[clang] [llvm] [RISCV][MC] Add assembler support for XRivosVisni (PR #128773)

[Philip Reames via llvm-commits]

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@@ -10,6 +10,46 @@
 //
 //===----------------------------------------------------------------------===//
 
+class RVInstVXI<bits<6> funct6, RISCVVFormat opv, dag outs, dag ins,
+                string opcodestr, string argstr>
+    : RVInst<outs, ins, opcodestr, argstr, [], InstFormatR> {
+  bits<5> imm;
+  bits<5> rs1;
+  bits<5> vd;
+  bit vm;
+
+  let Inst{31-26} = funct6;
+  let Inst{25} = vm;
+  let Inst{24-20} = imm;
+  let Inst{19-15} = rs1;
+  let Inst{14-12} = opv.Value;
+  let Inst{11-7} = vd;
+  let Inst{6-0} = OPC_OP_V.Value;
----------------
preames wrote:

If you look at the instruction definitions which use these classes, they override this.  However, that's maybe a code smell of it's own.  I'd originally written these classes modeling RVInst ones, thinking we might have a standardized example eventually, and I'd kill off the custom ones.  However, since we don't, maybe I should rename and specialize them for the custom user here?  

Any preference?  It looks like SiFive specialized the custom ones, and avoided the generic sounding naming, so maybe we should do that here?  

https://github.com/llvm/llvm-project/pull/128773