Check in LLVM r95781.
diff --git a/lib/Analysis/IPA/CallGraph.cpp b/lib/Analysis/IPA/CallGraph.cpp
new file mode 100644
index 0000000..8c43aa1
--- /dev/null
+++ b/lib/Analysis/IPA/CallGraph.cpp
@@ -0,0 +1,310 @@
+//===- CallGraph.cpp - Build a Module's call graph ------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the CallGraph class and provides the BasicCallGraph
+// default implementation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Module.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+namespace {
+
+//===----------------------------------------------------------------------===//
+// BasicCallGraph class definition
+//
+class BasicCallGraph : public ModulePass, public CallGraph {
+  // Root is root of the call graph, or the external node if a 'main' function
+  // couldn't be found.
+  //
+  CallGraphNode *Root;
+
+  // ExternalCallingNode - This node has edges to all external functions and
+  // those internal functions that have their address taken.
+  CallGraphNode *ExternalCallingNode;
+
+  // CallsExternalNode - This node has edges to it from all functions making
+  // indirect calls or calling an external function.
+  CallGraphNode *CallsExternalNode;
+
+public:
+  static char ID; // Class identification, replacement for typeinfo
+  BasicCallGraph() : ModulePass(&ID), Root(0), 
+    ExternalCallingNode(0), CallsExternalNode(0) {}
+
+  // runOnModule - Compute the call graph for the specified module.
+  virtual bool runOnModule(Module &M) {
+    CallGraph::initialize(M);
+    
+    ExternalCallingNode = getOrInsertFunction(0);
+    CallsExternalNode = new CallGraphNode(0);
+    Root = 0;
+  
+    // Add every function to the call graph.
+    for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
+      addToCallGraph(I);
+  
+    // If we didn't find a main function, use the external call graph node
+    if (Root == 0) Root = ExternalCallingNode;
+    
+    return false;
+  }
+
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+    AU.setPreservesAll();
+  }
+
+  virtual void print(raw_ostream &OS, const Module *) const {
+    OS << "CallGraph Root is: ";
+    if (Function *F = getRoot()->getFunction())
+      OS << F->getName() << "\n";
+    else {
+      OS << "<<null function: 0x" << getRoot() << ">>\n";
+    }
+    
+    CallGraph::print(OS, 0);
+  }
+
+  virtual void releaseMemory() {
+    destroy();
+  }
+  
+  /// getAdjustedAnalysisPointer - This method is used when a pass implements
+  /// an analysis interface through multiple inheritance.  If needed, it should
+  /// override this to adjust the this pointer as needed for the specified pass
+  /// info.
+  virtual void *getAdjustedAnalysisPointer(const PassInfo *PI) {
+    if (PI->isPassID(&CallGraph::ID))
+      return (CallGraph*)this;
+    return this;
+  }
+  
+  CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; }
+  CallGraphNode* getCallsExternalNode()   const { return CallsExternalNode; }
+
+  // getRoot - Return the root of the call graph, which is either main, or if
+  // main cannot be found, the external node.
+  //
+  CallGraphNode *getRoot()             { return Root; }
+  const CallGraphNode *getRoot() const { return Root; }
+
+private:
+  //===---------------------------------------------------------------------
+  // Implementation of CallGraph construction
+  //
+
+  // addToCallGraph - Add a function to the call graph, and link the node to all
+  // of the functions that it calls.
+  //
+  void addToCallGraph(Function *F) {
+    CallGraphNode *Node = getOrInsertFunction(F);
+
+    // If this function has external linkage, anything could call it.
+    if (!F->hasLocalLinkage()) {
+      ExternalCallingNode->addCalledFunction(CallSite(), Node);
+
+      // Found the entry point?
+      if (F->getName() == "main") {
+        if (Root)    // Found multiple external mains?  Don't pick one.
+          Root = ExternalCallingNode;
+        else
+          Root = Node;          // Found a main, keep track of it!
+      }
+    }
+
+    // Loop over all of the users of the function, looking for non-call uses.
+    for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I)
+      if ((!isa<CallInst>(I) && !isa<InvokeInst>(I))
+          || !CallSite(cast<Instruction>(I)).isCallee(I)) {
+        // Not a call, or being used as a parameter rather than as the callee.
+        ExternalCallingNode->addCalledFunction(CallSite(), Node);
+        break;
+      }
+
+    // If this function is not defined in this translation unit, it could call
+    // anything.
+    if (F->isDeclaration() && !F->isIntrinsic())
+      Node->addCalledFunction(CallSite(), CallsExternalNode);
+
+    // Look for calls by this function.
