[MLInliner] Keep track of deleted functions (llvm#97348)

As opposed to using Node::isDead(), which is no longer accurate after

This is only used in diagnostics.

(cherry picked from commit ebdb6f4)

Author: aeubanks

llvm/include/llvm/Analysis/MLInlineAdvisor.h

@@ -82,6 +82,7 @@ class MLInlineAdvisor : public InlineAdvisor {
   int32_t CurrentIRSize = 0;
   llvm::SmallPtrSet<const LazyCallGraph::Node *, 1> NodesInLastSCC;
   DenseSet<const LazyCallGraph::Node *> AllNodes;
+  DenseSet<Function *> DeadFunctions;
   bool ForceStop = false;
 };
 

llvm/lib/Analysis/MLInlineAdvisor.cpp

@@ -254,11 +254,13 @@ void MLInlineAdvisor::onSuccessfulInlining(const MLInlineAdvice &Advice,
   int64_t NewCallerAndCalleeEdges =
       getCachedFPI(*Caller).DirectCallsToDefinedFunctions;
 
-  if (CalleeWasDeleted)
+  if (CalleeWasDeleted) {
     --NodeCount;
-  else
+    DeadFunctions.insert(Callee);
+  } else {
     NewCallerAndCalleeEdges +=
         getCachedFPI(*Callee).DirectCallsToDefinedFunctions;
+  }
   EdgeCount += (NewCallerAndCalleeEdges - Advice.CallerAndCalleeEdges);
   assert(CurrentIRSize >= 0 && EdgeCount >= 0 && NodeCount >= 0);
 }