28 Apr
2008
28 Apr
'08
2:01 p.m.
Henning Westerholt schrieb:
Hi Christian,
i think the correct statement for (a recent) 3.X gcc would be
either 'mcpu=prescott' or 'mtune=prescott'. I don't know why march is
used in
this case, for the x86_64 case its correct. Then the compiler will only
optimize for this special processor, but the code will nevertheless run on
i386 machines too.
The 'prescott' type is unfortunally not available on older gcc, so i
used 'pentium4' instead. I'll make a fix on svn, could you perhaps test
this?
Thank you,
Henning
Hi Henning,
you're right. The manpage of gcc says for mtune:
While picking a specific cpu-type will schedule things appropriately
for that particular chip, the compiler will not generate any code
that does not run on the i386 without the -march=cpu-type option
being used.
But as I have a Pentium III, I wouldn't benefit of "mtune=prescott",
although the compiled code will run on my machine, of course. I think
the correct way would be to have a configure script determining the CPU
type and using that type for mtune (I know, that would be a lot of
work....).
When you fixed the Makefile in SVN, just tell me, so I can test it.
Christian