Java example source code file (Instruction.java)
The Instruction.java Java example source code/*
* Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.java.util.jar.pack;
import java.io.IOException;
import java.util.Arrays;
import static com.sun.java.util.jar.pack.Constants.*;
/**
* A parsed bytecode instruction.
* Provides accessors to various relevant bits.
* @author John Rose
*/
class Instruction {
protected byte[] bytes; // bytecodes
protected int pc; // location of this instruction
protected int bc; // opcode of this instruction
protected int w; // 0 if normal, 1 if a _wide prefix at pc
protected int length; // bytes in this instruction
protected boolean special;
protected Instruction(byte[] bytes, int pc, int bc, int w, int length) {
reset(bytes, pc, bc, w, length);
}
private void reset(byte[] bytes, int pc, int bc, int w, int length) {
this.bytes = bytes;
this.pc = pc;
this.bc = bc;
this.w = w;
this.length = length;
}
public int getBC() {
return bc;
}
public boolean isWide() {
return w != 0;
}
public byte[] getBytes() {
return bytes;
}
public int getPC() {
return pc;
}
public int getLength() {
return length;
}
public int getNextPC() {
return pc + length;
}
public Instruction next() {
int npc = pc + length;
if (npc == bytes.length)
return null;
else
return Instruction.at(bytes, npc, this);
}
public boolean isNonstandard() {
return isNonstandard(bc);
}
public void setNonstandardLength(int length) {
assert(isNonstandard());
this.length = length;
}
/** A fake instruction at this pc whose next() will be at nextpc. */
public Instruction forceNextPC(int nextpc) {
int llength = nextpc - pc;
return new Instruction(bytes, pc, -1, -1, llength);
}
public static Instruction at(byte[] bytes, int pc) {
return Instruction.at(bytes, pc, null);
}
public static Instruction at(byte[] bytes, int pc, Instruction reuse) {
int bc = getByte(bytes, pc);
int prefix = -1;
int w = 0;
int length = BC_LENGTH[w][bc];
if (length == 0) {
// Hard cases:
switch (bc) {
case _wide:
bc = getByte(bytes, pc+1);
w = 1;
length = BC_LENGTH[w][bc];
if (length == 0) {
// unknown instruction; treat as one byte
length = 1;
}
break;
case _tableswitch:
return new TableSwitch(bytes, pc);
case _lookupswitch:
return new LookupSwitch(bytes, pc);
default:
// unknown instruction; treat as one byte
length = 1;
break;
}
}
assert(length > 0);
assert(pc+length <= bytes.length);
// Speed hack: Instruction.next reuses self if possible.
if (reuse != null && !reuse.special) {
reuse.reset(bytes, pc, bc, w, length);
return reuse;
}
return new Instruction(bytes, pc, bc, w, length);
}
// Return the constant pool reference type, or 0 if none.
public byte getCPTag() {
return BC_TAG[w][bc];
}
// Return the constant pool index, or -1 if none.
public int getCPIndex() {
int indexLoc = BC_INDEX[w][bc];
if (indexLoc == 0) return -1;
assert(w == 0);
if (length == 2)
return getByte(bytes, pc+indexLoc); // _ldc opcode only
else
return getShort(bytes, pc+indexLoc);
}
public void setCPIndex(int cpi) {
int indexLoc = BC_INDEX[w][bc];
assert(indexLoc != 0);
if (length == 2)
setByte(bytes, pc+indexLoc, cpi); // _ldc opcode only
else
setShort(bytes, pc+indexLoc, cpi);
assert(getCPIndex() == cpi);
}
public ConstantPool.Entry getCPRef(ConstantPool.Entry[] cpMap) {
int index = getCPIndex();
return (index < 0) ? null : cpMap[index];
}
// Return the slot of the affected local, or -1 if none.
public int getLocalSlot() {
int slotLoc = BC_SLOT[w][bc];
if (slotLoc == 0) return -1;
if (w == 0)
return getByte(bytes, pc+slotLoc);
else
return getShort(bytes, pc+slotLoc);
}
// Return the target of the branch, or -1 if none.
