1 /* 2 * Copyright (c) 1999, 2010, 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 "precompiled.hpp" 26 #include "opto/chaitin.hpp" 27 #include "opto/machnode.hpp" 28 29 // Disallow the use of the frame pointer (EBP) for implicit null exceptions 30 // on win95/98. If we do not do this, the OS gets confused and gives a stack 31 // error. 32 void PhaseRegAlloc::pd_preallocate_hook() { 33 #ifndef _WIN64 34 if (ImplicitNullChecks && !os::win32::is_nt()) { 35 for (uint block_num=1; block_num<_cfg._num_blocks; block_num++) { 36 Block *block = _cfg._blocks[block_num]; 37 38 Node *block_end = block->end(); 39 if (block_end->is_MachNullCheck() && 40 block_end->as_Mach()->ideal_Opcode() != Op_Con) { 41 // The last instruction in the block is an implicit null check. 42 // Fix its input so that it does not load into the frame pointer. 43 _matcher.pd_implicit_null_fixup(block_end->in(1)->as_Mach(), 44 block_end->as_MachNullCheck()->_vidx); 45 } 46 } 47 } 48 #else 49 // WIN64==itanium on XP 50 #endif 51 } 52 53 #ifdef ASSERT 54 // Verify that no implicit null check uses the frame pointer (EBP) as 55 // its register on win95/98. Use of the frame pointer in an implicit 56 // null check confuses the OS, yielding a stack error. 57 void PhaseRegAlloc::pd_postallocate_verify_hook() { 58 #ifndef _WIN64 59 if (ImplicitNullChecks && !os::win32::is_nt()) { 60 for (uint block_num=1; block_num<_cfg._num_blocks; block_num++) { 61 Block *block = _cfg._blocks[block_num]; 62 63 Node *block_end = block->_nodes[block->_nodes.size()-1]; 64 if (block_end->is_MachNullCheck() && block_end->as_Mach()->ideal_Opcode() != Op_Con) { 65 // The last instruction in the block is an implicit 66 // null check. Verify that this instruction does not 67 // use the frame pointer. 68 int reg = get_reg_first(block_end->in(1)->in(block_end->as_MachNullCheck()->_vidx)); 69 assert(reg != EBP_num, 70 "implicit null check using frame pointer on win95/98"); 71 } 72 } 73 } 74 #else 75 // WIN64==itanium on XP 76 #endif 77 } 78 #endif