1 files changed, 116 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm/src/math/fabs.rs b/library/compiler-builtins/libm/src/math/fabs.rs
new file mode 100644
index 00000000000..0050a309fee
--- /dev/null
+++ b/library/compiler-builtins/libm/src/math/fabs.rs
@@ -0,0 +1,116 @@
+/// Absolute value (magnitude) (f16)
+///
+/// Calculates the absolute value (magnitude) of the argument `x`,
+/// by direct manipulation of the bit representation of `x`.
+#[cfg(f16_enabled)]
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn fabsf16(x: f16) -> f16 {
+    super::generic::fabs(x)
+}
+
+/// Absolute value (magnitude) (f32)
+///
+/// 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 fabsf(x: f32) -> f32 {
+    select_implementation! {
+        name: fabsf,
+        use_arch: all(target_arch = "wasm32", intrinsics_enabled),
+        args: x,
+    }
+
+    super::generic::fabs(x)
+}
+
+/// 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 {
+    select_implementation! {
+        name: fabs,
+        use_arch: all(target_arch = "wasm32", intrinsics_enabled),
+        args: x,
+    }
+
+    super::generic::fabs(x)
+}
+
+/// Absolute value (magnitude) (f128)
+///
+/// Calculates the absolute value (magnitude) of the argument `x`,
+/// by direct manipulation of the bit representation of `x`.
+#[cfg(f128_enabled)]
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn fabsf128(x: f128) -> f128 {
+    super::generic::fabs(x)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::support::Float;
+
+    /// Based on https://en.cppreference.com/w/cpp/numeric/math/fabs
+    fn spec_test<F: Float>(f: impl Fn(F) -> F) {
+        assert_biteq!(f(F::ZERO), F::ZERO);
+        assert_biteq!(f(F::NEG_ZERO), F::ZERO);
+        assert_biteq!(f(F::INFINITY), F::INFINITY);
+        assert_biteq!(f(F::NEG_INFINITY), F::INFINITY);
+        assert!(f(F::NAN).is_nan());
+
+        // Not spec rewquired but we expect it
+        assert!(f(F::NAN).is_sign_positive());
+        assert!(f(F::from_bits(F::NAN.to_bits() | F::SIGN_MASK)).is_sign_positive());
+    }
+
+    #[test]
+    #[cfg(f16_enabled)]
+    fn sanity_check_f16() {
+        assert_eq!(fabsf16(-1.0f16), 1.0);
+        assert_eq!(fabsf16(2.8f16), 2.8);
+    }
+
+    #[test]
+    #[cfg(f16_enabled)]
+    fn spec_tests_f16() {
+        spec_test::<f16>(fabsf16);
+    }
+
+    #[test]
+    fn sanity_check_f32() {
+        assert_eq!(fabsf(-1.0f32), 1.0);
+        assert_eq!(fabsf(2.8f32), 2.8);
+    }
+
+    #[test]
+    fn spec_tests_f32() {
+        spec_test::<f32>(fabsf);
+    }
+
+    #[test]
+    fn sanity_check_f64() {
+        assert_eq!(fabs(-1.0f64), 1.0);
+        assert_eq!(fabs(2.8f64), 2.8);
+    }
+
+    #[test]
+    fn spec_tests_f64() {
+        spec_test::<f64>(fabs);
+    }
+
+    #[test]
+    #[cfg(f128_enabled)]
+    fn sanity_check_f128() {
+        assert_eq!(fabsf128(-1.0f128), 1.0);
+        assert_eq!(fabsf128(2.8f128), 2.8);
+    }
+
+    #[test]
+    #[cfg(f128_enabled)]
+    fn spec_tests_f128() {
+        spec_test::<f128>(fabsf128);
+    }
+}