1 /*
2 * Copyright (c) 2017, 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 #include "precompiled.hpp"
25 #include "code/relocInfo.hpp"
26 #include "code/nativeInst.hpp"
27 #include "code/nmethod.hpp"
28 #include "gc/z/zHash.inline.hpp"
29 #include "gc/z/zNMethodTable.hpp"
30 #include "logging/log.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/atomic.hpp"
35 #include "utilities/debug.hpp"
36
37 class ZNMethodWithImmediateOops {
38 private:
39 nmethod* const _nm;
40 const size_t _nimmediate_oops;
41
42 static size_t header_size();
43
44 ZNMethodWithImmediateOops(nmethod* nm, const GrowableArray<oop*>& immediate_oops);
45
46 public:
47 static ZNMethodWithImmediateOops* create(nmethod* nm, const GrowableArray<oop*>& immediate_oops);
48 static void destroy(ZNMethodWithImmediateOops* nmi);
49
50 nmethod* method() const;
51 size_t immediate_oops_count() const;
52 oop** immediate_oops_begin() const;
53 oop** immediate_oops_begin_safe() const;
54 oop** immediate_oops_end() const;
55 };
56
57 size_t ZNMethodWithImmediateOops::header_size() {
58 const size_t size = sizeof(ZNMethodWithImmediateOops);
59 assert(is_aligned(size, sizeof(oop*)), "Header misaligned");
60 return size;
61 }
62
63 ZNMethodWithImmediateOops::ZNMethodWithImmediateOops(nmethod* nm, const GrowableArray<oop*>& immediate_oops) :
64 _nm(nm),
65 _nimmediate_oops(immediate_oops.length()) {
66 // Save all immediate oops
67 for (size_t i = 0; i < _nimmediate_oops; i++) {
68 immediate_oops_begin()[i] = immediate_oops.at(i);
69 }
70 }
71
72 ZNMethodWithImmediateOops* ZNMethodWithImmediateOops::create(nmethod* nm, const GrowableArray<oop*>& immediate_oops) {
73 // Allocate memory for the ZNMethodWithImmediateOops object
74 // plus the immediate oop* array that follows right after.
75 const size_t size = header_size() + (sizeof(oop*) * immediate_oops.length());
76 void* const method_with_immediate_oops = NEW_C_HEAP_ARRAY(uint8_t, size, mtGC);
77 return ::new (method_with_immediate_oops) ZNMethodWithImmediateOops(nm, immediate_oops);
78 }
79
80 void ZNMethodWithImmediateOops::destroy(ZNMethodWithImmediateOops* nmi) {
81 FREE_C_HEAP_ARRAY(uint8_t, nmi);
82 }
83
84 nmethod* ZNMethodWithImmediateOops::method() const {
85 return _nm;
86 }
87
88 size_t ZNMethodWithImmediateOops::immediate_oops_count() const {
89 return _nimmediate_oops;
90 }
91
92 oop** ZNMethodWithImmediateOops::immediate_oops_begin() const {
93 // The immediate oop* array starts immediately after this object
94 return (oop**)((uintptr_t)this + header_size());
95 }
96
97 oop** ZNMethodWithImmediateOops::immediate_oops_begin_safe() const {
98 // Non-entrant nmethods have a jump instruction patched into the beginning
99 // of the verified entry point, which could have overwritten an immediate
100 // oop. If so, make sure we skip over that oop.
