public FaintVariableAnalysis(Body body) {
Chain<Local> locals = body.getLocals();
allVariables = new CollectionFlowUniverse<Local>(locals);
universalSet = new ArrayPackedSet(allVariables);
for (Local l : locals) universalSet.add(l);
useSetMap = new HashMap<Unit, BoundedFlowSet>();
defSetMap = new HashMap<Unit, BoundedFlowSet>();
UnitGraph graph = new BriefUnitGraph(body);
for (Unit u : graph) {
BoundedFlowSet defSet = new ArrayPackedSet(allVariables);
BoundedFlowSet useSet = new ArrayPackedSet(allVariables);
for (ValueBox v : u.getDefBoxes()) {
// Only do this for locals. We're not going to even try to handle anything
// other than locals.
if (v.getValue() instanceof Local) {
defSet.add(v.getValue());
}
}
for (ValueBox v : u.getUseBoxes()) {
// Only do this for locals. We're not going to even try to handle anything
// other than locals.
if (v.getValue() instanceof Local) {
useSet.add(v.getValue());
}
}
defSetMap.put(u, defSet);
useSetMap.put(u, useSet);
}
}
private static boolean internalAggregate(
StmtBody body, Map<ValueBox, Zone> boxToZone, boolean onlyStackVars) {
LocalUses localUses;
LocalDefs localDefs;
ExceptionalUnitGraph graph;
boolean hadAggregation = false;
Chain<Unit> units = body.getUnits();
graph = new ExceptionalUnitGraph(body);
localDefs = new SmartLocalDefs(graph, new SimpleLiveLocals(graph));
localUses = new SimpleLocalUses(graph, localDefs);
List<Unit> unitList = new PseudoTopologicalOrderer<Unit>().newList(graph, false);
for (Unit u : unitList) {
if (!(u instanceof AssignStmt)) continue;
AssignStmt s = (AssignStmt) u;
Value lhs = s.getLeftOp();
if (!(lhs instanceof Local)) continue;
Local lhsLocal = (Local) lhs;
if (onlyStackVars && !lhsLocal.getName().startsWith("$")) continue;
List<UnitValueBoxPair> lu = localUses.getUsesOf(s);
if (lu.size() != 1) continue;
UnitValueBoxPair usepair = lu.get(0);
Unit use = usepair.unit;
ValueBox useBox = usepair.valueBox;
List<Unit> ld = localDefs.getDefsOfAt(lhsLocal, use);
if (ld.size() != 1) continue;
// Check to make sure aggregation pair in the same zone
if (boxToZone.get(s.getRightOpBox()) != boxToZone.get(usepair.valueBox)) {
continue;
}
/* we need to check the path between def and use */
/* to see if there are any intervening re-defs of RHS */
/* in fact, we should check that this path is unique. */
/* if the RHS uses only locals, then we know what
to do; if RHS has a method invocation f(a, b,
c) or field access, we must ban field writes, other method
calls and (as usual) writes to a, b, c. */
boolean cantAggr = false;
boolean propagatingInvokeExpr = false;
boolean propagatingFieldRef = false;
boolean propagatingArrayRef = false;
ArrayList<FieldRef> fieldRefList = new ArrayList<FieldRef>();
LinkedList<Value> localsUsed = new LinkedList<Value>();
for (ValueBox vb : s.getUseBoxes()) {
Value v = vb.getValue();
if (v instanceof Local) localsUsed.add(v);
else if (v instanceof InvokeExpr) propagatingInvokeExpr = true;
else if (v instanceof ArrayRef) propagatingArrayRef = true;
else if (v instanceof FieldRef) {
propagatingFieldRef = true;
fieldRefList.add((FieldRef) v);
}
}
// look for a path from s to use in graph.
// only look in an extended basic block, though.
List<Unit> path = graph.getExtendedBasicBlockPathBetween(s, use);
if (path == null) continue;
Iterator<Unit> pathIt = path.iterator();
// skip s.
if (pathIt.hasNext()) pathIt.next();
while (pathIt.hasNext() && !cantAggr) {
Stmt between = (Stmt) (pathIt.next());
if (between != use) {
// Check for killing definitions
for (ValueBox vb : between.getDefBoxes()) {
Value v = vb.getValue();
if (localsUsed.contains(v)) {
cantAggr = true;
break;
}
if (propagatingInvokeExpr || propagatingFieldRef || propagatingArrayRef) {
if (v instanceof FieldRef) {
if (propagatingInvokeExpr) {
cantAggr = true;
break;
} else if (propagatingFieldRef) {
// Can't aggregate a field access if passing a definition of a field
// with the same name, because they might be aliased
for (FieldRef fieldRef : fieldRefList) {
if (((FieldRef) v).getField() == fieldRef.getField()) {
cantAggr = true;
break;
}
}
}
} else if (v instanceof ArrayRef) {
if (propagatingInvokeExpr) {
// Cannot aggregate an invoke expr past an array write
cantAggr = true;
break;
} else if (propagatingArrayRef) {
// cannot aggregate an array read past a write
// this is somewhat conservative
// (if types differ they may not be aliased)
cantAggr = true;
break;
}
}
}
}
// Make sure not propagating past a {enter,exit}Monitor
if (propagatingInvokeExpr && between instanceof MonitorStmt) cantAggr = true;
}
// Check for intervening side effects due to method calls
if (propagatingInvokeExpr || propagatingFieldRef || propagatingArrayRef) {
for (final ValueBox box : between.getUseBoxes()) {
if (between == use && box == useBox) {
// Reached use point, stop looking for
// side effects
break;
}
Value v = box.getValue();
if (v instanceof InvokeExpr
|| (propagatingInvokeExpr && (v instanceof FieldRef || v instanceof ArrayRef))) {
cantAggr = true;
break;
}
}
}
}
// we give up: can't aggregate.
if (cantAggr) {
continue;
}
/* assuming that the d-u chains are correct, */
/* we need not check the actual contents of ld */
Value aggregatee = s.getRightOp();
if (usepair.valueBox.canContainValue(aggregatee)) {
boolean wasSimpleCopy = isSimpleCopy(usepair.unit);
usepair.valueBox.setValue(aggregatee);
units.remove(s);
hadAggregation = true;
// clean up the tags. If s was not a simple copy, the new statement should get
// the tags of s.
// OK, this fix was wrong. The condition should not be
// "If s was not a simple copy", but rather "If usepair.unit
// was a simple copy". This way, when there's a load of a constant
// followed by an invoke, the invoke gets the tags.
if (wasSimpleCopy) {
// usepair.unit.removeAllTags();
usepair.unit.addAllTagsOf(s);
}
} else {
/*
if(Options.v().verbose())
{
G.v().out.println("[debug] failed aggregation");
G.v().out.println("[debug] tried to put "+aggregatee+
" into "+usepair.stmt +
": in particular, "+usepair.valueBox);
G.v().out.println("[debug] aggregatee instanceof Expr: "
+(aggregatee instanceof Expr));
}*/
}
}
return hadAggregation;
}