+    for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
+      for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
+           II != IE; ++II) {
+        CallSite CS = CallSite::get(II);
+        if (CS.getInstruction() && !isa<DbgInfoIntrinsic>(II)) {
+          const Function *Callee = CS.getCalledFunction();
+          if (Callee)
+            Node->addCalledFunction(CS, getOrInsertFunction(Callee));
+          else
+            Node->addCalledFunction(CS, CallsExternalNode);
+        }
+      }
+  }
+
+  //
+  // destroy - Release memory for the call graph
+  virtual void destroy() {
+    /// CallsExternalNode is not in the function map, delete it explicitly.
+    delete CallsExternalNode;
+    CallsExternalNode = 0;
+    CallGraph::destroy();
+  }
+};
+
+} //End anonymous namespace
+
+static RegisterAnalysisGroup<CallGraph> X("Call Graph");
+static RegisterPass<BasicCallGraph>
+Y("basiccg", "Basic CallGraph Construction", false, true);
+static RegisterAnalysisGroup<CallGraph, true> Z(Y);
+
+char CallGraph::ID = 0;
+char BasicCallGraph::ID = 0;
+
+void CallGraph::initialize(Module &M) {
+  Mod = &M;
+}
+
+void CallGraph::destroy() {
+  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 {
+  for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
+    I->second->print(OS);
+}
+void CallGraph::dump() const {
+  print(dbgs(), 0);
+}
+
+//===----------------------------------------------------------------------===//
+// Implementations of public modification methods
+//
+
+// removeFunctionFromModule - Unlink the function from this module, returning
+// it.  Because this removes the function from the module, the call graph node
+// is destroyed.  This is only valid if the function does not call any other
+// functions (ie, there are no edges in it's CGN).  The easiest way to do this
+// is to dropAllReferences before calling this.
+//
+Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
+  assert(CGN->empty() && "Cannot remove function from call "
+         "graph if it references other functions!");
+  Function *F = CGN->getFunction(); // Get the function for the call graph node
+  delete CGN;                       // Delete the call graph node for this func
+  FunctionMap.erase(F);             // Remove the call graph node from the map
+
+  Mod->getFunctionList().remove(F);
+  return F;
+}
+
+// getOrInsertFunction - This method is identical to calling operator[], but
+// it will insert a new CallGraphNode for the specified function if one does
+// not already exist.
+CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
+  CallGraphNode *&CGN = FunctionMap[F];
+  if (CGN) return CGN;
+  
+  assert((!F || F->getParent() == Mod) && "Function not in current module!");
+  return CGN = new CallGraphNode(const_cast<Function*>(F));
+}
+
+void CallGraphNode::print(raw_ostream &OS) const {
+  if (Function *F = getFunction())
+    OS << "Call graph node for function: '" << F->getName() << "'";
+  else
+    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())
+      OS << "  Calls function '" << FI->getName() <<"'\n";
+  else
+    OS << "  Calls external node\n";
+  OS << "\n";
+}
+
+void CallGraphNode::dump() const { print(dbgs()); }
+
+/// removeCallEdgeFor - This method removes the edge in the node for the
+/// specified call site.  Note that this method takes linear time, so it
+/// should be used sparingly.
+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.getInstruction()) {
+      I->second->DropRef();
+      *I = CalledFunctions.back();
+      CalledFunctions.pop_back();
+      return;
+    }
+  }
+}
+
+
+// removeAnyCallEdgeTo - This method removes any call edges from this node to
+// the specified callee function.  This takes more time to execute than
+// removeCallEdgeTo, so it should not be used unless necessary.
+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;
+    }
+}
+
+/// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
+/// from this node to the specified callee function.
+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 == 0) {
+      Callee->DropRef();
+      *I = CalledFunctions.back();
+      CalledFunctions.pop_back();
+      return;
+    }
+  }
+}
+
+/// replaceCallEdge - This method replaces the edge in the node for the
+/// specified call site with a new one.  Note that this method takes linear
+/// time, so it should be used sparingly.
+void CallGraphNode::replaceCallEdge(CallSite CS,
+                                    CallSite NewCS, CallGraphNode *NewNode){
+  for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
+    assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
+    if (I->first == CS.getInstruction()) {
+      I->second->DropRef();
+      I->first = NewCS.getInstruction();
+      I->second = NewNode;
+      NewNode->AddRef();
+      return;
+    }
+  }
+}
+
+// Enuse that users of CallGraph.h also link with this file
+DEFINING_FILE_FOR(CallGraph)