--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/prims/methodComparator.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,321 @@
+/*
+ * Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "oops/oop.inline.hpp"
+#include "oops/symbol.hpp"
+#include "prims/methodComparator.hpp"
+#include "runtime/handles.inline.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+BytecodeStream *MethodComparator::_s_old;
+BytecodeStream *MethodComparator::_s_new;
+ConstantPool* MethodComparator::_old_cp;
+ConstantPool* MethodComparator::_new_cp;
+
+bool MethodComparator::methods_EMCP(Method* old_method, Method* new_method) {
+  if (old_method->code_size() != new_method->code_size())
+    return false;
+  if (check_stack_and_locals_size(old_method, new_method) != 0) {
+    if (log_is_enabled(Debug, redefine, class, methodcomparator)) {
+      ResourceMark rm;
+      log_debug(redefine, class, methodcomparator)
+        ("Methods %s non-comparable with diagnosis %d",
+         old_method->name()->as_C_string(), check_stack_and_locals_size(old_method, new_method));
+    }
+    return false;
+  }
+
+  _old_cp = old_method->constants();
+  _new_cp = new_method->constants();
+  BytecodeStream s_old(old_method);
+  BytecodeStream s_new(new_method);
+  _s_old = &s_old;
+  _s_new = &s_new;
+  Bytecodes::Code c_old, c_new;
+
+  while ((c_old = s_old.next()) >= 0) {
+    if ((c_new = s_new.next()) < 0 || c_old != c_new)
+      return false;
+
+    if (! args_same(c_old, c_new))
+      return false;
+  }
+  return true;
+}
+
+bool MethodComparator::args_same(Bytecodes::Code c_old, Bytecodes::Code c_new) {
+  // BytecodeStream returns the correct standard Java bytecodes for various "fast"
+  // bytecode versions, so we don't have to bother about them here..
+  switch (c_old) {
+  case Bytecodes::_new            : // fall through
+  case Bytecodes::_anewarray      : // fall through
+  case Bytecodes::_multianewarray : // fall through
+  case Bytecodes::_checkcast      : // fall through
+  case Bytecodes::_instanceof     : {
+    u2 cpi_old = _s_old->get_index_u2();
+    u2 cpi_new = _s_new->get_index_u2();
+    if ((_old_cp->klass_at_noresolve(cpi_old) != _new_cp->klass_at_noresolve(cpi_new)))
+        return false;
+    if (c_old == Bytecodes::_multianewarray &&
+        *(jbyte*)(_s_old->bcp() + 3) != *(jbyte*)(_s_new->bcp() + 3))
+      return false;
+    break;
+  }
+
+  case Bytecodes::_getstatic       : // fall through
+  case Bytecodes::_putstatic       : // fall through
+  case Bytecodes::_getfield        : // fall through
+  case Bytecodes::_putfield        : // fall through
+  case Bytecodes::_invokevirtual   : // fall through
+  case Bytecodes::_invokespecial   : // fall through
+  case Bytecodes::_invokestatic    : // fall through
+  case Bytecodes::_invokeinterface : {
+    int cpci_old = _s_old->get_index_u2_cpcache();
+    int cpci_new = _s_new->get_index_u2_cpcache();
+    // Check if the names of classes, field/method names and signatures at these indexes
+    // are the same. Indices which are really into constantpool cache (rather than constant
+    // pool itself) are accepted by the constantpool query routines below.
+    if ((_old_cp->klass_ref_at_noresolve(cpci_old) != _new_cp->klass_ref_at_noresolve(cpci_new)) ||
+        (_old_cp->name_ref_at(cpci_old) != _new_cp->name_ref_at(cpci_new)) ||
+        (_old_cp->signature_ref_at(cpci_old) != _new_cp->signature_ref_at(cpci_new)))
+      return false;
+    break;
+  }
+  case Bytecodes::_invokedynamic: {
+    int cpci_old = _s_old->get_index_u4();
+    int cpci_new = _s_new->get_index_u4();
+
+    // Check if the names of classes, field/method names and signatures at these indexes
+    // are the same. Indices which are really into constantpool cache (rather than constant
+    // pool itself) are accepted by the constantpool query routines below.
+    if ((_old_cp->name_ref_at(cpci_old) != _new_cp->name_ref_at(cpci_new)) ||
+        (_old_cp->signature_ref_at(cpci_old) != _new_cp->signature_ref_at(cpci_new)))
+      return false;
+
+    // Translate object indexes to constant pool cache indexes.
