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From: "amker.cheng at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/62025] [4.9/4.10 Regression] Miscompilation of openssl sha512.c
Date: Wed, 13 Aug 2014 04:22:00 -0000 [thread overview]
Message-ID: <bug-62025-4-auh040YQqS@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-62025-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62025
bin.cheng <amker.cheng at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |amker.cheng at gmail dot com
--- Comment #19 from bin.cheng <amker.cheng at gmail dot com> ---
(In reply to Jeffrey A. Law from comment #16)
> In reference to c#12. I think the ivopts changes are just setting up the
> situation that is mis-handled later. I'd gotten as far as seeing the +128
> increment moving in the scheduler, but hadn't looked to see if it was valid.
>
> Anyway, so yes I think the ivopts stuff is fine.
>
> I should have realized I was chasing something of that nature when the
> bisection settled on the ivopts code as the trigger.
Yes, The scheduling behavior is triggered by specific offset in this case. It
changes below insn sequence:
11405: ......
11406: {%r2:SI=ltu(%cc:CCL1,0)+%r2:SI+[%r8:SI+0xf8];clobber %cc:CC;}
......
2803: {%r8:SI=%r8:SI+0x80;clobber %cc:CC;}
REG_UNUSED %cc:CC
into:
11405: ......
2803: {%r8:SI=%r8:SI+0x80;clobber %cc:CC;}
REG_UNUSED %cc:CC
11406: {%r2:SI=ltu(%cc:CCL1,0)+%r2:SI+[%r8:SI+0x78];clobber %cc:CC;}
by changing the offset in insn 11406.
The problem is why minipass in
http://gcc.gnu.org/ml/gcc-patches/2012-08/msg00155.html would do this
transformation. According to the description, it is to change
rn++
rm=[rn]
into
rm=[rn+4]
rn++
Here it is exactly the opposite tranformation and introducing more dependency.
Thanks.
next prev parent reply other threads:[~2014-08-13 4:22 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-62025-4@http.gcc.gnu.org/bugzilla/>
2014-08-05 14:58 ` jakub at gcc dot gnu.org
2014-08-05 15:02 ` jakub at gcc dot gnu.org
2014-08-11 14:02 ` jakub at gcc dot gnu.org
2014-08-11 16:47 ` jakub at gcc dot gnu.org
2014-08-12 4:07 ` law at redhat dot com
2014-08-12 6:52 ` amker at gcc dot gnu.org
2014-08-12 6:53 ` law at redhat dot com
2014-08-12 8:17 ` jakub at gcc dot gnu.org
2014-08-12 8:55 ` jakub at gcc dot gnu.org
2014-08-12 9:57 ` jakub at gcc dot gnu.org
2014-08-12 10:38 ` amker at gcc dot gnu.org
2014-08-12 11:06 ` jakub at gcc dot gnu.org
2014-08-12 11:47 ` jakub at gcc dot gnu.org
2014-08-12 12:17 ` jakub at gcc dot gnu.org
2014-08-12 14:30 ` law at redhat dot com
2014-08-12 21:25 ` jakub at gcc dot gnu.org
2014-08-12 22:04 ` jakub at gcc dot gnu.org
2014-08-13 4:22 ` amker.cheng at gmail dot com [this message]
2014-08-13 16:25 ` [Bug target/62025] [4.9/5 " jakub at gcc dot gnu.org
2014-08-13 16:27 ` jakub at gcc dot gnu.org
2014-09-01 11:16 ` jakub at gcc dot gnu.org
2014-09-01 11:50 ` jakub at gcc dot gnu.org
2014-10-14 14:01 ` jakub at gcc dot gnu.org
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