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-rw-r--r--src/strings/strings.go79
-rw-r--r--src/strings/strings_amd64.go79
-rw-r--r--src/strings/strings_generic.go55
-rw-r--r--src/strings/strings_s390x.go80
4 files changed, 79 insertions, 214 deletions
diff --git a/src/strings/strings.go b/src/strings/strings.go
index 7d3ed37edd..b0a53fdefd 100644
--- a/src/strings/strings.go
+++ b/src/strings/strings.go
@@ -932,6 +932,85 @@ func EqualFold(s, t string) bool {
return s == t
}
+// Index returns the index of the first instance of substr in s, or -1 if substr is not present in s.
+func Index(s, substr string) int {
+ n := len(substr)
+ switch {
+ case n == 0:
+ return 0
+ case n == 1:
+ return IndexByte(s, substr[0])
+ case n == len(s):
+ if substr == s {
+ return 0
+ }
+ return -1
+ case n > len(s):
+ return -1
+ case n <= bytealg.MaxLen:
+ // Use brute force when s and substr both are small
+ if len(s) <= bytealg.MaxBruteForce {
+ return bytealg.IndexString(s, substr)
+ }
+ c := substr[0]
+ i := 0
+ t := s[:len(s)-n+1]
+ fails := 0
+ for i < len(t) {
+ if t[i] != c {
+ // IndexByte is faster than bytealg.IndexString, so use it as long as
+ // we're not getting lots of false positives.
+ o := IndexByte(t[i:], c)
+ if o < 0 {
+ return -1
+ }
+ i += o
+ }
+ if s[i:i+n] == substr {
+ return i
+ }
+ fails++
+ i++
+ // Switch to bytealg.IndexString when IndexByte produces too many false positives.
+ if fails > bytealg.Cutover(i) {
+ r := bytealg.IndexString(s[i:], substr)
+ if r >= 0 {
+ return r + i
+ }
+ return -1
+ }
+ }
+ return -1
+ }
+ c := substr[0]
+ i := 0
+ t := s[:len(s)-n+1]
+ fails := 0
+ for i < len(t) {
+ if t[i] != c {
+ o := IndexByte(t[i:], c)
+ if o < 0 {
+ return -1
+ }
+ i += o
+ }
+ if s[i:i+n] == substr {
+ return i
+ }
+ i++
+ fails++
+ if fails >= 4+i>>4 && i < len(t) {
+ // See comment in ../bytes/bytes_generic.go.
+ j := indexRabinKarp(s[i:], substr)
+ if j < 0 {
+ return -1
+ }
+ return i + j
+ }
+ }
+ return -1
+}
+
func indexRabinKarp(s, substr string) int {
// Rabin-Karp search
hashss, pow := hashStr(substr)
diff --git a/src/strings/strings_amd64.go b/src/strings/strings_amd64.go
deleted file mode 100644
index 75e7d0c139..0000000000
--- a/src/strings/strings_amd64.go
+++ /dev/null
@@ -1,79 +0,0 @@
-// Copyright 2015 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 strings
-
-import "internal/cpu"
-
-//go:noescape
-
-// indexShortStr returns the index of the first instance of c in s, or -1 if c is not present in s.
-// indexShortStr requires 2 <= len(c) <= shortStringLen
-func indexShortStr(s, c string) int // ../runtime/asm_amd64.s
-func countByte(s string, c byte) int // ../runtime/asm_amd64.s
-
-var shortStringLen int
-
-func init() {
- if cpu.X86.HasAVX2 {
- shortStringLen = 63
- } else {
- shortStringLen = 31
- }
-}
-
-// Index returns the index of the first instance of substr in s, or -1 if substr is not present in s.
-func Index(s, substr string) int {
- n := len(substr)
- switch {
- case n == 0:
- return 0
- case n == 1:
- return IndexByte(s, substr[0])
- case n == len(s):
- if substr == s {
- return 0
- }
- return -1
- case n > len(s):
- return -1
- case n <= shortStringLen:
- // Use brute force when s and substr both are small
- if len(s) <= 64 {
- return indexShortStr(s, substr)
- }
- c := substr[0]
- i := 0
- t := s[:len(s)-n+1]
- fails := 0
- for i < len(t) {
- if t[i] != c {
- // IndexByte skips 16/32 bytes per iteration,
- // so it's faster than indexShortStr.
