From 9503bcae2b20d290332d00d78672881b7fcfedf0 Mon Sep 17 00:00:00 2001 From: Anuraag Agrawal Date: Fri, 10 Jun 2022 05:41:02 +0000 Subject: strings: reuse the input string for Repeat count of 1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The existing implementation allocates a new string even when the count is 1, where we know the output is the same as the input. While we wouldn't expect a count of 1 for hardcoded values of the parameter, it is expected when the parameter is computed based on a different value (e.g., the length of a input slice). name old time/op new time/op delta Repeat/5x0-10 2.03ns ± 0% 2.02ns ± 0% ~ (p=1.000 n=1+1) Repeat/5x1-10 13.7ns ± 0% 2.0ns ± 0% ~ (p=1.000 n=1+1) Repeat/5x2-10 18.2ns ± 0% 18.1ns ± 0% ~ (p=1.000 n=1+1) Repeat/5x6-10 27.0ns ± 0% 27.0ns ± 0% ~ (p=1.000 n=1+1) Repeat/10x0-10 2.02ns ± 0% 2.02ns ± 0% ~ (p=1.000 n=1+1) Repeat/10x1-10 16.1ns ± 0% 2.0ns ± 0% ~ (p=1.000 n=1+1) Repeat/10x2-10 20.8ns ± 0% 20.9ns ± 0% ~ (p=1.000 n=1+1) Repeat/10x6-10 29.2ns ± 0% 29.4ns ± 0% ~ (p=1.000 n=1+1) Change-Id: I48e08e08f8f6d6914d62b3d6a61d563d637bec59 GitHub-Last-Rev: 068f58e08b8f5c4105e7a210f242ca1ff3a61177 GitHub-Pull-Request: golang/go#53321 Reviewed-on: https://go-review.googlesource.com/c/go/+/411477 Reviewed-by: Ian Lance Taylor Run-TryBot: Ian Lance Taylor TryBot-Result: Gopher Robot Auto-Submit: Ian Lance Taylor Reviewed-by: Keith Randall --- src/strings/strings_test.go | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/strings/strings_test.go') diff --git a/src/strings/strings_test.go b/src/strings/strings_test.go index 8af81a556b..9323ff988d 100644 --- a/src/strings/strings_test.go +++ b/src/strings/strings_test.go @@ -1852,7 +1852,7 @@ func BenchmarkSplitNMultiByteSeparator(b *testing.B) { func BenchmarkRepeat(b *testing.B) { s := "0123456789" for _, n := range []int{5, 10} { - for _, c := range []int{1, 2, 6} { + for _, c := range []int{0, 1, 2, 6} { b.Run(fmt.Sprintf("%dx%d", n, c), func(b *testing.B) { for i := 0; i < b.N; i++ { Repeat(s[:n], c) -- cgit v1.3-5-g9baa