1 /*
2 * Copyright (c) 1997, 2005, 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 "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 // Create a new array, copying the src array but adding a hole at
439 // the specified location
440 static typeArrayOop insert_hole_at(
441 size_t where, int hole_sz, typeArrayOop src) {
442 Thread* THREAD = Thread::current();
443 Handle src_hnd(THREAD, src);
444 typeArrayOop dst =
445 oopFactory::new_permanent_byteArray(src->length() + hole_sz, CHECK_NULL);
446 src = (typeArrayOop)src_hnd();
447
448 address src_addr = (address)src->byte_at_addr(0);
449 address dst_addr = (address)dst->byte_at_addr(0);
450
451 memcpy(dst_addr, src_addr, where);
452 memcpy(dst_addr + where + hole_sz,
453 src_addr + where, src->length() - where);
454 return dst;
455 }
456
457 // The width of instruction at "bci" is changing by "delta". Adjust the stack
458 // map frames.
459 void Relocator::adjust_stack_map_table(int bci, int delta) {
460 if (method()->has_stackmap_table()) {
461 typeArrayOop data = method()->stackmap_data();
462 // The data in the array is a classfile representation of the stackmap
463 // table attribute, less the initial u2 tag and u4 attribute_length fields.
464 stack_map_table_attribute* attr = stack_map_table_attribute::at(
465 (address)data->byte_at_addr(0) - (sizeof(u2) + sizeof(u4)));
466
467 int count = attr->number_of_entries();
468 stack_map_frame* frame = attr->entries();
469 int bci_iter = -1;
470 bool offset_adjusted = false; // only need to adjust one offset
471
472 for (int i = 0; i < count; ++i) {
473 int offset_delta = frame->offset_delta();
474 bci_iter += offset_delta;
475
476 if (!offset_adjusted && bci_iter > bci) {
477 int new_offset_delta = offset_delta + delta;
478
479 if (frame->is_valid_offset(new_offset_delta)) {
480 frame->set_offset_delta(new_offset_delta);
481 } else {
482 assert(frame->is_same_frame() ||
483 frame->is_same_frame_1_stack_item_frame(),
484 "Frame must be one of the compressed forms");
485 // The new delta exceeds the capacity of the 'same_frame' or
486 // 'same_frame_1_stack_item_frame' frame types. We need to
487 // convert these frames to the extended versions, but the extended
488 // version is bigger and requires more room. So we allocate a
489 // new array and copy the data, being sure to leave u2-sized hole
490 // right after the 'frame_type' for the new offset field.
491 //
492 // We can safely ignore the reverse situation as a small delta
493 // can still be used in an extended version of the frame.
494
495 size_t frame_offset = (address)frame - (address)data->byte_at_addr(0);
496
497 data = insert_hole_at(frame_offset + 1, 2, data);
498 if (data == NULL) {
499 return; // out-of-memory?
500 }
501
502 address frame_addr = (address)(data->byte_at_addr(0) + frame_offset);
503 frame = stack_map_frame::at(frame_addr);
504
505
506 // Now convert the frames in place
507 if (frame->is_same_frame()) {
508 same_frame_extended::create_at(frame_addr, new_offset_delta);
509 } else {
510 same_frame_1_stack_item_extended::create_at(
511 frame_addr, new_offset_delta, NULL);
512 // the verification_info_type should already be at the right spot
513 }
514 }
515 offset_adjusted = true; // needs to be done only once, since subsequent
516 // values are offsets from the current
517 }
518
519 // The stack map frame may contain verification types, if so we need to
520 // check and update any Uninitialized type's bci (no matter where it is).
