CGDecl.cpp revision c3e81e78e8b1d5ba3df2d5801841b4fbc53c1bd8 
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 "CodeGenFunction.h"
15#include "CGDebugInfo.h"
16#include "CGOpenCLRuntime.h"
17#include "CodeGenModule.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/IR/DataLayout.h"
26#include "llvm/IR/GlobalVariable.h"
27#include "llvm/IR/Intrinsics.h"
28#include "llvm/IR/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::MSProperty:
49  case Decl::IndirectField:
50  case Decl::ObjCIvar:
51  case Decl::ObjCAtDefsField:
52  case Decl::ParmVar:
53  case Decl::ImplicitParam:
54  case Decl::ClassTemplate:
55  case Decl::FunctionTemplate:
56  case Decl::TypeAliasTemplate:
57  case Decl::TemplateTemplateParm:
58  case Decl::ObjCMethod:
59  case Decl::ObjCCategory:
60  case Decl::ObjCProtocol:
61  case Decl::ObjCInterface:
62  case Decl::ObjCCategoryImpl:
63  case Decl::ObjCImplementation:
64  case Decl::ObjCProperty:
65  case Decl::ObjCCompatibleAlias:
66  case Decl::AccessSpec:
67  case Decl::LinkageSpec:
68  case Decl::ObjCPropertyImpl:
69  case Decl::FileScopeAsm:
70  case Decl::Friend:
71  case Decl::FriendTemplate:
72  case Decl::Block:
73  case Decl::Captured:
74  case Decl::ClassScopeFunctionSpecialization:
75    llvm_unreachable("Declaration should not be in declstmts!");
76  case Decl::Function:  // void X();
77  case Decl::Record:    // struct/union/class X;
78  case Decl::Enum:      // enum X;
79  case Decl::EnumConstant: // enum ? { X = ? }
80  case Decl::CXXRecord: // struct/union/class X; [C++]
81  case Decl::Using:          // using X; [C++]
82  case Decl::UsingShadow:
83  case Decl::UsingDirective: // using namespace X; [C++]
84  case Decl::NamespaceAlias:
85  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
86  case Decl::Label:        // __label__ x;
87  case Decl::Import:
88  case Decl::OMPThreadPrivate:
89  case Decl::Empty:
90    // None of these decls require codegen support.
91    return;
92
93  case Decl::Var: {
94    const VarDecl &VD = cast<VarDecl>(D);
95    assert(VD.isLocalVarDecl() &&
96           "Should not see file-scope variables inside a function!");
97    return EmitVarDecl(VD);
98  }
99
100  case Decl::Typedef:      // typedef int X;
101  case Decl::TypeAlias: {  // using X = int; [C++0x]
102    const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
103    QualType Ty = TD.getUnderlyingType();
104
105    if (Ty->isVariablyModifiedType())
106      EmitVariablyModifiedType(Ty);
107  }
108  }
109}
110
111/// EmitVarDecl - This method handles emission of any variable declaration
112/// inside a function, including static vars etc.
113void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
114  switch (D.getStorageClass()) {
115  case SC_None:
116  case SC_Auto:
117  case SC_Register:
118    return EmitAutoVarDecl(D);
119  case SC_Static: {
120    llvm::GlobalValue::LinkageTypes Linkage =
121      llvm::GlobalValue::InternalLinkage;
122
123    // If the function definition has some sort of weak linkage, its
124    // static variables should also be weak so that they get properly
125    // uniqued.  We can't do this in C, though, because there's no
126    // standard way to agree on which variables are the same (i.e.
127    // there's no mangling).
128    if (getLangOpts().CPlusPlus)
129      if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
130        Linkage = CurFn->getLinkage();
131
132    return EmitStaticVarDecl(D, Linkage);
133  }
134  case SC_Extern:
135  case SC_PrivateExtern:
136    // Don't emit it now, allow it to be emitted lazily on its first use.
137    return;
138  case SC_OpenCLWorkGroupLocal:
139    return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
140  }
141
142  llvm_unreachable("Unknown storage class");
143}
144
145static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
146                                     const char *Separator) {
147  CodeGenModule &CGM = CGF.CGM;
148  if (CGF.getLangOpts().CPlusPlus) {
149    StringRef Name = CGM.getMangledName(&D);
150    return Name.str();
151  }
152
153  std::string ContextName;
154  if (!CGF.CurFuncDecl) {
155    // Better be in a block declared in global scope.
156    const NamedDecl *ND = cast<NamedDecl>(&D);
157    const DeclContext *DC = ND->getDeclContext();
158    if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
159      MangleBuffer Name;
160      CGM.getBlockMangledName(GlobalDecl(), Name, BD);
161      ContextName = Name.getString();
162    }
163    else
164      llvm_unreachable("Unknown context for block static var decl");
165  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
166    StringRef Name = CGM.getMangledName(FD);
167    ContextName = Name.str();
168  } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
169    ContextName = CGF.CurFn->getName();
170  else
171    llvm_unreachable("Unknown context for static var decl");
172
173  return ContextName + Separator + D.getNameAsString();
174}
175
176llvm::GlobalVariable *
177CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
178                                     const char *Separator,
179                                     llvm::GlobalValue::LinkageTypes Linkage) {
180  QualType Ty = D.getType();
181  assert(Ty->isConstantSizeType() && "VLAs can't be static");
182
183  // Use the label if the variable is renamed with the asm-label extension.
184  std::string Name;
185  if (D.hasAttr<AsmLabelAttr>())
186    Name = CGM.getMangledName(&D);
187  else
188    Name = GetStaticDeclName(*this, D, Separator);
189
190  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
191  unsigned AddrSpace =
192   CGM.GetGlobalVarAddressSpace(&D, CGM.getContext().getTargetAddressSpace(Ty));
193  llvm::GlobalVariable *GV =
194    new llvm::GlobalVariable(CGM.getModule(), LTy,
195                             Ty.isConstant(getContext()), Linkage,
196                             CGM.EmitNullConstant(D.getType()), Name, 0,
197                             llvm::GlobalVariable::NotThreadLocal,
198                             AddrSpace);
199  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
200  if (Linkage != llvm::GlobalValue::InternalLinkage)
201    GV->setVisibility(CurFn->getVisibility());
202
203  if (D.getTLSKind())
204    CGM.setTLSMode(GV, D);
205
206  return GV;
207}
208
209/// hasNontrivialDestruction - Determine whether a type's destruction is
210/// non-trivial. If so, and the variable uses static initialization, we must
211/// register its destructor to run on exit.
212static bool hasNontrivialDestruction(QualType T) {
213  CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
214  return RD && !RD->hasTrivialDestructor();
215}
216
217/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
218/// global variable that has already been created for it.  If the initializer
219/// has a different type than GV does, this may free GV and return a different
220/// one.  Otherwise it just returns GV.
221llvm::GlobalVariable *
222CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
223                                               llvm::GlobalVariable *GV) {
224  llvm::Constant *Init = CGM.EmitConstantInit(D, this);
225
226  // If constant emission failed, then this should be a C++ static
227  // initializer.
