1 /*
2 * Copyright (c) 2017, 2018, 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/zGlobals.hpp"
29 #include "gc/z/zHash.inline.hpp"
30 #include "gc/z/zNMethodTable.hpp"
31 #include "logging/log.hpp"
32 #include "memory/allocation.inline.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/atomic.hpp"
36 #include "utilities/debug.hpp"
37
38 class ZNMethodWithImmediateOops {
39 private:
40 nmethod* const _nm;
41 const size_t _nimmediate_oops;
42
43 static size_t header_size();
44
45 ZNMethodWithImmediateOops(nmethod* nm, const GrowableArray<oop*>& immediate_oops);
46
47 public:
48 static ZNMethodWithImmediateOops* create(nmethod* nm, const GrowableArray<oop*>& immediate_oops);
49 static void destroy(ZNMethodWithImmediateOops* nmi);
50
51 nmethod* method() const;
52 size_t immediate_oops_count() const;
53 oop** immediate_oops_begin() const;
54 oop** immediate_oops_begin_safe() const;
55 oop** immediate_oops_end() const;
56 };
57
58 size_t ZNMethodWithImmediateOops::header_size() {
59 const size_t size = sizeof(ZNMethodWithImmediateOops);
60 assert(is_aligned(size, sizeof(oop*)), "Header misaligned");
61 return size;
62 }
63
64 ZNMethodWithImmediateOops::ZNMethodWithImmediateOops(nmethod* nm, const GrowableArray<oop*>& immediate_oops) :
65 _nm(nm),
66 _nimmediate_oops(immediate_oops.length()) {
67 // Save all immediate oops
68 for (size_t i = 0; i < _nimmediate_oops; i++) {
69 immediate_oops_begin()[i] = immediate_oops.at(i);
70 }
71 }
72
73 ZNMethodWithImmediateOops* ZNMethodWithImmediateOops::create(nmethod* nm, const GrowableArray<oop*>& immediate_oops) {
74 // Allocate memory for the ZNMethodWithImmediateOops object
75 // plus the immediate oop* array that follows right after.
76 const size_t size = header_size() + (sizeof(oop*) * immediate_oops.length());
77 void* const method_with_immediate_oops = NEW_C_HEAP_ARRAY(uint8_t, size, mtGC);
78 return ::new (method_with_immediate_oops) ZNMethodWithImmediateOops(nm, immediate_oops);
79 }
80
81 void ZNMethodWithImmediateOops::destroy(ZNMethodWithImmediateOops* nmi) {
82 FREE_C_HEAP_ARRAY(uint8_t, nmi);
83 }
84
85 nmethod* ZNMethodWithImmediateOops::method() const {
86 return _nm;
87 }
88
89 size_t ZNMethodWithImmediateOops::immediate_oops_count() const {
90 return _nimmediate_oops;
91 }
92
93 oop** ZNMethodWithImmediateOops::immediate_oops_begin() const {
94 // The immediate oop* array starts immediately after this object
95 return (oop**)((uintptr_t)this + header_size());
96 }
97
98 oop** ZNMethodWithImmediateOops::immediate_oops_begin_safe() const {
99 // Non-entrant nmethods have a jump instruction patched into the beginning
100 // of the verified entry point, which could have overwritten an immediate
101 // oop. If so, make sure we skip over that oop.
