internal/bytealg: move Count to bytealg

Move bytes.Count and strings.Count to bytealg.

Update #19792

Change-Id: I3e4e14b504a0b71758885bb131e5656e342cf8cb
Reviewed-on: https://go-review.googlesource.com/98495
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

7 files changed, 7 insertions, 41 deletions

diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
index 9af177fa88..08d8260e9e 100644
--- a/src/bytes/bytes.go
+++ b/src/bytes/bytes.go
@@ -7,6 +7,7 @@
 package bytes
 
 import (
+	"internal/bytealg"
 	"unicode"
 	"unicode/utf8"
 )
@@ -46,12 +47,16 @@ func explode(s []byte, n int) [][]byte {
 	return a[0:na]
 }
 
-// countGeneric actually implements Count
-func countGeneric(s, sep []byte) int {
+// Count counts the number of non-overlapping instances of sep in s.
+// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
+func Count(s, sep []byte) int {
 	// special case
 	if len(sep) == 0 {
 		return utf8.RuneCount(s) + 1
 	}
+	if len(sep) == 1 {
+		return bytealg.Count(s, sep[0])
+	}
 	n := 0
 	for {
 		i := Index(s, sep)
diff --git a/src/bytes/bytes_amd64.go b/src/bytes/bytes_amd64.go
index 0c9d613ef9..2fc88c68fc 100644
--- a/src/bytes/bytes_amd64.go
+++ b/src/bytes/bytes_amd64.go
@@ -77,12 +77,3 @@ func Index(s, sep []byte) int {
 	}
 	return indexRabinKarp(s, sep)
 }
-
-// Count counts the number of non-overlapping instances of sep in s.
-// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
-func Count(s, sep []byte) int {
-	if len(sep) == 1 && cpu.X86.HasPOPCNT {
-		return countByte(s, sep[0])
-	}
-	return countGeneric(s, sep)
-}
diff --git a/src/bytes/bytes_arm64.go b/src/bytes/bytes_arm64.go
index 3d9ed3dd22..39e9562db1 100644
--- a/src/bytes/bytes_arm64.go
+++ b/src/bytes/bytes_arm64.go
@@ -70,12 +70,3 @@ func Index(s, sep []byte) int {
 	}
 	return -1
 }
-
-// Count counts the number of non-overlapping instances of sep in s.
-// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
-func Count(s, sep []byte) int {
-	if len(sep) == 1 {
-		return countByte(s, sep[0])
-	}
-	return countGeneric(s, sep)
-}
diff --git a/src/bytes/bytes_generic.go b/src/bytes/bytes_generic.go
index 0e7d33f09a..347d28473f 100644
--- a/src/bytes/bytes_generic.go
+++ b/src/bytes/bytes_generic.go
@@ -57,9 +57,3 @@ func Index(s, sep []byte) int {
 	}
 	return -1
 }
-
-// Count counts the number of non-overlapping instances of sep in s.
-// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
-func Count(s, sep []byte) int {
-	return countGeneric(s, sep)
-}
diff --git a/src/bytes/bytes_s390x.go b/src/bytes/bytes_s390x.go
index c59b891292..84f040d43d 100644
--- a/src/bytes/bytes_s390x.go
+++ b/src/bytes/bytes_s390x.go
@@ -78,9 +78,3 @@ func Index(s, sep []byte) int {
 	}
 	return indexRabinKarp(s, sep)
 }
-
-// Count counts the number of non-overlapping instances of sep in s.
-// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
-func Count(s, sep []byte) int {
-	return countGeneric(s, sep)
-}
diff --git a/src/bytes/bytes_test.go b/src/bytes/bytes_test.go
index 1e56571c73..55a22bae22 100644
--- a/src/bytes/bytes_test.go
+++ b/src/bytes/bytes_test.go
@@ -410,10 +410,6 @@ func TestCountByte(t *testing.T) {
 			if p != j+1 {
 				t.Errorf("TestCountByte.Count(%q, 100) = %d", b[i:i+window], p)
 			}
-			pGeneric := CountGeneric(b[i:i+window], []byte{100})
-			if pGeneric != j+1 {
-				t.Errorf("TestCountByte.CountGeneric(%q, 100) = %d", b[i:i+window], p)
-			}
 		}
 	}
 
@@ -461,10 +457,6 @@ func TestCountByteNoMatch(t *testing.T) {
 			if p != 0 {
 				t.Errorf("TestCountByteNoMatch(%q, 0) = %d", b[i:i+window], p)
 			}
-			pGeneric := CountGeneric(b[i:i+window], []byte{0})
-			if pGeneric != 0 {
-				t.Errorf("TestCountByteNoMatch.CountGeneric(%q, 100) = %d", b[i:i+window], p)
-			}
 			for j := 0; j < window; j++ {
 				b[i+j] = byte(0)
 			}
diff --git a/src/bytes/export_test.go b/src/bytes/export_test.go
index 823c8b09ee..f61523e60b 100644
--- a/src/bytes/export_test.go
+++ b/src/bytes/export_test.go
@@ -7,4 +7,3 @@ package bytes
 // Export func for testing
 var IndexBytePortable = indexBytePortable
 var EqualPortable = equalPortable
-var CountGeneric = countGeneric