On Mon, 23 May 2011, Aldy Hernandez wrote: > This is a patch implementing builtins for an atomic exchange with full, > acquire, and release memory barrier semantics. It is similar to > __sync_lock_test_and_set(), but the target does not have the option of > implementing a reduced functionality of only implementing a store of 1. Also, > unlike __sync_lock_test_and_set(), we have all three memory barrier variants.
What's the reason you've implemented three variants, rather than six (the C1X/C++0X atomics have six memory order values) or one built-in function taking a memory order parameter? More generally, what is the underlying design here for how built-in functions should cover the whole of the new atomics functionality in C1X and C++0X? Adding functions to libgcc-std.ver seems premature in the absence of any library implementations of them. -- Joseph S. Myers jos...@codesourcery.com