228  if (!Init) {
229    if (!getLangOpts().CPlusPlus)
230      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
231    else if (Builder.GetInsertBlock()) {
232      // Since we have a static initializer, this global variable can't
233      // be constant.
234      GV->setConstant(false);
235
236      EmitCXXGuardedInit(D, GV, /*PerformInit*/true);
237    }
238    return GV;
239  }
240
241  // The initializer may differ in type from the global. Rewrite
242  // the global to match the initializer.  (We have to do this
243  // because some types, like unions, can't be completely represented
244  // in the LLVM type system.)
245  if (GV->getType()->getElementType() != Init->getType()) {
246    llvm::GlobalVariable *OldGV = GV;
247
248    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
249                                  OldGV->isConstant(),
250                                  OldGV->getLinkage(), Init, "",
251                                  /*InsertBefore*/ OldGV,
252                                  OldGV->getThreadLocalMode(),
253                           CGM.getContext().getTargetAddressSpace(D.getType()));
254    GV->setVisibility(OldGV->getVisibility());
255
256    // Steal the name of the old global
257    GV->takeName(OldGV);
258
259    // Replace all uses of the old global with the new global
260    llvm::Constant *NewPtrForOldDecl =
261    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
262    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
263
264    // Erase the old global, since it is no longer used.
265    OldGV->eraseFromParent();
266  }
267
268  GV->setConstant(CGM.isTypeConstant(D.getType(), true));
269  GV->setInitializer(Init);
270
271  if (hasNontrivialDestruction(D.getType())) {
272    // We have a constant initializer, but a nontrivial destructor. We still
273    // need to perform a guarded "initialization" in order to register the
274    // destructor.
275    EmitCXXGuardedInit(D, GV, /*PerformInit*/false);
276  }
277
278  return GV;
279}
280
281void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
282                                      llvm::GlobalValue::LinkageTypes Linkage) {
283  llvm::Value *&DMEntry = LocalDeclMap[&D];
284  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
285
286  // Check to see if we already have a global variable for this
287  // declaration.  This can happen when double-emitting function
288  // bodies, e.g. with complete and base constructors.
289  llvm::Constant *addr =
290    CGM.getStaticLocalDeclAddress(&D);
291
292  llvm::GlobalVariable *var;
293  if (addr) {
294    var = cast<llvm::GlobalVariable>(addr->stripPointerCasts());
295  } else {
296    addr = var = CreateStaticVarDecl(D, ".", Linkage);
297  }
298
299  // Store into LocalDeclMap before generating initializer to handle
300  // circular references.
301  DMEntry = addr;
302  CGM.setStaticLocalDeclAddress(&D, addr);
303
304  // We can't have a VLA here, but we can have a pointer to a VLA,
305  // even though that doesn't really make any sense.
306  // Make sure to evaluate VLA bounds now so that we have them for later.
307  if (D.getType()->isVariablyModifiedType())
308    EmitVariablyModifiedType(D.getType());
309
310  // Save the type in case adding the initializer forces a type change.
311  llvm::Type *expectedType = addr->getType();
312
313  // If this value has an initializer, emit it.
314  if (D.getInit())
315    var = AddInitializerToStaticVarDecl(D, var);
316
317  var->setAlignment(getContext().getDeclAlign(&D).getQuantity());
318
319  if (D.hasAttr<AnnotateAttr>())
320    CGM.AddGlobalAnnotations(&D, var);
321
322  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
323    var->setSection(SA->getName());
324
325  if (D.hasAttr<UsedAttr>())
326    CGM.AddUsedGlobal(var);
327
328  // We may have to cast the constant because of the initializer
329  // mismatch above.
330  //
331  // FIXME: It is really dangerous to store this in the map; if anyone
332  // RAUW's the GV uses of this constant will be invalid.
333  llvm::Constant *castedAddr = llvm::ConstantExpr::getBitCast(var, expectedType);
334  DMEntry = castedAddr;
335  CGM.setStaticLocalDeclAddress(&D, castedAddr);
336
337  // Emit global variable debug descriptor for static vars.
338  CGDebugInfo *DI = getDebugInfo();
339  if (DI &&
340      CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo) {
341    DI->setLocation(D.getLocation());
342    DI->EmitGlobalVariable(var, &D);
343  }
344}
345
346namespace {
347  struct DestroyObject : EHScopeStack::Cleanup {
348    DestroyObject(llvm::Value *addr, QualType type,
349                  CodeGenFunction::Destroyer *destroyer,
350                  bool useEHCleanupForArray)
351      : addr(addr), type(type), destroyer(destroyer),
352        useEHCleanupForArray(useEHCleanupForArray) {}
353
354    llvm::Value *addr;
355    QualType type;
356    CodeGenFunction::Destroyer *destroyer;
357    bool useEHCleanupForArray;
358
359    void Emit(CodeGenFunction &CGF, Flags flags) {
360      // Don't use an EH cleanup recursively from an EH cleanup.
361      bool useEHCleanupForArray =
362        flags.isForNormalCleanup() && this->useEHCleanupForArray;
363
364      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
365    }
366  };
367
368  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
369    DestroyNRVOVariable(llvm::Value *addr,
370                        const CXXDestructorDecl *Dtor,
371                        llvm::Value *NRVOFlag)
372      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
373
374    const CXXDestructorDecl *Dtor;
375    llvm::Value *NRVOFlag;
376    llvm::Value *Loc;
377
378    void Emit(CodeGenFunction &CGF, Flags flags) {
379      // Along the exceptions path we always execute the dtor.
380      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
381
382      llvm::BasicBlock *SkipDtorBB = 0;
383      if (NRVO) {
384        // If we exited via NRVO, we skip the destructor call.
385        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
386        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
387        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
388        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
389        CGF.EmitBlock(RunDtorBB);
390      }
391
392      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
393                                /*ForVirtualBase=*/false,
394                                /*Delegating=*/false,
395                                Loc);
396
397      if (NRVO) CGF.EmitBlock(SkipDtorBB);
398    }
399  };
400
401  struct CallStackRestore : EHScopeStack::Cleanup {
402    llvm::Value *Stack;
403    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
404    void Emit(CodeGenFunction &CGF, Flags flags) {
405      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
406      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
407      CGF.Builder.CreateCall(F, V);
408    }
409  };
410
411  struct ExtendGCLifetime : EHScopeStack::Cleanup {
412    const VarDecl &Var;
413    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
414
415    void Emit(CodeGenFunction &CGF, Flags flags) {
416      // Compute the address of the local variable, in case it's a
417      // byref or something.
418      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
419                      Var.getType(), VK_LValue, SourceLocation());
420      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
421      CGF.EmitExtendGCLifetime(value);
422    }
423  };
424
425  struct CallCleanupFunction : EHScopeStack::Cleanup {
426    llvm::Constant *CleanupFn;
427    const CGFunctionInfo &FnInfo;
428    const VarDecl &Var;
429
430    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
431                        const VarDecl *Var)
432      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
433
434    void Emit(CodeGenFunction &CGF, Flags flags) {
435      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
436                      Var.getType(), VK_LValue, SourceLocation());
437      // Compute the address of the local variable, in case it's a byref
438      // or something.
