1 /* 2 * Copyright (c) 1997, 2010, 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/oopFactory.hpp" 29 #include "memory/universe.inline.hpp" 30 #include "oops/oop.inline.hpp" 31 #include "runtime/handles.inline.hpp" 32 #include "runtime/relocator.hpp" 33 34 #define MAX_METHOD_LENGTH 65535 35 36 #define MAX_SHORT ((1 << 15) - 1) 37 #define MIN_SHORT (- (1 << 15)) 38 39 // Encapsulates a code change request. There are 3 types. 40 // General instruction, jump instruction, and table/lookup switches 41 // 42 class ChangeItem : public ResourceObj { 43 int _bci; 44 public: 45 ChangeItem(int bci) { _bci = bci; } 46 virtual bool handle_code_change(Relocator *r) = 0; 47 48 // type info 49 virtual bool is_widen() { return false; } 50 virtual bool is_jump_widen() { return false; } 51 virtual bool is_switch_pad() { return false; } 52 53 // accessors 54 int bci() { return _bci; } 55 void relocate(int break_bci, int delta) { if (_bci > break_bci) { _bci += delta; } } 56 57 virtual bool adjust(int bci, int delta) { return false; } 58 59 // debug 60 virtual void print() = 0; 61 }; 62 63 class ChangeWiden : public ChangeItem { 64 int _new_ilen; // New length of instruction at bci 65 u_char* _inst_buffer; // New bytecodes 66 public: 67 ChangeWiden(int bci, int new_ilen, u_char* inst_buffer) : ChangeItem(bci) { 68 _new_ilen = new_ilen; 69 _inst_buffer = inst_buffer; 70 } 71 72 // Callback to do instruction 73 bool handle_code_change(Relocator *r) { return r->handle_widen(bci(), _new_ilen, _inst_buffer); }; 74 75 bool is_widen() { return true; } 76 77 void print() { tty->print_cr("ChangeWiden. bci: %d New_ilen: %d", bci(), _new_ilen); } 78 }; 79 80 class ChangeJumpWiden : public ChangeItem { 81 int _delta; // New length of instruction at bci 82 public: 83 ChangeJumpWiden(int bci, int delta) : ChangeItem(bci) { _delta = delta; } 84 85 // Callback to do instruction 86 bool handle_code_change(Relocator *r) { return r->handle_jump_widen(bci(), _delta); }; 87 88 bool is_jump_widen() { return true; } 89 90 // If the bci matches, adjust the delta in the change jump request. 91 bool adjust(int jump_bci, int delta) { 92 if (bci() == jump_bci) { 93 if (_delta > 0) 94 _delta += delta; 95 else 96 _delta -= delta; 97 return true; 98 } 99 return false; 100 } 101 102 void print() { tty->print_cr("ChangeJumpWiden. bci: %d Delta: %d", bci(), _delta); } 103 }; 104 105 class ChangeSwitchPad : public ChangeItem { 106 int _padding; 107 bool _is_lookup_switch; 108 public: 109 ChangeSwitchPad(int bci, int padding, bool is_lookup_switch) : ChangeItem(bci) { 110 _padding = padding; 111 _is_lookup_switch = is_lookup_switch; 112 } 113 114 // Callback to do instruction 115 bool handle_code_change(Relocator *r) { return r->handle_switch_pad(bci(), _padding, _is_lookup_switch); }; 116 117 bool is_switch_pad() { return true; } 118 int padding() { return _padding; } 119 bool is_lookup_switch() { return _is_lookup_switch; } 120 121 void print() { tty->print_cr("ChangeSwitchPad. bci: %d Padding: %d IsLookupSwitch: %d", bci(), _padding, _is_lookup_switch); } 122 }; 123 124 //----------------------------------------------------------------------------------------------------------- 125 // Relocator code 126 127 Relocator::Relocator(methodHandle m, RelocatorListener* listener) { 128 set_method(m); 129 set_code_length(method()->code_size()); 130 set_code_array(NULL); 131 // Allocate code array and copy bytecodes 132 if (!expand_code_array(0)) { 133 // Should have at least MAX_METHOD_LENGTH available or the verifier 134 // would have failed. 