From 7015ed891c6f4e51ebaa642fce42ea8a1592b4e1 Mon Sep 17 00:00:00 2001 From: Mauri de Souza Meneguzzo Date: Fri, 1 Sep 2023 18:26:49 +0000 Subject: sync: prevent (*Map).Range from always escaping After the change from CL 426074 the Range method on Map always escape the read variable, leading to an allocation. Since the compiler doesn't do live-range splitting for local variables we need to use some hints to only escape in that particular branch. Fixes #62404 Change-Id: I938a5e593647455fa827e3dd3ed8ea22c7365df1 GitHub-Last-Rev: fcbedb467c7b4e6f1d49e299d243cad70deb34e9 GitHub-Pull-Request: golang/go#62408 Reviewed-on: https://go-review.googlesource.com/c/go/+/524976 Auto-Submit: Bryan Mills LUCI-TryBot-Result: Go LUCI Run-TryBot: Bryan Mills Reviewed-by: Ian Lance Taylor Reviewed-by: Bryan Mills TryBot-Result: Gopher Robot --- src/sync/map_test.go | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'src/sync/map_test.go') diff --git a/src/sync/map_test.go b/src/sync/map_test.go index 1eb3fc68a5..20872f3b72 100644 --- a/src/sync/map_test.go +++ b/src/sync/map_test.go @@ -5,6 +5,7 @@ package sync_test import ( + "internal/testenv" "math/rand" "reflect" "runtime" @@ -280,3 +281,16 @@ func TestCompareAndSwap_NonExistingKey(t *testing.T) { t.Fatalf("CompareAndSwap on an non-existing key succeeded") } } + +func TestMapRangeNoAllocations(t *testing.T) { // Issue 62404 + testenv.SkipIfOptimizationOff(t) + var m sync.Map + allocs := testing.AllocsPerRun(10, func() { + m.Range(func(key, value any) bool { + return true + }) + }) + if allocs > 0 { + t.Errorf("AllocsPerRun of m.Range = %v; want 0", allocs) + } +} -- cgit v1.3