CodeGenModule.cpp revision 04d4078425614bf9fd58d606335c1f5f74ee7fa4 
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 "CodeGenModule.h"
15#include "CGDebugInfo.h"
16#include "CodeGenFunction.h"
17#include "CGCall.h"
18#include "CGObjCRuntime.h"
19#include "Mangle.h"
20#include "clang/Frontend/CompileOptions.h"
21#include "clang/AST/ASTContext.h"
22#include "clang/AST/DeclObjC.h"
23#include "clang/AST/DeclCXX.h"
24#include "clang/Basic/Diagnostic.h"
25#include "clang/Basic/SourceManager.h"
26#include "clang/Basic/TargetInfo.h"
27#include "clang/Basic/ConvertUTF.h"
28#include "llvm/CallingConv.h"
29#include "llvm/Module.h"
30#include "llvm/Intrinsics.h"
31#include "llvm/Target/TargetData.h"
32using namespace clang;
33using namespace CodeGen;
34
35
36CodeGenModule::CodeGenModule(ASTContext &C, const CompileOptions &compileOpts,
37                             llvm::Module &M, const llvm::TargetData &TD,
38                             Diagnostic &diags)
39  : BlockModule(C, M, TD, Types, *this), Context(C),
40    Features(C.getLangOptions()), CompileOpts(compileOpts), TheModule(M),
41    TheTargetData(TD), Diags(diags), Types(C, M, TD), Runtime(0),
42    MemCpyFn(0), MemMoveFn(0), MemSetFn(0), CFConstantStringClassRef(0) {
43
44  if (!Features.ObjC1)
45    Runtime = 0;
46  else if (!Features.NeXTRuntime)
47    Runtime = CreateGNUObjCRuntime(*this);
48  else if (Features.ObjCNonFragileABI)
49    Runtime = CreateMacNonFragileABIObjCRuntime(*this);
50  else
51    Runtime = CreateMacObjCRuntime(*this);
52
53  // If debug info generation is enabled, create the CGDebugInfo object.
54  DebugInfo = CompileOpts.DebugInfo ? new CGDebugInfo(this) : 0;
55}
56
57CodeGenModule::~CodeGenModule() {
58  delete Runtime;
59  delete DebugInfo;
60}
61
62void CodeGenModule::Release() {
63  EmitDeferred();
64  if (Runtime)
65    if (llvm::Function *ObjCInitFunction = Runtime->ModuleInitFunction())
66      AddGlobalCtor(ObjCInitFunction);
67  EmitCtorList(GlobalCtors, "llvm.global_ctors");
68  EmitCtorList(GlobalDtors, "llvm.global_dtors");
69  EmitAnnotations();
70  EmitLLVMUsed();
71}
72
73/// ErrorUnsupported - Print out an error that codegen doesn't support the
74/// specified stmt yet.
75void CodeGenModule::ErrorUnsupported(const Stmt *S, const char *Type,
76                                     bool OmitOnError) {
77  if (OmitOnError && getDiags().hasErrorOccurred())
78    return;
79  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
80                                               "cannot compile this %0 yet");
81  std::string Msg = Type;
82  getDiags().Report(Context.getFullLoc(S->getLocStart()), DiagID)
83    << Msg << S->getSourceRange();
84}
85
86/// ErrorUnsupported - Print out an error that codegen doesn't support the
87/// specified decl yet.
88void CodeGenModule::ErrorUnsupported(const Decl *D, const char *Type,
89                                     bool OmitOnError) {
90  if (OmitOnError && getDiags().hasErrorOccurred())
91    return;
92  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
93                                               "cannot compile this %0 yet");
94  std::string Msg = Type;
95  getDiags().Report(Context.getFullLoc(D->getLocation()), DiagID) << Msg;
96}
97
98LangOptions::VisibilityMode
99CodeGenModule::getDeclVisibilityMode(const Decl *D) const {
100  if (const VarDecl *VD = dyn_cast<VarDecl>(D))
101    if (VD->getStorageClass() == VarDecl::PrivateExtern)
102      return LangOptions::Hidden;
103
104  if (const VisibilityAttr *attr = D->getAttr<VisibilityAttr>()) {
105    switch (attr->getVisibility()) {
106    default: assert(0 && "Unknown visibility!");
107    case VisibilityAttr::DefaultVisibility:
108      return LangOptions::Default;
109    case VisibilityAttr::HiddenVisibility:
110      return LangOptions::Hidden;
111    case VisibilityAttr::ProtectedVisibility:
112      return LangOptions::Protected;
113    }
114  }
115
116  return getLangOptions().getVisibilityMode();
117}
118
119void CodeGenModule::setGlobalVisibility(llvm::GlobalValue *GV,
120                                        const Decl *D) const {
121  // Internal definitions always have default visibility.
122  if (GV->hasLocalLinkage()) {
123    GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
124    return;
125  }
126
127  switch (getDeclVisibilityMode(D)) {
128  default: assert(0 && "Unknown visibility!");
129  case LangOptions::Default:
130    return GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
131  case LangOptions::Hidden:
132    return GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
133  case LangOptions::Protected:
134    return GV->setVisibility(llvm::GlobalValue::ProtectedVisibility);
135  }
136}
137
138/// \brief Retrieves the mangled name for the given declaration.
139///
140/// If the given declaration requires a mangled name, returns an
141/// const char* containing the mangled name.  Otherwise, returns
142/// the unmangled name.
143///
144const char *CodeGenModule::getMangledName(const NamedDecl *ND) {
145  // In C, functions with no attributes never need to be mangled. Fastpath them.
146  if (!getLangOptions().CPlusPlus && !ND->hasAttrs()) {
147    assert(ND->getIdentifier() && "Attempt to mangle unnamed decl.");
148    return ND->getNameAsCString();
149  }
150
151  llvm::SmallString<256> Name;
152  llvm::raw_svector_ostream Out(Name);
153  if (!mangleName(ND, Context, Out)) {
154    assert(ND->getIdentifier() && "Attempt to mangle unnamed decl.");
155    return ND->getNameAsCString();
156  }
157
158  Name += '\0';
159  return MangledNames.GetOrCreateValue(Name.begin(), Name.end()).getKeyData();
160}
161
162/// AddGlobalCtor - Add a function to the list that will be called before
163/// main() runs.
164void CodeGenModule::AddGlobalCtor(llvm::Function * Ctor, int Priority) {
165  // FIXME: Type coercion of void()* types.
166  GlobalCtors.push_back(std::make_pair(Ctor, Priority));
167}
168
169/// AddGlobalDtor - Add a function to the list that will be called
170/// when the module is unloaded.
171void CodeGenModule::AddGlobalDtor(llvm::Function * Dtor, int Priority) {
172  // FIXME: Type coercion of void()* types.
173  GlobalDtors.push_back(std::make_pair(Dtor, Priority));
174}
175
176void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
177  // Ctor function type is void()*.
178  llvm::FunctionType* CtorFTy =
179    llvm::FunctionType::get(llvm::Type::VoidTy,
180                            std::vector<const llvm::Type*>(),
181                            false);
182  llvm::Type *CtorPFTy = llvm::PointerType::getUnqual(CtorFTy);
183
184  // Get the type of a ctor entry, { i32, void ()* }.
