@Override
public void visit(VariableExpr expr) {
int index = expr.getIndex();
resultExpr = expr;
if (readFrequencies[index] != 1 || preservedVars[index]) {
return;
}
if (resultSequence.isEmpty()) {
return;
}
Statement last = resultSequence.get(resultSequence.size() - 1);
if (!(last instanceof AssignmentStatement)) {
return;
}
AssignmentStatement assignment = (AssignmentStatement) last;
if (assignment.isAsync()) {
return;
}
if (!(assignment.getLeftValue() instanceof VariableExpr)) {
return;
}
VariableExpr var = (VariableExpr) assignment.getLeftValue();
if (var.getLocation() != null
&& assignment.getLocation() != null
&& !assignment.getLocation().equals(var.getLocation())) {
return;
}
if (var.getIndex() == index) {
resultSequence.remove(resultSequence.size() - 1);
assignment.getRightValue().setLocation(assignment.getLocation());
assignment.getRightValue().acceptVisitor(this);
}
}
@Override
public void visit(SequentialStatement statement) {
List<Statement> statements = processSequence(statement.getSequence());
if (statements.size() == 1) {
resultStmt = statements.get(0);
} else {
statement.getSequence().clear();
statement.getSequence().addAll(statements);
resultStmt = statement;
}
}
@Override
public void visit(MonitorExitInstruction insn) {
MonitorExitStatement stmt = new MonitorExitStatement();
stmt.setLocation(currentLocation);
stmt.setObjectRef(Expr.var(insn.getObjectRef().getIndex()));
statements.add(stmt);
}
@Override
public void visit(JumpInstruction insn) {
Statement stmt = generateJumpStatement(insn.getTarget());
if (stmt != null) {
statements.add(stmt);
}
}
@Override
public void visit(InvokeInstruction insn) {
Expr[] exprArgs = new Expr[insn.getMethod().getParameterTypes().length];
for (int i = 0; i < insn.getArguments().size(); ++i) {
exprArgs[i] = Expr.var(insn.getArguments().get(i).getIndex());
}
InvocationExpr invocationExpr;
if (insn.getInstance() != null) {
if (insn.getType() == InvocationType.VIRTUAL) {
invocationExpr =
Expr.invoke(insn.getMethod(), Expr.var(insn.getInstance().getIndex()), exprArgs);
} else {
invocationExpr =
Expr.invokeSpecial(insn.getMethod(), Expr.var(insn.getInstance().getIndex()), exprArgs);
}
} else {
invocationExpr = Expr.invokeStatic(insn.getMethod(), exprArgs);
}
AssignmentStatement stmt;
if (insn.getReceiver() != null) {
stmt = Statement.assign(Expr.var(insn.getReceiver().getIndex()), invocationExpr);
stmt.getDebugNames().addAll(insn.getReceiver().getDebugNames());
} else {
stmt = Statement.assign(null, invocationExpr);
}
stmt.setLocation(currentLocation);
stmt.setAsync(async);
async = false;
statements.add(stmt);
}
@Override
public void visit(RaiseInstruction insn) {
ThrowStatement stmt = new ThrowStatement();
stmt.setLocation(currentLocation);
stmt.setException(Expr.var(insn.getException().getIndex()));
statements.add(stmt);
}
@Override
public void visit(GetFieldInstruction insn) {
if (insn.getInstance() != null) {
AssignmentStatement stmt =
Statement.assign(
Expr.var(insn.getReceiver().getIndex()),
Expr.qualify(Expr.var(insn.getInstance().getIndex()), insn.getField()));
stmt.setLocation(currentLocation);
statements.add(stmt);
} else {
Expr fieldExpr = Expr.qualify(null, insn.getField());
AssignmentStatement stmt =
Statement.assign(Expr.var(insn.getReceiver().getIndex()), fieldExpr);
stmt.setLocation(currentLocation);
statements.add(stmt);
}
}
@Override
public void visit(ExitInstruction insn) {
ReturnStatement stmt =
Statement.exitFunction(
insn.getValueToReturn() != null ? Expr.var(insn.getValueToReturn().getIndex()) : null);
stmt.setLocation(currentLocation);
statements.add(stmt);
}
private void branch(Expr condition, BasicBlock consequentBlock, BasicBlock alternativeBlock) {
Statement consequent = generateJumpStatement(consequentBlock);
Statement alternative = generateJumpStatement(alternativeBlock);
statements.add(
Statement.cond(
condition,
consequent != null ? Arrays.asList(consequent) : Collections.emptyList(),
alternative != null ? Arrays.asList(alternative) : Collections.emptyList()));
