Subject: Re: bug#2790: emacs 22.1.1 cannot open 5GB file on 64GB 64-bit GNU/Linux box

From: Andreas Schwab <[email-masked]>
Date: Mon, 30 Mar 2009 10:08:10 +0200

Stefan Monnier <[email-masked]> writes:

> I do not know what you're referring to.  If you're referring to the fact
> that (((EMACS_INT)st.st_size)*4) may overflow, then I'm not sure what
> problem you're envisaging:

The compiler can (and does) optimize on the fact that overflow does not
occur, thus the operation x*4/4 becomes a no-op.  Never ever do overflow
checking after the fact.

Andreas.

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Andreas Schwab, [email-masked]
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