On 27/10/2015 11:36, "Richard Biener" <richard.guent...@gmail.com> wrote:
>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. > I did consider removing those asserts, but didn’t want to remove any important checks. Didn’t think about the disable-checking build. Anyway, new patch attached. Cheers, Alan.
avoid_issimple3.patch
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