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);
+        }
+    }
+}