cmd/internal/objabi: use sync.OnceValue

Change-Id: I09c134fff728d32c5bc475889b8c673cc18120a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/611041
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

diff --git a/src/cmd/internal/objabi/pkgspecial.go b/src/cmd/internal/objabi/pkgspecial.go
index f288096a025f07b661186d55f9a55f7a8fe74e67..0cf2e64e80e69d94fe64ad65a27a997138ee4990 100644 (file)
--- a/src/cmd/internal/objabi/pkgspecial.go
+++ b/src/cmd/internal/objabi/pkgspecial.go
@@ -91,39 +91,36 @@ var allowAsmABIPkgs = []string{
        "runtime/internal/startlinetest",
 }
 
-var (
-       pkgSpecials     map[string]PkgSpecial
-       pkgSpecialsOnce sync.Once
-)
-
 // LookupPkgSpecial returns special build properties for the given package path.
 func LookupPkgSpecial(pkgPath string) PkgSpecial {
-       pkgSpecialsOnce.Do(func() {
-               // Construct pkgSpecials from various package lists. This lets us use
-               // more flexible logic, while keeping the final map simple, and avoids
-               // the init-time cost of a map.
-               pkgSpecials = make(map[string]PkgSpecial)
-               set := func(elt string, f func(*PkgSpecial)) {
-                       s := pkgSpecials[elt]
-                       f(&s)
-                       pkgSpecials[elt] = s
-               }
-               for _, pkg := range runtimePkgs {
-                       set(pkg, func(ps *PkgSpecial) { ps.Runtime = true; ps.NoInstrument = true })
-               }
-               for _, pkg := range extraNoInstrumentPkgs {
-                       if pkg[0] == '-' {
-                               set(pkg[1:], func(ps *PkgSpecial) { ps.NoInstrument = false })
-                       } else {
-                               set(pkg, func(ps *PkgSpecial) { ps.NoInstrument = true })
-                       }
-               }
-               for _, pkg := range noRaceFuncPkgs {
-                       set(pkg, func(ps *PkgSpecial) { ps.NoRaceFunc = true })
-               }
-               for _, pkg := range allowAsmABIPkgs {
-                       set(pkg, func(ps *PkgSpecial) { ps.AllowAsmABI = true })
-               }
-       })
-       return pkgSpecials[pkgPath]
+       return pkgSpecialsOnce()[pkgPath]
 }
+
+var pkgSpecialsOnce = sync.OnceValue(func() map[string]PkgSpecial {
+       // Construct pkgSpecials from various package lists. This lets us use
+       // more flexible logic, while keeping the final map simple, and avoids
+       // the init-time cost of a map.
+       pkgSpecials := make(map[string]PkgSpecial)
+       set := func(elt string, f func(*PkgSpecial)) {
+               s := pkgSpecials[elt]
+               f(&s)
+               pkgSpecials[elt] = s
+       }
+       for _, pkg := range runtimePkgs {
+               set(pkg, func(ps *PkgSpecial) { ps.Runtime = true; ps.NoInstrument = true })
+       }
+       for _, pkg := range extraNoInstrumentPkgs {
+               if pkg[0] == '-' {
+                       set(pkg[1:], func(ps *PkgSpecial) { ps.NoInstrument = false })
+               } else {
+                       set(pkg, func(ps *PkgSpecial) { ps.NoInstrument = true })
+               }
+       }
+       for _, pkg := range noRaceFuncPkgs {
+               set(pkg, func(ps *PkgSpecial) { ps.NoRaceFunc = true })
+       }
+       for _, pkg := range allowAsmABIPkgs {
+               set(pkg, func(ps *PkgSpecial) { ps.AllowAsmABI = true })
+       }
+       return pkgSpecials
+})