introduce a new CallGraphSCC class, and pass it around

to CallGraphSCCPass's instead of passing around a
std::vector<CallGraphNode*>.  No functionality change,
but now we have a much tidier interface.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101558 91177308-0d34-0410-b5e6-96231b3b80d8

10 files changed, 132 insertions, 86 deletions

diff --git a/include/llvm/CallGraphSCCPass.h b/include/llvm/CallGraphSCCPass.h
index 37a454e..3cff8f2 100644
--- a/include/llvm/CallGraphSCCPass.h
+++ b/include/llvm/CallGraphSCCPass.h
@@ -29,9 +29,10 @@ namespace llvm {
 class CallGraphNode;
 class CallGraph;
 class PMStack;
-
-struct CallGraphSCCPass : public Pass {
-
+class CallGraphSCC;
+  
+class CallGraphSCCPass : public Pass {
+public:
   explicit CallGraphSCCPass(intptr_t pid) : Pass(PT_CallGraphSCC, pid) {}
   explicit CallGraphSCCPass(void *pid) : Pass(PT_CallGraphSCC, pid) {}
 
@@ -53,7 +54,7 @@ struct CallGraphSCCPass : public Pass {
   /// SCC passes that add or delete functions to the SCC are required to update
   /// the SCC list, otherwise stale pointers may be dereferenced.
   ///
-  virtual bool runOnSCC(std::vector<CallGraphNode *> &SCC) = 0;
+  virtual bool runOnSCC(CallGraphSCC &SCC) = 0;
 
   /// doFinalization - This method is called after the SCC's of the program has
   /// been processed, allowing the pass to do final cleanup as necessary.
@@ -63,7 +64,7 @@ struct CallGraphSCCPass : public Pass {
 
   /// Assign pass manager to manager this pass
   virtual void assignPassManager(PMStack &PMS,
-                                 PassManagerType PMT = PMT_CallGraphPassManager);
+                                 PassManagerType PMT =PMT_CallGraphPassManager);
 
   ///  Return what kind of Pass Manager can manage this pass.
   virtual PassManagerType getPotentialPassManagerType() const {
@@ -76,6 +77,37 @@ struct CallGraphSCCPass : public Pass {
   virtual void getAnalysisUsage(AnalysisUsage &Info) const;
 };
 
+/// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on. 
+class CallGraphSCC {
+  void *Context; // The CGPassManager object that is vending this.
+  std::vector<CallGraphNode*> Nodes;
+public:
+  CallGraphSCC(void *context) : Context(context) {}
+  
+  void initialize(CallGraphNode*const*I, CallGraphNode*const*E) {
+    Nodes.assign(I, E);
+  }
+  
+  bool isSingular() const { return Nodes.size() == 1; }
+  unsigned size() const { return Nodes.size(); }
+  
+  /// ReplaceNode - This informs the SCC and the pass manager that the specified
+  /// Old node has been deleted, and New is to be used in its place.
+  void ReplaceNode(CallGraphNode *Old, CallGraphNode *New) {
+    assert(Old != New && "Should not replace node with self");
+    for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
+      if (Nodes[i] == Old) {
+        Nodes[i] = New;
+        return;
+      }
+    assert(0 && "Node not in SCC");
+  }
+  
+  typedef std::vector<CallGraphNode*>::const_iterator iterator;
+  iterator begin() const { return Nodes.begin(); }
+  iterator end() const { return Nodes.end(); }
+};
+
 } // End llvm namespace
 
 #endif
diff --git a/include/llvm/Transforms/IPO/InlinerPass.h b/include/llvm/Transforms/IPO/InlinerPass.h
index c5be59a..6af7ed7 100644
--- a/include/llvm/Transforms/IPO/InlinerPass.h
+++ b/include/llvm/Transforms/IPO/InlinerPass.h
@@ -40,7 +40,7 @@ struct Inliner : public CallGraphSCCPass {
 
   // Main run interface method, this implements the interface required by the
   // Pass class.
-  virtual bool runOnSCC(std::vector<CallGraphNode *> &SCC);
+  virtual bool runOnSCC(CallGraphSCC &SCC);
 
   // doFinalization - Remove now-dead linkonce functions at the end of
   // processing to avoid breaking the SCC traversal.
@@ -77,7 +77,7 @@ struct Inliner : public CallGraphSCCPass {
 
