https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118922
--- Comment #25 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-14 branch has been updated by Andrew Pinski <pins...@gcc.gnu.org>: https://gcc.gnu.org/g:0d931663498d2f95fb7ea0ae0ef8473f88eed26a commit r14-11613-g0d931663498d2f95fb7ea0ae0ef8473f88eed26a Author: Andrew Pinski <quic_apin...@quicinc.com> Date: Sat Mar 8 22:43:54 2025 -0800 phiopt: Fix value_replacement for middle bb having phi nodes [PR118922] After r12-5300-gf98f373dd822b3, value_replacement would be able to look at the following cfg structure: ``` <bb 5> [local count: 1014686024]: if (h_6 != 0) goto <bb 7>; [94.50%] else goto <bb 6>; [5.50%] <bb 6> [local count: 114863530]: # h_6 = PHI <0(4), 1(5)> <bb 7> [local count: 1073741824]: # f_8 = PHI <0(5), h_6(6)> _9 = f_8 ^ 1; a.0_10 = a; _11 = _9 + a.0_10; if (_11 != -117) goto <bb 5>; [94.50%] else goto <bb 8>; [5.50%] ``` value_replacement would incorrectly think the middle bb (6) was empty and so it decides to remove condition in bb5 and replacing it with 0 as the function thought it was `h_6 ? 0 : h_6`. But since the there is an incoming phi node to bb6 defining h_6 that is incorrect. The fix is to check if there is phi nodes in the middle bb and set empty_or_with_defined_p to false. This was not needed before r12-5300-gf98f373dd822b3 because the phi would have been dead otherwise due to other checks. Bootstrapped and tested on x86_64-linux-gnu. PR tree-optimization/118922 gcc/ChangeLog: * tree-ssa-phiopt.cc (value_replacement): Set empty_or_with_defined_p to false when there is phi nodes for the middle bb. gcc/testsuite/ChangeLog: * gcc.dg/torture/pr118922-1.c: New test. Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com> (cherry picked from commit 7232c005afb5002cdfd0a2dbd0e8b8f2d80250ce)
