private Set<CFGEdge> extractNonPostdominatingEdges(
DFAGraph reverseCFG, DFAGraph postDomTree, Procedure proc) {
if (PrintTools.getVerbosity() > 1)
System.out.println("[extractNonPostdominatingEdges]Proc: " + proc.getSymbolName());
Set<CFGEdge> retSet = new HashSet<CFGEdge>();
// extract all the edges from CFG
Set<CFGEdge> allEdgeList = new HashSet<CFGEdge>();
Iterator<DFANode> iter = reverseCFG.iterator();
while (iter.hasNext()) {
DFANode currentNode = iter.next();
Set<DFANode> predSet = currentNode.getPreds();
for (DFANode pred : predSet) {
// In the reversed cfg, pred is succ in CFG
allEdgeList.add(new CFGEdge(currentNode, pred));
}
}
List<DFANode> entryNodes = postDomTree.getEntryNodes();
if (entryNodes.size() != 1) {
throw new RuntimeException(
"Size of Entry node on PD Tree is not 1. Size: " + entryNodes.size());
}
DFANode entryNode = entryNodes.get(0);
// extract edge which head does not postdominate tail
// (head is not parent of tail on PostDomTree)
for (CFGEdge edge : allEdgeList) {
//
DFANode pdtTail = (DFANode) edge.tail.getData("pdtNode");
DFANode pdtHead = (DFANode) edge.head.getData("pdtNode");
Set<DFANode> predSet = pdtTail.getPreds();
boolean postDom = false;
while (predSet.size() != 0) {
if (predSet.size() > 1) {
throw new RuntimeException("The size of predecessor is expected to be less than 2");
}
DFANode pdtNode = predSet.iterator().next();
if (pdtNode.equals(pdtHead)) {
postDom = true;
break;
}
predSet = pdtNode.getPreds();
}
if (postDom == false) {
retSet.add(edge);
if (PrintTools.getVerbosity() > 1)
System.out.println(
"Found Edge: "
+ ((DFANode) edge.tail.getData("cfgNode")).getData("ir")
+ " --> "
+ ((DFANode) edge.head.getData("cfgNode")).getData("ir")
+ "("
+ ((DFANode) edge.head.getData("cfgNode")).getData("tag")
+ ")");
}
}
return retSet;
}
private void buildCDG() {
if (this.procSet == null) {
procSet = cfgMap.keySet();
}
for (Procedure proc : procSet) {
System.out.println(
"Building Control Dependence Graph for Proc: "
+ proc.getSymbolName()
+ ", time: "
+ (new Date()).toString());
CFGraph cfg = cfgMap.get(proc);
// reverse the control flow graph
DFAGraph reversedCFG = SlicingTools.reverseCFGraph(cfg);
// add additional start node for connecting multiple return node
// single return node works fine with this.
DFANode dummyEntryNode = new DFANode();
List<DFANode> entryList = reversedCFG.getEntryNodes();
reversedCFG.addNode(dummyEntryNode);
for (DFANode entry : entryList) {
dummyEntryNode.addSucc(entry);
reversedCFG.addEdge(dummyEntryNode, entry);
}
//
ArrayList<DFANode> nodeList = new ArrayList<DFANode>();
// extract dominator
BitSet[] dominator = SlicingTools.getDominators(reversedCFG, nodeList);
int nodeSize = nodeList.size();
DFANode[] nodeArray = new DFANode[nodeSize];
nodeList.toArray(nodeArray);
Set<Integer> entryIdxSet = SlicingTools.getEntryIdxSet(reversedCFG, nodeList);
List<DFANode> entryNodeList = reversedCFG.getEntryNodes();
// print dominator
// SlicingTools.printDominator(dominator, nodeArray, proc);
// extract immediate dominator
BitSet[] immediateDom =
SlicingTools.getImmediateDominator(dominator, entryIdxSet, entryNodeList, nodeArray);
// print immediate dominator
// SlicingTools.printDominator(immediateDom, nodeArray, proc);
// build Post Dominance Tree
if (PrintTools.getVerbosity() > 1)
System.out.println(
"############# build Post Dominace Tree (Graph) for "
+ proc.getSymbolName()
+ " ###########");
DFAGraph postDomTree =
SlicingTools.buildImmediateDominanceTree(reversedCFG, immediateDom, nodeArray, nodeList);
// print post dominance tree
// SlicingTools.printDominanceTree(postDomTree, proc);
// extract edges m --> n such that n does not postdominate(dominate in reversed) m
// CFGEdge's head and tail are on reversed cfg.
