code to lightly instrument at branches

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4511 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Instrumentation/ProfilePaths/InstLoops.cpp

@@ -0,0 +1,210 @@
+//===-- InstLoops.cpp ---------------------------------------- ---*- C++ -*--=//
+// Pass to instrument loops
+//
+// At every backedge, insert a counter for that backedge and a call function
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Reoptimizer/InstLoops.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Constants.h"
+#include "llvm/iMemory.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/iOther.h"
+#include "llvm/iOperators.h"
+#include "llvm/iTerminators.h"
+#include "llvm/iPHINode.h"
+#include "llvm/Module.h"
+#include "llvm/Function.h"
+#include "llvm/Pass.h"
+
+//this is used to color vertices
+//during DFS
+
+enum Color{
+  WHITE,
+  GREY,
+  BLACK
+};
+
+struct InstLoops : public FunctionPass {
+  bool runOnFunction(Function &F);
+};
+
+static RegisterOpt<InstLoops> X("instloops", "Instrument backedges for profiling");
+
+// createProfilePathsPass - Create a new pass to add path profiling
+//
+Pass *createInstLoopsPass() {
+  return new InstLoops();
+}
+
+
+//helper function to get back edges: it is called by 
+//the "getBackEdges" function below
+void getBackEdgesVisit(BasicBlock *u,
+                       std::map<BasicBlock *, Color > &color,
+                       std::map<BasicBlock *, int > &d, 
+                       int &time, Value *threshold) {
+  
+  color[u]=GREY;
+  time++;
+  d[u]=time;
+
+  for(BasicBlock::succ_iterator vl = succ_begin(u), 
+	ve = succ_end(u); vl != ve; ++vl){
+    
+    BasicBlock *BB = *vl;
+
+    if(color[BB]!=GREY && color[BB]!=BLACK){
+      getBackEdgesVisit(BB, color, d, time, threshold);
+    }
+    
+    //now checking for d and f vals
+    if(color[BB]==GREY){
+      //so v is ancestor of u if time of u > time of v
+      if(d[u] >= d[BB]){
+        //insert a new basic block: modify terminator accordingly!
+        BasicBlock *newBB = new BasicBlock("", u->getParent());
+        BranchInst *ti = cast<BranchInst>(u->getTerminator());
+        unsigned char index = 1;
+        if(ti->getSuccessor(0) == BB){
+          index = 0;
+        }
+        assert(ti->getNumSuccessors() > index && "Not enough successors!");
+        ti->setSuccessor(index, newBB);
+
+        //insert global variable of type int
+        Constant *initializer = Constant::getNullValue(Type::IntTy);
+        GlobalVariable *countVar = new GlobalVariable(Type::IntTy, false, true, 
+                                                      initializer, 
+                                                      "loopCounter", 
+                                                      u->getParent()->getParent());
+        
+        //load the variable
+        Instruction *ldInst = new LoadInst(countVar,"");
+        
+        //increment
+        Instruction *addIn = 
+          BinaryOperator::create(Instruction::Add, ldInst, 
+                                 ConstantSInt::get(Type::IntTy,1), "");
+
+        //store
+        Instruction *stInst = new StoreInst(addIn, countVar);
+
+
+        Instruction *etr = new LoadInst(threshold, "threshold");
+        Instruction *cmpInst = new SetCondInst(Instruction::SetLE, etr, 
+                                               addIn, "");
+        
+        BasicBlock *callTrigger = new BasicBlock("", u->getParent());
+        //branch to calltrigger, or *vl
+        Instruction *newBr = new BranchInst(callTrigger, BB, cmpInst);
+
+        BasicBlock::InstListType &lt = newBB->getInstList();
+
+        lt.push_back(ldInst);
+        lt.push_back(addIn);
+        lt.push_back(stInst);
+        lt.push_back(etr);
+        lt.push_back(cmpInst);
+        lt.push_back(newBr);
+
+        //Now add instructions to the triggerCall BB
+        //now create a call function
+        //call llvm_first_trigger(int *x);
+        std::vector<const Type*> inCountArgs;
+        inCountArgs.push_back(PointerType::get(Type::IntTy));
+ 
+        const FunctionType *cFty = FunctionType::get(Type::VoidTy, inCountArgs, 
+                                                     false);
+        Function *inCountMth = 
+          u->getParent()->getParent()->getOrInsertFunction("llvm_first_trigger", cFty);
+        
+        assert(inCountMth && "Initialize method could not be inserted!");
+
+        std::vector<Value *> iniArgs;
+        iniArgs.push_back(countVar);
+        Instruction *call = new CallInst(inCountMth, iniArgs, "");
+        callTrigger->getInstList().push_back(call);
+        callTrigger->getInstList().push_back(new BranchInst(BB));
+      
+        //now iterate over *vl, and set its Phi nodes right
+        for(BasicBlock::iterator BB2Inst = BB->begin(), BBend = BB->end(); 
+            BB2Inst != BBend; ++BB2Inst){
+        
+          if(PHINode *phiInst=dyn_cast<PHINode>(&*BB2Inst)){
+            int bbIndex = phiInst->getBasicBlockIndex(u);
+            if(bbIndex>=0){
+              phiInst->setIncomingBlock(bbIndex, newBB);
+          
+              Value *val = phiInst->getIncomingValue((unsigned int)bbIndex);
+              phiInst->addIncoming(val, callTrigger);
+            }
+          }
+        }
+      }
+    }
+  }
+  color[u]=BLACK;//done with visiting the node and its neighbors
+}
+
+
+//getting the backedges in a graph
+//Its a variation of DFS to get the backedges in the graph
+//We get back edges by associating a time
+//and a color with each vertex.
+//The time of a vertex is the time when it was first visited
+//The color of a vertex is initially WHITE,
+//Changes to GREY when it is first visited,
+//and changes to BLACK when ALL its neighbors
+//have been visited
+//So we have a back edge when we meet a successor of
+//a node with smaller time, and GREY color
+void getBackEdges(Function &F, Value *threshold){
+  std::map<BasicBlock *, Color > color;
+  std::map<BasicBlock *, int> d;
+  int time=0;
+  getBackEdgesVisit(F.begin(), color, d, time, threshold);
+}
+
+//Per function pass for inserting counters and call function
+bool InstLoops::runOnFunction(Function &F){
+  
+  static GlobalVariable *threshold = NULL;
+  static bool insertedThreshold = false;
+  
+   if(!insertedThreshold){
+    threshold = new GlobalVariable(Type::IntTy, false, false, 0,
+                                                   "reopt_threshold");
+
+    F.getParent()->getGlobalList().push_back(threshold);
+    insertedThreshold = true;
+  }
+
+  if(F.getName() == "main"){
+    //intialize threshold
+    std::vector<const Type*> initialize_args;
+    initialize_args.push_back(PointerType::get(Type::IntTy));
+    
+    const FunctionType *Fty = FunctionType::get(Type::VoidTy, initialize_args,
+                                                false);
+    Function *initialMeth = F.getParent()->getOrInsertFunction("reoptimizerInitialize", Fty);
+    assert(initialMeth && "Initialize method could not be inserted!");
+    
+    std::vector<Value *> trargs;
+    trargs.push_back(threshold);
+  
+    new CallInst(initialMeth, trargs, "", F.begin()->begin());
+  }
+
+  assert(threshold && "GlobalVariable threshold not defined!");
+
+  if(F.isExternal()) {
+    return false;
+  }
+
+  getBackEdges(F, threshold);
+  
+  return true;
+}