compiler: avoid introducing redundant write barriers
The traversal used by the write barrier insertion phase can sometimes
wind up visiting new statements inserted during the traversal, which
then results in duplicate / redundant write barrier guards. Example
program to reproduce:
package small
type S struct {
N *S
K int
}
var G *S = &S{N: nil, K: 101}
This patch changes the traversal code to keep track of statements
already added and avoid processing them again later in the traversal.
Fixes golang/go#25867
Change-Id: Ie7a81b49e815aff7379d3d4ef7c7a864cebcff5b
Reviewed-on: https://go-review.googlesource.com/118637
Reviewed-by: Ian Lance Taylor <iant@golang.org>
3 files changed
