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package com.ibm.wala.demandpa.flowgraph;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import com.ibm.wala.cfg.ControlFlowGraph;
import com.ibm.wala.cfg.IBasicBlock;
import com.ibm.wala.classLoader.CallSiteReference;
import com.ibm.wala.demandpa.util.MemoryAccessMap;
import com.ibm.wala.ipa.callgraph.CGNode;
import com.ibm.wala.ipa.callgraph.CallGraph;
import com.ibm.wala.ipa.callgraph.propagation.HeapModel;
import com.ibm.wala.ipa.callgraph.propagation.LocalPointerKey;
import com.ibm.wala.ipa.callgraph.propagation.PointerKey;
import com.ibm.wala.ipa.callgraph.propagation.ReturnValueKey;
import com.ibm.wala.ipa.callgraph.propagation.SSAPropagationCallGraphBuilder;
import com.ibm.wala.ipa.callgraph.propagation.cfa.CallerSiteContext;
import com.ibm.wala.ipa.cha.IClassHierarchy;
import com.ibm.wala.ssa.DefUse;
import com.ibm.wala.ssa.IR;
import com.ibm.wala.ssa.ISSABasicBlock;
import com.ibm.wala.ssa.SSAAbstractInvokeInstruction;
import com.ibm.wala.ssa.SSAInstruction;
import com.ibm.wala.ssa.SSAInvokeInstruction;
import com.ibm.wala.ssa.SSAPhiInstruction;
import com.ibm.wala.util.collections.EmptyIterator;
import com.ibm.wala.util.collections.HashMapFactory;
import com.ibm.wala.util.collections.HashSetFactory;
import com.ibm.wala.util.intset.BitVectorIntSet;
import com.ibm.wala.util.ref.ReferenceCleanser;
/**
* A graph representing program flow, constructed method-by-method on demand
*/
public abstract class AbstractDemandFlowGraph extends AbstractFlowGraph {
private final static boolean DEBUG = false;
/**
* Counter for wiping soft caches
*/
private static int wipeCount = 0;
/**
* node numbers of CGNodes we have already visited
*/
final BitVectorIntSet cgNodesVisited = new BitVectorIntSet();
/*
* @see com.ibm.wala.demandpa.flowgraph.IFlowGraph#addSubgraphForNode(com.ibm.wala.ipa.callgraph.CGNode)
*/
@Override
public void addSubgraphForNode(CGNode node) throws IllegalArgumentException {
if (node == null) {
throw new IllegalArgumentException("node == null");
}
IR ir = node.getIR();
if (ir == null) {
throw new IllegalArgumentException("no ir for node " + node);
}
int n = cg.getNumber(node);
if (!cgNodesVisited.contains(n)) {
cgNodesVisited.add(n);
unconditionallyAddConstraintsFromNode(node, ir);
addNodesForInvocations(node, ir);
addNodesForParameters(node, ir);
}
}
/*
* @see com.ibm.wala.demandpa.flowgraph.IFlowGraph#hasSubgraphForNode(com.ibm.wala.ipa.callgraph.CGNode)
*/
@Override
public boolean hasSubgraphForNode(CGNode node) {
return cgNodesVisited.contains(cg.getNumber(node));
}
/*
* @see com.ibm.wala.demandpa.flowgraph.IFlowGraph#getParamSuccs(com.ibm.wala.ipa.callgraph.propagation.LocalPointerKey)
*/
public Iterator<PointerKeyAndCallSite> getParamSuccs(LocalPointerKey pk) {
// TODO cache this result
// TODO take some cgnode as parameter if we have calling context?
