Re: Is -fno-strict-aliasing still needed?

[Andreas Schwab <schwab@suse.de>]

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.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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