[llvm] [LLVM] Slay undead copysign code (PR #111269)

[via llvm-commits]

workingjubilee wrote:

I _believe_ the PowerPC target code has setOperationAction for ppc_f128 in a way that somehow still finds this codepath. As it is logically the only user of this codepath, it seemed harmless to just leave it. If you want, I can go muck about inside llvm/lib/Target/PowerPC/PPCISelLowering.cpp so that the regression tests pass and we can completely remove this, but my initial inclination was to not bother because the Rust frontend doesn't use these types at all and I will be hacking pretty wildly at that point.

I believe the x87 case might actually be handled... "correctly". At least in the sense that the code produced by LLVM should be no more incorrect than it was before, for this target.

https://github.com/llvm/llvm-project/pull/111269