439      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
440
441      // In some cases, the type of the function argument will be different from
442      // the type of the pointer. An example of this is
443      // void f(void* arg);
444      // __attribute__((cleanup(f))) void *g;
445      //
446      // To fix this we insert a bitcast here.
447      QualType ArgTy = FnInfo.arg_begin()->type;
448      llvm::Value *Arg =
449        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
450
451      CallArgList Args;
452      Args.add(RValue::get(Arg),
453               CGF.getContext().getPointerType(Var.getType()));
454      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
455    }
456  };
457
458  /// A cleanup to call @llvm.lifetime.end.
459  class CallLifetimeEnd : public EHScopeStack::Cleanup {
460    llvm::Value *Addr;
461    llvm::Value *Size;
462  public:
463    CallLifetimeEnd(llvm::Value *addr, llvm::Value *size)
464      : Addr(addr), Size(size) {}
465
466    void Emit(CodeGenFunction &CGF, Flags flags) {
467      llvm::Value *castAddr = CGF.Builder.CreateBitCast(Addr, CGF.Int8PtrTy);
468      CGF.Builder.CreateCall2(CGF.CGM.getLLVMLifetimeEndFn(),
469                              Size, castAddr)
470        ->setDoesNotThrow();
471    }
472  };
473}
474
475/// EmitAutoVarWithLifetime - Does the setup required for an automatic
476/// variable with lifetime.
477static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
478                                    llvm::Value *addr,
479                                    Qualifiers::ObjCLifetime lifetime) {
480  switch (lifetime) {
481  case Qualifiers::OCL_None:
482    llvm_unreachable("present but none");
483
484  case Qualifiers::OCL_ExplicitNone:
485    // nothing to do
486    break;
487
488  case Qualifiers::OCL_Strong: {
489    CodeGenFunction::Destroyer *destroyer =
490      (var.hasAttr<ObjCPreciseLifetimeAttr>()
491       ? CodeGenFunction::destroyARCStrongPrecise
492       : CodeGenFunction::destroyARCStrongImprecise);
493
494    CleanupKind cleanupKind = CGF.getARCCleanupKind();
495    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
496                    cleanupKind & EHCleanup);
497    break;
498  }
499  case Qualifiers::OCL_Autoreleasing:
500    // nothing to do
501    break;
502
503  case Qualifiers::OCL_Weak:
504    // __weak objects always get EH cleanups; otherwise, exceptions
505    // could cause really nasty crashes instead of mere leaks.
506    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
507                    CodeGenFunction::destroyARCWeak,
508                    /*useEHCleanup*/ true);
509    break;
510  }
511}
512
513static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
514  if (const Expr *e = dyn_cast<Expr>(s)) {
515    // Skip the most common kinds of expressions that make
516    // hierarchy-walking expensive.
517    s = e = e->IgnoreParenCasts();
518
519    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
520      return (ref->getDecl() == &var);
521    if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
522      const BlockDecl *block = be->getBlockDecl();
523      for (BlockDecl::capture_const_iterator i = block->capture_begin(),
524           e = block->capture_end(); i != e; ++i) {
525        if (i->getVariable() == &var)
526          return true;
527      }
528    }
529  }
530
531  for (Stmt::const_child_range children = s->children(); children; ++children)
532    // children might be null; as in missing decl or conditional of an if-stmt.
533    if ((*children) && isAccessedBy(var, *children))
534      return true;
535
536  return false;
537}
538
539static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
540  if (!decl) return false;
541  if (!isa<VarDecl>(decl)) return false;
542  const VarDecl *var = cast<VarDecl>(decl);
543  return isAccessedBy(*var, e);
544}
545
546static void drillIntoBlockVariable(CodeGenFunction &CGF,
547                                   LValue &lvalue,
548                                   const VarDecl *var) {
549  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
550}
551
552void CodeGenFunction::EmitScalarInit(const Expr *init,
553                                     const ValueDecl *D,
554                                     LValue lvalue,
555                                     bool capturedByInit) {
556  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
557  if (!lifetime) {
558    llvm::Value *value = EmitScalarExpr(init);
559    if (capturedByInit)
560      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
561    EmitStoreThroughLValue(RValue::get(value), lvalue, true);
562    return;
563  }
564
565  // If we're emitting a value with lifetime, we have to do the
566  // initialization *before* we leave the cleanup scopes.
567  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
568    enterFullExpression(ewc);
569    init = ewc->getSubExpr();
570  }
571  CodeGenFunction::RunCleanupsScope Scope(*this);
572
573  // We have to maintain the illusion that the variable is
574  // zero-initialized.  If the variable might be accessed in its
575  // initializer, zero-initialize before running the initializer, then
576  // actually perform the initialization with an assign.
577  bool accessedByInit = false;
578  if (lifetime != Qualifiers::OCL_ExplicitNone)
579    accessedByInit = (capturedByInit || isAccessedBy(D, init));
580  if (accessedByInit) {
581    LValue tempLV = lvalue;
582    // Drill down to the __block object if necessary.
583    if (capturedByInit) {
584      // We can use a simple GEP for this because it can't have been
585      // moved yet.
586      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
587                                   getByRefValueLLVMField(cast<VarDecl>(D))));
588    }
589
590    llvm::PointerType *ty
591      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
592    ty = cast<llvm::PointerType>(ty->getElementType());
593
594    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
595
596    // If __weak, we want to use a barrier under certain conditions.
597    if (lifetime == Qualifiers::OCL_Weak)
598      EmitARCInitWeak(tempLV.getAddress(), zero);
599
600    // Otherwise just do a simple store.
601    else
602      EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true);
603  }
604
605  // Emit the initializer.
606  llvm::Value *value = 0;
607
608  switch (lifetime) {
609  case Qualifiers::OCL_None:
610    llvm_unreachable("present but none");
611
612  case Qualifiers::OCL_ExplicitNone:
613    // nothing to do
614    value = EmitScalarExpr(init);
615    break;
616
617  case Qualifiers::OCL_Strong: {
618    value = EmitARCRetainScalarExpr(init);
619    break;
620  }
621
622  case Qualifiers::OCL_Weak: {
623    // No way to optimize a producing initializer into this.  It's not
624    // worth optimizing for, because the value will immediately
625    // disappear in the common case.
626    value = EmitScalarExpr(init);
627
628    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
629    if (accessedByInit)
630      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
631    else
632      EmitARCInitWeak(lvalue.getAddress(), value);
633    return;
634  }
635
636  case Qualifiers::OCL_Autoreleasing:
637    value = EmitARCRetainAutoreleaseScalarExpr(init);
638    break;
639  }
640
641  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
642
643  // If the variable might have been accessed by its initializer, we
644  // might have to initialize with a barrier.  We have to do this for
645  // both __weak and __strong, but __weak got filtered out above.
646  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
647    llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
648    EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
649    EmitARCRelease(oldValue, ARCImpreciseLifetime);
650    return;
651  }
652
653  EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
654}
655
656/// EmitScalarInit - Initialize the given lvalue with the given object.
