CGDecl.cpp revision 5e2d5dec7736f6f9292d4212dec67295909f1328 
1//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This contains code to emit Decl nodes as LLVM code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CGDebugInfo.h"
15#include "CodeGenFunction.h"
16#include "CodeGenModule.h"
17#include "CGOpenCLRuntime.h"
18#include "clang/AST/ASTContext.h"
19#include "clang/AST/CharUnits.h"
20#include "clang/AST/Decl.h"
21#include "clang/AST/DeclObjC.h"
22#include "clang/Basic/SourceManager.h"
23#include "clang/Basic/TargetInfo.h"
24#include "clang/Frontend/CodeGenOptions.h"
25#include "llvm/GlobalVariable.h"
26#include "llvm/Intrinsics.h"
27#include "llvm/Target/TargetData.h"
28#include "llvm/Type.h"
29using namespace clang;
30using namespace CodeGen;
31
32
33void CodeGenFunction::EmitDecl(const Decl &D) {
34  switch (D.getKind()) {
35  case Decl::TranslationUnit:
36  case Decl::Namespace:
37  case Decl::UnresolvedUsingTypename:
38  case Decl::ClassTemplateSpecialization:
39  case Decl::ClassTemplatePartialSpecialization:
40  case Decl::TemplateTypeParm:
41  case Decl::UnresolvedUsingValue:
42  case Decl::NonTypeTemplateParm:
43  case Decl::CXXMethod:
44  case Decl::CXXConstructor:
45  case Decl::CXXDestructor:
46  case Decl::CXXConversion:
47  case Decl::Field:
48  case Decl::IndirectField:
49  case Decl::ObjCIvar:
50  case Decl::ObjCAtDefsField:
51  case Decl::ParmVar:
52  case Decl::ImplicitParam:
53  case Decl::ClassTemplate:
54  case Decl::FunctionTemplate:
55  case Decl::TypeAliasTemplate:
56  case Decl::TemplateTemplateParm:
57  case Decl::ObjCMethod:
58  case Decl::ObjCCategory:
59  case Decl::ObjCProtocol:
60  case Decl::ObjCInterface:
61  case Decl::ObjCCategoryImpl:
62  case Decl::ObjCImplementation:
63  case Decl::ObjCProperty:
64  case Decl::ObjCCompatibleAlias:
65  case Decl::AccessSpec:
66  case Decl::LinkageSpec:
67  case Decl::ObjCPropertyImpl:
68  case Decl::FileScopeAsm:
69  case Decl::Friend:
70  case Decl::FriendTemplate:
71  case Decl::Block:
72  case Decl::ClassScopeFunctionSpecialization:
73    llvm_unreachable("Declaration should not be in declstmts!");
74  case Decl::Function:  // void X();
75  case Decl::Record:    // struct/union/class X;
76  case Decl::Enum:      // enum X;
77  case Decl::EnumConstant: // enum ? { X = ? }
78  case Decl::CXXRecord: // struct/union/class X; [C++]
79  case Decl::Using:          // using X; [C++]
80  case Decl::UsingShadow:
81  case Decl::UsingDirective: // using namespace X; [C++]
82  case Decl::NamespaceAlias:
83  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
84  case Decl::Label:        // __label__ x;
85  case Decl::Import:
86    // None of these decls require codegen support.
87    return;
88
89  case Decl::Var: {
90    const VarDecl &VD = cast<VarDecl>(D);
91    assert(VD.isLocalVarDecl() &&
92           "Should not see file-scope variables inside a function!");
93    return EmitVarDecl(VD);
94  }
95
96  case Decl::Typedef:      // typedef int X;
97  case Decl::TypeAlias: {  // using X = int; [C++0x]
98    const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
99    QualType Ty = TD.getUnderlyingType();
100
101    if (Ty->isVariablyModifiedType())
102      EmitVariablyModifiedType(Ty);
103  }
104  }
105}
106
107/// EmitVarDecl - This method handles emission of any variable declaration
108/// inside a function, including static vars etc.
109void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
110  switch (D.getStorageClass()) {
111  case SC_None:
112  case SC_Auto:
113  case SC_Register:
114    return EmitAutoVarDecl(D);
115  case SC_Static: {
116    llvm::GlobalValue::LinkageTypes Linkage =
117      llvm::GlobalValue::InternalLinkage;
118
119    // If the function definition has some sort of weak linkage, its
120    // static variables should also be weak so that they get properly
121    // uniqued.  We can't do this in C, though, because there's no
122    // standard way to agree on which variables are the same (i.e.
123    // there's no mangling).
124    if (getContext().getLangOpts().CPlusPlus)
125      if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
126        Linkage = CurFn->getLinkage();
127
128    return EmitStaticVarDecl(D, Linkage);
129  }
130  case SC_Extern:
131  case SC_PrivateExtern:
132    // Don't emit it now, allow it to be emitted lazily on its first use.
133    return;
134  case SC_OpenCLWorkGroupLocal:
135    return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
136  }
137
138  llvm_unreachable("Unknown storage class");
139}
140
141static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
142                                     const char *Separator) {
143  CodeGenModule &CGM = CGF.CGM;
144  if (CGF.getContext().getLangOpts().CPlusPlus) {
145    StringRef Name = CGM.getMangledName(&D);
146    return Name.str();
147  }
148
149  std::string ContextName;
150  if (!CGF.CurFuncDecl) {
151    // Better be in a block declared in global scope.
