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Re: [Bug tree-optimization/30604] Unable to coalesce ssa_names <x> and <y> which are marked as MUST COALESCE
- From: "Daniel Berlin" <dberlin at dberlin dot org>
- To: gcc-bugzilla at gcc dot gnu dot org
- Cc: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 9 Mar 2007 19:01:27 -0500
- Subject: Re: [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/> <20070308201216.26205.qmail@sourceware.org>
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.