135 ShouldNotReachHere(); 136 } 137 set_compressed_line_number_table(NULL); 138 set_compressed_line_number_table_size(0); 139 _listener = listener; 140 } 141 142 // size is the new size of the instruction at bci. Hence, if size is less than the current 143 // instruction sice, we will shrink the code. 144 methodHandle Relocator::insert_space_at(int bci, int size, u_char inst_buffer[], TRAPS) { 145 _changes = new GrowableArray<ChangeItem*> (10); 146 _changes->push(new ChangeWiden(bci, size, inst_buffer)); 147 148 if (TraceRelocator) { 149 tty->print_cr("Space at: %d Size: %d", bci, size); 150 _method->print(); 151 _method->print_codes(); 152 tty->print_cr("-------------------------------------------------"); 153 } 154 155 if (!handle_code_changes()) return methodHandle(); 156 157 // Construct the new method 158 methodHandle new_method = methodOopDesc::clone_with_new_data(method(), 159 code_array(), code_length(), 160 compressed_line_number_table(), 161 compressed_line_number_table_size(), 162 CHECK_(methodHandle())); 163 set_method(new_method); 164 165 if (TraceRelocator) { 166 tty->print_cr("-------------------------------------------------"); 167 tty->print_cr("new method"); 168 _method->print_codes(); 169 } 170 171 return new_method; 172 } 173 174 175 bool Relocator::handle_code_changes() { 176 assert(_changes != NULL, "changes vector must be initialized"); 177 178 while (!_changes->is_empty()) { 179 // Inv: everything is aligned. 180 ChangeItem* ci = _changes->first(); 181 182 if (TraceRelocator) { 183 ci->print(); 184 } 185 186 // Execute operation 187 if (!ci->handle_code_change(this)) return false; 188 189 // Shuffel items up 190 for (int index = 1; index < _changes->length(); index++) { 191 _changes->at_put(index-1, _changes->at(index)); 192 } 193 _changes->pop(); 194 } 195 return true; 196 } 197 198 199 bool Relocator::is_opcode_lookupswitch(Bytecodes::Code bc) { 200 switch (bc) { 201 case Bytecodes::_tableswitch: return false; 202 case Bytecodes::_lookupswitch: // not rewritten on ia64 203 case Bytecodes::_fast_linearswitch: // rewritten _lookupswitch 204 case Bytecodes::_fast_binaryswitch: return true; // rewritten _lookupswitch 205 default: ShouldNotReachHere(); 206 } 207 return true; // dummy 208 } 209 210 // We need a special instruction size method, since lookupswitches and tableswitches might not be 211 // properly alligned during relocation 212 int Relocator::rc_instr_len(int bci) { 213 Bytecodes::Code bc= code_at(bci); 214 switch (bc) { 215 // In the case of switch instructions, see if we have the original 216 // padding recorded. 217 case Bytecodes::_tableswitch: 218 case Bytecodes::_lookupswitch: 219 case Bytecodes::_fast_linearswitch: 220 case Bytecodes::_fast_binaryswitch: 221 { 222 int pad = get_orig_switch_pad(bci, is_opcode_lookupswitch(bc)); 223 if (pad == -1) { 224 return instruction_length_at(bci); 225 } 226 // Otherwise, depends on the switch type. 227 switch (bc) { 228 case Bytecodes::_tableswitch: { 229 int lo = int_at(bci + 1 + pad + 4 * 1); 230 int hi = int_at(bci + 1 + pad + 4 * 2); 231 int n = hi - lo + 1; 232 return 1 + pad + 4*(3 + n); 233 } 234 case Bytecodes::_lookupswitch: 235 case Bytecodes::_fast_linearswitch: 236 case Bytecodes::_fast_binaryswitch: { 237 int npairs = int_at(bci + 1 + pad + 4 * 1); 238 return 1 + pad + 4*(2 + 2*npairs); 239 } 240 default: 241 ShouldNotReachHere(); 242 } 243 } 244 } 245 return instruction_length_at(bci); 246 } 247 248 // If a change item is recorded for "pc", with type "ct", returns the 249 // associated padding, else -1. 