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/*
* Copyright (c) 2011, 2022, 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.
*
*/
#ifndef SHARE_OOPS_FIELDINFO_HPP
#define SHARE_OOPS_FIELDINFO_HPP
#include "oops/constantPool.hpp"
#include "oops/symbol.hpp"
#include "oops/typeArrayOop.hpp"
#include "utilities/vmEnums.hpp"
// This class represents the field information contained in the fields
// array of an InstanceKlass. Currently it's laid on top an array of
// Java shorts but in the future it could simply be used as a real
// array type. FieldInfo generally shouldn't be used directly.
// Fields should be queried either through InstanceKlass or through
// the various FieldStreams.
class FieldInfo {
friend class fieldDescriptor;
friend class JavaFieldStream;
friend class ClassFileParser;
public:
// fields
// Field info extracted from the class file and stored
// as an array of 6 shorts.
#define FIELDINFO_TAG_SIZE 2
#define FIELDINFO_TAG_OFFSET 1 << 0
#define FIELDINFO_TAG_CONTENDED 1 << 1
// Packed field has the tag, and can be either of:
// hi bits <--------------------------- lo bits
// |---------high---------|---------low---------|
// ..........................................CO
// ..........................................00 - non-contended field
// [--contention_group--]....................10 - contended field with contention group
// [------------------offset----------------]01 - real field offset
// Bit O indicates if the packed field contains an offset (O=1) or not (O=0)
// Bit C indicates if the field is contended (C=1) or not (C=0)
// (if it is contended, the high packed field contains the contention group)
enum FieldOffset {
access_flags_offset = 0,
name_index_offset = 1,
signature_index_offset = 2,
initval_index_offset = 3,
low_packed_offset = 4,
high_packed_offset = 5,
field_slots = 6
};
private:
u2 _shorts[field_slots];
void set_name_index(u2 val) { _shorts[name_index_offset] = val; }
void set_signature_index(u2 val) { _shorts[signature_index_offset] = val; }
void set_initval_index(u2 val) { _shorts[initval_index_offset] = val; }
u2 name_index() const { return _shorts[name_index_offset]; }
u2 signature_index() const { return _shorts[signature_index_offset]; }
u2 initval_index() const { return _shorts[initval_index_offset]; }
public:
static FieldInfo* from_field_array(Array<u2>* fields, int index) {
return ((FieldInfo*)fields->adr_at(index * field_slots));
}
static FieldInfo* from_field_array(u2* fields, int index) {
return ((FieldInfo*)(fields + index * field_slots));
}
void initialize(u2 access_flags,
u2 name_index,
u2 signature_index,
u2 initval_index) {
_shorts[access_flags_offset] = access_flags;
_shorts[name_index_offset] = name_index;
_shorts[signature_index_offset] = signature_index;
_shorts[initval_index_offset] = initval_index;
_shorts[low_packed_offset] = 0;
_shorts[high_packed_offset] = 0;
}
u2 access_flags() const { return _shorts[access_flags_offset]; }
u4 offset() const {
assert((_shorts[low_packed_offset] & FIELDINFO_TAG_OFFSET) != 0, "Offset must have been set");
return build_int_from_shorts(_shorts[low_packed_offset], _shorts[high_packed_offset]) >> FIELDINFO_TAG_SIZE;
}
bool is_contended() const {
return (_shorts[low_packed_offset] & FIELDINFO_TAG_CONTENDED) != 0;
}
u2 contended_group() const {
assert((_shorts[low_packed_offset] & FIELDINFO_TAG_OFFSET) == 0, "Offset must not have been set");
assert((_shorts[low_packed_offset] & FIELDINFO_TAG_CONTENDED) != 0, "Field must be contended");
return _shorts[high_packed_offset];
}
bool is_offset_set() const {
return (_shorts[low_packed_offset] & FIELDINFO_TAG_OFFSET)!= 0;
}
Symbol* name(ConstantPool* cp) const {
int index = name_index();
if (is_internal()) {
return lookup_symbol(index);
}
return cp->symbol_at(index);
}
Symbol* signature(ConstantPool* cp) const {
int index = signature_index();
if (is_internal()) {
return lookup_symbol(index);
}
return cp->symbol_at(index);
}
void set_access_flags(u2 val) { _shorts[access_flags_offset] = val; }
void set_offset(u4 val) {
val = val << FIELDINFO_TAG_SIZE; // make room for tag
_shorts[low_packed_offset] = extract_low_short_from_int(val) | FIELDINFO_TAG_OFFSET;
_shorts[high_packed_offset] = extract_high_short_from_int(val);
}
void set_contended_group(u2 val) {
assert((_shorts[low_packed_offset] & FIELDINFO_TAG_OFFSET) == 0, "Offset must not have been set");
assert((_shorts[low_packed_offset] & FIELDINFO_TAG_CONTENDED) == 0, "Overwriting contended group");
_shorts[low_packed_offset] |= FIELDINFO_TAG_CONTENDED;
_shorts[high_packed_offset] = val;
}
bool is_internal() const {
return (access_flags() & JVM_ACC_FIELD_INTERNAL) != 0;
}
bool is_stable() const {
return (access_flags() & JVM_ACC_FIELD_STABLE) != 0;
}
void set_stable(bool z) {
if (z) _shorts[access_flags_offset] |= JVM_ACC_FIELD_STABLE;
else _shorts[access_flags_offset] &= ~JVM_ACC_FIELD_STABLE;
}
Symbol* lookup_symbol(int symbol_index) const {
assert(is_internal(), "only internal fields");
return Symbol::vm_symbol_at(static_cast<vmSymbolID>(symbol_index));
}
};
#endif // SHARE_OOPS_FIELDINFO_HPP
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