1 /*
  2  * Copyright (c) 1997, 2025, 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 "asm/codeBuffer.hpp"
 26 #include "asm/macroAssembler.inline.hpp"
 27 #include "memory/resourceArea.hpp"
 28 #include "oops/access.inline.hpp"
 29 #include "oops/klass.hpp"
 30 #include "oops/oop.inline.hpp"
 31 #include "prims/vectorSupport.hpp"
 32 #include "runtime/continuation.hpp"
 33 #include "runtime/interfaceSupport.inline.hpp"
 34 #include "runtime/sharedRuntime.hpp"
 35 #include "runtime/stubRoutines.hpp"
 36 #include "runtime/timerTrace.hpp"
 37 #include "utilities/align.hpp"
 38 #include "utilities/copy.hpp"
 39 #ifdef COMPILER2
 40 #include "opto/runtime.hpp"
 41 #endif
 42 
 43 UnsafeMemoryAccess* UnsafeMemoryAccess::_table                  = nullptr;
 44 int UnsafeMemoryAccess::_table_length                           = 0;
 45 int UnsafeMemoryAccess::_table_max_length                       = 0;
 46 address UnsafeMemoryAccess::_common_exit_stub_pc                = nullptr;
 47 
 48 // Implementation of StubRoutines - for a description of how to
 49 // declare new blobs, stubs and entries , see stubDefinitions.hpp.
 50 
 51 // Define fields used to store blobs
 52 
 53 #define DEFINE_STUBGEN_BLOB_FIELD(blob_name)                            \
 54   BufferBlob* StubRoutines:: STUBGEN_BLOB_FIELD_NAME(blob_name) = nullptr;
 55 
 56 STUBGEN_BLOBS_DO(DEFINE_STUBGEN_BLOB_FIELD)
 57 
 58 #undef DEFINE_STUBGEN_BLOB_FIELD
 59 
 60 // Define fields used to store stubgen stub entries
 61 
 62 #define DEFINE_STUBGEN_ENTRY_FIELD(blob_name, stub_name, field_name, getter_name) \
 63   address StubRoutines:: STUB_FIELD_NAME(field_name) = nullptr;
 64 
 65 #define DEFINE_STUBGEN_ENTRY_FIELD_INIT(blob_name, stub_name, field_name, getter_name, init_function) \
 66   address StubRoutines:: STUB_FIELD_NAME(field_name) = CAST_FROM_FN_PTR(address, init_function);
 67 
 68 #define DEFINE_STUBGEN_ENTRY_FIELD_ARRAY(blob_name, stub_name, field_name, getter_name, count) \
 69   address StubRoutines:: STUB_FIELD_NAME(field_name)[count] = { nullptr };
 70 
 71 STUBGEN_ENTRIES_DO(DEFINE_STUBGEN_ENTRY_FIELD, DEFINE_STUBGEN_ENTRY_FIELD_INIT, DEFINE_STUBGEN_ENTRY_FIELD_ARRAY)
 72 
 73 #undef DEFINE_STUBGEN_ENTRY_FIELD_ARRAY
 74 #undef DEFINE_STUBGEN_ENTRY_FIELD_INIT
 75 #undef DEFINE_STUBGEN_ENTRY_FIELD
 76 
 77 jint    StubRoutines::_verify_oop_count                         = 0;
 78 
 79 
 80 address StubRoutines::_string_indexof_array[4]   =    { nullptr };
 81 
 82 const char* StubRoutines::get_blob_name(BlobId id) {
 83   assert(StubInfo::is_stubgen(id), "not a stubgen blob %s", StubInfo::name(id));
 84   return StubInfo::name(id);
 85 }
 86 
 87 const char* StubRoutines::get_stub_name(StubId id) {
 88   assert(StubInfo::is_stubgen(id), "not a stubgen stub %s", StubInfo::name(id));
 89   return StubInfo::name(id);
 90 }
 91 
 92 #ifdef ASSERT
 93 // translate a stub id to an associated blob id while checking that it
 94 // is a stubgen stub
 95 
 96 BlobId StubRoutines::stub_to_blob(StubId id) {
 97   assert(StubInfo::is_stubgen(id), "not a stubgen stub %s", StubInfo::name(id));
 98   return StubInfo::blob(id);
 99 }
100 
101 #endif // ASSERT
102 
103 // Initialization
104 
105 extern void StubGenerator_generate(CodeBuffer* code, BlobId blob_id); // only interface to generators
106 
