C++ MachineBasicBlock::getNumber方法代码示例

/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
/// register references and actual offsets.
///
void PEI::replaceFrameIndices(MachineFunction &Fn) {
  if (!Fn.getFrameInfo()->hasStackObjects()) return; // Nothing to do?

  // Store SPAdj at exit of a basic block.
  SmallVector<int, 8> SPState;
  SPState.resize(Fn.getNumBlockIDs());
  SmallPtrSet<MachineBasicBlock*, 8> Reachable;

  // Iterate over the reachable blocks in DFS order.
  for (df_ext_iterator<MachineFunction*, SmallPtrSet<MachineBasicBlock*, 8> >
       DFI = df_ext_begin(&Fn, Reachable), DFE = df_ext_end(&Fn, Reachable);
       DFI != DFE; ++DFI) {
    int SPAdj = 0;
    // Check the exit state of the DFS stack predecessor.
    if (DFI.getPathLength() >= 2) {
      MachineBasicBlock *StackPred = DFI.getPath(DFI.getPathLength() - 2);
      assert(Reachable.count(StackPred) &&
             "DFS stack predecessor is already visited.\n");
      SPAdj = SPState[StackPred->getNumber()];
    }
    MachineBasicBlock *BB = *DFI;
    replaceFrameIndices(BB, Fn, SPAdj);
    SPState[BB->getNumber()] = SPAdj;
  }

  // Handle the unreachable blocks.
  for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
    if (Reachable.count(BB))
      // Already handled in DFS traversal.
      continue;
    int SPAdj = 0;
    replaceFrameIndices(BB, Fn, SPAdj);
  }
}

/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
/// register references and actual offsets.
void PEI::replaceFrameIndices(MachineFunction &MF) {
  const TargetFrameLowering &TFI = *MF.getSubtarget().getFrameLowering();
  if (!TFI.needsFrameIndexResolution(MF)) return;

  // Store SPAdj at exit of a basic block.
  SmallVector<int, 8> SPState;
  SPState.resize(MF.getNumBlockIDs());
  df_iterator_default_set<MachineBasicBlock*> Reachable;

  // Iterate over the reachable blocks in DFS order.
  for (auto DFI = df_ext_begin(&MF, Reachable), DFE = df_ext_end(&MF, Reachable);
       DFI != DFE; ++DFI) {
    int SPAdj = 0;
    // Check the exit state of the DFS stack predecessor.
    if (DFI.getPathLength() >= 2) {
      MachineBasicBlock *StackPred = DFI.getPath(DFI.getPathLength() - 2);
      assert(Reachable.count(StackPred) &&
             "DFS stack predecessor is already visited.\n");
      SPAdj = SPState[StackPred->getNumber()];
    }
    MachineBasicBlock *BB = *DFI;
    replaceFrameIndices(BB, MF, SPAdj);
    SPState[BB->getNumber()] = SPAdj;
  }

  // Handle the unreachable blocks.
  for (auto &BB : MF) {
    if (Reachable.count(&BB))
      // Already handled in DFS traversal.
      continue;
    int SPAdj = 0;
    replaceFrameIndices(&BB, MF, SPAdj);
  }
}

/// Insert BLOCK markers at appropriate places.
static void PlaceBlockMarkers(MachineBasicBlock &MBB, MachineBasicBlock &Succ,
                              MachineFunction &MF, const MachineLoopInfo &MLI,
                              const WebAssemblyInstrInfo &TII) {
  // Backward branches are loop backedges, and we place the LOOP markers
  // separately. So only consider forward branches here.
  if (Succ.getNumber() <= MBB.getNumber())
    return;

  // Place the BLOCK for a forward branch. For simplicity, we just insert
  // blocks immediately inside loop boundaries.
  MachineLoop *Loop = MLI.getLoopFor(&Succ);
  MachineBasicBlock &Header = *(Loop ? Loop->getHeader() : &MF.front());
  MachineBasicBlock::iterator InsertPos = Header.begin(), End = Header.end();
  if (InsertPos != End) {
    if (InsertPos->getOpcode() == WebAssembly::LOOP)
      ++InsertPos;
    int SuccNumber = Succ.getNumber();
    // Position the BLOCK in nesting order.
    for (; InsertPos != End && InsertPos->getOpcode() == WebAssembly::BLOCK;
         ++InsertPos) {
      int N = InsertPos->getOperand(0).getMBB()->getNumber();
      if (N < SuccNumber)
        break;
      // If there's already a BLOCK for Succ, we don't need another.
      if (N == SuccNumber)
        return;
    }
  }

