https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121768
--- Comment #2 from GCC 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:56e7010eef88d941c59e3d677b7bc67a890c210d commit r16-3569-g56e7010eef88d941c59e3d677b7bc67a890c210d Author: Richard Biener <rguent...@suse.de> Date: Thu Sep 4 09:33:58 2025 +0200 tree-optimization/121768 - bogus double reduction detected The following changes how we detect double reductions, in particular not setting vect_double_reduction_def on the outer PHIs when the inner loop doesn't satisfy double reduction constraints. It also simplifies the setup a bit by not having to detect wheter we process an inner loop of a double reduction. PR tree-optimization/121768 * tree-vect-loop.cc (vect_inner_phi_in_double_reduction_p): Remove. (vect_analyze_scalar_cycles_1): Analyze inner loops of double reductions immediately and only mark fully recognized double reductions. Skip already analyzed inner loops. (vect_is_simple_reduction): Change double_reduc from a flag to an output of the inner loop PHI and to whether we are processing an inner loop of a double reduction. * gcc.dg/vect/pr121768.c: New testcase.
