On Mon, Oct 26, 2015 at 6:15 PM, Alan Hayward <alan.hayw...@arm.com> wrote: > > > On 26/10/2015 13:35, "Richard Biener" <richard.guent...@gmail.com> wrote: > >>On Mon, Oct 26, 2015 at 1:33 PM, Alan Hayward <alan.hayw...@arm.com> >>wrote: >>> There is a potential bug in vectorizable_live_operation. >>> >>> Consider the case where the first op for stmt is valid, but the second >>>is >>> null. >>> The first time through the for () loop, it will call out to >>> vect_is_simple_use () which will set dt. >>> The second time, because op is null, vect_is_simple_use () will not be >>> called. >>> However, dt is still set to a valid value, therefore the loop will >>> continue. >>> >>> Note this is different from the case where the first op is null, which >>> will cause the loop not call vect_is_simple_use () and then return >>>false. >>> >>> It is possible that this was intentional, however that is not clear from >>> the code. >>> >>> The fix is to simply ensure dt is initialized to a default value on each >>> iteration. >> >>I think the patch is a strict improvement, thus OK. Still a NULL operand >>is not possible in GIMPLE so the op && check is not necessary. The way >>it iterates over all stmt uses is a bit scary anyway. As it is ok with >>all invariants it should probably simply do sth like >> >> FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE) >> if (!vect_is_simple_use (op, ....)) >> >>and be done with that. Unvisited uses can only be constants (ok). >> >>Care to rework the funtion like that if you are here? >> > > Ok, I’ve updated as requested.
Ok. Please remove code = gimple_assign_rhs_code (stmt); op_type = TREE_CODE_LENGTH (code); rhs_class = get_gimple_rhs_class (code); gcc_assert (rhs_class != GIMPLE_UNARY_RHS || op_type == unary_op); gcc_assert (rhs_class != GIMPLE_BINARY_RHS || op_type == binary_op); and associated variables as I belive otherwise a --disable-checking build will fail with set-but-not-used warnings. And the asserts are quite pointless given the now sanitized loop. Thanks, Richard. > > Cheers, > Alan. >
