CGCXX.cpp revision 17945a0f64fe03ff6ec0c2146005a87636e3ac12 
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/Decl.h"
21#include "clang/AST/DeclCXX.h"
22#include "clang/AST/DeclObjC.h"
23#include "llvm/ADT/StringExtras.h"
24using namespace clang;
25using namespace CodeGen;
26
27void
28CodeGenFunction::GenerateStaticCXXBlockVarDeclInit(const VarDecl &D,
29                                                   llvm::GlobalVariable *GV) {
30  // FIXME: This should use __cxa_guard_{acquire,release}?
31
32  assert(!getContext().getLangOptions().ThreadsafeStatics &&
33         "thread safe statics are currently not supported!");
34
35  llvm::SmallString<256> GuardVName;
36  llvm::raw_svector_ostream GuardVOut(GuardVName);
37  mangleGuardVariable(&D, getContext(), GuardVOut);
38
39  // Create the guard variable.
40  llvm::GlobalValue *GuardV =
41    new llvm::GlobalVariable(llvm::Type::Int64Ty, false,
42                             GV->getLinkage(),
43                             llvm::Constant::getNullValue(llvm::Type::Int64Ty),
44                             GuardVName.c_str(),
45                             &CGM.getModule());
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  const llvm::Type *Ty =
110    CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(MD),
111                                   FPT->isVariadic());
112  llvm::Constant *Callee = CGM.GetAddrOfFunction(GlobalDecl(MD), Ty);
113
114  llvm::Value *This;
115
116  if (ME->isArrow())
117    This = EmitScalarExpr(ME->getBase());
118  else {
119    LValue BaseLV = EmitLValue(ME->getBase());
120    This = BaseLV.getAddress();
121  }
122
123  return EmitCXXMemberCall(MD, Callee, This,
124                           CE->arg_begin(), CE->arg_end());
125}
126
127RValue
128CodeGenFunction::EmitCXXOperatorMemberCallExpr(const CXXOperatorCallExpr *E,
129                                               const CXXMethodDecl *MD) {
130  assert(MD->isInstance() &&
131         "Trying to emit a member call expr on a static method!");
132
133
134  const FunctionProtoType *FPT = MD->getType()->getAsFunctionProtoType();
135  const llvm::Type *Ty =
136  CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(MD),
137                                 FPT->isVariadic());
138  llvm::Constant *Callee = CGM.GetAddrOfFunction(GlobalDecl(MD), Ty);
139
140  llvm::Value *This = EmitLValue(E->getArg(0)).getAddress();
141
142  return EmitCXXMemberCall(MD, Callee, This,
143                           E->arg_begin() + 1, E->arg_end());
144}
145
146llvm::Value *CodeGenFunction::LoadCXXThis() {
147  assert(isa<CXXMethodDecl>(CurFuncDecl) &&
148         "Must be in a C++ member function decl to load 'this'");
149  assert(cast<CXXMethodDecl>(CurFuncDecl)->isInstance() &&
150         "Must be in a C++ member function decl to load 'this'");
151
152  // FIXME: What if we're inside a block?
153  // ans: See how CodeGenFunction::LoadObjCSelf() uses
154  // CodeGenFunction::BlockForwardSelf() for how to do this.
155  return Builder.CreateLoad(LocalDeclMap[CXXThisDecl], "this");
156}
157
158void
159CodeGenFunction::EmitCXXConstructorCall(const CXXConstructorDecl *D,
160                                        CXXCtorType Type,
161                                        llvm::Value *This,
162                                        CallExpr::const_arg_iterator ArgBeg,
163                                        CallExpr::const_arg_iterator ArgEnd) {
164  llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D, Type);
165
166  EmitCXXMemberCall(D, Callee, This, ArgBeg, ArgEnd);
167}
168
169void CodeGenFunction::EmitCXXDestructorCall(const CXXDestructorDecl *D,
170                                            CXXDtorType Type,
171                                            llvm::Value *This) {
172  llvm::Value *Callee = CGM.GetAddrOfCXXDestructor(D, Type);
173
174  EmitCXXMemberCall(D, Callee, This, 0, 0);
175}
176
177void
178CodeGenFunction::EmitCXXConstructExpr(llvm::Value *Dest,
179                                      const CXXConstructExpr *E) {
180  assert(Dest && "Must have a destination!");
181
182  const CXXRecordDecl *RD =
183  cast<CXXRecordDecl>(E->getType()->getAsRecordType()->getDecl());
184  if (RD->hasTrivialConstructor())
185    return;
186
187  // Call the constructor.
