CGDecl.cpp revision af0f4d0b2e38c810effc8b024ad2fb6604eec5d3 
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  // FIXME: Merge attribute handling.
275  if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) {
276    SourceManager &SM = CGM.getContext().getSourceManager();
277    llvm::Constant *Ann =
278      CGM.EmitAnnotateAttr(GV, AA, SM.getExpansionLineNumber(D.getLocation()));
279    CGM.AddAnnotation(Ann);
280  }
281
282  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
283    GV->setSection(SA->getName());
284
285  if (D.hasAttr<UsedAttr>())
286    CGM.AddUsedGlobal(GV);
287
288  // We may have to cast the constant because of the initializer
289  // mismatch above.
290  //
291  // FIXME: It is really dangerous to store this in the map; if anyone
292  // RAUW's the GV uses of this constant will be invalid.
293  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
294  llvm::Type *LPtrTy =
295    LTy->getPointerTo(CGM.getContext().getTargetAddressSpace(D.getType()));
296  DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
297
298  // Emit global variable debug descriptor for static vars.
299  CGDebugInfo *DI = getDebugInfo();
300  if (DI) {
301    DI->setLocation(D.getLocation());
302    DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
303  }
304}
305
306namespace {
307  struct DestroyObject : EHScopeStack::Cleanup {
308    DestroyObject(llvm::Value *addr, QualType type,
309                  CodeGenFunction::Destroyer *destroyer,
310                  bool useEHCleanupForArray)
311      : addr(addr), type(type), destroyer(*destroyer),
312        useEHCleanupForArray(useEHCleanupForArray) {}
313
314    llvm::Value *addr;
315    QualType type;
316    CodeGenFunction::Destroyer &destroyer;
317    bool useEHCleanupForArray;
318
319    void Emit(CodeGenFunction &CGF, Flags flags) {
320      // Don't use an EH cleanup recursively from an EH cleanup.
321      bool useEHCleanupForArray =
322        flags.isForNormalCleanup() && this->useEHCleanupForArray;
323
324      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
325    }
326  };
327
328  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
329    DestroyNRVOVariable(llvm::Value *addr,
330                        const CXXDestructorDecl *Dtor,
331                        llvm::Value *NRVOFlag)
332      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
333
334    const CXXDestructorDecl *Dtor;
335    llvm::Value *NRVOFlag;
336    llvm::Value *Loc;
337
338    void Emit(CodeGenFunction &CGF, Flags flags) {
339      // Along the exceptions path we always execute the dtor.
340      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
341
342      llvm::BasicBlock *SkipDtorBB = 0;
343      if (NRVO) {
344        // If we exited via NRVO, we skip the destructor call.
345        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
346        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
347        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
348        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
349        CGF.EmitBlock(RunDtorBB);
350      }
351
352      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
353                                /*ForVirtualBase=*/false, Loc);
354
355      if (NRVO) CGF.EmitBlock(SkipDtorBB);
356    }
357  };
358
359  struct CallStackRestore : EHScopeStack::Cleanup {
360    llvm::Value *Stack;
361    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
362    void Emit(CodeGenFunction &CGF, Flags flags) {
363      llvm::Value *V = CGF.Builder.CreateLoad(Stack, "tmp");
364      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
365      CGF.Builder.CreateCall(F, V);
366    }
367  };
368
369  struct ExtendGCLifetime : EHScopeStack::Cleanup {
370    const VarDecl &Var;
371    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
372
373    void Emit(CodeGenFunction &CGF, Flags flags) {
374      // Compute the address of the local variable, in case it's a
375      // byref or something.
376      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
377                      SourceLocation());
378      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE));
379      CGF.EmitExtendGCLifetime(value);
380    }
381  };
382
383  struct CallCleanupFunction : EHScopeStack::Cleanup {
384    llvm::Constant *CleanupFn;
385    const CGFunctionInfo &FnInfo;
386    const VarDecl &Var;
387
388    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
389                        const VarDecl *Var)
390      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
391
392    void Emit(CodeGenFunction &CGF, Flags flags) {
393      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
394                      SourceLocation());
395      // Compute the address of the local variable, in case it's a byref
396      // or something.
397      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
398
399      // In some cases, the type of the function argument will be different from
400      // the type of the pointer. An example of this is
401      // void f(void* arg);
402      // __attribute__((cleanup(f))) void *g;
403      //
404      // To fix this we insert a bitcast here.
405      QualType ArgTy = FnInfo.arg_begin()->type;
406      llvm::Value *Arg =
407        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
408
409      CallArgList Args;
410      Args.add(RValue::get(Arg),
411               CGF.getContext().getPointerType(Var.getType()));
412      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
413    }
414  };
415}
416
417/// EmitAutoVarWithLifetime - Does the setup required for an automatic
418/// variable with lifetime.