public int getBranchLabel() {
int branchLoc = BC_BRANCH[w][bc];
if (branchLoc == 0) return -1;
assert(w == 0);
assert(length == 3 || length == 5);
int offset;
if (length == 3)
offset = (short)getShort(bytes, pc+branchLoc);
else
offset = getInt(bytes, pc+branchLoc);
assert(offset+pc >= 0);
assert(offset+pc <= bytes.length);
return offset+pc;
}
public void setBranchLabel(int targetPC) {
int branchLoc = BC_BRANCH[w][bc];
assert(branchLoc != 0);
if (length == 3)
setShort(bytes, pc+branchLoc, targetPC-pc);
else
setInt(bytes, pc+branchLoc, targetPC-pc);
assert(targetPC == getBranchLabel());
}
// Return the trailing constant in the instruction (as a signed value).
// Return 0 if there is none.
public int getConstant() {
int conLoc = BC_CON[w][bc];
if (conLoc == 0) return 0;
switch (length - conLoc) {
case 1: return (byte) getByte(bytes, pc+conLoc);
case 2: return (short) getShort(bytes, pc+conLoc);
}
assert(false);
return 0;
}
public void setConstant(int con) {
int conLoc = BC_CON[w][bc];
assert(conLoc != 0);
switch (length - conLoc) {
case 1: setByte(bytes, pc+conLoc, con); break;
case 2: setShort(bytes, pc+conLoc, con); break;
}
assert(con == getConstant());
}
public abstract static class Switch extends Instruction {
// Each case is a (value, label) pair, indexed 0 <= n < caseCount
public abstract int getCaseCount();
public abstract int getCaseValue(int n);
public abstract int getCaseLabel(int n);
public abstract void setCaseCount(int caseCount);
public abstract void setCaseValue(int n, int value);
public abstract void setCaseLabel(int n, int targetPC);
protected abstract int getLength(int caseCount);
public int getDefaultLabel() { return intAt(0)+pc; }
public void setDefaultLabel(int targetPC) { setIntAt(0, targetPC-pc); }
protected int apc; // aligned pc (table base)
protected int intAt(int n) { return getInt(bytes, apc + n*4); }
protected void setIntAt(int n, int x) { setInt(bytes, apc + n*4, x); }
protected Switch(byte[] bytes, int pc, int bc) {
super(bytes, pc, bc, /*w*/0, /*length*/0);
this.apc = alignPC(pc+1);
this.special = true;
length = getLength(getCaseCount());
}
public int getAlignedPC() { return apc; }
public String toString() {
String s = super.toString();
s += " Default:"+labstr(getDefaultLabel());
int caseCount = getCaseCount();
for (int i = 0; i < caseCount; i++) {
s += "\n\tCase "+getCaseValue(i)+":"+labstr(getCaseLabel(i));
}
return s;
}
public static int alignPC(int apc) {
while (apc % 4 != 0) ++apc;
return apc;
}
}
public static class TableSwitch extends Switch {
// apc: (df, lo, hi, (hi-lo+1)*(label))
public int getLowCase() { return intAt(1); }
public int getHighCase() { return intAt(2); }
public int getCaseCount() { return intAt(2)-intAt(1)+1; }
public int getCaseValue(int n) { return getLowCase()+n; }
public int getCaseLabel(int n) { return intAt(3+n)+pc; }
public void setLowCase(int val) { setIntAt(1, val); }
public void setHighCase(int val) { setIntAt(2, val); }
public void setCaseLabel(int n, int tpc) { setIntAt(3+n, tpc-pc); }
public void setCaseCount(int caseCount) {
setHighCase(getLowCase() + caseCount - 1);
length = getLength(caseCount);
}
public void setCaseValue(int n, int val) {
if (n != 0) throw new UnsupportedOperationException();
int caseCount = getCaseCount();
setLowCase(val);
setCaseCount(caseCount); // keep invariant
}
