From 0d9981bccb0e9783b25491c9395702ca099a11e3 Mon Sep 17 00:00:00 2001 From: Emmanuel T Odeke Date: Thu, 19 Sep 2019 23:35:34 -0700 Subject: [PATCH] debug/dwarf: optimize buf.string MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit (*buf).string previously manually searched through its underlying byte slice until we encountered a '0'. This change instead uses bytes.IndexByte that results in a speed up: $ benchstat before.txt after.txt name old time/op new time/op delta BufString-8 257ns ± 1% 174ns ± 1% -32.37% (p=0.000 n=9+8) name old speed new speed delta BufString-8 495MB/s ± 1% 732MB/s ± 1% +47.76% (p=0.000 n=10+8) name old alloc/op new alloc/op delta BufString-8 162B ± 0% 162B ± 0% ~ (all equal) name old allocs/op new allocs/op delta BufString-8 3.00 ± 0% 3.00 ± 0% ~ (all equal) Change-Id: I7cf241742cc091d5d30d987a168b02d83955b1cf Reviewed-on: https://go-review.googlesource.com/c/go/+/196657 Run-TryBot: Emmanuel Odeke TryBot-Result: Gobot Gobot Reviewed-by: Tobias Klauser --- src/debug/dwarf/buf.go | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/src/debug/dwarf/buf.go b/src/debug/dwarf/buf.go index 3e6ce293fd..c3822a0dac 100644 --- a/src/debug/dwarf/buf.go +++ b/src/debug/dwarf/buf.go @@ -7,6 +7,7 @@ package dwarf import ( + "bytes" "encoding/binary" "strconv" ) @@ -79,16 +80,16 @@ func (b *buf) bytes(n int) []byte { func (b *buf) skip(n int) { b.bytes(n) } func (b *buf) string() string { - for i := 0; i < len(b.data); i++ { - if b.data[i] == 0 { - s := string(b.data[0:i]) - b.data = b.data[i+1:] - b.off += Offset(i + 1) - return s - } + i := bytes.IndexByte(b.data, 0) + if i < 0 { + b.error("underflow") + return "" } - b.error("underflow") - return "" + + s := string(b.data[0:i]) + b.data = b.data[i+1:] + b.off += Offset(i + 1) + return s } func (b *buf) uint16() uint16 { -- 2.48.1