CGCXX.cpp revision 738f8c278da5950d0d4607de2debe0bdfad64185 
1//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This contains code dealing with C++ code generation.
11//
12//===----------------------------------------------------------------------===//
13
14// We might split this into multiple files if it gets too unwieldy
15
16#include "CodeGenFunction.h"
17#include "CodeGenModule.h"
18#include "Mangle.h"
19#include "clang/AST/ASTContext.h"
20#include "clang/AST/RecordLayout.h"
21#include "clang/AST/Decl.h"
22#include "clang/AST/DeclCXX.h"
23#include "clang/AST/DeclObjC.h"
24#include "llvm/ADT/StringExtras.h"
25using namespace clang;
26using namespace CodeGen;
27
28void
29CodeGenFunction::GenerateStaticCXXBlockVarDeclInit(const VarDecl &D,
30                                                   llvm::GlobalVariable *GV) {
31  // FIXME: This should use __cxa_guard_{acquire,release}?
32
33  assert(!getContext().getLangOptions().ThreadsafeStatics &&
34         "thread safe statics are currently not supported!");
35
36  llvm::SmallString<256> GuardVName;
37  llvm::raw_svector_ostream GuardVOut(GuardVName);
38  mangleGuardVariable(&D, getContext(), GuardVOut);
39
40  // Create the guard variable.
41  llvm::GlobalValue *GuardV =
42    new llvm::GlobalVariable(CGM.getModule(), llvm::Type::Int64Ty, false,
43                             GV->getLinkage(),
44                             llvm::Constant::getNullValue(llvm::Type::Int64Ty),
45                             GuardVName.c_str());
46
47  // Load the first byte of the guard variable.
48  const llvm::Type *PtrTy = llvm::PointerType::get(llvm::Type::Int8Ty, 0);
49  llvm::Value *V = Builder.CreateLoad(Builder.CreateBitCast(GuardV, PtrTy),
50                                      "tmp");
51
52  // Compare it against 0.
53  llvm::Value *nullValue = llvm::Constant::getNullValue(llvm::Type::Int8Ty);
54  llvm::Value *ICmp = Builder.CreateICmpEQ(V, nullValue , "tobool");
55
56  llvm::BasicBlock *InitBlock = createBasicBlock("init");
57  llvm::BasicBlock *EndBlock = createBasicBlock("init.end");
58
59  // If the guard variable is 0, jump to the initializer code.
60  Builder.CreateCondBr(ICmp, InitBlock, EndBlock);
61
62  EmitBlock(InitBlock);
63
64  const Expr *Init = D.getInit();
65  if (!hasAggregateLLVMType(Init->getType())) {
66    llvm::Value *V = EmitScalarExpr(Init);
67    Builder.CreateStore(V, GV, D.getType().isVolatileQualified());
68  } else if (Init->getType()->isAnyComplexType()) {
69    EmitComplexExprIntoAddr(Init, GV, D.getType().isVolatileQualified());
70  } else {
71    EmitAggExpr(Init, GV, D.getType().isVolatileQualified());
72  }
73
74  Builder.CreateStore(llvm::ConstantInt::get(llvm::Type::Int8Ty, 1),
75                      Builder.CreateBitCast(GuardV, PtrTy));
76
77  EmitBlock(EndBlock);
78}
79
80RValue CodeGenFunction::EmitCXXMemberCall(const CXXMethodDecl *MD,
81                                          llvm::Value *Callee,
82                                          llvm::Value *This,
83                                          CallExpr::const_arg_iterator ArgBeg,
84                                          CallExpr::const_arg_iterator ArgEnd) {
85  assert(MD->isInstance() &&
86         "Trying to emit a member call expr on a static method!");
87
88  const FunctionProtoType *FPT = MD->getType()->getAsFunctionProtoType();
89
90  CallArgList Args;
91
92  // Push the this ptr.
