[Fb-contrib-commit] SF.net SVN: fb-contrib: [613] trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/TailRecursion.java

[<dbr...@us...>]

Revision: 613
Author:   dbrosius
Date:     2006-08-12 10:18:40 -0700 (Sat, 12 Aug 2006)
ViewCVS:  http://svn.sourceforge.net/fb-contrib/?rev=613&view=rev

Log Message:
-----------
in order for it to be recursion, method has to be called on 'this' -- duh!

Modified Paths:
--------------
    trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/TailRecursion.java
Modified: trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/TailRecursion.java
===================================================================
--- trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/TailRecursion.java	2006-08-12 15:20:44 UTC (rev 612)
+++ trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/TailRecursion.java	2006-08-12 17:18:40 UTC (rev 613)
@@ -20,10 +20,13 @@
 
 import org.apache.bcel.classfile.Code;
 import org.apache.bcel.classfile.Method;
+import org.apache.bcel.generic.Type;
 
 import edu.umd.cs.findbugs.BugInstance;
 import edu.umd.cs.findbugs.BugReporter;
 import edu.umd.cs.findbugs.BytecodeScanningDetector;
+import edu.umd.cs.findbugs.OpcodeStack;
+import edu.umd.cs.findbugs.ba.ClassContext;
 
 /**
  * looks for methods that make a recursive call to itself as the last statement in the
@@ -35,8 +38,11 @@
 	public static final int TAILRECURSIONFUDGE = 6;
 	
 	private BugReporter bugReporter;
+	private OpcodeStack stack;
 	private int trPCPos;
 	private boolean possibleTailRecursion;
+	private boolean isStatic;
+	
     /**
      * constructs a TR detector given the reporter to report bugs on
 
@@ -47,6 +53,20 @@
 	}
 	
 	/**
+	 * implements the visitor to create and clear the stack
+	 * 
+	 * @param classContext the context object of the currently parsed class
+	 */
+	@Override
+	public void visitClassContext(ClassContext classContext) {
+		try {
+			stack = new OpcodeStack();
+			super.visitClassContext(classContext);
+		} finally {
+			stack = null;
+		}
+	}
+	/**
 	 * implements the visitor to figure the pc where the method call must occur
 	 * depending on whether the method returns a value, or not.
 	 * 
@@ -64,6 +84,8 @@
 				}
 				trPCPos -= TAILRECURSIONFUDGE;
 				possibleTailRecursion = true;
+				isStatic = obj.isStatic();
+				stack.resetForMethodEntry(this);
 				super.visitMethod(obj);
 			}
 		}
@@ -76,19 +98,33 @@
 	 */
 	@Override
 	public void sawOpcode(int seen) {
-		if (seen == INVOKEVIRTUAL) {
-			boolean isRecursion = (getMethodName().equals(getNameConstantOperand()))
-							   && (getMethodSig().equals(getSigConstantOperand()))
-							   && (getClassName().equals(getClassConstantOperand()));
+		try {
+			stack.mergeJumps(this);
 
-			if (isRecursion && possibleTailRecursion && (getPC() >= trPCPos)) {
-				bugReporter.reportBug(new BugInstance(this, "TR_TAIL_RECURSION", NORMAL_PRIORITY)
-							.addClass(this)
-							.addMethod(this)
-							.addSourceLine(this));
+			if (seen == INVOKEVIRTUAL) {
+				boolean isRecursion = (getMethodName().equals(getNameConstantOperand()))
+								   && (getMethodSig().equals(getSigConstantOperand()))
+								   && (getClassName().equals(getClassConstantOperand()));
+				
+				if (isRecursion && !isStatic) {
+					int numParms = Type.getArgumentTypes(getMethodSig()).length;
+					if (stack.getStackDepth() > numParms) {
+						OpcodeStack.Item itm = stack.getStackItem(numParms);
+						isRecursion = (itm.getRegisterNumber() == 0);
+					}
+				}
+	
+				if (isRecursion && possibleTailRecursion && (getPC() >= trPCPos)) {
+					bugReporter.reportBug(new BugInstance(this, "TR_TAIL_RECURSION", NORMAL_PRIORITY)
+								.addClass(this)
+								.addMethod(this)
+								.addSourceLine(this));
+				}
+				else
+					possibleTailRecursion = false;
 			}
-			else
-				possibleTailRecursion = false;
+		} finally {
+			stack.sawOpcode(this, seen);
 		}
 	}
 }


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