   /// growCachedCostInfo - update the cached cost info for Caller after Callee
   /// has been inlined.
-  virtual void growCachedCostInfo(Function* Caller, Function* Callee) = 0;
+  virtual void growCachedCostInfo(Function *Caller, Function *Callee) = 0;
 
   /// removeDeadFunctions - Remove dead functions that are not included in
   /// DNR (Do Not Remove) list.
diff --git a/lib/Analysis/IPA/CallGraphSCCPass.cpp b/lib/Analysis/IPA/CallGraphSCCPass.cpp
index 8a2c03a..774f0d4 100644
--- a/lib/Analysis/IPA/CallGraphSCCPass.cpp
+++ b/lib/Analysis/IPA/CallGraphSCCPass.cpp
@@ -81,9 +81,9 @@ public:
   }
   
 private:
-  bool RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
+  bool RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC,
                     CallGraph &CG, bool &CallGraphUpToDate);
-  void RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC, CallGraph &CG,
+  void RefreshCallGraph(CallGraphSCC &CurSCC, CallGraph &CG,
                         bool IsCheckingMode);
 };
 
@@ -92,7 +92,7 @@ private:
 char CGPassManager::ID = 0;
 
 
-bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
+bool CGPassManager::RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC,
                                  CallGraph &CG, bool &CallGraphUpToDate) {
   bool Changed = false;
   PMDataManager *PM = P->getAsPMDataManager();
@@ -125,8 +125,9 @@ bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
   FPPassManager *FPP = (FPPassManager*)P;
   
   // Run pass P on all functions in the current SCC.
-  for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
-    if (Function *F = CurSCC[i]->getFunction()) {
+  for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
+       I != E; ++I) {
+    if (Function *F = (*I)->getFunction()) {
       dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
       TimeRegion PassTimer(getPassTimer(FPP));
       Changed |= FPP->runOnFunction(*F);
@@ -149,21 +150,24 @@ bool CGPassManager::RunPassOnSCC(Pass *P, std::vector<CallGraphNode*> &CurSCC,
 /// FunctionPasses have potentially munged the callgraph, and can be used after
 /// CallGraphSCC passes to verify that they correctly updated the callgraph.
 ///
-void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
+void CGPassManager::RefreshCallGraph(CallGraphSCC &CurSCC,
                                      CallGraph &CG, bool CheckingMode) {
   DenseMap<Value*, CallGraphNode*> CallSites;
   
   DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
                << " nodes:\n";
-        for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
-          CurSCC[i]->dump();
+        for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
+             I != E; ++I)
+          (*I)->dump();
         );
 
   bool MadeChange = false;
   
   // Scan all functions in the SCC.
-  for (unsigned sccidx = 0, e = CurSCC.size(); sccidx != e; ++sccidx) {
-    CallGraphNode *CGN = CurSCC[sccidx];
+  unsigned FunctionNo = 0;
+  for (CallGraphSCC::iterator SCCIdx = CurSCC.begin(), E = CurSCC.end();
+       SCCIdx != E; ++SCCIdx, ++FunctionNo) {
+    CallGraphNode *CGN = *SCCIdx;
     Function *F = CGN->getFunction();
     if (F == 0 || F->isDeclaration()) continue;
     
@@ -282,14 +286,15 @@ void CGPassManager::RefreshCallGraph(std::vector<CallGraphNode*> &CurSCC,
     
     // Periodically do an explicit clear to remove tombstones when processing
     // large scc's.
-    if ((sccidx & 15) == 0)
+    if ((FunctionNo & 15) == 15)
       CallSites.clear();
   }
 
   DEBUG(if (MadeChange) {
           dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
-          for (unsigned i = 0, e = CurSCC.size(); i != e; ++i)
-            CurSCC[i]->dump();
+          for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
+            I != E; ++I)
+              (*I)->dump();
          } else {
            dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
          }
@@ -302,14 +307,15 @@ bool CGPassManager::runOnModule(Module &M) {
   CallGraph &CG = getAnalysis<CallGraph>();
   bool Changed = doInitialization(CG);
 
-  std::vector<CallGraphNode*> CurSCC;
+  CallGraphSCC CurSCC(this);
   
   // Walk the callgraph in bottom-up SCC order.
   for (scc_iterator<CallGraph*> CGI = scc_begin(&CG), E = scc_end(&CG);
        CGI != E;) {
     // Copy the current SCC and increment past it so that the pass can hack
     // on the SCC if it wants to without invalidating our iterator.
-    CurSCC = *CGI;
+    std::vector<CallGraphNode*> &NodeVec = *CGI;
+    CurSCC.initialize(&NodeVec[0], &NodeVec[0]+NodeVec.size());
     ++CGI;
     
