regexp: evaluate context flags lazily
There's no point in computing whether we're at the
beginning of the line if the NFA isn't going to ask.
Wait to compute that until asked.
Whatever minor slowdowns were introduced by
the conversion to pools that were not repaid by
other optimizations are taken care of by this one.
name old time/op new time/op delta
Find-12 252ns ± 0% 260ns ± 0% +3.34% (p=0.000 n=10+8)
FindAllNoMatches-12 136ns ± 4% 134ns ± 4% -0.96% (p=0.033 n=10+10)
FindString-12 246ns ± 0% 250ns ± 0% +1.46% (p=0.000 n=8+10)
FindSubmatch-12 332ns ± 1% 332ns ± 0% ~ (p=0.101 n=9+10)
FindStringSubmatch-12 321ns ± 1% 322ns ± 1% ~ (p=0.717 n=9+10)
Literal-12 91.6ns ± 0% 92.3ns ± 0% +0.74% (p=0.000 n=9+9)
NotLiteral-12 1.47µs ± 0% 1.47µs ± 0% +0.38% (p=0.000 n=9+8)
MatchClass-12 2.15µs ± 0% 2.15µs ± 0% +0.39% (p=0.000 n=10+10)
MatchClass_InRange-12 2.09µs ± 0% 2.11µs ± 0% +0.75% (p=0.000 n=9+9)
ReplaceAll-12 1.40µs ± 0% 1.40µs ± 0% ~ (p=0.525 n=10+10)
AnchoredLiteralShortNonMatch-12 83.5ns ± 0% 81.6ns ± 0% -2.28% (p=0.000 n=9+10)
AnchoredLiteralLongNonMatch-12 101ns ± 0% 97ns ± 1% -3.54% (p=0.000 n=10+10)
AnchoredShortMatch-12 131ns ± 0% 128ns ± 0% -2.29% (p=0.000 n=10+9)
AnchoredLongMatch-12 268ns ± 1% 252ns ± 1% -6.04% (p=0.000 n=10+10)
OnePassShortA-12 614ns ± 0% 587ns ± 1% -4.33% (p=0.000 n=6+10)
NotOnePassShortA-12 552ns ± 0% 547ns ± 1% -0.89% (p=0.000 n=10+10)
OnePassShortB-12 494ns ± 0% 455ns ± 0% -7.96% (p=0.000 n=9+9)
NotOnePassShortB-12 411ns ± 0% 406ns ± 0% -1.30% (p=0.000 n=9+9)
OnePassLongPrefix-12 109ns ± 0% 108ns ± 1% ~ (p=0.064 n=8+9)
OnePassLongNotPrefix-12 403ns ± 0% 349ns ± 0% -13.30% (p=0.000 n=9+8)
MatchParallelShared-12 38.9ns ± 1% 37.9ns ± 1% -2.65% (p=0.000 n=10+8)
MatchParallelCopied-12 39.2ns ± 1% 38.3ns ± 2% -2.20% (p=0.001 n=10+10)
QuoteMetaAll-12 94.5ns ± 0% 94.7ns ± 0% +0.18% (p=0.043 n=10+9)
QuoteMetaNone-12 52.7ns ± 0% 52.7ns ± 0% ~ (all equal)
Match/Easy0/32-12 72.2ns ± 0% 71.9ns ± 0% -0.38% (p=0.009 n=8+10)
Match/Easy0/1K-12 296ns ± 1% 297ns ± 0% +0.51% (p=0.001 n=10+9)
Match/Easy0/32K-12 4.57µs ± 3% 4.61µs ± 2% ~ (p=0.280 n=10+10)
Match/Easy0/1M-12 234µs ± 0% 234µs ± 0% ~ (p=0.986 n=10+10)
Match/Easy0/32M-12 7.96ms ± 0% 7.98ms ± 0% +0.22% (p=0.010 n=10+9)
Match/Easy0i/32-12 1.09µs ± 0% 1.10µs ± 0% +0.23% (p=0.000 n=8+9)
