fmaximum,fminimum: Fix incorrect result and add tests

After adding tests, the current implementation for fminimum fails when
provided a negative zero and NaN as inputs:

    ---- math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f64 stdout ----

    thread 'math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f64' panicked at libm/src/math/fminimum_fmaximum_num.rs:240:13:
    fmaximum_num(-0x0p+0, NaN)
    l: NaN (0x7ff8000000000000)
    r: -0.0 (0x8000000000000000)

    ---- math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f32 stdout ----

    thread 'math::fminimum_fmaximum_num::tests::fmaximum_num_spec_tests_f32' panicked at libm/src/math/fminimum_fmaximum_num.rs:240:13:
    fmaximum_num(-0x0p+0, NaN)
    l: NaN (0x7fc00000)
    r: -0.0 (0x80000000)

Add more thorough spec tests for these functions and correct the
implementations.

Canonicalization is also moved to a trait method to centralize
documentation about what it does and doesn't do.

1 files changed, 122 insertions, 16 deletions

diff --git a/library/compiler-builtins/libm/src/math/fminimum_fmaximum_num.rs b/library/compiler-builtins/libm/src/math/fminimum_fmaximum_num.rs
index 180d21f72b7..fadf934180a 100644
--- a/library/compiler-builtins/libm/src/math/fminimum_fmaximum_num.rs
+++ b/library/compiler-builtins/libm/src/math/fminimum_fmaximum_num.rs
@@ -74,24 +74,77 @@ mod tests {
     fn fminimum_num_spec_test<F: Float>(f: impl Fn(F, F) -> F) {
         let cases = [
             (F::ZERO, F::ZERO, F::ZERO),
-            (F::ONE, F::ONE, F::ONE),
+            (F::ZERO, F::NEG_ZERO, F::NEG_ZERO),
             (F::ZERO, F::ONE, F::ZERO),
-            (F::ONE, F::ZERO, F::ZERO),
             (F::ZERO, F::NEG_ONE, F::NEG_ONE),
+            (F::ZERO, F::INFINITY, F::ZERO),
+            (F::ZERO, F::NEG_INFINITY, F::NEG_INFINITY),
+            (F::ZERO, F::NAN, F::ZERO),
+            (F::ZERO, F::NEG_NAN, F::ZERO),
+            (F::NEG_ZERO, F::ZERO, F::NEG_ZERO),
+            (F::NEG_ZERO, F::NEG_ZERO, F::NEG_ZERO),
+            (F::NEG_ZERO, F::ONE, F::NEG_ZERO),
+            (F::NEG_ZERO, F::NEG_ONE, F::NEG_ONE),
+            (F::NEG_ZERO, F::INFINITY, F::NEG_ZERO),
+            (F::NEG_ZERO, F::NEG_INFINITY, F::NEG_INFINITY),
+            (F::NEG_ZERO, F::NAN, F::NEG_ZERO),
+            (F::NEG_ZERO, F::NEG_NAN, F::NEG_ZERO),
+            (F::ONE, F::ZERO, F::ZERO),
+            (F::ONE, F::NEG_ZERO, F::NEG_ZERO),
+            (F::ONE, F::ONE, F::ONE),
+            (F::ONE, F::NEG_ONE, F::NEG_ONE),
+            (F::ONE, F::INFINITY, F::ONE),
+            (F::ONE, F::NEG_INFINITY, F::NEG_INFINITY),
+            (F::ONE, F::NAN, F::ONE),
+            (F::ONE, F::NEG_NAN, F::ONE),
             (F::NEG_ONE, F::ZERO, F::NEG_ONE),
+            (F::NEG_ONE, F::NEG_ZERO, F::NEG_ONE),
+            (F::NEG_ONE, F::ONE, F::NEG_ONE),
+            (F::NEG_ONE, F::NEG_ONE, F::NEG_ONE),
+            (F::NEG_ONE, F::INFINITY, F::NEG_ONE),
+            (F::NEG_ONE, F::NEG_INFINITY, F::NEG_INFINITY),
+            (F::NEG_ONE, F::NAN, F::NEG_ONE),
+            (F::NEG_ONE, F::NEG_NAN, F::NEG_ONE),
             (F::INFINITY, F::ZERO, F::ZERO),
+            (F::INFINITY, F::NEG_ZERO, F::NEG_ZERO),
+            (F::INFINITY, F::ONE, F::ONE),
+            (F::INFINITY, F::NEG_ONE, F::NEG_ONE),
+            (F::INFINITY, F::INFINITY, F::INFINITY),
+            (F::INFINITY, F::NEG_INFINITY, F::NEG_INFINITY),
+            (F::INFINITY, F::NAN, F::INFINITY),
+            (F::INFINITY, F::NEG_NAN, F::INFINITY),
             (F::NEG_INFINITY, F::ZERO, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::NEG_ZERO, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::ONE, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::NEG_ONE, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::INFINITY, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::NEG_INFINITY, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::NAN, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::NEG_NAN, F::NEG_INFINITY),
             (F::NAN, F::ZERO, F::ZERO),
-            (F::ZERO, F::NAN, F::ZERO),
+            (F::NAN, F::NEG_ZERO, F::NEG_ZERO),
+            (F::NAN, F::ONE, F::ONE),
+            (F::NAN, F::NEG_ONE, F::NEG_ONE),
+            (F::NAN, F::INFINITY, F::INFINITY),
+            (F::NAN, F::NEG_INFINITY, F::NEG_INFINITY),
             (F::NAN, F::NAN, F::NAN),
-            (F::ZERO, F::NEG_ZERO, F::NEG_ZERO),
-            (F::NEG_ZERO, F::ZERO, F::NEG_ZERO),
+            (F::NEG_NAN, F::ZERO, F::ZERO),
+            (F::NEG_NAN, F::NEG_ZERO, F::NEG_ZERO),
+            (F::NEG_NAN, F::ONE, F::ONE),
+            (F::NEG_NAN, F::NEG_ONE, F::NEG_ONE),
+            (F::NEG_NAN, F::INFINITY, F::INFINITY),
+            (F::NEG_NAN, F::NEG_INFINITY, F::NEG_INFINITY),
         ];
 