419static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
420                                    llvm::Value *addr,
421                                    Qualifiers::ObjCLifetime lifetime) {
422  switch (lifetime) {
423  case Qualifiers::OCL_None:
424    llvm_unreachable("present but none");
425
426  case Qualifiers::OCL_ExplicitNone:
427    // nothing to do
428    break;
429
430  case Qualifiers::OCL_Strong: {
431    CodeGenFunction::Destroyer &destroyer =
432      (var.hasAttr<ObjCPreciseLifetimeAttr>()
433       ? CodeGenFunction::destroyARCStrongPrecise
434       : CodeGenFunction::destroyARCStrongImprecise);
435
436    CleanupKind cleanupKind = CGF.getARCCleanupKind();
437    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
438                    cleanupKind & EHCleanup);
439    break;
440  }
441  case Qualifiers::OCL_Autoreleasing:
442    // nothing to do
443    break;
444
445  case Qualifiers::OCL_Weak:
446    // __weak objects always get EH cleanups; otherwise, exceptions
447    // could cause really nasty crashes instead of mere leaks.
448    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
449                    CodeGenFunction::destroyARCWeak,
450                    /*useEHCleanup*/ true);
451    break;
452  }
453}
454
455static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
456  if (const Expr *e = dyn_cast<Expr>(s)) {
457    // Skip the most common kinds of expressions that make
458    // hierarchy-walking expensive.
459    s = e = e->IgnoreParenCasts();
460
461    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
462      return (ref->getDecl() == &var);
463  }
464
465  for (Stmt::const_child_range children = s->children(); children; ++children)
466    // children might be null; as in missing decl or conditional of an if-stmt.
467    if ((*children) && isAccessedBy(var, *children))
468      return true;
469
470  return false;
471}
472
473static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
474  if (!decl) return false;
475  if (!isa<VarDecl>(decl)) return false;
476  const VarDecl *var = cast<VarDecl>(decl);
477  return isAccessedBy(*var, e);
478}
479
480static void drillIntoBlockVariable(CodeGenFunction &CGF,
481                                   LValue &lvalue,
482                                   const VarDecl *var) {
483  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
484}
485
486void CodeGenFunction::EmitScalarInit(const Expr *init,
487                                     const ValueDecl *D,
488                                     LValue lvalue,
489                                     bool capturedByInit) {
490  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
491  if (!lifetime) {
492    llvm::Value *value = EmitScalarExpr(init);
493    if (capturedByInit)
494      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
495    EmitStoreThroughLValue(RValue::get(value), lvalue);
496    return;
497  }
498
499  // If we're emitting a value with lifetime, we have to do the
500  // initialization *before* we leave the cleanup scopes.
501  CodeGenFunction::RunCleanupsScope Scope(*this);
502  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init))
503    init = ewc->getSubExpr();
504
505  // We have to maintain the illusion that the variable is
506  // zero-initialized.  If the variable might be accessed in its
507  // initializer, zero-initialize before running the initializer, then
508  // actually perform the initialization with an assign.
509  bool accessedByInit = false;
510  if (lifetime != Qualifiers::OCL_ExplicitNone)
511    accessedByInit = (capturedByInit || isAccessedBy(D, init));
512  if (accessedByInit) {
513    LValue tempLV = lvalue;
514    // Drill down to the __block object if necessary.
515    if (capturedByInit) {
516      // We can use a simple GEP for this because it can't have been
517      // moved yet.
518      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
519                                   getByRefValueLLVMField(cast<VarDecl>(D))));
520    }
521
522    llvm::PointerType *ty
523      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
524    ty = cast<llvm::PointerType>(ty->getElementType());
525
526    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
527
528    // If __weak, we want to use a barrier under certain conditions.
529    if (lifetime == Qualifiers::OCL_Weak)
530      EmitARCInitWeak(tempLV.getAddress(), zero);
531
532    // Otherwise just do a simple store.
533    else
534      EmitStoreOfScalar(zero, tempLV);
535  }
536
537  // Emit the initializer.
538  llvm::Value *value = 0;
539
540  switch (lifetime) {
541  case Qualifiers::OCL_None:
542    llvm_unreachable("present but none");
543
544  case Qualifiers::OCL_ExplicitNone:
545    // nothing to do
546    value = EmitScalarExpr(init);
547    break;
548
549  case Qualifiers::OCL_Strong: {
550    value = EmitARCRetainScalarExpr(init);
551    break;
552  }
553
554  case Qualifiers::OCL_Weak: {
555    // No way to optimize a producing initializer into this.  It's not
556    // worth optimizing for, because the value will immediately
557    // disappear in the common case.
558    value = EmitScalarExpr(init);
559
560    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
561    if (accessedByInit)
562      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
563    else
564      EmitARCInitWeak(lvalue.getAddress(), value);
565    return;
566  }
567
568  case Qualifiers::OCL_Autoreleasing:
569    value = EmitARCRetainAutoreleaseScalarExpr(init);
570    break;
571  }
572
573  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
574
575  // If the variable might have been accessed by its initializer, we
576  // might have to initialize with a barrier.  We have to do this for
577  // both __weak and __strong, but __weak got filtered out above.
