https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100089
--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> --- So this fixes it for -fvect-cost-model=very-cheap. One could argue that we should enable the code for all cost models, fixing the -O3 regression (and backportable to the branch). I'll see to experiment with "fancy" costing of the stray vectorizations. I'll also note that the scanning for load/store (and other ifns not supported) could be handled in the costing as well (but the costing would need to run also for -fno-vect-cost-model then, just the result ignored if not forced). I'm talking about bool require_loop_vectorize = false; for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple *stmt = gsi_stmt (gsi); gcall *call = dyn_cast <gcall *> (stmt); if (call && gimple_call_internal_p (call)) { internal_fn ifn = gimple_call_internal_fn (call); if (ifn == IFN_MASK_LOAD || ifn == IFN_MASK_STORE /* Don't keep the if-converted parts when the ifn with specifc type is not supported by the backend. */ || (direct_internal_fn_p (ifn) && !direct_internal_fn_supported_p (call, OPTIMIZE_FOR_SPEED))) { require_loop_vectorize = true; break; } }