  BuildMI(Header, InsertPos, DebugLoc(), TII.get(WebAssembly::BLOCK))
      .addMBB(&Succ);
}

/// Insert a LOOP marker for a loop starting at MBB (if it's a loop header).
static void PlaceLoopMarker(MachineBasicBlock &MBB, MachineFunction &MF,
                            SmallVectorImpl<MachineBasicBlock *> &ScopeTops,
                            const WebAssemblyInstrInfo &TII,
                            const MachineLoopInfo &MLI) {
  MachineLoop *Loop = MLI.getLoopFor(&MBB);
  if (!Loop || Loop->getHeader() != &MBB)
    return;

  // The operand of a LOOP is the first block after the loop. If the loop is the
  // bottom of the function, insert a dummy block at the end.
  MachineBasicBlock *Bottom = LoopBottom(Loop);
  auto Iter = next(MachineFunction::iterator(Bottom));
  if (Iter == MF.end()) {
    MachineBasicBlock *Label = MF.CreateMachineBasicBlock();
    // Give it a fake predecessor so that AsmPrinter prints its label.
    Label->addSuccessor(Label);
    MF.push_back(Label);
    Iter = next(MachineFunction::iterator(Bottom));
  }
  MachineBasicBlock *AfterLoop = &*Iter;
  BuildMI(MBB, MBB.begin(), DebugLoc(), TII.get(WebAssembly::LOOP))
      .addMBB(AfterLoop);

  // Emit a special no-op telling the asm printer that we need a label to close
  // the loop scope, even though the destination is only reachable by
  // fallthrough.
  if (!Bottom->back().isBarrier())
    BuildMI(*Bottom, Bottom->end(), DebugLoc(), TII.get(WebAssembly::LOOP_END));

  assert((!ScopeTops[AfterLoop->getNumber()] ||
          ScopeTops[AfterLoop->getNumber()]->getNumber() < MBB.getNumber()) &&
         "With RPO we should visit the outer-most loop for a block first.");
  if (!ScopeTops[AfterLoop->getNumber()])
    ScopeTops[AfterLoop->getNumber()] = &MBB;
}

void MIRPrinter::convert(ModuleSlotTracker &MST,
                         yaml::MachineBasicBlock &YamlMBB,
                         const MachineBasicBlock &MBB) {
    assert(MBB.getNumber() >= 0 && "Invalid MBB number");
    YamlMBB.ID = (unsigned)MBB.getNumber();
    // TODO: Serialize unnamed BB references.
    if (const auto *BB = MBB.getBasicBlock())
        YamlMBB.Name.Value = BB->hasName() ? BB->getName() : "<unnamed bb>";
    else
        YamlMBB.Name.Value = "";
    YamlMBB.Alignment = MBB.getAlignment();
    YamlMBB.AddressTaken = MBB.hasAddressTaken();
    YamlMBB.IsLandingPad = MBB.isLandingPad();
    for (const auto *SuccMBB : MBB.successors()) {
        std::string Str;
        raw_string_ostream StrOS(Str);
        MIPrinter(StrOS, MST, RegisterMaskIds).printMBBReference(*SuccMBB);
        YamlMBB.Successors.push_back(StrOS.str());
    }

    // Print the machine instructions.
    YamlMBB.Instructions.reserve(MBB.size());
    std::string Str;
    for (const auto &MI : MBB) {
        raw_string_ostream StrOS(Str);
        MIPrinter(StrOS, MST, RegisterMaskIds).print(MI);
        YamlMBB.Instructions.push_back(StrOS.str());
        Str.clear();
    }
}

/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
/// register references and actual offsets.
///
void PEI::replaceFrameIndices(MachineFunction &Fn) {
  const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering();
  if (!TFI.needsFrameIndexResolution(Fn)) return;

  MachineModuleInfo &MMI = Fn.getMMI();
  const Function *F = Fn.getFunction();
  const Function *ParentF = MMI.getWinEHParent(F);
  unsigned FrameReg;
  if (F == ParentF) {
    WinEHFuncInfo &FuncInfo = MMI.getWinEHFuncInfo(Fn.getFunction());
    // FIXME: This should be unconditional but we have bugs in the preparation
    // pass.
    if (FuncInfo.UnwindHelpFrameIdx != INT_MAX)
      FuncInfo.UnwindHelpFrameOffset = TFI.getFrameIndexReferenceFromSP(
          Fn, FuncInfo.UnwindHelpFrameIdx, FrameReg);
    for (WinEHTryBlockMapEntry &TBME : FuncInfo.TryBlockMap) {
      for (WinEHHandlerType &H : TBME.HandlerArray) {
        unsigned UnusedReg;
        if (H.CatchObj.FrameIndex == INT_MAX)
          H.CatchObj.FrameOffset = INT_MAX;
        else
          H.CatchObj.FrameOffset =
              TFI.getFrameIndexReference(Fn, H.CatchObj.FrameIndex, UnusedReg);
      }
    }
  }

