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? Might be worth clarifying that in the comments in gimple.h. jeff
