[RISCV] Move PseudoVSET(I)VLI expansion to use PseudoInstExpansion. (#102496)

Instead of expanding in RISCVExpandPseudoInsts, expand during
MachineInstr to MCInst lowering.

We weren't doing anything in expansion other than copying operands.

Author: topperc

llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp

@@ -46,7 +46,6 @@ class RISCVExpandPseudo : public MachineFunctionPass {
                 MachineBasicBlock::iterator &NextMBBI);
   bool expandCCOp(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
                   MachineBasicBlock::iterator &NextMBBI);
-  bool expandVSetVL(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI);
   bool expandVMSET_VMCLR(MachineBasicBlock &MBB,
                          MachineBasicBlock::iterator MBBI, unsigned Opcode);
   bool expandRV32ZdinxStore(MachineBasicBlock &MBB,
@@ -139,10 +138,6 @@ bool RISCVExpandPseudo::expandMI(MachineBasicBlock &MBB,
   case RISCV::PseudoCCORN:
   case RISCV::PseudoCCXNOR:
     return expandCCOp(MBB, MBBI, NextMBBI);
-  case RISCV::PseudoVSETVLI:
-  case RISCV::PseudoVSETVLIX0:
-  case RISCV::PseudoVSETIVLI:
-    return expandVSetVL(MBB, MBBI);
   case RISCV::PseudoVMCLR_M_B1:
   case RISCV::PseudoVMCLR_M_B2:
   case RISCV::PseudoVMCLR_M_B4:
@@ -258,36 +253,6 @@ bool RISCVExpandPseudo::expandCCOp(MachineBasicBlock &MBB,
   return true;
 }
 
-bool RISCVExpandPseudo::expandVSetVL(MachineBasicBlock &MBB,
-                                     MachineBasicBlock::iterator MBBI) {
-  assert(MBBI->getNumExplicitOperands() == 3 && MBBI->getNumOperands() >= 5 &&
-         "Unexpected instruction format");
-
-  DebugLoc DL = MBBI->getDebugLoc();
-
-  assert((MBBI->getOpcode() == RISCV::PseudoVSETVLI ||
-          MBBI->getOpcode() == RISCV::PseudoVSETVLIX0 ||
-          MBBI->getOpcode() == RISCV::PseudoVSETIVLI) &&
-         "Unexpected pseudo instruction");
-  unsigned Opcode;
-  if (MBBI->getOpcode() == RISCV::PseudoVSETIVLI)
-    Opcode = RISCV::VSETIVLI;
-  else
-    Opcode = RISCV::VSETVLI;
-  const MCInstrDesc &Desc = TII->get(Opcode);
-  assert(Desc.getNumOperands() == 3 && "Unexpected instruction format");
-
-  Register DstReg = MBBI->getOperand(0).getReg();
-  bool DstIsDead = MBBI->getOperand(0).isDead();
-  BuildMI(MBB, MBBI, DL, Desc)
-      .addReg(DstReg, RegState::Define | getDeadRegState(DstIsDead))
-      .add(MBBI->getOperand(1))  // VL
-      .add(MBBI->getOperand(2)); // VType
-
-  MBBI->eraseFromParent(); // The pseudo instruction is gone now.
-  return true;
-}
-
 bool RISCVExpandPseudo::expandVMSET_VMCLR(MachineBasicBlock &MBB,
                                           MachineBasicBlock::iterator MBBI,
                                           unsigned Opcode) {

llvm/lib/Target/RISCV/RISCVInstrInfoVPseudos.td

@@ -6136,10 +6136,13 @@ let hasSideEffects = 0, mayLoad = 0, mayStore = 0, Defs = [VL, VTYPE] in {
 // be accidentally be made X0 by MachineIR optimizations. To satisfy the
 // verifier, we also need a GPRX0 instruction for the special encodings.
 def PseudoVSETVLI : Pseudo<(outs GPR:$rd), (ins GPRNoX0:$rs1, VTypeIOp11:$vtypei), []>,
+                    PseudoInstExpansion<(VSETVLI GPR:$rd, GPR:$rs1, VTypeIOp11:$vtypei)>,
                     Sched<[WriteVSETVLI, ReadVSETVLI]>;
 def PseudoVSETVLIX0 : Pseudo<(outs GPR:$rd), (ins GPRX0:$rs1, VTypeIOp11:$vtypei), []>,
+                      PseudoInstExpansion<(VSETVLI GPR:$rd, GPR:$rs1, VTypeIOp11:$vtypei)>,
                       Sched<[WriteVSETVLI, ReadVSETVLI]>;
 def PseudoVSETIVLI : Pseudo<(outs GPR:$rd), (ins uimm5:$rs1, VTypeIOp10:$vtypei), []>,
+                     PseudoInstExpansion<(VSETIVLI GPR:$rd, uimm5:$rs1, VTypeIOp10:$vtypei)>,
                      Sched<[WriteVSETIVLI]>;
 }