jdk/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapDecoder.java
Adam Sotona d85b0ca5cd 8332457: Examine startup overheads from JDK-8294961
8229959: Convert proxy class to use constant dynamic

Reviewed-by: liach, redestad
2024-06-05 15:33:03 +00:00

289 lines
12 KiB
Java

/*
* Copyright (c) 2022, 2024, 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
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package jdk.internal.classfile.impl;
import java.lang.classfile.BufWriter;
import java.lang.classfile.ClassReader;
import java.lang.classfile.Label;
import java.lang.classfile.MethodModel;
import java.lang.classfile.attribute.StackMapFrameInfo;
import java.lang.classfile.attribute.StackMapFrameInfo.*;
import java.lang.classfile.constantpool.ClassEntry;
import java.lang.constant.ConstantDescs;
import java.lang.constant.MethodTypeDesc;
import java.lang.reflect.AccessFlag;
import java.util.List;
import java.util.Objects;
import java.util.TreeMap;
import static java.lang.classfile.ClassFile.*;
public class StackMapDecoder {
private static final int
SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
SAME_EXTENDED = 251;
private final ClassReader classReader;
private final int pos;
private final LabelContext ctx;
private final List<VerificationTypeInfo> initFrameLocals;
private int p;
StackMapDecoder(ClassReader classReader, int pos, LabelContext ctx, List<VerificationTypeInfo> initFrameLocals) {
this.classReader = classReader;
this.pos = pos;
this.ctx = ctx;
this.initFrameLocals = initFrameLocals;
}
static List<VerificationTypeInfo> initFrameLocals(MethodModel method) {
return initFrameLocals(method.parent().orElseThrow().thisClass(),
method.methodName().stringValue(),
method.methodTypeSymbol(),
method.flags().has(AccessFlag.STATIC));
}
public static List<VerificationTypeInfo> initFrameLocals(ClassEntry thisClass, String methodName, MethodTypeDesc methodType, boolean isStatic) {
VerificationTypeInfo vtis[];
int i = 0;
if (!isStatic) {
vtis = new VerificationTypeInfo[methodType.parameterCount() + 1];
if ("<init>".equals(methodName) && !ConstantDescs.CD_Object.equals(thisClass.asSymbol())) {
vtis[i++] = SimpleVerificationTypeInfo.ITEM_UNINITIALIZED_THIS;
} else {
vtis[i++] = new StackMapDecoder.ObjectVerificationTypeInfoImpl(thisClass);
}
} else {
vtis = new VerificationTypeInfo[methodType.parameterCount()];
}
for (int pi = 0; pi < methodType.parameterCount(); pi++) {
var arg = methodType.parameterType(pi);
vtis[i++] = switch (arg.descriptorString().charAt(0)) {
case 'I', 'S', 'C' ,'B', 'Z' -> SimpleVerificationTypeInfo.ITEM_INTEGER;
case 'J' -> SimpleVerificationTypeInfo.ITEM_LONG;
case 'F' -> SimpleVerificationTypeInfo.ITEM_FLOAT;
case 'D' -> SimpleVerificationTypeInfo.ITEM_DOUBLE;
case 'V' -> throw new IllegalArgumentException("Illegal method argument type: " + arg);
default -> new StackMapDecoder.ObjectVerificationTypeInfoImpl(TemporaryConstantPool.INSTANCE.classEntry(arg));
};
}
return List.of(vtis);
}
public static void writeFrames(BufWriter b, List<StackMapFrameInfo> entries) {
var buf = (BufWriterImpl)b;
var dcb = (DirectCodeBuilder)buf.labelContext();
var mi = dcb.methodInfo();
var prevLocals = StackMapDecoder.initFrameLocals(buf.thisClass(),
mi.methodName().stringValue(),
mi.methodTypeSymbol(),
(mi.methodFlags() & ACC_STATIC) != 0);
int prevOffset = -1;
var map = new TreeMap<Integer, StackMapFrameInfo>();
//sort by resolved label offsets first to allow unordered entries
for (var fr : entries) {
map.put(dcb.labelToBci(fr.target()), fr);
}
b.writeU2(map.size());
for (var me : map.entrySet()) {
int offset = me.getKey();
var fr = me.getValue();
writeFrame(buf, offset - prevOffset - 1, prevLocals, fr);
prevOffset = offset;
prevLocals = fr.locals();
}
}
private static void writeFrame(BufWriterImpl out, int offsetDelta, List<VerificationTypeInfo> prevLocals, StackMapFrameInfo fr) {
if (offsetDelta < 0) throw new IllegalArgumentException("Invalid stack map frames order");
if (fr.stack().isEmpty()) {
int commonLocalsSize = Math.min(prevLocals.size(), fr.locals().size());
int diffLocalsSize = fr.locals().size() - prevLocals.size();
if (-3 <= diffLocalsSize && diffLocalsSize <= 3 && equals(fr.locals(), prevLocals, commonLocalsSize)) {
if (diffLocalsSize == 0 && offsetDelta < 64) { //same frame
out.writeU1(offsetDelta);
} else { //chop, same extended or append frame
out.writeU1(251 + diffLocalsSize);
out.writeU2(offsetDelta);
for (int i=commonLocalsSize; i<fr.locals().size(); i++) writeTypeInfo(out, fr.locals().get(i));
}
return;
