/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.bcel.generic;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import org.apache.bcel.Const;
import org.apache.bcel.classfile.Constant;
import org.apache.bcel.util.ByteSequence;
/**
* This class is a container for a list of Instruction objects. Instructions can be appended, inserted, moved, deleted, etc..
* Instructions are being wrapped into InstructionHandles objects that are returned upon append/insert operations. They
* give the user (read only) access to the list structure, such that it can be traversed and manipulated in a controlled way.
*
* A list is finally dumped to a byte code array with getByteCode.
*
* @see Instruction
* @see InstructionHandle
* @see BranchHandle
*/
public class InstructionList implements Iterable {
private InstructionHandle start = null;
private InstructionHandle end = null;
private int length = 0; // number of elements in list
private int[] bytePositions; // byte code offsets corresponding to instructions
/**
* Create (empty) instruction list.
*/
public InstructionList() {
}
/**
* Create instruction list containing one instruction.
*
* @param i
* initial instruction
*/
public InstructionList(final Instruction i) {
append(i);
}
/**
* Create instruction list containing one instruction.
*
* @param i
* initial instruction
*/
public InstructionList(final BranchInstruction i) {
append(i);
}
/**
* Initialize list with (nonnull) compound instruction. Consumes argument list, i.e., it becomes empty.
*
* @param c
* compound instruction (list)
*/
public InstructionList(final CompoundInstruction c) {
append(c.getInstructionList());
}
/**
* Test for empty list.
*/
public boolean isEmpty() {
return start == null;
} // && end == null
/**
* Find the target instruction (handle) that corresponds to the given target position (byte code offset).
*
* @param ihs
* array of instruction handles, i.e. il.getInstructionHandles()
* @param pos
* array of positions corresponding to ihs, i.e. il.getInstructionPositions()
* @param count
* length of arrays
* @param target
* target position to search for
* @return target position's instruction handle if available
*/
public static InstructionHandle findHandle(final InstructionHandle[] ihs, final int[] pos, final int count, final int target) {
int l = 0;
int r = count - 1;
/*
* Do a binary search since the pos array is orderd.
*/
do {
final int i = (l + r) >>> 1;
final int j = pos[i];
if (j == target) {
return ihs[i];
} else if (target < j) {
r = i - 1;
} else {
l = i + 1;
}
} while (l <= r);
return null;
}
/**
* Get instruction handle for instruction at byte code position pos. This only works properly, if the list is freshly initialized from a byte array or
* setPositions() has been called before this method.
*
* @param pos
* byte code position to search for
* @return target position's instruction handle if available
*/
public InstructionHandle findHandle(final int pos) {
final int[] positions = bytePositions;
InstructionHandle ih = start;
for (int i = 0; i < length; i++) {
if (positions[i] == pos) {
return ih;
}
ih = ih.getNext();
}
return null;
}
/**
* Initialize instruction list from byte array.
*
* @param code
* byte array containing the instructions
*/
public InstructionList(final byte[] code) {
int count = 0; // Contains actual length
int[] pos;
InstructionHandle[] ihs;
try (ByteSequence bytes = new ByteSequence(code)) {
ihs = new InstructionHandle[code.length];
pos = new int[code.length]; // Can't be more than that
/*
* Pass 1: Create an object for each byte code and append them to the list.
*/
while (bytes.available() > 0) {
// Remember byte offset and associate it with the instruction
final int off = bytes.getIndex();
pos[count] = off;
/*
* Read one instruction from the byte stream, the byte position is set accordingly.
*/
final Instruction i = Instruction.readInstruction(bytes);
InstructionHandle ih;
if (i instanceof BranchInstruction) {
ih = append((BranchInstruction) i);
} else {
ih = append(i);
}
ih.setPosition(off);
ihs[count] = ih;
count++;
}
} catch (final IOException e) {
throw new ClassGenException(e.toString(), e);
}
bytePositions = new int[count]; // Trim to proper size
System.arraycopy(pos, 0, bytePositions, 0, count);
/*
* Pass 2: Look for BranchInstruction and update their targets, i.e., convert offsets to instruction handles.
