CGDecl.cpp revision e289d81369914678db386f6aa86faf8f178e245d 
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 "clang/AST/ASTContext.h"
18#include "clang/AST/CharUnits.h"
19#include "clang/AST/Decl.h"
20#include "clang/AST/DeclObjC.h"
21#include "clang/Basic/SourceManager.h"
22#include "clang/Basic/TargetInfo.h"
23#include "clang/Frontend/CodeGenOptions.h"
24#include "llvm/GlobalVariable.h"
25#include "llvm/Intrinsics.h"
26#include "llvm/Target/TargetData.h"
27#include "llvm/Type.h"
28using namespace clang;
29using namespace CodeGen;
30
31
32void CodeGenFunction::EmitDecl(const Decl &D) {
33  switch (D.getKind()) {
34  case Decl::TranslationUnit:
35  case Decl::Namespace:
36  case Decl::UnresolvedUsingTypename:
37  case Decl::ClassTemplateSpecialization:
38  case Decl::ClassTemplatePartialSpecialization:
39  case Decl::TemplateTypeParm:
40  case Decl::UnresolvedUsingValue:
41  case Decl::NonTypeTemplateParm:
42  case Decl::CXXMethod:
43  case Decl::CXXConstructor:
44  case Decl::CXXDestructor:
45  case Decl::CXXConversion:
46  case Decl::Field:
47  case Decl::IndirectField:
48  case Decl::ObjCIvar:
49  case Decl::ObjCAtDefsField:
50  case Decl::ParmVar:
51  case Decl::ImplicitParam:
52  case Decl::ClassTemplate:
53  case Decl::FunctionTemplate:
54  case Decl::TypeAliasTemplate:
55  case Decl::TemplateTemplateParm:
56  case Decl::ObjCMethod:
57  case Decl::ObjCCategory:
58  case Decl::ObjCProtocol:
59  case Decl::ObjCInterface:
60  case Decl::ObjCCategoryImpl:
61  case Decl::ObjCImplementation:
62  case Decl::ObjCProperty:
63  case Decl::ObjCCompatibleAlias:
64  case Decl::AccessSpec:
65  case Decl::LinkageSpec:
66  case Decl::ObjCPropertyImpl:
67  case Decl::ObjCClass:
68  case Decl::ObjCForwardProtocol:
69  case Decl::FileScopeAsm:
70  case Decl::Friend:
71  case Decl::FriendTemplate:
72  case Decl::Block:
73  case Decl::ClassScopeFunctionSpecialization:
74    assert(0 && "Declaration should not be in declstmts!");
75  case Decl::Function:  // void X();
76  case Decl::Record:    // struct/union/class X;
77  case Decl::Enum:      // enum X;
78  case Decl::EnumConstant: // enum ? { X = ? }
79  case Decl::CXXRecord: // struct/union/class X; [C++]
80  case Decl::Using:          // using X; [C++]
81  case Decl::UsingShadow:
82  case Decl::UsingDirective: // using namespace X; [C++]
83  case Decl::NamespaceAlias:
84  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
85  case Decl::Label:        // __label__ x;
86    // 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().getLangOptions().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  }
135
136  assert(0 && "Unknown storage class");
137}
138
139static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
140                                     const char *Separator) {
141  CodeGenModule &CGM = CGF.CGM;
142  if (CGF.getContext().getLangOptions().CPlusPlus) {
143    StringRef Name = CGM.getMangledName(&D);
144    return Name.str();
145  }
146
147  std::string ContextName;
148  if (!CGF.CurFuncDecl) {
149    // Better be in a block declared in global scope.
150    const NamedDecl *ND = cast<NamedDecl>(&D);
151    const DeclContext *DC = ND->getDeclContext();
152    if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
153      MangleBuffer Name;
154      CGM.getBlockMangledName(GlobalDecl(), Name, BD);
155      ContextName = Name.getString();
156    }
157    else
158      assert(0 && "Unknown context for block static var decl");
159  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
160    StringRef Name = CGM.getMangledName(FD);
161    ContextName = Name.str();
162  } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
163    ContextName = CGF.CurFn->getName();
164  else
165    assert(0 && "Unknown context for static var decl");
166
167  return ContextName + Separator + D.getNameAsString();
168}
169
170llvm::GlobalVariable *
171CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
172                                     const char *Separator,
173                                     llvm::GlobalValue::LinkageTypes Linkage) {
174  QualType Ty = D.getType();
175  assert(Ty->isConstantSizeType() && "VLAs can't be static");
176
177  std::string Name = GetStaticDeclName(*this, D, Separator);
178
179  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
180  llvm::GlobalVariable *GV =
181    new llvm::GlobalVariable(CGM.getModule(), LTy,
182                             Ty.isConstant(getContext()), Linkage,
183                             CGM.EmitNullConstant(D.getType()), Name, 0,
184                             D.isThreadSpecified(),
185                             CGM.getContext().getTargetAddressSpace(Ty));
186  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
187  if (Linkage != llvm::GlobalValue::InternalLinkage)
188    GV->setVisibility(CurFn->getVisibility());
189  return GV;
190}
191
192/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
193/// global variable that has already been created for it.  If the initializer
194/// has a different type than GV does, this may free GV and return a different
195/// one.  Otherwise it just returns GV.
196llvm::GlobalVariable *
197CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
198                                               llvm::GlobalVariable *GV) {
199  llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this);
200
201  // If constant emission failed, then this should be a C++ static
202  // initializer.
203  if (!Init) {
204    if (!getContext().getLangOptions().CPlusPlus)
205      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
206    else if (Builder.GetInsertBlock()) {
207      // Since we have a static initializer, this global variable can't
208      // be constant.
209      GV->setConstant(false);
210
211      EmitCXXGuardedInit(D, GV);
212    }
213    return GV;
214  }
215
216  // The initializer may differ in type from the global. Rewrite
217  // the global to match the initializer.  (We have to do this
218  // because some types, like unions, can't be completely represented
219  // in the LLVM type system.)
