1 /*
   2  * Copyright (c) 2005, 2016, 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 "code/dependencies.hpp"
  32 #include "compiler/compileLog.hpp"
  33 #include "memory/resourceArea.hpp"
  34 #include "oops/oop.inline.hpp"
  35 #include "oops/objArrayKlass.hpp"
  36 #include "runtime/handles.hpp"
  37 #include "runtime/handles.inline.hpp"
  38 #include "runtime/thread.inline.hpp"
  39 #include "utilities/copy.hpp"
  40 
  41 
  42 #ifdef ASSERT
  43 static bool must_be_in_vm() {
  44   Thread* thread = Thread::current();
  45   if (thread->is_Java_thread())
  46     return ((JavaThread*)thread)->thread_state() == _thread_in_vm;
  47   else
  48     return true;  //something like this: thread->is_VM_thread();
  49 }
  50 #endif //ASSERT
  51 
  52 void Dependencies::initialize(ciEnv* env) {
  53   Arena* arena = env->arena();
  54   _oop_recorder = env->oop_recorder();
  55   _log = env->log();
  56   _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
  57 #if INCLUDE_JVMCI
  58   _using_dep_values = false;
  59 #endif
  60   DEBUG_ONLY(_deps[end_marker] = NULL);
  61   for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
  62     _deps[i] = new(arena) GrowableArray<ciBaseObject*>(arena, 10, 0, 0);
  63   }
  64   _content_bytes = NULL;
  65   _size_in_bytes = (size_t)-1;
  66 
  67   assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
  68 }
  69 
  70 void Dependencies::assert_evol_method(ciMethod* m) {
  71   assert_common_1(evol_method, m);
  72 }
  73 
  74 void Dependencies::assert_leaf_type(ciKlass* ctxk) {
  75   if (ctxk->is_array_klass()) {
  76     // As a special case, support this assertion on an array type,
  77     // which reduces to an assertion on its element type.
  78     // Note that this cannot be done with assertions that
  79     // relate to concreteness or abstractness.
  80     ciType* elemt = ctxk->as_array_klass()->base_element_type();
  81     if (!elemt->is_instance_klass())  return;   // Ex:  int[][]
  82     ctxk = elemt->as_instance_klass();
  83     //if (ctxk->is_final())  return;            // Ex:  String[][]
  84   }
  85   check_ctxk(ctxk);
  86   assert_common_1(leaf_type, ctxk);
  87 }
  88 
  89 void Dependencies::assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck) {
  90   check_ctxk_abstract(ctxk);
  91   assert_common_2(abstract_with_unique_concrete_subtype, ctxk, conck);
  92 }
  93 
  94 void Dependencies::assert_abstract_with_no_concrete_subtype(ciKlass* ctxk) {
  95   check_ctxk_abstract(ctxk);
  96   assert_common_1(abstract_with_no_concrete_subtype, ctxk);
  97 }
  98 
  99 void Dependencies::assert_concrete_with_no_concrete_subtype(ciKlass* ctxk) {
 100   check_ctxk_concrete(ctxk);
 101   assert_common_1(concrete_with_no_concrete_subtype, ctxk);
 102 }
 103 
 104 void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm) {
 105   check_ctxk(ctxk);
 106   assert_common_2(unique_concrete_method, ctxk, uniqm);
 107 }
 108 
 109 void Dependencies::assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2) {
 110   check_ctxk(ctxk);
 111   assert_common_3(abstract_with_exclusive_concrete_subtypes_2, ctxk, k1, k2);
 112 }
 113 
 114 void Dependencies::assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2) {
 115   check_ctxk(ctxk);
 116   assert_common_3(exclusive_concrete_methods_2, ctxk, m1, m2);
 117 }
 118 
 119 void Dependencies::assert_has_no_finalizable_subclasses(ciKlass* ctxk) {
 120   check_ctxk(ctxk);
 121   assert_common_1(no_finalizable_subclasses, ctxk);
 122 }
 123 
 124 void Dependencies::assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle) {
 125   assert_common_2(call_site_target_value, call_site, method_handle);
 126 }
 127 
 128 #if INCLUDE_JVMCI
 129 
 130 Dependencies::Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log) {
 131   _oop_recorder = oop_recorder;
 132   _log = log;
 133   _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
 134   _using_dep_values = true;
 135   DEBUG_ONLY(_dep_values[end_marker] = NULL);
 136   for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
 137     _dep_values[i] = new(arena) GrowableArray<DepValue>(arena, 10, 0, DepValue());
 138   }
 139   _content_bytes = NULL;
 140   _size_in_bytes = (size_t)-1;
 141 
 142   assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
 143 }
 144 
 145 void Dependencies::assert_evol_method(Method* m) {
 146   assert_common_1(evol_method, DepValue(_oop_recorder, m));
 147 }
 148 
 149 void Dependencies::assert_has_no_finalizable_subclasses(Klass* ctxk) {
 150   check_ctxk(ctxk);
 151   assert_common_1(no_finalizable_subclasses, DepValue(_oop_recorder, ctxk));
 152 }
 153 
 154 void Dependencies::assert_leaf_type(Klass* ctxk) {
 155   if (ctxk->is_array_klass()) {
 156     // As a special case, support this assertion on an array type,
 157     // which reduces to an assertion on its element type.
 158     // Note that this cannot be done with assertions that
 159     // relate to concreteness or abstractness.
 160     BasicType elemt = ArrayKlass::cast(ctxk)->element_type();
 161     if (is_java_primitive(elemt))  return;   // Ex:  int[][]
 162     ctxk = ObjArrayKlass::cast(ctxk)->bottom_klass();
 163     //if (ctxk->is_final())  return;            // Ex:  String[][]
 164   }
 165   check_ctxk(ctxk);
 166   assert_common_1(leaf_type, DepValue(_oop_recorder, ctxk));
 167 }
 168 
 169 void Dependencies::assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck) {
 170   check_ctxk_abstract(ctxk);
 171   DepValue ctxk_dv(_oop_recorder, ctxk);
 172   DepValue conck_dv(_oop_recorder, conck, &ctxk_dv);
 173   assert_common_2(abstract_with_unique_concrete_subtype, ctxk_dv, conck_dv);
 174 }
 175 
 176 void Dependencies::assert_unique_concrete_method(Klass* ctxk, Method* uniqm) {
 177   check_ctxk(ctxk);
 178   assert_common_2(unique_concrete_method, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqm));
 179 }
 180 
 181 void Dependencies::assert_call_site_target_value(oop call_site, oop method_handle) {
 182   assert_common_2(call_site_target_value, DepValue(_oop_recorder, JNIHandles::make_local(call_site)), DepValue(_oop_recorder, JNIHandles::make_local(method_handle)));
 183 }
 184 
 185 #endif // INCLUDE_JVMCI
 186 
 187 
 188 // Helper function.  If we are adding a new dep. under ctxk2,
 189 // try to find an old dep. under a broader* ctxk1.  If there is
 190 //
 191 bool Dependencies::maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
 192                                     int ctxk_i, ciKlass* ctxk2) {
 193   ciKlass* ctxk1 = deps->at(ctxk_i)->as_metadata()->as_klass();
 194   if (ctxk2->is_subtype_of(ctxk1)) {
 195     return true;  // success, and no need to change
 196   } else if (ctxk1->is_subtype_of(ctxk2)) {
 197     // new context class fully subsumes previous one
 198     deps->at_put(ctxk_i, ctxk2);
 199     return true;
 200   } else {
 201     return false;
 202   }
 203 }
 204 
 205 void Dependencies::assert_common_1(DepType dept, ciBaseObject* x) {
 206   assert(dep_args(dept) == 1, "sanity");
 207   log_dependency(dept, x);
 208   GrowableArray<ciBaseObject*>* deps = _deps[dept];
 209 
 210   // see if the same (or a similar) dep is already recorded
 211   if (note_dep_seen(dept, x)) {
 212     assert(deps->find(x) >= 0, "sanity");
 213   } else {
 214     deps->append(x);
 215   }
 216 }
 217 
 218 void Dependencies::assert_common_2(DepType dept,
 219                                    ciBaseObject* x0, ciBaseObject* x1) {
 220   assert(dep_args(dept) == 2, "sanity");
 221   log_dependency(dept, x0, x1);
 222   GrowableArray<ciBaseObject*>* deps = _deps[dept];
 223 
 224   // see if the same (or a similar) dep is already recorded
 225   bool has_ctxk = has_explicit_context_arg(dept);
 226   if (has_ctxk) {
 227     assert(dep_context_arg(dept) == 0, "sanity");
 228     if (note_dep_seen(dept, x1)) {
 229       // look in this bucket for redundant assertions
 230       const int stride = 2;
 231       for (int i = deps->length(); (i -= stride) >= 0; ) {
 232         ciBaseObject* y1 = deps->at(i+1);
 233         if (x1 == y1) {  // same subject; check the context
 234           if (maybe_merge_ctxk(deps, i+0, x0->as_metadata()->as_klass())) {
 235             return;
 236           }
 237         }
 238       }
 239     }
 240   } else {
 241     if (note_dep_seen(dept, x0) && note_dep_seen(dept, x1)) {
 242       // look in this bucket for redundant assertions
 243       const int stride = 2;
 244       for (int i = deps->length(); (i -= stride) >= 0; ) {
 245         ciBaseObject* y0 = deps->at(i+0);
 246         ciBaseObject* y1 = deps->at(i+1);
 247         if (x0 == y0 && x1 == y1) {
 248           return;
 249         }
 250       }
 251     }
 252   }
 253 
 254   // append the assertion in the correct bucket:
 255   deps->append(x0);
 256   deps->append(x1);
 257 }
 258 
 259 void Dependencies::assert_common_3(DepType dept,
 260                                    ciKlass* ctxk, ciBaseObject* x, ciBaseObject* x2) {
