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5564 | serge | 1 | /* -*- c++ -*- */ |
2 | /* |
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3 | * Copyright © 2010 Intel Corporation |
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4 | * |
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5 | * Permission is hereby granted, free of charge, to any person obtaining a |
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6 | * copy of this software and associated documentation files (the "Software"), |
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7 | * to deal in the Software without restriction, including without limitation |
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8 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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9 | * and/or sell copies of the Software, and to permit persons to whom the |
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10 | * Software is furnished to do so, subject to the following conditions: |
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11 | * |
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12 | * The above copyright notice and this permission notice (including the next |
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13 | * paragraph) shall be included in all copies or substantial portions of the |
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14 | * Software. |
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15 | * |
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16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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19 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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20 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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21 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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22 | * DEALINGS IN THE SOFTWARE. |
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23 | */ |
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24 | |||
25 | #pragma once |
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26 | #ifndef LOOP_ANALYSIS_H |
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27 | #define LOOP_ANALYSIS_H |
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28 | |||
29 | #include "ir.h" |
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30 | #include "program/hash_table.h" |
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31 | |||
32 | /** |
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33 | * Analyze and classify all variables used in all loops in the instruction list |
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34 | */ |
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35 | extern class loop_state * |
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36 | analyze_loop_variables(exec_list *instructions); |
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37 | |||
38 | |||
39 | /** |
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40 | * Fill in loop control fields |
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41 | * |
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42 | * Based on analysis of loop variables, this function tries to remove |
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43 | * redundant sequences in the loop of the form |
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44 | * |
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45 | * (if (expression bool ...) (break)) |
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46 | * |
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47 | * For example, if it is provable that one loop exit condition will |
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48 | * always be satisfied before another, the unnecessary exit condition will be |
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49 | * removed. |
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50 | */ |
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51 | extern bool |
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52 | set_loop_controls(exec_list *instructions, loop_state *ls); |
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53 | |||
54 | |||
55 | extern bool |
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56 | unroll_loops(exec_list *instructions, loop_state *ls, |
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57 | const struct gl_shader_compiler_options *options); |
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58 | |||
59 | ir_rvalue * |
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60 | find_initial_value(ir_loop *loop, ir_variable *var); |
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61 | |||
62 | int |
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63 | calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment, |
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64 | enum ir_expression_operation op); |
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65 | |||
66 | |||
67 | /** |
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68 | * Tracking for all variables used in a loop |
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69 | */ |
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70 | class loop_variable_state : public exec_node { |
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71 | public: |
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72 | class loop_variable *get(const ir_variable *); |
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73 | class loop_variable *insert(ir_variable *); |
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74 | class loop_variable *get_or_insert(ir_variable *, bool in_assignee); |
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75 | class loop_terminator *insert(ir_if *); |
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76 | |||
77 | |||
78 | /** |
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79 | * Variables that have not yet been classified |
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80 | */ |
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81 | exec_list variables; |
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82 | |||
83 | /** |
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84 | * Variables whose values are constant within the body of the loop |
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85 | * |
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86 | * This list contains \c loop_variable objects. |
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87 | */ |
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88 | exec_list constants; |
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89 | |||
90 | /** |
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91 | * Induction variables for this loop |
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92 | * |
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93 | * This list contains \c loop_variable objects. |
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94 | */ |
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95 | exec_list induction_variables; |
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96 | |||
97 | /** |
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98 | * Simple if-statements that lead to the termination of the loop |
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99 | * |
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100 | * This list contains \c loop_terminator objects. |
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101 | * |
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102 | * \sa is_loop_terminator |
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103 | */ |
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104 | exec_list terminators; |
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105 | |||
106 | /** |
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107 | * If any of the terminators in \c terminators leads to termination of the |
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108 | * loop after a constant number of iterations, this is the terminator that |
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109 | * leads to termination after the smallest number of iterations. Otherwise |
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110 | * NULL. |
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111 | */ |
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112 | loop_terminator *limiting_terminator; |
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113 | |||
114 | /** |
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115 | * Hash table containing all variables accessed in this loop |
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116 | */ |
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117 | hash_table *var_hash; |
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118 | |||
119 | /** |
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120 | * Number of ir_loop_jump instructions that operate on this loop |
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121 | */ |
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122 | unsigned num_loop_jumps; |
