regexp: speedups

MatchEasy0_1K        500000        4207 ns/op   243.35 MB/s
MatchEasy0_1K_Old    500000        4625 ns/op   221.40 MB/s
MatchEasy0_1M           500     3948932 ns/op   265.53 MB/s
MatchEasy0_1M_Old       500     3943926 ns/op   265.87 MB/s
MatchEasy0_32K        10000      122974 ns/op   266.46 MB/s
MatchEasy0_32K_Old    10000      123270 ns/op   265.82 MB/s
MatchEasy0_32M           10   127265400 ns/op   263.66 MB/s
MatchEasy0_32M_Old       10   127123500 ns/op   263.95 MB/s
MatchEasy1_1K        500000        5637 ns/op   181.63 MB/s
MatchEasy1_1K_Old     10000      100690 ns/op    10.17 MB/s
MatchEasy1_1M           200     7683150 ns/op   136.48 MB/s
MatchEasy1_1M_Old        10   145774000 ns/op     7.19 MB/s
MatchEasy1_32K        10000      239887 ns/op   136.60 MB/s
MatchEasy1_32K_Old      500     4508182 ns/op     7.27 MB/s
MatchEasy1_32M           10   247103500 ns/op   135.79 MB/s
MatchEasy1_32M_Old        1  4660191000 ns/op     7.20 MB/s
MatchMedium_1K        10000      160567 ns/op     6.38 MB/s
MatchMedium_1K_Old    10000      158367 ns/op     6.47 MB/s
MatchMedium_1M           10   162928000 ns/op     6.44 MB/s
MatchMedium_1M_Old       10   159699200 ns/op     6.57 MB/s
MatchMedium_32K         500     5090758 ns/op     6.44 MB/s
MatchMedium_32K_Old     500     5005800 ns/op     6.55 MB/s
MatchMedium_32M           1  5233973000 ns/op     6.41 MB/s
MatchMedium_32M_Old       1  5109676000 ns/op     6.57 MB/s
MatchHard_1K          10000      249087 ns/op     4.11 MB/s
MatchHard_1K_Old       5000      364569 ns/op     2.81 MB/s
MatchHard_1M              5   256050000 ns/op     4.10 MB/s
MatchHard_1M_Old          5   372446400 ns/op     2.82 MB/s
MatchHard_32K           200     7944525 ns/op     4.12 MB/s
MatchHard_32K_Old       100    11609380 ns/op     2.82 MB/s
MatchHard_32M             1  8144503000 ns/op     4.12 MB/s
MatchHard_32M_Old         1 11885434000 ns/op     2.82 MB/s

R=r, bradfitz
CC=golang-dev
https://golang.org/cl/5134049

src/pkg/regexp/exec.go

@@ -50,6 +50,13 @@ func progMachine(p *syntax.Prog) *machine {
 	return m
 }
 
+func (m *machine) init(ncap int) {
+	for _, t := range m.pool {
+		t.cap = t.cap[:ncap]
+	}
+	m.matchcap = m.matchcap[:ncap]
+}
+
 // alloc allocates a new thread with the given instruction.
 // It uses the free pool if possible.
 func (m *machine) alloc(i *syntax.Inst) *thread {
@@ -59,9 +66,8 @@ func (m *machine) alloc(i *syntax.Inst) *thread {
 		m.pool = m.pool[:n-1]
 	} else {
 		t = new(thread)
-		t.cap = make([]int, cap(m.matchcap))
+		t.cap = make([]int, len(m.matchcap), cap(m.matchcap))
 	}
-	t.cap = t.cap[:len(m.matchcap)]
 	t.inst = i
 	return t
 }
@@ -121,7 +127,7 @@ func (m *machine) match(i input, pos int) bool {
 			if len(m.matchcap) > 0 {
 				m.matchcap[0] = pos
 			}
-			m.add(runq, uint32(m.p.Start), pos, m.matchcap, flag)
+			m.add(runq, uint32(m.p.Start), pos, m.matchcap, flag, nil)
 		}
 		flag = syntax.EmptyOpContext(rune, rune1)
 		m.step(runq, nextq, pos, pos+width, rune, flag)
@@ -148,7 +154,8 @@ func (m *machine) match(i input, pos int) bool {
 func (m *machine) clear(q *queue) {
 	for _, d := range q.dense {
 		if d.t != nil {
-			m.free(d.t)
+			// m.free(d.t)
+			m.pool = append(m.pool, d.t)
 		}
 	}
 	q.dense = q.dense[:0]
@@ -168,10 +175,12 @@ func (m *machine) step(runq, nextq *queue, pos, nextPos, c int, nextCond syntax.
 			continue
 		}
 		if longest && m.matched && len(t.cap) > 0 && m.matchcap[0] < t.cap[0] {
-			m.free(t)
+			// m.free(t)
+			m.pool = append(m.pool, t)
 			continue
 		}
 		i := t.inst
+		add := false
 		switch i.Op {
 		default:
 			panic("bad inst")
@@ -185,7 +194,8 @@ func (m *machine) step(runq, nextq *queue, pos, nextPos, c int, nextCond syntax.
 				// First-match mode: cut off all lower-priority threads.
 				for _, d := range runq.dense[j+1:] {
 					if d.t != nil {
-						m.free(d.t)
+						// m.free(d.t)
+						m.pool = append(m.pool, d.t)
 					}
 				}
 				runq.dense = runq.dense[:0]
@@ -193,11 +203,21 @@ func (m *machine) step(runq, nextq *queue, pos, nextPos, c int, nextCond syntax.
 			m.matched = true
 
