Addresses Regex Perf Issue 32764 by Alois-xx · Pull Request #32899 · dotnet/corefx (original) (raw)

@ViktorHofer
Benchmark.NET was a little funny to get it to use the compiled dlls and not the ones from the framework sdk. Here are the patched Results:

                        Method | N |         Mean |        Error |       StdDev | Allocated |
------------------------------ |-- |-------------:|-------------:|-------------:|----------:|
                      Original | 1 | 438,212.4 ns | 4,647.930 ns | 4,347.676 ns |       0 B |
                 CaseSensitive | 1 | 227,563.0 ns | 5,142.693 ns | 5,281.167 ns |       0 B |
 CaseSensitiveCultureInvariant | 1 | 215,541.1 ns | 1,187.442 ns | 1,110.734 ns |       0 B |
          SimplifiedExpression | 1 |   1,525.5 ns |    11.969 ns |    11.195 ns |       0 B |
      Case_Sensitive_Substring | 1 |     691.5 ns |     4.897 ns |     4.581 ns |       0 B |

And here the baseline version where I did revert the changes of my commit to really measure the impact of only my change:

                        Method | N |           Mean |         Error |        StdDev | Allocated |
------------------------------ |-- |---------------:|--------------:|--------------:|----------:|
                      Original | 1 | 1,055,537.2 ns | 31,271.169 ns | 36,011.922 ns |       0 B |
                 CaseSensitive | 1 |   216,579.6 ns |  1,827.153 ns |  1,709.119 ns |       0 B |
 CaseSensitiveCultureInvariant | 1 |   217,116.7 ns |  2,212.376 ns |  1,961.213 ns |       0 B |
          SimplifiedExpression | 1 |     1,523.0 ns |     13.191 ns |     12.339 ns |       0 B |
      Case_Sensitive_Substring | 1 |       671.3 ns |      8.552 ns |      8.000 ns |       0 B |

Just in case you did not see here is the ETW chart:

Actually the Benchmark.NET numbers are even better. From the numbers it looks like the slow code gen path is only triggerd when RegexOptions.IgnoreCase is used. But anyway this is certainly a widely used option.