[Issue 18114] [Reg 2.078] regex performance regression

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18114

--- Comment #8 from Jon Degenhardt <jrdemail2000-dlang at yahoo.com> ---
I re-ran the benchmark with the new DMD 2.079.0 release (OS X). Numbers below
are fastest of several runs, but were generally consistent:

| Regex                 | 2.077.1      | 2.078.0-beta1 | 2.079.0      |
|-----------------------+--------------+---------------+--------------|
| 'abc'                 |  3819.314 ms |  6202.892 ms  |  5077.937 ms |
| '(aa)+(cc)+g'         |  5457.678 ms |  8209.269 ms  |  6672.057 ms |
| '(aa|ax).+[gxb][cyw]' | 10121.181 ms | 12448.443 ms  | 11254.978 ms |

These results are a material improvement over 2.078.0-beta1, but still a fair
bit off 2.077.1, by 10-25% depending on the test.

Perhaps no longer a "performance regression", but there's still an opportunity
for improvement. Would it be more appropriate to leave this open as an
enhancement request?

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