lib/Transforms/Instrumentation/RSProfiling.cpp - chromiumos/third_party/llvm - Git at Google

 //===- RSProfiling.cpp - Various profiling using random sampling ----------===//
 //
 //                      The LLVM Compiler Infrastructure
 //
 // This file was developed by the LLVM research group and is distributed under
 // the University of Illinois Open Source License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // These passes implement a random sampling based profiling.  Different methods
 // of choosing when to sample are supported, as well as different types of
 // profiling.  This is done as two passes.  The first is a sequence of profiling
 // passes which insert profiling into the program, and remember what they
 // inserted.
 //
 // The second stage duplicates all instructions in a function, ignoring the
 // profiling code, then connects the two versions togeather at the entry and at
 // backedges.  At each connection point a choice is made as to whether to jump
 // to the profiled code (take a sample) or execute the unprofiled code.
 //
 // It is highly recommeneded that after this pass one runs mem2reg and adce
 // (instcombine load-vn gdce dse also are good to run afterwards)
 //
 // This design is intended to make the profiling passes independent of the RS
 // framework, but any profiling pass that implements the RSProfiling interface
 // is compatible with the rs framework (and thus can be sampled)
 //
 // TODO: obviously the block and function profiling are almost identical to the
 // existing ones, so they can be unified (esp since these passes are valid
 // without the rs framework).
 // TODO: Fix choice code so that frequency is not hard coded
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Pass.h"
 #include "llvm/Module.h"
 #include "llvm/Instructions.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Transforms/Instrumentation.h"
 #include "RSProfiling.h"
 #include <set>
 #include <map>
 #include <queue>
 #include <list>
 using namespace llvm;

 namespace {
   enum RandomMeth {
     GBV, GBVO, HOSTCC
   };

   cl::opt<RandomMeth> RandomMethod("profile-randomness",
       cl::desc("How to randomly choose to profile:"),
       cl::values(
                  clEnumValN(GBV, "global", "global counter"),
                  clEnumValN(GBVO, "ra_global",
                             "register allocated global counter"),
                  clEnumValN(HOSTCC, "rdcc", "cycle counter"),
                  clEnumValEnd));

   /// NullProfilerRS - The basic profiler that does nothing.  It is the default
   /// profiler and thus terminates RSProfiler chains.  It is useful for
   /// measuring framework overhead
   class VISIBILITY_HIDDEN NullProfilerRS : public RSProfilers {
   public:
     static char ID; // Pass identification, replacement for typeid
     bool isProfiling(Value* v) {
       return false;
     }
     bool runOnModule(Module &M) {
       return false;
     }
     void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.setPreservesAll();
     }
   };

   static RegisterAnalysisGroup<RSProfilers> A("Profiling passes");
   static RegisterPass<NullProfilerRS> NP("insert-null-profiling-rs",
                                          "Measure profiling framework overhead");
   static RegisterAnalysisGroup<RSProfilers, true> NPT(NP);

   /// Chooser - Something that chooses when to make a sample of the profiled code
   class VISIBILITY_HIDDEN Chooser {
   public:
     /// ProcessChoicePoint - is called for each basic block inserted to choose
     /// between normal and sample code
     virtual void ProcessChoicePoint(BasicBlock*) = 0;
     /// PrepFunction - is called once per function before other work is done.
     /// This gives the opertunity to insert new allocas and such.
     virtual void PrepFunction(Function*) = 0;
     virtual ~Chooser() {}
   };

   //Things that implement sampling policies
   //A global value that is read-mod-stored to choose when to sample.
   //A sample is taken when the global counter hits 0
   class VISIBILITY_HIDDEN GlobalRandomCounter : public Chooser {
     GlobalVariable* Counter;
     Value* ResetValue;
     const Type* T;
   public:
     GlobalRandomCounter(Module& M, const Type* t, uint64_t resetval);
     virtual ~GlobalRandomCounter();
     virtual void PrepFunction(Function* F);
     virtual void ProcessChoicePoint(BasicBlock* bb);
   };

   //Same is GRC, but allow register allocation of the global counter
   class VISIBILITY_HIDDEN GlobalRandomCounterOpt : public Chooser {
     GlobalVariable* Counter;
     Value* ResetValue;
     AllocaInst* AI;
     const Type* T;
   public:
     GlobalRandomCounterOpt(Module& M, const Type* t, uint64_t resetval);
     virtual ~GlobalRandomCounterOpt();
     virtual void PrepFunction(Function* F);
     virtual void ProcessChoicePoint(BasicBlock* bb);
   };

   //Use the cycle counter intrinsic as a source of pseudo randomness when
   //deciding when to sample.
   class VISIBILITY_HIDDEN CycleCounter : public Chooser {
     uint64_t rm;
     Constant *F;
   public:
     CycleCounter(Module& m, uint64_t resetmask);
     virtual ~CycleCounter();
     virtual void PrepFunction(Function* F);
     virtual void ProcessChoicePoint(BasicBlock* bb);
   };

   /// ProfilerRS - Insert the random sampling framework
   struct VISIBILITY_HIDDEN ProfilerRS : public FunctionPass {
     static char ID; // Pass identification, replacement for typeid
     ProfilerRS() : FunctionPass((intptr_t)&ID) {}

     std::map<Value*, Value*> TransCache;
     std::set<BasicBlock*> ChoicePoints;
     Chooser* c;

     //Translate and duplicate values for the new profile free version of stuff
     Value* Translate(Value* v);
     //Duplicate an entire function (with out profiling)
     void Duplicate(Function& F, RSProfilers& LI);
     //Called once for each backedge, handle the insertion of choice points and
     //the interconection of the two versions of the code
     void ProcessBackEdge(BasicBlock* src, BasicBlock* dst, Function& F);
     bool runOnFunction(Function& F);
     bool doInitialization(Module &M);
     virtual void getAnalysisUsage(AnalysisUsage &AU) const;
   };

   RegisterPass<ProfilerRS> X("insert-rs-profiling-framework",
                              "Insert random sampling instrumentation framework");
 }

 char RSProfilers::ID = 0;
 char NullProfilerRS::ID = 0;
 char ProfilerRS::ID = 0;

