xref: /llvm-project/clang/lib/CodeGen/CodeGenModule.cpp (revision f804897ee94fe082cc840c5eca54ae6698324452)
1 //===--- CodeGenModule.cpp - Emit LLVM Code from ASTs for a Module --------===//
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 coordinates the per-module state used while generating code.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "CGDebugInfo.h"
15 #include "CodeGenModule.h"
16 #include "CodeGenFunction.h"
17 #include "CGCall.h"
18 #include "CGObjCRuntime.h"
19 #include "Mangle.h"
20 #include "clang/AST/ASTContext.h"
21 #include "clang/AST/DeclObjC.h"
22 #include "clang/AST/DeclCXX.h"
23 #include "clang/Basic/Diagnostic.h"
24 #include "clang/Basic/SourceManager.h"
25 #include "clang/Basic/TargetInfo.h"
26 #include "llvm/CallingConv.h"
27 #include "llvm/Module.h"
28 #include "llvm/Intrinsics.h"
29 #include "llvm/Target/TargetData.h"
30 using namespace clang;
31 using namespace CodeGen;
32 
33 
34 CodeGenModule::CodeGenModule(ASTContext &C, const LangOptions &LO,
35                              llvm::Module &M, const llvm::TargetData &TD,
36                              Diagnostic &diags, bool GenerateDebugInfo)
37   : BlockModule(C, M, TD, Types, *this), Context(C), Features(LO), TheModule(M),
38     TheTargetData(TD), Diags(diags), Types(C, M, TD), Runtime(0),
39     MemCpyFn(0), MemMoveFn(0), MemSetFn(0), CFConstantStringClassRef(0) {
40 
41   if (Features.ObjC1) {
42     if (Features.NeXTRuntime) {
43       Runtime = Features.ObjCNonFragileABI ? CreateMacNonFragileABIObjCRuntime(*this)
44                                        : CreateMacObjCRuntime(*this);
45     } else {
46       Runtime = CreateGNUObjCRuntime(*this);
47     }
48   }
49 
50   // If debug info generation is enabled, create the CGDebugInfo object.
51   DebugInfo = GenerateDebugInfo ? new CGDebugInfo(this) : 0;
52 }
53 
54 CodeGenModule::~CodeGenModule() {
55   delete Runtime;
56   delete DebugInfo;
57 }
58 
59 void CodeGenModule::Release() {
60   EmitDeferred();
61   EmitAliases();
62   if (Runtime)
63     if (llvm::Function *ObjCInitFunction = Runtime->ModuleInitFunction())
64       AddGlobalCtor(ObjCInitFunction);
65   EmitCtorList(GlobalCtors, "llvm.global_ctors");
66   EmitCtorList(GlobalDtors, "llvm.global_dtors");
67   EmitAnnotations();
68   EmitLLVMUsed();
69   BindRuntimeFunctions();
70 }
71 
72 void CodeGenModule::BindRuntimeFunctions() {
73   // Deal with protecting runtime function names.
74   for (unsigned i = 0, e = RuntimeFunctions.size(); i < e; ++i) {
75     llvm::Function *Fn = RuntimeFunctions[i].first;
76     const std::string &Name = RuntimeFunctions[i].second;
77 
78     // Discard unused runtime functions.
79     if (Fn->use_empty()) {
80       Fn->eraseFromParent();
81       continue;
82     }
83 
84     // See if there is a conflict against a function.
85     llvm::Function *Conflict = TheModule.getFunction(Name);
86     if (Conflict) {
87       // Decide which version to take. If the conflict is a definition
88       // we are forced to take that, otherwise assume the runtime
89       // knows best.
90       if (!Conflict->isDeclaration()) {
91         llvm::Value *Casted =
92           llvm::ConstantExpr::getBitCast(Conflict, Fn->getType());
93         Fn->replaceAllUsesWith(Casted);
94         Fn->eraseFromParent();
95       } else {
96         Fn->takeName(Conflict);
97         llvm::Value *Casted =
98           llvm::ConstantExpr::getBitCast(Fn, Conflict->getType());
99         Conflict->replaceAllUsesWith(Casted);
100         Conflict->eraseFromParent();
101       }
102     } else {
103       // FIXME: There still may be conflicts with aliases and
104       // variables.
105       Fn->setName(Name);
106     }
107   }
108 }
109 
110 /// ErrorUnsupported - Print out an error that codegen doesn't support the
111 /// specified stmt yet.
112 void CodeGenModule::ErrorUnsupported(const Stmt *S, const char *Type,
113                                      bool OmitOnError) {
114   if (OmitOnError && getDiags().hasErrorOccurred())
115     return;
116   unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
117                                                "cannot compile this %0 yet");
118   std::string Msg = Type;
119   getDiags().Report(Context.getFullLoc(S->getLocStart()), DiagID)
120     << Msg << S->getSourceRange();
121 }
122 
123 /// ErrorUnsupported - Print out an error that codegen doesn't support the
124 /// specified decl yet.
125 void CodeGenModule::ErrorUnsupported(const Decl *D, const char *Type,
126                                      bool OmitOnError) {
127   if (OmitOnError && getDiags().hasErrorOccurred())
128     return;
129   unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
130                                                "cannot compile this %0 yet");
131   std::string Msg = Type;
132   getDiags().Report(Context.getFullLoc(D->getLocation()), DiagID) << Msg;
133 }
134 
135 /// setGlobalVisibility - Set the visibility for the given LLVM
136 /// GlobalValue according to the given clang AST visibility value.
137 static void setGlobalVisibility(llvm::GlobalValue *GV,
138                                 VisibilityAttr::VisibilityTypes Vis) {
139   switch (Vis) {
140   default: assert(0 && "Unknown visibility!");
141   case VisibilityAttr::DefaultVisibility:
142     GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
143     break;
144   case VisibilityAttr::HiddenVisibility:
145     GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
146     break;
147   case VisibilityAttr::ProtectedVisibility:
148     GV->setVisibility(llvm::GlobalValue::ProtectedVisibility);
149     break;
150   }
151 }
152 
153 /// \brief Retrieves the mangled name for the given declaration.
154 ///
155 /// If the given declaration requires a mangled name, returns an
156 /// IdentifierInfo* containing the mangled name. Otherwise, returns
157 /// the name of the declaration as an identifier.
158 ///
159 /// FIXME: Returning an IdentifierInfo* here is a total hack. We
160 /// really need some kind of string abstraction that either stores a
161 /// mangled name or stores an IdentifierInfo*. This will require
162 /// changes to the GlobalDeclMap, too. (I disagree, I think what we
163 /// actually need is for Sema to provide some notion of which Decls
164 /// refer to the same semantic decl. We shouldn't need to mangle the
165 /// names and see what comes out the same to figure this out. - DWD)
166 ///
167 /// FIXME: Performance here is going to be terribly until we start
168 /// caching mangled names. However, we should fix the problem above
169 /// first.
