Auto merge of rust-lang#125188 - tgross35:f16-f128-powi, r=Nilstrieb

Add `powi` fo `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.

Author: bors

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/core/src/num/f128.rs

@@ -228,6 +228,16 @@ impl f128 {
     /// the bit pattern of NaNs are conserved over arithmetic operations, the result of
     /// `is_sign_positive` on a NaN might produce an unexpected result in some cases.
     /// See [explanation of NaN as a special value](f32) for more info.
+    ///
+    /// ```
+    /// #![feature(f128)]
+    ///
+    /// let f = 7.0_f128;
+    /// let g = -7.0_f128;
+    ///
+    /// assert!(f.is_sign_positive());
+    /// assert!(!g.is_sign_positive());
+    /// ```
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
@@ -241,6 +251,16 @@ impl f128 {
     /// the bit pattern of NaNs are conserved over arithmetic operations, the result of
     /// `is_sign_negative` on a NaN might produce an unexpected result in some cases.
     /// See [explanation of NaN as a special value](f32) for more info.
+    ///
+    /// ```
+    /// #![feature(f128)]
+    ///
+    /// let f = 7.0_f128;
+    /// let g = -7.0_f128;
+    ///
+    /// assert!(!f.is_sign_negative());
+    /// assert!(g.is_sign_negative());
+    /// ```
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]

library/core/src/num/f16.rs

@@ -224,6 +224,16 @@ impl f16 {
     /// the bit pattern of NaNs are conserved over arithmetic operations, the result of
     /// `is_sign_positive` on a NaN might produce an unexpected result in some cases.
     /// See [explanation of NaN as a special value](f32) for more info.
+    ///
+    /// ```
+    /// #![feature(f16)]
+    ///
+    /// let f = 7.0_f16;
+    /// let g = -7.0_f16;
+    ///
+    /// assert!(f.is_sign_positive());
+    /// assert!(!g.is_sign_positive());
+    /// ```
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
@@ -237,6 +247,16 @@ impl f16 {
     /// the bit pattern of NaNs are conserved over arithmetic operations, the result of
     /// `is_sign_negative` on a NaN might produce an unexpected result in some cases.
     /// See [explanation of NaN as a special value](f32) for more info.
+    ///
+    /// ```
+    /// #![feature(f16)]
+    ///
+    /// let f = 7.0_f16;
+    /// let g = -7.0_f16;
+    ///
+    /// assert!(!f.is_sign_negative());
+    /// assert!(g.is_sign_negative());
+    /// ```
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]

library/core/src/num/f64.rs

@@ -1111,7 +1111,6 @@ impl f64 {
     /// ```
     /// assert!((1f64).to_bits() != 1f64 as u64); // to_bits() is not casting!
     /// assert_eq!((12.5f64).to_bits(), 0x4029000000000000);
-    ///
     /// ```
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]

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) }
+    }
+}