Fri, 27 Feb 2009 13:27:09 -0800
6810672: Comment typos
Summary: I have collected some typos I have found while looking at the code.
Reviewed-by: kvn, never
1 /*
2 * Copyright 1997-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 // This class is used internally by nmethods, to cache
26 // exception/pc/handler information.
28 class ExceptionCache : public CHeapObj {
29 friend class VMStructs;
30 private:
31 static address _unwind_handler;
32 enum { cache_size = 16 };
33 klassOop _exception_type;
34 address _pc[cache_size];
35 address _handler[cache_size];
36 int _count;
37 ExceptionCache* _next;
39 address pc_at(int index) { assert(index >= 0 && index < count(),""); return _pc[index]; }
40 void set_pc_at(int index, address a) { assert(index >= 0 && index < cache_size,""); _pc[index] = a; }
41 address handler_at(int index) { assert(index >= 0 && index < count(),""); return _handler[index]; }
42 void set_handler_at(int index, address a) { assert(index >= 0 && index < cache_size,""); _handler[index] = a; }
43 int count() { return _count; }
44 void increment_count() { _count++; }
46 public:
48 ExceptionCache(Handle exception, address pc, address handler);
50 klassOop exception_type() { return _exception_type; }
51 klassOop* exception_type_addr() { return &_exception_type; }
52 ExceptionCache* next() { return _next; }
53 void set_next(ExceptionCache *ec) { _next = ec; }
55 address match(Handle exception, address pc);
56 bool match_exception_with_space(Handle exception) ;
57 address test_address(address addr);
58 bool add_address_and_handler(address addr, address handler) ;
60 static address unwind_handler() { return _unwind_handler; }
61 };
64 // cache pc descs found in earlier inquiries
65 class PcDescCache VALUE_OBJ_CLASS_SPEC {
66 friend class VMStructs;
67 private:
68 enum { cache_size = 4 };
69 PcDesc* _last_pc_desc; // most recent pc_desc found
70 PcDesc* _pc_descs[cache_size]; // last cache_size pc_descs found
71 public:
72 PcDescCache() { debug_only(_last_pc_desc = NULL); }
73 void reset_to(PcDesc* initial_pc_desc);
74 PcDesc* find_pc_desc(int pc_offset, bool approximate);
75 void add_pc_desc(PcDesc* pc_desc);
76 PcDesc* last_pc_desc() { return _last_pc_desc; }
77 };
80 // nmethods (native methods) are the compiled code versions of Java methods.
82 struct nmFlags {
83 friend class VMStructs;
84 unsigned int version:8; // version number (0 = first version)
85 unsigned int level:4; // optimization level
86 unsigned int age:4; // age (in # of sweep steps)
88 unsigned int state:2; // {alive, zombie, unloaded)
90 unsigned int isUncommonRecompiled:1; // recompiled because of uncommon trap?
91 unsigned int isToBeRecompiled:1; // to be recompiled as soon as it matures
92 unsigned int hasFlushedDependencies:1; // Used for maintenance of dependencies
93 unsigned int markedForReclamation:1; // Used by NMethodSweeper
95 unsigned int has_unsafe_access:1; // May fault due to unsafe access.
97 void clear();
98 };
101 // A nmethod contains:
102 // - header (the nmethod structure)
103 // [Relocation]
104 // - relocation information
105 // - constant part (doubles, longs and floats used in nmethod)
106 // [Code]
107 // - code body
108 // - exception handler
109 // - stub code
110 // [Debugging information]
111 // - oop array
112 // - data array
113 // - pcs
114 // [Exception handler table]
115 // - handler entry point array
116 // [Implicit Null Pointer exception table]
117 // - implicit null table array
119 class Dependencies;
120 class ExceptionHandlerTable;
121 class ImplicitExceptionTable;
122 class AbstractCompiler;
123 class xmlStream;
125 class nmethod : public CodeBlob {
126 friend class VMStructs;
127 friend class NMethodSweeper;
128 private:
129 // Shared fields for all nmethod's
130 static int _zombie_instruction_size;
132 methodOop _method;
133 int _entry_bci; // != InvocationEntryBci if this nmethod is an on-stack replacement method
135 nmethod* _link; // To support simple linked-list chaining of nmethods
137 AbstractCompiler* _compiler; // The compiler which compiled this nmethod
139 // Offsets for different nmethod parts
140 int _exception_offset;
141 // All deoptee's will resume execution at this location described by this offset
142 int _deoptimize_offset;
143 #ifdef HAVE_DTRACE_H
144 int _trap_offset;
145 #endif // def HAVE_DTRACE_H
146 int _stub_offset;
147 int _consts_offset;
148 int _scopes_data_offset;
149 int _scopes_pcs_offset;
150 int _dependencies_offset;
151 int _handler_table_offset;
152 int _nul_chk_table_offset;
153 int _nmethod_end_offset;
155 // location in frame (offset for sp) that deopt can store the original
156 // pc during a deopt.
