libgo: update to Go 1.13beta1 release

    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/193497

From-SVN: r275473

8 files changed, 116 insertions, 22 deletions

diff --git a/libgo/go/regexp/all_test.go b/libgo/go/regexp/all_test.go
index 623f82d..626a691 100644
--- a/libgo/go/regexp/all_test.go
+++ b/libgo/go/regexp/all_test.go
@@ -860,6 +860,25 @@ func BenchmarkQuoteMetaNone(b *testing.B) {
 	}
 }
 
+var compileBenchData = []struct{ name, re string }{
+	{"Onepass", `^a.[l-nA-Cg-j]?e$`},
+	{"Medium", `^((a|b|[d-z0-9])*(日){4,5}.)+$`},
+	{"Hard", strings.Repeat(`((abc)*|`, 50) + strings.Repeat(`)`, 50)},
+}
+
+func BenchmarkCompile(b *testing.B) {
+	for _, data := range compileBenchData {
+		b.Run(data.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				if _, err := Compile(data.re); err != nil {
+					b.Fatal(err)
+				}
+			}
+		})
+	}
+}
+
 func TestDeepEqual(t *testing.T) {
 	re1 := MustCompile("a.*b.*c.*d")
 	re2 := MustCompile("a.*b.*c.*d")
@@ -882,3 +901,31 @@ func TestDeepEqual(t *testing.T) {
 		t.Errorf("DeepEqual(re1, re2) = false, want true")
 	}
 }
+
+var minInputLenTests = []struct {
+	Regexp string
+	min    int
+}{
+	{``, 0},
+	{`a`, 1},
+	{`aa`, 2},
+	{`(aa)a`, 3},
+	{`(?:aa)a`, 3},
+	{`a?a`, 1},
+	{`(aaa)|(aa)`, 2},
+	{`(aa)+a`, 3},
+	{`(aa)*a`, 1},
+	{`(aa){3,5}`, 6},
+	{`[a-z]`, 1},
+	{`日`, 3},
+}
+
+func TestMinInputLen(t *testing.T) {
+	for _, tt := range minInputLenTests {
+		re, _ := syntax.Parse(tt.Regexp, syntax.Perl)
+		m := minInputLen(re)
+		if m != tt.min {
+			t.Errorf("regexp %#q has minInputLen %d, should be %d", tt.Regexp, m, tt.min)
+		}
+	}
+}
diff --git a/libgo/go/regexp/exec.go b/libgo/go/regexp/exec.go
index efe764e..4411e4c 100644
--- a/libgo/go/regexp/exec.go
+++ b/libgo/go/regexp/exec.go
@@ -524,6 +524,10 @@ func (re *Regexp) doExecute(r io.RuneReader, b []byte, s string, pos int, ncap i
 		dstCap = arrayNoInts[:0:0]
 	}
 
