https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109087
--- Comment #15 from rguenther at suse dot de <rguenther at suse dot de> --- On Tue, 14 Mar 2023, jakub at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109087 > > --- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > I didn't mean for GCC 13, we need to fix the actual backend bug regardless and > so a DSE improvement can't be considered a fix... ;) > Just the DSE thing happens very often with -ftrivial-auto-var-init=. > I wonder if even after your improvement we don't keep .DEFERRED_INIT for > unused > vars for the case when the DSE walk will run into the vdef/vuse limits (I > assume it doesn't do unbounded walk). Sure, it's still covered by the walking limit. > Perhaps some special handling of > .DEFERRED_INITs for vars which have solely those statements and clobbers and > nothing else? remove_unused_locals has code to handle vars only CLOBBEREd, so yes, we can probably wire such a thing in there at the cost of one extra walk (see the have_local_clobbers flag, the first walk discovers, the second eventually removes them). I'll see to draft a patch for this as well.
