--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/prims/methodComparator.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,383 @@
+/*
+ * Copyright 2000-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_methodComparator.cpp.incl"
+
+BytecodeStream *MethodComparator::_s_old;
+BytecodeStream *MethodComparator::_s_new;
+constantPoolOop MethodComparator::_old_cp;
+constantPoolOop MethodComparator::_new_cp;
+BciMap *MethodComparator::_bci_map;
+bool MethodComparator::_switchable_test;
+GrowableArray<int> *MethodComparator::_fwd_jmps;
+
+bool MethodComparator::methods_EMCP(methodOop old_method, methodOop new_method) {
+  if (old_method->code_size() != new_method->code_size())
+    return false;
+  if (check_stack_and_locals_size(old_method, new_method) != 0) {
+    // RC_TRACE macro has an embedded ResourceMark
+    RC_TRACE(0x00800000, ("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;
+  _switchable_test = false;
+  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::methods_switchable(methodOop old_method, methodOop new_method,
+                                          BciMap &bci_map) {
+  if (old_method->code_size() > new_method->code_size())
+    // Something has definitely been deleted in the new method, compared to the old one.
+    return false;
+
+  if (! 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;
+  _bci_map = &bci_map;
+  _switchable_test = true;
+  GrowableArray<int> fwd_jmps(16);
+  _fwd_jmps = &fwd_jmps;
+  Bytecodes::Code c_old, c_new;
+
+  while ((c_old = s_old.next()) >= 0) {
+    if ((c_new = s_new.next()) < 0)
+      return false;
+    if (! (c_old == c_new && args_same(c_old, c_new))) {
+      int old_bci = s_old.bci();
+      int new_st_bci = s_new.bci();
+      bool found_match = false;
+      do {
+        c_new = s_new.next();
+        if (c_new == c_old && args_same(c_old, c_new)) {
+          found_match = true;
+          break;
+        }
+      } while (c_new >= 0);
+      if (! found_match)
+        return false;
+      int new_end_bci = s_new.bci();
+      bci_map.store_fragment_location(old_bci, new_st_bci, new_end_bci);
+    }
+  }
+
+  // Now we can test all forward jumps
+  for (int i = 0; i < fwd_jmps.length() / 2; i++) {
+    if (! bci_map.old_and_new_locations_same(fwd_jmps.at(i*2), fwd_jmps.at(i*2+1))) {
+      RC_TRACE(0x00800000,
+        ("Fwd jump miss: old dest = %d, calc new dest = %d, act new dest = %d",
+        fwd_jmps.at(i*2), bci_map.new_bci_for_old(fwd_jmps.at(i*2)),
+        fwd_jmps.at(i*2+1)));
+      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_big();
+    u2 cpi_new = _s_new->get_index_big();
+    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 : {
+    u2 cpci_old = _s_old->get_index_big();
+    u2 cpci_new = _s_new->get_index_big();
+    // 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::_ldc   : // fall through
+  case Bytecodes::_ldc_w : {
+    u2 cpi_old, cpi_new;
+    if (c_old == Bytecodes::_ldc) {
+      cpi_old = _s_old->bcp()[1];
+      cpi_new = _s_new->bcp()[1];
+    } else {
+      cpi_old = _s_old->get_index_big();
+      cpi_new = _s_new->get_index_big();
+    }
+    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 {
+        if (_old_cp->float_at(cpi_old) != _new_cp->float_at(cpi_new))
+          return false;
+      }
+    } else if (tag_old.is_string() || tag_old.is_unresolved_string()) {
+      if (! (tag_new.is_unresolved_string() || tag_new.is_string()))
+        return false;
+      if (strcmp(_old_cp->string_at_noresolve(cpi_old),
+                 _new_cp->string_at_noresolve(cpi_new)) != 0)
+        return false;
+    } else { // 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;
+    }
+    break;
+  }
+
+  case Bytecodes::_ldc2_w : {
+    u2 cpi_old = _s_old->get_index_big();
+    u2 cpi_new = _s_new->get_index_big();
+    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 {
+      if (_old_cp->double_at(cpi_old) != _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_big() != _s_new->get_index_big())
+      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       : {
+    short old_ofs = (short) _s_old->get_index_big();
