aboutsummaryrefslogtreecommitdiffstats
path: root/lib/AST/ItaniumCXXABI.cpp
blob: d6bc16b6350fc1b6050c73acfdeffba8875689cf (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
//===------- ItaniumCXXABI.cpp - AST support for the Itanium C++ ABI ------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This provides C++ AST support targeting the Itanium C++ ABI, which is
// documented at:
//  http://www.codesourcery.com/public/cxx-abi/abi.html
//  http://www.codesourcery.com/public/cxx-abi/abi-eh.html
//
// It also supports the closely-related ARM C++ ABI, documented at:
// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf
//
//===----------------------------------------------------------------------===//

#include "CXXABI.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/MangleNumberingContext.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/Type.h"
#include "clang/Basic/TargetInfo.h"

using namespace clang;

namespace {

/// According to Itanium C++ ABI 5.1.2:
/// the name of an anonymous union is considered to be
/// the name of the first named data member found by a pre-order,
/// depth-first, declaration-order walk of the data members of
/// the anonymous union.
/// If there is no such data member (i.e., if all of the data members
/// in the union are unnamed), then there is no way for a program to
/// refer to the anonymous union, and there is therefore no need to mangle its name.
///
/// Returns the name of anonymous union VarDecl or nullptr if it is not found.
static const IdentifierInfo *findAnonymousUnionVarDeclName(const VarDecl& VD) {
  const RecordType *RT = VD.getType()->getAs<RecordType>();
  assert(RT && "type of VarDecl is expected to be RecordType.");
  assert(RT->getDecl()->isUnion() && "RecordType is expected to be a union.");
  if (const FieldDecl *FD = RT->getDecl()->findFirstNamedDataMember()) {
    return FD->getIdentifier();
  }

  return nullptr;
}

/// \brief Keeps track of the mangled names of lambda expressions and block
/// literals within a particular context.
class ItaniumNumberingContext : public MangleNumberingContext {
  llvm::DenseMap<const Type *, unsigned> ManglingNumbers;
  llvm::DenseMap<const IdentifierInfo *, unsigned> VarManglingNumbers;
  llvm::DenseMap<const IdentifierInfo *, unsigned> TagManglingNumbers;

public:
  unsigned getManglingNumber(const CXXMethodDecl *CallOperator) override {
    const FunctionProtoType *Proto =
        CallOperator->getType()->getAs<FunctionProtoType>();
    ASTContext &Context = CallOperator->getASTContext();

    FunctionProtoType::ExtProtoInfo EPI;
    EPI.Variadic = Proto->isVariadic();
    QualType Key =
        Context.getFunctionType(Context.VoidTy, Proto->getParamTypes(), EPI);
    Key = Context.getCanonicalType(Key);
    return ++ManglingNumbers[Key->castAs<FunctionProtoType>()];
  }

  unsigned getManglingNumber(const BlockDecl *BD) override {
    const Type *Ty = nullptr;
    return ++ManglingNumbers[Ty];
  }

  unsigned getStaticLocalNumber(const VarDecl *VD) override {
    return 0;
  }

  /// Variable decls are numbered by identifier.
  unsigned getManglingNumber(const VarDecl *VD, unsigned) override {
    const IdentifierInfo *Identifier = VD->getIdentifier();
    if (!Identifier) {
      // VarDecl without an identifier represents an anonymous union declaration.
      Identifier = findAnonymousUnionVarDeclName(*VD);
    }
    return ++VarManglingNumbers[Identifier];
  }

  unsigned getManglingNumber(const TagDecl *TD, unsigned) override {
    return ++TagManglingNumbers[TD->getIdentifier()];
  }
};

class ItaniumCXXABI : public CXXABI {
protected:
  ASTContext &Context;
public:
  ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }

  MemberPointerInfo
  getMemberPointerInfo(const MemberPointerType *MPT) const override {
    const TargetInfo &Target = Context.getTargetInfo();
    TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0);
    MemberPointerInfo MPI;
    MPI.Width = Target.getTypeWidth(PtrDiff);
    MPI.Align = Target.getTypeAlign(PtrDiff);
    MPI.HasPadding = false;
    if (MPT->isMemberFunctionPointer())
      MPI.Width *= 2;
    return MPI;
  }

  CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
    const llvm::Triple &T = Context.getTargetInfo().getTriple();
    if (!isVariadic && T.isWindowsGNUEnvironment() &&
        T.getArch() == llvm::Triple::x86)
      return CC_X86ThisCall;
    return CC_C;
  }

  // We cheat and just check that the class has a vtable pointer, and that it's
  // only big enough to have a vtable pointer and nothing more (or less).
  bool isNearlyEmpty(const CXXRecordDecl *RD) const override {

    // Check that the class has a vtable pointer.
    if (!RD->isDynamicClass())
      return false;

    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
    CharUnits PointerSize = 
      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
    return Layout.getNonVirtualSize() == PointerSize;
  }

  const CXXConstructorDecl *
  getCopyConstructorForExceptionObject(CXXRecordDecl *RD) override {
    return nullptr;
  }

  void addCopyConstructorForExceptionObject(CXXRecordDecl *RD,
                                            CXXConstructorDecl *CD) override {}

  void addTypedefNameForUnnamedTagDecl(TagDecl *TD,
                                       TypedefNameDecl *DD) override {}

  TypedefNameDecl *getTypedefNameForUnnamedTagDecl(const TagDecl *TD) override {
    return nullptr;
  }

  void addDeclaratorForUnnamedTagDecl(TagDecl *TD,
                                      DeclaratorDecl *DD) override {}

  DeclaratorDecl *getDeclaratorForUnnamedTagDecl(const TagDecl *TD) override {
    return nullptr;
  }

  std::unique_ptr<MangleNumberingContext>
  createMangleNumberingContext() const override {
    return llvm::make_unique<ItaniumNumberingContext>();
  }
};
}

CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
  return new ItaniumCXXABI(Ctx);
}