1 files changed, 10 insertions, 7 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
index 05df6cbd464..2dc60b2d237 100644
--- a/library/compiler-builtins/libm/src/math/generic/fmaximum_num.rs
+++ b/library/compiler-builtins/libm/src/math/generic/fmaximum_num.rs
@@ -4,10 +4,10 @@
 //! 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
+//! - +0.0 if x and y are zero with opposite signs
 //! - Either `x` or `y` if `x == y` and the signs are the same
-//! - qNaN if either operand is a NaN
+//! - Non-NaN if one operand is NaN
+//! - qNaN if both operands are NaNx
 //!
 //! Excluded from our implementation is sNaN handling.
 
@@ -15,12 +15,15 @@ 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()) {
+    let res = if x > y || y.is_nan() {
+        x
+    } else if y > x || x.is_nan() {
         y
-    } else {
+    } else if x.is_sign_positive() {
         x
+    } else {
+        y
     };
 
-    // Canonicalize
-    res * F::ONE
+    res.canonicalize()
 }