1/*
2 * Copyright (c) 1997, 2018, 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 "precompiled.hpp"
26#include "classfile/stackMapTableFormat.hpp"
27#include "interpreter/bytecodes.hpp"
28#include "memory/metadataFactory.hpp"
29#include "memory/oopFactory.hpp"
30#include "oops/method.inline.hpp"
31#include "oops/oop.inline.hpp"
32#include "runtime/handles.inline.hpp"
33#include "runtime/relocator.hpp"
34
35#define MAX_METHOD_LENGTH 65535
36
37#define MAX_SHORT ((1 << 15) - 1)
38#define MIN_SHORT (- (1 << 15))
39
40// Encapsulates a code change request. There are 3 types.
41// General instruction, jump instruction, and table/lookup switches
42//
43class ChangeItem : public ResourceObj {
44 int _bci;
45 public:
46 ChangeItem(int bci) { _bci = bci; }
47 virtual bool handle_code_change(Relocator *r) = 0;
48
49 // type info
50 virtual bool is_widen() { return false; }
51 virtual bool is_jump_widen() { return false; }
52 virtual bool is_switch_pad() { return false; }
53
54 // accessors
55 int bci() { return _bci; }
56 void relocate(int break_bci, int delta) { if (_bci > break_bci) { _bci += delta; } }
57
58 virtual bool adjust(int bci, int delta) { return false; }
59
60 // debug
61 virtual void print() = 0;
62};
63
64class ChangeWiden : public ChangeItem {
65 int _new_ilen; // New length of instruction at bci
66 u_char* _inst_buffer; // New bytecodes
67 public:
68 ChangeWiden(int bci, int new_ilen, u_char* inst_buffer) : ChangeItem(bci) {
69 _new_ilen = new_ilen;
70 _inst_buffer = inst_buffer;
71 }
72
73 // Callback to do instruction
74 bool handle_code_change(Relocator *r) { return r->handle_widen(bci(), _new_ilen, _inst_buffer); };
75
76 bool is_widen() { return true; }
77
78 void print() { tty->print_cr("ChangeWiden. bci: %d New_ilen: %d", bci(), _new_ilen); }
79};
80
81class ChangeJumpWiden : public ChangeItem {
82 int _delta; // New length of instruction at bci
83 public:
84 ChangeJumpWiden(int bci, int delta) : ChangeItem(bci) { _delta = delta; }
85
86 // Callback to do instruction
87 bool handle_code_change(Relocator *r) { return r->handle_jump_widen(bci(), _delta); };
88
89 bool is_jump_widen() { return true; }
90
91 // If the bci matches, adjust the delta in the change jump request.
92 bool adjust(int jump_bci, int delta) {
93 if (bci() == jump_bci) {
94 if (_delta > 0)
95 _delta += delta;
96 else
97 _delta -= delta;
98 return true;
99 }
100 return false;
101 }
102
103 void print() { tty->print_cr("ChangeJumpWiden. bci: %d Delta: %d", bci(), _delta); }
104};
105
106class ChangeSwitchPad : public ChangeItem {
107 int _padding;
108 bool _is_lookup_switch;
109 public:
110 ChangeSwitchPad(int bci, int padding, bool is_lookup_switch) : ChangeItem(bci) {
111 _padding = padding;
112 _is_lookup_switch = is_lookup_switch;
113 }
114
115 // Callback to do instruction
116 bool handle_code_change(Relocator *r) { return r->handle_switch_pad(bci(), _padding, _is_lookup_switch); };
117
118 bool is_switch_pad() { return true; }
119 int padding() { return _padding; }
120 bool is_lookup_switch() { return _is_lookup_switch; }
121
122 void print() { tty->print_cr("ChangeSwitchPad. bci: %d Padding: %d IsLookupSwitch: %d", bci(), _padding, _is_lookup_switch); }
123};
124
125//-----------------------------------------------------------------------------------------------------------
126// Relocator code
127
128Relocator::Relocator(const methodHandle& m, RelocatorListener* listener) {
129 set_method(m);
130 set_code_length(method()->code_size());
131 set_code_array(NULL);
132 // Allocate code array and copy bytecodes
133 if (!expand_code_array(0)) {
134 // Should have at least MAX_METHOD_LENGTH available or the verifier
135 // would have failed.
