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bytes: Use the same algorithm as strings for Index

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name                     old time/op    new time/op      delta
IndexByte32-48             9.05ns ± 7%      9.59ns ±11%     +5.93%  (p=0.001 n=19+20)
IndexByte4K-48              118ns ± 4%       122ns ± 8%     +3.52%  (p=0.002 n=19+19)
IndexByte4M-48              172µs ±13%       188µs ±12%     +9.49%  (p=0.000 n=20+20)
IndexByte64M-48            8.00ms ±14%      8.05ms ±23%       ~     (p=0.799 n=20+20)
IndexBytePortable32-48     41.7ns ±15%      42.5ns ±12%       ~     (p=0.372 n=20+20)
IndexBytePortable4K-48     3.08µs ±16%      3.26µs ±10%     +5.77%  (p=0.018 n=20+20)
IndexBytePortable4M-48     3.12ms ±17%      3.20ms ±10%       ~     (p=0.157 n=20+20)
IndexBytePortable64M-48    54.0ms ±14%      55.3ms ±14%       ~     (p=0.640 n=20+20)
Index32-48                  230ns ±12%        46ns ± 6%    -79.87%  (p=0.000 n=20+19)
Index4K-48                 43.2µs ± 9%       3.2µs ±12%    -92.58%  (p=0.000 n=19+20)
Index4M-48                 44.4ms ± 7%       3.3ms ±13%    -92.59%  (p=0.000 n=19+20)
Index64M-48                 714ms ±10%        56ms ± 8%    -92.22%  (p=0.000 n=19+19)
IndexEasy32-48             52.7ns ±10%      31.0ns ±11%    -41.21%  (p=0.000 n=20+20)
IndexEasy4K-48              139ns ± 5%      1598ns ± 6%  +1046.37%  (p=0.000 n=19+19)
IndexEasy4M-48              179µs ± 8%      1674µs ±10%   +834.31%  (p=0.000 n=19+20)
IndexEasy64M-48            8.56ms ±10%     27.82ms ±16%   +225.14%  (p=0.000 n=19+20)

name                     old speed      new speed        delta
IndexByte32-48           3.52GB/s ± 7%    3.35GB/s ±11%     -4.99%  (p=0.001 n=20+20)
IndexByte4K-48           34.5GB/s ± 7%    33.2GB/s ±10%     -3.67%  (p=0.002 n=20+20)
IndexByte4M-48           24.6GB/s ±14%    22.4GB/s ±14%     -8.73%  (p=0.000 n=20+20)
IndexByte64M-48          8.42GB/s ±16%    8.42GB/s ±19%       ~     (p=0.799 n=20+20)
IndexBytePortable32-48    770MB/s ±13%     756MB/s ±11%       ~     (p=0.383 n=20+20)
IndexBytePortable4K-48   1.34GB/s ±14%    1.26GB/s ±10%     -5.76%  (p=0.018 n=20+20)
IndexBytePortable4M-48   1.35GB/s ±15%    1.31GB/s ±11%       ~     (p=0.157 n=20+20)
IndexBytePortable64M-48  1.25GB/s ±16%    1.22GB/s ±13%       ~     (p=0.640 n=20+20)
Index32-48                138MB/s ± 8%     687MB/s ± 8%   +398.57%  (p=0.000 n=19+20)
Index4K-48               94.9MB/s ± 9%  1280.5MB/s ±11%  +1249.11%  (p=0.000 n=19+20)
Index4M-48               94.6MB/s ± 7%  1278.5MB/s ±12%  +1250.99%  (p=0.000 n=19+20)
Index64M-48              94.2MB/s ±10%  1210.9MB/s ± 8%  +1185.04%  (p=0.000 n=19+19)
IndexEasy32-48            608MB/s ±10%    1035MB/s ±10%    +70.15%  (p=0.000 n=20+20)
IndexEasy4K-48           29.3GB/s ± 6%     2.6GB/s ± 6%    -91.24%  (p=0.000 n=19+19)
IndexEasy4M-48           23.3GB/s ±10%     2.5GB/s ± 9%    -89.23%  (p=0.000 n=20+20)
IndexEasy64M-48          7.86GB/s ±11%    2.42GB/s ±14%    -69.18%  (p=0.000 n=19+20)

Change-Id: Ia191f0a6ca80e113397d9ed98d25f195768b65bc
Reviewed-on: https://go-review.googlesource.com/22550
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Ilya Tocar 2016-04-28 17:34:24 +03:00
parent 1c53a1b197
commit 44f1854c9d
4 changed files with 132 additions and 35 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

