On PowerPC, VSRpRC represents the pairs of even and odd VSX register ((vs0, vs1), (vs2, vs3), ...).VRRC means the latter 32 registers in VSRC. So in some cases, when we're handling incoming VRRC arguments with VSRpRC, extra copies are produced.
This patch changes the allocation order of VSRpRC to put latter 32 ones first. This should not affect ACC/UACC since they only own the first 32 VSX registers.
Please explain the strange allocation order with something like: