/* Soot - a J*va Optimization Framework
* Copyright (C) 1997-1999 Raja Vallee-Rai
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
* Modified by the Sable Research Group and others 1997-1999.
* See the 'credits' file distributed with Soot for the complete list of
* contributors. (Soot is distributed at http://www.sable.mcgill.ca/soot)
*/
package soot.toolkits.scalar;
import soot.options.*;
import soot.*;
import soot.toolkits.graph.*;
import soot.util.*;
import java.util.*;
/**
* A BodyTransformer that attemps to indentify and separate uses of a local
* varible that are independent of each other. Conceptually the inverse transform
* with respect to the LocalPacker transform.
*
* For example the code:
*
* for(int i; i < k; i++);
* for(int i; i < k; i++);
*
* would be transformed into:
* for(int i; i < k; i++);
* for(int j; j < k; j++);
*
*
* @see BodyTransformer
* @see LocalPacker
* @see Body
*/
public class LocalSplitter extends BodyTransformer
{
public LocalSplitter( Singletons.Global g ) {}
public static LocalSplitter v() { return G.v().soot_toolkits_scalar_LocalSplitter(); }
protected void internalTransform(Body body, String phaseName, Map options)
{
Chain units = body.getUnits();
List<List> webs = new ArrayList<List>();
if(Options.v().verbose())
G.v().out.println("[" + body.getMethod().getName() + "] Splitting locals...");
Map boxToSet = new HashMap(units.size() * 2 + 1, 0.7f);
if(Options.v().time())
Timers.v().splitPhase1Timer.start();
// Go through the definitions, building the webs
{
ExceptionalUnitGraph graph = new ExceptionalUnitGraph(body);
LocalDefs localDefs;
localDefs = new SmartLocalDefs(graph, new SimpleLiveLocals(graph));
LocalUses localUses = new SimpleLocalUses(graph, localDefs);
if(Options.v().time())
Timers.v().splitPhase1Timer.end();
if(Options.v().time())
Timers.v().splitPhase2Timer.start();
Set<ValueBox> markedBoxes = new HashSet<ValueBox>();
Map<ValueBox, Unit> boxToUnit = new HashMap<ValueBox, Unit>(units.size() * 2 + 1, 0.7f);
Iterator codeIt = units.iterator();
while(codeIt.hasNext())
{
Unit s = (Unit) codeIt.next();
if (s.getDefBoxes().size() > 1)
throw new RuntimeException("stmt with more than 1 defbox!");
if (s.getDefBoxes().size() < 1)
continue;
ValueBox loBox = (ValueBox)s.getDefBoxes().get(0);
Value lo = loBox.getValue();
if(lo instanceof Local && !markedBoxes.contains(loBox))
{
LinkedList<Unit> defsToVisit = new LinkedList<Unit>();
LinkedList<ValueBox> boxesToVisit = new LinkedList<ValueBox>();
List web = new ArrayList();
webs.add(web);
defsToVisit.add(s);
markedBoxes.add(loBox);
boxToUnit.put(loBox, s); // RoboVM note: Added
while(!boxesToVisit.isEmpty() || !defsToVisit.isEmpty())
{
if(!defsToVisit.isEmpty())
{
Unit d = defsToVisit.removeFirst();
web.add(d.getDefBoxes().get(0));
// Add all the uses of this definition to the queue
{
List uses = localUses.getUsesOf(d);
Iterator useIt = uses.iterator();
while(useIt.hasNext())
{
UnitValueBoxPair use = (UnitValueBoxPair) useIt.next();
if(!markedBoxes.contains(use.valueBox))
{
markedBoxes.add(use.valueBox);
boxesToVisit.addLast(use.valueBox);
boxToUnit.put(use.valueBox, use.unit);
}
}
}
}
else {
ValueBox box = boxesToVisit.removeFirst();
web.add(box);
// Add all the definitions of this use to the queue.
{
List<Unit> defs = localDefs.getDefsOfAt((Local) box.getValue(),
boxToUnit.get(box));
Iterator<Unit> defIt = defs.iterator();
while(defIt.hasNext())
{
Unit u = defIt.next();
Iterator defBoxesIter = u.getDefBoxes().iterator();
ValueBox b;
for (; defBoxesIter.hasNext(); )
{
b = (ValueBox)defBoxesIter.next();
if(!markedBoxes.contains(b))
{
markedBoxes.add(b);
defsToVisit.addLast(u);
boxToUnit.put(b, u); // RoboVM note: Added
}
}
}
}
}
}
}
}
// RoboVM note: Added in RoboVM to merge webs referring to the same
// local variable in the original source code. This prevents
// splitting of such Locals.
webs = mergeWebs(body, webs, boxToUnit, localUses);
}
// Assign locals appropriately.