578  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
579    llvm::Value *oldValue = EmitLoadOfScalar(lvalue);
580    EmitStoreOfScalar(value, lvalue);
581    EmitARCRelease(oldValue, /*precise*/ false);
582    return;
583  }
584
585  EmitStoreOfScalar(value, lvalue);
586}
587
588/// EmitScalarInit - Initialize the given lvalue with the given object.
589void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
590  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
591  if (!lifetime)
592    return EmitStoreThroughLValue(RValue::get(init), lvalue);
593
594  switch (lifetime) {
595  case Qualifiers::OCL_None:
596    llvm_unreachable("present but none");
597
598  case Qualifiers::OCL_ExplicitNone:
599    // nothing to do
600    break;
601
602  case Qualifiers::OCL_Strong:
603    init = EmitARCRetain(lvalue.getType(), init);
604    break;
605
606  case Qualifiers::OCL_Weak:
607    // Initialize and then skip the primitive store.
608    EmitARCInitWeak(lvalue.getAddress(), init);
609    return;
610
611  case Qualifiers::OCL_Autoreleasing:
612    init = EmitARCRetainAutorelease(lvalue.getType(), init);
613    break;
614  }
615
616  EmitStoreOfScalar(init, lvalue);
617}
618
619/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
620/// non-zero parts of the specified initializer with equal or fewer than
621/// NumStores scalar stores.
622static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
623                                                unsigned &NumStores) {
624  // Zero and Undef never requires any extra stores.
625  if (isa<llvm::ConstantAggregateZero>(Init) ||
626      isa<llvm::ConstantPointerNull>(Init) ||
627      isa<llvm::UndefValue>(Init))
628    return true;
629  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
630      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
631      isa<llvm::ConstantExpr>(Init))
632    return Init->isNullValue() || NumStores--;
633
634  // See if we can emit each element.
635  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
636    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
637      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
638      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
639        return false;
640    }
641    return true;
642  }
643
644  // Anything else is hard and scary.
645  return false;
646}
647
648/// emitStoresForInitAfterMemset - For inits that
649/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
650/// stores that would be required.
651static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
652                                         bool isVolatile, CGBuilderTy &Builder) {
653  // Zero doesn't require any stores.
654  if (isa<llvm::ConstantAggregateZero>(Init) ||
655      isa<llvm::ConstantPointerNull>(Init) ||
656      isa<llvm::UndefValue>(Init))
657    return;
658
659  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
660      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
661      isa<llvm::ConstantExpr>(Init)) {
662    if (!Init->isNullValue())
663      Builder.CreateStore(Init, Loc, isVolatile);
664    return;
665  }
666
667  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
668         "Unknown value type!");
669
670  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
671    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
672    if (Elt->isNullValue()) continue;
673
674    // Otherwise, get a pointer to the element and emit it.
675    emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
676                                 isVolatile, Builder);
677  }
678}
679
680
681/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
682/// plus some stores to initialize a local variable instead of using a memcpy
683/// from a constant global.  It is beneficial to use memset if the global is all
684/// zeros, or mostly zeros and large.
685static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
686                                                  uint64_t GlobalSize) {
687  // If a global is all zeros, always use a memset.
688  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
689
690
691  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
692  // do it if it will require 6 or fewer scalar stores.
693  // TODO: Should budget depends on the size?  Avoiding a large global warrants
694  // plopping in more stores.
695  unsigned StoreBudget = 6;
696  uint64_t SizeLimit = 32;
697
698  return GlobalSize > SizeLimit &&
699         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
700}
701
702
703/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
704/// variable declaration with auto, register, or no storage class specifier.
705/// These turn into simple stack objects, or GlobalValues depending on target.
706void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
707  AutoVarEmission emission = EmitAutoVarAlloca(D);
708  EmitAutoVarInit(emission);
709  EmitAutoVarCleanups(emission);
710}
711
712/// EmitAutoVarAlloca - Emit the alloca and debug information for a
713/// local variable.  Does not emit initalization or destruction.
714CodeGenFunction::AutoVarEmission
715CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
716  QualType Ty = D.getType();
717
718  AutoVarEmission emission(D);
719
720  bool isByRef = D.hasAttr<BlocksAttr>();
721  emission.IsByRef = isByRef;
722
723  CharUnits alignment = getContext().getDeclAlign(&D);
724  emission.Alignment = alignment;
725
726  // If the type is variably-modified, emit all the VLA sizes for it.
727  if (Ty->isVariablyModifiedType())
728    EmitVariablyModifiedType(Ty);
729
730  llvm::Value *DeclPtr;
731  if (Ty->isConstantSizeType()) {
732    if (!Target.useGlobalsForAutomaticVariables()) {
733      bool NRVO = getContext().getLangOptions().ElideConstructors &&
734                  D.isNRVOVariable();
735
736      // If this value is a POD array or struct with a statically
737      // determinable constant initializer, there are optimizations we
738      // can do.