250 int Relocator::get_orig_switch_pad(int bci, bool is_lookup_switch) { 251 for (int k = 0; k < _changes->length(); k++) { 252 ChangeItem* ci = _changes->at(k); 253 if (ci->is_switch_pad()) { 254 ChangeSwitchPad* csp = (ChangeSwitchPad*)ci; 255 if (csp->is_lookup_switch() == is_lookup_switch && csp->bci() == bci) { 256 return csp->padding(); 257 } 258 } 259 } 260 return -1; 261 } 262 263 264 // Push a ChangeJumpWiden if it doesn't already exist on the work queue, 265 // otherwise adjust the item already there by delta. The calculation for 266 // new_delta is wrong for this because it uses the offset stored in the 267 // code stream itself which wasn't fixed when item was pushed on the work queue. 268 void Relocator::push_jump_widen(int bci, int delta, int new_delta) { 269 for (int j = 0; j < _changes->length(); j++) { 270 ChangeItem* ci = _changes->at(j); 271 if (ci->adjust(bci, delta)) return; 272 } 273 _changes->push(new ChangeJumpWiden(bci, new_delta)); 274 } 275 276 277 // The current instruction of "c" is a jump; one of its offset starts 278 // at "offset" and is a short if "isShort" is "TRUE", 279 // and an integer otherwise. If the jump crosses "breakPC", change 280 // the span of the jump by "delta". 281 void Relocator::change_jump(int bci, int offset, bool is_short, int break_bci, int delta) { 282 int bci_delta = (is_short) ? short_at(offset) : int_at(offset); 283 int targ = bci + bci_delta; 284 285 if ((bci <= break_bci && targ > break_bci) || 286 (bci > break_bci && targ <= break_bci)) { 287 int new_delta; 288 if (bci_delta > 0) 289 new_delta = bci_delta + delta; 290 else 291 new_delta = bci_delta - delta; 292 293 if (is_short && ((new_delta > MAX_SHORT) || new_delta < MIN_SHORT)) { 294 push_jump_widen(bci, delta, new_delta); 295 } else if (is_short) { 296 short_at_put(offset, new_delta); 297 } else { 298 int_at_put(offset, new_delta); 299 } 300 } 301 } 302 303 304 // Changes all jumps crossing "break_bci" by "delta". May enqueue things 305 // on "rc->changes" 306 void Relocator::change_jumps(int break_bci, int delta) { 307 int bci = 0; 308 Bytecodes::Code bc; 309 // Now, adjust any affected instructions. 310 while (bci < code_length()) { 311 switch (bc= code_at(bci)) { 312 case Bytecodes::_ifeq: 313 case Bytecodes::_ifne: 314 case Bytecodes::_iflt: 315 case Bytecodes::_ifge: 316 case Bytecodes::_ifgt: 317 case Bytecodes::_ifle: 318 case Bytecodes::_if_icmpeq: 319 case Bytecodes::_if_icmpne: 320 case Bytecodes::_if_icmplt: 321 case Bytecodes::_if_icmpge: 322 case Bytecodes::_if_icmpgt: 323 case Bytecodes::_if_icmple: 324 case Bytecodes::_if_acmpeq: 325 case Bytecodes::_if_acmpne: 326 case Bytecodes::_ifnull: 327 case Bytecodes::_ifnonnull: 328 case Bytecodes::_goto: 329 case Bytecodes::_jsr: 330 change_jump(bci, bci+1, true, break_bci, delta); 331 break; 332 case Bytecodes::_goto_w: 333 case Bytecodes::_jsr_w: 334 change_jump(bci, bci+1, false, break_bci, delta); 335 break; 336 case Bytecodes::_tableswitch: 337 case Bytecodes::_lookupswitch: 338 case Bytecodes::_fast_linearswitch: 339 case Bytecodes::_fast_binaryswitch: { 340 int recPad = get_orig_switch_pad(bci, (bc != Bytecodes::_tableswitch)); 341 int oldPad = (recPad != -1) ? recPad : align(bci+1) - (bci+1); 342 if (bci > break_bci) { 343 int new_bci = bci + delta; 344 int newPad = align(new_bci+1) - (new_bci+1); 345 // Do we need to check the padding? 346 if (newPad != oldPad) { 347 if (recPad == -1) { 348 _changes->push(new ChangeSwitchPad(bci, oldPad, (bc != Bytecodes::_tableswitch))); 349 } 350 } 351 } 352 353 // Then the rest, which depend on the kind of switch. 