[libcxx-commits] [libcxx] [libcxx][algorithm] Optimize std::stable_sort via radix sort algorithm (PR #104683)

Дмитрий Изволов via libcxx-commits libcxx-commits at lists.llvm.org
Sat Aug 17 12:25:31 PDT 2024


https://github.com/izvolov created https://github.com/llvm/llvm-project/pull/104683

The radix sort (MSD) algorithm allows to speed up std::stable_sort dramatically in case we sort integers.
The speed up varies from a relatively small to x10 times, depending on type of sorted elements and the initial state of the sorted array.

```
Running ./libcxx/test/benchmarks/stable_sort.bench.out
Run on (12 X 2600 MHz CPU s)
CPU Caches:
  L1 Data 32 KiB
  L1 Instruction 32 KiB
  L2 Unified 256 KiB (x6)
  L3 Unified 12288 KiB
Load Average: 3.48, 3.38, 3.08
---------------------------------------------------------------------------
Benchmark                                               After        Before 
---------------------------------------------------------------------------
BM_StableSort_int8_Random_1                           3.39 ns       3.58 ns 
BM_StableSort_int8_Random_4                           21.1 ns       21.9 ns 
BM_StableSort_int8_Random_16                           142 ns        147 ns 
BM_StableSort_int8_Random_64                           893 ns        903 ns 
BM_StableSort_int8_Random_256                          409 ns       5810 ns 
BM_StableSort_int8_Random_1024                        1235 ns      29973 ns 
BM_StableSort_int8_Random_4096                        4410 ns     141880 ns 
BM_StableSort_int8_Random_16384                      18044 ns     620540 ns 
BM_StableSort_int8_Random_65536                     144030 ns    2592013 ns 
BM_StableSort_int8_Random_262144                    858350 ns   10935814 ns 
BM_StableSort_int8_Random_524288                   2929988 ns   27060729 ns 
BM_StableSort_int8_Random_1048576                  6058292 ns   49622720 ns 
BM_StableSort_int8_Ascending_1                        3.42 ns       3.92 ns 
BM_StableSort_int8_Ascending_4                        5.86 ns       8.08 ns 
BM_StableSort_int8_Ascending_16                       10.6 ns       12.0 ns 
BM_StableSort_int8_Ascending_64                       28.9 ns       30.6 ns 
BM_StableSort_int8_Ascending_256                       415 ns        391 ns 
BM_StableSort_int8_Ascending_1024                     1666 ns       2309 ns 
BM_StableSort_int8_Ascending_4096                     7748 ns      12269 ns 
BM_StableSort_int8_Ascending_16384                   40588 ns      60181 ns 
BM_StableSort_int8_Ascending_65536                  178843 ns     298221 ns 
BM_StableSort_int8_Ascending_262144                 919959 ns    1402692 ns 
BM_StableSort_int8_Ascending_524288                2397397 ns    3036984 ns 
BM_StableSort_int8_Ascending_1048576               5080043 ns    7218581 ns 
BM_StableSort_int8_Descending_1                       3.44 ns       3.53 ns 
BM_StableSort_int8_Descending_4                       7.94 ns       8.29 ns 
BM_StableSort_int8_Descending_16                      59.6 ns       57.7 ns 
BM_StableSort_int8_Descending_64                      1051 ns       1027 ns 
BM_StableSort_int8_Descending_256                      422 ns       4718 ns 
BM_StableSort_int8_Descending_1024                    1676 ns      21044 ns 
BM_StableSort_int8_Descending_4096                    7766 ns      64827 ns 
BM_StableSort_int8_Descending_16384                  40230 ns      93981 ns 
BM_StableSort_int8_Descending_65536                 190978 ns     421151 ns 
BM_StableSort_int8_Descending_262144               1055141 ns    1918927 ns 
BM_StableSort_int8_Descending_524288               2875115 ns    3809153 ns 
BM_StableSort_int8_Descending_1048576              5854135 ns    8713690 ns 
BM_StableSort_int8_SingleElement_1                    3.52 ns       3.46 ns 
BM_StableSort_int8_SingleElement_4                    6.25 ns       5.79 ns 
BM_StableSort_int8_SingleElement_16                   10.7 ns       11.4 ns 
BM_StableSort_int8_SingleElement_64                   29.3 ns       30.3 ns 
BM_StableSort_int8_SingleElement_256                   858 ns        380 ns 
BM_StableSort_int8_SingleElement_1024                 3036 ns       2231 ns 
BM_StableSort_int8_SingleElement_4096                11580 ns      11866 ns 
BM_StableSort_int8_SingleElement_16384               44956 ns      59621 ns 
BM_StableSort_int8_SingleElement_65536              182006 ns     297853 ns 
BM_StableSort_int8_SingleElement_262144             962181 ns    1432857 ns 
BM_StableSort_int8_SingleElement_524288            2256687 ns    2975707 ns 
BM_StableSort_int8_SingleElement_1048576           4522556 ns    6949948 ns 
BM_StableSort_int8_PipeOrgan_1                        3.26 ns       3.64 ns 
BM_StableSort_int8_PipeOrgan_4                        6.21 ns       6.58 ns 
BM_StableSort_int8_PipeOrgan_16                       23.7 ns       25.4 ns 
BM_StableSort_int8_PipeOrgan_64                        250 ns        248 ns 
BM_StableSort_int8_PipeOrgan_256                       414 ns       2498 ns 
BM_StableSort_int8_PipeOrgan_1024                     1697 ns      10946 ns 
BM_StableSort_int8_PipeOrgan_4096                     7840 ns      37238 ns 
BM_StableSort_int8_PipeOrgan_16384                   41402 ns      74805 ns 
BM_StableSort_int8_PipeOrgan_65536                  180107 ns     357891 ns 
BM_StableSort_int8_PipeOrgan_262144                 988273 ns    1647296 ns 
BM_StableSort_int8_PipeOrgan_524288                2547374 ns    3245991 ns 
BM_StableSort_int8_PipeOrgan_1048576               5128783 ns    7342444 ns 
BM_StableSort_int8_QuickSortAdversary_1               3.14 ns       4.01 ns 
BM_StableSort_int8_QuickSortAdversary_4               6.05 ns       7.02 ns 
BM_StableSort_int8_QuickSortAdversary_16              10.5 ns       11.9 ns 
BM_StableSort_int8_QuickSortAdversary_64               520 ns        516 ns 
BM_StableSort_int8_QuickSortAdversary_256              920 ns        386 ns 
BM_StableSort_int8_QuickSortAdversary_1024            3083 ns       2299 ns 
BM_StableSort_int8_QuickSortAdversary_4096           11659 ns      12295 ns 
BM_StableSort_int8_QuickSortAdversary_16384          45721 ns      60931 ns 
BM_StableSort_int8_QuickSortAdversary_65536         186334 ns     295423 ns 
BM_StableSort_int8_QuickSortAdversary_262144        946262 ns    1399973 ns 
BM_StableSort_int8_QuickSortAdversary_524288       2282004 ns    2832266 ns 
BM_StableSort_int8_QuickSortAdversary_1048576      4691123 ns    6963253 ns 
BM_StableSort_uint8_Random_1                          3.11 ns       3.44 ns 
BM_StableSort_uint8_Random_4                          21.9 ns       23.1 ns 
BM_StableSort_uint8_Random_16                          154 ns        171 ns 
BM_StableSort_uint8_Random_64                         1000 ns       1051 ns 
BM_StableSort_uint8_Random_256                         402 ns       6498 ns 
BM_StableSort_uint8_Random_1024                       1176 ns      35310 ns 
BM_StableSort_uint8_Random_4096                       4415 ns     164087 ns 
BM_StableSort_uint8_Random_16384                     17849 ns     686769 ns 
BM_StableSort_uint8_Random_65536                    146109 ns    2932051 ns 
BM_StableSort_uint8_Random_262144                   876710 ns   12163988 ns 
BM_StableSort_uint8_Random_524288                  2858089 ns   26458830 ns 
BM_StableSort_uint8_Random_1048576                 5766942 ns   54836214 ns 
BM_StableSort_uint8_Ascending_1                       3.11 ns       3.43 ns 
BM_StableSort_uint8_Ascending_4                       6.18 ns       7.24 ns 
BM_StableSort_uint8_Ascending_16                      14.5 ns       17.0 ns 
BM_StableSort_uint8_Ascending_64                      50.7 ns       59.2 ns 
BM_StableSort_uint8_Ascending_256                      395 ns        536 ns 
BM_StableSort_uint8_Ascending_1024                    1752 ns       2956 ns 
BM_StableSort_uint8_Ascending_4096                    7785 ns      15146 ns 
BM_StableSort_uint8_Ascending_16384                  41442 ns      74136 ns 
BM_StableSort_uint8_Ascending_65536                 180879 ns     354261 ns 
BM_StableSort_uint8_Ascending_262144                945880 ns    1674256 ns 
BM_StableSort_uint8_Ascending_524288               2287832 ns    3138581 ns 
BM_StableSort_uint8_Ascending_1048576              4630290 ns    7296278 ns 
BM_StableSort_uint8_Descending_1                      3.19 ns       3.63 ns 
BM_StableSort_uint8_Descending_4                      9.60 ns       11.5 ns 
BM_StableSort_uint8_Descending_16                     78.3 ns       86.0 ns 
BM_StableSort_uint8_Descending_64                     1265 ns       1308 ns 
BM_StableSort_uint8_Descending_256                     395 ns       6556 ns 
BM_StableSort_uint8_Descending_1024                   1712 ns      24669 ns 
BM_StableSort_uint8_Descending_4096                   7748 ns      83407 ns 
BM_StableSort_uint8_Descending_16384                 40779 ns     104043 ns 
BM_StableSort_uint8_Descending_65536                181560 ns     467680 ns 
