tree 9a675aa6123cb7a49a9ad8c93d3c4d5c0c5007ec
parent cb319b3e67ef0802420c5095b7b67026ce392853
author Vitaly Goldshteyn <goldvitaly@google.com> 1718127699 -0700
committer Copybara-Service <copybara-worker@google.com> 1718127754 -0700

Disallow reentrance removal in `absl::erase_if`.

Predicates should generally have no side effects since we do not guarantee the order or quantity for the calls.

In this change we forbid one specific side effect: modification of the table we are iterating over.

As a positive effect we have performance improvements (less computations and less branches).

```
name                                          old cpu/op   new cpu/op   delta
BM_EraseIf/num_elements:10/num_erased:0       3.02ns ± 2%  2.79ns ± 3%   -7.44%  (p=0.000 n=35+37)
BM_EraseIf/num_elements:1000/num_erased:0     2.41ns ± 5%  2.05ns ± 4%  -14.88%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:10/num_erased:5       4.40ns ± 3%  4.22ns ± 3%   -4.19%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:1000/num_erased:500   9.16ns ± 4%  9.13ns ± 3%     ~     (p=0.307 n=37+37)
BM_EraseIf/num_elements:10/num_erased:10      5.77ns ± 3%  5.50ns ± 4%   -4.62%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:1000/num_erased:1000  7.84ns ± 3%  7.77ns ± 3%   -0.94%  (p=0.006 n=37+35)

name                                          old time/op          new time/op          delta
BM_EraseIf/num_elements:10/num_erased:0       3.02ns ± 2%          2.79ns ± 3%   -7.48%  (p=0.000 n=35+36)
BM_EraseIf/num_elements:1000/num_erased:0     2.41ns ± 5%          2.05ns ± 4%  -14.89%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:10/num_erased:5       4.42ns ± 3%          4.23ns ± 3%   -4.22%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:1000/num_erased:500   9.18ns ± 4%          9.15ns ± 3%     ~     (p=0.347 n=37+37)
BM_EraseIf/num_elements:10/num_erased:10      5.79ns ± 3%          5.52ns ± 4%   -4.61%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:1000/num_erased:1000  7.87ns ± 3%          7.79ns ± 3%   -0.95%  (p=0.007 n=37+35)

name                                          old INSTRUCTIONS/op  new INSTRUCTIONS/op  delta
BM_EraseIf/num_elements:10/num_erased:0         14.9 ± 0%            12.9 ± 0%  -13.46%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:1000/num_erased:0       12.7 ± 0%            10.3 ± 0%  -18.76%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:10/num_erased:5         30.9 ± 0%            28.9 ± 0%   -6.48%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:1000/num_erased:500     37.6 ± 0%            35.3 ± 0%   -6.33%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:10/num_erased:10        46.9 ± 0%            44.9 ± 0%   -4.27%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:1000/num_erased:1000    62.6 ± 0%            60.2 ± 0%   -3.80%  (p=0.000 n=37+36)

name                                          old CYCLES/op        new CYCLES/op        delta
BM_EraseIf/num_elements:10/num_erased:0         4.91 ± 1%            4.11 ± 1%  -16.35%  (p=0.000 n=36+35)
BM_EraseIf/num_elements:1000/num_erased:0       7.74 ± 2%            6.54 ± 2%  -15.54%  (p=0.000 n=37+37)
BM_EraseIf/num_elements:10/num_erased:5         9.18 ± 3%            8.45 ± 3%   -7.88%  (p=0.000 n=37+35)
BM_EraseIf/num_elements:1000/num_erased:500     29.5 ± 1%            29.3 ± 1%   -0.82%  (p=0.000 n=36+37)
BM_EraseIf/num_elements:10/num_erased:10        13.5 ± 1%            12.6 ± 0%   -7.06%  (p=0.000 n=33+34)
BM_EraseIf/num_elements:1000/num_erased:1000    25.1 ± 0%            24.9 ± 0%   -0.90%  (p=0.000 n=37+35)
```

PiperOrigin-RevId: 642318040
Change-Id: I78a4a5a9a5881db0818225f9c7c153c562009f66