https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117723
--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Alexandre Oliva <aol...@gcc.gnu.org>: https://gcc.gnu.org/g:70f7c603da67adff13e41831ab8ec4e2f6fadc2c commit r15-5769-g70f7c603da67adff13e41831ab8ec4e2f6fadc2c Author: Alexandre Oliva <ol...@adacore.com> Date: Fri Nov 29 05:42:28 2024 -0300 ifcombine: avoid unsound forwarder-enabled combinations [PR117723] When ifcombining contiguous blocks, we can follow forwarder blocks and reverse conditions to enable combinations, but when there are intervening blocks, we have to constrain ourselves to paths to the exit that share the PHI args with all intervening blocks. Avoiding considering forwarders when intervening blocks were present would match the preexisting test, but we can do better, recording in case a forwarded path corresponds to the outer block's exit path, and insisting on not combining through any other path but the one that was verified as corresponding. The latter is what this patch implements. While at that, I've fixed some typos, introduced early testing before computing the exit path to avoid it when computing it would be wasteful, or when avoiding it can enable other sound combinations. for gcc/ChangeLog PR tree-optimization/117723 * tree-ssa-ifcombine.cc (tree_ssa_ifcombine_bb): Record forwarder blocks in path to exit, and stick to them. Avoid computing the exit if obviously not needed, and if that enables additional optimizations. (tree_ssa_ifcombine_bb_1): Fix typos. for gcc/testsuite/ChangeLog PR tree-optimization/117723 * gcc.dg/torture/ifcmb-1.c: New.
