https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96480
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:b3aa137212b1af0c824a9890eba2ca27a7271d56 commit r11-2593-gb3aa137212b1af0c824a9890eba2ca27a7271d56 Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Aug 6 15:47:25 2020 +0200 reassoc: Improve maybe_optimize_range_tests [PR96480] On the following testcase, if the IL before reassoc would be: ... <bb 4> [local count: 354334800]: if (x_3(D) == 2) goto <bb 7>; [34.00%] else goto <bb 5>; [66.00%] <bb 5> [local count: 233860967]: if (x_3(D) == 3) goto <bb 7>; [34.00%] else goto <bb 6>; [66.00%] <bb 6> [local count: 79512730]: <bb 7> [local count: 1073741824]: # prephitmp_7 = PHI <1(3), 1(4), 1(5), 1(2), 0(6)> then we'd optimize it properly, but as bb 5-7 is instead: <bb 5> [local count: 233860967]: if (x_3(D) == 3) goto <bb 6>; [34.00%] else goto <bb 7>; [66.00%] <bb 6> [local count: 79512730]: <bb 7> [local count: 1073741824]: # prephitmp_7 = PHI <1(3), 1(4), 0(5), 1(2), 1(6)> (i.e. the true/false edges on the last bb with condition swapped and ditto for the phi args), we don't recognize it. If bb 6 is empty, there should be no functional difference between the two IL representations. This patch handles those special cases. 2020-08-06 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/96480 * tree-ssa-reassoc.c (suitable_cond_bb): Add TEST_SWAPPED_P argument. If TEST_BB ends in cond and has one edge to *OTHER_BB and another through an empty bb to that block too, if PHI args don't match, retry them through the other path from TEST_BB. (maybe_optimize_range_tests): Adjust callers. Handle such LAST_BB through inversion of the condition. * gcc.dg/tree-ssa/pr96480.c: New test.