152    const NamedDecl *ND = cast<NamedDecl>(&D);
153    const DeclContext *DC = ND->getDeclContext();
154    if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
155      MangleBuffer Name;
156      CGM.getBlockMangledName(GlobalDecl(), Name, BD);
157      ContextName = Name.getString();
158    }
159    else
160      llvm_unreachable("Unknown context for block static var decl");
161  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
162    StringRef Name = CGM.getMangledName(FD);
163    ContextName = Name.str();
164  } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
165    ContextName = CGF.CurFn->getName();
166  else
167    llvm_unreachable("Unknown context for static var decl");
168
169  return ContextName + Separator + D.getNameAsString();
170}
171
172llvm::GlobalVariable *
173CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
174                                     const char *Separator,
175                                     llvm::GlobalValue::LinkageTypes Linkage) {
176  QualType Ty = D.getType();
177  assert(Ty->isConstantSizeType() && "VLAs can't be static");
178
179  // Use the label if the variable is renamed with the asm-label extension.
180  std::string Name;
181  if (D.hasAttr<AsmLabelAttr>())
182    Name = CGM.getMangledName(&D);
183  else
184    Name = GetStaticDeclName(*this, D, Separator);
185
186  llvm::GlobalVariable::ThreadLocalMode TLM;
187  TLM = D.isThreadSpecified() ? llvm::GlobalVariable::GeneralDynamicTLSModel
188                              : llvm::GlobalVariable::NotThreadLocal;
189
190  // Set the TLS mode if it it's explicitly specified.
191  if (D.hasAttr<TLSModelAttr>()) {
192    assert(D.isThreadSpecified() && "Can't have TLS model on non-tls var.");
193    const TLSModelAttr *Attr = D.getAttr<TLSModelAttr>();
194    TLM = CodeGenModule::GetLLVMTLSModel(Attr->getModel());
195  }
196
197  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
198  llvm::GlobalVariable *GV =
199    new llvm::GlobalVariable(CGM.getModule(), LTy,
200                             Ty.isConstant(getContext()), Linkage,
201                             CGM.EmitNullConstant(D.getType()), Name, 0, TLM,
202                             CGM.getContext().getTargetAddressSpace(Ty));
203  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
204  if (Linkage != llvm::GlobalValue::InternalLinkage)
205    GV->setVisibility(CurFn->getVisibility());
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 (!getContext().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().DebugInfo >= 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, Loc);
394
395      if (NRVO) CGF.EmitBlock(SkipDtorBB);
396    }
397  };
398
399  struct CallStackRestore : EHScopeStack::Cleanup {
400    llvm::Value *Stack;
401    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
402    void Emit(CodeGenFunction &CGF, Flags flags) {
403      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
404      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
405      CGF.Builder.CreateCall(F, V);
406    }
407  };
408
409  struct ExtendGCLifetime : EHScopeStack::Cleanup {
410    const VarDecl &Var;
411    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
412
413    void Emit(CodeGenFunction &CGF, Flags flags) {
414      // Compute the address of the local variable, in case it's a
415      // byref or something.
416      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
417                      Var.getType(), VK_LValue, SourceLocation());
418      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
419      CGF.EmitExtendGCLifetime(value);
420    }
421  };
422
423  struct CallCleanupFunction : EHScopeStack::Cleanup {
424    llvm::Constant *CleanupFn;
425    const CGFunctionInfo &FnInfo;
426    const VarDecl &Var;
427
428    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
429                        const VarDecl *Var)
430      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
431
432    void Emit(CodeGenFunction &CGF, Flags flags) {
433      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
434                      Var.getType(), VK_LValue, SourceLocation());
435      // Compute the address of the local variable, in case it's a byref
436      // or something.
437      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
438
439      // In some cases, the type of the function argument will be different from
440      // the type of the pointer. An example of this is
441      // void f(void* arg);
442      // __attribute__((cleanup(f))) void *g;
443      //
444      // To fix this we insert a bitcast here.
445      QualType ArgTy = FnInfo.arg_begin()->type;
446      llvm::Value *Arg =
447        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
448
449      CallArgList Args;
450      Args.add(RValue::get(Arg),
451               CGF.getContext().getPointerType(Var.getType()));
452      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
453    }
454  };
455}
456
457/// EmitAutoVarWithLifetime - Does the setup required for an automatic
458/// variable with lifetime.
459static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
460                                    llvm::Value *addr,
461                                    Qualifiers::ObjCLifetime lifetime) {
462  switch (lifetime) {
463  case Qualifiers::OCL_None:
464    llvm_unreachable("present but none");
465
466  case Qualifiers::OCL_ExplicitNone:
467    // nothing to do
468    break;
469
470  case Qualifiers::OCL_Strong: {
471    CodeGenFunction::Destroyer *destroyer =
472      (var.hasAttr<ObjCPreciseLifetimeAttr>()
473       ? CodeGenFunction::destroyARCStrongPrecise
474       : CodeGenFunction::destroyARCStrongImprecise);
475
476    CleanupKind cleanupKind = CGF.getARCCleanupKind();
477    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
478                    cleanupKind & EHCleanup);
479    break;
480  }
481  case Qualifiers::OCL_Autoreleasing:
482    // nothing to do
483    break;
484
485  case Qualifiers::OCL_Weak:
486    // __weak objects always get EH cleanups; otherwise, exceptions
487    // could cause really nasty crashes instead of mere leaks.
488    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
489                    CodeGenFunction::destroyARCWeak,
490                    /*useEHCleanup*/ true);
491    break;
492  }
493}
494
495static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
496  if (const Expr *e = dyn_cast<Expr>(s)) {
497    // Skip the most common kinds of expressions that make
498    // hierarchy-walking expensive.
499    s = e = e->IgnoreParenCasts();
500
501    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
502      return (ref->getDecl() == &var);
503    if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
504      const BlockDecl *block = be->getBlockDecl();
505      for (BlockDecl::capture_const_iterator i = block->capture_begin(),
506           e = block->capture_end(); i != e; ++i) {
507        if (i->getVariable() == &var)
508          return true;
509      }
510    }
511  }
512
513  for (Stmt::const_child_range children = s->children(); children; ++children)
514    // children might be null; as in missing decl or conditional of an if-stmt.