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123 | |||
124 | /** |
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125 | * Whether this loop contains any function calls. |
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126 | */ |
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127 | bool contains_calls; |
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128 | |||
129 | loop_variable_state() |
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130 | { |
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131 | this->num_loop_jumps = 0; |
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132 | this->contains_calls = false; |
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133 | this->var_hash = hash_table_ctor(0, hash_table_pointer_hash, |
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134 | hash_table_pointer_compare); |
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135 | this->limiting_terminator = NULL; |
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136 | } |
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137 | |||
138 | ~loop_variable_state() |
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139 | { |
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140 | hash_table_dtor(this->var_hash); |
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141 | } |
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142 | |||
143 | DECLARE_RALLOC_CXX_OPERATORS(loop_variable_state) |
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144 | }; |
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145 | |||
146 | |||
147 | class loop_variable : public exec_node { |
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148 | public: |
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149 | /** The variable in question. */ |
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150 | ir_variable *var; |
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151 | |||
152 | /** Is the variable read in the loop before it is written? */ |
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153 | bool read_before_write; |
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154 | |||
155 | /** Are all variables in the RHS of the assignment loop constants? */ |
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156 | bool rhs_clean; |
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157 | |||
158 | /** |
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159 | * Is there an assignment to the variable that is conditional, or inside a |
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160 | * nested loop? |
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161 | */ |
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162 | bool conditional_or_nested_assignment; |
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163 | |||
164 | /** Reference to the first assignment to the variable in the loop body. */ |
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165 | ir_assignment *first_assignment; |
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166 | |||
167 | /** Number of assignments to the variable in the loop body. */ |
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168 | unsigned num_assignments; |
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169 | |||
170 | /** |
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171 | * Increment value for a loop induction variable |
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172 | * |
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173 | * If this is a loop induction variable, the amount by which the variable |
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174 | * is incremented on each iteration through the loop. |
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175 | * |
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176 | * If this is not a loop induction variable, NULL. |
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177 | */ |
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178 | ir_rvalue *increment; |
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179 | |||
180 | |||
181 | inline bool is_induction_var() const |
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182 | { |
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183 | /* Induction variables always have a non-null increment, and vice |
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184 | * versa. |
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185 | */ |
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186 | return this->increment != NULL; |
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187 | } |
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188 | |||
189 | |||
190 | inline bool is_loop_constant() const |
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191 | { |
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192 | const bool is_const = (this->num_assignments == 0) |
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193 | || (((this->num_assignments == 1) |
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194 | && !this->conditional_or_nested_assignment |
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195 | && !this->read_before_write |
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196 | && this->rhs_clean) || this->var->data.read_only); |
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197 | |||
198 | /* If the RHS of *the* assignment is clean, then there must be exactly |
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199 | * one assignment of the variable. |
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200 | */ |
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201 | assert((this->rhs_clean && (this->num_assignments == 1)) |
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202 | || !this->rhs_clean); |
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203 | |||
204 | return is_const; |
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205 | } |
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206 | |||
207 | void record_reference(bool in_assignee, |
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208 | bool in_conditional_code_or_nested_loop, |
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209 | ir_assignment *current_assignment); |
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210 | }; |
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211 | |||
212 | |||
213 | class loop_terminator : public exec_node { |
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214 | public: |
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215 | loop_terminator() |
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216 | : ir(NULL), iterations(-1) |
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217 | { |
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218 | } |
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219 | |||
220 | /** |
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221 | * Statement which terminates the loop. |
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222 | */ |
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223 | ir_if *ir; |
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224 | |||
225 | /** |
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226 | * The number of iterations after which the terminator is known to |
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227 | * terminate the loop (if that is a fixed value). Otherwise -1. |
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228 | */ |
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229 | int iterations; |
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230 | }; |
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231 | |||
232 | |||
233 | class loop_state { |
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234 | public: |
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235 | ~loop_state(); |
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236 | |||
237 | /** |
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238 | * Get the loop variable state data for a particular loop |
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239 | */ |
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240 | loop_variable_state *get(const ir_loop *); |
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241 | |||
242 | loop_variable_state *insert(ir_loop *ir); |
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243 | |||
244 | bool loop_found; |
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245 | |||
246 | private: |
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247 | loop_state(); |
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248 | |||
249 | /** |
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250 | * Hash table containing all loops that have been analyzed. |
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251 | */ |
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252 | hash_table *ht; |
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253 | |||
254 | void *mem_ctx; |
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255 | |||
256 | friend loop_state *analyze_loop_variables(exec_list *instructions); |
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257 | }; |
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258 | |||
259 | #endif /* LOOP_ANALYSIS_H */ |