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1 .. Copyright (C) 2014-2020 Free Software Foundation, Inc.
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2 Originally contributed by David Malcolm <dmalcolm@redhat.com>
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3
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4 This is free software: you can redistribute it and/or modify it
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5 under the terms of the GNU General Public License as published by
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6 the Free Software Foundation, either version 3 of the License, or
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7 (at your option) any later version.
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8
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9 This program is distributed in the hope that it will be useful, but
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10 WITHOUT ANY WARRANTY; without even the implied warranty of
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11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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12 General Public License for more details.
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13
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14 You should have received a copy of the GNU General Public License
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15 along with this program. If not, see
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16 <http://www.gnu.org/licenses/>.
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17
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18 .. default-domain:: cpp
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19
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20 Expressions
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21 ===========
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22
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23 Rvalues
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24 -------
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25 .. class:: gccjit::rvalue
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26
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27 A :class:`gccjit::rvalue` is an expression that can be computed. It is a
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28 subclass of :class:`gccjit::object`, and is a thin wrapper around
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29 :c:type:`gcc_jit_rvalue *` from the C API.
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30
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31 It can be simple, e.g.:
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32
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33 * an integer value e.g. `0` or `42`
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34 * a string literal e.g. `"Hello world"`
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35 * a variable e.g. `i`. These are also lvalues (see below).
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36
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37 or compound e.g.:
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38
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39 * a unary expression e.g. `!cond`
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40 * a binary expression e.g. `(a + b)`
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41 * a function call e.g. `get_distance (&player_ship, &target)`
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42 * etc.
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43
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44 Every rvalue has an associated type, and the API will check to ensure
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45 that types match up correctly (otherwise the context will emit an error).
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46
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47 .. function:: gccjit::type gccjit::rvalue::get_type ()
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48
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49 Get the type of this rvalue.
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50
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51
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52 Simple expressions
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53 ******************
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54
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55 .. function:: gccjit::rvalue \
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56 gccjit::context::new_rvalue (gccjit::type numeric_type, \
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57 int value) const
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58
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59 Given a numeric type (integer or floating point), build an rvalue for
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60 the given constant :c:type:`int` value.
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61
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62 .. function:: gccjit::rvalue \
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63 gccjit::context::new_rvalue (gccjit::type numeric_type, \
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64 long value) const
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65
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66 Given a numeric type (integer or floating point), build an rvalue for
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67 the given constant :c:type:`long` value.
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68
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69 .. function:: gccjit::rvalue \
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70 gccjit::context::zero (gccjit::type numeric_type) const
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71
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72 Given a numeric type (integer or floating point), get the rvalue for
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73 zero. Essentially this is just a shortcut for:
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74
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75 .. code-block:: c++
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76
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77 ctxt.new_rvalue (numeric_type, 0)
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78
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79 .. function:: gccjit::rvalue \
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80 gccjit::context::one (gccjit::type numeric_type) const
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81
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82 Given a numeric type (integer or floating point), get the rvalue for
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83 one. Essentially this is just a shortcut for:
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84
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85 .. code-block:: c++
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86
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87 ctxt.new_rvalue (numeric_type, 1)
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88
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89 .. function:: gccjit::rvalue \
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90 gccjit::context::new_rvalue (gccjit::type numeric_type, \
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91 double value) const
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92
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93 Given a numeric type (integer or floating point), build an rvalue for
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94 the given constant :c:type:`double` value.
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95
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96 .. function:: gccjit::rvalue \
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97 gccjit::context::new_rvalue (gccjit::type pointer_type, \
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98 void *value) const
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99
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100 Given a pointer type, build an rvalue for the given address.
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101
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102 .. function:: gccjit::rvalue \
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103 gccjit::context::new_rvalue (const std::string &value) const
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104
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105 Generate an rvalue of type :c:data:`GCC_JIT_TYPE_CONST_CHAR_PTR` for
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106 the given string. This is akin to a string literal.
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107
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108 Vector expressions
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109 ******************
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110
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111 .. function:: gccjit::rvalue \
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112 gccjit::context::new_rvalue (gccjit::type vector_type, \
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113 std::vector<gccjit::rvalue> elements) const
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114
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115 Given a vector type, and a vector of scalar rvalue elements, generate a
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116 vector rvalue.
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117
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118 The number of elements needs to match that of the vector type.
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119
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120 Unary Operations
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121 ****************
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122
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123 .. function:: gccjit::rvalue \
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124 gccjit::context::new_unary_op (enum gcc_jit_unary_op, \
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125 gccjit::type result_type, \
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126 gccjit::rvalue rvalue, \
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127 gccjit::location loc)
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128
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129 Build a unary operation out of an input rvalue.