93  Args.push_back(std::make_pair(RValue::get(This),
94                                MD->getThisType(getContext())));
95
96  // And the rest of the call args
97  EmitCallArgs(Args, FPT, ArgBeg, ArgEnd);
98
99  QualType ResultType = MD->getType()->getAsFunctionType()->getResultType();
100  return EmitCall(CGM.getTypes().getFunctionInfo(ResultType, Args),
101                  Callee, Args, MD);
102}
103
104RValue CodeGenFunction::EmitCXXMemberCallExpr(const CXXMemberCallExpr *CE) {
105  const MemberExpr *ME = cast<MemberExpr>(CE->getCallee());
106  const CXXMethodDecl *MD = cast<CXXMethodDecl>(ME->getMemberDecl());
107
108  const FunctionProtoType *FPT = MD->getType()->getAsFunctionProtoType();
109
110  if (MD->isVirtual()) {
111    ErrorUnsupported(CE, "virtual dispatch");
112  }
113
114  const llvm::Type *Ty =
115    CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(MD),
116                                   FPT->isVariadic());
117  llvm::Constant *Callee = CGM.GetAddrOfFunction(GlobalDecl(MD), Ty);
118
119  llvm::Value *This;
120
121  if (ME->isArrow())
122    This = EmitScalarExpr(ME->getBase());
123  else {
124    LValue BaseLV = EmitLValue(ME->getBase());
125    This = BaseLV.getAddress();
126  }
127
128  return EmitCXXMemberCall(MD, Callee, This,
129                           CE->arg_begin(), CE->arg_end());
130}
131
132RValue
133CodeGenFunction::EmitCXXOperatorMemberCallExpr(const CXXOperatorCallExpr *E,
134                                               const CXXMethodDecl *MD) {
135  assert(MD->isInstance() &&
136         "Trying to emit a member call expr on a static method!");
137
138
139  const FunctionProtoType *FPT = MD->getType()->getAsFunctionProtoType();
140  const llvm::Type *Ty =
141  CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(MD),
142                                 FPT->isVariadic());
143  llvm::Constant *Callee = CGM.GetAddrOfFunction(GlobalDecl(MD), Ty);
144
145  llvm::Value *This = EmitLValue(E->getArg(0)).getAddress();
146
147  return EmitCXXMemberCall(MD, Callee, This,
148                           E->arg_begin() + 1, E->arg_end());
149}
150
151llvm::Value *CodeGenFunction::LoadCXXThis() {
152  assert(isa<CXXMethodDecl>(CurFuncDecl) &&
153         "Must be in a C++ member function decl to load 'this'");
154  assert(cast<CXXMethodDecl>(CurFuncDecl)->isInstance() &&
155         "Must be in a C++ member function decl to load 'this'");
156
157  // FIXME: What if we're inside a block?
158  // ans: See how CodeGenFunction::LoadObjCSelf() uses
159  // CodeGenFunction::BlockForwardSelf() for how to do this.
160  return Builder.CreateLoad(LocalDeclMap[CXXThisDecl], "this");
161}
162
163static bool
164GetNestedPaths(llvm::SmallVectorImpl<const CXXRecordDecl *> &NestedBasePaths,
165               const CXXRecordDecl *ClassDecl,
166               const CXXRecordDecl *BaseClassDecl) {
167  assert(!ClassDecl->isPolymorphic() &&
168         "FIXME: We don't support polymorphic classes yet!");
169  for (CXXRecordDecl::base_class_const_iterator i = ClassDecl->bases_begin(),
170      e = ClassDecl->bases_end(); i != e; ++i) {
171    if (i->isVirtual())
172      continue;
173    const CXXRecordDecl *Base =
174        cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
175    if (Base == BaseClassDecl) {
176      NestedBasePaths.push_back(BaseClassDecl);
177      return true;
178    }
179  }
180  // BaseClassDecl not an immediate base of ClassDecl.
181  for (CXXRecordDecl::base_class_const_iterator i = ClassDecl->bases_begin(),
182       e = ClassDecl->bases_end(); i != e; ++i) {
183    if (i->isVirtual())
184      continue;
185    const CXXRecordDecl *Base =
186      cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
187    if (GetNestedPaths(NestedBasePaths, Base, BaseClassDecl)) {
188      NestedBasePaths.push_back(Base);
189      return true;
190    }
191  }
192  return false;
193}
194
195llvm::Value *CodeGenFunction::AddressCXXOfBaseClass(llvm::Value *BaseValue,
196                                          const CXXRecordDecl *ClassDecl,
197                                          const CXXRecordDecl *BaseClassDecl) {
198  if (ClassDecl == BaseClassDecl)
199    return BaseValue;
200
201  llvm::Type *I8Ptr = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
202  llvm::SmallVector<const CXXRecordDecl *, 16> NestedBasePaths;
203  GetNestedPaths(NestedBasePaths, ClassDecl, BaseClassDecl);
204  assert(NestedBasePaths.size() > 0 &&
205         "AddressCXXOfBaseClass - inheritence path failed");
206  NestedBasePaths.push_back(ClassDecl);
207  uint64_t Offset = 0;
208
209  // Accessing a member of the base class. Must add delata to
210  // the load of 'this'.
