[llvm] [RISCV][VLOPT] Add vfirst and vcpop to getOperandInfo (PR #122295)

[Philip Reames via llvm-commits]

================
@@ -488,6 +488,10 @@ getOperandLog2EEW(const MachineOperand &MO, const MachineRegisterInfo *MRI) {
   case RISCV::VFCVT_F_X_V:
   // Vector Floating-Point Merge Instruction
   case RISCV::VFMERGE_VFM:
+  // Vector count population in mask vcpop.m
+  // vfirst find-first-set mask bit
+  case RISCV::VCPOP_M:
+  case RISCV::VFIRST_M:
----------------
preames wrote:

Shouldn't the source operand for these both be a mask operand and thus 0?  Or is it the case that the MILog2SEW is guaranteed to be zero in this case?

After thinking about it for a bit, I think that is the case.  Please confirm, but consider this a non-blocking comment as long as that is in fact true.  

https://github.com/llvm/llvm-project/pull/122295