}
@Override
public void visit(AssignInstruction insn) {
AssignmentStatement stmt =
Statement.assign(
Expr.var(insn.getReceiver().getIndex()), Expr.var(insn.getAssignee().getIndex()));
stmt.getDebugNames().addAll(insn.getReceiver().getDebugNames());
stmt.setLocation(currentLocation);
statements.add(stmt);
}
private List<Statement> processSequence(List<Statement> statements) {
List<Statement> backup = resultSequence;
resultSequence = new ArrayList<>();
processSequenceImpl(statements);
wieldTryCatch(resultSequence);
List<Statement> result =
resultSequence.stream().filter(part -> part != null).collect(Collectors.toList());
resultSequence = backup;
return result;
}
@Override
public void visit(PutElementInstruction insn) {
AssignmentStatement stmt =
Statement.assign(
Expr.subscript(
Expr.var(insn.getArray().getIndex()), Expr.var(insn.getIndex().getIndex())),
Expr.var(insn.getValue().getIndex()));
stmt.setLocation(currentLocation);
statements.add(stmt);
}
@Override
public void visit(PutFieldInstruction insn) {
Expr right = Expr.var(insn.getValue().getIndex());
Expr left;
if (insn.getInstance() != null) {
left = Expr.qualify(Expr.var(insn.getInstance().getIndex()), insn.getField());
} else {
left = Expr.qualify(null, insn.getField());
}
AssignmentStatement stmt = Statement.assign(left, right);
stmt.setLocation(currentLocation);
statements.add(stmt);
}
private boolean tryApplyConstructor(InvocationExpr expr) {
if (!expr.getMethod().getName().equals("<init>")) {
return false;
}
if (resultSequence == null || resultSequence.isEmpty()) {
return false;
}
Statement last = resultSequence.get(resultSequence.size() - 1);
if (!(last instanceof AssignmentStatement)) {
return false;
}
AssignmentStatement assignment = (AssignmentStatement) last;
if (!(assignment.getLeftValue() instanceof VariableExpr)) {
return false;
}
VariableExpr var = (VariableExpr) assignment.getLeftValue();
if (!(expr.getArguments().get(0) instanceof VariableExpr)) {
return false;
}
VariableExpr target = (VariableExpr) expr.getArguments().get(0);
if (target.getIndex() != var.getIndex()) {
return false;
}
if (!(assignment.getRightValue() instanceof NewExpr)) {
return false;
}
NewExpr constructed = (NewExpr) assignment.getRightValue();
if (!constructed.getConstructedClass().equals(expr.getMethod().getClassName())) {
return false;
}
Expr[] args = expr.getArguments().toArray(new Expr[0]);
args = Arrays.copyOfRange(args, 1, args.length);
InvocationExpr constructrExpr = Expr.constructObject(expr.getMethod(), args);
constructrExpr.setLocation(expr.getLocation());
assignment.setRightValue(constructrExpr);
readFrequencies[var.getIndex()]--;
return true;
}
@Override
public void visit(WhileStatement statement) {
if (statement.getBody().size() == 1 && statement.getBody().get(0) instanceof WhileStatement) {
WhileStatement innerLoop = (WhileStatement) statement.getBody().get(0);
BreakToContinueReplacer replacer = new BreakToContinueReplacer(innerLoop, statement);
replacer.visitSequence(innerLoop.getBody());
statement.getBody().clear();
statement.getBody().addAll(innerLoop.getBody());
}
List<Statement> statements = processSequence(statement.getBody());
for (int i = 0; i < statements.size(); ++i) {
if (statements.get(i) instanceof ContinueStatement) {
ContinueStatement continueStmt = (ContinueStatement) statements.get(i);
if (continueStmt.getTarget() == statement) {
statements.subList(i, statements.size()).clear();
break;
}
}
}
statement.getBody().clear();
statement.getBody().addAll(statements);
if (statement.getCondition() != null) {
List<Statement> sequenceBackup = resultSequence;
resultSequence = new ArrayList<>();
statement.getCondition().acceptVisitor(this);
statement.setCondition(resultExpr);
resultSequence = sequenceBackup;
}
while (true) {
if (!statement.getBody().isEmpty()
&& statement.getBody().get(0) instanceof ConditionalStatement) {
ConditionalStatement cond = (ConditionalStatement) statement.getBody().get(0);
if (cond.getConsequent().size() == 1