170 const char *CodeGenModule::getMangledName(const NamedDecl *ND) {
171   llvm::SmallString<256> Name;
172   llvm::raw_svector_ostream Out(Name);
173   if (!mangleName(ND, Context, Out)) {
174     assert(ND->getIdentifier() && "Attempt to mangle unnamed decl.");
175     return ND->getIdentifier()->getName();
176   }
177 
178   Name += '\0';
179   return MangledNames.GetOrCreateValue(Name.begin(), Name.end())
180            .getKeyData();
181 }
182 
183 /// AddGlobalCtor - Add a function to the list that will be called before
184 /// main() runs.
185 void CodeGenModule::AddGlobalCtor(llvm::Function * Ctor, int Priority) {
186   // FIXME: Type coercion of void()* types.
187   GlobalCtors.push_back(std::make_pair(Ctor, Priority));
188 }
189 
190 /// AddGlobalDtor - Add a function to the list that will be called
191 /// when the module is unloaded.
192 void CodeGenModule::AddGlobalDtor(llvm::Function * Dtor, int Priority) {
193   // FIXME: Type coercion of void()* types.
194   GlobalDtors.push_back(std::make_pair(Dtor, Priority));
195 }
196 
197 void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
198   // Ctor function type is void()*.
199   llvm::FunctionType* CtorFTy =
200     llvm::FunctionType::get(llvm::Type::VoidTy,
201                             std::vector<const llvm::Type*>(),
202                             false);
203   llvm::Type *CtorPFTy = llvm::PointerType::getUnqual(CtorFTy);
204 
205   // Get the type of a ctor entry, { i32, void ()* }.
206   llvm::StructType* CtorStructTy =
207     llvm::StructType::get(llvm::Type::Int32Ty,
208                           llvm::PointerType::getUnqual(CtorFTy), NULL);
209 
210   // Construct the constructor and destructor arrays.
211   std::vector<llvm::Constant*> Ctors;
212   for (CtorList::const_iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
213     std::vector<llvm::Constant*> S;
214     S.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, I->second, false));
215     S.push_back(llvm::ConstantExpr::getBitCast(I->first, CtorPFTy));
216     Ctors.push_back(llvm::ConstantStruct::get(CtorStructTy, S));
217   }
218 
219   if (!Ctors.empty()) {
220     llvm::ArrayType *AT = llvm::ArrayType::get(CtorStructTy, Ctors.size());
221     new llvm::GlobalVariable(AT, false,
222                              llvm::GlobalValue::AppendingLinkage,
223                              llvm::ConstantArray::get(AT, Ctors),
224                              GlobalName,
225                              &TheModule);
226   }
227 }
228 
229 void CodeGenModule::EmitAnnotations() {
230   if (Annotations.empty())
231     return;
232 
233   // Create a new global variable for the ConstantStruct in the Module.
234   llvm::Constant *Array =
235   llvm::ConstantArray::get(llvm::ArrayType::get(Annotations[0]->getType(),
236                                                 Annotations.size()),
237                            Annotations);
238   llvm::GlobalValue *gv =
239   new llvm::GlobalVariable(Array->getType(), false,
240                            llvm::GlobalValue::AppendingLinkage, Array,
241                            "llvm.global.annotations", &TheModule);
242   gv->setSection("llvm.metadata");
243 }
244 
245 void CodeGenModule::SetGlobalValueAttributes(const Decl *D,
246                                              bool IsInternal,
247                                              bool IsInline,
248                                              llvm::GlobalValue *GV,
249                                              bool ForDefinition) {
250   // FIXME: Set up linkage and many other things.  Note, this is a simple
251   // approximation of what we really want.
252   if (!ForDefinition) {
253     // Only a few attributes are set on declarations.
254     if (D->getAttr<DLLImportAttr>()) {
255       // The dllimport attribute is overridden by a subsequent declaration as
256       // dllexport.
257       if (!D->getAttr<DLLExportAttr>()) {
258         // dllimport attribute can be applied only to function decls, not to
259         // definitions.
260         if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
261           if (!FD->getBody())
262             GV->setLinkage(llvm::Function::DLLImportLinkage);
263         } else
264           GV->setLinkage(llvm::Function::DLLImportLinkage);
265       }
266     } else if (D->getAttr<WeakAttr>())
267       GV->setLinkage(llvm::Function::ExternalWeakLinkage);
268   } else {
269     if (IsInternal) {
270       GV->setLinkage(llvm::Function::InternalLinkage);
271     } else {
272       if (D->getAttr<DLLExportAttr>()) {
273         if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
274           // The dllexport attribute is ignored for undefined symbols.
275           if (FD->getBody())
276             GV->setLinkage(llvm::Function::DLLExportLinkage);
277         } else
278           GV->setLinkage(llvm::Function::DLLExportLinkage);
279       } else if (D->getAttr<WeakAttr>() || IsInline)
280         GV->setLinkage(llvm::Function::WeakLinkage);
281     }
282   }
283 
284   // FIXME: Figure out the relative priority of the attribute,
285   // -fvisibility, and private_extern.
286   if (const VisibilityAttr *attr = D->getAttr<VisibilityAttr>())
287     setGlobalVisibility(GV, attr->getVisibility());
288   // FIXME: else handle -fvisibility
289 
290   // Prefaced with special LLVM marker to indicate that the name
291   // should not be munged.
292   if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>())
293     GV->setName("\01" + ALA->getLabel());
294 
295   if (const SectionAttr *SA = D->getAttr<SectionAttr>())
296     GV->setSection(SA->getName());
297 
298   // Only add to llvm.used when we see a definition, otherwise we
299   // might add multiple times or risk the value being replaced by a
300   // subsequent RAUW.
301   if (ForDefinition) {
302     if (D->getAttr<UsedAttr>())
303       AddUsedGlobal(GV);
304   }
305 }
306 
307 void CodeGenModule::SetFunctionAttributes(const Decl *D,
308                                           const CGFunctionInfo &Info,
309                                           llvm::Function *F) {
310   AttributeListType AttributeList;
311   ConstructAttributeList(Info, D, AttributeList);
312 
313   F->setAttributes(llvm::AttrListPtr::get(AttributeList.begin(),
314                                         AttributeList.size()));
315 
316   // Set the appropriate calling convention for the Function.
317   if (D->getAttr<FastCallAttr>())
318     F->setCallingConv(llvm::CallingConv::X86_FastCall);
319 
320   if (D->getAttr<StdCallAttr>())
321     F->setCallingConv(llvm::CallingConv::X86_StdCall);
322 }
323 
324 /// SetFunctionAttributesForDefinition - Set function attributes
325 /// specific to a function definition.