107 void UnsafeMemoryAccess::create_table(int max_size) {
108   UnsafeMemoryAccess::_table = new UnsafeMemoryAccess[max_size];
109   UnsafeMemoryAccess::_table_max_length = max_size;
110 }
111 
112 bool UnsafeMemoryAccess::contains_pc(address pc) {
113   assert(UnsafeMemoryAccess::_table != nullptr, "");
114   for (int i = 0; i < UnsafeMemoryAccess::_table_length; i++) {
115     UnsafeMemoryAccess* entry = &UnsafeMemoryAccess::_table[i];
116     if (pc >= entry->start_pc() && pc < entry->end_pc()) {
117       return true;
118     }
119   }
120   return false;
121 }
122 
123 address UnsafeMemoryAccess::page_error_continue_pc(address pc) {
124   assert(UnsafeMemoryAccess::_table != nullptr, "");
125   for (int i = 0; i < UnsafeMemoryAccess::_table_length; i++) {
126     UnsafeMemoryAccess* entry = &UnsafeMemoryAccess::_table[i];
127     if (pc >= entry->start_pc() && pc < entry->end_pc()) {
128       return entry->error_exit_pc();
129     }
130   }
131   return nullptr;
132 }
133 
134 // Used to retrieve mark regions that lie within a generated stub so
135 // they can be saved along with the stub and used to reinit the table
136 // when the stub is reloaded.
137 
138 void UnsafeMemoryAccess::collect_entries(address range_start, address range_end, GrowableArray<address>& entries)
139 {
140   for (int i = 0; i < _table_length; i++) {
141     UnsafeMemoryAccess& e = _table[i];
142     assert((e._start_pc != nullptr &&
143             e._end_pc != nullptr &&
144             e._error_exit_pc != nullptr),
145            "search for entries found incomplete table entry");
146     if (e._start_pc >= range_start && e._end_pc <= range_end) {
147       assert(((e._error_exit_pc >= range_start &&
148                e._error_exit_pc <= range_end) ||
149               e._error_exit_pc == _common_exit_stub_pc),
150              "unexpected error exit pc");
151       entries.append(e._start_pc);
152       entries.append(e._end_pc);
153       // only return an exit pc when it is within the range of the stub
154       if (e._error_exit_pc != _common_exit_stub_pc) {
155         entries.append(e._error_exit_pc);
156       } else {
157         // an address outside the stub must be the common exit stub address
158         entries.append(nullptr);
159       }
160     }
161   }
162 }
163 
164 static BufferBlob* initialize_stubs(BlobId blob_id,
165                                     int code_size, int max_aligned_stubs,
166                                     const char* timer_msg,
167                                     const char* buffer_name,
168                                     const char* assert_msg) {
169   assert(StubInfo::is_stubgen(blob_id), "not a stubgen blob %s", StubInfo::name(blob_id));
170   ResourceMark rm;
171   TraceTime timer(timer_msg, TRACETIME_LOG(Info, startuptime));
172   // Add extra space for large CodeEntryAlignment
173   int size = code_size + CodeEntryAlignment * max_aligned_stubs;
174   BufferBlob* stubs_code = BufferBlob::create(buffer_name, size);
175   if (stubs_code == nullptr) {
176     // The compiler blob may be created late by a C2 compiler thread
177     // rather than during normal initialization by the initial thread.
178     // In that case we can tolerate an allocation failure because the
179     // compiler will have been shut down and we have no need of the
180     // blob.