     
@@ -333,9 +339,10 @@ bool CGPassManager::runOnModule(Module &M) {
         std::string Functions;
 #ifndef NDEBUG
         raw_string_ostream OS(Functions);
-        for (unsigned i = 0, e = CurSCC.size(); i != e; ++i) {
-          if (i) OS << ", ";
-          CurSCC[i]->print(OS);
+        for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
+             I != E; ++I) {
+          if (I != CurSCC.begin()) OS << ", ";
+          (*I)->print(OS);
         }
         OS.flush();
 #endif
@@ -398,6 +405,12 @@ bool CGPassManager::doFinalization(CallGraph &CG) {
 }
 
 //===----------------------------------------------------------------------===//
+// CallGraphSCC Implementation
+//===----------------------------------------------------------------------===//
+
+
+
+//===----------------------------------------------------------------------===//
 // CallGraphSCCPass Implementation
 //===----------------------------------------------------------------------===//
 
@@ -468,10 +481,10 @@ namespace {
       AU.setPreservesAll();
     }
     
-    bool runOnSCC(std::vector<CallGraphNode *> &SCC) {
+    bool runOnSCC(CallGraphSCC &SCC) {
       Out << Banner;
-      for (unsigned i = 0, e = SCC.size(); i != e; ++i)
-        SCC[i]->getFunction()->print(Out);
+      for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+        (*I)->getFunction()->print(Out);
       return false;
     }
   };
diff --git a/lib/Transforms/IPO/ArgumentPromotion.cpp b/lib/Transforms/IPO/ArgumentPromotion.cpp
index 40a87e8..8cca4c6 100644
--- a/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -64,7 +64,7 @@ namespace {
       CallGraphSCCPass::getAnalysisUsage(AU);
     }
 
-    virtual bool runOnSCC(std::vector<CallGraphNode *> &SCC);
+    virtual bool runOnSCC(CallGraphSCC &SCC);
     static char ID; // Pass identification, replacement for typeid
     explicit ArgPromotion(unsigned maxElements = 3)
       : CallGraphSCCPass(&ID), maxElements(maxElements) {}
@@ -91,17 +91,18 @@ Pass *llvm::createArgumentPromotionPass(unsigned maxElements) {
   return new ArgPromotion(maxElements);
 }
 
-bool ArgPromotion::runOnSCC(std::vector<CallGraphNode *> &SCC) {
+bool ArgPromotion::runOnSCC(CallGraphSCC &SCC) {
   bool Changed = false, LocalChange;
 
   do {  // Iterate until we stop promoting from this SCC.
     LocalChange = false;
     // Attempt to promote arguments from all functions in this SCC.
-    for (unsigned i = 0, e = SCC.size(); i != e; ++i)
-      if (CallGraphNode *CGN = PromoteArguments(SCC[i])) {
+    for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+      if (CallGraphNode *CGN = PromoteArguments(*I)) {
         LocalChange = true;
-        SCC[i] = CGN;
+        SCC.ReplaceNode(*I, CGN);
       }
+    }
     Changed |= LocalChange;               // Remember that we changed something.
   } while (LocalChange);
 
diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index 298d5cf..9bd7af6 100644
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -44,20 +44,20 @@ namespace {
     FunctionAttrs() : CallGraphSCCPass(&ID) {}
 
     // runOnSCC - Analyze the SCC, performing the transformation if possible.
-    bool runOnSCC(std::vector<CallGraphNode *> &SCC);
+    bool runOnSCC(CallGraphSCC &SCC);
 
     // AddReadAttrs - Deduce readonly/readnone attributes for the SCC.
-    bool AddReadAttrs(const std::vector<CallGraphNode *> &SCC);
+    bool AddReadAttrs(const CallGraphSCC &SCC);
 
     // AddNoCaptureAttrs - Deduce nocapture attributes for the SCC.
-    bool AddNoCaptureAttrs(const std::vector<CallGraphNode *> &SCC);
+    bool AddNoCaptureAttrs(const CallGraphSCC &SCC);
 
     // IsFunctionMallocLike - Does this function allocate new memory?
     bool IsFunctionMallocLike(Function *F,
                               SmallPtrSet<Function*, 8> &) const;
 