136 ShouldNotReachHere();
137 }
138 set_compressed_line_number_table(NULL);
139 set_compressed_line_number_table_size(0);
140 _listener = listener;
141}
142
143// size is the new size of the instruction at bci. Hence, if size is less than the current
144// instruction size, we will shrink the code.
145methodHandle Relocator::insert_space_at(int bci, int size, u_char inst_buffer[], TRAPS) {
146 _changes = new GrowableArray<ChangeItem*> (10);
147 _changes->push(new ChangeWiden(bci, size, inst_buffer));
148
149 if (TraceRelocator) {
150 tty->print_cr("Space at: %d Size: %d", bci, size);
151 _method->print();
152 _method->print_codes();
153 tty->print_cr("-------------------------------------------------");
154 }
155
156 if (!handle_code_changes()) return methodHandle();
157
158 // Construct the new method
159 methodHandle new_method = Method::clone_with_new_data(method(),
160 code_array(), code_length(),
161 compressed_line_number_table(),
162 compressed_line_number_table_size(),
163 CHECK_(methodHandle()));
164
165 // Deallocate the old Method* from metadata
166 ClassLoaderData* loader_data = method()->method_holder()->class_loader_data();
167 loader_data->add_to_deallocate_list(method()());
168
169 set_method(new_method);
170
171 if (TraceRelocator) {
172 tty->print_cr("-------------------------------------------------");
173 tty->print_cr("new method");
174 _method->print_codes();
175 }
176
177 return new_method;
178}
179
180
181bool Relocator::handle_code_changes() {
182 assert(_changes != NULL, "changes vector must be initialized");
183
184 while (!_changes->is_empty()) {
185 // Inv: everything is aligned.
186 ChangeItem* ci = _changes->first();
187
188 if (TraceRelocator) {
189 ci->print();
190 }
191
192 // Execute operation
193 if (!ci->handle_code_change(this)) return false;
194
195 // Shuffle items up
196 for (int index = 1; index < _changes->length(); index++) {
197 _changes->at_put(index-1, _changes->at(index));
198 }
199 _changes->pop();
200 }
201 return true;
202}
203
204
205bool Relocator::is_opcode_lookupswitch(Bytecodes::Code bc) {
206 switch (bc) {
207 case Bytecodes::_tableswitch: return false;
208 case Bytecodes::_lookupswitch: // not rewritten on ia64
209 case Bytecodes::_fast_linearswitch: // rewritten _lookupswitch
210 case Bytecodes::_fast_binaryswitch: return true; // rewritten _lookupswitch
211 default: ShouldNotReachHere();
212 }
213 return true; // dummy
214}
215
216// We need a special instruction size method, since lookupswitches and tableswitches might not be
217// properly aligned during relocation
218int Relocator::rc_instr_len(int bci) {
219 Bytecodes::Code bc= code_at(bci);
220 switch (bc) {
221 // In the case of switch instructions, see if we have the original
222 // padding recorded.
223 case Bytecodes::_tableswitch:
224 case Bytecodes::_lookupswitch:
225 case Bytecodes::_fast_linearswitch:
226 case Bytecodes::_fast_binaryswitch:
227 {
228 int pad = get_orig_switch_pad(bci, is_opcode_lookupswitch(bc));
229 if (pad == -1) {
230 return instruction_length_at(bci);
231 }
232 // Otherwise, depends on the switch type.
233 switch (bc) {
234 case Bytecodes::_tableswitch: {
235 int lo = int_at(bci + 1 + pad + 4 * 1);
236 int hi = int_at(bci + 1 + pad + 4 * 2);
237 int n = hi - lo + 1;
238 return 1 + pad + 4*(3 + n);
239 }
240 case Bytecodes::_lookupswitch:
241 case Bytecodes::_fast_linearswitch:
242 case Bytecodes::_fast_binaryswitch: {
243 int npairs = int_at(bci + 1 + pad + 4 * 1);
244 return 1 + pad + 4*(2 + 2*npairs);
245 }
246 default:
247 ShouldNotReachHere();
248 }
249 }
250 default:
251 break;
252 }
253 return instruction_length_at(bci);
254}
255
256// If a change item is recorded for "pc", with type "ct", returns the
257// associated padding, else -1.
