CGDecl.cpp revision 51201882382fb40c9456a06c7f93d6ddd4a57712 
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::ObjCForwardProtocol:
69  case Decl::FileScopeAsm:
70  case Decl::Friend:
71  case Decl::FriendTemplate:
72  case Decl::Block:
73  case Decl::ClassScopeFunctionSpecialization:
74    llvm_unreachable("Declaration should not be in declstmts!");
75  case Decl::Function:  // void X();
76  case Decl::Record:    // struct/union/class X;
77  case Decl::Enum:      // enum X;
78  case Decl::EnumConstant: // enum ? { X = ? }
79  case Decl::CXXRecord: // struct/union/class X; [C++]
80  case Decl::Using:          // using X; [C++]
81  case Decl::UsingShadow:
82  case Decl::UsingDirective: // using namespace X; [C++]
83  case Decl::NamespaceAlias:
84  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
85  case Decl::Label:        // __label__ x;
86  case Decl::Import:
87    // None of these decls require codegen support.
88    return;
89
90  case Decl::Var: {
91    const VarDecl &VD = cast<VarDecl>(D);
92    assert(VD.isLocalVarDecl() &&
93           "Should not see file-scope variables inside a function!");
94    return EmitVarDecl(VD);
95  }
96
97  case Decl::Typedef:      // typedef int X;
98  case Decl::TypeAlias: {  // using X = int; [C++0x]
99    const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
100    QualType Ty = TD.getUnderlyingType();
101
102    if (Ty->isVariablyModifiedType())
103      EmitVariablyModifiedType(Ty);
104  }
105  }
106}
107
108/// EmitVarDecl - This method handles emission of any variable declaration
109/// inside a function, including static vars etc.
110void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
111  switch (D.getStorageClass()) {
112  case SC_None:
113  case SC_Auto:
114  case SC_Register:
115    return EmitAutoVarDecl(D);
116  case SC_Static: {
117    llvm::GlobalValue::LinkageTypes Linkage =
118      llvm::GlobalValue::InternalLinkage;
119
120    // If the function definition has some sort of weak linkage, its
121    // static variables should also be weak so that they get properly
122    // uniqued.  We can't do this in C, though, because there's no
123    // standard way to agree on which variables are the same (i.e.
124    // there's no mangling).
125    if (getContext().getLangOptions().CPlusPlus)
126      if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
127        Linkage = CurFn->getLinkage();
128
129    return EmitStaticVarDecl(D, Linkage);
130  }
131  case SC_Extern:
132  case SC_PrivateExtern:
133    // Don't emit it now, allow it to be emitted lazily on its first use.
134    return;
135  case SC_OpenCLWorkGroupLocal:
136    return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
137  }
138
139  llvm_unreachable("Unknown storage class");
140}
141
142static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
143                                     const char *Separator) {
144  CodeGenModule &CGM = CGF.CGM;
145  if (CGF.getContext().getLangOptions().CPlusPlus) {
146    StringRef Name = CGM.getMangledName(&D);
147    return Name.str();
148  }
149
150  std::string ContextName;
151  if (!CGF.CurFuncDecl) {
152    // Better be in a block declared in global scope.
153    const NamedDecl *ND = cast<NamedDecl>(&D);
154    const DeclContext *DC = ND->getDeclContext();
155    if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
156      MangleBuffer Name;
157      CGM.getBlockMangledName(GlobalDecl(), Name, BD);
158      ContextName = Name.getString();
159    }
160    else
161      llvm_unreachable("Unknown context for block static var decl");
162  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
163    StringRef Name = CGM.getMangledName(FD);
164    ContextName = Name.str();
165  } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
166    ContextName = CGF.CurFn->getName();
167  else
168    llvm_unreachable("Unknown context for static var decl");
169
170  return ContextName + Separator + D.getNameAsString();
171}
172
173llvm::GlobalVariable *
174CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
175                                     const char *Separator,
176                                     llvm::GlobalValue::LinkageTypes Linkage) {
177  QualType Ty = D.getType();
178  assert(Ty->isConstantSizeType() && "VLAs can't be static");
179
180  // Use the label if the variable is renamed with the asm-label extension.
181  std::string Name;
182  if (D.hasAttr<AsmLabelAttr>())
183    Name = CGM.getMangledName(&D);
184  else
185    Name = GetStaticDeclName(*this, D, Separator);
186
187  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
188  llvm::GlobalVariable *GV =
189    new llvm::GlobalVariable(CGM.getModule(), LTy,
190                             Ty.isConstant(getContext()), Linkage,
191                             CGM.EmitNullConstant(D.getType()), Name, 0,
192                             D.isThreadSpecified(),
193                             CGM.getContext().getTargetAddressSpace(Ty));
194  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
195  if (Linkage != llvm::GlobalValue::InternalLinkage)
196    GV->setVisibility(CurFn->getVisibility());
197  return GV;
198}
199
200/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
201/// global variable that has already been created for it.  If the initializer
202/// has a different type than GV does, this may free GV and return a different
203/// one.  Otherwise it just returns GV.
204llvm::GlobalVariable *
205CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
206                                               llvm::GlobalVariable *GV) {
207  llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this);
208
209  // If constant emission failed, then this should be a C++ static
210  // initializer.
211  if (!Init) {
212    if (!getContext().getLangOptions().CPlusPlus)
213      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
214    else if (Builder.GetInsertBlock()) {
215      // Since we have a static initializer, this global variable can't
216      // be constant.
217      GV->setConstant(false);
218
219      EmitCXXGuardedInit(D, GV);
220    }
221    return GV;
222  }
223
224  // The initializer may differ in type from the global. Rewrite
225  // the global to match the initializer.  (We have to do this
226  // because some types, like unions, can't be completely represented
227  // in the LLVM type system.)