657void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
658  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
659  if (!lifetime)
660    return EmitStoreThroughLValue(RValue::get(init), lvalue, true);
661
662  switch (lifetime) {
663  case Qualifiers::OCL_None:
664    llvm_unreachable("present but none");
665
666  case Qualifiers::OCL_ExplicitNone:
667    // nothing to do
668    break;
669
670  case Qualifiers::OCL_Strong:
671    init = EmitARCRetain(lvalue.getType(), init);
672    break;
673
674  case Qualifiers::OCL_Weak:
675    // Initialize and then skip the primitive store.
676    EmitARCInitWeak(lvalue.getAddress(), init);
677    return;
678
679  case Qualifiers::OCL_Autoreleasing:
680    init = EmitARCRetainAutorelease(lvalue.getType(), init);
681    break;
682  }
683
684  EmitStoreOfScalar(init, lvalue, /* isInitialization */ true);
685}
686
687/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
688/// non-zero parts of the specified initializer with equal or fewer than
689/// NumStores scalar stores.
690static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
691                                                unsigned &NumStores) {
692  // Zero and Undef never requires any extra stores.
693  if (isa<llvm::ConstantAggregateZero>(Init) ||
694      isa<llvm::ConstantPointerNull>(Init) ||
695      isa<llvm::UndefValue>(Init))
696    return true;
697  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
698      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
699      isa<llvm::ConstantExpr>(Init))
700    return Init->isNullValue() || NumStores--;
701
702  // See if we can emit each element.
703  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
704    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
705      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
706      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
707        return false;
708    }
709    return true;
710  }
711
712  if (llvm::ConstantDataSequential *CDS =
713        dyn_cast<llvm::ConstantDataSequential>(Init)) {
714    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
715      llvm::Constant *Elt = CDS->getElementAsConstant(i);
716      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
717        return false;
718    }
719    return true;
720  }
721
722  // Anything else is hard and scary.
723  return false;
724}
725
726/// emitStoresForInitAfterMemset - For inits that
727/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
728/// stores that would be required.
729static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
730                                         bool isVolatile, CGBuilderTy &Builder) {
731  assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) &&
732         "called emitStoresForInitAfterMemset for zero or undef value.");
733
734  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
735      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
736      isa<llvm::ConstantExpr>(Init)) {
737    Builder.CreateStore(Init, Loc, isVolatile);
738    return;
739  }
740
741  if (llvm::ConstantDataSequential *CDS =
742        dyn_cast<llvm::ConstantDataSequential>(Init)) {
743    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
744      llvm::Constant *Elt = CDS->getElementAsConstant(i);
745
746      // If necessary, get a pointer to the element and emit it.
747      if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
748        emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
749                                     isVolatile, Builder);
750    }
751    return;
752  }
753
754  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
755         "Unknown value type!");
756
757  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
758    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
759
760    // If necessary, get a pointer to the element and emit it.
761    if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
762      emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
763                                   isVolatile, Builder);
764  }
765}
766
767
768/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
769/// plus some stores to initialize a local variable instead of using a memcpy
770/// from a constant global.  It is beneficial to use memset if the global is all
771/// zeros, or mostly zeros and large.
772static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
773                                                  uint64_t GlobalSize) {
774  // If a global is all zeros, always use a memset.
775  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
776
777  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
778  // do it if it will require 6 or fewer scalar stores.
779  // TODO: Should budget depends on the size?  Avoiding a large global warrants
780  // plopping in more stores.
781  unsigned StoreBudget = 6;
782  uint64_t SizeLimit = 32;
783
784  return GlobalSize > SizeLimit &&
785         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
786}
787
788/// Should we use the LLVM lifetime intrinsics for the given local variable?
789static bool shouldUseLifetimeMarkers(CodeGenFunction &CGF, const VarDecl &D,
790                                     unsigned Size) {
791  // Always emit lifetime markers in -fsanitize=use-after-scope mode.
792  if (CGF.getLangOpts().Sanitize.UseAfterScope)
793    return true;
794  // For now, only in optimized builds.
795  if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0)
796    return false;
797
798  // Limit the size of marked objects to 32 bytes. We don't want to increase
799  // compile time by marking tiny objects.
800  unsigned SizeThreshold = 32;
801
802  return Size > SizeThreshold;
803}
804
805
806/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
807/// variable declaration with auto, register, or no storage class specifier.
808/// These turn into simple stack objects, or GlobalValues depending on target.
809void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
810  AutoVarEmission emission = EmitAutoVarAlloca(D);
811  EmitAutoVarInit(emission);
812  EmitAutoVarCleanups(emission);
813}
814
815/// EmitAutoVarAlloca - Emit the alloca and debug information for a
816/// local variable.  Does not emit initalization or destruction.
817CodeGenFunction::AutoVarEmission
818CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
819  QualType Ty = D.getType();
820
821  AutoVarEmission emission(D);
822
823  bool isByRef = D.hasAttr<BlocksAttr>();
824  emission.IsByRef = isByRef;
825
826  CharUnits alignment = getContext().getDeclAlign(&D);
827  emission.Alignment = alignment;
828
829  // If the type is variably-modified, emit all the VLA sizes for it.
830  if (Ty->isVariablyModifiedType())
831    EmitVariablyModifiedType(Ty);
832
833  llvm::Value *DeclPtr;
834  if (Ty->isConstantSizeType()) {
835    bool NRVO = getLangOpts().ElideConstructors &&
836      D.isNRVOVariable();
837
838    // If this value is a POD array or struct with a statically
839    // determinable constant initializer, there are optimizations we can do.
840    //
841    // TODO: We should constant-evaluate the initializer of any variable,
842    // as long as it is initialized by a constant expression. Currently,
843    // isConstantInitializer produces wrong answers for structs with
844    // reference or bitfield members, and a few other cases, and checking
845    // for POD-ness protects us from some of these.
846    if (D.getInit() &&
847        (Ty->isArrayType() || Ty->isRecordType()) &&
848        (Ty.isPODType(getContext()) ||
849         getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
850        D.getInit()->isConstantInitializer(getContext(), false)) {
851
852      // If the variable's a const type, and it's neither an NRVO
853      // candidate nor a __block variable and has no mutable members,
854      // emit it as a global instead.
855      if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef &&
856          CGM.isTypeConstant(Ty, true)) {
857        EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
858
859        emission.Address = 0; // signal this condition to later callbacks
860        assert(emission.wasEmittedAsGlobal());
861        return emission;
862      }
863
864      // Otherwise, tell the initialization code that we're in this case.
865      emission.IsConstantAggregate = true;
866    }
867
868    // A normal fixed sized variable becomes an alloca in the entry block,
869    // unless it's an NRVO variable.
870    llvm::Type *LTy = ConvertTypeForMem(Ty);
871
872    if (NRVO) {
873      // The named return value optimization: allocate this variable in the
874      // return slot, so that we can elide the copy when returning this
875      // variable (C++0x [class.copy]p34).
876      DeclPtr = ReturnValue;
877
878      if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
879        if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
880          // Create a flag that is used to indicate when the NRVO was applied
881          // to this variable. Set it to zero to indicate that NRVO was not
882          // applied.
