C++ LabelInstruction::getTrace方法代码示例

void LinearScan::allocRegsToTraceAux(Trace* trace) {
  IRInstruction::List& instructionList = trace->getInstructionList();
  IRInstruction::Iterator it;
  for (it = instructionList.begin();
       it != instructionList.end();
       it++) {
    IRInstruction* inst = *it;
    allocRegToInstruction(trace, it);
    if (RuntimeOption::EvalDumpIR > 3) {
      std::cout << "--- allocated to instruction: ";
      inst->print(std::cout);
      std::cout << "\n";
    }
    if (inst->isControlFlowInstruction()) {
      // This instruction may transfer control to another trace
      // If this is the last instruction in the trace that can branch
      // to this target trace, then allocate registers to the target
      // trace, effectively linearizing the target trace after inst.
      LabelInstruction* label = inst->getLabel();
      if (label != NULL && label->getId() == inst->getId() + 1) {
        allocRegsToTraceAux(label->getTrace());
      }
    }
  }

  // Insert spill instructions.
  // Reload instructions are already added in <allocRegsToTrace>.
  for (it = instructionList.begin(); it != instructionList.end(); ) {
    IRInstruction::Iterator next = it; ++next;
    IRInstruction* inst = *it;
    if (inst->getOpcode() != Reload) {
      // Reloaded SSATmps needn't be spilled again.
      if (SSATmp* dst = inst->getDst()) {
        int32 slotId = dst->getSpillSlot();
        if (slotId != -1) {
          // If this instruction is marked to be spilled,
          // add a spill right afterwards.
          IRInstruction* spillInst =
            m_slots[slotId].m_slotTmp->getInstruction();
          instructionList.insert(next, spillInst);
          spillInst->setParent(trace);
        }
      }
    }
    it = next;
  }
}

void LinearScan::collectNativesAux(Trace* trace) {
  IRInstruction::List& instList = trace->getInstructionList();
  for (IRInstruction::Iterator it = instList.begin();
       it != instList.end();
       ++it) {
    IRInstruction* inst = *it;
    if (inst->isNative()) {
      m_natives.push_back(inst);
    }
    if (inst->isControlFlowInstruction()) {
      LabelInstruction* label = inst->getLabel();
      if (label != NULL && label->getId() == inst->getId() + 1) {
        collectNativesAux(label->getTrace());
      }
    }
  }
}

void LinearScan::rematerializeAux(Trace* trace,
                                  SSATmp* curSp,
                                  SSATmp* curFp,
                                  std::vector<SSATmp*> localValues) {
  IRInstruction::List& instList = trace->getInstructionList();
  for (IRInstruction::Iterator it = instList.begin();
       it != instList.end();
       ++it) {
    IRInstruction* inst = *it;
    Opcode opc = inst->getOpcode();
    SSATmp* dst = inst->getDst();
    if (opc == DefFP || opc == FreeActRec) {
      curFp = dst;
      ASSERT(dst && dst->getReg() == rVmFp);
    }
    if (opc == Reload) {
      // s = Spill t0
      // t = Reload s
      SSATmp* spilledTmp = getSpilledTmp(dst);
      IRInstruction* spilledInst = spilledTmp->getInstruction();
      IRInstruction* newInst = NULL;
      if (spilledInst->isRematerializable() ||
          (spilledInst->getOpcode() == LdStack &&
           spilledInst->getSrc(0) == curSp)) {
        // XXX: could change <newInst> to the non-check version.
        // Rematerialize those rematerializable instructions (i.e.,
        // isRematerializable returns true) and LdStack.
        newInst = spilledInst->clone(m_irFactory);
        // The new instruction needn't have an exit label, because it is always
        // dominated by the original instruction.
        newInst->setLabel(NULL);
      } else {
        // Rematerialize LdLoc.
        std::vector<SSATmp*>::iterator pos =
          std::find(localValues.begin(),
                    localValues.end(),
                    canonicalize(spilledTmp));
        // Search for a local that stores the value of <spilledTmp>.
        if (pos != localValues.end()) {
          size_t locId = pos - localValues.begin();
          ASSERT(curFp != NULL);
          ConstInstruction constInst(curFp, Local(locId));
          IRInstruction* ldHomeInst =
            m_irFactory->cloneInstruction(&constInst);
          newInst = m_irFactory->ldLoc(m_irFactory->getSSATmp(ldHomeInst),
                                       dst->getType(),
                                       NULL);
        }
      }
      if (newInst) {
        newInst->setDst(dst);
        newInst->getDst()->setInstruction(newInst);
        *it = newInst;
        newInst->setParent(trace);
      }
    }