&& cond.getConsequent().get(0) instanceof BreakStatement) {
BreakStatement breakStmt = (BreakStatement) cond.getConsequent().get(0);
if (breakStmt.getTarget() == statement) {
statement.getBody().remove(0);
if (statement.getCondition() != null) {
Expr newCondition =
Expr.binary(
BinaryOperation.AND,
statement.getCondition(),
ExprOptimizer.invert(cond.getCondition()));
newCondition.setLocation(statement.getCondition().getLocation());
statement.setCondition(newCondition);
} else {
statement.setCondition(ExprOptimizer.invert(cond.getCondition()));
}
continue;
}
}
}
break;
}
resultStmt = statement;
}
private boolean briefStatementComparison(List<Statement> firstSeq, List<Statement> secondSeq) {
if (firstSeq.isEmpty() && secondSeq.isEmpty()) {
return true;
}
if (firstSeq.size() != 1 || secondSeq.size() != 1) {
return false;
}
Statement first = firstSeq.get(0);
Statement second = secondSeq.get(0);
if (first instanceof BreakStatement && second instanceof BreakStatement) {
BreakStatement firstBreak = (BreakStatement) first;
BreakStatement secondBreak = (BreakStatement) second;
return firstBreak.getTarget() == secondBreak.getTarget();
}
return false;
}
private void wieldTryCatch(List<Statement> statements) {
for (int i = 0; i < statements.size() - 1; ++i) {
if (statements.get(i) instanceof TryCatchStatement
&& statements.get(i + 1) instanceof TryCatchStatement) {
TryCatchStatement first = (TryCatchStatement) statements.get(i);
TryCatchStatement second = (TryCatchStatement) statements.get(i + 1);
if (Objects.equals(first.getExceptionType(), second.getExceptionType())
&& Objects.equals(first.getExceptionVariable(), second.getExceptionVariable())
&& briefStatementComparison(first.getHandler(), second.getHandler())) {
first.getProtectedBody().addAll(second.getProtectedBody());
statements.remove(i + 1);
wieldTryCatch(first.getProtectedBody());
--i;
}
}
}
}
private boolean processSequenceImpl(List<Statement> statements) {
for (Statement part : statements) {
if (part instanceof SequentialStatement) {
if (!processSequenceImpl(((SequentialStatement) part).getSequence())) {
return false;
}
continue;
}
part.acceptVisitor(this);
part = resultStmt;
if (part instanceof SequentialStatement) {
if (!processSequenceImpl(((SequentialStatement) part).getSequence())) {
return false;
}
continue;
}
resultSequence.add(part);
if (part instanceof BreakStatement) {
return false;
}
}
return true;
}
@Override
public void visit(SwitchInstruction insn) {
SwitchStatement stmt = new SwitchStatement();
stmt.setId("sblock" + (lastSwitchId++));
stmt.setValue(Expr.var(insn.getCondition().getIndex()));
Map<Integer, List<Integer>> switchMap = new HashMap<>();
for (int i = 0; i < insn.getEntries().size(); ++i) {
SwitchTableEntry entry = insn.getEntries().get(i);
List<Integer> conditions = switchMap.get(entry.getTarget().getIndex());
if (conditions == null) {
conditions = new ArrayList<>();
switchMap.put(entry.getTarget().getIndex(), conditions);
}
conditions.add(entry.getCondition());
}
List<Integer> targets = new ArrayList<>(switchMap.keySet());
Collections.sort(targets);
for (int target : targets) {
SwitchClause clause = new SwitchClause();
List<Integer> conditionList = switchMap.get(target);
int[] conditions = new int[conditionList.size()];
for (int i = 0; i < conditionList.size(); ++i) {
conditions[i] = conditionList.get(i);
}
clause.setConditions(conditions);
Statement jumpStmt = generateJumpStatement(stmt, target);
if (jumpStmt != null) {
clause.getBody().add(jumpStmt);
}
stmt.getClauses().add(clause);
}
Statement breakStmt = generateJumpStatement(insn.getDefaultTarget());
if (breakStmt != null) {
stmt.getDefaultClause().add(breakStmt);
}
statements.add(stmt);
}
@Override
public void visit(ConditionalStatement statement) {
statement.getCondition().acceptVisitor(this);
statement.setCondition(resultExpr);
List<Statement> consequent = processSequence(statement.getConsequent());
List<Statement> alternative = processSequence(statement.getAlternative());
