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[Bug c++/69564] [5/6 Regression] lto and/or C++ make scimark2 LU slower
- From: "jason at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 24 Feb 2016 05:33:21 +0000
- Subject: [Bug c++/69564] [5/6 Regression] lto and/or C++ make scimark2 LU slower
- Auto-submitted: auto-generated
- References: <bug-69564-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69564
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |NEW
Assignee|jason at gcc dot gnu.org |unassigned at gcc dot gnu.org
--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Jason Merrill from comment #7)
> But if I add loop inversion back into the C++ front end
> so that the .optimized output is indistinguishable, that resolves the
> difference without LTO
Actually, no, the loop inversion patch in comment 8 doesn't improve
performance; even though the .optimized dump is the same between C and C++, the
C++ build is still slower by roughly the same amount. I guess the RTL
optimizers must be doing something different? Mysterious. Unassigning myself.