220  if (GV->getType()->getElementType() != Init->getType()) {
221    llvm::GlobalVariable *OldGV = GV;
222
223    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
224                                  OldGV->isConstant(),
225                                  OldGV->getLinkage(), Init, "",
226                                  /*InsertBefore*/ OldGV,
227                                  D.isThreadSpecified(),
228                           CGM.getContext().getTargetAddressSpace(D.getType()));
229    GV->setVisibility(OldGV->getVisibility());
230
231    // Steal the name of the old global
232    GV->takeName(OldGV);
233
234    // Replace all uses of the old global with the new global
235    llvm::Constant *NewPtrForOldDecl =
236    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
237    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
238
239    // Erase the old global, since it is no longer used.
240    OldGV->eraseFromParent();
241  }
242
243  GV->setInitializer(Init);
244  return GV;
245}
246
247void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
248                                      llvm::GlobalValue::LinkageTypes Linkage) {
249  llvm::Value *&DMEntry = LocalDeclMap[&D];
250  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
251
252  llvm::GlobalVariable *GV = CreateStaticVarDecl(D, ".", Linkage);
253
254  // Store into LocalDeclMap before generating initializer to handle
255  // circular references.
256  DMEntry = GV;
257
258  // We can't have a VLA here, but we can have a pointer to a VLA,
259  // even though that doesn't really make any sense.
260  // Make sure to evaluate VLA bounds now so that we have them for later.
261  if (D.getType()->isVariablyModifiedType())
262    EmitVariablyModifiedType(D.getType());
263
264  // Local static block variables must be treated as globals as they may be
265  // referenced in their RHS initializer block-literal expresion.
266  CGM.setStaticLocalDeclAddress(&D, GV);
267
268  // If this value has an initializer, emit it.
269  if (D.getInit())
270    GV = AddInitializerToStaticVarDecl(D, GV);
271
272  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
273
274  if (D.hasAttr<AnnotateAttr>())
275    CGM.AddGlobalAnnotations(&D, GV);
276
277  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
278    GV->setSection(SA->getName());
279
280  if (D.hasAttr<UsedAttr>())
281    CGM.AddUsedGlobal(GV);
282
283  // We may have to cast the constant because of the initializer
284  // mismatch above.
285  //
286  // FIXME: It is really dangerous to store this in the map; if anyone
287  // RAUW's the GV uses of this constant will be invalid.
288  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
289  llvm::Type *LPtrTy =
290    LTy->getPointerTo(CGM.getContext().getTargetAddressSpace(D.getType()));
291  DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
292
293  // Emit global variable debug descriptor for static vars.
294  CGDebugInfo *DI = getDebugInfo();
295  if (DI) {
296    DI->setLocation(D.getLocation());
297    DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
298  }
299}
300
301namespace {
302  struct DestroyObject : EHScopeStack::Cleanup {
303    DestroyObject(llvm::Value *addr, QualType type,
304                  CodeGenFunction::Destroyer *destroyer,
305                  bool useEHCleanupForArray)
306      : addr(addr), type(type), destroyer(*destroyer),
307        useEHCleanupForArray(useEHCleanupForArray) {}
308
309    llvm::Value *addr;
310    QualType type;
311    CodeGenFunction::Destroyer &destroyer;
312    bool useEHCleanupForArray;
313
314    void Emit(CodeGenFunction &CGF, Flags flags) {
315      // Don't use an EH cleanup recursively from an EH cleanup.
316      bool useEHCleanupForArray =
317        flags.isForNormalCleanup() && this->useEHCleanupForArray;
318
319      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
320    }
321  };
322
323  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
324    DestroyNRVOVariable(llvm::Value *addr,
325                        const CXXDestructorDecl *Dtor,
326                        llvm::Value *NRVOFlag)
327      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
328
329    const CXXDestructorDecl *Dtor;
330    llvm::Value *NRVOFlag;
331    llvm::Value *Loc;
332
333    void Emit(CodeGenFunction &CGF, Flags flags) {
334      // Along the exceptions path we always execute the dtor.
335      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
336
337      llvm::BasicBlock *SkipDtorBB = 0;
338      if (NRVO) {
339        // If we exited via NRVO, we skip the destructor call.
340        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
341        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
342        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
343        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
344        CGF.EmitBlock(RunDtorBB);
345      }
346
347      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
348                                /*ForVirtualBase=*/false, Loc);
349
350      if (NRVO) CGF.EmitBlock(SkipDtorBB);
351    }
352  };
353
354  struct CallStackRestore : EHScopeStack::Cleanup {
355    llvm::Value *Stack;
356    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
357    void Emit(CodeGenFunction &CGF, Flags flags) {
358      llvm::Value *V = CGF.Builder.CreateLoad(Stack, "tmp");
359      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
360      CGF.Builder.CreateCall(F, V);
361    }
362  };
363
364  struct ExtendGCLifetime : EHScopeStack::Cleanup {
365    const VarDecl &Var;
366    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
367
368    void Emit(CodeGenFunction &CGF, Flags flags) {
369      // Compute the address of the local variable, in case it's a
370      // byref or something.
371      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
372                      SourceLocation());
373      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
374      CGF.EmitExtendGCLifetime(value);
375    }
376  };
377
378  struct CallCleanupFunction : EHScopeStack::Cleanup {
379    llvm::Constant *CleanupFn;
380    const CGFunctionInfo &FnInfo;
381    const VarDecl &Var;
382
383    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
384                        const VarDecl *Var)
385      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
386
387    void Emit(CodeGenFunction &CGF, Flags flags) {
388      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
389                      SourceLocation());
390      // Compute the address of the local variable, in case it's a byref
391      // or something.
392      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
393
394      // In some cases, the type of the function argument will be different from
395      // the type of the pointer. An example of this is
396      // void f(void* arg);
397      // __attribute__((cleanup(f))) void *g;
398      //
399      // To fix this we insert a bitcast here.
