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[Bug c++/69289] Compiling without --profile-generate causes longer execution time (-O3)
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 15 Jan 2016 09:05:03 +0000
- Subject: [Bug c++/69289] Compiling without --profile-generate causes longer execution time (-O3)
- Auto-submitted: auto-generated
- References: <bug-69289-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69289
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2016-01-15
Ever confirmed|0 |1
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
If you disable inlining it behaves as expected. I think you are measuring
the clearing of the vector with the .resize() call which is inlined in the
non-profile case but happens to end up using memset in the profile case.
The code of the actual copying function is the same.
Not sure how we end up "optimizing" the resize without profile-generate though.