521 int number_of_types = frame->number_of_types();
522 verification_type_info* types = frame->types();
523
524 for (int i = 0; i < number_of_types; ++i) {
525 if (types->is_uninitialized() && types->bci() > bci) {
526 types->set_bci(types->bci() + delta);
527 }
528 types = types->next();
529 }
530
531 // Full frame has stack values too
532 full_frame* ff = frame->as_full_frame();
533 if (ff != NULL) {
534 address eol = (address)types;
535 number_of_types = ff->stack_slots(eol);
536 types = ff->stack(eol);
537 for (int i = 0; i < number_of_types; ++i) {
538 if (types->is_uninitialized() && types->bci() > bci) {
539 types->set_bci(types->bci() + delta);
540 }
541 types = types->next();
542 }
543 }
544
545 frame = frame->next();
546 }
547
548 method()->set_stackmap_data(data); // in case it has changed
549 }
550 }
551
552
553 bool Relocator::expand_code_array(int delta) {
554 int length = MAX2(code_length() + delta, code_length() * (100+code_slop_pct()) / 100);
555
556 if (length > MAX_METHOD_LENGTH) {
557 if (delta == 0 && code_length() <= MAX_METHOD_LENGTH) {
558 length = MAX_METHOD_LENGTH;
559 } else {
560 return false;
561 }
562 }
563
564 unsigned char* new_code_array = NEW_RESOURCE_ARRAY(unsigned char, length);
565 if (!new_code_array) return false;
566
567 // Expanding current array
568 if (code_array() != NULL) {
569 memcpy(new_code_array, code_array(), code_length());
570 } else {
571 // Initial copy. Copy directly from methodOop
572 memcpy(new_code_array, method()->code_base(), code_length());
573 }
574
575 set_code_array(new_code_array);
576 set_code_array_length(length);
577
578 return true;
579 }
580
581
582 // The instruction at "bci", whose size is "ilen", is changing size by
583 // "delta". Reallocate, move code, recalculate jumps, and enqueue
584 // change items as necessary.
585 bool Relocator::relocate_code(int bci, int ilen, int delta) {
586 int next_bci = bci + ilen;
587 if (delta > 0 && code_length() + delta > code_array_length()) {
588 // Expand allocated code space, if necessary.
589 if (!expand_code_array(delta)) {
590 return false;
591 }
592 }
593
594 // We require 4-byte alignment of code arrays.
595 assert(((intptr_t)code_array() & 3) == 0, "check code alignment");
596 // Change jumps before doing the copying; this routine requires aligned switches.
597 change_jumps(bci, delta);
598
599 // In case we have shrunken a tableswitch/lookupswitch statement, we store the last
600 // bytes that get overwritten. We have to copy the bytes after the change_jumps method
601 // has been called, since it is likly to update last offset in a tableswitch/lookupswitch
602 if (delta < 0) {
603 assert(delta>=-3, "we cannot overwrite more than 3 bytes");
604 memcpy(_overwrite, addr_at(bci + ilen + delta), -delta);
605 }
606
607 memmove(addr_at(next_bci + delta), addr_at(next_bci), code_length() - next_bci);
608 set_code_length(code_length() + delta);
609 // Also adjust exception tables...
610 adjust_exception_table(bci, delta);
611 // Line number tables...
612 adjust_line_no_table(bci, delta);
613 // And local variable table...
614 adjust_local_var_table(bci, delta);
615
616 // Adjust stack maps
617 adjust_stack_map_table(bci, delta);
618
619 // Relocate the pending change stack...
620 for (int j = 0; j < _changes->length(); j++) {
621 ChangeItem* ci = _changes->at(j);
622 ci->relocate(bci, delta);
623 }
624
625 // Notify any listeners about code relocation
626 notify(bci, delta, code_length());
627
628 return true;
629 }
630
631 // relocate a general instruction. Called by ChangeWiden class
632 bool Relocator::handle_widen(int bci, int new_ilen, u_char inst_buffer[]) {
633 int ilen = rc_instr_len(bci);
634 if (!relocate_code(bci, ilen, new_ilen - ilen))
635 return false;
636
637 // Insert new bytecode(s)
638 for(int k = 0; k < new_ilen; k++) {
639 code_at_put(bci + k, (Bytecodes::Code)inst_buffer[k]);
640 }
641
642 return true;
643 }
644
645 // handle jump_widen instruction. Called be ChangeJumpWiden class
646 bool Relocator::handle_jump_widen(int bci, int delta) {
647 int ilen = rc_instr_len(bci);
648
649 Bytecodes::Code bc = code_at(bci);
650 switch (bc) {
651 case Bytecodes::_ifeq:
652 case Bytecodes::_ifne:
653 case Bytecodes::_iflt:
654 case Bytecodes::_ifge:
655 case Bytecodes::_ifgt:
656 case Bytecodes::_ifle:
657 case Bytecodes::_if_icmpeq:
658 case Bytecodes::_if_icmpne:
659 case Bytecodes::_if_icmplt:
660 case Bytecodes::_if_icmpge:
661 case Bytecodes::_if_icmpgt:
662 case Bytecodes::_if_icmple:
663 case Bytecodes::_if_acmpeq:
664 case Bytecodes::_if_acmpne:
665 case Bytecodes::_ifnull:
666 case Bytecodes::_ifnonnull: {
667 const int goto_length = Bytecodes::length_for(Bytecodes::_goto);
668
669 // If 'if' points to the next bytecode after goto, it's already handled.
