From 63c46847bdfe5fdc7894aeb0a95d2d6212ac7379 Mon Sep 17 00:00:00 2001
From: liach <liach@openjdk.org>
Date: Wed, 12 Feb 2025 18:01:48 -0600
Subject: [PATCH 1/4] 8348606: [lworld] Substitutability test may perform heap
allocations
---
.../java/lang/invoke/MethodHandleImpl.java | 6 +-
.../java/lang/runtime/ValueObjectMethods.java | 31 ++--
.../internal/access/JavaLangInvokeAccess.java | 13 +-
.../jdk/internal/value/LayoutIteration.java | 168 ++++++++++++++++++
.../valuetypes/LayoutIterationTest.java | 89 ++++++++++
5 files changed, 285 insertions(+), 22 deletions(-)
create mode 100644 src/java.base/share/classes/jdk/internal/value/LayoutIteration.java
create mode 100644 test/jdk/valhalla/valuetypes/LayoutIterationTest.java
diff --git a/src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java b/src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java
index c6c9d05ec31..5a2220fd9ed 100644
--- a/src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java
+++ b/src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2008, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2025, 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
@@ -1642,6 +1642,10 @@ public MethodHandle serializableConstructor(Class<?> decl, Constructor<?> ctorTo
return IMPL_LOOKUP.serializableConstructor(decl, ctorToCall);
}
+ @Override
+ public MethodHandle assertAsType(MethodHandle original, MethodType assertedType) {
+ return original.viewAsType(assertedType, false);
+ }
});
}
diff --git a/src/java.base/share/classes/java/lang/runtime/ValueObjectMethods.java b/src/java.base/share/classes/java/lang/runtime/ValueObjectMethods.java
index 450703a36ca..a2927c73bd4 100644
--- a/src/java.base/share/classes/java/lang/runtime/ValueObjectMethods.java
+++ b/src/java.base/share/classes/java/lang/runtime/ValueObjectMethods.java
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2018, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2025, 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
@@ -45,12 +45,14 @@
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Stream;
import jdk.internal.access.JavaLangInvokeAccess;
import jdk.internal.access.SharedSecrets;
+import jdk.internal.value.LayoutIteration;
import sun.invoke.util.Wrapper;
import static java.lang.invoke.MethodHandles.constant;
@@ -92,19 +94,12 @@ static class MethodHandleBuilder {
static Stream<MethodHandle> getterStream(Class<?> type, Comparator<MethodHandle> comparator) {
// filter static fields
- Stream<MethodHandle> s = Arrays.stream(type.getDeclaredFields())
- .filter(f -> !Modifier.isStatic(f.getModifiers()))
- .map(f -> {
- try {
- return JLIA.unreflectField(f, false);
- } catch (IllegalAccessException e) {
- throw newLinkageError(e);
- }
- });
+ List<MethodHandle> mhs = LayoutIteration.ELEMENTS.get(type);
if (comparator != null) {
- s = s.sorted(comparator);
+ mhs = new ArrayList<>(mhs);
+ mhs.sort(comparator);
}
- return s;
+ return mhs.stream();
}
static MethodHandle hashCodeForType(Class<?> type) {
@@ -141,13 +136,11 @@ static Class<?> fieldType(MethodHandle getter) {
}
private static List<Class<?>> valueTypeFields(Class<?> type) {
- List<Class<?>> result = new ArrayList<>();
- Arrays.stream(type.getDeclaredFields())
- .filter(f -> !Modifier.isStatic(f.getModifiers()))
- .map(f -> f.getType())
- .filter(ft -> ft.isValue() && !result.contains(ft))
- .forEach(result::add);
- return result;
+ return LayoutIteration.ELEMENTS.get(type).stream()
+ .<Class<?>>map(mh -> mh.type().returnType())
+ .filter(Class::isValue)
+ .distinct()
+ .toList();
}
/*
diff --git a/src/java.base/share/classes/jdk/internal/access/JavaLangInvokeAccess.java b/src/java.base/share/classes/jdk/internal/access/JavaLangInvokeAccess.java
index 0caf66bbc42..4cb49de31c2 100644
--- a/src/java.base/share/classes/jdk/internal/access/JavaLangInvokeAccess.java
+++ b/src/java.base/share/classes/jdk/internal/access/JavaLangInvokeAccess.java
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2015, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2025, 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
@@ -28,7 +28,6 @@
import jdk.internal.foreign.abi.NativeEntryPoint;
import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles.Lookup;
import java.lang.invoke.MethodType;
import java.lang.invoke.VarHandle;
import java.lang.reflect.Constructor;
@@ -176,4 +175,14 @@ public interface JavaLangInvokeAccess {
* This method should only be used by ReflectionFactory::newConstructorForSerialization.
