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src/hotspot/share/gc/shenandoah/shenandoahNMethod.cpp

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  1 /*
  2  * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
  3  * Copyright (c) 2019, 2022, Red Hat, Inc. All rights reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
 23  *
 24  */
 25 
 26 

 27 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
 28 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 29 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
 30 #include "memory/resourceArea.hpp"
 31 #include "runtime/continuation.hpp"

 32 #include "runtime/safepointVerifiers.hpp"
 33 
 34 ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>& oops, bool non_immediate_oops) :
 35   _nm(nm), _oops(nullptr), _oops_count(0), _unregistered(false), _lock(), _ic_lock() {
 36 
 37   if (!oops.is_empty()) {
 38     _oops_count = oops.length();
 39     _oops = NEW_C_HEAP_ARRAY(oop*, _oops_count, mtGC);
 40     for (int c = 0; c < _oops_count; c++) {
 41       _oops[c] = oops.at(c);
 42     }
 43   }
 44   _has_non_immed_oops = non_immediate_oops;
 45 
 46   assert_same_oops();
 47 }
 48 
 49 ShenandoahNMethod::~ShenandoahNMethod() {
 50   if (_oops != nullptr) {
 51     FREE_C_HEAP_ARRAY(_oops);
 52   }



 53 }
 54 
 55 void ShenandoahNMethod::update() {




 56   ResourceMark rm;
 57   bool non_immediate_oops = false;
 58   GrowableArray<oop*> oops;

 59 
 60   detect_reloc_oops(nm(), oops, non_immediate_oops);
 61   if (oops.length() != _oops_count) {


 62     if (_oops != nullptr) {
 63       FREE_C_HEAP_ARRAY(_oops);
 64       _oops = nullptr;
 65     }
 66 
 67     _oops_count = oops.length();
 68     if (_oops_count > 0) {
 69       _oops = NEW_C_HEAP_ARRAY(oop*, _oops_count, mtGC);
 70     }
 71   }





 72 
 73   for (int index = 0; index < _oops_count; index ++) {
 74     _oops[index] = oops.at(index);











 75   }
 76   _has_non_immed_oops = non_immediate_oops;
 77 
 78   assert_same_oops();
 79 }
 80 
 81 void ShenandoahNMethod::detect_reloc_oops(nmethod* nm, GrowableArray<oop*>& oops, bool& has_non_immed_oops) {
 82   has_non_immed_oops = false;
 83   // Find all oops relocations
 84   RelocIterator iter(nm);
 85   while (iter.next()) {
 86     if (iter.type() != relocInfo::oop_type) {
 87       // Not an oop
 88       continue;
 89     }
 90 
 91     oop_Relocation* r = iter.oop_reloc();
 92     if (!r->oop_is_immediate()) {
 93       // Non-immediate oop found
 94       has_non_immed_oops = true;
 95       continue;
 96     }
 97 
 98     oop value = r->oop_value();
 99     if (value != nullptr) {
100       oop* addr = r->oop_addr();
101       shenandoah_assert_correct(addr, value);
102       shenandoah_assert_not_in_cset_except(addr, value, ShenandoahHeap::heap()->cancelled_gc());
103       shenandoah_assert_not_forwarded(addr, value);
104       // Non-null immediate oop found. null oops can safely be
105       // ignored since the method will be re-registered if they
106       // are later patched to be non-null.
107       oops.push(addr);














