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================ Comment at: clang-tidy/abseil/UpgradeDurationConversionsCheck.cpp:33-36 + anyOf(hasAncestor( + functionTemplateDecl(HasMatchingDependentDescendant)), + hasAncestor( + classTemplateDecl(HasMatchingDependentDescendant)))) ---------------- alexfh wrote: > The hasAncestor and hasDescendant matchers frequently have non-trivial > performance implications. Especially the latter, especially when called on a > large number of nodes with a large number of transitive children (this > obviously depends on the code being analyzed). I don't know how likely is > this to cause problems here (the matcher seems to only be used when the check > is about to issue a diagnostic), but it's always good to be aware of the > possible issues. > > Frequently there's a more efficient (and easier to understand) alternative. > For example, instead of trying to evaluate certain conditions while > traversing the code (which may require a large number of lookups into > relatively distant parts of the AST), it's sometimes more efficient to split > the analysis into two or more stages. During the AST traversal (i.e. when AST > matchers run) the check could collect some raw information about all > potentially problematic places in the code and then (for example, in > `onEndOfTranslationUnit`) analyze the collected information together in a > second stage. This works best if there's a way to arrange the data gathered > on the first pass such that the second pass can efficiently look up necessary > information. Thanks, gave it a try, what do you think of this? https://reviews.llvm.org/D53830 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
