Re: [PATCH] Avoid -lm and -lpthread in libjava on darwin

[IainS <developer@sandoe-acoustics.co.uk>]

On 12 Aug 2010, at 22:38, Jack Howarth wrote:

> On Thu, Aug 12, 2010 at 11:09:46PM +0200, Ralf Wildenhues wrote:
>> * Andrew Pinski wrote on Thu, Aug 12, 2010 at 08:23:13PM CEST:
>>> On Thu, Aug 12, 2010 at 11:20 AM, Richard Henderson  
>>> <rth@redhat.com> wrote:
>>>> Is this patch necessary with the remove-outfile patch in place?
>>>
>>> Yes because libtool calls ld directly for libjava.  I wish it did  
>>> not
>>> but it does.
>>
>> * Jack Howarth wrote on Thu, Aug 12, 2010 at 08:24:30PM CEST:
>>> The remove-outfile patch is necessary to make sure that the gcc
>>> compilers don't shift libSystem forward in the linkage and
>>> disrupt the logic behind libgcc_ext when -ldl, -lm or -lpthread
>>> is passed to the compiler. The libjava patch covers the hardcoding
>>> of -lpthread and -lm into the linker flags that are passed via
>>> libtool directly to the linker.
>>
>> So do I understand correctly that this ought to be fixed in libtool?
>> Is the requirement to have libSystem last one that is specific to GCC
>> or common to all software built with GCC?

one can say for certain that specifying those libraries is unnecessary  
for Darwin >= 8
(so long as the compiler is using the same specs as gcc which place - 
lSystem as the last item)
If one is linking statically, which is only done for kernel code  
AFAIK, then you need to provide your own static libc anyway.

therefore, those rules could be changed as libtool is updated.

---

as far as link order goes, it's less clear where the issue arises with  
libjava, in principle  the two-level namespace in darwin should deal  
with it.

One thing I'm investigating is that, the libjava spec intercepts % 
(lib) rather than %(libgcc) which does not produce the same effect on  
darwin as other systems since we use   %G %L
and not %L %G %L

Still trying to track down what's happening...

as Jack says, at least putting libgcc before libSystem bypasses the  
buggy math routine.

cheers
Iain