/*

 * Copyright (c) 1999, 2010, 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 "opto/chaitin.hpp"

#include "opto/machnode.hpp"

// Disallow the use of the frame pointer (EBP) for implicit null exceptions

// on win95/98.  If we do not do this, the OS gets confused and gives a stack

// error.

void PhaseRegAlloc::pd_preallocate_hook() {

#ifndef _WIN64

  if (ImplicitNullChecks && !os::win32::is_nt()) {

    for (uint block_num=1; block_num<_cfg._num_blocks; block_num++) {

      Block *block = _cfg._blocks[block_num];

      Node *block_end = block->end();

      if (block_end->is_MachNullCheck() &&

          block_end->as_Mach()->ideal_Opcode() != Op_Con) {

        // The last instruction in the block is an implicit null check.

        // Fix its input so that it does not load into the frame pointer.

        _matcher.pd_implicit_null_fixup(block_end->in(1)->as_Mach(),

                                        block_end->as_MachNullCheck()->_vidx);

      }

    }

  }

#else

  // WIN64==itanium on XP

#endif

}

#ifdef ASSERT

// Verify that no implicit null check uses the frame pointer (EBP) as

// its register on win95/98.  Use of the frame pointer in an implicit

// null check confuses the OS, yielding a stack error.

void PhaseRegAlloc::pd_postallocate_verify_hook() {

#ifndef _WIN64

  if (ImplicitNullChecks && !os::win32::is_nt()) {

    for (uint block_num=1; block_num<_cfg._num_blocks; block_num++) {

      Block *block = _cfg._blocks[block_num];

      Node *block_end = block->_nodes[block->_nodes.size()-1];

      if (block_end->is_MachNullCheck() && block_end->as_Mach()->ideal_Opcode() != Op_Con) {

        // The last instruction in the block is an implicit

        // null check.  Verify that this instruction does not

        // use the frame pointer.

        int reg = get_reg_first(block_end->in(1)->in(block_end->as_MachNullCheck()->_vidx));

        assert(reg != EBP_num,

               "implicit null check using frame pointer on win95/98");

      }

    }

  }

#else

  // WIN64==itanium on XP

#endif

}

#endif