211  for (unsigned i = NestedBasePaths.size()-1; i > 0; i--) {
212    const CXXRecordDecl *DerivedClass = NestedBasePaths[i];
213    const CXXRecordDecl *BaseClass = NestedBasePaths[i-1];
214    const ASTRecordLayout &Layout =
215      getContext().getASTRecordLayout(DerivedClass);
216    Offset += Layout.getBaseClassOffset(BaseClass) / 8;
217  }
218  llvm::Value *OffsetVal =
219    llvm::ConstantInt::get(
220                  CGM.getTypes().ConvertType(CGM.getContext().LongTy), Offset);
221  BaseValue = Builder.CreateBitCast(BaseValue, I8Ptr);
222  BaseValue = Builder.CreateGEP(BaseValue, OffsetVal, "add.ptr");
223  QualType BTy =
224    getContext().getCanonicalType(
225      getContext().getTypeDeclType(const_cast<CXXRecordDecl*>(BaseClassDecl)));
226  const llvm::Type *BasePtr = ConvertType(BTy);
227  BasePtr = llvm::PointerType::getUnqual(BasePtr);
228  BaseValue = Builder.CreateBitCast(BaseValue, BasePtr);
229  return BaseValue;
230}
231
232void
233CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
234                                        CXXCtorType Type,
235                                        llvm::Value *This,
236                                        CallExpr::const_arg_iterator ArgBeg,
237                                        CallExpr::const_arg_iterator ArgEnd) {
238  llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D, Type);
239
240  EmitCXXMemberCall(D, Callee, This, ArgBeg, ArgEnd);
241}
242
243void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *D,
244                                            CXXDtorType Type,
245                                            llvm::Value *This) {
246  llvm::Value *Callee = CGM.GetAddrOfCXXDestructor(D, Type);
247
248  EmitCXXMemberCall(D, Callee, This, 0, 0);
249}
250
251void
252CodeGenFunction::EmitCXXConstructExpr(llvm::Value *Dest,
253                                      const CXXConstructExpr *E) {
254  assert(Dest && "Must have a destination!");
255
256  const CXXRecordDecl *RD =
257  cast<CXXRecordDecl>(E->getType()->getAs<RecordType>()->getDecl());
258  if (RD->hasTrivialConstructor())
259    return;
260
261  // Call the constructor.
262  EmitCXXConstructorCall(E->getConstructor(), Ctor_Complete, Dest,
263                         E->arg_begin(), E->arg_end());
264}
265
266llvm::Value *CodeGenFunction::EmitCXXNewExpr(const CXXNewExpr *E) {
267  if (E->isArray()) {
268    ErrorUnsupported(E, "new[] expression");
269    return llvm::UndefValue::get(ConvertType(E->getType()));
270  }
271
272  QualType AllocType = E->getAllocatedType();
273  FunctionDecl *NewFD = E->getOperatorNew();
274  const FunctionProtoType *NewFTy = NewFD->getType()->getAsFunctionProtoType();
275
276  CallArgList NewArgs;
277
278  // The allocation size is the first argument.
279  QualType SizeTy = getContext().getSizeType();
280  llvm::Value *AllocSize =
281    llvm::ConstantInt::get(ConvertType(SizeTy),
282                           getContext().getTypeSize(AllocType) / 8);
283
284  NewArgs.push_back(std::make_pair(RValue::get(AllocSize), SizeTy));
285
286  // Emit the rest of the arguments.
287  // FIXME: Ideally, this should just use EmitCallArgs.
288  CXXNewExpr::const_arg_iterator NewArg = E->placement_arg_begin();
289
290  // First, use the types from the function type.
291  // We start at 1 here because the first argument (the allocation size)
292  // has already been emitted.
293  for (unsigned i = 1, e = NewFTy->getNumArgs(); i != e; ++i, ++NewArg) {
294    QualType ArgType = NewFTy->getArgType(i);
295
296    assert(getContext().getCanonicalType(ArgType.getNonReferenceType()).