515    if ((*children) && isAccessedBy(var, *children))
516      return true;
517
518  return false;
519}
520
521static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
522  if (!decl) return false;
523  if (!isa<VarDecl>(decl)) return false;
524  const VarDecl *var = cast<VarDecl>(decl);
525  return isAccessedBy(*var, e);
526}
527
528static void drillIntoBlockVariable(CodeGenFunction &CGF,
529                                   LValue &lvalue,
530                                   const VarDecl *var) {
531  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
532}
533
534void CodeGenFunction::EmitScalarInit(const Expr *init,
535                                     const ValueDecl *D,
536                                     LValue lvalue,
537                                     bool capturedByInit) {
538  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
539  if (!lifetime) {
540    llvm::Value *value = EmitScalarExpr(init);
541    if (capturedByInit)
542      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
543    EmitStoreThroughLValue(RValue::get(value), lvalue, true);
544    return;
545  }
546
547  // If we're emitting a value with lifetime, we have to do the
548  // initialization *before* we leave the cleanup scopes.
549  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
550    enterFullExpression(ewc);
551    init = ewc->getSubExpr();
552  }
553  CodeGenFunction::RunCleanupsScope Scope(*this);
554
555  // We have to maintain the illusion that the variable is
556  // zero-initialized.  If the variable might be accessed in its
557  // initializer, zero-initialize before running the initializer, then
558  // actually perform the initialization with an assign.
559  bool accessedByInit = false;
560  if (lifetime != Qualifiers::OCL_ExplicitNone)
561    accessedByInit = (capturedByInit || isAccessedBy(D, init));
562  if (accessedByInit) {
563    LValue tempLV = lvalue;
564    // Drill down to the __block object if necessary.
565    if (capturedByInit) {
566      // We can use a simple GEP for this because it can't have been
567      // moved yet.
568      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
569                                   getByRefValueLLVMField(cast<VarDecl>(D))));
570    }
571
572    llvm::PointerType *ty
573      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
574    ty = cast<llvm::PointerType>(ty->getElementType());
575
576    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
577
578    // If __weak, we want to use a barrier under certain conditions.
579    if (lifetime == Qualifiers::OCL_Weak)
580      EmitARCInitWeak(tempLV.getAddress(), zero);
581
582    // Otherwise just do a simple store.
583    else
584      EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true);
585  }
586
587  // Emit the initializer.
588  llvm::Value *value = 0;
589
590  switch (lifetime) {
591  case Qualifiers::OCL_None:
592    llvm_unreachable("present but none");
593
594  case Qualifiers::OCL_ExplicitNone:
595    // nothing to do
596    value = EmitScalarExpr(init);
597    break;
598
599  case Qualifiers::OCL_Strong: {
600    value = EmitARCRetainScalarExpr(init);
601    break;
602  }
603
604  case Qualifiers::OCL_Weak: {
605    // No way to optimize a producing initializer into this.  It's not
606    // worth optimizing for, because the value will immediately
607    // disappear in the common case.
608    value = EmitScalarExpr(init);
609
610    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
611    if (accessedByInit)
612      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
613    else
614      EmitARCInitWeak(lvalue.getAddress(), value);
615    return;
616  }
617
618  case Qualifiers::OCL_Autoreleasing:
619    value = EmitARCRetainAutoreleaseScalarExpr(init);
620    break;
621  }
622
623  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
624
625  // If the variable might have been accessed by its initializer, we
626  // might have to initialize with a barrier.  We have to do this for
627  // both __weak and __strong, but __weak got filtered out above.
628  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
629    llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
630    EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
631    EmitARCRelease(oldValue, /*precise*/ false);
632    return;
633  }
634
635  EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
636}
637
638/// EmitScalarInit - Initialize the given lvalue with the given object.
639void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
640  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
641  if (!lifetime)
642    return EmitStoreThroughLValue(RValue::get(init), lvalue, true);
643
644  switch (lifetime) {
645  case Qualifiers::OCL_None:
646    llvm_unreachable("present but none");
647
648  case Qualifiers::OCL_ExplicitNone:
649    // nothing to do
650    break;
651
652  case Qualifiers::OCL_Strong:
653    init = EmitARCRetain(lvalue.getType(), init);
654    break;
655
656  case Qualifiers::OCL_Weak:
657    // Initialize and then skip the primitive store.
658    EmitARCInitWeak(lvalue.getAddress(), init);
659    return;
660
661  case Qualifiers::OCL_Autoreleasing:
662    init = EmitARCRetainAutorelease(lvalue.getType(), init);
663    break;
664  }
665
666  EmitStoreOfScalar(init, lvalue, /* isInitialization */ true);
667}
668
669/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
670/// non-zero parts of the specified initializer with equal or fewer than
671/// NumStores scalar stores.
672static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
673                                                unsigned &NumStores) {
674  // Zero and Undef never requires any extra stores.
675  if (isa<llvm::ConstantAggregateZero>(Init) ||
676      isa<llvm::ConstantPointerNull>(Init) ||
677      isa<llvm::UndefValue>(Init))
678    return true;
679  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
680      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
681      isa<llvm::ConstantExpr>(Init))
682    return Init->isNullValue() || NumStores--;
683
684  // See if we can emit each element.
685  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
686    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
687      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
688      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
689        return false;
690    }
691    return true;
692  }
693
694  if (llvm::ConstantDataSequential *CDS =
695        dyn_cast<llvm::ConstantDataSequential>(Init)) {
696    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
697      llvm::Constant *Elt = CDS->getElementAsConstant(i);
698      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
699        return false;
700    }
701    return true;
702  }
703
704  // Anything else is hard and scary.
705  return false;
706}
707
708/// emitStoresForInitAfterMemset - For inits that
709/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
710/// stores that would be required.
711static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
712                                         bool isVolatile, CGBuilderTy &Builder) {
713  // Zero doesn't require a store.
