https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105346
--- Comment #9 from rguenther at suse dot de <rguenther at suse dot de> --- On Tue, 26 Apr 2022, jakub at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105346 > > --- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > Started with r11-5732-gdce6c58db87ebf7f4477bd3126228e73e4eeee97 > The IL at -O0 -Wall looks during waccess pass like: > void foo () > { > char * bufp; > char buf[20]; > > <bb 2> : > bufp_2 = &buf; > if (&buf != bufp_2) > goto <bb 3>; [INV] > else > goto <bb 4>; [INV] > > <bb 3> : > __builtin_free (bufp_2); > > <bb 4> : > buf ={v} {CLOBBER(eol)}; > return; > > } > > So, I think the waccess pass must be walking SSA_NAME_DEF_STMT to figure out > it > is a free of non-heap. Either it shouldn't do that at -O0, or it should only > walk them when they are in the same bb as the free call, or it needs to be > able > to detect also conditionals like the above. It's using the ptr-query framework which discovers the bufp_2 equivalence but doesn't notice the conditional "invalidating" it.
