compare -> isTypingMoreGeneral; parallel minimize implementation

src/main/java/soot/jimple/toolkits/typing/fast/DefaultTypingStrategy.java

@@ -29,6 +29,11 @@
 import java.util.List;
 import java.util.ListIterator;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import soot.Local;
 import soot.RefType;
@@ -42,6 +47,7 @@
  * The default typing strategy
  */
 public class DefaultTypingStrategy implements ITypingStrategy {
+  private static final Logger logger = LoggerFactory.getLogger(DefaultTypingStrategy.class);
 
   public static final ITypingStrategy INSTANCE = new DefaultTypingStrategy();
 
@@ -81,49 +87,98 @@ public static Set<Local> getObjectLikeTypings(List<Typing> tgs) {
 
   @Override
   public void minimize(List<Typing> tgs, IHierarchy h) {
+    if (tgs.size() > 1000) {
+      minimizeParallel(tgs, h);
+      return;
+    }
+
     Set<Local> objectVars = getObjectLikeTypings(tgs);
     OUTER: for (ListIterator<Typing> i = tgs.listIterator(); i.hasNext();) {
       Typing tgi = i.next();
 
       // Throw out duplicate typings
       for (Typing tgj : tgs) {
-        // if compare = 1, then tgi is the more general typing
+        // if tgi is the more general typing (isTypingSetMoreGeneral == true)
         // We shouldn't pick that one as we would then end up
         // with lots of locals typed to Serializable etc.
-        if (tgi != tgj && compare(tgi, tgj, h, objectVars) == 1) {
+        if (tgi != tgj && isTypingMoreGeneral(tgi, tgj, h, objectVars)) {
           i.remove();
           continue OUTER;
         }
       }
     }
   }
 
-  public int compare(Typing a, Typing b, IHierarchy h, Collection<Local> localsToIgnore) {
-    int r = 0;
+  /**
+   * Check if typing a is more general than typing b
+   * 
+   * Replaces the old compare method that was able to detect more cases.
+   * 
+   * @param a
+   * @param b
+   * @param h
+   * @param localsToIgnore
+   * @return
+   */
+  public boolean isTypingMoreGeneral(Typing a, Typing b, IHierarchy h, Collection<Local> localsToIgnore) {
+    boolean result = false;
     for (Local v : a.map.keySet()) {
       if (!localsToIgnore.contains(v)) {
         Type ta = a.get(v), tb = b.get(v);
 
-        int cmp;
-        if (TypeResolver.typesEqual(ta, tb)) {
-          cmp = 0;
+        if (ta == tb || TypeResolver.typesEqual(ta, tb)) {
+          // ta == tb can happen often, thus it gains a small performance boost checking it directly
         } else if (h.ancestor(ta, tb)) {
-          cmp = 1;
+          // local ta is an ancestor of tb, so typing a is potentially more general than typing b.
+          // We need to check the other locals for a final result.
+          result = true;
         } else if (h.ancestor(tb, ta)) {
-          cmp = -1;
+          // local tb is an ancestor of ta, this means tb is more general than ta.
+          // Therefore the whole set a can not be more general than b
+          return false;
         } else {
-          return -2;
+          // types not comparable
+          return false;
         }
+      }
+    }
+    return result;
+  }
 
-        if ((cmp == 1 && r == -1) || (cmp == -1 && r == 1)) {
-          return 2;
-        }
-        if (r == 0) {
-          r = cmp;
+  public void minimizeParallel(List<Typing> tgs, IHierarchy h) {
+    logger.debug("Performing parallel minimization");
+    final AtomicInteger processed = new AtomicInteger();
+    Set<Local> objectVars = getObjectLikeTypings(tgs);
+
+    final int size = tgs.size();
+    List<DeletableTyping> typings = tgs.stream().map(t -> new DeletableTyping(t)).collect(Collectors.toList());
+
+    typings.parallelStream().forEach(t -> {
+      Typing tgi = t.typing;
+      // Mark duplicate typings
+      for (Typing tgj : tgs) {
+        // if tgi is the more general typing (isTypingSetMoreGeneral == true)
+        // We shouldn't pick that one as we would then end up
+        // with lots of locals typed to Serializable etc.
+        if (tgi != tgj && isTypingMoreGeneral(tgi, tgj, h, objectVars)) {
+          t.deleted = true;
+          break;
         }
       }
+      int count = processed.incrementAndGet();
+      if (count % 1000 == 0) {
+        logger.debug("minimizing {} = {}%", count, (100f * count) / size);
+      }
+    });
+
+    // Remove marked Typing list entries from tgs
+    // this loop works because tgs[i] == typings[i].typing
+    for (int i = typings.size() - 1; i >= 0; i--) {
+      DeletableTyping deletableTyping = typings.get(i);
+      if (deletableTyping.deleted) {
+        tgs.remove(i);
+      }
     }
-    return r;
   }
 
   @Override
@@ -136,4 +191,15 @@ public void finalizeTypes(Typing tp) {
     }
   }
 
+  private static class DeletableTyping {
+    private boolean deleted = false;
+
+    private final Typing typing;
+
+    public DeletableTyping(Typing typing) {
+      super();
+      this.typing = typing;
+    }
+
+  }
 }