  // Store SPAdj at exit of a basic block.
  SmallVector<int, 8> SPState;
  SPState.resize(Fn.getNumBlockIDs());
  SmallPtrSet<MachineBasicBlock*, 8> Reachable;

  // Iterate over the reachable blocks in DFS order.
  for (auto DFI = df_ext_begin(&Fn, Reachable), DFE = df_ext_end(&Fn, Reachable);
       DFI != DFE; ++DFI) {
    int SPAdj = 0;
    // Check the exit state of the DFS stack predecessor.
    if (DFI.getPathLength() >= 2) {
      MachineBasicBlock *StackPred = DFI.getPath(DFI.getPathLength() - 2);
      assert(Reachable.count(StackPred) &&
             "DFS stack predecessor is already visited.\n");
      SPAdj = SPState[StackPred->getNumber()];
    }
    MachineBasicBlock *BB = *DFI;
    replaceFrameIndices(BB, Fn, SPAdj);
    SPState[BB->getNumber()] = SPAdj;
  }

  // Handle the unreachable blocks.
  for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
    if (Reachable.count(BB))
      // Already handled in DFS traversal.
      continue;
    int SPAdj = 0;
    replaceFrameIndices(BB, Fn, SPAdj);
  }
}

/// Split the basic block containing MI into two blocks, which are joined by
/// an unconditional branch.  Update data structures and renumber blocks to
/// account for this change and returns the newly created block.
MachineBasicBlock *BranchRelaxation::splitBlockBeforeInstr(MachineInstr &MI,
                                                           MachineBasicBlock *DestBB) {
  MachineBasicBlock *OrigBB = MI.getParent();

  // Create a new MBB for the code after the OrigBB.
  MachineBasicBlock *NewBB =
      MF->CreateMachineBasicBlock(OrigBB->getBasicBlock());
  MF->insert(++OrigBB->getIterator(), NewBB);

  // Splice the instructions starting with MI over to NewBB.
  NewBB->splice(NewBB->end(), OrigBB, MI.getIterator(), OrigBB->end());

  // Add an unconditional branch from OrigBB to NewBB.
  // Note the new unconditional branch is not being recorded.
  // There doesn't seem to be meaningful DebugInfo available; this doesn't
  // correspond to anything in the source.
  TII->insertUnconditionalBranch(*OrigBB, NewBB, DebugLoc());

  // Insert an entry into BlockInfo to align it properly with the block numbers.
  BlockInfo.insert(BlockInfo.begin() + NewBB->getNumber(), BasicBlockInfo());


  NewBB->transferSuccessors(OrigBB);
  OrigBB->addSuccessor(NewBB);
  OrigBB->addSuccessor(DestBB);

  // Cleanup potential unconditional branch to successor block.
  // Note that updateTerminator may change the size of the blocks.
  NewBB->updateTerminator();
  OrigBB->updateTerminator();

  // Figure out how large the OrigBB is.  As the first half of the original
  // block, it cannot contain a tablejump.  The size includes
  // the new jump we added.  (It should be possible to do this without
  // recounting everything, but it's very confusing, and this is rarely
  // executed.)
  BlockInfo[OrigBB->getNumber()].Size = computeBlockSize(*OrigBB);

  // Figure out how large the NewMBB is. As the second half of the original
  // block, it may contain a tablejump.
  BlockInfo[NewBB->getNumber()].Size = computeBlockSize(*NewBB);

  // All BBOffsets following these blocks must be modified.
  adjustBlockOffsets(*OrigBB);

  // Need to fix live-in lists if we track liveness.
  if (TRI->trackLivenessAfterRegAlloc(*MF))
    computeLiveIns(LiveRegs, *TRI, *NewBB);