157 int _orig_pc_offset;
159 int _compile_id; // which compilation made this nmethod
160 int _comp_level; // compilation level
162 // offsets for entry points
163 address _entry_point; // entry point with class check
164 address _verified_entry_point; // entry point without class check
165 address _osr_entry_point; // entry point for on stack replacement
167 nmFlags flags; // various flags to keep track of nmethod state
168 bool _markedForDeoptimization; // Used for stack deoptimization
169 enum { alive = 0,
170 not_entrant = 1, // uncommon trap has happened but activations may still exist
171 zombie = 2,
172 unloaded = 3 };
174 // used by jvmti to track if an unload event has been posted for this nmethod.
175 bool _unload_reported;
177 NOT_PRODUCT(bool _has_debug_info; )
179 // Nmethod Flushing lock (if non-zero, then the nmethod is not removed)
180 jint _lock_count;
182 // not_entrant method removal. Each mark_sweep pass will update
183 // this mark to current sweep invocation count if it is seen on the
184 // stack. An not_entrant method can be removed when there is no
185 // more activations, i.e., when the _stack_traversal_mark is less than
186 // current sweep traversal index.
187 long _stack_traversal_mark;
189 ExceptionCache *_exception_cache;
190 PcDescCache _pc_desc_cache;
192 // These are only used for compiled synchronized native methods to
193 // locate the owner and stack slot for the BasicLock so that we can
194 // properly revoke the bias of the owner if necessary. They are
195 // needed because there is no debug information for compiled native
196 // wrappers and the oop maps are insufficient to allow
197 // frame::retrieve_receiver() to work. Currently they are expected
198 // to be byte offsets from the Java stack pointer for maximum code
199 // sharing between platforms. Note that currently biased locking
200 // will never cause Class instances to be biased but this code
201 // handles the static synchronized case as well.
202 ByteSize _compiled_synchronized_native_basic_lock_owner_sp_offset;
203 ByteSize _compiled_synchronized_native_basic_lock_sp_offset;
205 friend class nmethodLocker;
207 // For native wrappers
208 nmethod(methodOop method,
209 int nmethod_size,
210 CodeOffsets* offsets,
211 CodeBuffer *code_buffer,
212 int frame_size,
213 ByteSize basic_lock_owner_sp_offset, /* synchronized natives only */
214 ByteSize basic_lock_sp_offset, /* synchronized natives only */
215 OopMapSet* oop_maps);
217 #ifdef HAVE_DTRACE_H
218 // For native wrappers
219 nmethod(methodOop method,
220 int nmethod_size,
221 CodeOffsets* offsets,
222 CodeBuffer *code_buffer,
223 int frame_size);
224 #endif // def HAVE_DTRACE_H
226 // Creation support
227 nmethod(methodOop method,
228 int nmethod_size,
229 int compile_id,
230 int entry_bci,
231 CodeOffsets* offsets,
232 int orig_pc_offset,
233 DebugInformationRecorder *recorder,
234 Dependencies* dependencies,
235 CodeBuffer *code_buffer,
236 int frame_size,
237 OopMapSet* oop_maps,
238 ExceptionHandlerTable* handler_table,
239 ImplicitExceptionTable* nul_chk_table,
240 AbstractCompiler* compiler,
241 int comp_level);
243 // helper methods
244 void* operator new(size_t size, int nmethod_size);
245 void check_store();
247 const char* reloc_string_for(u_char* begin, u_char* end);
248 void make_not_entrant_or_zombie(int state);
249 void inc_decompile_count();
251 // used to check that writes to nmFlags are done consistently.
