runtime: clean up duplicate function

For #65355

Author: Jun10ng

src/go/build/deps_test.go

@@ -54,7 +54,7 @@ var depsRules = `
 	internal/goarch, unsafe
 	< internal/abi, internal/chacha8rand;
 
-	unsafe < maps;
+	unsafe < maps, internal/runtime/goroutine;
 
 	# RUNTIME is the core runtime group of packages, all of them very light-weight.
 	internal/abi,
@@ -63,6 +63,7 @@ var depsRules = `
 	internal/cpu,
 	internal/goarch,
 	internal/godebugs,
+	internal/runtime/goroutine,
 	internal/goexperiment,
 	internal/goos
 	< internal/bytealg
@@ -189,7 +190,7 @@ var depsRules = `
 
 	# FMT is OS (which includes string routines) plus reflect and fmt.
 	# It does not include package log, which should be avoided in core packages.
-	arena, strconv, unicode
+	arena, strconv, unicode, internal/runtime/goroutine
 	< reflect;
 
 	os, reflect

src/internal/runtime/goroutine/goroutine.go

@@ -0,0 +1,12 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package goroutine
+
+import "strings"
+
+func IsSystemGoroutine(entryFn string) bool {
+	// Locked g in extra M (with empty entryFn) is system goroutine.
+	return entryFn == "" || entryFn != "runtime.main" && strings.HasPrefix(entryFn, "runtime.")
+}

src/internal/trace/goroutines.go

@@ -5,8 +5,8 @@
 package trace
 
 import (
+	"internal/runtime/goroutine"
 	"sort"
-	"strings"
 )
 
 // GDesc contains statistics and execution details of a single goroutine.
@@ -134,7 +134,7 @@ func (g *GDesc) finalize(lastTs, activeGCStartTime int64, trigger *Event) {
 	// "inherit" a task due to creation (EvGoCreate) from within a region.
 	// This may happen e.g. if the first GC is triggered within a region,
 	// starting the GC worker goroutines.
-	if !IsSystemGoroutine(g.Name) {
+	if !goroutine.IsSystemGoroutine(g.Name) {
 		for _, s := range g.activeRegions {
 			s.End = trigger
 			s.GExecutionStat = finalStat.sub(s.GExecutionStat)
@@ -349,10 +349,3 @@ func RelatedGoroutines(events []*Event, goid uint64) map[uint64]bool {
 	gmap[0] = true // for GC events
 	return gmap
 }
-
-func IsSystemGoroutine(entryFn string) bool {
-	// This mimics runtime.isSystemGoroutine as closely as
-	// possible.
-	// Also, locked g in extra M (with empty entryFn) is system goroutine.
-	return entryFn == "" || entryFn != "runtime.main" && strings.HasPrefix(entryFn, "runtime.")
-}

src/internal/trace/summary.go

@@ -5,6 +5,7 @@
 package trace
 
 import (
+	"internal/runtime/goroutine"
 	tracev2 "internal/trace/v2"
 	"sort"
 	"time"
@@ -231,7 +232,7 @@ func (g *GoroutineSummary) finalize(lastTs tracev2.Time, trigger *tracev2.Event)
 	// "inherit" a task due to creation (EvGoCreate) from within a region.
 	// This may happen e.g. if the first GC is triggered within a region,
 	// starting the GC worker goroutines.
-	if !IsSystemGoroutine(g.Name) {
+	if !goroutine.IsSystemGoroutine(g.Name) {
 		for _, s := range g.activeRegions {
 			s.End = trigger
 			s.GoroutineExecStats = finalStat.sub(s.GoroutineExecStats)

src/runtime/traceback.go

@@ -8,6 +8,7 @@ import (
 	"internal/abi"
 	"internal/bytealg"
 	"internal/goarch"
+	"internal/runtime/goroutine"
 	"runtime/internal/sys"
 	"unsafe"
 )
@@ -1321,7 +1322,6 @@ func tracebackHexdump(stk stack, frame *stkframe, bad uintptr) {
 // system (that is, the finalizer goroutine) is considered a user
 // goroutine.
 func isSystemGoroutine(gp *g, fixed bool) bool {
-	// Keep this in sync with internal/trace.IsSystemGoroutine.
 	f := findfunc(gp.startpc)
 	if !f.valid() {
 		return false
@@ -1339,7 +1339,7 @@ func isSystemGoroutine(gp *g, fixed bool) bool {
 		}
 		return fingStatus.Load()&fingRunningFinalizer == 0
 	}
-	return hasPrefix(funcname(f), "runtime.")
+	return goroutine.IsSystemGoroutine(funcname(f))
 }
 
 // SetCgoTraceback records three C functions to use to gather