src/relation.c

   1 /* Binary relations.
   2
   3    Copyright (C) 2002, 2004, 2005, 2009, 2010 Free Software
   4    Foundation, Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    This program is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include <config.h>
  22 #include "system.h"
  23
  24 #include <bitsetv.h>
  25
  26 #include "getargs.h"
  27 #include "relation.h"
  28
  29 void
  30 relation_print (relation r, relation_node size, FILE *out)
  31 {
  32   relation_node i;
  33   relation_node j;
  34
  35   for (i = 0; i < size; ++i)
  36     {
  37       fprintf (out, "%3lu: ", (unsigned long int) i);
  38       if (r[i])
  39         for (j = 0; r[i][j] != END_NODE; ++j)
  40           fprintf (out, "%3lu ", (unsigned long int) r[i][j]);
  41       fputc ('\n', out);
  42     }
  43   fputc ('\n', out);
  44 }
  45
  46
  47 /*---------------------------------------------------------------.
  48 | digraph & traverse.                                            |
  49 |                                                                |
  50 | The following variables are used as common storage between the |
  51 | two.                                                           |
  52 `---------------------------------------------------------------*/
  53
  54 static relation R;
  55 static relation_nodes INDEX;
  56 static relation_nodes VERTICES;
  57 static relation_node top;
  58 static relation_node infinity;
  59 static bitsetv F;
  60
  61 static void
  62 traverse (relation_node i)
  63 {
  64   relation_node j;
  65   relation_node height;
  66
  67   VERTICES[++top] = i;
  68   INDEX[i] = height = top;
  69
  70   if (R[i])
  71     for (j = 0; R[i][j] != END_NODE; ++j)
  72       {
  73         if (INDEX[R[i][j]] == 0)
  74           traverse (R[i][j]);
  75
  76         if (INDEX[i] > INDEX[R[i][j]])
  77           INDEX[i] = INDEX[R[i][j]];
  78
  79         bitset_or (F[i], F[i], F[R[i][j]]);
  80       }
  81
  82   if (INDEX[i] == height)
  83     for (;;)
  84       {
  85         j = VERTICES[top--];
  86         INDEX[j] = infinity;
  87
  88         if (i == j)
  89           break;
  90
  91         bitset_copy (F[j], F[i]);
  92       }
  93 }
  94
  95
  96 void
  97 relation_digraph (relation r, relation_node size, bitsetv *function)
  98 {
  99   relation_node i;
 100
 101   infinity = size + 2;
 102   INDEX = xcalloc (size + 1, sizeof *INDEX);
 103   VERTICES = xnmalloc (size + 1, sizeof *VERTICES);
 104   top = 0;
 105
 106   R = r;
 107   F = *function;
 108
 109   for (i = 0; i < size; i++)
 110     if (INDEX[i] == 0 && R[i])
 111       traverse (i);
 112
 113   free (INDEX);
 114   free (VERTICES);
 115
 116   *function = F;
 117 }
 118
 119
 120 /*-------------------------------------------.
 121 | Destructively transpose R_ARG, of size N.  |
 122 `-------------------------------------------*/
 123
 124 void
 125 relation_transpose (relation *R_arg, relation_node n)
 126 {
 127   relation r = *R_arg;
 128   /* The result. */
 129   relation new_R = xnmalloc (n, sizeof *new_R);
 130   /* END_R[I] -- next entry of NEW_R[I]. */
 131   relation end_R = xnmalloc (n, sizeof *end_R);
 132   /* NEDGES[I] -- total size of NEW_R[I]. */
 133   size_t *nedges = xcalloc (n, sizeof *nedges);
 134   relation_node i;
 135   relation_node j;
 136
 137   if (trace_flag & trace_sets)
 138     {
 139       fputs ("relation_transpose: input\n", stderr);
 140       relation_print (r, n, stderr);
 141     }
 142
 143   /* Count. */
 144   for (i = 0; i < n; i++)
 145     if (r[i])
 146       for (j = 0; r[i][j] != END_NODE; ++j)
 147         ++nedges[r[i][j]];
 148
 149   /* Allocate. */
 150   for (i = 0; i < n; i++)
 151     {
 152       relation_node *sp = NULL;
 153       if (nedges[i] > 0)
 154         {
 155           sp = xnmalloc (nedges[i] + 1, sizeof *sp);
 156           sp[nedges[i]] = END_NODE;
 157         }
 158       new_R[i] = sp;
 159       end_R[i] = sp;
 160     }
 161
 162   /* Store. */
 163   for (i = 0; i < n; i++)
 164     if (r[i])
 165       for (j = 0; r[i][j] != END_NODE; ++j)
 166         *end_R[r[i][j]]++ = i;
 167
 168   free (nedges);
 169   free (end_R);
 170
 171   /* Free the input: it is replaced with the result. */
 172   for (i = 0; i < n; i++)
 173     free (r[i]);
 174   free (r);
 175
 176   if (trace_flag & trace_sets)
 177     {
 178       fputs ("relation_transpose: output\n", stderr);
 179       relation_print (new_R, n, stderr);
 180     }
 181
 182   *R_arg = new_R;
 183 }