228  if (GV->getType()->getElementType() != Init->getType()) {
229    llvm::GlobalVariable *OldGV = GV;
230
231    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
232                                  OldGV->isConstant(),
233                                  OldGV->getLinkage(), Init, "",
234                                  /*InsertBefore*/ OldGV,
235                                  D.isThreadSpecified(),
236                           CGM.getContext().getTargetAddressSpace(D.getType()));
237    GV->setVisibility(OldGV->getVisibility());
238
239    // Steal the name of the old global
240    GV->takeName(OldGV);
241
242    // Replace all uses of the old global with the new global
243    llvm::Constant *NewPtrForOldDecl =
244    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
245    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
246
247    // Erase the old global, since it is no longer used.
248    OldGV->eraseFromParent();
249  }
250
251  GV->setInitializer(Init);
252  return GV;
253}
254
255void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
256                                      llvm::GlobalValue::LinkageTypes Linkage) {
257  llvm::Value *&DMEntry = LocalDeclMap[&D];
258  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
259
260  llvm::GlobalVariable *GV = CreateStaticVarDecl(D, ".", Linkage);
261
262  // Store into LocalDeclMap before generating initializer to handle
263  // circular references.
264  DMEntry = GV;
265
266  // We can't have a VLA here, but we can have a pointer to a VLA,
267  // even though that doesn't really make any sense.
268  // Make sure to evaluate VLA bounds now so that we have them for later.
269  if (D.getType()->isVariablyModifiedType())
270    EmitVariablyModifiedType(D.getType());
271
272  // Local static block variables must be treated as globals as they may be
273  // referenced in their RHS initializer block-literal expresion.
274  CGM.setStaticLocalDeclAddress(&D, GV);
275
276  // If this value has an initializer, emit it.
277  if (D.getInit())
278    GV = AddInitializerToStaticVarDecl(D, GV);
279
280  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
281
282  if (D.hasAttr<AnnotateAttr>())
283    CGM.AddGlobalAnnotations(&D, GV);
284
285  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
286    GV->setSection(SA->getName());
287
288  if (D.hasAttr<UsedAttr>())
289    CGM.AddUsedGlobal(GV);
290
291  // We may have to cast the constant because of the initializer
292  // mismatch above.
293  //
294  // FIXME: It is really dangerous to store this in the map; if anyone
295  // RAUW's the GV uses of this constant will be invalid.
296  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
297  llvm::Type *LPtrTy =
298    LTy->getPointerTo(CGM.getContext().getTargetAddressSpace(D.getType()));
299  DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
300
301  // Emit global variable debug descriptor for static vars.
302  CGDebugInfo *DI = getDebugInfo();
303  if (DI) {
304    DI->setLocation(D.getLocation());
305    DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
306  }
307}
308
309namespace {
310  struct DestroyObject : EHScopeStack::Cleanup {
311    DestroyObject(llvm::Value *addr, QualType type,
312                  CodeGenFunction::Destroyer *destroyer,
313                  bool useEHCleanupForArray)
314      : addr(addr), type(type), destroyer(*destroyer),
315        useEHCleanupForArray(useEHCleanupForArray) {}
316
317    llvm::Value *addr;
318    QualType type;
319    CodeGenFunction::Destroyer &destroyer;
320    bool useEHCleanupForArray;
321
322    void Emit(CodeGenFunction &CGF, Flags flags) {
323      // Don't use an EH cleanup recursively from an EH cleanup.
324      bool useEHCleanupForArray =
325        flags.isForNormalCleanup() && this->useEHCleanupForArray;
326
327      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
328    }
329  };
330
331  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
332    DestroyNRVOVariable(llvm::Value *addr,
333                        const CXXDestructorDecl *Dtor,
334                        llvm::Value *NRVOFlag)
335      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
336
337    const CXXDestructorDecl *Dtor;
338    llvm::Value *NRVOFlag;
339    llvm::Value *Loc;
340
341    void Emit(CodeGenFunction &CGF, Flags flags) {
342      // Along the exceptions path we always execute the dtor.
343      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
344
345      llvm::BasicBlock *SkipDtorBB = 0;
346      if (NRVO) {
347        // If we exited via NRVO, we skip the destructor call.
348        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
349        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
350        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
351        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
352        CGF.EmitBlock(RunDtorBB);
353      }
354
355      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
356                                /*ForVirtualBase=*/false, Loc);
357
358      if (NRVO) CGF.EmitBlock(SkipDtorBB);
359    }
360  };
361
362  struct CallStackRestore : EHScopeStack::Cleanup {
363    llvm::Value *Stack;
364    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
365    void Emit(CodeGenFunction &CGF, Flags flags) {
366      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
367      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
368      CGF.Builder.CreateCall(F, V);
369    }
370  };
371
372  struct ExtendGCLifetime : EHScopeStack::Cleanup {
373    const VarDecl &Var;
374    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
375
376    void Emit(CodeGenFunction &CGF, Flags flags) {
377      // Compute the address of the local variable, in case it's a
378      // byref or something.
379      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
380                      SourceLocation());
381      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
382      CGF.EmitExtendGCLifetime(value);
383    }
384  };
385
386  struct CallCleanupFunction : EHScopeStack::Cleanup {
387    llvm::Constant *CleanupFn;
388    const CGFunctionInfo &FnInfo;
389    const VarDecl &Var;
390
391    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
392                        const VarDecl *Var)
393      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
394
395    void Emit(CodeGenFunction &CGF, Flags flags) {
396      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
397                      SourceLocation());
398      // Compute the address of the local variable, in case it's a byref
399      // or something.
400      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
401
402      // In some cases, the type of the function argument will be different from
403      // the type of the pointer. An example of this is
404      // void f(void* arg);
405      // __attribute__((cleanup(f))) void *g;
406      //
407      // To fix this we insert a bitcast here.
408      QualType ArgTy = FnInfo.arg_begin()->type;
409      llvm::Value *Arg =
410        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
411
412      CallArgList Args;
413      Args.add(RValue::get(Arg),
414               CGF.getContext().getPointerType(Var.getType()));
415      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
416    }
417  };
418}
419
420/// EmitAutoVarWithLifetime - Does the setup required for an automatic
421/// variable with lifetime.