 //Local utilities
 static void ReplacePhiPred(BasicBlock* btarget,
                            BasicBlock* bold, BasicBlock* bnew);

 static void CollapsePhi(BasicBlock* btarget, BasicBlock* bsrc);

 template<class T>
 static void recBackEdge(BasicBlock* bb, T& BackEdges,
                         std::map<BasicBlock*, int>& color,
                         std::map<BasicBlock*, int>& depth,
                         std::map<BasicBlock*, int>& finish,
                         int& time);

 //find the back edges and where they go to
 template<class T>
 static void getBackEdges(Function& F, T& BackEdges);


 ///////////////////////////////////////
 // Methods of choosing when to profile
 ///////////////////////////////////////

 GlobalRandomCounter::GlobalRandomCounter(Module& M, const Type* t,
                                          uint64_t resetval) : T(t) {
   ConstantInt* Init = ConstantInt::get(T, resetval);
   ResetValue = Init;
   Counter = new GlobalVariable(T, false, GlobalValue::InternalLinkage,
                                Init, "RandomSteeringCounter", &M);
 }

 GlobalRandomCounter::~GlobalRandomCounter() {}

 void GlobalRandomCounter::PrepFunction(Function* F) {}

 void GlobalRandomCounter::ProcessChoicePoint(BasicBlock* bb) {
   BranchInst* t = cast<BranchInst>(bb->getTerminator());

   //decrement counter
   LoadInst* l = new LoadInst(Counter, "counter", t);

   ICmpInst* s = new ICmpInst(ICmpInst::ICMP_EQ, l, ConstantInt::get(T, 0),
                              "countercc", t);

   Value* nv = BinaryOperator::createSub(l, ConstantInt::get(T, 1),
                                         "counternew", t);
   new StoreInst(nv, Counter, t);
   t->setCondition(s);

   //reset counter
   BasicBlock* oldnext = t->getSuccessor(0);
   BasicBlock* resetblock = new BasicBlock("reset", oldnext->getParent(),
                                           oldnext);
   TerminatorInst* t2 = new BranchInst(oldnext, resetblock);
   t->setSuccessor(0, resetblock);
   new StoreInst(ResetValue, Counter, t2);
   ReplacePhiPred(oldnext, bb, resetblock);
 }

 GlobalRandomCounterOpt::GlobalRandomCounterOpt(Module& M, const Type* t,
                                                uint64_t resetval)
   : AI(0), T(t) {
   ConstantInt* Init = ConstantInt::get(T, resetval);
   ResetValue  = Init;
   Counter = new GlobalVariable(T, false, GlobalValue::InternalLinkage,
                                Init, "RandomSteeringCounter", &M);
 }

 GlobalRandomCounterOpt::~GlobalRandomCounterOpt() {}

 void GlobalRandomCounterOpt::PrepFunction(Function* F) {
   //make a local temporary to cache the global
   BasicBlock& bb = F->getEntryBlock();
   BasicBlock::iterator InsertPt = bb.begin();
   AI = new AllocaInst(T, 0, "localcounter", InsertPt);
   LoadInst* l = new LoadInst(Counter, "counterload", InsertPt);
   new StoreInst(l, AI, InsertPt);

   //modify all functions and return values to restore the local variable to/from
   //the global variable
   for(Function::iterator fib = F->begin(), fie = F->end();
       fib != fie; ++fib)
     for(BasicBlock::iterator bib = fib->begin(), bie = fib->end();
         bib != bie; ++bib)
       if (isa<CallInst>(bib)) {
         LoadInst* l = new LoadInst(AI, "counter", bib);
         new StoreInst(l, Counter, bib);
         l = new LoadInst(Counter, "counter", ++bib);
         new StoreInst(l, AI, bib--);
       } else if (isa<InvokeInst>(bib)) {
         LoadInst* l = new LoadInst(AI, "counter", bib);
         new StoreInst(l, Counter, bib);

         BasicBlock* bb = cast<InvokeInst>(bib)->getNormalDest();
         BasicBlock::iterator i = bb->begin();
         while (isa<PHINode>(i))
           ++i;
         l = new LoadInst(Counter, "counter", i);

         bb = cast<InvokeInst>(bib)->getUnwindDest();
         i = bb->begin();
         while (isa<PHINode>(i)) ++i;
         l = new LoadInst(Counter, "counter", i);
         new StoreInst(l, AI, i);
       } else if (isa<UnwindInst>(&*bib) || isa<ReturnInst>(&*bib)) {
         LoadInst* l = new LoadInst(AI, "counter", bib);
         new StoreInst(l, Counter, bib);
       }
 }

 void GlobalRandomCounterOpt::ProcessChoicePoint(BasicBlock* bb) {
   BranchInst* t = cast<BranchInst>(bb->getTerminator());

   //decrement counter
   LoadInst* l = new LoadInst(AI, "counter", t);

   ICmpInst* s = new ICmpInst(ICmpInst::ICMP_EQ, l, ConstantInt::get(T, 0),
                              "countercc", t);

   Value* nv = BinaryOperator::createSub(l, ConstantInt::get(T, 1),
                                         "counternew", t);
   new StoreInst(nv, AI, t);
   t->setCondition(s);

   //reset counter
   BasicBlock* oldnext = t->getSuccessor(0);
   BasicBlock* resetblock = new BasicBlock("reset", oldnext->getParent(),
                                           oldnext);
   TerminatorInst* t2 = new BranchInst(oldnext, resetblock);
   t->setSuccessor(0, resetblock);
   new StoreInst(ResetValue, AI, t2);
   ReplacePhiPred(oldnext, bb, resetblock);
 }


 CycleCounter::CycleCounter(Module& m, uint64_t resetmask) : rm(resetmask) {
   F = m.getOrInsertFunction("llvm.readcyclecounter", Type::Int64Ty, NULL);
 }

 CycleCounter::~CycleCounter() {}

 void CycleCounter::PrepFunction(Function* F) {}

 void CycleCounter::ProcessChoicePoint(BasicBlock* bb) {
   BranchInst* t = cast<BranchInst>(bb->getTerminator());

   CallInst* c = new CallInst(F, "rdcc", t);
   BinaryOperator* b =
     BinaryOperator::createAnd(c, ConstantInt::get(Type::Int64Ty, rm),
                               "mrdcc", t);