 261   assert(dep_context_arg(dept) == 0, "sanity");
 262   assert(dep_args(dept) == 3, "sanity");
 263   log_dependency(dept, ctxk, x, x2);
 264   GrowableArray<ciBaseObject*>* deps = _deps[dept];
 265 
 266   // try to normalize an unordered pair:
 267   bool swap = false;
 268   switch (dept) {
 269   case abstract_with_exclusive_concrete_subtypes_2:
 270     swap = (x->ident() > x2->ident() && x->as_metadata()->as_klass() != ctxk);
 271     break;
 272   case exclusive_concrete_methods_2:
 273     swap = (x->ident() > x2->ident() && x->as_metadata()->as_method()->holder() != ctxk);
 274     break;
 275   }
 276   if (swap) { ciBaseObject* t = x; x = x2; x2 = t; }
 277 
 278   // see if the same (or a similar) dep is already recorded
 279   if (note_dep_seen(dept, x) && note_dep_seen(dept, x2)) {
 280     // look in this bucket for redundant assertions
 281     const int stride = 3;
 282     for (int i = deps->length(); (i -= stride) >= 0; ) {
 283       ciBaseObject* y  = deps->at(i+1);
 284       ciBaseObject* y2 = deps->at(i+2);
 285       if (x == y && x2 == y2) {  // same subjects; check the context
 286         if (maybe_merge_ctxk(deps, i+0, ctxk)) {
 287           return;
 288         }
 289       }
 290     }
 291   }
 292   // append the assertion in the correct bucket:
 293   deps->append(ctxk);
 294   deps->append(x);
 295   deps->append(x2);
 296 }
 297 
 298 #if INCLUDE_JVMCI
 299 bool Dependencies::maybe_merge_ctxk(GrowableArray<DepValue>* deps,
 300                                     int ctxk_i, DepValue ctxk2_dv) {
 301   Klass* ctxk1 = deps->at(ctxk_i).as_klass(_oop_recorder);
 302   Klass* ctxk2 = ctxk2_dv.as_klass(_oop_recorder);
 303   if (ctxk2->is_subtype_of(ctxk1)) {
 304     return true;  // success, and no need to change
 305   } else if (ctxk1->is_subtype_of(ctxk2)) {
 306     // new context class fully subsumes previous one
 307     deps->at_put(ctxk_i, ctxk2_dv);
 308     return true;
 309   } else {
 310     return false;
 311   }
 312 }
 313 
 314 void Dependencies::assert_common_1(DepType dept, DepValue x) {
 315   assert(dep_args(dept) == 1, "sanity");
 316   //log_dependency(dept, x);
 317   GrowableArray<DepValue>* deps = _dep_values[dept];
 318 
 319   // see if the same (or a similar) dep is already recorded
 320   if (note_dep_seen(dept, x)) {
 321     assert(deps->find(x) >= 0, "sanity");
 322   } else {
 323     deps->append(x);
 324   }
 325 }
 326 
 327 void Dependencies::assert_common_2(DepType dept,
 328                                    DepValue x0, DepValue x1) {
 329   assert(dep_args(dept) == 2, "sanity");
 330   //log_dependency(dept, x0, x1);
 331   GrowableArray<DepValue>* deps = _dep_values[dept];
 332 
 333   // see if the same (or a similar) dep is already recorded
 334   bool has_ctxk = has_explicit_context_arg(dept);
 335   if (has_ctxk) {
 336     assert(dep_context_arg(dept) == 0, "sanity");
 337     if (note_dep_seen(dept, x1)) {
 338       // look in this bucket for redundant assertions
 339       const int stride = 2;
 340       for (int i = deps->length(); (i -= stride) >= 0; ) {
 341         DepValue y1 = deps->at(i+1);
 342         if (x1 == y1) {  // same subject; check the context
 343           if (maybe_merge_ctxk(deps, i+0, x0)) {
 344             return;
 345           }
 346         }
 347       }
 348     }
 349   } else {
 350     if (note_dep_seen(dept, x0) && note_dep_seen(dept, x1)) {
 351       // look in this bucket for redundant assertions
 352       const int stride = 2;
 353       for (int i = deps->length(); (i -= stride) >= 0; ) {
 354         DepValue y0 = deps->at(i+0);
 355         DepValue y1 = deps->at(i+1);
 356         if (x0 == y0 && x1 == y1) {
 357           return;
 358         }
 359       }
 360     }
 361   }
 362 
 363   // append the assertion in the correct bucket:
 364   deps->append(x0);
 365   deps->append(x1);
 366 }
 367 #endif // INCLUDE_JVMCI
 368 
 369 /// Support for encoding dependencies into an nmethod:
 370 
 371 void Dependencies::copy_to(nmethod* nm) {
 372   address beg = nm->dependencies_begin();
 373   address end = nm->dependencies_end();
 374   guarantee(end - beg >= (ptrdiff_t) size_in_bytes(), "bad sizing");
 375   Copy::disjoint_words((HeapWord*) content_bytes(),
 376                        (HeapWord*) beg,
 377                        size_in_bytes() / sizeof(HeapWord));
 378   assert(size_in_bytes() % sizeof(HeapWord) == 0, "copy by words");
 379 }
 380 
 381 static int sort_dep(ciBaseObject** p1, ciBaseObject** p2, int narg) {
 382   for (int i = 0; i < narg; i++) {
 383     int diff = p1[i]->ident() - p2[i]->ident();
 384     if (diff != 0)  return diff;
 385   }
 386   return 0;
 387 }
 388 static int sort_dep_arg_1(ciBaseObject** p1, ciBaseObject** p2)
 389 { return sort_dep(p1, p2, 1); }
 390 static int sort_dep_arg_2(ciBaseObject** p1, ciBaseObject** p2)
 391 { return sort_dep(p1, p2, 2); }
 392 static int sort_dep_arg_3(ciBaseObject** p1, ciBaseObject** p2)
 393 { return sort_dep(p1, p2, 3); }
 394 
 395 #if INCLUDE_JVMCI
 396 // metadata deps are sorted before object deps
 397 static int sort_dep_value(Dependencies::DepValue* p1, Dependencies::DepValue* p2, int narg) {
 398   for (int i = 0; i < narg; i++) {
 399     int diff = p1[i].sort_key() - p2[i].sort_key();
 400     if (diff != 0)  return diff;
 401   }
 402   return 0;
 403 }
 404 static int sort_dep_value_arg_1(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
 405 { return sort_dep_value(p1, p2, 1); }
 406 static int sort_dep_value_arg_2(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
 407 { return sort_dep_value(p1, p2, 2); }
 408 static int sort_dep_value_arg_3(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
 409 { return sort_dep_value(p1, p2, 3); }
 410 #endif // INCLUDE_JVMCI
 411 
 412 void Dependencies::sort_all_deps() {
 413 #if INCLUDE_JVMCI
 414   if (_using_dep_values) {
 415     for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 416       DepType dept = (DepType)deptv;
 417       GrowableArray<DepValue>* deps = _dep_values[dept];
 418       if (deps->length() <= 1)  continue;
 419       switch (dep_args(dept)) {
 420       case 1: deps->sort(sort_dep_value_arg_1, 1); break;
 421       case 2: deps->sort(sort_dep_value_arg_2, 2); break;
 422       case 3: deps->sort(sort_dep_value_arg_3, 3); break;
 423       default: ShouldNotReachHere();
 424       }
 425     }
 426     return;
 427   }
 428 #endif // INCLUDE_JVMCI
 429   for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 430     DepType dept = (DepType)deptv;
 431     GrowableArray<ciBaseObject*>* deps = _deps[dept];
 432     if (deps->length() <= 1)  continue;
 433     switch (dep_args(dept)) {
 434     case 1: deps->sort(sort_dep_arg_1, 1); break;
 435     case 2: deps->sort(sort_dep_arg_2, 2); break;
 436     case 3: deps->sort(sort_dep_arg_3, 3); break;
 437     default: ShouldNotReachHere();
 438     }
 439   }
 440 }
 441 
 442 size_t Dependencies::estimate_size_in_bytes() {
 443   size_t est_size = 100;
 444 #if INCLUDE_JVMCI
 445   if (_using_dep_values) {
 446     for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 447       DepType dept = (DepType)deptv;
 448       GrowableArray<DepValue>* deps = _dep_values[dept];
 449       est_size += deps->length() * 2;  // tags and argument(s)
 450     }
 451     return est_size;
 452   }
 453 #endif // INCLUDE_JVMCI
 454   for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 455     DepType dept = (DepType)deptv;
 456     GrowableArray<ciBaseObject*>* deps = _deps[dept];
 457     est_size += deps->length()*2;  // tags and argument(s)
 458   }
 459   return est_size;
 460 }
 461 
 462 ciKlass* Dependencies::ctxk_encoded_as_null(DepType dept, ciBaseObject* x) {
 463   switch (dept) {
 464   case abstract_with_exclusive_concrete_subtypes_2:
 465     return x->as_metadata()->as_klass();
 466   case unique_concrete_method:
 467   case exclusive_concrete_methods_2:
 468     return x->as_metadata()->as_method()->holder();
 469   }
 470   return NULL;  // let NULL be NULL
 471 }
 472 
 473 Klass* Dependencies::ctxk_encoded_as_null(DepType dept, Metadata* x) {
 474   assert(must_be_in_vm(), "raw oops here");
 475   switch (dept) {
 476   case abstract_with_exclusive_concrete_subtypes_2:
 477     assert(x->is_klass(), "sanity");
 478     return (Klass*) x;
 479   case unique_concrete_method:
 480   case exclusive_concrete_methods_2:
 481     assert(x->is_method(), "sanity");
 482     return ((Method*)x)->method_holder();
 483   }
 484   return NULL;  // let NULL be NULL
 485 }
 486 
 487 void Dependencies::encode_content_bytes() {
 488   sort_all_deps();
 489 
 490   // cast is safe, no deps can overflow INT_MAX
 491   CompressedWriteStream bytes((int)estimate_size_in_bytes());
 492 
 493 #if INCLUDE_JVMCI
 494   if (_using_dep_values) {
 495     for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 496       DepType dept = (DepType)deptv;
 497       GrowableArray<DepValue>* deps = _dep_values[dept];
