pytorch

ed57425b - improve performance of unique with inverse indices (#16145)

improve performance of unique with inverse indices (#16145) Summary: Partial fix for #15804, only w/o dim. For jcjohnson benchmarking script I'm getting the following results on V100: Before: ``` unning with N = 10000, M = 10000 cuda (no inverse): 0.98 ms cpu (no inverse): 0.96 ms cuda (with inverse): 1.07 ms cpu (with inverse): 1.76 ms Running with N = 10000, M = 100000 cuda (no inverse): 0.76 ms cpu (no inverse): 1.53 ms cuda (with inverse): 1.23 ms cpu (with inverse): 3.02 ms Running with N = 100000, M = 100000 cuda (no inverse): 1.28 ms cpu (no inverse): 11.22 ms cuda (with inverse): 69.76 ms cpu (with inverse): 20.28 ms Running with N = 100000, M = 1000000 cuda (no inverse): 0.78 ms cpu (no inverse): 18.78 ms cuda (with inverse): 133.45 ms cpu (with inverse): 34.09 ms Running with N = 500000, M = 500000 cuda (no inverse): 1.43 ms cpu (no inverse): 61.13 ms cuda (with inverse): 3315.18 ms cpu (with inverse): 104.57 ms Running with N = 500000, M = 5000000 cuda (no inverse): 0.86 ms cpu (no inverse): 96.44 ms cuda (with inverse): 5209.93 ms cpu (with inverse): 176.10 ms ``` After ``` Running with N = 10000, M = 10000 cuda (no inverse): 1.04 ms cpu (no inverse): 0.94 ms cuda (with inverse): 0.64 ms cpu (with inverse): 1.76 ms Running with N = 10000, M = 100000 cuda (no inverse): 0.77 ms cpu (no inverse): 1.55 ms cuda (with inverse): 0.58 ms cpu (with inverse): 2.79 ms Running with N = 100000, M = 100000 cuda (no inverse): 1.30 ms cpu (no inverse): 14.15 ms cuda (with inverse): 1.63 ms cpu (with inverse): 20.90 ms Running with N = 100000, M = 1000000 cuda (no inverse): 0.82 ms cpu (no inverse): 18.63 ms cuda (with inverse): 0.61 ms cpu (with inverse): 33.52 ms Running with N = 500000, M = 500000 cuda (no inverse): 1.51 ms cpu (no inverse): 59.81 ms cuda (with inverse): 1.23 ms cpu (with inverse): 110.69 ms Running with N = 500000, M = 5000000 cuda (no inverse): 0.92 ms cpu (no inverse): 104.26 ms cuda (with inverse): 0.84 ms cpu (with inverse): 187.12 ms ``` Pull Request resolved: https://github.com/pytorch/pytorch/pull/16145 Differential Revision: D13738821 Pulled By: soumith fbshipit-source-id: 0811fb4ade47e3b466cebbc124e3f3333a986749