net.sourceforge.cobertura.instrument.pass1

Class DetectDuplicatedCodeClassVisitor

java.lang.Object

org.objectweb.asm.ClassVisitor

net.sourceforge.cobertura.instrument.pass1.DetectDuplicatedCodeClassVisitor

public class DetectDuplicatedCodeClassVisitor
extends org.objectweb.asm.ClassVisitor

The same line can cause generation of many byte-code blocks connected to the same line. This especially occurs in case of 'finally' blocks. For example:

 173: public void methodWithFinishBlock(FinishReturnTypeEnum f){
 174:   try {
 175:     switch (f) {
 176:       case BY_RETURN:
 177:         System.out.println("will return");
 178:         return;
 179:         case BY_THROW:
 180:           System.out.println("will throw");
 181:           throw new IllegalStateException("Expected exception");
 182:         default:
 183:           System.out.println("default");
 184:     }
 185:     } finally {
 186:       if (f != null) { //This piece of code is generated in ASM 3 times. We should merge it into one block
 187:         System.out.println("Finish with: f="+f);
 188:     }
 189:   }
 190}
 

effects in generation such a JVM code:

 // access flags 1
   public methodWithFinishBlock(Ltest/performance/Test1$FinishReturnTypeEnum;)V
     TRYCATCHBLOCK L0 L1 L2 
     TRYCATCHBLOCK L3 L2 L2 
    L0
     LINENUMBER 175 L0
     INVOKESTATIC test/performance/Test1.$SWITCH_TABLE$test$performance$Test1$FinishReturnTypeEnum()[I
     ALOAD 1
     INVOKEVIRTUAL test/performance/Test1$FinishReturnTypeEnum.ordinal()I
     IALOAD
     TABLESWITCH
       1: L4
       2: L3
       default: L5
    L4
     LINENUMBER 177 L4
     GETSTATIC java/lang/System.out : Ljava/io/PrintStream;
     LDC "will return"
     INVOKEVIRTUAL java/io/PrintStream.println(Ljava/lang/String;)V
    L1
     LINENUMBER 186 L1
     ALOAD 1
     IFNULL L6
    L7
     LINENUMBER 187 L7
     GETSTATIC java/lang/System.out : Ljava/io/PrintStream;
     NEW java/lang/StringBuilder
     DUP
     LDC "Finish with: f="
     INVOKESPECIAL java/lang/StringBuilder.(Ljava/lang/String;)V
     ALOAD 1
     INVOKEVIRTUAL java/lang/StringBuilder.append(Ljava/lang/Object;)Ljava/lang/StringBuilder;
     INVOKEVIRTUAL java/lang/StringBuilder.toString()Ljava/lang/String;
     INVOKEVIRTUAL java/io/PrintStream.println(Ljava/lang/String;)V
    L6
     LINENUMBER 178 L6
     RETURN
    L3
     LINENUMBER 180 L3
     GETSTATIC java/lang/System.out : Ljava/io/PrintStream;
     LDC "will throw"
     INVOKEVIRTUAL java/io/PrintStream.println(Ljava/lang/String;)V
    L8
     LINENUMBER 181 L8
     NEW java/lang/IllegalStateException
     DUP
     LDC "Expected exception"
     INVOKESPECIAL java/lang/IllegalStateException.(Ljava/lang/String;)V
     ATHROW
    L5
     LINENUMBER 183 L5
     GETSTATIC java/lang/System.out : Ljava/io/PrintStream;
     LDC "default"
     INVOKEVIRTUAL java/io/PrintStream.println(Ljava/lang/String;)V
     GOTO L9
    L2
     LINENUMBER 185 L2
     ASTORE 2
    L10
     LINENUMBER 186 L10
     ALOAD 1
     IFNULL L11
    L12
     LINENUMBER 187 L12
     GETSTATIC java/lang/System.out : Ljava/io/PrintStream;
     NEW java/lang/StringBuilder
     DUP
     LDC "Finish with: f="
     INVOKESPECIAL java/lang/StringBuilder.(Ljava/lang/String;)V
     ALOAD 1
     INVOKEVIRTUAL java/lang/StringBuilder.append(Ljava/lang/Object;)Ljava/lang/StringBuilder;
     INVOKEVIRTUAL java/lang/StringBuilder.toString()Ljava/lang/String;
     INVOKEVIRTUAL java/io/PrintStream.println(Ljava/lang/String;)V
    L11
     LINENUMBER 189 L11
     ALOAD 2
     ATHROW
    L9
     LINENUMBER 186 L9
     ALOAD 1
     IFNULL L13
    L14
     LINENUMBER 187 L14
     GETSTATIC java/lang/System.out : Ljava/io/PrintStream;
     NEW java/lang/StringBuilder
     DUP
     LDC "Finish with: f="
     INVOKESPECIAL java/lang/StringBuilder.(Ljava/lang/String;)V
     ALOAD 1
     INVOKEVIRTUAL java/lang/StringBuilder.append(Ljava/lang/Object;)Ljava/lang/StringBuilder;
     INVOKEVIRTUAL java/lang/StringBuilder.toString()Ljava/lang/String;
     INVOKEVIRTUAL java/io/PrintStream.println(Ljava/lang/String;)V
    L13
     LINENUMBER 190 L13
     RETURN
    L15
     LOCALVARIABLE this Ltest/performance/Test1; L0 L15 0
     LOCALVARIABLE f Ltest/performance/Test1$FinishReturnTypeEnum; L0 L15 1
     MAXSTACK = 4
     MAXLOCALS = 3
 

