1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/classes/com/sun/tools/classfile/Instruction.java Mon Mar 30 15:08:09 2009 -0700
1.3 @@ -0,0 +1,339 @@
1.4 +/*
1.5 + * Copyright 2009 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Sun designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Sun in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.25 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.26 + * have any questions.
1.27 + */
1.28 +
1.29 +package com.sun.tools.classfile;
1.30 +
1.31 +/**
1.32 + * See JVMS3, chapter 6.
1.33 + *
1.34 + * <p><b>This is NOT part of any API supported by Sun Microsystems. If
1.35 + * you write code that depends on this, you do so at your own risk.
1.36 + * This code and its internal interfaces are subject to change or
1.37 + * deletion without notice.</b>
1.38 + *
1.39 + * @see Code_attribute#getInstructions
1.40 + */
1.41 +public class Instruction {
1.42 + /** The kind of an instruction, as determined by the position, size and
1.43 + * types of its operands. */
1.44 + public static enum Kind {
1.45 + /** Opcode is not followed by any operands. */
1.46 + NO_OPERANDS(1),
1.47 + /** Opcode is followed by a byte indicating a type. */
1.48 + ATYPE(2),
1.49 + /** Opcode is followed by a 2-byte branch offset. */
1.50 + BRANCH(3),
1.51 + /** Opcode is followed by a 4-byte branch offset. */
1.52 + BRANCH_W(5),
1.53 + /** Opcode is followed by a signed byte value. */
1.54 + BYTE(2),
1.55 + /** Opcode is followed by a 1-byte index into the constant pool. */
1.56 + CPREF(2),
1.57 + /** Opcode is followed by a 2-byte index into the constant pool. */
1.58 + CPREF_W(3),
1.59 + /** Opcode is followed by a 2-byte index into the constant pool,
1.60 + * an unsigned byte value. */
1.61 + CPREF_W_UBYTE(4),
1.62 + /** Opcode is followed by a 2-byte index into the constant pool.,
1.63 + * an unsigned byte value, and a zero byte. */
1.64 + CPREF_W_UBYTE_ZERO(5),
1.65 + /** Opcode is followed by variable number of operands, depending
1.66 + * on the instruction.*/
1.67 + DYNAMIC(-1),
1.68 + /** Opcode is followed by a 1-byte reference to a local variable. */
1.69 + LOCAL(2),
1.70 + /** Opcode is followed by a 1-byte reference to a local variable,
1.71 + * and a signed byte value. */
1.72 + LOCAL_BYTE(3),
1.73 + /** Opcode is followed by a signed short value. */
1.74 + SHORT(3),
1.75 + /** Wide opcode is not followed by any operands. */
1.76 + WIDE_NO_OPERANDS(2),
1.77 + /** Wide opcode is followed by a 2-byte index into the constant pool. */
1.78 + WIDE_CPREF_W(4),
1.79 + /** Wide opcode is followed by a 2-byte index into the constant pool,
1.80 + * and a signed short value. */
1.81 + WIDE_CPREF_W_SHORT(6),
1.82 + /** Opcode was not recognized. */
1.83 + UNKNOWN(1);
1.84 +
1.85 + Kind(int length) {
1.86 + this.length = length;
1.87 + }
1.88 +
1.89 + /** The length, in bytes, of this kind of instruction, or -1 is the
1.90 + * length depends on the specific instruction. */
1.91 + public final int length;
1.92 + };
1.93 +
1.94 + /** A utility visitor to help decode the operands of an instruction.
1.95 + * @see Instruction#accept */
1.96 + public interface KindVisitor<R,P> {
1.97 + /** See {@link Kind#NO_OPERANDS}, {@link Kind#WIDE_NO_OPERANDS}. */
1.98 + R visitNoOperands(Instruction instr, P p);
1.99 + /** See {@link Kind#ATYPE}. */
1.100 + R visitArrayType(Instruction instr, TypeKind kind, P p);
1.101 + /** See {@link Kind#BRANCH}, {@link Kind#BRANCH_W}. */
1.102 + R visitBranch(Instruction instr, int offset, P p);
1.103 + /** See {@link Kind#CPREF}, {@link Kind#CPREF_W}, {@link Kind#WIDE_CPREF_W}. */
1.104 + R visitConstantPoolRef(Instruction instr, int index, P p);
1.105 + /** See {@link Kind#CPREF_W_UBYTE}, {@link Kind#CPREF_W_UBYTE_ZERO}, {@link Kind#WIDE_CPREF_W_SHORT}. */
1.106 + R visitConstantPoolRefAndValue(Instruction instr, int index, int value, P p);
1.107 + /** See {@link Kind#LOCAL}. */
1.108 + R visitLocal(Instruction instr, int index, P p);
1.109 + /** See {@link Kind#LOCAL_UBYTE}. */
1.110 + R visitLocalAndValue(Instruction instr, int index, int value, P p);
1.111 + /** See {@link Kind#DYNAMIC}. */
1.112 + R visitLookupSwitch(Instruction instr, int default_, int npairs, int[] matches, int[] offsets);
1.113 + /** See {@link Kind#DYNAMIC}. */
1.114 + R visitTableSwitch(Instruction instr, int default_, int low, int high, int[] offsets);
1.115 + /** See {@link Kind#BYTE}, {@link Kind#SHORT}. */
1.116 + R visitValue(Instruction instr, int value, P p);
1.117 + /** Instruction is unrecognized. */
1.118 + R visitUnknown(Instruction instr, P p);
1.119 +
1.120 + }
1.121 +
1.122 + /** The kind of primitive array type to create.