     // AddNoAliasAttrs - Deduce noalias attributes for the SCC.
-    bool AddNoAliasAttrs(const std::vector<CallGraphNode *> &SCC);
+    bool AddNoAliasAttrs(const CallGraphSCC &SCC);
 
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.setPreservesCFG();
@@ -123,19 +123,19 @@ bool FunctionAttrs::PointsToLocalMemory(Value *V) {
 }
 
 /// AddReadAttrs - Deduce readonly/readnone attributes for the SCC.
-bool FunctionAttrs::AddReadAttrs(const std::vector<CallGraphNode *> &SCC) {
+bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) {
   SmallPtrSet<Function*, 8> SCCNodes;
 
   // Fill SCCNodes with the elements of the SCC.  Used for quickly
   // looking up whether a given CallGraphNode is in this SCC.
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i)
-    SCCNodes.insert(SCC[i]->getFunction());
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+    SCCNodes.insert((*I)->getFunction());
 
   // Check if any of the functions in the SCC read or write memory.  If they
   // write memory then they can't be marked readnone or readonly.
   bool ReadsMemory = false;
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
-    Function *F = SCC[i]->getFunction();
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+    Function *F = (*I)->getFunction();
 
     if (F == 0)
       // External node - may write memory.  Just give up.
@@ -210,8 +210,8 @@ bool FunctionAttrs::AddReadAttrs(const std::vector<CallGraphNode *> &SCC) {
   // Success!  Functions in this SCC do not access memory, or only read memory.
   // Give them the appropriate attribute.
   bool MadeChange = false;
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
-    Function *F = SCC[i]->getFunction();
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+    Function *F = (*I)->getFunction();
 
     if (F->doesNotAccessMemory())
       // Already perfect!
@@ -239,13 +239,13 @@ bool FunctionAttrs::AddReadAttrs(const std::vector<CallGraphNode *> &SCC) {
 }
 
 /// AddNoCaptureAttrs - Deduce nocapture attributes for the SCC.
-bool FunctionAttrs::AddNoCaptureAttrs(const std::vector<CallGraphNode *> &SCC) {
+bool FunctionAttrs::AddNoCaptureAttrs(const CallGraphSCC &SCC) {
   bool Changed = false;
 
   // Check each function in turn, determining which pointer arguments are not
   // captured.
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
-    Function *F = SCC[i]->getFunction();
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+    Function *F = (*I)->getFunction();
 
     if (F == 0)
       // External node - skip it;
@@ -334,18 +334,18 @@ bool FunctionAttrs::IsFunctionMallocLike(Function *F,
 }
 
 /// AddNoAliasAttrs - Deduce noalias attributes for the SCC.
-bool FunctionAttrs::AddNoAliasAttrs(const std::vector<CallGraphNode *> &SCC) {
+bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) {
   SmallPtrSet<Function*, 8> SCCNodes;
 
   // Fill SCCNodes with the elements of the SCC.  Used for quickly
   // looking up whether a given CallGraphNode is in this SCC.
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i)
-    SCCNodes.insert(SCC[i]->getFunction());
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+    SCCNodes.insert((*I)->getFunction());
 
   // Check each function in turn, determining which functions return noalias
   // pointers.
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
-    Function *F = SCC[i]->getFunction();
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+    Function *F = (*I)->getFunction();
 
     if (F == 0)
       // External node - skip it;
@@ -370,8 +370,8 @@ bool FunctionAttrs::AddNoAliasAttrs(const std::vector<CallGraphNode *> &SCC) {
   }
 
   bool MadeChange = false;
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
-    Function *F = SCC[i]->getFunction();
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+    Function *F = (*I)->getFunction();
     if (F->doesNotAlias(0) || !F->getReturnType()->isPointerTy())
       continue;
 
@@ -383,7 +383,7 @@ bool FunctionAttrs::AddNoAliasAttrs(const std::vector<CallGraphNode *> &SCC) {
   return MadeChange;
 }
 
-bool FunctionAttrs::runOnSCC(std::vector<CallGraphNode *> &SCC) {
+bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
   bool Changed = AddReadAttrs(SCC);
   Changed |= AddNoCaptureAttrs(SCC);
   Changed |= AddNoAliasAttrs(SCC);
diff --git a/lib/Transforms/IPO/Inliner.cpp b/lib/Transforms/IPO/Inliner.cpp
index 03ec72c..0791854 100644
--- a/lib/Transforms/IPO/Inliner.cpp
+++ b/lib/Transforms/IPO/Inliner.cpp
@@ -292,14 +292,14 @@ bool Inliner::shouldInline(CallSite CS) {
   return true;
 }
 