102 if (_nm->is_not_entrant()) {
103 oop* const first_immediate_oop = *immediate_oops_begin();
104 oop* const safe_begin = (oop*)(_nm->verified_entry_point() + NativeJump::instruction_size);
105 if (first_immediate_oop < safe_begin) {
106 // First immediate oop overwritten, skip it
107 return immediate_oops_begin() + 1;
108 }
109 }
110
111 // First immediate oop not overwritten
112 return immediate_oops_begin();
113 }
114
115
116 oop** ZNMethodWithImmediateOops::immediate_oops_end() const {
117 return immediate_oops_begin() + immediate_oops_count();
118 }
119
120 ZNMethodTableEntry* ZNMethodTable::_table = NULL;
121 size_t ZNMethodTable::_size = 0;
122 size_t ZNMethodTable::_nregistered = 0;
123 size_t ZNMethodTable::_nunregistered = 0;
124 volatile size_t ZNMethodTable::_claimed = 0;
125
126 ZNMethodTableEntry ZNMethodTable::create_entry(nmethod* nm) {
127 GrowableArray<oop*> immediate_oops;
128 bool non_immediate_oops = false;
129
130 // Find all oops relocations
131 RelocIterator iter(nm);
132 while (iter.next()) {
133 if (iter.type() != relocInfo::oop_type) {
134 // Not an oop
135 continue;
136 }
137
138 oop_Relocation* r = iter.oop_reloc();
139
140 if (!r->oop_is_immediate()) {
141 // Non-immediate oop found
142 non_immediate_oops = true;
143 continue;
144 }
145
146 if (r->oop_value() != NULL) {
147 // Non-NULL immediate oop found. NULL oops can safely be
148 // ignored since the method will be re-registered if they
149 // are later patched to be non-NULL.
150 immediate_oops.push(r->oop_addr());
151 }
152 }
153
154 // oops_count() returns the number of oops in the oop table plus one
155 if (immediate_oops.is_empty() && nm->oops_count() == 1) {
156 // No oops found, return empty entry
157 return ZNMethodTableEntry();
158 }
159
160 if (immediate_oops.is_empty()) {
161 // No immediate oops found, return entry without immediate oops
162 return ZNMethodTableEntry(nm, non_immediate_oops);
163 }
164
165 // Return entry with immediate oops
166 return ZNMethodTableEntry(ZNMethodWithImmediateOops::create(nm, immediate_oops), non_immediate_oops);
167 }
168
169 void ZNMethodTable::destroy_entry(ZNMethodTableEntry entry) {
170 if (entry.immediate_oops()) {
171 ZNMethodWithImmediateOops::destroy(entry.method_with_immediate_oops());
172 }
173 }
174
175 nmethod* ZNMethodTable::method(ZNMethodTableEntry entry) {
176 return entry.immediate_oops() ? entry.method_with_immediate_oops()->method() : entry.method();
177 }
178
179 size_t ZNMethodTable::first_index(const nmethod* nm, size_t size) {
180 assert(is_power_of_2(size), "Invalid size");
181 const size_t mask = size - 1;
182 const size_t hash = ZHash::address_to_uint32((uintptr_t)nm);
183 return hash & mask;
184 }
185
186 size_t ZNMethodTable::next_index(size_t prev_index, size_t size) {
187 assert(is_power_of_2(size), "Invalid size");
188 const size_t mask = size - 1;
189 return (prev_index + 1) & mask;
190 }
191
192 bool ZNMethodTable::register_entry(ZNMethodTableEntry* table, size_t size, ZNMethodTableEntry entry) {
193 const nmethod* const nm = method(entry);
194 size_t index = first_index(nm, size);
195
196 for (;;) {
197 const ZNMethodTableEntry table_entry = table[index];
198
199 if (!table_entry.registered() && !table_entry.unregistered()) {
200 // Insert new entry
201 table[index] = entry;
202 return true;
203 }
204
205 if (table_entry.registered() && method(table_entry) == nm) {
206 // Replace existing entry
207 destroy_entry(table_entry);
208 table[index] = entry;
209 return false;
210 }
211
212 index = next_index(index, size);
213 }
214 }
215
216 bool ZNMethodTable::unregister_entry(ZNMethodTableEntry* table, size_t size, const nmethod* nm) {
217 if (size == 0) {
218 // Table is empty
219 return false;
220 }
221