185  llvm::StructType* CtorStructTy =
186    llvm::StructType::get(llvm::Type::Int32Ty,
187                          llvm::PointerType::getUnqual(CtorFTy), NULL);
188
189  // Construct the constructor and destructor arrays.
190  std::vector<llvm::Constant*> Ctors;
191  for (CtorList::const_iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
192    std::vector<llvm::Constant*> S;
193    S.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, I->second, false));
194    S.push_back(llvm::ConstantExpr::getBitCast(I->first, CtorPFTy));
195    Ctors.push_back(llvm::ConstantStruct::get(CtorStructTy, S));
196  }
197
198  if (!Ctors.empty()) {
199    llvm::ArrayType *AT = llvm::ArrayType::get(CtorStructTy, Ctors.size());
200    new llvm::GlobalVariable(AT, false,
201                             llvm::GlobalValue::AppendingLinkage,
202                             llvm::ConstantArray::get(AT, Ctors),
203                             GlobalName,
204                             &TheModule);
205  }
206}
207
208void CodeGenModule::EmitAnnotations() {
209  if (Annotations.empty())
210    return;
211
212  // Create a new global variable for the ConstantStruct in the Module.
213  llvm::Constant *Array =
214  llvm::ConstantArray::get(llvm::ArrayType::get(Annotations[0]->getType(),
215                                                Annotations.size()),
216                           Annotations);
217  llvm::GlobalValue *gv =
218  new llvm::GlobalVariable(Array->getType(), false,
219                           llvm::GlobalValue::AppendingLinkage, Array,
220                           "llvm.global.annotations", &TheModule);
221  gv->setSection("llvm.metadata");
222}
223
224void CodeGenModule::SetGlobalValueAttributes(const Decl *D,
225                                             bool IsInternal,
226                                             bool IsInline,
227                                             llvm::GlobalValue *GV,
228                                             bool ForDefinition) {
229  // FIXME: Set up linkage and many other things.  Note, this is a simple
230  // approximation of what we really want.
231  if (!ForDefinition) {
232    // Only a few attributes are set on declarations.
233
234    // The dllimport attribute is overridden by a subsequent declaration as
235    // dllexport.
236    if (D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>()) {
237      // dllimport attribute can be applied only to function decls, not to
238      // definitions.
239      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
240        if (!FD->getBody())
241          GV->setLinkage(llvm::Function::DLLImportLinkage);
242      } else
243        GV->setLinkage(llvm::Function::DLLImportLinkage);
244    } else if (D->hasAttr<WeakAttr>() || D->hasAttr<WeakImportAttr>()) {
245      // "extern_weak" is overloaded in LLVM; we probably should have
246      // separate linkage types for this.
247      GV->setLinkage(llvm::Function::ExternalWeakLinkage);
248    }
249  } else if (IsInternal) {
250    GV->setLinkage(llvm::Function::InternalLinkage);
251  } else if (D->hasAttr<DLLExportAttr>()) {
252    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
253      // The dllexport attribute is ignored for undefined symbols.
254      if (FD->getBody())
255        GV->setLinkage(llvm::Function::DLLExportLinkage);
256    } else {
257      GV->setLinkage(llvm::Function::DLLExportLinkage);
258    }
259  } else if (D->hasAttr<WeakAttr>() || D->hasAttr<WeakImportAttr>() ||
260             IsInline) {
261    GV->setLinkage(llvm::Function::WeakAnyLinkage);
262  }
263
264  if (ForDefinition) {
265    setGlobalVisibility(GV, D);
266
267    // Only add to llvm.used when we see a definition, otherwise we
268    // might add multiple times or risk the value being replaced by a
269    // subsequent RAUW.
270    if (D->hasAttr<UsedAttr>())
271      AddUsedGlobal(GV);
272  }
273
274  if (const SectionAttr *SA = D->getAttr<SectionAttr>())
275    GV->setSection(SA->getName());
276}
277
278void CodeGenModule::SetFunctionAttributes(const Decl *D,
279                                          const CGFunctionInfo &Info,
280                                          llvm::Function *F) {
281  AttributeListType AttributeList;
282  ConstructAttributeList(Info, D, AttributeList);
283
284  F->setAttributes(llvm::AttrListPtr::get(AttributeList.begin(),
285                                        AttributeList.size()));
286
287  // Set the appropriate calling convention for the Function.
288  if (D->hasAttr<FastCallAttr>())
289    F->setCallingConv(llvm::CallingConv::X86_FastCall);
290
291  if (D->hasAttr<StdCallAttr>())
292    F->setCallingConv(llvm::CallingConv::X86_StdCall);
293}
294
295/// SetFunctionAttributesForDefinition - Set function attributes
296/// specific to a function definition.
297void CodeGenModule::SetFunctionAttributesForDefinition(const Decl *D,
298                                                       llvm::Function *F) {
299  if (isa<ObjCMethodDecl>(D)) {
300    SetGlobalValueAttributes(D, true, false, F, true);
301  } else {
302    const FunctionDecl *FD = cast<FunctionDecl>(D);
303    SetGlobalValueAttributes(FD, FD->getStorageClass() == FunctionDecl::Static,
304                             FD->isInline(), F, true);
305  }
306
307  if (!Features.Exceptions && !Features.ObjCNonFragileABI)
308    F->addFnAttr(llvm::Attribute::NoUnwind);
309
310  if (D->hasAttr<AlwaysInlineAttr>())
311    F->addFnAttr(llvm::Attribute::AlwaysInline);
312
313  if (D->hasAttr<NoinlineAttr>())
314    F->addFnAttr(llvm::Attribute::NoInline);
315}
316
317void CodeGenModule::SetMethodAttributes(const ObjCMethodDecl *MD,
318                                        llvm::Function *F) {
319  SetFunctionAttributes(MD, getTypes().getFunctionInfo(MD), F);
320
321  SetFunctionAttributesForDefinition(MD, F);
322}
323
324void CodeGenModule::SetFunctionAttributes(const FunctionDecl *FD,
325                                          llvm::Function *F) {
326  SetFunctionAttributes(FD, getTypes().getFunctionInfo(FD), F);
327
328  SetGlobalValueAttributes(FD, FD->getStorageClass() == FunctionDecl::Static,
329                           FD->isInline(), F, false);
330}
331
332void CodeGenModule::AddUsedGlobal(llvm::GlobalValue *GV) {
333  assert(!GV->isDeclaration() &&
334         "Only globals with definition can force usage.");
335  LLVMUsed.push_back(GV);
336}
337
338void CodeGenModule::EmitLLVMUsed() {
339  // Don't create llvm.used if there is no need.
340  if (LLVMUsed.empty())
341    return;
342
343  llvm::Type *i8PTy = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
344  llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, LLVMUsed.size());
345
346  // Convert LLVMUsed to what ConstantArray needs.
347  std::vector<llvm::Constant*> UsedArray;
348  UsedArray.resize(LLVMUsed.size());
349  for (unsigned i = 0, e = LLVMUsed.size(); i != e; ++i) {
350    UsedArray[i] =
351     llvm::ConstantExpr::getBitCast(cast<llvm::Constant>(&*LLVMUsed[i]), i8PTy);
352  }
353
354  llvm::GlobalVariable *GV =
355    new llvm::GlobalVariable(ATy, false,
356                             llvm::GlobalValue::AppendingLinkage,
357                             llvm::ConstantArray::get(ATy, UsedArray),
358                             "llvm.used", &getModule());
359
360  GV->setSection("llvm.metadata");
361}
362
363void CodeGenModule::EmitDeferred() {
364  // Emit code for any potentially referenced deferred decls.  Since a
365  // previously unused static decl may become used during the generation of code
366  // for a static function, iterate until no  changes are made.
