793          (Ty->isArrayType() || Ty->isRecordType()) &&
794          (Ty.isPODType(getContext()) ||
795           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
796          D.getInit()->isConstantInitializer(getContext(), false)) {
797
798        // If the variable's a const type, and it's neither an NRVO
799        // candidate nor a __block variable and has no mutable members,
800        // emit it as a global instead.
801        if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef &&
802            CGM.isTypeConstant(Ty, true)) {
803          EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
804
805          emission.Address = 0; // signal this condition to later callbacks
806          assert(emission.wasEmittedAsGlobal());
807          return emission;
808        }
809
810        // Otherwise, tell the initialization code that we're in this case.
811        emission.IsConstantAggregate = true;
812      }
813
814      // A normal fixed sized variable becomes an alloca in the entry block,
815      // unless it's an NRVO variable.
816      llvm::Type *LTy = ConvertTypeForMem(Ty);
817
818      if (NRVO) {
819        // The named return value optimization: allocate this variable in the
820        // return slot, so that we can elide the copy when returning this
821        // variable (C++0x [class.copy]p34).
822        DeclPtr = ReturnValue;
823
824        if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
825          if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
826            // Create a flag that is used to indicate when the NRVO was applied
827            // to this variable. Set it to zero to indicate that NRVO was not
828            // applied.
829            llvm::Value *Zero = Builder.getFalse();
830            llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
831            EnsureInsertPoint();
832            Builder.CreateStore(Zero, NRVOFlag);
833
834            // Record the NRVO flag for this variable.
835            NRVOFlags[&D] = NRVOFlag;
836            emission.NRVOFlag = NRVOFlag;
837          }
838        }
839      } else {
840        if (isByRef)
841          LTy = BuildByRefType(&D);
842
843        llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
844        Alloc->setName(D.getName());
845
846        CharUnits allocaAlignment = alignment;
847        if (isByRef)
848          allocaAlignment = std::max(allocaAlignment,
849              getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
850        Alloc->setAlignment(allocaAlignment.getQuantity());
851        DeclPtr = Alloc;
852      }
853    } else {
854      // Targets that don't support recursion emit locals as globals.
855      const char *Class =
856        D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
857      DeclPtr = CreateStaticVarDecl(D, Class,
858                                    llvm::GlobalValue::InternalLinkage);
859    }
860  } else {
861    EnsureInsertPoint();
862
863    if (!DidCallStackSave) {
864      // Save the stack.
865      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
866
867      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
868      llvm::Value *V = Builder.CreateCall(F);
869
870      Builder.CreateStore(V, Stack);
871
872      DidCallStackSave = true;
873
874      // Push a cleanup block and restore the stack there.
875      // FIXME: in general circumstances, this should be an EH cleanup.
876      EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
877    }
878
879    llvm::Value *elementCount;
880    QualType elementType;
881    llvm::tie(elementCount, elementType) = getVLASize(Ty);
882
883    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
884
885    // Allocate memory for the array.
886    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
887    vla->setAlignment(alignment.getQuantity());
888
889    DeclPtr = vla;
890  }
891
892  llvm::Value *&DMEntry = LocalDeclMap[&D];
893  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
894  DMEntry = DeclPtr;
895  emission.Address = DeclPtr;
896
897  // Emit debug info for local var declaration.
898  if (HaveInsertPoint())
899    if (CGDebugInfo *DI = getDebugInfo()) {
900      DI->setLocation(D.getLocation());
901      if (Target.useGlobalsForAutomaticVariables()) {
902        DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
903      } else
904        DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
905    }
906
907  if (D.hasAttr<AnnotateAttr>())
908      EmitVarAnnotations(&D, emission.Address);
909
910  return emission;
911}
912
913/// Determines whether the given __block variable is potentially
914/// captured by the given expression.
915static bool isCapturedBy(const VarDecl &var, const Expr *e) {
916  // Skip the most common kinds of expressions that make
917  // hierarchy-walking expensive.
918  e = e->IgnoreParenCasts();
919
920  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
921    const BlockDecl *block = be->getBlockDecl();
922    for (BlockDecl::capture_const_iterator i = block->capture_begin(),
923           e = block->capture_end(); i != e; ++i) {
924      if (i->getVariable() == &var)
925        return true;
926    }
927
928    // No need to walk into the subexpressions.