326 void CodeGenModule::SetFunctionAttributesForDefinition(const Decl *D,
327                                                        llvm::Function *F) {
328   if (isa<ObjCMethodDecl>(D)) {
329     SetGlobalValueAttributes(D, true, false, F, true);
330   } else {
331     const FunctionDecl *FD = cast<FunctionDecl>(D);
332     SetGlobalValueAttributes(FD, FD->getStorageClass() == FunctionDecl::Static,
333                              FD->isInline(), F, true);
334   }
335 
336   if (!Features.Exceptions && !Features.ObjCNonFragileABI)
337     F->addFnAttr(llvm::Attribute::NoUnwind);
338 
339   if (D->getAttr<AlwaysInlineAttr>())
340     F->addFnAttr(llvm::Attribute::AlwaysInline);
341 
342   if (D->getAttr<NoinlineAttr>())
343     F->addFnAttr(llvm::Attribute::NoInline);
344 }
345 
346 void CodeGenModule::SetMethodAttributes(const ObjCMethodDecl *MD,
347                                         llvm::Function *F) {
348   SetFunctionAttributes(MD, getTypes().getFunctionInfo(MD), F);
349 
350   SetFunctionAttributesForDefinition(MD, F);
351 }
352 
353 void CodeGenModule::SetFunctionAttributes(const FunctionDecl *FD,
354                                           llvm::Function *F) {
355   SetFunctionAttributes(FD, getTypes().getFunctionInfo(FD), F);
356 
357   SetGlobalValueAttributes(FD, FD->getStorageClass() == FunctionDecl::Static,
358                            FD->isInline(), F, false);
359 }
360 
361 
362 void CodeGenModule::EmitAliases() {
363   for (unsigned i = 0, e = Aliases.size(); i != e; ++i) {
364     const FunctionDecl *D = Aliases[i];
365     const AliasAttr *AA = D->getAttr<AliasAttr>();
366 
367     // This is something of a hack, if the FunctionDecl got overridden
368     // then its attributes will be moved to the new declaration. In
369     // this case the current decl has no alias attribute, but we will
370     // eventually see it.
371     if (!AA)
372       continue;
373 
374     const std::string& aliaseeName = AA->getAliasee();
375     llvm::Function *aliasee = getModule().getFunction(aliaseeName);
376     if (!aliasee) {
377       // FIXME: This isn't unsupported, this is just an error, which
378       // sema should catch, but...
379       ErrorUnsupported(D, "alias referencing a missing function");
380       continue;
381     }
382 
383     llvm::GlobalValue *GA =
384       new llvm::GlobalAlias(aliasee->getType(),
385                             llvm::Function::ExternalLinkage,
386                             getMangledName(D), aliasee,
387                             &getModule());
388 
389     llvm::GlobalValue *&Entry = GlobalDeclMap[getMangledName(D)];
390     if (Entry) {
391       // If we created a dummy function for this then replace it.
392       GA->takeName(Entry);
393 
394       llvm::Value *Casted =
395         llvm::ConstantExpr::getBitCast(GA, Entry->getType());
396       Entry->replaceAllUsesWith(Casted);
397       Entry->eraseFromParent();
398 
399       Entry = GA;
400     }
401 
402     // Alias should never be internal or inline.
403     SetGlobalValueAttributes(D, false, false, GA, true);
404   }
405 }
406 
407 void CodeGenModule::AddUsedGlobal(llvm::GlobalValue *GV) {
408   assert(!GV->isDeclaration() &&
409          "Only globals with definition can force usage.");
410   llvm::Type *i8PTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
411   LLVMUsed.push_back(llvm::ConstantExpr::getBitCast(GV, i8PTy));
412 }
413 
414 void CodeGenModule::EmitLLVMUsed() {
415   // Don't create llvm.used if there is no need.
416   if (LLVMUsed.empty())
417     return;
418 
419   llvm::ArrayType *ATy = llvm::ArrayType::get(LLVMUsed[0]->getType(),
420                                               LLVMUsed.size());
421   llvm::GlobalVariable *GV =
422     new llvm::GlobalVariable(ATy, false,
423                              llvm::GlobalValue::AppendingLinkage,
424                              llvm::ConstantArray::get(ATy, LLVMUsed),
425                              "llvm.used", &getModule());
426 
427   GV->setSection("llvm.metadata");
428 }
429 
430 void CodeGenModule::EmitDeferred() {
431   // Emit code for any deferred decl which was used.  Since a
432   // previously unused static decl may become used during the
433   // generation of code for a static function, iterate until no
434   // changes are made.
435   bool Changed;
436   do {
437     Changed = false;
438 
439     for (std::list<const ValueDecl*>::iterator i = DeferredDecls.begin(),
440          e = DeferredDecls.end(); i != e; ) {
441       const ValueDecl *D = *i;
442 
443       // Check if we have used a decl with the same name
444       // FIXME: The AST should have some sort of aggregate decls or
445       // global symbol map.
446       // FIXME: This is missing some important cases. For example, we
447       // need to check for uses in an alias.
448       if (!GlobalDeclMap.count(getMangledName(D))) {
449         ++i;
450         continue;
451       }
452 
453       // Emit the definition.
454       EmitGlobalDefinition(D);
455 
456       // Erase the used decl from the list.
457       i = DeferredDecls.erase(i);
458 
459       // Remember that we made a change.
460       Changed = true;
461     }
462   } while (Changed);
463 }
464 
465 /// EmitAnnotateAttr - Generate the llvm::ConstantStruct which contains the
466 /// annotation information for a given GlobalValue.  The annotation struct is
467 /// {i8 *, i8 *, i8 *, i32}.  The first field is a constant expression, the
468 /// GlobalValue being annotated.  The second field is the constant string
469 /// created from the AnnotateAttr's annotation.  The third field is a constant
470 /// string containing the name of the translation unit.  The fourth field is
471 /// the line number in the file of the annotated value declaration.
472 ///
473 /// FIXME: this does not unique the annotation string constants, as llvm-gcc
474 ///        appears to.
475 ///
476 llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
477                                                 const AnnotateAttr *AA,
478                                                 unsigned LineNo) {
479   llvm::Module *M = &getModule();
480 
481   // get [N x i8] constants for the annotation string, and the filename string
482   // which are the 2nd and 3rd elements of the global annotation structure.
483   const llvm::Type *SBP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
484   llvm::Constant *anno = llvm::ConstantArray::get(AA->getAnnotation(), true);
485   llvm::Constant *unit = llvm::ConstantArray::get(M->getModuleIdentifier(),
486                                                   true);
487 
488   // Get the two global values corresponding to the ConstantArrays we just
489   // created to hold the bytes of the strings.