400      QualType ArgTy = FnInfo.arg_begin()->type;
401      llvm::Value *Arg =
402        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
403
404      CallArgList Args;
405      Args.add(RValue::get(Arg),
406               CGF.getContext().getPointerType(Var.getType()));
407      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
408    }
409  };
410}
411
412/// EmitAutoVarWithLifetime - Does the setup required for an automatic
413/// variable with lifetime.
414static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
415                                    llvm::Value *addr,
416                                    Qualifiers::ObjCLifetime lifetime) {
417  switch (lifetime) {
418  case Qualifiers::OCL_None:
419    llvm_unreachable("present but none");
420
421  case Qualifiers::OCL_ExplicitNone:
422    // nothing to do
423    break;
424
425  case Qualifiers::OCL_Strong: {
426    CodeGenFunction::Destroyer &destroyer =
427      (var.hasAttr<ObjCPreciseLifetimeAttr>()
428       ? CodeGenFunction::destroyARCStrongPrecise
429       : CodeGenFunction::destroyARCStrongImprecise);
430
431    CleanupKind cleanupKind = CGF.getARCCleanupKind();
432    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
433                    cleanupKind & EHCleanup);
434    break;
435  }
436  case Qualifiers::OCL_Autoreleasing:
437    // nothing to do
438    break;
439
440  case Qualifiers::OCL_Weak:
441    // __weak objects always get EH cleanups; otherwise, exceptions
442    // could cause really nasty crashes instead of mere leaks.
443    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
444                    CodeGenFunction::destroyARCWeak,
445                    /*useEHCleanup*/ true);
446    break;
447  }
448}
449
450static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
451  if (const Expr *e = dyn_cast<Expr>(s)) {
452    // Skip the most common kinds of expressions that make
453    // hierarchy-walking expensive.
454    s = e = e->IgnoreParenCasts();
455
456    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
457      return (ref->getDecl() == &var);
458  }
459
460  for (Stmt::const_child_range children = s->children(); children; ++children)
461    // children might be null; as in missing decl or conditional of an if-stmt.
462    if ((*children) && isAccessedBy(var, *children))
463      return true;
464
465  return false;
466}
467
468static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
469  if (!decl) return false;
470  if (!isa<VarDecl>(decl)) return false;
471  const VarDecl *var = cast<VarDecl>(decl);
472  return isAccessedBy(*var, e);
473}
474
475static void drillIntoBlockVariable(CodeGenFunction &CGF,
476                                   LValue &lvalue,
477                                   const VarDecl *var) {
478  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
479}
480
481void CodeGenFunction::EmitScalarInit(const Expr *init,
482                                     const ValueDecl *D,
483                                     LValue lvalue,
484                                     bool capturedByInit) {
485  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
486  if (!lifetime) {
487    llvm::Value *value = EmitScalarExpr(init);
488    if (capturedByInit)
489      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
490    EmitStoreThroughLValue(RValue::get(value), lvalue);
491    return;
492  }
493
494  // If we're emitting a value with lifetime, we have to do the
495  // initialization *before* we leave the cleanup scopes.
496  CodeGenFunction::RunCleanupsScope Scope(*this);
497  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init))
498    init = ewc->getSubExpr();
499
500  // We have to maintain the illusion that the variable is
501  // zero-initialized.  If the variable might be accessed in its
502  // initializer, zero-initialize before running the initializer, then
503  // actually perform the initialization with an assign.
504  bool accessedByInit = false;
505  if (lifetime != Qualifiers::OCL_ExplicitNone)
506    accessedByInit = (capturedByInit || isAccessedBy(D, init));
507  if (accessedByInit) {
508    LValue tempLV = lvalue;
509    // Drill down to the __block object if necessary.
510    if (capturedByInit) {
511      // We can use a simple GEP for this because it can't have been
512      // moved yet.
513      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
514                                   getByRefValueLLVMField(cast<VarDecl>(D))));
515    }
516
517    llvm::PointerType *ty
518      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
519    ty = cast<llvm::PointerType>(ty->getElementType());
520
521    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
522
523    // If __weak, we want to use a barrier under certain conditions.
524    if (lifetime == Qualifiers::OCL_Weak)
525      EmitARCInitWeak(tempLV.getAddress(), zero);
526
527    // Otherwise just do a simple store.
528    else
529      EmitStoreOfScalar(zero, tempLV);
530  }
531
532  // Emit the initializer.
533  llvm::Value *value = 0;
534
535  switch (lifetime) {
536  case Qualifiers::OCL_None:
537    llvm_unreachable("present but none");
538
539  case Qualifiers::OCL_ExplicitNone:
540    // nothing to do
541    value = EmitScalarExpr(init);
542    break;
543
544  case Qualifiers::OCL_Strong: {
545    value = EmitARCRetainScalarExpr(init);
546    break;
547  }
548
549  case Qualifiers::OCL_Weak: {
550    // No way to optimize a producing initializer into this.  It's not
551    // worth optimizing for, because the value will immediately
552    // disappear in the common case.
553    value = EmitScalarExpr(init);
554
555    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
556    if (accessedByInit)
557      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
558    else
559      EmitARCInitWeak(lvalue.getAddress(), value);
560    return;
561  }
562
563  case Qualifiers::OCL_Autoreleasing:
564    value = EmitARCRetainAutoreleaseScalarExpr(init);
565    break;
566  }
567
568  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
569
570  // If the variable might have been accessed by its initializer, we
571  // might have to initialize with a barrier.  We have to do this for
572  // both __weak and __strong, but __weak got filtered out above.
573  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
574    llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
575    EmitStoreOfScalar(value, lvalue);
576    EmitARCRelease(oldValue, /*precise*/ false);
577    return;
578  }
579
580  EmitStoreOfScalar(value, lvalue);
581}
582
583/// EmitScalarInit - Initialize the given lvalue with the given object.
584void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
585  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
586  if (!lifetime)
587    return EmitStoreThroughLValue(RValue::get(init), lvalue);
588
589  switch (lifetime) {
590  case Qualifiers::OCL_None:
591    llvm_unreachable("present but none");
592
593  case Qualifiers::OCL_ExplicitNone:
594    // nothing to do
595    break;
596
597  case Qualifiers::OCL_Strong:
598    init = EmitARCRetain(lvalue.getType(), init);
599    break;
600
601  case Qualifiers::OCL_Weak:
602    // Initialize and then skip the primitive store.