422static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
423                                    llvm::Value *addr,
424                                    Qualifiers::ObjCLifetime lifetime) {
425  switch (lifetime) {
426  case Qualifiers::OCL_None:
427    llvm_unreachable("present but none");
428
429  case Qualifiers::OCL_ExplicitNone:
430    // nothing to do
431    break;
432
433  case Qualifiers::OCL_Strong: {
434    CodeGenFunction::Destroyer &destroyer =
435      (var.hasAttr<ObjCPreciseLifetimeAttr>()
436       ? CodeGenFunction::destroyARCStrongPrecise
437       : CodeGenFunction::destroyARCStrongImprecise);
438
439    CleanupKind cleanupKind = CGF.getARCCleanupKind();
440    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
441                    cleanupKind & EHCleanup);
442    break;
443  }
444  case Qualifiers::OCL_Autoreleasing:
445    // nothing to do
446    break;
447
448  case Qualifiers::OCL_Weak:
449    // __weak objects always get EH cleanups; otherwise, exceptions
450    // could cause really nasty crashes instead of mere leaks.
451    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
452                    CodeGenFunction::destroyARCWeak,
453                    /*useEHCleanup*/ true);
454    break;
455  }
456}
457
458static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
459  if (const Expr *e = dyn_cast<Expr>(s)) {
460    // Skip the most common kinds of expressions that make
461    // hierarchy-walking expensive.
462    s = e = e->IgnoreParenCasts();
463
464    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
465      return (ref->getDecl() == &var);
466  }
467
468  for (Stmt::const_child_range children = s->children(); children; ++children)
469    // children might be null; as in missing decl or conditional of an if-stmt.
470    if ((*children) && isAccessedBy(var, *children))
471      return true;
472
473  return false;
474}
475
476static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
477  if (!decl) return false;
478  if (!isa<VarDecl>(decl)) return false;
479  const VarDecl *var = cast<VarDecl>(decl);
480  return isAccessedBy(*var, e);
481}
482
483static void drillIntoBlockVariable(CodeGenFunction &CGF,
484                                   LValue &lvalue,
485                                   const VarDecl *var) {
486  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
487}
488
489void CodeGenFunction::EmitScalarInit(const Expr *init,
490                                     const ValueDecl *D,
491                                     LValue lvalue,
492                                     bool capturedByInit) {
493  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
494  if (!lifetime) {
495    llvm::Value *value = EmitScalarExpr(init);
496    if (capturedByInit)
497      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
498    EmitStoreThroughLValue(RValue::get(value), lvalue);
499    return;
500  }
501
502  // If we're emitting a value with lifetime, we have to do the
503  // initialization *before* we leave the cleanup scopes.
504  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
505    enterFullExpression(ewc);
506    init = ewc->getSubExpr();
507  }
508  CodeGenFunction::RunCleanupsScope Scope(*this);
509
510  // We have to maintain the illusion that the variable is
511  // zero-initialized.  If the variable might be accessed in its
512  // initializer, zero-initialize before running the initializer, then
513  // actually perform the initialization with an assign.
514  bool accessedByInit = false;
515  if (lifetime != Qualifiers::OCL_ExplicitNone)
516    accessedByInit = (capturedByInit || isAccessedBy(D, init));
517  if (accessedByInit) {
518    LValue tempLV = lvalue;
519    // Drill down to the __block object if necessary.
520    if (capturedByInit) {
521      // We can use a simple GEP for this because it can't have been
522      // moved yet.
523      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
524                                   getByRefValueLLVMField(cast<VarDecl>(D))));
525    }
526
527    llvm::PointerType *ty
528      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
529    ty = cast<llvm::PointerType>(ty->getElementType());
530
531    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
532
533    // If __weak, we want to use a barrier under certain conditions.
534    if (lifetime == Qualifiers::OCL_Weak)
535      EmitARCInitWeak(tempLV.getAddress(), zero);
536
537    // Otherwise just do a simple store.
538    else
539      EmitStoreOfScalar(zero, tempLV);
540  }
541
542  // Emit the initializer.
543  llvm::Value *value = 0;
544
545  switch (lifetime) {
546  case Qualifiers::OCL_None:
547    llvm_unreachable("present but none");
548
549  case Qualifiers::OCL_ExplicitNone:
550    // nothing to do
551    value = EmitScalarExpr(init);
552    break;
553
554  case Qualifiers::OCL_Strong: {
555    value = EmitARCRetainScalarExpr(init);
556    break;
557  }
558
559  case Qualifiers::OCL_Weak: {
560    // No way to optimize a producing initializer into this.  It's not
561    // worth optimizing for, because the value will immediately
562    // disappear in the common case.
563    value = EmitScalarExpr(init);
564
565    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
566    if (accessedByInit)
567      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
568    else
569      EmitARCInitWeak(lvalue.getAddress(), value);
570    return;
571  }
572
573  case Qualifiers::OCL_Autoreleasing:
574    value = EmitARCRetainAutoreleaseScalarExpr(init);
575    break;
576  }
577
578  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
579
580  // If the variable might have been accessed by its initializer, we
581  // might have to initialize with a barrier.  We have to do this for
582  // both __weak and __strong, but __weak got filtered out above.
583  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
584    llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
585    EmitStoreOfScalar(value, lvalue);
586    EmitARCRelease(oldValue, /*precise*/ false);
587    return;
588  }
589
590  EmitStoreOfScalar(value, lvalue);
591}
592
593/// EmitScalarInit - Initialize the given lvalue with the given object.
594void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
595  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
596  if (!lifetime)
597    return EmitStoreThroughLValue(RValue::get(init), lvalue);
598
599  switch (lifetime) {
600  case Qualifiers::OCL_None:
601    llvm_unreachable("present but none");
602
603  case Qualifiers::OCL_ExplicitNone:
604    // nothing to do
605    break;
606
607  case Qualifiers::OCL_Strong:
608    init = EmitARCRetain(lvalue.getType(), init);
609    break;
610
611  case Qualifiers::OCL_Weak:
612    // Initialize and then skip the primitive store.
