From 3466e57354974cd2d17ce902df02e0ac58b8ded5 Mon Sep 17 00:00:00 2001 From: thepudds Date: Wed, 21 Jun 2023 14:35:53 -0400 Subject: [PATCH] fmt: avoid reflect.Value.Slice to help escape analysis This is part of a series of CLs that aim to reduce how often interface arguments escape for the print functions in fmt. Prior to this change, one reason arguments escape is because printValue calls reflect.Value.Slice, which causes its value argument to escape (though at this CL, that is shrouded in the fmt escape analysis logs by other printValue escape reasons). This CL avoids that usage by calling f.Bytes instead, which is possible because we know f is a slice of bytes or an addressable array of bytes. Arguments still escape for other reasons. Change-Id: Ic3f064117a364007e1dd3197cef9d641abbf784a Reviewed-on: https://go-review.googlesource.com/c/go/+/524940 TryBot-Result: Gopher Robot Reviewed-by: Ian Lance Taylor Reviewed-by: Matthew Dempsky Auto-Submit: Ian Lance Taylor Run-TryBot: t hepudds --- src/fmt/print.go | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/src/fmt/print.go b/src/fmt/print.go index 9225e2e28c..9c8e331118 100644 --- a/src/fmt/print.go +++ b/src/fmt/print.go @@ -872,10 +872,8 @@ func (p *pp) printValue(value reflect.Value, verb rune, depth int) { t := f.Type() if t.Elem().Kind() == reflect.Uint8 { var bytes []byte - if f.Kind() == reflect.Slice { + if f.Kind() == reflect.Slice || f.CanAddr() { bytes = f.Bytes() - } else if f.CanAddr() { - bytes = f.Slice(0, f.Len()).Bytes() } else { // We have an array, but we cannot Slice() a non-addressable array, // so we build a slice by hand. This is a rare case but it would be nice -- 2.50.0