CGCXXABI.h revision cec5ebd4a6a89a7023d04cec728fd340b541ed61 
1//===----- CGCXXABI.h - 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#ifndef CLANG_CODEGEN_CXXABI_H
16#define CLANG_CODEGEN_CXXABI_H
17
18#include "clang/Basic/LLVM.h"
19
20#include "CodeGenFunction.h"
21
22namespace llvm {
23  class Constant;
24  class Type;
25  class Value;
26}
27
28namespace clang {
29  class CastExpr;
30  class CXXConstructorDecl;
31  class CXXDestructorDecl;
32  class CXXMethodDecl;
33  class CXXRecordDecl;
34  class FieldDecl;
35  class MangleContext;
36
37namespace CodeGen {
38  class CodeGenFunction;
39  class CodeGenModule;
40
41/// Implements C++ ABI-specific code generation functions.
42class CGCXXABI {
43protected:
44  CodeGenModule &CGM;
45  OwningPtr<MangleContext> MangleCtx;
46
47  CGCXXABI(CodeGenModule &CGM)
48    : CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}
49
50protected:
51  ImplicitParamDecl *&getThisDecl(CodeGenFunction &CGF) {
52    return CGF.CXXABIThisDecl;
53  }
54  llvm::Value *&getThisValue(CodeGenFunction &CGF) {
55    return CGF.CXXABIThisValue;
56  }
57
58  ImplicitParamDecl *&getVTTDecl(CodeGenFunction &CGF) {
59    return CGF.CXXVTTDecl;
60  }
61  llvm::Value *&getVTTValue(CodeGenFunction &CGF) {
62    return CGF.CXXVTTValue;
63  }
64
65  /// Build a parameter variable suitable for 'this'.
66  void BuildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);
67
68  /// Perform prolog initialization of the parameter variable suitable
69  /// for 'this' emitted by BuildThisParam.
70  void EmitThisParam(CodeGenFunction &CGF);
71
72  ASTContext &getContext() const { return CGM.getContext(); }
73
74public:
75
76  virtual ~CGCXXABI();
77
78  /// Gets the mangle context.
79  MangleContext &getMangleContext() {
80    return *MangleCtx;
81  }
82
83  /// Find the LLVM type used to represent the given member pointer
84  /// type.
85  virtual llvm::Type *
86  ConvertMemberPointerType(const MemberPointerType *MPT);
87
88  /// Load a member function from an object and a member function
89  /// pointer.  Apply the this-adjustment and set 'This' to the
90  /// adjusted value.
91  virtual llvm::Value *
92  EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
93                                  llvm::Value *&This,
94                                  llvm::Value *MemPtr,
95                                  const MemberPointerType *MPT);
96
97  /// Calculate an l-value from an object and a data member pointer.
98  virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF,
99                                                    llvm::Value *Base,
100                                                    llvm::Value *MemPtr,
101                                            const MemberPointerType *MPT);
102
103  /// Perform a derived-to-base or base-to-derived member pointer
104  /// conversion.
105  virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
106                                                   const CastExpr *E,
107                                                   llvm::Value *Src);
108
109  /// Return true if the given member pointer can be zero-initialized
110  /// (in the C++ sense) with an LLVM zeroinitializer.
111  virtual bool isZeroInitializable(const MemberPointerType *MPT);
112
113  /// Create a null member pointer of the given type.
114  virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
115
116  /// Create a member pointer for the given method.
117  virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD);
118
119  /// Create a member pointer for the given field.
120  virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
121                                                CharUnits offset);
122
123  /// Create a member pointer for the given member pointer constant.
124  virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);
125
126  /// Emit a comparison between two member pointers.  Returns an i1.
127  virtual llvm::Value *
128  EmitMemberPointerComparison(CodeGenFunction &CGF,
129                              llvm::Value *L,
130                              llvm::Value *R,
131                              const MemberPointerType *MPT,
132                              bool Inequality);
133
134  /// Determine if a member pointer is non-null.  Returns an i1.
