linux-kernel - Re: [RFC PATCH v2 -tip 0/4] x86: signal handler improvement

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Date:	Thu, 25 Sep 2008 11:33:19 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 -tip 0/4] x86: signal handler improvement

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
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