CodeGenModule.cpp revision dce1406f1c1f572cfd61c494546572d63461c741 
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 "clang/AST/ASTContext.h"
18#include "clang/AST/Decl.h"
19#include "clang/Basic/Diagnostic.h"
20#include "clang/Basic/LangOptions.h"
21#include "clang/Basic/SourceManager.h"
22#include "clang/Basic/TargetInfo.h"
23#include "llvm/CallingConv.h"
24#include "llvm/Constants.h"
25#include "llvm/DerivedTypes.h"
26#include "llvm/Module.h"
27#include "llvm/Intrinsics.h"
28#include "llvm/Target/TargetData.h"
29#include "llvm/Analysis/Verifier.h"
30#include <algorithm>
31using namespace clang;
32using namespace CodeGen;
33
34
35CodeGenModule::CodeGenModule(ASTContext &C, const LangOptions &LO,
36                             llvm::Module &M, const llvm::TargetData &TD,
37                             Diagnostic &diags, bool GenerateDebugInfo)
38  : Context(C), Features(LO), TheModule(M), TheTargetData(TD), Diags(diags),
39    Types(C, M, TD), MemCpyFn(0), MemMoveFn(0), MemSetFn(0),
40    CFConstantStringClassRef(0) {
41  //TODO: Make this selectable at runtime
42  Runtime = CreateObjCRuntime(*this);
43
44  // If debug info generation is enabled, create the CGDebugInfo object.
45  if (GenerateDebugInfo)
46    DebugInfo = new CGDebugInfo(this);
47  else
48    DebugInfo = NULL;
49}
50
51CodeGenModule::~CodeGenModule() {
52  EmitStatics();
53  llvm::Function *ObjCInitFunction = Runtime->ModuleInitFunction();
54  if (ObjCInitFunction)
55    AddGlobalCtor(ObjCInitFunction);
56  EmitGlobalCtors();
57  EmitAnnotations();
58  delete Runtime;
59  delete DebugInfo;
60  // Run the verifier to check that the generated code is consistent.
61  assert(!verifyModule(TheModule));
62}
63
64/// WarnUnsupported - Print out a warning that codegen doesn't support the
65/// specified stmt yet.
66void CodeGenModule::WarnUnsupported(const Stmt *S, const char *Type) {
67  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Warning,
68                                               "cannot codegen this %0 yet");
69  SourceRange Range = S->getSourceRange();
70  std::string Msg = Type;
71  getDiags().Report(Context.getFullLoc(S->getLocStart()), DiagID,
72                    &Msg, 1, &Range, 1);
73}
74
75/// WarnUnsupported - Print out a warning that codegen doesn't support the
76/// specified decl yet.
77void CodeGenModule::WarnUnsupported(const Decl *D, const char *Type) {
78  unsigned DiagID = getDiags().getCustomDiagID(Diagnostic::Warning,
79                                               "cannot codegen this %0 yet");
80  std::string Msg = Type;
81  getDiags().Report(Context.getFullLoc(D->getLocation()), DiagID,
82                    &Msg, 1);
83}
84
85/// setVisibility - Set the visibility for the given LLVM GlobalValue
86/// according to the given clang AST visibility value.
87void CodeGenModule::setVisibility(llvm::GlobalValue *GV,
88                                  VisibilityAttr::VisibilityTypes Vis) {
89  switch (Vis) {
90  default: assert(0 && "Unknown visibility!");
91  case VisibilityAttr::DefaultVisibility:
92    GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
93    break;
94  case VisibilityAttr::HiddenVisibility:
95    GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
96    break;
97  case VisibilityAttr::ProtectedVisibility:
98    GV->setVisibility(llvm::GlobalValue::ProtectedVisibility);
99    break;
100  }
101}
102
103/// AddGlobalCtor - Add a function to the list that will be called before
104/// main() runs.
105void CodeGenModule::AddGlobalCtor(llvm::Function * Ctor) {
106  // TODO: Type coercion of void()* types.
107  GlobalCtors.push_back(Ctor);
108}
109
110/// EmitGlobalCtors - Generates the array of contsturctor functions to be
111/// called on module load, if any have been registered with AddGlobalCtor.
112void CodeGenModule::EmitGlobalCtors() {
113  if (GlobalCtors.empty()) return;
114
115  // Get the type of @llvm.global_ctors
116  std::vector<const llvm::Type*> CtorFields;
117  CtorFields.push_back(llvm::IntegerType::get(32));
118  // Constructor function type
119  std::vector<const llvm::Type*> VoidArgs;
120  llvm::FunctionType* CtorFuncTy =
121    llvm::FunctionType::get(llvm::Type::VoidTy, VoidArgs, false);
122
123  // i32, function type pair
124  const llvm::Type *FPType = llvm::PointerType::getUnqual(CtorFuncTy);
125  llvm::StructType* CtorStructTy =
126  llvm::StructType::get(llvm::Type::Int32Ty, FPType, NULL);
127  // Array of fields
128  llvm::ArrayType* GlobalCtorsTy =
129    llvm::ArrayType::get(CtorStructTy, GlobalCtors.size());
130
131  // Define the global variable
132  llvm::GlobalVariable *GlobalCtorsVal =
133    new llvm::GlobalVariable(GlobalCtorsTy, false,
134                             llvm::GlobalValue::AppendingLinkage,
135                             (llvm::Constant*)0, "llvm.global_ctors",
136                             &TheModule);
137
138  // Populate the array
139  std::vector<llvm::Constant*> CtorValues;
140  llvm::Constant *MagicNumber =
141    llvm::ConstantInt::get(llvm::Type::Int32Ty, 65535, false);
142  std::vector<llvm::Constant*> StructValues;
143  for (std::vector<llvm::Constant*>::iterator I = GlobalCtors.begin(),
144       E = GlobalCtors.end(); I != E; ++I) {
145    StructValues.clear();
146    StructValues.push_back(MagicNumber);
147    StructValues.push_back(*I);
148
149    CtorValues.push_back(llvm::ConstantStruct::get(CtorStructTy, StructValues));
150  }
151
152  GlobalCtorsVal->setInitializer(llvm::ConstantArray::get(GlobalCtorsTy,
153                                                          CtorValues));
154}
155
156
157
158void CodeGenModule::EmitAnnotations() {
159  if (Annotations.empty())
160    return;
161
162  // Create a new global variable for the ConstantStruct in the Module.