354 switch (bc) { 355 case Bytecodes::_tableswitch: { 356 change_jump(bci, bci +1 + oldPad, false, break_bci, delta); 357 // We cannot use the Bytecode_tableswitch abstraction, since the padding might not be correct. 358 int lo = int_at(bci + 1 + oldPad + 4 * 1); 359 int hi = int_at(bci + 1 + oldPad + 4 * 2); 360 int n = hi - lo + 1; 361 for (int k = 0; k < n; k++) { 362 change_jump(bci, bci +1 + oldPad + 4*(k+3), false, break_bci, delta); 363 } 364 // Special next-bci calculation here... 365 bci += 1 + oldPad + (n+3)*4; 366 continue; 367 } 368 case Bytecodes::_lookupswitch: 369 case Bytecodes::_fast_linearswitch: 370 case Bytecodes::_fast_binaryswitch: { 371 change_jump(bci, bci +1 + oldPad, false, break_bci, delta); 372 // We cannot use the Bytecode_lookupswitch abstraction, since the padding might not be correct. 373 int npairs = int_at(bci + 1 + oldPad + 4 * 1); 374 for (int k = 0; k < npairs; k++) { 375 change_jump(bci, bci + 1 + oldPad + 4*(2 + 2*k + 1), false, break_bci, delta); 376 } 377 /* Special next-bci calculation here... */ 378 bci += 1 + oldPad + (2 + (npairs*2))*4; 379 continue; 380 } 381 default: 382 ShouldNotReachHere(); 383 } 384 } 385 default: 386 break; 387 } 388 bci += rc_instr_len(bci); 389 } 390 } 391 392 // The width of instruction at "pc" is changing by "delta". Adjust the 393 // exception table, if any, of "rc->mb". 394 void Relocator::adjust_exception_table(int bci, int delta) { 395 typeArrayOop table = method()->exception_table(); 396 for (int index = 0; index < table->length(); index +=4) { 397 if (table->int_at(index) > bci) { 398 table->int_at_put(index+0, table->int_at(index+0) + delta); 399 table->int_at_put(index+1, table->int_at(index+1) + delta); 400 } else if (bci < table->int_at(index+1)) { 401 table->int_at_put(index+1, table->int_at(index+1) + delta); 402 } 403 if (table->int_at(index+2) > bci) 404 table->int_at_put(index+2, table->int_at(index+2) + delta); 405 } 406 } 407 408 409 // The width of instruction at "bci" is changing by "delta". Adjust the line number table. 410 void Relocator::adjust_line_no_table(int bci, int delta) { 411 if (method()->has_linenumber_table()) { 412 CompressedLineNumberReadStream reader(method()->compressed_linenumber_table()); 413 CompressedLineNumberWriteStream writer(64); // plenty big for most line number tables 414 while (reader.read_pair()) { 415 int adjustment = (reader.bci() > bci) ? delta : 0; 416 writer.write_pair(reader.bci() + adjustment, reader.line()); 417 } 418 writer.write_terminator(); 419 set_compressed_line_number_table(writer.buffer()); 420 set_compressed_line_number_table_size(writer.position()); 421 } 422 } 423 424 425 // The width of instruction at "bci" is changing by "delta". Adjust the local variable table. 426 void Relocator::adjust_local_var_table(int bci, int delta) { 427 int localvariable_table_length = method()->localvariable_table_length(); 428 if (localvariable_table_length > 0) { 429 LocalVariableTableElement* table = method()->localvariable_table_start(); 430 for (int i = 0; i < localvariable_table_length; i++) { 431 u2 current_bci = table[i].start_bci; 432 if (current_bci > bci) { 433 table[i].start_bci = current_bci + delta; 434 } else { 435 u2 current_length = table[i].length; 436 if (current_bci + current_length > bci) { 437 table[i].length = current_length + delta; 438 } 439 } 440 } 441 } 442 } 443 444 // Create a new array, copying the src array but adding a hole at 445 // the specified location 446 static typeArrayOop insert_hole_at( 447 size_t where, int hole_sz, typeArrayOop src) { 448 Thread* THREAD = Thread::current(); 449 Handle src_hnd(THREAD, src); 450 typeArrayOop dst = 451 oopFactory::new_permanent_byteArray(src->length() + hole_sz, CHECK_NULL); 452 src = (typeArrayOop)src_hnd(); 453 454 address src_addr = (address)src->byte_at_addr(0); 455 address dst_addr = (address)dst->byte_at_addr(0); 456 457 memcpy(dst_addr, src_addr, where); 458 memcpy(dst_addr + where + hole_sz, 459 src_addr + where, src->length() - where); 460 return dst; 461 } 462 463 // The width of instruction at "bci" is changing by "delta". Adjust the stack 464 // map frames. 