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From: Scott Wood <scottwood@freescale.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] use of C99
Date: Wed, 08 Apr 2009 17:26:10 -0500	[thread overview]
Message-ID: <49DD2482.7040909@freescale.com> (raw)
In-Reply-To: <49DD10BF.80002@freescale.com>

Timur Tabi wrote:
> Scott Wood wrote:
> 
>> It frees the variable up for later such blocks to use.  As does 
>> declaring iterators inside a for loop, but I guess that's forbidden as 
>> well. :-)
> 
> I'm not sure whether we want to allow the same variable to be defined
> more than once, even with the same type, inside a function.

What's wrong with this:?

for (i = 0; i < n; i++) {
	int j;
	...
}

for (i = 0; i < m; i++) {
	int j;
	...
}

>> Chances are it will allocate all stack space for all variables up front, 
>> regardless of where they're declared.
> 
> Yes, but it many cases it won't allocate any stack space at all because
> it will just keep the variable in a register.  My point was that if a
> variable is defined later in a function, then it's more likely to have
> limited scope, so the compiler will be more likely to use a register
> instead of stack to store it.

I don't think it will make a difference.  The compiler knows what the 
lifetime of the variable is, regardless of where you declare it.

-Scott

  reply	other threads:[~2009-04-08 22:26 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-08 18:51 [U-Boot] use of C99 Kumar Gala
2009-04-08 19:28 ` Wolfgang Denk
2009-04-08 19:46   ` Jerry Van Baren
2009-04-08 20:25     ` Timur Tabi
2009-04-08 20:46       ` Premi, Sanjeev
2009-04-08 20:57         ` Timur Tabi
2009-04-08 21:26           ` Premi, Sanjeev
2009-04-08 21:34             ` Timur Tabi
2009-04-08 21:03         ` Ben Warren
2009-04-08 21:23           ` Premi, Sanjeev
2009-04-08 20:52       ` Scott Wood
2009-04-08 21:01         ` Timur Tabi
2009-04-08 22:26           ` Scott Wood [this message]
2009-04-08 21:34       ` Wolfgang Denk
2009-04-08 21:38         ` Timur Tabi
2009-04-08 22:39           ` Graeme Russ
2009-04-08 22:45             ` Timur Tabi
2009-04-08 22:59               ` Wolfgang Denk
2009-04-08 23:09                 ` Scott Wood
2009-04-08 22:28         ` Scott Wood
2009-04-08 21:27     ` Wolfgang Denk
2009-04-08 23:22 ` Larry Johnson
2009-04-08 23:40   ` Scott Wood
2009-04-09  4:27 ` Kumar Gala
2009-04-09 11:38   ` Jerry Van Baren
  -- strict thread matches above, loose matches on Subject: below --
2009-04-09  1:53 Pink Boy
2009-04-09  2:12 ` Jerry Van Baren
2009-04-09  5:50 ` Wolfgang Denk
2009-04-09 13:27   ` Larry Johnson

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