CGCXX.cpp revision 8e51a1f5da6ef4a1a168d14116c6eed3a578a263 
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 "clang/AST/StmtCXX.h"
25#include "llvm/ADT/StringExtras.h"
26using namespace clang;
27using namespace CodeGen;
28
29
30
31void CodeGenModule::EmitCXXConstructors(const CXXConstructorDecl *D) {
32  EmitGlobal(GlobalDecl(D, Ctor_Complete));
33  EmitGlobal(GlobalDecl(D, Ctor_Base));
34}
35
36void CodeGenModule::EmitCXXConstructor(const CXXConstructorDecl *D,
37                                       CXXCtorType Type) {
38
39  llvm::Function *Fn = GetAddrOfCXXConstructor(D, Type);
40
41  CodeGenFunction(*this).GenerateCode(GlobalDecl(D, Type), Fn);
42
43  SetFunctionDefinitionAttributes(D, Fn);
44  SetLLVMFunctionAttributesForDefinition(D, Fn);
45}
46
47llvm::Function *
48CodeGenModule::GetAddrOfCXXConstructor(const CXXConstructorDecl *D,
49                                       CXXCtorType Type) {
50  const FunctionProtoType *FPT = D->getType()->getAs<FunctionProtoType>();
51  const llvm::FunctionType *FTy =
52    getTypes().GetFunctionType(getTypes().getFunctionInfo(D, Type),
53                               FPT->isVariadic());
54
55  const char *Name = getMangledCXXCtorName(D, Type);
56  return cast<llvm::Function>(
57                      GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(D, Type)));
58}
59
60const char *CodeGenModule::getMangledCXXCtorName(const CXXConstructorDecl *D,
61                                                 CXXCtorType Type) {
62  llvm::SmallString<256> Name;
63  getMangleContext().mangleCXXCtor(D, Type, Name);
64
65  Name += '\0';
66  return UniqueMangledName(Name.begin(), Name.end());
67}
68
69void CodeGenModule::EmitCXXDestructors(const CXXDestructorDecl *D) {
70  if (D->isVirtual())
71    EmitGlobal(GlobalDecl(D, Dtor_Deleting));
72  EmitGlobal(GlobalDecl(D, Dtor_Complete));
73  EmitGlobal(GlobalDecl(D, Dtor_Base));
74}
75
76void CodeGenModule::EmitCXXDestructor(const CXXDestructorDecl *D,
77                                      CXXDtorType Type) {
78  llvm::Function *Fn = GetAddrOfCXXDestructor(D, Type);
79
80  CodeGenFunction(*this).GenerateCode(GlobalDecl(D, Type), Fn);
81
82  SetFunctionDefinitionAttributes(D, Fn);
83  SetLLVMFunctionAttributesForDefinition(D, Fn);
84}
85
86llvm::Function *
87CodeGenModule::GetAddrOfCXXDestructor(const CXXDestructorDecl *D,
88                                      CXXDtorType Type) {
89  const llvm::FunctionType *FTy =
90    getTypes().GetFunctionType(getTypes().getFunctionInfo(D, Type), false);
91
92  const char *Name = getMangledCXXDtorName(D, Type);
93  return cast<llvm::Function>(
94                      GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(D, Type)));
95}
96
97const char *CodeGenModule::getMangledCXXDtorName(const CXXDestructorDecl *D,
98                                                 CXXDtorType Type) {
99  llvm::SmallString<256> Name;
100  getMangleContext().mangleCXXDtor(D, Type, Name);
101
102  Name += '\0';
103  return UniqueMangledName(Name.begin(), Name.end());
104}
105
106llvm::Constant *
107CodeGenFunction::GenerateThunk(llvm::Function *Fn, GlobalDecl GD,
108                               bool Extern,
109                               const ThunkAdjustment &ThisAdjustment) {
110  return GenerateCovariantThunk(Fn, GD, Extern,
111                                CovariantThunkAdjustment(ThisAdjustment,
112                                                         ThunkAdjustment()));