   ICmpInst *s = new ICmpInst(ICmpInst::ICMP_EQ, b,
                              ConstantInt::get(Type::Int64Ty, 0),
                              "mrdccc", t);

   t->setCondition(s);
 }

 ///////////////////////////////////////
 // Profiling:
 ///////////////////////////////////////
 bool RSProfilers_std::isProfiling(Value* v) {
   if (profcode.find(v) != profcode.end())
     return true;
   //else
   RSProfilers& LI = getAnalysis<RSProfilers>();
   return LI.isProfiling(v);
 }

 void RSProfilers_std::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
                                           GlobalValue *CounterArray) {
   // Insert the increment after any alloca or PHI instructions...
   BasicBlock::iterator InsertPos = BB->begin();
   while (isa<AllocaInst>(InsertPos) || isa<PHINode>(InsertPos))
     ++InsertPos;

   // Create the getelementptr constant expression
   std::vector<Constant*> Indices(2);
   Indices[0] = Constant::getNullValue(Type::Int32Ty);
   Indices[1] = ConstantInt::get(Type::Int32Ty, CounterNum);
   Constant *ElementPtr = ConstantExpr::getGetElementPtr(CounterArray,
                                                         &Indices[0], 2);

   // Load, increment and store the value back.
   Value *OldVal = new LoadInst(ElementPtr, "OldCounter", InsertPos);
   profcode.insert(OldVal);
   Value *NewVal = BinaryOperator::createAdd(OldVal,
                                             ConstantInt::get(Type::Int32Ty, 1),
                                             "NewCounter", InsertPos);
   profcode.insert(NewVal);
   profcode.insert(new StoreInst(NewVal, ElementPtr, InsertPos));
 }

 void RSProfilers_std::getAnalysisUsage(AnalysisUsage &AU) const {
   //grab any outstanding profiler, or get the null one
   AU.addRequired<RSProfilers>();
 }

 ///////////////////////////////////////
 // RS Framework
 ///////////////////////////////////////

 Value* ProfilerRS::Translate(Value* v) {
   if(TransCache[v])
     return TransCache[v];

   if (BasicBlock* bb = dyn_cast<BasicBlock>(v)) {
     if (bb == &bb->getParent()->getEntryBlock())
       TransCache[bb] = bb; //don't translate entry block
     else
       TransCache[bb] = new BasicBlock("dup_" + bb->getName(), bb->getParent(),
                                       NULL);
     return TransCache[bb];
   } else if (Instruction* i = dyn_cast<Instruction>(v)) {
     //we have already translated this
     //do not translate entry block allocas
     if(&i->getParent()->getParent()->getEntryBlock() == i->getParent()) {
       TransCache[i] = i;
       return i;
     } else {
       //translate this
       Instruction* i2 = i->clone();
       if (i->hasName())
         i2->setName("dup_" + i->getName());
       TransCache[i] = i2;
       //NumNewInst++;
       for (unsigned x = 0; x < i2->getNumOperands(); ++x)
         i2->setOperand(x, Translate(i2->getOperand(x)));
       return i2;
     }
   } else if (isa<Function>(v) || isa<Constant>(v) || isa<Argument>(v)) {
     TransCache[v] = v;
     return v;
   }
   assert(0 && "Value not handled");
   return 0;
 }

 void ProfilerRS::Duplicate(Function& F, RSProfilers& LI)
 {
   //perform a breadth first search, building up a duplicate of the code
   std::queue<BasicBlock*> worklist;
   std::set<BasicBlock*> seen;

   //This loop ensures proper BB order, to help performance
   for (Function::iterator fib = F.begin(), fie = F.end(); fib != fie; ++fib)
     worklist.push(fib);
   while (!worklist.empty()) {
     Translate(worklist.front());
     worklist.pop();
   }

   //remember than reg2mem created a new entry block we don't want to duplicate
   worklist.push(F.getEntryBlock().getTerminator()->getSuccessor(0));
   seen.insert(&F.getEntryBlock());

   while (!worklist.empty()) {
     BasicBlock* bb = worklist.front();
     worklist.pop();
     if(seen.find(bb) == seen.end()) {
       BasicBlock* bbtarget = cast<BasicBlock>(Translate(bb));
       BasicBlock::InstListType& instlist = bbtarget->getInstList();
       for (BasicBlock::iterator iib = bb->begin(), iie = bb->end();
            iib != iie; ++iib) {
         //NumOldInst++;
         if (!LI.isProfiling(&*iib)) {
           Instruction* i = cast<Instruction>(Translate(iib));
           instlist.insert(bbtarget->end(), i);
         }
       }
       //updated search state;
       seen.insert(bb);
       TerminatorInst* ti = bb->getTerminator();
       for (unsigned x = 0; x < ti->getNumSuccessors(); ++x) {
         BasicBlock* bbs = ti->getSuccessor(x);
         if (seen.find(bbs) == seen.end()) {
           worklist.push(bbs);
         }
       }
     }
   }
 }

 void ProfilerRS::ProcessBackEdge(BasicBlock* src, BasicBlock* dst, Function& F) {
   //given a backedge from B -> A, and translations A' and B',
   //a: insert C and C'
   //b: add branches in C to A and A' and in C' to A and A'
   //c: mod terminators@B, replace A with C
   //d: mod terminators@B', replace A' with C'
   //e: mod phis@A for pred B to be pred C
   //       if multiple entries, simplify to one
   //f: mod phis@A' for pred B' to be pred C'
   //       if multiple entries, simplify to one
   //g: for all phis@A with pred C using x
   //       add in edge from C' using x'
   //       add in edge from C using x in A'

   //a:
   Function::iterator BBN = src; ++BBN;
   BasicBlock* bbC = new BasicBlock("choice", &F, BBN);
   //ChoicePoints.insert(bbC);
   BBN = cast<BasicBlock>(Translate(src));
   BasicBlock* bbCp = new BasicBlock("choice", &F, ++BBN);
   ChoicePoints.insert(bbCp);

