[clang] [llvm] [Mips] Add r5900 (PlayStation 2 Emotion Engine) CPU support (PR #176666)

[Fredrik Noring via cfe-commits]

frno7 wrote:

> The `-mfix-r5900` option does seem usefull then, so I added it back in.

Great, many thanks, @rickgaiser!

> For inline assembly there is currently no fix or warning. I could add a new warning flag `-Wmips-r5900-short-loop`, only active when targeting R5900 or when `-mfix-r5900` is used?

That would be very nice indeed, and helpful to avoid difficult-to-find erratum disasters. I recall that @maciej-w-rozycki objected to it for GAS some years ago, on the grounds that they who wield the `noreorder` directive “know what they are doing”. But as mentioned, the poor R5900 is typically ignored by the authors in such cases. Maciej, what’s your assessment today? :-)

https://github.com/llvm/llvm-project/pull/176666