188  EmitCXXConstructorCall(E->getConstructor(), Ctor_Complete, Dest,
189                         E->arg_begin(), E->arg_end());
190}
191
192llvm::Value *CodeGenFunction::EmitCXXNewExpr(const CXXNewExpr *E) {
193  if (E->isArray()) {
194    ErrorUnsupported(E, "new[] expression");
195    return llvm::UndefValue::get(ConvertType(E->getType()));
196  }
197
198  QualType AllocType = E->getAllocatedType();
199  FunctionDecl *NewFD = E->getOperatorNew();
200  const FunctionProtoType *NewFTy = NewFD->getType()->getAsFunctionProtoType();
201
202  CallArgList NewArgs;
203
204  // The allocation size is the first argument.
205  QualType SizeTy = getContext().getSizeType();
206  llvm::Value *AllocSize =
207    llvm::ConstantInt::get(ConvertType(SizeTy),
208                           getContext().getTypeSize(AllocType) / 8);
209
210  NewArgs.push_back(std::make_pair(RValue::get(AllocSize), SizeTy));
211
212  // Emit the rest of the arguments.
213  // FIXME: Ideally, this should just use EmitCallArgs.
214  CXXNewExpr::const_arg_iterator NewArg = E->placement_arg_begin();
215
216  // First, use the types from the function type.
217  // We start at 1 here because the first argument (the allocation size)
218  // has already been emitted.
219  for (unsigned i = 1, e = NewFTy->getNumArgs(); i != e; ++i, ++NewArg) {
220    QualType ArgType = NewFTy->getArgType(i);
221
222    assert(getContext().getCanonicalType(ArgType.getNonReferenceType()).
223           getTypePtr() ==
224           getContext().getCanonicalType(NewArg->getType()).getTypePtr() &&
225           "type mismatch in call argument!");
226
227    NewArgs.push_back(std::make_pair(EmitCallArg(*NewArg, ArgType),
228                                     ArgType));
229
230  }
231
232  // Either we've emitted all the call args, or we have a call to a
233  // variadic function.
234  assert((NewArg == E->placement_arg_end() || NewFTy->isVariadic()) &&
235         "Extra arguments in non-variadic function!");
236
237  // If we still have any arguments, emit them using the type of the argument.
238  for (CXXNewExpr::const_arg_iterator NewArgEnd = E->placement_arg_end();
239       NewArg != NewArgEnd; ++NewArg) {
240    QualType ArgType = NewArg->getType();
241    NewArgs.push_back(std::make_pair(EmitCallArg(*NewArg, ArgType),
242                                     ArgType));
243  }
244
245  // Emit the call to new.
246  RValue RV =
247    EmitCall(CGM.getTypes().getFunctionInfo(NewFTy->getResultType(), NewArgs),
248             CGM.GetAddrOfFunction(GlobalDecl(NewFD)),
249             NewArgs, NewFD);
250
251  // If an allocation function is declared with an empty exception specification
252  // it returns null to indicate failure to allocate storage. [expr.new]p13.
253  // (We don't need to check for null when there's no new initializer and
254  // we're allocating a POD type).
255  bool NullCheckResult = NewFTy->hasEmptyExceptionSpec() &&
256    !(AllocType->isPODType() && !E->hasInitializer());
257
258  llvm::BasicBlock *NewNull = 0;
259  llvm::BasicBlock *NewNotNull = 0;
260  llvm::BasicBlock *NewEnd = 0;
261
262  llvm::Value *NewPtr = RV.getScalarVal();
263
264  if (NullCheckResult) {
265    NewNull = createBasicBlock("new.null");
266    NewNotNull = createBasicBlock("new.notnull");
267    NewEnd = createBasicBlock("new.end");
268
269    llvm::Value *IsNull =
270      Builder.CreateICmpEQ(NewPtr,
271                           llvm::Constant::getNullValue(NewPtr->getType()),
272                           "isnull");
273
274    Builder.CreateCondBr(IsNull, NewNull, NewNotNull);
275    EmitBlock(NewNotNull);
276  }
277
278  NewPtr = Builder.CreateBitCast(NewPtr, ConvertType(E->getType()));
279
280  if (AllocType->isPODType()) {
281    if (E->getNumConstructorArgs() > 0) {
282      assert(E->getNumConstructorArgs() == 1 &&
283             "Can only have one argument to initializer of POD type.");
284
285      const Expr *Init = E->getConstructorArg(0);
286
287      if (!hasAggregateLLVMType(AllocType))
288        Builder.CreateStore(EmitScalarExpr(Init), NewPtr);
289      else if (AllocType->isAnyComplexType())
290        EmitComplexExprIntoAddr(Init, NewPtr, AllocType.isVolatileQualified());
291      else
292        EmitAggExpr(Init, NewPtr, AllocType.isVolatileQualified());
293    }
294  } else {
295    // Call the constructor.
