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Re: C Compiler benchmark: gcc 4.6.3 vs. Intel v11 and others

On 1/19/2012 2:59 AM, Richard Guenther wrote:
On Thu, Jan 19, 2012 at 7:37 AM, Marc Glisse<> wrote:
On Wed, 18 Jan 2012, wrote:

For those who might be interested, I've recently benchmarked gcc 4.6.3
(and 3.4.2) vs. Intel v11 and Microsoft (in Windows 7) here:

For the math functions, this is normally more a libc feature, so you might
get very different results on different OS. Then again, by using
-ffast-math, you allow the math functions to return any random value, so I
can think of ways to make it even faster ;-)
Also for math functions you can simply substitute the Intel compilers one
(GCC uses the Microsoft ones) by linking against libimf.  You can also make
use of their vectorized variants from GCC by specifying -mveclibabi=svml
and link against libimf (the GCC autovectorizer will then use the routines
from the Intel compiler math library).  That makes a huge difference for
code using functions from math.h.


Marc Glisse
Thank you both for the tips. Are you certain that with the flags I used Intel doesn't completely in-line the math2.h functions at the compile stage? gcc? I take it to use libimf.a (legally) I would have to purchase the Intel compiler?

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