714  if (Init->isNullValue() || isa<llvm::UndefValue>(Init))
715    return;
716
717  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
718      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
719      isa<llvm::ConstantExpr>(Init)) {
720    Builder.CreateStore(Init, Loc, isVolatile);
721    return;
722  }
723
724  if (llvm::ConstantDataSequential *CDS =
725        dyn_cast<llvm::ConstantDataSequential>(Init)) {
726    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
727      llvm::Constant *Elt = CDS->getElementAsConstant(i);
728
729      // Get a pointer to the element and emit it.
730      emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
731                                   isVolatile, Builder);
732    }
733    return;
734  }
735
736  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
737         "Unknown value type!");
738
739  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
740    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
741    // Get a pointer to the element and emit it.
742    emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
743                                 isVolatile, Builder);
744  }
745}
746
747
748/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
749/// plus some stores to initialize a local variable instead of using a memcpy
750/// from a constant global.  It is beneficial to use memset if the global is all
751/// zeros, or mostly zeros and large.
752static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
753                                                  uint64_t GlobalSize) {
754  // If a global is all zeros, always use a memset.
755  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
756
757
758  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
759  // do it if it will require 6 or fewer scalar stores.
760  // TODO: Should budget depends on the size?  Avoiding a large global warrants
761  // plopping in more stores.
762  unsigned StoreBudget = 6;
763  uint64_t SizeLimit = 32;
764
765  return GlobalSize > SizeLimit &&
766         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
767}
768
769
770/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
771/// variable declaration with auto, register, or no storage class specifier.
772/// These turn into simple stack objects, or GlobalValues depending on target.
773void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
774  AutoVarEmission emission = EmitAutoVarAlloca(D);
775  EmitAutoVarInit(emission);
776  EmitAutoVarCleanups(emission);
777}
778
779/// EmitAutoVarAlloca - Emit the alloca and debug information for a
780/// local variable.  Does not emit initalization or destruction.
781CodeGenFunction::AutoVarEmission
782CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
783  QualType Ty = D.getType();
784
785  AutoVarEmission emission(D);
786
787  bool isByRef = D.hasAttr<BlocksAttr>();
788  emission.IsByRef = isByRef;
789
790  CharUnits alignment = getContext().getDeclAlign(&D);
791  emission.Alignment = alignment;
792
793  // If the type is variably-modified, emit all the VLA sizes for it.
794  if (Ty->isVariablyModifiedType())
795    EmitVariablyModifiedType(Ty);
796
797  llvm::Value *DeclPtr;
798  if (Ty->isConstantSizeType()) {
799    if (!Target.useGlobalsForAutomaticVariables()) {
800      bool NRVO = getContext().getLangOpts().ElideConstructors &&
801                  D.isNRVOVariable();
802
803      // If this value is a POD array or struct with a statically
804      // determinable constant initializer, there are optimizations we can do.
805      //
806      // TODO: We should constant-evaluate the initializer of any variable,
807      // as long as it is initialized by a constant expression. Currently,
808      // isConstantInitializer produces wrong answers for structs with
809      // reference or bitfield members, and a few other cases, and checking
810      // for POD-ness protects us from some of these.
811      if (D.getInit() &&
812          (Ty->isArrayType() || Ty->isRecordType()) &&
813          (Ty.isPODType(getContext()) ||
814           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
815          D.getInit()->isConstantInitializer(getContext(), false)) {
816
817        // If the variable's a const type, and it's neither an NRVO
818        // candidate nor a __block variable and has no mutable members,
819        // emit it as a global instead.
820        if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef &&
821            CGM.isTypeConstant(Ty, true)) {
822          EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
823
824          emission.Address = 0; // signal this condition to later callbacks
825          assert(emission.wasEmittedAsGlobal());
826          return emission;
827        }
828
829        // Otherwise, tell the initialization code that we're in this case.
830        emission.IsConstantAggregate = true;
831      }
832
833      // A normal fixed sized variable becomes an alloca in the entry block,
834      // unless it's an NRVO variable.
835      llvm::Type *LTy = ConvertTypeForMem(Ty);
836
837      if (NRVO) {
838        // The named return value optimization: allocate this variable in the
839        // return slot, so that we can elide the copy when returning this
840        // variable (C++0x [class.copy]p34).
841        DeclPtr = ReturnValue;
842
843        if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
844          if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
845            // Create a flag that is used to indicate when the NRVO was applied
846            // to this variable. Set it to zero to indicate that NRVO was not
847            // applied.
848            llvm::Value *Zero = Builder.getFalse();
849            llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
850            EnsureInsertPoint();
851            Builder.CreateStore(Zero, NRVOFlag);
852
853            // Record the NRVO flag for this variable.
854            NRVOFlags[&D] = NRVOFlag;
855            emission.NRVOFlag = NRVOFlag;
856          }
857        }
858      } else {
859        if (isByRef)
860          LTy = BuildByRefType(&D);
861
862        llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
863        Alloc->setName(D.getName());
864
865        CharUnits allocaAlignment = alignment;
866        if (isByRef)
867          allocaAlignment = std::max(allocaAlignment,
868              getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
869        Alloc->setAlignment(allocaAlignment.getQuantity());
870        DeclPtr = Alloc;
871      }
872    } else {
873      // Targets that don't support recursion emit locals as globals.
874      const char *Class =
875        D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
876      DeclPtr = CreateStaticVarDecl(D, Class,
877                                    llvm::GlobalValue::InternalLinkage);
878    }
879  } else {
880    EnsureInsertPoint();
881
882    if (!DidCallStackSave) {
883      // Save the stack.
884      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
885
886      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
887      llvm::Value *V = Builder.CreateCall(F);
888
889      Builder.CreateStore(V, Stack);
890
891      DidCallStackSave = true;
892
893      // Push a cleanup block and restore the stack there.
894      // FIXME: in general circumstances, this should be an EH cleanup.
