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Relation between -mcpu and CFLAGS
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Sodki
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PostPosted: Thu Dec 11, 2008 1:14 am    Post subject: Relation between -mcpu and CFLAGS Reply with quote

Hi,

GCC's PowerPC options state that "The -mcpu options automatically enable or disable the following options", with -maltivec being one of the options.

I have a late G4 iBook and I have "-mcpu=7450" on my CFLAGS and I also have -maltivec. But is it really necessary to have -maltivec? How can I know what options the -mcpu option has enabled?

Thank you.
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JoseJX
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Joined: 28 Apr 2002
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PostPosted: Fri Dec 12, 2008 5:25 am    Post subject: Reply with quote

I'm not sure how to show the enabled options, but the GCC manual is probably correct. I think that Altivec being enabled wasn't the default in the past, hence the recommendation.
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Sodki
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PostPosted: Wed Dec 17, 2008 11:40 pm    Post subject: Reply with quote

Just to close this, for those interested, the compilation logic is in GCC's source code, in gcc/config/rs6000/rs6000.c and gcc/config/rs6000/rs6000.h. Sort of. :D

Ah, gcc/config/rs6000/rs6000.opt in interesting too.
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