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regexp: port RE2's bitstate backtracker to the regexp package

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This is a port of RE2's bitstate backtracker, which triggers under
the same conditions that the RE2 backtracker triggers.  However I wasn't
sure how to port over some of the optimizations in the RE2 backtracker,
and there is a ~2% penalty on benchmarks that don't trigger the backtracker.

benchmark                                 old ns/op      new ns/op      delta
BenchmarkLiteral                          312            189            -39.42%
BenchmarkNotLiteral                       4435           3001           -32.33%
BenchmarkMatchClass                       5758           4378           -23.97%
BenchmarkMatchClass_InRange               5385           4084           -24.16%
BenchmarkReplaceAll                       5291           3505           -33.76%
BenchmarkAnchoredLiteralShortNonMatch     190            200            +5.26%
BenchmarkAnchoredLiteralLongNonMatch      189            194            +2.65%
BenchmarkAnchoredShortMatch               479            304            -36.53%
BenchmarkAnchoredLongMatch                478            499            +4.39%
BenchmarkOnePassShortA                    791            798            +0.88%
BenchmarkNotOnePassShortA                 3202           1571           -50.94%
BenchmarkOnePassShortB                    614            633            +3.09%
BenchmarkNotOnePassShortB                 2685           881            -67.19%
BenchmarkOnePassLongPrefix                152            154            +1.32%
BenchmarkOnePassLongNotPrefix             505            533            +5.54%
BenchmarkMatchEasy0_32                    139            171            +23.02%
BenchmarkMatchEasy0_1K                    653            1797           +175.19%
BenchmarkMatchEasy0_32K                   12032          13346          +10.92%
BenchmarkMatchEasy0_1M                    462882         461272         -0.35%
BenchmarkMatchEasy0_32M                   15015339       15365238       +2.33%
BenchmarkMatchEasy1_32                    122            168            +37.70%
BenchmarkMatchEasy1_1K                    3339           2612           -21.77%
BenchmarkMatchEasy1_32K                   72330          71721          -0.84%
BenchmarkMatchEasy1_1M                    2545410        2652284        +4.20%
BenchmarkMatchEasy1_32M                   80072063       82609750       +3.17%
BenchmarkMatchMedium_32                   2359           1980           -16.07%
BenchmarkMatchMedium_1K                   75939          58593          -22.84%
BenchmarkMatchMedium_32K                  2450907        2501106        +2.05%
BenchmarkMatchMedium_1M                   78707697       80174418       +1.86%
BenchmarkMatchMedium_32M                  2535146010     2570896441     +1.41%
BenchmarkMatchHard_32                     4297           2960           -31.11%
BenchmarkMatchHard_1K                     133592         88997          -33.38%
BenchmarkMatchHard_32K                    4240445        4336907        +2.27%
BenchmarkMatchHard_1M                     136187006      139350238      +2.32%
BenchmarkMatchHard_32M                    4350855890     4478537306     +2.93%

benchmark                    old MB/s     new MB/s     speedup
BenchmarkMatchEasy0_32       228.74       186.11       0.81x
BenchmarkMatchEasy0_1K       1565.91      569.64       0.36x
BenchmarkMatchEasy0_32K      2723.31      2455.10      0.90x
BenchmarkMatchEasy0_1M       2265.32      2273.22      1.00x
BenchmarkMatchEasy0_32M      2234.68      2183.79      0.98x
BenchmarkMatchEasy1_32       261.08       190.22       0.73x
BenchmarkMatchEasy1_1K       306.59       391.91       1.28x
BenchmarkMatchEasy1_32K      453.03       456.88       1.01x
BenchmarkMatchEasy1_1M       411.95       395.35       0.96x
BenchmarkMatchEasy1_32M      419.05       406.18       0.97x
BenchmarkMatchMedium_32      13.56        16.16        1.19x
BenchmarkMatchMedium_1K      13.48        17.48        1.30x
BenchmarkMatchMedium_32K     13.37        13.10        0.98x
BenchmarkMatchMedium_1M      13.32        13.08        0.98x
BenchmarkMatchMedium_32M     13.24        13.05        0.99x
BenchmarkMatchHard_32        7.45         10.81        1.45x
BenchmarkMatchHard_1K        7.67         11.51        1.50x
BenchmarkMatchHard_32K       7.73         7.56         0.98x
BenchmarkMatchHard_1M        7.70         7.52         0.98x
BenchmarkMatchHard_32M       7.71         7.49         0.97x

Fixes #4154

Change-Id: Iff7fb9507f0872b320d08afc08679751ed1b28bc
Reviewed-on: https://go-review.googlesource.com/2153
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Michael Matloob 2014-12-28 00:17:01 -08:00 • committed by Rob Pike
parent f7befa43a3
commit 93238623e2
2 changed files with 374 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

30
src/regexp/exec.go
View file

@ -35,13 +35,15 @@ type thread struct {
// A machine holds all the state during an NFA simulation for p.
type machine struct {
re *Regexp // corresponding Regexp
p *syntax.Prog // compiled program
op *onePassProg // compiled onepass program, or notOnePass
q0, q1 queue // two queues for runq, nextq
pool []*thread // pool of available threads
matched bool // whether a match was found
matchcap []int // capture information for the match
re *Regexp // corresponding Regexp
p *syntax.Prog // compiled program
op *onePassProg // compiled onepass program, or notOnePass
maxBitStateLen int // max length of string to search with bitstate
b *bitState // state for backtracker, allocated lazily
q0, q1 queue // two queues for runq, nextq
pool []*thread // pool of available threads
matched bool // whether a match was found
matchcap []int // capture information for the match
// cached inputs, to avoid allocation
inputBytes inputBytes
@ -76,6 +78,9 @@ func progMachine(p *syntax.Prog, op *onePassProg) *machine {
if ncap < 2 {
ncap = 2
}
if op == notOnePass {
m.maxBitStateLen = maxBitStateLen(p)
}
m.matchcap = make([]int, ncap)
return m
}
@ -422,18 +427,29 @@ var empty = make([]int, 0)
func (re *Regexp) doExecute(r io.RuneReader, b []byte, s string, pos int, ncap int) []int {
m := re.get()
var i input
var size int
if r != nil {
i = m.newInputReader(r)
} else if b != nil {
i = m.newInputBytes(b)
size = len(b)
} else {
i = m.newInputString(s)
size = len(s)
}
if m.op != notOnePass {
if !m.onepass(i, pos) {
re.put(m)
return nil
}
} else if size < m.maxBitStateLen && r == nil {
if m.b == nil {
m.b = newBitState(m.p)
}
if !m.backtrack(i, pos, size, ncap) {
re.put(m)
return nil
}
} else {
m.init(ncap)
if !m.match(i, pos) {