BM_StableSort_uint8_Descending_262144              1146627 ns    2102769 ns 
BM_StableSort_uint8_Descending_524288              2874096 ns    4572229 ns 
BM_StableSort_uint8_Descending_1048576             5873195 ns   10170663 ns 
BM_StableSort_uint8_SingleElement_1                   3.28 ns       3.58 ns 
BM_StableSort_uint8_SingleElement_4                   6.44 ns       7.40 ns 
BM_StableSort_uint8_SingleElement_16                  14.9 ns       16.4 ns 
BM_StableSort_uint8_SingleElement_64                  51.2 ns       52.9 ns 
BM_StableSort_uint8_SingleElement_256                  876 ns        490 ns 
BM_StableSort_uint8_SingleElement_1024                3041 ns       2750 ns 
BM_StableSort_uint8_SingleElement_4096               11947 ns      14326 ns 
BM_StableSort_uint8_SingleElement_16384              46669 ns      69984 ns 
BM_StableSort_uint8_SingleElement_65536             197903 ns     328961 ns 
BM_StableSort_uint8_SingleElement_262144           1031466 ns    1551436 ns 
BM_StableSort_uint8_SingleElement_524288           2447672 ns    3049553 ns 
BM_StableSort_uint8_SingleElement_1048576          4793087 ns    7615245 ns 
BM_StableSort_uint8_PipeOrgan_1                       3.38 ns       3.56 ns 
BM_StableSort_uint8_PipeOrgan_4                       7.16 ns       8.70 ns 
BM_StableSort_uint8_PipeOrgan_16                      31.7 ns       35.3 ns 
BM_StableSort_uint8_PipeOrgan_64                       326 ns        366 ns 
BM_StableSort_uint8_PipeOrgan_256                      409 ns       2942 ns 
BM_StableSort_uint8_PipeOrgan_1024                    1994 ns      12571 ns 
BM_StableSort_uint8_PipeOrgan_4096                    8086 ns      46278 ns 
BM_StableSort_uint8_PipeOrgan_16384                  41749 ns      79813 ns 
BM_StableSort_uint8_PipeOrgan_65536                 180697 ns     375120 ns 
BM_StableSort_uint8_PipeOrgan_262144               1004899 ns    1676143 ns 
BM_StableSort_uint8_PipeOrgan_524288               2456081 ns    3333949 ns 
BM_StableSort_uint8_PipeOrgan_1048576              5030857 ns    7591303 ns 
BM_StableSort_uint8_QuickSortAdversary_1              3.12 ns       3.46 ns 
BM_StableSort_uint8_QuickSortAdversary_4              7.25 ns       6.83 ns 
BM_StableSort_uint8_QuickSortAdversary_16             14.6 ns       16.2 ns 
BM_StableSort_uint8_QuickSortAdversary_64              650 ns        665 ns 
BM_StableSort_uint8_QuickSortAdversary_256             395 ns       2982 ns 
BM_StableSort_uint8_QuickSortAdversary_1024           3125 ns       2583 ns 
BM_StableSort_uint8_QuickSortAdversary_4096          11797 ns      13929 ns 
BM_StableSort_uint8_QuickSortAdversary_16384         45803 ns      66513 ns 
BM_StableSort_uint8_QuickSortAdversary_65536        190745 ns     313467 ns 
BM_StableSort_uint8_QuickSortAdversary_262144       974646 ns    1469014 ns 
BM_StableSort_uint8_QuickSortAdversary_524288      2317553 ns    3022065 ns 
BM_StableSort_uint8_QuickSortAdversary_1048576     4898703 ns    6854079 ns 
BM_StableSort_int16_Random_1                          3.94 ns       3.49 ns 
BM_StableSort_int16_Random_4                          20.8 ns       23.2 ns 
BM_StableSort_int16_Random_16                          133 ns        163 ns 
BM_StableSort_int16_Random_64                          903 ns        953 ns 
BM_StableSort_int16_Random_256                        5638 ns       6258 ns 
BM_StableSort_int16_Random_1024                       3056 ns      34587 ns 
BM_StableSort_int16_Random_4096                      10596 ns     168397 ns 
BM_StableSort_int16_Random_16384                     49908 ns     753031 ns 
BM_StableSort_int16_Random_65536                    444605 ns    3838368 ns 
BM_StableSort_int16_Random_262144                  2419345 ns   15657285 ns 
BM_StableSort_int16_Random_524288                  7984040 ns   32726933 ns 
BM_StableSort_int16_Random_1048576                16092424 ns   67999766 ns 
BM_StableSort_int16_Ascending_1                       3.40 ns       3.43 ns 
BM_StableSort_int16_Ascending_4                       5.45 ns       5.79 ns 
BM_StableSort_int16_Ascending_16                      12.0 ns       15.3 ns 
BM_StableSort_int16_Ascending_64                      39.6 ns       52.6 ns 
BM_StableSort_int16_Ascending_256                      470 ns        550 ns 
BM_StableSort_int16_Ascending_1024                    1686 ns       2707 ns 
BM_StableSort_int16_Ascending_4096                    5676 ns      14165 ns 
BM_StableSort_int16_Ascending_16384                  21413 ns      69483 ns 
BM_StableSort_int16_Ascending_65536                  88010 ns     334466 ns 
BM_StableSort_int16_Ascending_262144                567239 ns    1570620 ns 
BM_StableSort_int16_Ascending_524288               1553063 ns    3424666 ns 
BM_StableSort_int16_Ascending_1048576              3145577 ns    8499649 ns 
BM_StableSort_int16_Descending_1                      3.22 ns       3.54 ns 
BM_StableSort_int16_Descending_4                      6.85 ns       10.2 ns 
BM_StableSort_int16_Descending_16                     62.7 ns       62.2 ns 
BM_StableSort_int16_Descending_64                     1138 ns       1036 ns 
BM_StableSort_int16_Descending_256                    5541 ns       4696 ns 
BM_StableSort_int16_Descending_1024                   3046 ns      19577 ns 
BM_StableSort_int16_Descending_4096                  10962 ns      79149 ns 
BM_StableSort_int16_Descending_16384                 58182 ns     327709 ns 
BM_StableSort_int16_Descending_65536                447025 ns    1424896 ns 
BM_StableSort_int16_Descending_262144              1104973 ns    5921903 ns 
BM_StableSort_int16_Descending_524288              2547840 ns   17956789 ns 
BM_StableSort_int16_Descending_1048576             5093555 ns   17044318 ns 
BM_StableSort_int16_SingleElement_1                   3.56 ns       3.96 ns 
BM_StableSort_int16_SingleElement_4                   5.75 ns       6.72 ns 
BM_StableSort_int16_SingleElement_16                  12.4 ns       16.1 ns 
BM_StableSort_int16_SingleElement_64                  36.9 ns       54.4 ns 
BM_StableSort_int16_SingleElement_256                  473 ns        557 ns 
BM_StableSort_int16_SingleElement_1024                1828 ns       2826 ns 
BM_StableSort_int16_SingleElement_4096                6239 ns      14252 ns 
BM_StableSort_int16_SingleElement_16384              23695 ns      70369 ns 
BM_StableSort_int16_SingleElement_65536              93281 ns     361641 ns 
BM_StableSort_int16_SingleElement_262144            599078 ns    1640216 ns 
BM_StableSort_int16_SingleElement_524288           1659678 ns    3343087 ns 
BM_StableSort_int16_SingleElement_1048576          3184033 ns    7770271 ns 
BM_StableSort_int16_PipeOrgan_1                       3.75 ns       3.76 ns 
BM_StableSort_int16_PipeOrgan_4                       5.94 ns       7.74 ns 
BM_StableSort_int16_PipeOrgan_16                      26.7 ns       25.9 ns 
BM_StableSort_int16_PipeOrgan_64                       300 ns        263 ns 
BM_StableSort_int16_PipeOrgan_256                     2769 ns       2760 ns 
BM_StableSort_int16_PipeOrgan_1024                    2996 ns      10544 ns 
BM_StableSort_int16_PipeOrgan_4096                   11641 ns      44750 ns 
BM_StableSort_int16_PipeOrgan_16384                  57224 ns     200464 ns 
BM_StableSort_int16_PipeOrgan_65536                 416873 ns     887631 ns 
BM_StableSort_int16_PipeOrgan_262144                843264 ns    3588669 ns 
BM_StableSort_int16_PipeOrgan_524288               2027741 ns   11056924 ns 
BM_StableSort_int16_PipeOrgan_1048576              4223773 ns   13261276 ns 
BM_StableSort_int16_QuickSortAdversary_1              3.83 ns       3.68 ns 
BM_StableSort_int16_QuickSortAdversary_4              5.55 ns       6.93 ns 
BM_StableSort_int16_QuickSortAdversary_16             12.3 ns       15.2 ns 
BM_StableSort_int16_QuickSortAdversary_64              646 ns        632 ns 
BM_StableSort_int16_QuickSortAdversary_256            2751 ns       2542 ns 
BM_StableSort_int16_QuickSortAdversary_1024           3028 ns      16901 ns 
BM_StableSort_int16_QuickSortAdversary_4096          10862 ns      80222 ns 
BM_StableSort_int16_QuickSortAdversary_16384         57753 ns     317281 ns 
BM_StableSort_int16_QuickSortAdversary_65536         94064 ns     328502 ns 
BM_StableSort_int16_QuickSortAdversary_262144       557796 ns    1613208 ns 
BM_StableSort_int16_QuickSortAdversary_524288      1518451 ns    3479740 ns 
BM_StableSort_int16_QuickSortAdversary_1048576     3165129 ns    7655880 ns 
BM_StableSort_uint16_Random_1                         3.26 ns       3.44 ns 
BM_StableSort_uint16_Random_4                         21.1 ns       22.2 ns 
BM_StableSort_uint16_Random_16                         157 ns        156 ns 
BM_StableSort_uint16_Random_64                         955 ns        947 ns 
BM_StableSort_uint16_Random_256                       5886 ns       6097 ns 
BM_StableSort_uint16_Random_1024                      2787 ns      30776 ns 
BM_StableSort_uint16_Random_4096                      9973 ns     155652 ns 
