Apply Regex starting loop optimization to non-atomic loops as well#35936
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stephentoub merged 2 commits intodotnet:masterfrom May 9, 2020
Merged
Apply Regex starting loop optimization to non-atomic loops as well#35936stephentoub merged 2 commits intodotnet:masterfrom
stephentoub merged 2 commits intodotnet:masterfrom
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stephentoub
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area-System.Text.RegularExpressions
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Tagging subscribers to this area: @eerhardt |
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I missed this PR somehow. I'll go over the logic and comment/approve tomorrow |
The node.N > 0 restriction isn't necessary, and prevents this optimization from being used with * loops. Worst case, the loop doesn't match anything, and we pay to overwrite the starting position with itself. Best case, we eliminate a ton of cost.
This was referenced May 8, 2020
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eerhardt
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I can't think of a reason why this would break. If you are convinced it is correct, I think that's good enough for me. 😉
src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexNode.cs
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Alright, this looks good to me. I spent some time going over the parsing logic , ran some patterns locally and am reasonably convinced that this is a safe change.
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@danmosemsft, @eerhardt, @pgovind, this appears sound, but it'd be great if you could double-check me on it.