258int Relocator::get_orig_switch_pad(int bci, bool is_lookup_switch) {
259 for (int k = 0; k < _changes->length(); k++) {
260 ChangeItem* ci = _changes->at(k);
261 if (ci->is_switch_pad()) {
262 ChangeSwitchPad* csp = (ChangeSwitchPad*)ci;
263 if (csp->is_lookup_switch() == is_lookup_switch && csp->bci() == bci) {
264 return csp->padding();
265 }
266 }
267 }
268 return -1;
269}
270
271
272// Push a ChangeJumpWiden if it doesn't already exist on the work queue,
273// otherwise adjust the item already there by delta. The calculation for
274// new_delta is wrong for this because it uses the offset stored in the
275// code stream itself which wasn't fixed when item was pushed on the work queue.
276void Relocator::push_jump_widen(int bci, int delta, int new_delta) {
277 for (int j = 0; j < _changes->length(); j++) {
278 ChangeItem* ci = _changes->at(j);
279 if (ci->adjust(bci, delta)) return;
280 }
281 _changes->push(new ChangeJumpWiden(bci, new_delta));
282}
283
284
285// The current instruction of "c" is a jump; one of its offset starts
286// at "offset" and is a short if "isShort" is "TRUE",
287// and an integer otherwise. If the jump crosses "breakPC", change
288// the span of the jump by "delta".
289void Relocator::change_jump(int bci, int offset, bool is_short, int break_bci, int delta) {
290 int bci_delta = (is_short) ? short_at(offset) : int_at(offset);
291 int targ = bci + bci_delta;
292
293 if ((bci <= break_bci && targ > break_bci) ||
294 (bci > break_bci && targ <= break_bci)) {
295 int new_delta;
296 if (bci_delta > 0)
297 new_delta = bci_delta + delta;
298 else
299 new_delta = bci_delta - delta;
300
301 if (is_short && ((new_delta > MAX_SHORT) || new_delta < MIN_SHORT)) {
302 push_jump_widen(bci, delta, new_delta);
303 } else if (is_short) {
304 short_at_put(offset, new_delta);
305 } else {
306 int_at_put(offset, new_delta);
307 }
308 }
309}
310
311
312// Changes all jumps crossing "break_bci" by "delta". May enqueue things
313// on "rc->changes"
314void Relocator::change_jumps(int break_bci, int delta) {
315 int bci = 0;
316 Bytecodes::Code bc;
317 // Now, adjust any affected instructions.
318 while (bci < code_length()) {
319 switch (bc= code_at(bci)) {
320 case Bytecodes::_ifeq:
321 case Bytecodes::_ifne:
322 case Bytecodes::_iflt:
323 case Bytecodes::_ifge:
324 case Bytecodes::_ifgt:
325 case Bytecodes::_ifle:
326 case Bytecodes::_if_icmpeq:
327 case Bytecodes::_if_icmpne:
328 case Bytecodes::_if_icmplt:
329 case Bytecodes::_if_icmpge:
330 case Bytecodes::_if_icmpgt:
331 case Bytecodes::_if_icmple:
332 case Bytecodes::_if_acmpeq:
333 case Bytecodes::_if_acmpne:
334 case Bytecodes::_ifnull:
335 case Bytecodes::_ifnonnull:
336 case Bytecodes::_goto:
337 case Bytecodes::_jsr:
338 change_jump(bci, bci+1, true, break_bci, delta);
339 break;
340 case Bytecodes::_goto_w:
341 case Bytecodes::_jsr_w:
342 change_jump(bci, bci+1, false, break_bci, delta);
343 break;
344 case Bytecodes::_tableswitch:
345 case Bytecodes::_lookupswitch:
346 case Bytecodes::_fast_linearswitch:
347 case Bytecodes::_fast_binaryswitch: {
348 int recPad = get_orig_switch_pad(bci, (bc != Bytecodes::_tableswitch));
349 int oldPad = (recPad != -1) ? recPad : align(bci+1) - (bci+1);
350 if (bci > break_bci) {
351 int new_bci = bci + delta;
352 int newPad = align(new_bci+1) - (new_bci+1);
353 // Do we need to check the padding?