*/
MethodHandle serializableConstructor(Class<?> decl, Constructor<?> ctorToCall) throws IllegalAccessException;
+
+ /**
+ * Asserts a method handle to be another type without the conversion adaptions.
+ * Useful to avoid many redundant casts.
+ *
+ * @param original original MH
+ * @param assertedType the asserted type the origina MH can execute as
+ * @return the cheap view without extra adaptions
+ */
+ MethodHandle assertAsType(MethodHandle original, MethodType assertedType);
}
diff --git a/src/java.base/share/classes/jdk/internal/value/LayoutIteration.java b/src/java.base/share/classes/jdk/internal/value/LayoutIteration.java
new file mode 100644
index 00000000000..c99c2469ce4
--- /dev/null
+++ b/src/java.base/share/classes/jdk/internal/value/LayoutIteration.java
@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) 2025, 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 jdk.internal.value;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.ArrayList;
+import java.util.List;
+
+import jdk.internal.access.JavaLangInvokeAccess;
+import jdk.internal.access.SharedSecrets;
+import jdk.internal.misc.Unsafe;
+import sun.invoke.util.Wrapper;
+
+/**
+ * Iterates the layout elements of a value type.
+ * <p>
+ * In the long run, we should do this:
+ * Iterate the layout, create a mask masking bytes used by Object/abstract value
+ * class reference fields. Do a byte-wise compare and get the mask of value
+ * mismatch; if the mask's all clear, fine; if the mask has bits beyond our
+ * mask, fail; otherwise, compare reference fields indicated by the mismatch
+ * mask. There may be paddings to ignore, too, depends...
+ */
+public final class LayoutIteration {
+ // Initializer in static initializers below, order dependent
+ public static final ClassValue<List<MethodHandle>> ELEMENTS;
+
+ /**
+ * {@return a list of method handles accessing the basic elements}
+ * Basic elements are 8 primitives and pointers (to identity or value objects).
+ * Primitives and pointers are distinguished by the MH return types.
+ * The MH types are {@code flatType -> fieldType}.
+ *
+ * @param flatType the class that has a flat layout
+ * @return the accessors
+ * @throws IllegalArgumentException if argument has no flat layout
+ */
+ public static List<MethodHandle> computeElementGetters(Class<?> flatType) {
+ if (!canHaveFlatLayout(flatType))
+ throw new IllegalArgumentException(flatType + " cannot be flat");
+ var sink = new Sink(flatType);
+ iterateFields(U.valueHeaderSize(flatType), flatType, sink);
+ return List.copyOf(sink.getters);
+ }
+
+ // Ensures the given class has a potential a flat layout
+ private static boolean canHaveFlatLayout(Class<?> flatType) {
+ return flatType.isValue() && Modifier.isFinal(flatType.getModifiers());
+ }
+
+ private static final class Sink {
+ final Class<?> receiverType;
+ final List<MethodHandle> getters = new ArrayList<>();
+
+ Sink(Class<?> receiverType) {
+ this.receiverType = receiverType;
+ }
+
+ void accept(long offsetNoHeader, Class<?> itemType) {
+ Wrapper w = itemType.isPrimitive() ? Wrapper.forPrimitiveType(itemType) : Wrapper.OBJECT;
+ System.out.println(receiverType + " offset " + offsetNoHeader + " " + itemType);
+ var mh = MethodHandles.insertArguments(FIELD_GETTERS.get(w.ordinal()), 1, offsetNoHeader);
+ assert mh.type() == MethodType.methodType(w.primitiveType(), Object.class);
+ mh = JLIA.assertAsType(mh, MethodType.methodType(itemType, receiverType));
+ getters.add(mh);
+ }
+ }
+
+ // Sink is good for one to many mappings
+ private static void iterateFields(long enclosingOffset, Class<?> currentClass, Sink sink) {
+ assert canHaveFlatLayout(currentClass) : currentClass + " cannot be flat";
