C++ const_iterator::isLabel方法代码示例

//.........这里部分代码省略.........
        PrevAction = &Actions.back();
      }

      // Record the first action of the landing pad site.
      FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
    } // else identical - re-use previous FirstAction

    FirstActions.push_back(FirstAction);

    // Compute this sites contribution to size.
    SizeActions += SizeSiteActions;
  }

  // Compute the call-site table.  Entries must be ordered by address.
  SmallVector<CallSiteEntry, 64> CallSites;

  RangeMapType PadMap;
  for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
    const LandingPadInfo *LandingPad = LandingPads[i];
    for (unsigned j=0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
      MCSymbol *BeginLabel = LandingPad->BeginLabels[j];
      assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
      PadRange P = { i, j };
      PadMap[BeginLabel] = P;
    }
  }

  bool MayThrow = false;
  MCSymbol *LastLabel = 0;
  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
        I != E; ++I) {
    for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
          MI != E; ++MI) {
      if (!MI->isLabel()) {
        MayThrow |= MI->getDesc().isCall();
        continue;
      }

      MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
      assert(BeginLabel && "Invalid label!");

      if (BeginLabel == LastLabel)
        MayThrow = false;

      RangeMapType::iterator L = PadMap.find(BeginLabel);

      if (L == PadMap.end())
        continue;

      PadRange P = L->second;
      const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];

      assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
              "Inconsistent landing pad map!");

      // If some instruction between the previous try-range and this one may
      // throw, create a call-site entry with no landing pad for the region
      // between the try-ranges.
      if (MayThrow) {
        CallSiteEntry Site = {LastLabel, BeginLabel, 0, 0};
        CallSites.push_back(Site);
      }

      LastLabel = LandingPad->EndLabels[P.RangeIndex];
      CallSiteEntry Site = {BeginLabel, LastLabel,
        LandingPad->LandingPadLabel, FirstActions[P.PadIndex]};

/// ComputeCallSiteTable - Compute the call-site table.  The entry for an invoke
/// has a try-range containing the call, a non-zero landing pad, and an
/// appropriate action.  The entry for an ordinary call has a try-range
/// containing the call and zero for the landing pad and the action.  Calls
/// marked 'nounwind' have no entry and must not be contained in the try-range
/// of any entry - they form gaps in the table.  Entries must be ordered by
/// try-range address.
void DwarfException::
ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
                     const RangeMapType &PadMap,
                     const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
                     const SmallVectorImpl<unsigned> &FirstActions) {
  // The end label of the previous invoke or nounwind try-range.
  MCSymbol *LastLabel = 0;

  // Whether there is a potentially throwing instruction (currently this means
  // an ordinary call) between the end of the previous try-range and now.
  bool SawPotentiallyThrowing = false;

  // Whether the last CallSite entry was for an invoke.
  bool PreviousIsInvoke = false;

  // Visit all instructions in order of address.
  for (MachineFunction::const_iterator I = Asm->MF->begin(), E = Asm->MF->end();
       I != E; ++I) {
    for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
         MI != E; ++MI) {
      if (!MI->isLabel()) {
        if (MI->isCall())
          SawPotentiallyThrowing |= !CallToNoUnwindFunction(MI);
        continue;
      }

      // End of the previous try-range?
      MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
      if (BeginLabel == LastLabel)
        SawPotentiallyThrowing = false;

      // Beginning of a new try-range?
      RangeMapType::const_iterator L = PadMap.find(BeginLabel);
      if (L == PadMap.end())
        // Nope, it was just some random label.
        continue;

      const PadRange &P = L->second;
      const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];
      assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
             "Inconsistent landing pad map!");

      // For Dwarf exception handling (SjLj handling doesn't use this). If some
      // instruction between the previous try-range and this one may throw,
      // create a call-site entry with no landing pad for the region between the
      // try-ranges.
      if (SawPotentiallyThrowing && Asm->MAI->isExceptionHandlingDwarf()) {
        CallSiteEntry Site = { LastLabel, BeginLabel, 0, 0 };
        CallSites.push_back(Site);
        PreviousIsInvoke = false;
      }

      LastLabel = LandingPad->EndLabels[P.RangeIndex];
      assert(BeginLabel && LastLabel && "Invalid landing pad!");

      if (!LandingPad->LandingPadLabel) {
        // Create a gap.
        PreviousIsInvoke = false;
      } else {
        // This try-range is for an invoke.
        CallSiteEntry Site = {
          BeginLabel,
          LastLabel,
          LandingPad->LandingPadLabel,
          FirstActions[P.PadIndex]
        };

