Re: Crashes in "C-h h"

[Paul Eggert <eggert@cs.ucla.edu>]

Eli Zaretskii wrote:
> It is not useful to compare to a function that does nothing.

It's standard in benchmarking to do that, to try to distinguish the overhead of 
running the benchmark from the code one is actually trying to measure.

> Useful
> comparisons would be with functions that do this:
> 
>   return x == y;

That depends on what one means by "useful". I was trying to compare the 
performance of EQ+make_fixnum to that of FIXNUMP+XFIXNUM, not to that of ==.

> comparing with make_fixnum, i.e.
> 
>     EQ (x, make_fixnum (n))
> 
> is TRT when you are NOT certain that X is a fixnum ...
> If you ARE certain that X is a fixnum, then
> 
>     XFIXNUM (x) == n
> 
> is also OK.

Yes, that's right.

> 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, which is why I ran the benchmarks. Apparently my 
interpretation was a misunderstanding of what you intended. It is amusing that 
those benchmarks yield such wildly-different results on different CPUs, though.