TableSwitch(byte[] bytes, int pc) {
super(bytes, pc, _tableswitch);
}
protected int getLength(int caseCount) {
return (apc-pc) + (3 + caseCount) * 4;
}
}
public static class LookupSwitch extends Switch {
// apc: (df, nc, nc*(case, label))
public int getCaseCount() { return intAt(1); }
public int getCaseValue(int n) { return intAt(2+n*2+0); }
public int getCaseLabel(int n) { return intAt(2+n*2+1)+pc; }
public void setCaseCount(int caseCount) {
setIntAt(1, caseCount);
length = getLength(caseCount);
}
public void setCaseValue(int n, int val) { setIntAt(2+n*2+0, val); }
public void setCaseLabel(int n, int tpc) { setIntAt(2+n*2+1, tpc-pc); }
LookupSwitch(byte[] bytes, int pc) {
super(bytes, pc, _lookupswitch);
}
protected int getLength(int caseCount) {
return (apc-pc) + (2 + caseCount*2) * 4;
}
}
/** Two instructions are equal if they have the same bytes. */
public boolean equals(Object o) {
return (o != null) && (o.getClass() == Instruction.class)
&& equals((Instruction) o);
}
public int hashCode() {
int hash = 3;
hash = 11 * hash + Arrays.hashCode(this.bytes);
hash = 11 * hash + this.pc;
hash = 11 * hash + this.bc;
hash = 11 * hash + this.w;
hash = 11 * hash + this.length;
return hash;
}
public boolean equals(Instruction that) {
if (this.pc != that.pc) return false;
if (this.bc != that.bc) return false;
if (this.w != that.w) return false;
if (this.length != that.length) return false;
for (int i = 1; i < length; i++) {
if (this.bytes[this.pc+i] != that.bytes[that.pc+i])
return false;
}
return true;
}
static String labstr(int pc) {
if (pc >= 0 && pc < 100000)
return ((100000+pc)+"").substring(1);
return pc+"";
}
public String toString() {
return toString(null);
}
public String toString(ConstantPool.Entry[] cpMap) {
String s = labstr(pc) + ": ";
if (bc >= _bytecode_limit) {
s += Integer.toHexString(bc);
return s;
}
if (w == 1) s += "wide ";
String bcname = (bc < BC_NAME.length)? BC_NAME[bc]: null;
if (bcname == null) {
return s+"opcode#"+bc;
}
s += bcname;
int tag = getCPTag();
if (tag != 0) s += " "+ConstantPool.tagName(tag)+":";
int idx = getCPIndex();
if (idx >= 0) s += (cpMap == null) ? ""+idx : "="+cpMap[idx].stringValue();
int slt = getLocalSlot();
if (slt >= 0) s += " Local:"+slt;
int lab = getBranchLabel();
if (lab >= 0) s += " To:"+labstr(lab);
int con = getConstant();
if (con != 0) s += " Con:"+con;
return s;
}
//public static byte constantPoolTagFor(int bc) { return BC_TAG[0][bc]; }
/// Fetching values from byte arrays:
public int getIntAt(int off) {
return getInt(bytes, pc+off);
}
public int getShortAt(int off) {
return getShort(bytes, pc+off);
}
public int getByteAt(int off) {
return getByte(bytes, pc+off);
}
public static int getInt(byte[] bytes, int pc) {
return (getShort(bytes, pc+0) << 16) + (getShort(bytes, pc+2) << 0);
}
public static int getShort(byte[] bytes, int pc) {
return (getByte(bytes, pc+0) << 8) + (getByte(bytes, pc+1) << 0);
}
public static int getByte(byte[] bytes, int pc) {
return bytes[pc] & 0xFF;
}
public static void setInt(byte[] bytes, int pc, int x) {
setShort(bytes, pc+0, x >> 16);
setShort(bytes, pc+2, x >> 0);
}
public static void setShort(byte[] bytes, int pc, int x) {
setByte(bytes, pc+0, x >> 8);
setByte(bytes, pc+1, x >> 0);
}
public static void setByte(byte[] bytes, int pc, int x) {
bytes[pc] = (byte)x;
}
// some bytecode classifiers
