Fix NaN handling of simd float min and max operations

example/float-minmax-pass.rs

@@ -0,0 +1,53 @@
+// Copied from https://github.com/rust-lang/rust/blob/3fe3b89cd57229343eeca753fdd8c63d9b03c65c/src/test/ui/simd/intrinsic/float-minmax-pass.rs
+// run-pass
+// ignore-emscripten
+
+// Test that the simd_f{min,max} intrinsics produce the correct results.
+
+#![feature(repr_simd, platform_intrinsics)]
+#![allow(non_camel_case_types)]
+
+#[repr(simd)]
+#[derive(Copy, Clone, PartialEq, Debug)]
+struct f32x4(pub f32, pub f32, pub f32, pub f32);
+
+extern "platform-intrinsic" {
+    fn simd_fmin<T>(x: T, y: T) -> T;
+    fn simd_fmax<T>(x: T, y: T) -> T;
+}
+
+fn main() {
+    let x = f32x4(1.0, 2.0, 3.0, 4.0);
+    let y = f32x4(2.0, 1.0, 4.0, 3.0);
+
+    #[cfg(not(any(target_arch = "mips", target_arch = "mips64")))]
+    let nan = f32::NAN;
+    // MIPS hardware treats f32::NAN as SNAN. Clear the signaling bit.
+    // See https://github.com/rust-lang/rust/issues/52746.
+    #[cfg(any(target_arch = "mips", target_arch = "mips64"))]
+    let nan = f32::from_bits(f32::NAN.to_bits() - 1);
+
+    let n = f32x4(nan, nan, nan, nan);
+
+    unsafe {
+        let min0 = simd_fmin(x, y);
+        let min1 = simd_fmin(y, x);
+        assert_eq!(min0, min1);
+        let e = f32x4(1.0, 1.0, 3.0, 3.0);
+        assert_eq!(min0, e);
+        let minn = simd_fmin(x, n);
+        assert_eq!(minn, x);
+        let minn = simd_fmin(y, n);
+        assert_eq!(minn, y);
+
+        let max0 = simd_fmax(x, y);
+        let max1 = simd_fmax(y, x);
+        assert_eq!(max0, max1);
+        let e = f32x4(2.0, 2.0, 4.0, 4.0);
+        assert_eq!(max0, e);
+        let maxn = simd_fmax(x, n);
+        assert_eq!(maxn, x);
+        let maxn = simd_fmax(y, n);
+        assert_eq!(maxn, y);
+    }
+}