https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123343
--- Comment #16 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Zhongyao Chen <[email protected]>: https://gcc.gnu.org/g:1cca2bfbdaa4433002d321b580b173294ee88460 commit r17-1490-g1cca2bfbdaa4433002d321b580b173294ee88460 Author: Zhongyao Chen <[email protected]> Date: Wed Jan 14 11:38:02 2026 +0000 tree-optimization - Require size > 1 for SLP reduction subgroups The SLP reduction subgroup analysis can succeed for size-1 groups, but this leads to poor code generation. Size-1 cases should fall back to single-lane reduction instead. Handle size-1 groups by returning false from the analysis function, and add a loop exit check to avoid unnecessary processing. PR tree-optimization/123343 gcc/ChangeLog: * tree-vect-slp.cc (vect_analyze_slp_reduction_group): Return false for group_size <= 1 at entry. (vect_analyze_slp_reductions): Add loop exit check for group_size <= 1. gcc/testsuite/ChangeLog: * gcc.dg/vect/slp-reduc-var.c: New testcase. Signed-off-by: Zhongyao Chen <[email protected]>
