1 /* 2 * Copyright (c) 2005, 2023, 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 "ci/ciArrayKlass.hpp" 27 #include "ci/ciEnv.hpp" 28 #include "ci/ciKlass.hpp" 29 #include "ci/ciMethod.hpp" 30 #include "classfile/javaClasses.inline.hpp" 31 #include "classfile/vmClasses.hpp" 32 #include "code/dependencies.hpp" 33 #include "compiler/compileLog.hpp" 34 #include "compiler/compileBroker.hpp" 35 #include "compiler/compileTask.hpp" 36 #include "memory/resourceArea.hpp" 37 #include "oops/klass.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "oops/method.inline.hpp" 40 #include "oops/objArrayKlass.hpp" 41 #include "runtime/flags/flagSetting.hpp" 42 #include "runtime/handles.hpp" 43 #include "runtime/handles.inline.hpp" 44 #include "runtime/javaThread.inline.hpp" 45 #include "runtime/jniHandles.inline.hpp" 46 #include "runtime/mutexLocker.hpp" 47 #include "runtime/perfData.hpp" 48 #include "runtime/vmThread.hpp" 49 #include "utilities/copy.hpp" 50 51 52 #ifdef ASSERT 53 static bool must_be_in_vm() { 54 Thread* thread = Thread::current(); 55 if (thread->is_Java_thread()) { 56 return JavaThread::cast(thread)->thread_state() == _thread_in_vm; 57 } else { 58 return true; // Could be VMThread or GC thread 59 } 60 } 61 #endif //ASSERT 62 63 bool Dependencies::_verify_in_progress = false; // don't -Xlog:dependencies 64 65 void Dependencies::initialize(ciEnv* env) { 66 Arena* arena = env->arena(); 67 _oop_recorder = env->oop_recorder(); 68 _log = env->log(); 69 _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0); 70 #if INCLUDE_JVMCI 71 _using_dep_values = false; 72 #endif 73 DEBUG_ONLY(_deps[end_marker] = nullptr); 74 for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) { 75 _deps[i] = new(arena) GrowableArray<ciBaseObject*>(arena, 10, 0, 0); 76 } 77 _content_bytes = nullptr; 78 _size_in_bytes = (size_t)-1; 79 80 assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity"); 81 } 82 83 void Dependencies::assert_evol_method(ciMethod* m) { 84 assert_common_1(evol_method, m); 85 } 86 87 void Dependencies::assert_leaf_type(ciKlass* ctxk) { 88 if (ctxk->is_array_klass()) { 89 // As a special case, support this assertion on an array type, 90 // which reduces to an assertion on its element type. 91 // Note that this cannot be done with assertions that 92 // relate to concreteness or abstractness. 93 ciType* elemt = ctxk->as_array_klass()->base_element_type(); 94 if (!elemt->is_instance_klass()) return; // Ex: int[][] 95 ctxk = elemt->as_instance_klass(); 96 //if (ctxk->is_final()) return; // Ex: String[][] 97 } 98 check_ctxk(ctxk); 99 assert_common_1(leaf_type, ctxk); 100 } 101 102 void Dependencies::assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck) { 103 check_ctxk_abstract(ctxk); 104 assert_common_2(abstract_with_unique_concrete_subtype, ctxk, conck); 105 } 106 107 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm) { 108 check_ctxk(ctxk); 109 check_unique_method(ctxk, uniqm); 110 assert_common_2(unique_concrete_method_2, ctxk, uniqm); 111 } 112 113 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method) { 114 check_ctxk(ctxk); 115 check_unique_method(ctxk, uniqm); 116 if (UseVtableBasedCHA) { 117 assert_common_4(unique_concrete_method_4, ctxk, uniqm, resolved_klass, resolved_method); 118 } else { 119 assert_common_2(unique_concrete_method_2, ctxk, uniqm); 120 } 121 } 122 123 void Dependencies::assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) { 124 check_ctxk(ctxk); 125 check_unique_implementor(ctxk, uniqk); 126 assert_common_2(unique_implementor, ctxk, uniqk); 127 } 128 129 void Dependencies::assert_has_no_finalizable_subclasses(ciKlass* ctxk) { 130 check_ctxk(ctxk); 131 assert_common_1(no_finalizable_subclasses, ctxk); 132 } 133 134 void Dependencies::assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle) { 135 assert_common_2(call_site_target_value, call_site, method_handle); 136 } 137 138 #if INCLUDE_JVMCI 139 140 Dependencies::Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log) { 141 _oop_recorder = oop_recorder; 142 _log = log; 143 _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0); 144 _using_dep_values = true; 145 DEBUG_ONLY(_dep_values[end_marker] = nullptr); 146 for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) { 147 _dep_values[i] = new(arena) GrowableArray<DepValue>(arena, 10, 0, DepValue()); 148 } 149 _content_bytes = nullptr; 150 _size_in_bytes = (size_t)-1; 151 152 assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity"); 153 } 154 155 void Dependencies::assert_evol_method(Method* m) { 156 assert_common_1(evol_method, DepValue(_oop_recorder, m)); 157 } 158 159 void Dependencies::assert_has_no_finalizable_subclasses(Klass* ctxk) { 160 check_ctxk(ctxk); 161 assert_common_1(no_finalizable_subclasses, DepValue(_oop_recorder, ctxk)); 162 } 163 164 void Dependencies::assert_leaf_type(Klass* ctxk) { 165 if (ctxk->is_array_klass()) { 166 // As a special case, support this assertion on an array type, 167 // which reduces to an assertion on its element type. 168 // Note that this cannot be done with assertions that 169 // relate to concreteness or abstractness. 170 BasicType elemt = ArrayKlass::cast(ctxk)->element_type(); 171 if (is_java_primitive(elemt)) return; // Ex: int[][] 172 ctxk = ObjArrayKlass::cast(ctxk)->bottom_klass(); 173 //if (ctxk->is_final()) return; // Ex: String[][] 174 } 175 check_ctxk(ctxk); 176 assert_common_1(leaf_type, DepValue(_oop_recorder, ctxk)); 177 } 178 179 void Dependencies::assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck) { 180 check_ctxk_abstract(ctxk); 181 DepValue ctxk_dv(_oop_recorder, ctxk); 182 DepValue conck_dv(_oop_recorder, conck, &ctxk_dv); 183 assert_common_2(abstract_with_unique_concrete_subtype, ctxk_dv, conck_dv); 184 } 185 186 void Dependencies::assert_unique_implementor(InstanceKlass* ctxk, InstanceKlass* uniqk) { 187 check_ctxk(ctxk); 188 assert(ctxk->is_interface(), "not an interface"); 189 assert(ctxk->implementor() == uniqk, "not a unique implementor"); 190 assert_common_2(unique_implementor, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqk)); 191 } 192 193 void Dependencies::assert_unique_concrete_method(Klass* ctxk, Method* uniqm) { 194 check_ctxk(ctxk); 195 check_unique_method(ctxk, uniqm); 196 assert_common_2(unique_concrete_method_2, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqm)); 197 } 198 199 void Dependencies::assert_call_site_target_value(oop call_site, oop method_handle) { 200 assert_common_2(call_site_target_value, DepValue(_oop_recorder, JNIHandles::make_local(call_site)), DepValue(_oop_recorder, JNIHandles::make_local(method_handle))); 201 } 202 203 #endif // INCLUDE_JVMCI 204 205 206 // Helper function. If we are adding a new dep. under ctxk2, 207 // try to find an old dep. under a broader* ctxk1. If there is 208 // 209 bool Dependencies::maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps, 210 int ctxk_i, ciKlass* ctxk2) { 211 ciKlass* ctxk1 = deps->at(ctxk_i)->as_metadata()->as_klass(); 212 if (ctxk2->is_subtype_of(ctxk1)) { 213 return true; // success, and no need to change 214 } else if (ctxk1->is_subtype_of(ctxk2)) { 215 // new context class fully subsumes previous one 216 deps->at_put(ctxk_i, ctxk2); 217 return true; 218 } else { 219 return false; 220 } 221 } 222 223 void Dependencies::assert_common_1(DepType dept, ciBaseObject* x) { 224 assert(dep_args(dept) == 1, "sanity"); 225 log_dependency(dept, x); 226 GrowableArray<ciBaseObject*>* deps = _deps[dept]; 227 228 // see if the same (or a similar) dep is already recorded 229 if (note_dep_seen(dept, x)) { 230 assert(deps->find(x) >= 0, "sanity"); 231 } else { 232 deps->append(x); 233 } 234 } 235 236 void Dependencies::assert_common_2(DepType dept, 237 ciBaseObject* x0, ciBaseObject* x1) { 238 assert(dep_args(dept) == 2, "sanity"); 239 log_dependency(dept, x0, x1); 240 GrowableArray<ciBaseObject*>* deps = _deps[dept]; 241 242 // see if the same (or a similar) dep is already recorded 243 bool has_ctxk = has_explicit_context_arg(dept); 244 if (has_ctxk) { 245 assert(dep_context_arg(dept) == 0, "sanity"); 246 if (note_dep_seen(dept, x1)) { 247 // look in this bucket for redundant assertions 248 const int stride = 2; 249 for (int i = deps->length(); (i -= stride) >= 0; ) { 250 ciBaseObject* y1 = deps->at(i+1); 251 if (x1 == y1) { // same subject; check the context 252 if (maybe_merge_ctxk(deps, i+0, x0->as_metadata()->as_klass())) { 253 return; 254 } 255 } 256 } 257 } 258 } else { 259 bool dep_seen_x0 = note_dep_seen(dept, x0); // records x0 for future queries 260 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries 261 if (dep_seen_x0 && dep_seen_x1) { 262 // look in this bucket for redundant assertions 263 const int stride = 2; 264 for (int i = deps->length(); (i -= stride) >= 0; ) { 265 ciBaseObject* y0 = deps->at(i+0); 266 ciBaseObject* y1 = deps->at(i+1); 267 if (x0 == y0 && x1 == y1) { 268 return; 269 } 270 } 271 } 272 } 273 274 // append the assertion in the correct bucket: 275 deps->append(x0); 276 deps->append(x1); 277 } 278 279 void Dependencies::assert_common_4(DepType dept, 280 ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3) { 281 assert(has_explicit_context_arg(dept), "sanity"); 282 assert(dep_context_arg(dept) == 0, "sanity"); 283 assert(dep_args(dept) == 4, "sanity"); 284 log_dependency(dept, ctxk, x1, x2, x3); 285 GrowableArray<ciBaseObject*>* deps = _deps[dept]; 286 287 // see if the same (or a similar) dep is already recorded 288 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries 289 bool dep_seen_x2 = note_dep_seen(dept, x2); // records x2 for future queries 290 bool dep_seen_x3 = note_dep_seen(dept, x3); // records x3 for future queries 291 if (dep_seen_x1 && dep_seen_x2 && dep_seen_x3) { 292 // look in this bucket for redundant assertions 293 const int stride = 4; 294 for (int i = deps->length(); (i -= stride) >= 0; ) { 295 ciBaseObject* y1 = deps->at(i+1); 296 ciBaseObject* y2 = deps->at(i+2); 297 ciBaseObject* y3 = deps->at(i+3); 298 if (x1 == y1 && x2 == y2 && x3 == y3) { // same subjects; check the context 299 if (maybe_merge_ctxk(deps, i+0, ctxk)) { 300 return; 301 } 302 } 303 } 304 } 305 // append the assertion in the correct bucket: 306 deps->append(ctxk); 307 deps->append(x1); 308 deps->append(x2); 309 deps->append(x3); 310 } 311 312 #if INCLUDE_JVMCI 313 bool Dependencies::maybe_merge_ctxk(GrowableArray<DepValue>* deps, 314 int ctxk_i, DepValue ctxk2_dv) { 315 Klass* ctxk1 = deps->at(ctxk_i).as_klass(_oop_recorder); 316 Klass* ctxk2 = ctxk2_dv.as_klass(_oop_recorder); 317 if (ctxk2->is_subtype_of(ctxk1)) { 318 return true; // success, and no need to change 319 } else if (ctxk1->is_subtype_of(ctxk2)) { 320 // new context class fully subsumes previous one 321 deps->at_put(ctxk_i, ctxk2_dv); 322 return true; 323 } else { 324 return false; 325 } 326 } 327 328 void Dependencies::assert_common_1(DepType dept, DepValue x) { 329 assert(dep_args(dept) == 1, "sanity"); 330 //log_dependency(dept, x); 331 GrowableArray<DepValue>* deps = _dep_values[dept]; 332 333 // see if the same (or a similar) dep is already recorded 334 if (note_dep_seen(dept, x)) { 335 assert(deps->find(x) >= 0, "sanity"); 336 } else { 337 deps->append(x); 338 } 339 } 340 341 void Dependencies::assert_common_2(DepType dept, 342 DepValue x0, DepValue x1) { 343 assert(dep_args(dept) == 2, "sanity"); 344 //log_dependency(dept, x0, x1); 345 GrowableArray<DepValue>* deps = _dep_values[dept]; 346 347 // see if the same (or a similar) dep is already recorded 348 bool has_ctxk = has_explicit_context_arg(dept); 349 if (has_ctxk) { 350 assert(dep_context_arg(dept) == 0, "sanity"); 351 if (note_dep_seen(dept, x1)) { 352 // look in this bucket for redundant assertions 353 const int stride = 2; 354 for (int i = deps->length(); (i -= stride) >= 0; ) { 355 DepValue y1 = deps->at(i+1); 356 if (x1 == y1) { // same subject; check the context 357 if (maybe_merge_ctxk(deps, i+0, x0)) { 358 return; 359 } 360 } 361 } 362 } 363 } else { 364 bool dep_seen_x0 = note_dep_seen(dept, x0); // records x0 for future queries 365 bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries 366 if (dep_seen_x0 && dep_seen_x1) { 367 // look in this bucket for redundant assertions 368 const int stride = 2; 369 for (int i = deps->length(); (i -= stride) >= 0; ) { 370 DepValue y0 = deps->at(i+0); 371 DepValue y1 = deps->at(i+1); 372 if (x0 == y0 && x1 == y1) { 373 return; 374 } 375 } 376 } 377 } 378 379 // append the assertion in the correct bucket: 380 deps->append(x0); 381 deps->append(x1); 382 } 383 #endif // INCLUDE_JVMCI 384 385 /// Support for encoding dependencies into an nmethod: 386 387 void Dependencies::copy_to(nmethod* nm) { 388 address beg = nm->dependencies_begin(); 389 address end = nm->dependencies_end(); 390 guarantee(end - beg >= (ptrdiff_t) size_in_bytes(), "bad sizing"); 391 Copy::disjoint_words((HeapWord*) content_bytes(), 392 (HeapWord*) beg, 393 size_in_bytes() / sizeof(HeapWord)); 394 assert(size_in_bytes() % sizeof(HeapWord) == 0, "copy by words"); 395 } 396 397 static int sort_dep(ciBaseObject** p1, ciBaseObject** p2, int narg) { 398 for (int i = 0; i < narg; i++) { 399 int diff = p1[i]->ident() - p2[i]->ident(); 400 if (diff != 0) return diff; 401 } 402 return 0; 403 } 404 static int sort_dep_arg_1(ciBaseObject** p1, ciBaseObject** p2) 405 { return sort_dep(p1, p2, 1); } 406 static int sort_dep_arg_2(ciBaseObject** p1, ciBaseObject** p2) 407 { return sort_dep(p1, p2, 2); } 408 static int sort_dep_arg_3(ciBaseObject** p1, ciBaseObject** p2) 409 { return sort_dep(p1, p2, 3); } 410 static int sort_dep_arg_4(ciBaseObject** p1, ciBaseObject** p2) 411 { return sort_dep(p1, p2, 4); } 412 413 #if INCLUDE_JVMCI 414 // metadata deps are sorted before object deps 415 static int sort_dep_value(Dependencies::DepValue* p1, Dependencies::DepValue* p2, int narg) { 416 for (int i = 0; i < narg; i++) { 417 int diff = p1[i].sort_key() - p2[i].sort_key(); 418 if (diff != 0) return diff; 419 } 420 return 0; 421 } 422 static int sort_dep_value_arg_1(Dependencies::DepValue* p1, Dependencies::DepValue* p2) 423 { return sort_dep_value(p1, p2, 1); } 424 static int sort_dep_value_arg_2(Dependencies::DepValue* p1, Dependencies::DepValue* p2) 425 { return sort_dep_value(p1, p2, 2); } 426 static int sort_dep_value_arg_3(Dependencies::DepValue* p1, Dependencies::DepValue* p2) 427 { return sort_dep_value(p1, p2, 3); } 428 #endif // INCLUDE_JVMCI 429 430 void Dependencies::sort_all_deps() { 431 #if INCLUDE_JVMCI 432 if (_using_dep_values) { 433 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) { 434 DepType dept = (DepType)deptv; 435 GrowableArray<DepValue>* deps = _dep_values[dept]; 436 if (deps->length() <= 1) continue; 437 switch (dep_args(dept)) { 438 case 1: deps->sort(sort_dep_value_arg_1, 1); break; 439 case 2: deps->sort(sort_dep_value_arg_2, 2); break; 440 case 3: deps->sort(sort_dep_value_arg_3, 3); break; 441 default: ShouldNotReachHere(); break; 442 } 443 } 444 return; 445 } 446 #endif // INCLUDE_JVMCI 447 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) { 448 DepType dept = (DepType)deptv; 449 GrowableArray<ciBaseObject*>* deps = _deps[dept]; 450 if (deps->length() <= 1) continue; 451 switch (dep_args(dept)) { 452 case 1: deps->sort(sort_dep_arg_1, 1); break; 453 case 2: deps->sort(sort_dep_arg_2, 2); break; 454 case 3: deps->sort(sort_dep_arg_3, 3); break; 455 case 4: deps->sort(sort_dep_arg_4, 4); break; 456 default: ShouldNotReachHere(); break; 457 } 458 } 459 } 460 461 size_t Dependencies::estimate_size_in_bytes() { 462 size_t est_size = 100; 463 #if INCLUDE_JVMCI 464 if (_using_dep_values) { 465 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) { 466 DepType dept = (DepType)deptv; 467 GrowableArray<DepValue>* deps = _dep_values[dept]; 468 est_size += deps->length() * 2; // tags and argument(s) 469 } 470 return est_size; 471 } 472 #endif // INCLUDE_JVMCI 473 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) { 474 DepType dept = (DepType)deptv; 475 GrowableArray<ciBaseObject*>* deps = _deps[dept]; 476 est_size += deps->length()*2; // tags and argument(s) 477 } 478 return est_size; 479 } 480 481 ciKlass* Dependencies::ctxk_encoded_as_null(DepType dept, ciBaseObject* x) { 482 switch (dept) { 483 case unique_concrete_method_2: 484 case unique_concrete_method_4: 485 return x->as_metadata()->as_method()->holder(); 486 default: 487 return nullptr; // let nullptr be nullptr 488 } 489 } 490 491 Klass* Dependencies::ctxk_encoded_as_null(DepType dept, Metadata* x) { 492 assert(must_be_in_vm(), "raw oops here"); 493 switch (dept) { 494 case unique_concrete_method_2: 495 case unique_concrete_method_4: 496 assert(x->is_method(), "sanity"); 497 return ((Method*)x)->method_holder(); 498 default: 499 return nullptr; // let nullptr be nullptr 500 } 501 } 502 503 void Dependencies::encode_content_bytes() { 504 sort_all_deps(); 505 506 // cast is safe, no deps can overflow INT_MAX 507 CompressedWriteStream bytes((int)estimate_size_in_bytes()); 508 509 #if INCLUDE_JVMCI 510 if (_using_dep_values) { 511 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) { 512 DepType dept = (DepType)deptv; 513 GrowableArray<DepValue>* deps = _dep_values[dept]; 514 if (deps->length() == 0) continue; 515 int stride = dep_args(dept); 516 int ctxkj = dep_context_arg(dept); // -1 if no context arg 517 assert(stride > 0, "sanity"); 518 for (int i = 0; i < deps->length(); i += stride) { 519 jbyte code_byte = (jbyte)dept; 520 int skipj = -1; 521 if (ctxkj >= 0 && ctxkj+1 < stride) { 522 Klass* ctxk = deps->at(i+ctxkj+0).as_klass(_oop_recorder); 523 DepValue x = deps->at(i+ctxkj+1); // following argument 524 if (ctxk == ctxk_encoded_as_null(dept, x.as_metadata(_oop_recorder))) { 525 skipj = ctxkj; // we win: maybe one less oop to keep track of 526 code_byte |= default_context_type_bit; 527 } 528 } 529 bytes.write_byte(code_byte); 530 for (int j = 0; j < stride; j++) { 531 if (j == skipj) continue; 532 DepValue v = deps->at(i+j); 533 int idx = v.index(); 534 bytes.write_int(idx); 535 } 536 } 537 } 538 } else { 539 #endif // INCLUDE_JVMCI 540 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) { 541 DepType dept = (DepType)deptv; 542 GrowableArray<ciBaseObject*>* deps = _deps[dept]; 543 if (deps->length() == 0) continue; 544 int stride = dep_args(dept); 545 int ctxkj = dep_context_arg(dept); // -1 if no context arg 546 assert(stride > 0, "sanity"); 547 for (int i = 0; i < deps->length(); i += stride) { 548 jbyte code_byte = (jbyte)dept; 549 int skipj = -1; 550 if (ctxkj >= 0 && ctxkj+1 < stride) { 551 ciKlass* ctxk = deps->at(i+ctxkj+0)->as_metadata()->as_klass(); 552 ciBaseObject* x = deps->at(i+ctxkj+1); // following argument 553 if (ctxk == ctxk_encoded_as_null(dept, x)) { 554 skipj = ctxkj; // we win: maybe one less oop to keep track of 555 code_byte |= default_context_type_bit; 556 } 557 } 558 bytes.write_byte(code_byte); 559 for (int j = 0; j < stride; j++) { 560 if (j == skipj) continue; 561 ciBaseObject* v = deps->at(i+j); 562 int idx; 563 if (v->is_object()) { 564 idx = _oop_recorder->find_index(v->as_object()->constant_encoding()); 565 } else { 566 ciMetadata* meta = v->as_metadata(); 567 idx = _oop_recorder->find_index(meta->constant_encoding()); 568 } 569 bytes.write_int(idx); 570 } 571 } 572 } 573 #if INCLUDE_JVMCI 574 } 575 #endif 576 577 // write a sentinel byte to mark the end 578 bytes.write_byte(end_marker); 579 580 // round it out to a word boundary 581 while (bytes.position() % sizeof(HeapWord) != 0) { 582 bytes.write_byte(end_marker); 583 } 584 585 // check whether the dept byte encoding really works 586 assert((jbyte)default_context_type_bit != 0, "byte overflow"); 587 588 _content_bytes = bytes.buffer(); 589 _size_in_bytes = bytes.position(); 590 } 591 592 593 const char* Dependencies::_dep_name[TYPE_LIMIT] = { 594 "end_marker", 595 "evol_method", 596 "leaf_type", 597 "abstract_with_unique_concrete_subtype", 598 "unique_concrete_method_2", 599 "unique_concrete_method_4", 600 "unique_implementor", 601 "no_finalizable_subclasses", 602 "call_site_target_value" 603 }; 604 605 int Dependencies::_dep_args[TYPE_LIMIT] = { 606 -1,// end_marker 607 1, // evol_method m 608 1, // leaf_type ctxk 609 2, // abstract_with_unique_concrete_subtype ctxk, k 610 2, // unique_concrete_method_2 ctxk, m 611 4, // unique_concrete_method_4 ctxk, m, resolved_klass, resolved_method 612 2, // unique_implementor ctxk, implementor 613 1, // no_finalizable_subclasses ctxk 614 2 // call_site_target_value call_site, method_handle 615 }; 616 617 const char* Dependencies::dep_name(Dependencies::DepType dept) { 618 if (!dept_in_mask(dept, all_types)) return "?bad-dep?"; 619 return _dep_name[dept]; 620 } 621 622 int Dependencies::dep_args(Dependencies::DepType dept) { 623 if (!dept_in_mask(dept, all_types)) return -1; 624 return _dep_args[dept]; 625 } 626 627 void Dependencies::check_valid_dependency_type(DepType dept) { 628 guarantee(FIRST_TYPE <= dept && dept < TYPE_LIMIT, "invalid dependency type: %d", (int) dept); 629 } 630 631 Dependencies::DepType Dependencies::validate_dependencies(CompileTask* task, char** failure_detail) { 632 int klass_violations = 0; 633 DepType result = end_marker; 634 for (Dependencies::DepStream deps(this); deps.next(); ) { 635 Klass* witness = deps.check_dependency(); 636 if (witness != nullptr) { 637 if (klass_violations == 0) { 638 result = deps.type(); 639 if (failure_detail != nullptr && klass_violations == 0) { 640 // Use a fixed size buffer to prevent the string stream from 641 // resizing in the context of an inner resource mark. 642 char* buffer = NEW_RESOURCE_ARRAY(char, O_BUFLEN); 643 stringStream st(buffer, O_BUFLEN); 644 deps.print_dependency(&st, witness, true); 645 *failure_detail = st.as_string(); 646 } 647 } 648 klass_violations++; 649 if (xtty == nullptr) { 650 // If we're not logging then a single violation is sufficient, 651 // otherwise we want to log all the dependences which were 652 // violated. 