895      EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
896    }
897
898    llvm::Value *elementCount;
899    QualType elementType;
900    llvm::tie(elementCount, elementType) = getVLASize(Ty);
901
902    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
903
904    // Allocate memory for the array.
905    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
906    vla->setAlignment(alignment.getQuantity());
907
908    DeclPtr = vla;
909  }
910
911  llvm::Value *&DMEntry = LocalDeclMap[&D];
912  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
913  DMEntry = DeclPtr;
914  emission.Address = DeclPtr;
915
916  // Emit debug info for local var declaration.
917  if (HaveInsertPoint())
918    if (CGDebugInfo *DI = getDebugInfo()) {
919      if (CGM.getCodeGenOpts().DebugInfo >= CodeGenOptions::LimitedDebugInfo) {
920        DI->setLocation(D.getLocation());
921        if (Target.useGlobalsForAutomaticVariables()) {
922          DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr),
923                                 &D);
924        } else
925          DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
926      }
927    }
928
929  if (D.hasAttr<AnnotateAttr>())
930      EmitVarAnnotations(&D, emission.Address);
931
932  return emission;
933}
934
935/// Determines whether the given __block variable is potentially
936/// captured by the given expression.
937static bool isCapturedBy(const VarDecl &var, const Expr *e) {
938  // Skip the most common kinds of expressions that make
939  // hierarchy-walking expensive.
940  e = e->IgnoreParenCasts();
941
942  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
943    const BlockDecl *block = be->getBlockDecl();
944    for (BlockDecl::capture_const_iterator i = block->capture_begin(),
945           e = block->capture_end(); i != e; ++i) {
946      if (i->getVariable() == &var)
947        return true;
948    }
949
950    // No need to walk into the subexpressions.
951    return false;
952  }
953
954  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
955    const CompoundStmt *CS = SE->getSubStmt();
956    for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
957	   BE = CS->body_end(); BI != BE; ++BI)
958      if (Expr *E = dyn_cast<Expr>((*BI))) {
959        if (isCapturedBy(var, E))
960            return true;
961      }
962      else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) {
963          // special case declarations
964          for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
965               I != E; ++I) {
966              if (VarDecl *VD = dyn_cast<VarDecl>((*I))) {
967                Expr *Init = VD->getInit();
968                if (Init && isCapturedBy(var, Init))
969                  return true;
970              }
971          }
972      }
973      else
974        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
975        // Later, provide code to poke into statements for capture analysis.
976        return true;
977    return false;
978  }
979
980  for (Stmt::const_child_range children = e->children(); children; ++children)
981    if (isCapturedBy(var, cast<Expr>(*children)))
982      return true;
983
984  return false;
985}
986
987/// \brief Determine whether the given initializer is trivial in the sense
988/// that it requires no code to be generated.
989static bool isTrivialInitializer(const Expr *Init) {
990  if (!Init)
991    return true;
992
993  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
994    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
995      if (Constructor->isTrivial() &&
996          Constructor->isDefaultConstructor() &&
997          !Construct->requiresZeroInitialization())
998        return true;
999
1000  return false;
1001}
1002void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
1003  assert(emission.Variable && "emission was not valid!");
1004
1005  // If this was emitted as a global constant, we're done.
1006  if (emission.wasEmittedAsGlobal()) return;
1007
1008  const VarDecl &D = *emission.Variable;
1009  QualType type = D.getType();
1010
1011  // If this local has an initializer, emit it now.
1012  const Expr *Init = D.getInit();
1013
1014  // If we are at an unreachable point, we don't need to emit the initializer
1015  // unless it contains a label.
1016  if (!HaveInsertPoint()) {
1017    if (!Init || !ContainsLabel(Init)) return;
1018    EnsureInsertPoint();
1019  }
1020
1021  // Initialize the structure of a __block variable.
1022  if (emission.IsByRef)
1023    emitByrefStructureInit(emission);
1024
1025  if (isTrivialInitializer(Init))
1026    return;
1027
1028  CharUnits alignment = emission.Alignment;
1029
1030  // Check whether this is a byref variable that's potentially
1031  // captured and moved by its own initializer.  If so, we'll need to
1032  // emit the initializer first, then copy into the variable.
1033  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
1034
1035  llvm::Value *Loc =
1036    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
1037
1038  llvm::Constant *constant = 0;
1039  if (emission.IsConstantAggregate) {
1040    assert(!capturedByInit && "constant init contains a capturing block?");
1041    constant = CGM.EmitConstantInit(D, this);
1042  }
1043
1044  if (!constant) {
1045    LValue lv = MakeAddrLValue(Loc, type, alignment);
1046    lv.setNonGC(true);
1047    return EmitExprAsInit(Init, &D, lv, capturedByInit);
1048  }
1049
1050  // If this is a simple aggregate initialization, we can optimize it
1051  // in various ways.
1052  bool isVolatile = type.isVolatileQualified();
1053
1054  llvm::Value *SizeVal =
1055    llvm::ConstantInt::get(IntPtrTy,
1056                           getContext().getTypeSizeInChars(type).getQuantity());
1057
1058  llvm::Type *BP = Int8PtrTy;
1059  if (Loc->getType() != BP)
1060    Loc = Builder.CreateBitCast(Loc, BP);
1061
1062  // If the initializer is all or mostly zeros, codegen with memset then do
1063  // a few stores afterward.
1064  if (shouldUseMemSetPlusStoresToInitialize(constant,
1065                CGM.getTargetData().getTypeAllocSize(constant->getType()))) {
1066    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
1067                         alignment.getQuantity(), isVolatile);
1068    if (!constant->isNullValue()) {
1069      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
1070      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
1071    }
1072  } else {
1073    // Otherwise, create a temporary global with the initializer then
1074    // memcpy from the global to the alloca.