163  llvm::Constant *Array =
164  llvm::ConstantArray::get(llvm::ArrayType::get(Annotations[0]->getType(),
165                                                Annotations.size()),
166                           Annotations);
167  llvm::GlobalValue *gv =
168  new llvm::GlobalVariable(Array->getType(), false,
169                           llvm::GlobalValue::AppendingLinkage, Array,
170                           "llvm.global.annotations", &TheModule);
171  gv->setSection("llvm.metadata");
172}
173
174/// ReplaceMapValuesWith - This is a really slow and bad function that
175/// searches for any entries in GlobalDeclMap that point to OldVal, changing
176/// them to point to NewVal.  This is badbadbad, FIXME!
177void CodeGenModule::ReplaceMapValuesWith(llvm::Constant *OldVal,
178                                         llvm::Constant *NewVal) {
179  for (llvm::DenseMap<const Decl*, llvm::Constant*>::iterator
180       I = GlobalDeclMap.begin(), E = GlobalDeclMap.end(); I != E; ++I)
181    if (I->second == OldVal) I->second = NewVal;
182}
183
184bool hasAggregateLLVMType(QualType T) {
185  return !T->isRealType() && !T->isPointerLikeType() &&
186         !T->isVoidType() && !T->isVectorType() && !T->isFunctionType();
187}
188
189void CodeGenModule::SetGlobalValueAttributes(const FunctionDecl *FD,
190                                             llvm::GlobalValue *GV) {
191  // TODO: Set up linkage and many other things.  Note, this is a simple
192  // approximation of what we really want.
193  if (FD->getStorageClass() == FunctionDecl::Static)
194    GV->setLinkage(llvm::Function::InternalLinkage);
195  else if (FD->getAttr<DLLImportAttr>())
196    GV->setLinkage(llvm::Function::DLLImportLinkage);
197  else if (FD->getAttr<DLLExportAttr>())
198    GV->setLinkage(llvm::Function::DLLExportLinkage);
199  else if (FD->getAttr<WeakAttr>() || FD->isInline())
200    GV->setLinkage(llvm::Function::WeakLinkage);
201
202  if (const VisibilityAttr *attr = FD->getAttr<VisibilityAttr>())
203    CodeGenModule::setVisibility(GV, attr->getVisibility());
204  // FIXME: else handle -fvisibility
205}
206
207void CodeGenModule::SetFunctionAttributes(const FunctionDecl *FD,
208                                          llvm::Function *F,
209                                          const llvm::FunctionType *FTy) {
210  unsigned FuncAttrs = 0;
211  if (FD->getAttr<NoThrowAttr>())
212    FuncAttrs |= llvm::ParamAttr::NoUnwind;
213  if (FD->getAttr<NoReturnAttr>())
214    FuncAttrs |= llvm::ParamAttr::NoReturn;
215
216  llvm::SmallVector<llvm::ParamAttrsWithIndex, 8> ParamAttrList;
217  if (FuncAttrs)
218    ParamAttrList.push_back(llvm::ParamAttrsWithIndex::get(0, FuncAttrs));
219  // Note that there is parallel code in CodeGenFunction::EmitCallExpr
220  bool AggregateReturn = hasAggregateLLVMType(FD->getResultType());
221  if (AggregateReturn)
222    ParamAttrList.push_back(
223        llvm::ParamAttrsWithIndex::get(1, llvm::ParamAttr::StructRet));
224  unsigned increment = AggregateReturn ? 2 : 1;
225  const FunctionTypeProto* FTP = dyn_cast<FunctionTypeProto>(FD->getType());
226  if (FTP) {
227    for (unsigned i = 0; i < FTP->getNumArgs(); i++) {
228      QualType ParamType = FTP->getArgType(i);
229      unsigned ParamAttrs = 0;
230      if (ParamType->isRecordType())
231        ParamAttrs |= llvm::ParamAttr::ByVal;
232      if (ParamType->isSignedIntegerType() && ParamType->isPromotableIntegerType())
233        ParamAttrs |= llvm::ParamAttr::SExt;
234      if (ParamType->isUnsignedIntegerType() && ParamType->isPromotableIntegerType())
235        ParamAttrs |= llvm::ParamAttr::ZExt;
236      if (ParamAttrs)
237        ParamAttrList.push_back(llvm::ParamAttrsWithIndex::get(i + increment,
238                                                               ParamAttrs));
239    }
240  }
241
242  F->setParamAttrs(llvm::PAListPtr::get(ParamAttrList.begin(),
243                                        ParamAttrList.size()));
244
245  // Set the appropriate calling convention for the Function.