+	if r == nil && len(b)+len(s) < re.minInputLen {
+		return nil
+	}
+
 	if re.onepass != nil {
 		return re.doOnePass(r, b, s, pos, ncap, dstCap)
 	}
diff --git a/libgo/go/regexp/exec_test.go b/libgo/go/regexp/exec_test.go
index 1489219..1e87955 100644
--- a/libgo/go/regexp/exec_test.go
+++ b/libgo/go/regexp/exec_test.go
@@ -717,6 +717,7 @@ var benchSizes = []struct {
 	name string
 	n    int
 }{
+	{"16", 16},
 	{"32", 32},
 	{"1K", 1 << 10},
 	{"32K", 32 << 10},
diff --git a/libgo/go/regexp/find_test.go b/libgo/go/regexp/find_test.go
index e07eb7d..87c49b0 100644
--- a/libgo/go/regexp/find_test.go
+++ b/libgo/go/regexp/find_test.go
@@ -161,6 +161,9 @@ func TestFind(t *testing.T) {
 			t.Errorf("expected match; got none: %s", test)
 		case test.matches != nil && result != nil:
 			expect := test.text[test.matches[0][0]:test.matches[0][1]]
+			if len(result) != cap(result) {
+				t.Errorf("expected capacity %d got %d: %s", len(result), cap(result), test)
+			}
 			if expect != string(result) {
 				t.Errorf("expected %q got %q: %s", expect, result, test)
 			}
@@ -242,9 +245,13 @@ func TestFindAll(t *testing.T) {
 				continue
 			}
 			for k, e := range test.matches {
+				got := result[k]
+				if len(got) != cap(got) {
+					t.Errorf("match %d: expected capacity %d got %d: %s", k, len(got), cap(got), test)
+				}
 				expect := test.text[e[0]:e[1]]
-				if expect != string(result[k]) {
-					t.Errorf("match %d: expected %q got %q: %s", k, expect, result[k], test)
+				if expect != string(got) {
+					t.Errorf("match %d: expected %q got %q: %s", k, expect, got, test)
 				}
 			}
 		}
@@ -323,9 +330,14 @@ func testSubmatchBytes(test *FindTest, n int, submatches []int, result [][]byte,
 			}
 			continue
 		}
+		got := result[k/2]
+		if len(got) != cap(got) {
+			t.Errorf("match %d: expected capacity %d got %d: %s", n, len(got), cap(got), test)
+			return
+		}
 		expect := test.text[submatches[k]:submatches[k+1]]
-		if expect != string(result[k/2]) {
-			t.Errorf("match %d: expected %q got %q: %s", n, expect, result, test)
+		if expect != string(got) {
+			t.Errorf("match %d: expected %q got %q: %s", n, expect, got, test)
 			return
 		}
 	}
diff --git a/libgo/go/regexp/onepass_test.go b/libgo/go/regexp/onepass_test.go
index a0f2e39..32264d5 100644
--- a/libgo/go/regexp/onepass_test.go
+++ b/libgo/go/regexp/onepass_test.go
@@ -223,13 +223,3 @@ func TestRunOnePass(t *testing.T) {
 		}
 	}
 }
-
-func BenchmarkCompileOnepass(b *testing.B) {
-	b.ReportAllocs()
-	const re = `^a.[l-nA-Cg-j]?e$`
-	for i := 0; i < b.N; i++ {
-		if _, err := Compile(re); err != nil {
-			b.Fatal(err)
-		}
-	}
-}
diff --git a/libgo/go/regexp/regexp.go b/libgo/go/regexp/regexp.go
index 38b3c86..19ca6f2 100644
--- a/libgo/go/regexp/regexp.go
+++ b/libgo/go/regexp/regexp.go
@@ -46,9 +46,10 @@
 // If 'Index' is present, matches and submatches are identified by byte index
 // pairs within the input string: result[2*n:2*n+1] identifies the indexes of
 // the nth submatch. The pair for n==0 identifies the match of the entire
-// expression. If 'Index' is not present, the match is identified by the
-// text of the match/submatch. If an index is negative, it means that
-// subexpression did not match any string in the input.
+// expression. If 'Index' is not present, the match is identified by the text
+// of the match/submatch. If an index is negative or text is nil, it means that
+// subexpression did not match any string in the input. For 'String' versions
+// an empty string means either no match or an empty match.
 //
 // There is also a subset of the methods that can be applied to text read
 // from a RuneReader:
@@ -93,6 +94,7 @@ type Regexp struct {
 	matchcap       int            // size of recorded match lengths
 	prefixComplete bool           // prefix is the entire regexp
 	cond           syntax.EmptyOp // empty-width conditions required at start of match
+	minInputLen    int            // minimum length of the input in bytes
 
 	// This field can be modified by the Longest method,
 	// but it is otherwise read-only.
@@ -190,6 +192,7 @@ func compile(expr string, mode syntax.Flags, longest bool) (*Regexp, error) {
 		cond:        prog.StartCond(),
 		longest:     longest,
 		matchcap:    matchcap,
+		minInputLen: minInputLen(re),
 	}
 	if regexp.onepass == nil {
 		regexp.prefix, regexp.prefixComplete = prog.Prefix()
@@ -263,6 +266,42 @@ func (re *Regexp) put(m *machine) {
 	matchPool[re.mpool].Put(m)
 }
 