739      // TODO: we can potentially constant-evaluate non-POD structs and
740      // arrays as long as the initialization is trivial (e.g. if they
741      // have a non-trivial destructor, but not a non-trivial constructor).
742      if (D.getInit() &&
743          (Ty->isArrayType() || Ty->isRecordType()) &&
744          (Ty.isPODType(getContext()) ||
745           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
746          D.getInit()->isConstantInitializer(getContext(), false)) {
747
748        // If the variable's a const type, and it's neither an NRVO
749        // candidate nor a __block variable, emit it as a global instead.
750        if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() &&
751            !NRVO && !isByRef) {
752          EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
753
754          emission.Address = 0; // signal this condition to later callbacks
755          assert(emission.wasEmittedAsGlobal());
756          return emission;
757        }
758
759        // Otherwise, tell the initialization code that we're in this case.
760        emission.IsConstantAggregate = true;
761      }
762
763      // A normal fixed sized variable becomes an alloca in the entry block,
764      // unless it's an NRVO variable.
765      llvm::Type *LTy = ConvertTypeForMem(Ty);
766
767      if (NRVO) {
768        // The named return value optimization: allocate this variable in the
769        // return slot, so that we can elide the copy when returning this
770        // variable (C++0x [class.copy]p34).
771        DeclPtr = ReturnValue;
772
773        if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
774          if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
775            // Create a flag that is used to indicate when the NRVO was applied
776            // to this variable. Set it to zero to indicate that NRVO was not
777            // applied.
778            llvm::Value *Zero = Builder.getFalse();
779            llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
780            EnsureInsertPoint();
781            Builder.CreateStore(Zero, NRVOFlag);
782
783            // Record the NRVO flag for this variable.
784            NRVOFlags[&D] = NRVOFlag;
785            emission.NRVOFlag = NRVOFlag;
786          }
787        }
788      } else {
789        if (isByRef)
790          LTy = BuildByRefType(&D);
791
792        llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
793        Alloc->setName(D.getNameAsString());
794
795        CharUnits allocaAlignment = alignment;
796        if (isByRef)
797          allocaAlignment = std::max(allocaAlignment,
798              getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
799        Alloc->setAlignment(allocaAlignment.getQuantity());
800        DeclPtr = Alloc;
801      }
802    } else {
803      // Targets that don't support recursion emit locals as globals.
804      const char *Class =
805        D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
806      DeclPtr = CreateStaticVarDecl(D, Class,
807                                    llvm::GlobalValue::InternalLinkage);
808    }
809  } else {
810    EnsureInsertPoint();
811
812    if (!DidCallStackSave) {
813      // Save the stack.
814      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
815
816      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
817      llvm::Value *V = Builder.CreateCall(F);
818
819      Builder.CreateStore(V, Stack);
820
821      DidCallStackSave = true;
822
823      // Push a cleanup block and restore the stack there.
824      // FIXME: in general circumstances, this should be an EH cleanup.
825      EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
826    }
827
828    llvm::Value *elementCount;
829    QualType elementType;
830    llvm::tie(elementCount, elementType) = getVLASize(Ty);
831
832    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
833
834    // Allocate memory for the array.
835    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
836    vla->setAlignment(alignment.getQuantity());
837
838    DeclPtr = vla;
839  }
840
841  llvm::Value *&DMEntry = LocalDeclMap[&D];
842  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
843  DMEntry = DeclPtr;
844  emission.Address = DeclPtr;
845
846  // Emit debug info for local var declaration.
847  if (HaveInsertPoint())
848    if (CGDebugInfo *DI = getDebugInfo()) {
849      DI->setLocation(D.getLocation());
850      if (Target.useGlobalsForAutomaticVariables()) {
851        DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
852      } else
853        DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
854    }
855
856  return emission;
857}
858
859/// Determines whether the given __block variable is potentially
860/// captured by the given expression.
861static bool isCapturedBy(const VarDecl &var, const Expr *e) {
862  // Skip the most common kinds of expressions that make
863  // hierarchy-walking expensive.
864  e = e->IgnoreParenCasts();
865
866  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
867    const BlockDecl *block = be->getBlockDecl();
868    for (BlockDecl::capture_const_iterator i = block->capture_begin(),
869           e = block->capture_end(); i != e; ++i) {
870      if (i->getVariable() == &var)
871        return true;
872    }
873
874    // No need to walk into the subexpressions.
875    return false;
876  }
877
878  for (Stmt::const_child_range children = e->children(); children; ++children)
879    if (isCapturedBy(var, cast<Expr>(*children)))
880      return true;
881
882  return false;
883}
884
885/// \brief Determine whether the given initializer is trivial in the sense
886/// that it requires no code to be generated.
887static bool isTrivialInitializer(const Expr *Init) {
888  if (!Init)
889    return true;
890
891  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
892    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
893      if (Constructor->isTrivial() &&
894          Constructor->isDefaultConstructor() &&
895          !Construct->requiresZeroInitialization())
896        return true;
897
898  return false;
899}
900void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
901  assert(emission.Variable && "emission was not valid!");
902
903  // If this was emitted as a global constant, we're done.