297           getTypePtr() ==
298           getContext().getCanonicalType(NewArg->getType()).getTypePtr() &&
299           "type mismatch in call argument!");
300
301    NewArgs.push_back(std::make_pair(EmitCallArg(*NewArg, ArgType),
302                                     ArgType));
303
304  }
305
306  // Either we've emitted all the call args, or we have a call to a
307  // variadic function.
308  assert((NewArg == E->placement_arg_end() || NewFTy->isVariadic()) &&
309         "Extra arguments in non-variadic function!");
310
311  // If we still have any arguments, emit them using the type of the argument.
312  for (CXXNewExpr::const_arg_iterator NewArgEnd = E->placement_arg_end();
313       NewArg != NewArgEnd; ++NewArg) {
314    QualType ArgType = NewArg->getType();
315    NewArgs.push_back(std::make_pair(EmitCallArg(*NewArg, ArgType),
316                                     ArgType));
317  }
318
319  // Emit the call to new.
320  RValue RV =
321    EmitCall(CGM.getTypes().getFunctionInfo(NewFTy->getResultType(), NewArgs),
322             CGM.GetAddrOfFunction(GlobalDecl(NewFD)),
323             NewArgs, NewFD);
324
325  // If an allocation function is declared with an empty exception specification
326  // it returns null to indicate failure to allocate storage. [expr.new]p13.
327  // (We don't need to check for null when there's no new initializer and
328  // we're allocating a POD type).
329  bool NullCheckResult = NewFTy->hasEmptyExceptionSpec() &&
330    !(AllocType->isPODType() && !E->hasInitializer());
331
332  llvm::BasicBlock *NewNull = 0;
333  llvm::BasicBlock *NewNotNull = 0;
334  llvm::BasicBlock *NewEnd = 0;
335
336  llvm::Value *NewPtr = RV.getScalarVal();
337
338  if (NullCheckResult) {
339    NewNull = createBasicBlock("new.null");
340    NewNotNull = createBasicBlock("new.notnull");
341    NewEnd = createBasicBlock("new.end");
342
343    llvm::Value *IsNull =
344      Builder.CreateICmpEQ(NewPtr,
345                           llvm::Constant::getNullValue(NewPtr->getType()),
346                           "isnull");
347
348    Builder.CreateCondBr(IsNull, NewNull, NewNotNull);
349    EmitBlock(NewNotNull);
350  }
351
352  NewPtr = Builder.CreateBitCast(NewPtr, ConvertType(E->getType()));
353
354  if (AllocType->isPODType()) {
355    if (E->getNumConstructorArgs() > 0) {
356      assert(E->getNumConstructorArgs() == 1 &&
357             "Can only have one argument to initializer of POD type.");
358
359      const Expr *Init = E->getConstructorArg(0);
360
361      if (!hasAggregateLLVMType(AllocType))
362        Builder.CreateStore(EmitScalarExpr(Init), NewPtr);
363      else if (AllocType->isAnyComplexType())
364        EmitComplexExprIntoAddr(Init, NewPtr, AllocType.isVolatileQualified());
365      else
366        EmitAggExpr(Init, NewPtr, AllocType.isVolatileQualified());
367    }
368  } else {
369    // Call the constructor.
370    CXXConstructorDecl *Ctor = E->getConstructor();
371
372    EmitCXXConstructorCall(Ctor, Ctor_Complete, NewPtr,
373                           E->constructor_arg_begin(),
374                           E->constructor_arg_end());
375  }
376
377  if (NullCheckResult) {
378    Builder.CreateBr(NewEnd);
379    EmitBlock(NewNull);
380    Builder.CreateBr(NewEnd);
381    EmitBlock(NewEnd);
382
383    llvm::PHINode *PHI = Builder.CreatePHI(NewPtr->getType());
384    PHI->reserveOperandSpace(2);
385    PHI->addIncoming(NewPtr, NewNotNull);
386    PHI->addIncoming(llvm::Constant::getNullValue(NewPtr->getType()), NewNull);
387
388    NewPtr = PHI;
389  }
390
391  return NewPtr;
392}
393
394static bool canGenerateCXXstructor(const CXXRecordDecl *RD,
395                                   ASTContext &Context) {
396  // The class has base classes - we don't support that right now.
397  if (RD->getNumBases() > 0)
398    return false;
399
400  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
401         I != E; ++I) {
402    // We don't support ctors for fields that aren't POD.
