[Fb-contrib-commit] SF.net SVN: fb-contrib:[1451] trunk/fb-contrib/src/com/mebigfatguy/ fbcontrib/detect/WrongNullGuard.java

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

Revision: 1451
          http://fb-contrib.svn.sourceforge.net/fb-contrib/?rev=1451&view=rev
Author:   dbrosius
Date:     2010-01-09 04:24:17 +0000 (Sat, 09 Jan 2010)

Log Message:
-----------
only report WNG if another variable with the same signature as the nonnull guard variable is loaded in the if block guarded by a non null statement

Modified Paths:
--------------
    trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/WrongNullGuard.java

Modified: trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/WrongNullGuard.java
===================================================================
--- trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/WrongNullGuard.java	2010-01-05 09:04:32 UTC (rev 1450)
+++ trunk/fb-contrib/src/com/mebigfatguy/fbcontrib/detect/WrongNullGuard.java	2010-01-09 04:24:17 UTC (rev 1451)
@@ -23,6 +23,8 @@
 import java.util.Map;
 
 import org.apache.bcel.classfile.Code;
+import org.apache.bcel.classfile.LocalVariable;
+import org.apache.bcel.classfile.LocalVariableTable;
 
 import com.mebigfatguy.fbcontrib.utils.RegisterUtils;
 
@@ -44,6 +46,7 @@
 	
 	private BugReporter bugReporter;
 	private OpcodeStack stack;
+	private LocalVariableTable lvt;
 	private Map<Integer, NullGuard> nullGuards;
 	
 	/**
@@ -77,9 +80,14 @@
 	 */
 	@Override
 	public void visitCode(Code obj) {
-		stack.resetForMethodEntry(this);
-		nullGuards.clear();
-		super.visitCode(obj);
+		try {
+			stack.resetForMethodEntry(this);
+			lvt = getMethod().getLocalVariableTable();
+			nullGuards.clear();
+			super.visitCode(obj);
+		} finally {
+			lvt = null;
+		}
 	}
 	
 	/**
@@ -92,7 +100,7 @@
 		try {
 			Integer pc = Integer.valueOf(getPC());
 			NullGuard guard = nullGuards.remove(pc);
-			if (guard != null) {
+			if ((guard != null) && guard.sawSignatureOfGuard()) {
 				boolean localBug = guard.getRegister() >= 0;
 				bugReporter.reportBug(new BugInstance(this, localBug ? "WNG_WRONG_NULL_LOCAL_GUARD" : "WNG_WRONG_NULL_FIELD_GUARD", localBug ? NORMAL_PRIORITY : LOW_PRIORITY)
 						                    .addClass(this)
@@ -107,17 +115,31 @@
 						int reg = item.getRegisterNumber();
 						Integer target = Integer.valueOf(getBranchTarget());
 						if (reg >= 0) {
-							nullGuards.put(target, new NullGuard(reg, pc.intValue()));
+							nullGuards.put(target, new NullGuard(reg, pc.intValue(), item.getSignature()));
 						} else {
 							XField xf = item.getXField();
 							if (xf != null) {
-								nullGuards.put(target, new NullGuard(xf, pc.intValue()));
+								nullGuards.put(target, new NullGuard(xf, pc.intValue(), item.getSignature()));
 							}
 						}
 					}
 				}
 				break;
 				
+				case ALOAD:
+				case ALOAD_0:
+				case ALOAD_1:
+				case ALOAD_2:
+				case ALOAD_3: {
+					if (lvt != null) {
+						LocalVariable lv = lvt.getLocalVariable(RegisterUtils.getALoadReg(this, seen), getNextPC());
+						if (lv != null) {
+							markNullGuards(lv.getSignature());
+						}
+					}
+				}
+				break;
+					
 				case ASTORE:
 				case ASTORE_0:
 				case ASTORE_1:
@@ -127,6 +149,11 @@
 				}
 				break;
 				
+				case GETFIELD: {
+					markNullGuards(getSigConstantOperand());
+				}
+				break;
+				
 				case PUTFIELD: {
 					removeGuardForField(getXField());
 				}
@@ -150,27 +177,6 @@
 				}
 				break;
 				
-				case IRETURN:
-					if (stack.getStackDepth() > 0) {
-						OpcodeStack.Item item = stack.getStackItem(0);
-						Integer value = (Integer)item.getConstant();
-						if (value != null) {
-							int val = value.intValue();
-							if ((val == 0) || (val == 1)) 
-								nullGuards.clear();	
-						}
-					}
-					//FALL_THRU
-					
-				case FRETURN:
-				case DRETURN:
-				case ARETURN:
-				case LRETURN:
-				case RETURN: {
-					nullGuards.remove(Integer.valueOf(getPC() + 1));
-				}
-				break;
-				
 				case GOTO: {
 					if (stack.getStackDepth() > 0) {
 						nullGuards.clear();
@@ -194,6 +200,14 @@
 		}
 	}
 	
+	private void markNullGuards(String signature) {
+		for (NullGuard ng : nullGuards.values()) {
+			if (ng.getSignature().equals(signature)) {
+				ng.markSignatureOfGuard();
+			}
+		}
+	}
+	
 	private void removeGuardForRegister(int reg) {
 		Iterator<NullGuard> it = nullGuards.values().iterator();
 		while (it.hasNext()) {
@@ -220,18 +234,22 @@
 		int register;
 		XField field;
 		int location;
+		String signature;
+		boolean sawSignature = false;
 		
-		public NullGuard(int reg, int start) {
+		public NullGuard(int reg, int start, String guardSignature) {
 			register = reg;
 			field = null;
 			location = start;
+			signature = guardSignature;
 		}
 
 
-		public NullGuard(XField xf, int start) {
+		public NullGuard(XField xf, int start, String guardSignature) {
 			register = -1;
 			field = xf;
 			location = start;
+			signature = guardSignature;
 		}
 
 		public int getRegister() {
@@ -245,5 +263,17 @@
 		public int getLocation() {
 			return location;
 		}
+		
+		public String getSignature() {
+			return signature;
+		}
+		
+		public void markSignatureOfGuard() {
+			sawSignature = true;
+		}
+		
+		public boolean sawSignatureOfGuard() {
+			return sawSignature;
+		}
 	}
 }


This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site.