// On ARM, 386, and 32-bit MIPS, it is the caller's responsibility to arrange
// for 64-bit alignment of 64-bit words accessed atomically via the primitive
// atomic functions (types Int64 and Uint64 are automatically aligned).
-// The first word in a variable or in an allocated struct, array, or slice can
-// be relied upon to be 64-bit aligned.
+// The first word in an allocated struct, array, or slice; in a global
+// variable; or in a local variable (because the subject of all atomic operations
+// will escape to the heap) can be relied upon to be 64-bit aligned.
// SwapInt32 atomically stores new into *addr and returns the previous *addr value.
func SwapInt32(addr *int32, new int32) (old int32)