 498       if (deps->length() == 0)  continue;
 499       int stride = dep_args(dept);
 500       int ctxkj  = dep_context_arg(dept);  // -1 if no context arg
 501       assert(stride > 0, "sanity");
 502       for (int i = 0; i < deps->length(); i += stride) {
 503         jbyte code_byte = (jbyte)dept;
 504         int skipj = -1;
 505         if (ctxkj >= 0 && ctxkj+1 < stride) {
 506           Klass*  ctxk = deps->at(i+ctxkj+0).as_klass(_oop_recorder);
 507           DepValue x = deps->at(i+ctxkj+1);  // following argument
 508           if (ctxk == ctxk_encoded_as_null(dept, x.as_metadata(_oop_recorder))) {
 509             skipj = ctxkj;  // we win:  maybe one less oop to keep track of
 510             code_byte |= default_context_type_bit;
 511           }
 512         }
 513         bytes.write_byte(code_byte);
 514         for (int j = 0; j < stride; j++) {
 515           if (j == skipj)  continue;
 516           DepValue v = deps->at(i+j);
 517           int idx = v.index();
 518           bytes.write_int(idx);
 519         }
 520       }
 521     }
 522   } else {
 523 #endif // INCLUDE_JVMCI
 524   for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 525     DepType dept = (DepType)deptv;
 526     GrowableArray<ciBaseObject*>* deps = _deps[dept];
 527     if (deps->length() == 0)  continue;
 528     int stride = dep_args(dept);
 529     int ctxkj  = dep_context_arg(dept);  // -1 if no context arg
 530     assert(stride > 0, "sanity");
 531     for (int i = 0; i < deps->length(); i += stride) {
 532       jbyte code_byte = (jbyte)dept;
 533       int skipj = -1;
 534       if (ctxkj >= 0 && ctxkj+1 < stride) {
 535         ciKlass*  ctxk = deps->at(i+ctxkj+0)->as_metadata()->as_klass();
 536         ciBaseObject* x     = deps->at(i+ctxkj+1);  // following argument
 537         if (ctxk == ctxk_encoded_as_null(dept, x)) {
 538           skipj = ctxkj;  // we win:  maybe one less oop to keep track of
 539           code_byte |= default_context_type_bit;
 540         }
 541       }
 542       bytes.write_byte(code_byte);
 543       for (int j = 0; j < stride; j++) {
 544         if (j == skipj)  continue;
 545         ciBaseObject* v = deps->at(i+j);
 546         int idx;
 547         if (v->is_object()) {
 548           idx = _oop_recorder->find_index(v->as_object()->constant_encoding());
 549         } else {
 550           ciMetadata* meta = v->as_metadata();
 551           idx = _oop_recorder->find_index(meta->constant_encoding());
 552         }
 553         bytes.write_int(idx);
 554       }
 555     }
 556   }
 557 #if INCLUDE_JVMCI
 558   }
 559 #endif
 560 
 561   // write a sentinel byte to mark the end
 562   bytes.write_byte(end_marker);
 563 
 564   // round it out to a word boundary
 565   while (bytes.position() % sizeof(HeapWord) != 0) {
 566     bytes.write_byte(end_marker);
 567   }
 568 
 569   // check whether the dept byte encoding really works
 570   assert((jbyte)default_context_type_bit != 0, "byte overflow");
 571 
 572   _content_bytes = bytes.buffer();
 573   _size_in_bytes = bytes.position();
 574 }
 575 
 576 
 577 const char* Dependencies::_dep_name[TYPE_LIMIT] = {
 578   "end_marker",
 579   "evol_method",
 580   "leaf_type",
 581   "abstract_with_unique_concrete_subtype",
 582   "abstract_with_no_concrete_subtype",
 583   "concrete_with_no_concrete_subtype",
 584   "unique_concrete_method",
 585   "abstract_with_exclusive_concrete_subtypes_2",
 586   "exclusive_concrete_methods_2",
 587   "no_finalizable_subclasses",
 588   "call_site_target_value"
 589 };
 590 
 591 int Dependencies::_dep_args[TYPE_LIMIT] = {
 592   -1,// end_marker
 593   1, // evol_method m
 594   1, // leaf_type ctxk
 595   2, // abstract_with_unique_concrete_subtype ctxk, k
 596   1, // abstract_with_no_concrete_subtype ctxk
 597   1, // concrete_with_no_concrete_subtype ctxk
 598   2, // unique_concrete_method ctxk, m
 599   3, // unique_concrete_subtypes_2 ctxk, k1, k2
 600   3, // unique_concrete_methods_2 ctxk, m1, m2
 601   1, // no_finalizable_subclasses ctxk
 602   2  // call_site_target_value call_site, method_handle
 603 };
 604 
 605 const char* Dependencies::dep_name(Dependencies::DepType dept) {
 606   if (!dept_in_mask(dept, all_types))  return "?bad-dep?";
 607   return _dep_name[dept];
 608 }
 609 
 610 int Dependencies::dep_args(Dependencies::DepType dept) {
 611   if (!dept_in_mask(dept, all_types))  return -1;
 612   return _dep_args[dept];
 613 }
 614 
 615 void Dependencies::check_valid_dependency_type(DepType dept) {
 616   guarantee(FIRST_TYPE <= dept && dept < TYPE_LIMIT, "invalid dependency type: %d", (int) dept);
 617 }
 618 
 619 // for the sake of the compiler log, print out current dependencies:
 620 void Dependencies::log_all_dependencies() {
 621   if (log() == NULL)  return;
 622   ResourceMark rm;
 623   for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
 624     DepType dept = (DepType)deptv;
 625     GrowableArray<ciBaseObject*>* deps = _deps[dept];
 626     int deplen = deps->length();
 627     if (deplen == 0) {
 628       continue;
 629     }
 630     int stride = dep_args(dept);
 631     GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(stride);
 632     for (int i = 0; i < deps->length(); i += stride) {
 633       for (int j = 0; j < stride; j++) {
 634         // flush out the identities before printing
 635         ciargs->push(deps->at(i+j));
 636       }
 637       write_dependency_to(log(), dept, ciargs);
 638       ciargs->clear();
 639     }
 640     guarantee(deplen == deps->length(), "deps array cannot grow inside nested ResoureMark scope");
 641   }
 642 }
 643 
 644 void Dependencies::write_dependency_to(CompileLog* log,
 645                                        DepType dept,
 646                                        GrowableArray<DepArgument>* args,
 647                                        Klass* witness) {
 648   if (log == NULL) {
 649     return;
 650   }
 651   ResourceMark rm;
 652   ciEnv* env = ciEnv::current();
 653   GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(args->length());
 654   for (GrowableArrayIterator<DepArgument> it = args->begin(); it != args->end(); ++it) {
 655     DepArgument arg = *it;
 656     if (arg.is_oop()) {
 657       ciargs->push(env->get_object(arg.oop_value()));
 658     } else {
 659       ciargs->push(env->get_metadata(arg.metadata_value()));
 660     }
 661   }
 662   int argslen = ciargs->length();
 663   Dependencies::write_dependency_to(log, dept, ciargs, witness);
 664   guarantee(argslen == ciargs->length(), "ciargs array cannot grow inside nested ResoureMark scope");
 665 }
 666 
 667 void Dependencies::write_dependency_to(CompileLog* log,
 668                                        DepType dept,
 669                                        GrowableArray<ciBaseObject*>* args,
 670                                        Klass* witness) {
 671   if (log == NULL) {
 672     return;
 673   }
 674   ResourceMark rm;
 675   GrowableArray<int>* argids = new GrowableArray<int>(args->length());
 676   for (GrowableArrayIterator<ciBaseObject*> it = args->begin(); it != args->end(); ++it) {
 677     ciBaseObject* obj = *it;
 678     if (obj->is_object()) {
 679       argids->push(log->identify(obj->as_object()));
 680     } else {
 681       argids->push(log->identify(obj->as_metadata()));
 682     }
 683   }
 684   if (witness != NULL) {
 685     log->begin_elem("dependency_failed");
 686   } else {
 687     log->begin_elem("dependency");
 688   }
 689   log->print(" type='%s'", dep_name(dept));
 690   const int ctxkj = dep_context_arg(dept);  // -1 if no context arg
 691   if (ctxkj >= 0 && ctxkj < argids->length()) {
 692     log->print(" ctxk='%d'", argids->at(ctxkj));
 693   }
 694   // write remaining arguments, if any.
 695   for (int j = 0; j < argids->length(); j++) {
 696     if (j == ctxkj)  continue;  // already logged
 697     if (j == 1) {
 698       log->print(  " x='%d'",    argids->at(j));
 699     } else {
 700       log->print(" x%d='%d'", j, argids->at(j));
 701     }
 702   }
 703   if (witness != NULL) {
 704     log->object("witness", witness);
 705     log->stamp();
 706   }
 707   log->end_elem();
 708 }
 709 
 710 void Dependencies::write_dependency_to(xmlStream* xtty,
 711                                        DepType dept,
 712                                        GrowableArray<DepArgument>* args,
 713                                        Klass* witness) {
 714   if (xtty == NULL) {
 715     return;
 716   }
 717   ResourceMark rm;
 718   ttyLocker ttyl;
 719   int ctxkj = dep_context_arg(dept);  // -1 if no context arg
 720   if (witness != NULL) {
 721     xtty->begin_elem("dependency_failed");
 722   } else {
 723     xtty->begin_elem("dependency");
 724   }
 725   xtty->print(" type='%s'", dep_name(dept));
 726   if (ctxkj >= 0) {
 727     xtty->object("ctxk", args->at(ctxkj).metadata_value());
 728   }
 729   // write remaining arguments, if any.
