From: "H. Peter Anvin" <hpa@zytor.com>
To: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 -tip 0/4] x86: signal handler improvement
Date: Thu, 25 Sep 2008 11:33:19 -0700 [thread overview]
Message-ID: <48DBD96F.6090309@zytor.com> (raw)
In-Reply-To: <48DBD8A6.8060900@ct.jp.nec.com>
Hiroshi Shimamoto wrote:
>>>
>> This is a gcc failure, and should be reported to the gcc people.
>
> Does this gcc failure mean unnecessary storing into stack?
>
Yes, it should be able to process this in a register, instead of storing
to the stack and then merging later.
It's possible it's trying to do that to hide latency, but that's clearly
a lose in this case.
I'd hate to obfuscate the code, and I'd *really* hate to obfuscate the
code to work around gcc brokenness, and then not even bothering to tell
the gcc folks.
-hpa
next prev parent reply other threads:[~2008-09-25 18:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-25 18:08 [RFC PATCH v2 -tip 0/4] x86: signal handler improvement Hiroshi Shimamoto
2008-09-25 18:14 ` H. Peter Anvin
2008-09-25 18:29 ` Hiroshi Shimamoto
2008-09-25 18:33 ` H. Peter Anvin [this message]
2008-09-25 19:38 ` Hiroshi Shimamoto
2008-09-27 17:11 ` Ingo Molnar
2008-09-25 18:18 ` [RFC PATCH v2 -tip 1/4] x86: uaccess: rename __put_user_u64 to __put_user_asm_u64 Hiroshi Shimamoto
2008-09-25 18:18 ` [RFC PATCH v2 -tip 2/4] x86: uaccess: introduce __{put|get}_user_asm_eop Hiroshi Shimamoto
2008-09-25 18:18 ` [RFC PATCH v2 -tip 3/4] x86: uaccess: introduce __{put|get}_user_cerr Hiroshi Shimamoto
2008-09-25 18:18 ` [RFC PATCH v2 -tip 4/4] x86: signal: use __{put|get}_user_cerr Hiroshi Shimamoto
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