[Atomics] code stubs for atomic operations

test/mjsunit/harmony/atomics.js

Index: test/mjsunit/harmony/atomics.js
diff --git a/test/mjsunit/harmony/atomics.js b/test/mjsunit/harmony/atomics.js
index 4b9c9f6c663a3951c4dfaeefab6fb211a4ffc810..f835e5f07d7521b958449518d01b5c8a7fd70589 100644
--- a/test/mjsunit/harmony/atomics.js
+++ b/test/mjsunit/harmony/atomics.js
@@ -210,6 +210,24 @@ function clearArray(sab) {
       }
     })
   });
+
+  // Test Smi range
+  (function () {
+    var sab = new SharedArrayBuffer(4);
+    var i32 = new Int32Array(sab);
+    var u32 = new Uint32Array(sab);
+
+    function testLoad(signedValue, unsignedValue) {
+      u32[0] = unsignedValue;
+      assertEquals(unsignedValue, Atomics.load(u32, 0));
+      assertEquals(signedValue, Atomics.load(i32, 0));
+    }
+
+    testLoad(0x3fffffff,  0x3fffffff); // 2**30-1 (always smi)
+    testLoad(0x40000000,  0x40000000); // 2**30 (smi if signed and 32-bits)
+    testLoad(0x80000000, -0x80000000); // 2**31 (smi if signed and 32-bits)
+    testLoad(0xffffffff, -1);          // 2**31 (smi if signed)
+  });
 })();
 
 (function TestStore() {