252 static void check_safepoint() PRODUCT_RETURN;
254 // Used to manipulate the exception cache
255 void add_exception_cache_entry(ExceptionCache* new_entry);
256 ExceptionCache* exception_cache_entry_for_exception(Handle exception);
258 // Inform external interfaces that a compiled method has been unloaded
259 inline void post_compiled_method_unload();
261 public:
262 // create nmethod with entry_bci
263 static nmethod* new_nmethod(methodHandle method,
264 int compile_id,
265 int entry_bci,
266 CodeOffsets* offsets,
267 int orig_pc_offset,
268 DebugInformationRecorder* recorder,
269 Dependencies* dependencies,
270 CodeBuffer *code_buffer,
271 int frame_size,
272 OopMapSet* oop_maps,
273 ExceptionHandlerTable* handler_table,
274 ImplicitExceptionTable* nul_chk_table,
275 AbstractCompiler* compiler,
276 int comp_level);
278 static nmethod* new_native_nmethod(methodHandle method,
279 CodeBuffer *code_buffer,
280 int vep_offset,
281 int frame_complete,
282 int frame_size,
283 ByteSize receiver_sp_offset,
284 ByteSize basic_lock_sp_offset,
285 OopMapSet* oop_maps);
287 #ifdef HAVE_DTRACE_H
288 // The method we generate for a dtrace probe has to look
289 // like an nmethod as far as the rest of the system is concerned
290 // which is somewhat unfortunate.
291 static nmethod* new_dtrace_nmethod(methodHandle method,
292 CodeBuffer *code_buffer,
293 int vep_offset,
294 int trap_offset,
295 int frame_complete,
296 int frame_size);
298 int trap_offset() const { return _trap_offset; }
299 address trap_address() const { return code_begin() + _trap_offset; }
301 #endif // def HAVE_DTRACE_H
303 // accessors
304 methodOop method() const { return _method; }
305 AbstractCompiler* compiler() const { return _compiler; }
307 #ifndef PRODUCT
308 bool has_debug_info() const { return _has_debug_info; }
309 void set_has_debug_info(bool f) { _has_debug_info = false; }
310 #endif // NOT PRODUCT
312 // type info
313 bool is_nmethod() const { return true; }
314 bool is_java_method() const { return !method()->is_native(); }
315 bool is_native_method() const { return method()->is_native(); }
316 bool is_osr_method() const { return _entry_bci != InvocationEntryBci; }
317 bool is_osr_only_method() const { return is_osr_method(); }
319 bool is_compiled_by_c1() const;
320 bool is_compiled_by_c2() const;
322 // boundaries for different parts
323 address code_begin () const { return _entry_point; }
324 address code_end () const { return header_begin() + _stub_offset ; }
325 address exception_begin () const { return header_begin() + _exception_offset ; }
326 address deopt_handler_begin() const { return header_begin() + _deoptimize_offset ; }
327 address stub_begin () const { return header_begin() + _stub_offset ; }
328 address stub_end () const { return header_begin() + _consts_offset ; }
329 address consts_begin () const { return header_begin() + _consts_offset ; }
330 address consts_end () const { return header_begin() + _scopes_data_offset ; }
331 address scopes_data_begin () const { return header_begin() + _scopes_data_offset ; }
332 address scopes_data_end () const { return header_begin() + _scopes_pcs_offset ; }
333 PcDesc* scopes_pcs_begin () const { return (PcDesc*)(header_begin() + _scopes_pcs_offset ); }
334 PcDesc* scopes_pcs_end () const { return (PcDesc*)(header_begin() + _dependencies_offset); }
335 address dependencies_begin () const { return header_begin() + _dependencies_offset ; }
336 address dependencies_end () const { return header_begin() + _handler_table_offset ; }
337 address handler_table_begin() const { return header_begin() + _handler_table_offset ; }
338 address handler_table_end () const { return header_begin() + _nul_chk_table_offset ; }
339 address nul_chk_table_begin() const { return header_begin() + _nul_chk_table_offset ; }
