image: add benchmarks for At and Set methods

Added in preparation for looking at some optimizations around bounds
checks.

BenchmarkAt/rgba-8            100000000     18.5 ns/op      4 B/op   1 allocs/op
BenchmarkAt/rgba64-8          100000000     22.9 ns/op      8 B/op   1 allocs/op
BenchmarkAt/nrgba-8           100000000     18.8 ns/op      4 B/op   1 allocs/op
BenchmarkAt/nrgba64-8         100000000     22.1 ns/op      8 B/op   1 allocs/op
BenchmarkAt/alpha-8           100000000     14.6 ns/op      1 B/op   1 allocs/op
BenchmarkAt/alpha16-8         200000000     6.46 ns/op      0 B/op   0 allocs/op
BenchmarkAt/gray-8            100000000     14.3 ns/op      1 B/op   1 allocs/op
BenchmarkAt/gray16-8          200000000     6.45 ns/op      0 B/op   0 allocs/op
BenchmarkAt/paletted-8        300000000     4.28 ns/op      0 B/op   0 allocs/op
BenchmarkSet/rgba-8           50000000      39.2 ns/op      8 B/op   2 allocs/op
BenchmarkSet/rgba64-8         30000000      45.8 ns/op     16 B/op   2 allocs/op
BenchmarkSet/nrgba-8          50000000      39.3 ns/op      8 B/op   2 allocs/op
BenchmarkSet/nrgba64-8        30000000      45.6 ns/op     16 B/op   2 allocs/op
BenchmarkSet/alpha-8          50000000      34.5 ns/op      2 B/op   2 allocs/op
BenchmarkSet/alpha16-8        50000000      34.9 ns/op      4 B/op   2 allocs/op
BenchmarkSet/gray-8           100000000     20.3 ns/op      1 B/op   1 allocs/op
BenchmarkSet/gray16-8         50000000      36.2 ns/op      4 B/op   2 allocs/op
BenchmarkSet/paletted-8       50000000      39.5 ns/op      1 B/op   1 allocs/op
BenchmarkRGBAAt-8             500000000     3.74 ns/op
BenchmarkRGBASetRGBA-8        300000000     4.33 ns/op
BenchmarkRGBA64At-8           300000000     5.06 ns/op
BenchmarkRGBA64SetRGBA64-8    200000000     6.61 ns/op
BenchmarkNRGBAAt-8            500000000     3.69 ns/op
BenchmarkNRGBASetNRGBA-8      300000000     4.06 ns/op
BenchmarkNRGBA64At-8          300000000     4.98 ns/op
BenchmarkNRGBA64SetNRGBA64-8  200000000     6.62 ns/op
BenchmarkAlphaAt-8            2000000000    1.43 ns/op
BenchmarkAlphaSetAlpha-8      2000000000    1.55 ns/op
BenchmarkAlpha16At-8          1000000000    2.87 ns/op
BenchmarkAlphaSetAlpha16-8    500000000     3.27 ns/op
BenchmarkGrayAt-8             2000000000    1.43 ns/op
BenchmarkGraySetGray-8        2000000000    1.55 ns/op
BenchmarkGray16At-8           1000000000    2.87 ns/op
BenchmarkGraySetGray16-8      500000000     3.14 ns/op

Updates #14884

Change-Id: I349fb214ee75f13ecbc62ac22a40e3b337648f60
Reviewed-on: https://go-review.googlesource.com/136796Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/image/image_test.go

@@ -22,22 +22,27 @@ func cmp(cm color.Model, c0, c1 color.Color) bool {
 	return r0 == r1 && g0 == g1 && b0 == b1 && a0 == a1
 }
 
