From 8a16d7d40a371e61f6d30604224039cf9a46d106 Mon Sep 17 00:00:00 2001 From: haya14busa Date: Fri, 17 Mar 2017 00:41:58 +0900 Subject: [PATCH] regexp: reduce allocs in regexp.Match for onepass regex There were no allocations in regexp.Match for *non* onepass regex because m.matchcap length is reset to zero (ncap=0 for regexp.Match). But, as for onepass regex, m.matchcap length remains as it is even when ncap=0 and it leads needless allocations. benchmark old ns/op new ns/op delta BenchmarkMatch_onepass_regex/32-4 6465 4628 -28.41% BenchmarkMatch_onepass_regex/1K-4 208324 151558 -27.25% BenchmarkMatch_onepass_regex/32K-4 7230259 5834492 -19.30% BenchmarkMatch_onepass_regex/1M-4 234379810 166310682 -29.04% BenchmarkMatch_onepass_regex/32M-4 7903529363 4981119950 -36.98% benchmark old MB/s new MB/s speedup BenchmarkMatch_onepass_regex/32-4 4.95 6.91 1.40x BenchmarkMatch_onepass_regex/1K-4 4.92 6.76 1.37x BenchmarkMatch_onepass_regex/32K-4 4.53 5.62 1.24x BenchmarkMatch_onepass_regex/1M-4 4.47 6.30 1.41x BenchmarkMatch_onepass_regex/32M-4 4.25 6.74 1.59x benchmark old allocs new allocs delta BenchmarkMatch_onepass_regex/32-4 32 0 -100.00% BenchmarkMatch_onepass_regex/1K-4 1024 0 -100.00% BenchmarkMatch_onepass_regex/32K-4 32768 0 -100.00% BenchmarkMatch_onepass_regex/1M-4 1048576 0 -100.00% BenchmarkMatch_onepass_regex/32M-4 104559255 0 -100.00% benchmark old bytes new bytes delta BenchmarkMatch_onepass_regex/32-4 512 0 -100.00% BenchmarkMatch_onepass_regex/1K-4 16384 0 -100.00% BenchmarkMatch_onepass_regex/32K-4 524288 0 -100.00% BenchmarkMatch_onepass_regex/1M-4 16777216 0 -100.00% BenchmarkMatch_onepass_regex/32M-4 2019458128 0 -100.00% Fixes #19573 Change-Id: I033982d0003ebb0360bb40b92eb3941c781ec74d Reviewed-on: https://go-review.googlesource.com/38270 Run-TryBot: Michael Matloob TryBot-Result: Gobot Gobot Reviewed-by: Brad Fitzpatrick --- src/regexp/exec.go | 6 ++++-- src/regexp/exec_test.go | 29 +++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 2 deletions(-) diff --git a/src/regexp/exec.go b/src/regexp/exec.go index 977619cb28a..f8fe7b5deff 100644 --- a/src/regexp/exec.go +++ b/src/regexp/exec.go @@ -309,12 +309,14 @@ func (m *machine) add(q *queue, pc uint32, pos int, cap []int, cond syntax.Empty // onepass runs the machine over the input starting at pos. // It reports whether a match was found. // If so, m.matchcap holds the submatch information. -func (m *machine) onepass(i input, pos int) bool { +// ncap is the number of captures. +func (m *machine) onepass(i input, pos, ncap int) bool { startCond := m.re.cond if startCond == ^syntax.EmptyOp(0) { // impossible return false } m.matched = false + m.matchcap = m.matchcap[:ncap] for i := range m.matchcap { m.matchcap[i] = -1 } @@ -428,7 +430,7 @@ func (re *Regexp) doExecute(r io.RuneReader, b []byte, s string, pos int, ncap i size = len(s) } if m.op != notOnePass { - if !m.onepass(i, pos) { + if !m.onepass(i, pos, ncap) { re.put(m) return nil } diff --git a/src/regexp/exec_test.go b/src/regexp/exec_test.go index 766394de6ee..5f8e747b17b 100644 --- a/src/regexp/exec_test.go +++ b/src/regexp/exec_test.go @@ -681,6 +681,35 @@ func BenchmarkMatch(b *testing.B) { } } +func BenchmarkMatch_onepass_regex(b *testing.B) { + isRaceBuilder := strings.HasSuffix(testenv.Builder(), "-race") + r := MustCompile(`(?s)\A.*\z`) + if r.get().op == notOnePass { + b.Fatalf("want onepass regex, but %q is not onepass", r) + } + for _, size := range benchSizes { + if isRaceBuilder && size.n > 1<<10 { + continue + } + t := makeText(size.n) + bs := make([][]byte, len(t)) + for i, s := range t { + bs[i] = []byte{s} + } + b.Run(size.name, func(b *testing.B) { + b.SetBytes(int64(size.n)) + b.ReportAllocs() + for i := 0; i < b.N; i++ { + for _, byts := range bs { + if !r.Match(byts) { + b.Fatal("not match!") + } + } + } + }) + } +} + var benchData = []struct{ name, re string }{ {"Easy0", "ABCDEFGHIJKLMNOPQRSTUVWXYZ$"}, {"Easy0i", "(?i)ABCDEFGHIJklmnopqrstuvwxyz$"},