Robust/src/Analysis/Loops/CopyPropagation.java

   1 package Analysis.Loops;
   2 import IR.Flat.*;
   3 import IR.Operation;
   4 import java.util.Iterator;
   5 import java.util.Hashtable;
   6 import java.util.HashSet;
   7 import java.util.Set;
   8 import java.util.Map;
   9
  10 public class CopyPropagation {
  11   public CopyPropagation() {
  12   }
  13
  14   public void optimize(FlatMethod fm) {
  15
  16     Hashtable<FlatNode, Hashtable<TempDescriptor, TempDescriptor>> table
  17       =new Hashtable<FlatNode, Hashtable<TempDescriptor, TempDescriptor>>();
  18     boolean changed=false;
  19     TempDescriptor bogustd=new TempDescriptor("bogus");
  20     do {
  21       changed=false;
  22       HashSet tovisit=new HashSet();
  23       tovisit.add(fm);
  24       while(!tovisit.isEmpty()) {
  25         FlatNode fn=(FlatNode) tovisit.iterator().next();
  26         tovisit.remove(fn);
  27
  28         Hashtable<TempDescriptor, TempDescriptor> tab;
  29         if (fn.numPrev()>=1&&table.containsKey(fn.getPrev(0)))
  30           tab=new Hashtable<TempDescriptor, TempDescriptor>(table.get(fn.getPrev(0)));
  31         else
  32           tab=new Hashtable<TempDescriptor, TempDescriptor>();
  33         //Compute intersection
  34
  35         for(int i=1;i<fn.numPrev();i++) {
  36           Hashtable<TempDescriptor, TempDescriptor> tp=table.get(fn.getPrev(i));
  37           if (tp==null)
  38             continue;
  39           for(Iterator tmpit=tp.entrySet().iterator();tmpit.hasNext();) {
  40             Map.Entry t=(Map.Entry)tmpit.next();
  41             TempDescriptor tmp=(TempDescriptor)t.getKey();
  42
  43             if (!tab.containsKey(tmp))
  44               tab.put(tmp, tp.get(tmp));
  45             else if (tab.get(tmp)!=tp.get(tmp)) {
  46               tab.put(tmp, bogustd);
  47             }
  48           }
  49         }
  50
  51         HashSet<TempDescriptor> toremove=new HashSet<TempDescriptor>();
  52         TempDescriptor[]writes=fn.writesTemps();
  53         for(int i=0;i<writes.length;i++) {
  54           TempDescriptor tmp=writes[i];
  55           toremove.add(tmp);
  56           for(Iterator<TempDescriptor> tmpit=tab.keySet().iterator();tmpit.hasNext();) {
  57             TempDescriptor tmp2=tmpit.next();
  58             if (tmp==tab.get(tmp2))
  59               toremove.add(tmp2);
  60           }
  61         }
  62
  63         for(Iterator<TempDescriptor> tmpit=toremove.iterator();tmpit.hasNext();) {
  64           TempDescriptor tmp=tmpit.next();
  65           tab.put(tmp, bogustd);
  66         }
  67
  68         if (fn.kind()==FKind.FlatOpNode) {
  69           FlatOpNode fon=(FlatOpNode)fn;
  70           if (fon.getOp().getOp()==Operation.ASSIGN) {
  71             tab.put(fon.getDest(), fon.getLeft());
  72           }
  73         }
  74         if (!table.containsKey(fn)||!table.get(fn).equals(tab)) {
  75           table.put(fn,tab);
  76           changed=true;
  77           for(int i=0;i<fn.numNext();i++) {
  78             FlatNode nnext=fn.getNext(i);
  79             tovisit.add(nnext);
  80           }
  81         }
  82       } //end of dataflow while loop
  83
  84       Set<FlatNode> nodeset=fm.getNodeSet();
  85
  86       for(Iterator<FlatNode> it=fm.getNodeSet().iterator();it.hasNext();) {
  87         FlatNode fn=it.next();
  88         if (fn.numPrev()==0)
  89           continue;
  90
  91         Hashtable<TempDescriptor, TempDescriptor> tab=new Hashtable<TempDescriptor, TempDescriptor>();
  92
  93         for(int i=0;i<fn.numPrev();i++) {
  94           Hashtable<TempDescriptor, TempDescriptor> tp=table.get(fn.getPrev(i));
  95           for(Iterator tmpit=tp.entrySet().iterator();tmpit.hasNext();) {
  96             Map.Entry t=(Map.Entry)tmpit.next();
  97             TempDescriptor tmp=(TempDescriptor)t.getKey();
  98
  99             if (!tab.containsKey(tmp))
 100               tab.put(tmp, tp.get(tmp));
 101             else if (tab.get(tmp)!=tp.get(tmp)) {
 102               tab.put(tmp, bogustd);
 103             }
 104           }
 105         }
 106
 107         TempMap tmap=null;
 108         TempDescriptor[]reads=fn.readsTemps();
 109         for(int i=0;i<reads.length;i++) {
 110           TempDescriptor tmp=reads[i];
 111           if (tab.containsKey(tmp)&&tab.get(tmp)!=bogustd) {
 112             if (tmap==null)
 113               tmap=new TempMap();
 114             tmap.addPair(tmp, tab.get(tmp));
 115           }
 116         }
 117         if (tmap!=null)
 118           fn.rewriteUse(tmap);
 119       } //end of remapping for loop
 120     } while(changed);
 121   }
 122 }