C++ GlobalValue::hasInternalLinkage方法代码示例

static char TypeCharForSymbol(GlobalValue &GV) {
  if (GV.isDeclaration())                                  return 'U';
  if (GV.hasLinkOnceLinkage())                             return 'C';
  if (GV.hasCommonLinkage())                               return 'C';
  if (GV.hasWeakLinkage())                                 return 'W';
  if (isa<Function>(GV) && GV.hasInternalLinkage())        return 't';
  if (isa<Function>(GV))                                   return 'T';
  if (isa<GlobalVariable>(GV) && GV.hasInternalLinkage())  return 'd';
  if (isa<GlobalVariable>(GV))                             return 'D';
  if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(&GV)) {
    const GlobalValue *AliasedGV = GA->getAliasedGlobal();
    if (isa<Function>(AliasedGV))                          return 'T';
    if (isa<GlobalVariable>(AliasedGV))                    return 'D';
  }
                                                           return '?';
}

// getOrInsertFunction - Look up the specified function in the module symbol
// table.  If it does not exist, add a prototype for the function and return
// it.  This is nice because it allows most passes to get away with not handling
// the symbol table directly for this common task.
//
Constant *Module::getOrInsertFunction(const std::string &Name,
                                      const FunctionType *Ty) {
  ValueSymbolTable &SymTab = getValueSymbolTable();

  // See if we have a definition for the specified function already.
  GlobalValue *F = dyn_cast_or_null<GlobalValue>(SymTab.lookup(Name));
  if (F == 0) {
    // Nope, add it
    Function *New = Function::Create(Ty, GlobalVariable::ExternalLinkage, Name);
    FunctionList.push_back(New);
    return New;                    // Return the new prototype.
  }

  // Okay, the function exists.  Does it have externally visible linkage?
  if (F->hasInternalLinkage()) {
    // Clear the function's name.
    F->setName("");
    // Retry, now there won't be a conflict.
    Constant *NewF = getOrInsertFunction(Name, Ty);
    F->setName(&Name[0], Name.size());
    return NewF;
  }

  // If the function exists but has the wrong type, return a bitcast to the
  // right type.
  if (F->getType() != PointerType::getUnqual(Ty))
    return ConstantExpr::getBitCast(F, PointerType::getUnqual(Ty));
  
  // Otherwise, we just found the existing function or a prototype.
  return F;  
}

static void forceImport(Module *m, const char *name, const Type *retType, ...) {
  // If module lacks an externally visible symbol for the name then we
  // need to create one. We have to look in the symbol table because
  // we want to check everything (global variables, functions, and
  // aliases).

  Value *v = m->getValueSymbolTable().lookup(name);
  GlobalValue *gv = dyn_cast_or_null<GlobalValue>(v);

  if (!gv || gv->hasInternalLinkage()) {
    va_list ap;

    va_start(ap, retType);
    std::vector<const Type *> argTypes;
    while (const Type *t = va_arg(ap, const Type*))
      argTypes.push_back(t);
    va_end(ap);

    m->getOrInsertFunction(name, FunctionType::get(retType, argTypes, false));
  }

/// LowerOperation - Provide custom lowering hooks for some operations.
///
SDOperand AlphaTargetLowering::LowerOperation(SDOperand Op, SelectionDAG &DAG) {
  switch (Op.getOpcode()) {
  default: assert(0 && "Wasn't expecting to be able to lower this!");
  case ISD::FORMAL_ARGUMENTS: return LowerFORMAL_ARGUMENTS(Op, DAG, 
                                                           VarArgsBase,
                                                           VarArgsOffset);

  case ISD::RET: return LowerRET(Op,DAG);
  case ISD::JumpTable: return LowerJumpTable(Op, DAG);

  case ISD::SINT_TO_FP: {
    assert(MVT::i64 == Op.getOperand(0).getValueType() && 
           "Unhandled SINT_TO_FP type in custom expander!");
    SDOperand LD;
    bool isDouble = MVT::f64 == Op.getValueType();
    LD = DAG.getNode(ISD::BIT_CONVERT, MVT::f64, Op.getOperand(0));
    SDOperand FP = DAG.getNode(isDouble?AlphaISD::CVTQT_:AlphaISD::CVTQS_,
                               isDouble?MVT::f64:MVT::f32, LD);
    return FP;
  }
  case ISD::FP_TO_SINT: {
    bool isDouble = MVT::f64 == Op.getOperand(0).getValueType();
    SDOperand src = Op.getOperand(0);

