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8383559: [lworld] Autobox cache removal causes performance regression with Renaissance benchmarks #2390

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8383559: [lworld] Autobox cache removal causes performance regression with Renaissance benchmarks #2390

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f24c55e
JDK-8383559
TobiHartmann May 5, 2026
88b9e2f
Update src/hotspot/share/opto/type.cpp
TobiHartmann May 6, 2026
d51e0ad
Reviewer comments
TobiHartmann May 13, 2026
94f0f66
Merge branch 'lworld' into JDK-8383559
TobiHartmann May 13, 2026
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4 changes: 1 addition & 3 deletions src/hotspot/share/ci/ciField.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -499,9 +499,7 @@ bool ciField::is_call_site_target() {

bool ciField::is_autobox_cache() {
ciSymbol* klass_name = holder()->name();
// The box cache is disabled when boxes are value classes.
return (!Arguments::is_valhalla_enabled() &&
name() == ciSymbols::cache_field_name() &&
return (name() == ciSymbols::cache_field_name() &&
holder()->uses_default_loader() &&
(klass_name == ciSymbols::java_lang_Character_CharacterCache() ||
klass_name == ciSymbols::java_lang_Byte_ByteCache() ||
Expand Down
13 changes: 6 additions & 7 deletions src/hotspot/share/runtime/deoptimization.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1146,14 +1146,14 @@ template<typename PrimitiveType, typename CacheType, typename BoxType> class Box
protected:
static BoxCache<PrimitiveType, CacheType, BoxType> *_singleton;
BoxCache(Thread* thread) {
assert(!Arguments::is_valhalla_enabled(), "Should not use box caches with enable preview");
InstanceKlass* ik = BoxCacheBase<CacheType>::find_cache_klass(thread, CacheType::symbol());
if (ik->is_in_error_state()) {
_low = 1;
_high = 0;
_cache = nullptr;
} else {
refArrayOop cache = CacheType::cache(ik);
assert(!cache->is_flatArray(), "box caches must be reference arrays");
assert(cache->length() > 0, "Empty cache");
_low = BoxType::value(cache->obj_at(0));
_high = checked_cast<PrimitiveType>(_low + cache->length() - 1);
Expand Down Expand Up @@ -1218,8 +1218,11 @@ class BooleanBoxCache : public BoxCacheBase<java_lang_Boolean> {
_true_cache = nullptr;
_false_cache = nullptr;
} else {
_true_cache = JNIHandles::make_global(Handle(thread, java_lang_Boolean::get_TRUE(ik)));
_false_cache = JNIHandles::make_global(Handle(thread, java_lang_Boolean::get_FALSE(ik)));
oop true_cache = java_lang_Boolean::get_TRUE(ik);
oop false_cache = java_lang_Boolean::get_FALSE(ik);
assert(true_cache != nullptr && false_cache != nullptr, "Boolean cache fields must be initialized");
_true_cache = JNIHandles::make_global(Handle(thread, true_cache));
_false_cache = JNIHandles::make_global(Handle(thread, false_cache));
}
}
~BooleanBoxCache() {
Expand Down Expand Up @@ -1256,10 +1259,6 @@ class BooleanBoxCache : public BoxCacheBase<java_lang_Boolean> {
BooleanBoxCache* BooleanBoxCache::_singleton = nullptr;

oop Deoptimization::get_cached_box(AutoBoxObjectValue* bv, frame* fr, RegisterMap* reg_map, bool& cache_init_error, TRAPS) {
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if (Arguments::enable_preview()) {
// Box caches are not used with enable preview.
return nullptr;
}
Klass* k = java_lang_Class::as_Klass(bv->klass()->as_ConstantOopReadValue()->value()());
BasicType box_type = vmClasses::box_klass_type(k);
if (box_type != T_OBJECT) {
Expand Down
37 changes: 23 additions & 14 deletions src/java.base/share/classes/java/lang/Boolean.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2026, 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 All @@ -25,7 +25,6 @@

package java.lang;

import jdk.internal.misc.PreviewFeatures;
import jdk.internal.value.DeserializeConstructor;
import jdk.internal.vm.annotation.IntrinsicCandidate;

Expand Down Expand Up @@ -112,6 +111,7 @@ public final class Boolean implements java.io.Serializable,
* if possible.
*/
@Deprecated(since="9")
@DeserializeConstructor
public Boolean(boolean value) {
this.value = value;
}
Expand Down Expand Up @@ -168,25 +168,34 @@ public boolean booleanValue() {

