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1 /*
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2 * Copyright 1998-2007 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/_threadLS_solaris_x86.cpp.incl"
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27
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28 #ifdef AMD64
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29 extern "C" Thread* fs_load(ptrdiff_t tlsOffset);
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30 extern "C" intptr_t fs_thread();
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31 #else
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32 // From solaris_i486.s
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33 extern "C" Thread* gs_load(ptrdiff_t tlsOffset);
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34 extern "C" intptr_t gs_thread();
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35 #endif // AMD64
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36
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37 // tlsMode encoding:
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38 //
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39 // pd_tlsAccessUndefined : uninitialized
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40 // pd_tlsAccessSlow : not available
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41 // pd_tlsAccessIndirect :
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42 // old-style indirect access - present in "T1" libthread.
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43 // use thr_slot_sync_allocate() to attempt to allocate a slot.
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44 // pd_tlsAccessDirect :
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45 // new-style direct access - present in late-model "T2" libthread.
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46 // Allocate the offset (slot) via _thr_slot_offset() or by
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47 // defining an IE- or LE-mode TLS/TSD slot in the launcher and then passing
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48 // that offset into libjvm.so.
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49 // See http://sac.eng/Archives/CaseLog/arc/PSARC/2003/159/.
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50 //
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51 // Note that we have a capability gap - some early model T2 forms
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52 // (e.g., unpatched S9) have neither _thr_slot_sync_allocate() nor
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53 // _thr_slot_offset(). In that case we revert to the usual
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54 // thr_getspecific accessor.
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55 //
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56
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57 static ThreadLocalStorage::pd_tlsAccessMode tlsMode = ThreadLocalStorage::pd_tlsAccessUndefined ;
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58 static ptrdiff_t tlsOffset = 0 ;
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59 static thread_key_t tlsKey ;
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60
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61 typedef int (*TSSA_Entry) (ptrdiff_t *, int, int) ;
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62 typedef ptrdiff_t (*TSO_Entry) (int) ;
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63
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64 ThreadLocalStorage::pd_tlsAccessMode ThreadLocalStorage::pd_getTlsAccessMode ()
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65 {
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66 guarantee (tlsMode != pd_tlsAccessUndefined, "tlsMode not set") ;
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67 return tlsMode ;
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68 }
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69
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70 ptrdiff_t ThreadLocalStorage::pd_getTlsOffset () {
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71 guarantee (tlsMode != pd_tlsAccessUndefined, "tlsMode not set") ;
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72 return tlsOffset ;
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73 }
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74
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75 // TODO: Consider the following improvements:
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76 //
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77 // 1. Convert from thr_*specific* to pthread_*specific*.
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78 // The pthread_ forms are slightly faster. Also, the
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79 // pthread_ forms have a pthread_key_delete() API which
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80 // would aid in clean JVM shutdown and the eventual goal
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81 // of permitting a JVM to reinstantiate itself withing a process.
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82 //
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83 // 2. See ThreadLocalStorage::init(). We end up allocating
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84 // two TLS keys during VM startup. That's benign, but we could collapse
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85 // down to one key without too much trouble.
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86 //
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87 // 3. MacroAssembler::get_thread() currently emits calls to thr_getspecific().
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88 // Modify get_thread() to call Thread::current() instead.
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89 //
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90 // 4. Thread::current() currently uses a cache keyed by %gs:[0].
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91 // (The JVM has PSARC permission to use %g7/%gs:[0]
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92 // as an opaque temporally unique thread identifier).
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93 // For C++ access to a thread's reflexive "self" pointer we
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94 // should consider using one of the following:
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95 // a. a radix tree keyed by %esp - as in EVM.
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96 // This requires two loads (the 2nd dependent on the 1st), but
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97 // is easily inlined and doesn't require a "miss" slow path.
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98 // b. a fast TLS/TSD slot allocated by _thr_slot_offset
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99 // or _thr_slot_sync_allocate.
