From: bdemsky <bdemsky>
Date: Wed, 24 Jun 2009 09:34:20 +0000 (+0000)
Subject: improve propagation optimization
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c951b736cd2a3744c3af2410deb1929dc2800d6f;p=IRC.git

improve propagation optimization
---

diff --git a/Robust/src/Analysis/Loops/CopyPropagation.java b/Robust/src/Analysis/Loops/CopyPropagation.java
index e151f82a..9d211cf9 100644
--- a/Robust/src/Analysis/Loops/CopyPropagation.java
+++ b/Robust/src/Analysis/Loops/CopyPropagation.java
@@ -18,44 +18,46 @@ public class CopyPropagation {
     do {
       changed=false;
       HashSet tovisit=new HashSet();
-      HashSet discovered=new HashSet();
       tovisit.add(fm);
-      discovered.add(fm);
       while(!tovisit.isEmpty()) {
 	FlatNode fn=(FlatNode) tovisit.iterator().next();
 	tovisit.remove(fn);
-	for(int i=0;i<fn.numNext();i++) {
-	  FlatNode nnext=fn.getNext(i);
-	  if (!discovered.contains(nnext)) {
-	    discovered.add(nnext);
-	    tovisit.add(nnext);
-	  }
-	}
+
 	Hashtable<TempDescriptor, TempDescriptor> tab;
 	if (fn.numPrev()>=1&&table.containsKey(fn.getPrev(0)))
 	  tab=new Hashtable<TempDescriptor, TempDescriptor>(table.get(fn.getPrev(0)));
 	else
 	  tab=new Hashtable<TempDescriptor, TempDescriptor>();
 	//Compute intersection
+
+	HashSet<TempDescriptor> toremove=new HashSet<TempDescriptor>();
 	for(int i=1;i<fn.numPrev();i++) {
 	  Hashtable<TempDescriptor, TempDescriptor> tp=table.get(fn.getPrev(i));
 	  for(Iterator tmpit=tab.entrySet().iterator();tmpit.hasNext();) {
 	    Map.Entry t=(Map.Entry)tmpit.next();
 	    TempDescriptor tmp=(TempDescriptor)t.getKey();
-	    if (tp!=null&&(!tp.containsKey(tmp)||tp.get(tmp)!=tab.get(tmp))) {
-	      tmpit.remove();
+	    if (tp!=null&&tp.containsKey(tmp)&&tp.get(tmp)!=tab.get(tmp)) {
+	      toremove.add(tmp);
 	    }
 	  }
 	}
+
 	TempDescriptor[]writes=fn.writesTemps();
 	for(int i=0;i<writes.length;i++) {
 	  TempDescriptor tmp=writes[i];
+	  toremove.add(tmp);
 	  for(Iterator<TempDescriptor> tmpit=tab.keySet().iterator();tmpit.hasNext();) {	
 	    TempDescriptor tmp2=tmpit.next();
 	    if (tmp==tab.get(tmp2))
-	      tmpit.remove();
+	      toremove.add(tmp2);
 	  }
 	}
+
+	for(Iterator<TempDescriptor> tmpit=toremove.iterator();tmpit.hasNext();) {
+	  TempDescriptor tmp=tmpit.next();
+	  tab.put(tmp, bogustd);
+	}
+
 	if (fn.kind()==FKind.FlatOpNode) {
 	  FlatOpNode fon=(FlatOpNode)fn;
 	  if (fon.getOp().getOp()==Operation.ASSIGN) {
@@ -70,7 +72,9 @@ public class CopyPropagation {
 	    tovisit.add(nnext);
 	  }
 	}
-      }
+      } //end of dataflow while loop
+
+      //do remapping step here
       for(Iterator<FlatNode> it=fm.getNodeSet().iterator();it.hasNext();) {
 	FlatNode fn=it.next();
 	Hashtable<TempDescriptor, TempDescriptor> tab=table.get(fn);
@@ -78,7 +82,7 @@ public class CopyPropagation {
 	TempDescriptor[]reads=fn.readsTemps();
 	for(int i=0;i<reads.length;i++) {
 	  TempDescriptor tmp=reads[i];
-	  if (tab.containsKey(tmp)) {
+	  if (tab.containsKey(tmp)&&tab.get(tmp)!=bogustd) {
 	    if (tmap==null)
 	      tmap=new TempMap();
 	    tmap.addPair(tmp, tab.get(tmp));
@@ -86,7 +90,7 @@ public class CopyPropagation {
 	}
 	if (tmap!=null)
 	  fn.rewriteUse(tmap);
-      }
+      } //end of remapping for loop
     } while(changed);
   }
 }
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