go/test/bench/go1: add regexp test

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7480047

test/bench/go1/regexp_test.go

@@ -0,0 +1,59 @@
+// Copyright 2013 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 go1
+
+import (
+	"math/rand"
+	"regexp"
+	"testing"
+)
+
+// benchmark based on regexp/exec_test.go
+
+var regexpText []byte
+
+func makeRegexpText(n int) []byte {
+	rand.Seed(0) // For reproducibility.
+	if len(regexpText) >= n {
+		return regexpText[:n]
+	}
+	regexpText = make([]byte, n)
+	for i := range regexpText {
+		if rand.Intn(30) == 0 {
+			regexpText[i] = '\n'
+		} else {
+			regexpText[i] = byte(rand.Intn(0x7E+1-0x20) + 0x20)
+		}
+	}
+	return regexpText
+}
+
+func benchmark(b *testing.B, re string, n int) {
+	r := regexp.MustCompile(re)
+	t := makeRegexpText(n)
+	b.ResetTimer()
+	b.SetBytes(int64(n))
+	for i := 0; i < b.N; i++ {
+		if r.Match(t) {
+			b.Fatal("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$"
+	hard   = "[ -~]*ABCDEFGHIJKLMNOPQRSTUVWXYZ$"
+)
+
+func BenchmarkRegexpMatchEasy0_32(b *testing.B)  { benchmark(b, easy0, 32<<0) }
+func BenchmarkRegexpMatchEasy0_1K(b *testing.B)  { benchmark(b, easy0, 1<<10) }
+func BenchmarkRegexpMatchEasy1_32(b *testing.B)  { benchmark(b, easy1, 32<<0) }
+func BenchmarkRegexpMatchEasy1_1K(b *testing.B)  { benchmark(b, easy1, 1<<10) }
+func BenchmarkRegexpMatchMedium_32(b *testing.B) { benchmark(b, medium, 1<<0) }
+func BenchmarkRegexpMatchMedium_1K(b *testing.B) { benchmark(b, medium, 1<<10) }
+func BenchmarkRegexpMatchHard_32(b *testing.B)   { benchmark(b, hard, 32<<0) }
+func BenchmarkRegexpMatchHard_1K(b *testing.B)   { benchmark(b, hard, 1<<10) }