GFortran 44 optimizations and Intel SSE4

[Tim Prince]

On 11/1/2011 12:42 PM, Jacob Anderson wrote:
> Hi,
>
> Thanks for the responses! Yes, I did mean the "-Ox" generic options.
>
> We are compiling against Intel X5670 and X5620, so no desktop architectures.  The "SSE4.2" extensions are of interest for their vector capabilities. Is there any online documentation on the optimization algorithms used when the SSE4 optimizations are enabled?
>
> We are using gfortran44 version 4.4.4 20100726:
>
> GNU Fortran (GCC) 4.4.4 20100726 (Red Hat 4.4.4-13)
> Copyright (C) 2010 Free Software Foundation, Inc.
>
> Thanks
>
> -- jake
>
>
>
>> -----Original Message-----
>> From: fortran-owner@gcc.gnu.org [mailto:fortran-owner@gcc.gnu.org] On
>> Behalf Of Tim Prince
>> Sent: Tuesday, November 01, 2011 9:28 AM
>> To: fortran@gcc.gnu.org
>> Subject: Re: GFortran 44 optimizations and Intel SSE4
>>
>> On 11/1/2011 11:42 AM, Jacob Anderson wrote:
>>
>>>
>>> Does the general optimization option to gfortran44 include Intel SSE4
>> optimizations (4.1 AND 4.2)?
>>>
>>
>> Perhaps that's not what you meant to ask? By general, do you mean
>> generic (definitely not including -msse4)?
>>
>> http://gcc.gnu.org/onlinedocs/gcc-4.4.6/gcc/i386-and-x86_002d64-
>> Options.html#i386-and-x86_002d64-Options
>>
>> -msse4.1 and -msse4.2 are listed there.
>>
>>    -mtune=barcelona , which you might use for Core I7 (with or without
>> -msse4), if you don't want to use a current gfortran, is listed there.
>>
>> --

Oh, just in case, auto-vectorization is enabled either by setting -O3 or 
by adding -ftree-vectorize to the options list at -O2 or -O1.  For 
myself, I've got improved results on the Xeon 5500 and 5600 series by 
adding -funroll-loops --param max-unroll-times=4


-- 
Tim Prince