[clang] [clang] Support -Wa, options -mmsa and -mno-msa (PR #99615)

[Fangrui Song via cfe-commits]

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@@ -5337,7 +5337,9 @@ def mmadd4 : Flag<["-"], "mmadd4">, Group<m_mips_Features_Group>,
 def mno_madd4 : Flag<["-"], "mno-madd4">, Group<m_mips_Features_Group>,
   HelpText<"Disable the generation of 4-operand madd.s, madd.d and related instructions.">;
 def mmsa : Flag<["-"], "mmsa">, Group<m_mips_Features_Group>,
-  HelpText<"Enable MSA ASE (MIPS only)">;
+  Visibility<[ClangOption, CC1Option, CC1AsOption]>,
+  HelpText<"Enable MSA ASE (MIPS only)">,
+  MarshallingInfoFlag<CodeGenOpts<"Msa">>;
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MaskRay wrote:

Since this is MIPS specific. `MipsMsa` might be better.

https://github.com/llvm/llvm-project/pull/99615