222 size_t index = first_index(nm, size);
223
224 for (;;) {
225 const ZNMethodTableEntry table_entry = table[index];
226
227 if (!table_entry.registered() && !table_entry.unregistered()) {
228 // Entry not found
229 return false;
230 }
231
232 if (table_entry.registered() && method(table_entry) == nm) {
233 // Remove entry
234 destroy_entry(table_entry);
235 table[index] = ZNMethodTableEntry(true /* unregistered */);
236 return true;
237 }
238
239 index = next_index(index, size);
240 }
241 }
242
243 void ZNMethodTable::rebuild(size_t new_size) {
244 assert(is_power_of_2(new_size), "Invalid size");
245
246 log_debug(gc, nmethod)("Rebuilding NMethod Table: "
247 SIZE_FORMAT "->" SIZE_FORMAT " entries, "
248 SIZE_FORMAT "(%.0lf%%->%.0lf%%) registered, "
249 SIZE_FORMAT "(%.0lf%%->%.0lf%%) unregistered",
250 _size, new_size,
251 _nregistered, percent_of(_nregistered, _size), percent_of(_nregistered, new_size),
252 _nunregistered, percent_of(_nunregistered, _size), 0.0);
253
254 // Allocate new table
255 ZNMethodTableEntry* const new_table = new ZNMethodTableEntry[new_size];
256
257 // Transfer all registered entries
258 for (size_t i = 0; i < _size; i++) {
259 const ZNMethodTableEntry entry = _table[i];
260 if (entry.registered()) {
261 register_entry(new_table, new_size, entry);
262 }
263 }
264
265 // Delete old table
266 delete [] _table;
267
268 // Install new table
269 _table = new_table;
270 _size = new_size;
271 _nunregistered = 0;
272 }
273
274 void ZNMethodTable::rebuild_if_needed() {
275 // The hash table uses linear probing. To avoid wasting memory while
276 // at the same time maintaining good hash collision behavior we want
277 // to keep the table occupancy between 30% and 70%. The table always
278 // grows/shrinks by doubling/halving its size. Pruning of unregistered
279 // entries is done by rebuilding the table with or without resizing it.
280 const size_t min_size = 1024;
281 const size_t shrink_threshold = _size * 0.30;
282 const size_t prune_threshold = _size * 0.65;
283 const size_t grow_threshold = _size * 0.70;
284
285 if (_size == 0) {
286 // Initialize table
287 rebuild(min_size);
288 } else if (_nregistered < shrink_threshold && _size > min_size) {
289 // Shrink table
290 rebuild(_size / 2);
291 } else if (_nregistered + _nunregistered > grow_threshold) {
292 // Prune or grow table
293 if (_nregistered < prune_threshold) {
294 // Prune table
295 rebuild(_size);
296 } else {
297 // Grow table
298 rebuild(_size * 2);
299 }
300 }
301 }
302
303 void ZNMethodTable::log_register(const nmethod* nm, ZNMethodTableEntry entry) {
304 LogTarget(Trace, gc, nmethod) log;
305 if (!log.is_enabled()) {
306 return;
307 }
308
309 log.print("Register NMethod: %s.%s (" PTR_FORMAT "), "
310 "Compiler: %s, Oops: %d, ImmediateOops: " SIZE_FORMAT ", NonImmediateOops: %s",
311 nm->method()->method_holder()->external_name(),
312 nm->method()->name()->as_C_string(),
313 p2i(nm),
314 nm->compiler_name(),
315 nm->oops_count() - 1,
316 entry.immediate_oops() ? entry.method_with_immediate_oops()->immediate_oops_count() : 0,
317 BOOL_TO_STR(entry.non_immediate_oops()));
318
319 LogTarget(Trace, gc, nmethod, oops) log_oops;
320 if (!log_oops.is_enabled()) {
321 return;
322 }
323
324 // Print nmethod oops table
325 oop* const begin = nm->oops_begin();
326 oop* const end = nm->oops_end();
327 for (oop* p = begin; p < end; p++) {
328 log_oops.print(" Oop[" SIZE_FORMAT "] " PTR_FORMAT " (%s)",
329 (p - begin), p2i(*p), (*p)->klass()->external_name());
330 }
331
332 if (entry.immediate_oops()) {
333 // Print nmethod immediate oops
334 const ZNMethodWithImmediateOops* const nmi = entry.method_with_immediate_oops();
335 oop** const begin = nmi->immediate_oops_begin();
336 oop** const end = nmi->immediate_oops_end();