929    return false;
930  }
931
932  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
933    const CompoundStmt *CS = SE->getSubStmt();
934    for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
935	   BE = CS->body_end(); BI != BE; ++BI)
936      if (Expr *E = dyn_cast<Expr>((*BI))) {
937        if (isCapturedBy(var, E))
938            return true;
939      }
940      else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) {
941          // special case declarations
942          for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
943               I != E; ++I) {
944              if (VarDecl *VD = dyn_cast<VarDecl>((*I))) {
945                Expr *Init = VD->getInit();
946                if (Init && isCapturedBy(var, Init))
947                  return true;
948              }
949          }
950      }
951      else
952        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
953        // Later, provide code to poke into statements for capture analysis.
954        return true;
955    return false;
956  }
957
958  for (Stmt::const_child_range children = e->children(); children; ++children)
959    if (isCapturedBy(var, cast<Expr>(*children)))
960      return true;
961
962  return false;
963}
964
965/// \brief Determine whether the given initializer is trivial in the sense
966/// that it requires no code to be generated.
967static bool isTrivialInitializer(const Expr *Init) {
968  if (!Init)
969    return true;
970
971  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
972    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
973      if (Constructor->isTrivial() &&
974          Constructor->isDefaultConstructor() &&
975          !Construct->requiresZeroInitialization())
976        return true;
977
978  return false;
979}
980void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
981  assert(emission.Variable && "emission was not valid!");
982
983  // If this was emitted as a global constant, we're done.
984  if (emission.wasEmittedAsGlobal()) return;
985
986  const VarDecl &D = *emission.Variable;
987  QualType type = D.getType();
988
989  // If this local has an initializer, emit it now.
990  const Expr *Init = D.getInit();
991
992  // If we are at an unreachable point, we don't need to emit the initializer
993  // unless it contains a label.
994  if (!HaveInsertPoint()) {
995    if (!Init || !ContainsLabel(Init)) return;
996    EnsureInsertPoint();
997  }
998
999  // Initialize the structure of a __block variable.
1000  if (emission.IsByRef)
1001    emitByrefStructureInit(emission);
1002
1003  if (isTrivialInitializer(Init))
1004    return;
1005
1006  CharUnits alignment = emission.Alignment;
1007
1008  // Check whether this is a byref variable that's potentially
1009  // captured and moved by its own initializer.  If so, we'll need to
1010  // emit the initializer first, then copy into the variable.
1011  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
1012
1013  llvm::Value *Loc =
1014    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
1015
1016  llvm::Constant *constant = 0;
1017  if (emission.IsConstantAggregate) {
1018    assert(!capturedByInit && "constant init contains a capturing block?");
1019    constant = CGM.EmitConstantInit(D, this);
1020  }
1021
1022  if (!constant) {
1023    LValue lv = MakeAddrLValue(Loc, type, alignment);
1024    lv.setNonGC(true);
1025    return EmitExprAsInit(Init, &D, lv, capturedByInit);
1026  }
1027
1028  // If this is a simple aggregate initialization, we can optimize it
1029  // in various ways.
1030  bool isVolatile = type.isVolatileQualified();
1031
1032  llvm::Value *SizeVal =
1033    llvm::ConstantInt::get(IntPtrTy,
1034                           getContext().getTypeSizeInChars(type).getQuantity());
1035
1036  llvm::Type *BP = Int8PtrTy;
1037  if (Loc->getType() != BP)
1038    Loc = Builder.CreateBitCast(Loc, BP);
1039
1040  // If the initializer is all or mostly zeros, codegen with memset then do
1041  // a few stores afterward.
1042  if (shouldUseMemSetPlusStoresToInitialize(constant,
1043                CGM.getTargetData().getTypeAllocSize(constant->getType()))) {
1044    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
1045                         alignment.getQuantity(), isVolatile);
1046    if (!constant->isNullValue()) {
1047      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
1048      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
1049    }
1050  } else {
1051    // Otherwise, create a temporary global with the initializer then
1052    // memcpy from the global to the alloca.