BM_StableSort_uint16_Random_16384                    48628 ns     741072 ns 
BM_StableSort_uint16_Random_65536                   439609 ns    3478966 ns 
BM_StableSort_uint16_Random_262144                 2336983 ns   15197642 ns 
BM_StableSort_uint16_Random_524288                 7888701 ns   34234254 ns 
BM_StableSort_uint16_Random_1048576               14865180 ns   68516386 ns 
BM_StableSort_uint16_Ascending_1                      3.33 ns       4.00 ns 
BM_StableSort_uint16_Ascending_4                      5.79 ns       6.64 ns 
BM_StableSort_uint16_Ascending_16                     14.9 ns       15.5 ns 
BM_StableSort_uint16_Ascending_64                     50.2 ns       52.5 ns 
BM_StableSort_uint16_Ascending_256                     538 ns        546 ns 
BM_StableSort_uint16_Ascending_1024                   1645 ns       2652 ns 
BM_StableSort_uint16_Ascending_4096                   5559 ns      14517 ns 
BM_StableSort_uint16_Ascending_16384                 22803 ns      70275 ns 
BM_StableSort_uint16_Ascending_65536                 83109 ns     333446 ns 
BM_StableSort_uint16_Ascending_262144               562667 ns    1568670 ns 
BM_StableSort_uint16_Ascending_524288              1564646 ns    3059839 ns 
BM_StableSort_uint16_Ascending_1048576             3178826 ns    7048327 ns 
BM_StableSort_uint16_Descending_1                     3.34 ns       3.93 ns 
BM_StableSort_uint16_Descending_4                     8.75 ns       9.73 ns 
BM_StableSort_uint16_Descending_16                    55.9 ns       55.5 ns 
BM_StableSort_uint16_Descending_64                    1021 ns       1035 ns 
BM_StableSort_uint16_Descending_256                   4752 ns       4931 ns 
BM_StableSort_uint16_Descending_1024                  2982 ns      19727 ns 
BM_StableSort_uint16_Descending_4096                 10432 ns      83165 ns 
BM_StableSort_uint16_Descending_16384                56593 ns     326131 ns 
BM_StableSort_uint16_Descending_65536               439134 ns    1371346 ns 
BM_StableSort_uint16_Descending_262144             1220925 ns    5735665 ns 
BM_StableSort_uint16_Descending_524288             2767234 ns   16758330 ns 
BM_StableSort_uint16_Descending_1048576            5673769 ns   17541715 ns 
BM_StableSort_uint16_SingleElement_1                  3.53 ns       3.73 ns 
BM_StableSort_uint16_SingleElement_4                  6.27 ns       5.81 ns 
BM_StableSort_uint16_SingleElement_16                 14.8 ns       15.1 ns 
BM_StableSort_uint16_SingleElement_64                 51.5 ns       50.9 ns 
BM_StableSort_uint16_SingleElement_256                 536 ns        540 ns 
BM_StableSort_uint16_SingleElement_1024               1669 ns       2690 ns 
BM_StableSort_uint16_SingleElement_4096               5840 ns      14230 ns 
BM_StableSort_uint16_SingleElement_16384             22468 ns      68524 ns 
BM_StableSort_uint16_SingleElement_65536             89845 ns     332187 ns 
BM_StableSort_uint16_SingleElement_262144           590736 ns    1550868 ns 
BM_StableSort_uint16_SingleElement_524288          1573677 ns    3095703 ns 
BM_StableSort_uint16_SingleElement_1048576         3183421 ns    8251180 ns 
BM_StableSort_uint16_PipeOrgan_1                      3.70 ns       3.64 ns 
BM_StableSort_uint16_PipeOrgan_4                      7.01 ns       6.81 ns 
BM_StableSort_uint16_PipeOrgan_16                     25.7 ns       26.4 ns 
BM_StableSort_uint16_PipeOrgan_64                      283 ns        277 ns 
BM_StableSort_uint16_PipeOrgan_256                    2562 ns       2852 ns 
BM_StableSort_uint16_PipeOrgan_1024                   2863 ns      10892 ns 
BM_StableSort_uint16_PipeOrgan_4096                  10585 ns      45668 ns 
BM_StableSort_uint16_PipeOrgan_16384                 59151 ns     194358 ns 
BM_StableSort_uint16_PipeOrgan_65536                508579 ns     854692 ns 
BM_StableSort_uint16_PipeOrgan_262144               901294 ns    3606346 ns 
BM_StableSort_uint16_PipeOrgan_524288              2192498 ns   10449279 ns 
BM_StableSort_uint16_PipeOrgan_1048576             4204368 ns   11956606 ns 
BM_StableSort_uint16_QuickSortAdversary_1             3.20 ns       3.63 ns 
BM_StableSort_uint16_QuickSortAdversary_4             5.30 ns       6.38 ns 
BM_StableSort_uint16_QuickSortAdversary_16            14.5 ns       15.3 ns 
BM_StableSort_uint16_QuickSortAdversary_64             575 ns        611 ns 
BM_StableSort_uint16_QuickSortAdversary_256           2423 ns       2577 ns 
BM_StableSort_uint16_QuickSortAdversary_1024          2794 ns      16854 ns 
BM_StableSort_uint16_QuickSortAdversary_4096         10511 ns      75952 ns 
BM_StableSort_uint16_QuickSortAdversary_16384        56214 ns     333824 ns 
BM_StableSort_uint16_QuickSortAdversary_65536       422512 ns    1354867 ns 
BM_StableSort_uint16_QuickSortAdversary_262144      583301 ns    1564443 ns 
BM_StableSort_uint16_QuickSortAdversary_524288     1584319 ns    3265575 ns 
BM_StableSort_uint16_QuickSortAdversary_1048576    3197732 ns    7945245 ns 
BM_StableSort_int32_Random_1                          3.81 ns       3.70 ns 
BM_StableSort_int32_Random_4                          20.8 ns       23.4 ns 
BM_StableSort_int32_Random_16                          134 ns        161 ns 
BM_StableSort_int32_Random_64                          895 ns        984 ns 
BM_StableSort_int32_Random_256                        5640 ns       5897 ns 
BM_StableSort_int32_Random_1024                       6994 ns      32118 ns 
BM_StableSort_int32_Random_4096                      27367 ns     168960 ns 
BM_StableSort_int32_Random_16384                    183261 ns     843240 ns 
BM_StableSort_int32_Random_65536                    950914 ns    3953588 ns 
BM_StableSort_int32_Random_262144                  3673311 ns   16790171 ns 
BM_StableSort_int32_Random_524288                 11515700 ns   36023098 ns 
BM_StableSort_int32_Random_1048576                24492515 ns   78116028 ns 
BM_StableSort_int32_Ascending_1                       3.31 ns       4.48 ns 
BM_StableSort_int32_Ascending_4                       5.96 ns       6.99 ns 
BM_StableSort_int32_Ascending_16                      13.0 ns       16.0 ns 
BM_StableSort_int32_Ascending_64                      36.7 ns       53.0 ns 
BM_StableSort_int32_Ascending_256                      391 ns        471 ns 
BM_StableSort_int32_Ascending_1024                    2705 ns       2682 ns 
BM_StableSort_int32_Ascending_4096                    8773 ns      14231 ns 
BM_StableSort_int32_Ascending_16384                  34709 ns      70625 ns 
BM_StableSort_int32_Ascending_65536                 142907 ns     344482 ns 
BM_StableSort_int32_Ascending_262144                745483 ns    1591418 ns 
BM_StableSort_int32_Ascending_524288               1873701 ns    3190305 ns 
BM_StableSort_int32_Ascending_1048576              3851590 ns    7570095 ns 
BM_StableSort_int32_Descending_1                      3.22 ns       4.23 ns 
BM_StableSort_int32_Descending_4                      7.58 ns       11.2 ns 
BM_StableSort_int32_Descending_16                     63.9 ns       58.6 ns 
BM_StableSort_int32_Descending_64                     1133 ns       1017 ns 
BM_StableSort_int32_Descending_256                    4850 ns       4464 ns 
BM_StableSort_int32_Descending_1024                   7023 ns      18954 ns 
BM_StableSort_int32_Descending_4096                  28550 ns      75163 ns 
BM_StableSort_int32_Descending_16384                200880 ns     341104 ns 
BM_StableSort_int32_Descending_65536               1095910 ns    1398021 ns 
BM_StableSort_int32_Descending_262144              3818864 ns    5695486 ns 
BM_StableSort_int32_Descending_524288              5606779 ns   17593982 ns 
BM_StableSort_int32_Descending_1048576            16416366 ns   26649503 ns 
BM_StableSort_int32_SingleElement_1                   3.81 ns       3.71 ns 
BM_StableSort_int32_SingleElement_4                   6.57 ns       6.61 ns 
BM_StableSort_int32_SingleElement_16                  14.0 ns       15.8 ns 
BM_StableSort_int32_SingleElement_64                  38.7 ns       53.5 ns 
BM_StableSort_int32_SingleElement_256                  386 ns        554 ns 
BM_StableSort_int32_SingleElement_1024                2761 ns       3046 ns 
BM_StableSort_int32_SingleElement_4096                9179 ns      15188 ns 
BM_StableSort_int32_SingleElement_16384              34794 ns      70119 ns 
BM_StableSort_int32_SingleElement_65536             135190 ns     354755 ns 
BM_StableSort_int32_SingleElement_262144            760995 ns    1644072 ns 
BM_StableSort_int32_SingleElement_524288           1969575 ns    3343419 ns 
BM_StableSort_int32_SingleElement_1048576          4423816 ns    8346971 ns 
BM_StableSort_int32_PipeOrgan_1                       3.79 ns       3.63 ns 
BM_StableSort_int32_PipeOrgan_4                       6.21 ns       6.73 ns 
BM_StableSort_int32_PipeOrgan_16                      27.5 ns       26.0 ns 
BM_StableSort_int32_PipeOrgan_64                       291 ns        265 ns 