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130
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131 Parameter ``loc`` is optional.
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132
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133 This is a thin wrapper around the C API's
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134 :c:func:`gcc_jit_context_new_unary_op` and the available unary
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135 operations are documented there.
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136
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137 There are shorter ways to spell the various specific kinds of unary
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138 operation:
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139
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140 .. function:: gccjit::rvalue \
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141 gccjit::context::new_minus (gccjit::type result_type, \
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142 gccjit::rvalue a, \
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143 gccjit::location loc)
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144
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145 Negate an arithmetic value; for example:
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146
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147 .. code-block:: c++
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148
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149 gccjit::rvalue negpi = ctxt.new_minus (t_double, pi);
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150
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151 builds the equivalent of this C expression:
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152
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153 .. code-block:: c
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154
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155 -pi
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156
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157 .. function:: gccjit::rvalue \
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158 new_bitwise_negate (gccjit::type result_type, \
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159 gccjit::rvalue a, \
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160 gccjit::location loc)
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161
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162 Bitwise negation of an integer value (one's complement); for example:
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163
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164 .. code-block:: c++
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165
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166 gccjit::rvalue mask = ctxt.new_bitwise_negate (t_int, a);
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167
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168 builds the equivalent of this C expression:
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169
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170 .. code-block:: c
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171
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172 ~a
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173
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174 .. function:: gccjit::rvalue \
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175 new_logical_negate (gccjit::type result_type, \
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176 gccjit::rvalue a, \
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177 gccjit::location loc)
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178
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179 Logical negation of an arithmetic or pointer value; for example:
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180
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181 .. code-block:: c++
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182
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183 gccjit::rvalue guard = ctxt.new_logical_negate (t_bool, cond);
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184
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185 builds the equivalent of this C expression:
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186
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187 .. code-block:: c
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188
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189 !cond
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190
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191
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192 The most concise way to spell them is with overloaded operators:
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193
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194 .. function:: gccjit::rvalue operator- (gccjit::rvalue a)
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195
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196 .. code-block:: c++
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197
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198 gccjit::rvalue negpi = -pi;
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199
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200
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201 .. function:: gccjit::rvalue operator~ (gccjit::rvalue a)
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202
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203 .. code-block:: c++
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204
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205 gccjit::rvalue mask = ~a;
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206
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207 .. function:: gccjit::rvalue operator! (gccjit::rvalue a)
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208
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209 .. code-block:: c++
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210
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211 gccjit::rvalue guard = !cond;
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212
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213
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214 Binary Operations
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215 *****************
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216
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217 .. function:: gccjit::rvalue\
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218 gccjit::context::new_binary_op (enum gcc_jit_binary_op, \
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219 gccjit::type result_type, \
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220 gccjit::rvalue a, \
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221 gccjit::rvalue b, \
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222 gccjit::location loc)
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223
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224 Build a binary operation out of two constituent rvalues.
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225
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226 Parameter ``loc`` is optional.
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227
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228 This is a thin wrapper around the C API's
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229 :c:func:`gcc_jit_context_new_binary_op` and the available binary
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230 operations are documented there.