883          llvm::Value *Zero = Builder.getFalse();
884          llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
885          EnsureInsertPoint();
886          Builder.CreateStore(Zero, NRVOFlag);
887
888          // Record the NRVO flag for this variable.
889          NRVOFlags[&D] = NRVOFlag;
890          emission.NRVOFlag = NRVOFlag;
891        }
892      }
893    } else {
894      if (isByRef)
895        LTy = BuildByRefType(&D);
896
897      llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
898      Alloc->setName(D.getName());
899
900      CharUnits allocaAlignment = alignment;
901      if (isByRef)
902        allocaAlignment = std::max(allocaAlignment,
903            getContext().toCharUnitsFromBits(getTarget().getPointerAlign(0)));
904      Alloc->setAlignment(allocaAlignment.getQuantity());
905      DeclPtr = Alloc;
906
907      // Emit a lifetime intrinsic if meaningful.  There's no point
908      // in doing this if we don't have a valid insertion point (?).
909      uint64_t size = CGM.getDataLayout().getTypeAllocSize(LTy);
910      if (HaveInsertPoint() && shouldUseLifetimeMarkers(*this, D, size)) {
911        llvm::Value *sizeV = llvm::ConstantInt::get(Int64Ty, size);
912
913        emission.SizeForLifetimeMarkers = sizeV;
914        llvm::Value *castAddr = Builder.CreateBitCast(Alloc, Int8PtrTy);
915        Builder.CreateCall2(CGM.getLLVMLifetimeStartFn(), sizeV, castAddr)
916          ->setDoesNotThrow();
917      } else {
918        assert(!emission.useLifetimeMarkers());
919      }
920    }
921  } else {
922    EnsureInsertPoint();
923
924    if (!DidCallStackSave) {
925      // Save the stack.
926      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
927
928      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
929      llvm::Value *V = Builder.CreateCall(F);
930
931      Builder.CreateStore(V, Stack);
932
933      DidCallStackSave = true;
934
935      // Push a cleanup block and restore the stack there.
936      // FIXME: in general circumstances, this should be an EH cleanup.
937      EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
938    }
939
940    llvm::Value *elementCount;
941    QualType elementType;
942    llvm::tie(elementCount, elementType) = getVLASize(Ty);
943
944    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
945
946    // Allocate memory for the array.
947    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
948    vla->setAlignment(alignment.getQuantity());
949
950    DeclPtr = vla;
951  }
952
953  llvm::Value *&DMEntry = LocalDeclMap[&D];
954  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
955  DMEntry = DeclPtr;
956  emission.Address = DeclPtr;
957
958  // Emit debug info for local var declaration.
959  if (HaveInsertPoint())
960    if (CGDebugInfo *DI = getDebugInfo()) {
961      if (CGM.getCodeGenOpts().getDebugInfo()
962            >= CodeGenOptions::LimitedDebugInfo) {
963        DI->setLocation(D.getLocation());
964        DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
965      }
966    }
967
968  if (D.hasAttr<AnnotateAttr>())
969      EmitVarAnnotations(&D, emission.Address);
970
971  return emission;
972}
973
974/// Determines whether the given __block variable is potentially
975/// captured by the given expression.
976static bool isCapturedBy(const VarDecl &var, const Expr *e) {
977  // Skip the most common kinds of expressions that make
978  // hierarchy-walking expensive.
979  e = e->IgnoreParenCasts();
980
981  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
982    const BlockDecl *block = be->getBlockDecl();
983    for (BlockDecl::capture_const_iterator i = block->capture_begin(),
984           e = block->capture_end(); i != e; ++i) {
985      if (i->getVariable() == &var)
986        return true;
987    }
988
989    // No need to walk into the subexpressions.
990    return false;
991  }
992
993  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
994    const CompoundStmt *CS = SE->getSubStmt();
995    for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
996	   BE = CS->body_end(); BI != BE; ++BI)
997      if (Expr *E = dyn_cast<Expr>((*BI))) {
998        if (isCapturedBy(var, E))
999            return true;
1000      }
1001      else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) {
1002          // special case declarations
1003          for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
1004               I != E; ++I) {
1005              if (VarDecl *VD = dyn_cast<VarDecl>((*I))) {
1006                Expr *Init = VD->getInit();
1007                if (Init && isCapturedBy(var, Init))
1008                  return true;
1009              }
1010          }
1011      }
1012      else
1013        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
1014        // Later, provide code to poke into statements for capture analysis.
1015        return true;
1016    return false;
1017  }
1018
1019  for (Stmt::const_child_range children = e->children(); children; ++children)
1020    if (isCapturedBy(var, cast<Expr>(*children)))
1021      return true;
1022
1023  return false;
1024}
1025
1026/// \brief Determine whether the given initializer is trivial in the sense
1027/// that it requires no code to be generated.
1028static bool isTrivialInitializer(const Expr *Init) {
1029  if (!Init)
1030    return true;
1031
1032  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
1033    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
1034      if (Constructor->isTrivial() &&
1035          Constructor->isDefaultConstructor() &&
1036          !Construct->requiresZeroInitialization())
1037        return true;
1038
1039  return false;
1040}
1041void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
1042  assert(emission.Variable && "emission was not valid!");
1043
1044  // If this was emitted as a global constant, we're done.
1045  if (emission.wasEmittedAsGlobal()) return;
1046
1047  const VarDecl &D = *emission.Variable;
1048  QualType type = D.getType();
1049
1050  // If this local has an initializer, emit it now.
1051  const Expr *Init = D.getInit();
1052
1053  // If we are at an unreachable point, we don't need to emit the initializer
1054  // unless it contains a label.
1055  if (!HaveInsertPoint()) {
1056    if (!Init || !ContainsLabel(Init)) return;
1057    EnsureInsertPoint();
1058  }
1059
1060  // Initialize the structure of a __block variable.
1061  if (emission.IsByRef)
1062    emitByrefStructureInit(emission);
1063
1064  if (isTrivialInitializer(Init))
1065    return;
1066
1067  CharUnits alignment = emission.Alignment;
1068
1069  // Check whether this is a byref variable that's potentially
1070  // captured and moved by its own initializer.  If so, we'll need to
1071  // emit the initializer first, then copy into the variable.
1072  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
1073
1074  llvm::Value *Loc =
1075    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
1076
1077  llvm::Constant *constant = 0;
1078  if (emission.IsConstantAggregate) {
1079    assert(!capturedByInit && "constant init contains a capturing block?");
1080    constant = CGM.EmitConstantInit(D, this);
1081  }
1082
1083  if (!constant) {
1084    LValue lv = MakeAddrLValue(Loc, type, alignment);
1085    lv.setNonGC(true);
1086    return EmitExprAsInit(Init, &D, lv, capturedByInit);
1087  }
1088
1089  // If this is a simple aggregate initialization, we can optimize it
1090  // in various ways.
1091  bool isVolatile = type.isVolatileQualified();
1092
1093  llvm::Value *SizeVal =
1094    llvm::ConstantInt::get(IntPtrTy,
1095                           getContext().getTypeSizeInChars(type).getQuantity());
1096
1097  llvm::Type *BP = Int8PtrTy;
1098  if (Loc->getType() != BP)
1099    Loc = Builder.CreateBitCast(Loc, BP);
1100
1101  // If the initializer is all or mostly zeros, codegen with memset then do
1102  // a few stores afterward.
