CodeGenModule.cpp revision 761d7f78e2dac7ea5f35828c2271e60d91e106ce 
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 "clang/AST/ASTContext.h"
20#include "clang/AST/DeclObjC.h"
21#include "clang/Basic/Diagnostic.h"
22#include "clang/Basic/SourceManager.h"
23#include "clang/Basic/TargetInfo.h"
24#include "llvm/CallingConv.h"
25#include "llvm/Module.h"
26#include "llvm/Intrinsics.h"
27#include "llvm/Target/TargetData.h"
28#include "llvm/Analysis/Verifier.h"
29using namespace clang;
30using namespace CodeGen;
31
32
33CodeGenModule::CodeGenModule(ASTContext &C, const LangOptions &LO,
34                             llvm::Module &M, const llvm::TargetData &TD,
35                             Diagnostic &diags, bool GenerateDebugInfo)
36  : Context(C), Features(LO), TheModule(M), TheTargetData(TD), Diags(diags),
37    Types(C, M, TD), Runtime(0), MemCpyFn(0), MemMoveFn(0), MemSetFn(0),
38    CFConstantStringClassRef(0) {
39
40  if (Features.ObjC1) {
41    if (Features.NeXTRuntime) {
42      Runtime = CreateMacObjCRuntime(*this);
43    } else {
44      Runtime = CreateGNUObjCRuntime(*this);
45    }
46  }
47
48  // If debug info generation is enabled, create the CGDebugInfo object.
49  DebugInfo = GenerateDebugInfo ? new CGDebugInfo(this) : 0;
50}
51
52CodeGenModule::~CodeGenModule() {
53  delete Runtime;
54  delete DebugInfo;
55}
56
57void CodeGenModule::Release() {
58  EmitStatics();
59  EmitAliases();
60  if (Runtime)
61    if (llvm::Function *ObjCInitFunction = Runtime->ModuleInitFunction())
62      AddGlobalCtor(ObjCInitFunction);
63  EmitCtorList(GlobalCtors, "llvm.global_ctors");
64  EmitCtorList(GlobalDtors, "llvm.global_dtors");
65  EmitAnnotations();
66  // Run the verifier to check that the generated code is consistent.
67  if (verifyModule(TheModule, llvm::PrintMessageAction)) {
68    TheModule.dump();
69    assert(0 && "Module failed verification!");
70  }
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 codegen this %0 yet");
81  SourceRange Range = S->getSourceRange();
82  std::string Msg = Type;
83  getDiags().Report(Context.getFullLoc(S->getLocStart()), DiagID,
84                    &Msg, 1, &Range, 1);
85}
86
87/// ErrorUnsupported - Print out an error that codegen doesn't support the
88/// specified decl yet.
89void CodeGenModule::ErrorUnsupported(const Decl *D, const char *Type,
90                                     bool OmitOnError) {
91  if (OmitOnError && getDiags().hasErrorOccurred())
92    return;
93  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Error,
94                                               "cannot codegen this %0 yet");
95  std::string Msg = Type;
96  getDiags().Report(Context.getFullLoc(D->getLocation()), DiagID,
97                    &Msg, 1);
98}
99
100/// setGlobalVisibility - Set the visibility for the given LLVM
101/// GlobalValue according to the given clang AST visibility value.
102static void setGlobalVisibility(llvm::GlobalValue *GV,
103                                VisibilityAttr::VisibilityTypes Vis) {
104  switch (Vis) {
105  default: assert(0 && "Unknown visibility!");
106  case VisibilityAttr::DefaultVisibility:
107    GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
108    break;
109  case VisibilityAttr::HiddenVisibility:
110    GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
111    break;
112  case VisibilityAttr::ProtectedVisibility:
113    GV->setVisibility(llvm::GlobalValue::ProtectedVisibility);
114    break;
115  }
116}
117
118/// AddGlobalCtor - Add a function to the list that will be called before
119/// main() runs.
120void CodeGenModule::AddGlobalCtor(llvm::Function * Ctor, int Priority) {
121  // TODO: Type coercion of void()* types.
122  GlobalCtors.push_back(std::make_pair(Ctor, Priority));
123}
124
125/// AddGlobalDtor - Add a function to the list that will be called
126/// when the module is unloaded.
127void CodeGenModule::AddGlobalDtor(llvm::Function * Dtor, int Priority) {
128  // TODO: Type coercion of void()* types.
129  GlobalDtors.push_back(std::make_pair(Dtor, Priority));
130}
131
132void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
133  // Ctor function type is void()*.
134  llvm::FunctionType* CtorFTy =
135    llvm::FunctionType::get(llvm::Type::VoidTy,
136                            std::vector<const llvm::Type*>(),
137                            false);
138  llvm::Type *CtorPFTy = llvm::PointerType::getUnqual(CtorFTy);
139
140  // Get the type of a ctor entry, { i32, void ()* }.
141  llvm::StructType* CtorStructTy =
142    llvm::StructType::get(llvm::Type::Int32Ty,
143                          llvm::PointerType::getUnqual(CtorFTy), NULL);
144
145  // Construct the constructor and destructor arrays.
