On Fri, Sep 16, 2016 at 08:47:28AM +0200, Richard Biener wrote:
> On Fri, 16 Sep 2016, Jakub Jelinek wrote:
> > Hi!
> > As mentioned in the PR, combiner sometimes calls
> > purge_all_dead_edges or purge_dead_edges that can invalidate the dominator
> > info if it is computed. Other passes like CSE in that case free the
> > dominance info, this patch does the same in the combiner.
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> Ok. (I wonder if/why cleanup_cfg (0) doesn't do this then?)
cleanup_cfg only frees it in some cases if it does some kind of changes:
/* ??? We probably do this way too often. */
|| (mode & CLEANUP_CFG_CHANGED)))
But here the dominator info gets out of sync earlier, in particular on this
testcase in the
new_direct_jump_p |= purge_all_dead_edges ();
Perhaps ideally we should teach all these functions to update the dominator
info, but I'm afraid it is a lot of work.