108     }
109   }
110 }
111 
112 ShenandoahNMethod* ShenandoahNMethod::for_nmethod(nmethod* nm) {
113   ResourceMark rm;
114   bool non_immediate_oops = false;
115   GrowableArray<oop*> oops;
116 
117   detect_reloc_oops(nm, oops, non_immediate_oops);
118   return new ShenandoahNMethod(nm, oops, non_immediate_oops);
119 }
120 
121 void ShenandoahNMethod::heal_nmethod(nmethod* nm) {
122   ShenandoahNMethod* data = gc_data(nm);
123   assert(data != nullptr, "Sanity");
124   assert(data->lock()->owned_by_self(), "Must hold the lock");
125 
126   ShenandoahHeap* const heap = ShenandoahHeap::heap();
127   if ((heap->is_concurrent_weak_root_in_progress() && heap->is_evacuation_in_progress()) ||
128       heap->is_concurrent_strong_root_in_progress()) {
129     heal_nmethod_metadata(data);
130   } else if (heap->is_concurrent_mark_in_progress()) {
131     ShenandoahKeepAliveClosure cl;
132     data->oops_do(&cl);
133   } else {
134     // There is possibility that GC is cancelled when it arrives final mark.
135     // In this case, concurrent root phase is skipped and degenerated GC should be
136     // followed, where nmethods are disarmed.
137   }
138 }
139 

























































140 #ifdef ASSERT
141 void ShenandoahNMethod::assert_correct() {
142   ShenandoahHeap* heap = ShenandoahHeap::heap();
143   for (int c = 0; c < _oops_count; c++) {
144     oop *loc = _oops[c];
145     assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");
146     oop o = RawAccess<>::oop_load(loc);
147     shenandoah_assert_correct_except(loc, o, o == nullptr || heap->is_full_gc_move_in_progress());
148   }
149 
150   oop* const begin = _nm->oops_begin();
151   oop* const end = _nm->oops_end();
152   for (oop* p = begin; p < end; p++) {
153     if (*p != Universe::non_oop_word()) {
154       oop o = RawAccess<>::oop_load(p);
155       shenandoah_assert_correct_except(p, o, o == nullptr || heap->is_full_gc_move_in_progress());
156     }
157   }
158 }
159 

188     assert(oops->contains(_oops[index]), "Must contain this oop");
189   }
190 
191   for (oop* p = nm()->oops_begin(); p < nm()->oops_end(); p ++) {
192     if (*p == Universe::non_oop_word()) continue;
193     count++;
194     assert(oops->contains(p), "Must contain this oop");
195   }
196 
197   if (oops->length() < count) {
198     stringStream debug_stream;
199     debug_stream.print_cr("detected locs: %d", oops->length());
200     for (int i = 0; i < oops->length(); i++) {
201       debug_stream.print_cr("-> " PTR_FORMAT, p2i(oops->at(i)));
202     }
203     debug_stream.print_cr("recorded oops: %d", _oops_count);
204     for (int i = 0; i < _oops_count; i++) {
205       debug_stream.print_cr("-> " PTR_FORMAT, p2i(_oops[i]));
206     }
207     GrowableArray<oop*> check;

208     bool non_immed;
209     detect_reloc_oops(nm(), check, non_immed);
210     debug_stream.print_cr("check oops: %d", check.length());
211     for (int i = 0; i < check.length(); i++) {
212       debug_stream.print_cr("-> " PTR_FORMAT, p2i(check.at(i)));
213     }
214     fatal("Must match #detected: %d, #recorded: %d, #total: %d, begin: " PTR_FORMAT ", end: " PTR_FORMAT "\n%s",
215           oops->length(), _oops_count, count, p2i(nm()->oops_begin()), p2i(nm()->oops_end()), debug_stream.freeze());
216   }
217 }
218 #endif
219 
220 ShenandoahNMethodTable::ShenandoahNMethodTable() :
221   _heap(ShenandoahHeap::heap()),

222   _index(0),
223   _itr_cnt(0) {
224   _list = new ShenandoahNMethodList(minSize);
225 }
226 
227 ShenandoahNMethodTable::~ShenandoahNMethodTable() {
228   assert(_list != nullptr, "Sanity");
229   _list->release();
230 }
231 
232 void ShenandoahNMethodTable::register_nmethod(nmethod* nm) {
233   assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");
234   assert(_index >= 0 && _index <= _list->size(), "Sanity");
235 
236   ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
237 
238   if (data != nullptr) {


239     assert(contain(nm), "Must have been registered");
240     assert(nm == data->nm(), "Must be same nmethod");


241     // Prevent updating a nmethod while concurrent iteration is in progress.
242     wait_until_concurrent_iteration_done();
243     ShenandoahNMethodLocker data_locker(data->lock());
244     data->update();
245   } else {
246     // For a new nmethod, we can safely append it to the list, because
247     // concurrent iteration will not touch it.