 		case syntax.InstRune:
-			if i.MatchRune(c) {
-				m.add(nextq, i.Out, nextPos, t.cap, nextCond)
-			}
+			add = i.MatchRune(c)
+		case syntax.InstRune1:
+			add = c == i.Rune[0]
+		case syntax.InstRuneAny:
+			add = true
+		case syntax.InstRuneAnyNotNL:
+			add = c != '\n'
+		}
+		if add {
+			t = m.add(nextq, i.Out, nextPos, t.cap, nextCond, t)
+		}
+		if t != nil {
+			// m.free(t)
+			m.pool = append(m.pool, t)
 		}
-		m.free(t)
 	}
 	runq.dense = runq.dense[:0]
 }
@@ -206,12 +226,12 @@ func (m *machine) step(runq, nextq *queue, pos, nextPos, c int, nextCond syntax.
 // It also recursively adds an entry for all instructions reachable from pc by following
 // empty-width conditions satisfied by cond.  pos gives the current position
 // in the input.
-func (m *machine) add(q *queue, pc uint32, pos int, cap []int, cond syntax.EmptyOp) {
+func (m *machine) add(q *queue, pc uint32, pos int, cap []int, cond syntax.EmptyOp, t *thread) *thread {
 	if pc == 0 {
-		return
+		return t
 	}
 	if j := q.sparse[pc]; j < uint32(len(q.dense)) && q.dense[j].pc == pc {
-		return
+		return t
 	}
 
 	j := len(q.dense)
@@ -228,30 +248,36 @@ func (m *machine) add(q *queue, pc uint32, pos int, cap []int, cond syntax.Empty
 	case syntax.InstFail:
 		// nothing
 	case syntax.InstAlt, syntax.InstAltMatch:
-		m.add(q, i.Out, pos, cap, cond)
-		m.add(q, i.Arg, pos, cap, cond)
+		t = m.add(q, i.Out, pos, cap, cond, t)
+		t = m.add(q, i.Arg, pos, cap, cond, t)
 	case syntax.InstEmptyWidth:
 		if syntax.EmptyOp(i.Arg)&^cond == 0 {
-			m.add(q, i.Out, pos, cap, cond)
+			t = m.add(q, i.Out, pos, cap, cond, t)
 		}
 	case syntax.InstNop:
-		m.add(q, i.Out, pos, cap, cond)
+		t = m.add(q, i.Out, pos, cap, cond, t)
 	case syntax.InstCapture:
 		if int(i.Arg) < len(cap) {
 			opos := cap[i.Arg]
 			cap[i.Arg] = pos
-			m.add(q, i.Out, pos, cap, cond)
+			m.add(q, i.Out, pos, cap, cond, nil)
 			cap[i.Arg] = opos
 		} else {
-			m.add(q, i.Out, pos, cap, cond)
+			t = m.add(q, i.Out, pos, cap, cond, t)
+		}
+	case syntax.InstMatch, syntax.InstRune, syntax.InstRune1, syntax.InstRuneAny, syntax.InstRuneAnyNotNL:
+		if t == nil {
+			t = m.alloc(i)
+		} else {
+			t.inst = i
 		}
-	case syntax.InstMatch, syntax.InstRune:
-		t := m.alloc(i)
-		if len(t.cap) > 0 {
+		if len(cap) > 0 && &t.cap[0] != &cap[0] {
 			copy(t.cap, cap)
 		}
 		d.t = t
+		t = nil
 	}
+	return t
 }
 