246  if (FD->getAttr<FastCallAttr>())
247    F->setCallingConv(llvm::CallingConv::Fast);
248
249  SetGlobalValueAttributes(FD, F);
250}
251
252
253
254llvm::Constant *CodeGenModule::GetAddrOfFunctionDecl(const FunctionDecl *D,
255                                                     bool isDefinition) {
256  // See if it is already in the map.  If so, just return it.
257  llvm::Constant *&Entry = GlobalDeclMap[D];
258  if (!isDefinition && Entry) return Entry;
259
260  const llvm::Type *Ty = getTypes().ConvertType(D->getType());
261
262  // Check to see if the function already exists.
263  llvm::Function *F = getModule().getFunction(D->getName());
264  const llvm::FunctionType *FTy = cast<llvm::FunctionType>(Ty);
265
266  // If it doesn't already exist, just create and return an entry.
267  if (F == 0) {
268    // FIXME: param attributes for sext/zext etc.
269    if (D->getBody() || !D->getAttr<AliasAttr>())
270      F = llvm::Function::Create(FTy, llvm::Function::ExternalLinkage,
271                                 D->getName(), &getModule());
272    else {
273      const std::string& aliaseeName = D->getAttr<AliasAttr>()->getAliasee();
274      llvm::Function *aliasee = getModule().getFunction(aliaseeName);
275      llvm::GlobalValue *alias = new llvm::GlobalAlias(aliasee->getType(),
276                                                       llvm::Function::ExternalLinkage,
277                                                       D->getName(),
278                                                       aliasee,
279                                                       &getModule());
280      SetGlobalValueAttributes(D, alias);
281      return Entry = alias;
282    }
283
284    SetFunctionAttributes(D, F, FTy);
285    return Entry = F;
286  }
287
288  // If the pointer type matches, just return it.
289  llvm::Type *PFTy = llvm::PointerType::getUnqual(Ty);
290  if (PFTy == F->getType()) return Entry = F;
291
292  // If this isn't a definition, just return it casted to the right type.
293  if (!isDefinition)
294    return Entry = llvm::ConstantExpr::getBitCast(F, PFTy);
295
296  // Otherwise, we have a definition after a prototype with the wrong type.
297  // F is the Function* for the one with the wrong type, we must make a new
298  // Function* and update everything that used F (a declaration) with the new
299  // Function* (which will be a definition).
300  //
301  // This happens if there is a prototype for a function (e.g. "int f()") and
302  // then a definition of a different type (e.g. "int f(int x)").  Start by
303  // making a new function of the correct type, RAUW, then steal the name.
304  llvm::Function *NewFn = llvm::Function::Create(FTy,
305                                             llvm::Function::ExternalLinkage,
306                                             "", &getModule());
307  NewFn->takeName(F);
308
309  // Replace uses of F with the Function we will endow with a body.
310  llvm::Constant *NewPtrForOldDecl =
311    llvm::ConstantExpr::getBitCast(NewFn, F->getType());
312  F->replaceAllUsesWith(NewPtrForOldDecl);
313
314  // FIXME: Update the globaldeclmap for the previous decl of this name.  We
315  // really want a way to walk all of these, but we don't have it yet.  This
316  // is incredibly slow!
317  ReplaceMapValuesWith(F, NewPtrForOldDecl);
318
319  // Ok, delete the old function now, which is dead.
320  assert(F->isDeclaration() && "Shouldn't replace non-declaration");
321  F->eraseFromParent();
322
323  SetFunctionAttributes(D, NewFn, FTy);
324  // Return the new function which has the right type.
325  return Entry = NewFn;
326}
327
328llvm::Constant *CodeGenModule::GetAddrOfGlobalVar(const VarDecl *D,
329                                                  bool isDefinition) {
330  assert(D->hasGlobalStorage() && "Not a global variable");
331  assert(!isDefinition && "This shouldn't be called for definitions!");
332
333  // See if it is already in the map.
334  llvm::Constant *&Entry = GlobalDeclMap[D];
335  if (Entry) return Entry;
336
337  QualType ASTTy = D->getType();
338  const llvm::Type *Ty = getTypes().ConvertTypeForMem(ASTTy);
339
340  // Check to see if the global already exists.
341  llvm::GlobalVariable *GV = getModule().getGlobalVariable(D->getName(), true);
342
343  // If it doesn't already exist, just create and return an entry.
344  if (GV == 0) {
345    return Entry = new llvm::GlobalVariable(Ty, false,
346                                            llvm::GlobalValue::ExternalLinkage,
347                                            0, D->getName(), &getModule(), 0,
348                                            ASTTy.getAddressSpace());
349  }
350
351  // Otherwise, it already exists; return the existing version
352  llvm::PointerType *PTy = llvm::PointerType::get(Ty, ASTTy.getAddressSpace());
353  return Entry = llvm::ConstantExpr::getBitCast(GV, PTy);
354}
355
356void CodeGenModule::EmitObjCMethod(const ObjCMethodDecl *OMD) {
357  // If this is not a prototype, emit the body.
