changed is_partitioned impl to make it similar to pstl's is_partitioned

[dhruvilmehta]

Description

Changed the implementation of thrust::is_partitioned to make it similar to libcudacxx::is_partitioned(#8084 ).

closes #8085

Made the implementation similar to pstl's implementation

Checklist

• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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[bernhardmgruber]

Thx for the PR! We need a benchmark that shows the benefits of the new approach. Can you please add the benchmark from #8084 to Thrust and measure the performance before and after your changes, and report the nvbench diff? Instructions for benchmarking are in our documentation: https://nvidia.github.io/cccl/unstable/cub/benchmarking.html

[miscco]

I believe this is not the right approach here.

The reason being that transform_reduce does not short-circuit on a negative match, so especially for larger arrays you are spending a considerable time searching for a result you already know.

in #8084 I used our DeviceFind::If machinery, because that stops searching after the first hit

[dhruvilmehta]

I made the implementation similar to pstl's implementation. There'e no major difference in the benchmark results which I got.

['../oldimpl.json', '../new7impl.json']
# base

## [0] Tesla T4

|  T   |  Elements  |  MismatchAt  |   Ref Time |   Ref Noise |   Cmp Time |   Cmp Noise |        Diff |   %Diff |  Status  |
|------|------------|--------------|------------|-------------|------------|-------------|-------------|---------|----------|
|  I8  |    2^16    |      1       |  45.334 us |      18.33% |  45.856 us |      71.58% |    0.522 us |   1.15% |   SAME   |
|  I8  |    2^20    |      1       |  51.538 us |      49.43% |  50.800 us |      55.33% |   -0.738 us |  -1.43% |   SAME   |
|  I8  |    2^24    |      1       |  52.547 us |      22.93% |  52.088 us |      67.03% |   -0.460 us |  -0.87% |   SAME   |
|  I8  |    2^28    |      1       |  52.800 us |      75.12% |  51.713 us |      37.90% |   -1.087 us |  -2.06% |   SAME   |
|  I8  |    2^16    |     0.5      |  40.156 us |      70.62% |  37.834 us |      27.81% |   -2.322 us |  -5.78% |   SAME   |
|  I8  |    2^20    |     0.5      |  51.094 us |      16.84% |  49.730 us |      26.71% |   -1.364 us |  -2.67% |   SAME   |
|  I8  |    2^24    |     0.5      |  53.648 us |      93.98% |  51.422 us |      22.64% |   -2.227 us |  -4.15% |   SAME   |
|  I8  |    2^28    |     0.5      |  52.578 us |      37.88% |  51.725 us |      19.76% |   -0.853 us |  -1.62% |   SAME   |
|  I8  |    2^16    |     0.01     |  39.959 us |      38.91% |  38.194 us |      81.40% |   -1.766 us |  -4.42% |   SAME   |
|  I8  |    2^20    |     0.01     |  52.631 us |      86.96% |  50.805 us |      43.13% |   -1.826 us |  -3.47% |   SAME   |
|  I8  |    2^24    |     0.01     |  52.499 us |      10.31% |  52.492 us |      86.75% |   -0.008 us |  -0.01% |   SAME   |
|  I8  |    2^28    |     0.01     |  53.753 us |     111.54% |  52.706 us |      75.45% |   -1.047 us |  -1.95% |   SAME   |
| I16  |    2^16    |      1       |  41.483 us |      83.14% |  37.766 us |      23.98% |   -3.717 us |  -8.96% |   SAME   |
| I16  |    2^20    |      1       |  56.753 us |      77.24% |  56.059 us |      68.79% |   -0.694 us |  -1.22% |   SAME   |
| I16  |    2^24    |      1       |  66.726 us |      84.07% |  59.674 us |      32.90% |   -7.052 us | -10.57% |   SAME   |
| I16  |    2^28    |      1       |  65.277 us |     221.17% |  62.395 us |     103.03% |   -2.882 us |  -4.41% |   SAME   |
| I16  |    2^16    |     0.5      |  41.761 us |     112.52% |  37.572 us |      79.34% |   -4.188 us | -10.03% |   SAME   |
| I16  |    2^20    |     0.5      |  56.374 us |      24.10% |  55.865 us |      64.63% |   -0.509 us |  -0.90% |   SAME   |
| I16  |    2^24    |     0.5      |  60.688 us |      52.68% |  60.477 us |      87.88% |   -0.210 us |  -0.35% |   SAME   |
| I16  |    2^28    |     0.5      |  62.222 us |      69.35% |  59.797 us |      25.45% |   -2.426 us |  -3.90% |   SAME   |