+var testImages = []struct {
+	name  string
+	image image
+}{
+	{"rgba", NewRGBA(Rect(0, 0, 10, 10))},
+	{"rgba64", NewRGBA64(Rect(0, 0, 10, 10))},
+	{"nrgba", NewNRGBA(Rect(0, 0, 10, 10))},
+	{"nrgba64", NewNRGBA64(Rect(0, 0, 10, 10))},
+	{"alpha", NewAlpha(Rect(0, 0, 10, 10))},
+	{"alpha16", NewAlpha16(Rect(0, 0, 10, 10))},
+	{"gray", NewGray(Rect(0, 0, 10, 10))},
+	{"gray16", NewGray16(Rect(0, 0, 10, 10))},
+	{"paletted", NewPaletted(Rect(0, 0, 10, 10), color.Palette{
+		Transparent,
+		Opaque,
+	})},
+}
+
 func TestImage(t *testing.T) {
-	testImage := []image{
-		NewRGBA(Rect(0, 0, 10, 10)),
-		NewRGBA64(Rect(0, 0, 10, 10)),
-		NewNRGBA(Rect(0, 0, 10, 10)),
-		NewNRGBA64(Rect(0, 0, 10, 10)),
-		NewAlpha(Rect(0, 0, 10, 10)),
-		NewAlpha16(Rect(0, 0, 10, 10)),
-		NewGray(Rect(0, 0, 10, 10)),
-		NewGray16(Rect(0, 0, 10, 10)),
-		NewPaletted(Rect(0, 0, 10, 10), color.Palette{
-			Transparent,
-			Opaque,
-		}),
-	}
-	for _, m := range testImage {
+	for _, tc := range testImages {
+		m := tc.image
 		if !Rect(0, 0, 10, 10).Eq(m.Bounds()) {
 			t.Errorf("%T: want bounds %v, got %v", m, Rect(0, 0, 10, 10), m.Bounds())
 			continue
@@ -111,3 +116,178 @@ func Test16BitsPerColorChannel(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkAt(b *testing.B) {
+	for _, tc := range testImages {
+		b.Run(tc.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				tc.image.At(4, 5)
+			}
+		})
+	}
+}
+
+func BenchmarkSet(b *testing.B) {
+	c := color.Gray{0xff}
+	for _, tc := range testImages {
+		b.Run(tc.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				tc.image.Set(4, 5, c)
+			}
+		})
+	}
+}
+
+func BenchmarkRGBAAt(b *testing.B) {
+	m := NewRGBA(Rect(0, 0, 10, 10))
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.RGBAAt(4, 5)
+	}
+}
+
+func BenchmarkRGBASetRGBA(b *testing.B) {
+	m := NewRGBA(Rect(0, 0, 10, 10))
+	c := color.RGBA{0xff, 0xff, 0xff, 0x13}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.SetRGBA(4, 5, c)
+	}
+}
+
+func BenchmarkRGBA64At(b *testing.B) {
+	m := NewRGBA64(Rect(0, 0, 10, 10))
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.RGBA64At(4, 5)
+	}
+}
+
+func BenchmarkRGBA64SetRGBA64(b *testing.B) {
+	m := NewRGBA64(Rect(0, 0, 10, 10))
+	c := color.RGBA64{0xffff, 0xffff, 0xffff, 0x1357}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.SetRGBA64(4, 5, c)
+	}
+}
+
+func BenchmarkNRGBAAt(b *testing.B) {
+	m := NewNRGBA(Rect(0, 0, 10, 10))
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.NRGBAAt(4, 5)
+	}
+}
+
+func BenchmarkNRGBASetNRGBA(b *testing.B) {
+	m := NewNRGBA(Rect(0, 0, 10, 10))
+	c := color.NRGBA{0xff, 0xff, 0xff, 0x13}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.SetNRGBA(4, 5, c)
+	}
+}
+
+func BenchmarkNRGBA64At(b *testing.B) {
+	m := NewNRGBA64(Rect(0, 0, 10, 10))
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.NRGBA64At(4, 5)
+	}
+}
+
+func BenchmarkNRGBA64SetNRGBA64(b *testing.B) {
+	m := NewNRGBA64(Rect(0, 0, 10, 10))
+	c := color.NRGBA64{0xffff, 0xffff, 0xffff, 0x1357}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.SetNRGBA64(4, 5, c)
+	}
+}
+
+func BenchmarkAlphaAt(b *testing.B) {
+	m := NewAlpha(Rect(0, 0, 10, 10))
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.AlphaAt(4, 5)
+	}
+}
+
+func BenchmarkAlphaSetAlpha(b *testing.B) {
+	m := NewAlpha(Rect(0, 0, 10, 10))
+	c := color.Alpha{0x13}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.SetAlpha(4, 5, c)
+	}
+}
+
+func BenchmarkAlpha16At(b *testing.B) {
+	m := NewAlpha16(Rect(0, 0, 10, 10))
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.Alpha16At(4, 5)
+	}
+}
+
+func BenchmarkAlphaSetAlpha16(b *testing.B) {
+	m := NewAlpha16(Rect(0, 0, 10, 10))
+	c := color.Alpha16{0x13}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.SetAlpha16(4, 5, c)
+	}
+}
+
+func BenchmarkGrayAt(b *testing.B) {
+	m := NewGray(Rect(0, 0, 10, 10))
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.GrayAt(4, 5)
+	}
+}
+
+func BenchmarkGraySetGray(b *testing.B) {
+	m := NewGray(Rect(0, 0, 10, 10))
+	c := color.Gray{0x13}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.SetGray(4, 5, c)
+	}
+}
+
+func BenchmarkGray16At(b *testing.B) {
+	m := NewGray16(Rect(0, 0, 10, 10))
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.Gray16At(4, 5)
+	}
+}
+
+func BenchmarkGraySetGray16(b *testing.B) {
+	m := NewGray16(Rect(0, 0, 10, 10))
+	c := color.Gray16{0x13}
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		m.SetGray16(4, 5, c)
+	}
+}