1 /*
  2  * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #include "precompiled.hpp"
 26 #include "classfile/altHashing.hpp"
 27 #include "classfile/javaClasses.inline.hpp"
 28 #include "gc/shared/collectedHeap.inline.hpp"
 29 #include "gc/shared/gc_globals.hpp"
 30 #include "memory/resourceArea.hpp"
 31 #include "memory/universe.hpp"
 32 #include "oops/access.inline.hpp"
 33 #include "oops/compressedKlass.inline.hpp"
 34 #include "oops/compressedOops.inline.hpp"
 35 #include "oops/oop.inline.hpp"
 36 #include "oops/verifyOopClosure.hpp"
 37 #include "runtime/handles.inline.hpp"
 38 #include "runtime/javaThread.hpp"
 39 #include "runtime/synchronizer.hpp"
 40 #include "utilities/macros.hpp"
 41 
 42 void oopDesc::print_on(outputStream* st) const {
 43   if (*((juint*)this) == badHeapWordVal) {
 44     st->print_cr("BAD WORD");
 45   } else if (*((juint*)this) == badMetaWordVal) {
 46     st->print_cr("BAD META WORD");
 47   } else {
 48     klass()->oop_print_on(cast_to_oop(this), st);
 49   }
 50 }
 51 
 52 void oopDesc::print_address_on(outputStream* st) const {
 53   st->print("{" PTR_FORMAT "}", p2i(this));
 54 
 55 }
 56 
 57 void oopDesc::print_name_on(outputStream* st) const {
 58   if (*((juint*)this) == badHeapWordVal) {
 59     st->print_cr("BAD WORD");
 60   } else if (*((juint*)this) == badMetaWordVal) {
 61     st->print_cr("BAD META WORD");
 62   } else {
 63     st->print_cr("%s", klass()->external_name());
 64   }
 65 }
 66 
 67 void oopDesc::print()         { print_on(tty);         }
 68 
 69 void oopDesc::print_address() { print_address_on(tty); }
 70 
 71 char* oopDesc::print_string() {
 72   stringStream st;
 73   print_on(&st);
 74   return st.as_string();
 75 }
 76 
 77 void oopDesc::print_value() {
 78   print_value_on(tty);
 79 }
 80 
 81 char* oopDesc::print_value_string() {
 82   char buf[100];
 83   stringStream st(buf, sizeof(buf));
 84   print_value_on(&st);
 85   return st.as_string();
 86 }
 87 
 88 void oopDesc::print_value_on(outputStream* st) const {
 89   oop obj = const_cast<oopDesc*>(this);
 90   if (java_lang_String::is_instance(obj)) {
 91     java_lang_String::print(obj, st);
 92     print_address_on(st);
 93   } else {
 94     klass()->oop_print_value_on(obj, st);
 95   }
 96 }
 97 
 98 
 99 void oopDesc::verify_on(outputStream* st, oopDesc* oop_desc) {
100   if (oop_desc != nullptr) {
101     oop_desc->klass()->oop_verify_on(oop_desc, st);
102   }
103 }
104 
105 
106 void oopDesc::verify(oopDesc* oop_desc) {
107   verify_on(tty, oop_desc);
108 }
109 
110 intptr_t oopDesc::slow_identity_hash() {
111   // slow case; we have to acquire the micro lock in order to locate the header
112   Thread* current = Thread::current();
113   return ObjectSynchronizer::FastHashCode(current, this);
114 }
115 
116 // used only for asserts and guarantees
117 bool oopDesc::is_oop(oop obj, bool ignore_mark_word) {
118   if (!Universe::heap()->is_oop(obj)) {
119     return false;
120   }
121 
122   // Header verification: the mark is typically non-zero. If we're
123   // at a safepoint, it must not be zero, except when using the new lightweight locking.
124   // Outside of a safepoint, the header could be changing (for example,
125   // another thread could be inflating a lock on this object).
126   if (ignore_mark_word) {
127     return true;
128   }
129   if (obj->mark().value() != 0) {
130     return true;
131   }
132   return LockingMode == LM_LIGHTWEIGHT || !SafepointSynchronize::is_at_safepoint();
133 }
134 
135 // used only for asserts and guarantees
136 bool oopDesc::is_oop_or_null(oop obj, bool ignore_mark_word) {
137   return obj == nullptr ? true : is_oop(obj, ignore_mark_word);
138 }
139 
140 VerifyOopClosure VerifyOopClosure::verify_oop;
141 
142 template <class T> void VerifyOopClosure::do_oop_work(T* p) {
143   oop obj = RawAccess<>::oop_load(p);
144   guarantee(oopDesc::is_oop_or_null(obj), "invalid oop: " PTR_FORMAT, p2i(obj));
145 }
146 
147 void VerifyOopClosure::do_oop(oop* p)       { VerifyOopClosure::do_oop_work(p); }
148 void VerifyOopClosure::do_oop(narrowOop* p) { VerifyOopClosure::do_oop_work(p); }
149 
150 // type test operations that doesn't require inclusion of oop.inline.hpp.
151 bool oopDesc::is_instance_noinline()    const { return is_instance();    }
152 bool oopDesc::is_instanceRef_noinline() const { return is_instanceRef(); }
153 bool oopDesc::is_stackChunk_noinline()  const { return is_stackChunk();  }
154 bool oopDesc::is_array_noinline()       const { return is_array();       }
155 bool oopDesc::is_objArray_noinline()    const { return is_objArray();    }
156 bool oopDesc::is_typeArray_noinline()   const { return is_typeArray();   }
157 
158 bool oopDesc::has_klass_gap() {
159   // Only has a klass gap when compressed class pointers are used.
