1 /*
   2  * Copyright (c) 1999, 2006, 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 "incls/_precompiled.incl"
  26 #include "incls/_chaitin_windows.cpp.incl"
  27 
  28 // Disallow the use of the frame pointer (EBP) for implicit null exceptions
  29 // on win95/98.  If we do not do this, the OS gets confused and gives a stack
  30 // error.
  31 void PhaseRegAlloc::pd_preallocate_hook() {
  32 #ifndef _WIN64
  33   if (ImplicitNullChecks && !os::win32::is_nt()) {
  34     for (uint block_num=1; block_num<_cfg._num_blocks; block_num++) {
  35       Block *block = _cfg._blocks[block_num];
  36 
  37       Node *block_end = block->end();
  38       if (block_end->is_MachNullCheck() &&
  39           block_end->as_Mach()->ideal_Opcode() != Op_Con) {
  40         // The last instruction in the block is an implicit null check.
  41         // Fix its input so that it does not load into the frame pointer.
  42         _matcher.pd_implicit_null_fixup(block_end->in(1)->as_Mach(),
  43                                         block_end->as_MachNullCheck()->_vidx);
  44       }
  45     }
  46   }
  47 #else
  48   // WIN64==itanium on XP
  49 #endif
  50 }
  51 
  52 #ifdef ASSERT
  53 // Verify that no implicit null check uses the frame pointer (EBP) as
  54 // its register on win95/98.  Use of the frame pointer in an implicit
  55 // null check confuses the OS, yielding a stack error.
  56 void PhaseRegAlloc::pd_postallocate_verify_hook() {
  57 #ifndef _WIN64
  58   if (ImplicitNullChecks && !os::win32::is_nt()) {
  59     for (uint block_num=1; block_num<_cfg._num_blocks; block_num++) {
  60       Block *block = _cfg._blocks[block_num];
  61 
  62       Node *block_end = block->_nodes[block->_nodes.size()-1];
  63       if (block_end->is_MachNullCheck() && block_end->as_Mach()->ideal_Opcode() != Op_Con) {
  64         // The last instruction in the block is an implicit
  65         // null check.  Verify that this instruction does not
  66         // use the frame pointer.
  67         int reg = get_reg_first(block_end->in(1)->in(block_end->as_MachNullCheck()->_vidx));
  68         assert(reg != EBP_num,
  69                "implicit null check using frame pointer on win95/98");
  70       }
  71     }
  72   }
  73 #else
  74   // WIN64==itanium on XP
  75 #endif
  76 }
  77 #endif