 // empty is a non-nil 0-element slice,
@@ -263,7 +289,7 @@ var empty = make([]int, 0)
 // the position of its subexpressions.
 func (re *Regexp) doExecute(i input, pos int, ncap int) []int {
 	m := re.get()
-	m.matchcap = m.matchcap[:ncap]
+	m.init(ncap)
 	if !m.match(i, pos) {
 		re.put(m)
 		return nil

src/pkg/regexp/exec_test.go

@@ -9,8 +9,10 @@ import (
 	"compress/bzip2"
 	"fmt"
 	"io"
+	old "old/regexp"
 	"os"
 	"path/filepath"
+	"rand"
 	"regexp/syntax"
 	"strconv"
 	"strings"
@@ -647,3 +649,86 @@ func parseFowlerResult(s string) (ok, compiled, matched bool, pos []int) {
 	pos = x
 	return
 }
+
+var text []byte
+
+func makeText(n int) []byte {
+	if len(text) >= n {
+		return text[:n]
+	}
+	text = make([]byte, n)
+	for i := range text {
+		if rand.Intn(30) == 0 {
+			text[i] = '\n'
+		} else {
+			text[i] = byte(rand.Intn(0x7E+1-0x20) + 0x20)
+		}
+	}
+	return text
+}
+
+func benchmark(b *testing.B, re string, n int) {
+	r := MustCompile(re)
+	t := makeText(n)
+	b.ResetTimer()
+	b.SetBytes(int64(n))
+	for i := 0; i < b.N; i++ {
+		if r.Match(t) {
+			panic("match!")
+		}
+	}
+}
+
+func benchold(b *testing.B, re string, n int) {
+	r := old.MustCompile(re)
+	t := makeText(n)
+	b.ResetTimer()
+	b.SetBytes(int64(n))
+	for i := 0; i < b.N; i++ {
+		if r.Match(t) {
+			panic("match!")
+		}
+	}
+}
+
+const (
+	easy0  = "ABCDEFGHIJKLMNOPQRSTUVWXYZ$"
+	easy1  = "A[AB]B[BC]C[CD]D[DE]E[EF]F[FG]G[GH]H[HI]I[IJ]J$"
+	medium = "[XYZ]ABCDEFGHIJKLMNOPQRSTUVWXYZ$"
+	hard   = "[ -~]*ABCDEFGHIJKLMNOPQRSTUVWXYZ$"
+	parens = "([ -~])*(A)(B)(C)(D)(E)(F)(G)(H)(I)(J)(K)(L)(M)" +
+		"(N)(O)(P)(Q)(R)(S)(T)(U)(V)(W)(X)(Y)(Z)$"
+)
+
+func BenchmarkMatchEasy0_1K(b *testing.B)       { benchmark(b, easy0, 1<<10) }
+func BenchmarkMatchEasy0_1K_Old(b *testing.B)   { benchold(b, easy0, 1<<10) }
+func BenchmarkMatchEasy0_1M(b *testing.B)       { benchmark(b, easy0, 1<<20) }
+func BenchmarkMatchEasy0_1M_Old(b *testing.B)   { benchold(b, easy0, 1<<20) }
+func BenchmarkMatchEasy0_32K(b *testing.B)      { benchmark(b, easy0, 32<<10) }
+func BenchmarkMatchEasy0_32K_Old(b *testing.B)  { benchold(b, easy0, 32<<10) }
+func BenchmarkMatchEasy0_32M(b *testing.B)      { benchmark(b, easy0, 32<<20) }
+func BenchmarkMatchEasy0_32M_Old(b *testing.B)  { benchold(b, easy0, 32<<20) }
+func BenchmarkMatchEasy1_1K(b *testing.B)       { benchmark(b, easy1, 1<<10) }
+func BenchmarkMatchEasy1_1K_Old(b *testing.B)   { benchold(b, easy1, 1<<10) }
+func BenchmarkMatchEasy1_1M(b *testing.B)       { benchmark(b, easy1, 1<<20) }
+func BenchmarkMatchEasy1_1M_Old(b *testing.B)   { benchold(b, easy1, 1<<20) }
+func BenchmarkMatchEasy1_32K(b *testing.B)      { benchmark(b, easy1, 32<<10) }
+func BenchmarkMatchEasy1_32K_Old(b *testing.B)  { benchold(b, easy1, 32<<10) }
+func BenchmarkMatchEasy1_32M(b *testing.B)      { benchmark(b, easy1, 32<<20) }
+func BenchmarkMatchEasy1_32M_Old(b *testing.B)  { benchold(b, easy1, 32<<20) }
+func BenchmarkMatchMedium_1K(b *testing.B)      { benchmark(b, medium, 1<<10) }
+func BenchmarkMatchMedium_1K_Old(b *testing.B)  { benchold(b, medium, 1<<10) }
+func BenchmarkMatchMedium_1M(b *testing.B)      { benchmark(b, medium, 1<<20) }
+func BenchmarkMatchMedium_1M_Old(b *testing.B)  { benchold(b, medium, 1<<20) }
+func BenchmarkMatchMedium_32K(b *testing.B)     { benchmark(b, medium, 32<<10) }
+func BenchmarkMatchMedium_32K_Old(b *testing.B) { benchold(b, medium, 32<<10) }
+func BenchmarkMatchMedium_32M(b *testing.B)     { benchmark(b, medium, 32<<20) }
+func BenchmarkMatchMedium_32M_Old(b *testing.B) { benchold(b, medium, 32<<20) }
+func BenchmarkMatchHard_1K(b *testing.B)        { benchmark(b, hard, 1<<10) }
+func BenchmarkMatchHard_1K_Old(b *testing.B)    { benchold(b, hard, 1<<10) }
+func BenchmarkMatchHard_1M(b *testing.B)        { benchmark(b, hard, 1<<20) }
+func BenchmarkMatchHard_1M_Old(b *testing.B)    { benchold(b, hard, 1<<20) }
+func BenchmarkMatchHard_32K(b *testing.B)       { benchmark(b, hard, 32<<10) }
+func BenchmarkMatchHard_32K_Old(b *testing.B)   { benchold(b, hard, 32<<10) }
+func BenchmarkMatchHard_32M(b *testing.B)       { benchmark(b, hard, 32<<20) }
+func BenchmarkMatchHard_32M_Old(b *testing.B)   { benchold(b, hard, 32<<20) }

