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

[Matt Arsenault via llvm-commits]

arsenm wrote:

> I'm still not really convinced that your general approach here is an improvement over the status quo. exp10 is going to be available on any platform using glibc/musl, regardless of architecture. Excluding it from the default set for the sake of darwin platforms, and then having to add it back **for every single architecture** does not seem like a good tradeoff to me. Wouldn't it be better to remove it instead for the two arches where darwin is actually relevant?
> 
> Alternatively, it seems to me like you need a mechanism that allows you to exclude exp10 on darwin in a way that does not require listing this for each arch.

I very deliberately do not want any opt-out mechanism. All target based decisions should be explicitly opt-in, and all the places that are opt-out were a mistake. It results in falsely reporting things that don't exist as available, like this. And hard to untangle messes. This is a staging step to getting all logic into tablegen to work towards that


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