Support for AVX2 argsort/argselect/key-value sort

[sterrettm2]

This adds support for argsort, argselect, and kv sort for AVX2.

Benchmark                                                                        Time             CPU      Time Old      Time New       CPU Old       CPU New
-------------------------------------------------------------------------------------------------------------------------------------------------------------
[scalarargsort.*random_ vs. simdargsort.*random_]128/int64_t                  +1.2711         +1.2711           727          1652           727          1652
[scalarargsort.*random_ vs. simdargsort.*random_]256/int64_t                  +1.5339         +1.5339          1588          4024          1588          4024
[scalarargsort.*random_ vs. simdargsort.*random_]512/int64_t                  +1.9735         +1.9736          3544         10540          3544         10539
[scalarargsort.*random_ vs. simdargsort.*random_]1k/int64_t                   +0.4899         +0.4900         15180         22617         15179         22616
[scalarargsort.*random_ vs. simdargsort.*random_]5k/int64_t                   -0.5218         -0.5218        282968        135304        282948        135298
[scalarargsort.*random_ vs. simdargsort.*random_]100k/int64_t                 -0.5681         -0.5681       8460175       3654211       8459586       3653843
[scalarargsort.*random_ vs. simdargsort.*random_]1m/int64_t                   -0.4836         -0.4836     114586394      59170334     114575027      59163423
[scalarargsort.*random_ vs. simdargsort.*random_]10m/int64_t                  -0.3137         -0.3137    2054677762    1410045438    2054394419    1409915110
[scalarargsort.*random_ vs. simdargsort.*random_]128/uint64_t                 +1.4105         +1.4106           772          1860           772          1860
[scalarargsort.*random_ vs. simdargsort.*random_]256/uint64_t                 +1.6515         +1.6515          1656          4390          1656          4390
[scalarargsort.*random_ vs. simdargsort.*random_]512/uint64_t                 +2.1449         +2.1450          3651         11481          3650         11481
[scalarargsort.*random_ vs. simdargsort.*random_]1k/uint64_t                  +0.7929         +0.7929         13720         24598         13720         24597
[scalarargsort.*random_ vs. simdargsort.*random_]5k/uint64_t                  -0.4799         -0.4799        282869        147117        282846        147105
[scalarargsort.*random_ vs. simdargsort.*random_]100k/uint64_t                -0.5415         -0.5415       8484708       3890152       8484148       3889736
[scalarargsort.*random_ vs. simdargsort.*random_]1m/uint64_t                  -0.4600         -0.4601     114569475      61862446     114556094      61851167
[scalarargsort.*random_ vs. simdargsort.*random_]10m/uint64_t                 -0.3001         -0.3002    2053241244    1436979877    2053014588    1436779082
[scalarargsort.*random_ vs. simdargsort.*random_]128/double                   +0.6567         +0.6567           846          1402           846          1402
[scalarargsort.*random_ vs. simdargsort.*random_]256/double                   +0.7314         +0.7314          1893          3277          1892          3277
[scalarargsort.*random_ vs. simdargsort.*random_]512/double                   +1.0740         +1.0740          4092          8488          4092          8487
[scalarargsort.*random_ vs. simdargsort.*random_]1k/double                    -0.1487         -0.1487         23149         19707         23148         19707
[scalarargsort.*random_ vs. simdargsort.*random_]5k/double                    -0.6091         -0.6091        283673        110887        283655        110878
[scalarargsort.*random_ vs. simdargsort.*random_]100k/double                  -0.6174         -0.6174       8354939       3196334       8354229       3196128
[scalarargsort.*random_ vs. simdargsort.*random_]1m/double                    -0.5592         -0.5592     114068183      50284350     114053402      50276509
[scalarargsort.*random_ vs. simdargsort.*random_]10m/double                   -0.3127         -0.3126    2049582813    1408765808    2049324581    1408636738
[scalarargsort.*random_ vs. simdargsort.*random_]128/int32_t                  +0.7179         +0.7179           794          1364           794          1364
[scalarargsort.*random_ vs. simdargsort.*random_]256/int32_t                  +0.8265         +0.8266          1708          3120          1708          3120
[scalarargsort.*random_ vs. simdargsort.*random_]512/int32_t                  +1.2124         +1.2123          3726          8243          3726          8243
[scalarargsort.*random_ vs. simdargsort.*random_]1k/int32_t                   -0.2279         -0.2279         21168         16343         21167         16342
[scalarargsort.*random_ vs. simdargsort.*random_]5k/int32_t                   -0.6317         -0.6317        274010        100910        273990        100904
[scalarargsort.*random_ vs. simdargsort.*random_]100k/int32_t                 -0.6196         -0.6196       7931878       3017433       7931299       3017179
[scalarargsort.*random_ vs. simdargsort.*random_]1m/int32_t                   -0.5841         -0.5841     107409913      44675142     107401385      44668507
[scalarargsort.*random_ vs. simdargsort.*random_]10m/int32_t                  -0.3744         -0.3745    1836718161    1148961661    1836541830    1148846511