*/
for (int i = 0; i < count; i++) {
if (ihs[i] instanceof BranchHandle) {
final BranchInstruction bi = (BranchInstruction) ihs[i].getInstruction();
int target = bi.getPosition() + bi.getIndex(); /*
* Byte code position: relative -> absolute.
*/
// Search for target position
InstructionHandle ih = findHandle(ihs, pos, count, target);
if (ih == null) {
throw new ClassGenException("Couldn't find target for branch: " + bi);
}
bi.setTarget(ih); // Update target
// If it is a Select instruction, update all branch targets
if (bi instanceof Select) { // Either LOOKUPSWITCH or TABLESWITCH
final Select s = (Select) bi;
final int[] indices = s.getIndices();
for (int j = 0; j < indices.length; j++) {
target = bi.getPosition() + indices[j];
ih = findHandle(ihs, pos, count, target);
if (ih == null) {
throw new ClassGenException("Couldn't find target for switch: " + bi);
}
s.setTarget(j, ih); // Update target
}
}
}
}
}
/**
* Append another list after instruction (handle) ih contained in this list. Consumes argument list, i.e., it becomes empty.
*
* @param ih
* where to append the instruction list
* @param il
* Instruction list to append to this one
* @return instruction handle pointing to the first appended instruction
*/
public InstructionHandle append(final InstructionHandle ih, final InstructionList il) {
if (il == null) {
throw new ClassGenException("Appending null InstructionList");
}
if (il.isEmpty()) {
return ih;
}
final InstructionHandle next = ih.getNext();
final InstructionHandle ret = il.start;
ih.setNext(il.start);
il.start.setPrev(ih);
il.end.setNext(next);
if (next != null) {
next.setPrev(il.end);
} else {
end = il.end; // Update end ...
}
length += il.length; // Update length
il.clear();
return ret;
}
/**
* Append another list after instruction i contained in this list. Consumes argument list, i.e., it becomes empty.
*
* @param i
* where to append the instruction list
* @param il
* Instruction list to append to this one
* @return instruction handle pointing to the first appended instruction
*/
public InstructionHandle append(final Instruction i, final InstructionList il) {
InstructionHandle ih;
if ((ih = findInstruction2(i)) == null) {
throw new ClassGenException("Instruction " + i + " is not contained in this list.");
}
return append(ih, il);
}
/**
* Append another list to this one. Consumes argument list, i.e., it becomes empty.
*
* @param il
* list to append to end of this list
* @return instruction handle of the first appended instruction
*/
public InstructionHandle append(final InstructionList il) {
if (il == null) {
throw new ClassGenException("Appending null InstructionList");
}
if (il.isEmpty()) {
return null;
}
if (isEmpty()) {
start = il.start;
end = il.end;
length = il.length;
il.clear();
return start;
}
return append(end, il); // was end.instruction
}
/**
* Append an instruction to the end of this list.
*
* @param ih
* instruction to append
*/
private void append(final InstructionHandle ih) {
if (isEmpty()) {
start = end = ih;
ih.setNext(ih.setPrev(null));
} else {
end.setNext(ih);
ih.setPrev(end);
ih.setNext(null);
end = ih;
}
length++; // Update length
}
/**
* Append an instruction to the end of this list.
*
* @param i
* instruction to append
* @return instruction handle of the appended instruction
*/
public InstructionHandle append(final Instruction i) {
final InstructionHandle ih = InstructionHandle.getInstructionHandle(i);
append(ih);
return ih;
}
/**
* Append a branch instruction to the end of this list.
*
* @param i
* branch instruction to append
* @return branch instruction handle of the appended instruction
*/
public BranchHandle append(final BranchInstruction i) {
final BranchHandle ih = BranchHandle.getBranchHandle(i);
append(ih);
return ih;
}
/**
* Append a single instruction j after another instruction i, which must be in this list of course!
