[RISCV] Temporary in vmsge(u).vx pseudo instructions can't be V0.

This was checked in some asserts, but not enforced by the
instruction matching.

There's still a second bug that we don't check that vt and vd
are different registers, but that will require custom checking.

Differential Revision: https://reviews.llvm.org/D100928

llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp

@@ -2419,6 +2419,8 @@ void RISCVAsmParser::emitVMSGE(MCInst &Inst, unsigned Opcode, SMLoc IDLoc,
     // pseudoinstruction: vmsge{u}.vx vd, va, x, v0.t, vt
     // expansion: vmslt{u}.vx vt, va, x; vmandnot.mm vt, v0, vt; vmandnot.mm vd,
     // vd, v0; vmor.mm vd, vt, vd
+    assert(Inst.getOperand(1).getReg() != RISCV::V0 &&
+           "The temporary vector register should not be V0.");
     emitToStreamer(Out, MCInstBuilder(Opcode)
                             .addOperand(Inst.getOperand(1))
                             .addOperand(Inst.getOperand(2))

llvm/lib/Target/RISCV/RISCVInstrInfoV.td

@@ -663,10 +663,10 @@ def PseudoVMSGEU_VX_M : Pseudo<(outs VRNoV0:$vd),
 def PseudoVMSGE_VX_M : Pseudo<(outs VRNoV0:$vd),
                               (ins VR:$vs2, GPR:$rs1, VMaskOp:$vm),
                               [], "vmsge.vx", "$vd, $vs2, $rs1$vm">;
-def PseudoVMSGEU_VX_M_T : Pseudo<(outs VR:$vd, VR:$scratch),
+def PseudoVMSGEU_VX_M_T : Pseudo<(outs VR:$vd, VRNoV0:$scratch),
                                  (ins VR:$vs2, GPR:$rs1, VMaskOp:$vm),
                                  [], "vmsgeu.vx", "$vd, $vs2, $rs1$vm, $scratch">;
-def PseudoVMSGE_VX_M_T : Pseudo<(outs VR:$vd, VR:$scratch),
+def PseudoVMSGE_VX_M_T : Pseudo<(outs VR:$vd, VRNoV0:$scratch),
                                 (ins VR:$vs2, GPR:$rs1, VMaskOp:$vm),
                                 [], "vmsge.vx", "$vd, $vs2, $rs1$vm, $scratch">;
 }

llvm/test/MC/RISCV/rvv/invalid.s

@@ -661,3 +661,8 @@ vs8r.v v6, (a0)
 vs8r.v v7, (a0)
 # CHECK-ERROR: invalid operand for instruction
 
+vmsge.vx v2, v4, a0, v0.t, v0
+# CHECK-ERROR: invalid operand for instruction
+
+vmsgeu.vx v2, v4, a0, v0.t, v0
+# CHECK-ERROR: invalid operand for instruction