icedtea zero ARM atomic patch

[Gary Benson]

Xerxes Rånby wrote:
> Here is a patch for the ARM zero port to deal with missing atomic
> operations in the ARM hardware, here implemented using linux-
> kernelcalls.  With this patch the zero hotspot and bootstrap-ecj
> part of icedtea6 do compile on ARM targets.

I committed a reworked version of the first part of this patch.
I've left the second part out as I don't think it's used -- you'll
get an "unimplemented" message if it is.

FWIW I'm not entirely convinced that the arm-specific functions
are doing what they ought; arm_add_and_fetch and arm_lock_test_and_set
seem to be dereferencing a volatile pointer twice, which doesn't seem
atomic to me.  But then I'm not great at this stuff either :)

Cheers,
Gary

-- 
http://gbenson.net/