    // Updating <curSp> and <localValues>.
    if (dst && dst->getReg() == rVmSp) {
      // <inst> modifies the stack pointer.
      curSp = dst;
    }
    if (opc == LdLoc || opc == StLoc || opc == StLocNT) {
      // dst = LdLoc home
      // StLoc/StLocNT home, src
      int locId = getLocalIdFromHomeOpnd(inst->getSrc(0));
      SSATmp* localValue = (opc == LdLoc ? dst : inst->getSrc(1));
      if (int(localValues.size()) < locId + 1) {
        localValues.resize(locId + 1);
      }
      localValues[locId] = canonicalize(localValue);
    }

    if (inst->isControlFlowInstruction()) {
      LabelInstruction* label = inst->getLabel();
      if (label != NULL && label->getId() == inst->getId() + 1) {
        rematerializeAux(label->getTrace(), curSp, curFp, localValues);
      }
    }
  }
}

uint32 LinearScan::assignSpillLocAux(Trace* trace,
                                     uint32 nextSpillLoc,
                                     uint32 nextMmxReg) {
  IRInstruction::List& instructionList = trace->getInstructionList();
  for (IRInstruction::Iterator it = instructionList.begin();
       it != instructionList.end();
       ++it) {
    IRInstruction* inst = *it;
    if (getNextNative() == inst) {
      ASSERT(!m_natives.empty());
      m_natives.pop_front();
    }
    if (inst->getOpcode() == Spill) {
      SSATmp* dst = inst->getDst();
      SSATmp* src = inst->getSrc(0);
      for (int locIndex = 0;
           locIndex < src->numNeededRegs();
           ++locIndex) {
        if (dst->getLastUseId() <= getNextNativeId()) {
          TRACE(3, "[counter] 1 spill a tmp that does not span native\n");
        } else {
          TRACE(3, "[counter] 1 spill a tmp that spans native\n");
        }

        const bool allowMmxSpill = RuntimeOption::EvalHHIREnableMmx &&
          // The live range of the spill slot doesn't span native calls,
          // and we still have free MMX registers.
          dst->getLastUseId() <= getNextNativeId() &&
          nextMmxReg < (uint32)NumMmxRegs;

        dst->setSpillInfo(locIndex,
          allowMmxSpill
            ? SpillInfo(RegNumber(nextMmxReg++))
            : SpillInfo(nextSpillLoc++)
        );
        if (allowMmxSpill) {
          TRACE(3, "[counter] 1 spill to mmx\n");
        } else {
          TRACE(3, "[counter] 1 spill to memory\n");
        }
      }
    }
    if (inst->getOpcode() == Reload) {
      SSATmp* src = inst->getSrc(0);
      for (int locIndex = 0;
           locIndex < src->numNeededRegs();
           ++locIndex) {
        if (src->getSpillInfo(locIndex).type() == SpillInfo::MMX) {
          TRACE(3, "[counter] reload from mmx\n");
        } else {
          TRACE(3, "[counter] reload from memory\n");
        }
      }
    }
    if (inst->isControlFlowInstruction()) {
      LabelInstruction* label = inst->getLabel();
      if (label != NULL && label->getId() == inst->getId() + 1) {
        nextSpillLoc = assignSpillLocAux(label->getTrace(),
                                         nextSpillLoc,
                                         nextMmxReg);
      }
    }
  }
  return nextSpillLoc;
}

void eliminateDeadCode(Trace* trace, IRFactory* irFactory) {
  IRInstruction::List wl; // worklist of live instructions
  Trace::List& exitTraces = trace->getExitTraces();
  // first mark all exit traces as unreachable by setting the id on
  // their labels to 0
  for (Trace::Iterator it = exitTraces.begin();
       it != exitTraces.end();
       it++) {
    Trace* trace = *it;
    trace->getLabel()->setId(DEAD);
  }