146  std::vector<llvm::Constant*> Ctors;
147  for (CtorList::const_iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
148    std::vector<llvm::Constant*> S;
149    S.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, I->second, false));
150    S.push_back(llvm::ConstantExpr::getBitCast(I->first, CtorPFTy));
151    Ctors.push_back(llvm::ConstantStruct::get(CtorStructTy, S));
152  }
153
154  if (!Ctors.empty()) {
155    llvm::ArrayType *AT = llvm::ArrayType::get(CtorStructTy, Ctors.size());
156    new llvm::GlobalVariable(AT, false,
157                             llvm::GlobalValue::AppendingLinkage,
158                             llvm::ConstantArray::get(AT, Ctors),
159                             GlobalName,
160                             &TheModule);
161  }
162}
163
164void CodeGenModule::EmitAnnotations() {
165  if (Annotations.empty())
166    return;
167
168  // Create a new global variable for the ConstantStruct in the Module.
169  llvm::Constant *Array =
170  llvm::ConstantArray::get(llvm::ArrayType::get(Annotations[0]->getType(),
171                                                Annotations.size()),
172                           Annotations);
173  llvm::GlobalValue *gv =
174  new llvm::GlobalVariable(Array->getType(), false,
175                           llvm::GlobalValue::AppendingLinkage, Array,
176                           "llvm.global.annotations", &TheModule);
177  gv->setSection("llvm.metadata");
178}
179
180static void SetGlobalValueAttributes(const Decl *D,
181                                     bool IsInternal,
182                                     bool IsInline,
183                                     llvm::GlobalValue *GV,
184                                     bool ForDefinition) {
185  // TODO: Set up linkage and many other things.  Note, this is a simple
186  // approximation of what we really want.
187  if (!ForDefinition) {
188    // Only a few attributes are set on declarations.
189    if (D->getAttr<DLLImportAttr>())
190      GV->setLinkage(llvm::Function::DLLImportLinkage);
191  } else {
192    if (IsInternal) {
193      GV->setLinkage(llvm::Function::InternalLinkage);
194    } else {
195      if (D->getAttr<DLLImportAttr>())
196        GV->setLinkage(llvm::Function::DLLImportLinkage);
197      else if (D->getAttr<DLLExportAttr>())
198        GV->setLinkage(llvm::Function::DLLExportLinkage);
199      else if (D->getAttr<WeakAttr>() || IsInline)
200        GV->setLinkage(llvm::Function::WeakLinkage);
201    }
202  }
203
204  if (const VisibilityAttr *attr = D->getAttr<VisibilityAttr>())
205    setGlobalVisibility(GV, attr->getVisibility());
206  // FIXME: else handle -fvisibility
207
208  if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
209    // Prefaced with special LLVM marker to indicate that the name
210    // should not be munged.
211    GV->setName("\01" + ALA->getLabel());
212  }
213}
214
215void CodeGenModule::SetFunctionAttributes(const Decl *D,
216                                          const CGFunctionInfo &Info,
217                                          llvm::Function *F) {
218  AttributeListType AttributeList;
219  ConstructAttributeList(D, Info.argtypes_begin(), Info.argtypes_end(),
220                         AttributeList);
221
222  F->setAttributes(llvm::AttrListPtr::get(AttributeList.begin(),
223                                        AttributeList.size()));
224
225  // Set the appropriate calling convention for the Function.
226  if (D->getAttr<FastCallAttr>())
227    F->setCallingConv(llvm::CallingConv::Fast);
228}
229
230/// SetFunctionAttributesForDefinition - Set function attributes
231/// specific to a function definition.
232void CodeGenModule::SetFunctionAttributesForDefinition(const Decl *D,
233                                                       llvm::Function *F) {
234  if (isa<ObjCMethodDecl>(D)) {
235    SetGlobalValueAttributes(D, true, false, F, true);
236  } else {
237    const FunctionDecl *FD = cast<FunctionDecl>(D);
238    SetGlobalValueAttributes(FD, FD->getStorageClass() == FunctionDecl::Static,
239                             FD->isInline(), F, true);
240  }
241
242  if (!Features.Exceptions)
243    F->addAttribute(0, llvm::Attribute::NoUnwind);
244}
245
246void CodeGenModule::SetMethodAttributes(const ObjCMethodDecl *MD,
247                                        llvm::Function *F) {
248  SetFunctionAttributes(MD, CGFunctionInfo(MD, Context), F);
249
250  SetFunctionAttributesForDefinition(MD, F);
251}
252
253void CodeGenModule::SetFunctionAttributes(const FunctionDecl *FD,
254                                          llvm::Function *F) {
255  SetFunctionAttributes(FD, CGFunctionInfo(FD), F);
256
257  SetGlobalValueAttributes(FD, FD->getStorageClass() == FunctionDecl::Static,
258                           FD->isInline(), F, false);
259}
260
261
262void CodeGenModule::EmitAliases() {
263  for (unsigned i = 0, e = Aliases.size(); i != e; ++i) {
264    const FunctionDecl *D = Aliases[i];
265    const AliasAttr *AA = D->getAttr<AliasAttr>();
266
267    // This is something of a hack, if the FunctionDecl got overridden
268    // then its attributes will be moved to the new declaration. In
269    // this case the current decl has no alias attribute, but we will
270    // eventually see it.