-        for (x, y, res) in cases {
-            let val = f(x, y);
-            assert_biteq!(val, res, "fminimum_num({}, {})", Hexf(x), Hexf(y));
+        for (x, y, expected) in cases {
+            let actual = f(x, y);
+            assert_biteq!(actual, expected, "fminimum_num({}, {})", Hexf(x), Hexf(y));
         }
+
+        // Ordering between NaNs does not matter
+        assert!(f(F::NAN, F::NEG_NAN).is_nan());
+        assert!(f(F::NEG_NAN, F::NAN).is_nan());
+        assert!(f(F::NEG_NAN, F::NEG_NAN).is_nan());
     }
 
     #[test]
@@ -119,24 +172,77 @@ mod tests {
     fn fmaximum_num_spec_test<F: Float>(f: impl Fn(F, F) -> F) {
         let cases = [
             (F::ZERO, F::ZERO, F::ZERO),
-            (F::ONE, F::ONE, F::ONE),
+            (F::ZERO, F::NEG_ZERO, F::ZERO),
             (F::ZERO, F::ONE, F::ONE),
-            (F::ONE, F::ZERO, F::ONE),
             (F::ZERO, F::NEG_ONE, F::ZERO),
+            (F::ZERO, F::INFINITY, F::INFINITY),
+            (F::ZERO, F::NEG_INFINITY, F::ZERO),
+            (F::ZERO, F::NAN, F::ZERO),
+            (F::ZERO, F::NEG_NAN, F::ZERO),
+            (F::NEG_ZERO, F::ZERO, F::ZERO),
+            (F::NEG_ZERO, F::NEG_ZERO, F::NEG_ZERO),
+            (F::NEG_ZERO, F::ONE, F::ONE),
+            (F::NEG_ZERO, F::NEG_ONE, F::NEG_ZERO),
+            (F::NEG_ZERO, F::INFINITY, F::INFINITY),
+            (F::NEG_ZERO, F::NEG_INFINITY, F::NEG_ZERO),
+            (F::NEG_ZERO, F::NAN, F::NEG_ZERO),
+            (F::NEG_ZERO, F::NEG_NAN, F::NEG_ZERO),
+            (F::ONE, F::ZERO, F::ONE),
+            (F::ONE, F::NEG_ZERO, F::ONE),
+            (F::ONE, F::ONE, F::ONE),
+            (F::ONE, F::NEG_ONE, F::ONE),
+            (F::ONE, F::INFINITY, F::INFINITY),
+            (F::ONE, F::NEG_INFINITY, F::ONE),
+            (F::ONE, F::NAN, F::ONE),
+            (F::ONE, F::NEG_NAN, F::ONE),
             (F::NEG_ONE, F::ZERO, F::ZERO),
+            (F::NEG_ONE, F::NEG_ZERO, F::NEG_ZERO),
+            (F::NEG_ONE, F::ONE, F::ONE),
+            (F::NEG_ONE, F::NEG_ONE, F::NEG_ONE),
+            (F::NEG_ONE, F::INFINITY, F::INFINITY),
+            (F::NEG_ONE, F::NEG_INFINITY, F::NEG_ONE),
+            (F::NEG_ONE, F::NAN, F::NEG_ONE),
