duke@435: /*
stefank@2314:  * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "opto/chaitin.hpp"
stefank@2314: #include "opto/machnode.hpp"
duke@435: 
duke@435: // Disallow the use of the frame pointer (EBP) for implicit null exceptions
duke@435: // on win95/98.  If we do not do this, the OS gets confused and gives a stack
duke@435: // error.
duke@435: void PhaseRegAlloc::pd_preallocate_hook() {
duke@435: #ifndef _WIN64
duke@435:   if (ImplicitNullChecks && !os::win32::is_nt()) {
duke@435:     for (uint block_num=1; block_num<_cfg._num_blocks; block_num++) {
duke@435:       Block *block = _cfg._blocks[block_num];
duke@435: 
duke@435:       Node *block_end = block->end();
duke@435:       if (block_end->is_MachNullCheck() &&
duke@435:           block_end->as_Mach()->ideal_Opcode() != Op_Con) {
duke@435:         // The last instruction in the block is an implicit null check.
duke@435:         // Fix its input so that it does not load into the frame pointer.
duke@435:         _matcher.pd_implicit_null_fixup(block_end->in(1)->as_Mach(),
duke@435:                                         block_end->as_MachNullCheck()->_vidx);
duke@435:       }
duke@435:     }
duke@435:   }
duke@435: #else
duke@435:   // WIN64==itanium on XP
duke@435: #endif
duke@435: }
duke@435: 
duke@435: #ifdef ASSERT
duke@435: // Verify that no implicit null check uses the frame pointer (EBP) as
duke@435: // its register on win95/98.  Use of the frame pointer in an implicit
duke@435: // null check confuses the OS, yielding a stack error.
duke@435: void PhaseRegAlloc::pd_postallocate_verify_hook() {
duke@435: #ifndef _WIN64
duke@435:   if (ImplicitNullChecks && !os::win32::is_nt()) {
duke@435:     for (uint block_num=1; block_num<_cfg._num_blocks; block_num++) {
duke@435:       Block *block = _cfg._blocks[block_num];
duke@435: 
duke@435:       Node *block_end = block->_nodes[block->_nodes.size()-1];
duke@435:       if (block_end->is_MachNullCheck() && block_end->as_Mach()->ideal_Opcode() != Op_Con) {
duke@435:         // The last instruction in the block is an implicit
duke@435:         // null check.  Verify that this instruction does not
duke@435:         // use the frame pointer.
duke@435:         int reg = get_reg_first(block_end->in(1)->in(block_end->as_MachNullCheck()->_vidx));
duke@435:         assert(reg != EBP_num,
duke@435:                "implicit null check using frame pointer on win95/98");
duke@435:       }
duke@435:     }
duke@435:   }
duke@435: #else
duke@435:   // WIN64==itanium on XP
duke@435: #endif
duke@435: }
duke@435: #endif