org.objectweb.asm.tree.analysis
Class Analyzer

java.lang.Object
  org.objectweb.asm.tree.analysis.Analyzer

All Implemented Interfaces:

Opcodes

public class Analyzer
extends java.lang.Object
implements Opcodes

A semantic bytecode analyzer. This class does not fully check that JSR and RET instructions are valid.

Author:

Eric Bruneton

Field Summary

private Frame[]	frames
private java.util.List[]	handlers
private InsnList	insns
private Interpreter	interpreter
private int	n
private int[]	queue
private boolean[]	queued
private Subroutine[]	subroutines
private int	top

Fields inherited from interface org.objectweb.asm.Opcodes

AALOAD, AASTORE, ACC_ABSTRACT, ACC_ANNOTATION, ACC_BRIDGE, ACC_DEPRECATED, ACC_ENUM, ACC_FINAL, ACC_INTERFACE, ACC_NATIVE, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_STATIC, ACC_STRICT, ACC_SUPER, ACC_SYNCHRONIZED, ACC_SYNTHETIC, ACC_TRANSIENT, ACC_VARARGS, ACC_VOLATILE, ACONST_NULL, ALOAD, ANEWARRAY, ARETURN, ARRAYLENGTH, ASTORE, ATHROW, BALOAD, BASTORE, BIPUSH, CALOAD, CASTORE, CHECKCAST, D2F, D2I, D2L, DADD, DALOAD, DASTORE, DCMPG, DCMPL, DCONST_0, DCONST_1, DDIV, DLOAD, DMUL, DNEG, DOUBLE, DREM, DRETURN, DSTORE, DSUB, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, F_APPEND, F_CHOP, F_FULL, F_NEW, F_SAME, F_SAME1, F2D, F2I, F2L, FADD, FALOAD, FASTORE, FCMPG, FCMPL, FCONST_0, FCONST_1, FCONST_2, FDIV, FLOAD, FLOAT, FMUL, FNEG, FREM, FRETURN, FSTORE, FSUB, GETFIELD, GETSTATIC, GOTO, I2B, I2C, I2D, I2F, I2L, I2S, IADD, IALOAD, IAND, IASTORE, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, ICONST_M1, IDIV, IF_ACMPEQ, IF_ACMPNE, IF_ICMPEQ, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ICMPLT, IF_ICMPNE, IFEQ, IFGE, IFGT, IFLE, IFLT, IFNE, IFNONNULL, IFNULL, IINC, ILOAD, IMUL, INEG, INSTANCEOF, INTEGER, INVOKEINTERFACE, INVOKESPECIAL, INVOKESTATIC, INVOKEVIRTUAL, IOR, IREM, IRETURN, ISHL, ISHR, ISTORE, ISUB, IUSHR, IXOR, JSR, L2D, L2F, L2I, LADD, LALOAD, LAND, LASTORE, LCMP, LCONST_0, LCONST_1, LDC, LDIV, LLOAD, LMUL, LNEG, LONG, LOOKUPSWITCH, LOR, LREM, LRETURN, LSHL, LSHR, LSTORE, LSUB, LUSHR, LXOR, MONITORENTER, MONITOREXIT, MULTIANEWARRAY, NEW, NEWARRAY, NOP, NULL, POP, POP2, PUTFIELD, PUTSTATIC, RET, RETURN, SALOAD, SASTORE, SIPUSH, SWAP, T_BOOLEAN, T_BYTE, T_CHAR, T_DOUBLE, T_FLOAT, T_INT, T_LONG, T_SHORT, TABLESWITCH, TOP, UNINITIALIZED_THIS, V1_1, V1_2, V1_3, V1_4, V1_5, V1_6

Constructor Summary

Analyzer(Interpreter interpreter)
Constructs a new Analyzer.

