tree 38f7503e6e289a201aeeafce99492b8d5111b13b
parent 9bffb10e8b77b00033f2e997731193f81676cd60
author lbonn <github@lbonnans.net> 1764321201 +0100
committer GitHub <noreply@github.com> 1764321201 +0100
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[libcxx] Unwrap iterators in __find_segment (#161274)

The segmented iterator optimized implementation of find now unwraps
iterators when processing each segments.

As a result, it is able to take better advantage to some find
specializations: calling memchr/wmemchr for vector<vector<{char,int}>>

```
Benchmark                                                         Baseline    Candidate    Difference    % Difference
--------------------------------------------------------------  ----------  -----------  ------------  --------------
rng::find(join_view(deque<deque<int>>))_(process_all)/1024           71.13        61.19         -9.94          -13.97
rng::find(join_view(deque<deque<int>>))_(process_all)/32768        2359.19      2237.02       -122.17           -5.18
rng::find(join_view(deque<deque<int>>))_(process_all)/50             16.88        17.59          0.71            4.20
rng::find(join_view(deque<deque<int>>))_(process_all)/8              15.59        16.10          0.51            3.27
rng::find(join_view(deque<deque<int>>))_(process_all)/8192          647.01       532.75       -114.26          -17.66
rng::find(join_view(list<vector<int>>))_(process_all)/1024          689.76       680.74         -9.02           -1.31
rng::find(join_view(list<vector<int>>))_(process_all)/32768       22284.95     21500.26       -784.69           -3.52
rng::find(join_view(list<vector<int>>))_(process_all)/50             32.77        32.12         -0.65           -1.98
rng::find(join_view(list<vector<int>>))_(process_all)/8               6.11         5.92         -0.19           -3.11
rng::find(join_view(list<vector<int>>))_(process_all)/8192         5527.88      5373.43       -154.45           -2.79
rng::find(join_view(vector<list<int>>))_(process_all)/1024         1305.59      1264.04        -41.55           -3.18
rng::find(join_view(vector<list<int>>))_(process_all)/32768       42840.88     43322.64        481.76            1.12
rng::find(join_view(vector<list<int>>))_(process_all)/50             57.52        62.35          4.82            8.38
rng::find(join_view(vector<list<int>>))_(process_all)/8               6.06         5.98         -0.07           -1.18
rng::find(join_view(vector<list<int>>))_(process_all)/8192        20700.53     21431.66        731.12            3.53
rng::find(join_view(vector<vector<char>>))_(process_all)/1024       310.64        18.34       -292.30          -94.09
rng::find(join_view(vector<vector<char>>))_(process_all)/32768     9424.96       531.99      -8892.97          -94.36
rng::find(join_view(vector<vector<char>>))_(process_all)/50          18.58         3.25        -15.32          -82.49
rng::find(join_view(vector<vector<char>>))_(process_all)/8            4.81         2.98         -1.84          -38.13
rng::find(join_view(vector<vector<char>>))_(process_all)/8192      2437.50       126.88      -2310.62          -94.79
rng::find(join_view(vector<vector<int>>))_(process_all)/1024        297.10        41.70       -255.39          -85.96
rng::find(join_view(vector<vector<int>>))_(process_all)/32768      9662.42      1822.05      -7840.36          -81.14
rng::find(join_view(vector<vector<int>>))_(process_all)/50           22.29         5.10        -17.19          -77.11
rng::find(join_view(vector<vector<int>>))_(process_all)/8             3.73         3.13         -0.60          -16.05
rng::find(join_view(vector<vector<int>>))_(process_all)/8192       2399.68       356.10      -2043.58          -85.16
```