 730   for (int j = 0; j < args->length(); j++) {
 731     if (j == ctxkj)  continue;  // already logged
 732     DepArgument arg = args->at(j);
 733     if (j == 1) {
 734       if (arg.is_oop()) {
 735         xtty->object("x", arg.oop_value());
 736       } else {
 737         xtty->object("x", arg.metadata_value());
 738       }
 739     } else {
 740       char xn[10]; sprintf(xn, "x%d", j);
 741       if (arg.is_oop()) {
 742         xtty->object(xn, arg.oop_value());
 743       } else {
 744         xtty->object(xn, arg.metadata_value());
 745       }
 746     }
 747   }
 748   if (witness != NULL) {
 749     xtty->object("witness", witness);
 750     xtty->stamp();
 751   }
 752   xtty->end_elem();
 753 }
 754 
 755 void Dependencies::print_dependency(DepType dept, GrowableArray<DepArgument>* args,
 756                                     Klass* witness, outputStream* st) {
 757   ResourceMark rm;
 758   ttyLocker ttyl;   // keep the following output all in one block
 759   st->print_cr("%s of type %s",
 760                 (witness == NULL)? "Dependency": "Failed dependency",
 761                 dep_name(dept));
 762   // print arguments
 763   int ctxkj = dep_context_arg(dept);  // -1 if no context arg
 764   for (int j = 0; j < args->length(); j++) {
 765     DepArgument arg = args->at(j);
 766     bool put_star = false;
 767     if (arg.is_null())  continue;
 768     const char* what;
 769     if (j == ctxkj) {
 770       assert(arg.is_metadata(), "must be");
 771       what = "context";
 772       put_star = !Dependencies::is_concrete_klass((Klass*)arg.metadata_value());
 773     } else if (arg.is_method()) {
 774       what = "method ";
 775       put_star = !Dependencies::is_concrete_method((Method*)arg.metadata_value(), NULL);
 776     } else if (arg.is_klass()) {
 777       what = "class  ";
 778     } else {
 779       what = "object ";
 780     }
 781     st->print("  %s = %s", what, (put_star? "*": ""));
 782     if (arg.is_klass()) {
 783       st->print("%s", ((Klass*)arg.metadata_value())->external_name());
 784     } else if (arg.is_method()) {
 785       ((Method*)arg.metadata_value())->print_value_on(st);
 786     } else if (arg.is_oop()) {
 787       arg.oop_value()->print_value_on(st);
 788     } else {
 789       ShouldNotReachHere(); // Provide impl for this type.
 790     }
 791 
 792     st->cr();
 793   }
 794   if (witness != NULL) {
 795     bool put_star = !Dependencies::is_concrete_klass(witness);
 796     st->print_cr("  witness = %s%s",
 797                   (put_star? "*": ""),
 798                   witness->external_name());
 799   }
 800 }
 801 
 802 void Dependencies::DepStream::log_dependency(Klass* witness) {
 803   if (_deps == NULL && xtty == NULL)  return;  // fast cutout for runtime
 804   ResourceMark rm;
 805   const int nargs = argument_count();
 806   GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
 807   for (int j = 0; j < nargs; j++) {
 808     if (is_oop_argument(j)) {
 809       args->push(argument_oop(j));
 810     } else {
 811       args->push(argument(j));
 812     }
 813   }
 814   int argslen = args->length();
 815   if (_deps != NULL && _deps->log() != NULL) {
 816     if (ciEnv::current() != NULL) {
 817       Dependencies::write_dependency_to(_deps->log(), type(), args, witness);
 818     } else {
 819       // Treat the CompileLog as an xmlstream instead
 820       Dependencies::write_dependency_to((xmlStream*)_deps->log(), type(), args, witness);
 821     }
 822   } else {
 823     Dependencies::write_dependency_to(xtty, type(), args, witness);
 824   }
 825   guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
 826 }
 827 
 828 void Dependencies::DepStream::print_dependency(Klass* witness, bool verbose, outputStream* st) {
 829   ResourceMark rm;
 830   int nargs = argument_count();
 831   GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
 832   for (int j = 0; j < nargs; j++) {
 833     if (is_oop_argument(j)) {
 834       args->push(argument_oop(j));
 835     } else {
 836       args->push(argument(j));
 837     }
 838   }
 839   int argslen = args->length();
 840   Dependencies::print_dependency(type(), args, witness, st);
 841   if (verbose) {
 842     if (_code != NULL) {
 843       st->print("  code: ");
 844       _code->print_value_on(st);
 845       st->cr();
 846     }
 847   }
 848   guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
 849 }
 850 
 851 
 852 /// Dependency stream support (decodes dependencies from an nmethod):
 853 
 854 #ifdef ASSERT
 855 void Dependencies::DepStream::initial_asserts(size_t byte_limit) {
 856   assert(must_be_in_vm(), "raw oops here");
 857   _byte_limit = byte_limit;
 858   _type       = (DepType)(end_marker-1);  // defeat "already at end" assert
 859   assert((_code!=NULL) + (_deps!=NULL) == 1, "one or t'other");
 860 }
 861 #endif //ASSERT
 862 
 863 bool Dependencies::DepStream::next() {
 864   assert(_type != end_marker, "already at end");
 865   if (_bytes.position() == 0 && _code != NULL
 866       && _code->dependencies_size() == 0) {
 867     // Method has no dependencies at all.
 868     return false;
 869   }
 870   int code_byte = (_bytes.read_byte() & 0xFF);
 871   if (code_byte == end_marker) {
 872     DEBUG_ONLY(_type = end_marker);
 873     return false;
 874   } else {
 875     int ctxk_bit = (code_byte & Dependencies::default_context_type_bit);
 876     code_byte -= ctxk_bit;
 877     DepType dept = (DepType)code_byte;
 878     _type = dept;
 879     Dependencies::check_valid_dependency_type(dept);
 880     int stride = _dep_args[dept];
 881     assert(stride == dep_args(dept), "sanity");
 882     int skipj = -1;
 883     if (ctxk_bit != 0) {
 884       skipj = 0;  // currently the only context argument is at zero
 885       assert(skipj == dep_context_arg(dept), "zero arg always ctxk");
 886     }
 887     for (int j = 0; j < stride; j++) {
 888       _xi[j] = (j == skipj)? 0: _bytes.read_int();
 889     }
 890     DEBUG_ONLY(_xi[stride] = -1);   // help detect overruns
 891     return true;
 892   }
 893 }
 894 
 895 inline Metadata* Dependencies::DepStream::recorded_metadata_at(int i) {
 896   Metadata* o = NULL;
 897   if (_code != NULL) {
 898     o = _code->metadata_at(i);
 899   } else {
 900     o = _deps->oop_recorder()->metadata_at(i);
 901   }
 902   return o;
 903 }
 904 
 905 inline oop Dependencies::DepStream::recorded_oop_at(int i) {
 906   return (_code != NULL)
 907          ? _code->oop_at(i)
 908     : JNIHandles::resolve(_deps->oop_recorder()->oop_at(i));
 909 }
 910 
 911 Metadata* Dependencies::DepStream::argument(int i) {
 912   Metadata* result = recorded_metadata_at(argument_index(i));
 913 
 914   if (result == NULL) { // Explicit context argument can be compressed
 915     int ctxkj = dep_context_arg(type());  // -1 if no explicit context arg
 916     if (ctxkj >= 0 && i == ctxkj && ctxkj+1 < argument_count()) {
 917       result = ctxk_encoded_as_null(type(), argument(ctxkj+1));
 918     }
 919   }
 920 
 921   assert(result == NULL || result->is_klass() || result->is_method(), "must be");
 922   return result;
 923 }
 924 
 925 /**
 926  * Returns a unique identifier for each dependency argument.
 927  */
 928 uintptr_t Dependencies::DepStream::get_identifier(int i) {
 929   if (is_oop_argument(i)) {
 930     return (uintptr_t)(oopDesc*)argument_oop(i);
 931   } else {
 932     return (uintptr_t)argument(i);
 933   }
 934 }
 935 
 936 oop Dependencies::DepStream::argument_oop(int i) {
 937   oop result = recorded_oop_at(argument_index(i));
 938   assert(result == NULL || result->is_oop(), "must be");
 939   return result;
 940 }
 941 
 942 Klass* Dependencies::DepStream::context_type() {
 943   assert(must_be_in_vm(), "raw oops here");
 944 
 945   // Most dependencies have an explicit context type argument.
 946   {
 947     int ctxkj = dep_context_arg(type());  // -1 if no explicit context arg
 948     if (ctxkj >= 0) {
 949       Metadata* k = argument(ctxkj);
 950       assert(k != NULL && k->is_klass(), "type check");
 951       return (Klass*)k;
 952     }
 953   }
 954 
 955   // Some dependencies are using the klass of the first object
 956   // argument as implicit context type.
 957   {
 958     int ctxkj = dep_implicit_context_arg(type());
 959     if (ctxkj >= 0) {
 960       Klass* k = argument_oop(ctxkj)->klass();
 961       assert(k != NULL && k->is_klass(), "type check");
 962       return (Klass*) k;
 963     }
 964   }
 965 
 966   // And some dependencies don't have a context type at all,
 967   // e.g. evol_method.
 968   return NULL;
 969 }
 970 
 971 // ----------------- DependencySignature --------------------------------------
 972 bool DependencySignature::equals(DependencySignature const& s1, DependencySignature const& s2) {
 973   if ((s1.type() != s2.type()) || (s1.args_count() != s2.args_count())) {
 974     return false;
 975   }
 976 
 977   for (int i = 0; i < s1.args_count(); i++) {
 978     if (s1.arg(i) != s2.arg(i)) {
 979       return false;
 980     }
 981   }
 982   return true;
 983 }
 984 
 985 /// Checking dependencies:
 986 
 987 // This hierarchy walker inspects subtypes of a given type,
 988 // trying to find a "bad" class which breaks a dependency.
 989 // Such a class is called a "witness" to the broken dependency.
 990 // While searching around, we ignore "participants", which
 991 // are already known to the dependency.