465 void Relocator::adjust_stack_map_table(int bci, int delta) { 466 if (method()->has_stackmap_table()) { 467 typeArrayOop data = method()->stackmap_data(); 468 // The data in the array is a classfile representation of the stackmap 469 // table attribute, less the initial u2 tag and u4 attribute_length fields. 470 stack_map_table_attribute* attr = stack_map_table_attribute::at( 471 (address)data->byte_at_addr(0) - (sizeof(u2) + sizeof(u4))); 472 473 int count = attr->number_of_entries(); 474 stack_map_frame* frame = attr->entries(); 475 int bci_iter = -1; 476 bool offset_adjusted = false; // only need to adjust one offset 477 478 for (int i = 0; i < count; ++i) { 479 int offset_delta = frame->offset_delta(); 480 bci_iter += offset_delta; 481 482 if (!offset_adjusted && bci_iter > bci) { 483 int new_offset_delta = offset_delta + delta; 484 485 if (frame->is_valid_offset(new_offset_delta)) { 486 frame->set_offset_delta(new_offset_delta); 487 } else { 488 assert(frame->is_same_frame() || 489 frame->is_same_frame_1_stack_item_frame(), 490 "Frame must be one of the compressed forms"); 491 // The new delta exceeds the capacity of the 'same_frame' or 492 // 'same_frame_1_stack_item_frame' frame types. We need to 493 // convert these frames to the extended versions, but the extended 494 // version is bigger and requires more room. So we allocate a 495 // new array and copy the data, being sure to leave u2-sized hole 496 // right after the 'frame_type' for the new offset field. 497 // 498 // We can safely ignore the reverse situation as a small delta 499 // can still be used in an extended version of the frame. 500 501 size_t frame_offset = (address)frame - (address)data->byte_at_addr(0); 502 503 data = insert_hole_at(frame_offset + 1, 2, data); 504 if (data == NULL) { 505 return; // out-of-memory? 506 } 507 508 address frame_addr = (address)(data->byte_at_addr(0) + frame_offset); 509 frame = stack_map_frame::at(frame_addr); 510 511 512 // Now convert the frames in place 513 if (frame->is_same_frame()) { 514 same_frame_extended::create_at(frame_addr, new_offset_delta); 515 } else { 516 same_frame_1_stack_item_extended::create_at( 517 frame_addr, new_offset_delta, NULL); 518 // the verification_info_type should already be at the right spot 519 } 520 } 521 offset_adjusted = true; // needs to be done only once, since subsequent 522 // values are offsets from the current 523 } 524 525 // The stack map frame may contain verification types, if so we need to 526 // check and update any Uninitialized type's bci (no matter where it is). 527 int number_of_types = frame->number_of_types(); 528 verification_type_info* types = frame->types(); 529 530 for (int i = 0; i < number_of_types; ++i) { 531 if (types->is_uninitialized() && types->bci() > bci) { 532 types->set_bci(types->bci() + delta); 533 } 534 types = types->next(); 535 } 536 537 // Full frame has stack values too 538 full_frame* ff = frame->as_full_frame(); 539 if (ff != NULL) { 540 address eol = (address)types; 541 number_of_types = ff->stack_slots(eol); 542 types = ff->stack(eol); 543 for (int i = 0; i < number_of_types; ++i) { 544 if (types->is_uninitialized() && types->bci() > bci) { 