1.123 + * See JVMS chapter 6, newarray. */
1.124 + public static enum TypeKind {
1.125 + T_BOOLEAN(4, "boolean"),
1.126 + T_CHAR(5, "char"),
1.127 + T_FLOAT(6, "float"),
1.128 + T_DOUBLE(7, "double"),
1.129 + T_BYTE(8, "byte"),
1.130 + T_SHORT(9, "short"),
1.131 + T_INT (10, "int"),
1.132 + T_LONG (11, "long");
1.133 + TypeKind(int value, String name) {
1.134 + this.value = value;
1.135 + this.name = name;
1.136 + }
1.137 +
1.138 + public static TypeKind get(int value) {
1.139 + switch (value) {
1.140 + case 4: return T_BOOLEAN;
1.141 + case 5: return T_CHAR;
1.142 + case 6: return T_FLOAT;
1.143 + case 7: return T_DOUBLE;
1.144 + case 8: return T_BYTE;
1.145 + case 9: return T_SHORT;
1.146 + case 10: return T_INT;
1.147 + case 11: return T_LONG;
1.148 + default: return null;
1.149 + }
1.150 + }
1.151 +
1.152 + public final int value;
1.153 + public final String name;
1.154 + }
1.155 +
1.156 + /** An instruction is defined by its position in a bytecode array. */
1.157 + public Instruction(byte[] bytes, int pc) {
1.158 + this.bytes = bytes;
1.159 + this.pc = pc;
1.160 + }
1.161 +
1.162 + /** Get the position of the instruction within the bytecode array. */
1.163 + public int getPC() {
1.164 + return pc;
1.165 + }
1.166 +
1.167 + /** Get a byte value, relative to the start of this instruction. */
1.168 + public int getByte(int offset) {
1.169 + return bytes[pc + offset];
1.170 + }
1.171 +
1.172 + /** Get an unsigned byte value, relative to the start of this instruction. */
1.173 + public int getUnsignedByte(int offset) {
1.174 + return getByte(offset) & 0xff;
1.175 + }
1.176 +
1.177 + /** Get a 2-byte value, relative to the start of this instruction. */
1.178 + public int getShort(int offset) {
1.179 + return (getByte(offset) << 8) | getUnsignedByte(offset + 1);
1.180 + }
1.181 +
1.182 + /** Get a unsigned 2-byte value, relative to the start of this instruction. */
1.183 + public int getUnsignedShort(int offset) {
1.184 + return getShort(offset) & 0xFFFF;
1.185 + }
1.186 +
1.187 + /** Get a 4-byte value, relative to the start of this instruction. */
1.188 + public int getInt(int offset) {
1.189 + return (getShort(offset) << 16) | (getUnsignedShort(offset + 2));
1.190 + }
1.191 +
1.192 + /** Get the Opcode for this instruction, or null if the instruction is
1.193 + * unrecognized. */
1.194 + public Opcode getOpcode() {
1.195 + int b = getUnsignedByte(0);
1.196 + switch (b) {
1.197 + case Opcode.NONPRIV:
1.198 + case Opcode.PRIV:
1.199 + case Opcode.WIDE:
1.200 + return Opcode.get(b, getUnsignedByte(1));
1.201 + }
1.202 + return Opcode.get(b);
1.203 + }
1.204 +
1.205 + /** Get the mnemonic for this instruction, or a default string if the
1.206 + * instruction is unrecognized. */
1.207 + public String getMnemonic() {
1.208 + Opcode opcode = getOpcode();
1.209 + if (opcode == null)
1.210 + return "bytecode " + getUnsignedByte(0);
1.211 + else
1.212 + return opcode.toString().toLowerCase();
1.213 + }
1.214 +
1.215 + /** Get the length, in bytes, of this instruction, including the opcode
1.216 + * and all its operands. */
1.217 + public int length() {
1.218 + Opcode opcode = getOpcode();
1.219 + if (opcode == null)
1.220 + return 1;
1.221 +
1.222 + switch (opcode) {
1.223 + case TABLESWITCH: {
1.224 + int pad = align(pc + 1) - pc;
1.225 + int low = getInt(pad + 4);
1.226 + int high = getInt(pad + 8);
1.227 + return pad + 12 + 4 * (high - low + 1);
1.228 + }
1.229 + case LOOKUPSWITCH: {
1.230 + int pad = align(pc + 1) - pc;