181     if (Thread::current()->is_Compiler_thread()) {
182       assert(blob_id == BlobId::stubgen_compiler_id, "sanity");
183       assert(DelayCompilerStubsGeneration, "sanity");
184       log_warning(stubs)("%s\t not generated:\t no space left in CodeCache", buffer_name);
185       return nullptr;
186     }
187     vm_exit_out_of_memory(code_size, OOM_MALLOC_ERROR, "CodeCache: no room for %s", buffer_name);
188   }
189   CodeBuffer buffer(stubs_code);
190   StubGenerator_generate(&buffer, blob_id);
191   if (code_size == 0) {
192     assert(buffer.insts_size() == 0, "should not write into buffer when bob size declared as 0");
193     LogTarget(Info, stubs) lt;
194     if (lt.is_enabled()) {
195       LogStream ls(lt);
196       ls.print_cr("%s\t not generated", buffer_name);
197     }
198     return nullptr;
199   }
200   // When new stubs added we need to make sure there is some space left
201   // to catch situation when we should increase size again.
202   assert(buffer.insts_remaining() > 200,
203          "increase %s, code_size: %d, used: %d, free: %d",
204          assert_msg, code_size, buffer.total_content_size(), buffer.insts_remaining());
205 
206   LogTarget(Info, stubs) lt;
207   if (lt.is_enabled()) {
208     LogStream ls(lt);
209     ls.print_cr("%s\t [" INTPTR_FORMAT ", " INTPTR_FORMAT "] used: %d, free: %d",
210                 buffer_name, p2i(stubs_code->content_begin()), p2i(stubs_code->content_end()),
211                 buffer.total_content_size(), buffer.insts_remaining());
212   }
213 
214   return stubs_code;
215 }
216 
217 #define DEFINE_BLOB_INIT_METHOD(blob_name)                              \
218   void StubRoutines::initialize_ ## blob_name ## _stubs() {             \
219     if (STUBGEN_BLOB_FIELD_NAME(blob_name) == nullptr) {                \
220       BlobId blob_id = BlobId:: JOIN3(stubgen, blob_name, id);          \
221       int size = _ ## blob_name ## _code_size;                          \
222       int max_aligned_size = 10;                                        \
223       const char* timer_msg = "StubRoutines generation " # blob_name " stubs"; \
224       const char* name = "StubRoutines (" # blob_name " stubs)";        \
225       const char* assert_msg = "_" # blob_name "_code_size";            \
226       STUBGEN_BLOB_FIELD_NAME(blob_name) =                              \
227         initialize_stubs(blob_id, size, max_aligned_size, timer_msg,    \
228                          name, assert_msg);                             \
229     }                                                                   \
230   }
231 
232 
233 STUBGEN_BLOBS_DO(DEFINE_BLOB_INIT_METHOD)
234 
235 #undef DEFINE_BLOB_INIT_METHOD
236 
237 
238 #define DEFINE_BLOB_INIT_FUNCTION(blob_name)            \
239   void blob_name ## _stubs_init()  {                    \
240     StubRoutines::initialize_ ## blob_name ## _stubs(); \
241   }
242 
243 STUBGEN_BLOBS_DO(DEFINE_BLOB_INIT_FUNCTION)
244 
245 #undef DEFINE_BLOB_INIT_FUNCTION
246 
247 /*
248  * we generate the underlying driver method but this wrapper is needed
249  * to perform special handling depending on where the compiler init
250  * gets called from. it ought to be possible to remove this at some
251  * point and have a determinate ordered init.
252  */
253 
254 void compiler_stubs_init(bool in_compiler_thread) {
255   if (in_compiler_thread && DelayCompilerStubsGeneration) {
256     // Temporarily revert state of stubs generation because
257     // it is called after final_stubs_init() finished
258     // during compiler runtime initialization.
259     // It is fine because these stubs are only used by
260     // compiled code and compiler is not running yet.