1075    std::string Name = GetStaticDeclName(*this, D, ".");
1076    llvm::GlobalVariable *GV =
1077      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1078                               llvm::GlobalValue::PrivateLinkage,
1079                               constant, Name);
1080    GV->setAlignment(alignment.getQuantity());
1081    GV->setUnnamedAddr(true);
1082
1083    llvm::Value *SrcPtr = GV;
1084    if (SrcPtr->getType() != BP)
1085      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1086
1087    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1088                         isVolatile);
1089  }
1090}
1091
1092/// Emit an expression as an initializer for a variable at the given
1093/// location.  The expression is not necessarily the normal
1094/// initializer for the variable, and the address is not necessarily
1095/// its normal location.
1096///
1097/// \param init the initializing expression
1098/// \param var the variable to act as if we're initializing
1099/// \param loc the address to initialize; its type is a pointer
1100///   to the LLVM mapping of the variable's type
1101/// \param alignment the alignment of the address
1102/// \param capturedByInit true if the variable is a __block variable
1103///   whose address is potentially changed by the initializer
1104void CodeGenFunction::EmitExprAsInit(const Expr *init,
1105                                     const ValueDecl *D,
1106                                     LValue lvalue,
1107                                     bool capturedByInit) {
1108  QualType type = D->getType();
1109
1110  if (type->isReferenceType()) {
1111    RValue rvalue = EmitReferenceBindingToExpr(init, D);
1112    if (capturedByInit)
1113      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1114    EmitStoreThroughLValue(rvalue, lvalue, true);
1115  } else if (!hasAggregateLLVMType(type)) {
1116    EmitScalarInit(init, D, lvalue, capturedByInit);
1117  } else if (type->isAnyComplexType()) {
1118    ComplexPairTy complex = EmitComplexExpr(init);
1119    if (capturedByInit)
1120      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1121    StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile());
1122  } else {
1123    // TODO: how can we delay here if D is captured by its initializer?
1124    EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1125                                              AggValueSlot::IsDestructed,
1126                                         AggValueSlot::DoesNotNeedGCBarriers,
1127                                              AggValueSlot::IsNotAliased));
1128    MaybeEmitStdInitializerListCleanup(lvalue.getAddress(), init);
1129  }
1130}
1131
1132/// Enter a destroy cleanup for the given local variable.
1133void CodeGenFunction::emitAutoVarTypeCleanup(
1134                            const CodeGenFunction::AutoVarEmission &emission,
1135                            QualType::DestructionKind dtorKind) {
1136  assert(dtorKind != QualType::DK_none);
1137
1138  // Note that for __block variables, we want to destroy the
1139  // original stack object, not the possibly forwarded object.
1140  llvm::Value *addr = emission.getObjectAddress(*this);
1141
1142  const VarDecl *var = emission.Variable;
1143  QualType type = var->getType();
1144
1145  CleanupKind cleanupKind = NormalAndEHCleanup;
1146  CodeGenFunction::Destroyer *destroyer = 0;
1147
1148  switch (dtorKind) {
1149  case QualType::DK_none:
1150    llvm_unreachable("no cleanup for trivially-destructible variable");
1151
1152  case QualType::DK_cxx_destructor:
1153    // If there's an NRVO flag on the emission, we need a different
1154    // cleanup.
1155    if (emission.NRVOFlag) {
1156      assert(!type->isArrayType());
1157      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1158      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1159                                               emission.NRVOFlag);
1160      return;
1161    }
1162    break;
1163
1164  case QualType::DK_objc_strong_lifetime:
1165    // Suppress cleanups for pseudo-strong variables.
1166    if (var->isARCPseudoStrong()) return;
1167
1168    // Otherwise, consider whether to use an EH cleanup or not.
1169    cleanupKind = getARCCleanupKind();
1170
1171    // Use the imprecise destroyer by default.
1172    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1173      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1174    break;
1175
1176  case QualType::DK_objc_weak_lifetime:
1177    break;
1178  }
1179
1180  // If we haven't chosen a more specific destroyer, use the default.
1181  if (!destroyer) destroyer = getDestroyer(dtorKind);
1182
1183  // Use an EH cleanup in array destructors iff the destructor itself
1184  // is being pushed as an EH cleanup.
1185  bool useEHCleanup = (cleanupKind & EHCleanup);
1186  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1187                                     useEHCleanup);
1188}
1189
1190void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1191  assert(emission.Variable && "emission was not valid!");
1192
1193  // If this was emitted as a global constant, we're done.
1194  if (emission.wasEmittedAsGlobal()) return;
1195
1196  // If we don't have an insertion point, we're done.  Sema prevents
1197  // us from jumping into any of these scopes anyway.
1198  if (!HaveInsertPoint()) return;
1199
1200  const VarDecl &D = *emission.Variable;
1201
1202  // Check the type for a cleanup.
1203  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1204    emitAutoVarTypeCleanup(emission, dtorKind);
1205
1206  // In GC mode, honor objc_precise_lifetime.
1207  if (getLangOpts().getGC() != LangOptions::NonGC &&
1208      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1209    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1210  }
1211
1212  // Handle the cleanup attribute.
1213  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1214    const FunctionDecl *FD = CA->getFunctionDecl();
1215
1216    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1217    assert(F && "Could not find function!");
1218
1219    const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
1220    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1221  }
1222
1223  // If this is a block variable, call _Block_object_destroy
1224  // (on the unforwarded address).
1225  if (emission.IsByRef)
1226    enterByrefCleanup(emission);
1227}
1228
1229CodeGenFunction::Destroyer *
1230CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1231  switch (kind) {
1232  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1233  case QualType::DK_cxx_destructor:
1234    return destroyCXXObject;
1235  case QualType::DK_objc_strong_lifetime:
1236    return destroyARCStrongPrecise;
1237  case QualType::DK_objc_weak_lifetime:
1238    return destroyARCWeak;
1239  }
1240  llvm_unreachable("Unknown DestructionKind");
1241}
1242
1243/// pushDestroy - Push the standard destructor for the given type.