*
* @param i
* Instruction in list
* @param j
* Instruction to append after i in list
* @return instruction handle of the first appended instruction
*/
public InstructionHandle append(final Instruction i, final Instruction j) {
return append(i, new InstructionList(j));
}
/**
* Append a compound instruction, after instruction i.
*
* @param i
* Instruction in list
* @param c
* The composite instruction (containing an InstructionList)
* @return instruction handle of the first appended instruction
*/
public InstructionHandle append(final Instruction i, final CompoundInstruction c) {
return append(i, c.getInstructionList());
}
/**
* Append a compound instruction.
*
* @param c
* The composite instruction (containing an InstructionList)
* @return instruction handle of the first appended instruction
*/
public InstructionHandle append(final CompoundInstruction c) {
return append(c.getInstructionList());
}
/**
* Append a compound instruction.
*
* @param ih
* where to append the instruction list
* @param c
* The composite instruction (containing an InstructionList)
* @return instruction handle of the first appended instruction
*/
public InstructionHandle append(final InstructionHandle ih, final CompoundInstruction c) {
return append(ih, c.getInstructionList());
}
/**
* Append an instruction after instruction (handle) ih contained in this list.
*
* @param ih
* where to append the instruction list
* @param i
* Instruction to append
* @return instruction handle pointing to the first appended instruction
*/
public InstructionHandle append(final InstructionHandle ih, final Instruction i) {
return append(ih, new InstructionList(i));
}
/**
* Append an instruction after instruction (handle) ih contained in this list.
*
* @param ih
* where to append the instruction list
* @param i
* Instruction to append
* @return instruction handle pointing to the first appended instruction
*/
public BranchHandle append(final InstructionHandle ih, final BranchInstruction i) {
final BranchHandle bh = BranchHandle.getBranchHandle(i);
final InstructionList il = new InstructionList();
il.append(bh);
append(ih, il);
return bh;
}
/**
* Insert another list before Instruction handle ih contained in this list. Consumes argument list, i.e., it becomes empty.
*
* @param ih
* where to append the instruction list
* @param il
* Instruction list to insert
* @return instruction handle of the first inserted instruction
*/
public InstructionHandle insert(final InstructionHandle ih, final InstructionList il) {
if (il == null) {
throw new ClassGenException("Inserting null InstructionList");
}
if (il.isEmpty()) {
return ih;
}
final InstructionHandle prev = ih.getPrev();
final InstructionHandle ret = il.start;
ih.setPrev(il.end);
il.end.setNext(ih);
il.start.setPrev(prev);
if (prev != null) {
prev.setNext(il.start);
} else {
start = il.start; // Update start ...
}
length += il.length; // Update length
il.clear();
return ret;
}
/**
* Insert another list.
*
* @param il
* list to insert before start of this list
* @return instruction handle of the first inserted instruction
*/
public InstructionHandle insert(final InstructionList il) {
if (isEmpty()) {
append(il); // Code is identical for this case
return start;
}
return insert(start, il);
}
/**
* Insert an instruction at start of this list.
*
* @param ih
* instruction to insert
*/
private void insert(final InstructionHandle ih) {
if (isEmpty()) {
start = end = ih;
ih.setNext(ih.setPrev(null));
} else {
start.setPrev(ih);
ih.setNext(start);
ih.setPrev(null);
start = ih;
}
length++;
}
/**
* Insert another list before Instruction i contained in this list. Consumes argument list, i.e., it becomes empty.
*
* @param i
* where to append the instruction list
* @param il
* Instruction list to insert
* @return instruction handle pointing to the first inserted instruction, i.e., il.getStart()
*/
public InstructionHandle insert(final Instruction i, final InstructionList il) {
InstructionHandle ih;
if ((ih = findInstruction1(i)) == null) {
throw new ClassGenException("Instruction " + i + " is not contained in this list.");
}
return insert(ih, il);
}
/**
* Insert an instruction at start of this list.