 992 class ClassHierarchyWalker {
 993  public:
 994   enum { PARTICIPANT_LIMIT = 3 };
 995 
 996  private:
 997   // optional method descriptor to check for:
 998   Symbol* _name;
 999   Symbol* _signature;
1000 
1001   // special classes which are not allowed to be witnesses:
1002   Klass*    _participants[PARTICIPANT_LIMIT+1];
1003   int       _num_participants;
1004 
1005   // cache of method lookups
1006   Method* _found_methods[PARTICIPANT_LIMIT+1];
1007 
1008   // if non-zero, tells how many witnesses to convert to participants
1009   int       _record_witnesses;
1010 
1011   void initialize(Klass* participant) {
1012     _record_witnesses = 0;
1013     _participants[0]  = participant;
1014     _found_methods[0] = NULL;
1015     _num_participants = 0;
1016     if (participant != NULL) {
1017       // Terminating NULL.
1018       _participants[1] = NULL;
1019       _found_methods[1] = NULL;
1020       _num_participants = 1;
1021     }
1022   }
1023 
1024   void initialize_from_method(Method* m) {
1025     assert(m != NULL && m->is_method(), "sanity");
1026     _name      = m->name();
1027     _signature = m->signature();
1028   }
1029 
1030  public:
1031   // The walker is initialized to recognize certain methods and/or types
1032   // as friendly participants.
1033   ClassHierarchyWalker(Klass* participant, Method* m) {
1034     initialize_from_method(m);
1035     initialize(participant);
1036   }
1037   ClassHierarchyWalker(Method* m) {
1038     initialize_from_method(m);
1039     initialize(NULL);
1040   }
1041   ClassHierarchyWalker(Klass* participant = NULL) {
1042     _name      = NULL;
1043     _signature = NULL;
1044     initialize(participant);
1045   }
1046 
1047   // This is common code for two searches:  One for concrete subtypes,
1048   // the other for concrete method implementations and overrides.
1049   bool doing_subtype_search() {
1050     return _name == NULL;
1051   }
1052 
1053   int num_participants() { return _num_participants; }
1054   Klass* participant(int n) {
1055     assert((uint)n <= (uint)_num_participants, "oob");
1056     return _participants[n];
1057   }
1058 
1059   // Note:  If n==num_participants, returns NULL.
1060   Method* found_method(int n) {
1061     assert((uint)n <= (uint)_num_participants, "oob");
1062     Method* fm = _found_methods[n];
1063     assert(n == _num_participants || fm != NULL, "proper usage");
1064     if (fm != NULL && fm->method_holder() != _participants[n]) {
1065       // Default methods from interfaces can be added to classes. In
1066       // that case the holder of the method is not the class but the
1067       // interface where it's defined.
1068       assert(fm->is_default_method(), "sanity");
1069       return NULL;
1070     }
1071     return fm;
1072   }
1073 
1074 #ifdef ASSERT
1075   // Assert that m is inherited into ctxk, without intervening overrides.
1076   // (May return true even if this is not true, in corner cases where we punt.)
1077   bool check_method_context(Klass* ctxk, Method* m) {
1078     if (m->method_holder() == ctxk)
1079       return true;  // Quick win.
1080     if (m->is_private())
1081       return false; // Quick lose.  Should not happen.
1082     if (!(m->is_public() || m->is_protected()))
1083       // The override story is complex when packages get involved.
1084       return true;  // Must punt the assertion to true.
1085     Klass* k = ctxk;
1086     Method* lm = k->lookup_method(m->name(), m->signature());
1087     if (lm == NULL && k->is_instance_klass()) {
1088       // It might be an interface method
1089       lm = InstanceKlass::cast(k)->lookup_method_in_ordered_interfaces(m->name(),
1090                                                                  m->signature());
1091     }
1092     if (lm == m)
1093       // Method m is inherited into ctxk.
1094       return true;
1095     if (lm != NULL) {
1096       if (!(lm->is_public() || lm->is_protected())) {
1097         // Method is [package-]private, so the override story is complex.
1098         return true;  // Must punt the assertion to true.
1099       }
1100       if (lm->is_static()) {
1101         // Static methods don't override non-static so punt
1102         return true;
1103       }
1104       if (   !Dependencies::is_concrete_method(lm, k)
1105           && !Dependencies::is_concrete_method(m, ctxk)
1106           && lm->method_holder()->is_subtype_of(m->method_holder()))
1107         // Method m is overridden by lm, but both are non-concrete.
1108         return true;
1109     }
1110     ResourceMark rm;
1111     tty->print_cr("Dependency method not found in the associated context:");
1112     tty->print_cr("  context = %s", ctxk->external_name());
1113     tty->print(   "  method = "); m->print_short_name(tty); tty->cr();
1114     if (lm != NULL) {
1115       tty->print( "  found = "); lm->print_short_name(tty); tty->cr();
1116     }
1117     return false;
1118   }
1119 #endif
1120 
1121   void add_participant(Klass* participant) {
1122     assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob");
1123     int np = _num_participants++;
1124     _participants[np] = participant;
1125     _participants[np+1] = NULL;
1126     _found_methods[np+1] = NULL;
1127   }
1128 
1129   void record_witnesses(int add) {
1130     if (add > PARTICIPANT_LIMIT)  add = PARTICIPANT_LIMIT;
1131     assert(_num_participants + add < PARTICIPANT_LIMIT, "oob");
1132     _record_witnesses = add;
1133   }
1134 
1135   bool is_witness(Klass* k) {
1136     if (doing_subtype_search()) {
1137       return Dependencies::is_concrete_klass(k);
1138     } else if (!k->is_instance_klass()) {
1139       return false; // no methods to find in an array type
1140     } else {
1141       // Search class hierarchy first.
1142       Method* m = InstanceKlass::cast(k)->find_instance_method(_name, _signature);
1143       if (!Dependencies::is_concrete_method(m, k)) {
1144         // Check interface defaults also, if any exist.
1145         Array<Method*>* default_methods = InstanceKlass::cast(k)->default_methods();
1146         if (default_methods == NULL)
1147             return false;
1148         m = InstanceKlass::cast(k)->find_method(default_methods, _name, _signature);
1149         if (!Dependencies::is_concrete_method(m, NULL))
1150             return false;
1151       }
1152       _found_methods[_num_participants] = m;
1153       // Note:  If add_participant(k) is called,
1154       // the method m will already be memoized for it.
1155       return true;
1156     }
1157   }
1158 
1159   bool is_participant(Klass* k) {
1160     if (k == _participants[0]) {
1161       return true;
1162     } else if (_num_participants <= 1) {
1163       return false;
1164     } else {
1165       return in_list(k, &_participants[1]);
1166     }
1167   }
1168   bool ignore_witness(Klass* witness) {
1169     if (_record_witnesses == 0) {
1170       return false;
1171     } else {
1172       --_record_witnesses;
1173       add_participant(witness);
1174       return true;
1175     }
1176   }
1177   static bool in_list(Klass* x, Klass** list) {
1178     for (int i = 0; ; i++) {
1179       Klass* y = list[i];
1180       if (y == NULL)  break;
1181       if (y == x)  return true;
1182     }
1183     return false;  // not in list
1184   }
1185 
1186  private:
1187   // the actual search method:
1188   Klass* find_witness_anywhere(Klass* context_type,
1189                                  bool participants_hide_witnesses,
1190                                  bool top_level_call = true);
1191   // the spot-checking version:
1192   Klass* find_witness_in(KlassDepChange& changes,
1193                          Klass* context_type,
1194                            bool participants_hide_witnesses);
1195  public:
1196   Klass* find_witness_subtype(Klass* context_type, KlassDepChange* changes = NULL) {
1197     assert(doing_subtype_search(), "must set up a subtype search");
1198     // When looking for unexpected concrete types,
1199     // do not look beneath expected ones.
1200     const bool participants_hide_witnesses = true;
1201     // CX > CC > C' is OK, even if C' is new.
1202     // CX > { CC,  C' } is not OK if C' is new, and C' is the witness.
1203     if (changes != NULL) {
1204       return find_witness_in(*changes, context_type, participants_hide_witnesses);
1205     } else {
1206       return find_witness_anywhere(context_type, participants_hide_witnesses);
1207     }
1208   }
1209   Klass* find_witness_definer(Klass* context_type, KlassDepChange* changes = NULL) {
1210     assert(!doing_subtype_search(), "must set up a method definer search");
1211     // When looking for unexpected concrete methods,
1212     // look beneath expected ones, to see if there are overrides.
1213     const bool participants_hide_witnesses = true;
1214     // CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness.
1215     if (changes != NULL) {
1216       return find_witness_in(*changes, context_type, !participants_hide_witnesses);
1217     } else {
1218       return find_witness_anywhere(context_type, !participants_hide_witnesses);
1219     }
1220   }
1221 };
1222 
1223 #ifndef PRODUCT
1224 static int deps_find_witness_calls = 0;
1225 static int deps_find_witness_steps = 0;
1226 static int deps_find_witness_recursions = 0;
1227 static int deps_find_witness_singles = 0;
1228 static int deps_find_witness_print = 0; // set to -1 to force a final print
1229 static bool count_find_witness_calls() {
1230   if (TraceDependencies || LogCompilation) {
1231     int pcount = deps_find_witness_print + 1;
1232     bool final_stats      = (pcount == 0);
1233     bool initial_call     = (pcount == 1);
1234     bool occasional_print = ((pcount & ((1<<10) - 1)) == 0);
1235     if (pcount < 0)  pcount = 1; // crude overflow protection
1236     deps_find_witness_print = pcount;
1237     if (VerifyDependencies && initial_call) {
1238       tty->print_cr("Warning:  TraceDependencies results may be inflated by VerifyDependencies");
1239     }
1240     if (occasional_print || final_stats) {
1241       // Every now and then dump a little info about dependency searching.