  ++NumSplit;

  return NewBB;
}

void MIRPrinter::convert(ModuleSlotTracker &MST,
                         yaml::MachineBasicBlock &YamlMBB,
                         const MachineBasicBlock &MBB) {
  assert(MBB.getNumber() >= 0 && "Invalid MBB number");
  YamlMBB.ID = (unsigned)MBB.getNumber();
  if (const auto *BB = MBB.getBasicBlock()) {
    if (BB->hasName()) {
      YamlMBB.Name.Value = BB->getName();
    } else {
      int Slot = MST.getLocalSlot(BB);
      if (Slot == -1)
        YamlMBB.IRBlock.Value = "<badref>";
      else
        YamlMBB.IRBlock.Value = (Twine("%ir-block.") + Twine(Slot)).str();
    }
  }
  YamlMBB.Alignment = MBB.getAlignment();
  YamlMBB.AddressTaken = MBB.hasAddressTaken();
  YamlMBB.IsLandingPad = MBB.isLandingPad();
  for (const auto *SuccMBB : MBB.successors()) {
    std::string Str;
    raw_string_ostream StrOS(Str);
    MIPrinter(StrOS, MST, RegisterMaskIds, StackObjectOperandMapping)
        .printMBBReference(*SuccMBB);
    YamlMBB.Successors.push_back(StrOS.str());
  }
  if (MBB.hasSuccessorWeights()) {
    for (auto I = MBB.succ_begin(), E = MBB.succ_end(); I != E; ++I)
      YamlMBB.SuccessorWeights.push_back(
          yaml::UnsignedValue(MBB.getSuccWeight(I)));
  }
  // Print the live in registers.
  const auto *TRI = MBB.getParent()->getSubtarget().getRegisterInfo();
  assert(TRI && "Expected target register info");
  for (auto I = MBB.livein_begin(), E = MBB.livein_end(); I != E; ++I) {
    std::string Str;
    raw_string_ostream StrOS(Str);
    printReg(*I, StrOS, TRI);
    YamlMBB.LiveIns.push_back(StrOS.str());
  }
  // Print the machine instructions.
  YamlMBB.Instructions.reserve(MBB.size());
  std::string Str;
  for (const auto &MI : MBB) {
    raw_string_ostream StrOS(Str);
    MIPrinter(StrOS, MST, RegisterMaskIds, StackObjectOperandMapping).print(MI);
    YamlMBB.Instructions.push_back(StrOS.str());
    Str.clear();
  }
}

/// enterIntvAtEnd - Enter openli at the end of MBB.
/// PhiMBB is a successor inside openli where a PHI value is created.
/// Currently, all entries must share the same PhiMBB.
void SplitEditor::enterIntvAtEnd(MachineBasicBlock &A, MachineBasicBlock &B) {
  assert(openli_ && "openIntv not called before enterIntvAtEnd");

  SlotIndex EndA = lis_.getMBBEndIdx(&A);
  VNInfo *CurVNIA = curli_->getVNInfoAt(EndA.getPrevIndex());
  if (!CurVNIA) {
    DEBUG(dbgs() << "    enterIntvAtEnd, curli not live out of BB#"
                 << A.getNumber() << ".\n");
    return;
  }

  // Add a phi kill value and live range out of A.
  VNInfo *VNIA = insertCopy(*openli_, A, A.getFirstTerminator());
  openli_->addRange(LiveRange(VNIA->def, EndA, VNIA));

  // FIXME: If this is the only entry edge, we don't need the extra PHI value.
  // FIXME: If there are multiple entry blocks (so not a loop), we need proper
  // SSA update.

  // Now look at the start of B.
  SlotIndex StartB = lis_.getMBBStartIdx(&B);
  SlotIndex EndB = lis_.getMBBEndIdx(&B);
  const LiveRange *CurB = curli_->getLiveRangeContaining(StartB);
  if (!CurB) {
    DEBUG(dbgs() << "    enterIntvAtEnd: curli not live in to BB#"
                 << B.getNumber() << ".\n");
    return;
  }

  VNInfo *VNIB = openli_->getVNInfoAt(StartB);
  if (!VNIB) {
    // Create a phi value.
    VNIB = openli_->getNextValue(SlotIndex(StartB, true), 0, false,
                                 lis_.getVNInfoAllocator());
    VNIB->setIsPHIDef(true);
    VNInfo *&mapVNI = valueMap_[CurB->valno];
    if (mapVNI) {
      // Multiple copies - must create PHI value.
      abort();
    } else {
      // This is the first copy of dupLR. Mark the mapping.
      mapVNI = VNIB;
    }