1053    std::string Name = GetStaticDeclName(*this, D, ".");
1054    llvm::GlobalVariable *GV =
1055      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1056                               llvm::GlobalValue::PrivateLinkage,
1057                               constant, Name, 0, false, 0);
1058    GV->setAlignment(alignment.getQuantity());
1059    GV->setUnnamedAddr(true);
1060
1061    llvm::Value *SrcPtr = GV;
1062    if (SrcPtr->getType() != BP)
1063      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1064
1065    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1066                         isVolatile);
1067  }
1068}
1069
1070/// Emit an expression as an initializer for a variable at the given
1071/// location.  The expression is not necessarily the normal
1072/// initializer for the variable, and the address is not necessarily
1073/// its normal location.
1074///
1075/// \param init the initializing expression
1076/// \param var the variable to act as if we're initializing
1077/// \param loc the address to initialize; its type is a pointer
1078///   to the LLVM mapping of the variable's type
1079/// \param alignment the alignment of the address
1080/// \param capturedByInit true if the variable is a __block variable
1081///   whose address is potentially changed by the initializer
1082void CodeGenFunction::EmitExprAsInit(const Expr *init,
1083                                     const ValueDecl *D,
1084                                     LValue lvalue,
1085                                     bool capturedByInit) {
1086  QualType type = D->getType();
1087
1088  if (type->isReferenceType()) {
1089    RValue rvalue = EmitReferenceBindingToExpr(init, D);
1090    if (capturedByInit)
1091      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1092    EmitStoreThroughLValue(rvalue, lvalue, true);
1093  } else if (!hasAggregateLLVMType(type)) {
1094    EmitScalarInit(init, D, lvalue, capturedByInit);
1095  } else if (type->isAnyComplexType()) {
1096    ComplexPairTy complex = EmitComplexExpr(init);
1097    if (capturedByInit)
1098      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1099    StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile());
1100  } else {
1101    // TODO: how can we delay here if D is captured by its initializer?
1102    EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1103                                              AggValueSlot::IsDestructed,
1104                                         AggValueSlot::DoesNotNeedGCBarriers,
1105                                              AggValueSlot::IsNotAliased));
1106    MaybeEmitStdInitializerListCleanup(lvalue.getAddress(), init);
1107  }
1108}
1109
1110/// Enter a destroy cleanup for the given local variable.
1111void CodeGenFunction::emitAutoVarTypeCleanup(
1112                            const CodeGenFunction::AutoVarEmission &emission,
1113                            QualType::DestructionKind dtorKind) {
1114  assert(dtorKind != QualType::DK_none);
1115
1116  // Note that for __block variables, we want to destroy the
1117  // original stack object, not the possibly forwarded object.
1118  llvm::Value *addr = emission.getObjectAddress(*this);
1119
1120  const VarDecl *var = emission.Variable;
1121  QualType type = var->getType();
1122
1123  CleanupKind cleanupKind = NormalAndEHCleanup;
1124  CodeGenFunction::Destroyer *destroyer = 0;
1125
1126  switch (dtorKind) {
1127  case QualType::DK_none:
1128    llvm_unreachable("no cleanup for trivially-destructible variable");
1129
1130  case QualType::DK_cxx_destructor:
1131    // If there's an NRVO flag on the emission, we need a different
1132    // cleanup.
1133    if (emission.NRVOFlag) {
1134      assert(!type->isArrayType());
1135      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1136      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1137                                               emission.NRVOFlag);
1138      return;
1139    }
1140    break;
1141
1142  case QualType::DK_objc_strong_lifetime:
1143    // Suppress cleanups for pseudo-strong variables.
1144    if (var->isARCPseudoStrong()) return;
1145
1146    // Otherwise, consider whether to use an EH cleanup or not.
1147    cleanupKind = getARCCleanupKind();
1148
1149    // Use the imprecise destroyer by default.
1150    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1151      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1152    break;
1153
1154  case QualType::DK_objc_weak_lifetime:
1155    break;
1156  }
1157
1158  // If we haven't chosen a more specific destroyer, use the default.
1159  if (!destroyer) destroyer = getDestroyer(dtorKind);
1160
1161  // Use an EH cleanup in array destructors iff the destructor itself
1162  // is being pushed as an EH cleanup.
1163  bool useEHCleanup = (cleanupKind & EHCleanup);
1164  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1165                                     useEHCleanup);
1166}
1167
1168void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1169  assert(emission.Variable && "emission was not valid!");
1170
1171  // If this was emitted as a global constant, we're done.