+    short new_ofs = (short) _s_new->get_index_big();
+    if (_switchable_test) {
+      int old_dest = _s_old->bci() + old_ofs;
+      int new_dest = _s_new->bci() + new_ofs;
+      if (old_ofs < 0 && new_ofs < 0) {
+        if (! _bci_map->old_and_new_locations_same(old_dest, new_dest))
+          return false;
+      } else if (old_ofs > 0 && new_ofs > 0) {
+        _fwd_jmps->append(old_dest);
+        _fwd_jmps->append(new_dest);
+      } else {
+        return false;
+      }
+    } else {
+      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()) {
+      if (_s_old->get_index_big() != _s_new->get_index_big())
+        return false;
+    } else {
+      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 = (int) Bytes::get_Java_u4(_s_old->bcp() + 1);
+    int new_ofs = (int) Bytes::get_Java_u4(_s_new->bcp() + 1);
+    if (_switchable_test) {
+      int old_dest = _s_old->bci() + old_ofs;
+      int new_dest = _s_new->bci() + new_ofs;
+      if (old_ofs < 0 && new_ofs < 0) {
+        if (! _bci_map->old_and_new_locations_same(old_dest, new_dest))
+          return false;
+      } else if (old_ofs > 0 && new_ofs > 0) {
+        _fwd_jmps->append(old_dest);
+        _fwd_jmps->append(new_dest);
+      } else {
+        return false;
+      }
+    } else {
+      if (old_ofs != new_ofs)
+        return false;
+    }
+    break;
+  }
+
+  case Bytecodes::_lookupswitch : // fall through
+  case Bytecodes::_tableswitch  : {
+    if (_switchable_test) {
+      address aligned_bcp_old = (address) round_to((intptr_t)_s_old->bcp() + 1, jintSize);
+      address aligned_bcp_new = (address) round_to((intptr_t)_s_new->bcp() + 1, jintSize);
+      int default_old = (int) Bytes::get_Java_u4(aligned_bcp_old);
+      int default_new = (int) Bytes::get_Java_u4(aligned_bcp_new);
+      _fwd_jmps->append(_s_old->bci() + default_old);
+      _fwd_jmps->append(_s_new->bci() + default_new);
+      if (c_old == Bytecodes::_lookupswitch) {
+        int npairs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + jintSize);
+        int npairs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + jintSize);
+        if (npairs_old != npairs_new)
+          return false;
+        for (int i = 0; i < npairs_old; i++) {
+          int match_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (2+2*i)*jintSize);
+          int match_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (2+2*i)*jintSize);
+          if (match_old != match_new)
+            return false;
+          int ofs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (2+2*i+1)*jintSize);
+          int ofs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (2+2*i+1)*jintSize);
+          _fwd_jmps->append(_s_old->bci() + ofs_old);
+          _fwd_jmps->append(_s_new->bci() + ofs_new);
+        }
+      } else if (c_old == Bytecodes::_tableswitch) {
+        int lo_old = (int) Bytes::get_Java_u4(aligned_bcp_old + jintSize);
+        int lo_new = (int) Bytes::get_Java_u4(aligned_bcp_new + jintSize);
+        if (lo_old != lo_new)
+          return false;
+        int hi_old = (int) Bytes::get_Java_u4(aligned_bcp_old + 2*jintSize);
+        int hi_new = (int) Bytes::get_Java_u4(aligned_bcp_new + 2*jintSize);
+        if (hi_old != hi_new)
+          return false;
+        for (int i = 0; i < hi_old - lo_old + 1; i++) {
+          int ofs_old = (int) Bytes::get_Java_u4(aligned_bcp_old + (3+i)*jintSize);
+          int ofs_new = (int) Bytes::get_Java_u4(aligned_bcp_new + (3+i)*jintSize);
+          _fwd_jmps->append(_s_old->bci() + ofs_old);
+          _fwd_jmps->append(_s_new->bci() + ofs_new);
+        }
+      }
+    } else { // !_switchable_test, can use fast rough compare
+      int len_old = _s_old->next_bcp() - _s_old->bcp();
+      int len_new = _s_new->next_bcp() - _s_new->bcp();
+      if (len_old != len_new)
+        return false;
+      if (memcmp(_s_old->bcp(), _s_new->bcp(), len_old) != 0)
+        return false;
+    }
+    break;
+  }
+  }
+
+  return true;
+}
+
+
+int MethodComparator::check_stack_and_locals_size(methodOop old_method, methodOop 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;
+}