1 /* 2 * Copyright (c) 1997, 2015, 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 "memory/universe.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 // 43 class 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 64 class 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 81 class 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 }; 105 106 class 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 127 128 Relocator::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. 145 methodHandle 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 } 179 180 181 bool 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 } 203 204 205 bool 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 218 int 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 } 251 return instruction_length_at(bci); 252 } 253 254 // If a change item is recorded for "pc", with type "ct", returns the 255 // associated padding, else -1. 256 int Relocator::get_orig_switch_pad(int bci, bool is_lookup_switch) { 257 for (int k = 0; k < _changes->length(); k++) { 258 ChangeItem* ci = _changes->at(k); 259 if (ci->is_switch_pad()) { 260 ChangeSwitchPad* csp = (ChangeSwitchPad*)ci; 261 if (csp->is_lookup_switch() == is_lookup_switch && csp->bci() == bci) { 262 return csp->padding(); 263 } 264 } 265 } 266 return -1; 267 } 268 269 270 // Push a ChangeJumpWiden if it doesn't already exist on the work queue, 271 // otherwise adjust the item already there by delta. The calculation for 272 // new_delta is wrong for this because it uses the offset stored in the 273 // code stream itself which wasn't fixed when item was pushed on the work queue. 274 void Relocator::push_jump_widen(int bci, int delta, int new_delta) { 275 for (int j = 0; j < _changes->length(); j++) { 276 ChangeItem* ci = _changes->at(j); 277 if (ci->adjust(bci, delta)) return; 278 } 279 _changes->push(new ChangeJumpWiden(bci, new_delta)); 280 } 281 282 283 // The current instruction of "c" is a jump; one of its offset starts 284 // at "offset" and is a short if "isShort" is "TRUE", 285 // and an integer otherwise. If the jump crosses "breakPC", change 286 // the span of the jump by "delta". 287 void Relocator::change_jump(int bci, int offset, bool is_short, int break_bci, int delta) { 288 int bci_delta = (is_short) ? short_at(offset) : int_at(offset); 289 int targ = bci + bci_delta; 290 291 if ((bci <= break_bci && targ > break_bci) || 292 (bci > break_bci && targ <= break_bci)) { 293 int new_delta; 294 if (bci_delta > 0) 295 new_delta = bci_delta + delta; 296 else 297 new_delta = bci_delta - delta; 298 299 if (is_short && ((new_delta > MAX_SHORT) || new_delta < MIN_SHORT)) { 300 push_jump_widen(bci, delta, new_delta); 301 } else if (is_short) { 302 short_at_put(offset, new_delta); 303 } else { 304 int_at_put(offset, new_delta); 305 } 306 } 307 } 308 309 310 // Changes all jumps crossing "break_bci" by "delta". May enqueue things 311 // on "rc->changes" 312 void Relocator::change_jumps(int break_bci, int delta) { 313 int bci = 0; 314 Bytecodes::Code bc; 315 // Now, adjust any affected instructions. 316 while (bci < code_length()) { 317 switch (bc= code_at(bci)) { 318 case Bytecodes::_ifeq: 319 case Bytecodes::_ifne: 320 case Bytecodes::_iflt: 321 case Bytecodes::_ifge: 322 case Bytecodes::_ifgt: 323 case Bytecodes::_ifle: 324 case Bytecodes::_if_icmpeq: 325 case Bytecodes::_if_icmpne: 326 case Bytecodes::_if_icmplt: 327 case Bytecodes::_if_icmpge: 328 case Bytecodes::_if_icmpgt: 329 case Bytecodes::_if_icmple: 330 case Bytecodes::_if_acmpeq: 331 case Bytecodes::_if_acmpne: 332 case Bytecodes::_ifnull: 333 case Bytecodes::_ifnonnull: 334 case Bytecodes::_goto: 335 case Bytecodes::_jsr: 336 change_jump(bci, bci+1, true, break_bci, delta); 337 break; 338 case Bytecodes::_goto_w: 339 case Bytecodes::_jsr_w: 340 change_jump(bci, bci+1, false, break_bci, delta); 341 break; 342 case Bytecodes::_tableswitch: 343 case Bytecodes::_lookupswitch: 344 case Bytecodes::_fast_linearswitch: 345 case Bytecodes::_fast_binaryswitch: { 346 int recPad = get_orig_switch_pad(bci, (bc != Bytecodes::_tableswitch)); 347 int oldPad = (recPad != -1) ? recPad : align(bci+1) - (bci+1); 348 if (bci > break_bci) { 349 int new_bci = bci + delta; 350 int newPad = align(new_bci+1) - (new_bci+1); 351 // Do we need to check the padding? 