653 break; 654 } 655 } 656 } 657 658 return result; 659 } 660 661 // for the sake of the compiler log, print out current dependencies: 662 void Dependencies::log_all_dependencies() { 663 if (log() == nullptr) return; 664 ResourceMark rm; 665 for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) { 666 DepType dept = (DepType)deptv; 667 GrowableArray<ciBaseObject*>* deps = _deps[dept]; 668 int deplen = deps->length(); 669 if (deplen == 0) { 670 continue; 671 } 672 int stride = dep_args(dept); 673 GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(stride); 674 for (int i = 0; i < deps->length(); i += stride) { 675 for (int j = 0; j < stride; j++) { 676 // flush out the identities before printing 677 ciargs->push(deps->at(i+j)); 678 } 679 write_dependency_to(log(), dept, ciargs); 680 ciargs->clear(); 681 } 682 guarantee(deplen == deps->length(), "deps array cannot grow inside nested ResoureMark scope"); 683 } 684 } 685 686 void Dependencies::write_dependency_to(CompileLog* log, 687 DepType dept, 688 GrowableArray<DepArgument>* args, 689 Klass* witness) { 690 if (log == nullptr) { 691 return; 692 } 693 ResourceMark rm; 694 ciEnv* env = ciEnv::current(); 695 GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(args->length()); 696 for (GrowableArrayIterator<DepArgument> it = args->begin(); it != args->end(); ++it) { 697 DepArgument arg = *it; 698 if (arg.is_oop()) { 699 ciargs->push(env->get_object(arg.oop_value())); 700 } else { 701 ciargs->push(env->get_metadata(arg.metadata_value())); 702 } 703 } 704 int argslen = ciargs->length(); 705 Dependencies::write_dependency_to(log, dept, ciargs, witness); 706 guarantee(argslen == ciargs->length(), "ciargs array cannot grow inside nested ResoureMark scope"); 707 } 708 709 void Dependencies::write_dependency_to(CompileLog* log, 710 DepType dept, 711 GrowableArray<ciBaseObject*>* args, 712 Klass* witness) { 713 if (log == nullptr) { 714 return; 715 } 716 ResourceMark rm; 717 GrowableArray<int>* argids = new GrowableArray<int>(args->length()); 718 for (GrowableArrayIterator<ciBaseObject*> it = args->begin(); it != args->end(); ++it) { 719 ciBaseObject* obj = *it; 720 if (obj->is_object()) { 721 argids->push(log->identify(obj->as_object())); 722 } else { 723 argids->push(log->identify(obj->as_metadata())); 724 } 725 } 726 if (witness != nullptr) { 727 log->begin_elem("dependency_failed"); 728 } else { 729 log->begin_elem("dependency"); 730 } 731 log->print(" type='%s'", dep_name(dept)); 732 const int ctxkj = dep_context_arg(dept); // -1 if no context arg 733 if (ctxkj >= 0 && ctxkj < argids->length()) { 734 log->print(" ctxk='%d'", argids->at(ctxkj)); 735 } 736 // write remaining arguments, if any. 737 for (int j = 0; j < argids->length(); j++) { 738 if (j == ctxkj) continue; // already logged 739 if (j == 1) { 740 log->print( " x='%d'", argids->at(j)); 741 } else { 742 log->print(" x%d='%d'", j, argids->at(j)); 743 } 744 } 745 if (witness != nullptr) { 746 log->object("witness", witness); 747 log->stamp(); 748 } 749 log->end_elem(); 750 } 751 752 void Dependencies::write_dependency_to(xmlStream* xtty, 753 DepType dept, 754 GrowableArray<DepArgument>* args, 755 Klass* witness) { 756 if (xtty == nullptr) { 757 return; 758 } 759 Thread* thread = Thread::current(); 760 HandleMark rm(thread); 761 ttyLocker ttyl; 762 int ctxkj = dep_context_arg(dept); // -1 if no context arg 763 if (witness != nullptr) { 764 xtty->begin_elem("dependency_failed"); 765 } else { 766 xtty->begin_elem("dependency"); 767 } 768 xtty->print(" type='%s'", dep_name(dept)); 769 if (ctxkj >= 0) { 770 xtty->object("ctxk", args->at(ctxkj).metadata_value()); 771 } 772 // write remaining arguments, if any. 773 for (int j = 0; j < args->length(); j++) { 774 if (j == ctxkj) continue; // already logged 775 DepArgument arg = args->at(j); 776 if (j == 1) { 777 if (arg.is_oop()) { 778 xtty->object("x", Handle(thread, arg.oop_value())); 779 } else { 780 xtty->object("x", arg.metadata_value()); 781 } 782 } else { 783 char xn[12]; 784 os::snprintf_checked(xn, sizeof(xn), "x%d", j); 785 if (arg.is_oop()) { 786 xtty->object(xn, Handle(thread, arg.oop_value())); 787 } else { 788 xtty->object(xn, arg.metadata_value()); 789 } 790 } 791 } 792 if (witness != nullptr) { 793 xtty->object("witness", witness); 794 xtty->stamp(); 795 } 796 xtty->end_elem(); 797 } 798 799 void Dependencies::print_dependency(DepType dept, GrowableArray<DepArgument>* args, 800 Klass* witness, outputStream* st) { 801 ResourceMark rm; 802 ttyLocker ttyl; // keep the following output all in one block 803 st->print_cr("%s of type %s", 804 (witness == nullptr)? "Dependency": "Failed dependency", 805 dep_name(dept)); 806 // print arguments 807 int ctxkj = dep_context_arg(dept); // -1 if no context arg 808 for (int j = 0; j < args->length(); j++) { 809 DepArgument arg = args->at(j); 810 bool put_star = false; 811 if (arg.is_null()) continue; 812 const char* what; 813 if (j == ctxkj) { 814 assert(arg.is_metadata(), "must be"); 815 what = "context"; 816 put_star = !Dependencies::is_concrete_klass((Klass*)arg.metadata_value()); 817 } else if (arg.is_method()) { 818 what = "method "; 819 put_star = !Dependencies::is_concrete_method((Method*)arg.metadata_value(), nullptr); 820 } else if (arg.is_klass()) { 821 what = "class "; 822 } else { 823 what = "object "; 824 } 825 st->print(" %s = %s", what, (put_star? "*": "")); 826 if (arg.is_klass()) { 827 st->print("%s", ((Klass*)arg.metadata_value())->external_name()); 828 } else if (arg.is_method()) { 829 ((Method*)arg.metadata_value())->print_value_on(st); 830 } else if (arg.is_oop()) { 831 arg.oop_value()->print_value_on(st); 832 } else { 833 ShouldNotReachHere(); // Provide impl for this type. 834 } 835 836 st->cr(); 837 } 838 if (witness != nullptr) { 839 bool put_star = !Dependencies::is_concrete_klass(witness); 840 st->print_cr(" witness = %s%s", 841 (put_star? "*": ""), 842 witness->external_name()); 843 } 844 } 845 846 void Dependencies::DepStream::log_dependency(Klass* witness) { 847 if (_deps == nullptr && xtty == nullptr) return; // fast cutout for runtime 848 ResourceMark rm; 849 const int nargs = argument_count(); 850 GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs); 851 for (int j = 0; j < nargs; j++) { 852 if (is_oop_argument(j)) { 853 args->push(argument_oop(j)); 854 } else { 855 args->push(argument(j)); 856 } 857 } 858 int argslen = args->length(); 859 if (_deps != nullptr && _deps->log() != nullptr) { 860 if (ciEnv::current() != nullptr) { 861 Dependencies::write_dependency_to(_deps->log(), type(), args, witness); 862 } else { 863 // Treat the CompileLog as an xmlstream instead 864 Dependencies::write_dependency_to((xmlStream*)_deps->log(), type(), args, witness); 865 } 866 } else { 867 Dependencies::write_dependency_to(xtty, type(), args, witness); 868 } 869 guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope"); 870 } 871 872 void Dependencies::DepStream::print_dependency(outputStream* st, Klass* witness, bool verbose) { 873 ResourceMark rm; 874 int nargs = argument_count(); 875 GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs); 876 for (int j = 0; j < nargs; j++) { 877 if (is_oop_argument(j)) { 878 args->push(argument_oop(j)); 879 } else { 880 args->push(argument(j)); 881 } 882 } 883 int argslen = args->length(); 884 Dependencies::print_dependency(type(), args, witness, st); 885 if (verbose) { 886 if (_code != nullptr) { 887 st->print(" code: "); 888 _code->print_value_on(st); 889 st->cr(); 890 } 891 } 892 guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope"); 893 } 894 895 896 /// Dependency stream support (decodes dependencies from an nmethod): 897 898 #ifdef ASSERT 899 void Dependencies::DepStream::initial_asserts(size_t byte_limit) { 900 assert(must_be_in_vm(), "raw oops here"); 901 _byte_limit = byte_limit; 902 _type = (DepType)(end_marker-1); // defeat "already at end" assert 903 assert((_code!=nullptr) + (_deps!=nullptr) == 1, "one or t'other"); 904 } 905 #endif //ASSERT 906 907 bool Dependencies::DepStream::next() { 908 assert(_type != end_marker, "already at end"); 909 if (_bytes.position() == 0 && _code != nullptr 910 && _code->dependencies_size() == 0) { 911 // Method has no dependencies at all. 912 return false; 913 } 914 int code_byte = (_bytes.read_byte() & 0xFF); 915 if (code_byte == end_marker) { 916 DEBUG_ONLY(_type = end_marker); 917 return false; 918 } else { 919 int ctxk_bit = (code_byte & Dependencies::default_context_type_bit); 920 code_byte -= ctxk_bit; 921 DepType dept = (DepType)code_byte; 922 _type = dept; 923 Dependencies::check_valid_dependency_type(dept); 924 int stride = _dep_args[dept]; 925 assert(stride == dep_args(dept), "sanity"); 926 int skipj = -1; 927 if (ctxk_bit != 0) { 928 skipj = 0; // currently the only context argument is at zero 929 assert(skipj == dep_context_arg(dept), "zero arg always ctxk"); 930 } 931 for (int j = 0; j < stride; j++) { 932 _xi[j] = (j == skipj)? 0: _bytes.read_int(); 933 } 934 DEBUG_ONLY(_xi[stride] = -1); // help detect overruns 935 return true; 936 } 937 } 938 939 inline Metadata* Dependencies::DepStream::recorded_metadata_at(int i) { 940 Metadata* o = nullptr; 941 if (_code != nullptr) { 942 o = _code->metadata_at(i); 943 } else { 944 o = _deps->oop_recorder()->metadata_at(i); 945 } 946 return o; 947 } 948 949 inline oop Dependencies::DepStream::recorded_oop_at(int i) { 950 return (_code != nullptr) 951 ? _code->oop_at(i) 952 : JNIHandles::resolve(_deps->oop_recorder()->oop_at(i)); 953 } 954 955 Metadata* Dependencies::DepStream::argument(int i) { 956 Metadata* result = recorded_metadata_at(argument_index(i)); 957 958 if (result == nullptr) { // Explicit context argument can be compressed 959 int ctxkj = dep_context_arg(type()); // -1 if no explicit context arg 960 if (ctxkj >= 0 && i == ctxkj && ctxkj+1 < argument_count()) { 961 result = ctxk_encoded_as_null(type(), argument(ctxkj+1)); 962 } 963 } 964 965 assert(result == nullptr || result->is_klass() || result->is_method(), "must be"); 966 return result; 967 } 968 969 /** 970 * Returns a unique identifier for each dependency argument. 