Pin-based ChampSim Traces consider x86 partial registers to be independent #575

Describe the bug
ChampSim traces created using the Intel Pin tracer use the values from the REG enum, which assign unique values to (for example) AX/AH/AL/EAX/RAX, and similarly to RSP/ESP/SP and others, like the AVX registers.

To Reproduce
N/A

Expected behavior
Currently, this causes register usage to be quite high, as in my own testing on the SPEC traces, I see upwards of 90 unique register identifiers in use, whereas there should only be around 40-50 or so. While register dependency chains of mixed-size are not very common, this is incorrect behavior.

Proposed fix
In the instruction intake function, at runtime, alias the partial register reference values to that of their respective parent registers. For example, AH, AL, AX, and EAX would all use the same identifier as RAX.