[Patch, Darwin, I386] enable mtune=core2 on darwin and make it the default.

[IainS]

Hi HJ,

On 13 Aug 2010, at 18:22, H.J. Lu wrote:

> On Fri, Aug 13, 2010 at 9:39 AM, IainS <developer@sandoe-acoustics.co.uk 
> > wrote:
>> In order to do that it was necessary to get -mtune=core2 to work ..
>> ... this had a couple of residual cases where the use of movq is
>> incompatible with the darwin  assembler.
>
> Do you know -mtune=core generates slower code than -mtune=generic?

I have not benchmarked - unfortunately, we volunteers do not have  
access to SPEC &c.

... but I observe that the code is circa 7% smaller with -mtune=core2  
c.f. generic.
... and we replace all the _pc_thunk calls with a local call and pop -  
which makes quite an impact on our asm.

If you can provide me with a realistic way to perform some suitable  
benchmarks, I will happily do so.
..  otherwise, for the platform, I'm simply making our default the  
same as the vendor's.

It does not, of course, prevent someone from bootstrapping with --with- 
cpu=generic if they wish to.

thanks
Iain