[clang] [clang][dataflow] Cache getModeledFields (PR #180878)

[Jan Voung via cfe-commits]

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@@ -329,6 +335,9 @@ class DataflowAnalysisContext {
   // Fields modeled by environments covered by this context.
   FieldSet ModeledFields;
 
+  // Cache of modeled fields for each type, covered by this context.
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jvoung wrote:

Updated comment.

https://github.com/llvm/llvm-project/pull/180878