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To: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Davide Libenzi <davidel@xmailserver.org>, Ingo Molnar <mingo@elte.hu>,
       Jeff Garzik <jgarzik@pobox.com>, Greg KH <greg@kroah.com>,
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Subject: Re: MSEC_TO_JIFFIES is messed up...
References: <20040512020700.6f6aa61f.akpm@osdl.org>
	<20040512181903.GG13421@kroah.com> <40A26FFA.4030701@pobox.com>
	<20040512193349.GA14936@elte.hu>
	<Pine.LNX.4.58.0405121247011.11950@bigblue.dev.mdolabs.com>
	<20040512200305.GA16078@elte.hu>
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	<20040512213913.GA16658@fieldses.org>
From: Andreas Schwab <schwab@suse.de>
X-Yow: Where's th' DAFFY DUCK EXHIBIT??
Date: Wed, 12 May 2004 23:55:18 +0200
In-Reply-To: <20040512213913.GA16658@fieldses.org> (J. Bruce Fields's
 message of "Wed, 12 May 2004 17:39:13 -0400")
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"J. Bruce Fields" <bfields@fieldses.org> writes:

> If gcc really optimizes that to just the identity function, then surely
> that's a gcc bug?  Multiplication is left-associative, so i * 1000 /
> 1000 = (i * 1000) / 1000, but (i * 1000) should be zero for any i
> divisible by i^(sizeof(int) - 12).

Signed integer overflow is undefined in C, so the compiler is allowed to
assume it does not happen.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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