31
src/bytes/bytes.go
View file

@ -93,37 +93,6 @@ func ContainsRune(b []byte, r rune) bool {
return IndexRune(b, r) >= 0
}
// Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
func Index(s, sep []byte) int {
n := len(sep)
if n == 0 {
return 0
}
if n > len(s) {
return -1
}
c := sep[0]
if n == 1 {
return IndexByte(s, c)
}
i := 0
t := s[:len(s)-n+1]
for i < len(t) {
if t[i] != c {
o := IndexByte(t[i:], c)
if o < 0 {
break
}
i += o
}
if Equal(s[i:i+n], sep) {
return i
}
i++
}
return -1
}
func indexBytePortable(s []byte, c byte) int {
for i, b := range s {
if b == c {

69
src/bytes/bytes_amd64.go Normal file
View file

@ -0,0 +1,69 @@
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package bytes
// indexShortStr returns the index of the first instance of c in s, or -1 if c is not present in s.
// indexShortStr requires 2 <= len(c) <= shortStringLen
func indexShortStr(s, c []byte) int // ../runtime/asm_$GOARCH.s
const shortStringLen = 31
// Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
func Index(s, sep []byte) int {
n := len(sep)
switch {
case n == 0:
return 0
case n == 1:
return IndexByte(s, sep[0])
case n <= shortStringLen:
return indexShortStr(s, sep)
case n == len(s):
if Equal(sep, s) {
return 0
}
return -1
case n > len(s):
return -1
}
// Rabin-Karp search
hashsep, pow := hashStr(sep)
var h uint32
for i := 0; i < n; i++ {
h = h*primeRK + uint32(s[i])
}
if h == hashsep && Equal(s[:n], sep) {
return 0
}
for i := n; i < len(s); {
h *= primeRK
h += uint32(s[i])
h -= pow * uint32(s[i-n])
i++
if h == hashsep && Equal(s[i-n:i], sep) {
return i - n
}
}
return -1
}
// primeRK is the prime base used in Rabin-Karp algorithm.
const primeRK = 16777619
// hashStr returns the hash and the appropriate multiplicative
// factor for use in Rabin-Karp algorithm.
func hashStr(sep []byte) (uint32, uint32) {
hash := uint32(0)
for i := 0; i < len(sep); i++ {
hash = hash*primeRK + uint32(sep[i])
}
var pow, sq uint32 = 1, primeRK
for i := len(sep); i > 0; i >>= 1 {
if i&1 != 0 {
pow *= sq
}
sq *= sq
}
return hash, pow
}

41
src/bytes/bytes_generic.go Normal file
View file

@ -0,0 +1,41 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !amd64
package bytes
// TODO: implements short string optimization on non amd64 platforms
// and get rid of bytes_amd64.go
// Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
func Index(s, sep []byte) int {
n := len(sep)
if n == 0 {
return 0
}
if n > len(s) {
return -1
}
c := sep[0]
if n == 1 {
return IndexByte(s, c)
}
i := 0
t := s[:len(s)-n+1]
for i < len(t) {
if t[i] != c {
o := IndexByte(t[i:], c)
if o < 0 {
break
}
i += o
}
if Equal(s[i:i+n], sep) {
return i
}
i++
}
return -1
}

26
src/runtime/asm_amd64.s
View file

@ -1695,13 +1695,31 @@ big_loop_avx2_exit:
JMP loop
// TODO: Also use this in bytes.Index
TEXT strings·indexShortStr(SB),NOSPLIT,$0-40
MOVQ s+0(FP), DI
// We want len in DX and AX, because PCMPESTRI implicitly consumes them
MOVQ s_len+8(FP), DX
MOVQ c+16(FP), BP
MOVQ c_len+24(FP), AX
MOVQ DI, R10
LEAQ ret+32(FP), R11
JMP runtime·indexShortStr(SB)
TEXT bytes·indexShortStr(SB),NOSPLIT,$0-56
MOVQ s+0(FP), DI
MOVQ s_len+8(FP), DX
MOVQ c+24(FP), BP
MOVQ c_len+32(FP), AX
MOVQ DI, R10
LEAQ ret+48(FP), R11
JMP runtime·indexShortStr(SB)
// AX: length of string, that we are searching for
// DX: length of string, in which we are searching
// DI: pointer to string, in which we are searching
// BP: pointer to string, that we are searching for
// R11: address, where to put return value
TEXT runtime·indexShortStr(SB),NOSPLIT,$0
CMPQ AX, DX
JA fail
CMPQ DX, $16
@ -1853,7 +1871,7 @@ partial_success17to31:
CMPQ DI,DX
JB loop17to31
fail:
MOVQ $-1, ret+32(FP)
MOVQ $-1, (R11)
RET
sse42:
MOVL runtime·cpuid_ecx(SB), CX
@ -1893,8 +1911,8 @@ loop_sse42:
sse42_success:
ADDQ CX, DI
success:
SUBQ s+0(FP), DI
MOVQ DI, ret+32(FP)
SUBQ R10, DI
MOVQ DI, (R11)
RET