971 */ 972 uintptr_t Dependencies::DepStream::get_identifier(int i) { 973 if (is_oop_argument(i)) { 974 return (uintptr_t)(oopDesc*)argument_oop(i); 975 } else { 976 return (uintptr_t)argument(i); 977 } 978 } 979 980 oop Dependencies::DepStream::argument_oop(int i) { 981 oop result = recorded_oop_at(argument_index(i)); 982 assert(oopDesc::is_oop_or_null(result), "must be"); 983 return result; 984 } 985 986 InstanceKlass* Dependencies::DepStream::context_type() { 987 assert(must_be_in_vm(), "raw oops here"); 988 989 // Most dependencies have an explicit context type argument. 990 { 991 int ctxkj = dep_context_arg(type()); // -1 if no explicit context arg 992 if (ctxkj >= 0) { 993 Metadata* k = argument(ctxkj); 994 assert(k != nullptr && k->is_klass(), "type check"); 995 return InstanceKlass::cast((Klass*)k); 996 } 997 } 998 999 // Some dependencies are using the klass of the first object 1000 // argument as implicit context type. 1001 { 1002 int ctxkj = dep_implicit_context_arg(type()); 1003 if (ctxkj >= 0) { 1004 Klass* k = argument_oop(ctxkj)->klass(); 1005 assert(k != nullptr, "type check"); 1006 return InstanceKlass::cast(k); 1007 } 1008 } 1009 1010 // And some dependencies don't have a context type at all, 1011 // e.g. evol_method. 1012 return nullptr; 1013 } 1014 1015 // ----------------- DependencySignature -------------------------------------- 1016 bool DependencySignature::equals(DependencySignature const& s1, DependencySignature const& s2) { 1017 if ((s1.type() != s2.type()) || (s1.args_count() != s2.args_count())) { 1018 return false; 1019 } 1020 1021 for (int i = 0; i < s1.args_count(); i++) { 1022 if (s1.arg(i) != s2.arg(i)) { 1023 return false; 1024 } 1025 } 1026 return true; 1027 } 1028 1029 /// Checking dependencies 1030 1031 // This hierarchy walker inspects subtypes of a given type, trying to find a "bad" class which breaks a dependency. 1032 // Such a class is called a "witness" to the broken dependency. 1033 // While searching around, we ignore "participants", which are already known to the dependency. 1034 class AbstractClassHierarchyWalker { 1035 public: 1036 enum { PARTICIPANT_LIMIT = 3 }; 1037 1038 private: 1039 // if non-zero, tells how many witnesses to convert to participants 1040 uint _record_witnesses; 1041 1042 // special classes which are not allowed to be witnesses: 1043 Klass* _participants[PARTICIPANT_LIMIT+1]; 1044 uint _num_participants; 1045 1046 #ifdef ASSERT 1047 uint _nof_requests; // one-shot walker 1048 #endif // ASSERT 1049 1050 static PerfCounter* _perf_find_witness_anywhere_calls_count; 1051 static PerfCounter* _perf_find_witness_anywhere_steps_count; 1052 static PerfCounter* _perf_find_witness_in_calls_count; 1053 1054 protected: 1055 virtual Klass* find_witness_in(KlassDepChange& changes) = 0; 1056 virtual Klass* find_witness_anywhere(InstanceKlass* context_type) = 0; 1057 1058 AbstractClassHierarchyWalker(Klass* participant) : _record_witnesses(0), _num_participants(0) 1059 #ifdef ASSERT 1060 , _nof_requests(0) 1061 #endif // ASSERT 1062 { 1063 for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) { 1064 _participants[i] = nullptr; 1065 } 1066 if (participant != nullptr) { 1067 add_participant(participant); 1068 } 1069 } 1070 1071 bool is_participant(Klass* k) { 1072 for (uint i = 0; i < _num_participants; i++) { 1073 if (_participants[i] == k) { 1074 return true; 1075 } 1076 } 1077 return false; 1078 } 1079 1080 bool record_witness(Klass* witness) { 1081 if (_record_witnesses > 0) { 1082 --_record_witnesses; 1083 add_participant(witness); 1084 return false; // not a witness 1085 } else { 1086 return true; // is a witness 1087 } 1088 } 1089 1090 class CountingClassHierarchyIterator : public ClassHierarchyIterator { 1091 private: 1092 jlong _nof_steps; 1093 public: 1094 CountingClassHierarchyIterator(InstanceKlass* root) : ClassHierarchyIterator(root), _nof_steps(0) {} 1095 1096 void next() { 1097 _nof_steps++; 1098 ClassHierarchyIterator::next(); 1099 } 1100 1101 ~CountingClassHierarchyIterator() { 1102 if (UsePerfData) { 1103 _perf_find_witness_anywhere_steps_count->inc(_nof_steps); 1104 } 1105 } 1106 }; 1107 1108 public: 1109 uint num_participants() { return _num_participants; } 1110 Klass* participant(uint n) { 1111 assert(n <= _num_participants, "oob"); 1112 if (n < _num_participants) { 1113 return _participants[n]; 1114 } else { 1115 return nullptr; 1116 } 1117 } 1118 1119 void add_participant(Klass* participant) { 1120 assert(!is_participant(participant), "sanity"); 1121 assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob"); 1122 uint np = _num_participants++; 1123 _participants[np] = participant; 1124 } 1125 1126 void record_witnesses(uint add) { 1127 if (add > PARTICIPANT_LIMIT) add = PARTICIPANT_LIMIT; 1128 assert(_num_participants + add < PARTICIPANT_LIMIT, "oob"); 1129 _record_witnesses = add; 1130 } 1131 1132 Klass* find_witness(InstanceKlass* context_type, KlassDepChange* changes = nullptr); 1133 1134 static void init(); 1135 static void print_statistics(); 1136 }; 1137 1138 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_calls_count = nullptr; 1139 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_steps_count = nullptr; 1140 PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_in_calls_count = nullptr; 1141 1142 void AbstractClassHierarchyWalker::init() { 1143 if (UsePerfData) { 1144 EXCEPTION_MARK; 1145 _perf_find_witness_anywhere_calls_count = 1146 PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhere", PerfData::U_Events, CHECK); 1147 _perf_find_witness_anywhere_steps_count = 1148 PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhereSteps", PerfData::U_Events, CHECK); 1149 _perf_find_witness_in_calls_count = 1150 PerfDataManager::create_counter(SUN_CI, "findWitnessIn", PerfData::U_Events, CHECK); 1151 } 1152 } 1153 1154 Klass* AbstractClassHierarchyWalker::find_witness(InstanceKlass* context_type, KlassDepChange* changes) { 1155 // Current thread must be in VM (not native mode, as in CI): 1156 assert(must_be_in_vm(), "raw oops here"); 1157 // Must not move the class hierarchy during this check: 1158 assert_locked_or_safepoint(Compile_lock); 1159 assert(_nof_requests++ == 0, "repeated requests are not supported"); 1160 1161 assert(changes == nullptr || changes->involves_context(context_type), "irrelevant dependency"); 1162 1163 // (Note: Interfaces do not have subclasses.) 1164 // If it is an interface, search its direct implementors. 1165 // (Their subclasses are additional indirect implementors. See InstanceKlass::add_implementor().) 1166 if (context_type->is_interface()) { 1167 int nof_impls = context_type->nof_implementors(); 1168 if (nof_impls == 0) { 1169 return nullptr; // no implementors 1170 } else if (nof_impls == 1) { // unique implementor 1171 assert(context_type != context_type->implementor(), "not unique"); 1172 context_type = context_type->implementor(); 1173 } else { // nof_impls >= 2 1174 // Avoid this case: *I.m > { A.m, C }; B.m > C 1175 // Here, I.m has 2 concrete implementations, but m appears unique 1176 // as A.m, because the search misses B.m when checking C. 1177 // The inherited method B.m was getting missed by the walker 1178 // when interface 'I' was the starting point. 1179 // %%% Until this is fixed more systematically, bail out. 1180 return context_type; 1181 } 1182 } 1183 assert(!context_type->is_interface(), "no interfaces allowed"); 1184 1185 if (changes != nullptr) { 1186 if (UsePerfData) { 1187 _perf_find_witness_in_calls_count->inc(); 1188 } 1189 return find_witness_in(*changes); 1190 } else { 1191 if (UsePerfData) { 1192 _perf_find_witness_anywhere_calls_count->inc(); 1193 } 1194 return find_witness_anywhere(context_type); 1195 } 1196 } 1197 1198 class ConcreteSubtypeFinder : public AbstractClassHierarchyWalker { 1199 private: 1200 bool is_witness(Klass* k); 1201 1202 protected: 1203 virtual Klass* find_witness_in(KlassDepChange& changes); 1204 virtual Klass* find_witness_anywhere(InstanceKlass* context_type); 1205 1206 public: 1207 ConcreteSubtypeFinder(Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {} 1208 }; 1209 1210 bool ConcreteSubtypeFinder::is_witness(Klass* k) { 1211 if (Dependencies::is_concrete_klass(k)) { 1212 return record_witness(k); // concrete subtype 1213 } else { 1214 return false; // not a concrete class 1215 } 1216 } 1217 1218 Klass* ConcreteSubtypeFinder::find_witness_in(KlassDepChange& changes) { 1219 // When looking for unexpected concrete types, do not look beneath expected ones: 1220 // * CX > CC > C' is OK, even if C' is new. 1221 // * CX > { CC, C' } is not OK if C' is new, and C' is the witness. 1222 Klass* new_type = changes.as_new_klass_change()->new_type(); 1223 assert(!is_participant(new_type), "only old classes are participants"); 1224 // If the new type is a subtype of a participant, we are done. 1225 for (uint i = 0; i < num_participants(); i++) { 1226 if (changes.involves_context(participant(i))) { 1227 // new guy is protected from this check by previous participant 1228 return nullptr; 1229 } 1230 } 1231 if (is_witness(new_type)) { 1232 return new_type; 1233 } 1234 // No witness found. The dependency remains unbroken. 1235 return nullptr; 1236 } 1237 1238 Klass* ConcreteSubtypeFinder::find_witness_anywhere(InstanceKlass* context_type) { 1239 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) { 1240 Klass* sub = iter.klass(); 1241 // Do not report participant types. 1242 if (is_participant(sub)) { 1243 // Don't walk beneath a participant since it hides witnesses. 1244 iter.skip_subclasses(); 1245 } else if (is_witness(sub)) { 1246 return sub; // found a witness 1247 } 1248 } 1249 // No witness found. The dependency remains unbroken. 