354 if (newPad != oldPad) {
355 if (recPad == -1) {
356 _changes->push(new ChangeSwitchPad(bci, oldPad, (bc != Bytecodes::_tableswitch)));
357 }
358 }
359 }
360
361 // Then the rest, which depend on the kind of switch.
362 switch (bc) {
363 case Bytecodes::_tableswitch: {
364 change_jump(bci, bci +1 + oldPad, false, break_bci, delta);
365 // We cannot use the Bytecode_tableswitch abstraction, since the padding might not be correct.
366 int lo = int_at(bci + 1 + oldPad + 4 * 1);
367 int hi = int_at(bci + 1 + oldPad + 4 * 2);
368 int n = hi - lo + 1;
369 for (int k = 0; k < n; k++) {
370 change_jump(bci, bci +1 + oldPad + 4*(k+3), false, break_bci, delta);
371 }
372 // Special next-bci calculation here...
373 bci += 1 + oldPad + (n+3)*4;
374 continue;
375 }
376 case Bytecodes::_lookupswitch:
377 case Bytecodes::_fast_linearswitch:
378 case Bytecodes::_fast_binaryswitch: {
379 change_jump(bci, bci +1 + oldPad, false, break_bci, delta);
380 // We cannot use the Bytecode_lookupswitch abstraction, since the padding might not be correct.
381 int npairs = int_at(bci + 1 + oldPad + 4 * 1);
382 for (int k = 0; k < npairs; k++) {
383 change_jump(bci, bci + 1 + oldPad + 4*(2 + 2*k + 1), false, break_bci, delta);
384 }
385 /* Special next-bci calculation here... */
386 bci += 1 + oldPad + (2 + (npairs*2))*4;
387 continue;
388 }
389 default:
390 ShouldNotReachHere();
391 }
392 }
393 default:
394 break;
395 }
396 bci += rc_instr_len(bci);
397 }
398}
399
400// The width of instruction at "pc" is changing by "delta". Adjust the
401// exception table, if any, of "rc->mb".
402void Relocator::adjust_exception_table(int bci, int delta) {
403 ExceptionTable table(_method());
404 for (int index = 0; index < table.length(); index ++) {
405 if (table.start_pc(index) > bci) {
406 table.set_start_pc(index, table.start_pc(index) + delta);
407 table.set_end_pc(index, table.end_pc(index) + delta);
408 } else if (bci < table.end_pc(index)) {
409 table.set_end_pc(index, table.end_pc(index) + delta);
410 }
411 if (table.handler_pc(index) > bci)
412 table.set_handler_pc(index, table.handler_pc(index) + delta);
413 }
414}
415
416
417// The width of instruction at "bci" is changing by "delta". Adjust the line number table.
418void Relocator::adjust_line_no_table(int bci, int delta) {
419 if (method()->has_linenumber_table()) {
420 CompressedLineNumberReadStream reader(method()->compressed_linenumber_table());
421 CompressedLineNumberWriteStream writer(64); // plenty big for most line number tables
422 while (reader.read_pair()) {
423 int adjustment = (reader.bci() > bci) ? delta : 0;
424 writer.write_pair(reader.bci() + adjustment, reader.line());
425 }
426 writer.write_terminator();
427 set_compressed_line_number_table(writer.buffer());
428 set_compressed_line_number_table_size(writer.position());
429 }
430}
431
432
433// The width of instruction at "bci" is changing by "delta". Adjust the local variable table.
434void Relocator::adjust_local_var_table(int bci, int delta) {
435 int localvariable_table_length = method()->localvariable_table_length();
436 if (localvariable_table_length > 0) {
437 LocalVariableTableElement* table = method()->localvariable_table_start();
438 for (int i = 0; i < localvariable_table_length; i++) {
439 u2 current_bci = table[i].start_bci;
440 if (current_bci > bci) {
441 table[i].start_bci = current_bci + delta;
442 } else {
443 u2 current_length = table[i].length;
444 if (current_bci + current_length > bci) {
445 table[i].length = current_length + delta;
446 }
447 }
448 }
449 }
450}
451
452// Create a new array, copying the src array but adding a hole at
453// the specified location
454static Array<u1>* insert_hole_at(ClassLoaderData* loader_data,
455 size_t where, int hole_sz, Array<u1>* src) {
456 Thread* THREAD = Thread::current();
457 Array<u1>* dst =
458 MetadataFactory::new_array<u1>(loader_data, src->length() + hole_sz, 0, CHECK_NULL);
459
460 address src_addr = (address)src->adr_at(0);
461 address dst_addr = (address)dst->adr_at(0);
462
463 memcpy(dst_addr, src_addr, where);
464 memcpy(dst_addr + where + hole_sz,
465 src_addr + where, src->length() - where);
466 return dst;
467}
468
469// The width of instruction at "bci" is changing by "delta". Adjust the stack
470// map frames.