904  if (emission.wasEmittedAsGlobal()) return;
905
906  const VarDecl &D = *emission.Variable;
907  QualType type = D.getType();
908
909  // If this local has an initializer, emit it now.
910  const Expr *Init = D.getInit();
911
912  // If we are at an unreachable point, we don't need to emit the initializer
913  // unless it contains a label.
914  if (!HaveInsertPoint()) {
915    if (!Init || !ContainsLabel(Init)) return;
916    EnsureInsertPoint();
917  }
918
919  // Initialize the structure of a __block variable.
920  if (emission.IsByRef)
921    emitByrefStructureInit(emission);
922
923  if (isTrivialInitializer(Init))
924    return;
925
926
927  CharUnits alignment = emission.Alignment;
928
929  // Check whether this is a byref variable that's potentially
930  // captured and moved by its own initializer.  If so, we'll need to
931  // emit the initializer first, then copy into the variable.
932  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
933
934  llvm::Value *Loc =
935    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
936
937  if (!emission.IsConstantAggregate) {
938    LValue lv = MakeAddrLValue(Loc, type, alignment.getQuantity());
939    lv.setNonGC(true);
940    return EmitExprAsInit(Init, &D, lv, capturedByInit);
941  }
942
943  // If this is a simple aggregate initialization, we can optimize it
944  // in various ways.
945  assert(!capturedByInit && "constant init contains a capturing block?");
946
947  bool isVolatile = type.isVolatileQualified();
948
949  llvm::Constant *constant = CGM.EmitConstantExpr(D.getInit(), type, this);
950  assert(constant != 0 && "Wasn't a simple constant init?");
951
952  llvm::Value *SizeVal =
953    llvm::ConstantInt::get(IntPtrTy,
954                           getContext().getTypeSizeInChars(type).getQuantity());
955
956  llvm::Type *BP = Int8PtrTy;
957  if (Loc->getType() != BP)
958    Loc = Builder.CreateBitCast(Loc, BP, "tmp");
959
960  // If the initializer is all or mostly zeros, codegen with memset then do
961  // a few stores afterward.
962  if (shouldUseMemSetPlusStoresToInitialize(constant,
963                CGM.getTargetData().getTypeAllocSize(constant->getType()))) {
964    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
965                         alignment.getQuantity(), isVolatile);
966    if (!constant->isNullValue()) {
967      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
968      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
969    }
970  } else {
971    // Otherwise, create a temporary global with the initializer then
972    // memcpy from the global to the alloca.
973    std::string Name = GetStaticDeclName(*this, D, ".");
974    llvm::GlobalVariable *GV =
975      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
976                               llvm::GlobalValue::InternalLinkage,
977                               constant, Name, 0, false, 0);
978    GV->setAlignment(alignment.getQuantity());
979    GV->setUnnamedAddr(true);
980
981    llvm::Value *SrcPtr = GV;
982    if (SrcPtr->getType() != BP)
983      SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
984
985    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
986                         isVolatile);
987  }
988}
989
990/// Emit an expression as an initializer for a variable at the given
991/// location.  The expression is not necessarily the normal
992/// initializer for the variable, and the address is not necessarily
993/// its normal location.
994///
995/// \param init the initializing expression
996/// \param var the variable to act as if we're initializing
997/// \param loc the address to initialize; its type is a pointer
998///   to the LLVM mapping of the variable's type
999/// \param alignment the alignment of the address
1000/// \param capturedByInit true if the variable is a __block variable
1001///   whose address is potentially changed by the initializer
1002void CodeGenFunction::EmitExprAsInit(const Expr *init,
1003                                     const ValueDecl *D,
1004                                     LValue lvalue,
1005                                     bool capturedByInit) {
1006  QualType type = D->getType();
1007
1008  if (type->isReferenceType()) {
1009    RValue rvalue = EmitReferenceBindingToExpr(init, D);
1010    if (capturedByInit)
1011      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1012    EmitStoreThroughLValue(rvalue, lvalue);
1013  } else if (!hasAggregateLLVMType(type)) {
1014    EmitScalarInit(init, D, lvalue, capturedByInit);
1015  } else if (type->isAnyComplexType()) {
1016    ComplexPairTy complex = EmitComplexExpr(init);
1017    if (capturedByInit)
1018      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1019    StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile());
1020  } else {
1021    // TODO: how can we delay here if D is captured by its initializer?
1022    EmitAggExpr(init, AggValueSlot::forLValue(lvalue, true, false));
1023  }
1024}
1025
1026/// Enter a destroy cleanup for the given local variable.
1027void CodeGenFunction::emitAutoVarTypeCleanup(
1028                            const CodeGenFunction::AutoVarEmission &emission,
1029                            QualType::DestructionKind dtorKind) {
1030  assert(dtorKind != QualType::DK_none);
1031
1032  // Note that for __block variables, we want to destroy the
1033  // original stack object, not the possibly forwarded object.
