[llvm] [SPIR-V] Implement SPV_KHR_float_controls2 (PR #146941)

[Nathan Gauër via llvm-commits]

https://github.com/Keenuts commented:

sorry thought I had published the comments.
Not very familiar with the float extensions & float behaviors in general, so couple observations. Will defer approval to others on the spec correctness, but OK to get this merged otherwise.

https://github.com/llvm/llvm-project/pull/146941