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