*
* @param i
* instruction to insert
* @return instruction handle of the inserted instruction
*/
public InstructionHandle insert(final Instruction i) {
final InstructionHandle ih = InstructionHandle.getInstructionHandle(i);
insert(ih);
return ih;
}
/**
* Insert a branch instruction at start of this list.
*
* @param i
* branch instruction to insert
* @return branch instruction handle of the appended instruction
*/
public BranchHandle insert(final BranchInstruction i) {
final BranchHandle ih = BranchHandle.getBranchHandle(i);
insert(ih);
return ih;
}
/**
* Insert a single instruction j before another instruction i, which must be in this list of course!
*
* @param i
* Instruction in list
* @param j
* Instruction to insert before i in list
* @return instruction handle of the first inserted instruction
*/
public InstructionHandle insert(final Instruction i, final Instruction j) {
return insert(i, new InstructionList(j));
}
/**
* Insert a compound instruction before instruction i.
*
* @param i
* Instruction in list
* @param c
* The composite instruction (containing an InstructionList)
* @return instruction handle of the first inserted instruction
*/
public InstructionHandle insert(final Instruction i, final CompoundInstruction c) {
return insert(i, c.getInstructionList());
}
/**
* Insert a compound instruction.
*
* @param c
* The composite instruction (containing an InstructionList)
* @return instruction handle of the first inserted instruction
*/
public InstructionHandle insert(final CompoundInstruction c) {
return insert(c.getInstructionList());
}
/**
* Insert an instruction before instruction (handle) ih contained in this list.
*
* @param ih
* where to insert to the instruction list
* @param i
* Instruction to insert
* @return instruction handle of the first inserted instruction
*/
public InstructionHandle insert(final InstructionHandle ih, final Instruction i) {
return insert(ih, new InstructionList(i));
}
/**
* Insert a compound instruction.
*
* @param ih
* where to insert the instruction list
* @param c
* The composite instruction (containing an InstructionList)
* @return instruction handle of the first inserted instruction
*/
public InstructionHandle insert(final InstructionHandle ih, final CompoundInstruction c) {
return insert(ih, c.getInstructionList());
}
/**
* Insert an instruction before instruction (handle) ih contained in this list.
*
* @param ih
* where to insert to the instruction list
* @param i
* Instruction to insert
* @return instruction handle of the first inserted instruction
*/
public BranchHandle insert(final InstructionHandle ih, final BranchInstruction i) {
final BranchHandle bh = BranchHandle.getBranchHandle(i);
final InstructionList il = new InstructionList();
il.append(bh);
insert(ih, il);
return bh;
}
/**
* Take all instructions (handles) from "start" to "end" and append them after the new location "target". Of course, "end" must be after "start" and target
* must not be located withing this range. If you want to move something to the start of the list use null as value for target.
*
* Any instruction targeters pointing to handles within the block, keep their targets.
*
*
* @param start
* of moved block
* @param end
* of moved block
* @param target
* of moved block
*/
public void move(final InstructionHandle start, final InstructionHandle end, final InstructionHandle target) {
// Step 1: Check constraints
if ((start == null) || (end == null)) {
throw new ClassGenException("Invalid null handle: From " + start + " to " + end);
}
if ((target == start) || (target == end)) {
throw new ClassGenException("Invalid range: From " + start + " to " + end + " contains target " + target);
}
for (InstructionHandle ih = start; ih != end.getNext(); ih = ih.getNext()) {
if (ih == null) {
throw new ClassGenException("Invalid range: From " + start + " to " + end);
} else if (ih == target) {
throw new ClassGenException("Invalid range: From " + start + " to " + end + " contains target " + target);
}
}
// Step 2: Temporarily remove the given instructions from the list
final InstructionHandle prev = start.getPrev();
InstructionHandle next = end.getNext();
if (prev != null) {
prev.setNext(next);
} else {
this.start = next;
}
if (next != null) {
next.setPrev(prev);
} else {
this.end = prev;
}
start.setPrev(end.setNext(null));
// Step 3: append after target
if (target == null) { // append to start of list
if (this.start != null) {
this.start.setPrev(end);
}
end.setNext(this.start);
this.start = start;
} else {
next = target.getNext();
target.setNext(start);
start.setPrev(target);
end.setNext(next);
if (next != null) {
next.setPrev(end);
} else {
this.end = end;
}
}
}
/**
* Move a single instruction (handle) to a new location.