CGNode cgNode = params.get(pk);
if (cgNode == null) {
return EmptyIterator.instance();
}
int paramPos = pk.getValueNumber() - 1;
ArrayList<PointerKeyAndCallSite> paramSuccs = new ArrayList<PointerKeyAndCallSite>();
// iterate over callers
for (CGNode caller : cg) {
// TODO optimization: we don't need to add the graph if null is passed
// as the argument
addSubgraphForNode(caller);
IR ir = caller.getIR();
for (Iterator<CallSiteReference> iterator = ir.iterateCallSites(); iterator.hasNext();) {
CallSiteReference call = iterator.next();
if (cg.getPossibleTargets(caller, call).contains(cgNode)) {
SSAAbstractInvokeInstruction[] callInstrs = ir.getCalls(call);
for (int i = 0; i < callInstrs.length; i++) {
SSAAbstractInvokeInstruction callInstr = callInstrs[i];
PointerKey actualPk = heapModel.getPointerKeyForLocal(caller, callInstr.getUse(paramPos));
assert containsNode(actualPk);
assert containsNode(pk);
paramSuccs.add(new PointerKeyAndCallSite(actualPk, call));
}
}
}
}
return paramSuccs.iterator();
}
/*
* @see com.ibm.wala.demandpa.flowgraph.IFlowGraph#getParamPreds(com.ibm.wala.ipa.callgraph.propagation.LocalPointerKey)
*/
public Iterator<PointerKeyAndCallSite> getParamPreds(LocalPointerKey pk) {
// TODO
Set<SSAAbstractInvokeInstruction> instrs = callParams.get(pk);
if (instrs == null) {
return EmptyIterator.instance();
}
ArrayList<PointerKeyAndCallSite> paramPreds = new ArrayList<PointerKeyAndCallSite>();
for (SSAAbstractInvokeInstruction callInstr : instrs) {
for (int i = 0; i < callInstr.getNumberOfUses(); i++) {
if (pk.getValueNumber() != callInstr.getUse(i))
continue;
CallSiteReference callSiteRef = callInstr.getCallSite();
// get call targets
Collection<CGNode> possibleCallees = cg.getPossibleTargets(pk.getNode(), callSiteRef);
// construct graph for each target
for (CGNode callee : possibleCallees) {
addSubgraphForNode(callee);
// TODO test this!!!
// TODO test passing null as an argument
PointerKey paramVal = heapModel.getPointerKeyForLocal(callee, i + 1);
assert containsNode(paramVal);
paramPreds.add(new PointerKeyAndCallSite(paramVal, callSiteRef));
}
}
}
return paramPreds.iterator();
}
/*
* @see com.ibm.wala.demandpa.flowgraph.IFlowGraph#getReturnSuccs(com.ibm.wala.ipa.callgraph.propagation.LocalPointerKey)
*/
public Iterator<PointerKeyAndCallSite> getReturnSuccs(LocalPointerKey pk) {
SSAAbstractInvokeInstruction callInstr = callDefs.get(pk);
if (callInstr == null)
return EmptyIterator.instance();
ArrayList<PointerKeyAndCallSite> returnSuccs = new ArrayList<PointerKeyAndCallSite>();
boolean isExceptional = pk.getValueNumber() == callInstr.getException();
CallSiteReference callSiteRef = callInstr.getCallSite();
// get call targets
Collection<CGNode> possibleCallees = cg.getPossibleTargets(pk.getNode(), callSiteRef);
// construct graph for each target
for (CGNode callee : possibleCallees) {
addSubgraphForNode(callee);
PointerKey retVal = isExceptional ? heapModel.getPointerKeyForExceptionalReturnValue(callee) : heapModel
.getPointerKeyForReturnValue(callee);
assert containsNode(retVal);
returnSuccs.add(new PointerKeyAndCallSite(retVal, callSiteRef));
}
return returnSuccs.iterator();
}
/*
* @see com.ibm.wala.demandpa.flowgraph.IFlowGraph#getReturnPreds(com.ibm.wala.ipa.callgraph.propagation.LocalPointerKey)
*/
public Iterator<PointerKeyAndCallSite> getReturnPreds(LocalPointerKey pk) {
CGNode cgNode = returns.get(pk);
if (cgNode == null) {
return EmptyIterator.instance();
}
boolean isExceptional = pk == heapModel.getPointerKeyForExceptionalReturnValue(cgNode);
ArrayList<PointerKeyAndCallSite> returnPreds = new ArrayList<PointerKeyAndCallSite>();
// iterate over callers
for (CGNode caller : cg) {
// TODO we don't need to add the graph if null is passed
// as the argument
addSubgraphForNode(caller);
IR ir = caller.getIR();
for (Iterator<CallSiteReference> iterator = ir.iterateCallSites(); iterator.hasNext();) {
CallSiteReference call = iterator.next();
if (cg.getPossibleTargets(caller, call).contains(cgNode)) {
SSAAbstractInvokeInstruction[] callInstrs = ir.getCalls(call);
for (int i = 0; i < callInstrs.length; i++) {
SSAAbstractInvokeInstruction callInstr = callInstrs[i];
PointerKey returnPk = heapModel.getPointerKeyForLocal(caller, isExceptional ? callInstr.getException() : callInstr
.getDef());
assert containsNode(returnPk);
assert containsNode(pk);
returnPreds.add(new PointerKeyAndCallSite(returnPk, call));
}
}
}
}
return returnPreds.iterator();
}
protected abstract void addNodesForParameters(CGNode node, IR ir);
protected void unconditionallyAddConstraintsFromNode(CGNode node, IR ir) {
if (DEBUG) {
System.err.println(("Adding constraints for CGNode " + node));
}
if (SSAPropagationCallGraphBuilder.PERIODIC_WIPE_SOFT_CACHES) {
wipeCount++;
if (wipeCount >= SSAPropagationCallGraphBuilder.WIPE_SOFT_CACHE_INTERVAL) {
wipeCount = 0;
ReferenceCleanser.clearSoftCaches();
}
}
debugPrintIR(ir);
if (ir == null) {
return;
}
DefUse du = node.getDU();
addNodeInstructionConstraints(node, ir, du);
addNodePassthruExceptionConstraints(node, ir);
addNodeConstantConstraints(node, ir);
}
/**
* Add pointer flow constraints based on instructions in a given node
*/
protected void addNodeInstructionConstraints(CGNode node, IR ir, DefUse du) {
FlowStatementVisitor v = makeVisitor(node);
ControlFlowGraph<SSAInstruction, ISSABasicBlock> cfg = ir.getControlFlowGraph();
for (ISSABasicBlock b : cfg) {
addBlockInstructionConstraints(node, cfg, b, v);
}
}
/**
* Add constraints for a particular basic block.
