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Optimize classfile read/write #14637

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30 changes: 23 additions & 7 deletions src/java.base/share/classes/jdk/internal/classfile/impl/BufWriterImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -87,17 +87,23 @@ public int getMajorVersion() {

@Override
public void writeU1(int x) {
writeIntBytes(1, x);
reserveSpace(Byte.BYTES);
elems[offset] = (byte) (x & 0xFF);
offset += Byte.BYTES;
}

@Override
public void writeU2(int x) {
writeIntBytes(2, x);
reserveSpace(Short.BYTES);
Util.putShort(elems, offset, (short) (x & 0xFFFF));
offset += Short.BYTES;
}

@Override
public void writeInt(int x) {
writeIntBytes(4, x);
reserveSpace(Integer.BYTES);
Util.putInt(elems, offset, x);
offset += Integer.BYTES;
}

@Override
Expand All @@ -107,7 +113,9 @@ public void writeFloat(float x) {

@Override
public void writeLong(long x) {
writeIntBytes(8, x);
reserveSpace(Long.BYTES);
Util.putLong(elems, offset, x);
offset += Long.BYTES;
}

@Override
Expand Down Expand Up @@ -143,9 +151,17 @@ public void patchInt(int offset, int size, int value) {

@Override
public void writeIntBytes(int intSize, long intValue) {
reserveSpace(intSize);
for (int i = 0; i < intSize; i++) {
elems[offset++] = (byte) ((intValue >> 8 * (intSize - i - 1)) & 0xFF);
switch (intSize) {
case 1 -> writeU1((int) (intValue & 0xFFL));
case 2 -> writeU2((int) (intValue & 0xFFFFL));
case 4 -> writeInt((int) (intValue & 0xFFFFFFFFL));
case 8 -> writeLong(intValue);
default -> {
reserveSpace(intSize);
for (int i = 0; i < intSize; i++) {
elems[offset++] = (byte) ((intValue >> 8 * (intSize - i - 1)) & 0xFF);
}
}
}
}

Expand Down
26 changes: 9 additions & 17 deletions src/java.base/share/classes/jdk/internal/classfile/impl/ClassReaderImpl.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2022, 2023, 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
Expand Down Expand Up @@ -43,6 +43,7 @@
import jdk.internal.classfile.constantpool.PackageEntry;
import jdk.internal.classfile.constantpool.PoolEntry;
import jdk.internal.classfile.constantpool.Utf8Entry;
import jdk.internal.misc.Unsafe;

import static jdk.internal.classfile.Classfile.TAG_CLASS;
import static jdk.internal.classfile.Classfile.TAG_CONSTANTDYNAMIC;
Expand All @@ -65,6 +66,8 @@
public final class ClassReaderImpl
implements ClassReader {
static final int CP_ITEM_START = 10;
// Cannot use VarHandle as it depends on bytecode generation
private static final Unsafe UNSAFE = Unsafe.getUnsafe();

private final byte[] buffer;
private final int metadataStart;
Expand Down Expand Up @@ -194,14 +197,12 @@ public BootstrapMethodEntryImpl bootstrapMethodEntry(int index) {

@Override
public int readU1(int p) {
return buffer[p] & 0xFF;
return Byte.toUnsignedInt(buffer[p]);
}

@Override
public int readU2(int p) {
int b1 = buffer[p] & 0xFF;
int b2 = buffer[p + 1] & 0xFF;
return (b1 << 8) + b2;
return Short.toUnsignedInt(Util.getShort(buffer, p));
}

@Override
Expand All @@ -211,26 +212,17 @@ public int readS1(int p) {

@Override
public int readS2(int p) {
int b1 = buffer[p];
int b2 = buffer[p + 1] & 0xFF;
return (b1 << 8) + b2;
return Util.getShort(buffer, p);
}

@Override
public int readInt(int p) {
int ch1 = buffer[p] & 0xFF;
int ch2 = buffer[p + 1] & 0xFF;
int ch3 = buffer[p + 2] & 0xFF;
int ch4 = buffer[p + 3] & 0xFF;
return (ch1 << 24) + (ch2 << 16) + (ch3 << 8) + ch4;
return Util.getInt(buffer, p);
}

@Override
public long readLong(int p) {
return ((long) buffer[p + 0] << 56) + ((long) (buffer[p + 1] & 255) << 48) +
((long) (buffer[p + 2] & 255) << 40) + ((long) (buffer[p + 3] & 255) << 32) +
((long) (buffer[p + 4] & 255) << 24) + ((buffer[p + 5] & 255) << 16) + ((buffer[p + 6] & 255) << 8) +
(buffer[p + 7] & 255);
return Util.getLong(buffer, p);
}