*
* @param ih
* moved instruction
* @param target
* new location of moved instruction
*/
public void move(final InstructionHandle ih, final InstructionHandle target) {
move(ih, ih, target);
}
/**
* Remove from instruction `prev' to instruction `next' both contained in this list. Throws TargetLostException when one of the removed instruction handles
* is still being targeted.
*
* @param prev
* where to start deleting (predecessor, exclusive)
* @param next
* where to end deleting (successor, exclusive)
*/
private void remove(final InstructionHandle prev, InstructionHandle next) throws TargetLostException {
InstructionHandle first;
InstructionHandle last; // First and last deleted instruction
if ((prev == null) && (next == null)) {
first = start;
last = end;
start = end = null;
} else {
if (prev == null) { // At start of list
first = start;
start = next;
} else {
first = prev.getNext();
prev.setNext(next);
}
if (next == null) { // At end of list
last = end;
end = prev;
} else {
last = next.getPrev();
next.setPrev(prev);
}
}
first.setPrev(null); // Completely separated from rest of list
last.setNext(null);
final List target_vec = new ArrayList<>();
for (InstructionHandle ih = first; ih != null; ih = ih.getNext()) {
ih.getInstruction().dispose(); // e.g. BranchInstructions release their targets
}
final StringBuilder buf = new StringBuilder("{ ");
for (InstructionHandle ih = first; ih != null; ih = next) {
next = ih.getNext();
length--;
if (ih.hasTargeters()) { // Still got targeters?
target_vec.add(ih);
buf.append(ih.toString(true)).append(" ");
ih.setNext(ih.setPrev(null));
} else {
ih.dispose();
}
}
buf.append("}");
if (!target_vec.isEmpty()) {
final InstructionHandle[] targeted = new InstructionHandle[target_vec.size()];
target_vec.toArray(targeted);
throw new TargetLostException(targeted, buf.toString());
}
}
/**
* Remove instruction from this list. The corresponding Instruction handles must not be reused!
*
* @param ih
* instruction (handle) to remove
*/
public void delete(final InstructionHandle ih) throws TargetLostException {
remove(ih.getPrev(), ih.getNext());
}
/**
* Remove instruction from this list. The corresponding Instruction handles must not be reused!
*
* @param i
* instruction to remove
*/
public void delete(final Instruction i) throws TargetLostException {
InstructionHandle ih;
if ((ih = findInstruction1(i)) == null) {
throw new ClassGenException("Instruction " + i + " is not contained in this list.");
}
delete(ih);
}
/**
* Remove instructions from instruction `from' to instruction `to' contained in this list. The user must ensure that `from' is an instruction before `to',
* or risk havoc. The corresponding Instruction handles must not be reused!
*
* @param from
* where to start deleting (inclusive)
* @param to
* where to end deleting (inclusive)
*/
public void delete(final InstructionHandle from, final InstructionHandle to) throws TargetLostException {
remove(from.getPrev(), to.getNext());
}
/**
* Remove instructions from instruction `from' to instruction `to' contained in this list. The user must ensure that `from' is an instruction before `to',
* or risk havoc. The corresponding Instruction handles must not be reused!
*
* @param from
* where to start deleting (inclusive)
* @param to
* where to end deleting (inclusive)
*/
public void delete(final Instruction from, final Instruction to) throws TargetLostException {
InstructionHandle from_ih;
InstructionHandle to_ih;
if ((from_ih = findInstruction1(from)) == null) {
throw new ClassGenException("Instruction " + from + " is not contained in this list.");
}
if ((to_ih = findInstruction2(to)) == null) {
throw new ClassGenException("Instruction " + to + " is not contained in this list.");
}
delete(from_ih, to_ih);
}
/**
* Search for given Instruction reference, start at beginning of list.
