Transparency Issue on Handling YMM registers

From zhao...@google.com on December 15, 2011 15:34:42

xref issue #437 (closed) The first execution of AVX instruction in a thread will change the processor state. So if blindly save and restore YMM register using AVX instruction will cause transparency issue.

One solution is to use and conditional check to decide if YMM is need save or not. However, if using thread-shared code cache, how can we tell if a thread has executed any AVX instruction before?

Original issue: http://code.google.com/p/dynamorio/issues/detail?id=639