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1 /* Copyright (C) 2012-2018 Free Software Foundation, Inc.
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2 Contributed by Richard Henderson <rth@redhat.com>.
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3
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4 This file is part of the GNU Atomic Library (libatomic).
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5
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6 Libatomic is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 3 of the License, or
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9 (at your option) any later version.
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10
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11 Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY
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12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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13 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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14 more details.
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15
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16 Under Section 7 of GPL version 3, you are granted additional
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17 permissions described in the GCC Runtime Library Exception, version
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18 3.1, as published by the Free Software Foundation.
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19
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20 You should have received a copy of the GNU General Public License and
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21 a copy of the GCC Runtime Library Exception along with this program;
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22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 <http://www.gnu.org/licenses/>. */
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24
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25 #include <libatomic_i.h>
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26
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27
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28 /* This file is included multiple times with required defines:
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29 NAME the name of the operation that we're implementing;
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30 OP a two-operand functional macro the implements the operation.
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31 */
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32
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33
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34 /* If we support the builtin, just use it. */
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35 #if !DONE && SIZE(HAVE_ATOMIC_FETCH_OP)
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36 UTYPE
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37 SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel)
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38 {
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39 if (maybe_specialcase_relaxed(smodel))
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40 return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_RELAXED);
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41 else if (maybe_specialcase_acqrel(smodel))
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42 return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_ACQ_REL);
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43 else
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44 return C2(__atomic_fetch_,NAME) (mptr, opval, __ATOMIC_SEQ_CST);
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45 }
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46
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47 UTYPE
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48 SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel)
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49 {
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50 if (maybe_specialcase_relaxed(smodel))
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51 return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_RELAXED);
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52 else if (maybe_specialcase_acqrel(smodel))
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53 return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_ACQ_REL);
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54 else
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55 return C3(__atomic_,NAME,_fetch) (mptr, opval, __ATOMIC_SEQ_CST);
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56 }
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57
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58 #define DONE 1
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59 #endif /* HAVE_ATOMIC_FETCH_OP */
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60
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61
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62 #if !DONE && defined(atomic_compare_exchange_n)
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63 UTYPE
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64 SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel)
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65 {
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66 UTYPE oldval, t;
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67
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68 pre_barrier (smodel);
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69
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70 oldval = *mptr;
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71 do
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72 {
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73 t = OP(oldval, opval);
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74 }
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75 while (!atomic_compare_exchange_n (mptr, &oldval, t, true,
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76 __ATOMIC_RELAXED, __ATOMIC_RELAXED));
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77
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78 post_barrier (smodel);
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79 return oldval;
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80 }
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81
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82 UTYPE
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83 SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel)
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84 {
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85 UTYPE oldval, t;
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86
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87 pre_barrier (smodel);
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88
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89 oldval = *mptr;
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90 do
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91 {
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92 t = OP(oldval, opval);
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93 }
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94 while (!atomic_compare_exchange_n (mptr, &oldval, t, true,
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95 __ATOMIC_RELAXED, __ATOMIC_RELAXED));
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96
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97 post_barrier (smodel);
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98 return t;
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99 }
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100
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101 #define DONE 1
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102 #endif /* atomic_compare_exchange_n */
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103
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104
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105 /* If this type is no larger than word-sized, fall back to a word-sized
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106 compare-and-swap loop. */
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107 #if !DONE && N < WORDSIZE && defined(atomic_compare_exchange_w)
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108 UTYPE
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109 SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel)
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110 {
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111 UWORD mask, shift, woldval, wopval, t, *wptr;
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112
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113 pre_barrier (smodel);
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114
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115 wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
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116 shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK);
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117 mask = SIZE(MASK) << shift;
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118
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119 wopval = (UWORD)opval << shift;
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120 woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);
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121 do
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122 {
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123 t = (woldval & ~mask) | (OP(woldval, wopval) & mask);
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124 }
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125 while (!atomic_compare_exchange_w (wptr, &woldval, t, true,
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126 __ATOMIC_RELAXED, __ATOMIC_RELAXED));
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127
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128 post_barrier (smodel);
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129 return woldval >> shift;
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130 }
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131
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132 UTYPE
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133 SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel)
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134 {
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135 UWORD mask, shift, woldval, wopval, t, *wptr;
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136
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137 pre_barrier (smodel);
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138
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139 wptr = (UWORD *)((uintptr_t)mptr & -WORDSIZE);
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140 shift = (((uintptr_t)mptr % WORDSIZE) * CHAR_BIT) ^ SIZE(INVERT_MASK);
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141 mask = SIZE(MASK) << shift;
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142
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143 wopval = (UWORD)opval << shift;
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144 woldval = __atomic_load_n (wptr, __ATOMIC_RELAXED);
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145 do
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146 {
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147 t = (woldval & ~mask) | (OP(woldval, wopval) & mask);
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148 }
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149 while (!atomic_compare_exchange_w (wptr, &woldval, t, true,
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150 __ATOMIC_RELAXED, __ATOMIC_RELAXED));
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151
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152 post_barrier (smodel);
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153 return t >> shift;
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154 }
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155
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156 #define DONE 1
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157 #endif /* atomic_compare_exchange_w */
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158
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159
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160 /* Otherwise, fall back to some sort of protection mechanism. */
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161 #if !DONE
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162 UTYPE
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163 SIZE(C2(libat_fetch_,NAME)) (UTYPE *mptr, UTYPE opval, int smodel UNUSED)
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164 {
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165 UTYPE ret;
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166 UWORD magic;
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167
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168 pre_seq_barrier (smodel);
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169 magic = protect_start (mptr);
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170
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171 ret = *mptr;
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172 *mptr = OP(ret, opval);
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173
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174 protect_end (mptr, magic);
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175 post_seq_barrier (smodel);
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176
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177 return ret;
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178 }
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179
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180 UTYPE
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181 SIZE(C3(libat_,NAME,_fetch)) (UTYPE *mptr, UTYPE opval, int smodel UNUSED)
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182 {
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183 UTYPE ret;
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184 UWORD magic;
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185
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186 pre_seq_barrier (smodel);
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187 magic = protect_start (mptr);
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188
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189 ret = OP (*mptr, opval);
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190 *mptr = ret;
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191
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192 protect_end (mptr, magic);
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193 post_seq_barrier (smodel);
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194
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195 return ret;
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196 }
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197 #endif
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198
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199 EXPORT_ALIAS (SIZE(C2(fetch_,NAME)));
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200 EXPORT_ALIAS (SIZE(C2(NAME,_fetch)));
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