+ long memberOffsetDelta = enclosingOffset - U.valueHeaderSize(currentClass);
+ for (Field f : currentClass.getDeclaredFields()) {
+ if (Modifier.isStatic(f.getModifiers()))
+ continue;
+ var type = f.getType();
+ long memberOffset = U.objectFieldOffset(f) + memberOffsetDelta;
+ if (!U.isFlatField(f)) {
+ sink.accept(memberOffset, type);
+ } else {
+ iterateFields(memberOffset, type, sink);
+ }
+ }
+ }
+
+ private static boolean getBoolean(Object o, long offset) {
+ return U.getBoolean(o, offset);
+ }
+ private static byte getByte(Object o, long offset) {
+ return U.getByte(o, offset);
+ }
+ private static short getShort(Object o, long offset) {
+ return U.getShort(o, offset);
+ }
+ private static char getCharacter(Object o, long offset) {
+ return U.getChar(o, offset);
+ }
+ private static int getInteger(Object o, long offset) {
+ return U.getInt(o, offset);
+ }
+ private static long getLong(Object o, long offset) {
+ return U.getLong(o, offset);
+ }
+ private static float getFloat(Object o, long offset) {
+ return U.getFloat(o, offset);
+ }
+ private static double getDouble(Object o, long offset) {
+ return U.getDouble(o, offset);
+ }
+ public static Object getObject(Object o, long offset) {
+ return U.getReference(o, offset);
+ }
+
+ private static final Unsafe U = Unsafe.getUnsafe();
+ private static final JavaLangInvokeAccess JLIA = SharedSecrets.getJavaLangInvokeAccess();
+ private static final List<MethodHandle> FIELD_GETTERS;
+ static {
+ MethodHandle[] fieldGetters = new MethodHandle[9];
+ var lookup = MethodHandles.lookup();
+ var type = MethodType.methodType(void.class, Object.class, long.class);
+ try {
+ for (Wrapper w : Wrapper.values()) {
+ if (w != Wrapper.VOID) {
+ fieldGetters[w.ordinal()] = lookup.findStatic(LayoutIteration.class,
+ "get" + w.wrapperSimpleName(), type.changeReturnType(w.primitiveType()));
+ }
+ }
+ } catch (ReflectiveOperationException ex) {
+ throw new ExceptionInInitializerError(ex);
+ }
+ FIELD_GETTERS = List.of(fieldGetters);
+ ELEMENTS = new ClassValue<>() {
+ @Override
+ protected List<MethodHandle> computeValue(Class<?> type) {
+ return computeElementGetters(type);
+ }
+ };
+ }
+
+ private LayoutIteration() {}
+}
diff --git a/test/jdk/valhalla/valuetypes/LayoutIterationTest.java b/test/jdk/valhalla/valuetypes/LayoutIterationTest.java
new file mode 100644
index 00000000000..b0aadd7e794
--- /dev/null
+++ b/test/jdk/valhalla/valuetypes/LayoutIterationTest.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2025, 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.
+ */
+
+
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import jdk.internal.value.LayoutIteration;
+import jdk.internal.vm.annotation.ImplicitlyConstructible;
+import jdk.internal.vm.annotation.LooselyConsistentValue;
+import jdk.internal.vm.annotation.NullRestricted;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/*
+ * @test
+ * @summary test LayoutIteration
+ * @enablePreview
+ * @modules java.base/jdk.internal.vm.annotation
+ * java.base/jdk.internal.value
+ * @run junit/othervm LayoutIterationTest
+ */
+class LayoutIterationTest {
+
+ @LooselyConsistentValue
+ @ImplicitlyConstructible
+ static value class One {
+ int a;
+ short b;
+
+ One(int a, short b) {
+ this.a = a;
+ this.b = b;
+ }
+ }
+
+ @LooselyConsistentValue
+ static value class Two {
+ @NullRestricted
+ One one = new One(5, (short) 3);
+ One anotherOne = new One(4, (short) 2);
+ long l = 5L;
+ }
+
+ @Test
+ void test() {
+ Two t = new Two();
+ Set<Class<?>> classes = LayoutIteration.computeElementGetters(One.class).stream()
+ .map(mh -> mh.type().returnType()).collect(Collectors.toSet());
+ assertEquals(Set.of(int.class, short.class), classes);
