1 //===----- CGCXXABI.h - Interface to C++ ABIs -------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This provides an abstract class for C++ code generation. Concrete subclasses
11 // of this implement code generation for specific C++ ABIs.
13 //===----------------------------------------------------------------------===//
15 #ifndef CLANG_CODEGEN_CXXABI_H
16 #define CLANG_CODEGEN_CXXABI_H
18 #include "CodeGenFunction.h"
25 template <class T> class SmallVectorImpl;
30 class CXXConstructorDecl;
31 class CXXDestructorDecl;
37 class CodeGenFunction;
41 /// Implements C++ ABI-specific code generation functions.
46 CGCXXABI(CodeGenModule &CGM) : CGM(CGM) {}
49 ImplicitParamDecl *&getThisDecl(CodeGenFunction &CGF) {
50 return CGF.CXXThisDecl;
52 llvm::Value *&getThisValue(CodeGenFunction &CGF) {
53 return CGF.CXXThisValue;
56 ImplicitParamDecl *&getVTTDecl(CodeGenFunction &CGF) {
57 return CGF.CXXVTTDecl;
59 llvm::Value *&getVTTValue(CodeGenFunction &CGF) {
60 return CGF.CXXVTTValue;
63 /// Build a parameter variable suitable for 'this'.
64 void BuildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);
66 /// Perform prolog initialization of the parameter variable suitable
67 /// for 'this' emitted by BuildThisParam.
68 void EmitThisParam(CodeGenFunction &CGF);
70 ASTContext &getContext() const { return CGM.getContext(); }
76 /// Gets the mangle context.
77 virtual MangleContext &getMangleContext() = 0;
79 /// Find the LLVM type used to represent the given member pointer
81 virtual const llvm::Type *
82 ConvertMemberPointerType(const MemberPointerType *MPT);
84 /// Load a member function from an object and a member function
85 /// pointer. Apply the this-adjustment and set 'This' to the
88 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
91 const MemberPointerType *MPT);
93 /// Calculate an l-value from an object and a data member pointer.
94 virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF,
97 const MemberPointerType *MPT);
99 /// Perform a derived-to-base or base-to-derived member pointer
101 virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
105 /// Perform a derived-to-base or base-to-derived member pointer
106 /// conversion on a constant member pointer.
107 virtual llvm::Constant *EmitMemberPointerConversion(llvm::Constant *C,
110 /// Return true if the given member pointer can be zero-initialized
111 /// (in the C++ sense) with an LLVM zeroinitializer.
112 virtual bool isZeroInitializable(const MemberPointerType *MPT);
114 /// Create a null member pointer of the given type.
115 virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
117 /// Create a member pointer for the given method.
118 virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD);
120 /// Create a member pointer for the given field.
121 virtual llvm::Constant *EmitMemberPointer(const FieldDecl *FD);
123 /// Emit a comparison between two member pointers. Returns an i1.
124 virtual llvm::Value *
125 EmitMemberPointerComparison(CodeGenFunction &CGF,
128 const MemberPointerType *MPT,
131 /// Determine if a member pointer is non-null. Returns an i1.
132 virtual llvm::Value *
133 EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
135 const MemberPointerType *MPT);
137 /// Build the signature of the given constructor variant by adding
138 /// any required parameters. For convenience, ResTy has been
139 /// initialized to 'void', and ArgTys has been initialized with the
140 /// type of 'this' (although this may be changed by the ABI) and
141 /// will have the formal parameters added to it afterwards.
143 /// If there are ever any ABIs where the implicit parameters are
144 /// intermixed with the formal parameters, we can address those
146 virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
149 llvm::SmallVectorImpl<CanQualType> &ArgTys) = 0;
151 /// Build the signature of the given destructor variant by adding
152 /// any required parameters. For convenience, ResTy has been
153 /// initialized to 'void' and ArgTys has been initialized with the
154 /// type of 'this' (although this may be changed by the ABI).
155 virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
158 llvm::SmallVectorImpl<CanQualType> &ArgTys) = 0;
160 /// Build the ABI-specific portion of the parameter list for a
161 /// function. This generally involves a 'this' parameter and
162 /// possibly some extra data for constructors and destructors.
164 /// ABIs may also choose to override the return type, which has been
165 /// initialized with the formal return type of the function.
166 virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF,
168 FunctionArgList &Params) = 0;
170 /// Emit the ABI-specific prolog for the function.
171 virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
173 virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
174 RValue RV, QualType ResultType);
176 /**************************** Array cookies ******************************/
178 /// Returns the extra size required in order to store the array
179 /// cookie for the given type. May return 0 to indicate that no
180 /// array cookie is required.
182 /// Several cases are filtered out before this method is called:
183 /// - non-array allocations never need a cookie
184 /// - calls to ::operator new(size_t, void*) never need a cookie
186 /// \param ElementType - the allocated type of the expression,
187 /// i.e. the pointee type of the expression result type
188 virtual CharUnits GetArrayCookieSize(QualType ElementType);
190 /// Initialize the array cookie for the given allocation.
192 /// \param NewPtr - a char* which is the presumed-non-null
193 /// return value of the allocation function
194 /// \param NumElements - the computed number of elements,
195 /// potentially collapsed from the multidimensional array case
196 /// \param ElementType - the base element allocated type,
197 /// i.e. the allocated type after stripping all array types
198 virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
200 llvm::Value *NumElements,
201 QualType ElementType);
203 /// Reads the array cookie associated with the given pointer,
206 /// \param Ptr - a pointer to the first element in the array
207 /// \param ElementType - the base element type of elements of the array
208 /// \param NumElements - an out parameter which will be initialized
209 /// with the number of elements allocated, or zero if there is no
211 /// \param AllocPtr - an out parameter which will be initialized
212 /// with a char* pointing to the address returned by the allocation
214 /// \param CookieSize - an out parameter which will be initialized
215 /// with the size of the cookie, or zero if there is no cookie
216 virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
217 QualType ElementType, llvm::Value *&NumElements,
218 llvm::Value *&AllocPtr, CharUnits &CookieSize);
220 /*************************** Static local guards ****************************/
222 /// Emits the guarded initializer and destructor setup for the given
223 /// variable, given that it couldn't be emitted as a constant.
225 /// The variable may be:
226 /// - a static local variable
227 /// - a static data member of a class template instantiation
228 virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
229 llvm::GlobalVariable *DeclPtr);
233 /// Creates an instance of a C++ ABI class.
234 CGCXXABI *CreateARMCXXABI(CodeGenModule &CGM);
235 CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
236 CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);