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Flatten non-static NullRestricted fields #18173

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Sep 21, 2023
Merged

Flatten non-static NullRestricted fields #18173

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6 changes: 6 additions & 0 deletions runtime/oti/j9.h
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Original file line number Diff line number Diff line change
Expand Up @@ -339,6 +339,11 @@ static const struct { \
#define J9_IS_FIELD_FLATTENED(fieldClazz, romFieldShape) \
(J9_IS_J9CLASS_FLATTENED(fieldClazz) && \
(J9_ARE_NO_BITS_SET((romFieldShape)->modifiers, J9AccVolatile) || (J9CLASS_UNPADDED_INSTANCE_SIZE(fieldClazz) <= sizeof(U_64))))
/* This will replace J9_IS_FIELD_FLATTENED when QTypes are removed. J9_IS_J9CLASS_FLATTENED will return false since the current check requires a primitive value type. */
#define J9_IS_NULL_RESTRICTED_FIELD_FLATTENED(fieldClazz, romFieldShape) \
(J9_ARE_ALL_BITS_SET((romFieldShape)->modifiers, J9FieldFlagIsNullRestricted) && \
J9_IS_J9CLASS_FLATTENED(fieldClazz) && \
(J9_ARE_NO_BITS_SET((romFieldShape)->modifiers, J9AccVolatile) || (J9CLASS_UNPADDED_INSTANCE_SIZE(fieldClazz) <= sizeof(U_64))))
#define J9_VALUETYPE_FLATTENED_SIZE(clazz) (J9CLASS_HAS_4BYTE_PREPADDING((clazz)) ? ((clazz)->totalInstanceSize - sizeof(U_32)) : (clazz)->totalInstanceSize)
#define IS_REF_OR_VAL_SIGNATURE(firstChar) ('L' == (firstChar) || 'Q' == (firstChar))
#define IS_QTYPE(firstChar) ('Q' == (firstChar))
Expand All @@ -347,6 +352,7 @@ static const struct { \
#define J9_IS_J9CLASS_PRIMITIVE_VALUETYPE(clazz) FALSE
#define J9_IS_J9CLASS_FLATTENED(clazz) FALSE
#define J9_IS_FIELD_FLATTENED(fieldClazz, romFieldShape) FALSE
#define J9_IS_NULL_RESTRICTED_FIELD_FLATTENED(fieldClazz, romFieldShape) FALSE
#define J9_VALUETYPE_FLATTENED_SIZE(clazz)((UDATA) 0) /* It is not possible for this macro to be used since we always check J9_IS_J9CLASS_FLATTENED before ever using it. */
#define IS_REF_OR_VAL_SIGNATURE(firstChar) ('L' == (firstChar))
#define IS_QTYPE(firstChar) FALSE
Expand Down
58 changes: 41 additions & 17 deletions runtime/vm/createramclass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2006,9 +2006,47 @@ loadFlattenableFieldValueClasses(J9VMThread *currentThread, J9ClassLoader *class
*valueTypeFlags |= J9ClassLargestAlignmentConstraintDouble;
break;
case 'L':
*valueTypeFlags |= (J9ClassLargestAlignmentConstraintReference | J9ClassHasReferences);
eligibleForFastSubstitutability = false;
{
if (J9_ARE_ALL_BITS_SET(modifiers, J9FieldFlagIsNullRestricted)) {
J9Class *valueClass = internalFindClassUTF8(currentThread, signatureChars + 1, signatureLength - 2, classLoader, classPreloadFlags);
if (NULL == valueClass) {
result = FALSE;
goto done;
} else {
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J9ROMClass *valueROMClass = valueClass->romClass;

