processor type.

[David O'Brien]

On Mon, Jan 10, 2005 at 08:16:06AM -0500, David Gilbert wrote:
> I see in the compiler lines crawling by that gcc is asked to optimize
> for 'EV5' while being compatible with 'EV4'.  My Alpha is an EV4 ---
> I'm wondering if I would see better performance with a different flag
> there, but the gcc manual doesn't even acknowledge the existance of
> the options that are in use, let alone the available options.

It doens't???

>From /usr/share/mk/bsd.cpu.mk:
    . elif ${MACHINE_ARCH} == "alpha"
    _CPUCFLAGS = -mcpu=ev4 -mtune=ev5

http://gcc.gnu.org/onlinedocs/gcc-3.4.3/gcc/DEC-Alpha-Options.html#DEC-Alpha-Options
clearly tells:

-mcpu=cpu_type
    Set the instruction set and instruction scheduling parameters for
    machine type cpu_type. You can specify either the EV style name or
    the corresponding chip number. GCC supports scheduling parameters for
    the EV4, EV5 and EV6 family of processors.

-mtune=cpu_type
    Set only the instruction scheduling parameters for machine type
    cpu_type. The instruction set is not changed.


That said, you should remove the -mtune=ev5 or change it to -mtune=ev4.
My guess is you won't notice a difference, but this this change will
produce the best code for your machine.

-- 
-- David  (obrien at FreeBSD.org)