1103  if (shouldUseMemSetPlusStoresToInitialize(constant,
1104                CGM.getDataLayout().getTypeAllocSize(constant->getType()))) {
1105    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
1106                         alignment.getQuantity(), isVolatile);
1107    // Zero and undef don't require a stores.
1108    if (!constant->isNullValue() && !isa<llvm::UndefValue>(constant)) {
1109      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
1110      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
1111    }
1112  } else {
1113    // Otherwise, create a temporary global with the initializer then
1114    // memcpy from the global to the alloca.
1115    std::string Name = GetStaticDeclName(*this, D, ".");
1116    llvm::GlobalVariable *GV =
1117      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1118                               llvm::GlobalValue::PrivateLinkage,
1119                               constant, Name);
1120    GV->setAlignment(alignment.getQuantity());
1121    GV->setUnnamedAddr(true);
1122
1123    llvm::Value *SrcPtr = GV;
1124    if (SrcPtr->getType() != BP)
1125      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1126
1127    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1128                         isVolatile);
1129  }
1130}
1131
1132/// Emit an expression as an initializer for a variable at the given
1133/// location.  The expression is not necessarily the normal
1134/// initializer for the variable, and the address is not necessarily
1135/// its normal location.
1136///
1137/// \param init the initializing expression
1138/// \param var the variable to act as if we're initializing
1139/// \param loc the address to initialize; its type is a pointer
1140///   to the LLVM mapping of the variable's type
1141/// \param alignment the alignment of the address
1142/// \param capturedByInit true if the variable is a __block variable
1143///   whose address is potentially changed by the initializer
1144void CodeGenFunction::EmitExprAsInit(const Expr *init,
1145                                     const ValueDecl *D,
1146                                     LValue lvalue,
1147                                     bool capturedByInit) {
1148  QualType type = D->getType();
1149
1150  if (type->isReferenceType()) {
1151    RValue rvalue = EmitReferenceBindingToExpr(init, D);
1152    if (capturedByInit)
1153      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1154    EmitStoreThroughLValue(rvalue, lvalue, true);
1155    return;
1156  }
1157  switch (getEvaluationKind(type)) {
1158  case TEK_Scalar:
1159    EmitScalarInit(init, D, lvalue, capturedByInit);
1160    return;
1161  case TEK_Complex: {
1162    ComplexPairTy complex = EmitComplexExpr(init);
1163    if (capturedByInit)
1164      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1165    EmitStoreOfComplex(complex, lvalue, /*init*/ true);
1166    return;
1167  }
1168  case TEK_Aggregate:
1169    if (type->isAtomicType()) {
1170      EmitAtomicInit(const_cast<Expr*>(init), lvalue);
1171    } else {
1172      // TODO: how can we delay here if D is captured by its initializer?
1173      EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1174                                              AggValueSlot::IsDestructed,
1175                                         AggValueSlot::DoesNotNeedGCBarriers,
1176                                              AggValueSlot::IsNotAliased));
1177    }
1178    MaybeEmitStdInitializerListCleanup(lvalue.getAddress(), init);
1179    return;
1180  }
1181  llvm_unreachable("bad evaluation kind");
1182}
1183
1184/// Enter a destroy cleanup for the given local variable.
1185void CodeGenFunction::emitAutoVarTypeCleanup(
1186                            const CodeGenFunction::AutoVarEmission &emission,
1187                            QualType::DestructionKind dtorKind) {
1188  assert(dtorKind != QualType::DK_none);
1189
1190  // Note that for __block variables, we want to destroy the
1191  // original stack object, not the possibly forwarded object.
1192  llvm::Value *addr = emission.getObjectAddress(*this);
1193
1194  const VarDecl *var = emission.Variable;
1195  QualType type = var->getType();
1196
1197  CleanupKind cleanupKind = NormalAndEHCleanup;
1198  CodeGenFunction::Destroyer *destroyer = 0;
1199
1200  switch (dtorKind) {
1201  case QualType::DK_none:
1202    llvm_unreachable("no cleanup for trivially-destructible variable");
1203
1204  case QualType::DK_cxx_destructor:
1205    // If there's an NRVO flag on the emission, we need a different
1206    // cleanup.
1207    if (emission.NRVOFlag) {
1208      assert(!type->isArrayType());
1209      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1210      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1211                                               emission.NRVOFlag);
1212      return;
1213    }
1214    break;
1215
1216  case QualType::DK_objc_strong_lifetime:
1217    // Suppress cleanups for pseudo-strong variables.
1218    if (var->isARCPseudoStrong()) return;
1219
1220    // Otherwise, consider whether to use an EH cleanup or not.
1221    cleanupKind = getARCCleanupKind();
1222
1223    // Use the imprecise destroyer by default.
1224    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1225      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1226    break;
1227
1228  case QualType::DK_objc_weak_lifetime:
1229    break;
1230  }
1231
1232  // If we haven't chosen a more specific destroyer, use the default.
1233  if (!destroyer) destroyer = getDestroyer(dtorKind);
1234
1235  // Use an EH cleanup in array destructors iff the destructor itself
1236  // is being pushed as an EH cleanup.
1237  bool useEHCleanup = (cleanupKind & EHCleanup);
1238  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1239                                     useEHCleanup);
1240}
1241
1242void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1243  assert(emission.Variable && "emission was not valid!");
1244
1245  // If this was emitted as a global constant, we're done.
1246  if (emission.wasEmittedAsGlobal()) return;
1247
1248  // If we don't have an insertion point, we're done.  Sema prevents
1249  // us from jumping into any of these scopes anyway.
1250  if (!HaveInsertPoint()) return;
1251
1252  const VarDecl &D = *emission.Variable;
1253
1254  // Make sure we call @llvm.lifetime.end.  This needs to happen
1255  // *last*, so the cleanup needs to be pushed *first*.
1256  if (emission.useLifetimeMarkers()) {
1257    EHStack.pushCleanup<CallLifetimeEnd>(NormalCleanup,
1258                                         emission.getAllocatedAddress(),
1259                                         emission.getSizeForLifetimeMarkers());
1260  }
1261
1262  // Check the type for a cleanup.
1263  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1264    emitAutoVarTypeCleanup(emission, dtorKind);
1265
1266  // In GC mode, honor objc_precise_lifetime.
1267  if (getLangOpts().getGC() != LangOptions::NonGC &&
1268      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1269    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1270  }
1271
1272  // Handle the cleanup attribute.
1273  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1274    const FunctionDecl *FD = CA->getFunctionDecl();
1275
1276    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1277    assert(F && "Could not find function!");
1278
1279    const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
1280    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1281  }
1282
1283  // If this is a block variable, call _Block_object_destroy
1284  // (on the unforwarded address).
