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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/59644] [4.9 Regression] r206243 miscompiles Linux kernel
Date: Tue, 31 Dec 2013 11:47:00 -0000 [thread overview]
Message-ID: <bug-59644-4-yD7iuvoLVj@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-59644-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59644
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |hjl.tools at gmail dot com,
| |hubicka at gcc dot gnu.org
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, on this source file the only differences caused by r206243 are caused by
the
ix86_save_reg hunk, the 4 functions in question before pro_and_epilogue pass
don't need dynamic stack realignment, drap_reg is set to r10 but isn't live at
the beginning of the function, just used somewhere in the function. Previously
we'd save/restore it anyway, I assume just in case it would be used by the
epilogue if drap would be needed there (but it isn't), after my commit it isn't
saved (r10 is call used register, so there is no point in saving/restoring it).
So, I fail to see why this change is wrong, unless the kernel say calls one of
those functions from assembly and mistakenly assumes r10 is not clobbered by
the call.
Note that if stack realignment would happen, then r10 would not be preserved
even before the patch, in that case, while r10 is saved/restored, it is saved
after it has been set to the DRAP value.
next prev parent reply other threads:[~2013-12-31 11:47 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-30 23:03 [Bug tree-optimization/59644] New: " trippels at gcc dot gnu.org
2013-12-30 23:43 ` [Bug tree-optimization/59644] " jakub at gcc dot gnu.org
2013-12-31 8:17 ` trippels at gcc dot gnu.org
2013-12-31 8:18 ` trippels at gcc dot gnu.org
2013-12-31 8:19 ` trippels at gcc dot gnu.org
2013-12-31 8:20 ` trippels at gcc dot gnu.org
2013-12-31 8:26 ` trippels at gcc dot gnu.org
2013-12-31 11:47 ` jakub at gcc dot gnu.org [this message]
2013-12-31 13:03 ` trippels at gcc dot gnu.org
2014-01-06 8:21 ` trippels at gcc dot gnu.org
2014-01-06 8:48 ` trippels at gcc dot gnu.org
2014-01-06 9:08 ` jakub at gcc dot gnu.org
2014-01-06 9:17 ` trippels at gcc dot gnu.org
2014-01-06 9:26 ` jakub at gcc dot gnu.org
2014-01-06 9:36 ` trippels at gcc dot gnu.org
2014-01-06 10:00 ` trippels at gcc dot gnu.org
2014-01-06 10:04 ` trippels at gcc dot gnu.org
2014-01-06 10:09 ` hjl.tools at gmail dot com
2014-01-06 10:12 ` jakub at gcc dot gnu.org
2014-01-06 10:21 ` trippels at gcc dot gnu.org
2014-01-06 11:28 ` jakub at gcc dot gnu.org
2014-01-06 11:55 ` jakub at gcc dot gnu.org
2014-01-06 13:39 ` [Bug target/59644] " jakub at gcc dot gnu.org
2014-01-06 21:38 ` jakub at gcc dot gnu.org
2014-01-06 21:39 ` jakub at gcc dot gnu.org
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