This patch adds a new Ir-Ir pass in the PPC back-end that expands memcpy calls. There are 2 types of expansion added:
- calls where the size is a known compile time constant, but are large enough that we either don't want to or wont expand them with the straight line expansion.
- Expand calls where the size isn't a compile time constant.
This patch is to be followed up with a subsequent patch which will leverage pgo profiling data to make better decisions about when and under what conditions to actually perform these expansions.