https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96404
--- Comment #18 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Sergei Trofimovich <sly...@gcc.gnu.org>: https://gcc.gnu.org/g:6e46b3f3da5c03bc529b3690dd0995927feb9142 commit r11-2491-g6e46b3f3da5c03bc529b3690dd0995927feb9142 Author: Sergei Trofimovich <siarh...@google.com> Date: Sun Aug 2 12:03:55 2020 +0100 var-tracking: fix uninitialised use of 'in_pending' [PR96404] r11-2447-g:1212cfad093 ("Improve var-tracking dataflow iteration order") changed 'in_pending' initialization from: in_pending = sbitmap_alloc (last_basic_block_for_fn (cfun)); bitmap_ones (in_pending); to more complex partial bit population algorithm. Due to presence of uninitialized bits gcc started injecting extra debug entries in seemigly arbitrary locations and started failing stage2/stage3 bootstrap comparison. valgrind detected unilitialized bits as: Conditional jump or move depends on uninitialised value(s) at 0xDBED3B: vt_find_locations() (var-tracking.c:7230) by 0xDBF2FB: variable_tracking_main_1() (var-tracking.c:10519) ... Uninitialised value was created by a heap allocation at 0x483779F: malloc (vg_replace_malloc.c:307) by 0x14EE80B: xmalloc (xmalloc.c:147) by 0x14911F9: sbitmap_alloc(unsigned int) (sbitmap.c:51) ... The fix explicitly initializes 'in_pending' bitmap with zeros. 2020-08-02 Sergei Trofimovich <siarh...@google.com> gcc/ PR bootstrap/96404 * var-tracking.c (vt_find_locations): Fully initialize all 'in_pending' bits.