   //b:
   new BranchInst(cast<BasicBlock>(Translate(dst)), bbC);
   new BranchInst(dst, cast<BasicBlock>(Translate(dst)),
                  ConstantInt::get(Type::Int1Ty, true), bbCp);
   //c:
   {
     TerminatorInst* iB = src->getTerminator();
     for (unsigned x = 0; x < iB->getNumSuccessors(); ++x)
       if (iB->getSuccessor(x) == dst)
         iB->setSuccessor(x, bbC);
   }
   //d:
   {
     TerminatorInst* iBp = cast<TerminatorInst>(Translate(src->getTerminator()));
     for (unsigned x = 0; x < iBp->getNumSuccessors(); ++x)
       if (iBp->getSuccessor(x) == cast<BasicBlock>(Translate(dst)))
         iBp->setSuccessor(x, bbCp);
   }
   //e:
   ReplacePhiPred(dst, src, bbC);
   //src could be a switch, in which case we are replacing several edges with one
   //thus collapse those edges int the Phi
   CollapsePhi(dst, bbC);
   //f:
   ReplacePhiPred(cast<BasicBlock>(Translate(dst)),
                  cast<BasicBlock>(Translate(src)),bbCp);
   CollapsePhi(cast<BasicBlock>(Translate(dst)), bbCp);
   //g:
   for(BasicBlock::iterator ib = dst->begin(), ie = dst->end(); ib != ie;
       ++ib)
     if (PHINode* phi = dyn_cast<PHINode>(&*ib)) {
       for(unsigned x = 0; x < phi->getNumIncomingValues(); ++x)
         if(bbC == phi->getIncomingBlock(x)) {
           phi->addIncoming(Translate(phi->getIncomingValue(x)), bbCp);
           cast<PHINode>(Translate(phi))->addIncoming(phi->getIncomingValue(x),
                                                      bbC);
         }
       phi->removeIncomingValue(bbC);
     }
 }

 bool ProfilerRS::runOnFunction(Function& F) {
   if (!F.isDeclaration()) {
     std::set<std::pair<BasicBlock*, BasicBlock*> > BackEdges;
     RSProfilers& LI = getAnalysis<RSProfilers>();

     getBackEdges(F, BackEdges);
     Duplicate(F, LI);
     //assume that stuff worked.  now connect the duplicated basic blocks
     //with the originals in such a way as to preserve ssa.  yuk!
     for (std::set<std::pair<BasicBlock*, BasicBlock*> >::iterator
            ib = BackEdges.begin(), ie = BackEdges.end(); ib != ie; ++ib)
       ProcessBackEdge(ib->first, ib->second, F);

     //oh, and add the edge from the reg2mem created entry node to the
     //duplicated second node
     TerminatorInst* T = F.getEntryBlock().getTerminator();
     ReplaceInstWithInst(T, new BranchInst(T->getSuccessor(0),
                                           cast<BasicBlock>(
                                             Translate(T->getSuccessor(0))),
                                           ConstantInt::get(Type::Int1Ty, true)));

     //do whatever is needed now that the function is duplicated
     c->PrepFunction(&F);

     //add entry node to choice points
     ChoicePoints.insert(&F.getEntryBlock());

     for (std::set<BasicBlock*>::iterator
            ii = ChoicePoints.begin(), ie = ChoicePoints.end(); ii != ie; ++ii)
       c->ProcessChoicePoint(*ii);

     ChoicePoints.clear();
     TransCache.clear();

     return true;
   }
   return false;
 }

 bool ProfilerRS::doInitialization(Module &M) {
   switch (RandomMethod) {
   case GBV:
     c = new GlobalRandomCounter(M, Type::Int32Ty, (1 << 14) - 1);
     break;
   case GBVO:
     c = new GlobalRandomCounterOpt(M, Type::Int32Ty, (1 << 14) - 1);
     break;
   case HOSTCC:
     c = new CycleCounter(M, (1 << 14) - 1);
     break;
   };
   return true;
 }

 void ProfilerRS::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<RSProfilers>();
   AU.addRequiredID(DemoteRegisterToMemoryID);
 }

 ///////////////////////////////////////
 // Utilities:
 ///////////////////////////////////////
 static void ReplacePhiPred(BasicBlock* btarget,
                            BasicBlock* bold, BasicBlock* bnew) {
   for(BasicBlock::iterator ib = btarget->begin(), ie = btarget->end();
       ib != ie; ++ib)
     if (PHINode* phi = dyn_cast<PHINode>(&*ib)) {
       for(unsigned x = 0; x < phi->getNumIncomingValues(); ++x)
         if(bold == phi->getIncomingBlock(x))
           phi->setIncomingBlock(x, bnew);
     }
 }

 static void CollapsePhi(BasicBlock* btarget, BasicBlock* bsrc) {
   for(BasicBlock::iterator ib = btarget->begin(), ie = btarget->end();
       ib != ie; ++ib)
     if (PHINode* phi = dyn_cast<PHINode>(&*ib)) {
       std::map<BasicBlock*, Value*> counter;
       for(unsigned i = 0; i < phi->getNumIncomingValues(); ) {
         if (counter[phi->getIncomingBlock(i)]) {
           assert(phi->getIncomingValue(i) == counter[phi->getIncomingBlock(i)]);
           phi->removeIncomingValue(i, false);
         } else {
           counter[phi->getIncomingBlock(i)] = phi->getIncomingValue(i);
           ++i;
         }
       }
     }
 }

 template<class T>
 static void recBackEdge(BasicBlock* bb, T& BackEdges,
                         std::map<BasicBlock*, int>& color,
                         std::map<BasicBlock*, int>& depth,
                         std::map<BasicBlock*, int>& finish,
                         int& time)
 {
   color[bb] = 1;
   ++time;
   depth[bb] = time;
   TerminatorInst* t= bb->getTerminator();
   for(unsigned i = 0; i < t->getNumSuccessors(); ++i) {
     BasicBlock* bbnew = t->getSuccessor(i);
     if (color[bbnew] == 0)
       recBackEdge(bbnew, BackEdges, color, depth, finish, time);
     else if (color[bbnew] == 1) {
       BackEdges.insert(std::make_pair(bb, bbnew));
       //NumBackEdges++;
     }
   }
   color[bb] = 2;
   ++time;
   finish[bb] = time;
 }


 //find the back edges and where they go to
 template<class T>
 static void getBackEdges(Function& F, T& BackEdges) {
   std::map<BasicBlock*, int> color;
   std::map<BasicBlock*, int> depth;
   std::map<BasicBlock*, int> finish;
   int time = 0;
   recBackEdge(&F.getEntryBlock(), BackEdges, color, depth, finish, time);
   DOUT << F.getName() << " " << BackEdges.size() << "\n";
 }


 //Creation functions
 ModulePass* llvm::createNullProfilerRSPass() {
   return new NullProfilerRS();
 }