113}
114
115llvm::Value *
116CodeGenFunction::DynamicTypeAdjust(llvm::Value *V,
117                                   const ThunkAdjustment &Adjustment) {
118  const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
119
120  const llvm::Type *OrigTy = V->getType();
121  if (Adjustment.NonVirtual) {
122    // Do the non-virtual adjustment
123    V = Builder.CreateBitCast(V, Int8PtrTy);
124    V = Builder.CreateConstInBoundsGEP1_64(V, Adjustment.NonVirtual);
125    V = Builder.CreateBitCast(V, OrigTy);
126  }
127
128  if (!Adjustment.Virtual)
129    return V;
130
131  assert(Adjustment.Virtual % (LLVMPointerWidth / 8) == 0 &&
132         "vtable entry unaligned");
133
134  // Do the virtual this adjustment
135  const llvm::Type *PtrDiffTy = ConvertType(getContext().getPointerDiffType());
136  const llvm::Type *PtrDiffPtrTy = PtrDiffTy->getPointerTo();
137
138  llvm::Value *ThisVal = Builder.CreateBitCast(V, Int8PtrTy);
139  V = Builder.CreateBitCast(V, PtrDiffPtrTy->getPointerTo());
140  V = Builder.CreateLoad(V, "vtable");
141
142  llvm::Value *VTablePtr = V;
143  uint64_t VirtualAdjustment = Adjustment.Virtual / (LLVMPointerWidth / 8);
144  V = Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment);
145  V = Builder.CreateLoad(V);
146  V = Builder.CreateGEP(ThisVal, V);
147
148  return Builder.CreateBitCast(V, OrigTy);
149}
150
151llvm::Constant *
152CodeGenFunction::GenerateCovariantThunk(llvm::Function *Fn,
153                                   GlobalDecl GD, bool Extern,
154                                   const CovariantThunkAdjustment &Adjustment) {
155  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
156  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
157  QualType ResultType = FPT->getResultType();
158
159  FunctionArgList Args;
160  ImplicitParamDecl *ThisDecl =
161    ImplicitParamDecl::Create(getContext(), 0, SourceLocation(), 0,
162                              MD->getThisType(getContext()));
163  Args.push_back(std::make_pair(ThisDecl, ThisDecl->getType()));
164  for (FunctionDecl::param_const_iterator i = MD->param_begin(),
165         e = MD->param_end();
166       i != e; ++i) {
167    ParmVarDecl *D = *i;
168    Args.push_back(std::make_pair(D, D->getType()));
169  }
170  IdentifierInfo *II
171    = &CGM.getContext().Idents.get("__thunk_named_foo_");
172  FunctionDecl *FD = FunctionDecl::Create(getContext(),
173                                          getContext().getTranslationUnitDecl(),
174                                          SourceLocation(), II, ResultType, 0,
175                                          Extern
176                                            ? FunctionDecl::Extern
177                                            : FunctionDecl::Static,
178                                          false, true);
179  StartFunction(FD, ResultType, Fn, Args, SourceLocation());
180
181  // generate body
182  const llvm::Type *Ty =
183    CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(MD),
184                                   FPT->isVariadic());
185  llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty);
186
187  CallArgList CallArgs;
188
189  bool ShouldAdjustReturnPointer = true;
190  QualType ArgType = MD->getThisType(getContext());
191  llvm::Value *Arg = Builder.CreateLoad(LocalDeclMap[ThisDecl], "this");
192  if (!Adjustment.ThisAdjustment.isEmpty()) {
193    // Do the this adjustment.