160   return UseCompressedClassPointers;
161 }
162 
163 #if INCLUDE_CDS_JAVA_HEAP
164 void oopDesc::set_narrow_klass(narrowKlass nk) {
165   assert(DumpSharedSpaces, "Used by CDS only. Do not abuse!");
166   assert(UseCompressedClassPointers, "must be");
167   _metadata._compressed_klass = nk;
168 }
169 #endif
170 
171 void* oopDesc::load_klass_raw(oop obj) {
172   if (UseCompressedClassPointers) {
173     narrowKlass narrow_klass = obj->_metadata._compressed_klass;
174     if (narrow_klass == 0) return nullptr;
175     return (void*)CompressedKlassPointers::decode_raw(narrow_klass);
176   } else {
177     return obj->_metadata._klass;
178   }
179 }
180 
181 void* oopDesc::load_oop_raw(oop obj, int offset) {
182   uintptr_t addr = (uintptr_t)(void*)obj + (uint)offset;
183   if (UseCompressedOops) {
184     narrowOop narrow_oop = *(narrowOop*)addr;
185     if (CompressedOops::is_null(narrow_oop)) return nullptr;
186     return (void*)CompressedOops::decode_raw(narrow_oop);
187   } else {
188     return *(void**)addr;
189   }
190 }
191 
192 oop oopDesc::obj_field_acquire(int offset) const                      { return HeapAccess<MO_ACQUIRE>::oop_load_at(as_oop(), offset); }
193 
194 void oopDesc::obj_field_put_raw(int offset, oop value)                { assert(!(UseZGC && ZGenerational), "Generational ZGC must use store barriers");
195                                                                         RawAccess<>::oop_store_at(as_oop(), offset, value); }
196 void oopDesc::release_obj_field_put(int offset, oop value)            { HeapAccess<MO_RELEASE>::oop_store_at(as_oop(), offset, value); }
197 void oopDesc::obj_field_put_volatile(int offset, oop value)           { HeapAccess<MO_SEQ_CST>::oop_store_at(as_oop(), offset, value); }
198 
199 address oopDesc::address_field(int offset) const                      { return *field_addr<address>(offset); }
200 address oopDesc::address_field_acquire(int offset) const              { return Atomic::load_acquire(field_addr<address>(offset)); }
201 
202 void oopDesc::address_field_put(int offset, address value)            { *field_addr<address>(offset) = value; }
203 void oopDesc::release_address_field_put(int offset, address value)    { Atomic::release_store(field_addr<address>(offset), value); }
204 
205 Metadata* oopDesc::metadata_field(int offset) const                   { return *field_addr<Metadata*>(offset); }
206 void oopDesc::metadata_field_put(int offset, Metadata* value)         { *field_addr<Metadata*>(offset) = value; }
207 
208 Metadata* oopDesc::metadata_field_acquire(int offset) const           { return Atomic::load_acquire(field_addr<Metadata*>(offset)); }
209 void oopDesc::release_metadata_field_put(int offset, Metadata* value) { Atomic::release_store(field_addr<Metadata*>(offset), value); }
210 
211 jbyte oopDesc::byte_field_acquire(int offset) const                   { return Atomic::load_acquire(field_addr<jbyte>(offset)); }
212 void oopDesc::release_byte_field_put(int offset, jbyte value)         { Atomic::release_store(field_addr<jbyte>(offset), value); }
213 
214 jchar oopDesc::char_field_acquire(int offset) const                   { return Atomic::load_acquire(field_addr<jchar>(offset)); }
215 void oopDesc::release_char_field_put(int offset, jchar value)         { Atomic::release_store(field_addr<jchar>(offset), value); }
216 
217 jboolean oopDesc::bool_field_acquire(int offset) const                { return Atomic::load_acquire(field_addr<jboolean>(offset)); }
218 void oopDesc::release_bool_field_put(int offset, jboolean value)      { Atomic::release_store(field_addr<jboolean>(offset), jboolean(value & 1)); }
219 
220 jint oopDesc::int_field_acquire(int offset) const                     { return Atomic::load_acquire(field_addr<jint>(offset)); }
221 void oopDesc::release_int_field_put(int offset, jint value)           { Atomic::release_store(field_addr<jint>(offset), value); }
222 
223 jshort oopDesc::short_field_acquire(int offset) const                 { return Atomic::load_acquire(field_addr<jshort>(offset)); }
224 void oopDesc::release_short_field_put(int offset, jshort value)       { Atomic::release_store(field_addr<jshort>(offset), value); }
225 
226 jlong oopDesc::long_field_acquire(int offset) const                   { return Atomic::load_acquire(field_addr<jlong>(offset)); }
227 void oopDesc::release_long_field_put(int offset, jlong value)         { Atomic::release_store(field_addr<jlong>(offset), value); }
228 
229 jfloat oopDesc::float_field_acquire(int offset) const                 { return Atomic::load_acquire(field_addr<jfloat>(offset)); }
230 void oopDesc::release_float_field_put(int offset, jfloat value)       { Atomic::release_store(field_addr<jfloat>(offset), value); }
231 
232 jdouble oopDesc::double_field_acquire(int offset) const               { return Atomic::load_acquire(field_addr<jdouble>(offset)); }
233 void oopDesc::release_double_field_put(int offset, jdouble value)     { Atomic::release_store(field_addr<jdouble>(offset), value); }
234 
235 #ifdef ASSERT
236 bool oopDesc::size_might_change() {
237   // UseParallelGC and UseG1GC can change the length field
238   // of an "old copy" of an object array in the young gen so it indicates
239   // the grey portion of an already copied array. This will cause the first
240   // disjunct below to fail if the two comparands are computed across such
241   // a concurrent change.
242   return Universe::heap()->is_gc_active() && is_objArray() && is_forwarded() && (UseParallelGC || UseG1GC);
243 }
244 #endif