613    EmitARCInitWeak(lvalue.getAddress(), init);
614    return;
615
616  case Qualifiers::OCL_Autoreleasing:
617    init = EmitARCRetainAutorelease(lvalue.getType(), init);
618    break;
619  }
620
621  EmitStoreOfScalar(init, lvalue);
622}
623
624/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
625/// non-zero parts of the specified initializer with equal or fewer than
626/// NumStores scalar stores.
627static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
628                                                unsigned &NumStores) {
629  // Zero and Undef never requires any extra stores.
630  if (isa<llvm::ConstantAggregateZero>(Init) ||
631      isa<llvm::ConstantPointerNull>(Init) ||
632      isa<llvm::UndefValue>(Init))
633    return true;
634  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
635      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
636      isa<llvm::ConstantExpr>(Init))
637    return Init->isNullValue() || NumStores--;
638
639  // See if we can emit each element.
640  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
641    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
642      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
643      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
644        return false;
645    }
646    return true;
647  }
648
649  // Anything else is hard and scary.
650  return false;
651}
652
653/// emitStoresForInitAfterMemset - For inits that
654/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
655/// stores that would be required.
656static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
657                                         bool isVolatile, CGBuilderTy &Builder) {
658  // Zero doesn't require any stores.
659  if (isa<llvm::ConstantAggregateZero>(Init) ||
660      isa<llvm::ConstantPointerNull>(Init) ||
661      isa<llvm::UndefValue>(Init))
662    return;
663
664  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
665      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
666      isa<llvm::ConstantExpr>(Init)) {
667    if (!Init->isNullValue())
668      Builder.CreateStore(Init, Loc, isVolatile);
669    return;
670  }
671
672  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
673         "Unknown value type!");
674
675  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
676    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
677    if (Elt->isNullValue()) continue;
678
679    // Otherwise, get a pointer to the element and emit it.
680    emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
681                                 isVolatile, Builder);
682  }
683}
684
685
686/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
687/// plus some stores to initialize a local variable instead of using a memcpy
688/// from a constant global.  It is beneficial to use memset if the global is all
689/// zeros, or mostly zeros and large.
690static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
691                                                  uint64_t GlobalSize) {
692  // If a global is all zeros, always use a memset.
693  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
694
695
696  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
697  // do it if it will require 6 or fewer scalar stores.
698  // TODO: Should budget depends on the size?  Avoiding a large global warrants
699  // plopping in more stores.
700  unsigned StoreBudget = 6;
701  uint64_t SizeLimit = 32;
702
703  return GlobalSize > SizeLimit &&
704         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
705}
706
707
708/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
709/// variable declaration with auto, register, or no storage class specifier.
710/// These turn into simple stack objects, or GlobalValues depending on target.
711void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
712  AutoVarEmission emission = EmitAutoVarAlloca(D);
713  EmitAutoVarInit(emission);
714  EmitAutoVarCleanups(emission);
715}
716
717/// EmitAutoVarAlloca - Emit the alloca and debug information for a
718/// local variable.  Does not emit initalization or destruction.
719CodeGenFunction::AutoVarEmission
720CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
721  QualType Ty = D.getType();
722
723  AutoVarEmission emission(D);
724
725  bool isByRef = D.hasAttr<BlocksAttr>();
726  emission.IsByRef = isByRef;
727
728  CharUnits alignment = getContext().getDeclAlign(&D);
729  emission.Alignment = alignment;
730
731  // If the type is variably-modified, emit all the VLA sizes for it.
732  if (Ty->isVariablyModifiedType())
733    EmitVariablyModifiedType(Ty);
734
735  llvm::Value *DeclPtr;
736  if (Ty->isConstantSizeType()) {
737    if (!Target.useGlobalsForAutomaticVariables()) {
738      bool NRVO = getContext().getLangOptions().ElideConstructors &&
739                  D.isNRVOVariable();
740
741      // If this value is a POD array or struct with a statically
742      // determinable constant initializer, there are optimizations we can do.
743      //
744      // TODO: we should constant-evaluate any variable of literal type
745      // as long as it is initialized by a constant expression. Currently,
746      // isConstantInitializer produces wrong answers for structs with
747      // reference or bitfield members, and a few other cases, and checking
748      // for POD-ness protects us from some of these.
749      if (D.getInit() &&
750          (Ty->isArrayType() || Ty->isRecordType()) &&
751          (Ty.isPODType(getContext()) ||
752           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
753          D.getInit()->isConstantInitializer(getContext(), false)) {
754
755        // If the variable's a const type, and it's neither an NRVO
756        // candidate nor a __block variable and has no mutable members,
757        // emit it as a global instead.
758        if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() &&
759            !NRVO && !isByRef && Ty->isLiteralType()) {
760          EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
761
762          emission.Address = 0; // signal this condition to later callbacks
763          assert(emission.wasEmittedAsGlobal());
764          return emission;
765        }
766
767        // Otherwise, tell the initialization code that we're in this case.
768        emission.IsConstantAggregate = true;
769      }
770
771      // A normal fixed sized variable becomes an alloca in the entry block,
772      // unless it's an NRVO variable.
773      llvm::Type *LTy = ConvertTypeForMem(Ty);
774
775      if (NRVO) {
776        // The named return value optimization: allocate this variable in the
777        // return slot, so that we can elide the copy when returning this
778        // variable (C++0x [class.copy]p34).
779        DeclPtr = ReturnValue;
780
781        if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
782          if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
783            // Create a flag that is used to indicate when the NRVO was applied
784            // to this variable. Set it to zero to indicate that NRVO was not
785            // applied.
786            llvm::Value *Zero = Builder.getFalse();
787            llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
788            EnsureInsertPoint();
789            Builder.CreateStore(Zero, NRVOFlag);
790
791            // Record the NRVO flag for this variable.