1244void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1245                                  llvm::Value *addr, QualType type) {
1246  assert(dtorKind && "cannot push destructor for trivial type");
1247
1248  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1249  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1250              cleanupKind & EHCleanup);
1251}
1252
1253void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1254                                  QualType type, Destroyer *destroyer,
1255                                  bool useEHCleanupForArray) {
1256  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1257                                     destroyer, useEHCleanupForArray);
1258}
1259
1260/// emitDestroy - Immediately perform the destruction of the given
1261/// object.
1262///
1263/// \param addr - the address of the object; a type*
1264/// \param type - the type of the object; if an array type, all
1265///   objects are destroyed in reverse order
1266/// \param destroyer - the function to call to destroy individual
1267///   elements
1268/// \param useEHCleanupForArray - whether an EH cleanup should be
1269///   used when destroying array elements, in case one of the
1270///   destructions throws an exception
1271void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1272                                  Destroyer *destroyer,
1273                                  bool useEHCleanupForArray) {
1274  const ArrayType *arrayType = getContext().getAsArrayType(type);
1275  if (!arrayType)
1276    return destroyer(*this, addr, type);
1277
1278  llvm::Value *begin = addr;
1279  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1280
1281  // Normally we have to check whether the array is zero-length.
1282  bool checkZeroLength = true;
1283
1284  // But if the array length is constant, we can suppress that.
1285  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1286    // ...and if it's constant zero, we can just skip the entire thing.
1287    if (constLength->isZero()) return;
1288    checkZeroLength = false;
1289  }
1290
1291  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1292  emitArrayDestroy(begin, end, type, destroyer,
1293                   checkZeroLength, useEHCleanupForArray);
1294}
1295
1296/// emitArrayDestroy - Destroys all the elements of the given array,
1297/// beginning from last to first.  The array cannot be zero-length.
1298///
1299/// \param begin - a type* denoting the first element of the array
1300/// \param end - a type* denoting one past the end of the array
1301/// \param type - the element type of the array
1302/// \param destroyer - the function to call to destroy elements
1303/// \param useEHCleanup - whether to push an EH cleanup to destroy
1304///   the remaining elements in case the destruction of a single
1305///   element throws
1306void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1307                                       llvm::Value *end,
1308                                       QualType type,
1309                                       Destroyer *destroyer,
1310                                       bool checkZeroLength,
1311                                       bool useEHCleanup) {
1312  assert(!type->isArrayType());
1313
1314  // The basic structure here is a do-while loop, because we don't
1315  // need to check for the zero-element case.
1316  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1317  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1318
1319  if (checkZeroLength) {
1320    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1321                                                "arraydestroy.isempty");
1322    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1323  }
1324
1325  // Enter the loop body, making that address the current address.
1326  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1327  EmitBlock(bodyBB);
1328  llvm::PHINode *elementPast =
1329    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1330  elementPast->addIncoming(end, entryBB);
1331
1332  // Shift the address back by one element.
1333  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1334  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1335                                                   "arraydestroy.element");
1336
1337  if (useEHCleanup)
1338    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1339
1340  // Perform the actual destruction there.
1341  destroyer(*this, element, type);
1342
1343  if (useEHCleanup)
1344    PopCleanupBlock();
1345
1346  // Check whether we've reached the end.
1347  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1348  Builder.CreateCondBr(done, doneBB, bodyBB);
1349  elementPast->addIncoming(element, Builder.GetInsertBlock());
1350
1351  // Done.
1352  EmitBlock(doneBB);
1353}
1354
1355/// Perform partial array destruction as if in an EH cleanup.  Unlike
1356/// emitArrayDestroy, the element type here may still be an array type.
1357static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1358                                    llvm::Value *begin, llvm::Value *end,
1359                                    QualType type,
1360                                    CodeGenFunction::Destroyer *destroyer) {
1361  // If the element type is itself an array, drill down.
1362  unsigned arrayDepth = 0;
1363  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1364    // VLAs don't require a GEP index to walk into.
1365    if (!isa<VariableArrayType>(arrayType))
1366      arrayDepth++;
1367    type = arrayType->getElementType();
1368  }
1369
1370  if (arrayDepth) {
1371    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1372
1373    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1374    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1375    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1376  }
1377
1378  // Destroy the array.  We don't ever need an EH cleanup because we
1379  // assume that we're in an EH cleanup ourselves, so a throwing
1380  // destructor causes an immediate terminate.
1381  CGF.emitArrayDestroy(begin, end, type, destroyer,
1382                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1383}
1384
1385namespace {
1386  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1387  /// array destroy where the end pointer is regularly determined and
1388  /// does not need to be loaded from a local.
1389  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1390    llvm::Value *ArrayBegin;
1391    llvm::Value *ArrayEnd;
1392    QualType ElementType;
1393    CodeGenFunction::Destroyer *Destroyer;
1394  public:
1395    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1396                               QualType elementType,
1397                               CodeGenFunction::Destroyer *destroyer)
1398      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1399        ElementType(elementType), Destroyer(destroyer) {}
1400
1401    void Emit(CodeGenFunction &CGF, Flags flags) {
1402      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1403                              ElementType, Destroyer);
1404    }
1405  };
1406
1407  /// IrregularPartialArrayDestroy - a cleanup which performs a
1408  /// partial array destroy where the end pointer is irregularly
1409  /// determined and must be loaded from a local.
