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comparison src/share/vm/runtime/relocator.cpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 1997-2005 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 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_relocator.cpp.incl"
27
28 #define MAX_METHOD_LENGTH 65535
29
30 #define MAX_SHORT ((1 << 15) - 1)
31 #define MIN_SHORT (- (1 << 15))
32
33 // Encapsulates a code change request. There are 3 types.
34 // General instruction, jump instruction, and table/lookup switches
35 //
36 class ChangeItem : public ResourceObj {
37 int _bci;
38 public:
39 ChangeItem(int bci) { _bci = bci; }
40 virtual bool handle_code_change(Relocator *r) = 0;
41
42 // type info
43 virtual bool is_widen() { return false; }
44 virtual bool is_jump_widen() { return false; }
45 virtual bool is_switch_pad() { return false; }
46
47 // accessors
48 int bci() { return _bci; }
49 void relocate(int break_bci, int delta) { if (_bci > break_bci) { _bci += delta; } }
50
51 virtual bool adjust(int bci, int delta) { return false; }
52
53 // debug
54 virtual void print() = 0;
55 };
56
57 class ChangeWiden : public ChangeItem {
58 int _new_ilen; // New length of instruction at bci
59 u_char* _inst_buffer; // New bytecodes
60 public:
61 ChangeWiden(int bci, int new_ilen, u_char* inst_buffer) : ChangeItem(bci) {
62 _new_ilen = new_ilen;
63 _inst_buffer = inst_buffer;
64 }
65
66 // Callback to do instruction
67 bool handle_code_change(Relocator *r) { return r->handle_widen(bci(), _new_ilen, _inst_buffer); };
68
69 bool is_widen() { return true; }
70
71 void print() { tty->print_cr("ChangeWiden. bci: %d New_ilen: %d", bci(), _new_ilen); }
72 };
73
74 class ChangeJumpWiden : public ChangeItem {
75 int _delta; // New length of instruction at bci
76 public:
77 ChangeJumpWiden(int bci, int delta) : ChangeItem(bci) { _delta = delta; }
78
79 // Callback to do instruction
80 bool handle_code_change(Relocator *r) { return r->handle_jump_widen(bci(), _delta); };
81
82 bool is_jump_widen() { return true; }
83
84 // If the bci matches, adjust the delta in the change jump request.
85 bool adjust(int jump_bci, int delta) {
86 if (bci() == jump_bci) {
87 if (_delta > 0)
88 _delta += delta;
89 else
90 _delta -= delta;
91 return true;
92 }
93 return false;
94 }
95
96 void print() { tty->print_cr("ChangeJumpWiden. bci: %d Delta: %d", bci(), _delta); }
97 };
98
99 class ChangeSwitchPad : public ChangeItem {
100 int _padding;
101 bool _is_lookup_switch;
102 public:
103 ChangeSwitchPad(int bci, int padding, bool is_lookup_switch) : ChangeItem(bci) {
104 _padding = padding;
105 _is_lookup_switch = is_lookup_switch;
106 }
107
108 // Callback to do instruction
109 bool handle_code_change(Relocator *r) { return r->handle_switch_pad(bci(), _padding, _is_lookup_switch); };
110
111 bool is_switch_pad() { return true; }
112 int padding() { return _padding; }
113 bool is_lookup_switch() { return _is_lookup_switch; }
114
115 void print() { tty->print_cr("ChangeSwitchPad. bci: %d Padding: %d IsLookupSwitch: %d", bci(), _padding, _is_lookup_switch); }
116 };
117
118 //-----------------------------------------------------------------------------------------------------------
119 // Relocator code
120
121 Relocator::Relocator(methodHandle m, RelocatorListener* listener) {
122 set_method(m);
123 set_code_length(method()->code_size());
124 set_code_array(NULL);
125 // Allocate code array and copy bytecodes
126 if (!expand_code_array(0)) {
127 // Should have at least MAX_METHOD_LENGTH available or the verifier
128 // would have failed.