public static boolean isNonstandard(int bc) {
return BC_LENGTH[0][bc] < 0;
}
public static int opLength(int bc) {
int l = BC_LENGTH[0][bc];
assert(l > 0);
return l;
}
public static int opWideLength(int bc) {
int l = BC_LENGTH[1][bc];
assert(l > 0);
return l;
}
public static boolean isLocalSlotOp(int bc) {
return (bc < BC_SLOT[0].length && BC_SLOT[0][bc] > 0);
}
public static boolean isBranchOp(int bc) {
return (bc < BC_BRANCH[0].length && BC_BRANCH[0][bc] > 0);
}
public static boolean isCPRefOp(int bc) {
if (bc < BC_INDEX[0].length && BC_INDEX[0][bc] > 0) return true;
if (bc >= _xldc_op && bc < _xldc_limit) return true;
if (bc == _invokespecial_int || bc == _invokestatic_int) return true;
return false;
}
public static byte getCPRefOpTag(int bc) {
if (bc < BC_INDEX[0].length && BC_INDEX[0][bc] > 0) return BC_TAG[0][bc];
if (bc >= _xldc_op && bc < _xldc_limit) return CONSTANT_LoadableValue;
if (bc == _invokestatic_int || bc == _invokespecial_int) return CONSTANT_InterfaceMethodref;
return CONSTANT_None;
}
public static boolean isFieldOp(int bc) {
return (bc >= _getstatic && bc <= _putfield);
}
public static boolean isInvokeInitOp(int bc) {
return (bc >= _invokeinit_op && bc < _invokeinit_limit);
}
public static boolean isSelfLinkerOp(int bc) {
return (bc >= _self_linker_op && bc < _self_linker_limit);
}
/// Format definitions.
static private final byte[][] BC_LENGTH = new byte[2][0x100];
static private final byte[][] BC_INDEX = new byte[2][0x100];
static private final byte[][] BC_TAG = new byte[2][0x100];
static private final byte[][] BC_BRANCH = new byte[2][0x100];
static private final byte[][] BC_SLOT = new byte[2][0x100];
static private final byte[][] BC_CON = new byte[2][0x100];
static private final String[] BC_NAME = new String[0x100]; // debug only
static private final String[][] BC_FORMAT = new String[2][_bytecode_limit]; // debug only
static {
for (int i = 0; i < _bytecode_limit; i++) {
BC_LENGTH[0][i] = -1;
BC_LENGTH[1][i] = -1;
}
def("b", _nop, _dconst_1);
def("bx", _bipush);
def("bxx", _sipush);
def("bk", _ldc); // do not pack
def("bkk", _ldc_w, _ldc2_w); // do not pack
def("blwbll", _iload, _aload);
def("b", _iload_0, _saload);
def("blwbll", _istore, _astore);
def("b", _istore_0, _lxor);
def("blxwbllxx", _iinc);
def("b", _i2l, _dcmpg);
def("boo", _ifeq, _jsr); // pack oo
def("blwbll", _ret);
def("", _tableswitch, _lookupswitch); // pack all ints, omit padding
def("b", _ireturn, _return);
def("bkf", _getstatic, _putfield); // pack kf (base=Field)
def("bkm", _invokevirtual, _invokestatic); // pack kn (base=Method)
def("bkixx", _invokeinterface); // pack ki (base=IMethod), omit xx
def("bkyxx", _invokedynamic); // pack ky (base=Any), omit xx
def("bkc", _new); // pack kc
def("bx", _newarray);
def("bkc", _anewarray); // pack kc
def("b", _arraylength, _athrow);
def("bkc", _checkcast, _instanceof); // pack kc
def("b", _monitorenter, _monitorexit);
def("", _wide);
def("bkcx", _multianewarray); // pack kc
def("boo", _ifnull, _ifnonnull); // pack oo
def("boooo", _goto_w, _jsr_w); // pack oooo
for (int i = 0; i < _bytecode_limit; i++) {
//System.out.println(i+": l="+BC_LENGTH[0][i]+" i="+BC_INDEX[0][i]);
//assert(BC_LENGTH[0][i] != -1);
if (BC_LENGTH[0][i] == -1) {
continue; // unknown opcode
}
// Have a complete mapping, to support spurious _wide prefixes.