*
* @param i
* instruction to search for
* @return instruction found on success, null otherwise
*/
private InstructionHandle findInstruction1(final Instruction i) {
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
if (ih.getInstruction() == i) {
return ih;
}
}
return null;
}
/**
* Search for given Instruction reference, start at end of list
*
* @param i
* instruction to search for
* @return instruction found on success, null otherwise
*/
private InstructionHandle findInstruction2(final Instruction i) {
for (InstructionHandle ih = end; ih != null; ih = ih.getPrev()) {
if (ih.getInstruction() == i) {
return ih;
}
}
return null;
}
public boolean contains(final InstructionHandle i) {
if (i == null) {
return false;
}
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
if (ih == i) {
return true;
}
}
return false;
}
public boolean contains(final Instruction i) {
return findInstruction1(i) != null;
}
public void setPositions() { // TODO could be package-protected? (some test code would need to be repackaged)
setPositions(false);
}
/**
* Give all instructions their position number (offset in byte stream), i.e., make the list ready to be dumped.
*
* @param check
* Perform sanity checks, e.g. if all targeted instructions really belong to this list
*/
public void setPositions(final boolean check) { // called by code in other packages
int max_additional_bytes = 0;
int additional_bytes = 0;
int index = 0;
int count = 0;
final int[] pos = new int[length];
/*
* Pass 0: Sanity checks
*/
if (check) {
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
final Instruction i = ih.getInstruction();
if (i instanceof BranchInstruction) { // target instruction within list?
Instruction inst = ((BranchInstruction) i).getTarget().getInstruction();
if (!contains(inst)) {
throw new ClassGenException("Branch target of " + Const.getOpcodeName(i.getOpcode()) + ":" + inst + " not in instruction list");
}
if (i instanceof Select) {
final InstructionHandle[] targets = ((Select) i).getTargets();
for (final InstructionHandle target : targets) {
inst = target.getInstruction();
if (!contains(inst)) {
throw new ClassGenException("Branch target of " + Const.getOpcodeName(i.getOpcode()) + ":" + inst + " not in instruction list");
}
}
}
if (!(ih instanceof BranchHandle)) {
throw new ClassGenException(
"Branch instruction " + Const.getOpcodeName(i.getOpcode()) + ":" + inst + " not contained in BranchHandle.");
}
}
}
}
/*
* Pass 1: Set position numbers and sum up the maximum number of bytes an instruction may be shifted.
*/
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
final Instruction i = ih.getInstruction();
ih.setPosition(index);
pos[count++] = index;
/*
* Get an estimate about how many additional bytes may be added, because BranchInstructions may have variable length depending on the target offset
* (short vs. int) or alignment issues (TABLESWITCH and LOOKUPSWITCH).
*/
switch (i.getOpcode()) {
case Const.JSR:
case Const.GOTO:
max_additional_bytes += 2;
break;
case Const.TABLESWITCH:
case Const.LOOKUPSWITCH:
max_additional_bytes += 3;
break;
}
index += i.getLength();
}
/*
* Pass 2: Expand the variable-length (Branch)Instructions depending on the target offset (short or int) and ensure that branch targets are within this
* list.
*/
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
additional_bytes += ih.updatePosition(additional_bytes, max_additional_bytes);
}
/*
* Pass 3: Update position numbers (which may have changed due to the preceding expansions), like pass 1.
*/
index = count = 0;
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
final Instruction i = ih.getInstruction();
ih.setPosition(index);
pos[count++] = index;
index += i.getLength();
}
bytePositions = new int[count]; // Trim to proper size
System.arraycopy(pos, 0, bytePositions, 0, count);
}
/**
* When everything is finished, use this method to convert the instruction list into an array of bytes.