135  virtual llvm::Value *
136  EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
137                             llvm::Value *MemPtr,
138                             const MemberPointerType *MPT);
139
140  /// Build the signature of the given constructor variant by adding
141  /// any required parameters.  For convenience, ResTy has been
142  /// initialized to 'void', and ArgTys has been initialized with the
143  /// type of 'this' (although this may be changed by the ABI) and
144  /// will have the formal parameters added to it afterwards.
145  ///
146  /// If there are ever any ABIs where the implicit parameters are
147  /// intermixed with the formal parameters, we can address those
148  /// then.
149  virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
150                                         CXXCtorType T,
151                                         CanQualType &ResTy,
152                               SmallVectorImpl<CanQualType> &ArgTys) = 0;
153
154  /// Build the signature of the given destructor variant by adding
155  /// any required parameters.  For convenience, ResTy has been
156  /// initialized to 'void' and ArgTys has been initialized with the
157  /// type of 'this' (although this may be changed by the ABI).
158  virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
159                                        CXXDtorType T,
160                                        CanQualType &ResTy,
161                               SmallVectorImpl<CanQualType> &ArgTys) = 0;
162
163  /// Build the ABI-specific portion of the parameter list for a
164  /// function.  This generally involves a 'this' parameter and
165  /// possibly some extra data for constructors and destructors.
166  ///
167  /// ABIs may also choose to override the return type, which has been
168  /// initialized with the formal return type of the function.
169  virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF,
170                                           QualType &ResTy,
171                                           FunctionArgList &Params) = 0;
172
173  /// Emit the ABI-specific prolog for the function.
174  virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
175
176  virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
177                                   RValue RV, QualType ResultType);
178
179  /**************************** Array cookies ******************************/
180
181  /// Returns the extra size required in order to store the array
182  /// cookie for the given type.  May return 0 to indicate that no
183  /// array cookie is required.
184  ///
185  /// Several cases are filtered out before this method is called:
186  ///   - non-array allocations never need a cookie
187  ///   - calls to ::operator new(size_t, void*) never need a cookie
188  ///
189  /// \param ElementType - the allocated type of the expression,
190  ///   i.e. the pointee type of the expression result type
191  virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
192
193  /// Initialize the array cookie for the given allocation.
194  ///
195  /// \param NewPtr - a char* which is the presumed-non-null
196  ///   return value of the allocation function
197  /// \param NumElements - the computed number of elements,
198  ///   potentially collapsed from the multidimensional array case
199  /// \param ElementType - the base element allocated type,
200  ///   i.e. the allocated type after stripping all array types
201  virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
202                                             llvm::Value *NewPtr,
203                                             llvm::Value *NumElements,
204                                             const CXXNewExpr *expr,
205                                             QualType ElementType);
206
207  /// Reads the array cookie associated with the given pointer,
208  /// if it has one.
209  ///
210  /// \param Ptr - a pointer to the first element in the array
211  /// \param ElementType - the base element type of elements of the array
212  /// \param NumElements - an out parameter which will be initialized
213  ///   with the number of elements allocated, or zero if there is no
214  ///   cookie
215  /// \param AllocPtr - an out parameter which will be initialized
216  ///   with a char* pointing to the address returned by the allocation
217  ///   function
218  /// \param CookieSize - an out parameter which will be initialized
219  ///   with the size of the cookie, or zero if there is no cookie
220  virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
221                               const CXXDeleteExpr *expr,
222                               QualType ElementType, llvm::Value *&NumElements,
223                               llvm::Value *&AllocPtr, CharUnits &CookieSize);
224
225  /*************************** Static local guards ****************************/
226
227  /// Emits the guarded initializer and destructor setup for the given
228  /// variable, given that it couldn't be emitted as a constant.
229  ///
230  /// The variable may be:
231  ///   - a static local variable
232  ///   - a static data member of a class template instantiation
233  virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
234                               llvm::GlobalVariable *DeclPtr);
235
236};
237
238/// Creates an instance of a C++ ABI class.
239CGCXXABI *CreateARMCXXABI(CodeGenModule &CGM);
240CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
241CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);
242
243}
244}
245
246#endif
247