diff options
| -rw-r--r-- | library/core/src/primitive_docs.rs | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/library/core/src/primitive_docs.rs b/library/core/src/primitive_docs.rs index b1bc3ba1112..7fa119b5006 100644 --- a/library/core/src/primitive_docs.rs +++ b/library/core/src/primitive_docs.rs @@ -1082,8 +1082,12 @@ impl<T> (T,) {} /// bits. Please see [the documentation for [`prim@f32`] or [Wikipedia on /// half-precision values][wikipedia] for more information. /// -/// Note that most major platforms will provide `f16` math support by converting to and from -/// an `f32`, which is usually fairly performant but will not be as fast as using `f32` directly. +/// Note that most common platforms will not support `f16` in hardware without enabling extra target +/// features, with the notable exception of Apple Silicon (also known as M1, M2, etc.) processors. +/// Hardware support on x86-64 requires the avx512fp16 feature, while RISC-V requires Zhf. +/// Usually the fallback implementation will be to use `f32` hardware if it exists, and convert +/// between `f16` and `f32` when performing math. +/// /// *[See also the `std::f16::consts` module](crate::f16::consts).* /// /// [wikipedia]: https://en.wikipedia.org/wiki/Half-precision_floating-point_format @@ -1183,12 +1187,15 @@ mod prim_f64 {} /// as many bits as `f64`. Please see [the documentation for [`prim@f32`] or [Wikipedia on /// quad-precision values][wikipedia] for more information. /// -/// Note that most major platforms do not have hardware support for `f128`, in which case a -/// software implementation will be used. This can be significantly slower than using `f64`. +/// Note that no platforms have hardware support for `f128` without enabling target specific features +/// (and [only some consumer level hardware has support][wikipedia-support], for example RISC-V has support, but +/// neither amd64 nor aarch64 has support), in which case a software implementation will be used. This can be +/// significantly slower than using `f64`. /// /// *[See also the `std::f128::consts` module](crate::f128::consts).* /// /// [wikipedia]: https://en.wikipedia.org/wiki/Quadruple-precision_floating-point_format +/// [wikipedia-support]: https://en.wikipedia.org/wiki/Quadruple-precision_floating-point_format#Hardware_support #[unstable(feature = "f128", issue = "116909")] mod prim_f128 {} |