com.android.dx.dex.code.StdCatchBuilder Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of builder Show documentation
Show all versions of builder Show documentation
Library to build Android applications.
/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed 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 com.android.dx.dex.code;
import com.android.dx.rop.code.BasicBlock;
import com.android.dx.rop.code.BasicBlockList;
import com.android.dx.rop.code.RopMethod;
import com.android.dx.rop.cst.CstType;
import com.android.dx.rop.type.Type;
import com.android.dx.rop.type.TypeList;
import com.android.dx.util.IntList;
import java.util.ArrayList;
import java.util.HashSet;
/**
* Constructor of {@link CatchTable} instances from {@link RopMethod}
* and associated data.
*/
public final class StdCatchBuilder implements CatchBuilder {
/** the maximum range of a single catch handler, in code units */
private static final int MAX_CATCH_RANGE = 65535;
/** {@code non-null;} method to build the list for */
private final RopMethod method;
/** {@code non-null;} block output order */
private final int[] order;
/** {@code non-null;} address objects for each block */
private final BlockAddresses addresses;
/**
* Constructs an instance. It merely holds onto its parameters for
* a subsequent call to {@link #build}.
*
* @param method {@code non-null;} method to build the list for
* @param order {@code non-null;} block output order
* @param addresses {@code non-null;} address objects for each block
*/
public StdCatchBuilder(RopMethod method, int[] order,
BlockAddresses addresses) {
if (method == null) {
throw new NullPointerException("method == null");
}
if (order == null) {
throw new NullPointerException("order == null");
}
if (addresses == null) {
throw new NullPointerException("addresses == null");
}
this.method = method;
this.order = order;
this.addresses = addresses;
}
/** {@inheritDoc} */
public CatchTable build() {
return build(method, order, addresses);
}
/** {@inheritDoc} */
public boolean hasAnyCatches() {
BasicBlockList blocks = method.getBlocks();
int size = blocks.size();
for (int i = 0; i < size; i++) {
BasicBlock block = blocks.get(i);
TypeList catches = block.getLastInsn().getCatches();
if (catches.size() != 0) {
return true;
}
}
return false;
}
/** {@inheritDoc} */
public HashSet getCatchTypes() {
HashSet result = new HashSet(20);
BasicBlockList blocks = method.getBlocks();
int size = blocks.size();
for (int i = 0; i < size; i++) {
BasicBlock block = blocks.get(i);
TypeList catches = block.getLastInsn().getCatches();
int catchSize = catches.size();
for (int j = 0; j < catchSize; j++) {
result.add(catches.getType(j));
}
}
return result;
}
/**
* Builds and returns the catch table for a given method.
*
* @param method {@code non-null;} method to build the list for
* @param order {@code non-null;} block output order
* @param addresses {@code non-null;} address objects for each block
* @return {@code non-null;} the constructed table
*/
public static CatchTable build(RopMethod method, int[] order,
BlockAddresses addresses) {
int len = order.length;
BasicBlockList blocks = method.getBlocks();
ArrayList resultList =
new ArrayList(len);
CatchHandlerList currentHandlers = CatchHandlerList.EMPTY;
BasicBlock currentStartBlock = null;
BasicBlock currentEndBlock = null;
for (int i = 0; i < len; i++) {
BasicBlock block = blocks.labelToBlock(order[i]);
if (!block.canThrow()) {
/*
* There is no need to concern ourselves with the
* placement of blocks that can't throw with respect
* to the blocks that *can* throw.
*/
continue;
}
CatchHandlerList handlers = handlersFor(block, addresses);
if (currentHandlers.size() == 0) {
// This is the start of a new catch range.
currentStartBlock = block;
currentEndBlock = block;
currentHandlers = handlers;
continue;
}
if (currentHandlers.equals(handlers)
&& rangeIsValid(currentStartBlock, block, addresses)) {
/*
* The block we are looking at now has the same handlers
* as the block that started the currently open catch
* range, and adding it to the currently open range won't
* cause it to be too long.
*/
currentEndBlock = block;
continue;
}
/*
* The block we are looking at now has incompatible handlers,
* so we need to finish off the last entry and start a new
* one. Note: We only emit an entry if it has associated handlers.
