[RISCV][VLOPT] Add support for vfclass.v (#148246)

This PR adds support for the vfclass.v instruction in the RISC-V
VLOptimizer.

Author: mikhailramalho

llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp

@@ -1139,6 +1139,8 @@ static bool isSupportedInstr(const MachineInstr &MI) {
   case RISCV::VMFLE_VV:
   case RISCV::VMFGT_VF:
   case RISCV::VMFGE_VF:
+  // Vector Floating-Point Classify Instruction
+  case RISCV::VFCLASS_V:
   // Vector Floating-Point Merge Instruction
   case RISCV::VFMERGE_VFM:
   // Vector Floating-Point Move Instruction

llvm/test/CodeGen/RISCV/rvv/vl-opt-instrs.ll

@@ -5448,9 +5448,8 @@ define <vscale x 4 x i32> @vfclass_v(<vscale x 4 x float> %a, <vscale x 4 x i32>
 ;
 ; VLOPT-LABEL: vfclass_v:
 ; VLOPT:       # %bb.0:
-; VLOPT-NEXT:    vsetvli a1, zero, e32, m2, ta, ma
-; VLOPT-NEXT:    vfclass.v v8, v8
 ; VLOPT-NEXT:    vsetvli zero, a0, e32, m2, ta, ma
+; VLOPT-NEXT:    vfclass.v v8, v8
 ; VLOPT-NEXT:    vadd.vv v8, v8, v10
 ; VLOPT-NEXT:    ret
   %1 = call <vscale x 4 x i32> @llvm.riscv.vfclass.nxv4i32(<vscale x 4 x i32> poison, <vscale x 4 x float> %a, iXLen -1)