|  | // compile | 
|  |  | 
|  | // Copyright 2018 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. | 
|  |  | 
|  | // Make sure dead write barriers are handled correctly. | 
|  |  | 
|  | package main | 
|  |  | 
|  | func f(p **int) { | 
|  | // The trick here is to eliminate the block containing the write barrier, | 
|  | // but only after the write barrier branches are inserted. | 
|  | // This requires some delicate code. | 
|  | i := 0 | 
|  | var b []bool | 
|  | var s string | 
|  | for true { | 
|  | if b[i] { | 
|  | var a []string | 
|  | s = a[len(s)] | 
|  | i = 0 | 
|  | } | 
|  | *p = nil | 
|  | } | 
|  | } |