Implement pow{f32,f64} intrinsics

Author: bjorn3

example/std_example.rs

@@ -36,6 +36,7 @@ fn main() {
     println!("{}", 2.3f32.powi(2));
     println!("{}", 2.3f32.log2());
     assert_eq!(2.3f32.copysign(-1.0), -2.3f32);
+    println!("{}", 2.3f32.powf(2.0));
 
     assert_eq!(0b0000000000000000000000000010000010000000000000000000000000000000_0000000000100000000000000000000000001000000000000100000000000000u128.leading_zeros(), 26);
     assert_eq!(0b0000000000000000000000000010000000000000000000000000000000000000_0000000000000000000000000000000000001000000000000000000010000000u128.trailing_zeros(), 7);

src/intrinsics.rs

@@ -318,6 +318,8 @@ pub fn codegen_intrinsic_call<'tcx>(
         sqrtf64(flt) -> f64 => sqrt,
         powif32(a, x) -> f32 => __powisf2, // compiler-builtins
         powif64(a, x) -> f64 => __powidf2, // compiler-builtins
+        powf32(a, x) -> f32 => powf,
+        powf64(a, x) -> f64 => pow,
         logf32(flt) -> f32 => logf,
         logf64(flt) -> f64 => log,
         log2f32(flt) -> f32 => log2f,