[llvm] [RISCV] Add basic Mach-O triple support. (PR #141682)

[Jonas Devlieghere via llvm-commits]

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@@ -2838,6 +2842,15 @@ Triple MachOObjectFile::getArchTriple(uint32_t CPUType, uint32_t CPUSubType,
     default:
       return Triple();
     }
+  case MachO::CPU_TYPE_RISCV:
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JDevlieghere wrote:

I agree that in hindsight, using the alternative names would have been nicer. Internally that name is used extensively so changing that isn't quite that simple, even if someone was motivated to change that at this point. And `BinaryFormat/MachO.h` should match the "spec" which Apple controls (and has decided on `CPU_TYPE_RISCV`) even if the headers/defines aren't public.

https://github.com/llvm/llvm-project/pull/141682