    if (!isDouble) //Promote
      src = DAG.getNode(ISD::FP_EXTEND, MVT::f64, src);
    
    src = DAG.getNode(AlphaISD::CVTTQ_, MVT::f64, src);

    return DAG.getNode(ISD::BIT_CONVERT, MVT::i64, src);
  }
  case ISD::ConstantPool: {
    ConstantPoolSDNode *CP = cast<ConstantPoolSDNode>(Op);
    Constant *C = CP->getConstVal();
    SDOperand CPI = DAG.getTargetConstantPool(C, MVT::i64, CP->getAlignment());
    
    SDOperand Hi = DAG.getNode(AlphaISD::GPRelHi,  MVT::i64, CPI,
                               DAG.getNode(ISD::GLOBAL_OFFSET_TABLE, MVT::i64));
    SDOperand Lo = DAG.getNode(AlphaISD::GPRelLo, MVT::i64, CPI, Hi);
    return Lo;
  }
  case ISD::GlobalAddress: {
    GlobalAddressSDNode *GSDN = cast<GlobalAddressSDNode>(Op);
    GlobalValue *GV = GSDN->getGlobal();
    SDOperand GA = DAG.getTargetGlobalAddress(GV, MVT::i64, GSDN->getOffset());

    //    if (!GV->hasWeakLinkage() && !GV->isDeclaration() && !GV->hasLinkOnceLinkage()) {
    if (GV->hasInternalLinkage()) {
      SDOperand Hi = DAG.getNode(AlphaISD::GPRelHi,  MVT::i64, GA,
                                DAG.getNode(ISD::GLOBAL_OFFSET_TABLE, MVT::i64));
      SDOperand Lo = DAG.getNode(AlphaISD::GPRelLo, MVT::i64, GA, Hi);
      return Lo;
    } else
      return DAG.getNode(AlphaISD::RelLit, MVT::i64, GA, 
                         DAG.getNode(ISD::GLOBAL_OFFSET_TABLE, MVT::i64));
  }
  case ISD::ExternalSymbol: {
    return DAG.getNode(AlphaISD::RelLit, MVT::i64, 
                       DAG.getTargetExternalSymbol(cast<ExternalSymbolSDNode>(Op)
                                                   ->getSymbol(), MVT::i64),
                       DAG.getNode(ISD::GLOBAL_OFFSET_TABLE, MVT::i64));
  }

  case ISD::UREM:
  case ISD::SREM:
    //Expand only on constant case
    if (Op.getOperand(1).getOpcode() == ISD::Constant) {
      MVT::ValueType VT = Op.Val->getValueType(0);
      SDOperand Tmp1 = Op.Val->getOpcode() == ISD::UREM ?
        BuildUDIV(Op.Val, DAG, NULL) :
        BuildSDIV(Op.Val, DAG, NULL);
      Tmp1 = DAG.getNode(ISD::MUL, VT, Tmp1, Op.getOperand(1));
      Tmp1 = DAG.getNode(ISD::SUB, VT, Op.getOperand(0), Tmp1);
      return Tmp1;
    }
    //fall through
  case ISD::SDIV:
  case ISD::UDIV:
    if (MVT::isInteger(Op.getValueType())) {
      if (Op.getOperand(1).getOpcode() == ISD::Constant)
        return Op.getOpcode() == ISD::SDIV ? BuildSDIV(Op.Val, DAG, NULL) 
          : BuildUDIV(Op.Val, DAG, NULL);
      const char* opstr = 0;
      switch (Op.getOpcode()) {
      case ISD::UREM: opstr = "__remqu"; break;
      case ISD::SREM: opstr = "__remq";  break;
      case ISD::UDIV: opstr = "__divqu"; break;
      case ISD::SDIV: opstr = "__divq";  break;
      }
      SDOperand Tmp1 = Op.getOperand(0),
        Tmp2 = Op.getOperand(1),
        Addr = DAG.getExternalSymbol(opstr, MVT::i64);
      return DAG.getNode(AlphaISD::DivCall, MVT::i64, Addr, Tmp1, Tmp2);
    }
    break;

  case ISD::VAARG: {
    SDOperand Chain = Op.getOperand(0);
//.........这里部分代码省略.........