lib/CodeGen/CGCXXABI.cpp

   1 //===----- CGCXXABI.cpp - Interface to C++ ABIs -----------------*- C++ -*-===//
   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 an abstract class for C++ code generation. Concrete subclasses
  11 // of this implement code generation for specific C++ ABIs.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "CGCXXABI.h"
  16
  17 using namespace clang;
  18 using namespace CodeGen;
  19
  20 CGCXXABI::~CGCXXABI() { }
  21
  22 static void ErrorUnsupportedABI(CodeGenFunction &CGF,
  23                                 llvm::StringRef S) {
  24   Diagnostic &Diags = CGF.CGM.getDiags();
  25   unsigned DiagID = Diags.getCustomDiagID(Diagnostic::Error,
  26                                           "cannot yet compile %1 in this ABI");
  27   Diags.Report(CGF.getContext().getFullLoc(CGF.CurCodeDecl->getLocation()),
  28                DiagID)
  29     << S;
  30 }
  31
  32 static llvm::Constant *GetBogusMemberPointer(CodeGenModule &CGM,
  33                                              QualType T) {
  34   return llvm::Constant::getNullValue(CGM.getTypes().ConvertType(T));
  35 }
  36
  37 const llvm::Type *
  38 CGCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
  39   return CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
  40 }
  41
  42 llvm::Value *CGCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
  43                                                        llvm::Value *&This,
  44                                                        llvm::Value *MemPtr,
  45                                                  const MemberPointerType *MPT) {
  46   ErrorUnsupportedABI(CGF, "calls through member pointers");
  47
  48   const FunctionProtoType *FPT =
  49     MPT->getPointeeType()->getAs<FunctionProtoType>();
  50   const CXXRecordDecl *RD =
  51     cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
  52   const llvm::FunctionType *FTy =
  53     CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(RD, FPT),
  54                                    FPT->isVariadic());
  55   return llvm::Constant::getNullValue(FTy->getPointerTo());
  56 }
  57
  58 llvm::Value *CGCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF,
  59                                                     llvm::Value *Base,
  60                                                     llvm::Value *MemPtr,
  61                                               const MemberPointerType *MPT) {
  62   ErrorUnsupportedABI(CGF, "loads of member pointers");
  63   const llvm::Type *Ty = CGF.ConvertType(MPT->getPointeeType())->getPointerTo();
  64   return llvm::Constant::getNullValue(Ty);
  65 }
  66
  67 llvm::Value *CGCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
  68                                                    const CastExpr *E,
  69                                                    llvm::Value *Src) {
  70   ErrorUnsupportedABI(CGF, "member function pointer conversions");
  71   return GetBogusMemberPointer(CGM, E->getType());
  72 }
  73
  74 llvm::Value *
  75 CGCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
  76                                       llvm::Value *L,
  77                                       llvm::Value *R,
  78                                       const MemberPointerType *MPT,
  79                                       bool Inequality) {
  80   ErrorUnsupportedABI(CGF, "member function pointer comparison");
  81   return CGF.Builder.getFalse();
  82 }
  83
  84 llvm::Value *
  85 CGCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
  86                                      llvm::Value *MemPtr,
  87                                      const MemberPointerType *MPT) {
  88   ErrorUnsupportedABI(CGF, "member function pointer null testing");
  89   return CGF.Builder.getFalse();
  90 }
  91
  92 llvm::Constant *
  93 CGCXXABI::EmitMemberPointerConversion(llvm::Constant *C, const CastExpr *E) {
  94   return GetBogusMemberPointer(CGM, E->getType());
  95 }
  96
  97 llvm::Constant *
  98 CGCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
  99   return GetBogusMemberPointer(CGM, QualType(MPT, 0));
 100 }
 101
 102 llvm::Constant *CGCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) {
 103   return GetBogusMemberPointer(CGM,
 104                          CGM.getContext().getMemberPointerType(MD->getType(),
 105                                          MD->getParent()->getTypeForDecl()));
 106 }
 107
 108 llvm::Constant *CGCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
 109                                                 CharUnits offset) {
 110   return GetBogusMemberPointer(CGM, QualType(MPT, 0));
 111 }
 112
 113 bool CGCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
 114   // Fake answer.
 115   return true;
 116 }
 117
 118 void CGCXXABI::BuildThisParam(CodeGenFunction &CGF, FunctionArgList &Params) {
 119   const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
 120
 121   // FIXME: I'm not entirely sure I like using a fake decl just for code
 122   // generation. Maybe we can come up with a better way?
 123   ImplicitParamDecl *ThisDecl
 124     = ImplicitParamDecl::Create(CGM.getContext(), 0, MD->getLocation(),
 125                                 &CGM.getContext().Idents.get("this"),
 126                                 MD->getThisType(CGM.getContext()));
 127   Params.push_back(std::make_pair(ThisDecl, ThisDecl->getType()));
 128   getThisDecl(CGF) = ThisDecl;
 129 }
 130
 131 void CGCXXABI::EmitThisParam(CodeGenFunction &CGF) {
 132   /// Initialize the 'this' slot.
 133   assert(getThisDecl(CGF) && "no 'this' variable for function");
 134   getThisValue(CGF)
 135     = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getThisDecl(CGF)),
 136                              "this");
 137 }
 138
 139 void CGCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
 140                                    RValue RV, QualType ResultType) {
 141   CGF.EmitReturnOfRValue(RV, ResultType);
 142 }
 143
 144 CharUnits CGCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
 145   return CharUnits::Zero();
 146 }
 147
 148 llvm::Value *CGCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
 149                                              llvm::Value *NewPtr,
 150                                              llvm::Value *NumElements,
 151                                              const CXXNewExpr *expr,
 152                                              QualType ElementType) {
 153   // Should never be called.
 154   ErrorUnsupportedABI(CGF, "array cookie initialization");
 155   return 0;
 156 }
 157
 158 void CGCXXABI::ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
 159                                const CXXDeleteExpr *expr, QualType ElementType,
 160                                llvm::Value *&NumElements,
 161                                llvm::Value *&AllocPtr, CharUnits &CookieSize) {
 162   ErrorUnsupportedABI(CGF, "array cookie reading");
 163
 164   // This should be enough to avoid assertions.
 165   NumElements = 0;
 166   AllocPtr = llvm::Constant::getNullValue(CGF.Builder.getInt8PtrTy());
 167   CookieSize = CharUnits::Zero();
 168 }
 169
 170 void CGCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
 171                                const VarDecl &D,
 172                                llvm::GlobalVariable *GV) {
 173   ErrorUnsupportedABI(CGF, "static local variable initialization");
 174 }