-bool Inliner::runOnSCC(std::vector<CallGraphNode*> &SCC) {
+bool Inliner::runOnSCC(CallGraphSCC &SCC) {
   CallGraph &CG = getAnalysis<CallGraph>();
   const TargetData *TD = getAnalysisIfAvailable<TargetData>();
 
   SmallPtrSet<Function*, 8> SCCFunctions;
   DEBUG(dbgs() << "Inliner visiting SCC:");
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
-    Function *F = SCC[i]->getFunction();
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+    Function *F = (*I)->getFunction();
     if (F) SCCFunctions.insert(F);
     DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE"));
   }
@@ -309,8 +309,8 @@ bool Inliner::runOnSCC(std::vector<CallGraphNode*> &SCC) {
   // from inlining other functions.
   SmallVector<CallSite, 16> CallSites;
 
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
-    Function *F = SCC[i]->getFunction();
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+    Function *F = (*I)->getFunction();
     if (!F) continue;
     
     for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
@@ -417,7 +417,7 @@ bool Inliner::runOnSCC(std::vector<CallGraphNode*> &SCC) {
       // swap/pop_back for efficiency, but do not use it if doing so would
       // move a call site to a function in this SCC before the
       // 'FirstCallInSCC' barrier.
-      if (SCC.size() == 1) {
+      if (SCC.isSingular()) {
         std::swap(CallSites[CSi], CallSites.back());
         CallSites.pop_back();
       } else {
diff --git a/lib/Transforms/IPO/PruneEH.cpp b/lib/Transforms/IPO/PruneEH.cpp
index 161246b..de6099c 100644
--- a/lib/Transforms/IPO/PruneEH.cpp
+++ b/lib/Transforms/IPO/PruneEH.cpp
@@ -40,7 +40,7 @@ namespace {
     PruneEH() : CallGraphSCCPass(&ID) {}
 
     // runOnSCC - Analyze the SCC, performing the transformation if possible.
-    bool runOnSCC(std::vector<CallGraphNode *> &SCC);
+    bool runOnSCC(CallGraphSCC &SCC);
 
     bool SimplifyFunction(Function *F);
     void DeleteBasicBlock(BasicBlock *BB);
@@ -54,20 +54,20 @@ X("prune-eh", "Remove unused exception handling info");
 Pass *llvm::createPruneEHPass() { return new PruneEH(); }
 
 
-bool PruneEH::runOnSCC(std::vector<CallGraphNode *> &SCC) {
+bool PruneEH::runOnSCC(CallGraphSCC &SCC) {
   SmallPtrSet<CallGraphNode *, 8> SCCNodes;
   CallGraph &CG = getAnalysis<CallGraph>();
   bool MadeChange = false;
 
   // Fill SCCNodes with the elements of the SCC.  Used for quickly
   // looking up whether a given CallGraphNode is in this SCC.
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i)
-    SCCNodes.insert(SCC[i]);
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+    SCCNodes.insert(*I);
 
   // First pass, scan all of the functions in the SCC, simplifying them
   // according to what we know.
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i)
-    if (Function *F = SCC[i]->getFunction())
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+    if (Function *F = (*I)->getFunction())
       MadeChange |= SimplifyFunction(F);
 
   // Next, check to see if any callees might throw or if there are any external
@@ -78,9 +78,9 @@ bool PruneEH::runOnSCC(std::vector<CallGraphNode *> &SCC) {
   // obviously the SCC might throw.
   //
   bool SCCMightUnwind = false, SCCMightReturn = false;
-  for (unsigned i = 0, e = SCC.size();
-       (!SCCMightUnwind || !SCCMightReturn) && i != e; ++i) {
-    Function *F = SCC[i]->getFunction();
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); 
+       (!SCCMightUnwind || !SCCMightReturn) && I != E; ++I) {
+    Function *F = (*I)->getFunction();
     if (F == 0) {
       SCCMightUnwind = true;
       SCCMightReturn = true;
@@ -132,7 +132,7 @@ bool PruneEH::runOnSCC(std::vector<CallGraphNode *> &SCC) {
 