1250 return nullptr; 1251 } 1252 1253 class ConcreteMethodFinder : public AbstractClassHierarchyWalker { 1254 private: 1255 Symbol* _name; 1256 Symbol* _signature; 1257 1258 // cache of method lookups 1259 Method* _found_methods[PARTICIPANT_LIMIT+1]; 1260 1261 bool is_witness(Klass* k); 1262 1263 protected: 1264 virtual Klass* find_witness_in(KlassDepChange& changes); 1265 virtual Klass* find_witness_anywhere(InstanceKlass* context_type); 1266 1267 public: 1268 bool witnessed_reabstraction_in_supers(Klass* k); 1269 1270 ConcreteMethodFinder(Method* m, Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) { 1271 assert(m != nullptr && m->is_method(), "sanity"); 1272 _name = m->name(); 1273 _signature = m->signature(); 1274 1275 for (int i = 0; i < PARTICIPANT_LIMIT+1; i++) { 1276 _found_methods[i] = nullptr; 1277 } 1278 } 1279 1280 // Note: If n==num_participants, returns nullptr. 1281 Method* found_method(uint n) { 1282 assert(n <= num_participants(), "oob"); 1283 Method* fm = _found_methods[n]; 1284 assert(n == num_participants() || fm != nullptr, "proper usage"); 1285 if (fm != nullptr && fm->method_holder() != participant(n)) { 1286 // Default methods from interfaces can be added to classes. In 1287 // that case the holder of the method is not the class but the 1288 // interface where it's defined. 1289 assert(fm->is_default_method(), "sanity"); 1290 return nullptr; 1291 } 1292 return fm; 1293 } 1294 1295 void add_participant(Klass* participant) { 1296 AbstractClassHierarchyWalker::add_participant(participant); 1297 _found_methods[num_participants()] = nullptr; 1298 } 1299 1300 bool record_witness(Klass* witness, Method* m) { 1301 _found_methods[num_participants()] = m; 1302 return AbstractClassHierarchyWalker::record_witness(witness); 1303 } 1304 1305 private: 1306 static PerfCounter* _perf_find_witness_anywhere_calls_count; 1307 static PerfCounter* _perf_find_witness_anywhere_steps_count; 1308 static PerfCounter* _perf_find_witness_in_calls_count; 1309 1310 public: 1311 static void init(); 1312 static void print_statistics(); 1313 }; 1314 1315 bool ConcreteMethodFinder::is_witness(Klass* k) { 1316 if (is_participant(k)) { 1317 return false; // do not report participant types 1318 } 1319 if (k->is_instance_klass()) { 1320 InstanceKlass* ik = InstanceKlass::cast(k); 1321 // Search class hierarchy first, skipping private implementations 1322 // as they never override any inherited methods 1323 Method* m = ik->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip); 1324 if (Dependencies::is_concrete_method(m, ik)) { 1325 return record_witness(k, m); // concrete method found 1326 } else { 1327 // Check for re-abstraction of method 1328 if (!ik->is_interface() && m != nullptr && m->is_abstract()) { 1329 // Found a matching abstract method 'm' in the class hierarchy. 1330 // This is fine iff 'k' is an abstract class and all concrete subtypes 1331 // of 'k' override 'm' and are participates of the current search. 1332 ConcreteSubtypeFinder wf; 1333 for (uint i = 0; i < num_participants(); i++) { 1334 Klass* p = participant(i); 1335 wf.add_participant(p); 1336 } 1337 Klass* w = wf.find_witness(ik); 1338 if (w != nullptr) { 1339 Method* wm = InstanceKlass::cast(w)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip); 1340 if (!Dependencies::is_concrete_method(wm, w)) { 1341 // Found a concrete subtype 'w' which does not override abstract method 'm'. 1342 // Bail out because 'm' could be called with 'w' as receiver (leading to an 1343 // AbstractMethodError) and thus the method we are looking for is not unique. 1344 return record_witness(k, m); 1345 } 1346 } 1347 } 1348 // Check interface defaults also, if any exist. 1349 Array<Method*>* default_methods = ik->default_methods(); 1350 if (default_methods != nullptr) { 1351 Method* dm = ik->find_method(default_methods, _name, _signature); 1352 if (Dependencies::is_concrete_method(dm, nullptr)) { 1353 return record_witness(k, dm); // default method found 1354 } 1355 } 1356 return false; // no concrete method found 1357 } 1358 } else { 1359 return false; // no methods to find in an array type 1360 } 1361 } 1362 1363 Klass* ConcreteMethodFinder::find_witness_in(KlassDepChange& changes) { 1364 // When looking for unexpected concrete methods, look beneath expected ones, to see if there are overrides. 1365 // * CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness. 1366 Klass* new_type = changes.as_new_klass_change()->new_type(); 1367 assert(!is_participant(new_type), "only old classes are participants"); 1368 if (is_witness(new_type)) { 1369 return new_type; 1370 } else { 1371 // No witness found, but is_witness() doesn't detect method re-abstraction in case of spot-checking. 1372 if (witnessed_reabstraction_in_supers(new_type)) { 1373 return new_type; 1374 } 1375 } 1376 // No witness found. The dependency remains unbroken. 1377 return nullptr; 1378 } 1379 1380 bool ConcreteMethodFinder::witnessed_reabstraction_in_supers(Klass* k) { 1381 if (!k->is_instance_klass()) { 1382 return false; // no methods to find in an array type 1383 } else { 1384 // Looking for a case when an abstract method is inherited into a concrete class. 1385 if (Dependencies::is_concrete_klass(k) && !k->is_interface()) { 1386 Method* m = InstanceKlass::cast(k)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip); 1387 if (m != nullptr) { 1388 return false; // no reabstraction possible: local method found 1389 } 1390 for (InstanceKlass* super = k->java_super(); super != nullptr; super = super->java_super()) { 1391 m = super->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip); 1392 if (m != nullptr) { // inherited method found 1393 if (m->is_abstract() || m->is_overpass()) { 1394 return record_witness(super, m); // abstract method found 1395 } 1396 return false; 1397 } 1398 } 1399 // Miranda. 1400 return true; 1401 } 1402 return false; 1403 } 1404 } 1405 1406 1407 Klass* ConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) { 1408 // Walk hierarchy under a context type, looking for unexpected types. 1409 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) { 1410 Klass* sub = iter.klass(); 1411 if (is_witness(sub)) { 1412 return sub; // found a witness 1413 } 1414 } 1415 // No witness found. The dependency remains unbroken. 1416 return nullptr; 1417 } 1418 1419 // For some method m and some class ctxk (subclass of method holder), 1420 // enumerate all distinct overrides of m in concrete subclasses of ctxk. 1421 // It relies on vtable/itable information to perform method selection on each linked subclass 1422 // and ignores all non yet linked ones (speculatively treat them as "effectively abstract"). 1423 class LinkedConcreteMethodFinder : public AbstractClassHierarchyWalker { 1424 private: 1425 InstanceKlass* _resolved_klass; // resolved class (JVMS-5.4.3.1) 1426 InstanceKlass* _declaring_klass; // the holder of resolved method (JVMS-5.4.3.3) 1427 int _vtable_index; // vtable/itable index of the resolved method 1428 bool _do_itable_lookup; // choose between itable and vtable lookup logic 1429 1430 // cache of method lookups 1431 Method* _found_methods[PARTICIPANT_LIMIT+1]; 1432 1433 bool is_witness(Klass* k); 1434 Method* select_method(InstanceKlass* recv_klass); 1435 static int compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method, bool& is_itable_index); 1436 static bool is_concrete_klass(InstanceKlass* ik); 1437 1438 void add_participant(Method* m, Klass* participant) { 1439 uint np = num_participants(); 1440 AbstractClassHierarchyWalker::add_participant(participant); 1441 assert(np + 1 == num_participants(), "sanity"); 1442 _found_methods[np] = m; // record the method for the participant 1443 } 1444 1445 bool record_witness(Klass* witness, Method* m) { 1446 for (uint i = 0; i < num_participants(); i++) { 1447 if (found_method(i) == m) { 1448 return false; // already recorded 1449 } 1450 } 1451 // Record not yet seen method. 1452 _found_methods[num_participants()] = m; 1453 return AbstractClassHierarchyWalker::record_witness(witness); 1454 } 1455 1456 void initialize(Method* participant) { 1457 for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) { 1458 _found_methods[i] = nullptr; 1459 } 1460 if (participant != nullptr) { 1461 add_participant(participant, participant->method_holder()); 1462 } 1463 } 1464 1465 protected: 1466 virtual Klass* find_witness_in(KlassDepChange& changes); 1467 virtual Klass* find_witness_anywhere(InstanceKlass* context_type); 1468 1469 public: 1470 // In order to perform method selection, the following info is needed: 1471 // (1) interface or virtual call; 1472 // (2) vtable/itable index; 1473 // (3) declaring class (in case of interface call). 1474 // 1475 // It is prepared based on the results of method resolution: resolved class and resolved method (as specified in JVMS-5.4.3.3). 1476 // Optionally, a method which was previously determined as a unique target (uniqm) is added as a participant 1477 // to enable dependency spot-checking and speed up the search. 1478 LinkedConcreteMethodFinder(InstanceKlass* resolved_klass, Method* resolved_method, Method* uniqm = nullptr) : AbstractClassHierarchyWalker(nullptr) { 1479 assert(UseVtableBasedCHA, "required"); 1480 assert(resolved_klass->is_linked(), "required"); 1481 assert(resolved_method->method_holder()->is_linked(), "required"); 1482 assert(!resolved_method->can_be_statically_bound(), "no vtable index available"); 1483 1484 _resolved_klass = resolved_klass; 1485 _declaring_klass = resolved_method->method_holder(); 1486 _vtable_index = compute_vtable_index(resolved_klass, resolved_method, 1487 _do_itable_lookup); // out parameter 1488 assert(_vtable_index >= 0, "invalid vtable index"); 1489 1490 initialize(uniqm); 1491 } 1492 1493 // Note: If n==num_participants, returns nullptr. 1494 Method* found_method(uint n) { 1495 assert(n <= num_participants(), "oob"); 1496 assert(participant(n) != nullptr || n == num_participants(), "proper usage"); 1497 return _found_methods[n]; 1498 } 1499 }; 1500 1501 Klass* LinkedConcreteMethodFinder::find_witness_in(KlassDepChange& changes) { 1502 Klass* type = changes.type(); 1503 1504 assert(!is_participant(type), "only old classes are participants"); 1505 1506 if (is_witness(type)) { 1507 return type; 1508 } 1509 return nullptr; // No witness found. The dependency remains unbroken. 1510 } 1511 1512 Klass* LinkedConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) { 1513 for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) { 1514 Klass* sub = iter.klass(); 1515 if (is_witness(sub)) { 1516 return sub; 1517 } 1518 if (sub->is_instance_klass() && !InstanceKlass::cast(sub)->is_linked()) { 1519 iter.skip_subclasses(); // ignore not yet linked classes 1520 } 1521 } 1522 return nullptr; // No witness found. The dependency remains unbroken. 