1172  if (emission.wasEmittedAsGlobal()) return;
1173
1174  const VarDecl &D = *emission.Variable;
1175
1176  // Check the type for a cleanup.
1177  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1178    emitAutoVarTypeCleanup(emission, dtorKind);
1179
1180  // In GC mode, honor objc_precise_lifetime.
1181  if (getLangOpts().getGC() != LangOptions::NonGC &&
1182      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1183    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1184  }
1185
1186  // Handle the cleanup attribute.
1187  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1188    const FunctionDecl *FD = CA->getFunctionDecl();
1189
1190    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1191    assert(F && "Could not find function!");
1192
1193    const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
1194    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1195  }
1196
1197  // If this is a block variable, call _Block_object_destroy
1198  // (on the unforwarded address).
1199  if (emission.IsByRef)
1200    enterByrefCleanup(emission);
1201}
1202
1203CodeGenFunction::Destroyer *
1204CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1205  switch (kind) {
1206  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1207  case QualType::DK_cxx_destructor:
1208    return destroyCXXObject;
1209  case QualType::DK_objc_strong_lifetime:
1210    return destroyARCStrongPrecise;
1211  case QualType::DK_objc_weak_lifetime:
1212    return destroyARCWeak;
1213  }
1214  llvm_unreachable("Unknown DestructionKind");
1215}
1216
1217/// pushDestroy - Push the standard destructor for the given type.
1218void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1219                                  llvm::Value *addr, QualType type) {
1220  assert(dtorKind && "cannot push destructor for trivial type");
1221
1222  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1223  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1224              cleanupKind & EHCleanup);
1225}
1226
1227void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1228                                  QualType type, Destroyer *destroyer,
1229                                  bool useEHCleanupForArray) {
1230  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1231                                     destroyer, useEHCleanupForArray);
1232}
1233
1234/// emitDestroy - Immediately perform the destruction of the given
1235/// object.
1236///
1237/// \param addr - the address of the object; a type*
1238/// \param type - the type of the object; if an array type, all
1239///   objects are destroyed in reverse order
1240/// \param destroyer - the function to call to destroy individual
1241///   elements
1242/// \param useEHCleanupForArray - whether an EH cleanup should be
1243///   used when destroying array elements, in case one of the
1244///   destructions throws an exception
1245void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1246                                  Destroyer *destroyer,
1247                                  bool useEHCleanupForArray) {
1248  const ArrayType *arrayType = getContext().getAsArrayType(type);
1249  if (!arrayType)
1250    return destroyer(*this, addr, type);
1251
1252  llvm::Value *begin = addr;
1253  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1254
1255  // Normally we have to check whether the array is zero-length.
1256  bool checkZeroLength = true;
1257
1258  // But if the array length is constant, we can suppress that.
1259  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1260    // ...and if it's constant zero, we can just skip the entire thing.
1261    if (constLength->isZero()) return;
1262    checkZeroLength = false;
1263  }
1264
1265  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1266  emitArrayDestroy(begin, end, type, destroyer,
1267                   checkZeroLength, useEHCleanupForArray);
1268}
1269
1270/// emitArrayDestroy - Destroys all the elements of the given array,
1271/// beginning from last to first.  The array cannot be zero-length.
1272///
1273/// \param begin - a type* denoting the first element of the array
1274/// \param end - a type* denoting one past the end of the array
1275/// \param type - the element type of the array
1276/// \param destroyer - the function to call to destroy elements
1277/// \param useEHCleanup - whether to push an EH cleanup to destroy
1278///   the remaining elements in case the destruction of a single
1279///   element throws
1280void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1281                                       llvm::Value *end,
1282                                       QualType type,
1283                                       Destroyer *destroyer,
1284                                       bool checkZeroLength,
1285                                       bool useEHCleanup) {
1286  assert(!type->isArrayType());
1287
1288  // The basic structure here is a do-while loop, because we don't
1289  // need to check for the zero-element case.
1290  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1291  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1292
1293  if (checkZeroLength) {
1294    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1295                                                "arraydestroy.isempty");
1296    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1297  }
1298
1299  // Enter the loop body, making that address the current address.
1300  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1301  EmitBlock(bodyBB);
1302  llvm::PHINode *elementPast =
1303    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1304  elementPast->addIncoming(end, entryBB);
1305
1306  // Shift the address back by one element.