403    if (!I->getType()->isPODType())
404      return false;
405  }
406
407  return true;
408}
409
410void CodeGenModule::EmitCXXConstructors(const CXXConstructorDecl *D) {
411  if (!canGenerateCXXstructor(D->getParent(), getContext())) {
412    ErrorUnsupported(D, "C++ constructor", true);
413    return;
414  }
415
416  EmitGlobal(GlobalDecl(D, Ctor_Complete));
417  EmitGlobal(GlobalDecl(D, Ctor_Base));
418}
419
420void CodeGenModule::EmitCXXConstructor(const CXXConstructorDecl *D,
421                                       CXXCtorType Type) {
422
423  llvm::Function *Fn = GetAddrOfCXXConstructor(D, Type);
424
425  CodeGenFunction(*this).GenerateCode(D, Fn);
426
427  SetFunctionDefinitionAttributes(D, Fn);
428  SetLLVMFunctionAttributesForDefinition(D, Fn);
429}
430
431llvm::Function *
432CodeGenModule::GetAddrOfCXXConstructor(const CXXConstructorDecl *D,
433                                       CXXCtorType Type) {
434  const llvm::FunctionType *FTy =
435    getTypes().GetFunctionType(getTypes().getFunctionInfo(D), false);
436
437  const char *Name = getMangledCXXCtorName(D, Type);
438  return cast<llvm::Function>(
439                      GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(D, Type)));
440}
441
442const char *CodeGenModule::getMangledCXXCtorName(const CXXConstructorDecl *D,
443                                                 CXXCtorType Type) {
444  llvm::SmallString<256> Name;
445  llvm::raw_svector_ostream Out(Name);
446  mangleCXXCtor(D, Type, Context, Out);
447
448  Name += '\0';
449  return UniqueMangledName(Name.begin(), Name.end());
450}
451
452void CodeGenModule::EmitCXXDestructors(const CXXDestructorDecl *D) {
453  if (!canGenerateCXXstructor(D->getParent(), getContext())) {
454    ErrorUnsupported(D, "C++ destructor", true);
455    return;
456  }
457
458  EmitCXXDestructor(D, Dtor_Complete);
459  EmitCXXDestructor(D, Dtor_Base);
460}
461
462void CodeGenModule::EmitCXXDestructor(const CXXDestructorDecl *D,
463                                      CXXDtorType Type) {
464  llvm::Function *Fn = GetAddrOfCXXDestructor(D, Type);
465
466  CodeGenFunction(*this).GenerateCode(D, Fn);
467
468  SetFunctionDefinitionAttributes(D, Fn);
469  SetLLVMFunctionAttributesForDefinition(D, Fn);
470}
471
472llvm::Function *
473CodeGenModule::GetAddrOfCXXDestructor(const CXXDestructorDecl *D,
474                                      CXXDtorType Type) {
475  const llvm::FunctionType *FTy =
476    getTypes().GetFunctionType(getTypes().getFunctionInfo(D), false);
477
478  const char *Name = getMangledCXXDtorName(D, Type);
479  return cast<llvm::Function>(
480                      GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(D, Type)));
481}
482
483const char *CodeGenModule::getMangledCXXDtorName(const CXXDestructorDecl *D,
484                                                 CXXDtorType Type) {
485  llvm::SmallString<256> Name;
486  llvm::raw_svector_ostream Out(Name);
487  mangleCXXDtor(D, Type, Context, Out);
488
489  Name += '\0';
490  return UniqueMangledName(Name.begin(), Name.end());
491}
492
493llvm::Constant *CodeGenFunction::GenerateRtti(const CXXRecordDecl *RD) {
494  llvm::Type *Ptr8Ty;
495  Ptr8Ty = llvm::PointerType::get(llvm::Type::Int8Ty, 0);
496  llvm::Constant *rtti = llvm::Constant::getNullValue(Ptr8Ty);
497
498  if (!getContext().getLangOptions().Rtti)
499    return rtti;
500
501  llvm::SmallString<256> OutName;
502  llvm::raw_svector_ostream Out(OutName);
503  QualType ClassTy;
504  // FIXME: What is the design on getTagDeclType when it requires casting
505  // away const?  mutable?
