Add powi to f16 and f128

This will unblock adding support to compiler_builtins
(<rust-lang/compiler-builtins#614>), which will
then unblock adding tests for these new functions.

library/core/src/intrinsics.rs

@@ -1594,6 +1594,12 @@ extern "rust-intrinsic" {
  #[rustc_nounwind]
  pub fn sqrtf64(x: f64) -> f64;
 
+ /// Raises an `f16` to an integer power.
+ ///
+ /// The stabilized version of this intrinsic is
+ /// [`f16::powi`](../../std/primitive.f16.html#method.powi)
+ #[rustc_nounwind]
+ pub fn powif16(a: f16, x: i32) -> f16;
  /// Raises an `f32` to an integer power.
  ///
  /// The stabilized version of this intrinsic is
@@ -1606,6 +1612,12 @@ extern "rust-intrinsic" {
  /// [`f64::powi`](../../std/primitive.f64.html#method.powi)
  #[rustc_nounwind]
  pub fn powif64(a: f64, x: i32) -> f64;
+ /// Raises an `f128` to an integer power.
+ ///
+ /// The stabilized version of this intrinsic is
+ /// [`f128::powi`](../../std/primitive.f128.html#method.powi)
+ #[rustc_nounwind]
+ pub fn powif128(a: f128, x: i32) -> f128;
 
  /// Returns the sine of an `f32`.
  ///

library/std/src/f128.rs

@@ -7,5 +7,29 @@
 #[cfg(test)]
 mod tests;
 
+#[cfg(not(test))]
+use crate::intrinsics;
+
 #[unstable(feature = "f128", issue = "116909")]
 pub use core::f128::consts;
+
+#[cfg(not(test))]
+impl f128 {
+ /// Raises a number to an integer power.
+ ///
+ /// Using this function is generally faster than using `powf`.
+ /// It might have a different sequence of rounding operations than `powf`,
+ /// so the results are not guaranteed to agree.
+ ///
+ /// # Unspecified precision
+ ///
+ /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
+ /// can even differ within the same execution from one invocation to the next.
+ #[inline]
+ #[rustc_allow_incoherent_impl]
+ #[unstable(feature = "f128", issue = "116909")]
+ #[must_use = "method returns a new number and does not mutate the original value"]
+ pub fn powi(self, n: i32) -> f128 {
+ unsafe { intrinsics::powif128(self, n) }
+ }
+}

library/std/src/f16.rs

@@ -7,5 +7,29 @@
 #[cfg(test)]
 mod tests;
 
+#[cfg(not(test))]
+use crate::intrinsics;
+
 #[unstable(feature = "f16", issue = "116909")]
 pub use core::f16::consts;
+
+#[cfg(not(test))]
+impl f16 {
+ /// Raises a number to an integer power.
+ ///
+ /// Using this function is generally faster than using `powf`.
+ /// It might have a different sequence of rounding operations than `powf`,
+ /// so the results are not guaranteed to agree.
+ ///
+ /// # Unspecified precision
+ ///
+ /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
+ /// can even differ within the same execution from one invocation to the next.
+ #[inline]
+ #[rustc_allow_incoherent_impl]
+ #[unstable(feature = "f16", issue = "116909")]
+ #[must_use = "method returns a new number and does not mutate the original value"]
+ pub fn powi(self, n: i32) -> f16 {
+ unsafe { intrinsics::powif16(self, n) }
+ }
+}