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8265423: [lworld] Provide experimental support for generating a single class file per primitive class #394

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@@ -1429,6 +1429,14 @@ public boolean isSubClass(Symbol base, Types types) {
return false;
}

/**
* Does `this' symbolize a primitive class that would, under the translation
* scheme in effect be lowered into two class files on a bifurcased basis ??
*/
public boolean isSplitPrimitiveClass(Types types) {
return types.splitPrimitiveClass && this.isPrimitiveClass();
}

/** Complete the elaboration of this symbol's definition.
*/
public void complete() throws CompletionFailure {
@@ -101,6 +101,18 @@
List<Warner> warnStack = List.nil();
final Name capturedName;

/**
* If true, the ClassWriter will split a primitive class declaration into two class files
* P.ref.class and P.val.class (P.class for pure primitive classes)
*
* This is the default behavior, can be eoverridden with -XDunifiedValRefClass
*
* If false, we emit a single class for a primtive class 'P' and the reference projection and
* value projection types are encoded in descriptors as LP; and QP; resperctively.
*/

public boolean splitPrimitiveClass;

public final Warner noWarnings;

// <editor-fold defaultstate="collapsed" desc="Instantiating">
@@ -126,6 +138,7 @@ protected Types(Context context) {
noWarnings = new Warner(null);
Options options = Options.instance(context);
allowValueBasedClasses = options.isSet("allowValueBasedClasses");
splitPrimitiveClass = options.isUnset("unifiedValRefClass");
}
// </editor-fold>

@@ -5353,7 +5366,7 @@ public void assembleClassSig(Type type) {
} else {
append(externalize(c.flatname));
}
if (ct.isReferenceProjection()) {
if (types.splitPrimitiveClass && ct.isReferenceProjection()) {
append('$');
append(types.names.ref);
}
@@ -3108,12 +3108,15 @@ public void visitApply(JCMethodInvocation tree) {
if (haveValue == type.isPrimitiveClass())
return tree;
if (haveValue) {
// widening coversion is a NOP for the VM due to subtyping relationship at class file
return tree;
} else {
// For narrowing conversion, insert a cast which should trigger a null check
return (T) make.TypeCast(type, tree);
// widening coversion is a NOP for the VM due to subtyping relationship at class file level
// where we bifurcate a primitive class into two class files.
if (types.splitPrimitiveClass)
return tree;
}
// For narrowing conversion, insert a cast which should trigger a null check
// For widening conversions, insert a cast if emitting a unified class file.
return (T) make.TypeCast(type, tree);

}


@@ -2687,7 +2687,7 @@ public void readClassFile(ClassSymbol c) {
ClassSymbol referenceProjection = syms.getClass(currentModule, flatname);
if (referenceProjection != null) {
if (referenceProjection.name != names.ref && referenceProjection.owner.kind == PCK) {
readClassFileInternal(referenceProjection);
referenceProjection.complete();

This comment has been minimized.

@mcimadamore

mcimadamore Apr 27, 2021
Collaborator

This change seems sneaky - what caused it?

This comment has been minimized.

@sadayapalam

sadayapalam Apr 27, 2021
Author Collaborator

Indeed. I should push this as a separate change set. I discovered this bug while working on the now aborted attempt to evolve the code generation scheme to match SoV4. The right way to internalize the class is by calling complete() on the symbol and not by directly calling readClassFileInternal(). Doing the latter, could result in com.sun.tools.javac.code.ClassFinder#fillIn(com.sun.tools.javac.code.Symbol.ClassSymbol) from being re-entered resulting in an assertion failure.

This change is not required for the present feature, but is a crucial fix that should be made independently.

This comment has been minimized.

@sadayapalam

sadayapalam Apr 27, 2021
Author Collaborator

(As I was studying the code that merges the projections back to see what changes I should make for the unified class model, I remembered that bug fix from that aborted work)

This comment has been minimized.

@mcimadamore

mcimadamore Apr 27, 2021
Collaborator

I'm fine with keeping the change here if that's easier - I just wanted to make sure I understood where this was coming from as it looked an odd change given what of the rest of the code is doing. Thanks for the explanation.

