[clang] [LifetimeSafety] Run analysis in post-order of CallGraph for better annotation propagation (PR #174178)

[Utkarsh Saxena via cfe-commits]

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@@ -2969,6 +3009,46 @@ void clang::sema::AnalysisBasedWarnings::IssueWarnings(
     CallableVisitor(CallAnalyzers, TU->getOwningModule())
         .TraverseTranslationUnitDecl(TU);
   }
+
+  if (S.getLangOpts().EnableLifetimeSafety && S.getLangOpts().CPlusPlus &&
+      S.getLangOpts().EnableLifetimeSafetyInferencePostOrder) {
+    llvm::SmallVector<const FunctionDecl *, 64> AllFunctions;
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usx95 wrote:

I would suggest to move the body of the `if` to a separate function. Also add a TimeTraceScope for that function. That would help in estimating the cost of doing this. I am primarily concerned about the CFG rebuilding and CallGraph building although I am positive that would be smallish and acceptable regression.

https://github.com/llvm/llvm-project/pull/174178