MIPS: DSPr2: Added over_n_8_8888 and over_n_8_0565 fast paths.
Performance numbers before/after on MIPS-74kc @ 1GHz
Referent (before):
lowlevel-blt-bench:
over_n_8_8888 = L1: 10.40 L2: 9.79 M: 8.47 ( 33.62%) HT: 7.64 VT: 7.59 R: 7.48 RT: 5.30 ( 40Kops/s)
over_n_8_0565 = L1: 7.40 L2: 7.23 M: 6.78 ( 17.94%) HT: 6.23 VT: 6.17 R: 6.14 RT: 4.62 ( 37Kops/s)
Optimized:
lowlevel-blt-bench:
over_n_8_8888 = L1: 27.25 L2: 26.24 M: 18.15 ( 72.12%) HT: 14.52 VT: 14.31 R: 13.83 RT: 7.57 ( 48Kops/s)
over_n_8_0565 = L1: 18.91 L2: 17.59 M: 15.06 ( 39.90%) HT: 12.18 VT: 11.98 R: 11.83 RT: 6.80 ( 46Kops/s)