diff options
Diffstat (limited to 'vendor/compiler_builtins/libm/src/math/fabs.rs')
-rw-r--r-- | vendor/compiler_builtins/libm/src/math/fabs.rs | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/libm/src/math/fabs.rs b/vendor/compiler_builtins/libm/src/math/fabs.rs new file mode 100644 index 000000000..b2255ad32 --- /dev/null +++ b/vendor/compiler_builtins/libm/src/math/fabs.rs @@ -0,0 +1,41 @@ +use core::u64; + +/// Absolute value (magnitude) (f64) +/// Calculates the absolute value (magnitude) of the argument `x`, +/// by direct manipulation of the bit representation of `x`. +#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] +pub fn fabs(x: f64) -> f64 { + // On wasm32 we know that LLVM's intrinsic will compile to an optimized + // `f64.abs` native instruction, so we can leverage this for both code size + // and speed. + llvm_intrinsically_optimized! { + #[cfg(target_arch = "wasm32")] { + return unsafe { ::core::intrinsics::fabsf64(x) } + } + } + f64::from_bits(x.to_bits() & (u64::MAX / 2)) +} + +#[cfg(test)] +mod tests { + use super::*; + use core::f64::*; + + #[test] + fn sanity_check() { + assert_eq!(fabs(-1.0), 1.0); + assert_eq!(fabs(2.8), 2.8); + } + + /// The spec: https://en.cppreference.com/w/cpp/numeric/math/fabs + #[test] + fn spec_tests() { + assert!(fabs(NAN).is_nan()); + for f in [0.0, -0.0].iter().copied() { + assert_eq!(fabs(f), 0.0); + } + for f in [INFINITY, NEG_INFINITY].iter().copied() { + assert_eq!(fabs(f), INFINITY); + } + } +} |