1034  llvm::Value *addr = emission.getObjectAddress(*this);
1035
1036  const VarDecl *var = emission.Variable;
1037  QualType type = var->getType();
1038
1039  CleanupKind cleanupKind = NormalAndEHCleanup;
1040  CodeGenFunction::Destroyer *destroyer = 0;
1041
1042  switch (dtorKind) {
1043  case QualType::DK_none:
1044    llvm_unreachable("no cleanup for trivially-destructible variable");
1045
1046  case QualType::DK_cxx_destructor:
1047    // If there's an NRVO flag on the emission, we need a different
1048    // cleanup.
1049    if (emission.NRVOFlag) {
1050      assert(!type->isArrayType());
1051      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1052      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1053                                               emission.NRVOFlag);
1054      return;
1055    }
1056    break;
1057
1058  case QualType::DK_objc_strong_lifetime:
1059    // Suppress cleanups for pseudo-strong variables.
1060    if (var->isARCPseudoStrong()) return;
1061
1062    // Otherwise, consider whether to use an EH cleanup or not.
1063    cleanupKind = getARCCleanupKind();
1064
1065    // Use the imprecise destroyer by default.
1066    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1067      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1068    break;
1069
1070  case QualType::DK_objc_weak_lifetime:
1071    break;
1072  }
1073
1074  // If we haven't chosen a more specific destroyer, use the default.
1075  if (!destroyer) destroyer = &getDestroyer(dtorKind);
1076
1077  // Use an EH cleanup in array destructors iff the destructor itself
1078  // is being pushed as an EH cleanup.
1079  bool useEHCleanup = (cleanupKind & EHCleanup);
1080  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1081                                     useEHCleanup);
1082}
1083
1084void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1085  assert(emission.Variable && "emission was not valid!");
1086
1087  // If this was emitted as a global constant, we're done.
1088  if (emission.wasEmittedAsGlobal()) return;
1089
1090  const VarDecl &D = *emission.Variable;
1091
1092  // Check the type for a cleanup.
1093  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1094    emitAutoVarTypeCleanup(emission, dtorKind);
1095
1096  // In GC mode, honor objc_precise_lifetime.
1097  if (getLangOptions().getGCMode() != LangOptions::NonGC &&
1098      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1099    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1100  }
1101
1102  // Handle the cleanup attribute.
1103  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1104    const FunctionDecl *FD = CA->getFunctionDecl();
1105
1106    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1107    assert(F && "Could not find function!");
1108
1109    const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
1110    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1111  }
1112
1113  // If this is a block variable, call _Block_object_destroy
1114  // (on the unforwarded address).
1115  if (emission.IsByRef)
1116    enterByrefCleanup(emission);
1117}
1118
1119CodeGenFunction::Destroyer &
1120CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1121  // This is surprisingly compiler-dependent.  GCC 4.2 can't bind
1122  // references to functions directly in returns, and using '*&foo'
1123  // confuses MSVC.  Luckily, the following code pattern works in both.
1124  Destroyer *destroyer = 0;
1125  switch (kind) {
1126  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1127  case QualType::DK_cxx_destructor:
1128    destroyer = &destroyCXXObject;
1129    break;
1130  case QualType::DK_objc_strong_lifetime:
1131    destroyer = &destroyARCStrongPrecise;
1132    break;
1133  case QualType::DK_objc_weak_lifetime:
1134    destroyer = &destroyARCWeak;
1135    break;
1136  }
1137  return *destroyer;
1138}
1139
1140/// pushDestroy - Push the standard destructor for the given type.
1141void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1142                                  llvm::Value *addr, QualType type) {
1143  assert(dtorKind && "cannot push destructor for trivial type");
1144
1145  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1146  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1147              cleanupKind & EHCleanup);
1148}
1149
1150void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1151                                  QualType type, Destroyer &destroyer,
1152                                  bool useEHCleanupForArray) {
1153  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1154                                     destroyer, useEHCleanupForArray);
1155}
1156
1157/// emitDestroy - Immediately perform the destruction of the given
1158/// object.
1159///
1160/// \param addr - the address of the object; a type*
1161/// \param type - the type of the object; if an array type, all
1162///   objects are destroyed in reverse order
1163/// \param destroyer - the function to call to destroy individual
1164///   elements
1165/// \param useEHCleanupForArray - whether an EH cleanup should be
1166///   used when destroying array elements, in case one of the
1167///   destructions throws an exception
1168void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1169                                  Destroyer &destroyer,
1170                                  bool useEHCleanupForArray) {
1171  const ArrayType *arrayType = getContext().getAsArrayType(type);
1172  if (!arrayType)
1173    return destroyer(*this, addr, type);
1174
1175  llvm::Value *begin = addr;
1176  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1177
1178  // Normally we have to check whether the array is zero-length.
1179  bool checkZeroLength = true;
1180
1181  // But if the array length is constant, we can suppress that.