+            (F::NEG_ONE, F::NEG_NAN, F::NEG_ONE),
             (F::INFINITY, F::ZERO, F::INFINITY),
+            (F::INFINITY, F::NEG_ZERO, F::INFINITY),
+            (F::INFINITY, F::ONE, F::INFINITY),
+            (F::INFINITY, F::NEG_ONE, F::INFINITY),
+            (F::INFINITY, F::INFINITY, F::INFINITY),
+            (F::INFINITY, F::NEG_INFINITY, F::INFINITY),
+            (F::INFINITY, F::NAN, F::INFINITY),
+            (F::INFINITY, F::NEG_NAN, F::INFINITY),
             (F::NEG_INFINITY, F::ZERO, F::ZERO),
+            (F::NEG_INFINITY, F::NEG_ZERO, F::NEG_ZERO),
+            (F::NEG_INFINITY, F::ONE, F::ONE),
+            (F::NEG_INFINITY, F::NEG_ONE, F::NEG_ONE),
+            (F::NEG_INFINITY, F::INFINITY, F::INFINITY),
+            (F::NEG_INFINITY, F::NEG_INFINITY, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::NAN, F::NEG_INFINITY),
+            (F::NEG_INFINITY, F::NEG_NAN, F::NEG_INFINITY),
             (F::NAN, F::ZERO, F::ZERO),
-            (F::ZERO, F::NAN, F::ZERO),
+            (F::NAN, F::NEG_ZERO, F::NEG_ZERO),
+            (F::NAN, F::ONE, F::ONE),
+            (F::NAN, F::NEG_ONE, F::NEG_ONE),
+            (F::NAN, F::INFINITY, F::INFINITY),
+            (F::NAN, F::NEG_INFINITY, F::NEG_INFINITY),
             (F::NAN, F::NAN, F::NAN),
-            (F::ZERO, F::NEG_ZERO, F::ZERO),
-            (F::NEG_ZERO, F::ZERO, F::ZERO),
+            (F::NEG_NAN, F::ZERO, F::ZERO),
+            (F::NEG_NAN, F::NEG_ZERO, F::NEG_ZERO),
+            (F::NEG_NAN, F::ONE, F::ONE),
+            (F::NEG_NAN, F::NEG_ONE, F::NEG_ONE),
+            (F::NEG_NAN, F::INFINITY, F::INFINITY),
+            (F::NEG_NAN, F::NEG_INFINITY, F::NEG_INFINITY),
         ];
 
-        for (x, y, res) in cases {
-            let val = f(x, y);
-            assert_biteq!(val, res, "fmaximum_num({}, {})", Hexf(x), Hexf(y));
+        for (x, y, expected) in cases {
+            let actual = f(x, y);
+            assert_biteq!(actual, expected, "fmaximum_num({}, {})", Hexf(x), Hexf(y));
         }
+
+        // Ordering between NaNs does not matter
+        assert!(f(F::NAN, F::NEG_NAN).is_nan());
+        assert!(f(F::NEG_NAN, F::NAN).is_nan());
+        assert!(f(F::NEG_NAN, F::NEG_NAN).is_nan());
     }
 
     #[test]