545 types->set_bci(types->bci() + delta); 546 } 547 types = types->next(); 548 } 549 } 550 551 frame = frame->next(); 552 } 553 554 method()->set_stackmap_data(data); // in case it has changed 555 } 556 } 557 558 559 bool Relocator::expand_code_array(int delta) { 560 int length = MAX2(code_length() + delta, code_length() * (100+code_slop_pct()) / 100); 561 562 if (length > MAX_METHOD_LENGTH) { 563 if (delta == 0 && code_length() <= MAX_METHOD_LENGTH) { 564 length = MAX_METHOD_LENGTH; 565 } else { 566 return false; 567 } 568 } 569 570 unsigned char* new_code_array = NEW_RESOURCE_ARRAY(unsigned char, length); 571 if (!new_code_array) return false; 572 573 // Expanding current array 574 if (code_array() != NULL) { 575 memcpy(new_code_array, code_array(), code_length()); 576 } else { 577 // Initial copy. Copy directly from methodOop 578 memcpy(new_code_array, method()->code_base(), code_length()); 579 } 580 581 set_code_array(new_code_array); 582 set_code_array_length(length); 583 584 return true; 585 } 586 587 588 // The instruction at "bci", whose size is "ilen", is changing size by 589 // "delta". Reallocate, move code, recalculate jumps, and enqueue 590 // change items as necessary. 591 bool Relocator::relocate_code(int bci, int ilen, int delta) { 592 int next_bci = bci + ilen; 593 if (delta > 0 && code_length() + delta > code_array_length()) { 594 // Expand allocated code space, if necessary. 595 if (!expand_code_array(delta)) { 596 return false; 597 } 598 } 599 600 // We require 4-byte alignment of code arrays. 601 assert(((intptr_t)code_array() & 3) == 0, "check code alignment"); 602 // Change jumps before doing the copying; this routine requires aligned switches. 603 change_jumps(bci, delta); 604 605 // In case we have shrunken a tableswitch/lookupswitch statement, we store the last 606 // bytes that get overwritten. We have to copy the bytes after the change_jumps method 607 // has been called, since it is likly to update last offset in a tableswitch/lookupswitch 608 if (delta < 0) { 609 assert(delta>=-3, "we cannot overwrite more than 3 bytes"); 610 memcpy(_overwrite, addr_at(bci + ilen + delta), -delta); 611 } 612 613 memmove(addr_at(next_bci + delta), addr_at(next_bci), code_length() - next_bci); 614 set_code_length(code_length() + delta); 615 // Also adjust exception tables... 616 adjust_exception_table(bci, delta); 617 // Line number tables... 618 adjust_line_no_table(bci, delta); 619 // And local variable table... 620 adjust_local_var_table(bci, delta); 621 622 // Adjust stack maps 623 adjust_stack_map_table(bci, delta); 624 625 // Relocate the pending change stack... 626 for (int j = 0; j < _changes->length(); j++) { 627 ChangeItem* ci = _changes->at(j); 628 ci->relocate(bci, delta); 629 } 630 631 // Notify any listeners about code relocation 632 notify(bci, delta, code_length()); 633 634 return true; 635 } 636 637 // relocate a general instruction. Called by ChangeWiden class 638 bool Relocator::handle_widen(int bci, int new_ilen, u_char inst_buffer[]) { 639 int ilen = rc_instr_len(bci); 640 if (!relocate_code(bci, ilen, new_ilen - ilen)) 641 return false; 642 643 // Insert new bytecode(s) 644 for(int k = 0; k < new_ilen; k++) { 645 code_at_put(bci + k, (Bytecodes::Code)inst_buffer[k]); 646 } 647 648 return true; 649 } 650 651 // handle jump_widen instruction. Called be ChangeJumpWiden class 652 bool Relocator::handle_jump_widen(int bci, int delta) { 653 int ilen = rc_instr_len(bci); 654 655 Bytecodes::Code bc = code_at(bci); 656 switch (bc) { 657 case Bytecodes::_ifeq: 658 case Bytecodes::_ifne: 659 