248     data = ShenandoahNMethod::for_nmethod(nm);
249     assert(data != nullptr, "Sanity");
250     ShenandoahNMethod::attach_gc_data(nm, data);
251     ShenandoahLocker locker(&_lock);
252     log_register_nmethod(nm);
253     append(data);






254   }
255   // Disarm new nmethod
256   ShenandoahNMethod::disarm_nmethod(nm);

257 }
258 
259 void ShenandoahNMethodTable::unregister_nmethod(nmethod* nm) {
260   assert_locked_or_safepoint(CodeCache_lock);
261 
262   ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
263   assert(data != nullptr, "Sanity");
264   log_unregister_nmethod(nm);
265   ShenandoahLocker locker(&_lock);
266   assert(contain(nm), "Must have been registered");
267 
268   int idx = index_of(nm);
269   assert(idx >= 0 && idx < _index, "Invalid index");
270   ShenandoahNMethod::attach_gc_data(nm, nullptr);
271   remove(idx);
272 }
273 
274 bool ShenandoahNMethodTable::contain(nmethod* nm) const {
275   return index_of(nm) != -1;
276 }

  1 /*
  2  * Copyright (c) 2024, 2026, Oracle and/or its affiliates. All rights reserved.
  3  * Copyright (c) 2019, 2022, Red Hat, Inc. All rights reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
 23  *
 24  */
 25 
 26 
 27 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
 28 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
 29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 30 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
 31 #include "memory/resourceArea.hpp"
 32 #include "runtime/continuation.hpp"
 33 #include "runtime/icache.hpp"
 34 #include "runtime/safepointVerifiers.hpp"
 35 
 36 ShenandoahNMethod::ShenandoahNMethod(nmethod* nm) :
 37   _nm(nm), _oops(nullptr), _oops_count(0), _patchable_jumps(nullptr), _patchable_jumps_count(0), _unregistered(false), _lock(), _ic_lock() {
 38   init_from(nm);










 39 }
 40 
 41 ShenandoahNMethod::~ShenandoahNMethod() {
 42   if (_oops != nullptr) {
 43     FREE_C_HEAP_ARRAY(_oops);
 44   }
 45   if (_patchable_jumps != nullptr) {
 46     FREE_C_HEAP_ARRAY(_patchable_jumps);
 47   }
 48 }
 49 
 50 void ShenandoahNMethod::update() {
 51   init_from(nm());
 52 }
 53 
 54 void ShenandoahNMethod::init_from(nmethod* nm) {
 55   ResourceMark rm;
 56   bool non_immediate_oops = false;
 57   GrowableArray<oop*> oops;
 58   GrowableArray<ShenandoahPatchableJump> jumps;
 59 
 60   parse(nm, oops, non_immediate_oops, jumps);
 61 
 62   int new_oops_count = oops.length();
 63   if (_oops_count != new_oops_count) {
 64     if (_oops != nullptr) {
 65       FREE_C_HEAP_ARRAY(_oops);
 66       _oops = nullptr;
 67     }
 68     if (new_oops_count > 0) {
 69       _oops = NEW_C_HEAP_ARRAY(oop*, new_oops_count, mtGC);


 70     }
 71   }
 72   _oops_count = new_oops_count;
 73   for (int c = 0; c < _oops_count; c++) {
 74     _oops[c] = oops.at(c);
 75   }
 76   assert_same_oops();
 77 
 78   int new_jumps_count = jumps.length();
 79   if (_patchable_jumps_count != new_jumps_count) {
 80     if (_patchable_jumps != nullptr) {
 81       FREE_C_HEAP_ARRAY(_patchable_jumps);
 82       _patchable_jumps = nullptr;
 83     }
 84     if (new_jumps_count > 0) {
 85       _patchable_jumps = NEW_C_HEAP_ARRAY(ShenandoahPatchableJump, new_jumps_count, mtGC);
 86     }
 87   }
 88   _patchable_jumps_count = new_jumps_count;
 89   for (int c = 0; c < _patchable_jumps_count; c++) {
 90     _patchable_jumps[c] = jumps.at(c);
 91   }