/**
* Returns a {@code Boolean} instance representing the specified
* {@code boolean} value. If the specified {@code boolean} value
* is {@code true}, this method returns {@code Boolean.TRUE};
* if it is {@code false}, this method returns {@code Boolean.FALSE}.
* If a new {@code Boolean} instance is not required, this method
* should generally be used in preference to the constructor
* {@link #Boolean(boolean)}, as this method is likely to yield
* significantly better space and time performance.
* {@code boolean} value.
* <div class="preview-block">
* <div class="preview-comment">
* <p>
* - When preview features are NOT enabled, {@code Boolean} is an identity class.
* If the specified {@code boolean} value is {@code true},
* this method returns {@code Boolean.TRUE}; if it is
* {@code false}, this method returns {@code Boolean.FALSE}.
* If a new {@code Boolean} instance is not required, this
* method should generally be used in preference to the
* constructor {@link #Boolean(boolean)}, as this method is
* likely to yield significantly better space and time
* performance.
* </p>
* <p>
* - When preview features are enabled, {@code Boolean} is a {@linkplain Class#isValue value class}.
* The {@code valueOf} behavior is the same as invoking the constructor.
* </p>
* </div>
* </div>
*
* @param b a boolean value.
* @return a {@code Boolean} instance representing {@code b}.
* @since 1.4
*/
@IntrinsicCandidate
@DeserializeConstructor
public static Boolean valueOf(boolean b) {
if (!PreviewFeatures.isEnabled()) {
return (b ? TRUE : FALSE);
}
return new Boolean(b);
return (b ? TRUE : FALSE);
}

/**
Expand Down
47 changes: 24 additions & 23 deletions src/java.base/share/classes/java/lang/Byte.java
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
import jdk.internal.misc.CDS;
import jdk.internal.misc.PreviewFeatures;
import jdk.internal.value.DeserializeConstructor;
import jdk.internal.value.ValueClass;
import jdk.internal.vm.annotation.AOTSafeClassInitializer;
import jdk.internal.vm.annotation.IntrinsicCandidate;
import jdk.internal.vm.annotation.Stable;
Expand Down Expand Up @@ -123,25 +124,28 @@ private ByteCache() {}
static Byte[] archivedCache;

static {
if (!PreviewFeatures.isEnabled()) {
final int size = -(-128) + 127 + 1;

// Load and use the archived cache if it exists
CDS.initializeFromArchive(ByteCache.class);
if (archivedCache == null) {
Byte[] c = new Byte[size];
byte value = (byte)-128;
for(int i = 0; i < size; i++) {
c[i] = new Byte(value++);
}
archivedCache = c;
final int size = -(-128) + 127 + 1;

// Load and use the archived cache if it exists
CDS.initializeFromArchive(ByteCache.class);
if (archivedCache == null) {
Byte[] c = newCacheArray(size);
byte value = (byte)-128;
for(int i = 0; i < size; i++) {
c[i] = new Byte(value++);
}
cache = archivedCache;
assert cache.length == size;
} else {
cache = null;
assert archivedCache == null;
archivedCache = c;
}
cache = archivedCache;
assert cache.length == size;
}

private static Byte[] newCacheArray(int size) {
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@liach liach May 6, 2026

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I don't think we need this - we should be able to revert to mainline code. The only code I think that need any update would be the old new Byte[size] should become (Byte[]) ValueClass.newReferenceArray(Byte.class, size) both with and without preview.

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@TobiHartmann TobiHartmann May 13, 2026

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new Byte[size] should become (Byte[]) ValueClass.newReferenceArray(Byte.class, size) both with and without preview.

@liach That's not possible because ValueClass.newReferenceArray throws when preview is disabled because boxes are identity classes then.

// ValueClass.newReferenceArray requires a value class component.
if (PreviewFeatures.isEnabled()) {
return (Byte[]) ValueClass.newReferenceArray(Byte.class, size);
}
return new Byte[size];
}
}

Expand Down Expand Up @@ -171,13 +175,9 @@ private ByteCache() {}
* @since 1.5
*/
@IntrinsicCandidate
@DeserializeConstructor
public static Byte valueOf(byte b) {
if (!PreviewFeatures.isEnabled()) {
final int offset = 128;
return ByteCache.cache[(int) b + offset];
}
return new Byte(b);
final int offset = 128;
return ByteCache.cache[(int) b + offset];
}

/**
Expand Down Expand Up @@ -378,6 +378,7 @@ public static Byte decode(String nm) throws NumberFormatException {
* likely to yield significantly better space and time performance.
*/
@Deprecated(since="9")
@DeserializeConstructor
public Byte(byte value) {
this.value = value;
}
Expand Down
44 changes: 23 additions & 21 deletions src/java.base/share/classes/java/lang/Character.java
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
import jdk.internal.misc.CDS;
import jdk.internal.misc.PreviewFeatures;
import jdk.internal.value.DeserializeConstructor;
import jdk.internal.value.ValueClass;
import jdk.internal.vm.annotation.AOTSafeClassInitializer;
import jdk.internal.vm.annotation.IntrinsicCandidate;
import jdk.internal.vm.annotation.Stable;
Expand Down Expand Up @@ -9422,6 +9423,7 @@ public static final UnicodeScript forName(String scriptName) {
* likely to yield significantly better space and time performance.
*/
@Deprecated(since="9")
@DeserializeConstructor
public Character(char value) {
this.value = value;
}
Expand All @@ -9435,24 +9437,27 @@ private CharacterCache(){}
static Character[] archivedCache;

static {
if (!PreviewFeatures.isEnabled()) {
int size = 127 + 1;

