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1 /*
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2 * Copyright 1999-2003 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 #include "incls/_precompiled.incl"
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26 #include "incls/_assembler_windows_x86_32.cpp.incl"
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27
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28
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29 void MacroAssembler::int3() {
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30 emit_byte(0xCC);
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31 }
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32
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33 // The current scheme to accelerate access to the thread
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34 // pointer is to store the current thread in the os_exception_wrapper
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35 // and reference the current thread from stubs and compiled code
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36 // via the FS register. FS[0] contains a pointer to the structured
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37 // exception block which is actually a stack address. The first time
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38 // we call the os exception wrapper, we calculate and store the
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39 // offset from this exception block and use that offset here.
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40 //
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41 // The last mechanism we used was problematic in that the
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42 // the offset we had hard coded in the VM kept changing as Microsoft
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43 // evolved the OS.
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44 //
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45 // Warning: This mechanism assumes that we only attempt to get the
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46 // thread when we are nested below a call wrapper.
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47 //
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48 // movl reg, fs:[0] Get exeception pointer
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49 // movl reg, [reg + thread_ptr_offset] Load thread
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50 //
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51 void MacroAssembler::get_thread(Register thread) {
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52 // can't use ExternalAddress because it can't take NULL
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53 AddressLiteral null(0, relocInfo::none);
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54
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55 prefix(FS_segment);
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56 movptr(thread, null);
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57 assert(ThreadLocalStorage::get_thread_ptr_offset() != 0,
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58 "Thread Pointer Offset has not been initialized");
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59 movl(thread, Address(thread, ThreadLocalStorage::get_thread_ptr_offset()));
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60 }
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61
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62 bool MacroAssembler::needs_explicit_null_check(int offset) {
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63 return offset < 0 || (int)os::vm_page_size() <= offset;
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64 }
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