

The rep prefix and detecting valgrind (2012) - nkurz
http://repzret.org/p/rep-prefix-and-detecting-valgrind/

======
greglindahl
Self-modifying code is a classic way to observe differences among various
implementations.

As a random example of an emulator that needed this that I found,
[https://github.com/kstenerud/Musashi/tree/master](https://github.com/kstenerud/Musashi/tree/master)
says:

    
    
      - M68K_EMULATE_PREFETCH emulates the 4-word instruction prefetch that
      is part of the 68000/68010 (needed for Amiga emulation).
    

Or, [http://www.atari-forum.com/viewtopic.php?f=68&t=12313](http://www.atari-
forum.com/viewtopic.php?f=68&t=12313) mentions:

    
    
      Instruction Cache
      Self modifying code loops wont work on the 68010+ because
      it's (sic) instruction cache has no writeback stage. You must
      replace all examples of SMC or switch off the I cache.