129 ShouldNotReachHere();
130 }
131 set_compressed_line_number_table(NULL);
132 set_compressed_line_number_table_size(0);
133 _listener = listener;
134 }
135
136 // size is the new size of the instruction at bci. Hence, if size is less than the current
137 // instruction sice, we will shrink the code.
138 methodHandle Relocator::insert_space_at(int bci, int size, u_char inst_buffer[], TRAPS) {
139 _changes = new GrowableArray<ChangeItem*> (10);
140 _changes->push(new ChangeWiden(bci, size, inst_buffer));
141
142 if (TraceRelocator) {
143 tty->print_cr("Space at: %d Size: %d", bci, size);
144 _method->print();
145 _method->print_codes();
146 tty->print_cr("-------------------------------------------------");
147 }
148
149 if (!handle_code_changes()) return methodHandle();
150
151 // Construct the new method
152 methodHandle new_method = methodOopDesc::clone_with_new_data(method(),
153 code_array(), code_length(),
154 compressed_line_number_table(),
155 compressed_line_number_table_size(),
156 CHECK_(methodHandle()));
157 set_method(new_method);
158
159 if (TraceRelocator) {
160 tty->print_cr("-------------------------------------------------");
161 tty->print_cr("new method");
162 _method->print_codes();
163 }
164
165 return new_method;
166 }
167
168
169 bool Relocator::handle_code_changes() {
170 assert(_changes != NULL, "changes vector must be initialized");
171
172 while (!_changes->is_empty()) {
173 // Inv: everything is aligned.
174 ChangeItem* ci = _changes->first();
175
176 if (TraceRelocator) {
177 ci->print();
178 }
179
180 // Execute operation
181 if (!ci->handle_code_change(this)) return false;
182
183 // Shuffel items up
184 for (int index = 1; index < _changes->length(); index++) {
185 _changes->at_put(index-1, _changes->at(index));
186 }
187 _changes->pop();
188 }
189 return true;
190 }
191
192
193 bool Relocator::is_opcode_lookupswitch(Bytecodes::Code bc) {
194 switch (bc) {
195 case Bytecodes::_tableswitch: return false;
196 case Bytecodes::_lookupswitch: // not rewritten on ia64
197 case Bytecodes::_fast_linearswitch: // rewritten _lookupswitch
198 case Bytecodes::_fast_binaryswitch: return true; // rewritten _lookupswitch
199 default: ShouldNotReachHere();
200 }
201 return true; // dummy
202 }
203
204 // We need a special instruction size method, since lookupswitches and tableswitches might not be
205 // properly alligned during relocation
206 int Relocator::rc_instr_len(int bci) {
207 Bytecodes::Code bc= code_at(bci);
208 switch (bc) {
209 // In the case of switch instructions, see if we have the original
210 // padding recorded.
211 case Bytecodes::_tableswitch:
212 case Bytecodes::_lookupswitch:
213 case Bytecodes::_fast_linearswitch:
214 case Bytecodes::_fast_binaryswitch:
215 {
216 int pad = get_orig_switch_pad(bci, is_opcode_lookupswitch(bc));
217 if (pad == -1) {
218 return instruction_length_at(bci);
219 }
220 // Otherwise, depends on the switch type.
221 switch (bc) {
222 case Bytecodes::_tableswitch: {
223 int lo = int_at(bci + 1 + pad + 4 * 1);
224 int hi = int_at(bci + 1 + pad + 4 * 2);
225 int n = hi - lo + 1;
226 return 1 + pad + 4*(3 + n);
227 }
228 case Bytecodes::_lookupswitch:
229 case Bytecodes::_fast_linearswitch:
230 case Bytecodes::_fast_binaryswitch: {
231 int npairs = int_at(bci + 1 + pad + 4 * 1);
232 return 1 + pad + 4*(2 + 2*npairs);
233 }
234 default:
235 ShouldNotReachHere();
236 }
237 }
238 }
239 return instruction_length_at(bci);
240 }
241
242 // If a change item is recorded for "pc", with type "ct", returns the
243 // associated padding, else -1.
