https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105679
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:49ba4fdeb648c149fa7d964ba812084262c3d06f commit r13-1891-g49ba4fdeb648c149fa7d964ba812084262c3d06f Author: Richard Biener <rguent...@suse.de> Date: Fri Jul 29 10:40:34 2022 +0200 tree-optimization/105679 - disable backward threading of unlikely entry The following makes the backward threader reject threads whose entry edge is probably never executed according to the profile. That in particular, for the testcase, avoids threading the irq == 1 check on the path where irq > 31, thereby avoiding spurious -Warray-bounds diagnostics if (irq_1(D) > 31) goto <bb 3>; [0.00%] else goto <bb 4>; [100.00%] ;; basic block 3, loop depth 0, count 0 (precise), probably never executed _2 = (unsigned long) irq_1(D); __builtin___ubsan_handle_shift_out_of_bounds (&*.Lubsan_data0, 1, _2); _3 = 1 << irq_1(D); mask_4 = (u32) _3; entry = instance_5(D)->array[irq_1(D)]; capture (mask_4); if (level_6(D) != 0) goto <bb 7>; [34.00%] else goto <bb 5>; [66.00%] ;; basic block 5, loop depth 0, count 708669600 (estimated locally), maybe hot if (irq_1(D) == 1) goto <bb 7>; [20.97%] else goto <bb 6>; [79.03%] PR tree-optimization/105679 * tree-ssa-threadbackward.cc (back_threader_profitability::profitable_path_p): Avoid threading when the entry edge is probably never executed.