}
} else if (fr.stack().size() == 1 && fr.locals().equals(prevLocals)) {
if (offsetDelta < 64) { //same locals 1 stack item frame
out.writeU1(64 + offsetDelta);
} else { //same locals 1 stack item extended frame
out.writeU1(247);
out.writeU2(offsetDelta);
}
writeTypeInfo(out, fr.stack().get(0));
return;
}
//full frame
out.writeU1(255);
out.writeU2(offsetDelta);
out.writeU2(fr.locals().size());
for (var l : fr.locals()) writeTypeInfo(out, l);
out.writeU2(fr.stack().size());
for (var s : fr.stack()) writeTypeInfo(out, s);
}
private static boolean equals(List<VerificationTypeInfo> l1, List<VerificationTypeInfo> l2, int compareSize) {
for (int i = 0; i < compareSize; i++) {
if (!l1.get(i).equals(l2.get(i))) return false;
}
return true;
}
private static void writeTypeInfo(BufWriterImpl bw, VerificationTypeInfo vti) {
bw.writeU1(vti.tag());
switch (vti) {
case SimpleVerificationTypeInfo svti ->
{}
case ObjectVerificationTypeInfo ovti ->
bw.writeIndex(ovti.className());
case UninitializedVerificationTypeInfo uvti ->
bw.writeU2(bw.labelContext().labelToBci(uvti.newTarget()));
}
}
List<StackMapFrameInfo> entries() {
p = pos;
List<VerificationTypeInfo> locals = initFrameLocals, stack = List.of();
int bci = -1;
var entries = new StackMapFrameInfo[u2()];
for (int ei = 0; ei < entries.length; ei++) {
int frameType = classReader.readU1(p++);
if (frameType < 64) {
bci += frameType + 1;
stack = List.of();
} else if (frameType < 128) {
bci += frameType - 63;
stack = List.of(readVerificationTypeInfo());
} else {
if (frameType < SAME_LOCALS_1_STACK_ITEM_EXTENDED)
throw new IllegalArgumentException("Invalid stackmap frame type: " + frameType);
bci += u2() + 1;
if (frameType == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {
stack = List.of(readVerificationTypeInfo());
} else if (frameType < SAME_EXTENDED) {
locals = locals.subList(0, locals.size() + frameType - SAME_EXTENDED);
stack = List.of();
} else if (frameType == SAME_EXTENDED) {
stack = List.of();
} else if (frameType < SAME_EXTENDED + 4) {
int actSize = locals.size();
var newLocals = locals.toArray(new VerificationTypeInfo[actSize + frameType - SAME_EXTENDED]);
for (int i = actSize; i < newLocals.length; i++)
newLocals[i] = readVerificationTypeInfo();
locals = List.of(newLocals);
stack = List.of();
} else {
var newLocals = new VerificationTypeInfo[u2()];
for (int i=0; i<newLocals.length; i++)
newLocals[i] = readVerificationTypeInfo();
var newStack = new VerificationTypeInfo[u2()];
for (int i=0; i<newStack.length; i++)
newStack[i] = readVerificationTypeInfo();
locals = List.of(newLocals);
stack = List.of(newStack);
}
}
entries[ei] = new StackMapFrameImpl(frameType,
ctx.getLabel(bci),
locals,
stack);
}
return List.of(entries);
}
private VerificationTypeInfo readVerificationTypeInfo() {
int tag = classReader.readU1(p++);
return switch (tag) {
case VT_TOP -> SimpleVerificationTypeInfo.ITEM_TOP;
case VT_INTEGER -> SimpleVerificationTypeInfo.ITEM_INTEGER;
case VT_FLOAT -> SimpleVerificationTypeInfo.ITEM_FLOAT;
case VT_DOUBLE -> SimpleVerificationTypeInfo.ITEM_DOUBLE;
case VT_LONG -> SimpleVerificationTypeInfo.ITEM_LONG;
case VT_NULL -> SimpleVerificationTypeInfo.ITEM_NULL;
case VT_UNINITIALIZED_THIS -> SimpleVerificationTypeInfo.ITEM_UNINITIALIZED_THIS;
case VT_OBJECT -> new ObjectVerificationTypeInfoImpl(classReader.entryByIndex(u2(), ClassEntry.class));
case VT_UNINITIALIZED -> new UninitializedVerificationTypeInfoImpl(ctx.getLabel(u2()));
default -> throw new IllegalArgumentException("Invalid verification type tag: " + tag);
};
}
public static record ObjectVerificationTypeInfoImpl(
ClassEntry className) implements ObjectVerificationTypeInfo {
@Override
public int tag() { return VT_OBJECT; }
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o instanceof ObjectVerificationTypeInfoImpl that) {
return Objects.equals(className, that.className);
}
return false;
}
@Override
public int hashCode() {
return Objects.hash(className);
}
@Override
public String toString() {
return className.asInternalName();
}
}
public static record UninitializedVerificationTypeInfoImpl(Label newTarget) implements UninitializedVerificationTypeInfo {
@Override
public int tag() { return VT_UNINITIALIZED; }
@Override
public String toString() {
return "UNINIT(" + newTarget +")";
}
}
private int u2() {
int v = classReader.readU2(p);
p += 2;
return v;
}
public static record StackMapFrameImpl(int frameType,
Label target,
List<VerificationTypeInfo> locals,
List<VerificationTypeInfo> stack)
implements StackMapFrameInfo {
}
}