194    const llvm::Type *OrigTy = Callee->getType();
195    Arg = DynamicTypeAdjust(Arg, Adjustment.ThisAdjustment);
196
197    if (!Adjustment.ReturnAdjustment.isEmpty()) {
198      const CovariantThunkAdjustment &ReturnAdjustment =
199        CovariantThunkAdjustment(ThunkAdjustment(),
200                                 Adjustment.ReturnAdjustment);
201
202      Callee = CGM.BuildCovariantThunk(GD, Extern, ReturnAdjustment);
203
204      Callee = Builder.CreateBitCast(Callee, OrigTy);
205      ShouldAdjustReturnPointer = false;
206    }
207  }
208
209  CallArgs.push_back(std::make_pair(RValue::get(Arg), ArgType));
210
211  for (FunctionDecl::param_const_iterator i = MD->param_begin(),
212         e = MD->param_end();
213       i != e; ++i) {
214    ParmVarDecl *D = *i;
215    QualType ArgType = D->getType();
216
217    // llvm::Value *Arg = CGF.GetAddrOfLocalVar(Dst);
218    Expr *Arg = new (getContext()) DeclRefExpr(D, ArgType.getNonReferenceType(),
219                                               SourceLocation());
220    CallArgs.push_back(std::make_pair(EmitCallArg(Arg, ArgType), ArgType));
221  }
222
223  RValue RV = EmitCall(CGM.getTypes().getFunctionInfo(ResultType, CallArgs,
224                                                      FPT->getCallConv(),
225                                                      FPT->getNoReturnAttr()),
226                       Callee, ReturnValueSlot(), CallArgs, MD);
227  if (ShouldAdjustReturnPointer && !Adjustment.ReturnAdjustment.isEmpty()) {
228    bool CanBeZero = !(ResultType->isReferenceType()
229    // FIXME: attr nonnull can't be zero either
230                       /* || ResultType->hasAttr<NonNullAttr>() */ );
231    // Do the return result adjustment.
232    if (CanBeZero) {
233      llvm::BasicBlock *NonZeroBlock = createBasicBlock();
234      llvm::BasicBlock *ZeroBlock = createBasicBlock();
235      llvm::BasicBlock *ContBlock = createBasicBlock();
236
237      const llvm::Type *Ty = RV.getScalarVal()->getType();
238      llvm::Value *Zero = llvm::Constant::getNullValue(Ty);
239      Builder.CreateCondBr(Builder.CreateICmpNE(RV.getScalarVal(), Zero),
240                           NonZeroBlock, ZeroBlock);
241      EmitBlock(NonZeroBlock);
242      llvm::Value *NZ =
243        DynamicTypeAdjust(RV.getScalarVal(), Adjustment.ReturnAdjustment);
244      EmitBranch(ContBlock);
245      EmitBlock(ZeroBlock);
246      llvm::Value *Z = RV.getScalarVal();
247      EmitBlock(ContBlock);
248      llvm::PHINode *RVOrZero = Builder.CreatePHI(Ty);
249      RVOrZero->reserveOperandSpace(2);
250      RVOrZero->addIncoming(NZ, NonZeroBlock);
251      RVOrZero->addIncoming(Z, ZeroBlock);
252      RV = RValue::get(RVOrZero);
253    } else
254      RV = RValue::get(DynamicTypeAdjust(RV.getScalarVal(),
255                                         Adjustment.ReturnAdjustment));
256  }
257
258  if (!ResultType->isVoidType())
259    EmitReturnOfRValue(RV, ResultType);
260
261  FinishFunction();
262  return Fn;
263}
264
265llvm::Constant *
266CodeGenModule::GetAddrOfThunk(GlobalDecl GD,
267                              const ThunkAdjustment &ThisAdjustment) {
268  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
269
270  // Compute mangled name
271  llvm::SmallString<256> OutName;
272  if (const CXXDestructorDecl* DD = dyn_cast<CXXDestructorDecl>(MD))
273    getMangleContext().mangleCXXDtorThunk(DD, GD.getDtorType(), ThisAdjustment,
274                                          OutName);
275  else
276    getMangleContext().mangleThunk(MD, ThisAdjustment, OutName);
277  OutName += '\0';
278  const char* Name = UniqueMangledName(OutName.begin(), OutName.end());
279
280  // Get function for mangled name
281  const llvm::Type *Ty = getTypes().GetFunctionTypeForVtable(MD);
282  return GetOrCreateLLVMFunction(Name, Ty, GlobalDecl());