1242       if (xtty != NULL) {
1243        ttyLocker ttyl;
1244        xtty->elem("deps_find_witness calls='%d' steps='%d' recursions='%d' singles='%d'",
1245                    deps_find_witness_calls,
1246                    deps_find_witness_steps,
1247                    deps_find_witness_recursions,
1248                    deps_find_witness_singles);
1249       }
1250       if (final_stats || (TraceDependencies && WizardMode)) {
1251         ttyLocker ttyl;
1252         tty->print_cr("Dependency check (find_witness) "
1253                       "calls=%d, steps=%d (avg=%.1f), recursions=%d, singles=%d",
1254                       deps_find_witness_calls,
1255                       deps_find_witness_steps,
1256                       (double)deps_find_witness_steps / deps_find_witness_calls,
1257                       deps_find_witness_recursions,
1258                       deps_find_witness_singles);
1259       }
1260     }
1261     return true;
1262   }
1263   return false;
1264 }
1265 #else
1266 #define count_find_witness_calls() (0)
1267 #endif //PRODUCT
1268 
1269 
1270 Klass* ClassHierarchyWalker::find_witness_in(KlassDepChange& changes,
1271                                                Klass* context_type,
1272                                                bool participants_hide_witnesses) {
1273   assert(changes.involves_context(context_type), "irrelevant dependency");
1274   Klass* new_type = changes.new_type();
1275 
1276   (void)count_find_witness_calls();
1277   NOT_PRODUCT(deps_find_witness_singles++);
1278 
1279   // Current thread must be in VM (not native mode, as in CI):
1280   assert(must_be_in_vm(), "raw oops here");
1281   // Must not move the class hierarchy during this check:
1282   assert_locked_or_safepoint(Compile_lock);
1283 
1284   int nof_impls = InstanceKlass::cast(context_type)->nof_implementors();
1285   if (nof_impls > 1) {
1286     // Avoid this case: *I.m > { A.m, C }; B.m > C
1287     // %%% Until this is fixed more systematically, bail out.
1288     // See corresponding comment in find_witness_anywhere.
1289     return context_type;
1290   }
1291 
1292   assert(!is_participant(new_type), "only old classes are participants");
1293   if (participants_hide_witnesses) {
1294     // If the new type is a subtype of a participant, we are done.
1295     for (int i = 0; i < num_participants(); i++) {
1296       Klass* part = participant(i);
1297       if (part == NULL)  continue;
1298       assert(changes.involves_context(part) == new_type->is_subtype_of(part),
1299              "correct marking of participants, b/c new_type is unique");
1300       if (changes.involves_context(part)) {
1301         // new guy is protected from this check by previous participant
1302         return NULL;
1303       }
1304     }
1305   }
1306 
1307   if (is_witness(new_type) &&
1308       !ignore_witness(new_type)) {
1309     return new_type;
1310   }
1311 
1312   return NULL;
1313 }
1314 
1315 
1316 // Walk hierarchy under a context type, looking for unexpected types.
1317 // Do not report participant types, and recursively walk beneath
1318 // them only if participants_hide_witnesses is false.
1319 // If top_level_call is false, skip testing the context type,
1320 // because the caller has already considered it.
1321 Klass* ClassHierarchyWalker::find_witness_anywhere(Klass* context_type,
1322                                                      bool participants_hide_witnesses,
1323                                                      bool top_level_call) {
1324   // Current thread must be in VM (not native mode, as in CI):
1325   assert(must_be_in_vm(), "raw oops here");
1326   // Must not move the class hierarchy during this check:
1327   assert_locked_or_safepoint(Compile_lock);
1328 
1329   bool do_counts = count_find_witness_calls();
1330 
1331   // Check the root of the sub-hierarchy first.
1332   if (top_level_call) {
1333     if (do_counts) {
1334       NOT_PRODUCT(deps_find_witness_calls++);
1335       NOT_PRODUCT(deps_find_witness_steps++);
1336     }
1337     if (is_participant(context_type)) {
1338       if (participants_hide_witnesses)  return NULL;
1339       // else fall through to search loop...
1340     } else if (is_witness(context_type) && !ignore_witness(context_type)) {
1341       // The context is an abstract class or interface, to start with.
1342       return context_type;
1343     }
1344   }
1345 
1346   // Now we must check each implementor and each subclass.
1347   // Use a short worklist to avoid blowing the stack.
1348   // Each worklist entry is a *chain* of subklass siblings to process.
1349   const int CHAINMAX = 100;  // >= 1 + InstanceKlass::implementors_limit
1350   Klass* chains[CHAINMAX];
1351   int    chaini = 0;  // index into worklist
1352   Klass* chain;       // scratch variable
1353 #define ADD_SUBCLASS_CHAIN(k)                     {  \
1354     assert(chaini < CHAINMAX, "oob");                \
1355     chain = k->subklass();                           \
1356     if (chain != NULL)  chains[chaini++] = chain;    }
1357 
1358   // Look for non-abstract subclasses.
1359   // (Note:  Interfaces do not have subclasses.)
1360   ADD_SUBCLASS_CHAIN(context_type);
1361 
1362   // If it is an interface, search its direct implementors.
1363   // (Their subclasses are additional indirect implementors.
1364   // See InstanceKlass::add_implementor.)
1365   // (Note:  nof_implementors is always zero for non-interfaces.)
1366   if (top_level_call) {
1367     int nof_impls = InstanceKlass::cast(context_type)->nof_implementors();
1368     if (nof_impls > 1) {
1369       // Avoid this case: *I.m > { A.m, C }; B.m > C
1370       // Here, I.m has 2 concrete implementations, but m appears unique
1371       // as A.m, because the search misses B.m when checking C.
1372       // The inherited method B.m was getting missed by the walker
1373       // when interface 'I' was the starting point.
1374       // %%% Until this is fixed more systematically, bail out.
1375       // (Old CHA had the same limitation.)
1376       return context_type;
1377     }
1378     if (nof_impls > 0) {
1379       Klass* impl = InstanceKlass::cast(context_type)->implementor();
1380       assert(impl != NULL, "just checking");
1381       // If impl is the same as the context_type, then more than one
1382       // implementor has seen. No exact info in this case.
1383       if (impl == context_type) {
1384         return context_type;  // report an inexact witness to this sad affair
1385       }
1386       if (do_counts)
1387         { NOT_PRODUCT(deps_find_witness_steps++); }
1388       if (is_participant(impl)) {
1389         if (!participants_hide_witnesses) {
1390           ADD_SUBCLASS_CHAIN(impl);
1391         }
1392       } else if (is_witness(impl) && !ignore_witness(impl)) {
1393         return impl;
1394       } else {
1395         ADD_SUBCLASS_CHAIN(impl);
1396       }
1397     }
1398   }
1399 
1400   // Recursively process each non-trivial sibling chain.
1401   while (chaini > 0) {
1402     Klass* chain = chains[--chaini];
1403     for (Klass* sub = chain; sub != NULL; sub = sub->next_sibling()) {
1404       if (do_counts) { NOT_PRODUCT(deps_find_witness_steps++); }
1405       if (is_participant(sub)) {
1406         if (participants_hide_witnesses)  continue;
1407         // else fall through to process this guy's subclasses
1408       } else if (is_witness(sub) && !ignore_witness(sub)) {
1409         return sub;
1410       }
1411       if (chaini < (VerifyDependencies? 2: CHAINMAX)) {
1412         // Fast path.  (Partially disabled if VerifyDependencies.)
1413         ADD_SUBCLASS_CHAIN(sub);
1414       } else {
1415         // Worklist overflow.  Do a recursive call.  Should be rare.
1416         // The recursive call will have its own worklist, of course.
1417         // (Note that sub has already been tested, so that there is
1418         // no need for the recursive call to re-test.  That's handy,
1419         // since the recursive call sees sub as the context_type.)
1420         if (do_counts) { NOT_PRODUCT(deps_find_witness_recursions++); }
1421         Klass* witness = find_witness_anywhere(sub,
1422                                                  participants_hide_witnesses,
1423                                                  /*top_level_call=*/ false);
1424         if (witness != NULL)  return witness;
1425       }
1426     }
1427   }
1428 
1429   // No witness found.  The dependency remains unbroken.
1430   return NULL;
1431 #undef ADD_SUBCLASS_CHAIN
1432 }
1433 
1434 
1435 bool Dependencies::is_concrete_klass(Klass* k) {
1436   if (k->is_abstract())  return false;
1437   // %%% We could treat classes which are concrete but
1438   // have not yet been instantiated as virtually abstract.
1439   // This would require a deoptimization barrier on first instantiation.
1440   //if (k->is_not_instantiated())  return false;
1441   return true;
1442 }
1443 
1444 bool Dependencies::is_concrete_method(Method* m, Klass * k) {
1445   // NULL is not a concrete method,
1446   // statics are irrelevant to virtual call sites,
1447   // abstract methods are not concrete,
1448   // overpass (error) methods are not concrete if k is abstract
1449   //
1450   // note "true" is conservative answer --
1451   //     overpass clause is false if k == NULL, implies return true if
1452   //     answer depends on overpass clause.
1453   return ! ( m == NULL || m -> is_static() || m -> is_abstract() ||
1454              m->is_overpass() && k != NULL && k -> is_abstract() );
1455 }
1456 
1457 
1458 Klass* Dependencies::find_finalizable_subclass(Klass* k) {
1459   if (k->is_interface())  return NULL;
1460   if (k->has_finalizer()) return k;
1461   k = k->subklass();
1462   while (k != NULL) {
1463     Klass* result = find_finalizable_subclass(k);
1464     if (result != NULL) return result;
1465     k = k->next_sibling();
1466   }
1467   return NULL;
1468 }
1469 
1470 
1471 bool Dependencies::is_concrete_klass(ciInstanceKlass* k) {
1472   if (k->is_abstract())  return false;
1473   // We could also return false if k does not yet appear to be
1474   // instantiated, if the VM version supports this distinction also.
1475   //if (k->is_not_instantiated())  return false;
1476   return true;
1477 }
1478 
1479 bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) {
1480   return k->has_finalizable_subclass();
1481 }
1482 
1483 
1484 // Any use of the contents (bytecodes) of a method must be
1485 // marked by an "evol_method" dependency, if those contents
1486 // can change.  (Note: A method is always dependent on itself.)