src/pkg/regexp/regexp.go

@@ -247,7 +247,11 @@ func newInputString(str string) *inputString {
 
 func (i *inputString) step(pos int) (int, int) {
 	if pos < len(i.str) {
-		return utf8.DecodeRuneInString(i.str[pos:len(i.str)])
+		c := i.str[pos]
+		if c < utf8.RuneSelf {
+			return int(c), 1
+		}
+		return utf8.DecodeRuneInString(i.str[pos:])
 	}
 	return endOfText, 0
 }
@@ -286,7 +290,11 @@ func newInputBytes(str []byte) *inputBytes {
 
 func (i *inputBytes) step(pos int) (int, int) {
 	if pos < len(i.str) {
-		return utf8.DecodeRune(i.str[pos:len(i.str)])
+		c := i.str[pos]
+		if c < utf8.RuneSelf {
+			return int(c), 1
+		}
+		return utf8.DecodeRune(i.str[pos:])
 	}
 	return endOfText, 0
 }

src/pkg/regexp/syntax/compile.go

@@ -273,5 +273,16 @@ func (c *compiler) rune(rune []int, flags Flags) frag {
 	}
 	i.Arg = uint32(flags)
 	f.out = patchList(f.i << 1)
+
+	// Special cases for exec machine.
+	switch {
+	case flags&FoldCase == 0 && (len(rune) == 1 || len(rune) == 2 && rune[0] == rune[1]):
+		i.Op = InstRune1
+	case len(rune) == 2 && rune[0] == 0 && rune[1] == unicode.MaxRune:
+		i.Op = InstRuneAny
+	case len(rune) == 4 && rune[0] == 0 && rune[1] == '\n'-1 && rune[2] == '\n'+1 && rune[3] == unicode.MaxRune:
+		i.Op = InstRuneAnyNotNL
+	}
+
 	return f
 }

src/pkg/regexp/syntax/prog.go

@@ -28,6 +28,9 @@ const (
 	InstFail
 	InstNop
 	InstRune
+	InstRune1
+	InstRuneAny
+	InstRuneAnyNotNL
 )
 
 // An EmptyOp specifies a kind or mixture of zero-width assertions.
@@ -102,6 +105,16 @@ func (p *Prog) skipNop(pc uint32) *Inst {
 	return i
 }
 
