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To: Horst von Brand <brand@jupiter.cs.uni-dortmund.de>
Cc: Art Haas <ahaas@airmail.net>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       brand@eeyore.valparaiso.cl
Subject: Re: Is -fno-strict-aliasing still needed?
X-Yow: Who wants some OYSTERS with SEN-SEN an' COOL WHIP?
From: Andreas Schwab <schwab@suse.de>
Date: Tue, 11 Feb 2003 10:45:19 +0100
In-Reply-To: <200302110939.h1B9dX6T013616@eeyore.valparaiso.cl> (Horst von
 Brand's message of "Tue, 11 Feb 2003 10:39:33 +0100")
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Horst von Brand <brand@jupiter.cs.uni-dortmund.de> writes:

|> Andreas Schwab <schwab@suse.de> said:
|> > Horst von Brand <brand@jupiter.cs.uni-dortmund.de> writes:
|> > 
|> > |> Art Haas <ahaas@airmail.net> said:
|> > |> > I ask because I've just built a kernel without using that flag -
|> > |> > linus-2.5 BK from this morning, probably missing the 2.5.60 release by
|> > |> > a few hours.
|> > |> 
|> > |> The problem with strict aliasing is that it allows the compiler to assume
|> > |> that in:
|> > |> 
|> > |>      void somefunc(int *foo, int *bar)
|> > |> 
|> > |> foo and bar will _*never*_ point to the same memory area
|> > 
|> > This is wrong.  Only if they are declared restrict.
|> 
|> ... can they point to the same area. That is exactly the problem: If you do
|> nothing, the language definition assumes the programmer made sure (LOL!)
|> that they don't point the same way.

Why are you insisting on spreading misinformation?

Pointers that are _not_ declared as restricted can alias _any_ other
non-restricted pointer of the same target type.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 N?rnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."
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