  }

  DEBUG(dbgs() << "    enterIntvAtEnd: " << *openli_ << '\n');
}

// Transfer information from the LiveIn vector to the live ranges.
void LiveRangeCalc::updateLiveIns() {
  LiveRangeUpdater Updater;
  for (SmallVectorImpl<LiveInBlock>::iterator I = LiveIn.begin(),
         E = LiveIn.end(); I != E; ++I) {
    if (!I->DomNode)
      continue;
    MachineBasicBlock *MBB = I->DomNode->getBlock();
    assert(I->Value && "No live-in value found");
    SlotIndex Start, End;
    std::tie(Start, End) = Indexes->getMBBRange(MBB);

    if (I->Kill.isValid())
      // Value is killed inside this block.
      End = I->Kill;
    else {
      // The value is live-through, update LiveOut as well.
      // Defer the Domtree lookup until it is needed.
      assert(Seen.test(MBB->getNumber()));
      LiveOut[MBB] = LiveOutPair(I->Value, (MachineDomTreeNode *)0);
    }
    Updater.setDest(&I->LR);
    Updater.add(Start, End, I->Value);
  }
  LiveIn.clear();
}

void MIPrinter::printMBBReference(const MachineBasicBlock &MBB) {
  OS << "%bb." << MBB.getNumber();
  if (const auto *BB = MBB.getBasicBlock()) {
    if (BB->hasName())
      OS << '.' << BB->getName();
  }
}

// Transfer information from the LiveIn vector to the live ranges.
void LiveRangeCalc::updateLiveIns(VNInfo *OverrideVNI) {
    for (SmallVectorImpl<LiveInBlock>::iterator I = LiveIn.begin(),
            E = LiveIn.end(); I != E; ++I) {
        if (!I->DomNode)
            continue;
        MachineBasicBlock *MBB = I->DomNode->getBlock();

        VNInfo *VNI = OverrideVNI ? OverrideVNI : I->Value;
        assert(VNI && "No live-in value found");

        SlotIndex Start, End;
        tie(Start, End) = Indexes->getMBBRange(MBB);

        if (I->Kill.isValid())
            I->LI->addRange(LiveRange(Start, I->Kill, VNI));
        else {
            I->LI->addRange(LiveRange(Start, End, VNI));
            // The value is live-through, update LiveOut as well.  Defer the Domtree
            // lookup until it is needed.
            assert(Seen.test(MBB->getNumber()));
            LiveOut[MBB] = LiveOutPair(VNI, (MachineDomTreeNode *)0);
        }
    }
    LiveIn.clear();
}

/// Return the "bottom" block of a loop. This differs from
/// MachineLoop::getBottomBlock in that it works even if the loop is
/// discontiguous.
static MachineBasicBlock *LoopBottom(const MachineLoop *Loop) {
  MachineBasicBlock *Bottom = Loop->getHeader();
  for (MachineBasicBlock *MBB : Loop->blocks())
    if (MBB->getNumber() > Bottom->getNumber())
      Bottom = MBB;
  return Bottom;
}

/// isBlockInRange - Returns true if the distance between specific MI and
/// specific BB can fit in MI's displacement field.
bool AArch64BranchRelaxation::isBlockInRange(
  const MachineInstr &MI, const MachineBasicBlock &DestBB) const {
  unsigned BrOffset = getInstrOffset(MI);
  unsigned DestOffset = BlockInfo[DestBB.getNumber()].Offset;

  if (TII->isBranchInRange(MI.getOpcode(), BrOffset, DestOffset))
    return true;

  DEBUG(
    dbgs() << "Out of range branch to destination BB#" << DestBB.getNumber()
           << " from BB#" << MI.getParent()->getNumber()
           << " to " << DestOffset
           << " offset " << static_cast<int>(DestOffset - BrOffset)
           << '\t' << MI
  );

  return false;
}

/// isBlockInRange - Returns true if the distance between specific MI and
/// specific BB can fit in MI's displacement field.
bool BranchRelaxation::isBlockInRange(
  const MachineInstr &MI, const MachineBasicBlock &DestBB) const {
  int64_t BrOffset = getInstrOffset(MI);
  int64_t DestOffset = BlockInfo[DestBB.getNumber()].Offset;

  if (TII->isBranchOffsetInRange(MI.getOpcode(), DestOffset - BrOffset))
    return true;

  DEBUG(
    dbgs() << "Out of range branch to destination BB#" << DestBB.getNumber()
           << " from BB#" << MI.getParent()->getNumber()
           << " to " << DestOffset
           << " offset " << DestOffset - BrOffset
           << '\t' << MI
  );

  return false;
}