// Load and use the archived cache if it exists
CDS.initializeFromArchive(CharacterCache.class);
if (archivedCache == null) {
Character[] c = new Character[size];
for (int i = 0; i < size; i++) {
c[i] = new Character((char) i);
}
archivedCache = c;
int size = 127 + 1;

// Load and use the archived cache if it exists
CDS.initializeFromArchive(CharacterCache.class);
if (archivedCache == null) {
Character[] c = newCacheArray(size);
for (int i = 0; i < size; i++) {
c[i] = new Character((char) i);
}
cache = archivedCache;
assert cache.length == size;
} else {
cache = null;
assert archivedCache == null;
archivedCache = c;
}
cache = archivedCache;
assert cache.length == size;
}

private static Character[] newCacheArray(int size) {
// ValueClass.newReferenceArray requires a value class component.
if (PreviewFeatures.isEnabled()) {
return (Character[]) ValueClass.newReferenceArray(Character.class, size);
}
return new Character[size];
}
}

Expand Down Expand Up @@ -9485,12 +9490,9 @@ private CharacterCache(){}
* @since 1.5
*/
@IntrinsicCandidate
@DeserializeConstructor
public static Character valueOf(char c) {
if (!PreviewFeatures.isEnabled()) {
if (c <= 127) { // must cache
return CharacterCache.cache[(int) c];
}
if (c <= 127) { // must cache
return CharacterCache.cache[(int) c];
}
return new Character(c);
}
Expand Down
25 changes: 18 additions & 7 deletions src/java.base/share/classes/java/lang/Double.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2026, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2025, Alibaba Group Holding Limited. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
Expand Down Expand Up @@ -968,18 +968,28 @@ public static Double valueOf(String s) throws NumberFormatException {
/**
* Returns a {@code Double} instance representing the specified
* {@code double} value.
* If a new {@code Double} instance is not required, this method
* should generally be used in preference to the constructor
* {@link #Double(double)}, as this method is likely to yield
* significantly better space and time performance by caching
* frequently requested values.
* <div class="preview-block">
* <div class="preview-comment">
* <p>
* - When preview features are NOT enabled, {@code Double} is an identity class.
* If a new {@code Double} instance is not required, this
* method should generally be used in preference to the
* constructor {@link #Double(double)}, as this method is
* likely to yield significantly better space and time
* performance by caching frequently requested values.
* </p>
* <p>
* - When preview features are enabled, {@code Double} is a {@linkplain Class#isValue value class}.
* The {@code valueOf} behavior is the same as invoking the constructor.
* </p>
* </div>
* </div>
*
* @param d a double value.
* @return a {@code Double} instance representing {@code d}.
* @since 1.5
*/
@IntrinsicCandidate
@DeserializeConstructor
public static Double valueOf(double d) {
return new Double(d);
}
Expand Down Expand Up @@ -1075,6 +1085,7 @@ public static boolean isFinite(double d) {
* likely to yield significantly better space and time performance.
*/
@Deprecated(since="9")
@DeserializeConstructor
public Double(double value) {
this.value = value;
}
Expand Down
25 changes: 18 additions & 7 deletions src/java.base/share/classes/java/lang/Float.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 1994, 2025, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1994, 2026, 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 @@ -571,18 +571,28 @@ public static Float valueOf(String s) throws NumberFormatException {
/**
* Returns a {@code Float} instance representing the specified
* {@code float} value.
* If a new {@code Float} instance is not required, this method
* should generally be used in preference to the constructor
* {@link #Float(float)}, as this method is likely to yield
* significantly better space and time performance by caching
* frequently requested values.
* <div class="preview-block">
* <div class="preview-comment">
* <p>
* - When preview features are NOT enabled, {@code Float} is an identity class.
* If a new {@code Float} instance is not required, this
* method should generally be used in preference to the
* constructor {@link #Float(float)}, as this method is
* likely to yield significantly better space and time
* performance by caching frequently requested values.
* </p>
* <p>
* - When preview features are enabled, {@code Float} is a {@linkplain Class#isValue value class}.
* The {@code valueOf} behavior is the same as invoking the constructor.
* </p>
* </div>
* </div>
*
* @param f a float value.
* @return a {@code Float} instance representing {@code f}.
* @since 1.5
*/
@IntrinsicCandidate
@DeserializeConstructor
public static Float valueOf(float f) {
return new Float(f);
}
Expand Down Expand Up @@ -678,6 +688,7 @@ public static boolean isFinite(float f) {
* likely to yield significantly better space and time performance.
*/
@Deprecated(since="9")
@DeserializeConstructor
public Float(float value) {
this.value = value;
}
Expand Down
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