C++ MCSymbol::isDefined方法代码示例

void MachineFunction::tidyLandingPads(DenseMap<MCSymbol*, uintptr_t> *LPMap) {
  for (unsigned i = 0; i != LandingPads.size(); ) {
    LandingPadInfo &LandingPad = LandingPads[i];
    if (LandingPad.LandingPadLabel &&
        !LandingPad.LandingPadLabel->isDefined() &&
        (!LPMap || (*LPMap)[LandingPad.LandingPadLabel] == 0))
      LandingPad.LandingPadLabel = nullptr;

    // Special case: we *should* emit LPs with null LP MBB. This indicates
    // "nounwind" case.
    if (!LandingPad.LandingPadLabel && LandingPad.LandingPadBlock) {
      LandingPads.erase(LandingPads.begin() + i);
      continue;
    }

    for (unsigned j = 0, e = LandingPads[i].BeginLabels.size(); j != e; ++j) {
      MCSymbol *BeginLabel = LandingPad.BeginLabels[j];
      MCSymbol *EndLabel = LandingPad.EndLabels[j];
      if ((BeginLabel->isDefined() ||
           (LPMap && (*LPMap)[BeginLabel] != 0)) &&
          (EndLabel->isDefined() ||
           (LPMap && (*LPMap)[EndLabel] != 0))) continue;

      LandingPad.BeginLabels.erase(LandingPad.BeginLabels.begin() + j);
      LandingPad.EndLabels.erase(LandingPad.EndLabels.begin() + j);
      --j;
      --e;
    }

    // Remove landing pads with no try-ranges.
    if (LandingPads[i].BeginLabels.empty()) {
      LandingPads.erase(LandingPads.begin() + i);
      continue;
    }

    // If there is no landing pad, ensure that the list of typeids is empty.
    // If the only typeid is a cleanup, this is the same as having no typeids.
    if (!LandingPad.LandingPadBlock ||
        (LandingPad.TypeIds.size() == 1 && !LandingPad.TypeIds[0]))
      LandingPad.TypeIds.clear();
    ++i;
  }
}

uint32_t SVMMemoryLayout::getEntryAddress(const MCAssembler &Asm,
    const MCAsmLayout &Layout) const
{
    MCSymbol *S = Asm.getContext().LookupSymbol("main");
    if (!S || !S->isDefined())
        report_fatal_error("No entry point exists. Is main() defined?");

    SVMSymbolInfo SI = getSymbol(Asm, Layout, S);
    assert(SI.Kind == SVMSymbolInfo::LOCAL);
    return SI.Value;
}

/// parseDirectiveAltEntry
///  ::= .alt_entry identifier
bool DarwinAsmParser::parseDirectiveAltEntry(StringRef, SMLoc) {
  StringRef Name;
  if (getParser().parseIdentifier(Name))
    return TokError("expected identifier in directive");

  // Look up symbol.
  MCSymbol *Sym = getContext().getOrCreateSymbol(Name);

  if (Sym->isDefined())
    return TokError(".alt_entry must preceed symbol definition");

  if (!getStreamer().EmitSymbolAttribute(Sym, MCSA_AltEntry))
    return TokError("unable to emit symbol attribute");

  Lex();
  return false;
}

void MMIAddrLabelMap::UpdateForDeletedBlock(BasicBlock *BB) {
  // If the block got deleted, there is no need for the symbol.  If the symbol
  // was already emitted, we can just forget about it, otherwise we need to
  // queue it up for later emission when the function is output.
  AddrLabelSymEntry Entry = AddrLabelSymbols[BB];
  AddrLabelSymbols.erase(BB);
  assert(!Entry.Symbols.isNull() && "Didn't have a symbol, why a callback?");
  BBCallbacks[Entry.Index] = nullptr;  // Clear the callback.

  assert((BB->getParent() == nullptr || BB->getParent() == Entry.Fn) &&
         "Block/parent mismatch");