[scalarargsort.*random_ vs. simdargsort.*random_]128/uint32_t                 +0.8510         +0.8510           738          1367           738          1366
[scalarargsort.*random_ vs. simdargsort.*random_]256/uint32_t                 +0.9039         +0.9038          1638          3119          1638          3118
[scalarargsort.*random_ vs. simdargsort.*random_]512/uint32_t                 +1.2184         +1.2183          3694          8194          3694          8194
[scalarargsort.*random_ vs. simdargsort.*random_]1k/uint32_t                  -0.3355         -0.3355         24425         16231         24424         16231
[scalarargsort.*random_ vs. simdargsort.*random_]5k/uint32_t                  -0.6356         -0.6356        272408         99267        272394         99260
[scalarargsort.*random_ vs. simdargsort.*random_]100k/uint32_t                -0.6286         -0.6286       7951807       2953532       7951342       2953390
[scalarargsort.*random_ vs. simdargsort.*random_]1m/uint32_t                  -0.5901         -0.5901     107336303      43997337     107324792      43989818
[scalarargsort.*random_ vs. simdargsort.*random_]10m/uint32_t                 -0.3739         -0.3739    1831763385    1146822687    1831508128    1146654958
[scalarargsort.*random_ vs. simdargsort.*random_]128/float                    +0.9103         +0.9103           747          1427           747          1427
[scalarargsort.*random_ vs. simdargsort.*random_]256/float                    +1.0918         +1.0918          1599          3345          1599          3345
[scalarargsort.*random_ vs. simdargsort.*random_]512/float                    +1.7642         +1.7642          3372          9322          3372          9322
[scalarargsort.*random_ vs. simdargsort.*random_]1k/float                     -0.0662         -0.0662         21543         20118         21542         20117
[scalarargsort.*random_ vs. simdargsort.*random_]5k/float                     -0.6006         -0.6006        270926        108214        270909        108205
[scalarargsort.*random_ vs. simdargsort.*random_]100k/float                   -0.6086         -0.6086       7880947       3084313       7880386       3084130
[scalarargsort.*random_ vs. simdargsort.*random_]1m/float                     -0.5793         -0.5793     104376538      43907818     104367917      43903884
[scalarargsort.*random_ vs. simdargsort.*random_]10m/float                    -0.3640         -0.3640    1800961740    1145333523    1800764793    1145208302
OVERALL_GEOMEAN                                                               -0.0772         -0.0772             0             0             0             0

Benchmark                                                                               Time             CPU      Time Old      Time New       CPU Old       CPU New
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_128/int64_t                  +1.3918         +1.3917           653          1561           653          1561
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_256/int64_t                  +1.7809         +1.7808          1420          3949          1420          3949
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_512/int64_t                  +2.5843         +2.5843          3104         11125          3104         11124
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1k/int64_t                   +2.2490         +2.2490          7089         23031          7088         23029
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_5k/int64_t                   -0.5963         -0.5963        149855         60501        149847         60498
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_100k/int64_t                 -0.7715         -0.7715       3753502        857590       3753191        857554
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1m/int64_t                   -0.7035         -0.7035      48425688      14357676      48422468      14356105
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_10m/int64_t                  -0.6725         -0.6726     947529173     310275725     947403886     310225775
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_128/uint64_t                 +1.7617         +1.7617           671          1853           671          1853
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_256/uint64_t                 +1.9803         +1.9803          1473          4390          1473          4390
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_512/uint64_t                 +2.6901         +2.6900          3130         11549          3130         11548
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1k/uint64_t                  +2.3899         +2.3897          7181         24341          7180         24339
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_5k/uint64_t                  -0.5657         -0.5657        149410         64883        149401         64882
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_100k/uint64_t                -0.7567         -0.7567       3741835        910257       3741600        910240
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1m/uint64_t                  -0.7050         -0.7050      48141231      14204042      48137278      14202672
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_10m/uint64_t                 -0.6656         -0.6656     946433261     316470749     946295547     316410250
