undo CL 8954044 / ad3c2ffb16d7

It works on i386, but fails on amd64 and arm.

««« original CL description
runtime: prevent the GC from seeing the content of a frame in runfinq()

Fixes #5348.

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/8954044
»»»

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8695051

src/pkg/runtime/mgc0.c

@@ -2191,7 +2191,7 @@ runfinq(void)
 				framesz = sizeof(uintptr) + f->nret;
 				if(framecap < framesz) {
 					runtime·free(frame);
-					frame = runtime·mallocgc(framesz, FlagNoPointers, 0, 1);
+					frame = runtime·mal(framesz);
 					framecap = framesz;
 				}
 				*(void**)frame = f->arg;

test/fixedbugs/issue5348.go

-// run
-
-// Copyright 2013 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.
-
-// Issue 5348: finalizers keep data live for a surprising amount of time
-
-package main
-
-import (
-	"runtime"
-)
-
-type T struct {
-	S *string
-}
-
-func newString(s string) *string {
-	return &s
-}
-
-var c = make(chan int)
-
-func foo() {
-	t := &T{S: newString("foo")}
-	runtime.SetFinalizer(t, func(p *T) { c <- 0 })
-	runtime.SetFinalizer(t.S, func(p *string) { c <- 0 })
-}
-
-func main() {
-	foo()
-	runtime.GC()
-	<-c
-	runtime.GC()
-	<-c
-}