Method Summary

Frame[]	analyze(java.lang.String owner, MethodNode m) Analyzes the given method.
private void	findSubroutine(int insn, Subroutine sub, java.util.List calls)
Frame[]	getFrames() Returns the symbolic stack frame for each instruction of the last recently analyzed method.
java.util.List	getHandlers(int insn) Returns the exception handlers for the given instruction.
private void	merge(int insn, Frame beforeJSR, Frame afterRET, Subroutine subroutineBeforeJSR, boolean[] access)
private void	merge(int insn, Frame frame, Subroutine subroutine)
protected void	newControlFlowEdge(int insn, int successor) Creates a control flow graph edge.
protected boolean	newControlFlowExceptionEdge(int insn, int successor) Creates a control flow graph edge corresponding to an exception handler.
protected Frame	newFrame(Frame src) Constructs a new frame that is identical to the given frame.
protected Frame	newFrame(int nLocals, int nStack) Constructs a new frame with the given size.

Methods inherited from class java.lang.Object

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

Field Detail

interpreter

private Interpreter interpreter

n

private int n

insns

private InsnList insns

handlers

private java.util.List[] handlers

frames

private Frame[] frames

subroutines

private Subroutine[] subroutines

queued

private boolean[] queued

queue

private int[] queue

top

private int top

Constructor Detail

Analyzer

public Analyzer(Interpreter interpreter)

Constructs a new Analyzer.

Parameters:

interpreter - the interpreter to be used to symbolically interpret the bytecode instructions.

Method Detail

analyze

public Frame[] analyze(java.lang.String owner,
                       MethodNode m)
                throws AnalyzerException

Analyzes the given method.

Parameters:

owner - the internal name of the class to which the method belongs.

m - the method to be analyzed.

Returns:

the symbolic state of the execution stack frame at each bytecode instruction of the method. The size of the returned array is equal to the number of instructions (and labels) of the method. A given frame is null if and only if the corresponding instruction cannot be reached (dead code).

Throws:

AnalyzerException - if a problem occurs during the analysis.

findSubroutine

private void findSubroutine(int insn,
                            Subroutine sub,
                            java.util.List calls)
                     throws AnalyzerException

Throws:

AnalyzerException

getFrames

public Frame[] getFrames()

Returns the symbolic stack frame for each instruction of the last recently analyzed method.

Returns:

the symbolic state of the execution stack frame at each bytecode instruction of the method. The size of the returned array is equal to the number of instructions (and labels) of the method. A given frame is null if the corresponding instruction cannot be reached, or if an error occured during the analysis of the method.

getHandlers

public java.util.List getHandlers(int insn)

Returns the exception handlers for the given instruction.

Parameters:

insn - the index of an instruction of the last recently analyzed method.

Returns:

a list of TryCatchBlockNode objects.

newFrame

protected Frame newFrame(int nLocals,
                         int nStack)

Constructs a new frame with the given size.

Parameters:

nLocals - the maximum number of local variables of the frame.

nStack - the maximum stack size of the frame.

Returns:

the created frame.

newFrame

protected Frame newFrame(Frame src)

Constructs a new frame that is identical to the given frame.

Parameters:

src - a frame.

Returns:

the created frame.

newControlFlowEdge

protected void newControlFlowEdge(int insn,
                                  int successor)

Creates a control flow graph edge. The default implementation of this method does nothing. It can be overriden in order to construct the control flow graph of a method (this method is called by the analyze method during its visit of the method's code).

Parameters:

insn - an instruction index.

successor - index of a successor instruction.

newControlFlowExceptionEdge

protected boolean newControlFlowExceptionEdge(int insn,
                                              int successor)

Creates a control flow graph edge corresponding to an exception handler. The default implementation of this method does nothing. It can be overriden in order to construct the control flow graph of a method (this method is called by the analyze method during its visit of the method's code).

Parameters:

insn - an instruction index.

successor - index of a successor instruction.

Returns:

true if this edge must be considered in the data flow analysis performed by this analyzer, or false otherwise. The default implementation of this method always returns true.

merge

private void merge(int insn,
                   Frame frame,
                   Subroutine subroutine)
            throws AnalyzerException

Throws:

AnalyzerException

merge

private void merge(int insn,
                   Frame beforeJSR,
                   Frame afterRET,
                   Subroutine subroutineBeforeJSR,
                   boolean[] access)
            throws AnalyzerException

Throws:

AnalyzerException