Clarification on mcpu/tune/arch options

Clarification on mcpu/tune/arch options

[NightStrike]

The gcc manual defines the options mcpu, mtune, and march as being
optimizers for various ARM targets.  It lists viable options, and they
are all ARM related.  However, I often see people using options that
aren't in the manual for targets that the manual says aren't
supported.  For instance, -mcpu=i686, or -march=native.  What is the
nature of this discrepancy between the documentation and what I see as
common usage?

RE: Clarification on mcpu/tune/arch options

[John (Eljay) Love-Jensen]

Hi NightStrike,

> What is the nature of this discrepancy between the documentation and what I see as common usage?

There are different -m options for different hardware models & configurations, that are particular to that hardware model.

http://gcc.gnu.org/onlinedocs/gcc-4.2.2/gcc/Submodel-Options.html

I suspect you are looking at the ARM information:

http://gcc.gnu.org/onlinedocs/gcc-4.2.2/gcc/ARM-Options.html

HTH,
--Eljay

PS:  I think the "m" in "-m" is "machine".  But that's just a guess.

Re: Clarification on mcpu/tune/arch options

[NightStrike]

On Dec 13, 2007 7:21 PM, John (Eljay) Love-Jensen <eljay@adobe.com> wrote:
> Hi NightStrike,
>
> > What is the nature of this discrepancy between the documentation and what I see as common usage?
>
> There are different -m options for different hardware models & configurations, that are particular to that hardware model.
>
> http://gcc.gnu.org/onlinedocs/gcc-4.2.2/gcc/Submodel-Options.html
>
> I suspect you are looking at the ARM information:
>
> http://gcc.gnu.org/onlinedocs/gcc-4.2.2/gcc/ARM-Options.html
>
> HTH,
> --Eljay
>
> PS:  I think the "m" in "-m" is "machine".  But that's just a guess.
>
>

Ah, jeez...  So basically, I totally misread the manual.  Or, more
accurately, I didn't read far enough.  Many thanks for clearing up my
mistake!