Version française
Home     About     Download     Resources     Contact us    

This site is updated infrequently. For up-to-date information, please visit the new OCaml website at

Browse thread
Ocamlopt code generator question
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: 2009-05-10 (23:13)
From: Matteo Frigo <athena@f...>
Subject: Re: [Caml-list] Ocamlopt x86-32 and SSE2
Do you guys have any sort of empirical evidence that scalar SSE2 math is
faster than plain old x87?

I ask because every time I tried compiling FFTW with gcc -m32
-mfpmath=sse, the result has been invariably slower than the vanilla x87
compilation.  (I am talking about scalar arithmetic here.  FFTW also
supports SSE2 2-way vector arithmetic, which is of course faster.)

I also remember trying similar experiments with other numerical code in
the Pentium 4 dark ages, with similar results.  I don't see any reason
why this should be the case, and maybe this is just a problem of gcc,
but I don't think you should automatically assume that SSE2 math is
faster without running a few experiments first.

Matteo Frigo