bytes, internal/bytealg: simplify Equal

The compiler has advanced enough that it is cheaper
to convert to strings than to go through the assembly
trampolines to call runtime.memequal.

Simplify Equal accordingly, and cull dead code from bytealg.

While we're here, simplify Equal's documentation.

Fixes #31587

Change-Id: Ie721d33f9a6cbd86b1d873398b20e7882c2c63e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/173323
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 10 insertions, 13 deletions

diff --git a/src/bytes/bytes_test.go b/src/bytes/bytes_test.go
index 340810facf..4c50755e7c 100644
--- a/src/bytes/bytes_test.go
+++ b/src/bytes/bytes_test.go
@@ -51,15 +51,17 @@ type BinOpTest struct {
 }
 
 func TestEqual(t *testing.T) {
-	for _, tt := range compareTests {
-		eql := Equal(tt.a, tt.b)
-		if eql != (tt.i == 0) {
-			t.Errorf(`Equal(%q, %q) = %v`, tt.a, tt.b, eql)
-		}
-		eql = EqualPortable(tt.a, tt.b)
-		if eql != (tt.i == 0) {
-			t.Errorf(`EqualPortable(%q, %q) = %v`, tt.a, tt.b, eql)
+	// Run the tests and check for allocation at the same time.
+	allocs := testing.AllocsPerRun(10, func() {
+		for _, tt := range compareTests {
+			eql := Equal(tt.a, tt.b)
+			if eql != (tt.i == 0) {
+				t.Errorf(`Equal(%q, %q) = %v`, tt.a, tt.b, eql)
+			}
 		}
+	})
+	if allocs > 0 {
+		t.Errorf("Equal allocated %v times", allocs)
 	}
 }
 
@@ -572,11 +574,6 @@ func BenchmarkEqual(b *testing.B) {
 	benchBytes(b, sizes, bmEqual(Equal))
 }
 
-func BenchmarkEqualPort(b *testing.B) {
-	sizes := []int{1, 6, 32, 4 << 10, 4 << 20, 64 << 20}
-	benchBytes(b, sizes, bmEqual(EqualPortable))
-}
-
 func bmEqual(equal func([]byte, []byte) bool) func(b *testing.B, n int) {
 	return func(b *testing.B, n int) {
 		if len(bmbuf) < 2*n {