Re: static estimation of conditional branches?

hrubin@pop.stat.purdue.edu (Herman Rubin) writes:
>... the programmer should have some way of communicating this, and other,
>frequency considerations to the compiler. As far as I know, this has not
>been done since the "FREQUENCY" statement in fairly early Fortran.
>[As I recall, Fortran II dropped FREQUENCY because it was infrequently
>used and made little difference. I've heard that it may even have been
>implemented backwards and nobody noticed. -John]


The other problem that occurs with such facilities is that programmer
intuition is notoriously unreliable about such things.


Now, if you amend Herman's statement to "the *profiler* should have some
way of communicating this...", I'd agree... and observe that there are
already compilers that will accept profiler data and exploit it for
optimization. I don't know whether they do this particular optimization,
but I wouldn't be surprised.
--
Henry Spencer @ U of Toronto Zoology, henry@zoo.toronto.edu utzoo!henry
--

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