[clang] [clang][dataflow] Add support for serialization and deserialization. (PR #152487)

[Yitzhak Mandelbaum via cfe-commits]

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@@ -140,6 +140,15 @@ class DataflowAnalysisContext {
   /// Adds `Constraint` to the flow condition identified by `Token`.
   void addFlowConditionConstraint(Atom Token, const Formula &Constraint);
 
+  /// Adds `Deps` to the dependencies of the flow condition identified by
+  /// `Token`. Intended for use in deserializing contexts. The formula alone
+  /// doesn't have enough information to indicate its deps.
+  void addFlowConditionDeps(Atom Token, const llvm::DenseSet<Atom> &Deps) {
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ymand wrote:

I've significantly restructured the PR per this conversation. I added some basic tests. PTAL and if the new API is good I can add more/expand. However, any suggestions for testing the import functions are welcome -- any tests, short of checking for round-tripping, will be more far more complicated than the code itself, given that the tests can't interrogate internal state.

https://github.com/llvm/llvm-project/pull/152487