471void Relocator::adjust_stack_map_table(int bci, int delta) {
472 if (method()->has_stackmap_table()) {
473 Array<u1>* data = method()->stackmap_data();
474 // The data in the array is a classfile representation of the stackmap table
475 stack_map_table* sm_table =
476 stack_map_table::at((address)data->adr_at(0));
477
478 int count = sm_table->number_of_entries();
479 stack_map_frame* frame = sm_table->entries();
480 int bci_iter = -1;
481 bool offset_adjusted = false; // only need to adjust one offset
482
483 for (int i = 0; i < count; ++i) {
484 int offset_delta = frame->offset_delta();
485 bci_iter += offset_delta;
486
487 if (!offset_adjusted && bci_iter > bci) {
488 int new_offset_delta = offset_delta + delta;
489
490 if (frame->is_valid_offset(new_offset_delta)) {
491 frame->set_offset_delta(new_offset_delta);
492 } else {
493 assert(frame->is_same_frame() ||
494 frame->is_same_locals_1_stack_item_frame(),
495 "Frame must be one of the compressed forms");
496 // The new delta exceeds the capacity of the 'same_frame' or
497 // 'same_frame_1_stack_item_frame' frame types. We need to
498 // convert these frames to the extended versions, but the extended
499 // version is bigger and requires more room. So we allocate a
500 // new array and copy the data, being sure to leave u2-sized hole
501 // right after the 'frame_type' for the new offset field.
502 //
503 // We can safely ignore the reverse situation as a small delta
504 // can still be used in an extended version of the frame.
505
506 size_t frame_offset = (address)frame - (address)data->adr_at(0);
507
508 ClassLoaderData* loader_data = method()->method_holder()->class_loader_data();
509 Array<u1>* new_data = insert_hole_at(loader_data, frame_offset + 1, 2, data);
510 if (new_data == NULL) {
511 return; // out-of-memory?
512 }
513 // Deallocate old data
514 MetadataFactory::free_array<u1>(loader_data, data);
515 data = new_data;
516
517 address frame_addr = (address)(data->adr_at(0) + frame_offset);
518 frame = stack_map_frame::at(frame_addr);
519
520
521 // Now convert the frames in place
522 if (frame->is_same_frame()) {
523 same_frame_extended::create_at(frame_addr, new_offset_delta);
524 } else {
525 same_locals_1_stack_item_extended::create_at(
526 frame_addr, new_offset_delta, NULL);
527 // the verification_info_type should already be at the right spot
528 }
529 }
530 offset_adjusted = true; // needs to be done only once, since subsequent
531 // values are offsets from the current
532 }
533
534 // The stack map frame may contain verification types, if so we need to
535 // check and update any Uninitialized type's bci (no matter where it is).
