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/RecordLayout.h"
24#include "clang/AST/Type.h"
25#include "clang/Basic/TargetInfo.h"
26
27using namespace clang;
28
29namespace {
30class ItaniumCXXABI : public CXXABI {
31protected:
32  ASTContext &Context;
33public:
34  ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }
35
36  std::pair<uint64_t, unsigned>
37  getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const {
38    const TargetInfo &Target = Context.getTargetInfo();
39    TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0);
40    uint64_t Width = Target.getTypeWidth(PtrDiff);
41    unsigned Align = Target.getTypeAlign(PtrDiff);
42    if (MPT->getPointeeType()->isFunctionType())
43      Width = 2 * Width;
44    return std::make_pair(Width, Align);
45  }
46
47  CallingConv getDefaultMethodCallConv(bool isVariadic) const {
48    return CC_C;
49  }
50
51  // We cheat and just check that the class has a vtable pointer, and that it's
52  // only big enough to have a vtable pointer and nothing more (or less).
53  bool isNearlyEmpty(const CXXRecordDecl *RD) const {
54
55    // Check that the class has a vtable pointer.
56    if (!RD->isDynamicClass())
57      return false;
58
59    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
60    CharUnits PointerSize =
61      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
62    return Layout.getNonVirtualSize() == PointerSize;
63  }
64};
65
66class ARMCXXABI : public ItaniumCXXABI {
67public:
68  ARMCXXABI(ASTContext &Ctx) : ItaniumCXXABI(Ctx) { }
69};
70}
71
72CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
73  return new ItaniumCXXABI(Ctx);
74}
75
76CXXABI *clang::CreateARMCXXABI(ASTContext &Ctx) {
77  return new ARMCXXABI(Ctx);
78}
79