1523 } 1524 1525 bool LinkedConcreteMethodFinder::is_witness(Klass* k) { 1526 if (is_participant(k)) { 1527 return false; // do not report participant types 1528 } else if (k->is_instance_klass()) { 1529 InstanceKlass* ik = InstanceKlass::cast(k); 1530 if (is_concrete_klass(ik)) { 1531 Method* m = select_method(ik); 1532 return record_witness(ik, m); 1533 } else { 1534 return false; // ignore non-concrete holder class 1535 } 1536 } else { 1537 return false; // no methods to find in an array type 1538 } 1539 } 1540 1541 Method* LinkedConcreteMethodFinder::select_method(InstanceKlass* recv_klass) { 1542 Method* selected_method = nullptr; 1543 if (_do_itable_lookup) { 1544 assert(_declaring_klass->is_interface(), "sanity"); 1545 bool implements_interface; // initialized by method_at_itable_or_null() 1546 selected_method = recv_klass->method_at_itable_or_null(_declaring_klass, _vtable_index, 1547 implements_interface); // out parameter 1548 assert(implements_interface, "not implemented"); 1549 } else { 1550 selected_method = recv_klass->method_at_vtable(_vtable_index); 1551 } 1552 return selected_method; // nullptr when corresponding slot is empty (AbstractMethodError case) 1553 } 1554 1555 int LinkedConcreteMethodFinder::compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method, 1556 // out parameter 1557 bool& is_itable_index) { 1558 if (resolved_klass->is_interface() && resolved_method->has_itable_index()) { 1559 is_itable_index = true; 1560 return resolved_method->itable_index(); 1561 } 1562 // Check for default or miranda method first. 1563 InstanceKlass* declaring_klass = resolved_method->method_holder(); 1564 if (!resolved_klass->is_interface() && declaring_klass->is_interface()) { 1565 is_itable_index = false; 1566 return resolved_klass->vtable_index_of_interface_method(resolved_method); 1567 } 1568 // At this point we are sure that resolved_method is virtual and not 1569 // a default or miranda method; therefore, it must have a valid vtable index. 1570 assert(resolved_method->has_vtable_index(), ""); 1571 is_itable_index = false; 1572 return resolved_method->vtable_index(); 1573 } 1574 1575 bool LinkedConcreteMethodFinder::is_concrete_klass(InstanceKlass* ik) { 1576 if (!Dependencies::is_concrete_klass(ik)) { 1577 return false; // not concrete 1578 } 1579 if (ik->is_interface()) { 1580 return false; // interfaces aren't concrete 1581 } 1582 if (!ik->is_linked()) { 1583 return false; // not yet linked classes don't have instances 1584 } 1585 return true; 1586 } 1587 1588 #ifdef ASSERT 1589 // Assert that m is inherited into ctxk, without intervening overrides. 1590 // (May return true even if this is not true, in corner cases where we punt.) 1591 bool Dependencies::verify_method_context(InstanceKlass* ctxk, Method* m) { 1592 if (m->is_private()) { 1593 return false; // Quick lose. Should not happen. 1594 } 1595 if (m->method_holder() == ctxk) { 1596 return true; // Quick win. 1597 } 1598 if (!(m->is_public() || m->is_protected())) { 1599 // The override story is complex when packages get involved. 1600 return true; // Must punt the assertion to true. 1601 } 1602 Method* lm = ctxk->lookup_method(m->name(), m->signature()); 1603 if (lm == nullptr) { 1604 // It might be an interface method 1605 lm = ctxk->lookup_method_in_ordered_interfaces(m->name(), m->signature()); 1606 } 1607 if (lm == m) { 1608 // Method m is inherited into ctxk. 1609 return true; 1610 } 1611 if (lm != nullptr) { 1612 if (!(lm->is_public() || lm->is_protected())) { 1613 // Method is [package-]private, so the override story is complex. 1614 return true; // Must punt the assertion to true. 1615 } 1616 if (lm->is_static()) { 1617 // Static methods don't override non-static so punt 1618 return true; 1619 } 1620 if (!Dependencies::is_concrete_method(lm, ctxk) && 1621 !Dependencies::is_concrete_method(m, ctxk)) { 1622 // They are both non-concrete 1623 if (lm->method_holder()->is_subtype_of(m->method_holder())) { 1624 // Method m is overridden by lm, but both are non-concrete. 1625 return true; 1626 } 1627 if (lm->method_holder()->is_interface() && m->method_holder()->is_interface() && 1628 ctxk->is_subtype_of(m->method_holder()) && ctxk->is_subtype_of(lm->method_holder())) { 1629 // Interface method defined in multiple super interfaces 1630 return true; 1631 } 1632 } 1633 } 1634 ResourceMark rm; 1635 tty->print_cr("Dependency method not found in the associated context:"); 1636 tty->print_cr(" context = %s", ctxk->external_name()); 1637 tty->print( " method = "); m->print_short_name(tty); tty->cr(); 1638 if (lm != nullptr) { 1639 tty->print( " found = "); lm->print_short_name(tty); tty->cr(); 1640 } 1641 return false; 1642 } 1643 #endif // ASSERT 1644 1645 bool Dependencies::is_concrete_klass(Klass* k) { 1646 if (k->is_abstract()) return false; 1647 // %%% We could treat classes which are concrete but 1648 // have not yet been instantiated as virtually abstract. 1649 // This would require a deoptimization barrier on first instantiation. 1650 //if (k->is_not_instantiated()) return false; 1651 return true; 1652 } 1653 1654 bool Dependencies::is_concrete_method(Method* m, Klass* k) { 1655 // nullptr is not a concrete method. 1656 if (m == nullptr) { 1657 return false; 1658 } 1659 // Statics are irrelevant to virtual call sites. 1660 if (m->is_static()) { 1661 return false; 1662 } 1663 // Abstract methods are not concrete. 1664 if (m->is_abstract()) { 1665 return false; 1666 } 1667 // Overpass (error) methods are not concrete if k is abstract. 1668 if (m->is_overpass() && k != nullptr) { 1669 return !k->is_abstract(); 1670 } 1671 // Note "true" is conservative answer: overpass clause is false if k == nullptr, 1672 // implies return true if answer depends on overpass clause. 1673 return true; 1674 } 1675 1676 Klass* Dependencies::find_finalizable_subclass(InstanceKlass* ik) { 1677 for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) { 1678 Klass* sub = iter.klass(); 1679 if (sub->has_finalizer() && !sub->is_interface()) { 1680 return sub; 1681 } 1682 } 1683 return nullptr; // not found 1684 } 1685 1686 bool Dependencies::is_concrete_klass(ciInstanceKlass* k) { 1687 if (k->is_abstract()) return false; 1688 // We could also return false if k does not yet appear to be 1689 // instantiated, if the VM version supports this distinction also. 1690 //if (k->is_not_instantiated()) return false; 1691 return true; 1692 } 1693 1694 bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) { 1695 return k->has_finalizable_subclass(); 1696 } 1697 1698 // Any use of the contents (bytecodes) of a method must be 1699 // marked by an "evol_method" dependency, if those contents 1700 // can change. (Note: A method is always dependent on itself.) 1701 Klass* Dependencies::check_evol_method(Method* m) { 1702 assert(must_be_in_vm(), "raw oops here"); 1703 // Did somebody do a JVMTI RedefineClasses while our backs were turned? 1704 // Or is there a now a breakpoint? 1705 // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.) 1706 if (m->is_old() 1707 || m->number_of_breakpoints() > 0) { 1708 return m->method_holder(); 1709 } else { 1710 return nullptr; 1711 } 1712 } 1713 1714 // This is a strong assertion: It is that the given type 1715 // has no subtypes whatever. It is most useful for 1716 // optimizing checks on reflected types or on array types. 1717 // (Checks on types which are derived from real instances 1718 // can be optimized more strongly than this, because we 1719 // know that the checked type comes from a concrete type, 1720 // and therefore we can disregard abstract types.) 1721 Klass* Dependencies::check_leaf_type(InstanceKlass* ctxk) { 1722 assert(must_be_in_vm(), "raw oops here"); 1723 assert_locked_or_safepoint(Compile_lock); 1724 Klass* sub = ctxk->subklass(); 1725 if (sub != nullptr) { 1726 return sub; 1727 } else if (ctxk->nof_implementors() != 0) { 1728 // if it is an interface, it must be unimplemented 1729 // (if it is not an interface, nof_implementors is always zero) 1730 InstanceKlass* impl = ctxk->implementor(); 1731 assert(impl != nullptr, "must be set"); 1732 return impl; 1733 } else { 1734 return nullptr; 1735 } 1736 } 1737 1738 // Test the assertion that conck is the only concrete subtype* of ctxk. 1739 // The type conck itself is allowed to have have further concrete subtypes. 1740 // This allows the compiler to narrow occurrences of ctxk by conck, 1741 // when dealing with the types of actual instances. 1742 Klass* Dependencies::check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk, 1743 Klass* conck, 1744 NewKlassDepChange* changes) { 1745 ConcreteSubtypeFinder wf(conck); 1746 Klass* k = wf.find_witness(ctxk, changes); 1747 return k; 1748 } 1749 1750 1751 // Find the unique concrete proper subtype of ctxk, or nullptr if there 1752 // is more than one concrete proper subtype. If there are no concrete 1753 // proper subtypes, return ctxk itself, whether it is concrete or not. 1754 // The returned subtype is allowed to have have further concrete subtypes. 1755 // That is, return CC1 for CX > CC1 > CC2, but nullptr for CX > { CC1, CC2 }. 1756 Klass* Dependencies::find_unique_concrete_subtype(InstanceKlass* ctxk) { 1757 ConcreteSubtypeFinder wf(ctxk); // Ignore ctxk when walking. 1758 wf.record_witnesses(1); // Record one other witness when walking. 1759 Klass* wit = wf.find_witness(ctxk); 1760 if (wit != nullptr) return nullptr; // Too many witnesses. 1761 Klass* conck = wf.participant(0); 1762 if (conck == nullptr) { 1763 return ctxk; // Return ctxk as a flag for "no subtypes". 1764 } else { 1765 #ifndef PRODUCT 1766 // Make sure the dependency mechanism will pass this discovery: 1767 if (VerifyDependencies) { 1768 // Turn off dependency tracing while actually testing deps. 1769 FlagSetting fs(_verify_in_progress, true); 1770 if (!Dependencies::is_concrete_klass(ctxk)) { 1771 guarantee(nullptr == (void *) 1772 check_abstract_with_unique_concrete_subtype(ctxk, conck), 1773 "verify dep."); 1774 } 1775 } 1776 #endif //PRODUCT 1777 return conck; 1778 } 1779 } 1780 1781 // Try to determine whether root method in some context is concrete or not based on the information about the unique method 1782 // in that context. It exploits the fact that concrete root method is always inherited into the context when there's a unique method. 1783 // Hence, unique method holder is always a supertype of the context class when root method is concrete. 1784 // Examples for concrete_root_method 1785 // C (C.m uniqm) 1786 // | 1787 // CX (ctxk) uniqm is inherited into context. 