244 int Relocator::get_orig_switch_pad(int bci, bool is_lookup_switch) {
245 for (int k = 0; k < _changes->length(); k++) {
246 ChangeItem* ci = _changes->at(k);
247 if (ci->is_switch_pad()) {
248 ChangeSwitchPad* csp = (ChangeSwitchPad*)ci;
249 if (csp->is_lookup_switch() == is_lookup_switch && csp->bci() == bci) {
250 return csp->padding();
251 }
252 }
253 }
254 return -1;
255 }
256
257
258 // Push a ChangeJumpWiden if it doesn't already exist on the work queue,
259 // otherwise adjust the item already there by delta. The calculation for
260 // new_delta is wrong for this because it uses the offset stored in the
261 // code stream itself which wasn't fixed when item was pushed on the work queue.
262 void Relocator::push_jump_widen(int bci, int delta, int new_delta) {
263 for (int j = 0; j < _changes->length(); j++) {
264 ChangeItem* ci = _changes->at(j);
265 if (ci->adjust(bci, delta)) return;
266 }
267 _changes->push(new ChangeJumpWiden(bci, new_delta));
268 }
269
270
271 // The current instruction of "c" is a jump; one of its offset starts
272 // at "offset" and is a short if "isShort" is "TRUE",
273 // and an integer otherwise. If the jump crosses "breakPC", change
274 // the span of the jump by "delta".
275 void Relocator::change_jump(int bci, int offset, bool is_short, int break_bci, int delta) {
276 int bci_delta = (is_short) ? short_at(offset) : int_at(offset);
277 int targ = bci + bci_delta;
278
279 if ((bci <= break_bci && targ > break_bci) ||
280 (bci > break_bci && targ <= break_bci)) {
281 int new_delta;
282 if (bci_delta > 0)
283 new_delta = bci_delta + delta;
284 else
285 new_delta = bci_delta - delta;
286
287 if (is_short && ((new_delta > MAX_SHORT) || new_delta < MIN_SHORT)) {
288 push_jump_widen(bci, delta, new_delta);
289 } else if (is_short) {
290 short_at_put(offset, new_delta);
291 } else {
292 int_at_put(offset, new_delta);
293 }
294 }
295 }
296
297
298 // Changes all jumps crossing "break_bci" by "delta". May enqueue things
299 // on "rc->changes"
300 void Relocator::change_jumps(int break_bci, int delta) {
301 int bci = 0;
302 Bytecodes::Code bc;
303 // Now, adjust any affected instructions.
304 while (bci < code_length()) {
305 switch (bc= code_at(bci)) {
306 case Bytecodes::_ifeq:
307 case Bytecodes::_ifne:
308 case Bytecodes::_iflt:
309 case Bytecodes::_ifge:
310 case Bytecodes::_ifgt:
311 case Bytecodes::_ifle:
312 case Bytecodes::_if_icmpeq:
313 case Bytecodes::_if_icmpne:
314 case Bytecodes::_if_icmplt:
315 case Bytecodes::_if_icmpge:
316 case Bytecodes::_if_icmpgt:
317 case Bytecodes::_if_icmple:
318 case Bytecodes::_if_acmpeq:
319 case Bytecodes::_if_acmpne:
320 case Bytecodes::_ifnull:
321 case Bytecodes::_ifnonnull:
322 case Bytecodes::_goto:
323 case Bytecodes::_jsr:
324 change_jump(bci, bci+1, true, break_bci, delta);
325 break;
326 case Bytecodes::_goto_w:
327 case Bytecodes::_jsr_w:
328 change_jump(bci, bci+1, false, break_bci, delta);
329 break;
330 case Bytecodes::_tableswitch:
331 case Bytecodes::_lookupswitch:
332 case Bytecodes::_fast_linearswitch:
333 case Bytecodes::_fast_binaryswitch: {
334 int recPad = get_orig_switch_pad(bci, (bc != Bytecodes::_tableswitch));
335 int oldPad = (recPad != -1) ? recPad : align(bci+1) - (bci+1);
336 if (bci > break_bci) {
337 int new_bci = bci + delta;
338 int newPad = align(new_bci+1) - (new_bci+1);
339 // Do we need to check the padding?