367  while (!DeferredDeclsToEmit.empty()) {
368    const ValueDecl *D = DeferredDeclsToEmit.back();
369    DeferredDeclsToEmit.pop_back();
370
371    // The mangled name for the decl must have been emitted in GlobalDeclMap.
372    // Look it up to see if it was defined with a stronger definition (e.g. an
373    // extern inline function with a strong function redefinition).  If so,
374    // just ignore the deferred decl.
375    llvm::GlobalValue *CGRef = GlobalDeclMap[getMangledName(D)];
376    assert(CGRef && "Deferred decl wasn't referenced?");
377
378    if (!CGRef->isDeclaration())
379      continue;
380
381    // Otherwise, emit the definition and move on to the next one.
382    EmitGlobalDefinition(D);
383  }
384}
385
386/// EmitAnnotateAttr - Generate the llvm::ConstantStruct which contains the
387/// annotation information for a given GlobalValue.  The annotation struct is
388/// {i8 *, i8 *, i8 *, i32}.  The first field is a constant expression, the
389/// GlobalValue being annotated.  The second field is the constant string
390/// created from the AnnotateAttr's annotation.  The third field is a constant
391/// string containing the name of the translation unit.  The fourth field is
392/// the line number in the file of the annotated value declaration.
393///
394/// FIXME: this does not unique the annotation string constants, as llvm-gcc
395///        appears to.
396///
397llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
398                                                const AnnotateAttr *AA,
399                                                unsigned LineNo) {
400  llvm::Module *M = &getModule();
401
402  // get [N x i8] constants for the annotation string, and the filename string
403  // which are the 2nd and 3rd elements of the global annotation structure.
404  const llvm::Type *SBP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
405  llvm::Constant *anno = llvm::ConstantArray::get(AA->getAnnotation(), true);
406  llvm::Constant *unit = llvm::ConstantArray::get(M->getModuleIdentifier(),
407                                                  true);
408
409  // Get the two global values corresponding to the ConstantArrays we just
410  // created to hold the bytes of the strings.
411  const char *StringPrefix = getContext().Target.getStringSymbolPrefix(true);
412  llvm::GlobalValue *annoGV =
413  new llvm::GlobalVariable(anno->getType(), false,
414                           llvm::GlobalValue::InternalLinkage, anno,
415                           GV->getName() + StringPrefix, M);
416  // translation unit name string, emitted into the llvm.metadata section.
417  llvm::GlobalValue *unitGV =
418  new llvm::GlobalVariable(unit->getType(), false,
419                           llvm::GlobalValue::InternalLinkage, unit,
420                           StringPrefix, M);
421
422  // Create the ConstantStruct that is the global annotion.
423  llvm::Constant *Fields[4] = {
424    llvm::ConstantExpr::getBitCast(GV, SBP),
425    llvm::ConstantExpr::getBitCast(annoGV, SBP),
426    llvm::ConstantExpr::getBitCast(unitGV, SBP),
427    llvm::ConstantInt::get(llvm::Type::Int32Ty, LineNo)
428  };
429  return llvm::ConstantStruct::get(Fields, 4, false);
430}
431
432bool CodeGenModule::MayDeferGeneration(const ValueDecl *Global) {
433  // Never defer when EmitAllDecls is specified or the decl has
434  // attribute used.
435  if (Features.EmitAllDecls || Global->hasAttr<UsedAttr>())
436    return false;
437
438  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
439    // Constructors and destructors should never be deferred.
440    if (FD->hasAttr<ConstructorAttr>() || FD->hasAttr<DestructorAttr>())
441      return false;
442
443    // FIXME: What about inline, and/or extern inline?
444    if (FD->getStorageClass() != FunctionDecl::Static)
445      return false;
446  } else {
447    const VarDecl *VD = cast<VarDecl>(Global);
448    assert(VD->isFileVarDecl() && "Invalid decl");
449
450    if (VD->getStorageClass() != VarDecl::Static)
451      return false;
452  }
453
454  return true;
455}
456
457void CodeGenModule::EmitGlobal(const ValueDecl *Global) {
458  // If this is an alias definition (which otherwise looks like a declaration)
459  // emit it now.
460  if (Global->hasAttr<AliasAttr>())
461    return EmitAliasDefinition(Global);
462
463  // Ignore declarations, they will be emitted on their first use.
464  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
465    // Forward declarations are emitted lazily on first use.
466    if (!FD->isThisDeclarationADefinition())
467      return;
468  } else {
469    const VarDecl *VD = cast<VarDecl>(Global);
470    assert(VD->isFileVarDecl() && "Cannot emit local var decl as global.");
471
472    // Forward declarations are emitted lazily on first use.
473    if (!VD->getInit() && VD->hasExternalStorage())
474      return;
475  }
476
477  // Defer code generation when possible if this is a static definition, inline
478  // function etc.  These we only want to emit if they are used.
479  if (MayDeferGeneration(Global)) {
480    // If the value has already been used, add it directly to the
481    // DeferredDeclsToEmit list.
482    const char *MangledName = getMangledName(Global);
483    if (GlobalDeclMap.count(MangledName))
484      DeferredDeclsToEmit.push_back(Global);
485    else {
486      // Otherwise, remember that we saw a deferred decl with this name.  The
487      // first use of the mangled name will cause it to move into
488      // DeferredDeclsToEmit.
489      DeferredDecls[MangledName] = Global;
490    }
491    return;
492  }
493
494  // Otherwise emit the definition.
495  EmitGlobalDefinition(Global);
496}
497
498void CodeGenModule::EmitGlobalDefinition(const ValueDecl *D) {
499  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
500    EmitGlobalFunctionDefinition(FD);
501  } else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
502    EmitGlobalVarDefinition(VD);
503  } else {
504    assert(0 && "Invalid argument to EmitGlobalDefinition()");
505  }
506}
507
508/// GetOrCreateLLVMFunction - If the specified mangled name is not in the
509/// module, create and return an llvm Function with the specified type. If there
510/// is something in the module with the specified name, return it potentially
511/// bitcasted to the right type.
512///
513/// If D is non-null, it specifies a decl that correspond to this.  This is used
514/// to set the attributes on the function when it is first created.
515llvm::Constant *CodeGenModule::GetOrCreateLLVMFunction(const char *MangledName,
516                                                       const llvm::Type *Ty,
517                                                       const FunctionDecl *D) {
518  // Lookup the entry, lazily creating it if necessary.
519  llvm::GlobalValue *&Entry = GlobalDeclMap[MangledName];
520  if (Entry) {
521    if (Entry->getType()->getElementType() == Ty)
522      return Entry;
523
524    // Make sure the result is of the correct type.
525    const llvm::Type *PTy = llvm::PointerType::getUnqual(Ty);
526    return llvm::ConstantExpr::getBitCast(Entry, PTy);
527  }
528
529  // This is the first use or definition of a mangled name.  If there is a
530  // deferred decl with this name, remember that we need to emit it at the end
531  // of the file.
