Re: apple silicon fortran

[Rosemary Mardling <rosemary.mardling@monash.edu>]

Hi everyone,

Still dreaming of buying a MacBook Air with the M1 chip, but still worried I won’t be able to run my fortran codes on it.

Just wondering if you have made progress with a fortran compiler for this new machine? I sure appreciate all your help in January!

Best wishes,
Rosemary



> On 10 Jan 2021, at 6:30 am, Iain Sandoe <idsandoe@googlemail.com> wrote:
> 
> Hi Jim,
> 
> James Secan <james.secan@gmail.com> wrote:
>>> On Jan 9, 2021, at 11:07 AM, Iain Sandoe via Fortran <fortran@gcc.gnu.org> wrote:
> 
>>> I am testing out the Rosetta 2 alternative (which is, AFAIU, a binary-conversion done at install-time native on macOS).
>>> 
>>> Useful to have some fall-back solutions in the short-term, but a native compiler is still the eventual objective.
>> 
> 
>> I would think that running the compiler under Rosetta 2 would still produce a binary that is not compatible with the M1 processor (would it run on a Mac Intel box?).
> 
> Yes, that’s right - it would be an x86_64 compiler, running via Rosetta on Arm64, producing X86_64 object ...
> 
>> Can you run the binary on M1 using Rosetta 2 again?
> 
> … it would seem to defeat some use-case if not - given that the bootstrap succeeded, evidently yes (but perhaps using the JIT mechanism, which might not perform so well)..
> 
>> And my admittedly-shallow understanding of Rosetta 2, isn’t it supposed to generate a new binary the first time a code is run using it, said new binary then being run directly in a subsequent invocation of Rosetta2+userApp?
> 
> Actually, (from limited reading, and likely equally shallow understaning), it seems that this operates two ways;  a one-off when something is installed (so that from then-on one is running native code, with no translation phase).  That’s different from the Rosetta 1 (PowerPC=>X86).
> 
> The second mode is more akin to the Rosetta 1 case, a JIT that is run as needed...
> 
>> I am interested to hear the results of your testing with Rosetta 2.
> 
> I bootstrapped x86_64-apple-darwin20 on aarch64-darwin20.3, and currently running the Fortran testsuite - it’s not clear to me if some of the issues (PIE and no-executable stack) will be sidestepped or not.  We shall see.
> 
> Iain
>