cc -march questions

Scott Bennett bennett at
Fri Sep 4 05:11:51 UTC 2009

     On Thu, 3 Sep 2009 10:28:09 -0400 Daniel Molina Wegener <dmw at>
>2009/9/3 Scott Bennett <bennett at>
>>     What exactly does "cc -march=prescott" enable cc to do?  Does it
>> include
>> instruction scheduling for the pipeline structure of the Prescott CPUs?
>>  Does
>> it include other options, e.g., "-mmmx -msse -msse2 -msse3"?
>>     Thanks in advance for any information on the above!
>According to the GCC manual page, it enables MMX, SSE, SSE2 and SSE3
>instruction set support.
>$ man 1 gcc
     Thanks much for your reply.  This is very bizarre.  I think I've looked
at that page at least 50 times in the past few years and somehow never saw
those lines.  Sigh. :-}
     I've had CPUTYPE=prescott in my /etc/make.conf for a long time now,
and I recently installed math/atlas-devel.  I wonder if specifying
CPUTYPE=prescott may have caused it to choose the wrong components to
include in the final version of libalapack.  If so, then I should rebuild
it without CPUTYPE=prescott.

                                  Scott Bennett, Comm. ASMELG, CFIAG
* Internet:       bennett at                              *
* "A well regulated and disciplined militia, is at all times a good  *
* objection to the introduction of that bane of all free governments *
* -- a standing army."                                               *
*    -- Gov. John Hancock, New York Journal, 28 January 1790         *

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