603    EmitARCInitWeak(lvalue.getAddress(), init);
604    return;
605
606  case Qualifiers::OCL_Autoreleasing:
607    init = EmitARCRetainAutorelease(lvalue.getType(), init);
608    break;
609  }
610
611  EmitStoreOfScalar(init, lvalue);
612}
613
614/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
615/// non-zero parts of the specified initializer with equal or fewer than
616/// NumStores scalar stores.
617static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
618                                                unsigned &NumStores) {
619  // Zero and Undef never requires any extra stores.
620  if (isa<llvm::ConstantAggregateZero>(Init) ||
621      isa<llvm::ConstantPointerNull>(Init) ||
622      isa<llvm::UndefValue>(Init))
623    return true;
624  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
625      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
626      isa<llvm::ConstantExpr>(Init))
627    return Init->isNullValue() || NumStores--;
628
629  // See if we can emit each element.
630  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
631    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
632      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
633      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
634        return false;
635    }
636    return true;
637  }
638
639  // Anything else is hard and scary.
640  return false;
641}
642
643/// emitStoresForInitAfterMemset - For inits that
644/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
645/// stores that would be required.
646static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
647                                         bool isVolatile, CGBuilderTy &Builder) {
648  // Zero doesn't require any stores.
649  if (isa<llvm::ConstantAggregateZero>(Init) ||
650      isa<llvm::ConstantPointerNull>(Init) ||
651      isa<llvm::UndefValue>(Init))
652    return;
653
654  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
655      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
656      isa<llvm::ConstantExpr>(Init)) {
657    if (!Init->isNullValue())
658      Builder.CreateStore(Init, Loc, isVolatile);
659    return;
660  }
661
662  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
663         "Unknown value type!");
664
665  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
666    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
667    if (Elt->isNullValue()) continue;
668
669    // Otherwise, get a pointer to the element and emit it.
670    emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
671                                 isVolatile, Builder);
672  }
673}
674
675
676/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
677/// plus some stores to initialize a local variable instead of using a memcpy
678/// from a constant global.  It is beneficial to use memset if the global is all
679/// zeros, or mostly zeros and large.
680static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
681                                                  uint64_t GlobalSize) {
682  // If a global is all zeros, always use a memset.
683  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
684
685
686  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
687  // do it if it will require 6 or fewer scalar stores.
688  // TODO: Should budget depends on the size?  Avoiding a large global warrants
689  // plopping in more stores.
690  unsigned StoreBudget = 6;
691  uint64_t SizeLimit = 32;
692
693  return GlobalSize > SizeLimit &&
694         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
695}
696
697
698/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
699/// variable declaration with auto, register, or no storage class specifier.
700/// These turn into simple stack objects, or GlobalValues depending on target.
701void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
702  AutoVarEmission emission = EmitAutoVarAlloca(D);
703  EmitAutoVarInit(emission);
704  EmitAutoVarCleanups(emission);
705}
706
707/// EmitAutoVarAlloca - Emit the alloca and debug information for a
708/// local variable.  Does not emit initalization or destruction.
709CodeGenFunction::AutoVarEmission
710CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
711  QualType Ty = D.getType();
712
713  AutoVarEmission emission(D);
714
715  bool isByRef = D.hasAttr<BlocksAttr>();
716  emission.IsByRef = isByRef;
717
718  CharUnits alignment = getContext().getDeclAlign(&D);
719  emission.Alignment = alignment;
720
721  // If the type is variably-modified, emit all the VLA sizes for it.
722  if (Ty->isVariablyModifiedType())
723    EmitVariablyModifiedType(Ty);
724
725  llvm::Value *DeclPtr;
726  if (Ty->isConstantSizeType()) {
727    if (!Target.useGlobalsForAutomaticVariables()) {
728      bool NRVO = getContext().getLangOptions().ElideConstructors &&
729                  D.isNRVOVariable();
730
731      // If this value is a POD array or struct with a statically
732      // determinable constant initializer, there are optimizations we
733      // can do.
734      // TODO: we can potentially constant-evaluate non-POD structs and
735      // arrays as long as the initialization is trivial (e.g. if they
736      // have a non-trivial destructor, but not a non-trivial constructor).
737      if (D.getInit() &&
738          (Ty->isArrayType() || Ty->isRecordType()) &&
739          (Ty.isPODType(getContext()) ||
740           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
741          D.getInit()->isConstantInitializer(getContext(), false)) {
742
743        // If the variable's a const type, and it's neither an NRVO
744        // candidate nor a __block variable, emit it as a global instead.
745        if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() &&
746            !NRVO && !isByRef) {
747          EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
748
749          emission.Address = 0; // signal this condition to later callbacks
750          assert(emission.wasEmittedAsGlobal());
751          return emission;
752        }
753
754        // Otherwise, tell the initialization code that we're in this case.
755        emission.IsConstantAggregate = true;
756      }
757
758      // A normal fixed sized variable becomes an alloca in the entry block,
759      // unless it's an NRVO variable.
760      llvm::Type *LTy = ConvertTypeForMem(Ty);
761
762      if (NRVO) {
763        // The named return value optimization: allocate this variable in the
764        // return slot, so that we can elide the copy when returning this
765        // variable (C++0x [class.copy]p34).
766        DeclPtr = ReturnValue;
767
768        if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
769          if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
770            // Create a flag that is used to indicate when the NRVO was applied
771            // to this variable. Set it to zero to indicate that NRVO was not
772            // applied.
773            llvm::Value *Zero = Builder.getFalse();
774            llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
775            EnsureInsertPoint();
776            Builder.CreateStore(Zero, NRVOFlag);
777
778            // Record the NRVO flag for this variable.