case Bytecodes::_iflt: 660 case Bytecodes::_ifge: 661 case Bytecodes::_ifgt: 662 case Bytecodes::_ifle: 663 case Bytecodes::_if_icmpeq: 664 case Bytecodes::_if_icmpne: 665 case Bytecodes::_if_icmplt: 666 case Bytecodes::_if_icmpge: 667 case Bytecodes::_if_icmpgt: 668 case Bytecodes::_if_icmple: 669 case Bytecodes::_if_acmpeq: 670 case Bytecodes::_if_acmpne: 671 case Bytecodes::_ifnull: 672 case Bytecodes::_ifnonnull: { 673 const int goto_length = Bytecodes::length_for(Bytecodes::_goto); 674 675 // If 'if' points to the next bytecode after goto, it's already handled. 676 // it shouldn't be. 677 assert (short_at(bci+1) != ilen+goto_length, "if relocation already handled"); 678 assert(ilen == 3, "check length"); 679 680 // Convert to 0 if <cond> goto 6 681 // 3 _goto 11 682 // 6 _goto_w <wide delta offset> 683 // 11 <else code> 684 const int goto_w_length = Bytecodes::length_for(Bytecodes::_goto_w); 685 const int add_bci = goto_length + goto_w_length; 686 687 if (!relocate_code(bci, 3, /*delta*/add_bci)) return false; 688 689 // if bytecode points to goto_w instruction 690 short_at_put(bci + 1, ilen + goto_length); 691 692 int cbci = bci + ilen; 693 // goto around 694 code_at_put(cbci, Bytecodes::_goto); 695 short_at_put(cbci + 1, add_bci); 696 // goto_w <wide delta> 697 cbci = cbci + goto_length; 698 code_at_put(cbci, Bytecodes::_goto_w); 699 if (delta > 0) { 700 delta += 2; // goto_w is 2 bytes more than "if" code 701 } else { 702 delta -= ilen+goto_length; // branch starts at goto_w offset 703 } 704 int_at_put(cbci + 1, delta); 705 break; 706 707 } 708 case Bytecodes::_goto: 709 case Bytecodes::_jsr: 710 assert(ilen == 3, "check length"); 711 712 if (!relocate_code(bci, 3, 2)) return false; 713 if (bc == Bytecodes::_goto) 714 code_at_put(bci, Bytecodes::_goto_w); 715 else 716 code_at_put(bci, Bytecodes::_jsr_w); 717 718 // If it's a forward jump, add 2 for the widening. 719 if (delta > 0) delta += 2; 720 int_at_put(bci + 1, delta); 721 break; 722 723 default: ShouldNotReachHere(); 724 } 725 726 return true; 727 } 728 729 // handle lookup/table switch instructions. Called be ChangeSwitchPad class 730 bool Relocator::handle_switch_pad(int bci, int old_pad, bool is_lookup_switch) { 731 int ilen = rc_instr_len(bci); 732 int new_pad = align(bci+1) - (bci+1); 733 int pad_delta = new_pad - old_pad; 734 if (pad_delta != 0) { 735 int len; 736 if (!is_lookup_switch) { 737 int low = int_at(bci+1+old_pad+4); 738 int high = int_at(bci+1+old_pad+8); 739 len = high-low+1 + 3; // 3 for default, hi, lo. 740 } else { 741 int npairs = int_at(bci+1+old_pad+4); 742 len = npairs*2 + 2; // 2 for default, npairs. 743 } 744 // Because "relocateCode" does a "changeJumps" loop, 745 // which parses instructions to determine their length, 746 // we need to call that before messing with the current 747 // instruction. Since it may also overwrite the current 748 // instruction when moving down, remember the possibly 749 // overwritten part. 750 751 // Move the code following the instruction... 752 if (!relocate_code(bci, ilen, pad_delta)) return false; 753 754 if (pad_delta < 0) { 755 // Move the shrunken instruction down. 756 memmove(addr_at(bci + 1 + new_pad), 757 addr_at(bci + 1 + old_pad), 758 len * 4 + pad_delta); 759 memmove(addr_at(bci + 1 + new_pad + len*4 + pad_delta), 760 _overwrite, -pad_delta); 761 } else { 762 assert(pad_delta > 0, "check"); 763 // Move the expanded instruction up. 764 memmove(addr_at(bci +1 + new_pad), 765 addr_at(bci +1 + old_pad), 766 len * 4); 767 memset(addr_at(bci + 1), 0, new_pad); // pad must be 0 768 } 769 } 770 return true; 771 }