*
* @return the byte code ready to be dumped
*/
public byte[] getByteCode() {
// Update position indices of instructions
setPositions();
final ByteArrayOutputStream b = new ByteArrayOutputStream();
final DataOutputStream out = new DataOutputStream(b);
try {
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
final Instruction i = ih.getInstruction();
i.dump(out); // Traverse list
}
out.flush();
} catch (final IOException e) {
System.err.println(e);
return new byte[0];
}
return b.toByteArray();
}
/**
* @return an array of instructions without target information for branch instructions.
*/
public Instruction[] getInstructions() {
final List instructions = new ArrayList<>();
try (ByteSequence bytes = new ByteSequence(getByteCode())) {
while (bytes.available() > 0) {
instructions.add(Instruction.readInstruction(bytes));
}
} catch (final IOException e) {
throw new ClassGenException(e.toString(), e);
}
return instructions.toArray(new Instruction[instructions.size()]);
}
@Override
public String toString() {
return toString(true);
}
/**
* @param verbose
* toggle output format
* @return String containing all instructions in this list.
*/
public String toString(final boolean verbose) {
final StringBuilder buf = new StringBuilder();
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
buf.append(ih.toString(verbose)).append("\n");
}
return buf.toString();
}
/**
* @return iterator that lists all instructions (handles)
*/
@Override
public Iterator iterator() {
return new Iterator() {
private InstructionHandle ih = start;
@Override
public InstructionHandle next() throws NoSuchElementException {
if (ih == null) {
throw new NoSuchElementException();
}
final InstructionHandle i = ih;
ih = ih.getNext();
return i;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
@Override
public boolean hasNext() {
return ih != null;
}
};
}
/**
* @return array containing all instructions (handles)
*/
public InstructionHandle[] getInstructionHandles() {
final InstructionHandle[] ihs = new InstructionHandle[length];
InstructionHandle ih = start;
for (int i = 0; i < length; i++) {
ihs[i] = ih;
ih = ih.getNext();
}
return ihs;
}
/**
* Get positions (offsets) of all instructions in the list. This relies on that the list has been freshly created from an byte code array, or that
* setPositions() has been called. Otherwise this may be inaccurate.
*
* @return array containing all instruction's offset in byte code
*/
public int[] getInstructionPositions() {
return bytePositions;
}
/**
* @return complete, i.e., deep copy of this list
*/
public InstructionList copy() {
final Map map = new HashMap<>();
final InstructionList il = new InstructionList();
/*
* Pass 1: Make copies of all instructions, append them to the new list and associate old instruction references with the new ones, i.e., a 1:1 mapping.
*/
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
final Instruction i = ih.getInstruction();
final Instruction c = i.copy(); // Use clone for shallow copy
if (c instanceof BranchInstruction) {
map.put(ih, il.append((BranchInstruction) c));
} else {
map.put(ih, il.append(c));
}
}
/*
* Pass 2: Update branch targets.
*/
InstructionHandle ih = start;
InstructionHandle ch = il.start;
while (ih != null) {
final Instruction i = ih.getInstruction();
final Instruction c = ch.getInstruction();
if (i instanceof BranchInstruction) {
final BranchInstruction bi = (BranchInstruction) i;
final BranchInstruction bc = (BranchInstruction) c;
final InstructionHandle itarget = bi.getTarget(); // old target
// New target is in hash map
bc.setTarget(map.get(itarget));
if (bi instanceof Select) { // Either LOOKUPSWITCH or TABLESWITCH
final InstructionHandle[] itargets = ((Select) bi).getTargets();
final InstructionHandle[] ctargets = ((Select) bc).getTargets();
for (int j = 0; j < itargets.length; j++) { // Update all targets
ctargets[j] = map.get(itargets[j]);
}
}
}
ih = ih.getNext();
ch = ch.getNext();
}
return il;
}
/**
* Replace all references to the old constant pool with references to the new constant pool
*/
public void replaceConstantPool(final ConstantPoolGen old_cp, final ConstantPoolGen new_cp) {
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
final Instruction i = ih.getInstruction();
if (i instanceof CPInstruction) {
final CPInstruction ci = (CPInstruction) i;
final Constant c = old_cp.getConstant(ci.getIndex());
ci.setIndex(new_cp.addConstant(c, old_cp));
}
}
}
private void clear() {
start = end = null;
length = 0;
}
/**
* Delete contents of list. Provides better memory utilization, because the system then may reuse the instruction handles. This method is typically called
* right after {@link MethodGen#getMethod()}.
