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Date: Mon, 23 Jul 2001 15:50:54 -0600
Message-Id: <200107232150.f6NLosh13126@vindaloo.ras.ucalgary.ca>
From: Richard Gooch <rgooch@ras.ucalgary.ca>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Chris Friesen <cfriesen@nortelnetworks.com>,
        Linus Torvalds <torvalds@transmeta.com>, Jeff Dike <jdike@karaya.com>,
        user-mode-linux-user <user-mode-linux-user@lists.sourceforge.net>,
        linux-kernel <linux-kernel@vger.kernel.org>, Jan Hubicka <jh@suse.cz>
Subject: Re: user-mode port 0.44-2.4.7
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Andrea Arcangeli writes:
> cases if the code breaks in the actual usages of xtime it is likely that
> gcc is doing something stupid in terms of performance. but GCC if it
> wants to is allowed to compile this code:
> 
> 	printf("%lx\n", xtime.tv_sec);
> 
> as:
> 
> 	unsigned long sec = xtime.tv_sec;
> 	if (sec != xtime.tv_sec)
> 		BUG();
> 	printf("%lx\n", sec);

And if it does that, it's stupid. Why on earth would GCC add extra
code to check if a value hasn't changed? I want it to produce
efficient code. What's next? Wrap checking?
    printk ("You've just wrapped an integer: press [ENTER] to confirm,
	    [NT] to ignore   ");

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca
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