Note that 'LINENUMBER 186' instruction occurs many times and code after that instruction is nearly identical (see CodeFootstamp criteria of 'identity').

On the other hand duplicated 'LINENUMBER 186' instruction could happened for for example for 'for' loop. In this case the code after this instruction is different.

The goal of this class is to provide duplicatedLinesCollector that is map of: (line number -> (duplicated lineId -> origin lineId)).

Field Summary

Fields

Modifier and Type	Field and Description
private java.lang.String	className Name (internal asm) of currently processed class
private java.util.Map<java.lang.Integer,java.util.Map<java.lang.Integer,java.lang.Integer>>	duplicatedLinesCollector map of (line number -> (duplicated lineId -> origin lineId))
private java.util.concurrent.atomic.AtomicInteger	lineIdGenerator Every LINENUMBER instruction will have generated it's lineId.

Fields inherited from class org.objectweb.asm.ClassVisitor

api, cv

Constructor Summary

Constructors

Constructor and Description
DetectDuplicatedCodeClassVisitor(org.objectweb.asm.ClassVisitor cv)

Method Summary

Modifier and Type	Method and Description
java.util.Map<java.lang.Integer,java.util.Map<java.lang.Integer,java.lang.Integer>>	getDuplicatesLinesCollector() Returns map of (line number -> (duplicated lineId -> origin lineId))
void	visit(int version, int access, java.lang.String name, java.lang.String signature, java.lang.String superName, java.lang.String[] interfaces)
org.objectweb.asm.MethodVisitor	visitMethod(int access, java.lang.String methodName, java.lang.String description, java.lang.String signature, java.lang.String[] exceptions)

Methods inherited from class org.objectweb.asm.ClassVisitor

visitAnnotation, visitAttribute, visitEnd, visitField, visitInnerClass, visitOuterClass, visitSource, visitTypeAnnotation

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

duplicatedLinesCollector

private java.util.Map<java.lang.Integer,java.util.Map<java.lang.Integer,java.lang.Integer>> duplicatedLinesCollector

map of (line number -> (duplicated lineId -> origin lineId))

className

private java.lang.String className

Name (internal asm) of currently processed class

lineIdGenerator

private final java.util.concurrent.atomic.AtomicInteger lineIdGenerator

Every LINENUMBER instruction will have generated it's lineId. The generated ids must be the same as those generated by ( AbstractFindTouchPointsClassInstrumenter.lineIdGenerator )

Constructor Detail

DetectDuplicatedCodeClassVisitor

public DetectDuplicatedCodeClassVisitor(org.objectweb.asm.ClassVisitor cv)

Method Detail

visit

public void visit(int version,
                  int access,
                  java.lang.String name,
                  java.lang.String signature,
                  java.lang.String superName,
                  java.lang.String[] interfaces)

Overrides:

visit in class org.objectweb.asm.ClassVisitor

visitMethod

public org.objectweb.asm.MethodVisitor visitMethod(int access,
                                                   java.lang.String methodName,
                                                   java.lang.String description,
                                                   java.lang.String signature,
                                                   java.lang.String[] exceptions)

Overrides:

visitMethod in class org.objectweb.asm.ClassVisitor

getDuplicatesLinesCollector

public java.util.Map<java.lang.Integer,java.util.Map<java.lang.Integer,java.lang.Integer>> getDuplicatesLinesCollector()

Returns map of (line number -> (duplicated lineId -> origin lineId))