Store integer registers in SavePoint #181
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Without saving the int registers, quantifications can't accurately
keep track of their loop count when backtracking, so some patterns
were incorrectly matching.
For example, /(a|a){3}a/ incorrectly matched against `"aaaxyz"`,
because after failing to match the final `a` against the `"x"`, the
engine backtracked to the second alternation without resetting the
number of times the quantification had been satisfied.
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@swift-ci Please test Linux platform |
milseman
approved these changes
Feb 23, 2022
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LGTM.
Another area where this bug could surface is a nested reluctant quantification, where after a restore the old int register values would still be around.
Long term, I think we want to avoid having such heavy-weight save points, but that would require switching the engine off of generalized control flow.
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Without saving the int registers, quantifications can't accurately keep track of their loop count when backtracking, so some patterns were incorrectly matching.
For example,
/(a|a){3}a/incorrectly matched against"aaaxyz", because after failing to match the finalaagainst the"x", the engine backtracked to the second alternation without resetting the number of times the quantification had been satisfied.