792            NRVOFlags[&D] = NRVOFlag;
793            emission.NRVOFlag = NRVOFlag;
794          }
795        }
796      } else {
797        if (isByRef)
798          LTy = BuildByRefType(&D);
799
800        llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
801        Alloc->setName(D.getName());
802
803        CharUnits allocaAlignment = alignment;
804        if (isByRef)
805          allocaAlignment = std::max(allocaAlignment,
806              getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
807        Alloc->setAlignment(allocaAlignment.getQuantity());
808        DeclPtr = Alloc;
809      }
810    } else {
811      // Targets that don't support recursion emit locals as globals.
812      const char *Class =
813        D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
814      DeclPtr = CreateStaticVarDecl(D, Class,
815                                    llvm::GlobalValue::InternalLinkage);
816    }
817  } else {
818    EnsureInsertPoint();
819
820    if (!DidCallStackSave) {
821      // Save the stack.
822      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
823
824      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
825      llvm::Value *V = Builder.CreateCall(F);
826
827      Builder.CreateStore(V, Stack);
828
829      DidCallStackSave = true;
830
831      // Push a cleanup block and restore the stack there.
832      // FIXME: in general circumstances, this should be an EH cleanup.
833      EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
834    }
835
836    llvm::Value *elementCount;
837    QualType elementType;
838    llvm::tie(elementCount, elementType) = getVLASize(Ty);
839
840    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
841
842    // Allocate memory for the array.
843    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
844    vla->setAlignment(alignment.getQuantity());
845
846    DeclPtr = vla;
847  }
848
849  llvm::Value *&DMEntry = LocalDeclMap[&D];
850  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
851  DMEntry = DeclPtr;
852  emission.Address = DeclPtr;
853
854  // Emit debug info for local var declaration.
855  if (HaveInsertPoint())
856    if (CGDebugInfo *DI = getDebugInfo()) {
857      DI->setLocation(D.getLocation());
858      if (Target.useGlobalsForAutomaticVariables()) {
859        DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
860      } else
861        DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
862    }
863
864  if (D.hasAttr<AnnotateAttr>())
865      EmitVarAnnotations(&D, emission.Address);
866
867  return emission;
868}
869
870/// Determines whether the given __block variable is potentially
871/// captured by the given expression.
872static bool isCapturedBy(const VarDecl &var, const Expr *e) {
873  // Skip the most common kinds of expressions that make
874  // hierarchy-walking expensive.
875  e = e->IgnoreParenCasts();
876
877  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
878    const BlockDecl *block = be->getBlockDecl();
879    for (BlockDecl::capture_const_iterator i = block->capture_begin(),
880           e = block->capture_end(); i != e; ++i) {
881      if (i->getVariable() == &var)
882        return true;
883    }
884
885    // No need to walk into the subexpressions.
886    return false;
887  }
888
889  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
890    const CompoundStmt *CS = SE->getSubStmt();
891    for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
892	   BE = CS->body_end(); BI != BE; ++BI)
893      if (Expr *E = dyn_cast<Expr>((*BI))) {
894        if (isCapturedBy(var, E))
895            return true;
896      }
897      else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) {
898          // special case declarations
899          for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
900               I != E; ++I) {
901              if (VarDecl *VD = dyn_cast<VarDecl>((*I))) {
902                Expr *Init = VD->getInit();
903                if (Init && isCapturedBy(var, Init))
904                  return true;
905              }
906          }
907      }
908      else
909        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
910        // Later, provide code to poke into statements for capture analysis.
911        return true;
912    return false;
913  }
914
915  for (Stmt::const_child_range children = e->children(); children; ++children)
916    if (isCapturedBy(var, cast<Expr>(*children)))
917      return true;
918
919  return false;
920}
921
922/// \brief Determine whether the given initializer is trivial in the sense
923/// that it requires no code to be generated.
924static bool isTrivialInitializer(const Expr *Init) {
925  if (!Init)
926    return true;
927
928  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
929    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
930      if (Constructor->isTrivial() &&
931          Constructor->isDefaultConstructor() &&
932          !Construct->requiresZeroInitialization())
933        return true;
934
935  return false;
936}
937void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
938  assert(emission.Variable && "emission was not valid!");
939
940  // If this was emitted as a global constant, we're done.
941  if (emission.wasEmittedAsGlobal()) return;
942
943  const VarDecl &D = *emission.Variable;
944  QualType type = D.getType();
945
946  // If this local has an initializer, emit it now.
947  const Expr *Init = D.getInit();
948
949  // If we are at an unreachable point, we don't need to emit the initializer
950  // unless it contains a label.
951  if (!HaveInsertPoint()) {
952    if (!Init || !ContainsLabel(Init)) return;
953    EnsureInsertPoint();
954  }
955
956  // Initialize the structure of a __block variable.
957  if (emission.IsByRef)
958    emitByrefStructureInit(emission);
959
960  if (isTrivialInitializer(Init))
961    return;
962
963  CharUnits alignment = emission.Alignment;
964
965  // Check whether this is a byref variable that's potentially
966  // captured and moved by its own initializer.  If so, we'll need to
967  // emit the initializer first, then copy into the variable.
968  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
969
970  llvm::Value *Loc =
971    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
972
973  llvm::Constant *constant = 0;
974  if (emission.IsConstantAggregate) {
975    assert(!capturedByInit && "constant init contains a capturing block?");
976    constant = CGM.EmitConstantExpr(D.getInit(), type, this);
977  }
978
979  if (!constant) {
980    LValue lv = MakeAddrLValue(Loc, type, alignment);
981    lv.setNonGC(true);
982    return EmitExprAsInit(Init, &D, lv, capturedByInit);
983  }
984
985  // If this is a simple aggregate initialization, we can optimize it
986  // in various ways.
987  bool isVolatile = type.isVolatileQualified();
988
989  llvm::Value *SizeVal =
990    llvm::ConstantInt::get(IntPtrTy,
991                           getContext().getTypeSizeInChars(type).getQuantity());
992
993  llvm::Type *BP = Int8PtrTy;
994  if (Loc->getType() != BP)
995    Loc = Builder.CreateBitCast(Loc, BP);
996
997  // If the initializer is all or mostly zeros, codegen with memset then do
998  // a few stores afterward.
