[patch, make machinery, plugins] enable plugins for powerpc-apple-darwin

[IainS]

On 13 May 2010, at 16:24, Richard Guenther wrote:

> On Thu, May 13, 2010 at 4:50 PM, IainS <developer@sandoe-acoustics.co.uk 
> > wrote:
>>
>> On 13 May 2010, at 15:22, Richard Guenther wrote:
>>
>>> On Thu, May 13, 2010 at 3:57 PM, IainS <developer@sandoe-acoustics.co.uk 
>>> >
>>> wrote:
>>>>
>>>> Since we use "-mdynamic-no-pic" by default when building gcc on  
>>>> darwin,
>>>> and
>>>> this conflicts with fPIC (needed for plugins),  we need different  
>>>> flags
>>>> when
>>>> building (and testing for ability to build) plugins.
>>>>
>>>> the change to gcc/configure.ac deals with this for the test phase  
>>>> (and
>>>> actually ensures that fPIC is passed in CFLAGS for other targets  
>>>> too).
>>>
>>> Why do you need to do that change?
>>
>> without this the test fails (mdynamic-no-pic conflicts with fPIC  
>> producing a
>> warning) and plugin support is disabled after stage1.
>>
>> mdynamic-no-pic is added to BOOT_CFLAGS in config/mh-ppc-darwin  
>> with the
>> comment that it produces 3..5% improvement in compile performance,  
>> thus I am
>> loath to remove it completely.
>>
>> If you mean why add fPIC to CFLAGS for other targets? - just for  
>> tidiness
>> sake (I meant to remove it from LDFLAGS too).
>
> Yes.  -fPIC will slow down the compiler for no reason.

It is only present during the plugin test - and the comment in  
configure.ac says it is required for plugins.
(the purpose of the test is to check that it succeeds)

the prevailing CFLAGS are restored as soon as the plugin test is  
complete.

however, its easily deleted if that's the only objection to the patch.

iain

>>
>>>> I've put a filter in config/x-darwin to remove the "-mdynamic-no- 
>>>> pic"
>>>> from
>>>> PLUGINCFLAGS since, at present, there is no mechanism to specify  
>>>> these
>>>> separately - since they are substituted from:
>>>>  PLUGINCFLAGS = @CFLAGS@
>>>>
>>>> (I wonder if the latter was really intended)
>>>>
>>>> ===
>>>>
>>>> With this patch all the gcc plugins pass..
>>>> ... unfortunately, some of the g++ ones do not - although AFAICT  
>>>> those
>>>> fails
>>>> are not due to build issues (they fail at runtime rather than
>>>> build-time).
>>>>
>>>> [all the plugins pass for powerpc64-apple-darwin, if that provides
>>>> additional clues...].
>>>>
>>>> (to run the plugins also requires :
>>>> http://gcc.gnu.org/ml/gcc-patches/2010-05/msg00872.html  )
>>>>
>>>> ===
>>>>
>>>> OK for trunk ?
>>>>
>>>> Iain
>>>>
>>>> gcc/Changelog:
>>>>
>>>>       * configure.ac: Strip "-mdynamic-no-pic" from CFLAGS when  
>>>> testing
>>>> for
>>>> plugin capability on Darwin.
>>>>       * configure: Regenerated.
>>>>       * config/x-darwin: Strip  "-mdynamic-no-pic" from  
>>>> PLUGINCFLAGS.
>>>>
>>>>
>>>>
>>>>
>>>>
>>
>>