[Bug c/43553] libgcc built with -DHAVE_CC_TLS against xgcc when emutls in use

[developer at sandoe-acoustics dot co dot uk]

------- Comment #17 from developer at sandoe-acoustics dot co dot uk  2010-04-01 08:02 -------
AFAICT the root problem does not relate to export of symbols from emutls (or to
its use).  Although this perhaps needs a different PR

The root problem is that the emutls implementation generates symbols in the
data area that are (AFAICT) translated into thread-unique addresses by
_emutls_get_address.

The two symbols in question are declared static and private and are being
optimized away.   (you will find that the profile tests work at -O0).

I am not sure why they are being optimized away when there is a reference to
them in the asm file -- see (b) below.

The variables need to be preserved and coalesced within one binary.

a/ A work-round solution is to mark the two variables PUBLIC and COMMON.  I've
tested that this works on i686-apple-darwin and ia32-pc-linux .... BUT....

b/ Looking at http://gcc.gnu.org/ml/gcc/2010-03/msg00482.html

It is perhaps the case that other attributes are not being copied that are
causing this problem.

Of course, maybe this is also a limitation of emutls.

I don't have time to do much on this today -- and the trunk freeze is fast
approaching.. input from more experienced would be welcome...


-- 

developer at sandoe-acoustics dot co dot uk changed:

           What    |Removed                     |Added
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                 CC|                            |developer at sandoe-
                   |                            |acoustics dot co dot uk


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43553