1410  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1411    llvm::Value *ArrayBegin;
1412    llvm::Value *ArrayEndPointer;
1413    QualType ElementType;
1414    CodeGenFunction::Destroyer *Destroyer;
1415  public:
1416    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1417                                 llvm::Value *arrayEndPointer,
1418                                 QualType elementType,
1419                                 CodeGenFunction::Destroyer *destroyer)
1420      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1421        ElementType(elementType), Destroyer(destroyer) {}
1422
1423    void Emit(CodeGenFunction &CGF, Flags flags) {
1424      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1425      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1426                              ElementType, Destroyer);
1427    }
1428  };
1429}
1430
1431/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1432/// already-constructed elements of the given array.  The cleanup
1433/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1434///
1435/// \param elementType - the immediate element type of the array;
1436///   possibly still an array type
1437/// \param array - a value of type elementType*
1438/// \param destructionKind - the kind of destruction required
1439/// \param initializedElementCount - a value of type size_t* holding
1440///   the number of successfully-constructed elements
1441void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1442                                                 llvm::Value *arrayEndPointer,
1443                                                       QualType elementType,
1444                                                       Destroyer *destroyer) {
1445  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1446                                                    arrayBegin, arrayEndPointer,
1447                                                    elementType, destroyer);
1448}
1449
1450/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1451/// already-constructed elements of the given array.  The cleanup
1452/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1453///
1454/// \param elementType - the immediate element type of the array;
1455///   possibly still an array type
1456/// \param array - a value of type elementType*
1457/// \param destructionKind - the kind of destruction required
1458/// \param initializedElementCount - a value of type size_t* holding
1459///   the number of successfully-constructed elements
1460void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1461                                                     llvm::Value *arrayEnd,
1462                                                     QualType elementType,
1463                                                     Destroyer *destroyer) {
1464  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1465                                                  arrayBegin, arrayEnd,
1466                                                  elementType, destroyer);
1467}
1468
1469namespace {
1470  /// A cleanup to perform a release of an object at the end of a
1471  /// function.  This is used to balance out the incoming +1 of a
1472  /// ns_consumed argument when we can't reasonably do that just by
1473  /// not doing the initial retain for a __block argument.
1474  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1475    ConsumeARCParameter(llvm::Value *param) : Param(param) {}
1476
1477    llvm::Value *Param;
1478
1479    void Emit(CodeGenFunction &CGF, Flags flags) {
1480      CGF.EmitARCRelease(Param, /*precise*/ false);
1481    }
1482  };
1483}
1484
1485/// Emit an alloca (or GlobalValue depending on target)
1486/// for the specified parameter and set up LocalDeclMap.
1487void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1488                                   unsigned ArgNo) {
1489  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1490  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1491         "Invalid argument to EmitParmDecl");
1492
1493  Arg->setName(D.getName());
1494
1495  // Use better IR generation for certain implicit parameters.
1496  if (isa<ImplicitParamDecl>(D)) {
1497    // The only implicit argument a block has is its literal.
1498    if (BlockInfo) {
1499      LocalDeclMap[&D] = Arg;
1500
1501      if (CGDebugInfo *DI = getDebugInfo()) {
1502        if (CGM.getCodeGenOpts().DebugInfo >=
1503            CodeGenOptions::LimitedDebugInfo) {
1504          DI->setLocation(D.getLocation());
1505          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
1506        }
1507      }
1508
1509      return;
1510    }
1511  }
1512
1513  QualType Ty = D.getType();
1514
1515  llvm::Value *DeclPtr;
1516  // If this is an aggregate or variable sized value, reuse the input pointer.
1517  if (!Ty->isConstantSizeType() ||
1518      CodeGenFunction::hasAggregateLLVMType(Ty)) {
1519    DeclPtr = Arg;
1520  } else {
1521    // Otherwise, create a temporary to hold the value.
1522    llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1523                                               D.getName() + ".addr");
1524    Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
1525    DeclPtr = Alloc;
1526
1527    bool doStore = true;
1528
1529    Qualifiers qs = Ty.getQualifiers();
1530
1531    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1532      // We honor __attribute__((ns_consumed)) for types with lifetime.
1533      // For __strong, it's handled by just skipping the initial retain;
1534      // otherwise we have to balance out the initial +1 with an extra
1535      // cleanup to do the release at the end of the function.
1536      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1537
1538      // 'self' is always formally __strong, but if this is not an
1539      // init method then we don't want to retain it.
1540      if (D.isARCPseudoStrong()) {
1541        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1542        assert(&D == method->getSelfDecl());
1543        assert(lt == Qualifiers::OCL_Strong);
1544        assert(qs.hasConst());
1545        assert(method->getMethodFamily() != OMF_init);
1546        (void) method;
1547        lt = Qualifiers::OCL_ExplicitNone;
1548      }
1549
1550      if (lt == Qualifiers::OCL_Strong) {
1551        if (!isConsumed)
1552          // Don't use objc_retainBlock for block pointers, because we
1553          // don't want to Block_copy something just because we got it
1554          // as a parameter.
1555          Arg = EmitARCRetainNonBlock(Arg);
1556      } else {
1557        // Push the cleanup for a consumed parameter.
1558        if (isConsumed)
1559          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg);
1560
1561        if (lt == Qualifiers::OCL_Weak) {
1562          EmitARCInitWeak(DeclPtr, Arg);
1563          doStore = false; // The weak init is a store, no need to do two.
1564        }
1565      }
1566
1567      // Enter the cleanup scope.
1568      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1569    }
1570
1571    // Store the initial value into the alloca.
1572    if (doStore) {
1573      LValue lv = MakeAddrLValue(DeclPtr, Ty,
1574                                 getContext().getDeclAlign(&D));
1575      EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1576    }
1577  }
1578
1579  llvm::Value *&DMEntry = LocalDeclMap[&D];
1580  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
1581  DMEntry = DeclPtr;
1582
1583  // Emit debug info for param declaration.
1584  if (CGDebugInfo *DI = getDebugInfo()) {
1585    if (CGM.getCodeGenOpts().DebugInfo >= CodeGenOptions::LimitedDebugInfo) {
1586      DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1587    }
1588  }
1589
1590  if (D.hasAttr<AnnotateAttr>())
1591      EmitVarAnnotations(&D, DeclPtr);
1592}
1593