101 if (_nm->is_not_entrant()) {
102 oop* const first_immediate_oop = *immediate_oops_begin();
103 oop* const safe_begin = (oop*)(_nm->verified_entry_point() + NativeJump::instruction_size);
104 if (first_immediate_oop < safe_begin) {
105 // First immediate oop overwritten, skip it
106 return immediate_oops_begin() + 1;
107 }
108 }
109
110 // First immediate oop not overwritten
111 return immediate_oops_begin();
112 }
113
114
115 oop** ZNMethodWithImmediateOops::immediate_oops_end() const {
116 return immediate_oops_begin() + immediate_oops_count();
117 }
118
119 ZNMethodTableEntry* ZNMethodTable::_table = NULL;
120 size_t ZNMethodTable::_size = 0;
121 size_t ZNMethodTable::_nregistered = 0;
122 size_t ZNMethodTable::_nunregistered = 0;
123 volatile size_t ZNMethodTable::_claimed = 0;
124
125 ZNMethodTableEntry ZNMethodTable::create_entry(nmethod* nm) {
126 GrowableArray<oop*> immediate_oops;
127 bool non_immediate_oops = false;
128
129 // Find all oops relocations
130 RelocIterator iter(nm);
131 while (iter.next()) {
132 if (iter.type() != relocInfo::oop_type) {
133 // Not an oop
134 continue;
135 }
136
137 oop_Relocation* r = iter.oop_reloc();
138
139 if (!r->oop_is_immediate()) {
140 // Non-immediate oop found
141 non_immediate_oops = true;
142 continue;
143 }
144
145 if (r->oop_value() != NULL) {
146 // Non-NULL immediate oop found. NULL oops can safely be
147 // ignored since the method will be re-registered if they
148 // are later patched to be non-NULL.
149 immediate_oops.push(r->oop_addr());
150 }
151 }
152
153 // oops_count() returns the number of oops in the oop table plus one
154 if (immediate_oops.is_empty() && nm->oops_count() == 1) {
155 // No oops found, return empty entry
156 return ZNMethodTableEntry();
157 }
158
159 if (immediate_oops.is_empty()) {
160 // No immediate oops found, return entry without immediate oops
161 return ZNMethodTableEntry(nm, non_immediate_oops);
162 }
163
164 // Return entry with immediate oops
165 return ZNMethodTableEntry(ZNMethodWithImmediateOops::create(nm, immediate_oops), non_immediate_oops);
166 }
167
168 void ZNMethodTable::destroy_entry(ZNMethodTableEntry entry) {
169 if (entry.immediate_oops()) {
170 ZNMethodWithImmediateOops::destroy(entry.method_with_immediate_oops());
171 }
172 }
173
174 nmethod* ZNMethodTable::method(ZNMethodTableEntry entry) {
175 return entry.immediate_oops() ? entry.method_with_immediate_oops()->method() : entry.method();
176 }
177
178 size_t ZNMethodTable::first_index(const nmethod* nm, size_t size) {
179 assert(is_power_of_2(size), "Invalid size");
180 const size_t mask = size - 1;
181 const size_t hash = ZHash::address_to_uint32((uintptr_t)nm);
182 return hash & mask;
183 }
184
185 size_t ZNMethodTable::next_index(size_t prev_index, size_t size) {
186 assert(is_power_of_2(size), "Invalid size");
187 const size_t mask = size - 1;
188 return (prev_index + 1) & mask;
189 }
190
191 bool ZNMethodTable::register_entry(ZNMethodTableEntry* table, size_t size, ZNMethodTableEntry entry) {
192 const nmethod* const nm = method(entry);
193 size_t index = first_index(nm, size);
194
195 for (;;) {
196 const ZNMethodTableEntry table_entry = table[index];
197
198 if (!table_entry.registered() && !table_entry.unregistered()) {
199 // Insert new entry
200 table[index] = entry;
201 return true;
202 }
203
204 if (table_entry.registered() && method(table_entry) == nm) {
205 // Replace existing entry
206 destroy_entry(table_entry);
207 table[index] = entry;
208 return false;
209 }
210
211 index = next_index(index, size);
212 }
213 }
214
215 bool ZNMethodTable::unregister_entry(ZNMethodTableEntry* table, size_t size, const nmethod* nm) {
216 if (size == 0) {
217 // Table is empty
