com.ibm.wala.util.bytecode

Class BytecodeStream

java.lang.Object

com.ibm.wala.util.bytecode.BytecodeStream

All Implemented Interfaces:

com.ibm.wala.shrikeBT.BytecodeConstants

public class BytecodeStream
extends Object
implements com.ibm.wala.shrikeBT.BytecodeConstants

Provides minimal abstraction layer to a stream of bytecodes from the code attribute of a method.

Field Summary

Fields inherited from interface com.ibm.wala.shrikeBT.BytecodeConstants

JBC_aaload, JBC_aastore, JBC_aconst_null, JBC_aload, JBC_aload_0, JBC_aload_1, JBC_aload_2, JBC_aload_3, JBC_anewarray, JBC_areturn, JBC_arraylength, JBC_astore, JBC_astore_0, JBC_astore_1, JBC_astore_2, JBC_astore_3, JBC_athrow, JBC_baload, JBC_bastore, JBC_bipush, JBC_caload, JBC_castore, JBC_checkcast, JBC_d2f, JBC_d2i, JBC_d2l, JBC_dadd, JBC_daload, JBC_dastore, JBC_dcmpg, JBC_dcmpl, JBC_dconst_0, JBC_dconst_1, JBC_ddiv, JBC_dload, JBC_dload_0, JBC_dload_1, JBC_dload_2, JBC_dload_3, JBC_dmul, JBC_dneg, JBC_drem, JBC_dreturn, JBC_dstore, JBC_dstore_0, JBC_dstore_1, JBC_dstore_2, JBC_dstore_3, JBC_dsub, JBC_dup, JBC_dup_x1, JBC_dup_x2, JBC_dup2, JBC_dup2_x1, JBC_dup2_x2, JBC_f2d, JBC_f2i, JBC_f2l, JBC_fadd, JBC_faload, JBC_fastore, JBC_fcmpg, JBC_fcmpl, JBC_fconst_0, JBC_fconst_1, JBC_fconst_2, JBC_fdiv, JBC_fload, JBC_fload_0, JBC_fload_1, JBC_fload_2, JBC_fload_3, JBC_fmul, JBC_fneg, JBC_frem, JBC_freturn, JBC_fstore, JBC_fstore_0, JBC_fstore_1, JBC_fstore_2, JBC_fstore_3, JBC_fsub, JBC_getfield, JBC_getstatic, JBC_goto, JBC_goto_w, JBC_i2d, JBC_i2f, JBC_i2l, JBC_iadd, JBC_iaload, JBC_iand, JBC_iastore, JBC_iconst_0, JBC_iconst_1, JBC_iconst_2, JBC_iconst_3, JBC_iconst_4, JBC_iconst_5, JBC_iconst_m1, JBC_idiv, JBC_if_acmpeq, JBC_if_acmpne, JBC_if_icmpeq, JBC_if_icmpge, JBC_if_icmpgt, JBC_if_icmple, JBC_if_icmplt, JBC_if_icmpne, JBC_ifeq, JBC_ifge, JBC_ifgt, JBC_ifle, JBC_iflt, JBC_ifne, JBC_ifnonnull, JBC_ifnull, JBC_iinc, JBC_iload, JBC_iload_0, JBC_iload_1, JBC_iload_2, JBC_iload_3, JBC_impdep1, JBC_impdep2, JBC_imul, JBC_ineg, JBC_instanceof, JBC_int2byte, JBC_int2char, JBC_int2short, JBC_invokeinterface, JBC_invokespecial, JBC_invokestatic, JBC_invokevirtual, JBC_ior, JBC_irem, JBC_ireturn, JBC_ishl, JBC_ishr, JBC_istore, JBC_istore_0, JBC_istore_1, JBC_istore_2, JBC_istore_3, JBC_isub, JBC_iushr, JBC_ixor, JBC_jsr, JBC_jsr_w, JBC_l2d, JBC_l2f, JBC_l2i, JBC_ladd, JBC_laload, JBC_land, JBC_lastore, JBC_lcmp, JBC_lconst_0, JBC_lconst_1, JBC_ldc, JBC_ldc_w, JBC_ldc2_w, JBC_ldiv, JBC_length, JBC_lload, JBC_lload_0, JBC_lload_1, JBC_lload_2, JBC_lload_3, JBC_lmul, JBC_lneg, JBC_lookupswitch, JBC_lor, JBC_lrem, JBC_lreturn, JBC_lshl, JBC_lshr, JBC_lstore, JBC_lstore_0, JBC_lstore_1, JBC_lstore_2, JBC_lstore_3, JBC_lsub, JBC_lushr, JBC_lxor, JBC_monitorenter, JBC_monitorexit, JBC_multianewarray, JBC_name, JBC_new, JBC_newarray, JBC_nop, JBC_pop, JBC_pop2, JBC_putfield, JBC_putstatic, JBC_ret, JBC_return, JBC_saload, JBC_sastore, JBC_sipush, JBC_swap, JBC_tableswitch, JBC_wide, JBC_xxxunusedxxx