@Override
Expand Down
18 changes: 10 additions & 8 deletions src/java.base/share/classes/jdk/internal/classfile/impl/RawBytecodeHelper.java
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Expand Up @@ -24,6 +24,8 @@
*/
package jdk.internal.classfile.impl;

import jdk.internal.vm.annotation.Stable;

import java.nio.ByteBuffer;
import static jdk.internal.classfile.Classfile.ASTORE_3;
import static jdk.internal.classfile.Classfile.ISTORE;
Expand All @@ -35,7 +37,7 @@ public final class RawBytecodeHelper {

public static final int ILLEGAL = -1;

private static final byte[] LENGTHS = new byte[] {
private static final @Stable byte[] LENGTHS = new byte[] {
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2, 3, 3, 2 | (4 << 4), 2 | (4 << 4), 2 | (4 << 4), 2 | (4 << 4), 2 | (4 << 4), 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
2 | (4 << 4), 2 | (4 << 4), 2 | (4 << 4), 2 | (4 << 4), 2 | (4 << 4), 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3 | (6 << 4), 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2 | (4 << 4), 0, 0, 1, 1, 1,
Expand Down Expand Up @@ -84,11 +86,11 @@ public int destW() {
}

public int getIndexU1() {
return bytecode.get(bci + 1) & 0xff;
return getU1(bci + 1);
}

public int getU1(int bci) {
return bytecode.get(bci) & 0xff;
return Byte.toUnsignedInt(bytecode.get(bci));
}

public int rawNext(int jumpTo) {
Expand All @@ -98,7 +100,7 @@ public int rawNext(int jumpTo) {

public int rawNext() {
bci = nextBci;
int code = bytecode.get(bci) & 0xff;
int code = getU1(bci);
int len = LENGTHS[code] & 0xf;
if (len > 0 && (bci <= endBci - len)) {
isWide = false;
Expand All @@ -109,12 +111,12 @@ public int rawNext() {
rawCode = code;
return code;
} else {
len = switch (bytecode.get(bci) & 0xff) {
len = switch (getU1(bci)) {
case WIDE -> {
if (bci + 1 >= endBci) {
yield -1;
}
yield LENGTHS[bytecode.get(bci + 1) & 0xff] >> 4;
yield LENGTHS[getIndexU1()] >> 4;
}
case TABLESWITCH -> {
int aligned_bci = align(bci + 1);
Expand Down Expand Up @@ -147,7 +149,7 @@ public int rawNext() {
if (bci + 1 >= endBci) {
code = ILLEGAL;
} else {
code = bytecode.get(bci + 1) & 0xff;
code = getIndexU1();
isWide = true;
}
}
Expand All @@ -166,6 +168,6 @@ public int getIndexU2() {
}

public int getIndexU2Raw(int bci) {
return bytecode.getShort(bci) & 0xffff;
return Short.toUnsignedInt(bytecode.getShort(bci));
}
}
38 changes: 35 additions & 3 deletions src/java.base/share/classes/jdk/internal/classfile/impl/Util.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,9 +27,7 @@
import java.lang.constant.ClassDesc;
import java.lang.constant.MethodTypeDesc;
import java.util.AbstractList;
import java.util.BitSet;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.function.Function;

Expand All @@ -38,11 +36,13 @@
import jdk.internal.classfile.constantpool.ModuleEntry;
import jdk.internal.classfile.constantpool.NameAndTypeEntry;
import java.lang.constant.ModuleDesc;
import jdk.internal.classfile.impl.TemporaryConstantPool;
import java.lang.reflect.AccessFlag;

import static jdk.internal.classfile.Classfile.ACC_STATIC;
import jdk.internal.access.SharedSecrets;
import jdk.internal.misc.Unsafe;
import jdk.internal.util.Preconditions;
import jdk.internal.vm.annotation.ForceInline;

/**
* Helper to create and manipulate type descriptors, where type descriptors are
Expand All @@ -54,6 +54,38 @@ public class Util {
private Util() {
}

// Utilities to speed up reading/writing from arrays, before VarHandle is available
private static final Unsafe UNSAFE = Unsafe.getUnsafe();

@ForceInline
public static long checkByteArrayIndex(byte[] array, int index, int bytes) {
return Unsafe.ARRAY_BYTE_BASE_OFFSET + Preconditions.checkIndex(index, array.length - bytes + 1, Preconditions.AIOOBE_FORMATTER);
}

public static short getShort(byte[] array, int index) {
return UNSAFE.getShortUnaligned(array, checkByteArrayIndex(array, index, Short.BYTES), true);
}

public static int getInt(byte[] array, int index) {
return UNSAFE.getIntUnaligned(array, checkByteArrayIndex(array, index, Integer.BYTES), true);
}

public static long getLong(byte[] array, int index) {
return UNSAFE.getLongUnaligned(array, checkByteArrayIndex(array, index, Long.BYTES), true);
}

public static void putShort(byte[] array, int index, short value) {
UNSAFE.putShortUnaligned(array, checkByteArrayIndex(array, index, Short.BYTES), value, true);
}

public static void putInt(byte[] array, int index, int value) {
UNSAFE.putIntUnaligned(array, checkByteArrayIndex(array, index, Integer.BYTES), value, true);
}

public static void putLong(byte[] array, int index, long value) {
UNSAFE.putLongUnaligned(array, checkByteArrayIndex(array, index, Long.BYTES), value, true);
}

public static int parameterSlots(MethodTypeDesc mDesc) {
int count = 0;
for (int i = 0; i < mDesc.parameterCount(); i++) {
Expand Down