bison-patches
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: remove unportable casts and storage allocation tricks from Bison


From: Paul Eggert
Subject: Re: remove unportable casts and storage allocation tricks from Bison
Date: Thu, 9 Jan 2003 21:16:42 -0800 (PST)

> From: Akim Demaille <address@hidden>
> Date: Thu, 09 Jan 2003 10:12:47 +0100
> 
>  Paul> Some architectures don't let you compute pointers to places that
>  Paul> aren't really storage.
> 
> I've heard that too, but saw no evidence of this either.

I tracked down one example of an architecture that has the problem:
the 80386 (and later) in 32-bit mode if the large array is allocated
in a separate segment.  In this case the nonconforming pointer
arithmetic can change the segment number causing a segment fault, even
if the resulting pointer is not dereferenced.  The x86 architecture is
still fairly popular, so this is of some practical concern.

> Huh.  Now I think I see what you mean: padding *after* the array
> (pointer) in the struct?

Yes, that's it.




reply via email to

[Prev in Thread] Current Thread [Next in Thread]