How to get scheduling class of MCInstr?

Question

I'm implementing llvm-mc in downstream compiler for VLIW architecture. Before encoding a bundle, I need to check that the instructions in that bundle are in correct order. To check this order I need to get scheduling units from MCInst, but I don't see a way to do it.

In Hexagon target there is a method HexagonInstrInfo::getUnits(), which implemented like this:

InstrStage::FuncUnits HexagonInstrInfo::getUnits(const MachineInstr &MI) const {
  const InstrItineraryData &II = *Subtarget.getInstrItineraryData();
  const InstrStage &IS = *II.beginStage(MI.getDesc().getSchedClass());
 
  return IS.getUnits();
}

But TargetInstructionInfo is not available inside MCCodeEmitter. I have access to MCInstr, MCSubtargetInfo, MCInstrInfo and MCContext. (that's the method, I'm trying to implement.)

Answer 1

Turns out, that I can access InstStage via:

 const InstrItineraryData &II = /*MCSubtargetInfo*/STI.getInstrItineraryForCPU(STI.getCPU());

InstrStage &IS = II
.beginStage(
    MCII/* MCInstrInfo */
.get(
        /* MCInstr& */MI.getOpcode().getSchedClass());
InstrStage::FuncUnits Units = II.getUnits();