ClassType classType = (ClassType) c.type;
classType.supertype_field = ((ClassType) referenceProjection.type).supertype_field;
classType.interfaces_field = ((ClassType) referenceProjection.type).interfaces_field;
@@ -845,7 +845,7 @@ void writeInnerClasses() {
!inner.name.isEmpty() ? poolWriter.putName(inner.name) : 0);
databuf.appendChar(flags);
icCount++;
if (inner.isPrimitiveClass()) {
if (inner.isSplitPrimitiveClass(types)) {
databuf.appendChar(poolWriter.putClass(inner.type.referenceProjection()));
databuf.appendChar(
inner.owner.kind == TYP && !inner.name.isEmpty() ? poolWriter.putClass((ClassSymbol)inner.owner) : 0);
@@ -883,7 +883,7 @@ int writeRecordAttribute(ClassSymbol csym) {
int writeNestMembersIfNeeded(ClassSymbol csym) {
Set<ClassSymbol> nestedUnique = new LinkedHashSet<>();
if (csym.owner.kind == PCK) {
if (csym.isPrimitiveClass()) {
if (csym.isSplitPrimitiveClass(types)) {
// reference projection is the host
} else if (csym.isReferenceProjection()) {
ClassSymbol valueProjection = csym.valueProjection();
@@ -899,7 +899,7 @@ int writeNestMembersIfNeeded(ClassSymbol csym) {
for (ClassSymbol s : nestedUnique) {
databuf.appendChar(poolWriter.putClass(s));
nmc++;
if (s.isPrimitiveClass() && s.owner.kind != PCK) {
if (s.isSplitPrimitiveClass(types) && s.owner.kind != PCK) {
databuf.appendChar(poolWriter.putClass(s.type.referenceProjection()));
nmc++;
}
@@ -916,10 +916,10 @@ int writeNestMembersIfNeeded(ClassSymbol csym) {
* Write NestHost attribute (if needed)
*/
int writeNestHostIfNeeded(ClassSymbol csym) {
if (csym.owner.kind != PCK || csym.isPrimitiveClass()) {
if (csym.owner.kind != PCK || csym.isSplitPrimitiveClass(types)) {
int alenIdx = writeAttr(names.NestHost);
ClassSymbol outerMost = csym.outermostClass();
if (outerMost.isPrimitiveClass()) {
if (outerMost.isSplitPrimitiveClass(types)) {
databuf.appendChar(poolWriter.putClass(outerMost.type.referenceProjection()));
} else {
databuf.appendChar(poolWriter.putClass(outerMost));
@@ -1530,7 +1530,7 @@ public JavaFileObject writeClass(ClassSymbol c)
throws IOException, PoolOverflow, StringOverflow
{
JavaFileObject javaFileObject = writeClassInternal(c);
if (c.isPrimitiveClass()) {
if (c.isSplitPrimitiveClass(types)) {
writeClassInternal(getReferenceProjection(c));
}
return javaFileObject;
@@ -1631,8 +1631,8 @@ public void writeClassFile(OutputStream out, ClassSymbol c)
databuf.reset();
poolbuf.reset();

Type supertype = c.isPrimitiveClass() ? c.type.referenceProjection() : types.supertype(c.type);
List<Type> interfaces = c.isPrimitiveClass() ? List.nil() : types.interfaces(c.type);
Type supertype = c.isSplitPrimitiveClass(types) ? c.type.referenceProjection() : types.supertype(c.type);
List<Type> interfaces = c.isSplitPrimitiveClass(types) ? List.nil() : types.interfaces(c.type);
List<Type> typarams = c.type.getTypeArguments();

int flags;
@@ -399,6 +399,17 @@ void postop() {

/** Emit a ldc (or ldc_w) instruction, taking into account operand size
*/
public void emitLdc(LoadableConstant constant, int od) {
if (od <= 255) {
emitop1(ldc1, od, constant);
}
else {
emitop2(ldc2, od, constant);
}
}

