Add intrinsic fallback for {minimum,maximum}{16,128}

Author: Urgau

library/core/src/intrinsics/mod.rs

@@ -3991,7 +3991,18 @@ pub const fn minnumf128(x: f128, y: f128) -> f128;
 #[rustc_nounwind]
 #[rustc_intrinsic]
 #[cfg(not(bootstrap))]
-pub const fn minimumf16(x: f16, y: f16) -> f16;
+pub const fn minimumf16(x: f16, y: f16) -> f16 {
+    if x < y {
+        x
+    } else if y < x {
+        y
+    } else if x == y {
+        if x.is_sign_negative() && y.is_sign_positive() { x } else { y }
+    } else {
+        // At least one input is NaN. Use `+` to perform NaN propagation and quieting.
+        x + y
+    }
+}
 
 /// Returns the minimum (IEEE 754-2019 minimum) of two `f32` values.
 ///
@@ -4024,7 +4035,18 @@ pub const fn minimumf64(x: f64, y: f64) -> f64;
 #[rustc_nounwind]
 #[rustc_intrinsic]
 #[cfg(not(bootstrap))]
-pub const fn minimumf128(x: f128, y: f128) -> f128;
+pub const fn minimumf128(x: f128, y: f128) -> f128 {
+    if x < y {
+        x
+    } else if y < x {
+        y
+    } else if x == y {
+        if x.is_sign_negative() && y.is_sign_positive() { x } else { y }
+    } else {
+        // At least one input is NaN. Use `+` to perform NaN propagation and quieting.
+        x + y
+    }
+}
 
 /// Returns the maximum (IEEE 754-2008 maxNum) of two `f16` values.
 ///
@@ -4089,7 +4111,17 @@ pub const fn maxnumf128(x: f128, y: f128) -> f128;
 #[rustc_nounwind]
 #[rustc_intrinsic]
 #[cfg(not(bootstrap))]
-pub const fn maximumf16(x: f16, y: f16) -> f16;
+pub const fn maximumf16(x: f16, y: f16) -> f16 {
+    if x > y {
+        x
+    } else if y > x {
+        y
+    } else if x == y {
+        if x.is_sign_positive() && y.is_sign_negative() { x } else { y }
+    } else {
+        x + y
+    }
+}
 
 /// Returns the maximum (IEEE 754-2019 maximum) of two `f32` values.
 ///
@@ -4122,7 +4154,17 @@ pub const fn maximumf64(x: f64, y: f64) -> f64;
 #[rustc_nounwind]
 #[rustc_intrinsic]
 #[cfg(not(bootstrap))]
-pub const fn maximumf128(x: f128, y: f128) -> f128;
+pub const fn maximumf128(x: f128, y: f128) -> f128 {
+    if x > y {
+        x
+    } else if y > x {
+        y
+    } else if x == y {
+        if x.is_sign_positive() && y.is_sign_negative() { x } else { y }
+    } else {
+        x + y
+    }
+}
 
 /// Returns the absolute value of an `f16`.
 ///

library/core/src/num/f128.rs

@@ -755,7 +755,6 @@ impl f128 {
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
-    #[rustc_const_unstable(feature = "f128", issue = "116909")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     pub const fn maximum(self, other: f128) -> f128 {
         #[cfg(not(bootstrap))]
@@ -804,7 +803,6 @@ impl f128 {
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
-    #[rustc_const_unstable(feature = "f128", issue = "116909")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     pub const fn minimum(self, other: f128) -> f128 {
         #[cfg(not(bootstrap))]

library/core/src/num/f16.rs

@@ -744,7 +744,6 @@ impl f16 {
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
-    #[rustc_const_unstable(feature = "f16", issue = "116909")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     pub const fn maximum(self, other: f16) -> f16 {
         #[cfg(not(bootstrap))]
@@ -792,7 +791,6 @@ impl f16 {
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
-    #[rustc_const_unstable(feature = "f16", issue = "116909")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     pub const fn minimum(self, other: f16) -> f16 {
         #[cfg(not(bootstrap))]