improved Javadoc

com.ibm.wala.cast.js/source/com/ibm/wala/cast/js/ssa/JavaScriptCheckReference.java

@@ -9,6 +9,10 @@ import com.ibm.wala.ssa.SSAInstructionFactory;
 import com.ibm.wala.ssa.SymbolTable;
 import com.ibm.wala.types.TypeReference;
 
+/**
+ * Checks if a reference is null or undefined, and if so, throws a
+ * ReferenceError. Otherwise, it's a no-op.
+ */
 public class JavaScriptCheckReference extends SSAInstruction {
   private final int ref;
   

com.ibm.wala.cast/source/java/com/ibm/wala/cast/ir/ssa/AstIsDefinedInstruction.java

@@ -10,15 +10,35 @@ import com.ibm.wala.types.FieldReference;
 import com.ibm.wala.types.TypeReference;
 import com.ibm.wala.util.debug.Assertions;
 
+/**
+ * IR instruction to check whether a field is defined on some object. The field
+ * is represented either by a {@link FieldReference} or by a local value number.  
+ */
 public class AstIsDefinedInstruction extends SSAInstruction {
+  /**
+   * name of the field.  If non-null, fieldVal should be -1.
+   */
   private final FieldReference fieldRef;
 
+  /**
+   * value number holding the field string.  If non-negative,
+   * fieldRef should be null.
+   */
   private final int fieldVal;
 
+  /**
+   * the base pointer
+   */
   private final int rval;
 
+  /**
+   * gets 1 if the field is defined, 0 otherwise.
+   */
   private final int lval;
 
+  /**
+   * This constructor should only be used from {@link SSAInstruction#copyForSSA(SSAInstructionFactory, int[], int[])}
+   */
   public AstIsDefinedInstruction(int lval, int rval, int fieldVal, FieldReference fieldRef) {
     this.lval = lval;
     this.rval = rval;