271    if (!AA)
272      continue;
273
274    const std::string& aliaseeName = AA->getAliasee();
275    llvm::Function *aliasee = getModule().getFunction(aliaseeName);
276    if (!aliasee) {
277      // FIXME: This isn't unsupported, this is just an error, which
278      // sema should catch, but...
279      ErrorUnsupported(D, "alias referencing a missing function");
280      continue;
281    }
282
283    llvm::GlobalValue *GA =
284      new llvm::GlobalAlias(aliasee->getType(),
285                            llvm::Function::ExternalLinkage,
286                            D->getName(),
287                            aliasee,
288                            &getModule());
289
290    llvm::GlobalValue *&Entry = GlobalDeclMap[D->getIdentifier()];
291    if (Entry) {
292      // If we created a dummy function for this then replace it.
293      GA->takeName(Entry);
294
295      llvm::Value *Casted =
296        llvm::ConstantExpr::getBitCast(GA, Entry->getType());
297      Entry->replaceAllUsesWith(Casted);
298      Entry->eraseFromParent();
299
300      Entry = GA;
301    }
302
303    // Alias should never be internal or inline.
304    SetGlobalValueAttributes(D, false, false, GA, true);
305  }
306}
307
308void CodeGenModule::EmitStatics() {
309  // Emit code for each used static decl encountered.  Since a previously unused
310  // static decl may become used during the generation of code for a static
311  // function, iterate until no changes are made.
312  bool Changed;
313  do {
314    Changed = false;
315    for (unsigned i = 0, e = StaticDecls.size(); i != e; ++i) {
316      const ValueDecl *D = StaticDecls[i];
317
318      // Check if we have used a decl with the same name
319      // FIXME: The AST should have some sort of aggregate decls or
320      // global symbol map.
321      // FIXME: This is missing some important cases. For example, we
322      // need to check for uses in an alias and in a constructor.
323      if (!GlobalDeclMap.count(D->getIdentifier()))
324        continue;
325
326      // Emit the definition.
327      EmitGlobalDefinition(D);
328
329      // Erase the used decl from the list.
330      StaticDecls[i] = StaticDecls.back();
331      StaticDecls.pop_back();
332      --i;
333      --e;
334
335      // Remember that we made a change.
336      Changed = true;
337    }
338  } while (Changed);
339}
340
341/// EmitAnnotateAttr - Generate the llvm::ConstantStruct which contains the
342/// annotation information for a given GlobalValue.  The annotation struct is
343/// {i8 *, i8 *, i8 *, i32}.  The first field is a constant expression, the
344/// GlobalValue being annotated.  The second field is the constant string
345/// created from the AnnotateAttr's annotation.  The third field is a constant
346/// string containing the name of the translation unit.  The fourth field is
347/// the line number in the file of the annotated value declaration.
348///
349/// FIXME: this does not unique the annotation string constants, as llvm-gcc
350///        appears to.
351///
352llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
353                                                const AnnotateAttr *AA,
354                                                unsigned LineNo) {
355  llvm::Module *M = &getModule();
356
357  // get [N x i8] constants for the annotation string, and the filename string
358  // which are the 2nd and 3rd elements of the global annotation structure.
359  const llvm::Type *SBP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
360  llvm::Constant *anno = llvm::ConstantArray::get(AA->getAnnotation(), true);
361  llvm::Constant *unit = llvm::ConstantArray::get(M->getModuleIdentifier(),
362                                                  true);
363
364  // Get the two global values corresponding to the ConstantArrays we just
365  // created to hold the bytes of the strings.
366  llvm::GlobalValue *annoGV =
367  new llvm::GlobalVariable(anno->getType(), false,
368                           llvm::GlobalValue::InternalLinkage, anno,
369                           GV->getName() + ".str", M);
370  // translation unit name string, emitted into the llvm.metadata section.
371  llvm::GlobalValue *unitGV =
372  new llvm::GlobalVariable(unit->getType(), false,
373                           llvm::GlobalValue::InternalLinkage, unit, ".str", M);
374
375  // Create the ConstantStruct that is the global annotion.
376  llvm::Constant *Fields[4] = {
377    llvm::ConstantExpr::getBitCast(GV, SBP),
378    llvm::ConstantExpr::getBitCast(annoGV, SBP),
379    llvm::ConstantExpr::getBitCast(unitGV, SBP),
380    llvm::ConstantInt::get(llvm::Type::Int32Ty, LineNo)
381  };
382  return llvm::ConstantStruct::get(Fields, 4, false);
383}
384
385void CodeGenModule::EmitGlobal(const ValueDecl *Global) {
386  bool isDef, isStatic;
387
388  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Global)) {
389    // Aliases are deferred until code for everything else has been
390    // emitted.
