gcc doesn't enable the right flags for a given arch

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gcc -xc -c - -march=core2 -Q --help=target

this prints out a set of options that is not even close to what the targeted arch ( mtune doesn't work either ) is able to do, needless to say that I have already tried to input several other valid options for the -march flag without any good results, gcc always prints the same setup.

Are this flags deprecated ? For what I know mcpu is deprecated, this ones should still be able to do their work, right ?

I was hoping to save some time in tuning the right flags for each platform, and this is a really weird behaviour.

I'm under Ubuntu Saucy 64 bit with gcc 4.8.1 .

I can't even find a way to display the enabled flags with clang so I'm stuck either way with this and I don't get what is possibly wrong .

my reference for this .

asked 49 secs ago

user2485710

2,235