+ Map<Class<?>, Object> values = LayoutIteration.computeElementGetters(Two.class).stream()
+ .collect(Collectors.toMap(mh -> mh.type().returnType(), mh -> {
+ try {
+ return (Object) mh.invoke(t);
+ } catch (Throwable ex) {
+ return Assertions.fail(ex);
+ }
+ }));
+ assertEquals(Map.of(
+ int.class, t.one.a,
+ short.class, t.one.b,
+ One.class, t.anotherOne,
+ long.class, t.l
+ ), values);
+ }
+}
From 4d6a7d5c795441193628e90bcc00a15dd1cdf72e Mon Sep 17 00:00:00 2001
From: liach <liach@openjdk.org>
Date: Wed, 12 Feb 2025 19:13:45 -0600
Subject: [PATCH 2/4] Fix redundant debug and failing IO test
---
.../share/classes/jdk/internal/value/LayoutIteration.java | 1 -
1 file changed, 1 deletion(-)
diff --git a/src/java.base/share/classes/jdk/internal/value/LayoutIteration.java b/src/java.base/share/classes/jdk/internal/value/LayoutIteration.java
index c99c2469ce4..946f27c6b3b 100644
--- a/src/java.base/share/classes/jdk/internal/value/LayoutIteration.java
+++ b/src/java.base/share/classes/jdk/internal/value/LayoutIteration.java
@@ -85,7 +85,6 @@ private static final class Sink {
void accept(long offsetNoHeader, Class<?> itemType) {
Wrapper w = itemType.isPrimitive() ? Wrapper.forPrimitiveType(itemType) : Wrapper.OBJECT;
- System.out.println(receiverType + " offset " + offsetNoHeader + " " + itemType);
var mh = MethodHandles.insertArguments(FIELD_GETTERS.get(w.ordinal()), 1, offsetNoHeader);
assert mh.type() == MethodType.methodType(w.primitiveType(), Object.class);
mh = JLIA.assertAsType(mh, MethodType.methodType(itemType, receiverType));
From 0e02b94f159eb99e19642dc75ae63053f3562dbc Mon Sep 17 00:00:00 2001
From: liach <liach@openjdk.org>
Date: Wed, 9 Apr 2025 07:38:07 -0500
Subject: [PATCH 3/4] Fix failing compiler tests, thanks to @TobiHartmann
---
src/hotspot/share/opto/library_call.cpp | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/src/hotspot/share/opto/library_call.cpp b/src/hotspot/share/opto/library_call.cpp
index ce8c943f4f0..69d6d33d911 100644
--- a/src/hotspot/share/opto/library_call.cpp
+++ b/src/hotspot/share/opto/library_call.cpp
@@ -2546,6 +2546,13 @@ bool LibraryCallKit::inline_unsafe_access(bool is_store, const BasicType type, c
if (field != nullptr) {
bt = type2field[field->type()->basic_type()];
}
+ if (bt != alias_type->basic_type()) {
+ // Type mismatch. Is it an access to a nested flat field?
+ field = k->get_field_by_offset(off, false);
+ if (field != nullptr) {
+ bt = type2field[field->type()->basic_type()];
+ }
+ }
assert(bt == alias_type->basic_type() || is_flat, "should match");
} else {
bt = alias_type->basic_type();
From 921a8d59961f46b0e29f5bd08644556d0eff3360 Mon Sep 17 00:00:00 2001
From: liach <liach@openjdk.org>
Date: Wed, 9 Apr 2025 07:48:27 -0500
Subject: [PATCH 4/4] Remove obsolete annotation
---
test/jdk/valhalla/valuetypes/LayoutIterationTest.java | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/test/jdk/valhalla/valuetypes/LayoutIterationTest.java b/test/jdk/valhalla/valuetypes/LayoutIterationTest.java
index b0aadd7e794..65f5b90176e 100644
--- a/test/jdk/valhalla/valuetypes/LayoutIterationTest.java
+++ b/test/jdk/valhalla/valuetypes/LayoutIterationTest.java
@@ -27,7 +27,6 @@
import java.util.stream.Collectors;
import jdk.internal.value.LayoutIteration;
-import jdk.internal.vm.annotation.ImplicitlyConstructible;
import jdk.internal.vm.annotation.LooselyConsistentValue;
import jdk.internal.vm.annotation.NullRestricted;
import org.junit.jupiter.api.Assertions;
@@ -46,7 +45,6 @@
class LayoutIterationTest {
@LooselyConsistentValue
- @ImplicitlyConstructible
static value class One {
int a;
short b;
@@ -54,6 +52,7 @@ static value class One {
One(int a, short b) {
this.a = a;
this.b = b;
+ super();
}
}