340 if (newPad != oldPad) {
341 if (recPad == -1) {
342 _changes->push(new ChangeSwitchPad(bci, oldPad, (bc != Bytecodes::_tableswitch)));
343 }
344 }
345 }
346
347 // Then the rest, which depend on the kind of switch.
348 switch (bc) {
349 case Bytecodes::_tableswitch: {
350 change_jump(bci, bci +1 + oldPad, false, break_bci, delta);
351 // We cannot use the Bytecode_tableswitch abstraction, since the padding might not be correct.
352 int lo = int_at(bci + 1 + oldPad + 4 * 1);
353 int hi = int_at(bci + 1 + oldPad + 4 * 2);
354 int n = hi - lo + 1;
355 for (int k = 0; k < n; k++) {
356 change_jump(bci, bci +1 + oldPad + 4*(k+3), false, break_bci, delta);
357 }
358 // Special next-bci calculation here...
359 bci += 1 + oldPad + (n+3)*4;
360 continue;
361 }
362 case Bytecodes::_lookupswitch:
363 case Bytecodes::_fast_linearswitch:
364 case Bytecodes::_fast_binaryswitch: {
365 change_jump(bci, bci +1 + oldPad, false, break_bci, delta);
366 // We cannot use the Bytecode_lookupswitch abstraction, since the padding might not be correct.
367 int npairs = int_at(bci + 1 + oldPad + 4 * 1);
368 for (int k = 0; k < npairs; k++) {
369 change_jump(bci, bci + 1 + oldPad + 4*(2 + 2*k + 1), false, break_bci, delta);
370 }
371 /* Special next-bci calculation here... */
372 bci += 1 + oldPad + (2 + (npairs*2))*4;
373 continue;
374 }
375 default:
376 ShouldNotReachHere();
377 }
378 }
379 default:
380 break;
381 }
382 bci += rc_instr_len(bci);
383 }
384 }
385
386 // The width of instruction at "pc" is changing by "delta". Adjust the
387 // exception table, if any, of "rc->mb".
388 void Relocator::adjust_exception_table(int bci, int delta) {
389 typeArrayOop table = method()->exception_table();
390 for (int index = 0; index < table->length(); index +=4) {
391 if (table->int_at(index) > bci) {
392 table->int_at_put(index+0, table->int_at(index+0) + delta);
393 table->int_at_put(index+1, table->int_at(index+1) + delta);
394 } else if (bci < table->int_at(index+1)) {
395 table->int_at_put(index+1, table->int_at(index+1) + delta);
396 }
397 if (table->int_at(index+2) > bci)
398 table->int_at_put(index+2, table->int_at(index+2) + delta);
399 }
400 }
401
402
403 // The width of instruction at "bci" is changing by "delta". Adjust the line number table.
404 void Relocator::adjust_line_no_table(int bci, int delta) {
405 if (method()->has_linenumber_table()) {
406 CompressedLineNumberReadStream reader(method()->compressed_linenumber_table());
407 CompressedLineNumberWriteStream writer(64); // plenty big for most line number tables
408 while (reader.read_pair()) {
409 int adjustment = (reader.bci() > bci) ? delta : 0;
410 writer.write_pair(reader.bci() + adjustment, reader.line());
411 }
412 writer.write_terminator();
413 set_compressed_line_number_table(writer.buffer());
414 set_compressed_line_number_table_size(writer.position());
415 }
416 }
417
418
419 // The width of instruction at "bci" is changing by "delta". Adjust the local variable table.
