https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83965
--- Comment #1 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> --- Author: rsandifo Date: Tue Jan 23 10:42:10 2018 New Revision: 256976 URL: https://gcc.gnu.org/viewcvs?rev=256976&root=gcc&view=rev Log: Disable some patterns for fold-left reductions (PR 83965) In this PR we recognised a PLUS_EXPR as a fold-left reduction, then applied pattern matching to convert it to a WIDEN_SUM_EXPR. We need to keep the original code in this case since we implement the reduction using scalar rather than vector operations. 2018-01-23 Richard Sandiford <richard.sandif...@linaro.org> gcc/ PR tree-optimization/83965 * tree-vect-patterns.c (vect_reassociating_reduction_p): New function. (vect_recog_dot_prod_pattern, vect_recog_sad_pattern): Use it instead of checking only for a reduction. (vect_recog_widen_sum_pattern): Likewise. gcc/testsuite/ PR tree-optimization/83965 * gcc.dg/vect/pr83965.c: New test. Added: trunk/gcc/testsuite/gcc.dg/vect/pr83965.c Modified: trunk/gcc/ChangeLog trunk/gcc/testsuite/ChangeLog trunk/gcc/tree-vect-patterns.c
