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

[willus.com]

On 1/19/2012 2:59 AM, Richard Guenther wrote:
> On Thu, Jan 19, 2012 at 7:37 AM, Marc Glisse<marc.glisse@inria.fr>  wrote:
>> On Wed, 18 Jan 2012, willus.com 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:
>>>
>>> http://willus.com/ccomp_benchmark2.shtml
>>
>> http://en.wikipedia.org/wiki/Microsoft_Windows_SDK#64-bit_development
>>
>> 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.
>
> Richard.
>
>> --
>> 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?