/* A NullRestricted field must be in a value class with an
* ImplicitCreation attribute. The attribute must have the ACC_DEFAULT flag set.
* Static fields will be checked during class preparation.
*/
if (J9_ARE_NO_BITS_SET(valueROMClass->modifiers, J9AccValueType)
|| J9_ARE_NO_BITS_SET(valueROMClass->optionalFlags, J9_ROMCLASS_OPTINFO_IMPLICITCREATION_ATTRIBUTE)
|| J9_ARE_NO_BITS_SET(getImplicitCreationFlags(valueROMClass), J9AccImplicitCreateHasDefaultValue)
) {
setCurrentExceptionForBadClass(currentThread, J9ROMCLASS_CLASSNAME(romClass), J9VMCONSTANTPOOL_JAVALANGINCOMPATIBLECLASSCHANGEERROR,
J9NLS_VM_NULLRESTRICTED_MUST_BE_IN_DEFAULT_IMPLICITCREATION_VALUE_CLASS);
}

if (!J9_IS_NULL_RESTRICTED_FIELD_FLATTENED(valueClass, field)) {
*valueTypeFlags |= (J9ClassContainsUnflattenedFlattenables | J9ClassHasReferences);
eligibleForFastSubstitutability = false;
} else if (J9_ARE_NO_BITS_SET(valueClass->classFlags, J9ClassCanSupportFastSubstitutability)) {
eligibleForFastSubstitutability = false;
}

J9FlattenedClassCacheEntry *entry = J9_VM_FCC_ENTRY_FROM_FCC(flattenedClassCache, flattenableFieldCount);
entry->clazz = valueClass;
entry->field = field;
entry->offset = UDATA_MAX;
flattenableFieldCount += 1;
}
*valueTypeFlags |= (valueClass->classFlags & (J9ClassLargestAlignmentConstraintDouble | J9ClassLargestAlignmentConstraintReference | J9ClassHasReferences));
} else {
*valueTypeFlags |= (J9ClassLargestAlignmentConstraintReference | J9ClassHasReferences);
eligibleForFastSubstitutability = false;
}
break;
}
case 'F':
eligibleForFastSubstitutability = false;
break;
Expand Down Expand Up @@ -2059,7 +2097,7 @@ checkFlattenableFieldValueClasses(J9VMThread *currentThread, J9ClassLoader *clas
J9ROMFieldShape *field = romFieldsStartDo(romClass, &fieldWalkState);
BOOLEAN result = TRUE;

/* iterate over fields and load classes of fields marked as QTypes */
/* iterate over fields and load classes of fields marked as QTypes or NullRestricted */
while (NULL != field) {
const U_32 modifiers = field->modifiers;
J9UTF8 *signature = J9ROMFIELDSHAPE_SIGNATURE(field);
Expand All @@ -2083,20 +2121,6 @@ checkFlattenableFieldValueClasses(J9VMThread *currentThread, J9ClassLoader *clas
result = FALSE;
break;
}

/* A NullRestricted field must be in a value class with an
* ImplicitCreation attribute. The attribute must have the ACC_DEFAULT flag set.
* Static fields will be checked during class preparation.
*/
if (J9_ARE_ALL_BITS_SET(modifiers, J9FieldFlagIsNullRestricted)) {
if (J9_ARE_NO_BITS_SET(valueROMClass->modifiers, J9AccValueType)
|| J9_ARE_NO_BITS_SET(valueROMClass->optionalFlags, J9_ROMCLASS_OPTINFO_IMPLICITCREATION_ATTRIBUTE)
|| J9_ARE_NO_BITS_SET(getImplicitCreationFlags(valueROMClass), J9AccImplicitCreateHasDefaultValue)
) {
setCurrentExceptionForBadClass(currentThread, J9ROMCLASS_CLASSNAME(romClass), J9VMCONSTANTPOOL_JAVALANGINCOMPATIBLECLASSCHANGEERROR,
J9NLS_VM_NULLRESTRICTED_MUST_BE_IN_DEFAULT_IMPLICITCREATION_VALUE_CLASS);
}
}
}
}
field = romFieldsNextDo(&fieldWalkState);
Expand Down