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_128/double                   +0.6683         +0.6683           832          1388           832          1388
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_256/double                   +0.7471         +0.7470          1873          3273          1873          3273
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_512/double                   +1.1045         +1.1045          4028          8476          4027          8476
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1k/double                    -0.1526         -0.1525         23252         19704         23251         19704
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_5k/double                    -0.6073         -0.6073        283470        111326        283466        111319
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_100k/double                  -0.6163         -0.6163       8326114       3194983       8325900       3194762
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1m/double                    -0.5595         -0.5595     114009657      50225387     113990117      50217236
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_10m/double                   -0.3102         -0.3102    2057833295    1419522163    2057528396    1419345363
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_128/int32_t                  +1.0741         +1.0742           656          1360           655          1360
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_256/int32_t                  +1.2354         +1.2355          1395          3119          1395          3119
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_512/int32_t                  +1.8226         +1.8227          2982          8418          2982          8418
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1k/int32_t                   +1.0254         +1.0256          8813         17850          8812         17850
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_5k/int32_t                   -0.6286         -0.6286        131963         49006        131953         49005
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_100k/int32_t                 -0.7699         -0.7699       3232776        743711       3232475        743701
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1m/int32_t                   -0.7470         -0.7470      39110830       9894646      39106243       9893241
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_10m/int32_t                  -0.7022         -0.7023     752520695     224088101     752375982     223963162
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_128/uint32_t                 +1.0364         +1.0365           668          1361           668          1361
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_256/uint32_t                 +1.1153         +1.1153          1476          3121          1475          3121
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_512/uint32_t                 +1.5222         +1.5222          3315          8361          3315          8361
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1k/uint32_t                  +1.0883         +1.0883          8479         17707          8479         17706
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_5k/uint32_t                  -0.6606         -0.6606        141834         48138        141829         48136
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_100k/uint32_t                -0.7961         -0.7961       3580397        730082       3580179        730028
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1m/uint32_t                  -0.7755         -0.7755      43469793       9758736      43465089       9757182
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_10m/uint32_t                 -0.7206         -0.7206     794028714     221868757     793926063     221859561
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_128/float                    +0.9151         +0.9150           743          1424           743          1424
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_256/float                    +1.0811         +1.0810          1605          3340          1605          3340
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_512/float                    +1.7802         +1.7801          3349          9311          3349          9311
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1k/float                     -0.0714         -0.0714         21620         20076         21619         20075
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_5k/float                     -0.6033         -0.6033        271797        107833        271783        107827
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_100k/float                   -0.6108         -0.6108       7880356       3067133       7879824       3066886
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_1m/float                     -0.5795         -0.5796     104396314      43894295     104385184      43887214
[scalarargsort.*smallrange vs. simdargsort.*smallrange]_10m/float                    -0.3627         -0.3627    1807677403    1151955798    1807465937    1151863691
OVERALL_GEOMEAN                                                                      -0.1297         -0.1298             0             0             0             0