| I16  |    2^16    |     0.01     |  47.228 us |      76.56% |  43.949 us |      65.08% |   -3.279 us |  -6.94% |   SAME   |
| I16  |    2^20    |     0.01     |  56.698 us |      72.63% |  56.757 us |      72.10% |    0.059 us |   0.10% |   SAME   |
| I16  |    2^24    |     0.01     |  61.906 us |      76.56% |  60.659 us |      64.02% |   -1.246 us |  -2.01% |   SAME   |
| I16  |    2^28    |     0.01     |  61.559 us |      99.16% |  60.249 us |      25.47% |   -1.310 us |  -2.13% |   SAME   |
| I32  |    2^16    |      1       |  42.349 us |      32.27% |  40.112 us |      55.90% |   -2.237 us |  -5.28% |   SAME   |
| I32  |    2^20    |      1       |  64.538 us |      68.48% |  62.926 us |      21.84% |   -1.611 us |  -2.50% |   SAME   |
| I32  |    2^24    |      1       | 298.761 us |       1.68% | 298.374 us |       2.57% |   -0.388 us |  -0.13% |   SAME   |
| I32  |    2^28    |      1       |   3.948 ms |       4.30% |   3.944 ms |       2.66% |   -4.081 us |  -0.10% |   SAME   |
| I32  |    2^16    |     0.5      |  42.137 us |      24.59% |  39.374 us |      80.15% |   -2.763 us |  -6.56% |   SAME   |
| I32  |    2^20    |     0.5      |  69.540 us |      15.57% |  69.100 us |      63.16% |   -0.440 us |  -0.63% |   SAME   |
| I32  |    2^24    |     0.5      | 301.848 us |       2.19% | 300.784 us |       1.28% |   -1.065 us |  -0.35% |   SAME   |
| I32  |    2^28    |     0.5      |   3.962 ms |       5.42% |   3.961 ms |       4.93% |   -1.704 us |  -0.04% |   SAME   |
| I32  |    2^16    |     0.01     |  49.163 us |      89.30% |  45.400 us |      16.42% |   -3.764 us |  -7.66% |   SAME   |
| I32  |    2^20    |     0.01     |  71.883 us |      63.06% |  70.766 us |       4.59% |   -1.117 us |  -1.55% |   SAME   |
| I32  |    2^24    |     0.01     | 305.453 us |      25.33% | 304.298 us |      16.40% |   -1.154 us |  -0.38% |   SAME   |
| I32  |    2^28    |     0.01     |   4.785 ms |       0.50% |   4.819 ms |       0.50% |   33.909 us |   0.71% |   SLOW   |
| I64  |    2^16    |      1       |  43.228 us |      17.70% |  42.177 us |      71.66% |   -1.051 us |  -2.43% |   SAME   |
| I64  |    2^20    |      1       |  84.847 us |      14.31% |  94.500 us |     177.12% |    9.653 us |  11.38% |   SAME   |
| I64  |    2^24    |      1       | 541.479 us |       0.88% | 547.327 us |      20.87% |    5.848 us |   1.08% |   SLOW   |
| I64  |    2^28    |      1       |   7.810 ms |       1.16% |   7.811 ms |       2.04% |    0.767 us |   0.01% |   SAME   |
| I64  |    2^16    |     0.5      |  43.242 us |      14.36% |  39.416 us |      26.06% |   -3.826 us |  -8.85% |   SAME   |
| I64  |    2^20    |     0.5      |  86.760 us |      70.38% |  84.565 us |       4.86% |   -2.195 us |  -2.53% |   SAME   |
| I64  |    2^24    |     0.5      | 550.581 us |      16.48% | 548.877 us |      17.38% |   -1.704 us |  -0.31% |   SAME   |
| I64  |    2^28    |     0.5      |   7.829 ms |       1.91% |   7.816 ms |       0.11% |  -12.872 us |  -0.16% |   FAST   |
| I64  |    2^16    |     0.01     |  50.755 us |     157.63% |  43.512 us |      67.15% |   -7.243 us | -14.27% |   SAME   |
| I64  |    2^20    |     0.01     |  94.091 us |      85.55% |  90.271 us |      29.35% |   -3.820 us |  -4.06% |   SAME   |
| I64  |    2^24    |     0.01     | 548.130 us |       0.85% | 544.964 us |       0.68% |   -3.166 us |  -0.58% |   SAME   |
| I64  |    2^28    |     0.01     |   8.296 ms |       1.99% |   8.274 ms |       0.50% |  -21.517 us |  -0.26% |   SAME   |
| I128 |    2^16    |      1       |  46.213 us |      35.17% |  45.490 us |      75.35% |   -0.722 us |  -1.56% |   SAME   |
| I128 |    2^20    |      1       | 113.639 us |       4.16% | 113.891 us |      49.22% |    0.252 us |   0.22% |   SAME   |
| I128 |    2^24    |      1       |   1.040 ms |      14.70% |   1.034 ms |      12.78% |   -6.069 us |  -0.58% |   SAME   |
| I128 |    2^28    |      1       |  15.581 ms |       0.15% |  15.593 ms |       0.20% |   11.849 us |   0.08% |   SAME   |
| I128 |    2^16    |     0.5      |  47.244 us |      34.59% |  48.081 us |     148.75% |    0.837 us |   1.77% |   SAME   |
