Re: [PATCH, DARWIN] fix emutls exports in libgcc_s10.{4,5}.dylib

[Jack Howarth <howarth at bromo dot med dot uc dot edu>]

Iain,
   In a perfect world, the real solution to this would be for
Apple to create a new libgcc_s.10.6.dylib which contained the
missing symbols for the newer FSF gcc releases. However since
Apple won't touch GPLv3, this is impossible since it would
require their adopting the libgcc from gcc 4.3 or 4.4 for
Snow Leopard.
                            Jack

On Thu, Dec 11, 2008 at 05:29:16PM +0000, IainS wrote:
>
> On 11 Dec 2008, at 13:51, Jack Howarth wrote:
>
>> On Thu, Dec 11, 2008 at 12:38:11PM +0000, IainS wrote:
>> ...
>>>
>>> I have a hunch that this is, at least partially, the origin of  
>>> sporadic
>>> failures in crayptr2 (which has been one of the very few tests using 
>>> tls
>>> so far - because all the rest have been UNSUPPORTED by the fails in 
>>> dg
>>> target supports).
>> ...
>>
>> No. The random failures in crayptr2 are due to multiple threads  
>> reading
>> an offset value of 0 and is fixed by the proposed patch...
>>
>> http://gcc.gnu.org/bugzilla/attachment.cgi?id=16879
>
> actually, the deeper one digs ...
>
> it seems that libgomp is not being built with tls emulation.
>
> (for exactly the same reasons - the configure test fails with the  
> unresolved __emutls...  symbol)
>
> from libgomp/config.h
> /* Define to 1 if the target assembler supports thread-local storage. */
> /* #undef HAVE_CC_TLS */
>
> ....
>
> /* Define to 1 if the target supports thread-local storage. */
> /* #undef HAVE_TLS */
>
> and libgomp/config.log
>
> tchCS/gcc-440-install/powerpc-apple-darwin8.11.0/sys-include -o conftest 
> -g -O2   -pthread   conftest.c  >&5
> /usr/libexec/gcc/powerpc-apple-darwin8/4.0.1/ld: Undefined symbols:
> ___emutls_get_address
> collect2: ld returned 1 exit status
> configure:17892: $? = 1
> configure: program exited with status 1
> configure: failed program was:
> | __thread int a; int b; int main() { return a = b; }
> configure:18104: result: no
>
>
> ----
>
> So, I guess,  the libgomp tests should not be built with TLS emulation ; 
> and any test requiring TLS should be hidden behind a
> { dg-require-effective-target tls_runtime }
>
> which was a proposal anyway ( http://gcc.gnu.org/ml/fortran/2008-12/ 
> msg00155.html).
>
> ----
>
> at least this will be consistent until such time as a general solution to 
> making the emulation available is agreed.
>
> (and that means addressing the general issues I raised earlier).
>
> Iain