391    if (FD->getAttr<AliasAttr>()) {
392      assert(!FD->isThisDeclarationADefinition() &&
393             "Function alias cannot have a definition!");
394      Aliases.push_back(FD);
395      return;
396    }
397
398    isDef = FD->isThisDeclarationADefinition();
399    isStatic = FD->getStorageClass() == FunctionDecl::Static;
400  } else if (const VarDecl *VD = cast<VarDecl>(Global)) {
401    assert(VD->isFileVarDecl() && "Cannot emit local var decl as global.");
402
403    isDef = !(VD->getStorageClass() == VarDecl::Extern && VD->getInit() == 0);
404    isStatic = VD->getStorageClass() == VarDecl::Static;
405  } else {
406    assert(0 && "Invalid argument to EmitGlobal");
407    return;
408  }
409
410  // Forward declarations are emitted lazily on first use.
411  if (!isDef)
412    return;
413
414  // If the global is a static, defer code generation until later so
415  // we can easily omit unused statics.
416  if (isStatic) {
417    StaticDecls.push_back(Global);
418    return;
419  }
420
421  // Otherwise emit the definition.
422  EmitGlobalDefinition(Global);
423}
424
425void CodeGenModule::EmitGlobalDefinition(const ValueDecl *D) {
426  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
427    EmitGlobalFunctionDefinition(FD);
428  } else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
429    EmitGlobalVarDefinition(VD);
430  } else {
431    assert(0 && "Invalid argument to EmitGlobalDefinition()");
432  }
433}
434
435 llvm::Constant *CodeGenModule::GetAddrOfGlobalVar(const VarDecl *D) {
436  assert(D->hasGlobalStorage() && "Not a global variable");
437
438  QualType ASTTy = D->getType();
439  const llvm::Type *Ty = getTypes().ConvertTypeForMem(ASTTy);
440  const llvm::Type *PTy = llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
441
442  // Lookup the entry, lazily creating it if necessary.
443  llvm::GlobalValue *&Entry = GlobalDeclMap[D->getIdentifier()];
444  if (!Entry)
445    Entry = new llvm::GlobalVariable(Ty, false,
446                                     llvm::GlobalValue::ExternalLinkage,
447                                     0, D->getName(), &getModule(), 0,
448                                     ASTTy.getAddressSpace());
449
450  // Make sure the result is of the correct type.
451  return llvm::ConstantExpr::getBitCast(Entry, PTy);
452}
453
454void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
455  llvm::Constant *Init = 0;
456  QualType ASTTy = D->getType();
457  const llvm::Type *VarTy = getTypes().ConvertTypeForMem(ASTTy);
458
459  if (D->getInit() == 0) {
460    // This is a tentative definition; tentative definitions are
461    // implicitly initialized with { 0 }
462    const llvm::Type* InitTy;
463    if (ASTTy->isIncompleteArrayType()) {
464      // An incomplete array is normally [ TYPE x 0 ], but we need
465      // to fix it to [ TYPE x 1 ].
466      const llvm::ArrayType* ATy = cast<llvm::ArrayType>(VarTy);
467      InitTy = llvm::ArrayType::get(ATy->getElementType(), 1);
468    } else {
469      InitTy = VarTy;
470    }
471    Init = llvm::Constant::getNullValue(InitTy);
472  } else {
473    Init = EmitConstantExpr(D->getInit());
474  }
475  const llvm::Type* InitType = Init->getType();
476
477  llvm::GlobalValue *&Entry = GlobalDeclMap[D->getIdentifier()];
478  llvm::GlobalVariable *GV = cast_or_null<llvm::GlobalVariable>(Entry);
479
480  if (!GV) {
481    GV = new llvm::GlobalVariable(InitType, false,
482                                  llvm::GlobalValue::ExternalLinkage,
483                                  0, D->getName(), &getModule(), 0,
484                                  ASTTy.getAddressSpace());
485  } else if (GV->getType() !=
486             llvm::PointerType::get(InitType, ASTTy.getAddressSpace())) {
487    // We have a definition after a prototype with the wrong type.
488    // We must make a new GlobalVariable* and update everything that used OldGV
489    // (a declaration or tentative definition) with the new GlobalVariable*
490    // (which will be a definition).
491    //
492    // This happens if there is a prototype for a global (e.g. "extern int x[];")
493    // and then a definition of a different type (e.g. "int x[10];"). This also
494    // happens when an initializer has a different type from the type of the
495    // global (this happens with unions).
496    //
497    // FIXME: This also ends up happening if there's a definition followed by
498    // a tentative definition!  (Although Sema rejects that construct
499    // at the moment.)
500
501    // Save the old global
502    llvm::GlobalVariable *OldGV = GV;
503
504    // Make a new global with the correct type
505    GV = new llvm::GlobalVariable(InitType, false,
506                                  llvm::GlobalValue::ExternalLinkage,
507                                  0, D->getName(), &getModule(), 0,
508                                  ASTTy.getAddressSpace());
509    // Steal the name of the old global
510    GV->takeName(OldGV);
511
512    // Replace all uses of the old global with the new global
513    llvm::Constant *NewPtrForOldDecl =
514        llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
515    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
516
517    // Erase the old global, since it is no longer used.