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231
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232 There are shorter ways to spell the various specific kinds of binary
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233 operation:
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234
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235 .. function:: gccjit::rvalue \
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236 gccjit::context::new_plus (gccjit::type result_type, \
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237 gccjit::rvalue a, gccjit::rvalue b, \
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238 gccjit::location loc)
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239
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240 .. function:: gccjit::rvalue \
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241 gccjit::context::new_minus (gccjit::type result_type, \
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242 gccjit::rvalue a, gccjit::rvalue b, \
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243 gccjit::location loc)
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244
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245 .. function:: gccjit::rvalue \
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246 gccjit::context::new_mult (gccjit::type result_type, \
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247 gccjit::rvalue a, gccjit::rvalue b, \
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248 gccjit::location loc)
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249
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250 .. function:: gccjit::rvalue \
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251 gccjit::context::new_divide (gccjit::type result_type, \
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252 gccjit::rvalue a, gccjit::rvalue b, \
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253 gccjit::location loc)
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254
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255 .. function:: gccjit::rvalue \
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256 gccjit::context::new_modulo (gccjit::type result_type, \
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257 gccjit::rvalue a, gccjit::rvalue b, \
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258 gccjit::location loc)
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259
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260 .. function:: gccjit::rvalue \
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261 gccjit::context::new_bitwise_and (gccjit::type result_type, \
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262 gccjit::rvalue a, gccjit::rvalue b, \
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263 gccjit::location loc)
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264
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265 .. function:: gccjit::rvalue \
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266 gccjit::context::new_bitwise_xor (gccjit::type result_type, \
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267 gccjit::rvalue a, gccjit::rvalue b, \
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268 gccjit::location loc)
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269
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270 .. function:: gccjit::rvalue \
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271 gccjit::context::new_bitwise_or (gccjit::type result_type, \
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272 gccjit::rvalue a, gccjit::rvalue b, \
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273 gccjit::location loc)
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274
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275 .. function:: gccjit::rvalue \
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276 gccjit::context::new_logical_and (gccjit::type result_type, \
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277 gccjit::rvalue a, gccjit::rvalue b, \
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278 gccjit::location loc)
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279
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280 .. function:: gccjit::rvalue \
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281 gccjit::context::new_logical_or (gccjit::type result_type, \
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282 gccjit::rvalue a, gccjit::rvalue b, \
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283 gccjit::location loc)
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284
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285 The most concise way to spell them is with overloaded operators:
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286
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287 .. function:: gccjit::rvalue operator+ (gccjit::rvalue a, gccjit::rvalue b)
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288
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289 .. code-block:: c++
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290
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291 gccjit::rvalue sum = a + b;
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292
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293 .. function:: gccjit::rvalue operator- (gccjit::rvalue a, gccjit::rvalue b)
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294
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295 .. code-block:: c++
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296
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297 gccjit::rvalue diff = a - b;
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298
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299 .. function:: gccjit::rvalue operator* (gccjit::rvalue a, gccjit::rvalue b)
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300
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301 .. code-block:: c++
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302
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303 gccjit::rvalue prod = a * b;
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304
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305 .. function:: gccjit::rvalue operator/ (gccjit::rvalue a, gccjit::rvalue b)
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306
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307 .. code-block:: c++
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308
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309 gccjit::rvalue result = a / b;
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310
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311 .. function:: gccjit::rvalue operator% (gccjit::rvalue a, gccjit::rvalue b)
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312
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313 .. code-block:: c++
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314
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315 gccjit::rvalue mod = a % b;
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316
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317 .. function:: gccjit::rvalue operator& (gccjit::rvalue a, gccjit::rvalue b)
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318
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319 .. code-block:: c++
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320
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321 gccjit::rvalue x = a & b;
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322
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323 .. function:: gccjit::rvalue operator^ (gccjit::rvalue a, gccjit::rvalue b)
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324
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325 .. code-block:: c++
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326
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327 gccjit::rvalue x = a ^ b;
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328
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329 .. function:: gccjit::rvalue operator| (gccjit::rvalue a, gccjit::rvalue b)
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330
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331 .. code-block:: c++
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332
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333 gccjit::rvalue x = a | b;
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334
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335 .. function:: gccjit::rvalue operator&& (gccjit::rvalue a, gccjit::rvalue b)
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336
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337 .. code-block:: c++
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338
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339 gccjit::rvalue cond = a && b;
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340
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341 .. function:: gccjit::rvalue operator|| (gccjit::rvalue a, gccjit::rvalue b)
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342
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343 .. code-block:: c++
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344
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345 gccjit::rvalue cond = a || b;
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346
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347 These can of course be combined, giving a terse way to build compound
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348 expressions:
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349
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350 .. code-block:: c++
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351
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352 gccjit::rvalue discriminant = (b * b) - (four * a * c);
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353
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354
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355 Comparisons
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356 ***********
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357
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358 .. function:: gccjit::rvalue \
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359 gccjit::context::new_comparison (enum gcc_jit_comparison,\
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360 gccjit::rvalue a, \
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361 gccjit::rvalue b, \
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362 gccjit::location loc)
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363
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364 Build a boolean rvalue out of the comparison of two other rvalues.
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365
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366 Parameter ``loc`` is optional.
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367
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368 This is a thin wrapper around the C API's
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369 :c:func:`gcc_jit_context_new_comparison` and the available kinds
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370 of comparison are documented there.
