Re: A question about df

["Seongbae Park (박성배, 朴成培)" <seongbae dot park at gmail dot com>]

On 10/24/07, Revital1 Eres <ERES@il.ibm.com> wrote:
>
> Hello,
>
> While testing a patch for the SMS I got an ICE which seems
> to be related to the fact we build def-use chains only
> and not use-def chains.  (removed in the following patch -
> http://gcc.gnu.org/ml/gcc-patches/2006-12/msg01682.html)

> The problem arises when we delete an insn from the df that contains a
> use but do not update the def-use chain of it's def as we do not have
> the use-def chain to reach it's def, This later causes a problem when
> we try to dump the def-use chain of it's def.

I'm sorry but I don't understand the description of the problem.
What do you mean by "dump" and what problem does this "dump" cause ?

> So, it seems that when asking for only def-use problem and later dump
> the function we should ask for use-def problem as well to avoid cases
> like the above.

The df chain dump routines are supposed to handle DU-only or UD-only cases
properly. If that's not the case, please send us a testcase
(and preferably file a bugzilla report). Thanks,

Seongbae