+    cpci_old = _old_cp->invokedynamic_cp_cache_index(cpci_old);
+    cpci_new = _new_cp->invokedynamic_cp_cache_index(cpci_new);
+
+    int cpi_old = _old_cp->cache()->entry_at(cpci_old)->constant_pool_index();
+    int cpi_new = _new_cp->cache()->entry_at(cpci_new)->constant_pool_index();
+    int bsm_old = _old_cp->invoke_dynamic_bootstrap_method_ref_index_at(cpi_old);
+    int bsm_new = _new_cp->invoke_dynamic_bootstrap_method_ref_index_at(cpi_new);
+    if (!pool_constants_same(bsm_old, bsm_new))
+      return false;
+    int cnt_old = _old_cp->invoke_dynamic_argument_count_at(cpi_old);
+    int cnt_new = _new_cp->invoke_dynamic_argument_count_at(cpi_new);
+    if (cnt_old != cnt_new)
+      return false;
+    for (int arg_i = 0; arg_i < cnt_old; arg_i++) {
+      int idx_old = _old_cp->invoke_dynamic_argument_index_at(cpi_old, arg_i);
+      int idx_new = _new_cp->invoke_dynamic_argument_index_at(cpi_new, arg_i);
+      if (!pool_constants_same(idx_old, idx_new))
+        return false;
+    }
+    break;
+  }
+
+  case Bytecodes::_ldc   : // fall through
+  case Bytecodes::_ldc_w : {
+    Bytecode_loadconstant ldc_old(_s_old->method(), _s_old->bci());
+    Bytecode_loadconstant ldc_new(_s_new->method(), _s_new->bci());
+    int cpi_old = ldc_old.pool_index();
+    int cpi_new = ldc_new.pool_index();
+    if (!pool_constants_same(cpi_old, cpi_new))
+      return false;
+    break;
+  }
+
+  case Bytecodes::_ldc2_w : {
+    u2 cpi_old = _s_old->get_index_u2();
+    u2 cpi_new = _s_new->get_index_u2();
+    constantTag tag_old = _old_cp->tag_at(cpi_old);
+    constantTag tag_new = _new_cp->tag_at(cpi_new);
+    if (tag_old.value() != tag_new.value())
+      return false;
+    if (tag_old.is_long()) {
+      if (_old_cp->long_at(cpi_old) != _new_cp->long_at(cpi_new))
+        return false;
+    } else {
+      // Use jlong_cast to compare the bits rather than numerical values.
+      // This makes a difference for NaN constants.
+      if (jlong_cast(_old_cp->double_at(cpi_old)) != jlong_cast(_new_cp->double_at(cpi_new)))
+        return false;
+    }
+    break;
+  }
+
+  case Bytecodes::_bipush :
+    if (_s_old->bcp()[1] != _s_new->bcp()[1])
+      return false;
+    break;
+
+  case Bytecodes::_sipush    :
+    if (_s_old->get_index_u2() != _s_new->get_index_u2())
+      return false;
+    break;
+
+  case Bytecodes::_aload  : // fall through
+  case Bytecodes::_astore : // fall through
+  case Bytecodes::_dload  : // fall through
+  case Bytecodes::_dstore : // fall through
+  case Bytecodes::_fload  : // fall through
+  case Bytecodes::_fstore : // fall through
+  case Bytecodes::_iload  : // fall through
+  case Bytecodes::_istore : // fall through
+  case Bytecodes::_lload  : // fall through
+  case Bytecodes::_lstore : // fall through
+  case Bytecodes::_ret    :
+    if (_s_old->is_wide() != _s_new->is_wide())
+      return false;
+    if (_s_old->get_index() != _s_new->get_index())
+      return false;
+    break;
+
+  case Bytecodes::_goto      : // fall through
+  case Bytecodes::_if_acmpeq : // fall through
+  case Bytecodes::_if_acmpne : // fall through
+  case Bytecodes::_if_icmpeq : // fall through
+  case Bytecodes::_if_icmpne : // fall through
+  case Bytecodes::_if_icmplt : // fall through
+  case Bytecodes::_if_icmpge : // fall through
+  case Bytecodes::_if_icmpgt : // fall through
+  case Bytecodes::_if_icmple : // fall through
+  case Bytecodes::_ifeq      : // fall through
+  case Bytecodes::_ifne      : // fall through
+  case Bytecodes::_iflt      : // fall through
+  case Bytecodes::_ifge      : // fall through
+  case Bytecodes::_ifgt      : // fall through
+  case Bytecodes::_ifle      : // fall through
+  case Bytecodes::_ifnonnull : // fall through
+  case Bytecodes::_ifnull    : // fall through
+  case Bytecodes::_jsr       : {
+    int old_ofs = _s_old->bytecode().get_offset_s2(c_old);
+    int new_ofs = _s_new->bytecode().get_offset_s2(c_new);
+    if (old_ofs != new_ofs)
+      return false;
+    break;
