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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/36503] x86 can use x >> -y for x >> 32-y
Date: Fri, 22 Oct 2010 07:37:00 -0000	[thread overview]
Message-ID: <20101022073700.b8XS5yVHV9oGZmSjnVuoPwMyr8DRzX3YAnprw4kmw6g@z> (raw)
In-Reply-To: <bug-36503-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36503

--- Comment #9 from Uros Bizjak <ubizjak at gmail dot com> 2010-10-22 07:37:22 UTC ---
(In reply to comment #8)
> I built ffmpeg for x86-64 with --disable-asm with the attached patch and the
> regression tests failed. Reverting the patch fixes them. I saved the binaries
> but haven't investigated yet.

The problem is that new insn pattern clobbers %ecx. Currently, this is not
modeled correctly - if this is fixed, then the combine doesn't recognize
combined pattern.  So, either combine should be fixed to allow correct
(match_dup X) in the combined pattern or this transformation should be
implemented in generic part of the compiler.


  parent reply	other threads:[~2010-10-22  7:37 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-36503-4@http.gcc.gnu.org/bugzilla/>
2010-10-21  4:39 ` astrange at ithinksw dot com
2010-10-22  7:37 ` ubizjak at gmail dot com [this message]
2008-06-11 22:53 [Bug target/36503] New: " astrange at ithinksw dot com
2008-06-11 22:53 ` [Bug target/36503] " astrange at ithinksw dot com
2008-06-12  0:05 ` pinskia at gcc dot gnu dot org
2008-06-12  9:25 ` rguenth at gcc dot gnu dot org
2008-06-12 10:44 ` ubizjak at gmail dot com
2008-06-12 16:49 ` astrange at ithinksw dot com
2009-11-07  9:22 ` bonzini at gnu dot org
2009-11-09  7:38 ` ubizjak at gmail dot com

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