283}
284
285llvm::Constant *
286CodeGenModule::GetAddrOfCovariantThunk(GlobalDecl GD,
287                                   const CovariantThunkAdjustment &Adjustment) {
288  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
289
290  // Compute mangled name
291  llvm::SmallString<256> OutName;
292  getMangleContext().mangleCovariantThunk(MD, Adjustment, OutName);
293  OutName += '\0';
294  const char* Name = UniqueMangledName(OutName.begin(), OutName.end());
295
296  // Get function for mangled name
297  const llvm::Type *Ty = getTypes().GetFunctionTypeForVtable(MD);
298  return GetOrCreateLLVMFunction(Name, Ty, GlobalDecl());
299}
300
301void CodeGenModule::BuildThunksForVirtual(GlobalDecl GD) {
302  CGVtableInfo::AdjustmentVectorTy *AdjPtr = getVtableInfo().getAdjustments(GD);
303  if (!AdjPtr)
304    return;
305  CGVtableInfo::AdjustmentVectorTy &Adj = *AdjPtr;
306  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
307  for (unsigned i = 0; i < Adj.size(); i++) {
308    GlobalDecl OGD = Adj[i].first;
309    const CXXMethodDecl *OMD = cast<CXXMethodDecl>(OGD.getDecl());
310    QualType nc_oret = OMD->getType()->getAs<FunctionType>()->getResultType();
311    CanQualType oret = getContext().getCanonicalType(nc_oret);
312    QualType nc_ret = MD->getType()->getAs<FunctionType>()->getResultType();
313    CanQualType ret = getContext().getCanonicalType(nc_ret);
314    ThunkAdjustment ReturnAdjustment;
315    if (oret != ret) {
316      QualType qD = nc_ret->getPointeeType();
317      QualType qB = nc_oret->getPointeeType();
318      CXXRecordDecl *D = cast<CXXRecordDecl>(qD->getAs<RecordType>()->getDecl());
319      CXXRecordDecl *B = cast<CXXRecordDecl>(qB->getAs<RecordType>()->getDecl());
320      ReturnAdjustment = ComputeThunkAdjustment(D, B);
321    }
322    ThunkAdjustment ThisAdjustment = Adj[i].second;
323    bool Extern = !cast<CXXRecordDecl>(OMD->getDeclContext())->isInAnonymousNamespace();
324    if (!ReturnAdjustment.isEmpty() || !ThisAdjustment.isEmpty()) {
325      CovariantThunkAdjustment CoAdj(ThisAdjustment, ReturnAdjustment);
326      llvm::Constant *FnConst;
327      if (!ReturnAdjustment.isEmpty())
328        FnConst = GetAddrOfCovariantThunk(GD, CoAdj);
329      else
330        FnConst = GetAddrOfThunk(GD, ThisAdjustment);
331      if (!isa<llvm::Function>(FnConst)) {
332        llvm::Constant *SubExpr =
333            cast<llvm::ConstantExpr>(FnConst)->getOperand(0);
334        llvm::Function *OldFn = cast<llvm::Function>(SubExpr);
335        std::string Name = OldFn->getNameStr();
336        GlobalDeclMap.erase(UniqueMangledName(Name.data(),
337                                              Name.data() + Name.size() + 1));
338        llvm::Constant *NewFnConst;
339        if (!ReturnAdjustment.isEmpty())
340          NewFnConst = GetAddrOfCovariantThunk(GD, CoAdj);
341        else
342          NewFnConst = GetAddrOfThunk(GD, ThisAdjustment);
343        llvm::Function *NewFn = cast<llvm::Function>(NewFnConst);
344        NewFn->takeName(OldFn);
345        llvm::Constant *NewPtrForOldDecl =
346            llvm::ConstantExpr::getBitCast(NewFn, OldFn->getType());
347        OldFn->replaceAllUsesWith(NewPtrForOldDecl);
348        OldFn->eraseFromParent();
349        FnConst = NewFn;
350      }
351      llvm::Function *Fn = cast<llvm::Function>(FnConst);
352      if (Fn->isDeclaration()) {
353        llvm::GlobalVariable::LinkageTypes linktype;
354        linktype = llvm::GlobalValue::WeakAnyLinkage;
355        if (!Extern)
356          linktype = llvm::GlobalValue::InternalLinkage;
357        Fn->setLinkage(linktype);
358        if (!Features.Exceptions && !Features.ObjCNonFragileABI)
359          Fn->addFnAttr(llvm::Attribute::NoUnwind);
360        Fn->setAlignment(2);