*/
public void dispose() {
// Traverse in reverse order, because ih.next is overwritten
for (InstructionHandle ih = end; ih != null; ih = ih.getPrev()) {
/*
* Causes BranchInstructions to release target and targeters, because it calls dispose() on the contained instruction.
*/
ih.dispose();
}
clear();
}
/**
* @return start of list
*/
public InstructionHandle getStart() {
return start;
}
/**
* @return end of list
*/
public InstructionHandle getEnd() {
return end;
}
/**
* @return length of list (Number of instructions, not bytes)
*/
public int getLength() {
return length;
}
/**
* @return length of list (Number of instructions, not bytes)
*/
public int size() {
return length;
}
/**
* Redirect all references from old_target to new_target, i.e., update targets of branch instructions.
*
* @param old_target
* the old target instruction handle
* @param new_target
* the new target instruction handle
*/
public void redirectBranches(final InstructionHandle old_target, final InstructionHandle new_target) {
for (InstructionHandle ih = start; ih != null; ih = ih.getNext()) {
final Instruction i = ih.getInstruction();
if (i instanceof BranchInstruction) {
final BranchInstruction b = (BranchInstruction) i;
final InstructionHandle target = b.getTarget();
if (target == old_target) {
b.setTarget(new_target);
}
if (b instanceof Select) { // Either LOOKUPSWITCH or TABLESWITCH
final InstructionHandle[] targets = ((Select) b).getTargets();
for (int j = 0; j < targets.length; j++) {
if (targets[j] == old_target) {
((Select) b).setTarget(j, new_target);
}
}
}
}
}
}
/**
* Redirect all references of local variables from old_target to new_target.
*
* @param lg
* array of local variables
* @param old_target
* the old target instruction handle
* @param new_target
* the new target instruction handle
* @see MethodGen
*/
public void redirectLocalVariables(final LocalVariableGen[] lg, final InstructionHandle old_target, final InstructionHandle new_target) {
for (final LocalVariableGen element : lg) {
final InstructionHandle start = element.getStart();
final InstructionHandle end = element.getEnd();
if (start == old_target) {
element.setStart(new_target);
}
if (end == old_target) {
element.setEnd(new_target);
}
}
}
/**
* Redirect all references of exception handlers from old_target to new_target.
*
* @param exceptions
* array of exception handlers
* @param old_target
* the old target instruction handle
* @param new_target
* the new target instruction handle
* @see MethodGen
*/
public void redirectExceptionHandlers(final CodeExceptionGen[] exceptions, final InstructionHandle old_target, final InstructionHandle new_target) {
for (final CodeExceptionGen exception : exceptions) {
if (exception.getStartPC() == old_target) {
exception.setStartPC(new_target);
}
if (exception.getEndPC() == old_target) {
exception.setEndPC(new_target);
}
if (exception.getHandlerPC() == old_target) {
exception.setHandlerPC(new_target);
}
}
}
private List observers;
/**
* Add observer for this object.
*/
public void addObserver(final InstructionListObserver o) {
if (observers == null) {
observers = new ArrayList<>();
}
observers.add(o);
}
/**
* Remove observer for this object.
*/
public void removeObserver(final InstructionListObserver o) {
if (observers != null) {
observers.remove(o);
}
}
/**
* Call notify() method on all observers. This method is not called automatically whenever the state has changed, but has to be called by the user after he
* has finished editing the object.
*/
public void update() {
if (observers != null) {
for (final InstructionListObserver observer : observers) {
observer.notify(this);
}
}
}
}
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