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From: "amonakov at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/60086] suboptimal asm generated for a loop (store/load false aliasing)
Date: Fri, 07 Feb 2014 17:21:00 -0000	[thread overview]
Message-ID: <bug-60086-4-YzW3IKoiJD@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-60086-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60086

--- Comment #9 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
By "good code" I was referring to the fact that your 4.7 asm does not contain
stack (%rbp) references in the vectorized loop.

Historically, first scheduling (-fschedule-insns) was problematic for 32-bit
x86 due to increase of register pressure to the point that register allocator
couldn't handle.  The situation got much better with the introduction of
-fsched-pressure, and was tuned a bit further recently.  I don't know the
latest status; I think compile time cost is the reason it's not enabled at -O2.

For regrename, the manpage notes there are debug info issues on some targets; I
don't know if there's anything else beside that.


      parent reply	other threads:[~2014-02-07 17:21 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-05 22:41 [Bug rtl-optimization/60086] New: " marcin.krotkiewski at gmail dot com
2014-02-06  8:28 ` [Bug rtl-optimization/60086] " jakub at gcc dot gnu.org
2014-02-06  9:34 ` marcin.krotkiewski at gmail dot com
2014-02-06 10:10 ` mpolacek at gcc dot gnu.org
2014-02-06 10:22 ` rguenth at gcc dot gnu.org
2014-02-07  8:52 ` abel at gcc dot gnu.org
2014-02-07  8:53 ` abel at gcc dot gnu.org
2014-02-07 14:33 ` amonakov at gcc dot gnu.org
2014-02-07 16:43 ` marcin.krotkiewski at gmail dot com
2014-02-07 17:21 ` amonakov at gcc dot gnu.org [this message]

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