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#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include <unordered_set>
#include <random>
#include "MarkNodes.h"
using namespace llvm;
static cl::opt<bool> MarkSetOpt("markset", cl::desc("MarkSet"),
cl::init(false));
static cl::opt<bool> LoopHeadOpt("loophead", cl::desc("LoopHead"),
cl::init(false));
namespace {
struct InsTrim : public ModulePass {
private:
std::mt19937 generator;
int total_instr = 0;
unsigned genLabel() {
return generator() % 65536;
}
public:
static char ID;
InsTrim() : ModulePass(ID), generator(0) {}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<DominatorTreeWrapperPass>();
}
StringRef getPassName() const override {
return "InstTrim Instrumentation";
}
bool runOnModule(Module &M) override {
if (getenv("LOOPHEAD")) {
LoopHeadOpt = true;
MarkSetOpt = true;
} else if (getenv("MARKSET")) {
MarkSetOpt = true;
}
LLVMContext &C = M.getContext();
IntegerType *Int8Ty = IntegerType::getInt8Ty(C);
IntegerType *Int32Ty = IntegerType::getInt32Ty(C);
GlobalVariable *CovMapPtr = new GlobalVariable(
M, PointerType::getUnqual(Int8Ty), false, GlobalValue::ExternalLinkage,
nullptr, "__afl_area_ptr");
GlobalVariable *OldPrev = new GlobalVariable(
M, Int32Ty, false, GlobalValue::ExternalLinkage, 0, "__afl_prev_loc",
0, GlobalVariable::GeneralDynamicTLSModel, 0, false);
unsigned total_rs = 0;
unsigned total_hs = 0;
for (Function &F : M) {
if (!F.size()) {
continue;
}
std::unordered_set<BasicBlock *> MS;
if (!MarkSetOpt) {
for (auto &BB : F) {
MS.insert(&BB);
}
total_rs += F.size();
} else {
auto Result = markNodes(&F);
auto RS = Result.first;
auto HS = Result.second;
MS.insert(RS.begin(), RS.end());
if (!LoopHeadOpt) {
MS.insert(HS.begin(), HS.end());
total_rs += MS.size();
} else {
DenseSet<std::pair<BasicBlock *, BasicBlock *>> EdgeSet;
DominatorTreeWrapperPass *DTWP =
&getAnalysis<DominatorTreeWrapperPass>(F);
auto DT = &DTWP->getDomTree();
total_rs += RS.size();
total_hs += HS.size();
for (BasicBlock *BB : HS) {
bool Inserted = false;
for (auto BI = pred_begin(BB), BE = pred_end(BB);
BI != BE; ++BI
) {
auto Edge = BasicBlockEdge(*BI, BB);
if (Edge.isSingleEdge() && DT->dominates(Edge, BB)) {
EdgeSet.insert({*BI, BB});
Inserted = true;
break;
}
}
if (!Inserted) {
MS.insert(BB);
total_rs += 1;
total_hs -= 1;
}
}
for (auto I = EdgeSet.begin(), E = EdgeSet.end(); I != E; ++I) {
auto PredBB = I->first;
auto SuccBB = I->second;
auto NewBB = SplitBlockPredecessors(SuccBB, {PredBB}, ".split",
DT);
MS.insert(NewBB);
}
}
auto *EBB = &F.getEntryBlock();
if (succ_begin(EBB) == succ_end(EBB)) {
MS.insert(EBB);
total_rs += 1;
}
for (BasicBlock &BB : F) {
if (MS.find(&BB) == MS.end()) {
continue;
}
IRBuilder<> IRB(&*BB.getFirstInsertionPt());
IRB.CreateStore(ConstantInt::get(Int32Ty, genLabel()), OldPrev);
}
}
for (BasicBlock &BB : F) {
auto PI = pred_begin(&BB);
auto PE = pred_end(&BB);
if (MarkSetOpt && MS.find(&BB) == MS.end()) {
continue;
}
IRBuilder<> IRB(&*BB.getFirstInsertionPt());
Value *L = NULL;
if (PI == PE) {
L = ConstantInt::get(Int32Ty, genLabel());
} else {
auto *PN = PHINode::Create(Int32Ty, 0, "", &*BB.begin());
DenseMap<BasicBlock *, unsigned> PredMap;
for (auto PI = pred_begin(&BB), PE = pred_end(&BB);
PI != PE; ++PI
) {
BasicBlock *PBB = *PI;
auto It = PredMap.insert({PBB, genLabel()});
unsigned Label = It.first->second;
PN->addIncoming(ConstantInt::get(Int32Ty, Label), PBB);
}
L = PN;
}
LoadInst *PrevLoc = IRB.CreateLoad(OldPrev);
Value *PrevLocCasted = IRB.CreateZExt(PrevLoc, IRB.getInt32Ty());
LoadInst *MapPtr = IRB.CreateLoad(CovMapPtr);
Value *MapPtrIdx = IRB.CreateGEP(MapPtr,
IRB.CreateXor(PrevLocCasted, L));
LoadInst *Counter = IRB.CreateLoad(MapPtrIdx);
Value *Incr = IRB.CreateAdd(Counter, ConstantInt::get(Int8Ty, 1));
IRB.CreateStore(Incr, MapPtrIdx);
total_instr++;
}
}
errs() << total_instr << " locations instrumented ("<< total_rs << "," << total_hs << ")\n";
return false;
}
}; // end of struct InsTrim
} // end of anonymous namespace
char InsTrim::ID = 0;
static void registerAFLPass(const PassManagerBuilder &,
legacy::PassManagerBase &PM) {
PM.add(new InsTrim());
}
static RegisterStandardPasses RegisterAFLPass(
PassManagerBuilder::EP_OptimizerLast, registerAFLPass);
static RegisterStandardPasses RegisterAFLPass0(
PassManagerBuilder::EP_EnabledOnOptLevel0, registerAFLPass);
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