1.231 + int npairs = getInt(pad + 4);
1.232 + return pad + 8 + 8 * npairs;
1.233 +
1.234 + }
1.235 + default:
1.236 + return opcode.kind.length;
1.237 + }
1.238 + }
1.239 +
1.240 + /** Get the {@link Kind} of this instruction. */
1.241 + public Kind getKind() {
1.242 + Opcode opcode = getOpcode();
1.243 + return (opcode != null ? opcode.kind : Kind.UNKNOWN);
1.244 + }
1.245 +
1.246 + /** Invoke a method on the visitor according to the kind of this
1.247 + * instruction, passing in the decoded operands for the instruction. */
1.248 + public <R,P> R accept(KindVisitor<R,P> visitor, P p) {
1.249 + switch (getKind()) {
1.250 + case NO_OPERANDS:
1.251 + return visitor.visitNoOperands(this, p);
1.252 +
1.253 + case ATYPE:
1.254 + return visitor.visitArrayType(
1.255 + this, TypeKind.get(getUnsignedByte(1)), p);
1.256 +
1.257 + case BRANCH:
1.258 + return visitor.visitBranch(this, getShort(1), p);
1.259 +
1.260 + case BRANCH_W:
1.261 + return visitor.visitBranch(this, getInt(1), p);
1.262 +
1.263 + case BYTE:
1.264 + return visitor.visitValue(this, getByte(1), p);
1.265 +
1.266 + case CPREF:
1.267 + return visitor.visitConstantPoolRef(this, getUnsignedByte(1), p);
1.268 +
1.269 + case CPREF_W:
1.270 + return visitor.visitConstantPoolRef(this, getUnsignedShort(1), p);
1.271 +
1.272 + case CPREF_W_UBYTE:
1.273 + case CPREF_W_UBYTE_ZERO:
1.274 + return visitor.visitConstantPoolRefAndValue(
1.275 + this, getUnsignedShort(1), getUnsignedByte(3), p);
1.276 +
1.277 + case DYNAMIC: {
1.278 + switch (getOpcode()) {
1.279 + case TABLESWITCH: {
1.280 + int pad = align(pc + 1) - pc;
1.281 + int default_ = getInt(pad);
1.282 + int low = getInt(pad + 4);
1.283 + int high = getInt(pad + 8);
1.284 + int[] values = new int[high - low + 1];
1.285 + for (int i = 0; i < values.length; i++)
1.286 + values[i] = getInt(pad + 12 + 4 * i);
1.287 + return visitor.visitTableSwitch(
1.288 + this, default_, low, high, values);
1.289 + }
1.290 + case LOOKUPSWITCH: {
1.291 + int pad = align(pc + 1) - pc;
1.292 + int default_ = getInt(pad);
1.293 + int npairs = getInt(pad + 4);
1.294 + int[] matches = new int[npairs];
1.295 + int[] offsets = new int[npairs];
1.296 + for (int i = 0; i < npairs; i++) {
1.297 + matches[i] = getInt(pad + 8 + i * 8);
1.298 + offsets[i] = getInt(pad + 12 + i * 8);
1.299 + }
1.300 + return visitor.visitLookupSwitch(
1.301 + this, default_, npairs, matches, offsets);
1.302 + }
1.303 + default:
1.304 + throw new IllegalStateException();
1.305 + }
1.306 + }
1.307 +
1.308 + case LOCAL:
1.309 + return visitor.visitLocal(this, getUnsignedByte(1), p);
1.310 +
1.311 + case LOCAL_BYTE:
1.312 + return visitor.visitLocalAndValue(
1.313 + this, getUnsignedByte(1), getByte(2), p);
1.314 +
1.315 + case SHORT:
1.316 + return visitor.visitValue(this, getShort(1), p);
1.317 +
1.318 + case WIDE_NO_OPERANDS:
1.319 + return visitor.visitNoOperands(this, p);
1.320 +
1.321 + case WIDE_CPREF_W:
1.322 + return visitor.visitConstantPoolRef(this, getUnsignedShort(2), p);
1.323 +
1.324 + case WIDE_CPREF_W_SHORT:
1.325 + return visitor.visitConstantPoolRefAndValue(
1.326 + this, getUnsignedShort(2), getUnsignedByte(4), p);
1.327 +
1.328 + case UNKNOWN:
1.329 + return visitor.visitUnknown(this, p);
1.330 +
1.331 + default:
1.332 + throw new IllegalStateException();
1.333 + }
1.334 + }
1.335 +
1.336 + private static int align(int n) {
1.337 + return (n + 3) & ~3;
1.338 + }
1.339 +
1.340 + private byte[] bytes;
1.341 + private int pc;
1.342 +}