  // mark the essential instructions and add them to the initial
  // work list; also mark the exit traces that are reachable by
  // any control flow instruction in the main trace.
  initInstructions(trace, wl);
  for (Trace::Iterator it = exitTraces.begin();
       it != exitTraces.end();
       it++) {
    // only process those exit traces that are reachable from
    // the main trace
    Trace* trace = *it;
    if (trace->getLabel()->getId() != DEAD) {
      initInstructions(trace, wl);
    }
  }

  // process the worklist
  while (!wl.empty()) {
    IRInstruction* inst = wl.front();
    wl.pop_front();
    for (uint32 i = 0; i < inst->getNumSrcs(); i++) {
      SSATmp* src = inst->getSrc(i);
      if (src->getInstruction()->isDefConst()) {
        continue;
      }
      IRInstruction* srcInst = src->getInstruction();
      if (srcInst->getId() == DEAD) {
        srcInst->setId(LIVE);
        wl.push_back(srcInst);
      }
      // <inst> consumes <srcInst> which is an IncRef,
      // so we mark <srcInst> as REFCOUNT_CONSUMED.
      if (inst->consumesReference(i) && srcInst->getOpcode() == IncRef) {
        if (inst->getParent()->isMain() || !srcInst->getParent()->isMain()) {
          // <srcInst> is consumed from its own trace.
          srcInst->setId(REFCOUNT_CONSUMED);
        } else {
          // <srcInst> is consumed off trace.
          if (srcInst->getId() != REFCOUNT_CONSUMED) {
            // mark <srcInst> as REFCOUNT_CONSUMED_OFF_TRACE unless it is
            // also consumed from its own trace.
            srcInst->setId(REFCOUNT_CONSUMED_OFF_TRACE);
          }
        }
      }
    }
  }

  // Optimize IncRefs and DecRefs.
  optimizeRefCount(trace);
  for (Trace::Iterator it = exitTraces.begin(); it != exitTraces.end(); ++it) {
    optimizeRefCount(*it);
  }

  if (RuntimeOption::EvalHHIREnableSinking) {
    // Sink IncRefs consumed off trace.
    IRInstruction::List toSink;
    sinkIncRefs(trace, irFactory, toSink);
  }

  // now remove instructions whose id == DEAD
  removeDeadInstructions(trace);
  for (Trace::Iterator it = exitTraces.begin(); it != exitTraces.end(); it++) {
    removeDeadInstructions(*it);
  }

  // If main trace ends with an unconditional jump, copy the target of
  // the jump to the end of the trace
  IRInstruction::List& instList = trace->getInstructionList();
  IRInstruction::Iterator lastInst = instList.end();
  lastInst--; // go back to the last instruction
  IRInstruction* jmpInst = *lastInst;
  if (jmpInst->getOpcode() == Jmp_) {
    Trace* targetTrace = jmpInst->getLabel()->getTrace();
    IRInstruction::List& targetInstList = targetTrace->getInstructionList();
    IRInstruction::Iterator instIter = targetInstList.begin();
    instIter++; // skip over label
    // update the parent trace of the moved instructions
    for (IRInstruction::Iterator it = instIter;
         it != targetInstList.end();
         ++it) {
      (*it)->setParent(trace);
    }
    instList.splice(lastInst, targetInstList, instIter, targetInstList.end());
    // delete the jump instruction
    instList.erase(lastInst);
  }

  // If main trace ends with a conditional jump with no side-effects on exit,
//.........这里部分代码省略.........