*/
protected void addBlockInstructionConstraints(CGNode node, ControlFlowGraph<SSAInstruction, ISSABasicBlock> cfg,
ISSABasicBlock b, FlowStatementVisitor v) {
v.setBasicBlock(b);
// visit each instruction in the basic block.
for (Iterator<SSAInstruction> it = b.iterator(); it.hasNext();) {
SSAInstruction s = it.next();
if (s != null) {
s.visit(v);
}
}
addPhiConstraints(node, cfg, b);
}
private void addPhiConstraints(CGNode node, ControlFlowGraph<SSAInstruction, ISSABasicBlock> cfg, ISSABasicBlock b) {
// visit each phi instruction in each successor block
for (Iterator<? extends IBasicBlock> iter = cfg.getSuccNodes(b); iter.hasNext();) {
ISSABasicBlock sb = (ISSABasicBlock) iter.next();
if (sb.isExitBlock()) {
// an optimization based on invariant that exit blocks should
// have no
// phis.
continue;
}
int n = 0;
// set n to be whichPred(this, sb);
for (Iterator<? extends IBasicBlock> back = cfg.getPredNodes(sb); back.hasNext(); n++) {
if (back.next() == b) {
break;
}
}
assert n < cfg.getPredNodeCount(sb);
for (Iterator<SSAPhiInstruction> phis = sb.iteratePhis(); phis.hasNext();) {
// Assertions.UNREACHABLE();
SSAPhiInstruction phi = phis.next();
if (phi == null) {
continue;
}
PointerKey def = heapModel.getPointerKeyForLocal(node, phi.getDef());
if (phi.getUse(n) > 0) {
PointerKey use = heapModel.getPointerKeyForLocal(node, phi.getUse(n));
addNode(def);
addNode(use);
addEdge(def, use, AssignLabel.noFilter());
}
// }
// }
}
}
}
protected abstract FlowStatementVisitor makeVisitor(CGNode node);
private void debugPrintIR(IR ir) {
if (DEBUG) {
if (ir == null) {
System.err.println("\n No statements\n");
} else {
try {
System.err.println(ir.toString());
} catch (Error e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
final Map<CGNode, Set<CallerSiteContext>> callerCache = HashMapFactory.make();
@Override
public Set<CallerSiteContext> getPotentialCallers(PointerKey formalPk) {
CGNode callee = null;
if (formalPk instanceof LocalPointerKey) {
callee = ((LocalPointerKey) formalPk).getNode();
} else if (formalPk instanceof ReturnValueKey) {
callee = ((ReturnValueKey) formalPk).getNode();
} else {
throw new IllegalArgumentException("formalPk must represent a local");
}
Set<CallerSiteContext> ret = callerCache.get(callee);
if (ret == null) {
ret = HashSetFactory.make();
for (Iterator<? extends CGNode> predNodes = cg.getPredNodes(callee); predNodes.hasNext();) {
CGNode caller = predNodes.next();
for (Iterator<CallSiteReference> iterator = cg.getPossibleSites(caller, callee); iterator.hasNext();) {
CallSiteReference call = iterator.next();
ret.add(new CallerSiteContext(caller, call));
}
}
callerCache.put(callee, ret);
}
return ret;
}
@Override
public Set<CGNode> getPossibleTargets(CGNode node, CallSiteReference site, LocalPointerKey actualPk) {
return cg.getPossibleTargets(node, site);
}
protected interface FlowStatementVisitor extends SSAInstruction.IVisitor {
void setBasicBlock(ISSABasicBlock b);
}
public AbstractDemandFlowGraph(final CallGraph cg, final HeapModel heapModel, final MemoryAccessMap mam, final IClassHierarchy cha) {
super(mam, heapModel, cha, cg);
}
}