| // 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 | 
 | 	} | 
 | } |