CGCXXABI.cpp revision de5d3c717684f3821b8db58037bc7140acf134aa 
1//===----- CGCXXABI.cpp - Interface to C++ ABIs -----------------*- C++ -*-===//
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 provides an abstract class for C++ code generation. Concrete subclasses
11// of this implement code generation for specific C++ ABIs.
12//
13//===----------------------------------------------------------------------===//
14
15#include "CGCXXABI.h"
16
17using namespace clang;
18using namespace CodeGen;
19
20CGCXXABI::~CGCXXABI() { }
21
22static void ErrorUnsupportedABI(CodeGenFunction &CGF,
23                                StringRef S) {
24  DiagnosticsEngine &Diags = CGF.CGM.getDiags();
25  unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
26                                          "cannot yet compile %1 in this ABI");
27  Diags.Report(CGF.getContext().getFullLoc(CGF.CurCodeDecl->getLocation()),
28               DiagID)
29    << S;
30}
31
32static llvm::Constant *GetBogusMemberPointer(CodeGenModule &CGM,
33                                             QualType T) {
34  return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T));
35}
36
37llvm::Type *
38CGCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
39  return CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
40}
41
42llvm::Value *CGCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
43                                                       llvm::Value *&This,
44                                                       llvm::Value *MemPtr,
45                                                 const MemberPointerType *MPT) {
46  ErrorUnsupportedABI(CGF, "calls through member pointers");
47
48  const FunctionProtoType *FPT =
49    MPT->getPointeeType()->getAs<FunctionProtoType>();
50  const CXXRecordDecl *RD =
51    cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
52  llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(
53                              CGM.getTypes().arrangeCXXMethodType(RD, FPT));
54  return llvm::Constant::getNullValue(FTy->getPointerTo());
55}
56
57llvm::Value *CGCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF,
58                                                    llvm::Value *Base,
59                                                    llvm::Value *MemPtr,
60                                              const MemberPointerType *MPT) {
61  ErrorUnsupportedABI(CGF, "loads of member pointers");
62  llvm::Type *Ty = CGF.ConvertType(MPT->getPointeeType())->getPointerTo();
63  return llvm::Constant::getNullValue(Ty);
64}
65
66llvm::Value *CGCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
67                                                   const CastExpr *E,
68                                                   llvm::Value *Src) {
69  ErrorUnsupportedABI(CGF, "member function pointer conversions");
70  return GetBogusMemberPointer(CGM, E->getType());
71}
72
73llvm::Constant *CGCXXABI::EmitMemberPointerConversion(const CastExpr *E,
74                                                      llvm::Constant *Src) {
75  return GetBogusMemberPointer(CGM, E->getType());
76}
77
78llvm::Value *
79CGCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
80                                      llvm::Value *L,
81                                      llvm::Value *R,
82                                      const MemberPointerType *MPT,
83                                      bool Inequality) {
84  ErrorUnsupportedABI(CGF, "member function pointer comparison");
85  return CGF.Builder.getFalse();
86}
87
88llvm::Value *
89CGCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
90                                     llvm::Value *MemPtr,
91                                     const MemberPointerType *MPT) {
92  ErrorUnsupportedABI(CGF, "member function pointer null testing");
93  return CGF.Builder.getFalse();
94}
95
96llvm::Constant *
97CGCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
98  return GetBogusMemberPointer(CGM, QualType(MPT, 0));
99}
100
101llvm::Constant *CGCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) {
102  return GetBogusMemberPointer(CGM,
103                         CGM.getContext().getMemberPointerType(MD->getType(),
104                                         MD->getParent()->getTypeForDecl()));
105}
106
107llvm::Constant *CGCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
108                                                CharUnits offset) {
109  return GetBogusMemberPointer(CGM, QualType(MPT, 0));
110}
111
112llvm::Constant *CGCXXABI::EmitMemberPointer(const APValue &MP, QualType MPT) {
113  return GetBogusMemberPointer(CGM, MPT);
114}
115
116bool CGCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
117  // Fake answer.
118  return true;
119}
120
121void CGCXXABI::BuildThisParam(CodeGenFunction &CGF, FunctionArgList &params) {
122  const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
123
124  // FIXME: I'm not entirely sure I like using a fake decl just for code
125  // generation. Maybe we can come up with a better way?
126  ImplicitParamDecl *ThisDecl
127    = ImplicitParamDecl::Create(CGM.getContext(), 0, MD->getLocation(),
128                                &CGM.getContext().Idents.get("this"),
129                                MD->getThisType(CGM.getContext()));
130  params.push_back(ThisDecl);
131  getThisDecl(CGF) = ThisDecl;
132}
133
134void CGCXXABI::EmitThisParam(CodeGenFunction &CGF) {
135  /// Initialize the 'this' slot.
136  assert(getThisDecl(CGF) && "no 'this' variable for function");
137  getThisValue(CGF)
138    = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
139                             "this");
140}
141
142void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
143                                   RValue RV, QualType ResultType) {
144  CGF.EmitReturnOfRValue(RV, ResultType);
145}
146
147CharUnits CGCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
148  return CharUnits::Zero();
149}
150
151llvm::Value *CGCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
152                                             llvm::Value *NewPtr,
153                                             llvm::Value *NumElements,
154                                             const CXXNewExpr *expr,
155                                             QualType ElementType) {
156  // Should never be called.
157  ErrorUnsupportedABI(CGF, "array cookie initialization");
158  return 0;
159}
160
161void CGCXXABI::ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
162                               const CXXDeleteExpr *expr, QualType ElementType,
163                               llvm::Value *&NumElements,
164                               llvm::Value *&AllocPtr, CharUnits &CookieSize) {
165  ErrorUnsupportedABI(CGF, "array cookie reading");
166
167  // This should be enough to avoid assertions.
168  NumElements = 0;
169  AllocPtr = llvm::Constant::getNullValue(CGF.Builder.getInt8PtrTy());
170  CookieSize = CharUnits::Zero();
171}
172
173void CGCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
174                               const VarDecl &D,
175                               llvm::GlobalVariable *GV,
176                               bool PerformInit) {
177  ErrorUnsupportedABI(CGF, "static local variable initialization");
178}
179
180/// Returns the adjustment, in bytes, required for the given
181/// member-pointer operation.  Returns null if no adjustment is
182/// required.
183llvm::Constant *CGCXXABI::getMemberPointerAdjustment(const CastExpr *E) {
184  assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
185         E->getCastKind() == CK_BaseToDerivedMemberPointer);
186
187  QualType derivedType;
188  if (E->getCastKind() == CK_DerivedToBaseMemberPointer)
189    derivedType = E->getSubExpr()->getType();
190  else
191    derivedType = E->getType();
192
193  const CXXRecordDecl *derivedClass =
194    derivedType->castAs<MemberPointerType>()->getClass()->getAsCXXRecordDecl();
195
196  return CGM.GetNonVirtualBaseClassOffset(derivedClass,
197                                          E->path_begin(),
198                                          E->path_end());
199}
200