a whole bunch of optimizations...should be useful for transactions

[IRC.git] / Robust / src / Analysis / Loops / UseDef.java

diff --git a/Robust/src/Analysis/Loops/UseDef.java b/Robust/src/Analysis/Loops/UseDef.java
index 243c7da0f004571686f0770cc339365223382ec5..7bf6b54c31f3d82e8628b34b9e446bcadd26e7dc 100644 (file)
--- a/Robust/src/Analysis/Loops/UseDef.java
+++ b/Robust/src/Analysis/Loops/UseDef.java
@@ -19,12 +19,20 @@ public class UseDef{
 
   /* Return FlatNodes that define Temp */
   public Set<FlatNode> defMap(FlatNode fn, TempDescriptor t) {
-    return defs.get(new TempFlatPair(t,fn));
+    Set<FlatNode> s=defs.get(new TempFlatPair(t,fn));
+    if (s==null)
+      return new HashSet<FlatNode>();
+    else
+      return s;
   }
 
   /* Return FlatNodes that use Temp */
   public Set<FlatNode> useMap(FlatNode fn, TempDescriptor t) {
-    return uses.get(new TempFlatPair(t,fn));
+    Set<FlatNode> s=uses.get(new TempFlatPair(t,fn));
+    if (s==null)
+      return new HashSet<FlatNode>();
+    else
+      return s;
   }
 
   public void analyze(FlatMethod fm) {
@@ -40,14 +48,16 @@ public class UseDef{
       for(int i=0;i<fn.numPrev();i++) {
        FlatNode prev=fn.getPrev(i);
        Set<TempFlatPair> prevs=tmp.get(prev);
-       nexttfp:
-       for(Iterator<TempFlatPair> tfit=prevs.iterator();tfit.hasNext();) {
-         TempFlatPair tfp=tfit.next();
-         for(int j=0;j<fnwrites.length;j++) {
-           if (tfp.t==fnwrites[j])
-             continue nexttfp;
+       if (prevs!=null) {
+         nexttfp:
+         for(Iterator<TempFlatPair> tfit=prevs.iterator();tfit.hasNext();) {
+           TempFlatPair tfp=tfit.next();
+           for(int j=0;j<fnwrites.length;j++) {
+             if (tfp.t==fnwrites[j])
+               continue nexttfp;
+           }
+           s.add(tfp);
          }
-         s.add(tfp);
        }
        for(int j=0;j<fnwrites.length;j++) {
          TempFlatPair tfp=new TempFlatPair(fnwrites[j], fn);