340 address nul_chk_table_end () const { return header_begin() + _nmethod_end_offset ; }
342 int code_size () const { return code_end () - code_begin (); }
343 int stub_size () const { return stub_end () - stub_begin (); }
344 int consts_size () const { return consts_end () - consts_begin (); }
345 int scopes_data_size () const { return scopes_data_end () - scopes_data_begin (); }
346 int scopes_pcs_size () const { return (intptr_t)scopes_pcs_end () - (intptr_t)scopes_pcs_begin (); }
347 int dependencies_size () const { return dependencies_end () - dependencies_begin (); }
348 int handler_table_size() const { return handler_table_end() - handler_table_begin(); }
349 int nul_chk_table_size() const { return nul_chk_table_end() - nul_chk_table_begin(); }
351 int total_size () const;
353 bool code_contains (address addr) const { return code_begin () <= addr && addr < code_end (); }
354 bool stub_contains (address addr) const { return stub_begin () <= addr && addr < stub_end (); }
355 bool consts_contains (address addr) const { return consts_begin () <= addr && addr < consts_end (); }
356 bool scopes_data_contains (address addr) const { return scopes_data_begin () <= addr && addr < scopes_data_end (); }
357 bool scopes_pcs_contains (PcDesc* addr) const { return scopes_pcs_begin () <= addr && addr < scopes_pcs_end (); }
358 bool handler_table_contains(address addr) const { return handler_table_begin() <= addr && addr < handler_table_end(); }
359 bool nul_chk_table_contains(address addr) const { return nul_chk_table_begin() <= addr && addr < nul_chk_table_end(); }
361 // entry points
362 address entry_point() const { return _entry_point; } // normal entry point
363 address verified_entry_point() const { return _verified_entry_point; } // if klass is correct
365 // flag accessing and manipulation
366 bool is_in_use() const { return flags.state == alive; }
367 bool is_alive() const { return flags.state == alive || flags.state == not_entrant; }
368 bool is_not_entrant() const { return flags.state == not_entrant; }
369 bool is_zombie() const { return flags.state == zombie; }
370 bool is_unloaded() const { return flags.state == unloaded; }
372 // Make the nmethod non entrant. The nmethod will continue to be alive.
373 // It is used when an uncommon trap happens.
374 void make_not_entrant() { make_not_entrant_or_zombie(not_entrant); }
375 void make_zombie() { make_not_entrant_or_zombie(zombie); }
377 // used by jvmti to track if the unload event has been reported
378 bool unload_reported() { return _unload_reported; }
379 void set_unload_reported() { _unload_reported = true; }
381 bool is_marked_for_deoptimization() const { return _markedForDeoptimization; }
382 void mark_for_deoptimization() { _markedForDeoptimization = true; }
384 void make_unloaded(BoolObjectClosure* is_alive, oop cause);
386 bool has_dependencies() { return dependencies_size() != 0; }
387 void flush_dependencies(BoolObjectClosure* is_alive);
388 bool has_flushed_dependencies() { return flags.hasFlushedDependencies; }
389 void set_has_flushed_dependencies() {
390 check_safepoint();
391 assert(!has_flushed_dependencies(), "should only happen once");
392 flags.hasFlushedDependencies = 1;
393 }
395 bool is_marked_for_reclamation() const { return flags.markedForReclamation; }
396 void mark_for_reclamation() { check_safepoint(); flags.markedForReclamation = 1; }
397 void unmark_for_reclamation() { check_safepoint(); flags.markedForReclamation = 0; }
399 bool has_unsafe_access() const { return flags.has_unsafe_access; }
400 void set_has_unsafe_access(bool z) { flags.has_unsafe_access = z; }
402 int level() const { return flags.level; }
403 void set_level(int newLevel) { check_safepoint(); flags.level = newLevel; }
405 int comp_level() const { return _comp_level; }
407 int version() const { return flags.version; }
408 void set_version(int v);
