Re: defaults for -march and -mtune

Re: defaults for -march and -mtune

[Jay Foad]

Marcin MirosÅaw wrote:
> Try: gcc -Q --help=target 2>&1|grep  "march\|mtune"

Thanks! It's a shame it doesn't work on GCC 4.1.2 as well...

Thanks,
Jay.

Re: defaults for -march and -mtune

[Marcin Mirosław]

W dniu 24.11.2011 13:50, Jay Foad pisze:
> Marcin MirosÃ…aw wrote:
>> Try: gcc -Q --help=target 2>&1|grep  "march\|mtune"
>
> Thanks! It's a shame it doesn't work on GCC 4.1.2 as well...

If you want to know what is default target for older gcc you can do such 
trick:
$ touch a.c
$ gcc -fverbose-asm -S a.c -o - |grep "march\|mtune"
(founded on gcc mailinglist)
Regards

Re: defaults for -march and -mtune

[Ryan Hill]

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On Thu, 24 Nov 2011 16:10:10 +0100
Marcin Mirosław <marcin@mejor.pl> wrote:

> W dniu 24.11.2011 13:50, Jay Foad pisze:
> > Marcin MirosÅaw wrote:
> >> Try: gcc -Q --help=target 2>&1|grep  "march\|mtune"
> >
> > Thanks! It's a shame it doesn't work on GCC 4.1.2 as well...
> 
> If you want to know what is default target for older gcc you can do such 
> trick:
> $ touch a.c
> $ gcc -fverbose-asm -S a.c -o - |grep "march\|mtune"
> (founded on gcc mailinglist)

Or `echo "" | gcc -v -E - 2>&1 | grep cc1`


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defaults for -march and -mtune

[Jay Foad]

If I don't specify any -march= or -mtune= options, what are the
default architectures to generate code for and to tune for? Can I get
the compiler to tell me this information?

The documentation here doesn't seem to say anything about it:

http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86_002d64-Options.html

I'm using "gcc (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1" targetting x86_64.

Thanks,
Jay.

Re: defaults for -march and -mtune

[Marcin Mirosław]

W dniu 24.11.2011 11:37, Jay Foad pisze:
> If I don't specify any -march= or -mtune= options, what are the
> default architectures to generate code for and to tune for? Can I get
> the compiler to tell me this information?
>
> The documentation here doesn't seem to say anything about it:
>
> http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86_002d64-Options.html
>
> I'm using "gcc (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1" targetting x86_64.

Hello!
Try: gcc -Q --help=target 2>&1|grep  "march\|mtune"
Regards