Handling large memory reference operand in pattern mode

_From [zhao...@google.com](https://code.google.com/u/106321947286816917100/) on February 06, 2012 14:24:04_

In pattern mode, if a memory reference is accessing more than 4-byte, e.g. multimedia instrs, we only check the first 4-byte. It would nice if we can check all the memory that being referenced, but efficiency is another consideration.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=774_