410 // Sweeper support
411 long stack_traversal_mark() { return _stack_traversal_mark; }
412 void set_stack_traversal_mark(long l) { _stack_traversal_mark = l; }
414 // Exception cache support
415 ExceptionCache* exception_cache() const { return _exception_cache; }
416 void set_exception_cache(ExceptionCache *ec) { _exception_cache = ec; }
417 address handler_for_exception_and_pc(Handle exception, address pc);
418 void add_handler_for_exception_and_pc(Handle exception, address pc, address handler);
419 void remove_from_exception_cache(ExceptionCache* ec);
421 // implicit exceptions support
422 address continuation_for_implicit_exception(address pc);
424 // On-stack replacement support
425 int osr_entry_bci() const { assert(_entry_bci != InvocationEntryBci, "wrong kind of nmethod"); return _entry_bci; }
426 address osr_entry() const { assert(_entry_bci != InvocationEntryBci, "wrong kind of nmethod"); return _osr_entry_point; }
427 void invalidate_osr_method();
428 nmethod* link() const { return _link; }
429 void set_link(nmethod *n) { _link = n; }
431 // tells whether frames described by this nmethod can be deoptimized
432 // note: native wrappers cannot be deoptimized.
433 bool can_be_deoptimized() const { return is_java_method(); }
435 // Inline cache support
436 void clear_inline_caches();
437 void cleanup_inline_caches();
438 bool inlinecache_check_contains(address addr) const {
439 return (addr >= instructions_begin() && addr < verified_entry_point());
440 }
442 // unlink and deallocate this nmethod
443 // Only NMethodSweeper class is expected to use this. NMethodSweeper is not
444 // expected to use any other private methods/data in this class.
446 protected:
447 void flush();
449 public:
450 // If returning true, it is unsafe to remove this nmethod even though it is a zombie
451 // nmethod, since the VM might have a reference to it. Should only be called from a safepoint.
452 bool is_locked_by_vm() const { return _lock_count >0; }
454 // See comment at definition of _last_seen_on_stack
455 void mark_as_seen_on_stack();
456 bool can_not_entrant_be_converted();
458 // Evolution support. We make old (discarded) compiled methods point to new methodOops.
459 void set_method(methodOop method) { _method = method; }
461 // GC support
462 void do_unloading(BoolObjectClosure* is_alive, OopClosure* keep_alive,
463 bool unloading_occurred);
464 bool can_unload(BoolObjectClosure* is_alive, OopClosure* keep_alive,
465 oop* root, bool unloading_occurred);
467 void preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map,
468 OopClosure* f);
469 void oops_do(OopClosure* f);
471 // ScopeDesc for an instruction
472 ScopeDesc* scope_desc_at(address pc);
474 private:
475 ScopeDesc* scope_desc_in(address begin, address end);
477 address* orig_pc_addr(const frame* fr ) { return (address*) ((address)fr->unextended_sp() + _orig_pc_offset); }
479 PcDesc* find_pc_desc_internal(address pc, bool approximate);
481 PcDesc* find_pc_desc(address pc, bool approximate) {
482 PcDesc* desc = _pc_desc_cache.last_pc_desc();
483 if (desc != NULL && desc->pc_offset() == pc - instructions_begin()) {
484 return desc;
485 }
486 return find_pc_desc_internal(pc, approximate);
487 }
489 public:
490 // ScopeDesc retrieval operation
491 PcDesc* pc_desc_at(address pc) { return find_pc_desc(pc, false); }
492 // pc_desc_near returns the first PcDesc at or after the givne pc.
493 PcDesc* pc_desc_near(address pc) { return find_pc_desc(pc, true); }
495 public:
496 // copying of debugging information
497 void copy_scopes_pcs(PcDesc* pcs, int count);
498 void copy_scopes_data(address buffer, int size);
500 // deopt
501 // return true is the pc is one would expect if the frame is being deopted.
502 bool is_deopt_pc(address pc);
503 // Accessor/mutator for the original pc of a frame before a frame was deopted.
