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From: "law at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/59747] [4.9 Regression] wrong code at -Os and above on x86_64-linux-gnu in 64-bit mode
Date: Fri, 10 Jan 2014 17:56:00 -0000	[thread overview]
Message-ID: <bug-59747-4-bvFYkHNRRQ@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-59747-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59747

--- Comment #8 from Jeffrey A. Law <law at redhat dot com> ---
This looks pretty easy to fix as we emit the copies.

Basically we had two extensions reached by the same def.  Elimination of the
first extension requires a copy.  Elimination of the second does not.  The
second extension is wider than the first.

All looks good after elimination of the first extension.  Elimination of the
second extension looks good as well -- basically we just widen the extension
that'll be done as part of the def insn.  However, when we do that we need to
widen the copy generated when we eliminated the first extension.

Thankfully we have the defining insn handy when we generate the copy (they're
not generated until after the defining insns are all munged).  So it's just a
matter of generating the copy in the wider mode.

I want to look at a couple things, but right now I expect this'll be wrapped up
shortly.


  parent reply	other threads:[~2014-01-10 17:56 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-10  6:19 [Bug tree-optimization/59747] New: " su at cs dot ucdavis.edu
2014-01-10  8:48 ` [Bug tree-optimization/59747] [4.9 Regression] " mpolacek at gcc dot gnu.org
2014-01-10 10:05 ` mpolacek at gcc dot gnu.org
2014-01-10 10:17 ` mpolacek at gcc dot gnu.org
2014-01-10 10:58 ` jakub at gcc dot gnu.org
2014-01-10 11:05 ` rguenth at gcc dot gnu.org
2014-01-10 11:08 ` jakub at gcc dot gnu.org
2014-01-10 13:14 ` jakub at gcc dot gnu.org
2014-01-10 16:25 ` law at redhat dot com
2014-01-10 17:14 ` law at redhat dot com
2014-01-10 17:56 ` law at redhat dot com [this message]
2014-01-15 13:11 ` trippels at gcc dot gnu.org
2014-01-15 18:14 ` law at redhat dot com
2014-01-15 18:14 ` law at gcc dot gnu.org
2014-01-16 20:11 ` dominiq at lps dot ens.fr
2014-01-16 20:12 ` dominiq at lps dot ens.fr
2014-01-16 20:12 ` dominiq at lps dot ens.fr
2014-01-16 20:20 ` jakub at gcc dot gnu.org
2014-01-16 21:05 ` dominiq at lps dot ens.fr

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