If the destination isn't any of the incoming sources then we can avoid
one of the moves at the end. This half works around the problem proposed
in #3794, but doesn't solve the entire problem.
To solve the other half of the moving problem means we need to solve the
SRA allocation problem for this temporary register with addsub/subadd, so it gets allocated
for both the FMA operation and the XOR operation.
Ryan Houdek
62cec7b6b2