358  if (OMD->getBody())
359    CodeGenFunction(*this).GenerateObjCMethod(OMD);
360}
361void CodeGenModule::EmitObjCProtocolImplementation(const ObjCProtocolDecl *PD){
362  llvm::SmallVector<std::string, 16> Protocols;
363  for (unsigned i = 0, e = PD->getNumReferencedProtocols() ; i < e ; i++)
364    Protocols.push_back(PD->getReferencedProtocols()[i]->getName());
365  llvm::SmallVector<llvm::Constant*, 16> InstanceMethodNames;
366  llvm::SmallVector<llvm::Constant*, 16> InstanceMethodTypes;
367  for (ObjCProtocolDecl::instmeth_iterator iter = PD->instmeth_begin(),
368      endIter = PD->instmeth_end() ; iter != endIter ; iter++) {
369    std::string TypeStr;
370    Context.getObjCEncodingForMethodDecl((*iter),TypeStr);
371    InstanceMethodNames.push_back(
372        GetAddrOfConstantString((*iter)->getSelector().getName()));
373    InstanceMethodTypes.push_back(GetAddrOfConstantString(TypeStr));
374  }
375  // Collect information about class methods:
376  llvm::SmallVector<llvm::Constant*, 16> ClassMethodNames;
377  llvm::SmallVector<llvm::Constant*, 16> ClassMethodTypes;
378  for (ObjCProtocolDecl::classmeth_iterator iter = PD->classmeth_begin(),
379      endIter = PD->classmeth_end() ; iter != endIter ; iter++) {
380    std::string TypeStr;
381    Context.getObjCEncodingForMethodDecl((*iter),TypeStr);
382    ClassMethodNames.push_back(
383        GetAddrOfConstantString((*iter)->getSelector().getName()));
384    ClassMethodTypes.push_back(GetAddrOfConstantString(TypeStr));
385  }
386  Runtime->GenerateProtocol(PD->getName(), Protocols, InstanceMethodNames,
387      InstanceMethodTypes, ClassMethodNames, ClassMethodTypes);
388}
389
390void CodeGenModule::EmitObjCCategoryImpl(const ObjCCategoryImplDecl *OCD) {
391
392  // Collect information about instance methods
393  llvm::SmallVector<llvm::Constant*, 16> InstanceMethodNames;
394  llvm::SmallVector<llvm::Constant*, 16> InstanceMethodTypes;
395  for (ObjCCategoryDecl::instmeth_iterator iter = OCD->instmeth_begin(),
396      endIter = OCD->instmeth_end() ; iter != endIter ; iter++) {
397    std::string TypeStr;
398    Context.getObjCEncodingForMethodDecl((*iter),TypeStr);
399    InstanceMethodNames.push_back(
400        GetAddrOfConstantString((*iter)->getSelector().getName()));
401    InstanceMethodTypes.push_back(GetAddrOfConstantString(TypeStr));
402  }
403
404  // Collect information about class methods
405  llvm::SmallVector<llvm::Constant*, 16> ClassMethodNames;
406  llvm::SmallVector<llvm::Constant*, 16> ClassMethodTypes;
407  for (ObjCCategoryDecl::classmeth_iterator iter = OCD->classmeth_begin(),
408      endIter = OCD->classmeth_end() ; iter != endIter ; iter++) {
409    std::string TypeStr;
410    Context.getObjCEncodingForMethodDecl((*iter),TypeStr);
411    ClassMethodNames.push_back(
412        GetAddrOfConstantString((*iter)->getSelector().getName()));
413    ClassMethodTypes.push_back(GetAddrOfConstantString(TypeStr));
414  }
415
416  // Collect the names of referenced protocols
417  llvm::SmallVector<std::string, 16> Protocols;
418  ObjCInterfaceDecl * ClassDecl = (ObjCInterfaceDecl*)OCD->getClassInterface();
419  for (unsigned i=0 ; i<ClassDecl->getNumIntfRefProtocols() ; i++)
420    Protocols.push_back(ClassDecl->getReferencedProtocols()[i]->getName());
421
422  // Generate the category
423  Runtime->GenerateCategory(OCD->getClassInterface()->getName(),
424      OCD->getName(), InstanceMethodNames, InstanceMethodTypes,
425      ClassMethodNames, ClassMethodTypes, Protocols);
426}
427
428void CodeGenModule::EmitObjCClassImplementation(
429    const ObjCImplementationDecl *OID) {
430  // Get the superclass name.
431  const ObjCInterfaceDecl * SCDecl = OID->getClassInterface()->getSuperClass();
432  const char * SCName = NULL;
433  if (SCDecl) {
434    SCName = SCDecl->getName();
435  }
436
437  // Get the class name
438  ObjCInterfaceDecl * ClassDecl = (ObjCInterfaceDecl*)OID->getClassInterface();
439  const char * ClassName = ClassDecl->getName();
440
441  // Get the size of instances.  For runtimes that support late-bound instances
442  // this should probably be something different (size just of instance
443  // varaibles in this class, not superclasses?).
444  int instanceSize = 0;
445  const llvm::Type *ObjTy;
446  if (!Runtime->LateBoundIVars()) {
447    ObjTy = getTypes().ConvertType(Context.getObjCInterfaceType(ClassDecl));
448    instanceSize = TheTargetData.getABITypeSize(ObjTy);
449  }
450
451  // Collect information about instance variables.