*/
if (currentHandlers.size() != 0) {
CatchTable.Entry entry =
makeEntry(currentStartBlock, currentEndBlock,
currentHandlers, addresses);
resultList.add(entry);
}
currentStartBlock = block;
currentEndBlock = block;
currentHandlers = handlers;
}
if (currentHandlers.size() != 0) {
// Emit an entry for the range that was left hanging.
CatchTable.Entry entry =
makeEntry(currentStartBlock, currentEndBlock,
currentHandlers, addresses);
resultList.add(entry);
}
// Construct the final result.
int resultSz = resultList.size();
if (resultSz == 0) {
return CatchTable.EMPTY;
}
CatchTable result = new CatchTable(resultSz);
for (int i = 0; i < resultSz; i++) {
result.set(i, resultList.get(i));
}
result.setImmutable();
return result;
}
/**
* Makes the {@link CatchHandlerList} for the given basic block.
*
* @param block {@code non-null;} block to get entries for
* @param addresses {@code non-null;} address objects for each block
* @return {@code non-null;} array of entries
*/
private static CatchHandlerList handlersFor(BasicBlock block,
BlockAddresses addresses) {
IntList successors = block.getSuccessors();
int succSize = successors.size();
int primary = block.getPrimarySuccessor();
TypeList catches = block.getLastInsn().getCatches();
int catchSize = catches.size();
if (catchSize == 0) {
return CatchHandlerList.EMPTY;
}
if (((primary == -1) && (succSize != catchSize))
|| ((primary != -1) &&
((succSize != (catchSize + 1))
|| (primary != successors.get(catchSize))))) {
/*
* Blocks that throw are supposed to list their primary
* successor -- if any -- last in the successors list, but
* that constraint appears to be violated here.
*/
throw new RuntimeException(
"shouldn't happen: weird successors list");
}
/*
* Reduce the effective catchSize if we spot a catch-all that
* isn't at the end.
*/
for (int i = 0; i < catchSize; i++) {
Type type = catches.getType(i);
if (type.equals(Type.OBJECT)) {
catchSize = i + 1;
break;
}
}
CatchHandlerList result = new CatchHandlerList(catchSize);
for (int i = 0; i < catchSize; i++) {
CstType oneType = new CstType(catches.getType(i));
CodeAddress oneHandler = addresses.getStart(successors.get(i));
result.set(i, oneType, oneHandler.getAddress());
}
result.setImmutable();
return result;
}
/**
* Makes a {@link CatchTable#Entry} for the given block range and
* handlers.
*
* @param start {@code non-null;} the start block for the range (inclusive)
* @param end {@code non-null;} the start block for the range (also inclusive)
* @param handlers {@code non-null;} the handlers for the range
* @param addresses {@code non-null;} address objects for each block
*/
private static CatchTable.Entry makeEntry(BasicBlock start,
BasicBlock end, CatchHandlerList handlers,
BlockAddresses addresses) {
/*
* We start at the *last* instruction of the start block, since
* that's the instruction that can throw...
*/
CodeAddress startAddress = addresses.getLast(start);
// ...And we end *after* the last instruction of the end block.
CodeAddress endAddress = addresses.getEnd(end);
return new CatchTable.Entry(startAddress.getAddress(),
endAddress.getAddress(), handlers);
}
/**
* Gets whether the address range for the given two blocks is valid
* for a catch handler. This is true as long as the covered range is
* under 65536 code units.
*
* @param start {@code non-null;} the start block for the range (inclusive)
* @param end {@code non-null;} the start block for the range (also inclusive)
* @param addresses {@code non-null;} address objects for each block
* @return {@code true} if the range is valid as a catch range
*/
private static boolean rangeIsValid(BasicBlock start, BasicBlock end,
BlockAddresses addresses) {
if (start == null) {
throw new NullPointerException("start == null");
}
if (end == null) {
throw new NullPointerException("end == null");
}
// See above about selection of instructions.
int startAddress = addresses.getLast(start).getAddress();
int endAddress = addresses.getEnd(end).getAddress();
return (endAddress - startAddress) <= MAX_CATCH_RANGE;
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy