Fixes BCEL-273 by partly reverting

adf9fc1.

java.lang.ClassCastException: edu.umd.cs.findbugs.bcel.generic.NULL2Z
cannot be cast to org.apache.commons.bcel6.generic.BranchInstruction
At
org.apache.commons.bcel6.generic.BranchHandle.getBI(BranchHandle.java:64)
At
org.apache.commons.bcel6.generic.BranchHandle.getPosition(BranchHandle.java:73)
At
edu.umd.cs.findbugs.ba.BetterCFGBuilder2$Subroutine.addInstruction(BetterCFGBuilder2.java:296)
At
edu.umd.cs.findbugs.ba.BetterCFGBuilder2.build(BetterCFGBuilder2.java:867)

src/main/java/org/apache/bcel/generic/BranchHandle.java

@@ -30,8 +30,12 @@
  */
 public final class BranchHandle extends InstructionHandle {
 
+    private BranchInstruction bi; // An alias in fact, but saves lots of casts
+
+
     private BranchHandle(final BranchInstruction i) {
         super(i);
+        bi = i;
     }
 
     /** Factory methods.
@@ -58,34 +62,29 @@ protected void addHandle() {
         bh_list = this;
     }
 
-    // get the instruction as a BranchInstruction
-    // (do the cast once)
-    private BranchInstruction getBI() {
-        return (BranchInstruction) super.getInstruction();
-    }
 
     /* Override InstructionHandle methods: delegate to branch instruction.
      * Through this overriding all access to the private i_position field should
      * be prevented.
      */
     @Override
     public int getPosition() {
-        return getBI().getPosition();
+        return bi.getPosition();
     }
 
 
     @Override
-    void setPosition( final int pos ) {
-        // Original code: i_position = bi.position = pos;
-        getBI().setPosition(pos);
-        super.setPosition(pos);
+    void setPosition( int pos ) {
+    	// Original code: i_position = bi.position = pos;
+    	bi.setPosition(pos);
+    	super.setPosition(pos);
     }
 
 
     @Override
     protected int updatePosition( final int offset, final int max_offset ) {
-        int x = getBI().updatePosition(offset, max_offset);
-        super.setPosition(getBI().getPosition());
+        int x = bi.updatePosition(offset, max_offset);
+        super.setPosition(bi.getPosition());
         return x;
     }
 
@@ -94,23 +93,23 @@ protected int updatePosition( final int offset, final int max_offset ) {
      * Pass new target to instruction.
      */
     public void setTarget( final InstructionHandle ih ) {
-        getBI().setTarget(ih);
+        bi.setTarget(ih);
     }
 
 
     /**
      * Update target of instruction.
      */
     public void updateTarget( final InstructionHandle old_ih, final InstructionHandle new_ih ) {
-        getBI().updateTarget(old_ih, new_ih);
+        bi.updateTarget(old_ih, new_ih);
     }
 
 
     /**
      * @return target of instruction.
      */
     public InstructionHandle getTarget() {
-        return getBI().getTarget();
+        return bi.getTarget();
     }
 
 
@@ -124,5 +123,6 @@ public void setInstruction( final Instruction i ) { // TODO could be package-pro
             throw new ClassGenException("Assigning " + i
                     + " to branch handle which is not a branch instruction");
         }
+        bi = (BranchInstruction) i;
     }
 }