1285  if (emission.IsByRef)
1286    enterByrefCleanup(emission);
1287}
1288
1289CodeGenFunction::Destroyer *
1290CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1291  switch (kind) {
1292  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1293  case QualType::DK_cxx_destructor:
1294    return destroyCXXObject;
1295  case QualType::DK_objc_strong_lifetime:
1296    return destroyARCStrongPrecise;
1297  case QualType::DK_objc_weak_lifetime:
1298    return destroyARCWeak;
1299  }
1300  llvm_unreachable("Unknown DestructionKind");
1301}
1302
1303/// pushEHDestroy - Push the standard destructor for the given type as
1304/// an EH-only cleanup.
1305void CodeGenFunction::pushEHDestroy(QualType::DestructionKind dtorKind,
1306                                  llvm::Value *addr, QualType type) {
1307  assert(dtorKind && "cannot push destructor for trivial type");
1308  assert(needsEHCleanup(dtorKind));
1309
1310  pushDestroy(EHCleanup, addr, type, getDestroyer(dtorKind), true);
1311}
1312
1313/// pushDestroy - Push the standard destructor for the given type as
1314/// at least a normal cleanup.
1315void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1316                                  llvm::Value *addr, QualType type) {
1317  assert(dtorKind && "cannot push destructor for trivial type");
1318
1319  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1320  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1321              cleanupKind & EHCleanup);
1322}
1323
1324void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1325                                  QualType type, Destroyer *destroyer,
1326                                  bool useEHCleanupForArray) {
1327  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1328                                     destroyer, useEHCleanupForArray);
1329}
1330
1331/// emitDestroy - Immediately perform the destruction of the given
1332/// object.
1333///
1334/// \param addr - the address of the object; a type*
1335/// \param type - the type of the object; if an array type, all
1336///   objects are destroyed in reverse order
1337/// \param destroyer - the function to call to destroy individual
1338///   elements
1339/// \param useEHCleanupForArray - whether an EH cleanup should be
1340///   used when destroying array elements, in case one of the
1341///   destructions throws an exception
1342void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1343                                  Destroyer *destroyer,
1344                                  bool useEHCleanupForArray) {
1345  const ArrayType *arrayType = getContext().getAsArrayType(type);
1346  if (!arrayType)
1347    return destroyer(*this, addr, type);
1348
1349  llvm::Value *begin = addr;
1350  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1351
1352  // Normally we have to check whether the array is zero-length.
1353  bool checkZeroLength = true;
1354
1355  // But if the array length is constant, we can suppress that.
1356  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1357    // ...and if it's constant zero, we can just skip the entire thing.
1358    if (constLength->isZero()) return;
1359    checkZeroLength = false;
1360  }
1361
1362  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1363  emitArrayDestroy(begin, end, type, destroyer,
1364                   checkZeroLength, useEHCleanupForArray);
1365}
1366
1367/// emitArrayDestroy - Destroys all the elements of the given array,
1368/// beginning from last to first.  The array cannot be zero-length.
1369///
1370/// \param begin - a type* denoting the first element of the array
1371/// \param end - a type* denoting one past the end of the array
1372/// \param type - the element type of the array
1373/// \param destroyer - the function to call to destroy elements
1374/// \param useEHCleanup - whether to push an EH cleanup to destroy
1375///   the remaining elements in case the destruction of a single
1376///   element throws
1377void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1378                                       llvm::Value *end,
1379                                       QualType type,
1380                                       Destroyer *destroyer,
1381                                       bool checkZeroLength,
1382                                       bool useEHCleanup) {
1383  assert(!type->isArrayType());
1384
1385  // The basic structure here is a do-while loop, because we don't
1386  // need to check for the zero-element case.
1387  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1388  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1389
1390  if (checkZeroLength) {
1391    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1392                                                "arraydestroy.isempty");
1393    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1394  }
1395
1396  // Enter the loop body, making that address the current address.
1397  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1398  EmitBlock(bodyBB);
1399  llvm::PHINode *elementPast =
1400    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1401  elementPast->addIncoming(end, entryBB);
1402
1403  // Shift the address back by one element.
1404  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1405  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1406                                                   "arraydestroy.element");
1407
1408  if (useEHCleanup)
1409    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1410
1411  // Perform the actual destruction there.
1412  destroyer(*this, element, type);
1413
1414  if (useEHCleanup)
1415    PopCleanupBlock();
1416
1417  // Check whether we've reached the end.
1418  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1419  Builder.CreateCondBr(done, doneBB, bodyBB);
1420  elementPast->addIncoming(element, Builder.GetInsertBlock());
1421
1422  // Done.
1423  EmitBlock(doneBB);
1424}
1425
1426/// Perform partial array destruction as if in an EH cleanup.  Unlike
1427/// emitArrayDestroy, the element type here may still be an array type.
1428static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1429                                    llvm::Value *begin, llvm::Value *end,
1430                                    QualType type,
1431                                    CodeGenFunction::Destroyer *destroyer) {
1432  // If the element type is itself an array, drill down.
1433  unsigned arrayDepth = 0;
1434  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1435    // VLAs don't require a GEP index to walk into.
1436    if (!isa<VariableArrayType>(arrayType))
1437      arrayDepth++;
1438    type = arrayType->getElementType();
1439  }
1440
1441  if (arrayDepth) {
1442    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1443
1444    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1445    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1446    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1447  }
1448
1449  // Destroy the array.  We don't ever need an EH cleanup because we
1450  // assume that we're in an EH cleanup ourselves, so a throwing
1451  // destructor causes an immediate terminate.
1452  CGF.emitArrayDestroy(begin, end, type, destroyer,
1453                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1454}
1455
1456namespace {
1457  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1458  /// array destroy where the end pointer is regularly determined and
1459  /// does not need to be loaded from a local.
1460  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1461    llvm::Value *ArrayBegin;
1462    llvm::Value *ArrayEnd;
1463    QualType ElementType;
1464    CodeGenFunction::Destroyer *Destroyer;
1465  public:
1466    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1467                               QualType elementType,
1468                               CodeGenFunction::Destroyer *destroyer)
1469      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1470        ElementType(elementType), Destroyer(destroyer) {}
1471
1472    void Emit(CodeGenFunction &CGF, Flags flags) {
1473      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1474                              ElementType, Destroyer);
1475    }
1476  };
1477
1478  /// IrregularPartialArrayDestroy - a cleanup which performs a
1479  /// partial array destroy where the end pointer is irregularly
1480  /// determined and must be loaded from a local.
1481  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1482    llvm::Value *ArrayBegin;
1483    llvm::Value *ArrayEndPointer;
1484    QualType ElementType;
1485    CodeGenFunction::Destroyer *Destroyer;
1486  public:
1487    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1488                                 llvm::Value *arrayEndPointer,
1489                                 QualType elementType,
1490                                 CodeGenFunction::Destroyer *destroyer)
1491      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1492        ElementType(elementType), Destroyer(destroyer) {}
1493
1494    void Emit(CodeGenFunction &CGF, Flags flags) {
1495      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1496      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1497                              ElementType, Destroyer);
1498    }
1499  };
1500}
1501
1502/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1503/// already-constructed elements of the given array.  The cleanup
1504/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1505///
1506/// \param elementType - the immediate element type of the array;
1507///   possibly still an array type
1508void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1509                                                 llvm::Value *arrayEndPointer,
1510                                                       QualType elementType,
1511                                                       Destroyer *destroyer) {
1512  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1513                                                    arrayBegin, arrayEndPointer,
1514                                                    elementType, destroyer);
1515}
1516
1517/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1518/// already-constructed elements of the given array.  The cleanup
1519/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1520///
1521/// \param elementType - the immediate element type of the array;
1522///   possibly still an array type
1523void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1524                                                     llvm::Value *arrayEnd,
1525                                                     QualType elementType,
1526                                                     Destroyer *destroyer) {
1527  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1528                                                  arrayBegin, arrayEnd,
1529                                                  elementType, destroyer);
1530}
1531
1532/// Lazily declare the @llvm.lifetime.start intrinsic.
