[llvm] [RISCV] Add groupid/bitmask for RISC-V extension (PR #94440)

[Craig Topper via llvm-commits]

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@@ -12,6 +12,11 @@ class RISCVExtension<string name, int major, int minor, string desc,
   bit Experimental = false;
 }
 
+class RISCVExtensionBitmask<bits<3> groupID, int bitmaskShift> {
+    bits<3> GroupID = groupID;
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topperc wrote:

Can we use `int` for these if we store bit position instead of bit mask?

https://github.com/llvm/llvm-project/pull/94440