 FunctionPass* llvm::createRSProfilingPass() {
   return new ProfilerRS();
 }
	//===- RSProfiling.cpp - Various profiling using random sampling ----------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file was developed by the LLVM research group and is distributed under
	// the University of Illinois Open Source License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// These passes implement a random sampling based profiling. Different methods
	// of choosing when to sample are supported, as well as different types of
	// profiling. This is done as two passes. The first is a sequence of profiling
	// passes which insert profiling into the program, and remember what they
	// inserted.
	//
	// The second stage duplicates all instructions in a function, ignoring the
	// profiling code, then connects the two versions togeather at the entry and at
	// backedges. At each connection point a choice is made as to whether to jump
	// to the profiled code (take a sample) or execute the unprofiled code.
	//
	// It is highly recommeneded that after this pass one runs mem2reg and adce
	// (instcombine load-vn gdce dse also are good to run afterwards)
	//
	// This design is intended to make the profiling passes independent of the RS
	// framework, but any profiling pass that implements the RSProfiling interface
	// is compatible with the rs framework (and thus can be sampled)
	//
	// TODO: obviously the block and function profiling are almost identical to the
	// existing ones, so they can be unified (esp since these passes are valid
	// without the rs framework).
	// TODO: Fix choice code so that frequency is not hard coded
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Pass.h"
	#include "llvm/Module.h"
	#include "llvm/Instructions.h"
	#include "llvm/Constants.h"
	#include "llvm/DerivedTypes.h"
	#include "llvm/Transforms/Scalar.h"
	#include "llvm/Transforms/Utils/BasicBlockUtils.h"
	#include "llvm/Support/CommandLine.h"
	#include "llvm/Support/Compiler.h"
	#include "llvm/Support/Debug.h"
	#include "llvm/Transforms/Instrumentation.h"
	#include "RSProfiling.h"
	#include <set>
	#include <map>
	#include <queue>
	#include <list>
	using namespace llvm;

	namespace {
	enum RandomMeth {
	GBV, GBVO, HOSTCC
	};

	cl::opt<RandomMeth> RandomMethod("profile-randomness",
	cl::desc("How to randomly choose to profile:"),
	cl::values(
	clEnumValN(GBV, "global", "global counter"),
	clEnumValN(GBVO, "ra_global",
	"register allocated global counter"),
	clEnumValN(HOSTCC, "rdcc", "cycle counter"),
	clEnumValEnd));

	/// NullProfilerRS - The basic profiler that does nothing. It is the default
	/// profiler and thus terminates RSProfiler chains. It is useful for
	/// measuring framework overhead
	class VISIBILITY_HIDDEN NullProfilerRS : public RSProfilers {
	public:
	static char ID; // Pass identification, replacement for typeid
	bool isProfiling(Value* v) {
	return false;
	}
	bool runOnModule(Module &M) {
	return false;
	}
	void getAnalysisUsage(AnalysisUsage &AU) const {
	AU.setPreservesAll();
	}
	};

	static RegisterAnalysisGroup<RSProfilers> A("Profiling passes");
	static RegisterPass<NullProfilerRS> NP("insert-null-profiling-rs",
	"Measure profiling framework overhead");
	static RegisterAnalysisGroup<RSProfilers, true> NPT(NP);

	/// Chooser - Something that chooses when to make a sample of the profiled code
	class VISIBILITY_HIDDEN Chooser {
	public:
	/// ProcessChoicePoint - is called for each basic block inserted to choose
	/// between normal and sample code
	virtual void ProcessChoicePoint(BasicBlock*) = 0;
	/// PrepFunction - is called once per function before other work is done.
	/// This gives the opertunity to insert new allocas and such.
	virtual void PrepFunction(Function*) = 0;
	virtual ~Chooser() {}
	};

	//Things that implement sampling policies
	//A global value that is read-mod-stored to choose when to sample.
	//A sample is taken when the global counter hits 0
	class VISIBILITY_HIDDEN GlobalRandomCounter : public Chooser {
	GlobalVariable* Counter;
	Value* ResetValue;
	const Type* T;
	public:
	GlobalRandomCounter(Module& M, const Type* t, uint64_t resetval);
	virtual ~GlobalRandomCounter();
	virtual void PrepFunction(Function* F);
	virtual void ProcessChoicePoint(BasicBlock* bb);
	};

	//Same is GRC, but allow register allocation of the global counter
	class VISIBILITY_HIDDEN GlobalRandomCounterOpt : public Chooser {
	GlobalVariable* Counter;
	Value* ResetValue;
	AllocaInst* AI;
	const Type* T;
	public:
	GlobalRandomCounterOpt(Module& M, const Type* t, uint64_t resetval);
	virtual ~GlobalRandomCounterOpt();
	virtual void PrepFunction(Function* F);
	virtual void ProcessChoicePoint(BasicBlock* bb);
	};

	//Use the cycle counter intrinsic as a source of pseudo randomness when
	//deciding when to sample.
	class VISIBILITY_HIDDEN CycleCounter : public Chooser {
	uint64_t rm;
	Constant *F;
	public:
	CycleCounter(Module& m, uint64_t resetmask);
	virtual ~CycleCounter();
	virtual void PrepFunction(Function* F);
	virtual void ProcessChoicePoint(BasicBlock* bb);
	};

	/// ProfilerRS - Insert the random sampling framework
	struct VISIBILITY_HIDDEN ProfilerRS : public FunctionPass {
	static char ID; // Pass identification, replacement for typeid
	ProfilerRS() : FunctionPass((intptr_t)&ID) {}

	std::map<Value, Value> TransCache;
	std::set<BasicBlock*> ChoicePoints;
	Chooser* c;

	//Translate and duplicate values for the new profile free version of stuff
	Value* Translate(Value* v);
	//Duplicate an entire function (with out profiling)
	void Duplicate(Function& F, RSProfilers& LI);
	//Called once for each backedge, handle the insertion of choice points and
	//the interconection of the two versions of the code
	void ProcessBackEdge(BasicBlock* src, BasicBlock* dst, Function& F);
	bool runOnFunction(Function& F);
	bool doInitialization(Module &M);
	virtual void getAnalysisUsage(AnalysisUsage &AU) const;
	};

	RegisterPass<ProfilerRS> X("insert-rs-profiling-framework",
	"Insert random sampling instrumentation framework");
	}

	char RSProfilers::ID = 0;
	char NullProfilerRS::ID = 0;
	char ProfilerRS::ID = 0;