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371
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372 There are shorter ways to spell the various specific kinds of binary
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373 operation:
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374
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375 .. function:: gccjit::rvalue \
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376 gccjit::context::new_eq (gccjit::rvalue a, gccjit::rvalue b, \
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377 gccjit::location loc)
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378
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379 .. function:: gccjit::rvalue \
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380 gccjit::context::new_ne (gccjit::rvalue a, gccjit::rvalue b, \
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381 gccjit::location loc)
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382
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383 .. function:: gccjit::rvalue \
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384 gccjit::context::new_lt (gccjit::rvalue a, gccjit::rvalue b, \
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385 gccjit::location loc)
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386
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387 .. function:: gccjit::rvalue \
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388 gccjit::context::new_le (gccjit::rvalue a, gccjit::rvalue b, \
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389 gccjit::location loc)
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390
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391 .. function:: gccjit::rvalue \
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392 gccjit::context::new_gt (gccjit::rvalue a, gccjit::rvalue b, \
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393 gccjit::location loc)
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394
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395 .. function:: gccjit::rvalue \
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396 gccjit::context::new_ge (gccjit::rvalue a, gccjit::rvalue b, \
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397 gccjit::location loc)
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398
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399 The most concise way to spell them is with overloaded operators:
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400
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401 .. function:: gccjit::rvalue \
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402 operator== (gccjit::rvalue a, gccjit::rvalue b)
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403
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404 .. code-block:: c++
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405
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406 gccjit::rvalue cond = (a == ctxt.zero (t_int));
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407
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408 .. function:: gccjit::rvalue \
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409 operator!= (gccjit::rvalue a, gccjit::rvalue b)
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410
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411 .. code-block:: c++
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412
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413 gccjit::rvalue cond = (i != j);
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414
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415 .. function:: gccjit::rvalue \
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416 operator< (gccjit::rvalue a, gccjit::rvalue b)
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417
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418 .. code-block:: c++
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419
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420 gccjit::rvalue cond = i < n;
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421
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422 .. function:: gccjit::rvalue \
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423 operator<= (gccjit::rvalue a, gccjit::rvalue b)
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424
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425 .. code-block:: c++
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426
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427 gccjit::rvalue cond = i <= n;
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428
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429 .. function:: gccjit::rvalue \
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430 operator> (gccjit::rvalue a, gccjit::rvalue b)
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431
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432 .. code-block:: c++
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433
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434 gccjit::rvalue cond = (ch > limit);
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435
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436 .. function:: gccjit::rvalue \
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437 operator>= (gccjit::rvalue a, gccjit::rvalue b)
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438
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439 .. code-block:: c++
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440
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441 gccjit::rvalue cond = (score >= ctxt.new_rvalue (t_int, 100));
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442
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443 .. TODO: beyond this point
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444
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445 Function calls
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446 **************
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447 .. function:: gcc_jit_rvalue *\
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448 gcc_jit_context_new_call (gcc_jit_context *ctxt,\
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449 gcc_jit_location *loc,\
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450 gcc_jit_function *func,\
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451 int numargs , gcc_jit_rvalue **args)
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452
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453 Given a function and the given table of argument rvalues, construct a
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454 call to the function, with the result as an rvalue.
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455
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456 .. note::
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457
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458 :func:`gccjit::context::new_call` merely builds a
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459 :class:`gccjit::rvalue` i.e. an expression that can be evaluated,
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460 perhaps as part of a more complicated expression.
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461 The call *won't* happen unless you add a statement to a function
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462 that evaluates the expression.
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463
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464 For example, if you want to call a function and discard the result
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465 (or to call a function with ``void`` return type), use
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466 :func:`gccjit::block::add_eval`:
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467
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468 .. code-block:: c++
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469
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470 /* Add "(void)printf (arg0, arg1);". */
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471 block.add_eval (ctxt.new_call (printf_func, arg0, arg1));
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472
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473 Function pointers
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474 *****************
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475
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476 .. function:: gccjit::rvalue \
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477 gccjit::function::get_address (gccjit::location loc)
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478
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479 Get the address of a function as an rvalue, of function pointer
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480 type.
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481
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482 Type-coercion
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483 *************
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484
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485 .. function:: gccjit::rvalue \
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486 gccjit::context::new_cast (gccjit::rvalue rvalue,\
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487 gccjit::type type, \
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488 gccjit::location loc)
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489
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490 Given an rvalue of T, construct another rvalue of another type.
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491
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492 Currently only a limited set of conversions are possible:
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493
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494 * int <-> float
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495 * int <-> bool
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496 * P* <-> Q*, for pointer types P and Q
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497
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498 Lvalues
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499 -------
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500
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501 .. class:: gccjit::lvalue
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502
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503 An lvalue is something that can of the *left*-hand side of an assignment:
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504 a storage area (such as a variable). It is a subclass of
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505 :class:`gccjit::rvalue`, where the rvalue is computed by reading from the
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506 storage area.
