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[Bug rtl-optimization/79279] combine/simplify_set: wrong call to REG_CANNOT_CHANGE_MODE_P
- From: "aurelien.buhrig.gcc at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 01 Feb 2017 09:16:18 +0000
- Subject: [Bug rtl-optimization/79279] combine/simplify_set: wrong call to REG_CANNOT_CHANGE_MODE_P
- Auto-submitted: auto-generated
- References: <bug-79279-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79279
Aurelien Buhrig <aurelien.buhrig.gcc at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |WONTFIX
--- Comment #2 from Aurelien Buhrig <aurelien.buhrig.gcc at gmail dot com> ---
According to the above gcc-patches discussion,
checking m2 -> m1 is required to be sure that the new reg:m2 interpreted as m1
is valid.
So both checks would be needed. But although the m1 -> m2 transformation is
invalid, this change should be filtered by predicates (from general_operand)
which wasn't.
So no need to fix, unless maybe speeding up the combine process.