[llvm] [GlobalISel][AArch64] Add G_FPTOSI_SAT/G_FPTOUI_SAT (PR #96297)

[David Green via llvm-commits]

davemgreen wrote:

> Could you link/fixes https://github.com/llvm/llvm-project/issues/94694 and maybe take the test case?

I believe that whilst #94694 is currently related to fptosi.sat, the same issue with infinite combines would come up from any other generic intrinsic. Prior to this patch GISel didn't know anything special about fptosi.sat, so it was just using a G_INTRINSIC and I believe the same problem would still exist for anything that wasn't now transformed into a G_FPTOSI_SAT.

https://github.com/llvm/llvm-project/pull/96297