452  llvm::SmallVector<llvm::Constant*, 16> IvarNames;
453  llvm::SmallVector<llvm::Constant*, 16> IvarTypes;
454  llvm::SmallVector<llvm::Constant*, 16> IvarOffsets;
455  const llvm::StructLayout *Layout =
456    TheTargetData.getStructLayout(cast<llvm::StructType>(ObjTy));
457  ObjTy = llvm::PointerType::getUnqual(ObjTy);
458  for (ObjCInterfaceDecl::ivar_iterator iter = ClassDecl->ivar_begin(),
459      endIter = ClassDecl->ivar_end() ; iter != endIter ; iter++) {
460      // Store the name
461      IvarNames.push_back(GetAddrOfConstantString((*iter)->getName()));
462      // Get the type encoding for this ivar
463      std::string TypeStr;
464      llvm::SmallVector<const RecordType *, 8> EncodingRecordTypes;
465      Context.getObjCEncodingForType((*iter)->getType(), TypeStr,
466                                     EncodingRecordTypes);
467      IvarTypes.push_back(GetAddrOfConstantString(TypeStr));
468      // Get the offset
469      int offset =
470        (int)Layout->getElementOffset(getTypes().getLLVMFieldNo(*iter));
471      IvarOffsets.push_back(
472          llvm::ConstantInt::get(llvm::Type::Int32Ty, offset));
473  }
474
475  // Collect information about instance methods
476  llvm::SmallVector<llvm::Constant*, 16> InstanceMethodNames;
477  llvm::SmallVector<llvm::Constant*, 16> InstanceMethodTypes;
478  for (ObjCImplementationDecl::instmeth_iterator iter = OID->instmeth_begin(),
479      endIter = OID->instmeth_end() ; iter != endIter ; iter++) {
480    std::string TypeStr;
481    Context.getObjCEncodingForMethodDecl((*iter),TypeStr);
482    InstanceMethodNames.push_back(
483        GetAddrOfConstantString((*iter)->getSelector().getName()));
484    InstanceMethodTypes.push_back(GetAddrOfConstantString(TypeStr));
485  }
486
487  // Collect information about class methods
488  llvm::SmallVector<llvm::Constant*, 16> ClassMethodNames;
489  llvm::SmallVector<llvm::Constant*, 16> ClassMethodTypes;
490  for (ObjCImplementationDecl::classmeth_iterator iter = OID->classmeth_begin(),
491      endIter = OID->classmeth_end() ; iter != endIter ; iter++) {
492    std::string TypeStr;
493    Context.getObjCEncodingForMethodDecl((*iter),TypeStr);
494    ClassMethodNames.push_back(
495        GetAddrOfConstantString((*iter)->getSelector().getName()));
496    ClassMethodTypes.push_back(GetAddrOfConstantString(TypeStr));
497  }
498  // Collect the names of referenced protocols
499  llvm::SmallVector<std::string, 16> Protocols;
500  for (unsigned i = 0, e = ClassDecl->getNumIntfRefProtocols() ; i < e ; i++)
501    Protocols.push_back(ClassDecl->getReferencedProtocols()[i]->getName());
502
503  // Generate the category
504  Runtime->GenerateClass(ClassName, SCName, instanceSize, IvarNames, IvarTypes,
505      IvarOffsets, InstanceMethodNames, InstanceMethodTypes, ClassMethodNames,
506      ClassMethodTypes, Protocols);
507}
508
509
510void CodeGenModule::EmitFunction(const FunctionDecl *FD) {
511  // If this is not a prototype, emit the body.
512  if (!FD->isThisDeclarationADefinition()) {
513    if (FD->getAttr<AliasAttr>())
514      GetAddrOfFunctionDecl(FD, true);
515    return;
516  }
517
518  // If the function is a static, defer code generation until later so we can
519  // easily omit unused statics.
520  if (FD->getStorageClass() != FunctionDecl::Static) {
521    CodeGenFunction(*this).GenerateCode(FD);
522    return;
523  }
524
525  StaticDecls.push_back(FD);
526}
527
528void CodeGenModule::EmitStatics() {
529  // Emit code for each used static decl encountered.  Since a previously unused
530  // static decl may become used during the generation of code for a static
531  // function, iterate until no changes are made.
532  bool Changed;
533  do {
534    Changed = false;
535    for (unsigned i = 0, e = StaticDecls.size(); i != e; ++i) {
536      const Decl *D = StaticDecls[i];
537
538      // Check if we have used a decl with the same name
539      // FIXME: The AST should have some sort of aggregate decls or
540      // global symbol map.
541      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
542        if (!getModule().getFunction(FD->getName()))
543          continue;
544      } else {
545        if (!getModule().getNamedGlobal(cast<VarDecl>(D)->getName()))
546          continue;
547      }
548
549      // If this is a function decl, generate code for the static function if it
550      // has a body.  Otherwise, we must have a var decl for a static global
551      // variable.
552      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
553        if (FD->getBody())
554          CodeGenFunction(*this).GenerateCode(FD);
555        else if (FD->getAttr<AliasAttr>())
556          GetAddrOfFunctionDecl(FD, true);
557      } else {
558        EmitGlobalVarInit(cast<VarDecl>(D));
559      }
560      // Erase the used decl from the list.
561      StaticDecls[i] = StaticDecls.back();
562      StaticDecls.pop_back();
563      --i;
564      --e;
565
566      // Remember that we made a change.
567      Changed = true;
568    }
569  } while (Changed);
570}
571
572llvm::Constant *CodeGenModule::EmitGlobalInit(const Expr *Expr) {
573  return EmitConstantExpr(Expr);
574}
575
576/// EmitAnnotateAttr - Generate the llvm::ConstantStruct which contains the
577/// annotation information for a given GlobalValue.  The annotation struct is
578/// {i8 *, i8 *, i8 *, i32}.  The first field is a constant expression, the
579/// GlobalValue being annotated.  The second filed is thee constant string
580/// created from the AnnotateAttr's annotation.  The third field is a constant
581/// string containing the name of the translation unit.  The fourth field is
582/// the line number in the file of the annotated value declaration.