352 if (newPad != oldPad) { 353 if (recPad == -1) { 354 _changes->push(new ChangeSwitchPad(bci, oldPad, (bc != Bytecodes::_tableswitch))); 355 } 356 } 357 } 358 359 // Then the rest, which depend on the kind of switch. 360 switch (bc) { 361 case Bytecodes::_tableswitch: { 362 change_jump(bci, bci +1 + oldPad, false, break_bci, delta); 363 // We cannot use the Bytecode_tableswitch abstraction, since the padding might not be correct. 364 int lo = int_at(bci + 1 + oldPad + 4 * 1); 365 int hi = int_at(bci + 1 + oldPad + 4 * 2); 366 int n = hi - lo + 1; 367 for (int k = 0; k < n; k++) { 368 change_jump(bci, bci +1 + oldPad + 4*(k+3), false, break_bci, delta); 369 } 370 // Special next-bci calculation here... 371 bci += 1 + oldPad + (n+3)*4; 372 continue; 373 } 374 case Bytecodes::_lookupswitch: 375 case Bytecodes::_fast_linearswitch: 376 case Bytecodes::_fast_binaryswitch: { 377 change_jump(bci, bci +1 + oldPad, false, break_bci, delta); 378 // We cannot use the Bytecode_lookupswitch abstraction, since the padding might not be correct. 379 int npairs = int_at(bci + 1 + oldPad + 4 * 1); 380 for (int k = 0; k < npairs; k++) { 381 change_jump(bci, bci + 1 + oldPad + 4*(2 + 2*k + 1), false, break_bci, delta); 382 } 383 /* Special next-bci calculation here... */ 384 bci += 1 + oldPad + (2 + (npairs*2))*4; 385 continue; 386 } 387 default: 388 ShouldNotReachHere(); 389 } 390 } 391 default: 392 break; 393 } 394 bci += rc_instr_len(bci); 395 } 396 } 397 398 // The width of instruction at "pc" is changing by "delta". Adjust the 399 // exception table, if any, of "rc->mb". 400 void Relocator::adjust_exception_table(int bci, int delta) { 401 ExceptionTable table(_method()); 402 for (int index = 0; index < table.length(); index ++) { 403 if (table.start_pc(index) > bci) { 404 table.set_start_pc(index, table.start_pc(index) + delta); 405 table.set_end_pc(index, table.end_pc(index) + delta); 406 } else if (bci < table.end_pc(index)) { 407 table.set_end_pc(index, table.end_pc(index) + delta); 408 } 409 if (table.handler_pc(index) > bci) 410 table.set_handler_pc(index, table.handler_pc(index) + delta); 411 } 412 } 413 414 415 // The width of instruction at "bci" is changing by "delta". Adjust the line number table. 416 void Relocator::adjust_line_no_table(int bci, int delta) { 417 if (method()->has_linenumber_table()) { 418 CompressedLineNumberReadStream reader(method()->compressed_linenumber_table()); 419 CompressedLineNumberWriteStream writer(64); // plenty big for most line number tables 420 while (reader.read_pair()) { 421 int adjustment = (reader.bci() > bci) ? delta : 0; 422 writer.write_pair(reader.bci() + adjustment, reader.line()); 423 } 424 writer.write_terminator(); 425 set_compressed_line_number_table(writer.buffer()); 426 set_compressed_line_number_table_size(writer.position()); 427 } 428 } 429 430 431 // The width of instruction at "bci" is changing by "delta". Adjust the local variable table. 