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
28 using namespace clang;
29
30 namespace {
31
32 /// \brief Keeps track of the mangled names of lambda expressions and block
33 /// literals within a particular context.
34 class ItaniumNumberingContext : public MangleNumberingContext {
35 llvm::DenseMap<IdentifierInfo*, unsigned> VarManglingNumbers;
36 llvm::DenseMap<IdentifierInfo*, unsigned> TagManglingNumbers;
37
38 public:
39 /// Variable decls are numbered by identifier.
getManglingNumber(const VarDecl * VD,unsigned)40 unsigned getManglingNumber(const VarDecl *VD, unsigned) override {
41 return ++VarManglingNumbers[VD->getIdentifier()];
42 }
43
getManglingNumber(const TagDecl * TD,unsigned)44 unsigned getManglingNumber(const TagDecl *TD, unsigned) override {
45 return ++TagManglingNumbers[TD->getIdentifier()];
46 }
47 };
48
49 class ItaniumCXXABI : public CXXABI {
50 protected:
51 ASTContext &Context;
52 public:
ItaniumCXXABI(ASTContext & Ctx)53 ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }
54
55 std::pair<uint64_t, unsigned>
getMemberPointerWidthAndAlign(const MemberPointerType * MPT) const56 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
getDefaultMethodCallConv(bool isVariadic) const66 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).
isNearlyEmpty(const CXXRecordDecl * RD) const76 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
createMangleNumberingContext() const88 MangleNumberingContext *createMangleNumberingContext() const override {
89 return new ItaniumNumberingContext();
90 }
91 };
92 }
93
CreateItaniumCXXABI(ASTContext & Ctx)94 CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
95 return new ItaniumCXXABI(Ctx);
96 }
97