779            NRVOFlags[&D] = NRVOFlag;
780            emission.NRVOFlag = NRVOFlag;
781          }
782        }
783      } else {
784        if (isByRef)
785          LTy = BuildByRefType(&D);
786
787        llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
788        Alloc->setName(D.getNameAsString());
789
790        CharUnits allocaAlignment = alignment;
791        if (isByRef)
792          allocaAlignment = std::max(allocaAlignment,
793              getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
794        Alloc->setAlignment(allocaAlignment.getQuantity());
795        DeclPtr = Alloc;
796      }
797    } else {
798      // Targets that don't support recursion emit locals as globals.
799      const char *Class =
800        D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
801      DeclPtr = CreateStaticVarDecl(D, Class,
802                                    llvm::GlobalValue::InternalLinkage);
803    }
804  } else {
805    EnsureInsertPoint();
806
807    if (!DidCallStackSave) {
808      // Save the stack.
809      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
810
811      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
812      llvm::Value *V = Builder.CreateCall(F);
813
814      Builder.CreateStore(V, Stack);
815
816      DidCallStackSave = true;
817
818      // Push a cleanup block and restore the stack there.
819      // FIXME: in general circumstances, this should be an EH cleanup.
820      EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
821    }
822
823    llvm::Value *elementCount;
824    QualType elementType;
825    llvm::tie(elementCount, elementType) = getVLASize(Ty);
826
827    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
828
829    // Allocate memory for the array.
830    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
831    vla->setAlignment(alignment.getQuantity());
832
833    DeclPtr = vla;
834  }
835
836  llvm::Value *&DMEntry = LocalDeclMap[&D];
837  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
838  DMEntry = DeclPtr;
839  emission.Address = DeclPtr;
840
841  // Emit debug info for local var declaration.
842  if (HaveInsertPoint())
843    if (CGDebugInfo *DI = getDebugInfo()) {
844      DI->setLocation(D.getLocation());
845      if (Target.useGlobalsForAutomaticVariables()) {
846        DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
847      } else
848        DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
849    }
850
851  if (D.hasAttr<AnnotateAttr>())
852      EmitVarAnnotations(&D, emission.Address);
853
854  return emission;
855}
856
857/// Determines whether the given __block variable is potentially
858/// captured by the given expression.
859static bool isCapturedBy(const VarDecl &var, const Expr *e) {
860  // Skip the most common kinds of expressions that make
861  // hierarchy-walking expensive.
862  e = e->IgnoreParenCasts();
863
864  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
865    const BlockDecl *block = be->getBlockDecl();
866    for (BlockDecl::capture_const_iterator i = block->capture_begin(),
867           e = block->capture_end(); i != e; ++i) {
868      if (i->getVariable() == &var)
869        return true;
870    }
871
872    // No need to walk into the subexpressions.
873    return false;
874  }
875
876  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
877    const CompoundStmt *CS = SE->getSubStmt();
878    for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
879	   BE = CS->body_end(); BI != BE; ++BI)
880      if (Expr *E = dyn_cast<Expr>((*BI))) {
881        if (isCapturedBy(var, E))
882            return true;
883      }
884      else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) {
885          // special case declarations
886          for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
887               I != E; ++I) {
888              if (VarDecl *VD = dyn_cast<VarDecl>((*I))) {
889                Expr *Init = VD->getInit();
890                if (Init && isCapturedBy(var, Init))
891                  return true;
892              }
893          }
894      }
895      else
896        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
897        // Later, provide code to poke into statements for capture analysis.
898        return true;
899    return false;
900  }
901
902  for (Stmt::const_child_range children = e->children(); children; ++children)
903    if (isCapturedBy(var, cast<Expr>(*children)))
904      return true;
905
906  return false;
907}
908
909/// \brief Determine whether the given initializer is trivial in the sense
910/// that it requires no code to be generated.
911static bool isTrivialInitializer(const Expr *Init) {
912  if (!Init)
913    return true;
914
915  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
916    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
917      if (Constructor->isTrivial() &&
918          Constructor->isDefaultConstructor() &&
919          !Construct->requiresZeroInitialization())
920        return true;
921
922  return false;
923}
924void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
925  assert(emission.Variable && "emission was not valid!");
926
927  // If this was emitted as a global constant, we're done.
928  if (emission.wasEmittedAsGlobal()) return;
929
930  const VarDecl &D = *emission.Variable;
931  QualType type = D.getType();
932
933  // If this local has an initializer, emit it now.
934  const Expr *Init = D.getInit();
935
936  // If we are at an unreachable point, we don't need to emit the initializer
937  // unless it contains a label.
938  if (!HaveInsertPoint()) {
939    if (!Init || !ContainsLabel(Init)) return;
940    EnsureInsertPoint();
941  }
942
943  // Initialize the structure of a __block variable.
944  if (emission.IsByRef)
945    emitByrefStructureInit(emission);
946
947  if (isTrivialInitializer(Init))
948    return;
949
950  CharUnits alignment = emission.Alignment;
951
952  // Check whether this is a byref variable that's potentially
953  // captured and moved by its own initializer.  If so, we'll need to
954  // emit the initializer first, then copy into the variable.
955  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
956
957  llvm::Value *Loc =
958    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
959
960  if (!emission.IsConstantAggregate) {
961    LValue lv = MakeAddrLValue(Loc, type, alignment.getQuantity());
962    lv.setNonGC(true);
963    return EmitExprAsInit(Init, &D, lv, capturedByInit);
964  }
965
966  // If this is a simple aggregate initialization, we can optimize it
967  // in various ways.
968  assert(!capturedByInit && "constant init contains a capturing block?");
969
970  bool isVolatile = type.isVolatileQualified();
971
972  llvm::Constant *constant = CGM.EmitConstantExpr(D.getInit(), type, this);
973  assert(constant != 0 && "Wasn't a simple constant init?");
974
975  llvm::Value *SizeVal =
976    llvm::ConstantInt::get(IntPtrTy,
977                           getContext().getTypeSizeInChars(type).getQuantity());
978
979  llvm::Type *BP = Int8PtrTy;
980  if (Loc->getType() != BP)
981    Loc = Builder.CreateBitCast(Loc, BP, "tmp");
982
983  // If the initializer is all or mostly zeros, codegen with memset then do
984  // a few stores afterward.
