[llvm] RuntimeLibcalls: Stop opting out of exp10 (PR #148604)

[Trevor Gross via llvm-commits]

tgross35 wrote:

> In theory the backend needs to do something to provide the intrinsic behavior. This is currently built on top of emitting libm calls to shoddy host math libraries. In a better world we would have complete coverage of all functions x types in compiler-rt and ignore the host libraries, or rip out most math intrinsics and disallow types we don't have a direct compiler implementation of

It would be nice if there was a triple flag to indicate presence of a backend-agnostic C23-compliant library, so e.g. `sqrtf16`, `sqrtf32`, `sqrtf64`, `sqrtf64x` (for x87 f80), and `sqrtf128` can be lowered to and `long double` never needs to be considered. Glibc has already had these for a while. `ppc_fp128` would still be a bit weird since I don't believe it can classify as `_Float64x`.

I know we talked about something like this on Discord a while back.

https://github.com/llvm/llvm-project/pull/148604