1307  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1308  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1309                                                   "arraydestroy.element");
1310
1311  if (useEHCleanup)
1312    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1313
1314  // Perform the actual destruction there.
1315  destroyer(*this, element, type);
1316
1317  if (useEHCleanup)
1318    PopCleanupBlock();
1319
1320  // Check whether we've reached the end.
1321  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1322  Builder.CreateCondBr(done, doneBB, bodyBB);
1323  elementPast->addIncoming(element, Builder.GetInsertBlock());
1324
1325  // Done.
1326  EmitBlock(doneBB);
1327}
1328
1329/// Perform partial array destruction as if in an EH cleanup.  Unlike
1330/// emitArrayDestroy, the element type here may still be an array type.
1331static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1332                                    llvm::Value *begin, llvm::Value *end,
1333                                    QualType type,
1334                                    CodeGenFunction::Destroyer *destroyer) {
1335  // If the element type is itself an array, drill down.
1336  unsigned arrayDepth = 0;
1337  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1338    // VLAs don't require a GEP index to walk into.
1339    if (!isa<VariableArrayType>(arrayType))
1340      arrayDepth++;
1341    type = arrayType->getElementType();
1342  }
1343
1344  if (arrayDepth) {
1345    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1346
1347    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1348    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1349    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1350  }
1351
1352  // Destroy the array.  We don't ever need an EH cleanup because we
1353  // assume that we're in an EH cleanup ourselves, so a throwing
1354  // destructor causes an immediate terminate.
1355  CGF.emitArrayDestroy(begin, end, type, destroyer,
1356                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1357}
1358
1359namespace {
1360  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1361  /// array destroy where the end pointer is regularly determined and
1362  /// does not need to be loaded from a local.
1363  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1364    llvm::Value *ArrayBegin;
1365    llvm::Value *ArrayEnd;
1366    QualType ElementType;
1367    CodeGenFunction::Destroyer *Destroyer;
1368  public:
1369    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1370                               QualType elementType,
1371                               CodeGenFunction::Destroyer *destroyer)
1372      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1373        ElementType(elementType), Destroyer(destroyer) {}
1374
1375    void Emit(CodeGenFunction &CGF, Flags flags) {
1376      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1377                              ElementType, Destroyer);
1378    }
1379  };
1380
1381  /// IrregularPartialArrayDestroy - a cleanup which performs a
1382  /// partial array destroy where the end pointer is irregularly
1383  /// determined and must be loaded from a local.
1384  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1385    llvm::Value *ArrayBegin;
1386    llvm::Value *ArrayEndPointer;
1387    QualType ElementType;
1388    CodeGenFunction::Destroyer *Destroyer;
1389  public:
1390    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1391                                 llvm::Value *arrayEndPointer,
1392                                 QualType elementType,
1393                                 CodeGenFunction::Destroyer *destroyer)
1394      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1395        ElementType(elementType), Destroyer(destroyer) {}
1396
1397    void Emit(CodeGenFunction &CGF, Flags flags) {
1398      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1399      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1400                              ElementType, Destroyer);
1401    }
1402  };
1403}
1404
1405/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1406/// already-constructed elements of the given array.  The cleanup
1407/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1408///
1409/// \param elementType - the immediate element type of the array;
1410///   possibly still an array type
1411/// \param array - a value of type elementType*
1412/// \param destructionKind - the kind of destruction required
1413/// \param initializedElementCount - a value of type size_t* holding
1414///   the number of successfully-constructed elements
1415void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1416                                                 llvm::Value *arrayEndPointer,
1417                                                       QualType elementType,
1418                                                       Destroyer *destroyer) {
1419  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1420                                                    arrayBegin, arrayEndPointer,
1421                                                    elementType, destroyer);
1422}
1423
1424/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1425/// already-constructed elements of the given array.  The cleanup
1426/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1427///
1428/// \param elementType - the immediate element type of the array;
1429///   possibly still an array type
1430/// \param array - a value of type elementType*
1431/// \param destructionKind - the kind of destruction required
1432/// \param initializedElementCount - a value of type size_t* holding
1433///   the number of successfully-constructed elements
1434void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1435                                                     llvm::Value *arrayEnd,
1436                                                     QualType elementType,
1437                                                     Destroyer *destroyer) {
1438  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1439                                                  arrayBegin, arrayEnd,
1440                                                  elementType, destroyer);
1441}
1442
1443namespace {
1444  /// A cleanup to perform a release of an object at the end of a
1445  /// function.  This is used to balance out the incoming +1 of a
1446  /// ns_consumed argument when we can't reasonably do that just by
1447  /// not doing the initial retain for a __block argument.