1487 Klass* Dependencies::check_evol_method(Method* m) {
1488   assert(must_be_in_vm(), "raw oops here");
1489   // Did somebody do a JVMTI RedefineClasses while our backs were turned?
1490   // Or is there a now a breakpoint?
1491   // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.)
1492   if (m->is_old()
1493       || m->number_of_breakpoints() > 0) {
1494     return m->method_holder();
1495   } else {
1496     return NULL;
1497   }
1498 }
1499 
1500 // This is a strong assertion:  It is that the given type
1501 // has no subtypes whatever.  It is most useful for
1502 // optimizing checks on reflected types or on array types.
1503 // (Checks on types which are derived from real instances
1504 // can be optimized more strongly than this, because we
1505 // know that the checked type comes from a concrete type,
1506 // and therefore we can disregard abstract types.)
1507 Klass* Dependencies::check_leaf_type(Klass* ctxk) {
1508   assert(must_be_in_vm(), "raw oops here");
1509   assert_locked_or_safepoint(Compile_lock);
1510   InstanceKlass* ctx = InstanceKlass::cast(ctxk);
1511   Klass* sub = ctx->subklass();
1512   if (sub != NULL) {
1513     return sub;
1514   } else if (ctx->nof_implementors() != 0) {
1515     // if it is an interface, it must be unimplemented
1516     // (if it is not an interface, nof_implementors is always zero)
1517     Klass* impl = ctx->implementor();
1518     assert(impl != NULL, "must be set");
1519     return impl;
1520   } else {
1521     return NULL;
1522   }
1523 }
1524 
1525 // Test the assertion that conck is the only concrete subtype* of ctxk.
1526 // The type conck itself is allowed to have have further concrete subtypes.
1527 // This allows the compiler to narrow occurrences of ctxk by conck,
1528 // when dealing with the types of actual instances.
1529 Klass* Dependencies::check_abstract_with_unique_concrete_subtype(Klass* ctxk,
1530                                                                    Klass* conck,
1531                                                                    KlassDepChange* changes) {
1532   ClassHierarchyWalker wf(conck);
1533   return wf.find_witness_subtype(ctxk, changes);
1534 }
1535 
1536 // If a non-concrete class has no concrete subtypes, it is not (yet)
1537 // instantiatable.  This can allow the compiler to make some paths go
1538 // dead, if they are gated by a test of the type.
1539 Klass* Dependencies::check_abstract_with_no_concrete_subtype(Klass* ctxk,
1540                                                                KlassDepChange* changes) {
1541   // Find any concrete subtype, with no participants:
1542   ClassHierarchyWalker wf;
1543   return wf.find_witness_subtype(ctxk, changes);
1544 }
1545 
1546 
1547 // If a concrete class has no concrete subtypes, it can always be
1548 // exactly typed.  This allows the use of a cheaper type test.
1549 Klass* Dependencies::check_concrete_with_no_concrete_subtype(Klass* ctxk,
1550                                                                KlassDepChange* changes) {
1551   // Find any concrete subtype, with only the ctxk as participant:
1552   ClassHierarchyWalker wf(ctxk);
1553   return wf.find_witness_subtype(ctxk, changes);
1554 }
1555 
1556 
1557 // Find the unique concrete proper subtype of ctxk, or NULL if there
1558 // is more than one concrete proper subtype.  If there are no concrete
1559 // proper subtypes, return ctxk itself, whether it is concrete or not.
1560 // The returned subtype is allowed to have have further concrete subtypes.
1561 // That is, return CC1 for CX > CC1 > CC2, but NULL for CX > { CC1, CC2 }.
1562 Klass* Dependencies::find_unique_concrete_subtype(Klass* ctxk) {
1563   ClassHierarchyWalker wf(ctxk);   // Ignore ctxk when walking.
1564   wf.record_witnesses(1);          // Record one other witness when walking.
1565   Klass* wit = wf.find_witness_subtype(ctxk);
1566   if (wit != NULL)  return NULL;   // Too many witnesses.
1567   Klass* conck = wf.participant(0);
1568   if (conck == NULL) {
1569 #ifndef PRODUCT
1570     // Make sure the dependency mechanism will pass this discovery:
1571     if (VerifyDependencies) {
1572       // Turn off dependency tracing while actually testing deps.
1573       FlagSetting fs(TraceDependencies, false);
1574       if (!Dependencies::is_concrete_klass(ctxk)) {
1575         guarantee(NULL ==
1576                   (void *)check_abstract_with_no_concrete_subtype(ctxk),
1577                   "verify dep.");
1578       } else {
1579         guarantee(NULL ==
1580                   (void *)check_concrete_with_no_concrete_subtype(ctxk),
1581                   "verify dep.");
1582       }
1583     }
1584 #endif //PRODUCT
1585     return ctxk;                   // Return ctxk as a flag for "no subtypes".
1586   } else {
1587 #ifndef PRODUCT
1588     // Make sure the dependency mechanism will pass this discovery:
1589     if (VerifyDependencies) {
1590       // Turn off dependency tracing while actually testing deps.
1591       FlagSetting fs(TraceDependencies, false);
1592       if (!Dependencies::is_concrete_klass(ctxk)) {
1593         guarantee(NULL == (void *)
1594                   check_abstract_with_unique_concrete_subtype(ctxk, conck),
1595                   "verify dep.");
1596       }
1597     }
1598 #endif //PRODUCT
1599     return conck;
1600   }
1601 }
1602 
1603 // Test the assertion that the k[12] are the only concrete subtypes of ctxk,
1604 // except possibly for further subtypes of k[12] themselves.
1605 // The context type must be abstract.  The types k1 and k2 are themselves
1606 // allowed to have further concrete subtypes.
1607 Klass* Dependencies::check_abstract_with_exclusive_concrete_subtypes(
1608                                                 Klass* ctxk,
1609                                                 Klass* k1,
1610                                                 Klass* k2,
1611                                                 KlassDepChange* changes) {
1612   ClassHierarchyWalker wf;
1613   wf.add_participant(k1);
1614   wf.add_participant(k2);
1615   return wf.find_witness_subtype(ctxk, changes);
1616 }
1617 
1618 // Search ctxk for concrete implementations.  If there are klen or fewer,
1619 // pack them into the given array and return the number.
1620 // Otherwise, return -1, meaning the given array would overflow.
1621 // (Note that a return of 0 means there are exactly no concrete subtypes.)
1622 // In this search, if ctxk is concrete, it will be reported alone.
1623 // For any type CC reported, no proper subtypes of CC will be reported.
1624 int Dependencies::find_exclusive_concrete_subtypes(Klass* ctxk,
1625                                                    int klen,
1626                                                    Klass* karray[]) {
1627   ClassHierarchyWalker wf;
1628   wf.record_witnesses(klen);
1629   Klass* wit = wf.find_witness_subtype(ctxk);
1630   if (wit != NULL)  return -1;  // Too many witnesses.
1631   int num = wf.num_participants();
1632   assert(num <= klen, "oob");
1633   // Pack the result array with the good news.
1634   for (int i = 0; i < num; i++)
1635     karray[i] = wf.participant(i);
1636 #ifndef PRODUCT
1637   // Make sure the dependency mechanism will pass this discovery:
1638   if (VerifyDependencies) {
1639     // Turn off dependency tracing while actually testing deps.
1640     FlagSetting fs(TraceDependencies, false);
1641     switch (Dependencies::is_concrete_klass(ctxk)? -1: num) {
1642     case -1: // ctxk was itself concrete
1643       guarantee(num == 1 && karray[0] == ctxk, "verify dep.");
1644       break;
1645     case 0:
1646       guarantee(NULL == (void *)check_abstract_with_no_concrete_subtype(ctxk),
1647                 "verify dep.");
1648       break;
1649     case 1:
1650       guarantee(NULL == (void *)
1651                 check_abstract_with_unique_concrete_subtype(ctxk, karray[0]),
1652                 "verify dep.");
1653       break;
1654     case 2:
1655       guarantee(NULL == (void *)
1656                 check_abstract_with_exclusive_concrete_subtypes(ctxk,
1657                                                                 karray[0],
1658                                                                 karray[1]),
1659                 "verify dep.");
1660       break;
1661     default:
1662       ShouldNotReachHere();  // klen > 2 yet supported
1663     }
1664   }
1665 #endif //PRODUCT
1666   return num;
1667 }
1668 
1669 // If a class (or interface) has a unique concrete method uniqm, return NULL.
1670 // Otherwise, return a class that contains an interfering method.
1671 Klass* Dependencies::check_unique_concrete_method(Klass* ctxk, Method* uniqm,
1672                                                     KlassDepChange* changes) {
1673   // Here is a missing optimization:  If uniqm->is_final(),
1674   // we don't really need to search beneath it for overrides.
1675   // This is probably not important, since we don't use dependencies
1676   // to track final methods.  (They can't be "definalized".)
1677   ClassHierarchyWalker wf(uniqm->method_holder(), uniqm);
1678   return wf.find_witness_definer(ctxk, changes);
1679 }
1680 
1681 // Find the set of all non-abstract methods under ctxk that match m.
1682 // (The method m must be defined or inherited in ctxk.)
1683 // Include m itself in the set, unless it is abstract.
1684 // If this set has exactly one element, return that element.
1685 Method* Dependencies::find_unique_concrete_method(Klass* ctxk, Method* m) {
1686   // Return NULL if m is marked old; must have been a redefined method.
1687   if (m->is_old()) {
1688     return NULL;
1689   }
1690   ClassHierarchyWalker wf(m);
1691   assert(wf.check_method_context(ctxk, m), "proper context");
1692   wf.record_witnesses(1);
1693   Klass* wit = wf.find_witness_definer(ctxk);
1694   if (wit != NULL)  return NULL;  // Too many witnesses.
1695   Method* fm = wf.found_method(0);  // Will be NULL if num_parts == 0.
1696   if (Dependencies::is_concrete_method(m, ctxk)) {
1697     if (fm == NULL) {
1698       // It turns out that m was always the only implementation.