536 int number_of_types = frame->number_of_types();
537 verification_type_info* types = frame->types();
538
539 for (int i = 0; i < number_of_types; ++i) {
540 if (types->is_uninitialized() && types->bci() > bci) {
541 types->set_bci(types->bci() + delta);
542 }
543 types = types->next();
544 }
545
546 // Full frame has stack values too
547 full_frame* ff = frame->as_full_frame();
548 if (ff != NULL) {
549 address eol = (address)types;
550 number_of_types = ff->stack_slots(eol);
551 types = ff->stack(eol);
552 for (int i = 0; i < number_of_types; ++i) {
553 if (types->is_uninitialized() && types->bci() > bci) {
554 types->set_bci(types->bci() + delta);
555 }
556 types = types->next();
557 }
558 }
559
560 frame = frame->next();
561 }
562
563 method()->set_stackmap_data(data); // in case it has changed
564 }
565}
566
567
568bool Relocator::expand_code_array(int delta) {
569 int length = MAX2(code_length() + delta, code_length() * (100+code_slop_pct()) / 100);
570
571 if (length > MAX_METHOD_LENGTH) {
572 if (delta == 0 && code_length() <= MAX_METHOD_LENGTH) {
573 length = MAX_METHOD_LENGTH;
574 } else {
575 return false;
576 }
577 }
578
579 unsigned char* new_code_array = NEW_RESOURCE_ARRAY(unsigned char, length);
580 if (!new_code_array) return false;
581
582 // Expanding current array
583 if (code_array() != NULL) {
584 memcpy(new_code_array, code_array(), code_length());
585 } else {
586 // Initial copy. Copy directly from Method*
587 memcpy(new_code_array, method()->code_base(), code_length());
588 }
589
590 set_code_array(new_code_array);
591 set_code_array_length(length);
592
593 return true;
594}
595
596
597// The instruction at "bci", whose size is "ilen", is changing size by
598// "delta". Reallocate, move code, recalculate jumps, and enqueue
599// change items as necessary.
600bool Relocator::relocate_code(int bci, int ilen, int delta) {
601 int next_bci = bci + ilen;
602 if (delta > 0 && code_length() + delta > code_array_length()) {
603 // Expand allocated code space, if necessary.
604 if (!expand_code_array(delta)) {
605 return false;
606 }
607 }
608
609 // We require 4-byte alignment of code arrays.
610 assert(((intptr_t)code_array() & 3) == 0, "check code alignment");
611 // Change jumps before doing the copying; this routine requires aligned switches.
612 change_jumps(bci, delta);
613
614 // In case we have shrunken a tableswitch/lookupswitch statement, we store the last
615 // bytes that get overwritten. We have to copy the bytes after the change_jumps method
616 // has been called, since it is likely to update last offset in a tableswitch/lookupswitch
617 assert(delta >= -3, "We cannot overwrite more than 3 bytes.");
618 if (delta < 0 && delta >= -3) {
619 memcpy(_overwrite, addr_at(bci + ilen + delta), -delta);
620 }
621
622 memmove(addr_at(next_bci + delta), addr_at(next_bci), code_length() - next_bci);
623 set_code_length(code_length() + delta);
624 // Also adjust exception tables...
625 adjust_exception_table(bci, delta);
626 // Line number tables...
627 adjust_line_no_table(bci, delta);
628 // And local variable table...
629 adjust_local_var_table(bci, delta);
630
631 // Adjust stack maps
632 adjust_stack_map_table(bci, delta);
633
634 // Relocate the pending change stack...
635 for (int j = 0; j < _changes->length(); j++) {
636 ChangeItem* ci = _changes->at(j);
637 ci->relocate(bci, delta);
638 }
639
640 // Notify any listeners about code relocation
641 notify(bci, delta, code_length());
642
643 return true;
644}
645
646// relocate a general instruction. Called by ChangeWiden class
647bool Relocator::handle_widen(int bci, int new_ilen, u_char inst_buffer[]) {
648 int ilen = rc_instr_len(bci);
649 if (!relocate_code(bci, ilen, new_ilen - ilen))
650 return false;
651
652 // Insert new bytecode(s)
653 for(int k = 0; k < new_ilen; k++) {
654 code_at_put(bci + k, (Bytecodes::Code)inst_buffer[k]);
655 }
656
657 return true;
658}
659
660// handle jump_widen instruction. Called be ChangeJumpWiden class
661bool Relocator::handle_jump_widen(int bci, int delta) {
662 int ilen = rc_instr_len(bci);
663
664 Bytecodes::Code bc = code_at(bci);
665 switch (bc) {
666 case Bytecodes::_ifeq:
667 case Bytecodes::_ifne:
668 case Bytecodes::_iflt:
669 case Bytecodes::_ifge:
670 case Bytecodes::_ifgt:
671 case Bytecodes::_ifle:
672 case Bytecodes::_if_icmpeq:
673 case Bytecodes::_if_icmpne:
674 case Bytecodes::_if_icmplt:
675 case Bytecodes::_if_icmpge:
676 case Bytecodes::_if_icmpgt:
677 case Bytecodes::_if_icmple:
678 case Bytecodes::_if_acmpeq:
679 case Bytecodes::_if_acmpne:
680 case Bytecodes::_ifnull:
681 case Bytecodes::_ifnonnull: {
682 const int goto_length = Bytecodes::length_for(Bytecodes::_goto);
683
684 // If 'if' points to the next bytecode after goto, it's already handled.