	//Local utilities
	static void ReplacePhiPred(BasicBlock* btarget,
	BasicBlock* bold, BasicBlock* bnew);

	static void CollapsePhi(BasicBlock* btarget, BasicBlock* bsrc);

	template<class T>
	static void recBackEdge(BasicBlock* bb, T& BackEdges,
	std::map<BasicBlock*, int>& color,
	std::map<BasicBlock*, int>& depth,
	std::map<BasicBlock*, int>& finish,
	int& time);

	//find the back edges and where they go to
	template<class T>
	static void getBackEdges(Function& F, T& BackEdges);


	///////////////////////////////////////
	// Methods of choosing when to profile
	///////////////////////////////////////

	GlobalRandomCounter::GlobalRandomCounter(Module& M, const Type* t,
	uint64_t resetval) : T(t) {
	ConstantInt* Init = ConstantInt::get(T, resetval);
	ResetValue = Init;
	Counter = new GlobalVariable(T, false, GlobalValue::InternalLinkage,
	Init, "RandomSteeringCounter", &M);
	}

	GlobalRandomCounter::~GlobalRandomCounter() {}

	void GlobalRandomCounter::PrepFunction(Function* F) {}

	void GlobalRandomCounter::ProcessChoicePoint(BasicBlock* bb) {
	BranchInst* t = cast<BranchInst>(bb->getTerminator());

	//decrement counter
	LoadInst* l = new LoadInst(Counter, "counter", t);

	ICmpInst* s = new ICmpInst(ICmpInst::ICMP_EQ, l, ConstantInt::get(T, 0),
	"countercc", t);

	Value* nv = BinaryOperator::createSub(l, ConstantInt::get(T, 1),
	"counternew", t);
	new StoreInst(nv, Counter, t);
	t->setCondition(s);

	//reset counter
	BasicBlock* oldnext = t->getSuccessor(0);
	BasicBlock* resetblock = new BasicBlock("reset", oldnext->getParent(),
	oldnext);
	TerminatorInst* t2 = new BranchInst(oldnext, resetblock);
	t->setSuccessor(0, resetblock);
	new StoreInst(ResetValue, Counter, t2);
	ReplacePhiPred(oldnext, bb, resetblock);
	}

	GlobalRandomCounterOpt::GlobalRandomCounterOpt(Module& M, const Type* t,
	uint64_t resetval)
	: AI(0), T(t) {
	ConstantInt* Init = ConstantInt::get(T, resetval);
	ResetValue = Init;
	Counter = new GlobalVariable(T, false, GlobalValue::InternalLinkage,
	Init, "RandomSteeringCounter", &M);
	}

	GlobalRandomCounterOpt::~GlobalRandomCounterOpt() {}

	void GlobalRandomCounterOpt::PrepFunction(Function* F) {
	//make a local temporary to cache the global
	BasicBlock& bb = F->getEntryBlock();
	BasicBlock::iterator InsertPt = bb.begin();
	AI = new AllocaInst(T, 0, "localcounter", InsertPt);
	LoadInst* l = new LoadInst(Counter, "counterload", InsertPt);
	new StoreInst(l, AI, InsertPt);

	//modify all functions and return values to restore the local variable to/from
	//the global variable
	for(Function::iterator fib = F->begin(), fie = F->end();
	fib != fie; ++fib)
	for(BasicBlock::iterator bib = fib->begin(), bie = fib->end();
	bib != bie; ++bib)
	if (isa<CallInst>(bib)) {
	LoadInst* l = new LoadInst(AI, "counter", bib);
	new StoreInst(l, Counter, bib);
	l = new LoadInst(Counter, "counter", ++bib);
	new StoreInst(l, AI, bib--);
	} else if (isa<InvokeInst>(bib)) {
	LoadInst* l = new LoadInst(AI, "counter", bib);
	new StoreInst(l, Counter, bib);

	BasicBlock* bb = cast<InvokeInst>(bib)->getNormalDest();
	BasicBlock::iterator i = bb->begin();
	while (isa<PHINode>(i))
	++i;
	l = new LoadInst(Counter, "counter", i);

	bb = cast<InvokeInst>(bib)->getUnwindDest();
	i = bb->begin();
	while (isa<PHINode>(i)) ++i;
	l = new LoadInst(Counter, "counter", i);
	new StoreInst(l, AI, i);
	} else if (isa<UnwindInst>(&bib) \|\| isa<ReturnInst>(&bib)) {
	LoadInst* l = new LoadInst(AI, "counter", bib);
	new StoreInst(l, Counter, bib);
	}
	}

	void GlobalRandomCounterOpt::ProcessChoicePoint(BasicBlock* bb) {
	BranchInst* t = cast<BranchInst>(bb->getTerminator());

	//decrement counter
	LoadInst* l = new LoadInst(AI, "counter", t);

	ICmpInst* s = new ICmpInst(ICmpInst::ICMP_EQ, l, ConstantInt::get(T, 0),
	"countercc", t);

	Value* nv = BinaryOperator::createSub(l, ConstantInt::get(T, 1),
	"counternew", t);
	new StoreInst(nv, AI, t);
	t->setCondition(s);

	//reset counter
	BasicBlock* oldnext = t->getSuccessor(0);
	BasicBlock* resetblock = new BasicBlock("reset", oldnext->getParent(),
	oldnext);
	TerminatorInst* t2 = new BranchInst(oldnext, resetblock);
	t->setSuccessor(0, resetblock);
	new StoreInst(ResetValue, AI, t2);
	ReplacePhiPred(oldnext, bb, resetblock);
	}


	CycleCounter::CycleCounter(Module& m, uint64_t resetmask) : rm(resetmask) {
	F = m.getOrInsertFunction("llvm.readcyclecounter", Type::Int64Ty, NULL);
	}

	CycleCounter::~CycleCounter() {}

	void CycleCounter::PrepFunction(Function* F) {}

	void CycleCounter::ProcessChoicePoint(BasicBlock* bb) {
	BranchInst* t = cast<BranchInst>(bb->getTerminator());

	CallInst* c = new CallInst(F, "rdcc", t);
	BinaryOperator* b =
	BinaryOperator::createAnd(c, ConstantInt::get(Type::Int64Ty, rm),
	"mrdcc", t);