261     StubCodeDesc::unfreeze();
262     StubRoutines::initialize_compiler_stubs();
263     StubCodeDesc::freeze();
264   } else if (!in_compiler_thread && !DelayCompilerStubsGeneration) {
265     StubRoutines::initialize_compiler_stubs();
266   }
267 }
268 
269 //
270 // Default versions of arraycopy functions
271 //
272 
273 JRT_LEAF(void, StubRoutines::jbyte_copy(jbyte* src, jbyte* dest, size_t count))
274 #ifndef PRODUCT
275   SharedRuntime::_jbyte_array_copy_ctr++;      // Slow-path byte array copy
276 #endif // !PRODUCT
277   Copy::conjoint_jbytes_atomic(src, dest, count);
278 JRT_END
279 
280 JRT_LEAF(void, StubRoutines::jshort_copy(jshort* src, jshort* dest, size_t count))
281 #ifndef PRODUCT
282   SharedRuntime::_jshort_array_copy_ctr++;     // Slow-path short/char array copy
283 #endif // !PRODUCT
284   Copy::conjoint_jshorts_atomic(src, dest, count);
285 JRT_END
286 
287 JRT_LEAF(void, StubRoutines::jint_copy(jint* src, jint* dest, size_t count))
288 #ifndef PRODUCT
289   SharedRuntime::_jint_array_copy_ctr++;       // Slow-path int/float array copy
290 #endif // !PRODUCT
291   Copy::conjoint_jints_atomic(src, dest, count);
292 JRT_END
293 
294 JRT_LEAF(void, StubRoutines::jlong_copy(jlong* src, jlong* dest, size_t count))
295 #ifndef PRODUCT
296   SharedRuntime::_jlong_array_copy_ctr++;      // Slow-path long/double array copy
297 #endif // !PRODUCT
298   Copy::conjoint_jlongs_atomic(src, dest, count);
299 JRT_END
300 
301 JRT_LEAF(void, StubRoutines::oop_copy(oop* src, oop* dest, size_t count))
302 #ifndef PRODUCT
303   SharedRuntime::_oop_array_copy_ctr++;        // Slow-path oop array copy
304 #endif // !PRODUCT
305   assert(count != 0, "count should be non-zero");
306   ArrayAccess<>::oop_arraycopy_raw((HeapWord*)src, (HeapWord*)dest, count);
307 JRT_END
308 
309 JRT_LEAF(void, StubRoutines::oop_copy_uninit(oop* src, oop* dest, size_t count))
310 #ifndef PRODUCT
311   SharedRuntime::_oop_array_copy_ctr++;        // Slow-path oop array copy
312 #endif // !PRODUCT
313   assert(count != 0, "count should be non-zero");
314   ArrayAccess<IS_DEST_UNINITIALIZED>::oop_arraycopy_raw((HeapWord*)src, (HeapWord*)dest, count);
315 JRT_END
316 
317 JRT_LEAF(void, StubRoutines::arrayof_jbyte_copy(HeapWord* src, HeapWord* dest, size_t count))
318 #ifndef PRODUCT
319   SharedRuntime::_jbyte_array_copy_ctr++;      // Slow-path byte array copy
320 #endif // !PRODUCT
321   Copy::arrayof_conjoint_jbytes(src, dest, count);
322 JRT_END
323 
324 JRT_LEAF(void, StubRoutines::arrayof_jshort_copy(HeapWord* src, HeapWord* dest, size_t count))
325 #ifndef PRODUCT
326   SharedRuntime::_jshort_array_copy_ctr++;     // Slow-path short/char array copy
327 #endif // !PRODUCT
328   Copy::arrayof_conjoint_jshorts(src, dest, count);
329 JRT_END
