ItaniumCXXABI.cpp revision 263508 
1//===------- ItaniumCXXABI.cpp - AST support for the Itanium C++ ABI ------===//
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++ AST support targeting the Itanium C++ ABI, which is
11// documented at:
12//  http://www.codesourcery.com/public/cxx-abi/abi.html
13//  http://www.codesourcery.com/public/cxx-abi/abi-eh.html
14//
15// It also supports the closely-related ARM C++ ABI, documented at:
16// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf
17//
18//===----------------------------------------------------------------------===//
19
20#include "CXXABI.h"
21#include "clang/AST/ASTContext.h"
22#include "clang/AST/DeclCXX.h"
23#include "clang/AST/MangleNumberingContext.h"
24#include "clang/AST/RecordLayout.h"
25#include "clang/AST/Type.h"
26#include "clang/Basic/TargetInfo.h"
27
28using namespace clang;
29
30namespace {
31
32/// \brief Keeps track of the mangled names of lambda expressions and block
33/// literals within a particular context.
34class ItaniumNumberingContext : public MangleNumberingContext {
35  llvm::DenseMap<IdentifierInfo*, unsigned> VarManglingNumbers;
36
37public:
38  /// Variable decls are numbered by identifier.
39  virtual unsigned getManglingNumber(const VarDecl *VD) {
40    return ++VarManglingNumbers[VD->getIdentifier()];
41  }
42};
43
44class ItaniumCXXABI : public CXXABI {
45protected:
46  ASTContext &Context;
47public:
48  ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }
49
50  std::pair<uint64_t, unsigned>
51  getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const {
52    const TargetInfo &Target = Context.getTargetInfo();
53    TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0);
54    uint64_t Width = Target.getTypeWidth(PtrDiff);
55    unsigned Align = Target.getTypeAlign(PtrDiff);
56    if (MPT->getPointeeType()->isFunctionType())
57      Width = 2 * Width;
58    return std::make_pair(Width, Align);
59  }
60
61  CallingConv getDefaultMethodCallConv(bool isVariadic) const {
62    return CC_C;
63  }
64
65  // We cheat and just check that the class has a vtable pointer, and that it's
66  // only big enough to have a vtable pointer and nothing more (or less).
67  bool isNearlyEmpty(const CXXRecordDecl *RD) const {
68
69    // Check that the class has a vtable pointer.
70    if (!RD->isDynamicClass())
71      return false;
72
73    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
74    CharUnits PointerSize =
75      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
76    return Layout.getNonVirtualSize() == PointerSize;
77  }
78
79  virtual MangleNumberingContext *createMangleNumberingContext() const {
80    return new ItaniumNumberingContext();
81  }
82};
83
84class ARMCXXABI : public ItaniumCXXABI {
85public:
86  ARMCXXABI(ASTContext &Ctx) : ItaniumCXXABI(Ctx) { }
87};
88}
89
90CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
91  return new ItaniumCXXABI(Ctx);
92}
93
94CXXABI *clang::CreateARMCXXABI(ASTContext &Ctx) {
95  return new ARMCXXABI(Ctx);
96}
97