1 //===-- InstLoops.cpp ---------------------------------------- ---*- C++ -*--=//
2 // Pass to instrument loops
4 // At every backedge, insert a counter for that backedge and a call function
5 //===----------------------------------------------------------------------===//
7 #include "llvm/Analysis/Dominators.h"
8 #include "llvm/Support/CFG.h"
9 #include "llvm/Constants.h"
10 #include "llvm/iMemory.h"
11 #include "llvm/GlobalVariable.h"
12 #include "llvm/DerivedTypes.h"
13 #include "llvm/iOther.h"
14 #include "llvm/iOperators.h"
15 #include "llvm/iTerminators.h"
16 #include "llvm/iPHINode.h"
17 #include "llvm/Module.h"
18 #include "llvm/Function.h"
19 #include "llvm/Pass.h"
21 //this is used to color vertices
31 typedef std::map<BasicBlock *, BasicBlock *> BBMap;
32 struct InstLoops : public FunctionPass {
33 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
34 AU.addRequired<DominatorSet>();
38 void getBackEdgesVisit(BasicBlock *u,
39 std::map<BasicBlock *, Color > &color,
40 std::map<BasicBlock *, int > &d,
41 int &time, BBMap &be);
42 void removeRedundant(BBMap &be);
43 void findAndInstrumentBackEdges(Function &F);
45 bool runOnFunction(Function &F);
48 RegisterOpt<InstLoops> X("instloops", "Instrument backedges for profiling");
51 //helper function to get back edges: it is called by
52 //the "getBackEdges" function below
53 void InstLoops::getBackEdgesVisit(BasicBlock *u,
54 std::map<BasicBlock *, Color > &color,
55 std::map<BasicBlock *, int > &d,
56 int &time, BBMap &be) {
61 for(succ_iterator vl = succ_begin(u), ve = succ_end(u); vl != ve; ++vl){
64 if(color[BB]!=GREY && color[BB]!=BLACK){
65 getBackEdgesVisit(BB, color, d, time, be);
68 //now checking for d and f vals
69 else if(color[BB]==GREY){
70 //so v is ancestor of u if time of u > time of v
77 color[u]=BLACK;//done with visiting the node and its neighbors
80 //look at all BEs, and remove all BEs that are dominated by other BE's in the
82 void InstLoops::removeRedundant(BBMap &be) {
83 std::vector<BasicBlock *> toDelete;
84 for(std::map<BasicBlock *, BasicBlock *>::iterator MI = be.begin(),
85 ME = be.end(); MI != ME; ++MI)
86 for(BBMap::iterator MMI = be.begin(), MME = be.end(); MMI != MME; ++MMI)
87 if(DS->properlyDominates(MI->first, MMI->first))
88 toDelete.push_back(MMI->first);
89 // Remove all the back-edges we found from be.
90 for(std::vector<BasicBlock *>::iterator VI = toDelete.begin(),
91 VE = toDelete.end(); VI != VE; ++VI)
95 //getting the backedges in a graph
96 //Its a variation of DFS to get the backedges in the graph
97 //We get back edges by associating a time
98 //and a color with each vertex.
99 //The time of a vertex is the time when it was first visited
100 //The color of a vertex is initially WHITE,
101 //Changes to GREY when it is first visited,
102 //and changes to BLACK when ALL its neighbors
104 //So we have a back edge when we meet a successor of
105 //a node with smaller time, and GREY color
106 void InstLoops::findAndInstrumentBackEdges(Function &F){
107 std::map<BasicBlock *, Color > color;
108 std::map<BasicBlock *, int> d;
111 getBackEdgesVisit(F.begin(), color, d, time, be);
115 // FIXME: THIS IS HORRIBLY BROKEN. FunctionPass's cannot do this, except in
116 // their initialize function!!
117 Function *inCountMth =
118 F.getParent()->getOrInsertFunction("llvm_first_trigger",
121 for(std::map<BasicBlock *, BasicBlock *>::iterator MI = be.begin(),
122 ME = be.end(); MI != ME; ++MI){
123 BasicBlock *u = MI->first;
124 BasicBlock *BB = MI->second;
125 //std::cerr<<"Edge from: "<<BB->getName()<<"->"<<u->getName()<<"\n";
126 //insert a new basic block: modify terminator accordingly!
127 BasicBlock *newBB = new BasicBlock("", u->getParent());
128 BranchInst *ti = cast<BranchInst>(u->getTerminator());
129 unsigned char index = 1;
130 if(ti->getSuccessor(0) == BB){
133 assert(ti->getNumSuccessors() > index && "Not enough successors!");
134 ti->setSuccessor(index, newBB);
136 BasicBlock::InstListType < = newBB->getInstList();
138 Instruction *call = new CallInst(inCountMth);
140 lt.push_back(new BranchInst(BB));
142 //now iterate over *vl, and set its Phi nodes right
143 for(BasicBlock::iterator BB2Inst = BB->begin(), BBend = BB->end();
144 BB2Inst != BBend; ++BB2Inst){
146 if (PHINode *phiInst = dyn_cast<PHINode>(BB2Inst)){
147 int bbIndex = phiInst->getBasicBlockIndex(u);
149 phiInst->setIncomingBlock(bbIndex, newBB);
156 /// Entry point for FunctionPass that inserts calls to trigger function.
158 bool InstLoops::runOnFunction(Function &F){
159 DS = &getAnalysis<DominatorSet>();
163 // Add a call to reoptimizerInitialize() to beginning of function named main.
164 if(F.getName() == "main"){
165 std::vector<const Type*> argTypes; // Empty formal parameter list.
166 const FunctionType *Fty = FunctionType::get(Type::VoidTy, argTypes, false);
167 Function *initialMeth =
168 F.getParent()->getOrInsertFunction("reoptimizerInitialize", Fty);
169 assert(initialMeth && "Initialize method could not be inserted!");
170 new CallInst(initialMeth, "", F.begin()->begin()); // Insert it.
172 findAndInstrumentBackEdges(F);
173 return true; // Function was modified.