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From: "b.grayson at samsung dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/64319] add alias runtime check to remove load after load redundancy
Date: Tue, 16 Dec 2014 15:31:00 -0000	[thread overview]
Message-ID: <bug-64319-4-rHrctpRDcF@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-64319-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64319

--- Comment #2 from Brian Grayson <b.grayson at samsung dot com> ---
alignd() in m88ksim from SPECint95 is a poster child for this kind of
optimization -- it receives several pointers to portions of FP representations,
and then operates on them via code like this:

...
*amantlo >>= 1;
*amantlo |= *amanthi << 31;
*amanthi >>= 1;
...

In this case, there may actually be a code-space reduction(!) with dynamic
disambiguation, because gcc has to insert so many redundant loads and stores in
the general case that are not needed in either of the two forks.

That may make a handy stand-alone real-world testcase.


  parent reply	other threads:[~2014-12-16 15:31 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-15 19:19 [Bug tree-optimization/64319] New: " spop at gcc dot gnu.org
2014-12-16 10:27 ` [Bug tree-optimization/64319] " rguenth at gcc dot gnu.org
2014-12-16 15:31 ` b.grayson at samsung dot com [this message]
2021-12-15 21:39 ` pinskia at gcc dot gnu.org

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