	ICmpInst *s = new ICmpInst(ICmpInst::ICMP_EQ, b,
	ConstantInt::get(Type::Int64Ty, 0),
	"mrdccc", t);

	t->setCondition(s);
	}

	///////////////////////////////////////
	// Profiling:
	///////////////////////////////////////
	bool RSProfilers_std::isProfiling(Value* v) {
	if (profcode.find(v) != profcode.end())
	return true;
	//else
	RSProfilers& LI = getAnalysis<RSProfilers>();
	return LI.isProfiling(v);
	}

	void RSProfilers_std::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
	GlobalValue *CounterArray) {
	// Insert the increment after any alloca or PHI instructions...
	BasicBlock::iterator InsertPos = BB->begin();
	while (isa<AllocaInst>(InsertPos) \|\| isa<PHINode>(InsertPos))
	++InsertPos;

	// Create the getelementptr constant expression
	std::vector<Constant*> Indices(2);
	Indices[0] = Constant::getNullValue(Type::Int32Ty);
	Indices[1] = ConstantInt::get(Type::Int32Ty, CounterNum);
	Constant *ElementPtr = ConstantExpr::getGetElementPtr(CounterArray,
	&Indices[0], 2);

	// Load, increment and store the value back.
	Value *OldVal = new LoadInst(ElementPtr, "OldCounter", InsertPos);
	profcode.insert(OldVal);
	Value *NewVal = BinaryOperator::createAdd(OldVal,
	ConstantInt::get(Type::Int32Ty, 1),
	"NewCounter", InsertPos);
	profcode.insert(NewVal);
	profcode.insert(new StoreInst(NewVal, ElementPtr, InsertPos));
	}

	void RSProfilers_std::getAnalysisUsage(AnalysisUsage &AU) const {
	//grab any outstanding profiler, or get the null one
	AU.addRequired<RSProfilers>();
	}

	///////////////////////////////////////
	// RS Framework
	///////////////////////////////////////

	Value* ProfilerRS::Translate(Value* v) {
	if(TransCache[v])
	return TransCache[v];

	if (BasicBlock* bb = dyn_cast<BasicBlock>(v)) {
	if (bb == &bb->getParent()->getEntryBlock())
	TransCache[bb] = bb; //don't translate entry block
	else
	TransCache[bb] = new BasicBlock("dup_" + bb->getName(), bb->getParent(),
	NULL);
	return TransCache[bb];
	} else if (Instruction* i = dyn_cast<Instruction>(v)) {
	//we have already translated this
	//do not translate entry block allocas
	if(&i->getParent()->getParent()->getEntryBlock() == i->getParent()) {
	TransCache[i] = i;
	return i;
	} else {
	//translate this
	Instruction* i2 = i->clone();
	if (i->hasName())
	i2->setName("dup_" + i->getName());
	TransCache[i] = i2;
	//NumNewInst++;
	for (unsigned x = 0; x < i2->getNumOperands(); ++x)
	i2->setOperand(x, Translate(i2->getOperand(x)));
	return i2;
	}
	} else if (isa<Function>(v) \|\| isa<Constant>(v) \|\| isa<Argument>(v)) {
	TransCache[v] = v;
	return v;
	}
	assert(0 && "Value not handled");
	return 0;
	}

	void ProfilerRS::Duplicate(Function& F, RSProfilers& LI)
	{
	//perform a breadth first search, building up a duplicate of the code
	std::queue<BasicBlock*> worklist;
	std::set<BasicBlock*> seen;

	//This loop ensures proper BB order, to help performance
	for (Function::iterator fib = F.begin(), fie = F.end(); fib != fie; ++fib)
	worklist.push(fib);
	while (!worklist.empty()) {
	Translate(worklist.front());
	worklist.pop();
	}

	//remember than reg2mem created a new entry block we don't want to duplicate
	worklist.push(F.getEntryBlock().getTerminator()->getSuccessor(0));
	seen.insert(&F.getEntryBlock());

	while (!worklist.empty()) {
	BasicBlock* bb = worklist.front();
	worklist.pop();
	if(seen.find(bb) == seen.end()) {
	BasicBlock* bbtarget = cast<BasicBlock>(Translate(bb));
	BasicBlock::InstListType& instlist = bbtarget->getInstList();
	for (BasicBlock::iterator iib = bb->begin(), iie = bb->end();
	iib != iie; ++iib) {
	//NumOldInst++;
	if (!LI.isProfiling(&*iib)) {
	Instruction* i = cast<Instruction>(Translate(iib));
	instlist.insert(bbtarget->end(), i);
	}
	}
	//updated search state;
	seen.insert(bb);
	TerminatorInst* ti = bb->getTerminator();
	for (unsigned x = 0; x < ti->getNumSuccessors(); ++x) {
	BasicBlock* bbs = ti->getSuccessor(x);
	if (seen.find(bbs) == seen.end()) {
	worklist.push(bbs);
	}
	}
	}
	}
	}

	void ProfilerRS::ProcessBackEdge(BasicBlock* src, BasicBlock* dst, Function& F) {
	//given a backedge from B -> A, and translations A' and B',
	//a: insert C and C'
	//b: add branches in C to A and A' and in C' to A and A'
	//c: mod terminators@B, replace A with C
	//d: mod terminators@B', replace A' with C'
	//e: mod phis@A for pred B to be pred C
	// if multiple entries, simplify to one
	//f: mod phis@A' for pred B' to be pred C'
	// if multiple entries, simplify to one
	//g: for all phis@A with pred C using x
	// add in edge from C' using x'
	// add in edge from C using x in A'

	//a:
	Function::iterator BBN = src; ++BBN;
	BasicBlock* bbC = new BasicBlock("choice", &F, BBN);
	//ChoicePoints.insert(bbC);
	BBN = cast<BasicBlock>(Translate(src));
	BasicBlock* bbCp = new BasicBlock("choice", &F, ++BBN);
	ChoicePoints.insert(bbCp);