+// op returns i.Op but merges all the Rune special cases into InstRune
+func (i *Inst) op() InstOp {
+	op := i.Op
+	switch op {
+	case InstRune1, InstRuneAny, InstRuneAnyNotNL:
+		op = InstRune
+	}
+	return op
+}
+
 // Prefix returns a literal string that all matches for the
 // regexp must start with.  Complete is true if the prefix
 // is the entire match.
@@ -109,13 +122,13 @@ func (p *Prog) Prefix() (prefix string, complete bool) {
 	i := p.skipNop(uint32(p.Start))
 
 	// Avoid allocation of buffer if prefix is empty.
-	if i.Op != InstRune || len(i.Rune) != 1 {
+	if i.op() != InstRune || len(i.Rune) != 1 {
 		return "", i.Op == InstMatch
 	}
 
 	// Have prefix; gather characters.
 	var buf bytes.Buffer
-	for i.Op == InstRune && len(i.Rune) == 1 && Flags(i.Arg)&FoldCase == 0 {
+	for i.op() == InstRune && len(i.Rune) == 1 && Flags(i.Arg)&FoldCase == 0 {
 		buf.WriteRune(i.Rune[0])
 		i = p.skipNop(i.Out)
 	}
@@ -283,5 +296,11 @@ func dumpInst(b *bytes.Buffer, i *Inst) {
 			bw(b, "/i")
 		}
 		bw(b, " -> ", u32(i.Out))
+	case InstRune1:
+		bw(b, "rune1 ", strconv.QuoteToASCII(string(i.Rune)), " -> ", u32(i.Out))
+	case InstRuneAny:
+		bw(b, "any -> ", u32(i.Out))
+	case InstRuneAnyNotNL:
+		bw(b, "anynotnl -> ", u32(i.Out))
 	}
 }

src/pkg/regexp/syntax/prog_test.go

@@ -9,7 +9,7 @@ var compileTests = []struct {
 	Prog   string
 }{
 	{"a", `  0	fail
-  1*	rune "a" -> 2
+  1*	rune1 "a" -> 2
   2	match
 `},
 	{"[A-M][n-z]", `  0	fail
@@ -22,69 +22,69 @@ var compileTests = []struct {
   2	match
 `},
 	{"a?", `  0	fail
-  1	rune "a" -> 3
+  1	rune1 "a" -> 3
   2*	alt -> 1, 3
   3	match
 `},
 	{"a??", `  0	fail
-  1	rune "a" -> 3
+  1	rune1 "a" -> 3
   2*	alt -> 3, 1
   3	match
 `},
 	{"a+", `  0	fail
-  1*	rune "a" -> 2
+  1*	rune1 "a" -> 2
   2	alt -> 1, 3
   3	match
 `},
 	{"a+?", `  0	fail
-  1*	rune "a" -> 2
+  1*	rune1 "a" -> 2
   2	alt -> 3, 1
   3	match
 `},
 	{"a*", `  0	fail
-  1	rune "a" -> 2
+  1	rune1 "a" -> 2
   2*	alt -> 1, 3
   3	match
 `},
 	{"a*?", `  0	fail
-  1	rune "a" -> 2
+  1	rune1 "a" -> 2
   2*	alt -> 3, 1
   3	match
 `},
 	{"a+b+", `  0	fail
-  1*	rune "a" -> 2
+  1*	rune1 "a" -> 2
   2	alt -> 1, 3
-  3	rune "b" -> 4
+  3	rune1 "b" -> 4
   4	alt -> 3, 5
   5	match
 `},
 	{"(a+)(b+)", `  0	fail
   1*	cap 2 -> 2
-  2	rune "a" -> 3
+  2	rune1 "a" -> 3
   3	alt -> 2, 4
   4	cap 3 -> 5
   5	cap 4 -> 6
-  6	rune "b" -> 7
+  6	rune1 "b" -> 7
   7	alt -> 6, 8
   8	cap 5 -> 9
   9	match
 `},
 	{"a+|b+", `  0	fail
-  1	rune "a" -> 2
+  1	rune1 "a" -> 2
   2	alt -> 1, 6
-  3	rune "b" -> 4
+  3	rune1 "b" -> 4
   4	alt -> 3, 6
   5*	alt -> 1, 3
   6	match
 `},
 	{"A[Aa]", `  0	fail
-  1*	rune "A" -> 2
+  1*	rune1 "A" -> 2
   2	rune "A"/i -> 3
   3	match
 `},
 	{"(?:(?:^).)", `  0	fail
   1*	empty 4 -> 2
-  2	rune "\x00\t\v\U0010ffff" -> 3
+  2	anynotnl -> 3
   3	match
 `},
 }