 92 
 93   _has_non_immed_oops = non_immediate_oops;
 94 }
 95 
 96 void ShenandoahNMethod::parse(nmethod* nm, GrowableArray<oop*>& oops, bool& has_non_immed_oops, GrowableArray<ShenandoahPatchableJump>& jumps) {
 97   has_non_immed_oops = false;
 98   address code_begin = nm->code_begin();
 99   RelocIterator iter(nm);
100   while (iter.next()) {
101     switch (iter.type()) {
102       case relocInfo::oop_type: {
103         oop_Relocation* r = iter.oop_reloc();
104         if (!r->oop_is_immediate()) {
105           // Non-immediate oop found
106           has_non_immed_oops = true;
107           break;
108         }
109 
110         oop value = r->oop_value();
111         if (value != nullptr) {
112           oop* addr = r->oop_addr();
113           shenandoah_assert_correct(addr, value);
114           shenandoah_assert_not_in_cset_except(addr, value, ShenandoahHeap::heap()->cancelled_gc());
115           shenandoah_assert_not_forwarded(addr, value);
116           // Non-null immediate oop found. null oops can safely be
117           // ignored since the method will be re-registered if they
118           // are later patched to be non-null.
119           oops.push(addr);
120         }
121         break;
122       }
123       case relocInfo::patchable_barrier_type: {
124         patchable_barrier_Relocation* r = iter.patchable_barrier_reloc();
125 
126         ShenandoahPatchableJump b;
127         b._rel_pc = checked_cast<int32_t>(pointer_delta(r->addr(), code_begin, 1));
128         b._rel_target_pc = r->target_offset();
129         b._gc_state = decode_reloc_gc_state(r->metadata());
130         b._jump_when_state = decode_reloc_jump_when_state(r->metadata());
131         jumps.push(b);
132         break;
133       }
134       default:
135         // We do not care about other relocations.
136         break;
137     }
138   }
139 }
140 
141 ShenandoahNMethod* ShenandoahNMethod::for_nmethod(nmethod* nm) {
142   return new ShenandoahNMethod(nm);