Constructor Summary

Constructors

Constructor and Description
BytecodeStream(IMethod m, byte[] bc)

Method Summary

Methods

Modifier and Type	Method and Description
void	alignInvokeInterface() Skips the extra stuff after an invokeinterface instruction Used for invokeinterface
void	alignSwitch() Skips the padding of a switch instruction Used for tableswitch, lookupswitch
int	computeLookupSwitchOffset(int value, int num) Returns the offset for a given value of the lookupswitch (as a signed int) or 0 if the value is not in the table.
int	computeTableSwitchOffset(int value, int low, int high) Returns the offset for a given value of the tableswitch (as a signed int) or 0 if the value is out of range.
IClass	declaringClass() Returns the declaring class that this bytecode stream is from
int	getArrayDimension() Returns the dimension of the array (as an unsigned byte) Used for multianewarray
int	getArrayElementType() Returns the element type (primitive) of the array (as an unsigned byte) Used for newarray
int	getBranchOffset() Returns the offset of the branch (as a signed short) Used for if, ificmp, ifacmp, goto, jsr
int	getByteValue() Returns a signed byte value Used for bipush
int	getConstantIndex() Returns the constant pool index of a constant (as an unsigned byte) Used for ldc
int	getDefaultSwitchOffset() Returns the default offset of the switch (as a signed int) Used for tableswitch, lookupswitch
int	getHighSwitchValue() Returns the highest value of the tableswitch (as a signed int) Used for tableswitch
int	getIncrement() Returns an increment value (as a signed byte) Used for iinc
int	getLocalNumber() Returns the number of the local (as an unsigned byte) Used for iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc, ret
int	getLookupSwitchOffset(int num) Returns the numbered offset of the lookupswitch (as a signed int) Used for lookupswitch The "cursor" has to be positioned at the start of the pair table NOTE: Will NOT advance cursor
int	getLookupSwitchValue(int num) Returns the numbered value of the lookupswitch (as a signed int) Used for lookupswitch The "cursor" has to be positioned at the start of the pair table NOTE: Will NOT advance cursor
int	getLowSwitchValue() Returns the lowest value of the tableswitch (as a signed int) Used for tableswitch
int	getOpcode() Returns the opcode of the current instruction in the sequence Note: if skipInstruction has been called, but nextInstruction has not, this method will return the opcode of the skipped instruction!
int	getShortValue() Returns a signed short value Used for sipush
int	getSwitchLength() Returns the number of match-offset pairs in the lookupswitch (as a signed int) Used for lookupswitch
int	getTableSwitchOffset(int num) Returns the numbered offset of the tableswitch (as a signed int) Used for tableswitch The "cursor" has to be positioned at the start of the offset table NOTE: Will NOT advance cursor
int	getWideBranchOffset() Returns the wide offset of the branch (as a signed int) Used for goto_w, jsr_w
int	getWideConstantIndex() Returns the wide constant pool index of a constant (as an unsigned short) Used for ldc_w, ldc2_w
int	getWideIncrement() Returns an increment value (as a signed short) Used for iinc prefixed by wide
int	getWideLocalNumber() Returns the wide number of the local (as an unsigned short) Used for iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc prefixed by wide
int	getWideOpcode() Returns the opcode of the wide instruction Used for wide Can be one of iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc
boolean	hasMoreBytecodes() Does the stream have more bytecodes in it?
int	index() Returns the current bytecode index
boolean	isWide() Are we currently processing a wide instruction?
int	length() Returns the length of the bytecode stream Returns 0 if the method doesn't have any bytecodes (i.e.
IMethod	method() Returns the method that this bytecode stream is from
int	nextInstruction() Sets up the next instruction in the sequence
int	peekNextOpcode() Returns the opcode of the next instruction in the sequence without advancing to it
void	reset() Resets the stream to the beginning
void	reset(int index) Resets the stream to a given position Use with caution
void	skipInstruction() Skips the current instruction
void	skipInstruction(int opc, boolean w) Skips the current instruction (without using the opcode field) A slightly optimized version of skipInstruction()
void	skipLookupSwitchPairs(int num) Skips the match-offset pairs of a lookupswitch instruction Used for lookupswitch
void	skipTableSwitchOffsets(int num) Skips the offsets of a tableswitch instruction Used for tableswitch