432 void Relocator::adjust_local_var_table(int bci, int delta) { 433 int localvariable_table_length = method()->localvariable_table_length(); 434 if (localvariable_table_length > 0) { 435 LocalVariableTableElement* table = method()->localvariable_table_start(); 436 for (int i = 0; i < localvariable_table_length; i++) { 437 u2 current_bci = table[i].start_bci; 438 if (current_bci > bci) { 439 table[i].start_bci = current_bci + delta; 440 } else { 441 u2 current_length = table[i].length; 442 if (current_bci + current_length > bci) { 443 table[i].length = current_length + delta; 444 } 445 } 446 } 447 } 448 } 449 450 // Create a new array, copying the src array but adding a hole at 451 // the specified location 452 static Array<u1>* insert_hole_at(ClassLoaderData* loader_data, 453 size_t where, int hole_sz, Array<u1>* src) { 454 Thread* THREAD = Thread::current(); 455 Array<u1>* dst = 456 MetadataFactory::new_array<u1>(loader_data, src->length() + hole_sz, 0, CHECK_NULL); 457 458 address src_addr = (address)src->adr_at(0); 459 address dst_addr = (address)dst->adr_at(0); 460 461 memcpy(dst_addr, src_addr, where); 462 memcpy(dst_addr + where + hole_sz, 463 src_addr + where, src->length() - where); 464 return dst; 465 } 466 467 // The width of instruction at "bci" is changing by "delta". Adjust the stack 468 // map frames. 469 void Relocator::adjust_stack_map_table(int bci, int delta) { 470 if (method()->has_stackmap_table()) { 471 Array<u1>* data = method()->stackmap_data(); 472 // The data in the array is a classfile representation of the stackmap table 473 stack_map_table* sm_table = 474 stack_map_table::at((address)data->adr_at(0)); 475 476 int count = sm_table->number_of_entries(); 477 stack_map_frame* frame = sm_table->entries(); 478 int bci_iter = -1; 479 bool offset_adjusted = false; // only need to adjust one offset 480 481 for (int i = 0; i < count; ++i) { 482 int offset_delta = frame->offset_delta(); 483 bci_iter += offset_delta; 484 485 if (!offset_adjusted && bci_iter > bci) { 486 int new_offset_delta = offset_delta + delta; 487 488 if (frame->is_valid_offset(new_offset_delta)) { 489 frame->set_offset_delta(new_offset_delta); 490 } else { 491 assert(frame->is_same_frame() || 492 frame->is_same_locals_1_stack_item_frame(), 493 "Frame must be one of the compressed forms"); 494 // The new delta exceeds the capacity of the 'same_frame' or 495 // 'same_frame_1_stack_item_frame' frame types. We need to 496 // convert these frames to the extended versions, but the extended 497 // version is bigger and requires more room. So we allocate a 498 // new array and copy the data, being sure to leave u2-sized hole 499 // right after the 'frame_type' for the new offset field. 500 // 501 // We can safely ignore the reverse situation as a small delta 502 // can still be used in an extended version of the frame. 503 504 size_t frame_offset = (address)frame - (address)data->adr_at(0); 505 506 ClassLoaderData* loader_data = method()->method_holder()->class_loader_data(); 507 Array<u1>* new_data = insert_hole_at(loader_data, frame_offset + 1, 2, data); 508 if (new_data == NULL) { 509 return; // out-of-memory? 510 } 511 // Deallocate old data 512 MetadataFactory::free_array<u1>(loader_data, data); 513 data = new_data; 514 515 address frame_addr = (address)(data->adr_at(0) + frame_offset); 516 frame = stack_map_frame::at(frame_addr); 517 518 519 // Now convert the frames in place 520 if (frame->is_same_frame()) { 521 same_frame_extended::create_at(frame_addr, new_offset_delta); 522 } else { 523 same_locals_1_stack_item_extended::create_at( 524 frame_addr, new_offset_delta, NULL); 525 // the verification_info_type should already be at the right spot 526 } 527 } 528 offset_adjusted = true; // needs to be done only once, since subsequent 529 // values are offsets from the current 530 } 531 532 // The stack map frame may contain verification types, if so we need to 533 // check and update any Uninitialized type's bci (no matter where it is). 