985  if (shouldUseMemSetPlusStoresToInitialize(constant,
986                CGM.getTargetData().getTypeAllocSize(constant->getType()))) {
987    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
988                         alignment.getQuantity(), isVolatile);
989    if (!constant->isNullValue()) {
990      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
991      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
992    }
993  } else {
994    // Otherwise, create a temporary global with the initializer then
995    // memcpy from the global to the alloca.
996    std::string Name = GetStaticDeclName(*this, D, ".");
997    llvm::GlobalVariable *GV =
998      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
999                               llvm::GlobalValue::PrivateLinkage,
1000                               constant, Name, 0, false, 0);
1001    GV->setAlignment(alignment.getQuantity());
1002    GV->setUnnamedAddr(true);
1003
1004    llvm::Value *SrcPtr = GV;
1005    if (SrcPtr->getType() != BP)
1006      SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
1007
1008    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1009                         isVolatile);
1010  }
1011}
1012
1013/// Emit an expression as an initializer for a variable at the given
1014/// location.  The expression is not necessarily the normal
1015/// initializer for the variable, and the address is not necessarily
1016/// its normal location.
1017///
1018/// \param init the initializing expression
1019/// \param var the variable to act as if we're initializing
1020/// \param loc the address to initialize; its type is a pointer
1021///   to the LLVM mapping of the variable's type
1022/// \param alignment the alignment of the address
1023/// \param capturedByInit true if the variable is a __block variable
1024///   whose address is potentially changed by the initializer
1025void CodeGenFunction::EmitExprAsInit(const Expr *init,
1026                                     const ValueDecl *D,
1027                                     LValue lvalue,
1028                                     bool capturedByInit) {
1029  QualType type = D->getType();
1030
1031  if (type->isReferenceType()) {
1032    RValue rvalue = EmitReferenceBindingToExpr(init, D);
1033    if (capturedByInit)
1034      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1035    EmitStoreThroughLValue(rvalue, lvalue);
1036  } else if (!hasAggregateLLVMType(type)) {
1037    EmitScalarInit(init, D, lvalue, capturedByInit);
1038  } else if (type->isAnyComplexType()) {
1039    ComplexPairTy complex = EmitComplexExpr(init);
1040    if (capturedByInit)
1041      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1042    StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile());
1043  } else {
1044    // TODO: how can we delay here if D is captured by its initializer?
1045    EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1046                                              AggValueSlot::IsDestructed,
1047                                         AggValueSlot::DoesNotNeedGCBarriers,
1048                                              AggValueSlot::IsNotAliased));
1049  }
1050}
1051
1052/// Enter a destroy cleanup for the given local variable.
1053void CodeGenFunction::emitAutoVarTypeCleanup(
1054                            const CodeGenFunction::AutoVarEmission &emission,
1055                            QualType::DestructionKind dtorKind) {
1056  assert(dtorKind != QualType::DK_none);
1057
1058  // Note that for __block variables, we want to destroy the
1059  // original stack object, not the possibly forwarded object.
1060  llvm::Value *addr = emission.getObjectAddress(*this);
1061
1062  const VarDecl *var = emission.Variable;
1063  QualType type = var->getType();
1064
1065  CleanupKind cleanupKind = NormalAndEHCleanup;
1066  CodeGenFunction::Destroyer *destroyer = 0;
1067
1068  switch (dtorKind) {
1069  case QualType::DK_none:
1070    llvm_unreachable("no cleanup for trivially-destructible variable");
1071
1072  case QualType::DK_cxx_destructor:
1073    // If there's an NRVO flag on the emission, we need a different
1074    // cleanup.
1075    if (emission.NRVOFlag) {
1076      assert(!type->isArrayType());
1077      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1078      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1079                                               emission.NRVOFlag);
1080      return;
1081    }
1082    break;
1083
1084  case QualType::DK_objc_strong_lifetime:
1085    // Suppress cleanups for pseudo-strong variables.
1086    if (var->isARCPseudoStrong()) return;
1087
1088    // Otherwise, consider whether to use an EH cleanup or not.
1089    cleanupKind = getARCCleanupKind();
1090
1091    // Use the imprecise destroyer by default.
1092    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1093      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1094    break;
1095
1096  case QualType::DK_objc_weak_lifetime:
1097    break;
1098  }
1099
1100  // If we haven't chosen a more specific destroyer, use the default.
1101  if (!destroyer) destroyer = &getDestroyer(dtorKind);
1102
1103  // Use an EH cleanup in array destructors iff the destructor itself
1104  // is being pushed as an EH cleanup.
1105  bool useEHCleanup = (cleanupKind & EHCleanup);
1106  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1107                                     useEHCleanup);
1108}
1109
1110void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1111  assert(emission.Variable && "emission was not valid!");
1112
1113  // If this was emitted as a global constant, we're done.
1114  if (emission.wasEmittedAsGlobal()) return;
1115
1116  const VarDecl &D = *emission.Variable;
1117
1118  // Check the type for a cleanup.
1119  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1120    emitAutoVarTypeCleanup(emission, dtorKind);
1121
1122  // In GC mode, honor objc_precise_lifetime.
1123  if (getLangOptions().getGC() != LangOptions::NonGC &&
1124      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1125    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1126  }
1127
1128  // Handle the cleanup attribute.
1129  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1130    const FunctionDecl *FD = CA->getFunctionDecl();
1131
1132    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1133    assert(F && "Could not find function!");
1134
1135    const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
1136    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1137  }
1138
1139  // If this is a block variable, call _Block_object_destroy
1140  // (on the unforwarded address).
1141  if (emission.IsByRef)
1142    enterByrefCleanup(emission);
1143}
1144
1145CodeGenFunction::Destroyer &
1146CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1147  // This is surprisingly compiler-dependent.  GCC 4.2 can't bind
1148  // references to functions directly in returns, and using '*&foo'
1149  // confuses MSVC.  Luckily, the following code pattern works in both.