504 address get_original_pc(const frame* fr) { return *orig_pc_addr(fr); }
505 void set_original_pc(const frame* fr, address pc) { *orig_pc_addr(fr) = pc; }
507 // jvmti support:
508 void post_compiled_method_load_event();
510 // verify operations
511 void verify();
512 void verify_scopes();
513 void verify_interrupt_point(address interrupt_point);
515 // printing support
516 void print() const;
517 void print_code();
518 void print_relocations() PRODUCT_RETURN;
519 void print_pcs() PRODUCT_RETURN;
520 void print_scopes() PRODUCT_RETURN;
521 void print_dependencies() PRODUCT_RETURN;
522 void print_value_on(outputStream* st) const PRODUCT_RETURN;
523 void print_calls(outputStream* st) PRODUCT_RETURN;
524 void print_handler_table() PRODUCT_RETURN;
525 void print_nul_chk_table() PRODUCT_RETURN;
526 void print_nmethod(bool print_code);
528 void print_on(outputStream* st, const char* title) const;
530 // Logging
531 void log_identity(xmlStream* log) const;
532 void log_new_nmethod() const;
533 void log_state_change(int state) const;
535 // Prints a comment for one native instruction (reloc info, pc desc)
536 void print_code_comment_on(outputStream* st, int column, address begin, address end);
537 static void print_statistics() PRODUCT_RETURN;
539 // Compiler task identification. Note that all OSR methods
540 // are numbered in an independent sequence if CICountOSR is true,
541 // and native method wrappers are also numbered independently if
542 // CICountNative is true.
543 int compile_id() const { return _compile_id; }
544 const char* compile_kind() const;
546 // For debugging
547 // CompiledIC* IC_at(char* p) const;
548 // PrimitiveIC* primitiveIC_at(char* p) const;
549 oop embeddedOop_at(address p);
551 // tells if any of this method's dependencies have been invalidated
552 // (this is expensive!)
553 bool check_all_dependencies();
555 // tells if this compiled method is dependent on the given changes,
556 // and the changes have invalidated it
557 bool check_dependency_on(DepChange& changes);
559 // Evolution support. Tells if this compiled method is dependent on any of
560 // methods m() of class dependee, such that if m() in dependee is replaced,
561 // this compiled method will have to be deoptimized.
562 bool is_evol_dependent_on(klassOop dependee);
564 // Fast breakpoint support. Tells if this compiled method is
565 // dependent on the given method. Returns true if this nmethod
566 // corresponds to the given method as well.
567 bool is_dependent_on_method(methodOop dependee);
569 // is it ok to patch at address?
570 bool is_patchable_at(address instr_address);
572 // UseBiasedLocking support
573 ByteSize compiled_synchronized_native_basic_lock_owner_sp_offset() {
574 return _compiled_synchronized_native_basic_lock_owner_sp_offset;
575 }
576 ByteSize compiled_synchronized_native_basic_lock_sp_offset() {
577 return _compiled_synchronized_native_basic_lock_sp_offset;
578 }
580 // support for code generation
581 static int verified_entry_point_offset() { return offset_of(nmethod, _verified_entry_point); }
582 static int osr_entry_point_offset() { return offset_of(nmethod, _osr_entry_point); }
583 static int entry_bci_offset() { return offset_of(nmethod, _entry_bci); }
585 };
587 // Locks an nmethod so its code will not get removed, even if it is a zombie/not_entrant method
588 class nmethodLocker : public StackObj {
589 nmethod* _nm;
591 static void lock_nmethod(nmethod* nm); // note: nm can be NULL
592 static void unlock_nmethod(nmethod* nm); // (ditto)
594 public:
595 nmethodLocker(address pc); // derive nm from pc
596 nmethodLocker(nmethod *nm) { _nm = nm; lock_nmethod(_nm); }
597 nmethodLocker() { _nm = NULL; }
598 ~nmethodLocker() { unlock_nmethod(_nm); }
600 nmethod* code() { return _nm; }
601 void set_code(nmethod* new_nm) {
602 unlock_nmethod(_nm); // note: This works even if _nm==new_nm.
603 _nm = new_nm;
604 lock_nmethod(_nm);
605 }
606 };