Methods inherited from class java.lang.Object

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

Constructor Detail

BytecodeStream

public BytecodeStream(IMethod m,
              byte[] bc)

Parameters:

m - the method containing the bytecodes

bc - the array of bytecodes

Throws:

IllegalArgumentException - if bc is null

IllegalArgumentException - if m is null

Method Detail

method

public final IMethod method()

Returns the method that this bytecode stream is from

declaringClass

public final IClass declaringClass()

Returns the declaring class that this bytecode stream is from

length

public final int length()

Returns the length of the bytecode stream Returns 0 if the method doesn't have any bytecodes (i.e. is abstract or native)

index

public final int index()

Returns the current bytecode index

reset

public final void reset()

Resets the stream to the beginning

reset

public final void reset(int index)

Resets the stream to a given position Use with caution

Parameters:

index - the position to reset the stream to

hasMoreBytecodes

public final boolean hasMoreBytecodes()

Does the stream have more bytecodes in it?

peekNextOpcode

public final int peekNextOpcode()

Returns the opcode of the next instruction in the sequence without advancing to it

Returns:

the opcode of the next instruction

See Also:

nextInstruction()

nextInstruction

public final int nextInstruction()

Sets up the next instruction in the sequence

Returns:

the opcode of the next instruction

See Also:

peekNextOpcode()

getOpcode

public final int getOpcode()

Returns the opcode of the current instruction in the sequence Note: if skipInstruction has been called, but nextInstruction has not, this method will return the opcode of the skipped instruction!

Returns:

the opcode of the current instruction

See Also:

nextInstruction(), isWide()

isWide

public final boolean isWide()

Are we currently processing a wide instruction?

Returns:

true if current instruction is wide

See Also:

nextInstruction(), getOpcode()

skipInstruction

public final void skipInstruction()

Skips the current instruction

See Also:

skipInstruction(int,boolean)

skipInstruction

public final void skipInstruction(int opc,
                   boolean w)

Skips the current instruction (without using the opcode field) A slightly optimized version of skipInstruction()

Parameters:

opc - current opcode

w - whether current instruction follows wide

See Also:

skipInstruction()

getByteValue

public final int getByteValue()

Returns a signed byte value Used for bipush

Returns:

signed byte value

getShortValue

public final int getShortValue()

Returns a signed short value Used for sipush

Returns:

signed short value

getLocalNumber

public final int getLocalNumber()

Returns the number of the local (as an unsigned byte) Used for iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc, ret

Returns:

local number

See Also:

getWideLocalNumber()

getWideLocalNumber

public final int getWideLocalNumber()

Returns the wide number of the local (as an unsigned short) Used for iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc prefixed by wide

Returns:

wide local number

See Also:

getLocalNumber()

getIncrement

public final int getIncrement()

Returns an increment value (as a signed byte) Used for iinc

Returns:

increment

See Also:

getWideIncrement()

getWideIncrement

public final int getWideIncrement()

Returns an increment value (as a signed short) Used for iinc prefixed by wide

Returns:

wide increment

See Also:

getIncrement()

getBranchOffset

public final int getBranchOffset()

Returns the offset of the branch (as a signed short) Used for if, ificmp, ifacmp, goto, jsr

Returns:

branch offset

See Also:

getWideBranchOffset()

getWideBranchOffset

public final int getWideBranchOffset()

Returns the wide offset of the branch (as a signed int) Used for goto_w, jsr_w

Returns:

wide branch offset

See Also:

getBranchOffset()

alignSwitch

public final void alignSwitch()

Skips the padding of a switch instruction Used for tableswitch, lookupswitch

getDefaultSwitchOffset

public final int getDefaultSwitchOffset()