670 // it shouldn't be.
671 assert (short_at(bci+1) != ilen+goto_length, "if relocation already handled");
672 assert(ilen == 3, "check length");
673
674 // Convert to 0 if <cond> goto 6
675 // 3 _goto 11
676 // 6 _goto_w <wide delta offset>
677 // 11 <else code>
678 const int goto_w_length = Bytecodes::length_for(Bytecodes::_goto_w);
679 const int add_bci = goto_length + goto_w_length;
680
681 if (!relocate_code(bci, 3, /*delta*/add_bci)) return false;
682
683 // if bytecode points to goto_w instruction
684 short_at_put(bci + 1, ilen + goto_length);
685
686 int cbci = bci + ilen;
687 // goto around
688 code_at_put(cbci, Bytecodes::_goto);
689 short_at_put(cbci + 1, add_bci);
690 // goto_w <wide delta>
691 cbci = cbci + goto_length;
692 code_at_put(cbci, Bytecodes::_goto_w);
693 if (delta > 0) {
694 delta += 2; // goto_w is 2 bytes more than "if" code
695 } else {
696 delta -= ilen+goto_length; // branch starts at goto_w offset
697 }
698 int_at_put(cbci + 1, delta);
699 break;
700
701 }
702 case Bytecodes::_goto:
703 case Bytecodes::_jsr:
704 assert(ilen == 3, "check length");
705
706 if (!relocate_code(bci, 3, 2)) return false;
707 if (bc == Bytecodes::_goto)
708 code_at_put(bci, Bytecodes::_goto_w);
709 else
710 code_at_put(bci, Bytecodes::_jsr_w);
711
712 // If it's a forward jump, add 2 for the widening.
713 if (delta > 0) delta += 2;
714 int_at_put(bci + 1, delta);
715 break;
716
717 default: ShouldNotReachHere();
718 }
719
720 return true;
721 }
722
723 // handle lookup/table switch instructions. Called be ChangeSwitchPad class
724 bool Relocator::handle_switch_pad(int bci, int old_pad, bool is_lookup_switch) {
725 int ilen = rc_instr_len(bci);
726 int new_pad = align(bci+1) - (bci+1);
727 int pad_delta = new_pad - old_pad;
728 if (pad_delta != 0) {
729 int len;
730 if (!is_lookup_switch) {
731 int low = int_at(bci+1+old_pad+4);
732 int high = int_at(bci+1+old_pad+8);
733 len = high-low+1 + 3; // 3 for default, hi, lo.
734 } else {
735 int npairs = int_at(bci+1+old_pad+4);
736 len = npairs*2 + 2; // 2 for default, npairs.
737 }
738 // Because "relocateCode" does a "changeJumps" loop,
739 // which parses instructions to determine their length,
740 // we need to call that before messing with the current
741 // instruction. Since it may also overwrite the current
742 // instruction when moving down, remember the possibly
743 // overwritten part.
744
745 // Move the code following the instruction...
746 if (!relocate_code(bci, ilen, pad_delta)) return false;
747
748 if (pad_delta < 0) {
749 // Move the shrunken instruction down.
750 memmove(addr_at(bci + 1 + new_pad),
751 addr_at(bci + 1 + old_pad),
752 len * 4 + pad_delta);
753 memmove(addr_at(bci + 1 + new_pad + len*4 + pad_delta),
754 _overwrite, -pad_delta);
755 } else {
756 assert(pad_delta > 0, "check");
757 // Move the expanded instruction up.
758 memmove(addr_at(bci +1 + new_pad),
759 addr_at(bci +1 + old_pad),
760 len * 4);
761 memset(addr_at(bci + 1), 0, new_pad); // pad must be 0
762 }
763 }
764 return true;
765 }