1699       fm = m;
1700     } else if (fm != m) {
1701       // Two conflicting implementations after all.
1702       // (This can happen if m is inherited into ctxk and fm overrides it.)
1703       return NULL;
1704     }
1705   }
1706 #ifndef PRODUCT
1707   // Make sure the dependency mechanism will pass this discovery:
1708   if (VerifyDependencies && fm != NULL) {
1709     guarantee(NULL == (void *)check_unique_concrete_method(ctxk, fm),
1710               "verify dep.");
1711   }
1712 #endif //PRODUCT
1713   return fm;
1714 }
1715 
1716 Klass* Dependencies::check_exclusive_concrete_methods(Klass* ctxk,
1717                                                         Method* m1,
1718                                                         Method* m2,
1719                                                         KlassDepChange* changes) {
1720   ClassHierarchyWalker wf(m1);
1721   wf.add_participant(m1->method_holder());
1722   wf.add_participant(m2->method_holder());
1723   return wf.find_witness_definer(ctxk, changes);
1724 }
1725 
1726 Klass* Dependencies::check_has_no_finalizable_subclasses(Klass* ctxk, KlassDepChange* changes) {
1727   Klass* search_at = ctxk;
1728   if (changes != NULL)
1729     search_at = changes->new_type(); // just look at the new bit
1730   return find_finalizable_subclass(search_at);
1731 }
1732 
1733 Klass* Dependencies::check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes) {
1734   assert(!oopDesc::is_null(call_site), "sanity");
1735   assert(!oopDesc::is_null(method_handle), "sanity");
1736   assert(call_site->is_a(SystemDictionary::CallSite_klass()),     "sanity");
1737 
1738   if (changes == NULL) {
1739     // Validate all CallSites
1740     if (java_lang_invoke_CallSite::target(call_site) != method_handle)
1741       return call_site->klass();  // assertion failed
1742   } else {
1743     // Validate the given CallSite
1744     if (call_site == changes->call_site() && java_lang_invoke_CallSite::target(call_site) != changes->method_handle()) {
1745       assert(method_handle != changes->method_handle(), "must be");
1746       return call_site->klass();  // assertion failed
1747     }
1748   }
1749   return NULL;  // assertion still valid
1750 }
1751 
1752 void Dependencies::DepStream::trace_and_log_witness(Klass* witness) {
1753   if (witness != NULL) {
1754     if (TraceDependencies) {
1755       print_dependency(witness, /*verbose=*/ true);
1756     }
1757     // The following is a no-op unless logging is enabled:
1758     log_dependency(witness);
1759   }
1760 }
1761 
1762 
1763 Klass* Dependencies::DepStream::check_klass_dependency(KlassDepChange* changes) {
1764   assert_locked_or_safepoint(Compile_lock);
1765   Dependencies::check_valid_dependency_type(type());
1766 
1767   Klass* witness = NULL;
1768   switch (type()) {
1769   case evol_method:
1770     witness = check_evol_method(method_argument(0));
1771     break;
1772   case leaf_type:
1773     witness = check_leaf_type(context_type());
1774     break;
1775   case abstract_with_unique_concrete_subtype:
1776     witness = check_abstract_with_unique_concrete_subtype(context_type(), type_argument(1), changes);
1777     break;
1778   case abstract_with_no_concrete_subtype:
1779     witness = check_abstract_with_no_concrete_subtype(context_type(), changes);
1780     break;
1781   case concrete_with_no_concrete_subtype:
1782     witness = check_concrete_with_no_concrete_subtype(context_type(), changes);
1783     break;
1784   case unique_concrete_method:
1785     witness = check_unique_concrete_method(context_type(), method_argument(1), changes);
1786     break;
1787   case abstract_with_exclusive_concrete_subtypes_2:
1788     witness = check_abstract_with_exclusive_concrete_subtypes(context_type(), type_argument(1), type_argument(2), changes);
1789     break;
1790   case exclusive_concrete_methods_2:
1791     witness = check_exclusive_concrete_methods(context_type(), method_argument(1), method_argument(2), changes);
1792     break;
1793   case no_finalizable_subclasses:
1794     witness = check_has_no_finalizable_subclasses(context_type(), changes);
1795     break;
1796   default:
1797     witness = NULL;
1798     break;
1799   }
1800   trace_and_log_witness(witness);
1801   return witness;
1802 }
1803 
1804 
1805 Klass* Dependencies::DepStream::check_call_site_dependency(CallSiteDepChange* changes) {
1806   assert_locked_or_safepoint(Compile_lock);
1807   Dependencies::check_valid_dependency_type(type());
1808 
1809   Klass* witness = NULL;
1810   switch (type()) {
1811   case call_site_target_value:
1812     witness = check_call_site_target_value(argument_oop(0), argument_oop(1), changes);
1813     break;
1814   default:
1815     witness = NULL;
1816     break;
1817   }
1818   trace_and_log_witness(witness);
1819   return witness;
1820 }
1821 
1822 
1823 Klass* Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) {
1824   // Handle klass dependency
1825   if (changes.is_klass_change() && changes.as_klass_change()->involves_context(context_type()))
1826     return check_klass_dependency(changes.as_klass_change());
1827 
1828   // Handle CallSite dependency
1829   if (changes.is_call_site_change())
1830     return check_call_site_dependency(changes.as_call_site_change());
1831 
1832   // irrelevant dependency; skip it
1833   return NULL;
1834 }
1835 
1836 
1837 void DepChange::print() {
1838   int nsup = 0, nint = 0;
1839   for (ContextStream str(*this); str.next(); ) {
1840     Klass* k = str.klass();
1841     switch (str.change_type()) {
1842     case Change_new_type:
1843       tty->print_cr("  dependee = %s", k->external_name());
1844       break;
1845     case Change_new_sub:
1846       if (!WizardMode) {
1847         ++nsup;
1848       } else {
1849         tty->print_cr("  context super = %s", k->external_name());
1850       }
1851       break;
1852     case Change_new_impl:
1853       if (!WizardMode) {
1854         ++nint;
1855       } else {
1856         tty->print_cr("  context interface = %s", k->external_name());
1857       }
1858       break;
1859     }
1860   }
1861   if (nsup + nint != 0) {
1862     tty->print_cr("  context supers = %d, interfaces = %d", nsup, nint);
1863   }
1864 }
1865 
1866 void DepChange::ContextStream::start() {
1867   Klass* new_type = _changes.is_klass_change() ? _changes.as_klass_change()->new_type() : (Klass*) NULL;
1868   _change_type = (new_type == NULL ? NO_CHANGE : Start_Klass);
1869   _klass = new_type;
1870   _ti_base = NULL;
1871   _ti_index = 0;
1872   _ti_limit = 0;
1873 }
1874 
1875 bool DepChange::ContextStream::next() {
1876   switch (_change_type) {
1877   case Start_Klass:             // initial state; _klass is the new type
1878     _ti_base = InstanceKlass::cast(_klass)->transitive_interfaces();
1879     _ti_index = 0;
1880     _change_type = Change_new_type;
1881     return true;
1882   case Change_new_type:
1883     // fall through:
1884     _change_type = Change_new_sub;
1885   case Change_new_sub:
1886     // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277
1887     {
1888       _klass = _klass->super();
1889       if (_klass != NULL) {
1890         return true;
1891       }
1892     }
1893     // else set up _ti_limit and fall through:
1894     _ti_limit = (_ti_base == NULL) ? 0 : _ti_base->length();
1895     _change_type = Change_new_impl;
1896   case Change_new_impl:
1897     if (_ti_index < _ti_limit) {
1898       _klass = _ti_base->at(_ti_index++);
1899       return true;
1900     }
1901     // fall through:
1902     _change_type = NO_CHANGE;  // iterator is exhausted
1903   case NO_CHANGE:
1904     break;
1905   default:
1906     ShouldNotReachHere();
1907   }
1908   return false;
1909 }
1910 
1911 void KlassDepChange::initialize() {
1912   // entire transaction must be under this lock:
1913   assert_lock_strong(Compile_lock);
1914 
1915   // Mark all dependee and all its superclasses
1916   // Mark transitive interfaces
1917   for (ContextStream str(*this); str.next(); ) {
1918     Klass* d = str.klass();
1919     assert(!InstanceKlass::cast(d)->is_marked_dependent(), "checking");
1920     InstanceKlass::cast(d)->set_is_marked_dependent(true);
1921   }
1922 }
1923 
1924 KlassDepChange::~KlassDepChange() {
1925   // Unmark all dependee and all its superclasses
1926   // Unmark transitive interfaces
1927   for (ContextStream str(*this); str.next(); ) {
1928     Klass* d = str.klass();
1929     InstanceKlass::cast(d)->set_is_marked_dependent(false);
1930   }
1931 }
1932 
1933 bool KlassDepChange::involves_context(Klass* k) {
1934   if (k == NULL || !k->is_instance_klass()) {
1935     return false;
1936   }
1937   InstanceKlass* ik = InstanceKlass::cast(k);
1938   bool is_contained = ik->is_marked_dependent();
1939   assert(is_contained == new_type()->is_subtype_of(k),
1940          "correct marking of potential context types");
1941   return is_contained;
1942 }
1943 
1944 #ifndef PRODUCT
1945 void Dependencies::print_statistics() {
1946   if (deps_find_witness_print != 0) {
1947     // Call one final time, to flush out the data.
1948     deps_find_witness_print = -1;
1949     count_find_witness_calls();
1950   }
1951 }
1952 #endif
1953 
1954 CallSiteDepChange::CallSiteDepChange(Handle call_site, Handle method_handle) :
1955   _call_site(call_site),
1956   _method_handle(method_handle) {
1957   assert(_call_site()->is_a(SystemDictionary::CallSite_klass()), "must be");
1958   assert(_method_handle.is_null() || _method_handle()->is_a(SystemDictionary::MethodHandle_klass()), "must be");
1959 }
--- EOF ---