- o := IndexByte(t[i:], c)
- if o < 0 {
- return -1
- }
- i += o
- }
- if s[i:i+n] == substr {
- return i
- }
- fails++
- i++
- // Switch to indexShortStr when IndexByte produces too many false positives.
- // Too many means more that 1 error per 8 characters.
- // Allow some errors in the beginning.
- if fails > (i+16)/8 {
- r := indexShortStr(s[i:], substr)
- if r >= 0 {
- return r + i
- }
- return -1
- }
- }
- return -1
- }
- return indexRabinKarp(s, substr)
-}
diff --git a/src/strings/strings_generic.go b/src/strings/strings_generic.go
deleted file mode 100644
index ac3b8dce85..0000000000
--- a/src/strings/strings_generic.go
+++ /dev/null
@@ -1,55 +0,0 @@
-// Copyright 2015 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.
-
-// +build !amd64,!s390x
-
-package strings
-
-// TODO: implements short string optimization on non amd64 platforms
-// and get rid of strings_amd64.go
-
-// Index returns the index of the first instance of substr in s, or -1 if substr is not present in s.
-func Index(s, substr string) int {
- n := len(substr)
- switch {
- case n == 0:
- return 0
- case n == 1:
- return IndexByte(s, substr[0])
- case n == len(s):
- if substr == s {
- return 0
- }
- return -1
- case n > len(s):
- return -1
- }
- c := substr[0]
- i := 0
- t := s[:len(s)-n+1]
- fails := 0
- for i < len(t) {
- if t[i] != c {
- o := IndexByte(t[i:], c)
- if o < 0 {
- return -1
- }
- i += o
- }
- if s[i:i+n] == substr {
- return i
- }
- i++
- fails++
- if fails >= 4+i>>4 && i < len(t) {
- // See comment in ../bytes/bytes_generic.go.
- j := indexRabinKarp(s[i:], substr)
- if j < 0 {
- return -1
- }
- return i + j
- }
- }
- return -1
-}
diff --git a/src/strings/strings_s390x.go b/src/strings/strings_s390x.go
deleted file mode 100644
index b2e459b04e..0000000000
--- a/src/strings/strings_s390x.go
+++ /dev/null
@@ -1,80 +0,0 @@
-// Copyright 2016 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 strings
-
-//go:noescape
-
-// indexShortStr returns the index of the first instance of sep in s,
-// or -1 if sep is not present in s.
-// indexShortStr requires 2 <= len(sep) <= shortStringLen
-func indexShortStr(s, sep string) int // ../runtime/asm_$GOARCH.s
-
-// supportsVX reports whether the vector facility is available.
-// indexShortStr must not be called if the vector facility is not
-// available.
-func supportsVX() bool // ../runtime/asm_s390x.s
-
-var shortStringLen = -1
-
-func init() {
- if supportsVX() {
- shortStringLen = 64
- }
-}
-
-// Index returns the index of the first instance of substr in s, or -1 if substr is not present in s.
-func Index(s, substr string) int {
- n := len(substr)
- switch {
- case n == 0:
- return 0
- case n == 1:
- return IndexByte(s, substr[0])
- case n == len(s):
- if substr == s {
- return 0
- }
- return -1
- case n > len(s):
- return -1
- case n <= shortStringLen:
- // Use brute force when s and substr both are small
- if len(s) <= 64 {
- return indexShortStr(s, substr)
- }
- c := substr[0]
- i := 0
- t := s[:len(s)-n+1]
- fails := 0
- for i < len(t) {
- if t[i] != c {
- // IndexByte skips 16/32 bytes per iteration,
- // so it's faster than indexShortStr.
- o := IndexByte(t[i:], c)
- if o < 0 {
- return -1
- }
- i += o
- }
- if s[i:i+n] == substr {
- return i
- }
- fails++
- i++
- // Switch to indexShortStr when IndexByte produces too many false positives.
- // Too many means more that 1 error per 8 characters.
- // Allow some errors in the beginning.
- if fails > (i+16)/8 {
- r := indexShortStr(s[i:], substr)
- if r >= 0 {
- return r + i
- }
- return -1
- }
- }
- return -1
- }
- return indexRabinKarp(s, substr)
-}
generated by cgit v1.3 (git 2.53.0) at 2026-04-15 19:28:46 +0000