490   llvm::GlobalValue *annoGV =
491   new llvm::GlobalVariable(anno->getType(), false,
492                            llvm::GlobalValue::InternalLinkage, anno,
493                            GV->getName() + ".str", M);
494   // translation unit name string, emitted into the llvm.metadata section.
495   llvm::GlobalValue *unitGV =
496   new llvm::GlobalVariable(unit->getType(), false,
497                            llvm::GlobalValue::InternalLinkage, unit, ".str", M);
498 
499   // Create the ConstantStruct that is the global annotion.
500   llvm::Constant *Fields[4] = {
501     llvm::ConstantExpr::getBitCast(GV, SBP),
502     llvm::ConstantExpr::getBitCast(annoGV, SBP),
503     llvm::ConstantExpr::getBitCast(unitGV, SBP),
504     llvm::ConstantInt::get(llvm::Type::Int32Ty, LineNo)
505   };
506   return llvm::ConstantStruct::get(Fields, 4, false);
507 }
508 
509 bool CodeGenModule::MayDeferGeneration(const ValueDecl *Global) {
510   // Never defer when EmitAllDecls is specified or the decl has
511   // attribute used.
512   if (Features.EmitAllDecls || Global->getAttr<UsedAttr>())
513     return false;
514 
515   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
516     // Constructors and destructors should never be deferred.
517     if (FD->getAttr<ConstructorAttr>() || FD->getAttr<DestructorAttr>())
518       return false;
519 
520     if (FD->getStorageClass() != FunctionDecl::Static)
521       return false;
522   } else {
523     const VarDecl *VD = cast<VarDecl>(Global);
524     assert(VD->isFileVarDecl() && "Invalid decl.");
525 
526     if (VD->getStorageClass() != VarDecl::Static)
527       return false;
528   }
529 
530   return true;
531 }
532 
533 void CodeGenModule::EmitGlobal(const ValueDecl *Global) {
534   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
535     // Aliases are deferred until code for everything else has been
536     // emitted.
537     if (FD->getAttr<AliasAttr>()) {
538       assert(!FD->isThisDeclarationADefinition() &&
539              "Function alias cannot have a definition!");
540       Aliases.push_back(FD);
541       return;
542     }
543 
544     // Forward declarations are emitted lazily on first use.
545     if (!FD->isThisDeclarationADefinition())
546       return;
547   } else {
548     const VarDecl *VD = cast<VarDecl>(Global);
549     assert(VD->isFileVarDecl() && "Cannot emit local var decl as global.");
550 
551     // Forward declarations are emitted lazily on first use.
552     if (!VD->getInit() && VD->hasExternalStorage())
553       return;
554   }
555 
556   // Defer code generation when possible.
557   if (MayDeferGeneration(Global)) {
558     DeferredDecls.push_back(Global);
559     return;
560   }
561 
562   // Otherwise emit the definition.
563   EmitGlobalDefinition(Global);
564 }
565 
566 void CodeGenModule::EmitGlobalDefinition(const ValueDecl *D) {
567   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
568     EmitGlobalFunctionDefinition(FD);
569   } else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
570     EmitGlobalVarDefinition(VD);
571   } else {
572     assert(0 && "Invalid argument to EmitGlobalDefinition()");
573   }
574 }
575 
576  llvm::Constant *CodeGenModule::GetAddrOfGlobalVar(const VarDecl *D) {
577   assert(D->hasGlobalStorage() && "Not a global variable");
578 
579   QualType ASTTy = D->getType();
580   const llvm::Type *Ty = getTypes().ConvertTypeForMem(ASTTy);
581   const llvm::Type *PTy = llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
582 
583   // Lookup the entry, lazily creating it if necessary.
584   llvm::GlobalValue *&Entry = GlobalDeclMap[getMangledName(D)];
585   if (!Entry) {
586     llvm::GlobalVariable *GV =
587       new llvm::GlobalVariable(Ty, false,
588                                llvm::GlobalValue::ExternalLinkage,
589                                0, getMangledName(D), &getModule(),
590                                0, ASTTy.getAddressSpace());
591     Entry = GV;
592 
593     // Handle things which are present even on external declarations.
594 
595     // FIXME: This code is overly simple and should be merged with
596     // other global handling.
597 
598     GV->setConstant(D->getType().isConstant(Context));
599 
600     // FIXME: Merge with other attribute handling code.
601 
602     if (D->getStorageClass() == VarDecl::PrivateExtern)
603       setGlobalVisibility(GV, VisibilityAttr::HiddenVisibility);
604 
605     if (D->getAttr<WeakAttr>())
606       GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
607 
608     if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
609       // Prefaced with special LLVM marker to indicate that the name
610       // should not be munged.
611       GV->setName("\01" + ALA->getLabel());
612     }
613   }
614 
615   // Make sure the result is of the correct type.
616   return llvm::ConstantExpr::getBitCast(Entry, PTy);
617 }
618 
619 void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
620   llvm::Constant *Init = 0;
621   QualType ASTTy = D->getType();
622   const llvm::Type *VarTy = getTypes().ConvertTypeForMem(ASTTy);
623 
624   if (D->getInit() == 0) {
625     // This is a tentative definition; tentative definitions are
626     // implicitly initialized with { 0 }
627     const llvm::Type* InitTy;
628     if (ASTTy->isIncompleteArrayType()) {
629       // An incomplete array is normally [ TYPE x 0 ], but we need
630       // to fix it to [ TYPE x 1 ].
631       const llvm::ArrayType* ATy = cast<llvm::ArrayType>(VarTy);
632       InitTy = llvm::ArrayType::get(ATy->getElementType(), 1);
633     } else {
634       InitTy = VarTy;
635     }
636     Init = llvm::Constant::getNullValue(InitTy);
637   } else {
638     Init = EmitConstantExpr(D->getInit());
639     if (!Init) {
640       ErrorUnsupported(D, "static initializer");
641       QualType T = D->getInit()->getType();
642       Init = llvm::UndefValue::get(getTypes().ConvertType(T));
643     }
644   }
645   const llvm::Type* InitType = Init->getType();
646 
647   llvm::GlobalValue *&Entry = GlobalDeclMap[getMangledName(D)];
648   llvm::GlobalVariable *GV = cast_or_null<llvm::GlobalVariable>(Entry);
649 
650   if (!GV) {
651     GV = new llvm::GlobalVariable(InitType, false,
652                                   llvm::GlobalValue::ExternalLinkage,
653                                   0, getMangledName(D),
654                                   &getModule(), 0, ASTTy.getAddressSpace());
655 
656   } else if (GV->hasInitializer() && !GV->getInitializer()->isNullValue()) {
657     // If we already have this global and it has an initializer, then
658     // we are in the rare situation where we emitted the defining
659     // declaration of the global and are now being asked to emit a
660     // definition which would be common. This occurs, for example, in
661     // the following situation because statics can be emitted out of
662     // order:
663     //
664     //  static int x;
665     //  static int *y = &x;
666     //  static int x = 10;
667     //  int **z = &y;
668     //
669     // Bail here so we don't blow away the definition. Note that if we
670     // can't distinguish here if we emitted a definition with a null
671     // initializer, but this case is safe.
