internal/bytealg: move short string Index implementations into bytealg

Also move the arm64 CountByte implementation while we're here.

Fixes #19792

Change-Id: I1e0fdf1e03e3135af84150a2703b58dad1b0d57e
Reviewed-on: https://go-review.googlesource.com/98518
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 0 insertions, 59 deletions

diff --git a/src/bytes/bytes_generic.go b/src/bytes/bytes_generic.go
deleted file mode 100644
index 347d28473f..0000000000
--- a/src/bytes/bytes_generic.go
+++ /dev/null
@@ -1,59 +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,!arm64
-
-package bytes
-
-// Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
-func Index(s, sep []byte) int {
-	n := len(sep)
-	switch {
-	case n == 0:
-		return 0
-	case n == 1:
-		return IndexByte(s, sep[0])
-	case n == len(s):
-		if Equal(sep, s) {
-			return 0
-		}
-		return -1
-	case n > len(s):
-		return -1
-	}
-	c := sep[0]
-	i := 0
-	fails := 0
-	t := s[:len(s)-n+1]
-	for i < len(t) {
-		if t[i] != c {
-			o := IndexByte(t[i:], c)
-			if o < 0 {
-				break
-			}
-			i += o
-		}
-		if Equal(s[i:i+n], sep) {
-			return i
-		}
-		i++
-		fails++
-		if fails >= 4+i>>4 && i < len(t) {
-			// Give up on IndexByte, it isn't skipping ahead
-			// far enough to be better than Rabin-Karp.
-			// Experiments (using IndexPeriodic) suggest
-			// the cutover is about 16 byte skips.
-			// TODO: if large prefixes of sep are matching
-			// we should cutover at even larger average skips,
-			// because Equal becomes that much more expensive.
-			// This code does not take that effect into account.
-			j := indexRabinKarp(s[i:], sep)
-			if j < 0 {
-				return -1
-			}
-			return i + j
-		}
-	}
-	return -1
-}