1448  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1449    ConsumeARCParameter(llvm::Value *param) : Param(param) {}
1450
1451    llvm::Value *Param;
1452
1453    void Emit(CodeGenFunction &CGF, Flags flags) {
1454      CGF.EmitARCRelease(Param, /*precise*/ false);
1455    }
1456  };
1457}
1458
1459/// Emit an alloca (or GlobalValue depending on target)
1460/// for the specified parameter and set up LocalDeclMap.
1461void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1462                                   unsigned ArgNo) {
1463  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1464  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1465         "Invalid argument to EmitParmDecl");
1466
1467  Arg->setName(D.getName());
1468
1469  // Use better IR generation for certain implicit parameters.
1470  if (isa<ImplicitParamDecl>(D)) {
1471    // The only implicit argument a block has is its literal.
1472    if (BlockInfo) {
1473      LocalDeclMap[&D] = Arg;
1474
1475      if (CGDebugInfo *DI = getDebugInfo()) {
1476        DI->setLocation(D.getLocation());
1477        DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
1478      }
1479
1480      return;
1481    }
1482  }
1483
1484  QualType Ty = D.getType();
1485
1486  llvm::Value *DeclPtr;
1487  // If this is an aggregate or variable sized value, reuse the input pointer.
1488  if (!Ty->isConstantSizeType() ||
1489      CodeGenFunction::hasAggregateLLVMType(Ty)) {
1490    DeclPtr = Arg;
1491  } else {
1492    // Otherwise, create a temporary to hold the value.
1493    llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1494                                               D.getName() + ".addr");
1495    Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
1496    DeclPtr = Alloc;
1497
1498    bool doStore = true;
1499
1500    Qualifiers qs = Ty.getQualifiers();
1501
1502    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1503      // We honor __attribute__((ns_consumed)) for types with lifetime.
1504      // For __strong, it's handled by just skipping the initial retain;
1505      // otherwise we have to balance out the initial +1 with an extra
1506      // cleanup to do the release at the end of the function.
1507      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1508
1509      // 'self' is always formally __strong, but if this is not an
1510      // init method then we don't want to retain it.
1511      if (D.isARCPseudoStrong()) {
1512        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1513        assert(&D == method->getSelfDecl());
1514        assert(lt == Qualifiers::OCL_Strong);
1515        assert(qs.hasConst());
1516        assert(method->getMethodFamily() != OMF_init);
1517        (void) method;
1518        lt = Qualifiers::OCL_ExplicitNone;
1519      }
1520
1521      if (lt == Qualifiers::OCL_Strong) {
1522        if (!isConsumed)
1523          // Don't use objc_retainBlock for block pointers, because we
1524          // don't want to Block_copy something just because we got it
1525          // as a parameter.
1526          Arg = EmitARCRetainNonBlock(Arg);
1527      } else {
1528        // Push the cleanup for a consumed parameter.
1529        if (isConsumed)
1530          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg);
1531
1532        if (lt == Qualifiers::OCL_Weak) {
1533          EmitARCInitWeak(DeclPtr, Arg);
1534          doStore = false; // The weak init is a store, no need to do two.
1535        }
1536      }
1537
1538      // Enter the cleanup scope.
1539      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1540    }
1541
1542    // Store the initial value into the alloca.
1543    if (doStore) {
1544      LValue lv = MakeAddrLValue(DeclPtr, Ty,
1545                                 getContext().getDeclAlign(&D));
1546      EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1547    }
1548  }
1549
1550  llvm::Value *&DMEntry = LocalDeclMap[&D];
1551  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
1552  DMEntry = DeclPtr;
1553
1554  // Emit debug info for param declaration.
1555  if (CGDebugInfo *DI = getDebugInfo())
1556    DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1557
1558  if (D.hasAttr<AnnotateAttr>())
1559      EmitVarAnnotations(&D, DeclPtr);
1560}
1561