330 
331 JRT_LEAF(void, StubRoutines::arrayof_jint_copy(HeapWord* src, HeapWord* dest, size_t count))
332 #ifndef PRODUCT
333   SharedRuntime::_jint_array_copy_ctr++;       // Slow-path int/float array copy
334 #endif // !PRODUCT
335   Copy::arrayof_conjoint_jints(src, dest, count);
336 JRT_END
337 
338 JRT_LEAF(void, StubRoutines::arrayof_jlong_copy(HeapWord* src, HeapWord* dest, size_t count))
339 #ifndef PRODUCT
340   SharedRuntime::_jlong_array_copy_ctr++;       // Slow-path int/float array copy
341 #endif // !PRODUCT
342   Copy::arrayof_conjoint_jlongs(src, dest, count);
343 JRT_END
344 
345 JRT_LEAF(void, StubRoutines::arrayof_oop_copy(HeapWord* src, HeapWord* dest, size_t count))
346 #ifndef PRODUCT
347   SharedRuntime::_oop_array_copy_ctr++;        // Slow-path oop array copy
348 #endif // !PRODUCT
349   assert(count != 0, "count should be non-zero");
350   ArrayAccess<ARRAYCOPY_ARRAYOF>::oop_arraycopy_raw(src, dest, count);
351 JRT_END
352 
353 JRT_LEAF(void, StubRoutines::arrayof_oop_copy_uninit(HeapWord* src, HeapWord* dest, size_t count))
354 #ifndef PRODUCT
355   SharedRuntime::_oop_array_copy_ctr++;        // Slow-path oop array copy
356 #endif // !PRODUCT
357   assert(count != 0, "count should be non-zero");
358   ArrayAccess<ARRAYCOPY_ARRAYOF | IS_DEST_UNINITIALIZED>::oop_arraycopy_raw(src, dest, count);
359 JRT_END
360 
361 address StubRoutines::select_fill_function(BasicType t, bool aligned, const char* &name) {
362 #define RETURN_STUB(xxx_fill) { \
363   name = #xxx_fill; \
364   return StubRoutines::xxx_fill(); }
365 
366   switch (t) {
367   case T_BYTE:
368   case T_BOOLEAN:
369     if (!aligned) RETURN_STUB(jbyte_fill);
370     RETURN_STUB(arrayof_jbyte_fill);
371   case T_CHAR:
372   case T_SHORT:
373     if (!aligned) RETURN_STUB(jshort_fill);
374     RETURN_STUB(arrayof_jshort_fill);
375   case T_INT:
376   case T_FLOAT:
377     if (!aligned) RETURN_STUB(jint_fill);
378     RETURN_STUB(arrayof_jint_fill);
379   case T_DOUBLE:
380   case T_LONG:
381   case T_ARRAY:
382   case T_OBJECT:
383   case T_NARROWOOP:
384   case T_NARROWKLASS:
385   case T_ADDRESS:
386   case T_VOID:
387     // Currently unsupported
388     return nullptr;
389 
390   default:
391     ShouldNotReachHere();
392     return nullptr;
393   }
394 
395 #undef RETURN_STUB
396 }
397 
398 // constants for computing the copy function
399 enum {
400   COPYFUNC_UNALIGNED = 0,
401   COPYFUNC_ALIGNED = 1,                 // src, dest aligned to HeapWordSize
402   COPYFUNC_CONJOINT = 0,
403   COPYFUNC_DISJOINT = 2                 // src != dest, or transfer can descend
404 };
405 
406 // Note:  The condition "disjoint" applies also for overlapping copies
407 // where an descending copy is permitted (i.e., dest_offset <= src_offset).
