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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/51821] [4.5/4.6/4.7 Regression] 64bit > 32bit conversion produces incorrect results with optimizations
Date: Wed, 11 Jan 2012 12:34:00 -0000 [thread overview]
Message-ID: <bug-51821-4-qRWmAzUwbK@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-51821-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51821
--- Comment #3 from Uros Bizjak <ubizjak at gmail dot com> 2012-01-11 12:33:59 UTC ---
(In reply to comment #2)
> I believe this is a target issue. We produce
>
> test:
> .LFB0:
> .cfi_startproc
> movl 4(%esp), %ecx
> movl $-1, %eax
> xorl %edx, %edx
> sall %cl, %eax
> testb $32, %cl
> cmovne %eax, %edx <-- wrong
> cmovne %edx, %eax
> ret
>
> but as this is a SHIFT_COUNT_TRUNCATED target the sall instruction does
> nothing, so shifting DImode by 32 is not implemented correctly on i?86
> (ix86_split_ashl).
There is one cmovne too much. -O2 -m32 -msse2 is needed to trigger this bug,
without cmove we produce correct code.
next prev parent reply other threads:[~2012-01-11 12:34 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-11 11:02 [Bug c/51821] New: " nos.utelsystems at gmail dot com
2012-01-11 11:21 ` [Bug c/51821] [4.5/4.6/4.7 Regression] " rguenth at gcc dot gnu.org
2012-01-11 11:28 ` [Bug target/51821] " rguenth at gcc dot gnu.org
2012-01-11 12:34 ` ubizjak at gmail dot com [this message]
2012-01-11 13:13 ` ubizjak at gmail dot com
2012-01-11 13:21 ` [Bug rtl-optimization/51821] " ubizjak at gmail dot com
2012-01-11 14:15 ` ubizjak at gmail dot com
2012-01-11 22:03 ` ebotcazou at gcc dot gnu.org
2012-01-11 22:35 ` ubizjak at gmail dot com
2012-01-11 22:57 ` ubizjak at gmail dot com
2012-01-12 7:44 ` ebotcazou at gcc dot gnu.org
2012-01-12 8:04 ` ubizjak at gmail dot com
2012-01-12 11:18 ` ebotcazou at gcc dot gnu.org
2012-01-12 11:35 ` ubizjak at gmail dot com
2012-01-12 11:42 ` ubizjak at gmail dot com
2012-01-12 13:20 ` ebotcazou at gcc dot gnu.org
2012-01-12 17:01 ` ubizjak at gmail dot com
2012-01-12 17:36 ` ubizjak at gmail dot com
2012-01-12 19:18 ` ubizjak at gmail dot com
2012-01-15 18:45 ` uros at gcc dot gnu.org
2012-01-15 20:02 ` uros at gcc dot gnu.org
2012-01-15 20:38 ` uros at gcc dot gnu.org
2012-01-15 21:01 ` uros at gcc dot gnu.org
2012-01-15 21:14 ` ubizjak at gmail dot com
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