Improve performance of NoUnusedVariablesRule & NoUnusedParametersRule #8853
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anthony-c-martin
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| @@ -22,7 +22,6 @@ va | |||
| // unassigned variable | |||
| var foo | |||
| //@[04:07) [BCP028 (Error)] Identifier "foo" is declared multiple times. Remove or rename the duplicates. (CodeDescription: none) |foo| | |||
| //@[04:07) [no-unused-vars (Warning)] Variable "foo" is declared but never used. (CodeDescription: bicep core(https://aka.ms/bicep/linter/no-unused-vars)) |foo| | |||
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This change is because I removed the OfType<VariableAccessSyntax>() filter when looking for references. Technically foo is being used in this file, but incorrectly as a function foo().
| // TODO: Performance: Use a visitor to visit VariableAccesssyntax and collects the non-error symbols into a list. | ||
| // Then do a symbol visitor to go through all the symbols that exist and compare. | ||
| // Same issue for unused-params rule. | ||
| var invertedBindings = model.Binder.Bindings.ToLookup(kvp => kvp.Value, kvp => kvp.Key); |
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[nit]: Since all the NoUnused*Rules use the same binding inversion, would it make sense to just expose this as a property of the binder? It looks like a cheap thing to calculate, but it could be done once and cached as an ImmutableDictionary<Symbol, ImmutableArray<SyntaxBase>>.
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I think in the long run, we'll want a more robust replacement for SemanticModel.FindReferences(), but it'll have to be semanticmodel-driven rather than binder-driven (for example, this approach wouldn't work for namespaced functions, as the binder won't bind them to a FunctionSymbol).
If I have time, I'll give this a go. For now, I didn't want to encourage this pattern in other places by making it available through the IBinder interface.
Noticed when implementing #8844 -
NoUnusedVariablesRuleis consuming ~34% total CPU time when running benchmarks. This PR drops that down to ~2.5%.Microsoft Reviewers: Open in CodeFlow