On Tue, Mar 19, 2019 at 8:53 PM Jeff Law <l...@redhat.com> wrote: > > On 3/6/19 3:05 AM, Richard Biener wrote: > > On Tue, Mar 5, 2019 at 10:36 PM Jeff Law <l...@redhat.com> wrote: > >> > >> On 3/5/19 7:44 AM, Richard Biener wrote: > >> > >>> So fixing it properly with also re-optimize_stmt those stmts so we'd CSE > >>> the MAX_EXPR introduced by folding makes it somewhat ugly. > >>> > >>> Bootstrapped on x86_64-unknown-linux-gnu, testing in progress. > >>> > >>> Any ideas how to make it less so? I can split out making optimize_stmt > >>> take a gsi * btw, in case that's a more obvious change and it makes the > >>> patch a little smaller. > >>> > >>> Richard. > >>> > >>> 2019-03-05 Richard Biener <rguent...@suse.de> > >>> > >>> PR tree-optimization/89595 > >>> * tree-ssa-dom.c (dom_opt_dom_walker::optimize_stmt): Take > >>> stmt iterator as reference, take boolean output parameter to > >>> indicate whether the stmt was removed and thus the iterator > >>> already advanced. > >>> (dom_opt_dom_walker::before_dom_children): Re-iterate over > >>> stmts created by folding. > >>> > >>> * gcc.dg/torture/pr89595.c: New testcase. > >>> > >> > >> Well, all the real logic changs are in the before_dom_children method. > >> The bits in optimize_stmt are trivial enough to effectively ignore. > >> > >> I don't see a better way to discover and process statements that are > >> created in the bowels of fold_stmt. > > > > I'm not entirely happy so I created the following alternative which > > is a bit larger and slower due to the pre-pass clearing the visited flag > > but is IMHO easier to follow. I guess there's plenty of TLC opportunity > > here but then I also hope to retire the VN parts of DOM in favor > > of the non-iterating RPO-VN code... > > > > So - I'd lean to this variant even though it has the extra loop over stmts, > > would you agree? > > > > Bootstrap / regtest running on x86_64-unknown-linux-gnu. > > > > Richard. > > > > 2019-03-06 Richard Biener <rguent...@suse.de> > > > > PR tree-optimization/89595 > > * tree-ssa-dom.c (dom_opt_dom_walker::optimize_stmt): Take > > stmt iterator as reference, take boolean output parameter to > > indicate whether the stmt was removed and thus the iterator > > already advanced. > > (dom_opt_dom_walker::before_dom_children): Re-iterate over > > stmts created by folding. > > > > * gcc.dg/torture/pr89595.c: New testcase. > This one is easier to follow from a logic standpoint. I don't think the > gimple_set_visited bits are going to be terribly expensive in general. > > Is that flag in a known state for new statements? I'm guessing it's > cleared by some structure-sized memset as we create the raw statement?
Yes, it's of course not documented that way but IMHo the only reasonable state. > Might be worth clarifying that in the comments in gimple.h. > > jeff >