218 return false;
219 }
220
221 size_t index = first_index(nm, size);
222
223 for (;;) {
224 const ZNMethodTableEntry table_entry = table[index];
225
226 if (!table_entry.registered() && !table_entry.unregistered()) {
227 // Entry not found
228 return false;
229 }
230
231 if (table_entry.registered() && method(table_entry) == nm) {
232 // Remove entry
233 destroy_entry(table_entry);
234 table[index] = ZNMethodTableEntry(true /* unregistered */);
235 return true;
236 }
237
238 index = next_index(index, size);
239 }
240 }
241
242 void ZNMethodTable::rebuild(size_t new_size) {
243 assert(is_power_of_2(new_size), "Invalid size");
244
245 log_debug(gc, nmethod)("Rebuilding NMethod Table: "
246 SIZE_FORMAT "->" SIZE_FORMAT " entries, "
247 SIZE_FORMAT "(%.0lf%%->%.0lf%%) registered, "
248 SIZE_FORMAT "(%.0lf%%->%.0lf%%) unregistered",
249 _size, new_size,
250 _nregistered, percent_of(_nregistered, _size), percent_of(_nregistered, new_size),
251 _nunregistered, percent_of(_nunregistered, _size), 0.0);
252
253 // Allocate new table
254 ZNMethodTableEntry* const new_table = new ZNMethodTableEntry[new_size];
255
256 // Transfer all registered entries
257 for (size_t i = 0; i < _size; i++) {
258 const ZNMethodTableEntry entry = _table[i];
259 if (entry.registered()) {
260 register_entry(new_table, new_size, entry);
261 }
262 }
263
264 // Delete old table
265 delete [] _table;
266
267 // Install new table
268 _table = new_table;
269 _size = new_size;
270 _nunregistered = 0;
271 }
272
273 void ZNMethodTable::rebuild_if_needed() {
274 // The hash table uses linear probing. To avoid wasting memory while
275 // at the same time maintaining good hash collision behavior we want
276 // to keep the table occupancy between 30% and 70%. The table always
277 // grows/shrinks by doubling/halving its size. Pruning of unregistered
278 // entries is done by rebuilding the table with or without resizing it.
279 const size_t min_size = 1024;
280 const size_t shrink_threshold = _size * 0.30;
281 const size_t prune_threshold = _size * 0.65;
282 const size_t grow_threshold = _size * 0.70;
283
284 if (_size == 0) {
285 // Initialize table
286 rebuild(min_size);
287 } else if (_nregistered < shrink_threshold && _size > min_size) {
288 // Shrink table
289 rebuild(_size / 2);
290 } else if (_nregistered + _nunregistered > grow_threshold) {
291 // Prune or grow table
292 if (_nregistered < prune_threshold) {
293 // Prune table
294 rebuild(_size);
295 } else {
296 // Grow table
297 rebuild(_size * 2);
298 }
299 }
300 }
301
302 void ZNMethodTable::log_register(const nmethod* nm, ZNMethodTableEntry entry) {
303 LogTarget(Trace, gc, nmethod) log;
304 if (!log.is_enabled()) {
305 return;
306 }
307
308 log.print("Register NMethod: %s.%s (" PTR_FORMAT "), "
309 "Compiler: %s, Oops: %d, ImmediateOops: " SIZE_FORMAT ", NonImmediateOops: %s",
310 nm->method()->method_holder()->external_name(),
311 nm->method()->name()->as_C_string(),
312 p2i(nm),
313 nm->compiler_name(),
314 nm->oops_count() - 1,
315 entry.immediate_oops() ? entry.method_with_immediate_oops()->immediate_oops_count() : 0,
316 BOOL_TO_STR(entry.non_immediate_oops()));
317
318 LogTarget(Trace, gc, nmethod, oops) log_oops;
319 if (!log_oops.is_enabled()) {
320 return;
321 }
322
323 // Print nmethod oops table
324 oop* const begin = nm->oops_begin();
325 oop* const end = nm->oops_end();
326 for (oop* p = begin; p < end; p++) {
327 log_oops.print(" Oop[" SIZE_FORMAT "] " PTR_FORMAT " (%s)",
328 (p - begin), p2i(*p), (*p)->klass()->external_name());
329 }
330
331 if (entry.immediate_oops()) {
332 // Print nmethod immediate oops
333 const ZNMethodWithImmediateOops* const nmi = entry.method_with_immediate_oops();
