[R-SIG-Win] Default mtune for R windows

[Uwe Ligges]

On 01.02.2017 05:31, Avraham Adler wrote:
> I put in a bug request for this over a year ago and it went nowhere.
> Nobody is using a core2 on Windows anymore. GCC itself has been
> suggesting for a very long time to use '-mtune=generic'. Their
> language on 4.9.3. is:
>
> ‘generic’ Produce code optimized for the most common IA32/AMD64/EM64T
> processors. If youknow the CPU on which your code will run, then you
> should use the corresponding -mtune or -march option instead of
> -mtune=generic. But, if you do not know exactly what CPU users of your
> application will have, then you should use this option.
>
> As new processors are deployed in the marketplace, the behavior of
> this option will change. Therefore, if you upgrade to a newer version
> of GCC, code generation controlled by this option will change to
> reflect the processors that are most common at the time that version
> of GCC is released.
>
>
> How difficult is it to change that line in Mkrules.dist/Mkrules.rules?

That is not the problem.

For the last transition, a lot of testing, adatptions to R, and a lot of 
third party software had to be rebuild.
Thanks to Jeroen Ooms, Duncan Murdoch, Jim Hester and several others it 
was possible to get most of that done within half a year or so. Even if 
the next transition works more smoothly and faster, it is still a 
considerable amount of work to get the 10000 CRAN and also several 
thousand BioC packages to a state they work with a current compiler 
collection on Windows and (if necessary) rebuild third party tools.

Best,
Uwe Ligges




>
> Avi
>
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