if (BC_LENGTH[1][i] == -1)
BC_LENGTH[1][i] = (byte)(1+BC_LENGTH[0][i]);
}
String names =
"nop aconst_null iconst_m1 iconst_0 iconst_1 iconst_2 iconst_3 iconst_4 "+
"iconst_5 lconst_0 lconst_1 fconst_0 fconst_1 fconst_2 dconst_0 dconst_1 "+
"bipush sipush ldc ldc_w ldc2_w iload lload fload dload aload iload_0 "+
"iload_1 iload_2 iload_3 lload_0 lload_1 lload_2 lload_3 fload_0 fload_1 "+
"fload_2 fload_3 dload_0 dload_1 dload_2 dload_3 aload_0 aload_1 aload_2 "+
"aload_3 iaload laload faload daload aaload baload caload saload istore "+
"lstore fstore dstore astore istore_0 istore_1 istore_2 istore_3 lstore_0 "+
"lstore_1 lstore_2 lstore_3 fstore_0 fstore_1 fstore_2 fstore_3 dstore_0 "+
"dstore_1 dstore_2 dstore_3 astore_0 astore_1 astore_2 astore_3 iastore "+
"lastore fastore dastore aastore bastore castore sastore pop pop2 dup "+
"dup_x1 dup_x2 dup2 dup2_x1 dup2_x2 swap iadd ladd fadd dadd isub lsub "+
"fsub dsub imul lmul fmul dmul idiv ldiv fdiv ddiv irem lrem frem drem "+
"ineg lneg fneg dneg ishl lshl ishr lshr iushr lushr iand land ior lor "+
"ixor lxor iinc i2l i2f i2d l2i l2f l2d f2i f2l f2d d2i d2l d2f i2b i2c "+
"i2s lcmp fcmpl fcmpg dcmpl dcmpg ifeq ifne iflt ifge ifgt ifle if_icmpeq "+
"if_icmpne if_icmplt if_icmpge if_icmpgt if_icmple if_acmpeq if_acmpne "+
"goto jsr ret tableswitch lookupswitch ireturn lreturn freturn dreturn "+
"areturn return getstatic putstatic getfield putfield invokevirtual "+
"invokespecial invokestatic invokeinterface invokedynamic new newarray "+
"anewarray arraylength athrow checkcast instanceof monitorenter "+
"monitorexit wide multianewarray ifnull ifnonnull goto_w jsr_w ";
for (int bc = 0; names.length() > 0; bc++) {
int sp = names.indexOf(' ');
BC_NAME[bc] = names.substring(0, sp);
names = names.substring(sp+1);
}
}
public static String byteName(int bc) {
String iname;
if (bc < BC_NAME.length && BC_NAME[bc] != null) {
iname = BC_NAME[bc];
} else if (isSelfLinkerOp(bc)) {
int idx = (bc - _self_linker_op);
boolean isSuper = (idx >= _self_linker_super_flag);
if (isSuper) idx -= _self_linker_super_flag;
boolean isAload = (idx >= _self_linker_aload_flag);
if (isAload) idx -= _self_linker_aload_flag;
int origBC = _first_linker_op + idx;
assert(origBC >= _first_linker_op && origBC <= _last_linker_op);
iname = BC_NAME[origBC];
iname += (isSuper ? "_super" : "_this");
if (isAload) iname = "aload_0&" + iname;
iname = "*"+iname;
} else if (isInvokeInitOp(bc)) {
int idx = (bc - _invokeinit_op);
switch (idx) {
case _invokeinit_self_option:
iname = "*invokespecial_init_this"; break;
case _invokeinit_super_option:
iname = "*invokespecial_init_super"; break;
default:
assert(idx == _invokeinit_new_option);
iname = "*invokespecial_init_new"; break;
}
} else {
switch (bc) {
case _ildc: iname = "*ildc"; break;
case _fldc: iname = "*fldc"; break;
case _ildc_w: iname = "*ildc_w"; break;
case _fldc_w: iname = "*fldc_w"; break;
case _dldc2_w: iname = "*dldc2_w"; break;
case _cldc: iname = "*cldc"; break;