        // Try to merge with the previous call-site. SJLJ doesn't do this
        if (PreviousIsInvoke && Asm->MAI->isExceptionHandlingDwarf()) {
          CallSiteEntry &Prev = CallSites.back();
          if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
            // Extend the range of the previous entry.
            Prev.EndLabel = Site.EndLabel;
            continue;
          }
        }

        // Otherwise, create a new call-site.
        if (Asm->MAI->isExceptionHandlingDwarf())
          CallSites.push_back(Site);
        else {
          // SjLj EH must maintain the call sites in the order assigned
          // to them by the SjLjPrepare pass.
          unsigned SiteNo = MMI->getCallSiteBeginLabel(BeginLabel);
          if (CallSites.size() < SiteNo)
            CallSites.resize(SiteNo);
          CallSites[SiteNo - 1] = Site;
        }
        PreviousIsInvoke = true;
      }
    }
  }

//.........这里部分代码省略.........

/// PrepareMonoLSDA - Collect information needed by EmitMonoLSDA
///
///   This function collects information available only during EndFunction which is needed
/// by EmitMonoLSDA and stores it into EHFrameInfo. It is the same as the
/// beginning of EmitExceptionTable.
///
void DwarfMonoException::PrepareMonoLSDA(FunctionEHFrameInfo *EHFrameInfo) {
  const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
  const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
  const MachineFunction *MF = Asm->MF;

  // Sort the landing pads in order of their type ids.  This is used to fold
  // duplicate actions.
  SmallVector<const LandingPadInfo *, 64> LandingPads;
  LandingPads.reserve(PadInfos.size());

  for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
    LandingPads.push_back(&PadInfos[i]);

  std::sort(LandingPads.begin(), LandingPads.end(),
          [](const LandingPadInfo *L,
			 const LandingPadInfo *R) { return L->TypeIds < R->TypeIds; });

  // Invokes and nounwind calls have entries in PadMap (due to being bracketed
  // by try-range labels when lowered).  Ordinary calls do not, so appropriate
  // try-ranges for them need be deduced when using DWARF exception handling.
  RangeMapType PadMap;
  for (unsigned i = 0, N = LandingPads.size(); i != N; ++i) {
    const LandingPadInfo *LandingPad = LandingPads[i];
    for (unsigned j = 0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
      MCSymbol *BeginLabel = LandingPad->BeginLabels[j];
      assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
      PadRange P = { i, j };
      PadMap[BeginLabel] = P;
    }
  }

  // Compute the call-site table.
  SmallVector<MonoCallSiteEntry, 64> CallSites;

  MCSymbol *LastLabel = 0;
  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
        I != E; ++I) {
    for (MachineBasicBlock::const_iterator MI = I->begin(), E = I->end();
          MI != E; ++MI) {
      if (!MI->isLabel()) {
        continue;
      }

      MCSymbol *BeginLabel = MI->getOperand(0).getMCSymbol();
      assert(BeginLabel && "Invalid label!");

      RangeMapType::iterator L = PadMap.find(BeginLabel);

      if (L == PadMap.end())
        continue;

      PadRange P = L->second;
      const LandingPadInfo *LandingPad = LandingPads[P.PadIndex];

      assert(BeginLabel == LandingPad->BeginLabels[P.RangeIndex] &&
              "Inconsistent landing pad map!");

      // Mono emits one landing pad for each CLR exception clause,
      // and the type info contains the clause index
      assert (LandingPad->TypeIds.size() == 1);
      assert (LandingPad->LandingPadLabel);

      LastLabel = LandingPad->EndLabels[P.RangeIndex];
      MonoCallSiteEntry Site = {BeginLabel, LastLabel,
							LandingPad->LandingPadLabel, LandingPad->TypeIds [0]};

      assert(Site.BeginLabel && Site.EndLabel && Site.PadLabel &&
              "Invalid landing pad!");

	  // FIXME: This doesn't work because it includes ranges outside clauses
#if 0
      // Try to merge with the previous call-site.
      if (CallSites.size()) {
        MonoCallSiteEntry &Prev = CallSites.back();
        if (Site.PadLabel == Prev.PadLabel && Site.TypeID == Prev.TypeID) {
          // Extend the range of the previous entry.
          Prev.EndLabel = Site.EndLabel;
          continue;
        }
      }
#endif

      // Otherwise, create a new call-site.
      CallSites.push_back(Site);
    }
  }

  //
  // Compute a mapping from method names to their AOT method index
  //
  if (FuncIndexes.size () == 0) {
    const Module *m = MMI->getModule ();
    NamedMDNode *indexes = m->getNamedMetadata ("mono.function_indexes");
	if (indexes) {
//.........这里部分代码省略.........