BM_StableSort_int32_PipeOrgan_256                     2557 ns       2518 ns 
BM_StableSort_int32_PipeOrgan_1024                    6765 ns      10976 ns 
BM_StableSort_int32_PipeOrgan_4096                   26373 ns      44537 ns 
BM_StableSort_int32_PipeOrgan_16384                 201466 ns     188582 ns 
BM_StableSort_int32_PipeOrgan_65536                1148533 ns     802368 ns 
BM_StableSort_int32_PipeOrgan_262144               2255177 ns    3477829 ns 
BM_StableSort_int32_PipeOrgan_524288               3947015 ns   10356637 ns 
BM_StableSort_int32_PipeOrgan_1048576             10274312 ns   16405366 ns 
BM_StableSort_int32_QuickSortAdversary_1              3.32 ns       4.36 ns 
BM_StableSort_int32_QuickSortAdversary_4              5.98 ns       7.44 ns 
BM_StableSort_int32_QuickSortAdversary_16             13.0 ns       16.3 ns 
BM_StableSort_int32_QuickSortAdversary_64              657 ns        616 ns 
BM_StableSort_int32_QuickSortAdversary_256            2569 ns       2483 ns 
BM_StableSort_int32_QuickSortAdversary_1024           6898 ns      19635 ns 
BM_StableSort_int32_QuickSortAdversary_4096          27092 ns      75108 ns 
BM_StableSort_int32_QuickSortAdversary_16384        190379 ns     316463 ns 
BM_StableSort_int32_QuickSortAdversary_65536       1109040 ns    1319018 ns 
BM_StableSort_int32_QuickSortAdversary_262144      4361925 ns    5472779 ns 
BM_StableSort_int32_QuickSortAdversary_524288      6528215 ns   17538983 ns 
BM_StableSort_int32_QuickSortAdversary_1048576    18345325 ns   27223926 ns 
BM_StableSort_uint32_Random_1                         3.67 ns       3.82 ns 
BM_StableSort_uint32_Random_4                         22.3 ns       21.8 ns 
BM_StableSort_uint32_Random_16                         155 ns        153 ns 
BM_StableSort_uint32_Random_64                         946 ns        976 ns 
BM_StableSort_uint32_Random_256                       5824 ns       6019 ns 
BM_StableSort_uint32_Random_1024                      4525 ns      32764 ns 
BM_StableSort_uint32_Random_4096                     17223 ns     158608 ns 
BM_StableSort_uint32_Random_16384                   134821 ns     748525 ns 
BM_StableSort_uint32_Random_65536                   716644 ns    3453325 ns 
BM_StableSort_uint32_Random_262144                 3628062 ns   16065414 ns 
BM_StableSort_uint32_Random_524288                10971334 ns   36567712 ns 
BM_StableSort_uint32_Random_1048576               22688377 ns   77533497 ns 
BM_StableSort_uint32_Ascending_1                      3.57 ns       3.44 ns 
BM_StableSort_uint32_Ascending_4                      5.73 ns       5.33 ns 
BM_StableSort_uint32_Ascending_16                     14.5 ns       14.0 ns 
BM_StableSort_uint32_Ascending_64                     50.3 ns       51.3 ns 
BM_StableSort_uint32_Ascending_256                     465 ns        467 ns 
BM_StableSort_uint32_Ascending_1024                   3042 ns       2530 ns 
BM_StableSort_uint32_Ascending_4096                   9842 ns      12207 ns 
BM_StableSort_uint32_Ascending_16384                 37994 ns      61726 ns 
BM_StableSort_uint32_Ascending_65536                148890 ns     294385 ns 
BM_StableSort_uint32_Ascending_262144               855080 ns    1422167 ns 
BM_StableSort_uint32_Ascending_524288              2154903 ns    3203018 ns 
BM_StableSort_uint32_Ascending_1048576             5002518 ns    7563817 ns 
BM_StableSort_uint32_Descending_1                     3.51 ns       3.40 ns 
BM_StableSort_uint32_Descending_4                     9.09 ns       7.95 ns 
BM_StableSort_uint32_Descending_16                    54.8 ns       74.4 ns 
BM_StableSort_uint32_Descending_64                    1003 ns       1305 ns 
BM_StableSort_uint32_Descending_256                   4545 ns       5300 ns 
BM_StableSort_uint32_Descending_1024                  4361 ns      21884 ns 
BM_StableSort_uint32_Descending_4096                 16018 ns      90534 ns 
BM_StableSort_uint32_Descending_16384               146274 ns     381943 ns 
BM_StableSort_uint32_Descending_65536               938248 ns    1536806 ns 
BM_StableSort_uint32_Descending_262144             3899300 ns    6387843 ns 
BM_StableSort_uint32_Descending_524288             5808157 ns   21959858 ns 
BM_StableSort_uint32_Descending_1048576           17520047 ns   26351912 ns 
BM_StableSort_uint32_SingleElement_1                  4.03 ns       3.97 ns 
BM_StableSort_uint32_SingleElement_4                  6.55 ns       6.41 ns 
BM_StableSort_uint32_SingleElement_16                 15.6 ns       15.8 ns 
BM_StableSort_uint32_SingleElement_64                 52.3 ns       58.7 ns 
BM_StableSort_uint32_SingleElement_256                 473 ns        485 ns 
BM_StableSort_uint32_SingleElement_1024               3020 ns       2407 ns 
BM_StableSort_uint32_SingleElement_4096               9998 ns      12527 ns 
BM_StableSort_uint32_SingleElement_16384             38072 ns      62228 ns 
BM_StableSort_uint32_SingleElement_65536            153706 ns     295662 ns 
BM_StableSort_uint32_SingleElement_262144           836532 ns    1477099 ns 
BM_StableSort_uint32_SingleElement_524288          2144900 ns    3157204 ns 
BM_StableSort_uint32_SingleElement_1048576         4995525 ns    7617233 ns 
BM_StableSort_uint32_PipeOrgan_1                      4.02 ns       3.99 ns 
BM_StableSort_uint32_PipeOrgan_4                      6.97 ns       6.84 ns 
BM_StableSort_uint32_PipeOrgan_16                     26.1 ns       29.7 ns 
BM_StableSort_uint32_PipeOrgan_64                      266 ns        333 ns 
BM_StableSort_uint32_PipeOrgan_256                    2462 ns       2892 ns 
BM_StableSort_uint32_PipeOrgan_1024                   4291 ns      12431 ns 
BM_StableSort_uint32_PipeOrgan_4096                  15638 ns      51449 ns 
BM_StableSort_uint32_PipeOrgan_16384                154563 ns     217460 ns 
BM_StableSort_uint32_PipeOrgan_65536                907724 ns     925873 ns 
BM_StableSort_uint32_PipeOrgan_262144              2394580 ns    4103575 ns 
BM_StableSort_uint32_PipeOrgan_524288              4177145 ns   13947158 ns 
BM_StableSort_uint32_PipeOrgan_1048576            11848224 ns   18807297 ns 
BM_StableSort_uint32_QuickSortAdversary_1             3.50 ns       3.43 ns 
BM_StableSort_uint32_QuickSortAdversary_4             5.88 ns       4.96 ns 
BM_StableSort_uint32_QuickSortAdversary_16            14.6 ns       14.0 ns 
BM_StableSort_uint32_QuickSortAdversary_64             576 ns        715 ns 
BM_StableSort_uint32_QuickSortAdversary_256           2353 ns       2797 ns 
BM_StableSort_uint32_QuickSortAdversary_1024          4176 ns      21775 ns 
BM_StableSort_uint32_QuickSortAdversary_4096         15565 ns      96188 ns 
BM_StableSort_uint32_QuickSortAdversary_16384       149092 ns     398332 ns 
BM_StableSort_uint32_QuickSortAdversary_65536       902488 ns    1552393 ns 
BM_StableSort_uint32_QuickSortAdversary_262144     3946517 ns    6560414 ns 
BM_StableSort_uint32_QuickSortAdversary_524288     6247114 ns   22420977 ns 
BM_StableSort_uint32_QuickSortAdversary_1048576   19892446 ns   26529576 ns 
BM_StableSort_int64_Random_1                          3.83 ns       3.98 ns 
BM_StableSort_int64_Random_4                          21.1 ns       24.0 ns 
BM_StableSort_int64_Random_16                          129 ns        136 ns 
BM_StableSort_int64_Random_64                          890 ns        906 ns 
BM_StableSort_int64_Random_256                        5542 ns       5901 ns 
BM_StableSort_int64_Random_1024                      16085 ns      33112 ns 
BM_StableSort_int64_Random_4096                      63895 ns     162181 ns 
BM_StableSort_int64_Random_16384                    348827 ns     790045 ns 
BM_StableSort_int64_Random_65536                   1488237 ns    3557506 ns 
BM_StableSort_int64_Random_262144                  8195713 ns   16315808 ns 
BM_StableSort_int64_Random_524288                 16586833 ns   38274075 ns 
BM_StableSort_int64_Random_1048576                40346644 ns   79182089 ns 
BM_StableSort_int64_Ascending_1                       3.76 ns       3.55 ns 
BM_StableSort_int64_Ascending_4                       5.82 ns       6.19 ns 
BM_StableSort_int64_Ascending_16                      11.7 ns       11.8 ns 
BM_StableSort_int64_Ascending_64                      32.9 ns       36.8 ns 
BM_StableSort_int64_Ascending_256                      415 ns        550 ns 
BM_StableSort_int64_Ascending_1024                    5352 ns       3347 ns 
BM_StableSort_int64_Ascending_4096                   17516 ns      19134 ns 
BM_StableSort_int64_Ascending_16384                  64147 ns      91099 ns 
BM_StableSort_int64_Ascending_65536                 322126 ns     434009 ns 
BM_StableSort_int64_Ascending_262144               1554669 ns    2057056 ns 
BM_StableSort_int64_Ascending_524288               3656527 ns    5016650 ns 
BM_StableSort_int64_Ascending_1048576             10469979 ns   12908613 ns 
BM_StableSort_int64_Descending_1                      4.09 ns       3.35 ns 
BM_StableSort_int64_Descending_4                      9.13 ns       8.01 ns 