672     assert(!D->getInit() && "Emitting multiple definitions of a decl!");
673     return;
674 
675   } else if (GV->getType() !=
676              llvm::PointerType::get(InitType, ASTTy.getAddressSpace())) {
677     // We have a definition after a prototype with the wrong type.
678     // We must make a new GlobalVariable* and update everything that used OldGV
679     // (a declaration or tentative definition) with the new GlobalVariable*
680     // (which will be a definition).
681     //
682     // This happens if there is a prototype for a global (e.g. "extern int x[];")
683     // and then a definition of a different type (e.g. "int x[10];"). This also
684     // happens when an initializer has a different type from the type of the
685     // global (this happens with unions).
686     //
687     // FIXME: This also ends up happening if there's a definition followed by
688     // a tentative definition!  (Although Sema rejects that construct
689     // at the moment.)
690 
691     // Save the old global
692     llvm::GlobalVariable *OldGV = GV;
693 
694     // Make a new global with the correct type
695     GV = new llvm::GlobalVariable(InitType, false,
696                                   llvm::GlobalValue::ExternalLinkage,
697                                   0, getMangledName(D),
698                                   &getModule(), 0, ASTTy.getAddressSpace());
699     // Steal the name of the old global
700     GV->takeName(OldGV);
701 
702     // Replace all uses of the old global with the new global
703     llvm::Constant *NewPtrForOldDecl =
704         llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
705     OldGV->replaceAllUsesWith(NewPtrForOldDecl);
706 
707     // Erase the old global, since it is no longer used.
708     OldGV->eraseFromParent();
709   }
710 
711   Entry = GV;
712 
713   if (const AnnotateAttr *AA = D->getAttr<AnnotateAttr>()) {
714     SourceManager &SM = Context.getSourceManager();
715     AddAnnotation(EmitAnnotateAttr(GV, AA,
716                               SM.getInstantiationLineNumber(D->getLocation())));
717   }
718 
719   GV->setInitializer(Init);
720   GV->setConstant(D->getType().isConstant(Context));
721   GV->setAlignment(getContext().getDeclAlignInBytes(D));
722 
723   if (const VisibilityAttr *attr = D->getAttr<VisibilityAttr>())
724     setGlobalVisibility(GV, attr->getVisibility());
725   // FIXME: else handle -fvisibility
726 
727   if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
728     // Prefaced with special LLVM marker to indicate that the name
729     // should not be munged.
730     GV->setName("\01" + ALA->getLabel());
731   }
732 
733   // Set the llvm linkage type as appropriate.
734   if (D->getStorageClass() == VarDecl::Static)
735     GV->setLinkage(llvm::Function::InternalLinkage);
736   else if (D->getAttr<DLLImportAttr>())
737     GV->setLinkage(llvm::Function::DLLImportLinkage);
738   else if (D->getAttr<DLLExportAttr>())
739     GV->setLinkage(llvm::Function::DLLExportLinkage);
740   else if (D->getAttr<WeakAttr>())
741     GV->setLinkage(llvm::GlobalVariable::WeakLinkage);
742   else {
743     // FIXME: This isn't right.  This should handle common linkage and other
744     // stuff.
745     switch (D->getStorageClass()) {
746     case VarDecl::Static: assert(0 && "This case handled above");
747     case VarDecl::Auto:
748     case VarDecl::Register:
749       assert(0 && "Can't have auto or register globals");
750     case VarDecl::None:
751       if (!D->getInit())
752         GV->setLinkage(llvm::GlobalVariable::CommonLinkage);
753       else
754         GV->setLinkage(llvm::GlobalVariable::ExternalLinkage);
755       break;
756     case VarDecl::Extern:
757       // FIXME: common
758       break;
759 
760     case VarDecl::PrivateExtern:
761       GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
762       // FIXME: common
763       break;
764     }
765   }
766 
767   if (const SectionAttr *SA = D->getAttr<SectionAttr>())
768     GV->setSection(SA->getName());
769 
770   if (D->getAttr<UsedAttr>())
771     AddUsedGlobal(GV);
772 
773   // Emit global variable debug information.
774   CGDebugInfo *DI = getDebugInfo();
775   if(DI) {
776     DI->setLocation(D->getLocation());
777     DI->EmitGlobalVariable(GV, D);
778   }
779 }
780 
781 llvm::GlobalValue *
782 CodeGenModule::EmitForwardFunctionDefinition(const FunctionDecl *D,
783                                              const llvm::Type *Ty) {
784   bool DoSetAttributes = true;
785   if (!Ty) {
786     Ty = getTypes().ConvertType(D->getType());
787     if (!isa<llvm::FunctionType>(Ty)) {
788       // This function doesn't have a complete type (for example, the return
789       // type is an incomplete struct). Use a fake type instead, and make
790       // sure not to try to set attributes.
791       Ty = llvm::FunctionType::get(llvm::Type::VoidTy,
792                                    std::vector<const llvm::Type*>(), false);
793       DoSetAttributes = false;
794     }
795   }
796   llvm::Function *F = llvm::Function::Create(cast<llvm::FunctionType>(Ty),
797                                              llvm::Function::ExternalLinkage,
798                                              getMangledName(D),
799                                              &getModule());
800   if (DoSetAttributes)
801     SetFunctionAttributes(D, F);
802   return F;
803 }
804 
805 llvm::Constant *CodeGenModule::GetAddrOfFunction(const FunctionDecl *D) {
806   QualType ASTTy = D->getType();
807   const llvm::Type *Ty = getTypes().ConvertTypeForMem(ASTTy);
808   const llvm::Type *PTy = llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
809 
810   // Lookup the entry, lazily creating it if necessary.
811   llvm::GlobalValue *&Entry = GlobalDeclMap[getMangledName(D)];
812   if (!Entry)
813     Entry = EmitForwardFunctionDefinition(D, 0);
814 
815   return llvm::ConstantExpr::getBitCast(Entry, PTy);
816 }
817 
818 void CodeGenModule::EmitGlobalFunctionDefinition(const FunctionDecl *D) {
819   const llvm::FunctionType *Ty =
820     cast<llvm::FunctionType>(getTypes().ConvertType(D->getType()));
821 
822   // As a special case, make sure that definitions of K&R function
823   // "type foo()" aren't declared as varargs (which forces the backend
824   // to do unnecessary work).
