[llvm] [TRI][RISCV] Add methods to get common register class of two registers (PR #118435)

[Pengcheng Wang via llvm-commits]

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@@ -222,6 +222,25 @@ TargetRegisterInfo::getMinimalPhysRegClass(MCRegister reg, MVT VT) const {
   return BestRC;
 }
 
+const TargetRegisterClass *TargetRegisterInfo::getCommonMinimalPhysRegClass(
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wangpc-pp wrote:

Done. I used type traits to decide the value, please have a look.

https://github.com/llvm/llvm-project/pull/118435