BM_StableSort_int64_Descending_16                     76.8 ns       92.9 ns 
BM_StableSort_int64_Descending_64                     1336 ns       1417 ns 
BM_StableSort_int64_Descending_256                    5525 ns       5674 ns 
BM_StableSort_int64_Descending_1024                  17461 ns      22558 ns 
BM_StableSort_int64_Descending_4096                  64285 ns     102360 ns 
BM_StableSort_int64_Descending_16384                336946 ns     388940 ns 
BM_StableSort_int64_Descending_65536                837912 ns    1662169 ns 
BM_StableSort_int64_Descending_262144              3680806 ns    7494323 ns 
BM_StableSort_int64_Descending_524288             11023784 ns   24935033 ns 
BM_StableSort_int64_Descending_1048576            20023568 ns   33220712 ns 
BM_StableSort_int64_SingleElement_1                   3.37 ns       3.98 ns 
BM_StableSort_int64_SingleElement_4                   5.32 ns       6.92 ns 
BM_StableSort_int64_SingleElement_16                  10.9 ns       13.3 ns 
BM_StableSort_int64_SingleElement_64                  32.1 ns       43.8 ns 
BM_StableSort_int64_SingleElement_256                  420 ns        541 ns 
BM_StableSort_int64_SingleElement_1024                5689 ns       3381 ns 
BM_StableSort_int64_SingleElement_4096               19199 ns      17989 ns 
BM_StableSort_int64_SingleElement_16384              75754 ns      91963 ns 
BM_StableSort_int64_SingleElement_65536             357106 ns     500326 ns 
BM_StableSort_int64_SingleElement_262144           1672975 ns    2417734 ns 
BM_StableSort_int64_SingleElement_524288           3642891 ns    5200878 ns 
BM_StableSort_int64_SingleElement_1048576         11172007 ns   13729511 ns 
BM_StableSort_int64_PipeOrgan_1                       3.38 ns       3.94 ns 
BM_StableSort_int64_PipeOrgan_4                       5.73 ns       6.44 ns 
BM_StableSort_int64_PipeOrgan_16                      27.5 ns       29.0 ns 
BM_StableSort_int64_PipeOrgan_64                       310 ns        321 ns 
BM_StableSort_int64_PipeOrgan_256                     2761 ns       2918 ns 
BM_StableSort_int64_PipeOrgan_1024                   16105 ns      12525 ns 
BM_StableSort_int64_PipeOrgan_4096                   65289 ns      59990 ns 
BM_StableSort_int64_PipeOrgan_16384                 341757 ns     270636 ns 
BM_StableSort_int64_PipeOrgan_65536                 587452 ns    1126132 ns 
BM_StableSort_int64_PipeOrgan_262144               2837955 ns    5034180 ns 
BM_StableSort_int64_PipeOrgan_524288               6617313 ns   15267354 ns 
BM_StableSort_int64_PipeOrgan_1048576             15208796 ns   23162989 ns 
BM_StableSort_int64_QuickSortAdversary_1              3.77 ns       3.45 ns 
BM_StableSort_int64_QuickSortAdversary_4              5.55 ns       5.20 ns 
BM_StableSort_int64_QuickSortAdversary_16             12.5 ns       11.5 ns 
BM_StableSort_int64_QuickSortAdversary_64              646 ns        750 ns 
BM_StableSort_int64_QuickSortAdversary_256            2655 ns       3539 ns 
BM_StableSort_int64_QuickSortAdversary_1024          16373 ns      22349 ns 
BM_StableSort_int64_QuickSortAdversary_4096          62306 ns      97248 ns 
BM_StableSort_int64_QuickSortAdversary_16384        321755 ns     388084 ns 
BM_StableSort_int64_QuickSortAdversary_65536       1374694 ns    1596091 ns 
BM_StableSort_int64_QuickSortAdversary_262144      4374661 ns    6894139 ns 
BM_StableSort_int64_QuickSortAdversary_524288     12736074 ns   23932229 ns 
BM_StableSort_int64_QuickSortAdversary_1048576    22615219 ns   33355629 ns 
BM_StableSort_uint64_Random_1                         3.82 ns       3.49 ns 
BM_StableSort_uint64_Random_4                         22.4 ns       23.4 ns 
BM_StableSort_uint64_Random_16                         154 ns        146 ns 
BM_StableSort_uint64_Random_64                         924 ns        926 ns 
BM_StableSort_uint64_Random_256                       5864 ns       5913 ns 
BM_StableSort_uint64_Random_1024                      7168 ns      31746 ns 
BM_StableSort_uint64_Random_4096                     27668 ns     154224 ns 
BM_StableSort_uint64_Random_16384                   219526 ns     755205 ns 
BM_StableSort_uint64_Random_65536                   965251 ns    3490165 ns 
BM_StableSort_uint64_Random_262144                 6262162 ns   15889589 ns 
BM_StableSort_uint64_Random_524288                12530078 ns   36458581 ns 
BM_StableSort_uint64_Random_1048576               38462191 ns   75168445 ns 
BM_StableSort_uint64_Ascending_1                      3.30 ns       3.35 ns 
BM_StableSort_uint64_Ascending_4                      5.65 ns       5.84 ns 
BM_StableSort_uint64_Ascending_16                     14.7 ns       12.6 ns 
BM_StableSort_uint64_Ascending_64                     55.3 ns       34.6 ns 
BM_StableSort_uint64_Ascending_256                     513 ns        533 ns 
BM_StableSort_uint64_Ascending_1024                   5541 ns       3189 ns 
BM_StableSort_uint64_Ascending_4096                  17706 ns      20326 ns 
BM_StableSort_uint64_Ascending_16384                 66420 ns      93757 ns 
BM_StableSort_uint64_Ascending_65536                341425 ns     435016 ns 
BM_StableSort_uint64_Ascending_262144              1595691 ns    2088317 ns 
BM_StableSort_uint64_Ascending_524288              3808703 ns    5092832 ns 
BM_StableSort_uint64_Ascending_1048576            11060417 ns   13023250 ns 
BM_StableSort_uint64_Descending_1                     3.29 ns       3.35 ns 
BM_StableSort_uint64_Descending_4                     8.65 ns       7.92 ns 
BM_StableSort_uint64_Descending_16                    54.7 ns       80.2 ns 
BM_StableSort_uint64_Descending_64                    1028 ns       1307 ns 
BM_StableSort_uint64_Descending_256                   4521 ns       5635 ns 
BM_StableSort_uint64_Descending_1024                  7122 ns      23323 ns 
BM_StableSort_uint64_Descending_4096                 30538 ns      95892 ns 
BM_StableSort_uint64_Descending_16384               195565 ns     392721 ns 
BM_StableSort_uint64_Descending_65536               852002 ns    1720358 ns 
BM_StableSort_uint64_Descending_262144             3737884 ns    7484130 ns 
BM_StableSort_uint64_Descending_524288            11159345 ns   25690770 ns 
BM_StableSort_uint64_Descending_1048576           20648864 ns   33057383 ns 
BM_StableSort_uint64_SingleElement_1                  3.62 ns       4.10 ns 
BM_StableSort_uint64_SingleElement_4                  6.73 ns       6.64 ns 
BM_StableSort_uint64_SingleElement_16                 14.9 ns       11.3 ns 
BM_StableSort_uint64_SingleElement_64                 52.0 ns       33.0 ns 
BM_StableSort_uint64_SingleElement_256                 511 ns        582 ns 
BM_StableSort_uint64_SingleElement_1024               6499 ns       3287 ns 
BM_StableSort_uint64_SingleElement_4096              22190 ns      17616 ns 
BM_StableSort_uint64_SingleElement_16384             84378 ns      86885 ns 
BM_StableSort_uint64_SingleElement_65536            466257 ns     457144 ns 
BM_StableSort_uint64_SingleElement_262144          1993687 ns    2361999 ns 
BM_StableSort_uint64_SingleElement_524288          4759565 ns    5096771 ns 
BM_StableSort_uint64_SingleElement_1048576        12426111 ns   13468453 ns 
BM_StableSort_uint64_PipeOrgan_1                      3.73 ns       3.94 ns 
BM_StableSort_uint64_PipeOrgan_4                      7.18 ns       7.54 ns 
BM_StableSort_uint64_PipeOrgan_16                     25.2 ns       29.1 ns 
BM_StableSort_uint64_PipeOrgan_64                      260 ns        321 ns 
BM_StableSort_uint64_PipeOrgan_256                    2468 ns       2970 ns 
BM_StableSort_uint64_PipeOrgan_1024                   7025 ns      12912 ns 
BM_StableSort_uint64_PipeOrgan_4096                  28968 ns      53379 ns 
BM_StableSort_uint64_PipeOrgan_16384                194156 ns     239790 ns 
BM_StableSort_uint64_PipeOrgan_65536                599491 ns     993800 ns 
BM_StableSort_uint64_PipeOrgan_262144              2648585 ns    4689680 ns 
BM_StableSort_uint64_PipeOrgan_524288              7621109 ns   15401808 ns 
BM_StableSort_uint64_PipeOrgan_1048576            15608814 ns   23484821 ns 
BM_StableSort_uint64_QuickSortAdversary_1             3.38 ns       3.54 ns 
BM_StableSort_uint64_QuickSortAdversary_4             5.50 ns       6.03 ns 
BM_StableSort_uint64_QuickSortAdversary_16            14.2 ns       11.0 ns 
BM_StableSort_uint64_QuickSortAdversary_64             597 ns        688 ns 
BM_StableSort_uint64_QuickSortAdversary_256           2446 ns       2818 ns 
BM_StableSort_uint64_QuickSortAdversary_1024          7266 ns      20319 ns 
BM_StableSort_uint64_QuickSortAdversary_4096         31155 ns      89112 ns 
BM_StableSort_uint64_QuickSortAdversary_16384       201033 ns     390574 ns 
BM_StableSort_uint64_QuickSortAdversary_65536       871014 ns    1685639 ns 
BM_StableSort_uint64_QuickSortAdversary_262144     3978535 ns    7265830 ns 
BM_StableSort_uint64_QuickSortAdversary_524288    10279721 ns   25350004 ns 
BM_StableSort_uint64_QuickSortAdversary_1048576   20256585 ns   33054393 ns 
```