+  }
+
+  case Bytecodes::_iinc :
+    if (_s_old->is_wide() != _s_new->is_wide())
+      return false;
+    if (! _s_old->is_wide()) {
+      // We could use get_index_u1 and get_constant_u1, but it's simpler to grab both bytes at once:
+      if (Bytes::get_Java_u2(_s_old->bcp() + 1) != Bytes::get_Java_u2(_s_new->bcp() + 1))
+        return false;
+    } else {
+      // We could use get_index_u2 and get_constant_u2, but it's simpler to grab all four bytes at once:
+      if (Bytes::get_Java_u4(_s_old->bcp() + 1) != Bytes::get_Java_u4(_s_new->bcp() + 1))
+        return false;
+    }
+    break;
+
+  case Bytecodes::_goto_w : // fall through
+  case Bytecodes::_jsr_w  : {
+    int old_ofs = _s_old->bytecode().get_offset_s4(c_old);
+    int new_ofs = _s_new->bytecode().get_offset_s4(c_new);
+    if (old_ofs != new_ofs)
+      return false;
+    break;
+  }
+
+  case Bytecodes::_lookupswitch : // fall through
+  case Bytecodes::_tableswitch  : {
+    int len_old = _s_old->instruction_size();
+    int len_new = _s_new->instruction_size();
+    if (len_old != len_new)
+      return false;
+    if (memcmp(_s_old->bcp(), _s_new->bcp(), len_old) != 0)
+      return false;
+    break;
+  }
+
+  default:
+    break;
+  }
+
+  return true;
+}
+
+bool MethodComparator::pool_constants_same(int cpi_old, int cpi_new) {
+  constantTag tag_old = _old_cp->tag_at(cpi_old);
+  constantTag tag_new = _new_cp->tag_at(cpi_new);
+  if (tag_old.is_int() || tag_old.is_float()) {
+    if (tag_old.value() != tag_new.value())
+      return false;
+    if (tag_old.is_int()) {
+      if (_old_cp->int_at(cpi_old) != _new_cp->int_at(cpi_new))
+        return false;
+    } else {
+      // Use jint_cast to compare the bits rather than numerical values.
+      // This makes a difference for NaN constants.
+      if (jint_cast(_old_cp->float_at(cpi_old)) != jint_cast(_new_cp->float_at(cpi_new)))
+        return false;
+    }
+  } else if (tag_old.is_string() && tag_new.is_string()) {
+    if (strcmp(_old_cp->string_at_noresolve(cpi_old),
+               _new_cp->string_at_noresolve(cpi_new)) != 0)
+      return false;
+    if (_old_cp->is_pseudo_string_at(cpi_old) || _new_cp->is_pseudo_string_at(cpi_new))
+      return (_old_cp->is_pseudo_string_at(cpi_old) == _new_cp->is_pseudo_string_at(cpi_new));
+  } else if (tag_old.is_klass() || tag_old.is_unresolved_klass()) {
+    // tag_old should be klass - 4881222
+    if (! (tag_new.is_unresolved_klass() || tag_new.is_klass()))
+      return false;
+    if (_old_cp->klass_at_noresolve(cpi_old) !=
+        _new_cp->klass_at_noresolve(cpi_new))
+      return false;
+  } else if (tag_old.is_method_type() && tag_new.is_method_type()) {
+    int mti_old = _old_cp->method_type_index_at(cpi_old);
+    int mti_new = _new_cp->method_type_index_at(cpi_new);
+    if ((_old_cp->symbol_at(mti_old) != _new_cp->symbol_at(mti_new)))
+      return false;
+  } else if (tag_old.is_method_handle() && tag_new.is_method_handle()) {
+    if (_old_cp->method_handle_ref_kind_at(cpi_old) !=
+        _new_cp->method_handle_ref_kind_at(cpi_new))
+      return false;
+    int mhi_old = _old_cp->method_handle_index_at(cpi_old);
+    int mhi_new = _new_cp->method_handle_index_at(cpi_new);
+    if ((_old_cp->uncached_klass_ref_at_noresolve(mhi_old) != _new_cp->uncached_klass_ref_at_noresolve(mhi_new)) ||
+        (_old_cp->uncached_name_ref_at(mhi_old) != _new_cp->uncached_name_ref_at(mhi_new)) ||
+        (_old_cp->uncached_signature_ref_at(mhi_old) != _new_cp->uncached_signature_ref_at(mhi_new)))
+      return false;
+  } else {
+    return false;  // unknown tag
+  }
+  return true;
+}
+
+
+int MethodComparator::check_stack_and_locals_size(Method* old_method, Method* new_method) {
+  if (old_method->max_stack() != new_method->max_stack()) {
+    return 1;
+  } else if (old_method->max_locals() != new_method->max_locals()) {
+    return 2;
+  } else if (old_method->size_of_parameters() != new_method->size_of_parameters()) {
+    return 3;
+  } else return 0;
+}