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.
 ///
@@ -4026,7 +4037,18 @@ 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.
 ///
@@ -4091,7 +4113,17 @@ 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.
 ///
@@ -4126,7 +4158,17 @@ 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`.
 ///