420 void Relocator::adjust_local_var_table(int bci, int delta) {
421 int localvariable_table_length = method()->localvariable_table_length();
422 if (localvariable_table_length > 0) {
423 LocalVariableTableElement* table = method()->localvariable_table_start();
424 for (int i = 0; i < localvariable_table_length; i++) {
425 u2 current_bci = table[i].start_bci;
426 if (current_bci > bci) {
427 table[i].start_bci = current_bci + delta;
428 } else {
429 u2 current_length = table[i].length;
430 if (current_bci + current_length > bci) {
431 table[i].length = current_length + delta;
432 }
433 }
434 }
435 }
436 }
437
438
439 bool Relocator::expand_code_array(int delta) {
440 int length = MAX2(code_length() + delta, code_length() * (100+code_slop_pct()) / 100);
441
442 if (length > MAX_METHOD_LENGTH) {
443 if (delta == 0 && code_length() <= MAX_METHOD_LENGTH) {
444 length = MAX_METHOD_LENGTH;
445 } else {
446 return false;
447 }
448 }
449
450 unsigned char* new_code_array = NEW_RESOURCE_ARRAY(unsigned char, length);
451 if (!new_code_array) return false;
452
453 // Expanding current array
454 if (code_array() != NULL) {
455 memcpy(new_code_array, code_array(), code_length());
456 } else {
457 // Initial copy. Copy directly from methodOop
458 memcpy(new_code_array, method()->code_base(), code_length());
459 }
460
461 set_code_array(new_code_array);
462 set_code_array_length(length);
463
464 return true;
465 }
466
467
468 // The instruction at "bci", whose size is "ilen", is changing size by
469 // "delta". Reallocate, move code, recalculate jumps, and enqueue
470 // change items as necessary.
471 bool Relocator::relocate_code(int bci, int ilen, int delta) {
472 int next_bci = bci + ilen;
473 if (delta > 0 && code_length() + delta > code_array_length()) {
474 // Expand allocated code space, if necessary.
475 if (!expand_code_array(delta)) {
476 return false;
477 }
478 }
479
480 // We require 4-byte alignment of code arrays.
481 assert(((intptr_t)code_array() & 3) == 0, "check code alignment");
482 // Change jumps before doing the copying; this routine requires aligned switches.
483 change_jumps(bci, delta);
484
485 // In case we have shrunken a tableswitch/lookupswitch statement, we store the last
486 // bytes that get overwritten. We have to copy the bytes after the change_jumps method
487 // has been called, since it is likly to update last offset in a tableswitch/lookupswitch
488 if (delta < 0) {
489 assert(delta>=-3, "we cannot overwrite more than 3 bytes");
490 memcpy(_overwrite, addr_at(bci + ilen + delta), -delta);
491 }
492
493 memmove(addr_at(next_bci + delta), addr_at(next_bci), code_length() - next_bci);
494 set_code_length(code_length() + delta);
495 // Also adjust exception tables...
496 adjust_exception_table(bci, delta);
497 // Line number tables...
498 adjust_line_no_table(bci, delta);
499 // And local variable table...
500 adjust_local_var_table(bci, delta);
501
502 // Relocate the pending change stack...
503 for (int j = 0; j < _changes->length(); j++) {
504 ChangeItem* ci = _changes->at(j);
505 ci->relocate(bci, delta);
506 }
507
508 // Notify any listeners about code relocation
509 notify(bci, delta, code_length());
510
511 return true;
512 }
513
514 // relocate a general instruction. Called by ChangeWiden class
515 bool Relocator::handle_widen(int bci, int new_ilen, u_char inst_buffer[]) {
516 int ilen = rc_instr_len(bci);
517 if (!relocate_code(bci, ilen, new_ilen - ilen))
518 return false;
519
520 // Insert new bytecode(s)
521 for(int k = 0; k < new_ilen; k++) {
522 code_at_put(bci + k, (Bytecodes::Code)inst_buffer[k]);
523 }
524
525 return true;
526 }
527
528 // handle jump_widen instruction. Called be ChangeJumpWiden class
529 bool Relocator::handle_jump_widen(int bci, int delta) {
530 int ilen = rc_instr_len(bci);
531
532 Bytecodes::Code bc = code_at(bci);
533 switch (bc) {
534 case Bytecodes::_ifeq:
535 case Bytecodes::_ifne:
536 case Bytecodes::_iflt:
537 case Bytecodes::_ifge:
538 case Bytecodes::_ifgt:
539 case Bytecodes::_ifle:
540 case Bytecodes::_if_icmpeq:
541 case Bytecodes::_if_icmpne:
542 case Bytecodes::_if_icmplt:
543 case Bytecodes::_if_icmpge:
544 case Bytecodes::_if_icmpgt:
545 case Bytecodes::_if_icmple:
546 case Bytecodes::_if_acmpeq:
547 case Bytecodes::_if_acmpne:
548 case Bytecodes::_ifnull:
549 case Bytecodes::_ifnonnull: {
550 const int goto_length = Bytecodes::length_for(Bytecodes::_goto);
551
552 // If 'if' points to the next bytecode after goto, it's already handled.
