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  llvm::DenseMap<IdentifierInfo*, unsigned> TagManglingNumbers;
37
38public:
39  /// Variable decls are numbered by identifier.
40  unsigned getManglingNumber(const VarDecl *VD, unsigned) override {
41    return ++VarManglingNumbers[VD->getIdentifier()];
42  }
43
44  unsigned getManglingNumber(const TagDecl *TD, unsigned) override {
45    return ++TagManglingNumbers[TD->getIdentifier()];
46  }
47};
48
49class ItaniumCXXABI : public CXXABI {
50protected:
51  ASTContext &Context;
52public:
53  ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }
54
55  std::pair<uint64_t, unsigned>
56  getMemberPointerWidthAndAlign(const MemberPointerType *MPT) const override {
57    const TargetInfo &Target = Context.getTargetInfo();
58    TargetInfo::IntType PtrDiff = Target.getPtrDiffType(0);
59    uint64_t Width = Target.getTypeWidth(PtrDiff);
60    unsigned Align = Target.getTypeAlign(PtrDiff);
61    if (MPT->getPointeeType()->isFunctionType())
62      Width = 2 * Width;
63    return std::make_pair(Width, Align);
64  }
65
66  CallingConv getDefaultMethodCallConv(bool isVariadic) const override {
67    const llvm::Triple &T = Context.getTargetInfo().getTriple();
68    if (!isVariadic && T.isWindowsGNUEnvironment() &&
69        T.getArch() == llvm::Triple::x86)
70      return CC_X86ThisCall;
71    return CC_C;
72  }
73
74  // We cheat and just check that the class has a vtable pointer, and that it's
75  // only big enough to have a vtable pointer and nothing more (or less).
76  bool isNearlyEmpty(const CXXRecordDecl *RD) const override {
77
78    // Check that the class has a vtable pointer.
79    if (!RD->isDynamicClass())
80      return false;
81
82    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
83    CharUnits PointerSize =
84      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
85    return Layout.getNonVirtualSize() == PointerSize;
86  }
87
88  MangleNumberingContext *createMangleNumberingContext() const override {
89    return new ItaniumNumberingContext();
90  }
91};
92}
93
94CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
95  return new ItaniumCXXABI(Ctx);
96}
97