583///
584/// FIXME: this does not unique the annotation string constants, as llvm-gcc
585///        appears to.
586///
587llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
588                                                const AnnotateAttr *AA,
589                                                unsigned LineNo) {
590  llvm::Module *M = &getModule();
591
592  // get [N x i8] constants for the annotation string, and the filename string
593  // which are the 2nd and 3rd elements of the global annotation structure.
594  const llvm::Type *SBP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
595  llvm::Constant *anno = llvm::ConstantArray::get(AA->getAnnotation(), true);
596  llvm::Constant *unit = llvm::ConstantArray::get(M->getModuleIdentifier(),
597                                                  true);
598
599  // Get the two global values corresponding to the ConstantArrays we just
600  // created to hold the bytes of the strings.
601  llvm::GlobalValue *annoGV =
602  new llvm::GlobalVariable(anno->getType(), false,
603                           llvm::GlobalValue::InternalLinkage, anno,
604                           GV->getName() + ".str", M);
605  // translation unit name string, emitted into the llvm.metadata section.
606  llvm::GlobalValue *unitGV =
607  new llvm::GlobalVariable(unit->getType(), false,
608                           llvm::GlobalValue::InternalLinkage, unit, ".str", M);
609
610  // Create the ConstantStruct that is the global annotion.
611  llvm::Constant *Fields[4] = {
612    llvm::ConstantExpr::getBitCast(GV, SBP),
613    llvm::ConstantExpr::getBitCast(annoGV, SBP),
614    llvm::ConstantExpr::getBitCast(unitGV, SBP),
615    llvm::ConstantInt::get(llvm::Type::Int32Ty, LineNo)
616  };
617  return llvm::ConstantStruct::get(Fields, 4, false);
618}
619
620void CodeGenModule::EmitGlobalVar(const VarDecl *D) {
621  // If the VarDecl is a static, defer code generation until later so we can
622  // easily omit unused statics.
623  if (D->getStorageClass() == VarDecl::Static) {
624    StaticDecls.push_back(D);
625    return;
626  }
627
628  // If this is just a forward declaration of the variable, don't emit it now,
629  // allow it to be emitted lazily on its first use.
630  if (D->getStorageClass() == VarDecl::Extern && D->getInit() == 0)
631    return;
632
633  EmitGlobalVarInit(D);
634}
635
636void CodeGenModule::EmitGlobalVarInit(const VarDecl *D) {
637  assert(D->hasGlobalStorage() && "Not a global variable");
638
639  llvm::Constant *Init = 0;
640  QualType ASTTy = D->getType();
641  const llvm::Type *VarTy = getTypes().ConvertTypeForMem(ASTTy);
642  const llvm::Type *VarPtrTy =
643      llvm::PointerType::get(VarTy, ASTTy.getAddressSpace());
644
645  if (D->getInit() == 0) {
646    // This is a tentative definition; tentative definitions are
647    // implicitly initialized with { 0 }
648    const llvm::Type* InitTy;
649    if (ASTTy->isIncompleteArrayType()) {
650      // An incomplete array is normally [ TYPE x 0 ], but we need
651      // to fix it to [ TYPE x 1 ].
652      const llvm::ArrayType* ATy = cast<llvm::ArrayType>(VarTy);
653      InitTy = llvm::ArrayType::get(ATy->getElementType(), 1);
654    } else {
655      InitTy = VarTy;
656    }
657    Init = llvm::Constant::getNullValue(InitTy);
658  } else {
659    Init = EmitGlobalInit(D->getInit());
660  }
661  const llvm::Type* InitType = Init->getType();
662
663  llvm::GlobalVariable *GV = getModule().getGlobalVariable(D->getName(), true);
664
665  if (!GV) {
666    GV = new llvm::GlobalVariable(InitType, false,
667                                  llvm::GlobalValue::ExternalLinkage,
668                                  0, D->getName(), &getModule(), 0,
669                                  ASTTy.getAddressSpace());
670  } else if (GV->getType()->getElementType() != InitType ||
671             GV->getType()->getAddressSpace() != ASTTy.getAddressSpace()) {
672    // We have a definition after a prototype with the wrong type.
673    // We must make a new GlobalVariable* and update everything that used OldGV
674    // (a declaration or tentative definition) with the new GlobalVariable*
675    // (which will be a definition).
676    //
677    // This happens if there is a prototype for a global (e.g. "extern int x[];")
678    // and then a definition of a different type (e.g. "int x[10];"). This also
679    // happens when an initializer has a different type from the type of the
680    // global (this happens with unions).
681    //
682    // FIXME: This also ends up happening if there's a definition followed by
683    // a tentative definition!  (Although Sema rejects that construct
684    // at the moment.)
685
686    // Save the old global
687    llvm::GlobalVariable *OldGV = GV;
688
689    // Make a new global with the correct type
690    GV = new llvm::GlobalVariable(InitType, false,
691                                  llvm::GlobalValue::ExternalLinkage,
692                                  0, D->getName(), &getModule(), 0,
693                                  ASTTy.getAddressSpace());
694    // Steal the name of the old global
695    GV->takeName(OldGV);
696
697    // Replace all uses of the old global with the new global
698    llvm::Constant *NewPtrForOldDecl =
699        llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
700    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
701    // Make sure we don't keep around any stale references to globals
702    // FIXME: This is really slow; we need a better way to walk all
703    // the decls with the same name
704    ReplaceMapValuesWith(OldGV, NewPtrForOldDecl);
705
706    // Erase the old global, since it is no longer used.
