1 files changed, 26 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm/src/math/generic/fmaximum_num.rs b/library/compiler-builtins/libm/src/math/generic/fmaximum_num.rs
new file mode 100644
index 00000000000..05df6cbd464
--- /dev/null
+++ b/library/compiler-builtins/libm/src/math/generic/fmaximum_num.rs
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: MIT OR Apache-2.0 */
+//! IEEE 754-2019 `maximumNumber`.
+//!
+//! Per the spec, returns:
+//! - `x` if `x > y`
+//! - `y` if `y > x`
+//! - Non-NaN if one operand is NaN
+//! - Logic following +0.0 > -0.0
+//! - Either `x` or `y` if `x == y` and the signs are the same
+//! - qNaN if either operand is a NaN
+//!
+//! Excluded from our implementation is sNaN handling.
+
+use crate::support::Float;
+
+#[inline]
+pub fn fmaximum_num<F: Float>(x: F, y: F) -> F {
+    let res = if x.is_nan() || x < y || (x.biteq(F::NEG_ZERO) && y.is_sign_positive()) {
+        y
+    } else {
+        x
+    };
+
+    // Canonicalize
+    res * F::ONE
+}