[llvm] [llvm][rtsan] Add transform pass for sanitize_realtime_unsafe (PR #109543)

[via llvm-commits]

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@@ -45,6 +46,26 @@ static void insertCallAtAllFunctionExitPoints(Function &Fn,
         insertCallBeforeInstruction(Fn, I, InsertFnName);
 }
 
+static PreservedAnalyses rtsanPreservedCFGAnalyses() {
+  PreservedAnalyses PA;
+  PA.preserveSet<CFGAnalyses>();
+  return PA;
+}
+
+static void insertNotifyBlockingCallAtFunctionEntryPoint(Function &F) {
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davidtrevelyan wrote:

Cool, sounds sensible - changed it to `Fn` throughout the file 

https://github.com/llvm/llvm-project/pull/109543