>From 5717ad80b633d5a2005b98bc35001c3cd0a47887 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=94=D0=BC=D0=B8=D1=82=D1=80=D0=B8=D0=B9=20=D0=98=D0=B7?=
 =?UTF-8?q?=D0=B2=D0=BE=D0=BB=D0=BE=D0=B2?= <dmitriy at izvolov.ru>
Date: Sun, 5 May 2024 11:08:26 +0300
Subject: [PATCH 1/2] radix-sort

---
 libcxx/include/CMakeLists.txt            |   1 +
 libcxx/include/__algorithm/radix_sort.h  | 410 +++++++++++++++++++++++
 libcxx/include/__algorithm/stable_sort.h | 111 ++++--
 libcxx/include/module.modulemap          |   1 +
 4 files changed, 491 insertions(+), 32 deletions(-)
 create mode 100644 libcxx/include/__algorithm/radix_sort.h

diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 32579272858a8e..95e4e3faf88671 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -74,6 +74,7 @@ set(files
   __algorithm/prev_permutation.h
   __algorithm/pstl.h
   __algorithm/push_heap.h
+  __algorithm/radix_sort.h
   __algorithm/ranges_adjacent_find.h
   __algorithm/ranges_all_of.h
   __algorithm/ranges_any_of.h
diff --git a/libcxx/include/__algorithm/radix_sort.h b/libcxx/include/__algorithm/radix_sort.h
new file mode 100644
index 00000000000000..5e14dec9df0918
--- /dev/null
+++ b/libcxx/include/__algorithm/radix_sort.h
@@ -0,0 +1,410 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_RADIX_SORT_H
+#define _LIBCPP___ALGORITHM_RADIX_SORT_H
+
+#include <__algorithm/copy.h>
+#include <__algorithm/for_each.h>
+#include <__config>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/move_iterator.h>
+#include <__iterator/next.h>
+#include <__numeric/partial_sum.h>
+#include <__type_traits/decay.h>
+#include <__type_traits/enable_if.h>
+#include <__type_traits/invoke.h>
+#include <__type_traits/is_assignable.h>
+#include <__type_traits/is_integral.h>
+#include <__type_traits/is_unsigned.h>
+#include <__type_traits/make_unsigned.h>
+#include <__utility/forward.h>
+#include <__utility/integer_sequence.h>
+#include <__utility/move.h>
+#include <__utility/pair.h>
+#include <climits>
+#include <cstdint>
+#include <initializer_list>
+#include <limits>
+#include <stdexcept>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 14
+
+inline void __variadic_expansion_dummy(initializer_list<int>) {}
+
+#  define EXPAND_VARIADIC(expression) __variadic_expansion_dummy({(expression, 0)...})
+
+template <typename _Iterator>
+constexpr auto __move_assign_please(_Iterator __i)
+    -> enable_if_t<is_move_assignable<typename iterator_traits<_Iterator>::value_type>::value,
+                   move_iterator<_Iterator> > {
+  return make_move_iterator(std::move(__i));
+}
+
+template <typename _Iterator>
+constexpr auto __move_assign_please(_Iterator __i)
+    -> enable_if_t<not is_move_assignable<typename iterator_traits<_Iterator>::value_type>::value, _Iterator> {
+  return __i;
+}
+
+template <typename _Integer>
+constexpr _Integer __intlog2_impl(_Integer __integer) {
+  auto __degree = _Integer{0};
+
+  while ((__integer >>= 1) > 0) {
+    ++__degree;
+  }
+
+  return __degree;
+}
+
+template <typename _Integer>
+constexpr _Integer __intlog2(_Integer __integer) {
+  static_assert(is_integral<_Integer>::value, "Must be an integral type");
+
+  return __integer > 0 ? __intlog2_impl(__integer)
+                       : throw domain_error("The binary logarithm is not defined on non-positive numbers");
+}
+
+template <typename _InputIterator, typename _OutputIterator>
+pair<_OutputIterator, typename iterator_traits<_InputIterator>::value_type>
+__partial_sum_max(_InputIterator __first, _InputIterator __last, _OutputIterator __result) {
+  if (__first == __last)
+    return {__result, 0};
+
+  auto __max                                                 = *__first;
+  typename iterator_traits<_InputIterator>::value_type __sum = *__first;
+  *__result                                                  = __sum;
+
+  while (++__first != __last) {
+    if (__max < *__first) {
+      __max = *__first;
+    }
+    __sum       = std::move(__sum) + *__first;
+    *++__result = __sum;
+  }
+  return {++__result, __max};
+}
+
+template <typename _Value, typename _Map, typename _Radix>
+struct __radix_sort_traits {
+  using image_type = decay_t<invoke_result_t<_Map, _Value> >;
+  static_assert(is_integral<image_type>::value, "");
+  static_assert(is_unsigned<image_type>::value, "");
+
+  using radix_type = decay_t<invoke_result_t<_Radix, image_type> >;
+  static_assert(is_integral<radix_type>::value, "");
+
+  constexpr static auto radix_value_range = numeric_limits<radix_type>::max() + 1;
+  constexpr static auto radix_size        = __intlog2<uint64_t>(radix_value_range);
+  constexpr static auto radix_count       = sizeof(image_type) * CHAR_BIT / radix_size;
+};
+
+template <typename _Value, typename _Map>
+struct __counting_sort_traits {
+  using image_type = decay_t<invoke_result_t<_Map, _Value> >;
+  static_assert(is_integral<image_type>::value, "");
+  static_assert(is_unsigned<image_type>::value, "");
+
+  constexpr static const auto value_range = numeric_limits<image_type>::max() + 1;
+  constexpr static auto radix_size        = __intlog2<uint64_t>(value_range);
+};
+
+template <typename _Radix>
+auto __nth_radix(size_t __radix_number, _Radix __radix) {
+  return [__radix_number, __radix = std::move(__radix)](auto __n) {
+    using value_type = decltype(__n);
+    static_assert(is_integral<value_type>::value, "");
+    static_assert(is_unsigned<value_type>::value, "");
+    using traits = __counting_sort_traits<value_type, _Radix>;
+
+    return __radix(static_cast<value_type>(__n >> traits::radix_size * __radix_number));
+  };
+}
+
+template <typename _ForwardIterator, typename _Map, typename _RandomAccessIterator>
+void __count(_ForwardIterator __first, _ForwardIterator __last, _Map __map, _RandomAccessIterator __counters) {
+  std::for_each(__first, __last, [&__counters, &__map](const auto& __preimage) { ++__counters[__map(__preimage)]; });
+}
+
+template <typename _ForwardIterator, typename _Map, typename _RandomAccessIterator>
+void __collect(_ForwardIterator __first, _ForwardIterator __last, _Map __map, _RandomAccessIterator __counters) {
+  using value_type = typename iterator_traits<_ForwardIterator>::value_type;
+  using traits     = __counting_sort_traits<value_type, _Map>;
+
+  __count(__first, __last, __map, __counters);
+
+  const auto __counters_end = __counters + traits::value_range;
+  partial_sum(__counters, __counters_end, __counters);
+}
+
+template <typename _ForwardIterator, typename _RandomAccessIterator1, typename _Map, typename _RandomAccessIterator2>
+void __dispose(_ForwardIterator __first,
+               _ForwardIterator __last,
+               _RandomAccessIterator1 __result,
+               _Map __map,
+               _RandomAccessIterator2 __counters) {
+  std::for_each(__first, __last, [&__result, &__counters, &__map](auto&& __preimage) {
+    auto __index      = __counters[__map(__preimage)]++;
+    __result[__index] = std::forward<decltype(__preimage)>(__preimage);
+  });
+}
+
+template <typename _BidirectionalIterator,
+          typename _RandomAccessIterator1,
+          typename _Map,
+          typename _RandomAccessIterator2>
+void dispose_backward(_BidirectionalIterator __first,
+                      _BidirectionalIterator __last,
+                      _RandomAccessIterator1 __result,
+                      _Map __map,
+                      _RandomAccessIterator2 __counters) {
+  std::for_each(make_reverse_iterator(__last),
+                make_reverse_iterator(__first),
+                [&__result, &__counters, &__map](auto&& __preimage) {
+                  auto __index      = --__counters[__map(__preimage)];
+                  __result[__index] = std::forward<decltype(__preimage)>(__preimage);
+                });
+}
+
+template <typename _ForwardIterator,
+          typename _Map,
+          typename _Radix,
+          typename _RandomAccessIterator1,
+          typename _RandomAccessIterator2,
+          size_t... _Radices>
+bool __collect_impl(
+    _ForwardIterator __first,
+    _ForwardIterator __last,
+    _Map __map,
+    _Radix __radix,
+    _RandomAccessIterator1 __counters,
+    _RandomAccessIterator2 __maximums,
+    index_sequence<_Radices...>) {
+  using value_type                   = typename iterator_traits<_ForwardIterator>::value_type;
+  constexpr auto __radix_value_range = __radix_sort_traits<value_type, _Map, _Radix>::radix_value_range;
+
+  auto __previous  = numeric_limits<invoke_result_t<_Map, value_type> >::min();
+  auto __is_sorted = true;
+  for_each(__first, __last, [&__counters, &__map, &__radix, &__previous, &__is_sorted](const auto& value) {
+    auto __current = __map(value);
+    __is_sorted &= (__current >= __previous);
+    __previous = __current;
+
+    EXPAND_VARIADIC(++__counters[_Radices][__nth_radix(_Radices, __radix)(__current)]);
+  });
+
+  EXPAND_VARIADIC(
+      __maximums[_Radices] =
+          __partial_sum_max(__counters[_Radices], __counters[_Radices] + __radix_value_range, __counters[_Radices])
+              .second);
+
+  return __is_sorted;
+}
+
+template <typename _ForwardIterator,
+          typename _Map,
+          typename _Radix,
+          typename _RandomAccessIterator1,
+          typename _RandomAccessIterator2>
+bool __collect(_ForwardIterator __first,
+               _ForwardIterator __last,
+               _Map __map,
+               _Radix __radix,
+               _RandomAccessIterator1 __counters,
+               _RandomAccessIterator2 __maximums) {
+  using value_type             = typename iterator_traits<_ForwardIterator>::value_type;
+  constexpr auto __radix_count = __radix_sort_traits<value_type, _Map, _Radix>::radix_count;
+  return __collect_impl(__first, __last, __map, __radix, __counters, __maximums, make_index_sequence<__radix_count>());
+}
+
+template <typename _BidirectionalIterator,
+          typename _RandomAccessIterator1,
+          typename _Map,
+          typename _RandomAccessIterator2>
+void __dispose_backward(_BidirectionalIterator __first,
+                        _BidirectionalIterator __last,
+                        _RandomAccessIterator1 __result,
+                        _Map __map,
+                        _RandomAccessIterator2 __counters) {
+  for_each(
+      make_reverse_iterator(__last), make_reverse_iterator(__first), [&__result, &__counters, &__map](auto&& preimage) {
+        auto __index      = --__counters[__map(preimage)];
+        __result[__index] = std::forward<decltype(preimage)>(preimage);
+      });
+}
+
+template <typename _ForwardIterator, typename _RandomAccessIterator, typename _Map>
+_RandomAccessIterator
+__counting_sort_impl(_ForwardIterator __first, _ForwardIterator __last, _RandomAccessIterator __result, _Map __map) {
+  using value_type = typename iterator_traits<_ForwardIterator>::value_type;
+  using traits     = __counting_sort_traits<value_type, _Map>;
+
+  using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;
+  difference_type __counters[traits::value_range + 1] = {0};
+
+  __collect(__first, __last, __map, next(std::begin(__counters)));
+  __dispose(__first, __last, __result, __map, std::begin(__counters));
+
+  return __result + __counters[traits::value_range];
+}
+
+template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _Map, typename _Radix>
+typename enable_if<
+    __radix_sort_traits<typename iterator_traits<_RandomAccessIterator1>::value_type, _Map, _Radix>::radix_count == 1,
+    void>::type
+__radix_sort_impl(_RandomAccessIterator1 __first,
+                  _RandomAccessIterator1 __last,
+                  _RandomAccessIterator2 buffer,
+                  _Map __map,
+                  _Radix __radix) {
+  auto __buffer_end = __counting_sort_impl(
+      __move_assign_please(__first), __move_assign_please(__last), buffer, [&__map, &__radix](const auto& value) {
+        return __radix(__map(value));
+      });
+
+  std::copy(__move_assign_please(buffer), __move_assign_please(__buffer_end), __first);
+}
+
+template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _Map, typename _Radix>
+typename enable_if<
+    __radix_sort_traits<typename iterator_traits<_RandomAccessIterator1>::value_type, _Map, _Radix>::radix_count % 2 ==
+        0,
+    void>::type
+__radix_sort_impl(_RandomAccessIterator1 __first,
+                  _RandomAccessIterator1 __last,
+                  _RandomAccessIterator2 __buffer_begin,
+                  _Map __map,
+                  _Radix __radix) {
+  using value_type = typename iterator_traits<_RandomAccessIterator1>::value_type;
+  using traits     = __radix_sort_traits<value_type, _Map, _Radix>;
+
+  using difference_type = typename iterator_traits<_RandomAccessIterator1>::difference_type;
+  difference_type __counters[traits::radix_count][traits::radix_value_range] = {{0}};
+  difference_type __maximums[traits::radix_count]                            = {0};
+  const auto __is_sorted = __collect(__first, __last, __map, __radix, __counters, __maximums);
+  if (not __is_sorted) {
+    const auto __range_size = distance(__first, __last);
+    auto __buffer_end       = __buffer_begin + __range_size;
+    for (size_t __radix_number = 0; __radix_number < traits::radix_count; __radix_number += 2) {
+      const auto __n0th_is_single = __maximums[__radix_number] == __range_size;
+      const auto __n1th_is_single = __maximums[__radix_number + 1] == __range_size;
+
+      if (__n0th_is_single && __n1th_is_single) {
+        continue;
+      }
+
+      if (__n0th_is_single) {
+        copy(__move_assign_please(__first), __move_assign_please(__last), __buffer_begin);
+      } else {
+        auto __n0th = [__radix_number, &__map, &__radix](const auto& __v) {
+          return __nth_radix(__radix_number, __radix)(__map(__v));
+        };
+        __dispose_backward(
+            __move_assign_please(__first),
+            __move_assign_please(__last),
+            __buffer_begin,
+            __n0th,
+            __counters[__radix_number]);
+      }
+
+      if (__n1th_is_single) {
+        copy(__move_assign_please(__buffer_begin), __move_assign_please(__buffer_end), __first);
+      } else {
+        auto __n1th = [__radix_number, &__map, &__radix](const auto& __v) {
+          return __nth_radix(__radix_number + 1, __radix)(__map(__v));
+        };
+        __dispose_backward(
+            __move_assign_please(__buffer_begin),
+            __move_assign_please(__buffer_end),
+            __first,
+            __n1th,
+            __counters[__radix_number + 1]);
+      }
+    }
+  }
+}
+
+constexpr auto __to_unsigned(bool __b) { return __b; }
+
+template <typename _Ip>
+constexpr auto __to_unsigned(_Ip __n) {
+  constexpr const auto __min_value = numeric_limits<_Ip>::min();
+  return static_cast<make_unsigned_t<_Ip> >(__n ^ __min_value);
+}
+
+struct __identity_fn {
+  template <typename _Tp>
+  constexpr decltype(auto) operator()(_Tp&& __value) const {
+    return std::forward<_Tp>(__value);
+  }
+};
+
+struct __low_byte_fn {
+  template <typename _Ip>
+  constexpr uint8_t operator()(_Ip __integer) const {
+    static_assert(is_integral<_Ip>::value, "");
+    static_assert(is_unsigned<_Ip>::value, "");
+
+    return static_cast<uint8_t>(__integer & 0xff);
+  }
+};
+
+template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, typename _Map, typename _Radix>
+void __radix_sort(_RandomAccessIterator1 __first,
+                  _RandomAccessIterator1 __last,
+                  _RandomAccessIterator2 buffer,
+                  _Map __map,
+                  _Radix __radix) {
+  auto __map_to_unsigned = [__map = std::move(__map)](const auto& x) { return __to_unsigned(__map(x)); };
+  __radix_sort_impl(__first, __last, buffer, __map_to_unsigned, __radix);
+}
+
+template <typename _RandomAccessIterator1, typename _RandomAccessIterator2>
+void __radix_sort(_RandomAccessIterator1 __first, _RandomAccessIterator1 __last, _RandomAccessIterator2 buffer) {
+  __radix_sort(__first, __last, buffer, __identity_fn{}, __low_byte_fn{});
+}
+
+template <typename _RandomAccessIterator1, typename _RandomAccessIterator2>
+bool __radix_sort(
+    _RandomAccessIterator1 __first, _RandomAccessIterator1 __last, _RandomAccessIterator2 buffer, _BoolConstant<true>) {
+  __radix_sort(__first, __last, buffer, __identity_fn{}, __low_byte_fn{});
+  return true;
+}
+
+template <typename _RandomAccessIterator1, typename _RandomAccessIterator2>
+bool __radix_sort(_RandomAccessIterator1, _RandomAccessIterator1, _RandomAccessIterator2, _BoolConstant<false>) {
+  return false;
+}
+
+#  undef EXPAND_VARIADIC
+
+#else // _LIBCPP_STD_VER > 14
+
+template <typename _RandomAccessIterator1, typename _RandomAccessIterator2, bool _B>
+bool __radix_sort(_RandomAccessIterator1, _RandomAccessIterator1, _RandomAccessIterator2, _BoolConstant<_B>) {
+  return false;
+}
+
+#endif // _LIBCPP_STD_VER > 14
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___ALGORITHM_RADIX_SORT_H
diff --git a/libcxx/include/__algorithm/stable_sort.h b/libcxx/include/__algorithm/stable_sort.h
index 726e7e16b3564a..f8624726a4e323 100644
--- a/libcxx/include/__algorithm/stable_sort.h
+++ b/libcxx/include/__algorithm/stable_sort.h
@@ -13,6 +13,7 @@
 #include <__algorithm/comp_ref_type.h>
 #include <__algorithm/inplace_merge.h>
 #include <__algorithm/iterator_operations.h>
+#include <__algorithm/radix_sort.h>
 #include <__algorithm/sort.h>
 #include <__config>
 #include <__debug_utils/strict_weak_ordering_check.h>
@@ -20,6 +21,9 @@
 #include <__memory/destruct_n.h>
 #include <__memory/temporary_buffer.h>
 #include <__memory/unique_ptr.h>
+#include <__type_traits/integral_constant.h>
+#include <__type_traits/is_integral.h>
+#include <__type_traits/is_same.h>
 #include <__type_traits/is_trivially_assignable.h>
 #include <__utility/move.h>
 #include <__utility/pair.h>
@@ -133,20 +137,24 @@ _LIBCPP_HIDE_FROM_ABI void __merge_move_assign(
     *__result = _Ops::__iter_move(__first2);
 }
 
