Beispiel #1
0
void GCMachineCodeAnalysis::FindRegisterRoots(MachineFunction &MF) {
  const TargetFrameLowering *TFI = TM->getFrameLowering();
  assert(TFI && "TargetRegisterInfo not available!");

  unsigned PointIndex = 0;
  for (MachineFunction::iterator BBI = MF.begin(),
                                 BBE = MF.end(); BBI != BBE; ++BBI) {
    for (MachineBasicBlock::iterator MI = BBI->begin(),
                                     ME = BBI->end(); MI != ME; ++MI) {
      if (MI->isGCLabel())
        PointIndex = FI->getPointIndex(MI->getOperand(0).getMCSymbol());
      if (!MI->isGCRegRoot())
        continue;

      unsigned RootIndex = MI->getOperand(MI->getNumOperands() - 1).getImm();
      if (FI->isRootGlobal(RootIndex))
        continue;

      FI->setLive(PointIndex, RootIndex, true);

      if (!FI->getRoot(RootIndex).isReg())
        continue;
      GCRootLoc Loc;
      Loc.PhysReg = MI->getOperand(0).getReg();
      FI->setRootLoc(RootIndex, Loc);
    }
  }
}
Beispiel #2
0
bool GCMachineCodeFixup::runOnMachineFunction(MachineFunction &MF) {
  // Quick exit for functions that do not use GC.
  if (!MF.getFunction()->hasGC())
    return false;

  const TargetMachine &TM = MF.getTarget();
  const TargetInstrInfo *TII = TM.getInstrInfo();
  GCModuleInfo &GMI = getAnalysis<GCModuleInfo>();
  GCFunctionInfo &GCFI = GMI.getFunctionInfo(*MF.getFunction());

  for (MachineFunction::iterator MBBI = MF.begin(),
                                 MBBE = MF.end(); MBBI != MBBE; ++MBBI) {
    for (MachineBasicBlock::iterator MII = MBBI->begin(),
                                     MIE = MBBI->end(); MII != MIE;) {
      if (!MII->isGCRegRoot() || !MII->getOperand(0).isReg()) {
        ++MII;
        continue;
      }

      // Trace the register back to its location at the site of the call (either
      // a physical reg or a frame index).
      bool TracingReg = true;
      unsigned TracedReg = MII->getOperand(0).getReg();
      int FrameIndex;

      MachineBasicBlock::iterator PrevII = MII;
      for (--PrevII;; --PrevII) {
        if (PrevII->isGCRegRoot() && PrevII->getOperand(0).isReg())
          break;
        if (PrevII->isCall())
          break;

        int FI;

        // Trace back through register reloads.
        unsigned Reg =
          TM.getInstrInfo()->isLoadFromStackSlotPostFE(&*PrevII, FI);
        if (Reg) {
          // This is a reload. If we're tracing this register, start tracing the
          // frame index instead.
          if (TracingReg && TracedReg == Reg) {
            TracingReg = false;
            FrameIndex = FI;
          }
          continue;
        }

        // Trace back through spills.
        if (TM.getInstrInfo()->isStoreToStackSlotPostFE(&*PrevII, FI))
          continue;

        // Trace back through register-to-register copies.
        if (PrevII->isCopy()) {
          if (TracingReg && TracedReg == PrevII->getOperand(0).getReg())
            TracedReg = PrevII->getOperand(1).getReg();
          continue;
        }

        // Trace back through non-register GC_REG_ROOT instructions.
        if (PrevII->isGCRegRoot() && !PrevII->getOperand(0).isReg())
          continue;

        DEBUG(dbgs() << "Bad instruction: " << *PrevII);
        llvm_unreachable("GC_REG_ROOT found in an unexpected location!");
      }

      // Now we've reached either a call or another GC_REG_ROOT instruction.
      // Move the GC_REG_ROOT instruction we're considering to the right place,
      // and rewrite it if necessary.
      //
      // Also, tell the GCFunctionInfo about the frame index, since this is
      // our only chance -- the frame indices will be deleted by the time
      // GCMachineCodeAnalysis runs.
      ++PrevII;
      unsigned RootIndex = MII->getOperand(1).getImm();
      MachineInstr *NewMI;
      if (TracingReg) {
        MachineInstrBuilder MIB = BuildMI(MF, MII->getDebugLoc(),
                                          TII->get(TargetOpcode::GC_REG_ROOT));
        MIB.addReg(TracedReg).addImm(RootIndex);
        NewMI = MIB;
      } else {
        NewMI = TII->emitFrameIndexGCRegRoot(MF, FrameIndex, RootIndex,
                                             MII->getDebugLoc());
        GCFI.spillRegRoot(RootIndex, FrameIndex);
      }

      MBBI->insert(PrevII, NewMI);

      MachineBasicBlock::iterator NextII = MII;
      ++NextII;
      MII->eraseFromParent();
      MII = NextII;
    }
  }

  return true;
}