534 int number_of_types = frame->number_of_types(); 535 verification_type_info* types = frame->types(); 536 537 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 // Full frame has stack values too 545 full_frame* ff = frame->as_full_frame(); 546 if (ff != NULL) { 547 address eol = (address)types; 548 number_of_types = ff->stack_slots(eol); 549 types = ff->stack(eol); 550 for (int i = 0; i < number_of_types; ++i) { 551 if (types->is_uninitialized() && types->bci() > bci) { 552 types->set_bci(types->bci() + delta); 553 } 554 types = types->next(); 555 } 556 } 557 558 frame = frame->next(); 559 } 560 561 method()->set_stackmap_data(data); // in case it has changed 562 } 563 } 564 565 566 bool Relocator::expand_code_array(int delta) { 567 int length = MAX2(code_length() + delta, code_length() * (100+code_slop_pct()) / 100); 568 569 if (length > MAX_METHOD_LENGTH) { 570 if (delta == 0 && code_length() <= MAX_METHOD_LENGTH) { 571 length = MAX_METHOD_LENGTH; 572 } else { 573 return false; 574 } 575 } 576 577 unsigned char* new_code_array = NEW_RESOURCE_ARRAY(unsigned char, length); 578 if (!new_code_array) return false; 579 580 // Expanding current array 581 if (code_array() != NULL) { 582 memcpy(new_code_array, code_array(), code_length()); 583 } else { 584 // Initial copy. Copy directly from Method* 585 memcpy(new_code_array, method()->code_base(), code_length()); 586 } 587 588 set_code_array(new_code_array); 589 set_code_array_length(length); 590 591 return true; 592 } 593 594 595 // The instruction at "bci", whose size is "ilen", is changing size by 596 // "delta". Reallocate, move code, recalculate jumps, and enqueue 597 // change items as necessary. 598 bool Relocator::relocate_code(int bci, int ilen, int delta) { 599 int next_bci = bci + ilen; 600 if (delta > 0 && code_length() + delta > code_array_length()) { 601 // Expand allocated code space, if necessary. 602 if (!expand_code_array(delta)) { 603 return false; 604 } 605 } 606 607 // We require 4-byte alignment of code arrays. 608 assert(((intptr_t)code_array() & 3) == 0, "check code alignment"); 609 // Change jumps before doing the copying; this routine requires aligned switches. 610 change_jumps(bci, delta); 611 612 // In case we have shrunken a tableswitch/lookupswitch statement, we store the last 613 // bytes that get overwritten. We have to copy the bytes after the change_jumps method 614 // has been called, since it is likely to update last offset in a tableswitch/lookupswitch 615 assert(delta >= -3, "We cannot overwrite more than 3 bytes."); 616 if (delta < 0 && delta >= -3) { 617 memcpy(_overwrite, addr_at(bci + ilen + delta), -delta); 618 } 619 620 memmove(addr_at(next_bci + delta), addr_at(next_bci), code_length() - next_bci); 621 set_code_length(code_length() + delta); 622 // Also adjust exception tables... 623 adjust_exception_table(bci, delta); 624 // Line number tables... 625 adjust_line_no_table(bci, delta); 626 // And local variable table... 627 adjust_local_var_table(bci, delta); 628 629 // Adjust stack maps 630 adjust_stack_map_table(bci, delta); 631 632 // Relocate the pending change stack... 633 for (int j = 0; j < _changes->length(); j++) { 634 ChangeItem* ci = _changes->at(j); 635 ci->relocate(bci, delta); 636 } 637 638 // Notify any listeners about code relocation 639 notify(bci, delta, code_length()); 640 641 return true; 642 } 643 644 // relocate a general instruction. Called by ChangeWiden class 645 bool Relocator::handle_widen(int bci, int new_ilen, u_char inst_buffer[]) { 646 int ilen = rc_instr_len(bci); 647 if (!relocate_code(bci, ilen, new_ilen - ilen)) 648 return false; 649 650 // Insert new bytecode(s) 651 for(int k = 0; k < new_ilen; k++) { 652 code_at_put(bci + k, (Bytecodes::Code)inst_buffer[k]); 653 } 654 655 return true; 656 } 657 658 // handle jump_widen instruction. Called be ChangeJumpWiden class 659 bool Relocator::handle_jump_widen(int