361        CodeGenFunction(*this).GenerateCovariantThunk(Fn, GD, Extern, CoAdj);
362      }
363    }
364  }
365}
366
367llvm::Constant *
368CodeGenModule::BuildThunk(GlobalDecl GD, bool Extern,
369                          const ThunkAdjustment &ThisAdjustment) {
370  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
371  llvm::SmallString<256> OutName;
372  if (const CXXDestructorDecl *D = dyn_cast<CXXDestructorDecl>(MD)) {
373    getMangleContext().mangleCXXDtorThunk(D, GD.getDtorType(), ThisAdjustment,
374                                          OutName);
375  } else
376    getMangleContext().mangleThunk(MD, ThisAdjustment, OutName);
377
378  llvm::GlobalVariable::LinkageTypes linktype;
379  linktype = llvm::GlobalValue::WeakAnyLinkage;
380  if (!Extern)
381    linktype = llvm::GlobalValue::InternalLinkage;
382  llvm::Type *Ptr8Ty=llvm::PointerType::get(llvm::Type::getInt8Ty(VMContext),0);
383  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
384  const llvm::FunctionType *FTy =
385    getTypes().GetFunctionType(getTypes().getFunctionInfo(MD),
386                               FPT->isVariadic());
387
388  llvm::Function *Fn = llvm::Function::Create(FTy, linktype, OutName.str(),
389                                              &getModule());
390  CodeGenFunction(*this).GenerateThunk(Fn, GD, Extern, ThisAdjustment);
391  llvm::Constant *m = llvm::ConstantExpr::getBitCast(Fn, Ptr8Ty);
392  return m;
393}
394
395llvm::Constant *
396CodeGenModule::BuildCovariantThunk(const GlobalDecl &GD, bool Extern,
397                                   const CovariantThunkAdjustment &Adjustment) {
398  const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
399  llvm::SmallString<256> OutName;
400  getMangleContext().mangleCovariantThunk(MD, Adjustment, OutName);
401  llvm::GlobalVariable::LinkageTypes linktype;
402  linktype = llvm::GlobalValue::WeakAnyLinkage;
403  if (!Extern)
404    linktype = llvm::GlobalValue::InternalLinkage;
405  llvm::Type *Ptr8Ty=llvm::PointerType::get(llvm::Type::getInt8Ty(VMContext),0);
406  const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
407  const llvm::FunctionType *FTy =
408    getTypes().GetFunctionType(getTypes().getFunctionInfo(MD),
409                               FPT->isVariadic());
410
411  llvm::Function *Fn = llvm::Function::Create(FTy, linktype, OutName.str(),
412                                              &getModule());
413  CodeGenFunction(*this).GenerateCovariantThunk(Fn, MD, Extern, Adjustment);
414  llvm::Constant *m = llvm::ConstantExpr::getBitCast(Fn, Ptr8Ty);
415  return m;
416}
417
418static llvm::Value *BuildVirtualCall(CodeGenFunction &CGF, uint64_t VtableIndex,
419                                     llvm::Value *This, const llvm::Type *Ty) {
420  Ty = Ty->getPointerTo()->getPointerTo()->getPointerTo();
421
422  llvm::Value *Vtable = CGF.Builder.CreateBitCast(This, Ty);
423  Vtable = CGF.Builder.CreateLoad(Vtable);
424
425  llvm::Value *VFuncPtr =
426    CGF.Builder.CreateConstInBoundsGEP1_64(Vtable, VtableIndex, "vfn");
427  return CGF.Builder.CreateLoad(VFuncPtr);
428}
429
430llvm::Value *
431CodeGenFunction::BuildVirtualCall(const CXXMethodDecl *MD, llvm::Value *This,
432                                  const llvm::Type *Ty) {
433  MD = MD->getCanonicalDecl();
434  uint64_t VtableIndex = CGM.getVtableInfo().getMethodVtableIndex(MD);
435
436  return ::BuildVirtualCall(*this, VtableIndex, This, Ty);
437}
438
439llvm::Value *
440CodeGenFunction::BuildVirtualCall(const CXXDestructorDecl *DD, CXXDtorType Type,
441                                  llvm::Value *&This, const llvm::Type *Ty) {
442  DD = cast<CXXDestructorDecl>(DD->getCanonicalDecl());
443  uint64_t VtableIndex =
444    CGM.getVtableInfo().getMethodVtableIndex(GlobalDecl(DD, Type));
445
446  return ::BuildVirtualCall(*this, VtableIndex, This, Ty);
447}
448