506  ClassTy = getContext().getTagDeclType(const_cast<CXXRecordDecl*>(RD));
507  mangleCXXRtti(ClassTy, getContext(), Out);
508  const char *Name = OutName.c_str();
509  llvm::GlobalVariable::LinkageTypes linktype;
510  linktype = llvm::GlobalValue::WeakAnyLinkage;
511  std::vector<llvm::Constant *> info;
512  assert (0 && "FIXME: implement rtti descriptor");
513  // FIXME: descriptor
514  info.push_back(llvm::Constant::getNullValue(Ptr8Ty));
515  assert (0 && "FIXME: implement rtti ts");
516  // FIXME: TS
517  info.push_back(llvm::Constant::getNullValue(Ptr8Ty));
518
519  llvm::Constant *C;
520  llvm::ArrayType *type = llvm::ArrayType::get(Ptr8Ty, info.size());
521  C = llvm::ConstantArray::get(type, info);
522  rtti = new llvm::GlobalVariable(CGM.getModule(), type, true, linktype, C,
523                                  Name);
524  rtti = llvm::ConstantExpr::getBitCast(rtti, Ptr8Ty);
525  return rtti;
526}
527
528llvm::Value *CodeGenFunction::GenerateVtable(const CXXRecordDecl *RD) {
529  llvm::SmallString<256> OutName;
530  llvm::raw_svector_ostream Out(OutName);
531  QualType ClassTy;
532  // FIXME: What is the design on getTagDeclType when it requires casting
533  // away const?  mutable?
534  ClassTy = getContext().getTagDeclType(const_cast<CXXRecordDecl*>(RD));
535  mangleCXXVtable(ClassTy, getContext(), Out);
536  const char *Name = OutName.c_str();
537  llvm::GlobalVariable::LinkageTypes linktype;
538  linktype = llvm::GlobalValue::WeakAnyLinkage;
539  std::vector<llvm::Constant *> methods;
540  typedef CXXRecordDecl::method_iterator meth_iter;
541  llvm::Constant *m;
542  llvm::Type *Ptr8Ty;
543  Ptr8Ty = llvm::PointerType::get(llvm::Type::Int8Ty, 0);
544  m = llvm::Constant::getNullValue(Ptr8Ty);
545  int64_t offset = 0;
546  methods.push_back(m); offset += LLVMPointerWidth;
547  methods.push_back(GenerateRtti(RD)); offset += LLVMPointerWidth;
548  for (meth_iter mi = RD->method_begin(), me = RD->method_end(); mi != me;
549       ++mi) {
550    if (mi->isVirtual()) {
551      m = CGM.GetAddrOfFunction(GlobalDecl(*mi));
552      m = llvm::ConstantExpr::getBitCast(m, Ptr8Ty);
553      methods.push_back(m);
554    }
555  }
556  llvm::Constant *C;
557  llvm::ArrayType *type = llvm::ArrayType::get(Ptr8Ty, methods.size());
558  C = llvm::ConstantArray::get(type, methods);
559  llvm::Value *vtable = new llvm::GlobalVariable(CGM.getModule(), type, true,
560                                                 linktype, C, Name);
561  vtable = Builder.CreateBitCast(vtable, Ptr8Ty);
562  // FIXME: finish layout for virtual bases
563  vtable = Builder.CreateGEP(vtable,
564                             llvm::ConstantInt::get(llvm::Type::Int64Ty,
565                                                    offset/8));
566  return vtable;
567}
568
569/// EmitCtorPrologue - This routine generates necessary code to initialize
570/// base classes and non-static data members belonging to this constructor.
571void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD) {
572  const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(CD->getDeclContext());
573  assert(ClassDecl->getNumVBases() == 0
574         && "FIXME: virtual base initialization unsupported");
575  llvm::Value *LoadOfThis = 0;
576
577
578  for (CXXConstructorDecl::init_const_iterator B = CD->init_begin(),
579       E = CD->init_end();
580       B != E; ++B) {
581    CXXBaseOrMemberInitializer *Member = (*B);
582    if (Member->isBaseInitializer()) {
583      LoadOfThis = LoadCXXThis();
584      Type *BaseType = Member->getBaseClass();
585      CXXRecordDecl *BaseClassDecl =
586        cast<CXXRecordDecl>(BaseType->getAs<RecordType>()->getDecl());
587      llvm::Value *V = AddressCXXOfBaseClass(LoadOfThis, ClassDecl,
588                                             BaseClassDecl);
589      EmitCXXConstructorCall(Member->getConstructor(),
590                             Ctor_Complete, V,
591                             Member->const_arg_begin(),
592                             Member->const_arg_end());
593    } else {
594      // non-static data member initilaizers.
