[clang] Clang: Drop float support from __builtin_elementwise_max (PR #180885)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> > That's how I lean but I don't have a good idea for what the warning conditions would be. I don't think "warn on any float" is viable -- outside of a handful of edge cases, the function does what it says on the tin, right? And the edge cases aren't something we can catch statically in most cases, I believe.
> 
> Deprecation warning

That seems like a reasonable approach to me; GCC doesn't implement this builtin nor does MSVC, so I don't think we need it for compatibility with other implementations. 

https://github.com/llvm/llvm-project/pull/180885