  // Handle both the single and the multiple symbols cases.
  if (MCSymbol *Sym = Entry.Symbols.dyn_cast<MCSymbol*>()) {
    if (Sym->isDefined())
      return;

    // If the block is not yet defined, we need to emit it at the end of the
    // function.  Add the symbol to the DeletedAddrLabelsNeedingEmission list
    // for the containing Function.  Since the block is being deleted, its
    // parent may already be removed, we have to get the function from 'Entry'.
    DeletedAddrLabelsNeedingEmission[Entry.Fn].push_back(Sym);
  } else {
    std::vector<MCSymbol*> *Syms = Entry.Symbols.get<std::vector<MCSymbol*>*>();

    for (unsigned i = 0, e = Syms->size(); i != e; ++i) {
      MCSymbol *Sym = (*Syms)[i];
      if (Sym->isDefined()) continue;  // Ignore already emitted labels.

      // If the block is not yet defined, we need to emit it at the end of the
      // function.  Add the symbol to the DeletedAddrLabelsNeedingEmission list
      // for the containing Function.  Since the block is being deleted, its
      // parent may already be removed, we have to get the function from
      // 'Entry'.
      DeletedAddrLabelsNeedingEmission[Entry.Fn].push_back(Sym);
    }

    // The entry is deleted, free the memory associated with the symbol list.
    delete Syms;
  }
}

/// EmitFrameMoves - Emit frame instructions to describe the layout of the
/// frame.
void AsmPrinter::EmitFrameMoves(const std::vector<MachineMove> &Moves,
                                MCSymbol *BaseLabel, bool isEH) const {
  const TargetRegisterInfo *RI = TM.getRegisterInfo();
  
  int stackGrowth = TM.getTargetData()->getPointerSize();
  if (TM.getFrameInfo()->getStackGrowthDirection() !=
      TargetFrameInfo::StackGrowsUp)
    stackGrowth *= -1;
  
  for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
    const MachineMove &Move = Moves[i];
    MCSymbol *Label = Move.getLabel();
    // Throw out move if the label is invalid.
    if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
    
    const MachineLocation &Dst = Move.getDestination();
    const MachineLocation &Src = Move.getSource();
    
    // Advance row if new location.
    if (BaseLabel && Label) {
      MCSymbol *ThisSym = Label;
      if (ThisSym != BaseLabel) {
        EmitCFAByte(dwarf::DW_CFA_advance_loc4);
        EmitLabelDifference(ThisSym, BaseLabel, 4);
        BaseLabel = ThisSym;
      }
    }
    
    // If advancing cfa.
    if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
      assert(!Src.isReg() && "Machine move not supported yet.");
      
      if (Src.getReg() == MachineLocation::VirtualFP) {
        EmitCFAByte(dwarf::DW_CFA_def_cfa_offset);
      } else {
        EmitCFAByte(dwarf::DW_CFA_def_cfa);
        EmitULEB128(RI->getDwarfRegNum(Src.getReg(), isEH), "Register");
      }
      
      EmitULEB128(-Src.getOffset(), "Offset");
      continue;
    }
    
    if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
      assert(Dst.isReg() && "Machine move not supported yet.");
      EmitCFAByte(dwarf::DW_CFA_def_cfa_register);
      EmitULEB128(RI->getDwarfRegNum(Dst.getReg(), isEH), "Register");
      continue;
    }
    
    unsigned Reg = RI->getDwarfRegNum(Src.getReg(), isEH);
    int Offset = Dst.getOffset() / stackGrowth;
    
    if (Offset < 0) {
      EmitCFAByte(dwarf::DW_CFA_offset_extended_sf);
      EmitULEB128(Reg, "Reg");
      EmitSLEB128(Offset, "Offset");
    } else if (Reg < 64) {
      EmitCFAByte(dwarf::DW_CFA_offset + Reg);
      EmitULEB128(Offset, "Offset");
    } else {
      EmitCFAByte(dwarf::DW_CFA_offset_extended);
      EmitULEB128(Reg, "Reg");
      EmitULEB128(Offset, "Offset");
    }
  }
}