999  if (shouldUseMemSetPlusStoresToInitialize(constant,
1000                CGM.getTargetData().getTypeAllocSize(constant->getType()))) {
1001    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
1002                         alignment.getQuantity(), isVolatile);
1003    if (!constant->isNullValue()) {
1004      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
1005      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
1006    }
1007  } else {
1008    // Otherwise, create a temporary global with the initializer then
1009    // memcpy from the global to the alloca.
1010    std::string Name = GetStaticDeclName(*this, D, ".");
1011    llvm::GlobalVariable *GV =
1012      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1013                               llvm::GlobalValue::PrivateLinkage,
1014                               constant, Name, 0, false, 0);
1015    GV->setAlignment(alignment.getQuantity());
1016    GV->setUnnamedAddr(true);
1017
1018    llvm::Value *SrcPtr = GV;
1019    if (SrcPtr->getType() != BP)
1020      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1021
1022    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1023                         isVolatile);
1024  }
1025}
1026
1027/// Emit an expression as an initializer for a variable at the given
1028/// location.  The expression is not necessarily the normal
1029/// initializer for the variable, and the address is not necessarily
1030/// its normal location.
1031///
1032/// \param init the initializing expression
1033/// \param var the variable to act as if we're initializing
1034/// \param loc the address to initialize; its type is a pointer
1035///   to the LLVM mapping of the variable's type
1036/// \param alignment the alignment of the address
1037/// \param capturedByInit true if the variable is a __block variable
1038///   whose address is potentially changed by the initializer
1039void CodeGenFunction::EmitExprAsInit(const Expr *init,
1040                                     const ValueDecl *D,
1041                                     LValue lvalue,
1042                                     bool capturedByInit) {
1043  QualType type = D->getType();
1044
1045  if (type->isReferenceType()) {
1046    RValue rvalue = EmitReferenceBindingToExpr(init, D);
1047    if (capturedByInit)
1048      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1049    EmitStoreThroughLValue(rvalue, lvalue);
1050  } else if (!hasAggregateLLVMType(type)) {
1051    EmitScalarInit(init, D, lvalue, capturedByInit);
1052  } else if (type->isAnyComplexType()) {
1053    ComplexPairTy complex = EmitComplexExpr(init);
1054    if (capturedByInit)
1055      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1056    StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile());
1057  } else {
1058    // TODO: how can we delay here if D is captured by its initializer?
1059    EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1060                                              AggValueSlot::IsDestructed,
1061                                         AggValueSlot::DoesNotNeedGCBarriers,
1062                                              AggValueSlot::IsNotAliased));
1063  }
1064}
1065
1066/// Enter a destroy cleanup for the given local variable.
1067void CodeGenFunction::emitAutoVarTypeCleanup(
1068                            const CodeGenFunction::AutoVarEmission &emission,
1069                            QualType::DestructionKind dtorKind) {
1070  assert(dtorKind != QualType::DK_none);
1071
1072  // Note that for __block variables, we want to destroy the
1073  // original stack object, not the possibly forwarded object.
1074  llvm::Value *addr = emission.getObjectAddress(*this);
1075
1076  const VarDecl *var = emission.Variable;
1077  QualType type = var->getType();
1078
1079  CleanupKind cleanupKind = NormalAndEHCleanup;
1080  CodeGenFunction::Destroyer *destroyer = 0;
1081
1082  switch (dtorKind) {
1083  case QualType::DK_none:
1084    llvm_unreachable("no cleanup for trivially-destructible variable");
1085
1086  case QualType::DK_cxx_destructor:
1087    // If there's an NRVO flag on the emission, we need a different
1088    // cleanup.
1089    if (emission.NRVOFlag) {
1090      assert(!type->isArrayType());
1091      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1092      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1093                                               emission.NRVOFlag);
1094      return;
1095    }
1096    break;
1097
1098  case QualType::DK_objc_strong_lifetime:
1099    // Suppress cleanups for pseudo-strong variables.
1100    if (var->isARCPseudoStrong()) return;
1101
1102    // Otherwise, consider whether to use an EH cleanup or not.
1103    cleanupKind = getARCCleanupKind();
1104
1105    // Use the imprecise destroyer by default.
1106    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1107      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1108    break;
1109
1110  case QualType::DK_objc_weak_lifetime:
1111    break;
1112  }
1113
1114  // If we haven't chosen a more specific destroyer, use the default.
1115  if (!destroyer) destroyer = &getDestroyer(dtorKind);
1116
1117  // Use an EH cleanup in array destructors iff the destructor itself
1118  // is being pushed as an EH cleanup.
1119  bool useEHCleanup = (cleanupKind & EHCleanup);
1120  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1121                                     useEHCleanup);
1122}
1123
1124void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1125  assert(emission.Variable && "emission was not valid!");
1126
1127  // If this was emitted as a global constant, we're done.
1128  if (emission.wasEmittedAsGlobal()) return;
1129
1130  const VarDecl &D = *emission.Variable;
1131
1132  // Check the type for a cleanup.
1133  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1134    emitAutoVarTypeCleanup(emission, dtorKind);
1135
1136  // In GC mode, honor objc_precise_lifetime.
1137  if (getLangOptions().getGC() != LangOptions::NonGC &&
1138      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1139    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1140  }
1141
1142  // Handle the cleanup attribute.
1143  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1144    const FunctionDecl *FD = CA->getFunctionDecl();
1145
1146    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1147    assert(F && "Could not find function!");
1148
1149    const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
1150    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1151  }
1152
1153  // If this is a block variable, call _Block_object_destroy
1154  // (on the unforwarded address).
1155  if (emission.IsByRef)
1156    enterByrefCleanup(emission);
1157}
1158
1159CodeGenFunction::Destroyer &
1160CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1161  // This is surprisingly compiler-dependent.  GCC 4.2 can't bind
1162  // references to functions directly in returns, and using '*&foo'
1163  // confuses MSVC.  Luckily, the following code pattern works in both.
