MicrosoftCXXABI.cpp revision beeb460aa571d23318fc0f6b8abcd868def791fa 
1//===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===//
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 C++ code generation targeting the Microsoft Visual C++ ABI.
11// The class in this file generates structures that follow the Microsoft
12// Visual C++ ABI, which is actually not very well documented at all outside
13// of Microsoft.
14//
15//===----------------------------------------------------------------------===//
16
17#include "CGCXXABI.h"
18#include "CodeGenModule.h"
19#include "clang/AST/Decl.h"
20#include "clang/AST/DeclCXX.h"
21
22using namespace clang;
23using namespace CodeGen;
24
25namespace {
26
27class MicrosoftCXXABI : public CGCXXABI {
28public:
29  MicrosoftCXXABI(CodeGenModule &CGM) : CGCXXABI(CGM) {}
30
31  void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
32                                 CXXCtorType Type,
33                                 CanQualType &ResTy,
34                                 SmallVectorImpl<CanQualType> &ArgTys) {
35    // 'this' is already in place
36    // TODO: 'for base' flag
37  }
38
39  void BuildDestructorSignature(const CXXDestructorDecl *Ctor,
40                                CXXDtorType Type,
41                                CanQualType &ResTy,
42                                SmallVectorImpl<CanQualType> &ArgTys) {
43    // 'this' is already in place
44    // TODO: 'for base' flag
45  }
46
47  void BuildInstanceFunctionParams(CodeGenFunction &CGF,
48                                   QualType &ResTy,
49                                   FunctionArgList &Params) {
50    BuildThisParam(CGF, Params);
51    // TODO: 'for base' flag
52  }
53
54  void EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
55    EmitThisParam(CGF);
56    // TODO: 'for base' flag
57  }
58
59  // ==== Notes on array cookies =========
60  //
61  // MSVC seems to only use cookies when the class has a destructor; a
62  // two-argument usual array deallocation function isn't sufficient.
63  //
64  // For example, this code prints "100" and "1":
65  //   struct A {
66  //     char x;
67  //     void *operator new[](size_t sz) {
68  //       printf("%u\n", sz);
69  //       return malloc(sz);
70  //     }
71  //     void operator delete[](void *p, size_t sz) {
72  //       printf("%u\n", sz);
73  //       free(p);
74  //     }
75  //   };
76  //   int main() {
77  //     A *p = new A[100];
78  //     delete[] p;
79  //   }
80  // Whereas it prints "104" and "104" if you give A a destructor.
81  void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
82                       const CXXDeleteExpr *expr,
83                       QualType ElementType, llvm::Value *&NumElements,
84                       llvm::Value *&AllocPtr, CharUnits &CookieSize) {
85    CGF.CGM.ErrorUnsupported(expr, "don't know how to handle array cookies "
86                                   "in the Microsoft C++ ABI");
87  }
88};
89
90}
91
92CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) {
93  return new MicrosoftCXXABI(CGM);
94}
95
96