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(BasicBlock::succ_iterator vl = succ_begin(u),
62 ve = succ_end(u); vl != ve; ++vl){
65 if(color[BB]!=GREY && color[BB]!=BLACK){
66 getBackEdgesVisit(BB, color, d, time, be);
69 //now checking for d and f vals
70 else if(color[BB]==GREY){
71 //so v is ancestor of u if time of u > time of v
78 color[u]=BLACK;//done with visiting the node and its neighbors
81 //look at all BEs, and remove all BEs that are dominated by other BE's in the
83 void InstLoops::removeRedundant(BBMap &be) {
84 std::vector<BasicBlock *> toDelete;
85 for(std::map<BasicBlock *, BasicBlock *>::iterator MI = be.begin(),
86 ME = be.end(); MI != ME; ++MI)
87 for(BBMap::iterator MMI = be.begin(), MME = be.end(); MMI != MME; ++MMI)
88 if(DS->properlyDominates(MI->first, MMI->first))
89 toDelete.push_back(MMI->first);
90 // Remove all the back-edges we found from be.
91 for(std::vector<BasicBlock *>::iterator VI = toDelete.begin(),
92 VE = toDelete.end(); VI != VE; ++VI)
96 //getting the backedges in a graph
97 //Its a variation of DFS to get the backedges in the graph
98 //We get back edges by associating a time
99 //and a color with each vertex.
100 //The time of a vertex is the time when it was first visited
101 //The color of a vertex is initially WHITE,
102 //Changes to GREY when it is first visited,
103 //and changes to BLACK when ALL its neighbors
105 //So we have a back edge when we meet a successor of
106 //a node with smaller time, and GREY color
107 void InstLoops::findAndInstrumentBackEdges(Function &F){
108 std::map<BasicBlock *, Color > color;
109 std::map<BasicBlock *, int> d;
112 getBackEdgesVisit(F.begin(), color, d, time, be);
116 // FIXME: THIS IS HORRIBLY BROKEN. FunctionPass's cannot do this, except in
117 // their initialize function!!
118 Function *inCountMth =
119 F.getParent()->getOrInsertFunction("llvm_first_trigger",
122 for(std::map<BasicBlock *, BasicBlock *>::iterator MI = be.begin(),
123 ME = be.end(); MI != ME; ++MI){
124 BasicBlock *u = MI->first;
125 BasicBlock *BB = MI->second;
126 //std::cerr<<"Edge from: "<<BB->getName()<<"->"<<u->getName()<<"\n";
127 //insert a new basic block: modify terminator accordingly!
128 BasicBlock *newBB = new BasicBlock("", u->getParent());
129 BranchInst *ti = cast<BranchInst>(u->getTerminator());
130 unsigned char index = 1;
131 if(ti->getSuccessor(0) == BB){
134 assert(ti->getNumSuccessors() > index && "Not enough successors!");
135 ti->setSuccessor(index, newBB);
137 BasicBlock::InstListType < = newBB->getInstList();
139 Instruction *call = new CallInst(inCountMth);
141 lt.push_back(new BranchInst(BB));
143 //now iterate over *vl, and set its Phi nodes right
144 for(BasicBlock::iterator BB2Inst = BB->begin(), BBend = BB->end();
145 BB2Inst != BBend; ++BB2Inst){
147 if (PHINode *phiInst = dyn_cast<PHINode>(BB2Inst)){
148 int bbIndex = phiInst->getBasicBlockIndex(u);
150 phiInst->setIncomingBlock(bbIndex, newBB);
157 /// Entry point for FunctionPass that inserts calls to trigger function.
159 bool InstLoops::runOnFunction(Function &F){
160 DS = &getAnalysis<DominatorSet>();
164 // Add a call to reoptimizerInitialize() to beginning of function named main.
165 if(F.getName() == "main"){
166 std::vector<const Type*> argTypes; // Empty formal parameter list.
167 const FunctionType *Fty = FunctionType::get(Type::VoidTy, argTypes, false);
168 Function *initialMeth =
169 F.getParent()->getOrInsertFunction("reoptimizerInitialize", Fty);
170 assert(initialMeth && "Initialize method could not be inserted!");
171 new CallInst(initialMeth, "", F.begin()->begin()); // Insert it.
173 findAndInstrumentBackEdges(F);
174 return true; // Function was modified.