825   if (Ty->isVarArg() && Ty->getNumParams() == 0 && Ty->isVarArg())
826     Ty = llvm::FunctionType::get(Ty->getReturnType(),
827                                  std::vector<const llvm::Type*>(),
828                                  false);
829 
830   llvm::GlobalValue *&Entry = GlobalDeclMap[getMangledName(D)];
831   if (!Entry) {
832     Entry = EmitForwardFunctionDefinition(D, Ty);
833   } else {
834     // If the types mismatch then we have to rewrite the definition.
835     if (Entry->getType() != llvm::PointerType::getUnqual(Ty)) {
836       // Otherwise, we have a definition after a prototype with the
837       // wrong type.  F is the Function* for the one with the wrong
838       // type, we must make a new Function* and update everything that
839       // used F (a declaration) with the new Function* (which will be
840       // a definition).
841       //
842       // This happens if there is a prototype for a function
843       // (e.g. "int f()") and then a definition of a different type
844       // (e.g. "int f(int x)").  Start by making a new function of the
845       // correct type, RAUW, then steal the name.
846       llvm::GlobalValue *NewFn = EmitForwardFunctionDefinition(D, Ty);
847       NewFn->takeName(Entry);
848 
849       // Replace uses of F with the Function we will endow with a body.
850       llvm::Constant *NewPtrForOldDecl =
851         llvm::ConstantExpr::getBitCast(NewFn, Entry->getType());
852       Entry->replaceAllUsesWith(NewPtrForOldDecl);
853 
854       // Ok, delete the old function now, which is dead.
855       assert(Entry->isDeclaration() && "Shouldn't replace non-declaration");
856       Entry->eraseFromParent();
857 
858       Entry = NewFn;
859     }
860   }
861 
862   llvm::Function *Fn = cast<llvm::Function>(Entry);
863   CodeGenFunction(*this).GenerateCode(D, Fn);
864 
865   SetFunctionAttributesForDefinition(D, Fn);
866 
867   if (const ConstructorAttr *CA = D->getAttr<ConstructorAttr>()) {
868     AddGlobalCtor(Fn, CA->getPriority());
869   } else if (const DestructorAttr *DA = D->getAttr<DestructorAttr>()) {
870     AddGlobalDtor(Fn, DA->getPriority());
871   }
872 }
873 
874 llvm::Function *
875 CodeGenModule::CreateRuntimeFunction(const llvm::FunctionType *FTy,
876                                      const std::string &Name) {
877   llvm::Function *Fn = llvm::Function::Create(FTy,
878                                               llvm::Function::ExternalLinkage,
879                                               "", &TheModule);
880   RuntimeFunctions.push_back(std::make_pair(Fn, Name));
881   return Fn;
882 }
883 
884 void CodeGenModule::UpdateCompletedType(const TagDecl *TD) {
885   // Make sure that this type is translated.
886   Types.UpdateCompletedType(TD);
887 }
888 
889 
890 /// getBuiltinLibFunction
891 llvm::Value *CodeGenModule::getBuiltinLibFunction(unsigned BuiltinID) {
892   if (BuiltinID > BuiltinFunctions.size())
893     BuiltinFunctions.resize(BuiltinID);
894 
895   // Cache looked up functions.  Since builtin id #0 is invalid we don't reserve
896   // a slot for it.
897   assert(BuiltinID && "Invalid Builtin ID");
898   llvm::Value *&FunctionSlot = BuiltinFunctions[BuiltinID-1];
899   if (FunctionSlot)
900     return FunctionSlot;
901 
902   assert((Context.BuiltinInfo.isLibFunction(BuiltinID) ||
903           Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) &&
904          "isn't a lib fn");
905 
906   // Get the name, skip over the __builtin_ prefix (if necessary).
907   const char *Name = Context.BuiltinInfo.GetName(BuiltinID);
908   if (Context.BuiltinInfo.isLibFunction(BuiltinID))
909     Name += 10;
910 
911   // Get the type for the builtin.
912   Builtin::Context::GetBuiltinTypeError Error;
913   QualType Type = Context.BuiltinInfo.GetBuiltinType(BuiltinID, Context, Error);
914   assert(Error == Builtin::Context::GE_None && "Can't get builtin type");
915 
916   const llvm::FunctionType *Ty =
917     cast<llvm::FunctionType>(getTypes().ConvertType(Type));
918 
919   // FIXME: This has a serious problem with code like this:
920   //  void abs() {}
921   //    ... __builtin_abs(x);
922   // The two versions of abs will collide.  The fix is for the builtin to win,
923   // and for the existing one to be turned into a constantexpr cast of the
924   // builtin.  In the case where the existing one is a static function, it
925   // should just be renamed.
926   if (llvm::Function *Existing = getModule().getFunction(Name)) {
927     if (Existing->getFunctionType() == Ty && Existing->hasExternalLinkage())
928       return FunctionSlot = Existing;
929     assert(Existing == 0 && "FIXME: Name collision");
930   }
931 
932   llvm::GlobalValue *&ExistingFn =
933     GlobalDeclMap[getContext().Idents.get(Name).getName()];
934   if (ExistingFn)
935     return FunctionSlot = llvm::ConstantExpr::getBitCast(ExistingFn, Ty);
936 
937   // FIXME: param attributes for sext/zext etc.
938   return FunctionSlot = ExistingFn =
939     llvm::Function::Create(Ty, llvm::Function::ExternalLinkage, Name,
940                            &getModule());
941 }
942 
943 llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,const llvm::Type **Tys,
944                                             unsigned NumTys) {
945   return llvm::Intrinsic::getDeclaration(&getModule(),
946                                          (llvm::Intrinsic::ID)IID, Tys, NumTys);
947 }
948 
949 llvm::Function *CodeGenModule::getMemCpyFn() {
950   if (MemCpyFn) return MemCpyFn;
951   const llvm::Type *IntPtr = TheTargetData.getIntPtrType();
952   return MemCpyFn = getIntrinsic(llvm::Intrinsic::memcpy, &IntPtr, 1);
953 }
954 
955 llvm::Function *CodeGenModule::getMemMoveFn() {
956   if (MemMoveFn) return MemMoveFn;
957   const llvm::Type *IntPtr = TheTargetData.getIntPtrType();
958   return MemMoveFn = getIntrinsic(llvm::Intrinsic::memmove, &IntPtr, 1);
959 }
960 
961 llvm::Function *CodeGenModule::getMemSetFn() {
962   if (MemSetFn) return MemSetFn;
963   const llvm::Type *IntPtr = TheTargetData.getIntPtrType();
964   return MemSetFn = getIntrinsic(llvm::Intrinsic::memset, &IntPtr, 1);
965 }
966 
967 static void appendFieldAndPadding(CodeGenModule &CGM,
968                                   std::vector<llvm::Constant*>& Fields,
969                                   FieldDecl *FieldD, FieldDecl *NextFieldD,
970                                   llvm::Constant* Field,
971                                   RecordDecl* RD, const llvm::StructType *STy)
972 {
973   // Append the field.