334 oop** const begin = nmi->immediate_oops_begin();
335 oop** const end = nmi->immediate_oops_end();
336 for (oop** p = begin; p < end; p++) {
337 log_oops.print(" ImmediateOop[" SIZE_FORMAT "] " PTR_FORMAT " @ " PTR_FORMAT " (%s)",
338 (p - begin), p2i(**p), p2i(*p), (**p)->klass()->external_name());
339 }
340 }
341 }
342
343 void ZNMethodTable::log_unregister(const nmethod* nm) {
344 LogTarget(Debug, gc, nmethod) log;
345 if (!log.is_enabled()) {
346 return;
347 }
348
349 log.print("Unregister NMethod: %s.%s (" PTR_FORMAT ")",
350 nm->method()->method_holder()->external_name(),
351 nm->method()->name()->as_C_string(),
352 p2i(nm));
353 }
354
355 size_t ZNMethodTable::registered_nmethods() {
356 return _nregistered;
357 }
358
359 size_t ZNMethodTable::unregistered_nmethods() {
360 return _nunregistered;
361 }
362
363 void ZNMethodTable::register_nmethod(nmethod* nm) {
364 ResourceMark rm;
365
366 // Create entry
367 const ZNMethodTableEntry entry = create_entry(nm);
368
369 log_register(nm, entry);
370
371 if (!entry.registered()) {
372 // Method doesn't have any oops, ignore it
373 return;
374 }
375
376 // Grow/Shrink/Prune table if needed
377 rebuild_if_needed();
378
379 // Insert new entry
380 if (register_entry(_table, _size, entry)) {
381 // New entry registered. When register_entry() instead returns
382 // false the nmethod was already in the table so we do not want
383 // to increase number of registered entries in that case.
384 _nregistered++;
385 }
386 }
387
388 void ZNMethodTable::unregister_nmethod(nmethod* nm) {
389 ResourceMark rm;
390
391 log_unregister(nm);
392
393 // Remove entry
394 if (unregister_entry(_table, _size, nm)) {
395 // Entry was unregistered. When unregister_entry() instead returns
396 // false the nmethod was not in the table (because it didn't have
397 // any oops) so we do not want to decrease the number of registered
398 // entries in that case.
399 _nregistered--;
400 _nunregistered++;
401 }
402 }
403
404 void ZNMethodTable::gc_prologue() {
405 _claimed = 0;
406 }
407
408 void ZNMethodTable::gc_epilogue() {
409 assert(_claimed >= _size, "Failed to claim all table entries");
410 }
411
412 void ZNMethodTable::entry_oops_do(ZNMethodTableEntry entry, OopClosure* cl) {
413 nmethod* const nm = method(entry);
414 if (!nm->is_alive()) {
415 // No need to visit oops
416 return;
417 }
418
419 // Process oops table
420 oop* const begin = nm->oops_begin();
421 oop* const end = nm->oops_end();
422 for (oop* p = begin; p < end; p++) {
423 if (*p != Universe::non_oop_word()) {
424 cl->do_oop(p);
425 }
426 }
427
428 if (entry.immediate_oops()) {
429 // Process immediate oops
430 const ZNMethodWithImmediateOops* const nmi = entry.method_with_immediate_oops();
431 oop** const begin = nmi->immediate_oops_begin_safe();
432 oop** const end = nmi->immediate_oops_end();
433 for (oop** p = begin; p < end; p++) {
434 cl->do_oop(*p);
435 }
436 }
437
438 if (entry.non_immediate_oops()) {
439 // Process non-immediate oops
440 nm->fix_oop_relocations();
441 }
442 }
443
444 void ZNMethodTable::oops_do(OopClosure* cl) {
445 for (;;) {
446 // Claim table partition
447 const size_t partition_size = DEFAULT_CACHE_LINE_SIZE / sizeof(ZNMethodTableEntry);
448 const size_t partition_start = MIN2(Atomic::add(partition_size, &_claimed) - partition_size, _size);
449 const size_t partition_end = MIN2(partition_start + partition_size, _size);
450 if (partition_start == partition_end) {
451 // End of table
452 break;
453 }
454
455 // Process table partition
456 for (size_t i = partition_start; i < partition_end; i++) {
457 const ZNMethodTableEntry entry = _table[i];
458 if (entry.registered()) {
459 entry_oops_do(entry, cl);
460 }
461 }
462 }
463 }