[Fb-contrib-commit] SF.net SVN: fb-contrib: [697] trunk/fb-contrib/src/com/mebigfatguy/ fbcontrib/detect/BloatedAssignmentScope.java

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

Revision: 697
          http://svn.sourceforge.net/fb-contrib/?rev=697&view=rev
Author:   dbrosius
Date:     2006-11-29 22:05:11 -0800 (Wed, 29 Nov 2006)

Log Message:
-----------
initial checkin BAS

Added Paths:
-----------
    trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/BloatedAssignmentScope.java

Added: trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/BloatedAssignmentScope.java
===================================================================
--- trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/BloatedAssignmentScope.java	                        (rev 0)
+++ trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/BloatedAssignmentScope.java	2006-11-30 06:05:11 UTC (rev 697)
@@ -0,0 +1,77 @@
+package com.mebigfatguy.fbcontrib.detect;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.bcel.classfile.Code;
+
+import com.mebigfatguy.fbcontrib.utils.RegisterUtils;
+
+import edu.umd.cs.findbugs.BugReporter;
+import edu.umd.cs.findbugs.BytecodeScanningDetector;
+import edu.umd.cs.findbugs.ba.ClassContext;
+
+/**
+ * looks for variable assignments at a scope larger than its use. In this case,
+ * the assignment can be pushed down into the smaller scope to reduce the performance
+ * impact of that assignment.
+ */
+public class BloatedAssignmentScope extends BytecodeScanningDetector 
+{
+	private BugReporter bugReporter;
+	private Map<Integer, Integer> regToLocationMap;
+	private Map<Integer, Integer> scopeBlockMap;
+	
+	/**
+     * constructs a BLT detector given the reporter to report bugs on
+
+     * @param bugReporter the sync of bug reports
+     */		
+	public BloatedAssignmentScope(BugReporter bugReporter) {
+		this.bugReporter = bugReporter;
+	}
+	
+	/**
+	 * implements the visitor to create and the clear the register to location map
+	 * 
+	 * @param classContext the context object of the currently parsed class
+	 */
+	@Override
+	public void visitClassContext(ClassContext classContext) {
+		try {
+			regToLocationMap = new HashMap<Integer, Integer>();
+			scopeBlockMap = new HashMap<Integer, Integer>();
+			super.visitClassContext(classContext);
+		} finally {
+			regToLocationMap = null;
+			scopeBlockMap = null;
+		}
+	}
+	
+	/**
+	 * implements the visitor to reset the register to location map
+	 * 
+	 * @param obj the context object of the currently parsed code block
+	 */
+	@Override
+	public void visitCode(Code obj) {
+		regToLocationMap.clear();
+		scopeBlockMap.clear();
+		super.visitCode(obj);
+	}
+	
+	/**
+	 * implements the visitor to look for variables assigned out side of the scope
+	 * in which they are used.
+	 * 
+	 * @param seen the opcode of the currently parsed instruction
+	 */
+	@Override
+	public void sawOpcode(int seen) {
+		if ((seen == ASTORE) || ((seen >= ASTORE_0) && (seen <= ASTORE_3))) {
+			int reg = RegisterUtils.getAStoreReg(this, seen);
+		} else if ((seen == ALOAD) || ((seen >= ALOAD_0) && (seen <= ALOAD_3))) {
+			int reg = RegisterUtils.getALoadReg(this, seen);
+		}
+	}
+}


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