1788 // 1789 // CX (ctxk) (CX.m uniqm) here uniqm is defined in ctxk. 1790 // Examples for !concrete_root_method 1791 // CX (ctxk) 1792 // | 1793 // C (C.m uniqm) uniqm is in subtype of ctxk. 1794 bool Dependencies::is_concrete_root_method(Method* uniqm, InstanceKlass* ctxk) { 1795 if (uniqm == nullptr) { 1796 return false; // match Dependencies::is_concrete_method() behavior 1797 } 1798 // Theoretically, the "direction" of subtype check matters here. 1799 // On one hand, in case of interface context with a single implementor, uniqm can be in a superclass of the implementor which 1800 // is not related to context class. 1801 // On another hand, uniqm could come from an interface unrelated to the context class, but right now it is not possible: 1802 // it is required that uniqm->method_holder() is the participant (uniqm->method_holder() <: ctxk), hence a default method 1803 // can't be used as unique. 1804 if (ctxk->is_interface()) { 1805 InstanceKlass* implementor = ctxk->implementor(); 1806 assert(implementor != ctxk, "single implementor only"); // should have been invalidated earlier 1807 ctxk = implementor; 1808 } 1809 InstanceKlass* holder = uniqm->method_holder(); 1810 assert(!holder->is_interface(), "no default methods allowed"); 1811 assert(ctxk->is_subclass_of(holder) || holder->is_subclass_of(ctxk), "not related"); 1812 return ctxk->is_subclass_of(holder); 1813 } 1814 1815 // If a class (or interface) has a unique concrete method uniqm, return nullptr. 1816 // Otherwise, return a class that contains an interfering method. 1817 Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk, 1818 Method* uniqm, 1819 NewKlassDepChange* changes) { 1820 ConcreteMethodFinder wf(uniqm, uniqm->method_holder()); 1821 Klass* k = wf.find_witness(ctxk, changes); 1822 if (k != nullptr) { 1823 return k; 1824 } 1825 if (!Dependencies::is_concrete_root_method(uniqm, ctxk) || changes != nullptr) { 1826 Klass* conck = find_witness_AME(ctxk, uniqm, changes); 1827 if (conck != nullptr) { 1828 // Found a concrete subtype 'conck' which does not override abstract root method. 1829 return conck; 1830 } 1831 } 1832 return nullptr; 1833 } 1834 1835 Klass* Dependencies::check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes) { 1836 assert(ctxk->is_interface(), "sanity"); 1837 assert(ctxk->nof_implementors() > 0, "no implementors"); 1838 if (ctxk->nof_implementors() == 1) { 1839 assert(ctxk->implementor() == uniqk, "sanity"); 1840 return nullptr; 1841 } 1842 return ctxk; // no unique implementor 1843 } 1844 1845 // Search for AME. 1846 // There are two version of checks. 1847 // 1) Spot checking version(Classload time). Newly added class is checked for AME. 1848 // Checks whether abstract/overpass method is inherited into/declared in newly added concrete class. 1849 // 2) Compile time analysis for abstract/overpass(abstract klass) root_m. The non uniqm subtrees are checked for concrete classes. 1850 Klass* Dependencies::find_witness_AME(InstanceKlass* ctxk, Method* m, KlassDepChange* changes) { 1851 if (m != nullptr) { 1852 if (changes != nullptr) { 1853 // Spot checking version. 1854 ConcreteMethodFinder wf(m); 1855 Klass* new_type = changes->as_new_klass_change()->new_type(); 1856 if (wf.witnessed_reabstraction_in_supers(new_type)) { 1857 return new_type; 1858 } 1859 } else { 1860 // Note: It is required that uniqm->method_holder() is the participant (see ClassHierarchyWalker::found_method()). 1861 ConcreteSubtypeFinder wf(m->method_holder()); 1862 Klass* conck = wf.find_witness(ctxk); 1863 if (conck != nullptr) { 1864 Method* cm = InstanceKlass::cast(conck)->find_instance_method(m->name(), m->signature(), Klass::PrivateLookupMode::skip); 1865 if (!Dependencies::is_concrete_method(cm, conck)) { 1866 return conck; 1867 } 1868 } 1869 } 1870 } 1871 return nullptr; 1872 } 1873 1874 // This function is used by find_unique_concrete_method(non vtable based) 1875 // to check whether subtype method overrides the base method. 1876 static bool overrides(Method* sub_m, Method* base_m) { 1877 assert(base_m != nullptr, "base method should be non null"); 1878 if (sub_m == nullptr) { 1879 return false; 1880 } 1881 /** 1882 * If base_m is public or protected then sub_m always overrides. 1883 * If base_m is !public, !protected and !private (i.e. base_m is package private) 1884 * then sub_m should be in the same package as that of base_m. 1885 * For package private base_m this is conservative approach as it allows only subset of all allowed cases in 1886 * the jvm specification. 1887 **/ 1888 if (base_m->is_public() || base_m->is_protected() || 1889 base_m->method_holder()->is_same_class_package(sub_m->method_holder())) { 1890 return true; 1891 } 1892 return false; 1893 } 1894 1895 // Find the set of all non-abstract methods under ctxk that match m. 1896 // (The method m must be defined or inherited in ctxk.) 1897 // Include m itself in the set, unless it is abstract. 1898 // If this set has exactly one element, return that element. 1899 Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass** participant) { 1900 // Return nullptr if m is marked old; must have been a redefined method. 1901 if (m->is_old()) { 1902 return nullptr; 1903 } 1904 if (m->is_default_method()) { 1905 return nullptr; // not supported 1906 } 1907 assert(verify_method_context(ctxk, m), "proper context"); 1908 ConcreteMethodFinder wf(m); 1909 wf.record_witnesses(1); 1910 Klass* wit = wf.find_witness(ctxk); 1911 if (wit != nullptr) return nullptr; // Too many witnesses. 1912 Method* fm = wf.found_method(0); // Will be nullptr if num_parts == 0. 1913 if (participant != nullptr) { 1914 (*participant) = wf.participant(0); 1915 } 1916 if (!Dependencies::is_concrete_method(fm, nullptr)) { 1917 fm = nullptr; // ignore abstract methods 1918 } 1919 if (Dependencies::is_concrete_method(m, ctxk)) { 1920 if (fm == nullptr) { 1921 // It turns out that m was always the only implementation. 1922 fm = m; 1923 } else if (fm != m) { 1924 // Two conflicting implementations after all. 1925 // (This can happen if m is inherited into ctxk and fm overrides it.) 1926 return nullptr; 1927 } 1928 } else if (Dependencies::find_witness_AME(ctxk, fm) != nullptr) { 1929 // Found a concrete subtype which does not override abstract root method. 1930 return nullptr; 1931 } else if (!overrides(fm, m)) { 1932 // Found method doesn't override abstract root method. 1933 return nullptr; 1934 } 1935 assert(Dependencies::is_concrete_root_method(fm, ctxk) == Dependencies::is_concrete_method(m, ctxk), "mismatch"); 1936 #ifndef PRODUCT 1937 // Make sure the dependency mechanism will pass this discovery: 1938 if (VerifyDependencies && fm != nullptr) { 1939 guarantee(nullptr == (void *)check_unique_concrete_method(ctxk, fm), 1940 "verify dep."); 1941 } 1942 #endif //PRODUCT 1943 return fm; 1944 } 1945 1946 // If a class (or interface) has a unique concrete method uniqm, return nullptr. 1947 // Otherwise, return a class that contains an interfering method. 1948 Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk, 1949 Method* uniqm, 1950 Klass* resolved_klass, 1951 Method* resolved_method, 1952 KlassDepChange* changes) { 1953 assert(UseVtableBasedCHA, "required"); 1954 assert(!ctxk->is_interface() || ctxk == resolved_klass, "sanity"); 1955 assert(!resolved_method->can_be_statically_bound() || resolved_method == uniqm, "sanity"); 1956 assert(resolved_klass->is_subtype_of(resolved_method->method_holder()), "sanity"); 1957 1958 if (!InstanceKlass::cast(resolved_klass)->is_linked() || 1959 !resolved_method->method_holder()->is_linked() || 1960 resolved_method->can_be_statically_bound()) { 1961 // Dependency is redundant, but benign. Just keep it to avoid unnecessary recompilation. 1962 return nullptr; // no vtable index available 1963 } 1964 1965 LinkedConcreteMethodFinder mf(InstanceKlass::cast(resolved_klass), resolved_method, uniqm); 1966 return mf.find_witness(ctxk, changes); 1967 } 1968 1969 // Find the set of all non-abstract methods under ctxk that match m. 1970 // (The method m must be defined or inherited in ctxk.) 1971 // Include m itself in the set, unless it is abstract. 1972 // If this set has exactly one element, return that element. 1973 // Not yet linked subclasses of ctxk are ignored since they don't have any instances yet. 1974 // Additionally, resolved_klass and resolved_method complete the description of the call site being analyzed. 1975 Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method) { 1976 // Return nullptr if m is marked old; must have been a redefined method. 1977 if (m->is_old()) { 1978 return nullptr; 1979 } 1980 if (!InstanceKlass::cast(resolved_klass)->is_linked() || 1981 !resolved_method->method_holder()->is_linked() || 1982 resolved_method->can_be_statically_bound()) { 1983 return m; // nothing to do: no witness under ctxk 1984 } 1985 LinkedConcreteMethodFinder wf(InstanceKlass::cast(resolved_klass), resolved_method); 1986 assert(Dependencies::verify_method_context(ctxk, m), "proper context"); 1987 wf.record_witnesses(1); 1988 Klass* wit = wf.find_witness(ctxk); 1989 if (wit != nullptr) { 1990 return nullptr; // Too many witnesses. 1991 } 1992 // p == nullptr when no participants are found (wf.num_participants() == 0). 1993 // fm == nullptr case has 2 meanings: 1994 // * when p == nullptr: no method found; 1995 // * when p != nullptr: AbstractMethodError-throwing method found. 1996 // Also, found method should always be accompanied by a participant class. 1997 Klass* p = wf.participant(0); 1998 Method* fm = wf.found_method(0); 1999 assert(fm == nullptr || p != nullptr, "no participant"); 2000 // Normalize all error-throwing cases to nullptr. 2001 if (fm == Universe::throw_illegal_access_error() || 2002 fm == Universe::throw_no_such_method_error() || 2003 !Dependencies::is_concrete_method(fm, p)) { 2004 fm = nullptr; // error-throwing method 2005 } 2006 if (Dependencies::is_concrete_method(m, ctxk)) { 2007 if (p == nullptr) { 2008 // It turns out that m was always the only implementation. 2009 assert(fm == nullptr, "sanity"); 2010 fm = m; 2011 } 2012 } 2013 #ifndef PRODUCT 2014 // Make sure the dependency mechanism will pass this discovery: 2015 if (VerifyDependencies && fm != nullptr) { 2016 guarantee(nullptr == check_unique_concrete_method(ctxk, fm, resolved_klass, resolved_method), 2017 "verify dep."); 2018 } 2019 #endif // PRODUCT 2020 assert(fm == nullptr || !fm->is_abstract(), "sanity"); 2021 // Old CHA conservatively reports concrete methods in abstract classes 2022 // irrespective of whether they have concrete subclasses or not. 2023 // Also, abstract root method case is not fully supported. 