Returns the default offset of the switch (as a signed int) Used for tableswitch, lookupswitch

Returns:

default switch offset

getLowSwitchValue

public final int getLowSwitchValue()

Returns the lowest value of the tableswitch (as a signed int) Used for tableswitch

Returns:

lowest switch value

See Also:

getHighSwitchValue()

getHighSwitchValue

public final int getHighSwitchValue()

Returns the highest value of the tableswitch (as a signed int) Used for tableswitch

Returns:

highest switch value

See Also:

getLowSwitchValue()

skipTableSwitchOffsets

public final void skipTableSwitchOffsets(int num)

Skips the offsets of a tableswitch instruction Used for tableswitch

Parameters:

num - the number of offsets to skip

See Also:

getTableSwitchOffset(int)

getTableSwitchOffset

public final int getTableSwitchOffset(int num)

Returns the numbered offset of the tableswitch (as a signed int) Used for tableswitch The "cursor" has to be positioned at the start of the offset table NOTE: Will NOT advance cursor

Parameters:

num - the number of the offset to retrieve

Returns:

switch offset

computeTableSwitchOffset

public final int computeTableSwitchOffset(int value,
                           int low,
                           int high)

Returns the offset for a given value of the tableswitch (as a signed int) or 0 if the value is out of range. Used for tableswitch The "cursor" has to be positioned at the start of the offset table NOTE: Will NOT advance cursor

Parameters:

value - the value to retrieve offset for

low - the lowest value of the tableswitch

high - the highest value of the tableswitch

Returns:

switch offset

getSwitchLength

public final int getSwitchLength()

Returns the number of match-offset pairs in the lookupswitch (as a signed int) Used for lookupswitch

Returns:

number of switch pairs

skipLookupSwitchPairs

public final void skipLookupSwitchPairs(int num)

Skips the match-offset pairs of a lookupswitch instruction Used for lookupswitch

Parameters:

num - the number of match-offset pairs to skip

See Also:

getLookupSwitchValue(int), getLookupSwitchOffset(int)

getLookupSwitchOffset

public final int getLookupSwitchOffset(int num)

Returns the numbered offset of the lookupswitch (as a signed int) Used for lookupswitch The "cursor" has to be positioned at the start of the pair table NOTE: Will NOT advance cursor

Parameters:

num - the number of the offset to retrieve

Returns:

switch offset

See Also:

getLookupSwitchValue(int)

getLookupSwitchValue

public final int getLookupSwitchValue(int num)

Returns the numbered value of the lookupswitch (as a signed int) Used for lookupswitch The "cursor" has to be positioned at the start of the pair table NOTE: Will NOT advance cursor

Parameters:

num - the number of the value to retrieve

Returns:

switch value

See Also:

getLookupSwitchOffset(int)

computeLookupSwitchOffset

public final int computeLookupSwitchOffset(int value,
                            int num)

Returns the offset for a given value of the lookupswitch (as a signed int) or 0 if the value is not in the table. Used for lookupswitch The "cursor" has to be positioned at the start of the offset table NOTE: Will NOT advance cursor WARNING: Uses LINEAR search. Whoever has time on their hands can re-implement this as a binary search.

Parameters:

value - the value to retrieve offset for

num - the number of match-offset pairs in the lookupswitch

Returns:

switch offset

alignInvokeInterface

public final void alignInvokeInterface()

Skips the extra stuff after an invokeinterface instruction Used for invokeinterface

getArrayElementType

public final int getArrayElementType()

Returns the element type (primitive) of the array (as an unsigned byte) Used for newarray

Returns:

array element type

getArrayDimension

public final int getArrayDimension()

Returns the dimension of the array (as an unsigned byte) Used for multianewarray

Returns:

array dimension

getWideOpcode

public final int getWideOpcode()

Returns the opcode of the wide instruction Used for wide Can be one of iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc

Returns:

the opcode of the wide instruction

getConstantIndex

public final int getConstantIndex()

Returns the constant pool index of a constant (as an unsigned byte) Used for ldc

Returns:

constant index

See Also:

getWideConstantIndex()

getWideConstantIndex

public final int getWideConstantIndex()

Returns the wide constant pool index of a constant (as an unsigned short) Used for ldc_w, ldc2_w

Returns:

wide constant index

See Also:

getConstantIndex()