1533llvm::Constant *CodeGenModule::getLLVMLifetimeStartFn() {
1534  if (LifetimeStartFn) return LifetimeStartFn;
1535  LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(),
1536                                            llvm::Intrinsic::lifetime_start);
1537  return LifetimeStartFn;
1538}
1539
1540/// Lazily declare the @llvm.lifetime.end intrinsic.
1541llvm::Constant *CodeGenModule::getLLVMLifetimeEndFn() {
1542  if (LifetimeEndFn) return LifetimeEndFn;
1543  LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(),
1544                                              llvm::Intrinsic::lifetime_end);
1545  return LifetimeEndFn;
1546}
1547
1548namespace {
1549  /// A cleanup to perform a release of an object at the end of a
1550  /// function.  This is used to balance out the incoming +1 of a
1551  /// ns_consumed argument when we can't reasonably do that just by
1552  /// not doing the initial retain for a __block argument.
1553  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1554    ConsumeARCParameter(llvm::Value *param,
1555                        ARCPreciseLifetime_t precise)
1556      : Param(param), Precise(precise) {}
1557
1558    llvm::Value *Param;
1559    ARCPreciseLifetime_t Precise;
1560
1561    void Emit(CodeGenFunction &CGF, Flags flags) {
1562      CGF.EmitARCRelease(Param, Precise);
1563    }
1564  };
1565}
1566
1567/// Emit an alloca (or GlobalValue depending on target)
1568/// for the specified parameter and set up LocalDeclMap.
1569void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1570                                   unsigned ArgNo) {
1571  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1572  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1573         "Invalid argument to EmitParmDecl");
1574
1575  Arg->setName(D.getName());
1576
1577  QualType Ty = D.getType();
1578
1579  // Use better IR generation for certain implicit parameters.
1580  if (isa<ImplicitParamDecl>(D)) {
1581    // The only implicit argument a block has is its literal.
1582    if (BlockInfo) {
1583      LocalDeclMap[&D] = Arg;
1584      llvm::Value *LocalAddr = 0;
1585      if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1586        // Allocate a stack slot to let the debug info survive the RA.
1587        llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1588                                                   D.getName() + ".addr");
1589        Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
1590        LValue lv = MakeAddrLValue(Alloc, Ty, getContext().getDeclAlign(&D));
1591        EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1592        LocalAddr = Builder.CreateLoad(Alloc);
1593      }
1594
1595      if (CGDebugInfo *DI = getDebugInfo()) {
1596        if (CGM.getCodeGenOpts().getDebugInfo()
1597              >= CodeGenOptions::LimitedDebugInfo) {
1598          DI->setLocation(D.getLocation());
1599          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, LocalAddr, Builder);
1600        }
1601      }
1602
1603      return;
1604    }
1605  }
1606
1607  llvm::Value *DeclPtr;
1608  // If this is an aggregate or variable sized value, reuse the input pointer.
1609  if (!Ty->isConstantSizeType() ||
1610      !CodeGenFunction::hasScalarEvaluationKind(Ty)) {
1611    DeclPtr = Arg;
1612  } else {
1613    // Otherwise, create a temporary to hold the value.
1614    llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1615                                               D.getName() + ".addr");
1616    CharUnits Align = getContext().getDeclAlign(&D);
1617    Alloc->setAlignment(Align.getQuantity());
1618    DeclPtr = Alloc;
1619
1620    bool doStore = true;
1621
1622    Qualifiers qs = Ty.getQualifiers();
1623    LValue lv = MakeAddrLValue(DeclPtr, Ty, Align);
1624    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1625      // We honor __attribute__((ns_consumed)) for types with lifetime.
1626      // For __strong, it's handled by just skipping the initial retain;
1627      // otherwise we have to balance out the initial +1 with an extra
1628      // cleanup to do the release at the end of the function.
1629      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1630
1631      // 'self' is always formally __strong, but if this is not an
1632      // init method then we don't want to retain it.
1633      if (D.isARCPseudoStrong()) {
1634        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1635        assert(&D == method->getSelfDecl());
1636        assert(lt == Qualifiers::OCL_Strong);
1637        assert(qs.hasConst());
1638        assert(method->getMethodFamily() != OMF_init);
1639        (void) method;
1640        lt = Qualifiers::OCL_ExplicitNone;
1641      }
1642
1643      if (lt == Qualifiers::OCL_Strong) {
1644        if (!isConsumed) {
1645          if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1646            // use objc_storeStrong(&dest, value) for retaining the
1647            // object. But first, store a null into 'dest' because
1648            // objc_storeStrong attempts to release its old value.
1649            llvm::Value * Null = CGM.EmitNullConstant(D.getType());
1650            EmitStoreOfScalar(Null, lv, /* isInitialization */ true);
1651            EmitARCStoreStrongCall(lv.getAddress(), Arg, true);
1652            doStore = false;
1653          }
1654          else
1655          // Don't use objc_retainBlock for block pointers, because we
1656          // don't want to Block_copy something just because we got it
1657          // as a parameter.
1658            Arg = EmitARCRetainNonBlock(Arg);
1659        }
1660      } else {
1661        // Push the cleanup for a consumed parameter.
1662        if (isConsumed) {
1663          ARCPreciseLifetime_t precise = (D.hasAttr<ObjCPreciseLifetimeAttr>()
1664                                ? ARCPreciseLifetime : ARCImpreciseLifetime);
1665          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg,
1666                                                   precise);
1667        }
1668
1669        if (lt == Qualifiers::OCL_Weak) {
1670          EmitARCInitWeak(DeclPtr, Arg);
1671          doStore = false; // The weak init is a store, no need to do two.
1672        }
1673      }
1674
1675      // Enter the cleanup scope.
1676      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1677    }
1678
1679    // Store the initial value into the alloca.
1680    if (doStore)
1681      EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1682  }
1683
1684  llvm::Value *&DMEntry = LocalDeclMap[&D];
1685  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
1686  DMEntry = DeclPtr;
1687
1688  // Emit debug info for param declaration.
1689  if (CGDebugInfo *DI = getDebugInfo()) {
1690    if (CGM.getCodeGenOpts().getDebugInfo()
1691          >= CodeGenOptions::LimitedDebugInfo) {
1692      DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1693    }
1694  }
1695
1696  if (D.hasAttr<AnnotateAttr>())
1697      EmitVarAnnotations(&D, DeclPtr);
1698}
1699