| I128 |    2^20    |     0.5      | 120.271 us |      67.71% | 118.311 us |      33.21% |   -1.960 us |  -1.63% |   SAME   |
| I128 |    2^24    |     0.5      |   1.032 ms |       0.44% |   1.032 ms |       0.49% |   -0.506 us |  -0.05% |   SAME   |
| I128 |    2^28    |     0.5      |  15.618 ms |       1.38% |  15.604 ms |       0.78% |  -13.271 us |  -0.08% |   SAME   |
| I128 |    2^16    |     0.01     |  50.795 us |      92.86% |  49.921 us |      73.83% |   -0.874 us |  -1.72% |   SAME   |
| I128 |    2^20    |     0.01     | 118.445 us |      12.91% | 117.693 us |      28.31% |   -0.752 us |  -0.64% |   SAME   |
| I128 |    2^24    |     0.01     |   1.050 ms |      10.23% |   1.045 ms |       7.30% |   -5.625 us |  -0.54% |   SAME   |
| I128 |    2^28    |     0.01     |  16.042 ms |       0.08% |  16.028 ms |       0.06% |  -14.009 us |  -0.09% |   FAST   |
| F32  |    2^16    |      1       |  43.349 us |      50.85% |  38.624 us |      29.72% |   -4.725 us | -10.90% |   SAME   |
| F32  |    2^20    |      1       |  63.879 us |      16.81% |  62.904 us |      29.56% |   -0.975 us |  -1.53% |   SAME   |
| F32  |    2^24    |      1       | 302.790 us |      23.29% | 298.561 us |      13.27% |   -4.229 us |  -1.40% |   SAME   |
| F32  |    2^28    |      1       |   3.950 ms |       2.89% |   3.965 ms |       6.60% |   15.831 us |   0.40% |   SAME   |
| F32  |    2^16    |     0.5      |  42.210 us |      53.55% |  38.462 us |      26.29% |   -3.748 us |  -8.88% |   SAME   |
| F32  |    2^20    |     0.5      |  68.671 us |       4.19% |  68.953 us |      59.08% |    0.282 us |   0.41% |   SAME   |
| F32  |    2^24    |     0.5      | 307.301 us |      31.60% | 300.741 us |       1.16% |   -6.560 us |  -2.13% |   FAST   |
| F32  |    2^28    |     0.5      |   3.981 ms |       0.16% |   3.985 ms |       3.57% |    4.630 us |   0.12% |   SAME   |
| F32  |    2^16    |     0.01     |  49.036 us |      43.25% |  44.988 us |      72.12% |   -4.049 us |  -8.26% |   SAME   |
| F32  |    2^20    |     0.01     |  72.343 us |      60.99% |  72.100 us |      55.31% |   -0.243 us |  -0.34% |   SAME   |
| F32  |    2^24    |     0.01     | 305.944 us |      19.45% | 303.353 us |      19.43% |   -2.591 us |  -0.85% |   SAME   |
| F32  |    2^28    |     0.01     |   4.944 ms |       3.84% |   4.817 ms |       2.14% | -126.893 us |  -2.57% |   FAST   |
| F64  |    2^16    |      1       |  44.029 us |      94.79% |  42.527 us |      26.53% |   -1.502 us |  -3.41% |   SAME   |
| F64  |    2^20    |      1       |  87.612 us |      83.17% |  84.878 us |      84.00% |   -2.734 us |  -3.12% |   SAME   |
| F64  |    2^24    |      1       | 539.380 us |       0.87% | 536.610 us |       0.92% |   -2.770 us |  -0.51% |   SAME   |
| F64  |    2^28    |      1       |   7.781 ms |       0.50% |   7.777 ms |       0.16% |   -4.394 us |  -0.06% |   SAME   |
| F64  |    2^16    |     0.5      |  43.664 us |      30.53% |  41.996 us |      15.39% |   -1.668 us |  -3.82% |   SAME   |
| F64  |    2^20    |     0.5      |  85.005 us |       4.18% |  85.806 us |      55.31% |    0.800 us |   0.94% |   SAME   |
| F64  |    2^24    |     0.5      | 547.693 us |      14.47% | 539.460 us |       0.73% |   -8.233 us |  -1.50% |   FAST   |
| F64  |    2^28    |     0.5      |   7.804 ms |       2.28% |   7.796 ms |       2.04% |   -7.296 us |  -0.09% |   SAME   |
| F64  |    2^16    |     0.01     |  47.953 us |      40.22% |  46.605 us |      69.76% |   -1.348 us |  -2.81% |   SAME   |
| F64  |    2^20    |     0.01     |  89.236 us |       4.18% |  86.693 us |       3.80% |   -2.543 us |  -2.85% |   SAME   |
| F64  |    2^24    |     0.01     | 557.966 us |      31.47% | 547.790 us |      12.80% |  -10.177 us |  -1.82% |   SAME   |
| F64  |    2^28    |     0.01     |   8.363 ms |       0.18% |   8.325 ms |       0.11% |  -38.158 us |  -0.46% |   FAST   |

# Summary

- Total Matches: 84
  - Pass    (diff <= min_noise): 76
  - Unknown (infinite noise):    0
  - Failure (diff > min_noise):  8