-template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
-void __stable_sort(_RandomAccessIterator __first,
-                   _RandomAccessIterator __last,
-                   _Compare __comp,
-                   typename iterator_traits<_RandomAccessIterator>::difference_type __len,
-                   typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
-                   ptrdiff_t __buff_size);
+template <class _AlgPolicy, class _Compare, class _RandomAccessIterator, bool _EnableRadixSort>
+void __stable_sort(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp,
+    typename iterator_traits<_RandomAccessIterator>::difference_type __len,
+    typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
+    ptrdiff_t __buff_size,
+    _BoolConstant<_EnableRadixSort>);
 
-template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
-void __stable_sort_move(_RandomAccessIterator __first1,
-                        _RandomAccessIterator __last1,
-                        _Compare __comp,
-                        typename iterator_traits<_RandomAccessIterator>::difference_type __len,
-                        typename iterator_traits<_RandomAccessIterator>::value_type* __first2) {
+template <class _AlgPolicy, class _Compare, class _RandomAccessIterator, bool _EnableRadixSort>
+void __stable_sort_move(
+    _RandomAccessIterator __first1,
+    _RandomAccessIterator __last1,
+    _Compare __comp,
+    typename iterator_traits<_RandomAccessIterator>::difference_type __len,
+    typename iterator_traits<_RandomAccessIterator>::value_type* __first2,
+    _BoolConstant<_EnableRadixSort> __rs) {
   using _Ops = _IterOps<_AlgPolicy>;
 
   typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
@@ -179,8 +187,8 @@ void __stable_sort_move(_RandomAccessIterator __first1,
   }
   typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
   _RandomAccessIterator __m                                             = __first1 + __l2;
-  std::__stable_sort<_AlgPolicy, _Compare>(__first1, __m, __comp, __l2, __first2, __l2);
-  std::__stable_sort<_AlgPolicy, _Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
+  std::__stable_sort<_AlgPolicy, _Compare>(__first1, __m, __comp, __l2, __first2, __l2, __rs);
+  std::__stable_sort<_AlgPolicy, _Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2, __rs);
   std::__merge_move_construct<_AlgPolicy, _Compare>(__first1, __m, __m, __last1, __first2, __comp);
 }
 
@@ -189,13 +197,35 @@ struct __stable_sort_switch {
   static const unsigned value = 128 * is_trivially_copy_assignable<_Tp>::value;
 };
 
-template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
-void __stable_sort(_RandomAccessIterator __first,
-                   _RandomAccessIterator __last,
-                   _Compare __comp,
-                   typename iterator_traits<_RandomAccessIterator>::difference_type __len,
-                   typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
-                   ptrdiff_t __buff_size) {
+template <class _Tp, class = void>
+struct __radix_sort_min_switch {
+  static const unsigned value = (1 << 10);
+};
+
+template <class _Int8>
+struct __radix_sort_min_switch<_Int8, enable_if_t<is_integral_v<_Int8> && sizeof(_Int8) == 1>> {
+  static const unsigned value = (1 << 8);
+};
+
+template <class _Tp, class = void>
+struct __radix_sort_max_switch {
+  static const unsigned value = (1 << 16);
+};
+
+template <class _Int64>
+struct __radix_sort_max_switch<_Int64, enable_if_t<is_integral_v<_Int64> && sizeof(_Int64) == 8>> {
+  static const unsigned value = (1 << 15);
+};
+
+template <class _AlgPolicy, class _Compare, class _RandomAccessIterator, bool _EnableRadixSort>
+void __stable_sort(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare __comp,
+    typename iterator_traits<_RandomAccessIterator>::difference_type __len,
+    typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
+    ptrdiff_t __buff_size,
+    _BoolConstant<_EnableRadixSort> __rs) {
   typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
   typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
   switch (__len) {
@@ -211,14 +241,20 @@ void __stable_sort(_RandomAccessIterator __first,
     std::__insertion_sort<_AlgPolicy, _Compare>(__first, __last, __comp);
     return;
   }
+  if (__len <= __buff_size && __len >= static_cast<difference_type>(__radix_sort_min_switch<value_type>::value) &&
+      __len <= static_cast<difference_type>(__radix_sort_max_switch<value_type>::value)) {
+    if (std::__radix_sort(__first, __last, __buff, __rs)) {
+      return;
+    }
+  }
   typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
   _RandomAccessIterator __m                                             = __first + __l2;
   if (__len <= __buff_size) {
     __destruct_n __d(0);
     unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
-    std::__stable_sort_move<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff);
+    std::__stable_sort_move<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff, __rs);
     __d.__set(__l2, (value_type*)nullptr);
-    std::__stable_sort_move<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
+    std::__stable_sort_move<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff + __l2, __rs);
     __d.__set(__len, (value_type*)nullptr);
     std::__merge_move_assign<_AlgPolicy, _Compare>(
         __buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
@@ -229,14 +265,17 @@ void __stable_sort(_RandomAccessIterator __first,
     //                                  __first, __comp);
     return;
   }
-  std::__stable_sort<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
-  std::__stable_sort<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
+  std::__stable_sort<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff, __buff_size, __rs);
+  std::__stable_sort<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size, __rs);
   std::__inplace_merge<_AlgPolicy>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
 }
 
-template <class _AlgPolicy, class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_HIDE_FROM_ABI void
-__stable_sort_impl(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare& __comp) {
+template <class _AlgPolicy, class _RandomAccessIterator, class _Compare, bool _EnableRadixSort = false>
+inline _LIBCPP_HIDE_FROM_ABI void __stable_sort_impl(
+    _RandomAccessIterator __first,
+    _RandomAccessIterator __last,
+    _Compare& __comp,
+    _BoolConstant<_EnableRadixSort> __rs = _BoolConstant<false>{}) {
   using value_type      = typename iterator_traits<_RandomAccessIterator>::value_type;
   using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;
 
@@ -251,19 +290,27 @@ __stable_sort_impl(_RandomAccessIterator __first, _RandomAccessIterator __last,
     __h.reset(__buf.first);
   }
 
-  std::__stable_sort<_AlgPolicy, __comp_ref_type<_Compare> >(__first, __last, __comp, __len, __buf.first, __buf.second);
+  std::__stable_sort<_AlgPolicy, __comp_ref_type<_Compare> >(
+      __first, __last, __comp, __len, __buf.first, __buf.second, __rs);
   std::__check_strict_weak_ordering_sorted(__first, __last, __comp);
 }
 
 template <class _RandomAccessIterator, class _Compare>
 inline _LIBCPP_HIDE_FROM_ABI void
 stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
-  std::__stable_sort_impl<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp);
+  std::__stable_sort_impl<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp, _BoolConstant<false>());
 }
 
 template <class _RandomAccessIterator>
 inline _LIBCPP_HIDE_FROM_ABI void stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last) {
-  std::stable_sort(__first, __last, __less<>());
+  using value_type     = typename iterator_traits<_RandomAccessIterator>::value_type;
+  using reference_type = typename iterator_traits<_RandomAccessIterator>::reference;
+  auto __comp          = __less<>();
+  std::__stable_sort_impl<_ClassicAlgPolicy>(
+      std::move(__first),
+      std::move(__last),
+      __comp,
+      _BoolConstant < is_integral<value_type>::value && is_same<value_type&, reference_type>::value > ());
 }
 
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
index 13d0dce34d97e3..b6125add8acf2d 100644
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -720,6 +720,7 @@ module std_private_algorithm_pstl                                        [system
   export *
 }
 module std_private_algorithm_push_heap                                   [system] { header "__algorithm/push_heap.h" }
+module std_private_algorithm_radix_sort                                  [system] { header "__algorithm/radix_sort.h" }
 module std_private_algorithm_ranges_adjacent_find                        [system] { header "__algorithm/ranges_adjacent_find.h" }
 module std_private_algorithm_ranges_all_of                               [system] { header "__algorithm/ranges_all_of.h" }
 module std_private_algorithm_ranges_any_of                               [system] { header "__algorithm/ranges_any_of.h" }

>From edaab46ed6286d4170daaad78af6bfad8791b6c4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=94=D0=BC=D0=B8=D1=82=D1=80=D0=B8=D0=B9=20=D0=98=D0=B7?=
 =?UTF-8?q?=D0=B2=D0=BE=D0=BB=D0=BE=D0=B2?= <dmitriy at izvolov.ru>
Date: Sat, 17 Aug 2024 17:21:06 +0300
Subject: [PATCH 2/2] ranged

---
 libcxx/include/__algorithm/ranges_stable_sort.h | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/libcxx/include/__algorithm/ranges_stable_sort.h b/libcxx/include/__algorithm/ranges_stable_sort.h
index 9c7df80ae98722..96d84b208687fc 100644
--- a/libcxx/include/__algorithm/ranges_stable_sort.h
+++ b/libcxx/include/__algorithm/ranges_stable_sort.h
@@ -24,6 +24,8 @@
 #include <__ranges/access.h>
 #include <__ranges/concepts.h>
 #include <__ranges/dangling.h>
+#include <__type_traits/is_integral.h>
+#include <__type_traits/is_same.h>
 #include <__utility/forward.h>
 #include <__utility/move.h>
 
@@ -45,7 +47,18 @@ struct __stable_sort {
     auto __last_iter = ranges::next(__first, __last);
 
     auto&& __projected_comp = std::__make_projected(__comp, __proj);
-    std::__stable_sort_impl<_RangeAlgPolicy>(std::move(__first), __last_iter, __projected_comp);
+    constexpr auto __default_comp        = is_same_v<_Comp, ranges::less>;
+    constexpr auto __default_proj        = is_same_v<_Proj, identity>;
+    constexpr auto __integral_value      = is_integral_v<iter_value_t<_Iter>>;
+    constexpr auto __integral_projection = __default_proj && __integral_value;
+    // constexpr auto __integral_projection = is_integral_v<remove_reference_t<invoke_result_t<_Proj&,
+    // iter_value_t<_Iter>>>>;
+    // TODO: Support projection in stable_sort
+    std::__stable_sort_impl<_RangeAlgPolicy>(
+        std::move(__first),
+        __last_iter,
+        __projected_comp,
+        _BoolConstant < __default_comp && __integral_projection > {});
 
     return __last_iter;
   }



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