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From: "msharov at users dot sourceforge.net" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/23684] Combine stores for non strict alignment targets Date: Sat, 18 May 2013 14:04:00 -0000 [thread overview] Message-ID: <bug-23684-4-FvuVEprd0S@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-23684-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23684 --- Comment #12 from msharov at users dot sourceforge.net --- I'd like to add that this is not some corner case; this is a very common issue. In my own projects, the compiler's inability to combine stores is the single largest reason for using inline assembly and raw casts. Pretty much every time I have an object 8 or 16 bytes in size, I end up writing a zeroing ctor, copy ctor, and operator= that use full-object memory access. That's cast to uint64_t for 8 bytes, and movups/movaps for 16 bytes. It also shows up when writing raw protocol data, such as X calls, where it is very common to write several constants in succession. The last time I checked, forcing whole-object moves in these cases results in projectwide code size reduction ~10%. Unfortunately, it also causes a variety of aliasing pessimizations, so I also have to test including or not including each of the above functions to get the smallest code size. I would be a very big deal if the optimizer could do this.
next prev parent reply other threads:[~2013-05-18 14:04 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-23684-4@http.gcc.gnu.org/bugzilla/> 2012-07-18 9:36 ` rguenth at gcc dot gnu.org 2013-05-17 8:48 ` rguenth at gcc dot gnu.org 2013-05-17 9:52 ` jakub at gcc dot gnu.org 2013-05-18 14:04 ` msharov at users dot sourceforge.net [this message] 2013-11-10 6:30 ` pinskia at gcc dot gnu.org [not found] <bug-23684-6528@http.gcc.gnu.org/bugzilla/> 2006-09-21 4:39 ` pinskia at gcc dot gnu dot org 2006-09-21 5:12 ` acahalan at gmail dot com 2006-11-29 5:05 ` pinskia at gcc dot gnu dot org 2006-11-29 5:11 ` acahalan at gmail dot com 2007-04-03 16:53 ` pinskia at gcc dot gnu dot org 2007-04-03 16:54 ` pinskia at gcc dot gnu dot org 2005-09-01 18:05 [Bug rtl-optimization/23684] New: " pinskia at gcc dot gnu dot org 2005-09-01 18:07 ` [Bug rtl-optimization/23684] " pinskia at gcc dot gnu dot org 2005-09-07 1:42 ` amodra at bigpond dot net dot au 2005-09-15 20:15 ` pinskia at gcc dot gnu dot org
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