1b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/* 2b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * ProGuard -- shrinking, optimization, obfuscation, and preverification 3b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * of Java bytecode. 4b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 5b9cc48a43ed984587c939d02fba5316bf5c0df6eYing Wang * Copyright (c) 2002-2013 Eric Lafortune (eric@graphics.cornell.edu) 6b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 7b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This program is free software; you can redistribute it and/or modify it 8b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * under the terms of the GNU General Public License as published by the Free 9b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Software Foundation; either version 2 of the License, or (at your option) 10b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * any later version. 11b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 12b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This program is distributed in the hope that it will be useful, but WITHOUT 13b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * more details. 16b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 17b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * You should have received a copy of the GNU General Public License along 18b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * with this program; if not, write to the Free Software Foundation, Inc., 19b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 21b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratopackage proguard.classfile.instruction; 22b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 23b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.*; 24b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.attribute.CodeAttribute; 25b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoimport proguard.classfile.instruction.visitor.InstructionVisitor; 26b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 27b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato/** 28b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * This interface describes an instruction that branches to a given offset in 29b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * the code. 30b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * 31b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @author Eric Lafortune 32b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 33b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratopublic class BranchInstruction extends Instruction 34b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato{ 35b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public int branchOffset; 36b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 37b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 38b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 39b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Creates an uninitialized BranchInstruction. 40b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 41b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public BranchInstruction() {} 42b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 43b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 44b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public BranchInstruction(byte opcode, int branchOffset) 45b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 46b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato this.opcode = opcode; 47b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato this.branchOffset = branchOffset; 48b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 49b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 50b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 51b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 52b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Copies the given instruction into this instruction. 53b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @param branchInstruction the instruction to be copied. 54b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * @return this instruction. 55b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 56b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public BranchInstruction copy(BranchInstruction branchInstruction) 57b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 58b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato this.opcode = branchInstruction.opcode; 59b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato this.branchOffset = branchInstruction.branchOffset; 60b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 61b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato return this; 62b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 63b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 64b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 65b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Implementations for Instruction. 66b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 67b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public byte canonicalOpcode() 68b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 69b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Remove the _w extension, if any. 70b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato switch (opcode) 71b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 72b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato case InstructionConstants.OP_GOTO_W: return InstructionConstants.OP_GOTO; 73b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 74b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato case InstructionConstants.OP_JSR_W: return InstructionConstants.OP_JSR; 75b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 76b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato default: return opcode; 77b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 78b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 79b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 80b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public Instruction shrink() 81b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 82b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Do we need an ordinary branch or a wide branch? 83b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (requiredBranchOffsetSize() == 2) 84b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 85b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Can we replace the wide branch by an ordinary branch? 86b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (opcode == InstructionConstants.OP_GOTO_W) 87b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 88b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato opcode = InstructionConstants.OP_GOTO; 89b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 90b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato else if (opcode == InstructionConstants.OP_JSR_W) 91b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 92b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato opcode = InstructionConstants.OP_JSR; 93b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 94b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 95b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato else 96b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 97b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Should we replace the ordinary branch by a wide branch? 98b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (opcode == InstructionConstants.OP_GOTO) 99b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 100b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato opcode = InstructionConstants.OP_GOTO_W; 101b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 102b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato else if (opcode == InstructionConstants.OP_JSR) 103b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 104b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato opcode = InstructionConstants.OP_JSR_W; 105b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 106b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato else 107b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 108b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato throw new IllegalArgumentException("Branch instruction can't be widened ("+this.toString()+")"); 109b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 110b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 111b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 112b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato return this; 113b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 114b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 115b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato protected void readInfo(byte[] code, int offset) 116b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 117b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato branchOffset = readSignedValue(code, offset, branchOffsetSize()); 118b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 119b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 120b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 121b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato protected void writeInfo(byte[] code, int offset) 122b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 123b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato if (requiredBranchOffsetSize() > branchOffsetSize()) 124b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 125b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato throw new IllegalArgumentException("Instruction has invalid branch offset size ("+this.toString(offset)+")"); 126b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 127b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 128b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato writeSignedValue(code, offset, branchOffset, branchOffsetSize()); 129b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 130b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 131b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 132b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public int length(int offset) 133b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 134b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato return 1 + branchOffsetSize(); 135b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 136b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 137b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 138b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, InstructionVisitor instructionVisitor) 139b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 140b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato instructionVisitor.visitBranchInstruction(clazz, method, codeAttribute, offset, this); 141b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 142b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 143b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 144b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public String toString(int offset) 145b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 146b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato return "["+offset+"] "+toString()+" (target="+(offset+branchOffset)+")"; 147b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 148b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 149b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 150b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Implementations for Object. 151b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 152b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato public String toString() 153b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 154b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato return getName()+" "+(branchOffset >= 0 ? "+" : "")+branchOffset; 155b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 156b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 157b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 158b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato // Small utility methods. 159b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 160b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 161b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Returns the branch offset size for this instruction. 162b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 163b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private int branchOffsetSize() 164b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 165b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato return opcode == InstructionConstants.OP_GOTO_W || 166b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato opcode == InstructionConstants.OP_JSR_W ? 4 : 167b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 2; 168b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 169b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 170b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 171b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /** 172b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * Computes the required branch offset size for this instruction's branch 173b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato * offset. 174b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato */ 175b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato private int requiredBranchOffsetSize() 176b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato { 177b9cc48a43ed984587c939d02fba5316bf5c0df6eYing Wang return (short)branchOffset == branchOffset ? 2 : 4; 178b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato } 179b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato} 180