974   Fields.push_back(Field);
975 
976   int StructFieldNo = CGM.getTypes().getLLVMFieldNo(FieldD);
977 
978   int NextStructFieldNo;
979   if (!NextFieldD) {
980     NextStructFieldNo = STy->getNumElements();
981   } else {
982     NextStructFieldNo = CGM.getTypes().getLLVMFieldNo(NextFieldD);
983   }
984 
985   // Append padding
986   for (int i = StructFieldNo + 1; i < NextStructFieldNo; i++) {
987     llvm::Constant *C =
988       llvm::Constant::getNullValue(STy->getElementType(StructFieldNo + 1));
989 
990     Fields.push_back(C);
991   }
992 }
993 
994 // We still need to work out the details of handling UTF-16.
995 // See: <rdr://2996215>
996 llvm::Constant *CodeGenModule::
997 GetAddrOfConstantCFString(const std::string &str) {
998   llvm::StringMapEntry<llvm::Constant *> &Entry =
999     CFConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
1000 
1001   if (Entry.getValue())
1002     return Entry.getValue();
1003 
1004   llvm::Constant *Zero = llvm::Constant::getNullValue(llvm::Type::Int32Ty);
1005   llvm::Constant *Zeros[] = { Zero, Zero };
1006 
1007   if (!CFConstantStringClassRef) {
1008     const llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
1009     Ty = llvm::ArrayType::get(Ty, 0);
1010 
1011     // FIXME: This is fairly broken if
1012     // __CFConstantStringClassReference is already defined, in that it
1013     // will get renamed and the user will most likely see an opaque
1014     // error message. This is a general issue with relying on
1015     // particular names.
1016     llvm::GlobalVariable *GV =
1017       new llvm::GlobalVariable(Ty, false,
1018                                llvm::GlobalVariable::ExternalLinkage, 0,
1019                                "__CFConstantStringClassReference",
1020                                &getModule());
1021 
1022     // Decay array -> ptr
1023     CFConstantStringClassRef =
1024       llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
1025   }
1026 
1027   QualType CFTy = getContext().getCFConstantStringType();
1028   RecordDecl *CFRD = CFTy->getAsRecordType()->getDecl();
1029 
1030   const llvm::StructType *STy =
1031     cast<llvm::StructType>(getTypes().ConvertType(CFTy));
1032 
1033   std::vector<llvm::Constant*> Fields;
1034   RecordDecl::field_iterator Field = CFRD->field_begin();
1035 
1036   // Class pointer.
1037   FieldDecl *CurField = *Field++;
1038   FieldDecl *NextField = *Field++;
1039   appendFieldAndPadding(*this, Fields, CurField, NextField,
1040                         CFConstantStringClassRef, CFRD, STy);
1041 
1042   // Flags.
1043   CurField = NextField;
1044   NextField = *Field++;
1045   const llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
1046   appendFieldAndPadding(*this, Fields, CurField, NextField,
1047                         llvm::ConstantInt::get(Ty, 0x07C8), CFRD, STy);
1048 
1049   // String pointer.
1050   CurField = NextField;
1051   NextField = *Field++;
1052   llvm::Constant *C = llvm::ConstantArray::get(str);
1053   C = new llvm::GlobalVariable(C->getType(), true,
1054                                llvm::GlobalValue::InternalLinkage,
1055                                C, ".str", &getModule());
1056   appendFieldAndPadding(*this, Fields, CurField, NextField,
1057                         llvm::ConstantExpr::getGetElementPtr(C, Zeros, 2),
1058                         CFRD, STy);
1059 
1060   // String length.
1061   CurField = NextField;
1062   NextField = 0;
1063   Ty = getTypes().ConvertType(getContext().LongTy);
1064   appendFieldAndPadding(*this, Fields, CurField, NextField,
1065                         llvm::ConstantInt::get(Ty, str.length()), CFRD, STy);
1066 
1067   // The struct.
1068   C = llvm::ConstantStruct::get(STy, Fields);
1069   llvm::GlobalVariable *GV =
1070     new llvm::GlobalVariable(C->getType(), true,
1071                              llvm::GlobalVariable::InternalLinkage,
1072                              C, "", &getModule());
1073 
1074   GV->setSection("__DATA,__cfstring");
1075   Entry.setValue(GV);
1076 
1077   return GV;
1078 }
1079 
1080 /// GetStringForStringLiteral - Return the appropriate bytes for a
1081 /// string literal, properly padded to match the literal type.
1082 std::string CodeGenModule::GetStringForStringLiteral(const StringLiteral *E) {
1083   const char *StrData = E->getStrData();
1084   unsigned Len = E->getByteLength();
1085 
1086   const ConstantArrayType *CAT =
1087     getContext().getAsConstantArrayType(E->getType());
1088   assert(CAT && "String isn't pointer or array!");
1089 
1090   // Resize the string to the right size.
1091   std::string Str(StrData, StrData+Len);
1092   uint64_t RealLen = CAT->getSize().getZExtValue();
1093 
1094   if (E->isWide())
1095     RealLen *= getContext().Target.getWCharWidth()/8;
1096 
1097   Str.resize(RealLen, '\0');
1098 
1099   return Str;
1100 }
1101 
1102 /// GetAddrOfConstantStringFromLiteral - Return a pointer to a
1103 /// constant array for the given string literal.
1104 llvm::Constant *
1105 CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
1106   // FIXME: This can be more efficient.
1107   return GetAddrOfConstantString(GetStringForStringLiteral(S));
1108 }
1109 
1110 /// GetAddrOfConstantStringFromObjCEncode - Return a pointer to a constant
1111 /// array for the given ObjCEncodeExpr node.
1112 llvm::Constant *
1113 CodeGenModule::GetAddrOfConstantStringFromObjCEncode(const ObjCEncodeExpr *E) {
1114   std::string Str;
1115   getContext().getObjCEncodingForType(E->getEncodedType(), Str);
1116 
1117   llvm::Constant *C = llvm::ConstantArray::get(Str);
1118   C = new llvm::GlobalVariable(C->getType(), true,
1119                                llvm::GlobalValue::InternalLinkage,
1120                                C, ".str", &getModule());
1121   return C;
1122 }
1123 
1124 
1125 /// GenerateWritableString -- Creates storage for a string literal.
1126 static llvm::Constant *GenerateStringLiteral(const std::string &str,
1127                                              bool constant,
1128                                              CodeGenModule &CGM,
1129                                              const char *GlobalName) {
1130   // Create Constant for this string literal. Don't add a '\0'.