1150  Destroyer *destroyer = 0;
1151  switch (kind) {
1152  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1153  case QualType::DK_cxx_destructor:
1154    destroyer = &destroyCXXObject;
1155    break;
1156  case QualType::DK_objc_strong_lifetime:
1157    destroyer = &destroyARCStrongPrecise;
1158    break;
1159  case QualType::DK_objc_weak_lifetime:
1160    destroyer = &destroyARCWeak;
1161    break;
1162  }
1163  return *destroyer;
1164}
1165
1166/// pushDestroy - Push the standard destructor for the given type.
1167void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1168                                  llvm::Value *addr, QualType type) {
1169  assert(dtorKind && "cannot push destructor for trivial type");
1170
1171  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1172  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1173              cleanupKind & EHCleanup);
1174}
1175
1176void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1177                                  QualType type, Destroyer &destroyer,
1178                                  bool useEHCleanupForArray) {
1179  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1180                                     destroyer, useEHCleanupForArray);
1181}
1182
1183/// emitDestroy - Immediately perform the destruction of the given
1184/// object.
1185///
1186/// \param addr - the address of the object; a type*
1187/// \param type - the type of the object; if an array type, all
1188///   objects are destroyed in reverse order
1189/// \param destroyer - the function to call to destroy individual
1190///   elements
1191/// \param useEHCleanupForArray - whether an EH cleanup should be
1192///   used when destroying array elements, in case one of the
1193///   destructions throws an exception
1194void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1195                                  Destroyer &destroyer,
1196                                  bool useEHCleanupForArray) {
1197  const ArrayType *arrayType = getContext().getAsArrayType(type);
1198  if (!arrayType)
1199    return destroyer(*this, addr, type);
1200
1201  llvm::Value *begin = addr;
1202  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1203
1204  // Normally we have to check whether the array is zero-length.
1205  bool checkZeroLength = true;
1206
1207  // But if the array length is constant, we can suppress that.
1208  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1209    // ...and if it's constant zero, we can just skip the entire thing.
1210    if (constLength->isZero()) return;
1211    checkZeroLength = false;
1212  }
1213
1214  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1215  emitArrayDestroy(begin, end, type, destroyer,
1216                   checkZeroLength, useEHCleanupForArray);
1217}
1218
1219/// emitArrayDestroy - Destroys all the elements of the given array,
1220/// beginning from last to first.  The array cannot be zero-length.
1221///
1222/// \param begin - a type* denoting the first element of the array
1223/// \param end - a type* denoting one past the end of the array
1224/// \param type - the element type of the array
1225/// \param destroyer - the function to call to destroy elements
1226/// \param useEHCleanup - whether to push an EH cleanup to destroy
1227///   the remaining elements in case the destruction of a single
1228///   element throws
1229void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1230                                       llvm::Value *end,
1231                                       QualType type,
1232                                       Destroyer &destroyer,
1233                                       bool checkZeroLength,
1234                                       bool useEHCleanup) {
1235  assert(!type->isArrayType());
1236
1237  // The basic structure here is a do-while loop, because we don't
1238  // need to check for the zero-element case.
1239  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1240  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1241
1242  if (checkZeroLength) {
1243    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1244                                                "arraydestroy.isempty");
1245    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1246  }
1247
1248  // Enter the loop body, making that address the current address.
1249  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1250  EmitBlock(bodyBB);
1251  llvm::PHINode *elementPast =
1252    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1253  elementPast->addIncoming(end, entryBB);
1254
1255  // Shift the address back by one element.
1256  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1257  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1258                                                   "arraydestroy.element");
1259
1260  if (useEHCleanup)
1261    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1262
1263  // Perform the actual destruction there.
1264  destroyer(*this, element, type);
1265
1266  if (useEHCleanup)
1267    PopCleanupBlock();
1268
1269  // Check whether we've reached the end.
1270  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1271  Builder.CreateCondBr(done, doneBB, bodyBB);
1272  elementPast->addIncoming(element, Builder.GetInsertBlock());
1273
1274  // Done.
1275  EmitBlock(doneBB);
1276}
1277
1278/// Perform partial array destruction as if in an EH cleanup.  Unlike
1279/// emitArrayDestroy, the element type here may still be an array type.
1280static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1281                                    llvm::Value *begin, llvm::Value *end,
1282                                    QualType type,
1283                                    CodeGenFunction::Destroyer &destroyer) {
1284  // If the element type is itself an array, drill down.
1285  unsigned arrayDepth = 0;
1286  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1287    // VLAs don't require a GEP index to walk into.
1288    if (!isa<VariableArrayType>(arrayType))
1289      arrayDepth++;
1290    type = arrayType->getElementType();
1291  }
1292
1293  if (arrayDepth) {
1294    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1295
1296    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1297    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1298    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1299  }
1300
1301  // Destroy the array.  We don't ever need an EH cleanup because we
1302  // assume that we're in an EH cleanup ourselves, so a throwing
1303  // destructor causes an immediate terminate.
1304  CGF.emitArrayDestroy(begin, end, type, destroyer,
1305                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1306}
1307
1308namespace {
1309  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1310  /// array destroy where the end pointer is regularly determined and
1311  /// does not need to be loaded from a local.
1312  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1313    llvm::Value *ArrayBegin;
1314    llvm::Value *ArrayEnd;
1315    QualType ElementType;
1316    CodeGenFunction::Destroyer &Destroyer;
1317  public:
1318    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1319                               QualType elementType,
1320                               CodeGenFunction::Destroyer *destroyer)
1321      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1322        ElementType(elementType), Destroyer(*destroyer) {}
1323
1324    void Emit(CodeGenFunction &CGF, Flags flags) {
1325      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1326                              ElementType, Destroyer);
1327    }
1328  };
1329
1330  /// IrregularPartialArrayDestroy - a cleanup which performs a
1331  /// partial array destroy where the end pointer is irregularly
1332  /// determined and must be loaded from a local.
1333  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1334    llvm::Value *ArrayBegin;
1335    llvm::Value *ArrayEndPointer;
1336    QualType ElementType;
1337    CodeGenFunction::Destroyer &Destroyer;
1338  public:
1339    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1340                                 llvm::Value *arrayEndPointer,
1341                                 QualType elementType,
1342                                 CodeGenFunction::Destroyer *destroyer)
1343      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1344        ElementType(elementType), Destroyer(*destroyer) {}
1345
1346    void Emit(CodeGenFunction &CGF, Flags flags) {
1347      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1348      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1349                              ElementType, Destroyer);
1350    }
1351  };
1352}
1353
1354/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1355/// already-constructed elements of the given array.  The cleanup
1356/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1357///
1358/// \param elementType - the immediate element type of the array;
1359///   possibly still an array type
1360/// \param array - a value of type elementType*
1361/// \param destructionKind - the kind of destruction required
1362/// \param initializedElementCount - a value of type size_t* holding
1363///   the number of successfully-constructed elements
1364void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1365                                                 llvm::Value *arrayEndPointer,
1366                                                       QualType elementType,
1367                                                       Destroyer &destroyer) {
1368  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1369                                                    arrayBegin, arrayEndPointer,
1370                                                    elementType, &destroyer);
1371}
1372
1373/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1374/// already-constructed elements of the given array.  The cleanup
1375/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1376///
1377/// \param elementType - the immediate element type of the array;
1378///   possibly still an array type
1379/// \param array - a value of type elementType*
1380/// \param destructionKind - the kind of destruction required
1381/// \param initializedElementCount - a value of type size_t* holding
1382///   the number of successfully-constructed elements
1383void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1384                                                     llvm::Value *arrayEnd,
1385                                                     QualType elementType,
1386                                                     Destroyer &destroyer) {
1387  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1388                                                  arrayBegin, arrayEnd,
1389                                                  elementType, &destroyer);
1390}
1391
1392namespace {
1393  /// A cleanup to perform a release of an object at the end of a
1394  /// function.  This is used to balance out the incoming +1 of a
1395  /// ns_consumed argument when we can't reasonably do that just by
1396  /// not doing the initial retain for a __block argument.
1397  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1398    ConsumeARCParameter(llvm::Value *param) : Param(param) {}
1399
1400    llvm::Value *Param;
1401
1402    void Emit(CodeGenFunction &CGF, Flags flags) {
1403      CGF.EmitARCRelease(Param, /*precise*/ false);
1404    }
1405  };
1406}
1407
1408/// Emit an alloca (or GlobalValue depending on target)
1409/// for the specified parameter and set up LocalDeclMap.
1410void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1411                                   unsigned ArgNo) {
1412  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1413  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1414         "Invalid argument to EmitParmDecl");
1415
1416  Arg->setName(D.getName());
1417
1418  // Use better IR generation for certain implicit parameters.
1419  if (isa<ImplicitParamDecl>(D)) {
1420    // The only implicit argument a block has is its literal.
1421    if (BlockInfo) {
1422      LocalDeclMap[&D] = Arg;
1423
1424      if (CGDebugInfo *DI = getDebugInfo()) {
1425        DI->setLocation(D.getLocation());
1426        DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
1427      }
1428
1429      return;
1430    }
1431  }
1432
1433  QualType Ty = D.getType();
1434
1435  llvm::Value *DeclPtr;
1436  // If this is an aggregate or variable sized value, reuse the input pointer.
1437  if (!Ty->isConstantSizeType() ||
1438      CodeGenFunction::hasAggregateLLVMType(Ty)) {
1439    DeclPtr = Arg;
1440  } else {
1441    // Otherwise, create a temporary to hold the value.
1442    DeclPtr = CreateMemTemp(Ty, D.getName() + ".addr");
1443
1444    bool doStore = true;
1445
1446    Qualifiers qs = Ty.getQualifiers();
1447
1448    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1449      // We honor __attribute__((ns_consumed)) for types with lifetime.
1450      // For __strong, it's handled by just skipping the initial retain;
1451      // otherwise we have to balance out the initial +1 with an extra
1452      // cleanup to do the release at the end of the function.
1453      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1454
1455      // 'self' is always formally __strong, but if this is not an
1456      // init method then we don't want to retain it.
1457      if (D.isARCPseudoStrong()) {
1458        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1459        assert(&D == method->getSelfDecl());
1460        assert(lt == Qualifiers::OCL_Strong);
1461        assert(qs.hasConst());
1462        assert(method->getMethodFamily() != OMF_init);
1463        (void) method;
1464        lt = Qualifiers::OCL_ExplicitNone;
1465      }
1466
1467      if (lt == Qualifiers::OCL_Strong) {
1468        if (!isConsumed)
1469          // Don't use objc_retainBlock for block pointers, because we
1470          // don't want to Block_copy something just because we got it
1471          // as a parameter.
1472          Arg = EmitARCRetainNonBlock(Arg);
1473      } else {
1474        // Push the cleanup for a consumed parameter.
1475        if (isConsumed)
1476          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg);
1477
1478        if (lt == Qualifiers::OCL_Weak) {
1479          EmitARCInitWeak(DeclPtr, Arg);
1480          doStore = false; // The weak init is a store, no need to do two
1481        }
1482      }
1483
1484      // Enter the cleanup scope.
1485      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1486    }
1487
1488    // Store the initial value into the alloca.
1489    if (doStore) {
1490      LValue lv = MakeAddrLValue(DeclPtr, Ty,
1491                                 getContext().getDeclAlign(&D).getQuantity());
1492      EmitStoreOfScalar(Arg, lv);
1493    }
1494  }
1495
1496  llvm::Value *&DMEntry = LocalDeclMap[&D];
1497  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
1498  DMEntry = DeclPtr;
1499
1500  // Emit debug info for param declaration.
1501  if (CGDebugInfo *DI = getDebugInfo())
1502    DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1503
1504  if (D.hasAttr<AnnotateAttr>())
1505      EmitVarAnnotations(&D, DeclPtr);
1506}
1507