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. Cheers, Alan.
avoid_issimple2.patch
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