bci, int delta) { 660 int ilen = rc_instr_len(bci); 661 662 Bytecodes::Code bc = code_at(bci); 663 switch (bc) { 664 case Bytecodes::_ifeq: 665 case Bytecodes::_ifne: 666 case Bytecodes::_iflt: 667 case Bytecodes::_ifge: 668 case Bytecodes::_ifgt: 669 case Bytecodes::_ifle: 670 case Bytecodes::_if_icmpeq: 671 case Bytecodes::_if_icmpne: 672 case Bytecodes::_if_icmplt: 673 case Bytecodes::_if_icmpge: 674 case Bytecodes::_if_icmpgt: 675 case Bytecodes::_if_icmple: 676 case Bytecodes::_if_acmpeq: 677 case Bytecodes::_if_acmpne: 678 case Bytecodes::_ifnull: 679 case Bytecodes::_ifnonnull: { 680 const int goto_length = Bytecodes::length_for(Bytecodes::_goto); 681 682 // If 'if' points to the next bytecode after goto, it's already handled. 683 // it shouldn't be. 684 assert (short_at(bci+1) != ilen+goto_length, "if relocation already handled"); 685 assert(ilen == 3, "check length"); 686 687 // Convert to 0 if <cond> goto 6 688 // 3 _goto 11 689 // 6 _goto_w <wide delta offset> 690 // 11 <else code> 691 const int goto_w_length = Bytecodes::length_for(Bytecodes::_goto_w); 692 const int add_bci = goto_length + goto_w_length; 693 694 if (!relocate_code(bci, 3, /*delta*/add_bci)) return false; 695 696 // if bytecode points to goto_w instruction 697 short_at_put(bci + 1, ilen + goto_length); 698 699 int cbci = bci + ilen; 700 // goto around 701 code_at_put(cbci, Bytecodes::_goto); 702 short_at_put(cbci + 1, add_bci); 703 // goto_w <wide delta> 704 cbci = cbci + goto_length; 705 code_at_put(cbci, Bytecodes::_goto_w); 706 if (delta > 0) { 707 delta += 2; // goto_w is 2 bytes more than "if" code 708 } else { 709 delta -= ilen+goto_length; // branch starts at goto_w offset 710 } 711 int_at_put(cbci + 1, delta); 712 break; 713 714 } 715 case Bytecodes::_goto: 716 case Bytecodes::_jsr: 717 assert(ilen == 3, "check length"); 718 719 if (!relocate_code(bci, 3, 2)) return false; 720 if (bc == Bytecodes::_goto) 721 code_at_put(bci, Bytecodes::_goto_w); 722 else 723 code_at_put(bci, Bytecodes::_jsr_w); 724 725 // If it's a forward jump, add 2 for the widening. 726 if (delta > 0) delta += 2; 727 int_at_put(bci + 1, delta); 728 break; 729 730 default: ShouldNotReachHere(); 731 } 732 733 return true; 734 } 735 736 // handle lookup/table switch instructions. Called be ChangeSwitchPad class 737 bool Relocator::handle_switch_pad(int bci, int old_pad, bool is_lookup_switch) { 738 int ilen = rc_instr_len(bci); 739 int new_pad = align(bci+1) - (bci+1); 740 int pad_delta = new_pad - old_pad; 741 if (pad_delta != 0) { 742 int len; 743 if (!is_lookup_switch) { 744 int low = int_at(bci+1+old_pad+4); 745 int high = int_at(bci+1+old_pad+8); 746 len = high-low+1 + 3; // 3 for default, hi, lo. 747 } else { 748 int npairs = int_at(bci+1+old_pad+4); 749 len = npairs*2 + 2; // 2 for default, npairs. 750 } 751 // Because "relocateCode" does a "changeJumps" loop, 752 // which parses instructions to determine their length, 753 // we need to call that before messing with the current 754 // instruction. Since it may also overwrite the current 755 // instruction when moving down, remember the possibly 756 // overwritten part. 757 758 // Move the code following the instruction... 759 if (!relocate_code(bci, ilen, pad_delta)) return false; 760 761 if (pad_delta < 0) { 762 // Move the shrunken instruction down. 763 memmove(addr_at(bci + 1 + new_pad), 764 addr_at(bci + 1 + old_pad), 765 len * 4 + pad_delta); 766 memmove(addr_at(bci + 1 + new_pad + len*4 + pad_delta), 767 _overwrite, -pad_delta); 768 } else { 769 assert(pad_delta > 0, "check"); 770 // Move the expanded instruction up. 771 memmove(addr_at(bci +1 + new_pad), 772 addr_at(bci +1 + old_pad), 773 len * 4); 774 memset(addr_at(bci + 1), 0, new_pad); // pad must be 0 775 } 776 } 777 return true; 778 }