When we talk about memory operation orderings, do we assume X and Y are on different processors?

The read-read reordering can occur when de-referencing a pointer *addr. After we load the value of addr from memory, if the system find out that the content of this address is in the cache, it might directly use the value (instead of reloading from memory).

To answer x2020's question, I think that X and Y can be on the same processor when we are thinking about memory operation orderings. In terms of compilers, this could certainly be the case because in this instance, software is reordering loads/stores that could execute on one processor. For hardware, I suppose it depends on the implementation, but I think that it is possible (even common?) for a single processor to be able to reorder reads/writes at the hardware level.

Seems that only the Wx->Ry order should be preserved?