143 }
144 
145 void ShenandoahNMethod::handle_oops(nmethod* nm, ICacheInvalidationContext* icic) {
146   ShenandoahNMethod* data = gc_data(nm);
147   assert(data != nullptr, "Sanity");
148   assert(data->lock()->owned_by_self(), "Must hold the lock");
149 
150   ShenandoahHeap* const heap = ShenandoahHeap::heap();
151   if ((heap->is_concurrent_weak_root_in_progress() && heap->is_evacuation_in_progress()) ||
152       heap->is_concurrent_strong_root_in_progress()) {
153     heal_nmethod_metadata(data, icic);
154   } else if (heap->is_concurrent_mark_in_progress()) {
155     ShenandoahKeepAliveClosure cl;
156     data->oops_do(&cl, /* fix_relocations = */ false, /* icic = */ nullptr);
157   } else {
158     // There is possibility that GC is cancelled when it arrives final mark.
159     // In this case, concurrent root phase is skipped and degenerated GC should be
160     // followed, where nmethods are disarmed.
161   }
162 }
163 
164 void ShenandoahNMethod::handle_jumps(nmethod* nm, ICacheInvalidationContext* icic) {
165   ShenandoahNMethod* data = gc_data(nm);
166   assert(data != nullptr, "Sanity");
167   assert(data->lock()->owned_by_self(), "Must hold the lock");
168 
169   char gc_state = ShenandoahHeap::heap()->gc_state();
170   address code_begin = nm->code_begin();
171 
172   bool changed = false;
173   for (int c = 0; c < data->_patchable_jumps_count; c++) {
174     ShenandoahPatchableJump& b = data->_patchable_jumps[c];
175     changed |= patch_jump(code_begin + b._rel_pc,
176                           code_begin + b._rel_target_pc,
177                           ((gc_state & b._gc_state) != 0) == b._jump_when_state);
178   }
179   if (changed) {
180     icic->set_has_modified_code();
181   }
182 }
183 
184 // Use precise instruction rewrite code, and only when it recognizes the current insns.
185 //
186 // This patching code is non-atomic, but it runs in two safe contexts:
187 //   a) For new nmethods that are not yet executing and not yet live. This covers the paths
188 //      for newly compiled methods, nmethods that were just relocated, the nmethods that
189 //      were AOT-loaded.
190 //   b) For existing methods in the nmethod entry barrier context. The nmethod entry barriers
191 //      are armed along with stack watermark machinery activation. Together they guarantee
192 //      the nmethod updates are not interleaved with execution, and nmethod would be patched
193 //      before allowing to proceed.
194 //
195 // The icache flushing is also handled on both paths.
196 //
197 bool ShenandoahNMethod::patch_jump(address pc, address target_pc, bool should_jump) {
198   bool patched = true;
199   if (should_jump && ShenandoahBarrierSetAssembler::is_patchable_nop(pc)) {
200     ShenandoahBarrierSetAssembler::insert_patchable_jump(pc, target_pc);
201   } else if (!should_jump && ShenandoahBarrierSetAssembler::is_patchable_jump(pc, target_pc)) {
202     ShenandoahBarrierSetAssembler::insert_patchable_nop(pc);
203   } else {
204     patched = false;
205   }
206 
207   // Failing to change the jump is catastrophic for correctness,
208   // so prefer to crash hard even in product.
209   if (should_jump) {
210     guarantee(ShenandoahBarrierSetAssembler::is_patchable_jump(pc, target_pc),
211       "Should be jump to the same address");
212     assert(ShenandoahBarrierSetAssembler::parse_jump_address(pc) == target_pc,
213       "Cross-checking, jump should be to the same address");
214   } else {
215     guarantee(ShenandoahBarrierSetAssembler::is_patchable_nop(pc),
216       "Should be patchable nop");
217   }
218   return patched;
219 }
220 
221 #ifdef ASSERT
222 void ShenandoahNMethod::assert_correct() {
223   ShenandoahHeap* heap = ShenandoahHeap::heap();
224   for (int c = 0; c < _oops_count; c++) {
225     oop *loc = _oops[c];
226     assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");
227     oop o = RawAccess<>::oop_load(loc);
228     shenandoah_assert_correct_except(loc, o, o == nullptr || heap->is_full_gc_move_in_progress());
229   }
230 
231   oop* const begin = _nm->oops_begin();
232   oop* const end = _nm->oops_end();
233   for (oop* p = begin; p < end; p++) {
234     if (*p != Universe::non_oop_word()) {
235       oop o = RawAccess<>::oop_load(p);
236       shenandoah_assert_correct_except(p, o, o == nullptr || heap->is_full_gc_move_in_progress());
237     }
238   }
239 }
240 

