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Re: Crashes in "C-h h"

From: Eli Zaretskii
Subject: Re: Crashes in "C-h h"
Date: Sat, 06 Jul 2019 10:08:13 +0300

> Cc: address@hidden
> From: Paul Eggert <address@hidden>
> Date: Fri, 5 Jul 2019 20:42:09 -0700
> > The comparison with
> > 
> >     if (FIXNUMP (x) && XFIXNUM (x) == n)
> > 
> > is IMO not useful, because it should be clear up front that it will
> > always lose due to the additional test.
> I suspect much of this thread is due to a misunderstanding then, as I 
> interpreted your earlier comment "It normally shouldn't matter either way" to 
> mean the opposite

Sorry about that.  I should have been clearer in my wording.

The original code there was just

  if (XFIXNUM (x) == y)

so that was my reference point for judging performance.

> It is amusing that those benchmarks yield such wildly-different
> results on different CPUs, though.

That's a mystery in itself, yes.  Whether we want to pursue it is
another matter, as it seems to involve subtle aspects of code
generation on modern CPUs, something we aren't the best specialists

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