org.plumelib.bcelutil

Class InstructionListUtils

java.lang.Object

org.plumelib.bcelutil.StackMapUtils

org.plumelib.bcelutil.InstructionListUtils

public abstract class InstructionListUtils
extends StackMapUtils

This class provides methods that manipulate BCEL InstructionLists while handling all the StackMap side effects.

BCEL should automatically build and maintain the StackMapTable in a manner similar to the LineNumberTable and the LocalVariableTable. However, for historical reasons it does not.

Field Summary

Fields inherited from class org.plumelib.bcelutil.StackMapUtils

debug_instrument, first_local_index, initial_locals_count, initial_type_list, needStackMap, number_active_locals, pool, running_offset, smta, stack_map_table

Constructor Summary

Constructors

Constructor and Description
InstructionListUtils()

Method Summary

Modifier and Type	Method and Description
protected void	append_inst(org.apache.bcel.generic.InstructionList il, org.apache.bcel.generic.Instruction inst) Appends the specified instruction to the end of the specified list.
protected org.apache.bcel.generic.InstructionList	build_il(org.apache.bcel.generic.Instruction... instructions) Convenience function to build an instruction list
protected org.apache.bcel.classfile.StackMapType[]	calculate_live_local_types(org.apache.bcel.generic.MethodGen mg, int location) Compute the StackMapTypes of the live variables of the current method at a specific location within the method.
protected org.apache.bcel.classfile.StackMapType[]	calculate_live_stack_types(org.apache.bcel.verifier.structurals.OperandStack stack) Compute the StackMapTypes of the items on the execution stack as described by the OperandStack argument.
protected void	insert_at_method_start(org.apache.bcel.generic.MethodGen mg, org.apache.bcel.generic.InstructionList new_il) Inserts an instruction list at the beginning of a method.
protected void	insert_before_handle(org.apache.bcel.generic.MethodGen mg, org.apache.bcel.generic.InstructionHandle ih, org.apache.bcel.generic.InstructionList new_il, boolean redirect_branches) Inserts a new instruction list into an existing instruction list just prior to the indicated instruction handle (which must be a member of the existing instruction list).
protected void	replace_instructions(org.apache.bcel.generic.MethodGen mg, org.apache.bcel.generic.InstructionList il, org.apache.bcel.generic.InstructionHandle ih, org.apache.bcel.generic.InstructionList new_il) Replace instruction ih in list il with the instructions in new_il.

Methods inherited from class org.plumelib.bcelutil.StackMapUtils

add_new_argument, add_string, adjust_code_for_locals_change, bcel_calc_stack_types, build_unitialized_NEW_map, create_method_scope_local, create_new_stack_map_attribute, fetch_current_stack_map_table, find_stack_map_equal, find_stack_map_index_after, find_stack_map_index_before, fix_local_variable_table, gen_temp_locals, generate_StackMapType_from_Type, generate_Type_from_StackMapType, get_attribute_name, get_local_variable_type_table_attribute, get_stack_map_table_attribute, getSize, is_local_variable_type_table, is_stack_map_table, modify_stack_maps_for_switches, print_stack_map_table, remove_local_variable_type_table, typeToClassGetName, update_full_frame_stack_map_entries, update_stack_map_offset, update_uninitialized_NEW_offsets

Methods inherited from class java.lang.Object

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

Constructor Detail

InstructionListUtils

public InstructionListUtils()

Method Detail

append_inst

protected final void append_inst(org.apache.bcel.generic.InstructionList il,
                                 org.apache.bcel.generic.Instruction inst)

Appends the specified instruction to the end of the specified list. Required because for some reason you can't directly append jump instructions to the list -- but you can create new ones and append them.

Parameters:

il - InstructionList to be modified

inst - Instruction to be appended

insert_at_method_start

protected final void insert_at_method_start(org.apache.bcel.generic.MethodGen mg,
                                            org.apache.bcel.generic.InstructionList new_il)

Inserts an instruction list at the beginning of a method.

Parameters:

mg - MethodGen of method to be modified

new_il - InstructionList holding the new code

insert_before_handle

protected final void insert_before_handle(org.apache.bcel.generic.MethodGen mg,
                                          org.apache.bcel.generic.InstructionHandle ih,
                                          org.apache.bcel.generic.InstructionList new_il,
                                          boolean redirect_branches)

Inserts a new instruction list into an existing instruction list just prior to the indicated instruction handle (which must be a member of the existing instruction list). If new_il is null, do nothing.

Parameters:

mg - MethodGen containing the instruction handle

ih - InstructionHandle indicating where to insert new code

new_il - InstructionList holding the new code

redirect_branches - flag indicating if branch targets should be moved from ih to new_il

build_il

protected final org.apache.bcel.generic.InstructionList build_il(org.apache.bcel.generic.Instruction... instructions)

Convenience function to build an instruction list

Parameters:

instructions - a variable number of BCEL instructions

Returns:

an InstructionList

calculate_live_local_types

protected final org.apache.bcel.classfile.StackMapType[] calculate_live_local_types(org.apache.bcel.generic.MethodGen mg,
                                                                                    int location)

Compute the StackMapTypes of the live variables of the current method at a specific location within the method. There may be gaps ("Bogus" or non-live slots) so we can't just count the number of live variables, we must find the max index of all the live variables.

Parameters:

mg - MethodGen for the current method

location - the code location to be evaluated

Returns:

an array of StackMapType describing the live locals at location

calculate_live_stack_types

protected final org.apache.bcel.classfile.StackMapType[] calculate_live_stack_types(org.apache.bcel.verifier.structurals.OperandStack stack)

Compute the StackMapTypes of the items on the execution stack as described by the OperandStack argument.

Parameters:

stack - an OperandStack object

Returns:

an array of StackMapType describing the stack contents

replace_instructions

protected final void replace_instructions(org.apache.bcel.generic.MethodGen mg,
                                          org.apache.bcel.generic.InstructionList il,
                                          org.apache.bcel.generic.InstructionHandle ih,
                                          org.apache.bcel.generic.InstructionList new_il)

Replace instruction ih in list il with the instructions in new_il. If new_il is null, do nothing.

Parameters:

mg - MethodGen containing the instruction handle

il - InstructionList containing ih

ih - InstructionHandle indicating where to insert new code

new_il - InstructionList holding the new code