CGDeclCXX.cpp revision 88d117c2eedd7c5bec57ac983a98d5e12bdd2cc6 
1//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ 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 code generation of C++ declarations
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CGObjCRuntime.h"
16#include "CGCXXABI.h"
17#include "clang/Frontend/CodeGenOptions.h"
18#include "llvm/Intrinsics.h"
19
20using namespace clang;
21using namespace CodeGen;
22
23static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
24                         llvm::Constant *DeclPtr) {
25  assert(D.hasGlobalStorage() && "VarDecl must have global storage!");
26  assert(!D.getType()->isReferenceType() &&
27         "Should not call EmitDeclInit on a reference!");
28
29  ASTContext &Context = CGF.getContext();
30
31  const Expr *Init = D.getInit();
32  QualType T = D.getType();
33  bool isVolatile = Context.getCanonicalType(T).isVolatileQualified();
34
35  unsigned Alignment = Context.getDeclAlign(&D).getQuantity();
36  if (!CGF.hasAggregateLLVMType(T)) {
37    llvm::Value *V = CGF.EmitScalarExpr(Init);
38    CodeGenModule &CGM = CGF.CGM;
39    Qualifiers::GC GCAttr = CGM.getContext().getObjCGCAttrKind(T);
40    if (GCAttr == Qualifiers::Strong)
41      CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, V, DeclPtr,
42                                                D.isThreadSpecified());
43    else if (GCAttr == Qualifiers::Weak)
44      CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, V, DeclPtr);
45    else
46      CGF.EmitStoreOfScalar(V, DeclPtr, isVolatile, Alignment, T);
47  } else if (T->isAnyComplexType()) {
48    CGF.EmitComplexExprIntoAddr(Init, DeclPtr, isVolatile);
49  } else {
50    CGF.EmitAggExpr(Init, AggValueSlot::forAddr(DeclPtr, isVolatile, true));
51  }
52}
53
54/// Emit code to cause the destruction of the given variable with
55/// static storage duration.
56static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
57                            llvm::Constant *DeclPtr) {
58  CodeGenModule &CGM = CGF.CGM;
59  ASTContext &Context = CGF.getContext();
60
61  QualType T = D.getType();
62
63  // Drill down past array types.
64  const ConstantArrayType *Array = Context.getAsConstantArrayType(T);
65  if (Array)
66    T = Context.getBaseElementType(Array);
67
68  /// If that's not a record, we're done.
69  /// FIXME:  __attribute__((cleanup)) ?
70  const RecordType *RT = T->getAs<RecordType>();
71  if (!RT)
72    return;
73
74  CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
75  if (RD->hasTrivialDestructor())
76    return;
77
78  CXXDestructorDecl *Dtor = RD->getDestructor();
79
80  llvm::Constant *DtorFn;
81  if (Array) {
82    DtorFn =
83      CodeGenFunction(CGM).GenerateCXXAggrDestructorHelper(Dtor, Array,
84                                                           DeclPtr);
85    const llvm::Type *Int8PtrTy =
86      llvm::Type::getInt8PtrTy(CGM.getLLVMContext());
87    DeclPtr = llvm::Constant::getNullValue(Int8PtrTy);
88  } else
89    DtorFn = CGM.GetAddrOfCXXDestructor(Dtor, Dtor_Complete);
90
91  CGF.EmitCXXGlobalDtorRegistration(DtorFn, DeclPtr);
92}
93
94void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
95                                               llvm::Constant *DeclPtr) {
96
97  const Expr *Init = D.getInit();
98  QualType T = D.getType();
99
100  if (!T->isReferenceType()) {
101    EmitDeclInit(*this, D, DeclPtr);
102    EmitDeclDestroy(*this, D, DeclPtr);
103    return;
104  }
105
106  unsigned Alignment = getContext().getDeclAlign(&D).getQuantity();
107  RValue RV = EmitReferenceBindingToExpr(Init, &D);
108  EmitStoreOfScalar(RV.getScalarVal(), DeclPtr, false, Alignment, T);
109}
110
111void
112CodeGenFunction::EmitCXXGlobalDtorRegistration(llvm::Constant *DtorFn,
113                                               llvm::Constant *DeclPtr) {
114  // Generate a global destructor entry if not using __cxa_atexit.