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100 //
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101 // 5. 'generate_code_for_get_thread' is a misnomer.
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102 // We should change it to something more general like
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103 // pd_ThreadSelf_Init(), for instance.
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104 //
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105
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106 static void AllocateTLSOffset ()
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107 {
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108 int rslt ;
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109 TSSA_Entry tssa ;
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110 TSO_Entry tso ;
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111 ptrdiff_t off ;
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112
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113 guarantee (tlsMode == ThreadLocalStorage::pd_tlsAccessUndefined, "tlsMode not set") ;
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114 tlsMode = ThreadLocalStorage::pd_tlsAccessSlow ;
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115 tlsOffset = 0 ;
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116 #ifndef AMD64
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117
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118 tssa = (TSSA_Entry) dlsym (RTLD_DEFAULT, "thr_slot_sync_allocate") ;
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119 if (tssa != NULL) {
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120 off = -1 ;
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121 rslt = (*tssa)(&off, NULL, NULL) ; // (off,dtor,darg)
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122 if (off != -1) {
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123 tlsOffset = off ;
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124 tlsMode = ThreadLocalStorage::pd_tlsAccessIndirect ;
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125 return ;
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126 }
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127 }
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128
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129 rslt = thr_keycreate (&tlsKey, NULL) ;
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130 if (rslt != 0) {
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131 tlsMode = ThreadLocalStorage::pd_tlsAccessSlow ; // revert to slow mode
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132 return ;
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133 }
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134
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135 tso = (TSO_Entry) dlsym (RTLD_DEFAULT, "_thr_slot_offset") ;
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136 if (tso != NULL) {
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137 off = (*tso)(tlsKey) ;
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138 if (off >= 0) {
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139 tlsOffset = off ;
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140 tlsMode = ThreadLocalStorage::pd_tlsAccessDirect ;
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141 return ;
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142 }
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143 }
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144
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145 // Failure: Too bad ... we've allocated a TLS slot we don't need and there's
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146 // no provision in the ABI for returning the slot.
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147 //
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148 // If we didn't find a slot then then:
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149 // 1. We might be on liblwp.
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150 // 2. We might be on T2 libthread, but all "fast" slots are already
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151 // consumed
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152 // 3. We might be on T1, and all TSD (thr_slot_sync_allocate) slots are
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153 // consumed.
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154 // 4. We might be on T2 libthread, but it's be re-architected
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155 // so that fast slots are no longer g7-relative.
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156 //
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157
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158 tlsMode = ThreadLocalStorage::pd_tlsAccessSlow ;
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159 return ;
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160 #endif // AMD64
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161 }
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162
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163 void ThreadLocalStorage::generate_code_for_get_thread() {
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164 AllocateTLSOffset() ;
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165 }
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166
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167 void ThreadLocalStorage::set_thread_in_slot(Thread *thread) {
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168 guarantee (tlsMode != pd_tlsAccessUndefined, "tlsMode not set") ;
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169 if (tlsMode == pd_tlsAccessIndirect) {
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170 #ifdef AMD64
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171 intptr_t tbase = fs_thread();
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172 #else
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173 intptr_t tbase = gs_thread();
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174 #endif // AMD64
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175 *((Thread**) (tbase + tlsOffset)) = thread ;
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176 } else
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177 if (tlsMode == pd_tlsAccessDirect) {
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178 thr_setspecific (tlsKey, (void *) thread) ;
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179 // set with thr_setspecific and then readback with gs_load to validate.
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180 #ifdef AMD64
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181 guarantee (thread == fs_load(tlsOffset), "tls readback failure") ;
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182 #else
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183 guarantee (thread == gs_load(tlsOffset), "tls readback failure") ;
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184 #endif // AMD64
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185 }
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186 }
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187
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188
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189 extern "C" Thread* get_thread() {
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190 return ThreadLocalStorage::thread();
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191 }
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