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Re: Undefined behavior in genautomata.c?
- From: Gabriel Dos Reis <gdr at integrable-solutions dot net>
- To: Sebastian Pop <sebastian dot pop at cri dot ensmp dot fr>
- Cc: gcc at gcc dot gnu dot org, Vladimir Makarov <vmakarov at redhat dot com>
- Date: 19 Sep 2005 11:48:53 +0200
- Subject: Re: Undefined behavior in genautomata.c?
- References: <20050919091420.GA5325@napoca.cri.ensmp.fr>
Sebastian Pop <sebastian.pop@cri.ensmp.fr> writes:
| Hi,
|
| I was working on improving the results of scev, when VRP has broken
| the bootstrap, eliminating loops that were estimated as running a
| single time. These loop bound estimates come from the undefined
| behavior of accessing over the bounds of statically allocated data in
| genautomata.c:
If VRP is doing what you described in the comment as "its work", then
VRP is broken. Period. The fix is to fix VRP. It is such a C
idomatic construct than I would not have expected any "optimizer" to
break it. And that is very worrisome and scary.
-- Gaby