/** Emit a ldc (or ldc_w) instruction, taking into account operand size
*/
public void emitLdc(LoadableConstant constant) {
int od = poolWriter.putConstant(constant);
if (od <= 255) {
@@ -2272,10 +2272,10 @@ public void visitTypeCast(JCTypeCast tree) {
// which is not statically a supertype of the expression's type.
// For basic types, the coerce(...) in genExpr(...) will do
// the conversion.
// inline widening conversion is a nop, as the VM sees a subtyping relationship.
// inline widening conversion is a nop when we bifurcate the primitive class, as the VM sees a subtyping relationship.
if (!tree.clazz.type.isPrimitive() &&
!types.isSameType(tree.expr.type, tree.clazz.type) &&
(!tree.clazz.type.isReferenceProjection() || !types.isSameType(tree.clazz.type.valueProjection(), tree.expr.type)) &&
(!tree.clazz.type.isReferenceProjection() || !types.splitPrimitiveClass || !types.isSameType(tree.clazz.type.valueProjection(), tree.expr.type)) &&
!types.isSubtype(tree.expr.type, tree.clazz.type)) {
checkDimension(tree.pos(), tree.clazz.type);
if (types.isPrimitiveClass(tree.clazz.type)) {
@@ -2345,7 +2345,7 @@ public void visitSelect(JCFieldAccess tree) {
Symbol sym = tree.sym;

if (tree.name == names._class) {
code.emitLdc((LoadableConstant)checkDimension(tree.pos(), tree.selected.type));
code.emitLdc((LoadableConstant) tree.selected.type, makeRef(tree.pos(), tree.selected.type, !types.splitPrimitiveClass && tree.selected.type.isPrimitiveClass()));
result = items.makeStackItem(pt);
return;
}
@@ -378,7 +378,7 @@ void writeConstant(PoolConstant c) {
Name name = ct.hasTag(ARRAY) ?
typeSig(ct) :
c instanceof ConstantPoolQType ? names.fromString("Q" + new String(externalize(ct.tsym.flatName())) + ";") : names.fromUtf(externalize(ct.tsym.flatName()));
if (ct.isReferenceProjection()) {
if (types.splitPrimitiveClass && ct.isReferenceProjection()) {
name = name.append('$', names.ref);
}
poolbuf.appendByte(tag);
@@ -514,8 +514,8 @@ private Name classSig(Type t) {
if (typarams.nonEmpty()) {
signatureGen.assembleParamsSig(typarams);
}
signatureGen.assembleSig(t.isPrimitiveClass() ? t.referenceProjection() : types.supertype(t));
if (!t.isPrimitiveClass()) {
signatureGen.assembleSig(t.isPrimitiveClass() && types.splitPrimitiveClass ? t.referenceProjection() : types.supertype(t));
if (!t.isPrimitiveClass() || !types.splitPrimitiveClass) {
for (Type i : types.interfaces(t))
signatureGen.assembleSig(i);
}
@@ -0,0 +1,118 @@
/*
* Copyright (c) 2021, 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.
*
* 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.
*/

/*
* @test
* @bug 8265423
* @summary Experimental support for generating a single class file per primitive class
* @modules jdk.compiler/com.sun.tools.javac.util jdk.jdeps/com.sun.tools.javap
* @compile SplitPrimitiveClassBytecodeTest.java
* @run main SplitPrimitiveClassBytecodeTest
* @modules jdk.compiler
*/

import java.io.PrintWriter;
import java.io.StringWriter;
import java.nio.file.Paths;

public class SplitPrimitiveClassBytecodeTest {

public primitive class X {

X.ref xr = null;

public void foo(X.ref[] xra, X[] xa) {
xa = new X[10];
xra = new X.ref[10];
xra[0] = xa[0];
xa[1] = xra[0];
Class<?> c = X.class;
c = X.ref.class;
}
}

public static void main(String[] args) {
new SplitPrimitiveClassBytecodeTest().run();
}

void run() {
String [] params = new String [] { "-v",
Paths.get(System.getProperty("test.classes"),
"SplitPrimitiveClassBytecodeTest$X.class").toString() };
runCheck(params, new String [] {

