From f04f594a1fd1e8cf1bd01f9dc62599d5bd6e1d92 Mon Sep 17 00:00:00 2001 From: Nao YONASHIRO Date: Wed, 24 Jul 2019 22:00:58 +0900 Subject: [PATCH] image/png: hoist repetitive pixels per byte out of loop in Encode MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The existing implementation has calculated pixels per byte for each pixel. reduce the calculation of pixels per byte. name old time/op new time/op delta EncodeGray-4 2.16ms ± 1% 2.16ms ± 1% -0.28% (p=0.000 n=86+84) EncodeGrayWithBufferPool-4 1.99ms ± 0% 1.97ms ± 0% -0.72% (p=0.000 n=97+92) EncodeNRGBOpaque-4 6.51ms ± 1% 6.48ms ± 1% -0.45% (p=0.000 n=90+85) EncodeNRGBA-4 7.33ms ± 1% 7.28ms ± 0% -0.69% (p=0.000 n=89+87) EncodePaletted-4 5.10ms ± 1% 2.29ms ± 0% -55.11% (p=0.000 n=90+85) EncodeRGBOpaque-4 6.51ms ± 1% 6.51ms ± 0% ~ (p=0.311 n=94+88) EncodeRGBA-4 24.3ms ± 2% 24.1ms ± 1% -0.87% (p=0.000 n=91+91) name old speed new speed delta EncodeGray-4 142MB/s ± 1% 143MB/s ± 1% +0.26% (p=0.000 n=86+85) EncodeGrayWithBufferPool-4 154MB/s ± 0% 156MB/s ± 0% +0.73% (p=0.000 n=97+92) EncodeNRGBOpaque-4 189MB/s ± 1% 190MB/s ± 1% +0.44% (p=0.000 n=90+86) EncodeNRGBA-4 168MB/s ± 1% 169MB/s ± 0% +0.69% (p=0.000 n=89+87) EncodePaletted-4 60.3MB/s ± 1% 134.2MB/s ± 0% +122.74% (p=0.000 n=90+85) EncodeRGBOpaque-4 189MB/s ± 1% 189MB/s ± 0% ~ (p=0.326 n=94+88) EncodeRGBA-4 50.6MB/s ± 2% 51.1MB/s ± 1% +0.87% (p=0.000 n=91+91) name old alloc/op new alloc/op delta EncodeGray-4 852kB ± 0% 852kB ± 0% +0.00% (p=0.000 n=100+100) EncodeGrayWithBufferPool-4 1.49kB ± 2% 1.47kB ± 1% -0.88% (p=0.000 n=95+90) EncodeNRGBOpaque-4 860kB ± 0% 860kB ± 0% +0.00% (p=0.003 n=98+58) EncodeNRGBA-4 864kB ± 0% 864kB ± 0% +0.00% (p=0.021 n=100+99) EncodePaletted-4 849kB ± 0% 849kB ± 0% +0.00% (p=0.040 n=100+100) EncodeRGBOpaque-4 860kB ± 0% 860kB ± 0% ~ (p=0.062 n=66+98) EncodeRGBA-4 3.32MB ± 0% 3.32MB ± 0% -0.00% (p=0.044 n=99+99) name old allocs/op new allocs/op delta EncodeGray-4 32.0 ± 0% 32.0 ± 0% ~ (all equal) EncodeGrayWithBufferPool-4 3.00 ± 0% 3.00 ± 0% ~ (all equal) EncodeNRGBOpaque-4 32.0 ± 0% 32.0 ± 0% ~ (all equal) EncodeNRGBA-4 32.0 ± 0% 32.0 ± 0% ~ (all equal) EncodePaletted-4 36.0 ± 0% 36.0 ± 0% ~ (all equal) EncodeRGBOpaque-4 32.0 ± 0% 32.0 ± 0% ~ (all equal) EncodeRGBA-4 614k ± 0% 614k ± 0% ~ (all equal) Change-Id: I716bde2dc80d8111d75d3d765fc09223f770d5a5 Reviewed-on: https://go-review.googlesource.com/c/go/+/187417 Reviewed-by: Emmanuel Odeke Reviewed-by: Nigel Tao Run-TryBot: Emmanuel Odeke TryBot-Result: Gobot Gobot --- src/image/png/writer.go | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/image/png/writer.go b/src/image/png/writer.go index 2bd4fde692..53adc1633c 100644 --- a/src/image/png/writer.go +++ b/src/image/png/writer.go @@ -426,10 +426,11 @@ func (e *encoder) writeImage(w io.Writer, m image.Image, cb int, level int) erro var a uint8 var c int + pixelsPerByte := 8 / bitsPerPixel for x := b.Min.X; x < b.Max.X; x++ { a = a<