[libc] [llvm] [libc][math][c23] Add {,u}fromfp{,x}{,f,l,f128} functions (PR #86003)

[via llvm-commits]

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@@ -140,8 +140,9 @@ LIBC_INLINE T round(T x) {
   }
 }
 
-template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
-LIBC_INLINE T round_using_current_rounding_mode(T x) {
+template <typename T>
+LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_floating_point_v<T>, T>
+round_using_specific_rounding_mode(T x, int rnd) {
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overmighty wrote:

Maybe this function should have been made `static` or put in a namespace.

https://github.com/llvm/llvm-project/pull/86003