518    OldGV->eraseFromParent();
519  }
520
521  Entry = GV;
522
523  if (const AnnotateAttr *AA = D->getAttr<AnnotateAttr>()) {
524    SourceManager &SM = Context.getSourceManager();
525    AddAnnotation(EmitAnnotateAttr(GV, AA,
526                                   SM.getLogicalLineNumber(D->getLocation())));
527  }
528
529  GV->setInitializer(Init);
530  GV->setConstant(D->getType().isConstant(Context));
531
532  // FIXME: This is silly; getTypeAlign should just work for incomplete arrays
533  unsigned Align;
534  if (const IncompleteArrayType* IAT =
535        Context.getAsIncompleteArrayType(D->getType()))
536    Align = Context.getTypeAlign(IAT->getElementType());
537  else
538    Align = Context.getTypeAlign(D->getType());
539  if (const AlignedAttr* AA = D->getAttr<AlignedAttr>()) {
540    Align = std::max(Align, AA->getAlignment());
541  }
542  GV->setAlignment(Align / 8);
543
544  if (const VisibilityAttr *attr = D->getAttr<VisibilityAttr>())
545    setGlobalVisibility(GV, attr->getVisibility());
546  // FIXME: else handle -fvisibility
547
548  if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
549    // Prefaced with special LLVM marker to indicate that the name
550    // should not be munged.
551    GV->setName("\01" + ALA->getLabel());
552  }
553
554  // Set the llvm linkage type as appropriate.
555  if (D->getStorageClass() == VarDecl::Static)
556    GV->setLinkage(llvm::Function::InternalLinkage);
557  else if (D->getAttr<DLLImportAttr>())
558    GV->setLinkage(llvm::Function::DLLImportLinkage);
559  else if (D->getAttr<DLLExportAttr>())
560    GV->setLinkage(llvm::Function::DLLExportLinkage);
561  else if (D->getAttr<WeakAttr>())
562    GV->setLinkage(llvm::GlobalVariable::WeakLinkage);
563  else {
564    // FIXME: This isn't right.  This should handle common linkage and other
565    // stuff.
566    switch (D->getStorageClass()) {
567    case VarDecl::Static: assert(0 && "This case handled above");
568    case VarDecl::Auto:
569    case VarDecl::Register:
570      assert(0 && "Can't have auto or register globals");
571    case VarDecl::None:
572      if (!D->getInit())
573        GV->setLinkage(llvm::GlobalVariable::CommonLinkage);
574      break;
575    case VarDecl::Extern:
576    case VarDecl::PrivateExtern:
577      // todo: common
578      break;
579    }
580  }
581
582  // Emit global variable debug information.
583  CGDebugInfo *DI = getDebugInfo();
584  if(DI) {
585    if(D->getLocation().isValid())
586      DI->setLocation(D->getLocation());
587    DI->EmitGlobalVariable(GV, D);
588  }
589}
590
591llvm::GlobalValue *
592CodeGenModule::EmitForwardFunctionDefinition(const FunctionDecl *D) {
593  const llvm::Type *Ty = getTypes().ConvertType(D->getType());
594  llvm::Function *F = llvm::Function::Create(cast<llvm::FunctionType>(Ty),
595                                             llvm::Function::ExternalLinkage,
596                                             D->getName(), &getModule());
597  SetFunctionAttributes(D, F);
598  return F;
599}
600
601llvm::Constant *CodeGenModule::GetAddrOfFunction(const FunctionDecl *D) {
602  QualType ASTTy = D->getType();
603  const llvm::Type *Ty = getTypes().ConvertTypeForMem(ASTTy);
604  const llvm::Type *PTy = llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
605
606  // Lookup the entry, lazily creating it if necessary.
607  llvm::GlobalValue *&Entry = GlobalDeclMap[D->getIdentifier()];
608  if (!Entry)
609    Entry = EmitForwardFunctionDefinition(D);
610
611  return llvm::ConstantExpr::getBitCast(Entry, PTy);
612}
613
614void CodeGenModule::EmitGlobalFunctionDefinition(const FunctionDecl *D) {
615  llvm::GlobalValue *&Entry = GlobalDeclMap[D->getIdentifier()];
616  if (!Entry) {
617    Entry = EmitForwardFunctionDefinition(D);
618  } else {
619    // If the types mismatch then we have to rewrite the definition.
620    const llvm::Type *Ty = getTypes().ConvertType(D->getType());
621    if (Entry->getType() != llvm::PointerType::getUnqual(Ty)) {
622      // Otherwise, we have a definition after a prototype with the wrong type.
623      // F is the Function* for the one with the wrong type, we must make a new
624      // Function* and update everything that used F (a declaration) with the new
625      // Function* (which will be a definition).
626      //
627      // This happens if there is a prototype for a function (e.g. "int f()") and
628      // then a definition of a different type (e.g. "int f(int x)").  Start by
629      // making a new function of the correct type, RAUW, then steal the name.