case _cldc_w: iname = "*cldc_w"; break;
case _qldc: iname = "*qldc"; break;
case _qldc_w: iname = "*qldc_w"; break;
case _byte_escape: iname = "*byte_escape"; break;
case _ref_escape: iname = "*ref_escape"; break;
case _end_marker: iname = "*end"; break;
default: iname = "*bc#"+bc; break;
}
}
return iname;
}
private static int BW = 4; // width of classification field
private static void def(String fmt, int bc) {
def(fmt, bc, bc);
}
private static void def(String fmt, int from_bc, int to_bc) {
String[] fmts = { fmt, null };
if (fmt.indexOf('w') > 0) {
fmts[1] = fmt.substring(fmt.indexOf('w'));
fmts[0] = fmt.substring(0, fmt.indexOf('w'));
}
for (int w = 0; w <= 1; w++) {
fmt = fmts[w];
if (fmt == null) continue;
int length = fmt.length();
int index = Math.max(0, fmt.indexOf('k'));
int tag = CONSTANT_None;
int branch = Math.max(0, fmt.indexOf('o'));
int slot = Math.max(0, fmt.indexOf('l'));
int con = Math.max(0, fmt.indexOf('x'));
if (index > 0 && index+1 < length) {
switch (fmt.charAt(index+1)) {
case 'c': tag = CONSTANT_Class; break;
case 'k': tag = CONSTANT_LoadableValue; break;
case 'f': tag = CONSTANT_Fieldref; break;
case 'm': tag = CONSTANT_Methodref; break;
case 'i': tag = CONSTANT_InterfaceMethodref; break;
case 'y': tag = CONSTANT_InvokeDynamic; break;
}
assert(tag != CONSTANT_None);
} else if (index > 0 && length == 2) {
assert(from_bc == _ldc);
tag = CONSTANT_LoadableValue; // _ldc opcode only
}
for (int bc = from_bc; bc <= to_bc; bc++) {
BC_FORMAT[w][bc] = fmt;
assert(BC_LENGTH[w][bc] == -1);
BC_LENGTH[w][bc] = (byte) length;
BC_INDEX[w][bc] = (byte) index;
BC_TAG[w][bc] = (byte) tag;
assert(!(index == 0 && tag != CONSTANT_None));
BC_BRANCH[w][bc] = (byte) branch;
BC_SLOT[w][bc] = (byte) slot;
assert(branch == 0 || slot == 0); // not both branch & local
assert(branch == 0 || index == 0); // not both branch & cp
assert(slot == 0 || index == 0); // not both local & cp
BC_CON[w][bc] = (byte) con;
}
}
}
public static void opcodeChecker(byte[] code, ConstantPool.Entry[] cpMap,
Package.Version clsVersion) throws FormatException {
Instruction i = at(code, 0);
while (i != null) {
int opcode = i.getBC();
if (opcode < _nop || opcode > _jsr_w) {
String message = "illegal opcode: " + opcode + " " + i;
throw new FormatException(message);
}
ConstantPool.Entry e = i.getCPRef(cpMap);
if (e != null) {
byte tag = i.getCPTag();
boolean match = e.tagMatches(tag);
if (!match &&
(i.bc == _invokespecial || i.bc == _invokestatic) &&
e.tagMatches(CONSTANT_InterfaceMethodref) &&
clsVersion.greaterThan(Constants.JAVA7_MAX_CLASS_VERSION)) {
match = true;
}
if (!match) {
String message = "illegal reference, expected type="
+ ConstantPool.tagName(tag) + ": "
+ i.toString(cpMap);
throw new FormatException(message);
}
}
i = i.next();
}
}
static class FormatException extends IOException {
private static final long serialVersionUID = 3175572275651367015L;
FormatException(String message) {
super(message);
}
}
}
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