Match/Easy0i/1K-12 31.7µs ± 0% 31.7µs ± 0% +0.09% (p=0.003 n=9+8)
Match/Easy0i/32K-12 1.61ms ± 0% 1.27ms ± 1% -21.03% (p=0.000 n=8+10)
Match/Easy0i/1M-12 51.4ms ± 0% 40.4ms ± 0% -21.29% (p=0.000 n=8+8)
Match/Easy0i/32M-12 1.65s ± 0% 1.30s ± 1% -21.22% (p=0.000 n=9+9)
Match/Easy1/32-12 67.6ns ± 1% 67.2ns ± 0% ~ (p=0.085 n=10+9)
Match/Easy1/1K-12 873ns ± 2% 880ns ± 0% +0.78% (p=0.006 n=9+7)
Match/Easy1/32K-12 39.7µs ± 1% 34.3µs ± 3% -13.53% (p=0.000 n=10+10)
Match/Easy1/1M-12 1.41ms ± 1% 1.19ms ± 3% -15.48% (p=0.000 n=10+10)
Match/Easy1/32M-12 44.9ms ± 1% 38.0ms ± 2% -15.21% (p=0.000 n=10+10)
Match/Medium/32-12 1.04µs ± 0% 1.03µs ± 0% -0.57% (p=0.000 n=9+9)
Match/Medium/1K-12 31.2µs ± 0% 31.4µs ± 1% +0.61% (p=0.000 n=8+10)
Match/Medium/32K-12 1.45ms ± 1% 1.20ms ± 0% -17.70% (p=0.000 n=10+8)
Match/Medium/1M-12 46.4ms ± 0% 38.4ms ± 2% -17.32% (p=0.000 n=6+9)
Match/Medium/32M-12 1.49s ± 1% 1.24s ± 1% -16.81% (p=0.000 n=10+10)
Match/Hard/32-12 1.47µs ± 0% 1.47µs ± 0% -0.31% (p=0.000 n=9+10)
Match/Hard/1K-12 44.5µs ± 1% 44.4µs ± 0% ~ (p=0.075 n=10+10)
Match/Hard/32K-12 2.09ms ± 0% 1.78ms ± 7% -14.88% (p=0.000 n=8+10)
Match/Hard/1M-12 67.8ms ± 5% 56.9ms ± 7% -16.05% (p=0.000 n=10+10)
Match/Hard/32M-12 2.17s ± 5% 1.84s ± 6% -15.21% (p=0.000 n=10+10)
Match/Hard1/32-12 7.89µs ± 0% 7.94µs ± 0% +0.61% (p=0.000 n=9+9)
Match/Hard1/1K-12 246µs ± 0% 245µs ± 0% -0.30% (p=0.010 n=9+10)
Match/Hard1/32K-12 8.93ms ± 0% 8.17ms ± 0% -8.44% (p=0.000 n=9+8)
Match/Hard1/1M-12 286ms ± 0% 269ms ± 9% -5.66% (p=0.028 n=9+10)
Match/Hard1/32M-12 9.16s ± 0% 8.61s ± 8% -5.98% (p=0.028 n=9+10)
Match_onepass_regex/32-12 825ns ± 0% 712ns ± 0% -13.75% (p=0.000 n=8+8)
Match_onepass_regex/1K-12 28.7µs ± 1% 19.8µs ± 0% -30.99% (p=0.000 n=9+8)
Match_onepass_regex/32K-12 950µs ± 1% 628µs ± 0% -33.83% (p=0.000 n=9+8)
Match_onepass_regex/1M-12 30.4ms ± 0% 20.1ms ± 0% -33.74% (p=0.000 n=9+8)
Match_onepass_regex/32M-12 974ms ± 1% 646ms ± 0% -33.73% (p=0.000 n=9+8)
CompileOnepass-12 4.60µs ± 0% 4.59µs ± 0% ~ (p=0.063 n=8+9)
[Geo mean] 23.1µs 21.3µs -7.44%
https://perf.golang.org/search?q=upload:
20181004.4
Change-Id: I47cdd09f6dcde1d7c317080e9b4df42c7d0a8d24
Reviewed-on: https://go-review.googlesource.com/c/139782
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>