Fix PR4834, a tricky case where the inliner would resolve an

indirect function pointer, inline it, then go to delete the body.
The problem is that the callgraph had other references to the function,
though the inliner had no way to know it, so we got a dangling pointer
and an invalid iterator out of the deal.

The fix to this is pretty simple: stop the inliner from deleting the
function by knowing that there are references to it.  Do this by making
CallGraphNodes contain a refcount.  This requires moving deletion of 
available_externally functions to the module-level cleanup sweep where
it belongs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80533 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 14 deletions

diff --git a/lib/Analysis/IPA/CallGraph.cpp b/lib/Analysis/IPA/CallGraph.cpp
index 152add9..9711013 100644
--- a/lib/Analysis/IPA/CallGraph.cpp
+++ b/lib/Analysis/IPA/CallGraph.cpp
@@ -53,7 +53,7 @@ public:
     CallsExternalNode = new CallGraphNode(0);
     Root = 0;
   
-    // Add every function to the call graph...
+    // Add every function to the call graph.
     for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
       addToCallGraph(I);
   
@@ -169,12 +169,12 @@ void CallGraph::initialize(Module &M) {
 }
 
 void CallGraph::destroy() {
-  if (!FunctionMap.empty()) {
-    for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
-        I != E; ++I)
-      delete I->second;
-    FunctionMap.clear();
-  }
+  if (FunctionMap.empty()) return;
+  
+  for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
+      I != E; ++I)
+    delete I->second;
+  FunctionMap.clear();
 }
 
 void CallGraph::print(raw_ostream &OS, Module*) const {
@@ -219,10 +219,11 @@ CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
 
 void CallGraphNode::print(raw_ostream &OS) const {
   if (Function *F = getFunction())
-    OS << "Call graph node for function: '" << F->getName()
-       << "'<<0x" << this << ">>\n";
+    OS << "Call graph node for function: '" << F->getName() << "'";
   else
-    OS << "Call graph node <<null function: 0x" << this << ">>:\n";
+    OS << "Call graph node <<null function>>";
+  
+  OS << "<<0x" << this << ">>  #uses=" << getNumReferences() << '\n';
 
   for (const_iterator I = begin(), E = end(); I != E; ++I)
     if (Function *FI = I->second->getFunction())
@@ -241,7 +242,9 @@ void CallGraphNode::removeCallEdgeFor(CallSite CS) {
   for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
     assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
     if (I->first == CS) {
-      CalledFunctions.erase(I);
+      I->second->DropRef();
+      *I = CalledFunctions.back();
+      CalledFunctions.pop_back();
       return;
     }
   }
@@ -254,6 +257,7 @@ void CallGraphNode::removeCallEdgeFor(CallSite CS) {
 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
   for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
     if (CalledFunctions[i].second == Callee) {
+      Callee->DropRef();
       CalledFunctions[i] = CalledFunctions.back();
       CalledFunctions.pop_back();
       --i; --e;
@@ -266,8 +270,10 @@ void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
   for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
     assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
     CallRecord &CR = *I;
-    if (CR.second == Callee && !CR.first.getInstruction()) {
-      CalledFunctions.erase(I);
+    if (CR.second == Callee && CR.first.getInstruction() == 0) {
+      Callee->DropRef();
+      *I = CalledFunctions.back();
+      CalledFunctions.pop_back();
       return;
     }
   }
@@ -285,8 +291,11 @@ void CallGraphNode::replaceCallSite(CallSite Old, CallSite New,
       
       // If the callee is changing, not just the callsite, then update it as
       // well.
-      if (NewCallee)
+      if (NewCallee) {
+        I->second->DropRef();
         I->second = NewCallee;
+        I->second->AddRef();
+      }
       return;
     }
   }