Added atomic cmpxchg.

test/atomic.py

@@ -0,0 +1,36 @@
+from llvm.core import *
+import unittest
+
+test_these_orderings = filter(bool, map(lambda s:s.strip(),
+'''
+unordered
+monotonic
+acquire
+release
+acq_rel
+seq_cst
+'''.splitlines()))
+
+class TestAtomic(unittest.TestCase):
+    def test_atomic(self):
+        mod = Module.new('mod')
+        functype = Type.function(Type.void(), [])
+        func = mod.add_function(functype, name='foo')
+        bb = func.append_basic_block('entry')
+        bldr = Builder.new(bb)
+        ptr = bldr.alloca(Type.int())
+
+        old = bldr.load(ptr)
+        new = Constant.int(Type.int(), 1234)
+
+
+        for ordering in test_these_orderings:
+            inst = bldr.atomic_cmpxchg(ptr, old, new, ordering)
+            self.assertEqual(ordering, str(inst).split(' ')[-1])
+
+
+        inst = bldr.atomic_cmpxchg(ptr, old, new, ordering, crossthread=False)
+        self.assertEqual('singlethread', str(inst).split(' ')[-2])
+
+if __name__ == '__main__':
+    unittest.main()