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

[Zeyi Xu via llvm-commits]

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@@ -379,6 +382,9 @@ def : SysReg<"mcause", 0x342>;
 def : SysReg<"mtval", 0x343>;
 def : DeprecatedSysRegName<"mbadaddr", 0x343>;
 def : SysReg<"mip", 0x344>;
+def : SysReg<"mistatus", 0x346>;
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zeyi2 wrote:

The machine-level CSR names and addresses are defined [here](https://github.com/riscv/riscv-fast-interrupt/blob/b623d1262ed40a255fd290333d8e0c6d0c44b2e8/src/aclic.adoc?plain=1#L694-L703).

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