// check field
"final SplitPrimitiveClassBytecodeTest$X$ref xr;",
"descriptor: LSplitPrimitiveClassBytecodeTest$X$ref;",
"flags: (0x0010) ACC_FINAL",

// check method
"public void foo(SplitPrimitiveClassBytecodeTest$X$ref[], SplitPrimitiveClassBytecodeTest$X[]);",
"descriptor: ([LSplitPrimitiveClassBytecodeTest$X$ref;[QSplitPrimitiveClassBytecodeTest$X;)V",
" 0: bipush 10",
" 2: anewarray #11 // class \"QSplitPrimitiveClassBytecodeTest$X;\"",
" 5: astore_2",
" 6: bipush 10",
" 8: anewarray #13 // class SplitPrimitiveClassBytecodeTest$X$ref",
"11: astore_1",
"12: aload_1",
"13: iconst_0",
"14: aload_2",
"15: iconst_0",
"16: aaload",
"17: aastore",
"18: aload_2",
"19: iconst_1",
"20: aload_1",
"21: iconst_0",
"22: aaload",
"23: checkcast #11 // class \"QSplitPrimitiveClassBytecodeTest$X;\"",
"26: aastore",
"27: ldc #1 // class SplitPrimitiveClassBytecodeTest$X",
"29: astore_3",
"30: ldc #13 // class SplitPrimitiveClassBytecodeTest$X$ref",
"32: astore_3",
"33: return",
});
}

void runCheck(String [] params, String [] expectedOut) {
StringWriter s;
String out;

try (PrintWriter pw = new PrintWriter(s = new StringWriter())) {
com.sun.tools.javap.Main.run(params, pw);
out = s.toString();
}
int errors = 0;
for (String eo: expectedOut) {
if (!out.contains(eo)) {
System.err.println("Match not found for string: " + eo);
errors++;
}
}
if (errors > 0) {
throw new AssertionError("Unexpected javap output: " + out);
}
}
}
@@ -0,0 +1,73 @@
/*
* Copyright (c) 2021, 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.
*/

/*
* @test
* @bug 8265423
* @summary Experimental support for generating a single class file per primitive class
* @modules jdk.jdeps/com.sun.tools.classfile
* @run main SplitPrimitiveClassInnerClassesTest
*/

import com.sun.tools.classfile.*;
import com.sun.tools.classfile.ConstantPool.CONSTANT_Class_info;

public class SplitPrimitiveClassInnerClassesTest {

primitive class V<T> implements java.io.Serializable {}

public static void main(String[] args) throws Exception {
ClassFile cls = ClassFile.read(SplitPrimitiveClassInnerClassesTest.class.getResourceAsStream("SplitPrimitiveClassInnerClassesTest.class"));

if (cls == null) {
throw new AssertionError("Could not locate the class files");
}

/* Check emission of inner class attribute */
InnerClasses_attribute inners = (InnerClasses_attribute) cls.attributes.get(Attribute.InnerClasses);
if (inners == null) {
throw new AssertionError("Missing inner class attribute");
}
boolean foundV = false, foundVref = false;
for (int i = 0; i < inners.number_of_classes; i++) {
String name = inners.classes[i].getInnerName(cls.constant_pool);
if (name.equals("V"))
foundV = true;
else if (name.equals("V$ref"))
foundVref = true;
}
if (!foundV || !foundVref) {
throw new AssertionError("Incorrect inner class attribute");
}

// Test signature attribute
cls = ClassFile.read(SplitPrimitiveClassInnerClassesTest.class.getResourceAsStream("SplitPrimitiveClassInnerClassesTest$V.class"));
Signature_attribute signature = (Signature_attribute)cls.attributes.get(Attribute.Signature);
String sign = signature.getSignature(cls.constant_pool);
if (sign == null || !sign.equals("<T:Ljava/lang/Object;>LSplitPrimitiveClassInnerClassesTest$V$ref<TT;>;")) {
throw new RuntimeException("Wrong signature " + sign);
}
}
}