1 package Analysis.Loops;
4 import java.util.Iterator;
5 import java.util.Hashtable;
6 import java.util.HashSet;
9 public class CopyPropagation {
10 public CopyPropagation() {
13 public void optimize(FlatMethod fm) {
14 Hashtable<FlatNode, Hashtable<TempDescriptor, TempDescriptor>> table
15 =new Hashtable<FlatNode, Hashtable<TempDescriptor, TempDescriptor>>();
16 boolean changed=false;
17 TempDescriptor bogustd=new TempDescriptor("bogus");
20 HashSet tovisit=new HashSet();
22 while(!tovisit.isEmpty()) {
23 FlatNode fn=(FlatNode) tovisit.iterator().next();
26 Hashtable<TempDescriptor, TempDescriptor> tab;
27 if (fn.numPrev()>=1&&table.containsKey(fn.getPrev(0)))
28 tab=new Hashtable<TempDescriptor, TempDescriptor>(table.get(fn.getPrev(0)));
30 tab=new Hashtable<TempDescriptor, TempDescriptor>();
31 //Compute intersection
33 HashSet<TempDescriptor> toremove=new HashSet<TempDescriptor>();
34 for(int i=1;i<fn.numPrev();i++) {
35 Hashtable<TempDescriptor, TempDescriptor> tp=table.get(fn.getPrev(i));
36 for(Iterator tmpit=tp.entrySet().iterator();tmpit.hasNext();) {
37 Map.Entry t=(Map.Entry)tmpit.next();
38 TempDescriptor tmp=(TempDescriptor)t.getKey();
40 if (!tab.containsKey(tmp))
41 tab.put(tmp, tp.get(tmp));
42 else if (tab.get(tmp)!=tp.get(tmp)) {
43 tab.put(tmp, bogustd);
48 TempDescriptor[]writes=fn.writesTemps();
49 for(int i=0;i<writes.length;i++) {
50 TempDescriptor tmp=writes[i];
52 for(Iterator<TempDescriptor> tmpit=tab.keySet().iterator();tmpit.hasNext();) {
53 TempDescriptor tmp2=tmpit.next();
54 if (tmp==tab.get(tmp2))
59 for(Iterator<TempDescriptor> tmpit=toremove.iterator();tmpit.hasNext();) {
60 TempDescriptor tmp=tmpit.next();
61 tab.put(tmp, bogustd);
64 if (fn.kind()==FKind.FlatOpNode) {
65 FlatOpNode fon=(FlatOpNode)fn;
66 if (fon.getOp().getOp()==Operation.ASSIGN) {
67 tab.put(fon.getDest(), fon.getLeft());
70 if (!table.containsKey(fn)||!table.get(fn).equals(tab)) {
73 for(int i=0;i<fn.numNext();i++) {
74 FlatNode nnext=fn.getNext(i);
78 } //end of dataflow while loop
80 //do remapping step here
81 for(Iterator<FlatNode> it=fm.getNodeSet().iterator();it.hasNext();) {
82 FlatNode fn=it.next();
83 Hashtable<TempDescriptor, TempDescriptor> tab=table.get(fn);
85 TempDescriptor[]reads=fn.readsTemps();
86 for(int i=0;i<reads.length;i++) {
87 TempDescriptor tmp=reads[i];
88 if (tab.containsKey(tmp)&&tab.get(tmp)!=bogustd) {
91 tmap.addPair(tmp, tab.get(tmp));
96 } //end of remapping for loop