[lld] [llvm] [CodeGen] Use __extendhfsf2 and __truncsfhf2 by default (PR #126880)

[Nikita Popov via llvm-commits]

nikic wrote:

Adjusted the lld test to use a different builtin, because the issue it is testing is fixed for half float builtins now.

https://github.com/llvm/llvm-project/pull/126880