   // If the SCC doesn't unwind or doesn't throw, note this fact.
   if (!SCCMightUnwind || !SCCMightReturn)
-    for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
+    for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
       Attributes NewAttributes = Attribute::None;
 
       if (!SCCMightUnwind)
@@ -140,19 +140,20 @@ bool PruneEH::runOnSCC(std::vector<CallGraphNode *> &SCC) {
       if (!SCCMightReturn)
         NewAttributes |= Attribute::NoReturn;
 
-      const AttrListPtr &PAL = SCC[i]->getFunction()->getAttributes();
+      Function *F = (*I)->getFunction();
+      const AttrListPtr &PAL = F->getAttributes();
       const AttrListPtr &NPAL = PAL.addAttr(~0, NewAttributes);
       if (PAL != NPAL) {
         MadeChange = true;
-        SCC[i]->getFunction()->setAttributes(NPAL);
+        F->setAttributes(NPAL);
       }
     }
 
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
     // Convert any invoke instructions to non-throwing functions in this node
     // into call instructions with a branch.  This makes the exception blocks
     // dead.
-    if (Function *F = SCC[i]->getFunction())
+    if (Function *F = (*I)->getFunction())
       MadeChange |= SimplifyFunction(F);
   }
 
diff --git a/lib/Transforms/IPO/StructRetPromotion.cpp b/lib/Transforms/IPO/StructRetPromotion.cpp
index dda32d0..473e83c 100644
--- a/lib/Transforms/IPO/StructRetPromotion.cpp
+++ b/lib/Transforms/IPO/StructRetPromotion.cpp
@@ -48,7 +48,7 @@ namespace {
       CallGraphSCCPass::getAnalysisUsage(AU);
     }
 
-    virtual bool runOnSCC(std::vector<CallGraphNode *> &SCC);
+    virtual bool runOnSCC(CallGraphSCC &SCC);
     static char ID; // Pass identification, replacement for typeid
     SRETPromotion() : CallGraphSCCPass(&ID) {}
 
@@ -69,12 +69,12 @@ Pass *llvm::createStructRetPromotionPass() {
   return new SRETPromotion();
 }
 
-bool SRETPromotion::runOnSCC(std::vector<CallGraphNode *> &SCC) {
+bool SRETPromotion::runOnSCC(CallGraphSCC &SCC) {
   bool Changed = false;
 
-  for (unsigned i = 0, e = SCC.size(); i != e; ++i)
-    if (CallGraphNode *NewNode = PromoteReturn(SCC[i])) {
-      SCC[i] = NewNode;
+  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
+    if (CallGraphNode *NewNode = PromoteReturn(*I)) {
+      SCC.ReplaceNode(*I, NewNode);
       Changed = true;
     }
 
diff --git a/tools/opt/opt.cpp b/tools/opt/opt.cpp
index 311f671..ff19942 100644
--- a/tools/opt/opt.cpp
+++ b/tools/opt/opt.cpp
@@ -141,15 +141,14 @@ struct CallGraphSCCPassPrinter : public CallGraphSCCPass {
   CallGraphSCCPassPrinter(const PassInfo *PI) :
     CallGraphSCCPass(&ID), PassToPrint(PI) {}
 
-  virtual bool runOnSCC(std::vector<CallGraphNode *>&SCC) {
+  virtual bool runOnSCC(CallGraphSCC &SCC) {
     if (!Quiet) {
       outs() << "Printing analysis '" << PassToPrint->getPassName() << "':\n";
 
-      for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
-        Function *F = SCC[i]->getFunction();
-        if (F) {
+      for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+        Function *F = (*I)->getFunction();
+        if (F)
           getAnalysisID<Pass>(PassToPrint).print(outs(), F->getParent());
-        }
       }
     }
     // Get and print pass...
diff --git a/unittests/VMCore/PassManagerTest.cpp b/unittests/VMCore/PassManagerTest.cpp
index bc21298..4b38910 100644
--- a/unittests/VMCore/PassManagerTest.cpp
+++ b/unittests/VMCore/PassManagerTest.cpp
@@ -154,7 +154,7 @@ namespace llvm {
 
     struct CGPass : public PassTest<CallGraph, CallGraphSCCPass> {
     public:
-      virtual bool runOnSCC(std::vector<CallGraphNode*> &SCMM) {
+      virtual bool runOnSCC(CallGraphSCC &SCMM) {
         EXPECT_TRUE(getAnalysisIfAvailable<TargetData>());
         run();
         return false;