553 // it shouldn't be.
554 assert (short_at(bci+1) != ilen+goto_length, "if relocation already handled");
555 assert(ilen == 3, "check length");
556
557 // Convert to 0 if <cond> goto 6
558 // 3 _goto 11
559 // 6 _goto_w <wide delta offset>
560 // 11 <else code>
561 const int goto_w_length = Bytecodes::length_for(Bytecodes::_goto_w);
562 const int add_bci = goto_length + goto_w_length;
563
564 if (!relocate_code(bci, 3, /*delta*/add_bci)) return false;
565
566 // if bytecode points to goto_w instruction
567 short_at_put(bci + 1, ilen + goto_length);
568
569 int cbci = bci + ilen;
570 // goto around
571 code_at_put(cbci, Bytecodes::_goto);
572 short_at_put(cbci + 1, add_bci);
573 // goto_w <wide delta>
574 cbci = cbci + goto_length;
575 code_at_put(cbci, Bytecodes::_goto_w);
576 if (delta > 0) {
577 delta += 2; // goto_w is 2 bytes more than "if" code
578 } else {
579 delta -= ilen+goto_length; // branch starts at goto_w offset
580 }
581 int_at_put(cbci + 1, delta);
582 break;
583
584 }
585 case Bytecodes::_goto:
586 case Bytecodes::_jsr:
587 assert(ilen == 3, "check length");
588
589 if (!relocate_code(bci, 3, 2)) return false;
590 if (bc == Bytecodes::_goto)
591 code_at_put(bci, Bytecodes::_goto_w);
592 else
593 code_at_put(bci, Bytecodes::_jsr_w);
594
595 // If it's a forward jump, add 2 for the widening.
596 if (delta > 0) delta += 2;
597 int_at_put(bci + 1, delta);
598 break;
599
600 default: ShouldNotReachHere();
601 }
602
603 return true;
604 }
605
606 // handle lookup/table switch instructions. Called be ChangeSwitchPad class
607 bool Relocator::handle_switch_pad(int bci, int old_pad, bool is_lookup_switch) {
608 int ilen = rc_instr_len(bci);
609 int new_pad = align(bci+1) - (bci+1);
610 int pad_delta = new_pad - old_pad;
611 if (pad_delta != 0) {
612 int len;
613 if (!is_lookup_switch) {
614 int low = int_at(bci+1+old_pad+4);
615 int high = int_at(bci+1+old_pad+8);
616 len = high-low+1 + 3; // 3 for default, hi, lo.
617 } else {
618 int npairs = int_at(bci+1+old_pad+4);
619 len = npairs*2 + 2; // 2 for default, npairs.
620 }
621 // Because "relocateCode" does a "changeJumps" loop,
622 // which parses instructions to determine their length,
623 // we need to call that before messing with the current
624 // instruction. Since it may also overwrite the current
625 // instruction when moving down, remember the possibly
626 // overwritten part.
627
628 // Move the code following the instruction...
629 if (!relocate_code(bci, ilen, pad_delta)) return false;
630
631 if (pad_delta < 0) {
632 // Move the shrunken instruction down.
633 memmove(addr_at(bci + 1 + new_pad),
634 addr_at(bci + 1 + old_pad),
635 len * 4 + pad_delta);
636 memmove(addr_at(bci + 1 + new_pad + len*4 + pad_delta),
637 _overwrite, -pad_delta);
638 } else {
639 assert(pad_delta > 0, "check");
640 // Move the expanded instruction up.
641 memmove(addr_at(bci +1 + new_pad),
642 addr_at(bci +1 + old_pad),
643 len * 4);
644 }
645 }
646 return true;
647 }