630      llvm::GlobalValue *NewFn = EmitForwardFunctionDefinition(D);
631      NewFn->takeName(Entry);
632
633      // Replace uses of F with the Function we will endow with a body.
634      llvm::Constant *NewPtrForOldDecl =
635        llvm::ConstantExpr::getBitCast(NewFn, Entry->getType());
636      Entry->replaceAllUsesWith(NewPtrForOldDecl);
637
638      // Ok, delete the old function now, which is dead.
639      assert(Entry->isDeclaration() && "Shouldn't replace non-declaration");
640      Entry->eraseFromParent();
641
642      Entry = NewFn;
643    }
644  }
645
646  llvm::Function *Fn = cast<llvm::Function>(Entry);
647  CodeGenFunction(*this).GenerateCode(D, Fn);
648
649  SetFunctionAttributesForDefinition(D, Fn);
650
651  if (const ConstructorAttr *CA = D->getAttr<ConstructorAttr>()) {
652    AddGlobalCtor(Fn, CA->getPriority());
653  } else if (const DestructorAttr *DA = D->getAttr<DestructorAttr>()) {
654    AddGlobalDtor(Fn, DA->getPriority());
655  }
656}
657
658void CodeGenModule::UpdateCompletedType(const TagDecl *TD) {
659  // Make sure that this type is translated.
660  Types.UpdateCompletedType(TD);
661}
662
663
664/// getBuiltinLibFunction
665llvm::Function *CodeGenModule::getBuiltinLibFunction(unsigned BuiltinID) {
666  if (BuiltinID > BuiltinFunctions.size())
667    BuiltinFunctions.resize(BuiltinID);
668
669  // Cache looked up functions.  Since builtin id #0 is invalid we don't reserve
670  // a slot for it.
671  assert(BuiltinID && "Invalid Builtin ID");
672  llvm::Function *&FunctionSlot = BuiltinFunctions[BuiltinID-1];
673  if (FunctionSlot)
674    return FunctionSlot;
675
676  assert(Context.BuiltinInfo.isLibFunction(BuiltinID) && "isn't a lib fn");
677
678  // Get the name, skip over the __builtin_ prefix.
679  const char *Name = Context.BuiltinInfo.GetName(BuiltinID)+10;
680
681  // Get the type for the builtin.
682  QualType Type = Context.BuiltinInfo.GetBuiltinType(BuiltinID, Context);
683  const llvm::FunctionType *Ty =
684    cast<llvm::FunctionType>(getTypes().ConvertType(Type));
685
686  // FIXME: This has a serious problem with code like this:
687  //  void abs() {}
688  //    ... __builtin_abs(x);
689  // The two versions of abs will collide.  The fix is for the builtin to win,
690  // and for the existing one to be turned into a constantexpr cast of the
691  // builtin.  In the case where the existing one is a static function, it
692  // should just be renamed.
693  if (llvm::Function *Existing = getModule().getFunction(Name)) {
694    if (Existing->getFunctionType() == Ty && Existing->hasExternalLinkage())
695      return FunctionSlot = Existing;
696    assert(Existing == 0 && "FIXME: Name collision");
697  }
698
699  // FIXME: param attributes for sext/zext etc.
700  return FunctionSlot =
701    llvm::Function::Create(Ty, llvm::Function::ExternalLinkage, Name,
702                           &getModule());
703}
704
705llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,const llvm::Type **Tys,
706                                            unsigned NumTys) {
707  return llvm::Intrinsic::getDeclaration(&getModule(),
708                                         (llvm::Intrinsic::ID)IID, Tys, NumTys);
709}
710
711llvm::Function *CodeGenModule::getMemCpyFn() {
712  if (MemCpyFn) return MemCpyFn;
713  llvm::Intrinsic::ID IID;
714  switch (Context.Target.getPointerWidth(0)) {
715  default: assert(0 && "Unknown ptr width");
716  case 32: IID = llvm::Intrinsic::memcpy_i32; break;
717  case 64: IID = llvm::Intrinsic::memcpy_i64; break;
718  }
719  return MemCpyFn = getIntrinsic(IID);
720}
721
722llvm::Function *CodeGenModule::getMemMoveFn() {
723  if (MemMoveFn) return MemMoveFn;
724  llvm::Intrinsic::ID IID;
725  switch (Context.Target.getPointerWidth(0)) {
726  default: assert(0 && "Unknown ptr width");
727  case 32: IID = llvm::Intrinsic::memmove_i32; break;
728  case 64: IID = llvm::Intrinsic::memmove_i64; break;
729  }
730  return MemMoveFn = getIntrinsic(IID);
731}
732
733llvm::Function *CodeGenModule::getMemSetFn() {
734  if (MemSetFn) return MemSetFn;
735  llvm::Intrinsic::ID IID;
736  switch (Context.Target.getPointerWidth(0)) {
737  default: assert(0 && "Unknown ptr width");
738  case 32: IID = llvm::Intrinsic::memset_i32; break;
739  case 64: IID = llvm::Intrinsic::memset_i64; break;
740  }
741  return MemSetFn = getIntrinsic(IID);
742}
743
744// We still need to work out the details of handling UTF-16.
