[llvm] [RISCV] Specify FilterClassField to filter out unneeded pseudos (PR #65460)

[Craig Topper via llvm-commits]

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@@ -527,11 +527,17 @@ class RISCVVPseudo {
   Instruction BaseInstr = !cast<Instruction>(PseudoToVInst<NAME>.VInst);
   // SEW = 0 is used to denote that the Pseudo is not SEW specific (or unknown).
   bits<8> SEW = 0;
+  bit IsNeeded = !cond(
+    !ne(!find(NAME, "PseudoVMCLR"), -1): 0,
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topperc wrote:

Can we set this from `VPseudoNullaryPseudoM`? Doing string matching here feels hacky.

https://github.com/llvm/llvm-project/pull/65460