595      FieldDecl *Field = Member->getMember();
596      QualType FieldType = getContext().getCanonicalType((Field)->getType());
597      assert(!getContext().getAsArrayType(FieldType)
598             && "FIXME. Field arrays initialization unsupported");
599
600      LoadOfThis = LoadCXXThis();
601      LValue LHS = EmitLValueForField(LoadOfThis, Field, false, 0);
602      if (FieldType->getAs<RecordType>()) {
603
604          assert(Member->getConstructor() &&
605                 "EmitCtorPrologue - no constructor to initialize member");
606          EmitCXXConstructorCall(Member->getConstructor(),
607                                 Ctor_Complete, LHS.getAddress(),
608                                 Member->const_arg_begin(),
609                                 Member->const_arg_end());
610        continue;
611      }
612
613      assert(Member->getNumArgs() == 1 && "Initializer count must be 1 only");
614      Expr *RhsExpr = *Member->arg_begin();
615      llvm::Value *RHS = EmitScalarExpr(RhsExpr, true);
616      if (LHS.isBitfield())
617        EmitStoreThroughBitfieldLValue(RValue::get(RHS), LHS, FieldType, 0);
618      else
619        EmitStoreThroughLValue(RValue::get(RHS), LHS, FieldType);
620    }
621  }
622
623  // Initialize the vtable pointer
624  if (ClassDecl->isPolymorphic() || ClassDecl->getNumVBases()) {
625    if (!LoadOfThis)
626      LoadOfThis = LoadCXXThis();
627    llvm::Value *VtableField;
628    llvm::Type *Ptr8Ty, *PtrPtr8Ty;
629    Ptr8Ty = llvm::PointerType::get(llvm::Type::Int8Ty, 0);
630    PtrPtr8Ty = llvm::PointerType::get(Ptr8Ty, 0);
631    VtableField = Builder.CreateBitCast(LoadOfThis, PtrPtr8Ty);
632    llvm::Value *vtable = GenerateVtable(ClassDecl);
633    Builder.CreateStore(vtable, VtableField);
634  }
635}
636
637/// EmitDtorEpilogue - Emit all code that comes at the end of class's
638/// destructor. This is to call destructors on members and base classes
639/// in reverse order of their construction.
640void CodeGenFunction::EmitDtorEpilogue(const CXXDestructorDecl *DD) {
641  const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(DD->getDeclContext());
642  assert(!ClassDecl->isPolymorphic() &&
643         "FIXME. polymorphic destruction not supported");
644  (void)ClassDecl;  // prevent warning.
645
646  for (CXXDestructorDecl::destr_const_iterator *B = DD->destr_begin(),
647       *E = DD->destr_end(); B != E; ++B) {
648    uintptr_t BaseOrMember = (*B);
649    if (DD->isMemberToDestroy(BaseOrMember)) {
650      FieldDecl *FD = DD->getMemberToDestroy(BaseOrMember);
651      QualType FieldType = getContext().getCanonicalType((FD)->getType());
652      assert(!getContext().getAsArrayType(FieldType)
653             && "FIXME. Field arrays destruction unsupported");
654      const RecordType *RT = FieldType->getAs<RecordType>();
655      CXXRecordDecl *FieldClassDecl = cast<CXXRecordDecl>(RT->getDecl());
656      if (FieldClassDecl->hasTrivialDestructor())
657        continue;
658      llvm::Value *LoadOfThis = LoadCXXThis();
659      LValue LHS = EmitLValueForField(LoadOfThis, FD, false, 0);
660      EmitCXXDestructorCall(FieldClassDecl->getDestructor(getContext()),
661                            Dtor_Complete, LHS.getAddress());
662    } else {
663      const RecordType *RT =
664        DD->getAnyBaseClassToDestroy(BaseOrMember)->getAs<RecordType>();
665      CXXRecordDecl *BaseClassDecl = cast<CXXRecordDecl>(RT->getDecl());
666      if (BaseClassDecl->hasTrivialDestructor())
667        continue;
668      llvm::Value *V = AddressCXXOfBaseClass(LoadCXXThis(),
669                                             ClassDecl,BaseClassDecl);
670      EmitCXXDestructorCall(BaseClassDecl->getDestructor(getContext()),
671                            Dtor_Complete, V);
672    }
673  }
674}
675