[PATCH] D82771: [ASTMatcher] Fix a performance regression: memorize the child match.

[Sam McCall via Phabricator via cfe-commits]

sammccall added a comment.

(I can't quite follow the original reason for disabling memoization in the non-recursive case, so this seems reasonable but going to leave that to Manuel who knew the argument)



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Comment at: clang/lib/ASTMatchers/ASTMatchFinder.cpp:468
+    // Memoize result even doing a single-level match, it might be expensive.
+    Key.Type = MaxDepth == 1 ? MatchType::Child : MatchType::Descendants;
     MemoizationMap::iterator I = ResultCache.find(Key);
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This line looks a lot like a cache-poisoning bug, until realizing that MaxDepth is never actually used as an integer, it's a boolean - 1 means non-recursive and 0 means recursive. (Note that the recursive call passes MaxDepth, not MaxDepth-1).
I guess we should just fix the type, actually bounding the depth doesn't seem likely to be done anytime soon.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D82771/new/

https://reviews.llvm.org/D82771