685 // it shouldn't be.
686 assert (short_at(bci+1) != ilen+goto_length, "if relocation already handled");
687 assert(ilen == 3, "check length");
688
689 // Convert to 0 if <cond> goto 6
690 // 3 _goto 11
691 // 6 _goto_w <wide delta offset>
692 // 11 <else code>
693 const int goto_w_length = Bytecodes::length_for(Bytecodes::_goto_w);
694 const int add_bci = goto_length + goto_w_length;
695
696 if (!relocate_code(bci, 3, /*delta*/add_bci)) return false;
697
698 // if bytecode points to goto_w instruction
699 short_at_put(bci + 1, ilen + goto_length);
700
701 int cbci = bci + ilen;
702 // goto around
703 code_at_put(cbci, Bytecodes::_goto);
704 short_at_put(cbci + 1, add_bci);
705 // goto_w <wide delta>
706 cbci = cbci + goto_length;
707 code_at_put(cbci, Bytecodes::_goto_w);
708 if (delta > 0) {
709 delta += 2; // goto_w is 2 bytes more than "if" code
710 } else {
711 delta -= ilen+goto_length; // branch starts at goto_w offset
712 }
713 int_at_put(cbci + 1, delta);
714 break;
715
716 }
717 case Bytecodes::_goto:
718 case Bytecodes::_jsr:
719 assert(ilen == 3, "check length");
720
721 if (!relocate_code(bci, 3, 2)) return false;
722 if (bc == Bytecodes::_goto)
723 code_at_put(bci, Bytecodes::_goto_w);
724 else
725 code_at_put(bci, Bytecodes::_jsr_w);
726
727 // If it's a forward jump, add 2 for the widening.
728 if (delta > 0) delta += 2;
729 int_at_put(bci + 1, delta);
730 break;
731
732 default: ShouldNotReachHere();
733 }
734
735 return true;
736}
737
738// handle lookup/table switch instructions. Called be ChangeSwitchPad class
739bool Relocator::handle_switch_pad(int bci, int old_pad, bool is_lookup_switch) {
740 int ilen = rc_instr_len(bci);
741 int new_pad = align(bci+1) - (bci+1);
742 int pad_delta = new_pad - old_pad;
743 if (pad_delta != 0) {
744 int len;
745 if (!is_lookup_switch) {
746 int low = int_at(bci+1+old_pad+4);
747 int high = int_at(bci+1+old_pad+8);
748 len = high-low+1 + 3; // 3 for default, hi, lo.
749 } else {
750 int npairs = int_at(bci+1+old_pad+4);
751 len = npairs*2 + 2; // 2 for default, npairs.
752 }
753 // Because "relocateCode" does a "changeJumps" loop,
754 // which parses instructions to determine their length,
755 // we need to call that before messing with the current
756 // instruction. Since it may also overwrite the current
757 // instruction when moving down, remember the possibly
758 // overwritten part.
759
760 // Move the code following the instruction...
761 if (!relocate_code(bci, ilen, pad_delta)) return false;
762
763 if (pad_delta < 0) {
764 // Move the shrunken instruction down.
765 memmove(addr_at(bci + 1 + new_pad),
766 addr_at(bci + 1 + old_pad),
767 len * 4 + pad_delta);
768 memmove(addr_at(bci + 1 + new_pad + len*4 + pad_delta),
769 _overwrite, -pad_delta);
770 } else {
771 assert(pad_delta > 0, "check");
772 // Move the expanded instruction up.
773 memmove(addr_at(bci +1 + new_pad),
774 addr_at(bci +1 + old_pad),
775 len * 4);
776 memset(addr_at(bci + 1), 0, new_pad); // pad must be 0
777 }
778 }
779 return true;
780}
781