	//b:
	new BranchInst(cast<BasicBlock>(Translate(dst)), bbC);
	new BranchInst(dst, cast<BasicBlock>(Translate(dst)),
	ConstantInt::get(Type::Int1Ty, true), bbCp);
	//c:
	{
	TerminatorInst* iB = src->getTerminator();
	for (unsigned x = 0; x < iB->getNumSuccessors(); ++x)
	if (iB->getSuccessor(x) == dst)
	iB->setSuccessor(x, bbC);
	}
	//d:
	{
	TerminatorInst* iBp = cast<TerminatorInst>(Translate(src->getTerminator()));
	for (unsigned x = 0; x < iBp->getNumSuccessors(); ++x)
	if (iBp->getSuccessor(x) == cast<BasicBlock>(Translate(dst)))
	iBp->setSuccessor(x, bbCp);
	}
	//e:
	ReplacePhiPred(dst, src, bbC);
	//src could be a switch, in which case we are replacing several edges with one
	//thus collapse those edges int the Phi
	CollapsePhi(dst, bbC);
	//f:
	ReplacePhiPred(cast<BasicBlock>(Translate(dst)),
	cast<BasicBlock>(Translate(src)),bbCp);
	CollapsePhi(cast<BasicBlock>(Translate(dst)), bbCp);
	//g:
	for(BasicBlock::iterator ib = dst->begin(), ie = dst->end(); ib != ie;
	++ib)
	if (PHINode* phi = dyn_cast<PHINode>(&*ib)) {
	for(unsigned x = 0; x < phi->getNumIncomingValues(); ++x)
	if(bbC == phi->getIncomingBlock(x)) {
	phi->addIncoming(Translate(phi->getIncomingValue(x)), bbCp);
	cast<PHINode>(Translate(phi))->addIncoming(phi->getIncomingValue(x),
	bbC);
	}
	phi->removeIncomingValue(bbC);
	}
	}

	bool ProfilerRS::runOnFunction(Function& F) {
	if (!F.isDeclaration()) {
	std::set<std::pair<BasicBlock, BasicBlock> > BackEdges;
	RSProfilers& LI = getAnalysis<RSProfilers>();

	getBackEdges(F, BackEdges);
	Duplicate(F, LI);
	//assume that stuff worked. now connect the duplicated basic blocks
	//with the originals in such a way as to preserve ssa. yuk!
	for (std::set<std::pair<BasicBlock, BasicBlock> >::iterator
	ib = BackEdges.begin(), ie = BackEdges.end(); ib != ie; ++ib)
	ProcessBackEdge(ib->first, ib->second, F);

	//oh, and add the edge from the reg2mem created entry node to the
	//duplicated second node
	TerminatorInst* T = F.getEntryBlock().getTerminator();
	ReplaceInstWithInst(T, new BranchInst(T->getSuccessor(0),
	cast<BasicBlock>(
	Translate(T->getSuccessor(0))),
	ConstantInt::get(Type::Int1Ty, true)));

	//do whatever is needed now that the function is duplicated
	c->PrepFunction(&F);

	//add entry node to choice points
	ChoicePoints.insert(&F.getEntryBlock());

	for (std::set<BasicBlock*>::iterator
	ii = ChoicePoints.begin(), ie = ChoicePoints.end(); ii != ie; ++ii)
	c->ProcessChoicePoint(*ii);

	ChoicePoints.clear();
	TransCache.clear();

	return true;
	}
	return false;
	}

	bool ProfilerRS::doInitialization(Module &M) {
	switch (RandomMethod) {
	case GBV:
	c = new GlobalRandomCounter(M, Type::Int32Ty, (1 << 14) - 1);
	break;
	case GBVO:
	c = new GlobalRandomCounterOpt(M, Type::Int32Ty, (1 << 14) - 1);
	break;
	case HOSTCC:
	c = new CycleCounter(M, (1 << 14) - 1);
	break;
	};
	return true;
	}

	void ProfilerRS::getAnalysisUsage(AnalysisUsage &AU) const {
	AU.addRequired<RSProfilers>();
	AU.addRequiredID(DemoteRegisterToMemoryID);
	}

	///////////////////////////////////////
	// Utilities:
	///////////////////////////////////////
	static void ReplacePhiPred(BasicBlock* btarget,
	BasicBlock* bold, BasicBlock* bnew) {
	for(BasicBlock::iterator ib = btarget->begin(), ie = btarget->end();
	ib != ie; ++ib)
	if (PHINode* phi = dyn_cast<PHINode>(&*ib)) {
	for(unsigned x = 0; x < phi->getNumIncomingValues(); ++x)
	if(bold == phi->getIncomingBlock(x))
	phi->setIncomingBlock(x, bnew);
	}
	}

	static void CollapsePhi(BasicBlock* btarget, BasicBlock* bsrc) {
	for(BasicBlock::iterator ib = btarget->begin(), ie = btarget->end();
	ib != ie; ++ib)
	if (PHINode* phi = dyn_cast<PHINode>(&*ib)) {
	std::map<BasicBlock, Value> counter;
	for(unsigned i = 0; i < phi->getNumIncomingValues(); ) {
	if (counter[phi->getIncomingBlock(i)]) {
	assert(phi->getIncomingValue(i) == counter[phi->getIncomingBlock(i)]);
	phi->removeIncomingValue(i, false);
	} else {
	counter[phi->getIncomingBlock(i)] = phi->getIncomingValue(i);
	++i;
	}
	}
	}
	}

	template<class T>
	static void recBackEdge(BasicBlock* bb, T& BackEdges,
	std::map<BasicBlock*, int>& color,
	std::map<BasicBlock*, int>& depth,
	std::map<BasicBlock*, int>& finish,
	int& time)
	{
	color[bb] = 1;
	++time;
	depth[bb] = time;
	TerminatorInst* t= bb->getTerminator();
	for(unsigned i = 0; i < t->getNumSuccessors(); ++i) {
	BasicBlock* bbnew = t->getSuccessor(i);
	if (color[bbnew] == 0)
	recBackEdge(bbnew, BackEdges, color, depth, finish, time);
	else if (color[bbnew] == 1) {
	BackEdges.insert(std::make_pair(bb, bbnew));
	//NumBackEdges++;
	}
	}
	color[bb] = 2;
	++time;
	finish[bb] = time;
	}



	//find the back edges and where they go to
	template<class T>
	static void getBackEdges(Function& F, T& BackEdges) {
	std::map<BasicBlock*, int> color;
	std::map<BasicBlock*, int> depth;
	std::map<BasicBlock*, int> finish;
	int time = 0;
	recBackEdge(&F.getEntryBlock(), BackEdges, color, depth, finish, time);
	DOUT << F.getName() << " " << BackEdges.size() << "\n";
	}


	//Creation functions
	ModulePass* llvm::createNullProfilerRSPass() {
	return new NullProfilerRS();
	}

	FunctionPass* llvm::createRSProfilingPass() {
	return new ProfilerRS();
	}