408 address
409 StubRoutines::select_arraycopy_function(BasicType t, bool aligned, bool disjoint, const char* &name, bool dest_uninitialized) {
410   int selector =
411     (aligned  ? COPYFUNC_ALIGNED  : COPYFUNC_UNALIGNED) +
412     (disjoint ? COPYFUNC_DISJOINT : COPYFUNC_CONJOINT);
413 
414 #define RETURN_STUB(xxx_arraycopy) { \
415   name = #xxx_arraycopy; \
416   return StubRoutines::xxx_arraycopy(); }
417 
418 #define RETURN_STUB_PARM(xxx_arraycopy, parm) { \
419   name = parm ? #xxx_arraycopy "_uninit": #xxx_arraycopy; \
420   return StubRoutines::xxx_arraycopy(parm); }
421 
422   switch (t) {
423   case T_BYTE:
424   case T_BOOLEAN:
425     switch (selector) {
426     case COPYFUNC_CONJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB(jbyte_arraycopy);
427     case COPYFUNC_CONJOINT | COPYFUNC_ALIGNED:    RETURN_STUB(arrayof_jbyte_arraycopy);
428     case COPYFUNC_DISJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB(jbyte_disjoint_arraycopy);
429     case COPYFUNC_DISJOINT | COPYFUNC_ALIGNED:    RETURN_STUB(arrayof_jbyte_disjoint_arraycopy);
430     }
431   case T_CHAR:
432   case T_SHORT:
433     switch (selector) {
434     case COPYFUNC_CONJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB(jshort_arraycopy);
435     case COPYFUNC_CONJOINT | COPYFUNC_ALIGNED:    RETURN_STUB(arrayof_jshort_arraycopy);
436     case COPYFUNC_DISJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB(jshort_disjoint_arraycopy);
437     case COPYFUNC_DISJOINT | COPYFUNC_ALIGNED:    RETURN_STUB(arrayof_jshort_disjoint_arraycopy);
438     }
439   case T_INT:
440   case T_FLOAT:
441     switch (selector) {
442     case COPYFUNC_CONJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB(jint_arraycopy);
443     case COPYFUNC_CONJOINT | COPYFUNC_ALIGNED:    RETURN_STUB(arrayof_jint_arraycopy);
444     case COPYFUNC_DISJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB(jint_disjoint_arraycopy);
445     case COPYFUNC_DISJOINT | COPYFUNC_ALIGNED:    RETURN_STUB(arrayof_jint_disjoint_arraycopy);
446     }
447   case T_DOUBLE:
448   case T_LONG:
449     switch (selector) {
450     case COPYFUNC_CONJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB(jlong_arraycopy);
451     case COPYFUNC_CONJOINT | COPYFUNC_ALIGNED:    RETURN_STUB(arrayof_jlong_arraycopy);
452     case COPYFUNC_DISJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB(jlong_disjoint_arraycopy);
453     case COPYFUNC_DISJOINT | COPYFUNC_ALIGNED:    RETURN_STUB(arrayof_jlong_disjoint_arraycopy);
454     }
455   case T_ARRAY:
456   case T_OBJECT:
457     switch (selector) {
458     case COPYFUNC_CONJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB_PARM(oop_arraycopy, dest_uninitialized);
459     case COPYFUNC_CONJOINT | COPYFUNC_ALIGNED:    RETURN_STUB_PARM(arrayof_oop_arraycopy, dest_uninitialized);
460     case COPYFUNC_DISJOINT | COPYFUNC_UNALIGNED:  RETURN_STUB_PARM(oop_disjoint_arraycopy, dest_uninitialized);
461     case COPYFUNC_DISJOINT | COPYFUNC_ALIGNED:    RETURN_STUB_PARM(arrayof_oop_disjoint_arraycopy, dest_uninitialized);
462     }
463   default:
464     ShouldNotReachHere();
465     return nullptr;
466   }
467 
468 #undef RETURN_STUB
469 #undef RETURN_STUB_PARM
470 }
471 
472 UnsafeMemoryAccessMark::UnsafeMemoryAccessMark(StubCodeGenerator* cgen, bool add_entry, bool continue_at_scope_end, address error_exit_pc) {
473   _cgen = cgen;
474   _ucm_entry = nullptr;
475   if (add_entry) {
476     address err_exit_pc = nullptr;
477     if (!continue_at_scope_end) {
478       err_exit_pc = error_exit_pc != nullptr ? error_exit_pc : UnsafeMemoryAccess::common_exit_stub_pc();
479     }
480     assert(err_exit_pc != nullptr || continue_at_scope_end, "error exit not set");
481     _ucm_entry = UnsafeMemoryAccess::add_to_table(_cgen->assembler()->pc(), nullptr, err_exit_pc);
482   }
483 }
484 
485 UnsafeMemoryAccessMark::~UnsafeMemoryAccessMark() {
486   if (_ucm_entry != nullptr) {
487     _ucm_entry->set_end_pc(_cgen->assembler()->pc());
488     if (_ucm_entry->error_exit_pc() == nullptr) {
489       _ucm_entry->set_error_exit_pc(_cgen->assembler()->pc());
490     }
491   }
492 }