115  if (!CGM.getCodeGenOpts().CXAAtExit) {
116    CGM.AddCXXDtorEntry(DtorFn, DeclPtr);
117    return;
118  }
119
120  std::vector<const llvm::Type *> Params;
121  Params.push_back(Int8PtrTy);
122
123  // Get the destructor function type
124  const llvm::Type *DtorFnTy =
125    llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()),
126                            Params, false);
127  DtorFnTy = llvm::PointerType::getUnqual(DtorFnTy);
128
129  Params.clear();
130  Params.push_back(DtorFnTy);
131  Params.push_back(Int8PtrTy);
132  Params.push_back(Int8PtrTy);
133
134  // Get the __cxa_atexit function type
135  // extern "C" int __cxa_atexit ( void (*f)(void *), void *p, void *d );
136  const llvm::FunctionType *AtExitFnTy =
137    llvm::FunctionType::get(ConvertType(getContext().IntTy), Params, false);
138
139  llvm::Constant *AtExitFn = CGM.CreateRuntimeFunction(AtExitFnTy,
140                                                       "__cxa_atexit");
141
142  llvm::Constant *Handle = CGM.CreateRuntimeVariable(Int8PtrTy,
143                                                     "__dso_handle");
144  llvm::Value *Args[3] = { llvm::ConstantExpr::getBitCast(DtorFn, DtorFnTy),
145                           llvm::ConstantExpr::getBitCast(DeclPtr, Int8PtrTy),
146                           llvm::ConstantExpr::getBitCast(Handle, Int8PtrTy) };
147  Builder.CreateCall(AtExitFn, &Args[0], llvm::array_endof(Args));
148}
149
150void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D,
151                                         llvm::GlobalVariable *DeclPtr) {
152  CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr);
153}
154
155static llvm::Function *
156CreateGlobalInitOrDestructFunction(CodeGenModule &CGM,
157                                   const llvm::FunctionType *FTy,
158                                   llvm::StringRef Name) {
159  llvm::Function *Fn =
160    llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
161                           Name, &CGM.getModule());
162  if (!CGM.getContext().getLangOptions().AppleKext) {
163    // Set the section if needed.
164    if (const char *Section =
165          CGM.getContext().Target.getStaticInitSectionSpecifier())
166      Fn->setSection(Section);
167  }
168
169  if (!CGM.getLangOptions().Exceptions)
170    Fn->setDoesNotThrow();
171
172  return Fn;
173}
174
175void
176CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
177                                            llvm::GlobalVariable *Addr) {
178  const llvm::FunctionType *FTy
179    = llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
180                              false);
181
182  // Create a variable initialization function.
183  llvm::Function *Fn =
184    CreateGlobalInitOrDestructFunction(*this, FTy, "__cxx_global_var_init");
185
186  CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr);
187
188  if (D->hasAttr<InitPriorityAttr>()) {
189    unsigned int order = D->getAttr<InitPriorityAttr>()->getPriority();
190    OrderGlobalInits Key(order, PrioritizedCXXGlobalInits.size());
191    PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
192    DelayedCXXInitPosition.erase(D);
193  }
194  else {
195    llvm::DenseMap<const Decl *, unsigned>::iterator I =
196      DelayedCXXInitPosition.find(D);
197    if (I == DelayedCXXInitPosition.end()) {
198      CXXGlobalInits.push_back(Fn);
199    } else {
200      assert(CXXGlobalInits[I->second] == 0);
201      CXXGlobalInits[I->second] = Fn;
202      DelayedCXXInitPosition.erase(I);
203    }
204  }
205}
206
207void
208CodeGenModule::EmitCXXGlobalInitFunc() {
209  while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
210    CXXGlobalInits.pop_back();
211
212  if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
213    return;
214
215  const llvm::FunctionType *FTy
216    = llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
217                              false);
218
219  // Create our global initialization function.
