[clang] [llvm] [RISCV][MC] Add experimental Smidctrl, Ssidctrl, Smnip, and Ssnip support (PR #218108)

[Zeyi Xu via llvm-commits]

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@@ -166,6 +166,9 @@ def : SysReg<"scause", 0x142>;
 def : SysReg<"stval", 0x143>;
 def : DeprecatedSysRegName<"sbadaddr", 0x143>;
 def : SysReg<"sip", 0x144>;
+def : SysReg<"sistatus", 0x146>;
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zeyi2 wrote:

The supervisor-level CSR names and addresses are defined [here](https://github.com/riscv/riscv-fast-interrupt/blob/b623d1262ed40a255fd290333d8e0c6d0c44b2e8/src/aclic.adoc?plain=1#L885-L894).

https://github.com/llvm/llvm-project/pull/218108