1164  Destroyer *destroyer = 0;
1165  switch (kind) {
1166  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1167  case QualType::DK_cxx_destructor:
1168    destroyer = &destroyCXXObject;
1169    break;
1170  case QualType::DK_objc_strong_lifetime:
1171    destroyer = &destroyARCStrongPrecise;
1172    break;
1173  case QualType::DK_objc_weak_lifetime:
1174    destroyer = &destroyARCWeak;
1175    break;
1176  }
1177  return *destroyer;
1178}
1179
1180/// pushDestroy - Push the standard destructor for the given type.
1181void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1182                                  llvm::Value *addr, QualType type) {
1183  assert(dtorKind && "cannot push destructor for trivial type");
1184
1185  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1186  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1187              cleanupKind & EHCleanup);
1188}
1189
1190void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1191                                  QualType type, Destroyer &destroyer,
1192                                  bool useEHCleanupForArray) {
1193  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1194                                     destroyer, useEHCleanupForArray);
1195}
1196
1197/// emitDestroy - Immediately perform the destruction of the given
1198/// object.
1199///
1200/// \param addr - the address of the object; a type*
1201/// \param type - the type of the object; if an array type, all
1202///   objects are destroyed in reverse order
1203/// \param destroyer - the function to call to destroy individual
1204///   elements
1205/// \param useEHCleanupForArray - whether an EH cleanup should be
1206///   used when destroying array elements, in case one of the
1207///   destructions throws an exception
1208void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1209                                  Destroyer &destroyer,
1210                                  bool useEHCleanupForArray) {
1211  const ArrayType *arrayType = getContext().getAsArrayType(type);
1212  if (!arrayType)
1213    return destroyer(*this, addr, type);
1214
1215  llvm::Value *begin = addr;
1216  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1217
1218  // Normally we have to check whether the array is zero-length.
1219  bool checkZeroLength = true;
1220
1221  // But if the array length is constant, we can suppress that.
1222  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1223    // ...and if it's constant zero, we can just skip the entire thing.
1224    if (constLength->isZero()) return;
1225    checkZeroLength = false;
1226  }
1227
1228  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1229  emitArrayDestroy(begin, end, type, destroyer,
1230                   checkZeroLength, useEHCleanupForArray);
1231}
1232
1233/// emitArrayDestroy - Destroys all the elements of the given array,
1234/// beginning from last to first.  The array cannot be zero-length.
1235///
1236/// \param begin - a type* denoting the first element of the array
1237/// \param end - a type* denoting one past the end of the array
1238/// \param type - the element type of the array
1239/// \param destroyer - the function to call to destroy elements
1240/// \param useEHCleanup - whether to push an EH cleanup to destroy
1241///   the remaining elements in case the destruction of a single
1242///   element throws
1243void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1244                                       llvm::Value *end,
1245                                       QualType type,
1246                                       Destroyer &destroyer,
1247                                       bool checkZeroLength,
1248                                       bool useEHCleanup) {
1249  assert(!type->isArrayType());
1250
1251  // The basic structure here is a do-while loop, because we don't
1252  // need to check for the zero-element case.
1253  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1254  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1255
1256  if (checkZeroLength) {
1257    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1258                                                "arraydestroy.isempty");
1259    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1260  }
1261
1262  // Enter the loop body, making that address the current address.
1263  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1264  EmitBlock(bodyBB);
1265  llvm::PHINode *elementPast =
1266    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1267  elementPast->addIncoming(end, entryBB);
1268
1269  // Shift the address back by one element.
1270  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1271  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1272                                                   "arraydestroy.element");
1273
1274  if (useEHCleanup)
1275    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1276
1277  // Perform the actual destruction there.
1278  destroyer(*this, element, type);
1279
1280  if (useEHCleanup)
1281    PopCleanupBlock();
1282
1283  // Check whether we've reached the end.
1284  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1285  Builder.CreateCondBr(done, doneBB, bodyBB);
1286  elementPast->addIncoming(element, Builder.GetInsertBlock());
1287
1288  // Done.
1289  EmitBlock(doneBB);
1290}
1291
1292/// Perform partial array destruction as if in an EH cleanup.  Unlike
1293/// emitArrayDestroy, the element type here may still be an array type.
1294static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1295                                    llvm::Value *begin, llvm::Value *end,
1296                                    QualType type,
1297                                    CodeGenFunction::Destroyer &destroyer) {
1298  // If the element type is itself an array, drill down.
1299  unsigned arrayDepth = 0;
1300  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1301    // VLAs don't require a GEP index to walk into.
1302    if (!isa<VariableArrayType>(arrayType))
1303      arrayDepth++;
1304    type = arrayType->getElementType();
1305  }
1306
1307  if (arrayDepth) {
1308    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1309
1310    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1311    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1312    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1313  }
1314
1315  // Destroy the array.  We don't ever need an EH cleanup because we
1316  // assume that we're in an EH cleanup ourselves, so a throwing
1317  // destructor causes an immediate terminate.
1318  CGF.emitArrayDestroy(begin, end, type, destroyer,
1319                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1320}
1321
1322namespace {
1323  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1324  /// array destroy where the end pointer is regularly determined and
1325  /// does not need to be loaded from a local.
1326  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1327    llvm::Value *ArrayBegin;
1328    llvm::Value *ArrayEnd;
1329    QualType ElementType;
1330    CodeGenFunction::Destroyer &Destroyer;
1331  public:
1332    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1333                               QualType elementType,
1334                               CodeGenFunction::Destroyer *destroyer)
1335      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1336        ElementType(elementType), Destroyer(*destroyer) {}
1337
1338    void Emit(CodeGenFunction &CGF, Flags flags) {
1339      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1340                              ElementType, Destroyer);
1341    }
1342  };
1343
1344  /// IrregularPartialArrayDestroy - a cleanup which performs a
1345  /// partial array destroy where the end pointer is irregularly
1346  /// determined and must be loaded from a local.