707    OldGV->eraseFromParent();
708  }
709
710  GlobalDeclMap[D] = llvm::ConstantExpr::getBitCast(GV, VarPtrTy);
711
712  if (const AnnotateAttr *AA = D->getAttr<AnnotateAttr>()) {
713    SourceManager &SM = Context.getSourceManager();
714    AddAnnotation(EmitAnnotateAttr(GV, AA,
715                                   SM.getLogicalLineNumber(D->getLocation())));
716  }
717
718  GV->setInitializer(Init);
719
720  // FIXME: This is silly; getTypeAlign should just work for incomplete arrays
721  unsigned Align;
722  if (const IncompleteArrayType* IAT = D->getType()->getAsIncompleteArrayType())
723    Align = Context.getTypeAlign(IAT->getElementType());
724  else
725    Align = Context.getTypeAlign(D->getType());
726  if (const AlignedAttr* AA = D->getAttr<AlignedAttr>()) {
727    Align = std::max(Align, AA->getAlignment());
728  }
729  GV->setAlignment(Align / 8);
730
731  if (const VisibilityAttr *attr = D->getAttr<VisibilityAttr>())
732    setVisibility(GV, attr->getVisibility());
733  // FIXME: else handle -fvisibility
734
735  // Set the llvm linkage type as appropriate.
736  if (D->getStorageClass() == VarDecl::Static)
737    GV->setLinkage(llvm::Function::InternalLinkage);
738  else if (D->getAttr<DLLImportAttr>())
739    GV->setLinkage(llvm::Function::DLLImportLinkage);
740  else if (D->getAttr<DLLExportAttr>())
741    GV->setLinkage(llvm::Function::DLLExportLinkage);
742  else if (D->getAttr<WeakAttr>())
743    GV->setLinkage(llvm::GlobalVariable::WeakLinkage);
744  else {
745    // FIXME: This isn't right.  This should handle common linkage and other
746    // stuff.
747    switch (D->getStorageClass()) {
748    case VarDecl::Static: assert(0 && "This case handled above");
749    case VarDecl::Auto:
750    case VarDecl::Register:
751      assert(0 && "Can't have auto or register globals");
752    case VarDecl::None:
753      if (!D->getInit())
754        GV->setLinkage(llvm::GlobalVariable::CommonLinkage);
755      break;
756    case VarDecl::Extern:
757    case VarDecl::PrivateExtern:
758      // todo: common
759      break;
760    }
761  }
762
763  // Emit global variable debug information.
764  CGDebugInfo *DI = getDebugInfo();
765  if(DI) {
766    if(D->getLocation().isValid())
767      DI->setLocation(D->getLocation());
768    DI->EmitGlobalVariable(GV, D);
769  }
770}
771
772/// EmitGlobalVarDeclarator - Emit all the global vars attached to the specified
773/// declarator chain.
774void CodeGenModule::EmitGlobalVarDeclarator(const VarDecl *D) {
775  for (; D; D = cast_or_null<VarDecl>(D->getNextDeclarator()))
776    if (D->isFileVarDecl())
777      EmitGlobalVar(D);
778}
779
780void CodeGenModule::UpdateCompletedType(const TagDecl *TD) {
781  // Make sure that this type is translated.
782  Types.UpdateCompletedType(TD);
783}
784
785
786/// getBuiltinLibFunction
787llvm::Function *CodeGenModule::getBuiltinLibFunction(unsigned BuiltinID) {
788  if (BuiltinID > BuiltinFunctions.size())
789    BuiltinFunctions.resize(BuiltinID);
790
791  // Cache looked up functions.  Since builtin id #0 is invalid we don't reserve
792  // a slot for it.
793  assert(BuiltinID && "Invalid Builtin ID");
794  llvm::Function *&FunctionSlot = BuiltinFunctions[BuiltinID-1];
795  if (FunctionSlot)
796    return FunctionSlot;
797
798  assert(Context.BuiltinInfo.isLibFunction(BuiltinID) && "isn't a lib fn");
799
800  // Get the name, skip over the __builtin_ prefix.
801  const char *Name = Context.BuiltinInfo.GetName(BuiltinID)+10;
802
803  // Get the type for the builtin.
804  QualType Type = Context.BuiltinInfo.GetBuiltinType(BuiltinID, Context);
805  const llvm::FunctionType *Ty =
806    cast<llvm::FunctionType>(getTypes().ConvertType(Type));
807
808  // FIXME: This has a serious problem with code like this:
809  //  void abs() {}
810  //    ... __builtin_abs(x);
811  // The two versions of abs will collide.  The fix is for the builtin to win,
812  // and for the existing one to be turned into a constantexpr cast of the
813  // builtin.  In the case where the existing one is a static function, it
814  // should just be renamed.
815  if (llvm::Function *Existing = getModule().getFunction(Name)) {
816    if (Existing->getFunctionType() == Ty && Existing->hasExternalLinkage())
817      return FunctionSlot = Existing;
818    assert(Existing == 0 && "FIXME: Name collision");
819  }
820
821  // FIXME: param attributes for sext/zext etc.
