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1 /* List implementation of a partition of consecutive integers.
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2 Copyright (C) 2000-2020 Free Software Foundation, Inc.
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3 Contributed by CodeSourcery, LLC.
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4
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5 This file is part of GNU CC.
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6
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7 GNU CC is free software; you can redistribute it and/or modify
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8 it under the terms of the GNU General Public License as published by
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9 the Free Software Foundation; either version 2, or (at your option)
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10 any later version.
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11
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12 GNU CC is distributed in the hope that it will be useful,
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13 but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 GNU General Public License for more details.
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16
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17 You should have received a copy of the GNU General Public License
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18 along with GNU CC; see the file COPYING. If not, write to
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19 the Free Software Foundation, 51 Franklin Street - Fifth Floor,
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20 Boston, MA 02110-1301, USA. */
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21
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22 #ifdef HAVE_CONFIG_H
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23 #include "config.h"
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24 #endif
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25
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26 #ifdef HAVE_STDLIB_H
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27 #include <stdlib.h>
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28 #endif
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29
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30 #ifdef HAVE_STRING_H
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31 #include <string.h>
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32 #endif
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33
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34 #include "libiberty.h"
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35 #include "partition.h"
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36
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37 static int elem_compare (const void *, const void *);
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38
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39 /* Creates a partition of NUM_ELEMENTS elements. Initially each
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40 element is in a class by itself. */
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41
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42 partition
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43 partition_new (int num_elements)
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44 {
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45 int e;
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46
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47 partition part = (partition)
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48 xmalloc (sizeof (struct partition_def) +
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49 (num_elements - 1) * sizeof (struct partition_elem));
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50 part->num_elements = num_elements;
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51 for (e = 0; e < num_elements; ++e)
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52 {
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53 part->elements[e].class_element = e;
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54 part->elements[e].next = &(part->elements[e]);
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55 part->elements[e].class_count = 1;
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56 }
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57
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58 return part;
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59 }
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60
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61 /* Freeds a partition. */
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62
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63 void
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64 partition_delete (partition part)
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65 {
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66 free (part);
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67 }
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68
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69 /* Unites the classes containing ELEM1 and ELEM2 into a single class
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70 of partition PART. If ELEM1 and ELEM2 are already in the same
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71 class, does nothing. Returns the canonical element of the
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72 resulting union class. */
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73
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74 int
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75 partition_union (partition part, int elem1, int elem2)
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76 {
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77 struct partition_elem *elements = part->elements;
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78 struct partition_elem *e1;
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79 struct partition_elem *e2;
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80 struct partition_elem *p;
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81 struct partition_elem *old_next;
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82 /* The canonical element of the resulting union class. */
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83 int class_element = elements[elem1].class_element;
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84
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85 /* If they're already in the same class, do nothing. */
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86 if (class_element == elements[elem2].class_element)
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87 return class_element;
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88
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89 /* Make sure ELEM1 is in the larger class of the two. If not, swap
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90 them. This way we always scan the shorter list. */
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91 if (elements[elem1].class_count < elements[elem2].class_count)
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92 {
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93 int temp = elem1;
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94 elem1 = elem2;
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95 elem2 = temp;
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96 class_element = elements[elem1].class_element;
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97 }
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98
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99 e1 = &(elements[elem1]);
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100 e2 = &(elements[elem2]);
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101
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102 /* Keep a count of the number of elements in the list. */
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103 elements[class_element].class_count
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104 += elements[e2->class_element].class_count;
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105
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106 /* Update the class fields in elem2's class list. */
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107 e2->class_element = class_element;
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108 for (p = e2->next; p != e2; p = p->next)
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109 p->class_element = class_element;
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110
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111 /* Splice ELEM2's class list into ELEM1's. These are circular
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112 lists. */
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113 old_next = e1->next;
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114 e1->next = e2->next;
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115 e2->next = old_next;
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116
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117 return class_element;
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118 }
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119
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120 /* Compare elements ELEM1 and ELEM2 from array of integers, given a
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121 pointer to each. Used to qsort such an array. */
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122
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123 static int
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124 elem_compare (const void *elem1, const void *elem2)
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125 {
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126 int e1 = * (const int *) elem1;
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127 int e2 = * (const int *) elem2;
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128 if (e1 < e2)
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129 return -1;
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130 else if (e1 > e2)
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131 return 1;
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132 else
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133 return 0;
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134 }
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135
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136 /* Prints PART to the file pointer FP. The elements of each
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137 class are sorted. */
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138
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139 void
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140 partition_print (partition part, FILE *fp)
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141 {
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142 char *done;
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143 int num_elements = part->num_elements;
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144 struct partition_elem *elements = part->elements;
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145 int *class_elements;
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146 int e;
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147
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148 /* Flag the elements we've already printed. */
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149 done = (char *) xmalloc (num_elements);
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150 memset (done, 0, num_elements);
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151
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152 /* A buffer used to sort elements in a class. */
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153 class_elements = (int *) xmalloc (num_elements * sizeof (int));
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154
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155 fputc ('[', fp);
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156 for (e = 0; e < num_elements; ++e)
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157 /* If we haven't printed this element, print its entire class. */
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158 if (! done[e])
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159 {
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160 int c = e;
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161 int count = elements[elements[e].class_element].class_count;
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162 int i;
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163
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164 /* Collect the elements in this class. */
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165 for (i = 0; i < count; ++i) {
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166 class_elements[i] = c;
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167 done[c] = 1;
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168 c = elements[c].next - elements;
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169 }
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170 /* Sort them. */
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171 qsort ((void *) class_elements, count, sizeof (int), elem_compare);
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172 /* Print them. */
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173 fputc ('(', fp);
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174 for (i = 0; i < count; ++i)
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175 fprintf (fp, i == 0 ? "%d" : " %d", class_elements[i]);
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176 fputc (')', fp);
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177 }
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178 fputc (']', fp);
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179
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180 free (class_elements);
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181 free (done);
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182 }
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183
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