From 2299d8a13af9637532b43c073f9d1c2c9bf37cf8 Mon Sep 17 00:00:00 2001
From: Manu Sridharan <msridhar@us.ibm.com>
Date: Tue, 17 Jul 2012 12:11:55 -0700
Subject: [PATCH] improve caching of receiver values when handling dispatch

---
 .../SSAPropagationCallGraphBuilder.java       | 27 +++++++++++++------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/propagation/SSAPropagationCallGraphBuilder.java b/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/propagation/SSAPropagationCallGraphBuilder.java
index 5d753f90b..dde349aeb 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/propagation/SSAPropagationCallGraphBuilder.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/propagation/SSAPropagationCallGraphBuilder.java
@@ -1601,7 +1601,9 @@ public abstract class SSAPropagationCallGraphBuilder extends PropagationCallGrap
     @Override
     public byte evaluate(PointsToSetVariable lhs, final PointsToSetVariable[] rhs) {
       assert dispatchIndices.length >= rhs.length : "bad operator at " + call;
-      final MutableBoolean sideEffect = new MutableBoolean();
+      // did evaluating the dispatch operation add a new possible target
+      // to the call site?  
+      final MutableBoolean addedNewTarget = new MutableBoolean();
       
       final MutableIntSet receiverVals;
       if (constParams != null && constParams[0] != null) {
@@ -1636,6 +1638,10 @@ public abstract class SSAPropagationCallGraphBuilder extends PropagationCallGrap
       // keep separate rhsIndex, since it doesn't advance for constant
       // parameters
       int rhsIndex = (constParams != null && constParams[0] != null)? 0: 1;
+      // this flag is set to true if we ever call handleAllReceivers() in the
+      // loop below. we need to catch the case where we have a new receiver, but
+      // there are no other dispatch indices with new values
+      boolean propagatedReceivers = false;
       // we start at index 1 since we need to handle the receiver specially; see
       // below
       for (int index = 1; index < dispatchIndices.length; index++) {
@@ -1652,7 +1658,8 @@ public abstract class SSAPropagationCallGraphBuilder extends PropagationCallGrap
           if (newReceiver || prevAtIndex.isEmpty()) {
             for(int i = 0; i < constParams[paramIndex].length; i++) {
               keys[paramIndex] = constParams[paramIndex][i];
-              handleAllReceivers(receiverVals,keys, sideEffect);
+              handleAllReceivers(receiverVals,keys, addedNewTarget);
+              propagatedReceivers = true;
               int ii = system.instanceKeys.getMappedIndex(constParams[paramIndex][i]);
               prevAtIndex.add(ii);
             }            
@@ -1665,7 +1672,8 @@ public abstract class SSAPropagationCallGraphBuilder extends PropagationCallGrap
               int ptr = ptrs.next();
               if (newReceiver || !prevAtIndex.contains(ptr)) {
                 keys[paramIndex] = system.getInstanceKey(ptr);
-                handleAllReceivers(receiverVals,keys, sideEffect);
+                handleAllReceivers(receiverVals,keys, addedNewTarget);
+                propagatedReceivers = true;
                 prevAtIndex.add(ptr);
               }
             }
@@ -1674,14 +1682,17 @@ public abstract class SSAPropagationCallGraphBuilder extends PropagationCallGrap
         }
         keys[paramIndex] = null;
       }
-      if (newReceiver && !sideEffect.b) {
-        // we have a new receiver value, and it wasn't propagated at all,
-        // so propagate it now
-        handleAllReceivers(receiverVals, keys, sideEffect);
+      if (newReceiver) {
+        if (!propagatedReceivers) {
+          // we have a new receiver value, and it wasn't propagated at all,
+          // so propagate it now
+          handleAllReceivers(receiverVals, keys, addedNewTarget);
+        }
+        // update receiver cache
         previousPtrs[0].addAll(receiverVals);
       }
 
-      byte sideEffectMask = sideEffect.b ? (byte) SIDE_EFFECT_MASK : 0;
+      byte sideEffectMask = addedNewTarget.b ? (byte) SIDE_EFFECT_MASK : 0;
       return (byte) (NOT_CHANGED | sideEffectMask);
     }