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 37 public: 38 /// Variable decls are numbered by identifier. 39 virtual unsigned getManglingNumber(const VarDecl *VD) { 40 return ++VarManglingNumbers[VD->getIdentifier()]; 41 } 42 }; 43 44 class ItaniumCXXABI : public CXXABI { 45 protected: 46 ASTContext &Context; 47 public: 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 84 class ARMCXXABI : public ItaniumCXXABI { 85 public: 86 ARMCXXABI(ASTContext &Ctx) : ItaniumCXXABI(Ctx) { } 87 }; 88 } 89 90 CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) { 91 return new ItaniumCXXABI(Ctx); 92 } 93 94 CXXABI *clang::CreateARMCXXABI(ASTContext &Ctx) { 95 return new ARMCXXABI(Ctx); 96 } 97