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Diffstat (limited to 'src/proguard/optimize/peephole/ReachableCodeMarker.java')
| -rw-r--r-- | src/proguard/optimize/peephole/ReachableCodeMarker.java | 262 |
1 files changed, 0 insertions, 262 deletions
diff --git a/src/proguard/optimize/peephole/ReachableCodeMarker.java b/src/proguard/optimize/peephole/ReachableCodeMarker.java deleted file mode 100644 index 2b8fb10..0000000 --- a/src/proguard/optimize/peephole/ReachableCodeMarker.java +++ /dev/null @@ -1,262 +0,0 @@ -/* - * ProGuard -- shrinking, optimization, obfuscation, and preverification - * of Java bytecode. - * - * Copyright (c) 2002-2014 Eric Lafortune (eric@graphics.cornell.edu) - * - * This program is free software; you can redistribute it and/or modify it - * under the terms of the GNU General Public License as published by the Free - * Software Foundation; either version 2 of the License, or (at your option) - * any later version. - * - * This program is distributed in the hope that it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for - * more details. - * - * You should have received a copy of the GNU General Public License along - * with this program; if not, write to the Free Software Foundation, Inc., - * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ -package proguard.optimize.peephole; - -import proguard.classfile.*; -import proguard.classfile.attribute.*; -import proguard.classfile.attribute.visitor.*; -import proguard.classfile.instruction.*; -import proguard.classfile.instruction.visitor.InstructionVisitor; -import proguard.classfile.util.SimplifiedVisitor; - -import java.util.Arrays; - -/** - * This AttributeVisitor finds all instruction offsets, branch targets, and - * exception targets in the CodeAttribute objects that it visits. - * - * @author Eric Lafortune - */ -public class ReachableCodeMarker -extends SimplifiedVisitor -implements AttributeVisitor, - InstructionVisitor, - ExceptionInfoVisitor -{ - private boolean[] isReachable = new boolean[ClassConstants.TYPICAL_CODE_LENGTH]; - - private boolean next; - private boolean evaluateExceptions; - - - /** - * Returns whether the instruction at the given offset is reachable in - * the CodeAttribute that was visited most recently. - */ - public boolean isReachable(int offset) - { - return isReachable[offset]; - } - - - /** - * Returns whether any of the instructions at the given offsets are - * reachable in the CodeAttribute that was visited most recently. - */ - public boolean isReachable(int startOffset, int endOffset) - { - // Check if any of the instructions is reachable. - for (int offset = startOffset; offset < endOffset; offset++) - { - if (isReachable[offset]) - { - return true; - } - } - - return false; - } - - - // Implementations for AttributeVisitor. - - public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} - - - public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) - { - // Make sure there is a sufficiently large array. - int codeLength = codeAttribute.u4codeLength; - if (isReachable.length < codeLength) - { - // Create a new array. - isReachable = new boolean[codeLength]; - } - else - { - // Reset the array. - Arrays.fill(isReachable, 0, codeLength, false); - } - - // Mark the code, starting at the entry point. - markCode(clazz, method, codeAttribute, 0); - - // Mark the exception handlers, iterating as long as necessary. - do - { - evaluateExceptions = false; - - codeAttribute.exceptionsAccept(clazz, method, this); - } - while (evaluateExceptions); - } - - - // Implementations for InstructionVisitor. - - public void visitSimpleInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SimpleInstruction simpleInstruction) - { - byte opcode = simpleInstruction.opcode; - if (opcode == InstructionConstants.OP_IRETURN || - opcode == InstructionConstants.OP_LRETURN || - opcode == InstructionConstants.OP_FRETURN || - opcode == InstructionConstants.OP_DRETURN || - opcode == InstructionConstants.OP_ARETURN || - opcode == InstructionConstants.OP_RETURN || - opcode == InstructionConstants.OP_ATHROW) - { - next = false; - } - } - - - public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction) - { - } - - - public void visitVariableInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, VariableInstruction variableInstruction) - { - if (variableInstruction.opcode == InstructionConstants.OP_RET) - { - next = false; - } - } - - - public void visitBranchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, BranchInstruction branchInstruction) - { - // Mark the branch target. - markBranchTarget(clazz, - method, - codeAttribute, - offset + branchInstruction.branchOffset); - - byte opcode = branchInstruction.opcode; - if (opcode == InstructionConstants.OP_GOTO || - opcode == InstructionConstants.OP_GOTO_W) - { - next = false; - } - } - - - public void visitAnySwitchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SwitchInstruction switchInstruction) - { - // Mark the branch targets of the default jump offset. - markBranchTarget(clazz, - method, - codeAttribute, - offset + switchInstruction.defaultOffset); - - // Mark the branch targets of the jump offsets. - markBranchTargets(clazz, - method, - codeAttribute, - offset, - switchInstruction.jumpOffsets); - - next = false; - } - - - // Implementations for ExceptionInfoVisitor. - - public void visitExceptionInfo(Clazz clazz, Method method, CodeAttribute codeAttribute, ExceptionInfo exceptionInfo) - { - // Mark the exception handler if it's relevant. - if (!isReachable(exceptionInfo.u2handlerPC) && - isReachable(exceptionInfo.u2startPC, exceptionInfo.u2endPC)) - { - markCode(clazz, method, codeAttribute, exceptionInfo.u2handlerPC); - - evaluateExceptions = true; - } - } - - - // Small utility methods. - - /** - * Marks the branch targets of the given jump offsets for the instruction - * at the given offset. - */ - private void markBranchTargets(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, int[] jumpOffsets) - { - for (int index = 0; index < jumpOffsets.length; index++) - { - markCode(clazz, method, codeAttribute, offset + jumpOffsets[index]); - } - } - - - /** - * Marks the branch target at the given offset. - */ - private void markBranchTarget(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset) - { - boolean oldNext = next; - - markCode(clazz, method, codeAttribute, offset); - - next = oldNext; - } - - - /** - * Marks the code starting at the given offset. - */ - private void markCode(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset) - { - boolean oldNext = next; - - byte[] code = codeAttribute.code; - - // Continue with the current instruction as long as we haven't marked it - // yet. - while (!isReachable[offset]) - { - // Get the current instruction. - Instruction instruction = InstructionFactory.create(code, offset); - - // Mark it as reachable. - isReachable[offset] = true; - - // By default, we'll assume we can continue with the next - // instruction in a moment. - next = true; - - // Mark the branch targets, if any. - instruction.accept(clazz, method, codeAttribute, offset, this); - - // Can we really continue with the next instruction? - if (!next) - { - break; - } - - // Go to the next instruction. - offset += instruction.length(offset); - } - - next = oldNext; - } -} |