1182  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1183    // ...and if it's constant zero, we can just skip the entire thing.
1184    if (constLength->isZero()) return;
1185    checkZeroLength = false;
1186  }
1187
1188  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1189  emitArrayDestroy(begin, end, type, destroyer,
1190                   checkZeroLength, useEHCleanupForArray);
1191}
1192
1193/// emitArrayDestroy - Destroys all the elements of the given array,
1194/// beginning from last to first.  The array cannot be zero-length.
1195///
1196/// \param begin - a type* denoting the first element of the array
1197/// \param end - a type* denoting one past the end of the array
1198/// \param type - the element type of the array
1199/// \param destroyer - the function to call to destroy elements
1200/// \param useEHCleanup - whether to push an EH cleanup to destroy
1201///   the remaining elements in case the destruction of a single
1202///   element throws
1203void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1204                                       llvm::Value *end,
1205                                       QualType type,
1206                                       Destroyer &destroyer,
1207                                       bool checkZeroLength,
1208                                       bool useEHCleanup) {
1209  assert(!type->isArrayType());
1210
1211  // The basic structure here is a do-while loop, because we don't
1212  // need to check for the zero-element case.
1213  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1214  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1215
1216  if (checkZeroLength) {
1217    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1218                                                "arraydestroy.isempty");
1219    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1220  }
1221
1222  // Enter the loop body, making that address the current address.
1223  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1224  EmitBlock(bodyBB);
1225  llvm::PHINode *elementPast =
1226    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1227  elementPast->addIncoming(end, entryBB);
1228
1229  // Shift the address back by one element.
1230  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1231  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1232                                                   "arraydestroy.element");
1233
1234  if (useEHCleanup)
1235    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1236
1237  // Perform the actual destruction there.
1238  destroyer(*this, element, type);
1239
1240  if (useEHCleanup)
1241    PopCleanupBlock();
1242
1243  // Check whether we've reached the end.
1244  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1245  Builder.CreateCondBr(done, doneBB, bodyBB);
1246  elementPast->addIncoming(element, Builder.GetInsertBlock());
1247
1248  // Done.
1249  EmitBlock(doneBB);
1250}
1251
1252/// Perform partial array destruction as if in an EH cleanup.  Unlike
1253/// emitArrayDestroy, the element type here may still be an array type.
1254static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1255                                    llvm::Value *begin, llvm::Value *end,
1256                                    QualType type,
1257                                    CodeGenFunction::Destroyer &destroyer) {
1258  // If the element type is itself an array, drill down.
1259  unsigned arrayDepth = 0;
1260  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1261    // VLAs don't require a GEP index to walk into.
1262    if (!isa<VariableArrayType>(arrayType))
1263      arrayDepth++;
1264    type = arrayType->getElementType();
1265  }
1266
1267  if (arrayDepth) {
1268    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1269
1270    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1271    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1272    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1273  }
1274
1275  // Destroy the array.  We don't ever need an EH cleanup because we
1276  // assume that we're in an EH cleanup ourselves, so a throwing
1277  // destructor causes an immediate terminate.
1278  CGF.emitArrayDestroy(begin, end, type, destroyer,
1279                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1280}
1281
1282namespace {
1283  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1284  /// array destroy where the end pointer is regularly determined and
1285  /// does not need to be loaded from a local.
1286  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1287    llvm::Value *ArrayBegin;
1288    llvm::Value *ArrayEnd;
1289    QualType ElementType;
1290    CodeGenFunction::Destroyer &Destroyer;
1291  public:
1292    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1293                               QualType elementType,
1294                               CodeGenFunction::Destroyer *destroyer)
1295      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1296        ElementType(elementType), Destroyer(*destroyer) {}
1297
1298    void Emit(CodeGenFunction &CGF, Flags flags) {
1299      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1300                              ElementType, Destroyer);
1301    }
1302  };
1303
1304  /// IrregularPartialArrayDestroy - a cleanup which performs a
1305  /// partial array destroy where the end pointer is irregularly
1306  /// determined and must be loaded from a local.
1307  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1308    llvm::Value *ArrayBegin;
1309    llvm::Value *ArrayEndPointer;
1310    QualType ElementType;
1311    CodeGenFunction::Destroyer &Destroyer;
1312  public:
1313    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1314                                 llvm::Value *arrayEndPointer,
1315                                 QualType elementType,
1316                                 CodeGenFunction::Destroyer *destroyer)
1317      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1318        ElementType(elementType), Destroyer(*destroyer) {}
1319
1320    void Emit(CodeGenFunction &CGF, Flags flags) {
1321      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1322      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1323                              ElementType, Destroyer);
1324    }
1325  };
1326}
1327
1328/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1329/// already-constructed elements of the given array.  The cleanup
1330/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1331///
1332/// \param elementType - the immediate element type of the array;
1333///   possibly still an array type
1334/// \param array - a value of type elementType*
1335/// \param destructionKind - the kind of destruction required
1336/// \param initializedElementCount - a value of type size_t* holding
1337///   the number of successfully-constructed elements
1338void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1339                                                 llvm::Value *arrayEndPointer,
1340                                                       QualType elementType,
1341                                                       Destroyer &destroyer) {
1342  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1343                                                    arrayBegin, arrayEndPointer,
1344                                                    elementType, &destroyer);
1345}
1346
1347/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1348/// already-constructed elements of the given array.  The cleanup
1349/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1350///
1351/// \param elementType - the immediate element type of the array;
1352///   possibly still an array type
1353/// \param array - a value of type elementType*
1354/// \param destructionKind - the kind of destruction required
1355/// \param initializedElementCount - a value of type size_t* holding
1356///   the number of successfully-constructed elements
1357void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1358                                                     llvm::Value *arrayEnd,
1359                                                     QualType elementType,
1360                                                     Destroyer &destroyer) {
1361  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1362                                                  arrayBegin, arrayEnd,
1363                                                  elementType, &destroyer);
1364}
1365
1366namespace {
1367  /// A cleanup to perform a release of an object at the end of a
1368  /// function.  This is used to balance out the incoming +1 of a
1369  /// ns_consumed argument when we can't reasonably do that just by
1370  /// not doing the initial retain for a __block argument.
1371  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1372    ConsumeARCParameter(llvm::Value *param) : Param(param) {}
1373
1374    llvm::Value *Param;
1375
1376    void Emit(CodeGenFunction &CGF, Flags flags) {
1377      CGF.EmitARCRelease(Param, /*precise*/ false);
1378    }
1379  };
1380}
1381
1382/// Emit an alloca (or GlobalValue depending on target)
1383/// for the specified parameter and set up LocalDeclMap.
1384void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1385                                   unsigned ArgNo) {
1386  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1387  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1388         "Invalid argument to EmitParmDecl");
1389
1390  Arg->setName(D.getName());
1391
1392  // Use better IR generation for certain implicit parameters.
1393  if (isa<ImplicitParamDecl>(D)) {
1394    // The only implicit argument a block has is its literal.
1395    if (BlockInfo) {
1396      LocalDeclMap[&D] = Arg;
1397
1398      if (CGDebugInfo *DI = getDebugInfo()) {
1399        DI->setLocation(D.getLocation());
1400        DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
1401      }
1402
1403      return;
1404    }
1405  }
1406
1407  QualType Ty = D.getType();
1408
1409  llvm::Value *DeclPtr;
1410  // If this is an aggregate or variable sized value, reuse the input pointer.
1411  if (!Ty->isConstantSizeType() ||
1412      CodeGenFunction::hasAggregateLLVMType(Ty)) {
1413    DeclPtr = Arg;
1414  } else {
1415    // Otherwise, create a temporary to hold the value.
1416    DeclPtr = CreateMemTemp(Ty, D.getName() + ".addr");
1417
1418    bool doStore = true;
1419
1420    Qualifiers qs = Ty.getQualifiers();
1421
1422    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1423      // We honor __attribute__((ns_consumed)) for types with lifetime.
1424      // For __strong, it's handled by just skipping the initial retain;
1425      // otherwise we have to balance out the initial +1 with an extra
1426      // cleanup to do the release at the end of the function.
1427      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1428
1429      // 'self' is always formally __strong, but if this is not an
1430      // init method then we don't want to retain it.
1431      if (D.isARCPseudoStrong()) {
1432        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1433        assert(&D == method->getSelfDecl());
1434        assert(lt == Qualifiers::OCL_Strong);
1435        assert(qs.hasConst());
1436        assert(method->getMethodFamily() != OMF_init);
1437        (void) method;
1438        lt = Qualifiers::OCL_ExplicitNone;
1439      }
1440
1441      if (lt == Qualifiers::OCL_Strong) {
1442        if (!isConsumed)
1443          // Don't use objc_retainBlock for block pointers, because we
1444          // don't want to Block_copy something just because we got it
1445          // as a parameter.
1446          Arg = EmitARCRetainNonBlock(Arg);
1447      } else {
1448        // Push the cleanup for a consumed parameter.
1449        if (isConsumed)
1450          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg);
1451
1452        if (lt == Qualifiers::OCL_Weak) {
1453          EmitARCInitWeak(DeclPtr, Arg);
1454          doStore = false; // The weak init is a store, no need to do two
1455        }
1456      }
1457
1458      // Enter the cleanup scope.
1459      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1460    }
1461
1462    // Store the initial value into the alloca.
1463    if (doStore) {
1464      LValue lv = MakeAddrLValue(DeclPtr, Ty,
1465                                 getContext().getDeclAlign(&D).getQuantity());
1466      EmitStoreOfScalar(Arg, lv);
1467    }
1468  }
1469
1470  llvm::Value *&DMEntry = LocalDeclMap[&D];
1471  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
1472  DMEntry = DeclPtr;
1473
1474  // Emit debug info for param declaration.
1475  if (CGDebugInfo *DI = getDebugInfo())
1476    DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1477}
1478