532  llvm::DenseMap<const char*, const ValueDecl*>::iterator DDI =
533  DeferredDecls.find(MangledName);
534  if (DDI != DeferredDecls.end()) {
535    // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
536    // list, and remove it from DeferredDecls (since we don't need it anymore).
537    DeferredDeclsToEmit.push_back(DDI->second);
538    DeferredDecls.erase(DDI);
539  }
540
541  // This function doesn't have a complete type (for example, the return
542  // type is an incomplete struct). Use a fake type instead, and make
543  // sure not to try to set attributes.
544  bool ShouldSetAttributes = true;
545  if (!isa<llvm::FunctionType>(Ty)) {
546    Ty = llvm::FunctionType::get(llvm::Type::VoidTy,
547                                 std::vector<const llvm::Type*>(), false);
548    ShouldSetAttributes = false;
549  }
550  llvm::Function *F = llvm::Function::Create(cast<llvm::FunctionType>(Ty),
551                                             llvm::Function::ExternalLinkage,
552                                             "", &getModule());
553  F->setName(MangledName);
554  if (D && ShouldSetAttributes)
555    SetFunctionAttributes(D, F);
556  Entry = F;
557  return F;
558}
559
560/// GetAddrOfFunction - Return the address of the given function.  If Ty is
561/// non-null, then this function will use the specified type if it has to
562/// create it (this occurs when we see a definition of the function).
563llvm::Constant *CodeGenModule::GetAddrOfFunction(const FunctionDecl *D,
564                                                 const llvm::Type *Ty) {
565  // If there was no specific requested type, just convert it now.
566  if (!Ty)
567    Ty = getTypes().ConvertType(D->getType());
568  return GetOrCreateLLVMFunction(getMangledName(D), Ty, D);
569}
570
571/// CreateRuntimeFunction - Create a new runtime function with the specified
572/// type and name.
573llvm::Constant *
574CodeGenModule::CreateRuntimeFunction(const llvm::FunctionType *FTy,
575                                     const char *Name) {
576  // Convert Name to be a uniqued string from the IdentifierInfo table.
577  Name = getContext().Idents.get(Name).getName();
578  return GetOrCreateLLVMFunction(Name, FTy, 0);
579}
580
581/// GetOrCreateLLVMGlobal - If the specified mangled name is not in the module,
582/// create and return an llvm GlobalVariable with the specified type.  If there
583/// is something in the module with the specified name, return it potentially
584/// bitcasted to the right type.
585///
586/// If D is non-null, it specifies a decl that correspond to this.  This is used
587/// to set the attributes on the global when it is first created.
588llvm::Constant *CodeGenModule::GetOrCreateLLVMGlobal(const char *MangledName,
589                                                     const llvm::PointerType*Ty,
590                                                     const VarDecl *D) {
591  // Lookup the entry, lazily creating it if necessary.
592  llvm::GlobalValue *&Entry = GlobalDeclMap[MangledName];
593  if (Entry) {
594    if (Entry->getType() == Ty)
595      return Entry;
596
597    // Make sure the result is of the correct type.
598    return llvm::ConstantExpr::getBitCast(Entry, Ty);
599  }
600
601  // We don't support __thread yet.
602  if (D && D->isThreadSpecified())
603    ErrorUnsupported(D, "thread local ('__thread') variable", true);
604
605  // This is the first use or definition of a mangled name.  If there is a
606  // deferred decl with this name, remember that we need to emit it at the end
607  // of the file.
608  llvm::DenseMap<const char*, const ValueDecl*>::iterator DDI =
609    DeferredDecls.find(MangledName);
610  if (DDI != DeferredDecls.end()) {
611    // Move the potentially referenced deferred decl to the DeferredDeclsToEmit
612    // list, and remove it from DeferredDecls (since we don't need it anymore).
613    DeferredDeclsToEmit.push_back(DDI->second);
614    DeferredDecls.erase(DDI);
615  }
616
617  llvm::GlobalVariable *GV =
618    new llvm::GlobalVariable(Ty->getElementType(), false,
619                             llvm::GlobalValue::ExternalLinkage,
620                             0, "", &getModule(),
621                             0, Ty->getAddressSpace());
622  GV->setName(MangledName);
623
624  // Handle things which are present even on external declarations.
625  if (D) {
626    // FIXME: This code is overly simple and should be merged with
627    // other global handling.
628    GV->setConstant(D->getType().isConstant(Context));
629
630    // FIXME: Merge with other attribute handling code.
631    if (D->getStorageClass() == VarDecl::PrivateExtern)
632      GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
633
634    if (D->hasAttr<WeakAttr>() || D->hasAttr<WeakImportAttr>())
635      GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
636  }
637
638  return Entry = GV;
639}
640
641
642/// GetAddrOfGlobalVar - Return the llvm::Constant for the address of the
643/// given global variable.  If Ty is non-null and if the global doesn't exist,
644/// then it will be greated with the specified type instead of whatever the
645/// normal requested type would be.
646llvm::Constant *CodeGenModule::GetAddrOfGlobalVar(const VarDecl *D,
647                                                  const llvm::Type *Ty) {
648  assert(D->hasGlobalStorage() && "Not a global variable");
649  QualType ASTTy = D->getType();
650  if (Ty == 0)
651    Ty = getTypes().ConvertTypeForMem(ASTTy);
652
653  const llvm::PointerType *PTy =
654    llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
655  return GetOrCreateLLVMGlobal(getMangledName(D), PTy, D);
656}
657
658/// CreateRuntimeVariable - Create a new runtime global variable with the
659/// specified type and name.
660llvm::Constant *
661CodeGenModule::CreateRuntimeVariable(const llvm::Type *Ty,
662                                     const char *Name) {
663  // Convert Name to be a uniqued string from the IdentifierInfo table.
664  Name = getContext().Idents.get(Name).getName();
665  return GetOrCreateLLVMGlobal(Name, llvm::PointerType::getUnqual(Ty), 0);
666}
667
668void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
669  llvm::Constant *Init = 0;
670  QualType ASTTy = D->getType();
671
672  if (D->getInit() == 0) {
673    // This is a tentative definition; tentative definitions are
674    // implicitly initialized with { 0 }
675    const llvm::Type *InitTy = getTypes().ConvertTypeForMem(ASTTy);
676    if (ASTTy->isIncompleteArrayType()) {
677      // An incomplete array is normally [ TYPE x 0 ], but we need
678      // to fix it to [ TYPE x 1 ].
679      const llvm::ArrayType* ATy = cast<llvm::ArrayType>(InitTy);
680      InitTy = llvm::ArrayType::get(ATy->getElementType(), 1);
681    }
682    Init = llvm::Constant::getNullValue(InitTy);
683  } else {
684    Init = EmitConstantExpr(D->getInit(), D->getType());
685    if (!Init) {
686      ErrorUnsupported(D, "static initializer");
687      QualType T = D->getInit()->getType();
688      Init = llvm::UndefValue::get(getTypes().ConvertType(T));
689    }
690  }
691
692  const llvm::Type* InitType = Init->getType();
693  llvm::Constant *Entry = GetAddrOfGlobalVar(D, InitType);
694
695  // Strip off a bitcast if we got one back.
