[PATCH, Ada] Fix powerpc-darwin bootstrap with gcc-trunk.

Iain Sandoe iain@codesourcery.com
Sun Mar 29 18:54:00 GMT 2015


Hi Arnaud,

On 29 Mar 2015, at 19:43, Arnaud Charlet wrote:

>> Currently Ada bootstrap is broken for bootstrap compiler == gcc-trunk, and
>> platform == powerpc-darwin9 (although it is possible to bootstrap with
>> gcc-4.9).
>> 
>> The reason is that generations of sinfo.h appears now to _require_ support
>> for atomics (I assume that's intended).
> 
> No, that's definitely not intended, and I doubt this is the case since there
> are other platforms without atomic support.
> 
>> In fact, w.r.t atomics there's no need to treat powerpc-darwin any
>> differently from other ppc platform.
>> 
>> The patch below enables them which restores bootstrap and fixes 15 acts and 8
>> gnat regressions (which essentially, leaves GCC trunk on parity with
>> gcc-4.9 for Ada on the powerpc-darwin9 platform).
>> 
>> This is a bootstrap fail, albeit for an unmentioned target - however, it is
>> entirely local to the platform, so
>> OK for trunk?
> 
> OK on principle, but that doesn't explain the underlying issue you got,
> since atomics should definitely not be needed for bootstrap.
> 
> Can you give more details on the failure you got?

recent trunk (say 221750) built without the patch, is installed and then used as the bootstrap compiler.

At stage #1 the following fail occurs when xsinfo is run to generate sinfo.h:

(cd ada/bldtools/sinfo; gnatmake -q xsinfo ; ./xsinfo sinfo.h )
raised PROGRAM_ERROR : s-atocou.adb:57 explicit raise

Looking at this code, it indicates that it is a dummy implementation for platforms without an atomic increment support.

hence, I concluded (possibly erroneously) that such support is now required in some way.

We can try and analyse further (slowish hardware), if necessary - but this is repeatable on two different setups.

thanks
Iain



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