1 files changed, 94 insertions, 0 deletions
diff --git a/src/math/all_test.go b/src/math/all_test.go
index 886267bc17..e29610a1ed 100644
--- a/src/math/all_test.go
+++ b/src/math/all_test.go
@@ -2094,6 +2094,67 @@ var sqrt32 = []float32{
 	-5.0106036182710749e+00,
 }
 
+type compareTest[F float32 | float64] struct {
+	x, y F
+	want int
+}
+
+func compareCasesFloat64() []compareTest[float64] {
+	zero, nan, inf := 0.0, NaN(), Inf(0)
+
+	// construct -NaN manually from its bit representation,
+	// since IEEE doesn't mandate negate(NaN) change the sign bit
+	unegnan := Float64bits(nan)
+	unegnan ^= 1 << 63
+	negnan := Float64frombits(unegnan)
+	return []compareTest[float64]{
+		{negnan, -inf, -1},
+		{-inf, negnan, 1},
+		{-inf, -Pi, -1},
+		{-Pi, -inf, 1},
+		{-Pi, -zero, -1},
+		{-zero, -Pi, 1},
+		{-zero, 0, -1},
+		{0, -zero, 1},
+		{0, Pi, -1},
+		{Pi, 0, 1},
+		{Pi, inf, -1},
+		{inf, Pi, 1},
+		{inf, nan, -1},
+		{nan, inf, 1},
+		{Pi, Pi, 0},
+		{negnan, negnan, 0},
+	}
+}
+
+func compareCasesFloat32() []compareTest[float32] {
+	zero, nan, inf := float32(0.0), float32(NaN()), float32(Inf(0))
+
+	// construct -NaN manually from its bit representation,
+	// since IEEE doesn't mandate negate(NaN) change the sign bit
+	unegnan := Float32bits(nan)
+	unegnan ^= 1 << 31
+	negnan := Float32frombits(unegnan)
+	return []compareTest[float32]{
+		{negnan, -inf, -1},
+		{-inf, negnan, 1},
+		{-inf, -Pi, -1},
+		{-Pi, -inf, 1},
+		{-Pi, -zero, -1},
+		{-zero, -Pi, 1},
+		{-zero, 0, -1},
+		{0, -zero, 1},
+		{0, Pi, -1},
+		{Pi, 0, 1},
+		{Pi, inf, -1},
+		{inf, Pi, 1},
+		{inf, nan, -1},
+		{nan, inf, 1},
+		{Pi, Pi, 0},
+		{negnan, negnan, 0},
+	}
+}
+
 func tolerance(a, b, e float64) bool {
 	// Multiplying by e here can underflow denormal values to zero.
 	// Check a==b so that at least if a and b are small and identical
@@ -2261,6 +2322,22 @@ func TestCeil(t *testing.T) {
 	}
 }
 
+func TestCompare(t *testing.T) {
+	// -NaN < -∞ < -3.14 < -0 < 0 < 3.14 < ∞ < NaN
+	for _, c := range compareCasesFloat64() {
+		cmp := Compare(c.x, c.y)
+		if cmp != c.want {
+			t.Errorf("Compare(%v, %v) = %d, want %v", c.x, c.y, cmp, c.want)
+		}
+	}
+	for _, c := range compareCasesFloat32() {
+		cmp := Compare32(c.x, c.y)
+		if cmp != c.want {
+			t.Errorf("Compare32(%v, %v) = %d, want %v", c.x, c.y, cmp, c.want)
+		}
+	}
+}
+
 func TestCopysign(t *testing.T) {
 	for i := 0; i < len(vf); i++ {
 		if f := Copysign(vf[i], -1); copysign[i] != f {
@@ -3320,6 +3397,23 @@ func BenchmarkCeil(b *testing.B) {
 	GlobalF = x
 }
 
+func BenchmarkCompare(b *testing.B) {
+	x := 0
+	for i := 0; i < b.N; i++ {
+		x = Compare(GlobalF, 1.5)
+	}
+	GlobalI = x
+}
+
+func BenchmarkCompare32(b *testing.B) {
+	x := 0
+	globalF32 := float32(GlobalF)
+	for i := 0; i < b.N; i++ {
+		x = Compare32(globalF32, 1.5)
+	}
+	GlobalI = x
+}
+
 var copysignNeg = -1.0
 
 func BenchmarkCopysign(b *testing.B) {