696  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
697    assert(CE->getOpcode() == llvm::Instruction::BitCast);
698    Entry = CE->getOperand(0);
699  }
700
701  // Entry is now either a Function or GlobalVariable.
702  llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Entry);
703
704  // If we already have this global and it has an initializer, then
705  // we are in the rare situation where we emitted the defining
706  // declaration of the global and are now being asked to emit a
707  // definition which would be common. This occurs, for example, in
708  // the following situation because statics can be emitted out of
709  // order:
710  //
711  //  static int x;
712  //  static int *y = &x;
713  //  static int x = 10;
714  //  int **z = &y;
715  //
716  // Bail here so we don't blow away the definition. Note that if we
717  // can't distinguish here if we emitted a definition with a null
718  // initializer, but this case is safe.
719  if (GV && GV->hasInitializer() && !GV->getInitializer()->isNullValue()) {
720    assert(!D->getInit() && "Emitting multiple definitions of a decl!");
721    return;
722  }
723
724  // We have a definition after a declaration with the wrong type.
725  // We must make a new GlobalVariable* and update everything that used OldGV
726  // (a declaration or tentative definition) with the new GlobalVariable*
727  // (which will be a definition).
728  //
729  // This happens if there is a prototype for a global (e.g.
730  // "extern int x[];") and then a definition of a different type (e.g.
731  // "int x[10];"). This also happens when an initializer has a different type
732  // from the type of the global (this happens with unions).
733  if (GV == 0 ||
734      GV->getType()->getElementType() != InitType ||
735      GV->getType()->getAddressSpace() != ASTTy.getAddressSpace()) {
736
737    // Remove the old entry from GlobalDeclMap so that we'll create a new one.
738    GlobalDeclMap.erase(getMangledName(D));
739
740    // Make a new global with the correct type, this is now guaranteed to work.
741    GV = cast<llvm::GlobalVariable>(GetAddrOfGlobalVar(D, InitType));
742    GV->takeName(cast<llvm::GlobalValue>(Entry));
743
744    // Replace all uses of the old global with the new global
745    llvm::Constant *NewPtrForOldDecl =
746        llvm::ConstantExpr::getBitCast(GV, Entry->getType());
747    Entry->replaceAllUsesWith(NewPtrForOldDecl);
748
749    // Erase the old global, since it is no longer used.
750    cast<llvm::GlobalValue>(Entry)->eraseFromParent();
751  }
752
753  if (const AnnotateAttr *AA = D->getAttr<AnnotateAttr>()) {
754    SourceManager &SM = Context.getSourceManager();
755    AddAnnotation(EmitAnnotateAttr(GV, AA,
756                              SM.getInstantiationLineNumber(D->getLocation())));
757  }
758
759  GV->setInitializer(Init);
760  GV->setConstant(D->getType().isConstant(Context));
761  GV->setAlignment(getContext().getDeclAlignInBytes(D));
762
763  // Set the llvm linkage type as appropriate.
764  if (D->getStorageClass() == VarDecl::Static)
765    GV->setLinkage(llvm::Function::InternalLinkage);
766  else if (D->hasAttr<DLLImportAttr>())
767    GV->setLinkage(llvm::Function::DLLImportLinkage);
768  else if (D->hasAttr<DLLExportAttr>())
769    GV->setLinkage(llvm::Function::DLLExportLinkage);
770  else if (D->hasAttr<WeakAttr>() || D->hasAttr<WeakImportAttr>())
771    GV->setLinkage(llvm::GlobalVariable::WeakAnyLinkage);
772  else if (!CompileOpts.NoCommon &&
773           (!D->hasExternalStorage() && !D->getInit()))
774    GV->setLinkage(llvm::GlobalVariable::CommonLinkage);
775  else
776    GV->setLinkage(llvm::GlobalVariable::ExternalLinkage);
777
778  setGlobalVisibility(GV, D);
779
780  if (D->hasAttr<UsedAttr>())
781    AddUsedGlobal(GV);
782
783  if (const SectionAttr *SA = D->getAttr<SectionAttr>())
784    GV->setSection(SA->getName());
785
786  // Emit global variable debug information.
787  if (CGDebugInfo *DI = getDebugInfo()) {
788    DI->setLocation(D->getLocation());
789    DI->EmitGlobalVariable(GV, D);
790  }
791}
792
793
794void CodeGenModule::EmitGlobalFunctionDefinition(const FunctionDecl *D) {
795  const llvm::FunctionType *Ty;
796
797  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D)) {
798    bool isVariadic = D->getType()->getAsFunctionProtoType()->isVariadic();
799
800    Ty = getTypes().GetFunctionType(getTypes().getFunctionInfo(MD), isVariadic);
801  } else {
802    Ty = cast<llvm::FunctionType>(getTypes().ConvertType(D->getType()));
803
804    // As a special case, make sure that definitions of K&R function
805    // "type foo()" aren't declared as varargs (which forces the backend
806    // to do unnecessary work).
807    if (D->getType()->isFunctionNoProtoType()) {
808      assert(Ty->isVarArg() && "Didn't lower type as expected");
809      // Due to stret, the lowered function could have arguments.
810      // Just create the same type as was lowered by ConvertType
811      // but strip off the varargs bit.
812      std::vector<const llvm::Type*> Args(Ty->param_begin(), Ty->param_end());
813      Ty = llvm::FunctionType::get(Ty->getReturnType(), Args, false);
814    }
815  }
816
817  // Get or create the prototype for teh function.
818  llvm::Constant *Entry = GetAddrOfFunction(D, Ty);
819
820  // Strip off a bitcast if we got one back.
821  if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
822    assert(CE->getOpcode() == llvm::Instruction::BitCast);
823    Entry = CE->getOperand(0);
824  }
825
826
827  if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() != Ty) {
828    // If the types mismatch then we have to rewrite the definition.
829    assert(cast<llvm::GlobalValue>(Entry)->isDeclaration() &&
830           "Shouldn't replace non-declaration");
831
832    // F is the Function* for the one with the wrong type, we must make a new
833    // Function* and update everything that used F (a declaration) with the new
834    // Function* (which will be a definition).
835    //
836    // This happens if there is a prototype for a function
837    // (e.g. "int f()") and then a definition of a different type
838    // (e.g. "int f(int x)").  Start by making a new function of the
839    // correct type, RAUW, then steal the name.
840    GlobalDeclMap.erase(getMangledName(D));
841    llvm::Function *NewFn = cast<llvm::Function>(GetAddrOfFunction(D, Ty));
842    NewFn->takeName(cast<llvm::GlobalValue>(Entry));
843
844    // Replace uses of F with the Function we will endow with a body.
845    llvm::Constant *NewPtrForOldDecl =
846      llvm::ConstantExpr::getBitCast(NewFn, Entry->getType());
847    Entry->replaceAllUsesWith(NewPtrForOldDecl);
848
849    // Ok, delete the old function now, which is dead.
