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//===-- MergeHandler.cpp --------------------------------------------------===//
//
// The KLEE Symbolic Virtual Machine
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "klee/MergeHandler.h"
#include "CoreStats.h"
#include "Executor.h"
#include "klee/ExecutionState.h"
namespace klee {
llvm::cl::opt<bool>
UseMerge("use-merge",
llvm::cl::init(false),
llvm::cl::desc("Enable support for klee_open_merge() and klee_close_merge() (experimental)"));
llvm::cl::opt<bool>
DebugLogMerge("debug-log-merge",
llvm::cl::init(false),
llvm::cl::desc("Enhanced verbosity for region based merge operations"));
llvm::cl::opt<bool>
UseIncompleteMerge("use-incomplete-merge",
llvm::cl::init(false),
llvm::cl::desc("Heuristic based merging"));
llvm::cl::opt<bool>
DebugLogIncompleteMerge("debug-log-incomplete-merge",
llvm::cl::init(false),
llvm::cl::desc("Debug info about incomplete merging"));
double MergeHandler::getMean() {
if (closedStateCount == 0)
return 0;
return closedMean;
}
unsigned MergeHandler::getInstructionDistance(ExecutionState *es){
return es->steppedInstructions - openInstruction;
}
ExecutionState *MergeHandler::getPrioritizeState(){
for (ExecutionState *cur_state : openStates) {
bool stateIsClosed = (executor->inCloseMerge.find(cur_state) !=
executor->inCloseMerge.end());
if (!stateIsClosed && (getInstructionDistance(cur_state) < 2 * getMean())) {
return cur_state;
}
}
return 0;
}
void MergeHandler::addOpenState(ExecutionState *es){
openStates.push_back(es);
}
void MergeHandler::removeOpenState(ExecutionState *es){
auto it = std::find(openStates.begin(), openStates.end(), es);
assert(it != openStates.end());
std::swap(*it, openStates.back());
openStates.pop_back();
}
void MergeHandler::addClosedState(ExecutionState *es,
llvm::Instruction *mp) {
// Update stats
++closedStateCount;
// Incremental update of mean (travelling mean)
// https://math.stackexchange.com/a/1836447
closedMean += (static_cast<double>(getInstructionDistance(es)) - closedMean) /
closedStateCount;
// Remove from openStates
removeOpenState(es);
auto closePoint = reachedCloseMerge.find(mp);
// If no other state has yet encountered this klee_close_merge instruction,
// add a new element to the map
if (closePoint == reachedCloseMerge.end()) {
reachedCloseMerge[mp].push_back(es);
executor->pauseState(*es);
} else {
// Otherwise try to merge with any state in the map element for this
// instruction
auto &cpv = closePoint->second;
bool mergedSuccessful = false;
for (auto& mState: cpv) {
if (mState->merge(*es)) {
executor->terminateState(*es);
executor->inCloseMerge.erase(es);
mergedSuccessful = true;
break;
}
}
if (!mergedSuccessful) {
cpv.push_back(es);
executor->pauseState(*es);
}
}
}
void MergeHandler::releaseStates() {
for (auto& curMergeGroup: reachedCloseMerge) {
for (auto curState: curMergeGroup.second) {
executor->continueState(*curState);
executor->inCloseMerge.erase(curState);
}
}
reachedCloseMerge.clear();
}
bool MergeHandler::hasMergedStates() {
return (!reachedCloseMerge.empty());
}
MergeHandler::MergeHandler(Executor *_executor, ExecutionState *es)
: executor(_executor), openInstruction(es->steppedInstructions),
closedStateCount(0), refCount(0) {
executor->mergeGroups.push_back(this);
addOpenState(es);
}
MergeHandler::~MergeHandler() {
auto it = std::find(executor->mergeGroups.begin(),
executor->mergeGroups.end(), this);
std::swap(*it, executor->mergeGroups.back());
executor->mergeGroups.pop_back();
releaseStates();
}
}
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