Add parallelization of TensorScanOp for types without packet ops.

Clean up the code a bit and do a few micro-optimizations to improve performance for small tensors.

Benchmark numbers for Tensor<uint32_t>:

name                                                       old time/op             new time/op             delta
BM_cumSumRowReduction_1T/8   [using 1 threads]             76.5ns ± 0%             61.3ns ± 4%    -19.80%          (p=0.008 n=5+5)
BM_cumSumRowReduction_1T/64  [using 1 threads]             2.47µs ± 1%             2.40µs ± 1%     -2.77%          (p=0.008 n=5+5)
BM_cumSumRowReduction_1T/256 [using 1 threads]             39.8µs ± 0%             39.6µs ± 0%     -0.60%          (p=0.008 n=5+5)
BM_cumSumRowReduction_1T/4k  [using 1 threads]             13.9ms ± 0%             13.4ms ± 1%     -4.19%          (p=0.008 n=5+5)
BM_cumSumRowReduction_2T/8   [using 2 threads]             76.8ns ± 0%             59.1ns ± 0%    -23.09%          (p=0.016 n=5+4)
BM_cumSumRowReduction_2T/64  [using 2 threads]             2.47µs ± 1%             2.41µs ± 1%     -2.53%          (p=0.008 n=5+5)
BM_cumSumRowReduction_2T/256 [using 2 threads]             39.8µs ± 0%             34.7µs ± 6%    -12.74%          (p=0.008 n=5+5)
BM_cumSumRowReduction_2T/4k  [using 2 threads]             13.8ms ± 1%              7.2ms ± 6%    -47.74%          (p=0.008 n=5+5)
BM_cumSumRowReduction_8T/8   [using 8 threads]             76.4ns ± 0%             61.8ns ± 3%    -19.02%          (p=0.008 n=5+5)
BM_cumSumRowReduction_8T/64  [using 8 threads]             2.47µs ± 1%             2.40µs ± 1%     -2.84%          (p=0.008 n=5+5)
BM_cumSumRowReduction_8T/256 [using 8 threads]             39.8µs ± 0%             28.3µs ±11%    -28.75%          (p=0.008 n=5+5)
BM_cumSumRowReduction_8T/4k  [using 8 threads]             13.8ms ± 0%              2.7ms ± 5%    -80.39%          (p=0.008 n=5+5)
BM_cumSumColReduction_1T/8   [using 1 threads]             59.1ns ± 0%             80.3ns ± 0%    +35.94%          (p=0.029 n=4+4)
BM_cumSumColReduction_1T/64  [using 1 threads]             3.06µs ± 0%             3.08µs ± 1%       ~             (p=0.114 n=4+4)
BM_cumSumColReduction_1T/256 [using 1 threads]              175µs ± 0%              176µs ± 0%       ~             (p=0.190 n=4+5)
BM_cumSumColReduction_1T/4k  [using 1 threads]              824ms ± 1%              844ms ± 1%     +2.37%          (p=0.008 n=5+5)
BM_cumSumColReduction_2T/8   [using 2 threads]             59.0ns ± 0%             90.7ns ± 0%    +53.74%          (p=0.029 n=4+4)
BM_cumSumColReduction_2T/64  [using 2 threads]             3.06µs ± 0%             3.10µs ± 0%     +1.08%          (p=0.016 n=4+5)
BM_cumSumColReduction_2T/256 [using 2 threads]              176µs ± 0%              189µs ±18%       ~             (p=0.151 n=5+5)
BM_cumSumColReduction_2T/4k  [using 2 threads]              836ms ± 2%              611ms ±14%    -26.92%          (p=0.008 n=5+5)
BM_cumSumColReduction_8T/8   [using 8 threads]             59.3ns ± 2%             90.6ns ± 0%    +52.79%          (p=0.008 n=5+5)
BM_cumSumColReduction_8T/64  [using 8 threads]             3.07µs ± 0%             3.10µs ± 0%     +0.99%          (p=0.016 n=5+4)
BM_cumSumColReduction_8T/256 [using 8 threads]              176µs ± 0%               80µs ±19%    -54.51%          (p=0.008 n=5+5)
BM_cumSumColReduction_8T/4k  [using 8 threads]              827ms ± 2%              180ms ±14%    -78.24%          (p=0.008 n=5+5)

0 files changed, 0 insertions, 0 deletions