1347  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1348    llvm::Value *ArrayBegin;
1349    llvm::Value *ArrayEndPointer;
1350    QualType ElementType;
1351    CodeGenFunction::Destroyer &Destroyer;
1352  public:
1353    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1354                                 llvm::Value *arrayEndPointer,
1355                                 QualType elementType,
1356                                 CodeGenFunction::Destroyer *destroyer)
1357      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1358        ElementType(elementType), Destroyer(*destroyer) {}
1359
1360    void Emit(CodeGenFunction &CGF, Flags flags) {
1361      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1362      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1363                              ElementType, Destroyer);
1364    }
1365  };
1366}
1367
1368/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1369/// already-constructed elements of the given array.  The cleanup
1370/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1371///
1372/// \param elementType - the immediate element type of the array;
1373///   possibly still an array type
1374/// \param array - a value of type elementType*
1375/// \param destructionKind - the kind of destruction required
1376/// \param initializedElementCount - a value of type size_t* holding
1377///   the number of successfully-constructed elements
1378void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1379                                                 llvm::Value *arrayEndPointer,
1380                                                       QualType elementType,
1381                                                       Destroyer &destroyer) {
1382  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1383                                                    arrayBegin, arrayEndPointer,
1384                                                    elementType, &destroyer);
1385}
1386
1387/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1388/// already-constructed elements of the given array.  The cleanup
1389/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1390///
1391/// \param elementType - the immediate element type of the array;
1392///   possibly still an array type
1393/// \param array - a value of type elementType*
1394/// \param destructionKind - the kind of destruction required
1395/// \param initializedElementCount - a value of type size_t* holding
1396///   the number of successfully-constructed elements
1397void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1398                                                     llvm::Value *arrayEnd,
1399                                                     QualType elementType,
1400                                                     Destroyer &destroyer) {
1401  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1402                                                  arrayBegin, arrayEnd,
1403                                                  elementType, &destroyer);
1404}
1405
1406namespace {
1407  /// A cleanup to perform a release of an object at the end of a
1408  /// function.  This is used to balance out the incoming +1 of a
1409  /// ns_consumed argument when we can't reasonably do that just by
1410  /// not doing the initial retain for a __block argument.
1411  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1412    ConsumeARCParameter(llvm::Value *param) : Param(param) {}
1413
1414    llvm::Value *Param;
1415
1416    void Emit(CodeGenFunction &CGF, Flags flags) {
1417      CGF.EmitARCRelease(Param, /*precise*/ false);
1418    }
1419  };
1420}
1421
1422/// Emit an alloca (or GlobalValue depending on target)
1423/// for the specified parameter and set up LocalDeclMap.
1424void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1425                                   unsigned ArgNo) {
1426  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1427  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1428         "Invalid argument to EmitParmDecl");
1429
1430  Arg->setName(D.getName());
1431
1432  // Use better IR generation for certain implicit parameters.
1433  if (isa<ImplicitParamDecl>(D)) {
1434    // The only implicit argument a block has is its literal.
1435    if (BlockInfo) {
1436      LocalDeclMap[&D] = Arg;
1437
1438      if (CGDebugInfo *DI = getDebugInfo()) {
1439        DI->setLocation(D.getLocation());
1440        DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
1441      }
1442
1443      return;
1444    }
1445  }
1446
1447  QualType Ty = D.getType();
1448
1449  llvm::Value *DeclPtr;
1450  // If this is an aggregate or variable sized value, reuse the input pointer.
1451  if (!Ty->isConstantSizeType() ||
1452      CodeGenFunction::hasAggregateLLVMType(Ty)) {
1453    DeclPtr = Arg;
1454  } else {
1455    // Otherwise, create a temporary to hold the value.
1456    llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1457                                               D.getName() + ".addr");
1458    Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
1459    DeclPtr = Alloc;
1460
1461    bool doStore = true;
1462
1463    Qualifiers qs = Ty.getQualifiers();
1464
1465    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1466      // We honor __attribute__((ns_consumed)) for types with lifetime.
1467      // For __strong, it's handled by just skipping the initial retain;
1468      // otherwise we have to balance out the initial +1 with an extra
1469      // cleanup to do the release at the end of the function.
1470      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1471
1472      // 'self' is always formally __strong, but if this is not an
1473      // init method then we don't want to retain it.
1474      if (D.isARCPseudoStrong()) {
1475        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1476        assert(&D == method->getSelfDecl());
1477        assert(lt == Qualifiers::OCL_Strong);
1478        assert(qs.hasConst());
1479        assert(method->getMethodFamily() != OMF_init);
1480        (void) method;
1481        lt = Qualifiers::OCL_ExplicitNone;
1482      }
1483
1484      if (lt == Qualifiers::OCL_Strong) {
1485        if (!isConsumed)
1486          // Don't use objc_retainBlock for block pointers, because we
1487          // don't want to Block_copy something just because we got it
1488          // as a parameter.
1489          Arg = EmitARCRetainNonBlock(Arg);
1490      } else {
1491        // Push the cleanup for a consumed parameter.
1492        if (isConsumed)
1493          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg);
1494
1495        if (lt == Qualifiers::OCL_Weak) {
1496          EmitARCInitWeak(DeclPtr, Arg);
1497          doStore = false; // The weak init is a store, no need to do two
1498        }
1499      }
1500
1501      // Enter the cleanup scope.
1502      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1503    }
1504
1505    // Store the initial value into the alloca.
1506    if (doStore) {
1507      LValue lv = MakeAddrLValue(DeclPtr, Ty,
1508                                 getContext().getDeclAlign(&D));
1509      EmitStoreOfScalar(Arg, lv);
1510    }
1511  }
1512
1513  llvm::Value *&DMEntry = LocalDeclMap[&D];
1514  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
1515  DMEntry = DeclPtr;
1516
1517  // Emit debug info for param declaration.
1518  if (CGDebugInfo *DI = getDebugInfo())
1519    DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1520
1521  if (D.hasAttr<AnnotateAttr>())
1522      EmitVarAnnotations(&D, DeclPtr);
1523}
1524