// can get PDTree node by getData("pdtNode")
Set<CFGEdge> nonPDEdgeSet = extractNonPostdominatingEdges(reversedCFG, postDomTree, proc);
List<DFANode> pdtNodeList = new ArrayList<DFANode>();
Iterator<DFANode> pdtIter = postDomTree.iterator();
int idx = 0;
while (pdtIter.hasNext()) {
DFANode node = pdtIter.next();
pdtNodeList.add(node);
// System.out.println("[" + idx++ + "]" +
// ((DFANode)((DFANode)node.getData("revNode")).getData("cfgNode")).getData("ir"));
}
for (CFGEdge edge : nonPDEdgeSet) {
// find lowest common ancestor of m and n (result: l)
DFANode commonAncestor = getLowestCommonAncestor(edge, postDomTree, pdtNodeList);
// all nodes in N on the path from l to n in the postdominance tree except l
// are control dependent on m
Set<DFANode> cdSet = getControlDependentSet(edge, commonAncestor);
DFANode controllingNode = edge.tail.getData("cfgNode");
// TODO: handled some corner cases this way but should be fixed later
// Some wrong controlling nodes are inserted, maybe due to the problem of control flow graph
if ((controllingNode.getData("ir") instanceof Expression) == false
&& (controllingNode.getData("ir") instanceof SwitchStatement) == false) {
// filter if a statement is a controlling node (wrong)
continue;
// throw new RuntimeException("controllingNode is not expression: " +
// controllingNode.getData("ir"));
} else {
if (controllingNode.getData("ir") instanceof Expression) {
// filter a stepping expression in the for loop is a controlling node (wrong)
Expression exp = controllingNode.getData("ir");
Traversable parent = exp.getParent();
if (parent instanceof ForLoop) {
ForLoop fLoop = (ForLoop) parent;
if (exp.equals(fLoop.getStep())) {
continue;
}
}
} else if (controllingNode.getData("ir") instanceof SwitchStatement) {
} else {
throw new RuntimeException(
"controllingNode is unexpected type: " + controllingNode.getData("ir"));
}
}
//
for (DFANode node : cdSet) {
DFANode revNode = node.getData("revNode");
if (revNode == null) {
continue;
}
DFANode controlledNode = revNode.getData("cfgNode");
controlledNode.putData("controlNode", controllingNode);
if (PrintTools.getVerbosity() > 1)
System.out.println(
"[Node]"
+ controlledNode.getData("ir")
+ " == control dependent on == [Node]"
+ controllingNode.getData("ir"));
}
}
// check inter-dependent node
// remove the controlling node for coming first node toward coming later node
Iterator<DFANode> cfgIter = cfg.iterator();
while (cfgIter.hasNext()) {
DFANode n = cfgIter.next();
DFANode cdNode = n.getData("controlNode");
if (cdNode == null) {
continue;
}
DFANode cdCDNode = cdNode.getData("controlNode");
if (n.equals(cdCDNode)) {
n.removeData("controlNode");
// throw new RuntimeException("My contol node is dependent on me. my: " + n +
// ",\n cd: " + cdNode);
}
}
// check a cyclic dependent node and remove it
cfgIter = cfg.iterator();
while (cfgIter.hasNext()) {
DFANode n = cfgIter.next();
DFANode cdNode = n.getData("controlNode");
while (cdNode != null) {
if (cdNode.equals(n)) {
cdNode.removeData("controlNode");
break;
// throw new RuntimeException("Cyclic dependency was found!!");
} else {
cdNode = cdNode.getData("controlNode");
}
}
}
}
}