822  return FunctionSlot =
823    llvm::Function::Create(Ty, llvm::Function::ExternalLinkage, Name,
824                           &getModule());
825}
826
827llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,const llvm::Type **Tys,
828                                            unsigned NumTys) {
829  return llvm::Intrinsic::getDeclaration(&getModule(),
830                                         (llvm::Intrinsic::ID)IID, Tys, NumTys);
831}
832
833llvm::Function *CodeGenModule::getMemCpyFn() {
834  if (MemCpyFn) return MemCpyFn;
835  llvm::Intrinsic::ID IID;
836  switch (Context.Target.getPointerWidth(0)) {
837  default: assert(0 && "Unknown ptr width");
838  case 32: IID = llvm::Intrinsic::memcpy_i32; break;
839  case 64: IID = llvm::Intrinsic::memcpy_i64; break;
840  }
841  return MemCpyFn = getIntrinsic(IID);
842}
843
844llvm::Function *CodeGenModule::getMemMoveFn() {
845  if (MemMoveFn) return MemMoveFn;
846  llvm::Intrinsic::ID IID;
847  switch (Context.Target.getPointerWidth(0)) {
848  default: assert(0 && "Unknown ptr width");
849  case 32: IID = llvm::Intrinsic::memmove_i32; break;
850  case 64: IID = llvm::Intrinsic::memmove_i64; break;
851  }
852  return MemMoveFn = getIntrinsic(IID);
853}
854
855llvm::Function *CodeGenModule::getMemSetFn() {
856  if (MemSetFn) return MemSetFn;
857  llvm::Intrinsic::ID IID;
858  switch (Context.Target.getPointerWidth(0)) {
859  default: assert(0 && "Unknown ptr width");
860  case 32: IID = llvm::Intrinsic::memset_i32; break;
861  case 64: IID = llvm::Intrinsic::memset_i64; break;
862  }
863  return MemSetFn = getIntrinsic(IID);
864}
865
866// FIXME: This needs moving into an Apple Objective-C runtime class
867llvm::Constant *CodeGenModule::
868GetAddrOfConstantCFString(const std::string &str) {
869  llvm::StringMapEntry<llvm::Constant *> &Entry =
870    CFConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
871
872  if (Entry.getValue())
873    return Entry.getValue();
874
875  std::vector<llvm::Constant*> Fields;
876
877  if (!CFConstantStringClassRef) {
878    const llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
879    Ty = llvm::ArrayType::get(Ty, 0);
880
881    CFConstantStringClassRef =
882      new llvm::GlobalVariable(Ty, false,
883                               llvm::GlobalVariable::ExternalLinkage, 0,
884                               "__CFConstantStringClassReference",
885                               &getModule());
886  }
887
888  // Class pointer.
889  llvm::Constant *Zero = llvm::Constant::getNullValue(llvm::Type::Int32Ty);
890  llvm::Constant *Zeros[] = { Zero, Zero };
891  llvm::Constant *C =
892    llvm::ConstantExpr::getGetElementPtr(CFConstantStringClassRef, Zeros, 2);
893  Fields.push_back(C);
894
895  // Flags.
896  const llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
897  Fields.push_back(llvm::ConstantInt::get(Ty, 1992));
898
899  // String pointer.
900  C = llvm::ConstantArray::get(str);
901  C = new llvm::GlobalVariable(C->getType(), true,
902                               llvm::GlobalValue::InternalLinkage,
903                               C, ".str", &getModule());
904
905  C = llvm::ConstantExpr::getGetElementPtr(C, Zeros, 2);
906  Fields.push_back(C);
907
908  // String length.
909  Ty = getTypes().ConvertType(getContext().LongTy);
910  Fields.push_back(llvm::ConstantInt::get(Ty, str.length()));
911
912  // The struct.
913  Ty = getTypes().ConvertType(getContext().getCFConstantStringType());
914  C = llvm::ConstantStruct::get(cast<llvm::StructType>(Ty), Fields);
915  llvm::GlobalVariable *GV =
916    new llvm::GlobalVariable(C->getType(), true,
917                             llvm::GlobalVariable::InternalLinkage,
918                             C, "", &getModule());
919  GV->setSection("__DATA,__cfstring");
920  Entry.setValue(GV);
921  return GV;
922}
923
924/// GenerateWritableString -- Creates storage for a string literal.
925static llvm::Constant *GenerateStringLiteral(const std::string &str,
926                                             bool constant,
927                                             CodeGenModule &CGM) {
928  // Create Constant for this string literal
929  llvm::Constant *C=llvm::ConstantArray::get(str);
930
931  // Create a global variable for this string
932  C = new llvm::GlobalVariable(C->getType(), constant,
933                               llvm::GlobalValue::InternalLinkage,
934                               C, ".str", &CGM.getModule());
935  return C;
936}
937
938/// CodeGenModule::GetAddrOfConstantString -- returns a pointer to the character
939/// array containing the literal.  The result is pointer to array type.
940llvm::Constant *CodeGenModule::GetAddrOfConstantString(const std::string &str) {
941  // Don't share any string literals if writable-strings is turned on.
942  if (Features.WritableStrings)
943    return GenerateStringLiteral(str, false, *this);
944
945  llvm::StringMapEntry<llvm::Constant *> &Entry =
946  ConstantStringMap.GetOrCreateValue(&str[0], &str[str.length()]);
947
948  if (Entry.getValue())
949      return Entry.getValue();
950
951  // Create a global variable for this.
952  llvm::Constant *C = GenerateStringLiteral(str, true, *this);
953  Entry.setValue(C);
954  return C;
955}
956