{
Map<Local, Integer> localToUseCount = new HashMap<Local, Integer>(body.getLocalCount() * 2 + 1, 0.7f);
Iterator<List> webIt = webs.iterator();
while(webIt.hasNext())
{
List web = webIt.next();
ValueBox rep = (ValueBox) web.get(0);
Local desiredLocal = (Local) rep.getValue();
if(!localToUseCount.containsKey(desiredLocal))
{
// claim this local for this set
localToUseCount.put(desiredLocal, new Integer(1));
}
else {
// generate a new local
int useCount = localToUseCount.get(desiredLocal).intValue() + 1;
localToUseCount.put(desiredLocal, new Integer(useCount));
Local local = (Local) desiredLocal.clone();
local.setName(desiredLocal.getName() + "#" + useCount);
body.getLocals().add(local);
// Change all boxes to point to this new local
{
Iterator j = web.iterator();
while(j.hasNext())
{
ValueBox box = (ValueBox) j.next();
box.setValue(local);
}
}
}
}
}
if(Options.v().time())
Timers.v().splitPhase2Timer.end();
}
/**
* Merges webs referring to the same local variable in the original source
* code. This prevents splitting of Locals which correspond to local
* variables. Splitting would otherwise interfere with debug info
* generation.
* RoboVM note: Added in RoboVM.
*/
private List<List> mergeWebs(Body body, List<List> webs, Map<ValueBox, Unit> boxToUnit, LocalUses localUses) {
List<List> result = new ArrayList<>();
LinkedList<List> websCopy = new LinkedList<>(webs);
while (!websCopy.isEmpty()) {
// Compare the local variable of the first web with the rest. If two
// webs refer to the same local variable we merge them into one.
List<ValueBox> web1 = websCopy.removeFirst();
Local local1 = (Local) web1.get(0).getValue();
if (local1.getIndex() == -1) {
// The Local doesn't refer to a local variable in the bytecode but rather a stack slot.
result.add(web1);
continue;
}
List<ValueBox> mergedWeb = new ArrayList<>(web1);
Set<LocalVariable> lvs1 = findLocalVariables(web1, local1, null, boxToUnit, body);
String expectedType = lvs1.isEmpty()? null: lvs1.iterator().next().getDescriptor();
for (Iterator<List> it2 = websCopy.iterator(); it2.hasNext();) {
List<ValueBox> web2 = it2.next();
Local local2 = (Local) web2.get(0).getValue();
if (!local1.equals(local2)) {
continue;
}
Set<LocalVariable> lvs2 = findLocalVariables(web2, local2, expectedType, boxToUnit, body);
if (!lvs1.isEmpty() && lvs1.equals(lvs2)) {
mergedWeb.addAll(web2);
it2.remove();
}
}
result.add(mergedWeb);
}
return result;
}
/**
* RoboVM note: Added in RoboVM.
*/
private Set<LocalVariable> findLocalVariables(List<ValueBox> web, Local local, String expectedTypeDescriptor, Map<ValueBox, Unit> boxToUnit, Body body) {
Set<LocalVariable> lvs = new HashSet<>();
if (local.getIndex() != -1) {
boolean incompatibleType = false;
String firstType = null;
for (ValueBox box : web) {
LocalVariable lv = findLocalVariable(body, local.getIndex(), boxToUnit.get(box));
if (lv != null) {
lvs.add(lv);
// does this local have a compatible type with the other web?
// if not we'll return an empty set and the webs don't get merged
if (expectedTypeDescriptor != null && lv.getDescriptor().equals(expectedTypeDescriptor)) {
incompatibleType = true;
}
// are the types of this web's locals consistent?
// if not we'll return an empty set and the
// webs don't get merged, see #920
if (firstType == null) {
firstType = lv.getDescriptor();
} else if (!firstType.equals(lv.getDescriptor())) {
incompatibleType = true;
}
}
}
// if we encountered incompatible types, either
// between the webs or inside the web, we
// return an empty set so the webs don't get
// merged
if (incompatibleType) {
lvs.clear();
return lvs;
}
if (lvs.size() > 1) {
// Verify that all LocalVariables refer to a variable with the same name.
String name = null;
for (LocalVariable lv : lvs) {
if (name == null) {
name = lv.getName();
} else {
if (!lv.getName().equals(name)) {
throw new IllegalStateException("Found LocalVariables do "
+ "not refer to a variable with the same name: " + lvs);
}
}
}
}
}
return lvs;
}
/**
* Finds a {@link LocalVariable} with the specified local variable index
* at the specified {@link Unit} or {@code null} if none was found.
* RoboVM note: Added in RoboVM.
*/
private LocalVariable findLocalVariable(Body body, int index, Unit unit) {
PatchingChain<Unit> units = body.getUnits();
for (LocalVariable lv : body.getLocalVariables()) {
if (lv.getIndex() == index) {
if ((unit == lv.getStartUnit() || units.follows(unit, lv.getStartUnit()))
&& (lv.getEndUnit() == null || units.follows(lv.getEndUnit(), unit))) {
return lv;
}
}
}
return null;
}
}