On Mon, Oct 05, 2026 at 01:48:01AM -0600, Jeff Law wrote: > > > On 10/4/26 5:24 AM, Aldy Hernandez wrote: > > [Well, since we can't get rid of DOM yet, why don't we clean it up and > > remove stuff we can clearly do better with ranges. Maybe we can > > reduce it to a bare minimum ;-).] > > > > We now have all the pieces to do what test_for_singularity does, but > > with ranges. Remove the function and use simplify_using_ranges > > instead. > > > > This makes DOM a tiny bit smarter, since simplify_using_ranges is far > > more capable than the ad-hoc stuff we did. As much as I hate making > > it smarter, it's all in the interest of nuking it :). > > > > Tested on ppc64le Linux. > > > > OK for trunk? > > > > gcc/ChangeLog: > > > > * tree-ssa-dom.cc (dom_opt_dom_walker::m_dummy_cond): Remove. > > (dom_opt_dom_walker::test_for_singularity): Remove. > > (dom_opt_dom_walker::fold_cond): Remove. > > (dom_opt_dom_walker::simplify_stmt): New. > > (dom_opt_dom_walker::optimize_stmt): Call it in place of > > test_for_singularity and fold_cond. > > > > gcc/testsuite/ChangeLog: > > > > * gcc.dg/tree-ssa/predcom-7.c: Add -fno-tree-dominator-opts. > > * gcc.dg/tree-ssa/ssa-dom-simplify-3.c: New test. > IIRC we've wanted to nuke this optimization as interacts poorly with SCEV. > > Furthermore, the main purpose was to turn these things into equality > comparisons which in turn would expose the constant equivalence on one of > the edges, something done quite well by using Ranger already. > > So no objection to the patch, but if you wanted to get a lot more aggressive > about this blob of code and nuke it, you've got my blessing.
I'll take you up on it, since I'm already knee deep into this. I'll post a follow-up patch. Thanks. Aldy
