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      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/RecordLayout.h"
     23 #include "clang/AST/DeclCXX.h"
     24 #include "clang/AST/Type.h"
     25 #include "clang/Basic/TargetInfo.h"
     26 
     27 using namespace clang;
     28 
     29 namespace {
     30 class ItaniumCXXABI : public CXXABI {
     31 protected:
     32   ASTContext &Context;
     33 public:
     34   ItaniumCXXABI(ASTContext &Ctx) : Context(Ctx) { }
     35 
     36   unsigned getMemberPointerSize(const MemberPointerType *MPT) const {
     37     QualType Pointee = MPT->getPointeeType();
     38     if (Pointee->isFunctionType()) return 2;
     39     return 1;
     40   }
     41 
     42   CallingConv getDefaultMethodCallConv() const {
     43     return CC_C;
     44   }
     45 
     46   // We cheat and just check that the class has a vtable pointer, and that it's
     47   // only big enough to have a vtable pointer and nothing more (or less).
     48   bool isNearlyEmpty(const CXXRecordDecl *RD) const {
     49 
     50     // Check that the class has a vtable pointer.
     51     if (!RD->isDynamicClass())
     52       return false;
     53 
     54     const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
     55     CharUnits PointerSize =
     56       Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
     57     return Layout.getNonVirtualSize() == PointerSize;
     58   }
     59 };
     60 
     61 class ARMCXXABI : public ItaniumCXXABI {
     62 public:
     63   ARMCXXABI(ASTContext &Ctx) : ItaniumCXXABI(Ctx) { }
     64 };
     65 }
     66 
     67 CXXABI *clang::CreateItaniumCXXABI(ASTContext &Ctx) {
     68   return new ItaniumCXXABI(Ctx);
     69 }
     70 
     71 CXXABI *clang::CreateARMCXXABI(ASTContext &Ctx) {
     72   return new ARMCXXABI(Ctx);
     73 }
     74