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compress/flate: optimize huffSym
By using local variables and assigning them back to decompressor at the end of huffSym, we allow compiler to keep them in registers and avoid reloading/storing them repeatedly. To archive this, moreBits was inlined and specialized to work with local variables. Also move EOF error conversion to helper function, to make inlined part of moreBits more readable. Together this results in nice speed-up: name old time/op new time/op delta Decode/Digits/Huffman/1e4-6 278µs ± 1% 240µs ± 2% -13.72% (p=0.000 n=10+10) Decode/Digits/Huffman/1e5-6 2.38ms ± 1% 2.05ms ± 1% -14.12% (p=0.000 n=10+10) Decode/Digits/Huffman/1e6-6 23.4ms ± 1% 19.9ms ± 0% -14.69% (p=0.000 n=9+9) Decode/Digits/Speed/1e4-6 280µs ± 2% 254µs ± 1% -9.28% (p=0.000 n=10+9) Decode/Digits/Speed/1e5-6 2.53ms ± 1% 2.35ms ± 1% -7.17% (p=0.000 n=10+10) Decode/Digits/Speed/1e6-6 24.8ms ± 1% 23.0ms ± 1% -7.22% (p=0.000 n=10+10) Decode/Digits/Default/1e4-6 281µs ± 2% 259µs ± 3% -8.03% (p=0.000 n=10+10) Decode/Digits/Default/1e5-6 2.45ms ± 1% 2.30ms ± 1% -6.15% (p=0.000 n=10+10) Decode/Digits/Default/1e6-6 24.1ms ± 1% 22.6ms ± 0% -6.31% (p=0.000 n=9+9) Decode/Digits/Compression/1e4-6 279µs ± 2% 261µs ± 2% -6.53% (p=0.000 n=8+9) Decode/Digits/Compression/1e5-6 2.44ms ± 1% 2.30ms ± 1% -5.72% (p=0.000 n=10+9) Decode/Digits/Compression/1e6-6 24.0ms ± 1% 22.6ms ± 0% -6.10% (p=0.000 n=10+9) Decode/Twain/Huffman/1e4-6 316µs ± 2% 267µs ± 3% -15.30% (p=0.000 n=9+10) Decode/Twain/Huffman/1e5-6 2.62ms ± 0% 2.22ms ± 0% -15.24% (p=0.000 n=10+10) Decode/Twain/Huffman/1e6-6 25.7ms ± 1% 21.8ms ± 0% -15.19% (p=0.000 n=10+10) Decode/Twain/Speed/1e4-6 290µs ± 1% 264µs ± 2% -9.17% (p=0.000 n=9+10) Decode/Twain/Speed/1e5-6 2.35ms ± 1% 2.13ms ± 1% -9.74% (p=0.000 n=9+10) Decode/Twain/Speed/1e6-6 22.9ms ± 0% 20.7ms ± 0% -9.68% (p=0.000 n=10+9) Decode/Twain/Default/1e4-6 270µs ± 2% 252µs ± 2% -6.67% (p=0.000 n=9+10) Decode/Twain/Default/1e5-6 2.02ms ± 1% 1.84ms ± 1% -8.85% (p=0.000 n=10+10) Decode/Twain/Default/1e6-6 19.1ms ± 0% 17.5ms ± 1% -8.73% (p=0.000 n=9+10) Decode/Twain/Compression/1e4-6 272µs ± 1% 250µs ± 4% -8.20% (p=0.000 n=9+10) Decode/Twain/Compression/1e5-6 2.01ms ± 0% 1.84ms ± 1% -8.57% (p=0.000 n=9+10) Decode/Twain/Compression/1e6-6 19.1ms ± 0% 17.4ms ± 1% -8.75% (p=0.000 n=9+10) name old speed new speed delta Decode/Digits/Huffman/1e4-6 35.9MB/s ± 1% 41.7MB/s ± 2% +15.91% (p=0.000 n=10+10) Decode/Digits/Huffman/1e5-6 41.9MB/s ± 1% 48.8MB/s ± 1% +16.44% (p=0.000 n=10+10) Decode/Digits/Huffman/1e6-6 42.8MB/s ± 1% 50.2MB/s ± 0% +17.22% (p=0.000 n=9+9) Decode/Digits/Speed/1e4-6 35.7MB/s ± 2% 39.4MB/s ± 1% +10.22% (p=0.000 n=10+9) Decode/Digits/Speed/1e5-6 39.6MB/s ± 1% 42.6MB/s ± 1% +7.73% (p=0.000 n=10+10) Decode/Digits/Speed/1e6-6 40.3MB/s ± 1% 43.4MB/s ± 1% +7.78% (p=0.000 n=10+10) Decode/Digits/Default/1e4-6 35.6MB/s ± 2% 38.7MB/s ± 2% +8.74% (p=0.000 n=10+10) Decode/Digits/Default/1e5-6 40.9MB/s ± 1% 43.6MB/s ± 1% +6.55% (p=0.000 n=10+10) Decode/Digits/Default/1e6-6 41.5MB/s ± 1% 44.3MB/s ± 0% +6.73% (p=0.000 n=9+9) Decode/Digits/Compression/1e4-6 35.8MB/s ± 2% 38.3MB/s ± 2% +6.99% (p=0.000 n=8+9) Decode/Digits/Compression/1e5-6 40.9MB/s ± 1% 43.4MB/s ± 1% +6.07% (p=0.000 n=10+9) Decode/Digits/Compression/1e6-6 41.6MB/s ± 1% 44.3MB/s ± 0% +6.49% (p=0.000 n=10+9) Decode/Twain/Huffman/1e4-6 31.7MB/s ± 2% 37.4MB/s ± 3% +18.08% (p=0.000 n=9+10) Decode/Twain/Huffman/1e5-6 38.2MB/s ± 0% 45.0MB/s ± 0% +17.97% (p=0.000 n=10+10) Decode/Twain/Huffman/1e6-6 38.9MB/s ± 1% 45.9MB/s ± 0% +17.90% (p=0.000 n=10+10) Decode/Twain/Speed/1e4-6 34.5MB/s ± 1% 38.0MB/s ± 2% +10.11% (p=0.000 n=9+10) Decode/Twain/Speed/1e5-6 42.5MB/s ± 1% 47.0MB/s ± 1% +10.79% (p=0.000 n=9+10) Decode/Twain/Speed/1e6-6 43.7MB/s ± 0% 48.3MB/s ± 0% +10.72% (p=0.000 n=10+9) Decode/Twain/Default/1e4-6 37.1MB/s ± 2% 39.8MB/s ± 2% +7.15% (p=0.000 n=9+10) Decode/Twain/Default/1e5-6 49.5MB/s ± 1% 54.3MB/s ± 1% +9.71% (p=0.000 n=10+10) Decode/Twain/Default/1e6-6 52.3MB/s ± 0% 57.3MB/s ± 1% +9.57% (p=0.000 n=9+10) Decode/Twain/Compression/1e4-6 36.7MB/s ± 1% 40.0MB/s ± 4% +8.96% (p=0.000 n=9+10) Decode/Twain/Compression/1e5-6 49.8MB/s ± 0% 54.5MB/s ± 1% +9.38% (p=0.000 n=9+10) Decode/Twain/Compression/1e6-6 52.3MB/s ± 0% 57.3MB/s ± 1% +9.58% (p=0.000 n=9+10) Change-Id: Iabfd285535ddb210f7f48f33317c6463b5532400 Reviewed-on: https://go-review.googlesource.com/102235 Run-TryBot: Ilya Tocar <ilya.tocar@intel.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Ilya Tocar
Brad Fitzpatrick
parent
9db1dd074d
commit
4984d843d9
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@ -629,10 +629,7 @@ func (f *decompressor) dataBlock() {
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nr, err := io.ReadFull(f.r, f.buf[0:4])
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f.roffset += int64(nr)
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if err != nil {
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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f.err = err
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f.err = noEOF(err)
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return
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}
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n := int(f.buf[0]) | int(f.buf[1])<<8
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@ -665,10 +662,7 @@ func (f *decompressor) copyData() {
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f.copyLen -= cnt