337 for (oop** p = begin; p < end; p++) {
338 log_oops.print(" ImmediateOop[" SIZE_FORMAT "] " PTR_FORMAT " @ " PTR_FORMAT " (%s)",
339 (p - begin), p2i(**p), p2i(*p), (**p)->klass()->external_name());
340 }
341 }
342 }
343
344 void ZNMethodTable::log_unregister(const nmethod* nm) {
345 LogTarget(Debug, gc, nmethod) log;
346 if (!log.is_enabled()) {
347 return;
348 }
349
350 log.print("Unregister NMethod: %s.%s (" PTR_FORMAT ")",
351 nm->method()->method_holder()->external_name(),
352 nm->method()->name()->as_C_string(),
353 p2i(nm));
354 }
355
356 size_t ZNMethodTable::registered_nmethods() {
357 return _nregistered;
358 }
359
360 size_t ZNMethodTable::unregistered_nmethods() {
361 return _nunregistered;
362 }
363
364 void ZNMethodTable::register_nmethod(nmethod* nm) {
365 ResourceMark rm;
366
367 // Create entry
368 const ZNMethodTableEntry entry = create_entry(nm);
369
370 log_register(nm, entry);
371
372 if (!entry.registered()) {
373 // Method doesn't have any oops, ignore it
374 return;
375 }
376
377 // Grow/Shrink/Prune table if needed
378 rebuild_if_needed();
379
380 // Insert new entry
381 if (register_entry(_table, _size, entry)) {
382 // New entry registered. When register_entry() instead returns
383 // false the nmethod was already in the table so we do not want
384 // to increase number of registered entries in that case.
385 _nregistered++;
386 }
387 }
388
389 void ZNMethodTable::unregister_nmethod(nmethod* nm) {
390 ResourceMark rm;
391
392 log_unregister(nm);
393
394 // Remove entry
395 if (unregister_entry(_table, _size, nm)) {
396 // Entry was unregistered. When unregister_entry() instead returns
397 // false the nmethod was not in the table (because it didn't have
398 // any oops) so we do not want to decrease the number of registered
399 // entries in that case.
400 _nregistered--;
401 _nunregistered++;
402 }
403 }
404
405 void ZNMethodTable::gc_prologue() {
406 _claimed = 0;
407 }
408
409 void ZNMethodTable::gc_epilogue() {
410 assert(_claimed >= _size, "Failed to claim all table entries");
411 }
412
413 void ZNMethodTable::entry_oops_do(ZNMethodTableEntry entry, OopClosure* cl) {
414 nmethod* const nm = method(entry);
415 if (!nm->is_alive()) {
416 // No need to visit oops
417 return;
418 }
419
420 // Process oops table
421 oop* const begin = nm->oops_begin();
422 oop* const end = nm->oops_end();
423 for (oop* p = begin; p < end; p++) {
424 if (*p != Universe::non_oop_word()) {
425 cl->do_oop(p);
426 }
427 }
428
429 if (entry.immediate_oops()) {
430 // Process immediate oops
431 const ZNMethodWithImmediateOops* const nmi = entry.method_with_immediate_oops();
432 oop** const begin = nmi->immediate_oops_begin_safe();
433 oop** const end = nmi->immediate_oops_end();
434 for (oop** p = begin; p < end; p++) {
435 cl->do_oop(*p);
436 }
437 }
438
439 if (entry.non_immediate_oops()) {
440 // Process non-immediate oops
441 nm->fix_oop_relocations();
442 }
443 }
444
445 void ZNMethodTable::oops_do(OopClosure* cl) {
446 for (;;) {
447 // Claim table partition. Each partition is currently sized to span
448 // two cache lines. This number is just a guess, but seems to work well.
449 const size_t partition_size = (ZCacheLineSize * 2) / sizeof(ZNMethodTableEntry);
450 const size_t partition_start = MIN2(Atomic::add(partition_size, &_claimed) - partition_size, _size);
451 const size_t partition_end = MIN2(partition_start + partition_size, _size);
452 if (partition_start == partition_end) {
453 // End of table
454 break;
455 }
456
457 // Process table partition
458 for (size_t i = partition_start; i < partition_end; i++) {
459 const ZNMethodTableEntry entry = _table[i];
460 if (entry.registered()) {
461 entry_oops_do(entry, cl);
462 }
463 }
464 }
465 }