[clang] [llvm] [MIPS] Add support for O64 Mips ABI (PR #223990)

[Jiaxun Yang via cfe-commits]

FlyGoat wrote:

I believe O64 ABI is a GCC extention that is dropped long ago? As far as I know Nintendo64 is actually using 32-bit C calling convention (i.e. O32), which uses 32-bit argument words.

SGI never implement O64 with their MipsPro, could you please elaborate a bit on your use case in homebrew?

Maybe what you actually want is `-mgp64` with `o32` ABI?

https://github.com/llvm/llvm-project/pull/223990