850    cast<llvm::GlobalValue>(Entry)->eraseFromParent();
851
852    Entry = NewFn;
853  }
854
855  llvm::Function *Fn = cast<llvm::Function>(Entry);
856
857  CodeGenFunction(*this).GenerateCode(D, Fn);
858
859  SetFunctionAttributesForDefinition(D, Fn);
860
861  if (const ConstructorAttr *CA = D->getAttr<ConstructorAttr>())
862    AddGlobalCtor(Fn, CA->getPriority());
863  if (const DestructorAttr *DA = D->getAttr<DestructorAttr>())
864    AddGlobalDtor(Fn, DA->getPriority());
865}
866
867void CodeGenModule::EmitAliasDefinition(const ValueDecl *D) {
868  const AliasAttr *AA = D->getAttr<AliasAttr>();
869  assert(AA && "Not an alias?");
870
871  const llvm::Type *DeclTy = getTypes().ConvertTypeForMem(D->getType());
872
873  // Unique the name through the identifier table.
874  const char *AliaseeName = AA->getAliasee().c_str();
875  AliaseeName = getContext().Idents.get(AliaseeName).getName();
876
877  // Create a reference to the named value.  This ensures that it is emitted
878  // if a deferred decl.
879  llvm::Constant *Aliasee;
880  if (isa<llvm::FunctionType>(DeclTy))
881    Aliasee = GetOrCreateLLVMFunction(AliaseeName, DeclTy, 0);
882  else
883    Aliasee = GetOrCreateLLVMGlobal(AliaseeName,
884                                    llvm::PointerType::getUnqual(DeclTy), 0);
885
886  // Create the new alias itself, but don't set a name yet.
887  llvm::GlobalValue *GA =
888    new llvm::GlobalAlias(Aliasee->getType(),
889                          llvm::Function::ExternalLinkage,
890                          "", Aliasee, &getModule());
891
892  // See if there is already something with the alias' name in the module.
893  const char *MangledName = getMangledName(D);
894  llvm::GlobalValue *&Entry = GlobalDeclMap[MangledName];
895
896  if (Entry && !Entry->isDeclaration()) {
897    // If there is a definition in the module, then it wins over the alias.
898    // This is dubious, but allow it to be safe.  Just ignore the alias.
899    GA->eraseFromParent();
900    return;
901  }
902
903  if (Entry) {
904    // If there is a declaration in the module, then we had an extern followed
905    // by the alias, as in:
906    //   extern int test6();
907    //   ...
908    //   int test6() __attribute__((alias("test7")));
909    //
910    // Remove it and replace uses of it with the alias.
911
912    Entry->replaceAllUsesWith(llvm::ConstantExpr::getBitCast(GA,
913                                                          Entry->getType()));
914    Entry->eraseFromParent();
915  }
916
917  // Now we know that there is no conflict, set the name.
918  Entry = GA;
919  GA->setName(MangledName);
920
921  // Alias should never be internal or inline.
922  SetGlobalValueAttributes(D, false, false, GA, true);
923}
924
925/// getBuiltinLibFunction - Given a builtin id for a function like
926/// "__builtin_fabsf", return a Function* for "fabsf".
927llvm::Value *CodeGenModule::getBuiltinLibFunction(unsigned BuiltinID) {
928  assert((Context.BuiltinInfo.isLibFunction(BuiltinID) ||
929          Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) &&
930         "isn't a lib fn");
931
932  // Get the name, skip over the __builtin_ prefix (if necessary).
933  const char *Name = Context.BuiltinInfo.GetName(BuiltinID);
934  if (Context.BuiltinInfo.isLibFunction(BuiltinID))
935    Name += 10;
936
937  // Get the type for the builtin.
938  Builtin::Context::GetBuiltinTypeError Error;
939  QualType Type = Context.BuiltinInfo.GetBuiltinType(BuiltinID, Context, Error);
940  assert(Error == Builtin::Context::GE_None && "Can't get builtin type");
941
942  const llvm::FunctionType *Ty =
943    cast<llvm::FunctionType>(getTypes().ConvertType(Type));
944
945  // Unique the name through the identifier table.
946  Name = getContext().Idents.get(Name).getName();
947  // FIXME: param attributes for sext/zext etc.
948  return GetOrCreateLLVMFunction(Name, Ty, 0);
949}
950
951llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,const llvm::Type **Tys,
952                                            unsigned NumTys) {
953  return llvm::Intrinsic::getDeclaration(&getModule(),
954                                         (llvm::Intrinsic::ID)IID, Tys, NumTys);
955}
956
957llvm::Function *CodeGenModule::getMemCpyFn() {
958  if (MemCpyFn) return MemCpyFn;
959  const llvm::Type *IntPtr = TheTargetData.getIntPtrType();
960  return MemCpyFn = getIntrinsic(llvm::Intrinsic::memcpy, &IntPtr, 1);
961}
962
963llvm::Function *CodeGenModule::getMemMoveFn() {
964  if (MemMoveFn) return MemMoveFn;
965  const llvm::Type *IntPtr = TheTargetData.getIntPtrType();
966  return MemMoveFn = getIntrinsic(llvm::Intrinsic::memmove, &IntPtr, 1);
967}
968
969llvm::Function *CodeGenModule::getMemSetFn() {
970  if (MemSetFn) return MemSetFn;
971  const llvm::Type *IntPtr = TheTargetData.getIntPtrType();
972  return MemSetFn = getIntrinsic(llvm::Intrinsic::memset, &IntPtr, 1);
973}
974
975static void appendFieldAndPadding(CodeGenModule &CGM,
976                                  std::vector<llvm::Constant*>& Fields,
977                                  FieldDecl *FieldD, FieldDecl *NextFieldD,
978                                  llvm::Constant* Field,
979                                  RecordDecl* RD, const llvm::StructType *STy) {
980  // Append the field.
981  Fields.push_back(Field);
982
983  int StructFieldNo = CGM.getTypes().getLLVMFieldNo(FieldD);
984
985  int NextStructFieldNo;
986  if (!NextFieldD) {
987    NextStructFieldNo = STy->getNumElements();
988  } else {
989    NextStructFieldNo = CGM.getTypes().getLLVMFieldNo(NextFieldD);
990  }
991
992  // Append padding
993  for (int i = StructFieldNo + 1; i < NextStructFieldNo; i++) {
994    llvm::Constant *C =
995      llvm::Constant::getNullValue(STy->getElementType(StructFieldNo + 1));
996
997    Fields.push_back(C);
998  }
999}
1000
1001llvm::Constant *CodeGenModule::
1002GetAddrOfConstantCFString(const StringLiteral *Literal) {
1003  std::string str;
1004  unsigned StringLength;
1005
1006  bool isUTF16 = false;
1007  if (Literal->containsNonAsciiOrNull()) {
1008    // Convert from UTF-8 to UTF-16.
1009    llvm::SmallVector<UTF16, 128> ToBuf(Literal->getByteLength());
1010    const UTF8 *FromPtr = (UTF8 *)Literal->getStrData();
1011    UTF16 *ToPtr = &ToBuf[0];
1012
1013    ConversionResult Result;
1014    Result = ConvertUTF8toUTF16(&FromPtr, FromPtr+Literal->getByteLength(),
1015                                &ToPtr, ToPtr+Literal->getByteLength(),
1016                                strictConversion);
1017    if (Result == conversionOK) {
1018      // FIXME: Storing UTF-16 in a C string is a hack to test Unicode strings
1019      // without doing more surgery to this routine. Since we aren't explicitly
1020      // checking for endianness here, it's also a bug (when generating code for
1021      // a target that doesn't match the host endianness). Modeling this as an
1022      // i16 array is likely the cleanest solution.