1131   llvm::Constant *C = llvm::ConstantArray::get(str, false);
1132 
1133   // Create a global variable for this string
1134   return new llvm::GlobalVariable(C->getType(), constant,
1135                                   llvm::GlobalValue::InternalLinkage,
1136                                   C, GlobalName ? GlobalName : ".str",
1137                                   &CGM.getModule());
1138 }
1139 
1140 /// GetAddrOfConstantString - Returns a pointer to a character array
1141 /// containing the literal. This contents are exactly that of the
1142 /// given string, i.e. it will not be null terminated automatically;
1143 /// see GetAddrOfConstantCString. Note that whether the result is
1144 /// actually a pointer to an LLVM constant depends on
1145 /// Feature.WriteableStrings.
1146 ///
1147 /// The result has pointer to array type.
1148 llvm::Constant *CodeGenModule::GetAddrOfConstantString(const std::string &str,
1149                                                        const char *GlobalName) {
1150   // Don't share any string literals if writable-strings is turned on.
1151   if (Features.WritableStrings)
1152     return GenerateStringLiteral(str, false, *this, GlobalName);
1153 
1154   llvm::StringMapEntry<llvm::Constant *> &Entry =
1155   ConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
1156 
1157   if (Entry.getValue())
1158     return Entry.getValue();
1159 
1160   // Create a global variable for this.
1161   llvm::Constant *C = GenerateStringLiteral(str, true, *this, GlobalName);
1162   Entry.setValue(C);
1163   return C;
1164 }
1165 
1166 /// GetAddrOfConstantCString - Returns a pointer to a character
1167 /// array containing the literal and a terminating '\-'
1168 /// character. The result has pointer to array type.
1169 llvm::Constant *CodeGenModule::GetAddrOfConstantCString(const std::string &str,
1170                                                         const char *GlobalName){
1171   return GetAddrOfConstantString(str + '\0', GlobalName);
1172 }
1173 
1174 /// EmitObjCPropertyImplementations - Emit information for synthesized
1175 /// properties for an implementation.
1176 void CodeGenModule::EmitObjCPropertyImplementations(const
1177                                                     ObjCImplementationDecl *D) {
1178   for (ObjCImplementationDecl::propimpl_iterator i = D->propimpl_begin(),
1179          e = D->propimpl_end(); i != e; ++i) {
1180     ObjCPropertyImplDecl *PID = *i;
1181 
1182     // Dynamic is just for type-checking.
1183     if (PID->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize) {
1184       ObjCPropertyDecl *PD = PID->getPropertyDecl();
1185 
1186       // Determine which methods need to be implemented, some may have
1187       // been overridden. Note that ::isSynthesized is not the method
1188       // we want, that just indicates if the decl came from a
1189       // property. What we want to know is if the method is defined in
1190       // this implementation.
1191       if (!D->getInstanceMethod(PD->getGetterName()))
1192         CodeGenFunction(*this).GenerateObjCGetter(
1193                                  const_cast<ObjCImplementationDecl *>(D), PID);
1194       if (!PD->isReadOnly() &&
1195           !D->getInstanceMethod(PD->getSetterName()))
1196         CodeGenFunction(*this).GenerateObjCSetter(
1197                                  const_cast<ObjCImplementationDecl *>(D), PID);
1198     }
1199   }
1200 }
1201 
1202 /// EmitTopLevelDecl - Emit code for a single top level declaration.
1203 void CodeGenModule::EmitTopLevelDecl(Decl *D) {
1204   // If an error has occurred, stop code generation, but continue
1205   // parsing and semantic analysis (to ensure all warnings and errors
1206   // are emitted).
1207   if (Diags.hasErrorOccurred())
1208     return;
1209 
1210   switch (D->getKind()) {
1211   case Decl::Function:
1212   case Decl::Var:
1213     EmitGlobal(cast<ValueDecl>(D));
1214     break;
1215 
1216   case Decl::Namespace:
1217     ErrorUnsupported(D, "namespace");
1218     break;
1219 
1220     // Objective-C Decls
1221 
1222     // Forward declarations, no (immediate) code generation.
1223   case Decl::ObjCClass:
1224   case Decl::ObjCCategory:
1225   case Decl::ObjCForwardProtocol:
1226   case Decl::ObjCInterface:
1227     break;
1228 
1229   case Decl::ObjCProtocol:
1230     Runtime->GenerateProtocol(cast<ObjCProtocolDecl>(D));
1231     break;
1232 
1233   case Decl::ObjCCategoryImpl:
1234     // Categories have properties but don't support synthesize so we
1235     // can ignore them here.
1236 
1237     Runtime->GenerateCategory(cast<ObjCCategoryImplDecl>(D));
1238     break;
1239 
1240   case Decl::ObjCImplementation: {
1241     ObjCImplementationDecl *OMD = cast<ObjCImplementationDecl>(D);
1242     EmitObjCPropertyImplementations(OMD);
1243     Runtime->GenerateClass(OMD);
1244     break;
1245   }
1246   case Decl::ObjCMethod: {
1247     ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(D);
1248     // If this is not a prototype, emit the body.
1249     if (OMD->getBody())
1250       CodeGenFunction(*this).GenerateObjCMethod(OMD);
1251     break;
1252   }
1253   case Decl::ObjCCompatibleAlias:
1254     // compatibility-alias is a directive and has no code gen.
1255     break;
1256 
1257   case Decl::LinkageSpec: {
1258     LinkageSpecDecl *LSD = cast<LinkageSpecDecl>(D);
1259     if (LSD->getLanguage() == LinkageSpecDecl::lang_cxx)
1260       ErrorUnsupported(LSD, "linkage spec");
1261     // FIXME: implement C++ linkage, C linkage works mostly by C
1262     // language reuse already.
1263     break;
1264   }
1265 
1266   case Decl::FileScopeAsm: {
1267     FileScopeAsmDecl *AD = cast<FileScopeAsmDecl>(D);
1268     std::string AsmString(AD->getAsmString()->getStrData(),
1269                           AD->getAsmString()->getByteLength());
1270 
1271     const std::string &S = getModule().getModuleInlineAsm();
1272     if (S.empty())
1273       getModule().setModuleInlineAsm(AsmString);
1274     else
1275       getModule().setModuleInlineAsm(S + '\n' + AsmString);
1276     break;
1277   }
1278 
1279   default:
1280     // Make sure we handled everything we should, every other kind is
1281     // a non-top-level decl.  FIXME: Would be nice to have an
1282     // isTopLevelDeclKind function. Need to recode Decl::Kind to do
1283     // that easily.
1284     assert(isa<TypeDecl>(D) && "Unsupported decl kind");
1285   }
1286 }
1287