220  llvm::Function *Fn =
221    CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__I_a");
222
223  if (!PrioritizedCXXGlobalInits.empty()) {
224    llvm::SmallVector<llvm::Constant*, 8> LocalCXXGlobalInits;
225    llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
226                         PrioritizedCXXGlobalInits.end());
227    for (unsigned i = 0; i < PrioritizedCXXGlobalInits.size(); i++) {
228      llvm::Function *Fn = PrioritizedCXXGlobalInits[i].second;
229      LocalCXXGlobalInits.push_back(Fn);
230    }
231    LocalCXXGlobalInits.append(CXXGlobalInits.begin(), CXXGlobalInits.end());
232    CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
233                                                    &LocalCXXGlobalInits[0],
234                                                    LocalCXXGlobalInits.size());
235  }
236  else
237    CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
238                                                     &CXXGlobalInits[0],
239                                                     CXXGlobalInits.size());
240  AddGlobalCtor(Fn);
241}
242
243void CodeGenModule::EmitCXXGlobalDtorFunc() {
244  if (CXXGlobalDtors.empty())
245    return;
246
247  const llvm::FunctionType *FTy
248    = llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext),
249                              false);
250
251  // Create our global destructor function.
252  llvm::Function *Fn =
253    CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__D_a");
254
255  CodeGenFunction(*this).GenerateCXXGlobalDtorFunc(Fn, CXXGlobalDtors);
256  AddGlobalDtor(Fn);
257}
258
259/// Emit the code necessary to initialize the given global variable.
260void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
261                                                       const VarDecl *D,
262                                                 llvm::GlobalVariable *Addr) {
263  StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
264                SourceLocation(), CC_Default);
265
266  // Use guarded initialization if the global variable is weak due to
267  // being a class template's static data member.
268  if (Addr->hasWeakLinkage() && D->getInstantiatedFromStaticDataMember()) {
269    EmitCXXGuardedInit(*D, Addr);
270  } else {
271    EmitCXXGlobalVarDeclInit(*D, Addr);
272  }
273
274  FinishFunction();
275}
276
277void CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
278                                                llvm::Constant **Decls,
279                                                unsigned NumDecls) {
280  StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
281                SourceLocation(), CC_Default);
282
283  for (unsigned i = 0; i != NumDecls; ++i)
284    if (Decls[i])
285      Builder.CreateCall(Decls[i]);
286
287  FinishFunction();
288}
289
290void CodeGenFunction::GenerateCXXGlobalDtorFunc(llvm::Function *Fn,
291                  const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> >
292                                                &DtorsAndObjects) {
293  const bool IsWin64 = getContext().Target.isWin64();
294
295  StartFunction(GlobalDecl(), getContext().VoidTy, Fn, FunctionArgList(),
296                SourceLocation(), IsWin64 ? CC_Win64ThisCall : CC_Default);
297
298  // Emit the dtors, in reverse order from construction.
299  for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
300    llvm::Value *Callee = DtorsAndObjects[e - i - 1].first;
301    llvm::CallInst *CI = Builder.CreateCall(Callee,
302                                            DtorsAndObjects[e - i - 1].second);
303    // Make sure the call and the callee agree on calling convention.
304    if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
305      CI->setCallingConv(F->getCallingConv());
306  }
307
308  FinishFunction();
309}
310
311/// GenerateCXXAggrDestructorHelper - Generates a helper function which when
312/// invoked, calls the default destructor on array elements in reverse order of
313/// construction.
314llvm::Function *
315CodeGenFunction::GenerateCXXAggrDestructorHelper(const CXXDestructorDecl *D,
316                                                 const ArrayType *Array,
317                                                 llvm::Value *This) {
318  FunctionArgList Args;
319  ImplicitParamDecl *Dst =
320    ImplicitParamDecl::Create(getContext(), 0,
321                              SourceLocation(), 0,
322                              getContext().getPointerType(getContext().VoidTy));
323  Args.push_back(std::make_pair(Dst, Dst->getType()));
324
325  const CGFunctionInfo &FI =
326    CGM.getTypes().getFunctionInfo(getContext().VoidTy, Args,
327                                   FunctionType::ExtInfo());
328  const llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI, false);
329  llvm::Function *Fn =
330    CreateGlobalInitOrDestructFunction(CGM, FTy, "__cxx_global_array_dtor");
331
332  StartFunction(GlobalDecl(), getContext().VoidTy, Fn, Args, SourceLocation(),
333                CC_Default);
334
335  QualType BaseElementTy = getContext().getBaseElementType(Array);
336  const llvm::Type *BasePtr = ConvertType(BaseElementTy)->getPointerTo();
337  llvm::Value *BaseAddrPtr = Builder.CreateBitCast(This, BasePtr);
338
339  EmitCXXAggrDestructorCall(D, Array, BaseAddrPtr);
340
341  FinishFunction();
342
343  return Fn;
344}
345