1023      StringLength = ToPtr-&ToBuf[0];
1024      str.assign((char *)&ToBuf[0], StringLength*2);// Twice as many UTF8 chars.
1025      isUTF16 = true;
1026    } else if (Result == sourceIllegal) {
1027      // FIXME: Have Sema::CheckObjCString() validate the UTF-8 string.
1028      str.assign(Literal->getStrData(), Literal->getByteLength());
1029      StringLength = str.length();
1030    } else
1031      assert(Result == conversionOK && "UTF-8 to UTF-16 conversion failed");
1032
1033  } else {
1034    str.assign(Literal->getStrData(), Literal->getByteLength());
1035    StringLength = str.length();
1036  }
1037  llvm::StringMapEntry<llvm::Constant *> &Entry =
1038    CFConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
1039
1040  if (llvm::Constant *C = Entry.getValue())
1041    return C;
1042
1043  llvm::Constant *Zero = llvm::Constant::getNullValue(llvm::Type::Int32Ty);
1044  llvm::Constant *Zeros[] = { Zero, Zero };
1045
1046  if (!CFConstantStringClassRef) {
1047    const llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
1048    Ty = llvm::ArrayType::get(Ty, 0);
1049
1050    // FIXME: This is fairly broken if
1051    // __CFConstantStringClassReference is already defined, in that it
1052    // will get renamed and the user will most likely see an opaque
1053    // error message. This is a general issue with relying on
1054    // particular names.
1055    llvm::GlobalVariable *GV =
1056      new llvm::GlobalVariable(Ty, false,
1057                               llvm::GlobalVariable::ExternalLinkage, 0,
1058                               "__CFConstantStringClassReference",
1059                               &getModule());
1060
1061    // Decay array -> ptr
1062    CFConstantStringClassRef =
1063      llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
1064  }
1065
1066  QualType CFTy = getContext().getCFConstantStringType();
1067  RecordDecl *CFRD = CFTy->getAsRecordType()->getDecl();
1068
1069  const llvm::StructType *STy =
1070    cast<llvm::StructType>(getTypes().ConvertType(CFTy));
1071
1072  std::vector<llvm::Constant*> Fields;
1073  RecordDecl::field_iterator Field = CFRD->field_begin(getContext());
1074
1075  // Class pointer.
1076  FieldDecl *CurField = *Field++;
1077  FieldDecl *NextField = *Field++;
1078  appendFieldAndPadding(*this, Fields, CurField, NextField,
1079                        CFConstantStringClassRef, CFRD, STy);
1080
1081  // Flags.
1082  CurField = NextField;
1083  NextField = *Field++;
1084  const llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
1085  appendFieldAndPadding(*this, Fields, CurField, NextField,
1086                        isUTF16 ? llvm::ConstantInt::get(Ty, 0x07d0)
1087                                : llvm::ConstantInt::get(Ty, 0x07C8),
1088                        CFRD, STy);
1089
1090  // String pointer.
1091  CurField = NextField;
1092  NextField = *Field++;
1093  llvm::Constant *C = llvm::ConstantArray::get(str);
1094
1095  const char *Sect, *Prefix;
1096  bool isConstant;
1097  if (isUTF16) {
1098    Prefix = getContext().Target.getUnicodeStringSymbolPrefix();
1099    Sect = getContext().Target.getUnicodeStringSection();
1100    // FIXME: Why does GCC not set constant here?
1101    isConstant = false;
1102  } else {
1103    Prefix = getContext().Target.getStringSymbolPrefix(true);
1104    Sect = getContext().Target.getCFStringDataSection();
1105    // FIXME: -fwritable-strings should probably affect this, but we
1106    // are following gcc here.
1107    isConstant = true;
1108  }
1109  llvm::GlobalVariable *GV =
1110    new llvm::GlobalVariable(C->getType(), isConstant,
1111                             llvm::GlobalValue::InternalLinkage,
1112                             C, Prefix, &getModule());
1113  if (Sect)
1114    GV->setSection(Sect);
1115  if (isUTF16) {
1116    unsigned Align = getContext().getTypeAlign(getContext().ShortTy)/8;
1117    GV->setAlignment(Align);
1118  }
1119  appendFieldAndPadding(*this, Fields, CurField, NextField,
1120                        llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2),
1121                        CFRD, STy);
1122
1123  // String length.
1124  CurField = NextField;
1125  NextField = 0;
1126  Ty = getTypes().ConvertType(getContext().LongTy);
1127  appendFieldAndPadding(*this, Fields, CurField, NextField,
1128                        llvm::ConstantInt::get(Ty, StringLength), CFRD, STy);
1129
1130  // The struct.
1131  C = llvm::ConstantStruct::get(STy, Fields);
1132  GV = new llvm::GlobalVariable(C->getType(), true,
1133                                llvm::GlobalVariable::InternalLinkage, C,
1134                                getContext().Target.getCFStringSymbolPrefix(),
1135                                &getModule());
1136  if (const char *Sect = getContext().Target.getCFStringSection())
1137    GV->setSection(Sect);
1138  Entry.setValue(GV);
1139
1140  return GV;
1141}
1142
1143/// GetStringForStringLiteral - Return the appropriate bytes for a
1144/// string literal, properly padded to match the literal type.
1145std::string CodeGenModule::GetStringForStringLiteral(const StringLiteral *E) {
1146  const char *StrData = E->getStrData();
1147  unsigned Len = E->getByteLength();
1148
1149  const ConstantArrayType *CAT =
1150    getContext().getAsConstantArrayType(E->getType());
1151  assert(CAT && "String isn't pointer or array!");
1152
1153  // Resize the string to the right size.
1154  std::string Str(StrData, StrData+Len);
1155  uint64_t RealLen = CAT->getSize().getZExtValue();
1156
1157  if (E->isWide())
1158    RealLen *= getContext().Target.getWCharWidth()/8;
1159
1160  Str.resize(RealLen, '\0');
1161
1162  return Str;
1163}
1164
1165/// GetAddrOfConstantStringFromLiteral - Return a pointer to a
1166/// constant array for the given string literal.
1167llvm::Constant *
1168CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
1169  // FIXME: This can be more efficient.
1170  return GetAddrOfConstantString(GetStringForStringLiteral(S));
1171}
1172
1173/// GetAddrOfConstantStringFromObjCEncode - Return a pointer to a constant
1174/// array for the given ObjCEncodeExpr node.
1175llvm::Constant *
1176CodeGenModule::GetAddrOfConstantStringFromObjCEncode(const ObjCEncodeExpr *E) {
1177  std::string Str;
1178  getContext().getObjCEncodingForType(E->getEncodedType(), Str);
1179
1180  return GetAddrOfConstantCString(Str);
1181}
1182
1183
1184/// GenerateWritableString -- Creates storage for a string literal.
1185static llvm::Constant *GenerateStringLiteral(const std::string &str,
1186                                             bool constant,
1187                                             CodeGenModule &CGM,
1188                                             const char *GlobalName) {
1189  // Create Constant for this string literal. Don't add a '\0'.
