Removed unused code

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Refactor code that does node replacement to a more general type into a method

the method returns the new node, and allows for an invocation of the general execution method.

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Added some SlowPath annotations

This was tricky, SlowPath annotations can cause Graal to not see what is happening to a virtual frame.

Signed-off-by: Stefan Marr <git@stefan-marr.de>