269     assert(oops->contains(_oops[index]), "Must contain this oop");
270   }
271 
272   for (oop* p = nm()->oops_begin(); p < nm()->oops_end(); p ++) {
273     if (*p == Universe::non_oop_word()) continue;
274     count++;
275     assert(oops->contains(p), "Must contain this oop");
276   }
277 
278   if (oops->length() < count) {
279     stringStream debug_stream;
280     debug_stream.print_cr("detected locs: %d", oops->length());
281     for (int i = 0; i < oops->length(); i++) {
282       debug_stream.print_cr("-> " PTR_FORMAT, p2i(oops->at(i)));
283     }
284     debug_stream.print_cr("recorded oops: %d", _oops_count);
285     for (int i = 0; i < _oops_count; i++) {
286       debug_stream.print_cr("-> " PTR_FORMAT, p2i(_oops[i]));
287     }
288     GrowableArray<oop*> check;
289     GrowableArray<ShenandoahPatchableJump> jumps;
290     bool non_immed;
291     parse(nm(), check, non_immed, jumps);
292     debug_stream.print_cr("check oops: %d", check.length());
293     for (int i = 0; i < check.length(); i++) {
294       debug_stream.print_cr("-> " PTR_FORMAT, p2i(check.at(i)));
295     }
296     fatal("Must match #detected: %d, #recorded: %d, #total: %d, begin: " PTR_FORMAT ", end: " PTR_FORMAT "\n%s",
297           oops->length(), _oops_count, count, p2i(nm()->oops_begin()), p2i(nm()->oops_end()), debug_stream.freeze());
298   }
299 }
300 #endif
301 
302 ShenandoahNMethodTable::ShenandoahNMethodTable() :
303   _heap(ShenandoahHeap::heap()),
304   _bs_nm(BarrierSet::barrier_set()->barrier_set_nmethod()),
305   _index(0),
306   _itr_cnt(0) {
307   _list = new ShenandoahNMethodList(minSize);
308 }
309 
310 ShenandoahNMethodTable::~ShenandoahNMethodTable() {
311   assert(_list != nullptr, "Sanity");
312   _list->release();
313 }
314 
315 void ShenandoahNMethodTable::register_nmethod(nmethod* nm) {
316   assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");
317   assert(_index >= 0 && _index <= _list->size(), "Sanity");
318 
319   ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
320 
321   if (data != nullptr) {
322     // Re-registering the existing nmethod. This is the C1 oop patching path.
323     // We expect no patchable jumps here, as only oops can change in C1 case.
324     assert(contain(nm), "Must have been registered");
325     assert(nm == data->nm(), "Must be same nmethod");
326     assert(nm->is_compiled_by_c1(), "Must be compiled by C1");
327     assert(!data->has_patchable_jumps(), "Must not have patchable jumps");
328     // Prevent updating a nmethod while concurrent iteration is in progress.
329     wait_until_concurrent_iteration_done();
330     ShenandoahNMethodLocker data_locker(data->lock());
331     data->update();
332   } else {
333     // New nmethod, not yet executing. We can safely append it to the list,
334     // because concurrent iteration will not touch it. Ditto we do jump
335     // fixups right here, without relying on nmethod entry barrier to be armed
336     // for new nmethods.
337     data = ShenandoahNMethod::for_nmethod(nm);
338     assert(data != nullptr, "Sanity");
339     ShenandoahNMethod::attach_gc_data(nm, data);
340     ShenandoahLocker locker(&_lock);
341     log_register_nmethod(nm);
342     append(data);
343     ShenandoahNMethodLocker data_locker(data->lock());
344     {
345       ICacheInvalidationContext icic;
346       ShenandoahNMethod::handle_jumps(nm, &icic);
347     }
348     ShenandoahNMethod::disarm_nmethod(nm);
349   }
350 
351   assert(!data->has_patchable_jumps() || _bs_nm->supports_entry_barrier(nm),
352          "NMethods with patchable jumps require entry barrier support");
353 }
354 
355 void ShenandoahNMethodTable::unregister_nmethod(nmethod* nm) {
356   assert_locked_or_safepoint(CodeCache_lock);
357 
358   ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
359   assert(data != nullptr, "Sanity");
360   log_unregister_nmethod(nm);
361   ShenandoahLocker locker(&_lock);
362   assert(contain(nm), "Must have been registered");
363 
364   int idx = index_of(nm);
365   assert(idx >= 0 && idx < _index, "Invalid index");
366   ShenandoahNMethod::attach_gc_data(nm, nullptr);
367   remove(idx);
368 }
369 
370 bool ShenandoahNMethodTable::contain(nmethod* nm) const {
371   return index_of(nm) != -1;
372 }
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