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[Bug optimization/13301] [tree-ssa] deficiency in jump threading
- From: "rth at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 4 Dec 2003 11:12:06 -0000
- Subject: [Bug optimization/13301] [tree-ssa] deficiency in jump threading
- References: <20031204102137.13301.rth@gcc.gnu.org>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From rth at redhat dot com 2003-12-04 11:12 -------
Subject: Re: [tree-ssa] deficiency in jump threading
On Thu, Dec 04, 2003 at 10:45:19AM -0000, pinskia at gcc dot gnu dot org wrote:
> I do not know if the tree jump threading supports switch tables at all...
It does, but that's not the problem. Past the switch, the
"return NULL" gets compiled to "retval = NULL; goto retloc;"
and we must thread *that* goto with the if condition that
immediately follows.
> but it would be good to know the real case of this bug.
I have no doubt that there is a PHI node in the block that
contains the if condition, and that it is causing the
existing jump threading pass to give up.
I also happen to know that Jeff said that he is working on
this type of problem, so I assigned the PR to him.
r~
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13301