296    CXXConstructorDecl *Ctor = E->getConstructor();
297
298    EmitCXXConstructorCall(Ctor, Ctor_Complete, NewPtr,
299                           E->constructor_arg_begin(),
300                           E->constructor_arg_end());
301  }
302
303  if (NullCheckResult) {
304    Builder.CreateBr(NewEnd);
305    EmitBlock(NewNull);
306    Builder.CreateBr(NewEnd);
307    EmitBlock(NewEnd);
308
309    llvm::PHINode *PHI = Builder.CreatePHI(NewPtr->getType());
310    PHI->reserveOperandSpace(2);
311    PHI->addIncoming(NewPtr, NewNotNull);
312    PHI->addIncoming(llvm::Constant::getNullValue(NewPtr->getType()), NewNull);
313
314    NewPtr = PHI;
315  }
316
317  return NewPtr;
318}
319
320static bool canGenerateCXXstructor(const CXXRecordDecl *RD,
321                                   ASTContext &Context) {
322  // The class has base classes - we don't support that right now.
323  if (RD->getNumBases() > 0)
324    return false;
325
326  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
327         I != E; ++I) {
328    // We don't support ctors for fields that aren't POD.
329    if (!I->getType()->isPODType())
330      return false;
331  }
332
333  return true;
334}
335
336void CodeGenModule::EmitCXXConstructors(const CXXConstructorDecl *D) {
337  if (!canGenerateCXXstructor(D->getParent(), getContext())) {
338    ErrorUnsupported(D, "C++ constructor", true);
339    return;
340  }
341
342  EmitGlobal(GlobalDecl(D, Ctor_Complete));
343  EmitGlobal(GlobalDecl(D, Ctor_Base));
344}
345
346void CodeGenModule::EmitCXXConstructor(const CXXConstructorDecl *D,
347                                       CXXCtorType Type) {
348
349  llvm::Function *Fn = GetAddrOfCXXConstructor(D, Type);
350
351  CodeGenFunction(*this).GenerateCode(D, Fn);
352
353  SetFunctionDefinitionAttributes(D, Fn);
354  SetLLVMFunctionAttributesForDefinition(D, Fn);
355}
356
357llvm::Function *
358CodeGenModule::GetAddrOfCXXConstructor(const CXXConstructorDecl *D,
359                                       CXXCtorType Type) {
360  const llvm::FunctionType *FTy =
361    getTypes().GetFunctionType(getTypes().getFunctionInfo(D), false);
362
363  const char *Name = getMangledCXXCtorName(D, Type);
364  return cast<llvm::Function>(
365                      GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(D, Type)));
366}
367
368const char *CodeGenModule::getMangledCXXCtorName(const CXXConstructorDecl *D,
369                                                 CXXCtorType Type) {
370  llvm::SmallString<256> Name;
371  llvm::raw_svector_ostream Out(Name);
372  mangleCXXCtor(D, Type, Context, Out);
373
374  Name += '\0';
375  return UniqueMangledName(Name.begin(), Name.end());
376}
377
378void CodeGenModule::EmitCXXDestructors(const CXXDestructorDecl *D) {
379  if (!canGenerateCXXstructor(D->getParent(), getContext())) {
380    ErrorUnsupported(D, "C++ destructor", true);
381    return;
382  }
383
384  EmitCXXDestructor(D, Dtor_Complete);
385  EmitCXXDestructor(D, Dtor_Base);
386}
387
388void CodeGenModule::EmitCXXDestructor(const CXXDestructorDecl *D,
389                                      CXXDtorType Type) {
390  llvm::Function *Fn = GetAddrOfCXXDestructor(D, Type);
391
392  CodeGenFunction(*this).GenerateCode(D, Fn);
393
394  SetFunctionDefinitionAttributes(D, Fn);
395  SetLLVMFunctionAttributesForDefinition(D, Fn);
396}
397
398llvm::Function *
399CodeGenModule::GetAddrOfCXXDestructor(const CXXDestructorDecl *D,
400                                      CXXDtorType Type) {
401  const llvm::FunctionType *FTy =
402    getTypes().GetFunctionType(getTypes().getFunctionInfo(D), false);
403
404  const char *Name = getMangledCXXDtorName(D, Type);
405  return cast<llvm::Function>(
406                      GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(D, Type)));
407}
408
409const char *CodeGenModule::getMangledCXXDtorName(const CXXDestructorDecl *D,
410                                                 CXXDtorType Type) {
411  llvm::SmallString<256> Name;
412  llvm::raw_svector_ostream Out(Name);
413  mangleCXXDtor(D, Type, Context, Out);
414
415  Name += '\0';
416  return UniqueMangledName(Name.begin(), Name.end());
417}
418