+// minInputLen walks the regexp to find the minimum length of any matchable input
+func minInputLen(re *syntax.Regexp) int {
+	switch re.Op {
+	default:
+		return 0
+	case syntax.OpAnyChar, syntax.OpAnyCharNotNL, syntax.OpCharClass:
+		return 1
+	case syntax.OpLiteral:
+		l := 0
+		for _, r := range re.Rune {
+			l += utf8.RuneLen(r)
+		}
+		return l
+	case syntax.OpCapture, syntax.OpPlus:
+		return minInputLen(re.Sub[0])
+	case syntax.OpRepeat:
+		return re.Min * minInputLen(re.Sub[0])
+	case syntax.OpConcat:
+		l := 0
+		for _, sub := range re.Sub {
+			l += minInputLen(sub)
+		}
+		return l
+	case syntax.OpAlternate:
+		l := minInputLen(re.Sub[0])
+		var lnext int
+		for _, sub := range re.Sub[1:] {
+			lnext = minInputLen(sub)
+			if lnext < l {
+				l = lnext
+			}
+		}
+		return l
+	}
+}
+
 // MustCompile is like Compile but panics if the expression cannot be parsed.
 // It simplifies safe initialization of global variables holding compiled regular
 // expressions.
@@ -761,7 +800,7 @@ func (re *Regexp) Find(b []byte) []byte {
 	if a == nil {
 		return nil
 	}
-	return b[a[0]:a[1]]
+	return b[a[0]:a[1]:a[1]]
 }
 
 // FindIndex returns a two-element slice of integers defining the location of
@@ -829,7 +868,7 @@ func (re *Regexp) FindSubmatch(b []byte) [][]byte {
 	ret := make([][]byte, 1+re.numSubexp)
 	for i := range ret {
 		if 2*i < len(a) && a[2*i] >= 0 {
-			ret[i] = b[a[2*i]:a[2*i+1]]
+			ret[i] = b[a[2*i]:a[2*i+1]:a[2*i+1]]
 		}
 	}
 	return ret
@@ -1025,7 +1064,7 @@ func (re *Regexp) FindAll(b []byte, n int) [][]byte {
 		if result == nil {
 			result = make([][]byte, 0, startSize)
 		}
-		result = append(result, b[match[0]:match[1]])
+		result = append(result, b[match[0]:match[1]:match[1]])
 	})
 	return result
 }
@@ -1100,7 +1139,7 @@ func (re *Regexp) FindAllSubmatch(b []byte, n int) [][][]byte {
 		slice := make([][]byte, len(match)/2)
 		for j := range slice {
 			if match[2*j] >= 0 {
-				slice[j] = b[match[2*j]:match[2*j+1]]
+				slice[j] = b[match[2*j]:match[2*j+1]:match[2*j+1]]
 			}
 		}
 		result = append(result, slice)
diff --git a/libgo/go/regexp/syntax/parse_test.go b/libgo/go/regexp/syntax/parse_test.go
index fe3d251..5581ba1 100644
--- a/libgo/go/regexp/syntax/parse_test.go
+++ b/libgo/go/regexp/syntax/parse_test.go
@@ -185,6 +185,7 @@ var parseTests = []parseTest{
 	{`(?-s).`, `dnl{}`},
 	{`(?:(?:^).)`, `cat{bol{}dot{}}`},
 	{`(?-s)(?:(?:^).)`, `cat{bol{}dnl{}}`},
+	{`[\s\S]a`, `cat{cc{0x0-0x10ffff}lit{a}}`},
 
 	// RE2 prefix_tests
 	{`abc|abd`, `cat{str{ab}cc{0x63-0x64}}`},
diff --git a/libgo/go/regexp/syntax/regexp.go b/libgo/go/regexp/syntax/regexp.go
index ae5fa05..3a4d2d2 100644
--- a/libgo/go/regexp/syntax/regexp.go
+++ b/libgo/go/regexp/syntax/regexp.go
@@ -139,7 +139,7 @@ func writeRegexp(b *strings.Builder, re *Regexp) {
 		b.WriteRune('[')
 		if len(re.Rune) == 0 {
 			b.WriteString(`^\x00-\x{10FFFF}`)
-		} else if re.Rune[0] == 0 && re.Rune[len(re.Rune)-1] == unicode.MaxRune {
+		} else if re.Rune[0] == 0 && re.Rune[len(re.Rune)-1] == unicode.MaxRune && len(re.Rune) > 2 {
 			// Contains 0 and MaxRune. Probably a negated class.
 			// Print the gaps.
 			b.WriteRune('^')