1190  llvm::Constant *C = llvm::ConstantArray::get(str, false);
1191
1192  // Create a global variable for this string
1193  return new llvm::GlobalVariable(C->getType(), constant,
1194                                  llvm::GlobalValue::InternalLinkage,
1195                                  C, GlobalName, &CGM.getModule());
1196}
1197
1198/// GetAddrOfConstantString - Returns a pointer to a character array
1199/// containing the literal. This contents are exactly that of the
1200/// given string, i.e. it will not be null terminated automatically;
1201/// see GetAddrOfConstantCString. Note that whether the result is
1202/// actually a pointer to an LLVM constant depends on
1203/// Feature.WriteableStrings.
1204///
1205/// The result has pointer to array type.
1206llvm::Constant *CodeGenModule::GetAddrOfConstantString(const std::string &str,
1207                                                       const char *GlobalName) {
1208  bool IsConstant = !Features.WritableStrings;
1209
1210  // Get the default prefix if a name wasn't specified.
1211  if (!GlobalName)
1212    GlobalName = getContext().Target.getStringSymbolPrefix(IsConstant);
1213
1214  // Don't share any string literals if strings aren't constant.
1215  if (!IsConstant)
1216    return GenerateStringLiteral(str, false, *this, GlobalName);
1217
1218  llvm::StringMapEntry<llvm::Constant *> &Entry =
1219  ConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
1220
1221  if (Entry.getValue())
1222    return Entry.getValue();
1223
1224  // Create a global variable for this.
1225  llvm::Constant *C = GenerateStringLiteral(str, true, *this, GlobalName);
1226  Entry.setValue(C);
1227  return C;
1228}
1229
1230/// GetAddrOfConstantCString - Returns a pointer to a character
1231/// array containing the literal and a terminating '\-'
1232/// character. The result has pointer to array type.
1233llvm::Constant *CodeGenModule::GetAddrOfConstantCString(const std::string &str,
1234                                                        const char *GlobalName){
1235  return GetAddrOfConstantString(str + '\0', GlobalName);
1236}
1237
1238/// EmitObjCPropertyImplementations - Emit information for synthesized
1239/// properties for an implementation.
1240void CodeGenModule::EmitObjCPropertyImplementations(const
1241                                                    ObjCImplementationDecl *D) {
1242  for (ObjCImplementationDecl::propimpl_iterator i = D->propimpl_begin(),
1243         e = D->propimpl_end(); i != e; ++i) {
1244    ObjCPropertyImplDecl *PID = *i;
1245
1246    // Dynamic is just for type-checking.
1247    if (PID->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize) {
1248      ObjCPropertyDecl *PD = PID->getPropertyDecl();
1249
1250      // Determine which methods need to be implemented, some may have
1251      // been overridden. Note that ::isSynthesized is not the method
1252      // we want, that just indicates if the decl came from a
1253      // property. What we want to know is if the method is defined in
1254      // this implementation.
1255      if (!D->getInstanceMethod(PD->getGetterName()))
1256        CodeGenFunction(*this).GenerateObjCGetter(
1257                                 const_cast<ObjCImplementationDecl *>(D), PID);
1258      if (!PD->isReadOnly() &&
1259          !D->getInstanceMethod(PD->getSetterName()))
1260        CodeGenFunction(*this).GenerateObjCSetter(
1261                                 const_cast<ObjCImplementationDecl *>(D), PID);
1262    }
1263  }
1264}
1265
1266/// EmitNamespace - Emit all declarations in a namespace.
1267void CodeGenModule::EmitNamespace(const NamespaceDecl *ND) {
1268  for (RecordDecl::decl_iterator I = ND->decls_begin(getContext()),
1269         E = ND->decls_end(getContext());
1270       I != E; ++I)
1271    EmitTopLevelDecl(*I);
1272}
1273
1274// EmitLinkageSpec - Emit all declarations in a linkage spec.
1275void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
1276  if (LSD->getLanguage() != LinkageSpecDecl::lang_c) {
1277    ErrorUnsupported(LSD, "linkage spec");
1278    return;
1279  }
1280
1281  for (RecordDecl::decl_iterator I = LSD->decls_begin(getContext()),
1282         E = LSD->decls_end(getContext());
1283       I != E; ++I)
1284    EmitTopLevelDecl(*I);
1285}
1286
1287/// EmitTopLevelDecl - Emit code for a single top level declaration.
1288void CodeGenModule::EmitTopLevelDecl(Decl *D) {
1289  // If an error has occurred, stop code generation, but continue
1290  // parsing and semantic analysis (to ensure all warnings and errors
1291  // are emitted).
1292  if (Diags.hasErrorOccurred())
1293    return;
1294
1295  switch (D->getKind()) {
1296  case Decl::CXXMethod:
1297  case Decl::Function:
1298  case Decl::Var:
1299    EmitGlobal(cast<ValueDecl>(D));
1300    break;
1301
1302  case Decl::Namespace:
1303    EmitNamespace(cast<NamespaceDecl>(D));
1304    break;
1305
1306    // Objective-C Decls
1307
1308  // Forward declarations, no (immediate) code generation.
1309  case Decl::ObjCClass:
1310  case Decl::ObjCForwardProtocol:
1311  case Decl::ObjCCategory:
1312    break;
1313  case Decl::ObjCInterface:
1314    // If we already laid out this interface due to an @class, and if we
1315    // codegen'd a reference it, update the 'opaque' type to be a real type now.
1316    Types.UpdateCompletedType(cast<ObjCInterfaceDecl>(D));
1317    break;
1318
1319  case Decl::ObjCProtocol:
1320    Runtime->GenerateProtocol(cast<ObjCProtocolDecl>(D));
1321    break;
1322
1323  case Decl::ObjCCategoryImpl:
1324    // Categories have properties but don't support synthesize so we
1325    // can ignore them here.
1326    Runtime->GenerateCategory(cast<ObjCCategoryImplDecl>(D));
1327    break;
1328
1329  case Decl::ObjCImplementation: {
1330    ObjCImplementationDecl *OMD = cast<ObjCImplementationDecl>(D);
1331    EmitObjCPropertyImplementations(OMD);
1332    Runtime->GenerateClass(OMD);
1333    break;
1334  }
1335  case Decl::ObjCMethod: {
1336    ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(D);
1337    // If this is not a prototype, emit the body.
1338    if (OMD->getBody())
1339      CodeGenFunction(*this).GenerateObjCMethod(OMD);
1340    break;
1341  }
1342  case Decl::ObjCCompatibleAlias:
1343    // compatibility-alias is a directive and has no code gen.
1344    break;
1345
1346  case Decl::LinkageSpec:
1347    EmitLinkageSpec(cast<LinkageSpecDecl>(D));
1348    break;
1349
1350  case Decl::FileScopeAsm: {
1351    FileScopeAsmDecl *AD = cast<FileScopeAsmDecl>(D);
1352    std::string AsmString(AD->getAsmString()->getStrData(),
1353                          AD->getAsmString()->getByteLength());
1354
1355    const std::string &S = getModule().getModuleInlineAsm();
1356    if (S.empty())
1357      getModule().setModuleInlineAsm(AsmString);
1358    else
1359      getModule().setModuleInlineAsm(S + '\n' + AsmString);
1360    break;
1361  }
1362
1363  default:
1364    // Make sure we handled everything we should, every other kind is
1365    // a non-top-level decl.  FIXME: Would be nice to have an
1366    // isTopLevelDeclKind function. Need to recode Decl::Kind to do
1367    // that easily.
1368    assert(isa<TypeDecl>(D) && "Unsupported decl kind");
1369  }
1370}
1371