The attached patch replaces the conditional branch tests in atomic_compare_and_exchange_val_acq with
conditional instruction nullification.  This avoids the stalls associated with conditional branches and the resulting
code is shorter.  There are no branches in the fast path when the operation is successful.

The change was intended as an optimization but tst-stack4 now passes.

Please install.

Thanks,
Dave
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John David Anglin	dave.anglin@bell.net