if (consequent.isEmpty()) {
consequent.addAll(alternative);
alternative.clear();
statement.setCondition(ExprOptimizer.invert(statement.getCondition()));
}
if (consequent.isEmpty()) {
resultStmt = Statement.empty();
return;
}
statement.getConsequent().clear();
statement.getConsequent().addAll(consequent);
statement.getAlternative().clear();
statement.getAlternative().addAll(alternative);
resultStmt = statement;
}
@Override
public void visit(InitClassInstruction insn) {
InitClassStatement stmt = Statement.initClass(insn.getClassName());
stmt.setLocation(currentLocation);
statements.add(stmt);
}
private void eliminateRedundantBreaks(List<Statement> statements, IdentifiedStatement exit) {
if (statements.isEmpty()) {
return;
}
Statement last = statements.get(statements.size() - 1);
if (last instanceof BreakStatement && exit != null) {
IdentifiedStatement target = ((BreakStatement) last).getTarget();
if (exit == target) {
statements.remove(statements.size() - 1);
}
}
if (statements.isEmpty()) {
return;
}
for (int i = 0; i < statements.size(); ++i) {
Statement stmt = statements.get(i);
if (stmt instanceof ConditionalStatement) {
ConditionalStatement cond = (ConditionalStatement) stmt;
check_conditional:
{
last =
cond.getConsequent().isEmpty()
? null
: cond.getConsequent().get(cond.getConsequent().size() - 1);
if (last instanceof BreakStatement) {
BreakStatement breakStmt = (BreakStatement) last;
if (exit != null && exit == breakStmt.getTarget()) {
cond.getConsequent().remove(cond.getConsequent().size() - 1);
List<Statement> remaining = statements.subList(i + 1, statements.size());
cond.getAlternative().addAll(remaining);
remaining.clear();
break check_conditional;
}
}
last =
cond.getAlternative().isEmpty()
? null
: cond.getAlternative().get(cond.getAlternative().size() - 1);
if (last instanceof BreakStatement) {
BreakStatement breakStmt = (BreakStatement) last;
if (exit != null && exit == breakStmt.getTarget()) {
cond.getAlternative().remove(cond.getAlternative().size() - 1);
List<Statement> remaining = statements.subList(i + 1, statements.size());
cond.getConsequent().addAll(remaining);
remaining.clear();
}
}
}
if (i == statements.size() - 1) {
eliminateRedundantBreaks(cond.getConsequent(), exit);
eliminateRedundantBreaks(cond.getAlternative(), exit);
}
normalizeConditional(cond);
if (cond.getConsequent().size() == 1
&& cond.getConsequent().get(0) instanceof ConditionalStatement) {
ConditionalStatement innerCond = (ConditionalStatement) cond.getConsequent().get(0);
if (innerCond.getAlternative().isEmpty()) {
if (cond.getAlternative().isEmpty()) {
cond.getConsequent().clear();
cond.getConsequent().addAll(innerCond.getConsequent());
cond.setCondition(
Expr.binary(
BinaryOperation.AND,
cond.getCondition(),
innerCond.getCondition(),
cond.getCondition().getLocation()));
--i;
} else if (cond.getAlternative().size() != 1
|| !(cond.getAlternative().get(0) instanceof ConditionalStatement)) {
cond.setCondition(ExprOptimizer.invert(cond.getCondition()));
cond.getConsequent().clear();
cond.getConsequent().addAll(cond.getAlternative());
cond.getAlternative().clear();
cond.getAlternative().add(innerCond);
--i;
}
}
}
} else if (stmt instanceof BlockStatement) {
BlockStatement nestedBlock = (BlockStatement) stmt;
eliminateRedundantBreaks(nestedBlock.getBody(), nestedBlock);
} else if (stmt instanceof WhileStatement) {
WhileStatement whileStmt = (WhileStatement) stmt;
eliminateRedundantBreaks(whileStmt.getBody(), null);
} else if (stmt instanceof SwitchStatement) {
SwitchStatement switchStmt = (SwitchStatement) stmt;
for (SwitchClause clause : switchStmt.getClauses()) {
eliminateRedundantBreaks(clause.getBody(), null);
}
eliminateRedundantBreaks(switchStmt.getDefaultClause(), null);
}
}
}
private void assign(Expr source, Variable target) {
AssignmentStatement stmt = Statement.assign(Expr.var(target.getIndex()), source);
stmt.setLocation(currentLocation);
stmt.getDebugNames().addAll(target.getDebugNames());
statements.add(stmt);
}