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f.dict.writeMark(cnt)
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if err != nil {
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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f.err = err
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f.err = noEOF(err)
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return
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}
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@ -690,13 +684,18 @@ func (f *decompressor) finishBlock() {
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f.step = (*decompressor).nextBlock
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}
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// noEOF returns err, unless err == io.EOF, in which case it returns io.ErrUnexpectedEOF.
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func noEOF(e error) error {
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if e == io.EOF {
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return io.ErrUnexpectedEOF
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}
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return e
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}
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func (f *decompressor) moreBits() error {
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c, err := f.r.ReadByte()
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if err != nil {
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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return err
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return noEOF(err)
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}
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f.roffset++
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f.b |= uint32(c) << f.nb
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@ -711,25 +710,37 @@ func (f *decompressor) huffSym(h *huffmanDecoder) (int, error) {
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// cases, the chunks slice will be 0 for the invalid sequence, leading it
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// satisfy the n == 0 check below.
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n := uint(h.min)
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// Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
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// but is smart enough to keep local variables in registers, so use nb and b,
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// inline call to moreBits and reassign b,nb back to f on return.
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nb, b := f.nb, f.b
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for {
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for f.nb < n {
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if err := f.moreBits(); err != nil {
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return 0, err
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for nb < n {
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c, err := f.r.ReadByte()
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if err != nil {
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f.b = b
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f.nb = nb
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return 0, noEOF(err)
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}
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f.roffset++
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b |= uint32(c) << (nb & 31)
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nb += 8
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}
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chunk := h.chunks[f.b&(huffmanNumChunks-1)]
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chunk := h.chunks[b&(huffmanNumChunks-1)]
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n = uint(chunk & huffmanCountMask)
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if n > huffmanChunkBits {
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chunk = h.links[chunk>>huffmanValueShift][(f.b>>huffmanChunkBits)&h.linkMask]
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chunk = h.links[chunk>>huffmanValueShift][(b>>huffmanChunkBits)&h.linkMask]
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n = uint(chunk & huffmanCountMask)
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}
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if n <= f.nb {
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if n <= nb {
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if n == 0 {
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f.b = b
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f.nb = nb
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f.err = CorruptInputError(f.roffset)
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return 0, f.err
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}
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f.b >>= n
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f.nb -= n
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f.b = b >> (n & 31)
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f.nb = nb - n
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return int(chunk >> huffmanValueShift), nil
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}
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}
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