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507
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508 It iss a thin wrapper around :c:type:`gcc_jit_lvalue *` from the C API.
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509
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510 .. function:: gccjit::rvalue \
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511 gccjit::lvalue::get_address (gccjit::location loc)
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512
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513 Take the address of an lvalue; analogous to:
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514
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515 .. code-block:: c
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516
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517 &(EXPR)
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518
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519 in C.
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520
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521 Parameter "loc" is optional.
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522
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523 Global variables
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524 ****************
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525
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526 .. function:: gccjit::lvalue \
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527 gccjit::context::new_global (enum gcc_jit_global_kind,\
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528 gccjit::type type, \
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529 const char *name, \
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530 gccjit::location loc)
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531
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532 Add a new global variable of the given type and name to the context.
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533
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534 This is a thin wrapper around :c:func:`gcc_jit_context_new_global` from
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535 the C API; the "kind" parameter has the same meaning as there.
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536
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537 Working with pointers, structs and unions
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538 -----------------------------------------
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539
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540 .. function:: gccjit::lvalue \
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541 gccjit::rvalue::dereference (gccjit::location loc)
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542
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543 Given an rvalue of pointer type ``T *``, dereferencing the pointer,
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544 getting an lvalue of type ``T``. Analogous to:
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545
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546 .. code-block:: c++
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547
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548 *(EXPR)
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549
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550 in C.
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551
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552 Parameter "loc" is optional.
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553
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554 If you don't need to specify the location, this can also be expressed using
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555 an overloaded operator:
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556
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557 .. function:: gccjit::lvalue \
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558 gccjit::rvalue::operator* ()
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559
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560 .. code-block:: c++
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561
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562 gccjit::lvalue content = *ptr;
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563
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564 Field access is provided separately for both lvalues and rvalues:
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565
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566 .. function:: gccjit::lvalue \
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567 gccjit::lvalue::access_field (gccjit::field field, \
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568 gccjit::location loc)
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569
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570 Given an lvalue of struct or union type, access the given field,
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571 getting an lvalue of the field's type. Analogous to:
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572
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573 .. code-block:: c++
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574
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575 (EXPR).field = ...;
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576
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577 in C.
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578
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579 .. function:: gccjit::rvalue \
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580 gccjit::rvalue::access_field (gccjit::field field, \
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581 gccjit::location loc)
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582
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583 Given an rvalue of struct or union type, access the given field
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584 as an rvalue. Analogous to:
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585
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586 .. code-block:: c++
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587
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588 (EXPR).field
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589
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590 in C.
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591
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592 .. function:: gccjit::lvalue \
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593 gccjit::rvalue::dereference_field (gccjit::field field, \
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594 gccjit::location loc)
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595
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596 Given an rvalue of pointer type ``T *`` where T is of struct or union
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597 type, access the given field as an lvalue. Analogous to:
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598
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599 .. code-block:: c++
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600
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601 (EXPR)->field
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602
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603 in C, itself equivalent to ``(*EXPR).FIELD``.
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604
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|
605 .. function:: gccjit::lvalue \
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606 gccjit::context::new_array_access (gccjit::rvalue ptr, \
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607 gccjit::rvalue index, \
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608 gccjit::location loc)
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609
|
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610 Given an rvalue of pointer type ``T *``, get at the element `T` at
|
|
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611 the given index, using standard C array indexing rules i.e. each
|
|
|
612 increment of ``index`` corresponds to ``sizeof(T)`` bytes.
|
|
|
613 Analogous to:
|
|
|
614
|
|
|
615 .. code-block:: c++
|
|
|
616
|
|
|
617 PTR[INDEX]
|
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|
618
|
|
|
619 in C (or, indeed, to ``PTR + INDEX``).
|
|
|
620
|
|
|
621 Parameter "loc" is optional.
|
|
|
622
|
|
|
623 For array accesses where you don't need to specify a :class:`gccjit::location`,
|
|
|
624 two overloaded operators are available:
|
|
|
625
|
|
|
626 gccjit::lvalue gccjit::rvalue::operator[] (gccjit::rvalue index)
|
|
|
627
|
|
|
628 .. code-block:: c++
|
|
|
629
|
|
|
630 gccjit::lvalue element = array[idx];
|
|
|
631
|
|
|
632 gccjit::lvalue gccjit::rvalue::operator[] (int index)
|
|
|
633
|
|
|
634 .. code-block:: c++
|
|
|
635
|
|
|
636 gccjit::lvalue element = array[0];
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