tree 119848ce8be4a31f8bc7ea1c5c722b3bb20dc97c
parent 0f6d673d5b1a3474c3424cb6994ae8ff9baed255
author Cherry Zhang <cherryyz@google.com> 1565985587 -0400
committer Ian Lance Taylor <iant@golang.org> 1566016502 +0000

runtime: scan write barrier buffer conservatively

In gccgo, we insert the write barriers in the frontend, and so we
cannot completely prevent write barriers on stack writes. So it
is possible for a bad pointer appearing in the write barrier
buffer. When flushing the write barrier, treat it the same as
sacnning the stack. In particular, don't mark a pointer if it
does not point to an allocated object. We already have similar
logic in greyobject. With this, hopefully, we can prevent an
unallocated object from being marked completely.

Change-Id: If8349916b648b1b4241b8499f57c764540402bdf
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/190599
Reviewed-by: Ian Lance Taylor <iant@golang.org>