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[Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE
- From: "dberlin at dberlin dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 10 Mar 2007 00:01:50 -0000
- Subject: [Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE
- References: <bug-30604-3639@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #9 from dberlin at gcc dot gnu dot org 2007-03-10 00:01 -------
Subject: Re: Unable to coalesce ssa_names <x> and <y> which are marked as MUST
COALESCE
On 8 Mar 2007 20:12:16 -0000, amacleod at redhat dot com
<gcc-bugzilla@gcc.gnu.org> wrote:
>
>
> ------- Comment #7 from amacleod at redhat dot com 2007-03-08 20:12 -------
> Looking at the original testcase, the complaint is that _t_8232 and _t_3 are
> both used in the PHI definition of _t_7. (using mainline from march 5th)
>
> ie, _t_7(ab) = PHI <...., _t_8232, ... , _t_3, ...>
>
Uh, did you not put the (ab) next to the arguments, or do they really
not have SSA_NAME_OCCURS_IN_ABNORMAL_PHI set on them? (They should)
> I can't really read the detailed output from FRE, but it does seem to have
> replaced a bunch of expressions with _t_3, so that would appear to be the
> culprit.
It won't value number things with SSA_NAME_OCCURS_IN_ABNORMAL_PHI set,
so it should never eliminate anything with them.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30604