[jdk19] RFR: 8289486: Improve XSLT XPath operators count efficiency

[Joe Wang]

On Fri, 1 Jul 2022 17:04:10 GMT, Joe Wang <joehw at openjdk.org> wrote:

> To improve efficiency, this patch moves the limit check to within the Lexer and reports any overlimit situation as soon as it happens.
> 
> Note the change in XPathParser: diff (and also webrevs) showed the whole error-report block was changed, the actual change was only placing the block to within the isOverLimit statement.
> 
> Test: java.xml tests passed.

Hi Naoto, 

Thanks for reviewing.

For counting, it's mainly the way the totalOpCount was accumulated (e.g. previously it was totalOpCount += opCount and now totalOpCount++). But since the limit on total ops is usually significantly larger than that of the count for one expression, this change won't have effect on how it was reported, that is, it won't be report before individual limit is reached. In that regard, the reporting sequence hasn't changed (that is, group -> individual count -> total). 

The other factor is that this feature is fairly new, the change therefore will unlikely affect any real-world applications.

The test cases, reporting group/individual/total errors in the order, continued passing, that's a good indicator as well.

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PR: https://git.openjdk.org/jdk19/pull/101