[clang] [llvm] [RISCV][GISel] Add support for quadruple-precision floating point ABIs (PR #195166)

[Sam Elliott via cfe-commits]

https://github.com/lenary commented:

This touches more than just GISel, so remove `[GISel]` from the description.

I haven't managed a particularly in-depth review, but it's looking mostly right apart from what I commented on below.

I'm not sure we have good handling for dealing with Quad FP values in ISel yet, but I guess that's coming soon.


https://github.com/llvm/llvm-project/pull/195166