fix powi

library/compiler-builtins/src/float/mod.rs

@@ -15,6 +15,7 @@ pub mod sub;
 #[doc(hidden)]
 pub trait Float:
     Copy
+    + core::fmt::Debug
     + PartialEq
     + PartialOrd
     + ops::AddAssign

library/compiler-builtins/src/float/pow.rs

@@ -1,39 +1,36 @@
 use float::Float;
+use int::Int;
 
-trait Pow: Float {
-    /// Returns `a` raised to the power `b`
-    fn pow(self, mut b: i32) -> Self {
-        let mut a = self;
-        let recip = b < 0;
-        let mut r = Self::ONE;
-        loop {
-            if (b & 1) != 0 {
-                r *= a;
-            }
-            b = ((b as u32) >> 1) as i32;
-            if b == 0 {
-                break;
-            }
-            a *= a;
+/// Returns `a` raised to the power `b`
+fn pow<F: Float>(a: F, b: i32) -> F {
+    let mut a = a;
+    let recip = b < 0;
+    let mut pow = i32::abs_diff(b, 0);
+    let mut mul = F::ONE;
+    loop {
+        if (pow & 1) != 0 {
+            mul *= a;
         }
+        pow >>= 1;
+        if pow == 0 {
+            break;
+        }
+        a *= a;
+    }
 
-        if recip {
-            Self::ONE / r
-        } else {
-            r
-        }
+    if recip {
+        F::ONE / mul
+    } else {
+        mul
     }
 }
 
-impl Pow for f32 {}
-impl Pow for f64 {}
-
 intrinsics! {
     pub extern "C" fn __powisf2(a: f32, b: i32) -> f32 {
-        a.pow(b)
+        pow(a, b)
     }
 
     pub extern "C" fn __powidf2(a: f64, b: i32) -> f64 {
-        a.pow(b)
+        pow(a, b)
     }
 }