2024 #ifdef ASSERT 2025 Klass* uniqp = nullptr; 2026 Method* uniqm = Dependencies::find_unique_concrete_method(ctxk, m, &uniqp); 2027 assert(uniqm == nullptr || uniqm == fm || 2028 m->is_abstract() || 2029 uniqm->method_holder()->is_abstract() || 2030 (fm == nullptr && uniqm != nullptr && uniqp != nullptr && !InstanceKlass::cast(uniqp)->is_linked()), 2031 "sanity"); 2032 #endif // ASSERT 2033 return fm; 2034 } 2035 2036 Klass* Dependencies::check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes) { 2037 InstanceKlass* search_at = ctxk; 2038 if (changes != nullptr) { 2039 search_at = changes->new_type(); // just look at the new bit 2040 } 2041 return find_finalizable_subclass(search_at); 2042 } 2043 2044 Klass* Dependencies::check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes) { 2045 assert(call_site != nullptr, "sanity"); 2046 assert(method_handle != nullptr, "sanity"); 2047 assert(call_site->is_a(vmClasses::CallSite_klass()), "sanity"); 2048 2049 if (changes == nullptr) { 2050 // Validate all CallSites 2051 if (java_lang_invoke_CallSite::target(call_site) != method_handle) 2052 return call_site->klass(); // assertion failed 2053 } else { 2054 // Validate the given CallSite 2055 if (call_site == changes->call_site() && java_lang_invoke_CallSite::target(call_site) != changes->method_handle()) { 2056 assert(method_handle != changes->method_handle(), "must be"); 2057 return call_site->klass(); // assertion failed 2058 } 2059 } 2060 return nullptr; // assertion still valid 2061 } 2062 2063 void Dependencies::DepStream::trace_and_log_witness(Klass* witness) { 2064 if (_verify_in_progress) return; // don't log 2065 if (witness != nullptr) { 2066 LogTarget(Debug, dependencies) lt; 2067 if (lt.is_enabled()) { 2068 LogStream ls(<); 2069 print_dependency(&ls, witness, /*verbose=*/ true); 2070 } 2071 // The following is a no-op unless logging is enabled: 2072 log_dependency(witness); 2073 } 2074 } 2075 2076 Klass* Dependencies::DepStream::check_new_klass_dependency(NewKlassDepChange* changes) { 2077 assert_locked_or_safepoint(Compile_lock); 2078 Dependencies::check_valid_dependency_type(type()); 2079 2080 Klass* witness = nullptr; 2081 switch (type()) { 2082 case evol_method: 2083 witness = check_evol_method(method_argument(0)); 2084 break; 2085 case leaf_type: 2086 witness = check_leaf_type(context_type()); 2087 break; 2088 case abstract_with_unique_concrete_subtype: 2089 witness = check_abstract_with_unique_concrete_subtype(context_type(), type_argument(1), changes); 2090 break; 2091 case unique_concrete_method_2: 2092 witness = check_unique_concrete_method(context_type(), method_argument(1), changes); 2093 break; 2094 case unique_concrete_method_4: 2095 witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes); 2096 break; 2097 case unique_implementor: 2098 witness = check_unique_implementor(context_type(), type_argument(1), changes); 2099 break; 2100 case no_finalizable_subclasses: 2101 witness = check_has_no_finalizable_subclasses(context_type(), changes); 2102 break; 2103 default: 2104 witness = nullptr; 2105 break; 2106 } 2107 trace_and_log_witness(witness); 2108 return witness; 2109 } 2110 2111 Klass* Dependencies::DepStream::check_klass_init_dependency(KlassInitDepChange* changes) { 2112 assert_locked_or_safepoint(Compile_lock); 2113 Dependencies::check_valid_dependency_type(type()); 2114 2115 // No new types added. Only unique_concrete_method_4 is sensitive to class initialization changes. 2116 Klass* witness = nullptr; 2117 switch (type()) { 2118 case unique_concrete_method_4: 2119 witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes); 2120 break; 2121 default: 2122 witness = nullptr; 2123 break; 2124 } 2125 trace_and_log_witness(witness); 2126 return witness; 2127 } 2128 2129 Klass* Dependencies::DepStream::check_klass_dependency(KlassDepChange* changes) { 2130 assert_locked_or_safepoint(Compile_lock); 2131 Dependencies::check_valid_dependency_type(type()); 2132 2133 if (changes != nullptr) { 2134 if (UseVtableBasedCHA && changes->is_klass_init_change()) { 2135 return check_klass_init_dependency(changes->as_klass_init_change()); 2136 } else { 2137 return check_new_klass_dependency(changes->as_new_klass_change()); 2138 } 2139 } else { 2140 Klass* witness = check_new_klass_dependency(nullptr); 2141 // check_klass_init_dependency duplicates check_new_klass_dependency checks when class hierarchy change info is absent. 2142 assert(witness != nullptr || check_klass_init_dependency(nullptr) == nullptr, "missed dependency"); 2143 return witness; 2144 } 2145 } 2146 2147 Klass* Dependencies::DepStream::check_call_site_dependency(CallSiteDepChange* changes) { 2148 assert_locked_or_safepoint(Compile_lock); 2149 Dependencies::check_valid_dependency_type(type()); 2150 2151 Klass* witness = nullptr; 2152 switch (type()) { 2153 case call_site_target_value: 2154 witness = check_call_site_target_value(argument_oop(0), argument_oop(1), changes); 2155 break; 2156 default: 2157 witness = nullptr; 2158 break; 2159 } 2160 trace_and_log_witness(witness); 2161 return witness; 2162 } 2163 2164 2165 Klass* Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) { 2166 // Handle klass dependency 2167 if (changes.is_klass_change() && changes.as_klass_change()->involves_context(context_type())) 2168 return check_klass_dependency(changes.as_klass_change()); 2169 2170 // Handle CallSite dependency 2171 if (changes.is_call_site_change()) 2172 return check_call_site_dependency(changes.as_call_site_change()); 2173 2174 // irrelevant dependency; skip it 2175 return nullptr; 2176 } 2177 2178 2179 void DepChange::print() { print_on(tty); } 2180 2181 void DepChange::print_on(outputStream* st) { 2182 int nsup = 0, nint = 0; 2183 for (ContextStream str(*this); str.next(); ) { 2184 InstanceKlass* k = str.klass(); 2185 switch (str.change_type()) { 2186 case Change_new_type: 2187 st->print_cr(" dependee = %s", k->external_name()); 2188 break; 2189 case Change_new_sub: 2190 if (!WizardMode) { 2191 ++nsup; 2192 } else { 2193 st->print_cr(" context super = %s", k->external_name()); 2194 } 2195 break; 2196 case Change_new_impl: 2197 if (!WizardMode) { 2198 ++nint; 2199 } else { 2200 st->print_cr(" context interface = %s", k->external_name()); 2201 } 2202 break; 2203 default: 2204 break; 2205 } 2206 } 2207 if (nsup + nint != 0) { 2208 st->print_cr(" context supers = %d, interfaces = %d", nsup, nint); 2209 } 2210 } 2211 2212 void DepChange::ContextStream::start() { 2213 InstanceKlass* type = (_changes.is_klass_change() ? _changes.as_klass_change()->type() : (InstanceKlass*) nullptr); 2214 _change_type = (type == nullptr ? NO_CHANGE : Start_Klass); 2215 _klass = type; 2216 _ti_base = nullptr; 2217 _ti_index = 0; 2218 _ti_limit = 0; 2219 } 2220 2221 bool DepChange::ContextStream::next() { 2222 switch (_change_type) { 2223 case Start_Klass: // initial state; _klass is the new type 2224 _ti_base = _klass->transitive_interfaces(); 2225 _ti_index = 0; 2226 _change_type = Change_new_type; 2227 return true; 2228 case Change_new_type: 2229 // fall through: 2230 _change_type = Change_new_sub; 2231 case Change_new_sub: 2232 // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277 2233 { 2234 _klass = _klass->java_super(); 2235 if (_klass != nullptr) { 2236 return true; 2237 } 2238 } 2239 // else set up _ti_limit and fall through: 2240 _ti_limit = (_ti_base == nullptr) ? 0 : _ti_base->length(); 2241 _change_type = Change_new_impl; 2242 case Change_new_impl: 2243 if (_ti_index < _ti_limit) { 2244 _klass = _ti_base->at(_ti_index++); 2245 return true; 2246 } 2247 // fall through: 2248 _change_type = NO_CHANGE; // iterator is exhausted 2249 case NO_CHANGE: 2250 break; 2251 default: 2252 ShouldNotReachHere(); 2253 } 2254 return false; 2255 } 2256 2257 void KlassDepChange::initialize() { 2258 // entire transaction must be under this lock: 2259 assert_lock_strong(Compile_lock); 2260 2261 // Mark all dependee and all its superclasses 2262 // Mark transitive interfaces 2263 for (ContextStream str(*this); str.next(); ) { 2264 InstanceKlass* d = str.klass(); 2265 assert(!d->is_marked_dependent(), "checking"); 2266 d->set_is_marked_dependent(true); 2267 } 2268 } 2269 2270 KlassDepChange::~KlassDepChange() { 2271 // Unmark all dependee and all its superclasses 2272 // Unmark transitive interfaces 2273 for (ContextStream str(*this); str.next(); ) { 2274 InstanceKlass* d = str.klass(); 2275 d->set_is_marked_dependent(false); 2276 } 2277 } 2278 2279 bool KlassDepChange::involves_context(Klass* k) { 2280 if (k == nullptr || !k->is_instance_klass()) { 2281 return false; 2282 } 2283 InstanceKlass* ik = InstanceKlass::cast(k); 2284 bool is_contained = ik->is_marked_dependent(); 2285 assert(is_contained == type()->is_subtype_of(k), 2286 "correct marking of potential context types"); 2287 return is_contained; 2288 } 2289 2290 void Dependencies::print_statistics() { 2291 AbstractClassHierarchyWalker::print_statistics(); 2292 } 2293 2294 void AbstractClassHierarchyWalker::print_statistics() { 2295 if (UsePerfData) { 2296 jlong deps_find_witness_calls = _perf_find_witness_anywhere_calls_count->get_value(); 2297 jlong deps_find_witness_steps = _perf_find_witness_anywhere_steps_count->get_value(); 2298 jlong deps_find_witness_singles = _perf_find_witness_in_calls_count->get_value(); 2299 2300 ttyLocker ttyl; 2301 tty->print_cr("Dependency check (find_witness) " 2302 "calls=" JLONG_FORMAT ", steps=" JLONG_FORMAT " (avg=%.1f), singles=" JLONG_FORMAT, 2303 deps_find_witness_calls, 2304 deps_find_witness_steps, 2305 (double)deps_find_witness_steps / deps_find_witness_calls, 2306 deps_find_witness_singles); 2307 if (xtty != nullptr) { 2308 xtty->elem("deps_find_witness calls='" JLONG_FORMAT "' steps='" JLONG_FORMAT "' singles='" JLONG_FORMAT "'", 2309 deps_find_witness_calls, 2310 deps_find_witness_steps, 2311 deps_find_witness_singles); 2312 } 2313 } 2314 } 2315 2316 CallSiteDepChange::CallSiteDepChange(Handle call_site, Handle method_handle) : 2317 _call_site(call_site), 2318 _method_handle(method_handle) { 2319 assert(_call_site()->is_a(vmClasses::CallSite_klass()), "must be"); 2320 assert(_method_handle.is_null() || _method_handle()->is_a(vmClasses::MethodHandle_klass()), "must be"); 2321 } 2322 2323 void dependencies_init() { 2324 AbstractClassHierarchyWalker::init(); 2325 }