745// See: <rdr://2996215>
746llvm::Constant *CodeGenModule::
747GetAddrOfConstantCFString(const std::string &str) {
748  llvm::StringMapEntry<llvm::Constant *> &Entry =
749    CFConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
750
751  if (Entry.getValue())
752    return Entry.getValue();
753
754  llvm::Constant *Zero = llvm::Constant::getNullValue(llvm::Type::Int32Ty);
755  llvm::Constant *Zeros[] = { Zero, Zero };
756
757  if (!CFConstantStringClassRef) {
758    const llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
759    Ty = llvm::ArrayType::get(Ty, 0);
760
761    // FIXME: This is fairly broken if
762    // __CFConstantStringClassReference is already defined, in that it
763    // will get renamed and the user will most likely see an opaque
764    // error message. This is a general issue with relying on
765    // particular names.
766    llvm::GlobalVariable *GV =
767      new llvm::GlobalVariable(Ty, false,
768                               llvm::GlobalVariable::ExternalLinkage, 0,
769                               "__CFConstantStringClassReference",
770                               &getModule());
771
772    // Decay array -> ptr
773    CFConstantStringClassRef =
774      llvm::ConstantExpr::getGetElementPtr(GV, Zeros, 2);
775  }
776
777  std::vector<llvm::Constant*> Fields(4);
778
779  // Class pointer.
780  Fields[0] = CFConstantStringClassRef;
781
782  // Flags.
783  const llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
784  Fields[1] = llvm::ConstantInt::get(Ty, 0x07C8);
785
786  // String pointer.
787  llvm::Constant *C = llvm::ConstantArray::get(str);
788  C = new llvm::GlobalVariable(C->getType(), true,
789                               llvm::GlobalValue::InternalLinkage,
790                               C, ".str", &getModule());
791  Fields[2] = llvm::ConstantExpr::getGetElementPtr(C, Zeros, 2);
792
793  // String length.
794  Ty = getTypes().ConvertType(getContext().LongTy);
795  Fields[3] = llvm::ConstantInt::get(Ty, str.length());
796
797  // The struct.
798  Ty = getTypes().ConvertType(getContext().getCFConstantStringType());
799  C = llvm::ConstantStruct::get(cast<llvm::StructType>(Ty), Fields);
800  llvm::GlobalVariable *GV =
801    new llvm::GlobalVariable(C->getType(), true,
802                             llvm::GlobalVariable::InternalLinkage,
803                             C, "", &getModule());
804
805  GV->setSection("__DATA,__cfstring");
806  Entry.setValue(GV);
807
808  return GV;
809}
810
811/// GetStringForStringLiteral - Return the appropriate bytes for a
812/// string literal, properly padded to match the literal type.
813std::string CodeGenModule::GetStringForStringLiteral(const StringLiteral *E) {
814  if (E->isWide()) {
815    ErrorUnsupported(E, "wide string");
816    return "FIXME";
817  }
818
819  const char *StrData = E->getStrData();
820  unsigned Len = E->getByteLength();
821
822  const ConstantArrayType *CAT =
823    getContext().getAsConstantArrayType(E->getType());
824  assert(CAT && "String isn't pointer or array!");
825
826  // Resize the string to the right size
827  // FIXME: What about wchar_t strings?
828  std::string Str(StrData, StrData+Len);
829  uint64_t RealLen = CAT->getSize().getZExtValue();
830  Str.resize(RealLen, '\0');
831
832  return Str;
833}
834
835/// GetAddrOfConstantStringFromLiteral - Return a pointer to a
836/// constant array for the given string literal.
837llvm::Constant *
838CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
839  // FIXME: This can be more efficient.
840  return GetAddrOfConstantString(GetStringForStringLiteral(S));
841}
842
843/// GenerateWritableString -- Creates storage for a string literal.
844static llvm::Constant *GenerateStringLiteral(const std::string &str,
845                                             bool constant,
846                                             CodeGenModule &CGM) {
847  // Create Constant for this string literal. Don't add a '\0'.
848  llvm::Constant *C = llvm::ConstantArray::get(str, false);
849
850  // Create a global variable for this string
851  C = new llvm::GlobalVariable(C->getType(), constant,
852                               llvm::GlobalValue::InternalLinkage,
853                               C, ".str", &CGM.getModule());
854
855  return C;
856}
857
858/// GetAddrOfConstantString - Returns a pointer to a character array
859/// containing the literal. This contents are exactly that of the
860/// given string, i.e. it will not be null terminated automatically;
861/// see GetAddrOfConstantCString. Note that whether the result is
862/// actually a pointer to an LLVM constant depends on
863/// Feature.WriteableStrings.
864///
865/// The result has pointer to array type.
866llvm::Constant *CodeGenModule::GetAddrOfConstantString(const std::string &str) {
867  // Don't share any string literals if writable-strings is turned on.
