Date: Sat, 11 Dec 1999 16:31:35 +0100
From: Xavier Leroy <Xavier.Leroy@inria.fr>
To: David McClain <email@example.com>, firstname.lastname@example.org
Subject: Re: Plea for inline expansion of transcendentals.
In-Reply-To: <000f01bf4246$81914b30$210148bf@dylan>; from David McClain on Thu, Dec 09, 1999 at 06:08:34AM -0700
> Since I do a great deal of bluk math processing, it would sure be nice if
> many of the simpler transcendental functions could be inlined by OCAMLOPT.
> I'm speaking primarily of round_to_int, sin, cos, tan, asin, acos, atan,
> atan2, log, exp, sqrt, etc.
> Of course I am working on Pentium class machines which have these functions
> available in hardware. Other arhitectures might not be so kind in this
One difficulty with the FSIN, FCOS, etc, Pentium instructions is that
they fail if the argument is greater than 2^64 (if I remember
correctly). To produce a correct result in all cases, the error must
be trapped and the operation retried after suitable normalization of
the argument. This makes it difficult to inline those operations.
(Note: I said "correct result", not "meaningful result". No one in
their right minds would compute sin(2^64), but still we have to
produce the same result as everyone else even in this case.)
- Xavier Leroy
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