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//===-- InstLoops.cpp -----------------------------------------------------===//
//
// 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.
//
//===----------------------------------------------------------------------===//
//
// Pass to instrument loops
//
// At every backedge, insert a counter for that backedge and a call function
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/Dominators.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
};
namespace {
typedef std::map<BasicBlock *, BasicBlock *> BBMap;
struct InstLoops : public FunctionPass {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorSet>();
}
private:
DominatorSet *DS;
void getBackEdgesVisit(BasicBlock *u,
std::map<BasicBlock *, Color > &color,
std::map<BasicBlock *, int > &d,
int &time, BBMap &be);
void removeRedundant(BBMap &be);
void findAndInstrumentBackEdges(Function &F);
public:
bool runOnFunction(Function &F);
};
RegisterOpt<InstLoops> X("instloops", "Instrument backedges for profiling");
}
//helper function to get back edges: it is called by
//the "getBackEdges" function below
void InstLoops::getBackEdgesVisit(BasicBlock *u,
std::map<BasicBlock *, Color > &color,
std::map<BasicBlock *, int > &d,
int &time, BBMap &be) {
color[u]=GREY;
time++;
d[u]=time;
for(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, be);
}
//now checking for d and f vals
else if(color[BB]==GREY){
//so v is ancestor of u if time of u > time of v
if(d[u] >= d[BB]){
//u->BB is a backedge
be[u] = BB;
}
}
}
color[u]=BLACK;//done with visiting the node and its neighbors
}
//look at all BEs, and remove all BEs that are dominated by other BE's in the
//set
void InstLoops::removeRedundant(BBMap &be) {
std::vector<BasicBlock *> toDelete;
for(std::map<BasicBlock *, BasicBlock *>::iterator MI = be.begin(),
ME = be.end(); MI != ME; ++MI)
for(BBMap::iterator MMI = be.begin(), MME = be.end(); MMI != MME; ++MMI)
if(DS->properlyDominates(MI->first, MMI->first))
toDelete.push_back(MMI->first);
// Remove all the back-edges we found from be.
for(std::vector<BasicBlock *>::iterator VI = toDelete.begin(),
VE = toDelete.end(); VI != VE; ++VI)
be.erase(*VI);
}
//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 InstLoops::findAndInstrumentBackEdges(Function &F){
std::map<BasicBlock *, Color > color;
std::map<BasicBlock *, int> d;
BBMap be;
int time=0;
getBackEdgesVisit(F.begin(), color, d, time, be);
removeRedundant(be);
// FIXME: THIS IS HORRIBLY BROKEN. FunctionPass's cannot do this, except in
// their initialize function!!
Function *inCountMth =
F.getParent()->getOrInsertFunction("llvm_first_trigger",
Type::VoidTy, 0);
for(std::map<BasicBlock *, BasicBlock *>::iterator MI = be.begin(),
ME = be.end(); MI != ME; ++MI){
BasicBlock *u = MI->first;
BasicBlock *BB = MI->second;
//std::cerr<<"Edge from: "<<BB->getName()<<"->"<<u->getName()<<"\n";
//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);
BasicBlock::InstListType < = newBB->getInstList();
Instruction *call = new CallInst(inCountMth);
lt.push_back(call);
lt.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);
}
}
}
}
}
/// Entry point for FunctionPass that inserts calls to trigger function.
///
bool InstLoops::runOnFunction(Function &F){
DS = &getAnalysis<DominatorSet>();
if(F.isExternal()) {
return false;
}
// Add a call to reoptimizerInitialize() to beginning of function named main.
if(F.getName() == "main"){
std::vector<const Type*> argTypes; // Empty formal parameter list.
const FunctionType *Fty = FunctionType::get(Type::VoidTy, argTypes, false);
Function *initialMeth =
F.getParent()->getOrInsertFunction("reoptimizerInitialize", Fty);
assert(initialMeth && "Initialize method could not be inserted!");
new CallInst(initialMeth, "", F.begin()->begin()); // Insert it.
}
findAndInstrumentBackEdges(F);
return true; // Function was modified.
}
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