868  if (Features.WritableStrings)
869    return GenerateStringLiteral(str, false, *this);
870
871  llvm::StringMapEntry<llvm::Constant *> &Entry =
872  ConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
873
874  if (Entry.getValue())
875      return Entry.getValue();
876
877  // Create a global variable for this.
878  llvm::Constant *C = GenerateStringLiteral(str, true, *this);
879  Entry.setValue(C);
880  return C;
881}
882
883/// GetAddrOfConstantCString - Returns a pointer to a character
884/// array containing the literal and a terminating '\-'
885/// character. The result has pointer to array type.
886llvm::Constant *CodeGenModule::GetAddrOfConstantCString(const std::string &str) {
887  return GetAddrOfConstantString(str + "\0");
888}
889
890/// EmitObjCPropertyImplementations - Emit information for synthesized
891/// properties for an implementation.
892void CodeGenModule::EmitObjCPropertyImplementations(const
893                                                    ObjCImplementationDecl *D) {
894  for (ObjCImplementationDecl::propimpl_iterator i = D->propimpl_begin(),
895         e = D->propimpl_end(); i != e; ++i) {
896    ObjCPropertyImplDecl *PID = *i;
897
898    // Dynamic is just for type-checking.
899    if (PID->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize) {
900      ObjCPropertyDecl *PD = PID->getPropertyDecl();
901
902      // Determine which methods need to be implemented, some may have
903      // been overridden. Note that ::isSynthesized is not the method
904      // we want, that just indicates if the decl came from a
905      // property. What we want to know is if the method is defined in
906      // this implementation.
907      if (!D->getInstanceMethod(PD->getGetterName()))
908        CodeGenFunction(*this).GenerateObjCGetter(PID);
909      if (!PD->isReadOnly() &&
910          !D->getInstanceMethod(PD->getSetterName()))
911        CodeGenFunction(*this).GenerateObjCSetter(PID);
912    }
913  }
914}
915
916/// EmitTopLevelDecl - Emit code for a single top level declaration.
917void CodeGenModule::EmitTopLevelDecl(Decl *D) {
918  // If an error has occurred, stop code generation, but continue
919  // parsing and semantic analysis (to ensure all warnings and errors
920  // are emitted).
921  if (Diags.hasErrorOccurred())
922    return;
923
924  switch (D->getKind()) {
925  case Decl::Function:
926  case Decl::Var:
927    EmitGlobal(cast<ValueDecl>(D));
928    break;
929
930  case Decl::Namespace:
931    ErrorUnsupported(D, "namespace");
932    break;
933
934    // Objective-C Decls
935
936    // Forward declarations, no (immediate) code generation.
937  case Decl::ObjCClass:
938  case Decl::ObjCCategory:
939  case Decl::ObjCForwardProtocol:
940  case Decl::ObjCInterface:
941    break;
942
943  case Decl::ObjCProtocol:
944    Runtime->GenerateProtocol(cast<ObjCProtocolDecl>(D));
945    break;
946
947  case Decl::ObjCCategoryImpl:
948    // Categories have properties but don't support synthesize so we
949    // can ignore them here.
950
951    Runtime->GenerateCategory(cast<ObjCCategoryImplDecl>(D));
952    break;
953
954  case Decl::ObjCImplementation: {
955    ObjCImplementationDecl *OMD = cast<ObjCImplementationDecl>(D);
956    EmitObjCPropertyImplementations(OMD);
957    Runtime->GenerateClass(OMD);
958    break;
959  }
960  case Decl::ObjCMethod: {
961    ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(D);
962    // If this is not a prototype, emit the body.
963    if (OMD->getBody())
964      CodeGenFunction(*this).GenerateObjCMethod(OMD);
965    break;
966  }
967  case Decl::ObjCCompatibleAlias:
968    ErrorUnsupported(D, "Objective-C compatible alias");
969    break;
970
971  case Decl::LinkageSpec: {
972    LinkageSpecDecl *LSD = cast<LinkageSpecDecl>(D);
973    if (LSD->getLanguage() == LinkageSpecDecl::lang_cxx)
974      ErrorUnsupported(LSD, "linkage spec");
975    // FIXME: implement C++ linkage, C linkage works mostly by C
976    // language reuse already.
977    break;
978  }
979
980  case Decl::FileScopeAsm: {
981    FileScopeAsmDecl *AD = cast<FileScopeAsmDecl>(D);
982    std::string AsmString(AD->getAsmString()->getStrData(),
983                          AD->getAsmString()->getByteLength());
984
985    const std::string &S = getModule().getModuleInlineAsm();
986    if (S.empty())
987      getModule().setModuleInlineAsm(AsmString);
988    else
989      getModule().setModuleInlineAsm(S + '\n' + AsmString);
990    break;
991  }
992
993  default:
994    // Make sure we handled everything we should, every other kind is
995    // a non-top-level decl.  FIXME: Would be nice to have an
996    // isTopLevelDeclKind function. Need to recode Decl::Kind to do
997    // that easily.
998    assert(isa<TypeDecl>(D) && "Unsupported decl kind");
999  }
1000}
1001
1002