src/relation.c

   1 /* Binary relations.
   2    Copyright (C) 2002, 2004 Free Software Foundation, Inc.
   3
   4    This file is part of Bison, the GNU Compiler Compiler.
   5
   6    Bison is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    Bison is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with Bison; see the file COPYING.  If not, write to
  18    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include "system.h"
  22
  23 #include <bitsetv.h>
  24
  25 #include "getargs.h"
  26 #include "relation.h"
  27
  28 void
  29 relation_print (relation r, size_t size, FILE *out)
  30 {
  31   unsigned int i;
  32   unsigned int j;
  33
  34   for (i = 0; i < size; ++i)
  35     {
  36       fprintf (out, "%3d: ", i);
  37       if (r[i])
  38         for (j = 0; r[i][j] != -1; ++j)
  39           fprintf (out, "%3d ", r[i][j]);
  40       fputc ('\n', out);
  41     }
  42   fputc ('\n', out);
  43 }
  44
  45
  46 /*---------------------------------------------------------------.
  47 | digraph & traverse.                                            |
  48 |                                                                |
  49 | The following variables are used as common storage between the |
  50 | two.                                                           |
  51 `---------------------------------------------------------------*/
  52
  53 static relation R;
  54 static relation_nodes INDEX;
  55 static relation_nodes VERTICES;
  56 static int top;
  57 static int infinity;
  58 static bitsetv F;
  59
  60 static void
  61 traverse (int i)
  62 {
  63   int j;
  64   int height;
  65
  66   VERTICES[++top] = i;
  67   INDEX[i] = height = top;
  68
  69   if (R[i])
  70     for (j = 0; R[i][j] >= 0; ++j)
  71       {
  72         if (INDEX[R[i][j]] == 0)
  73           traverse (R[i][j]);
  74
  75         if (INDEX[i] > INDEX[R[i][j]])
  76           INDEX[i] = INDEX[R[i][j]];
  77
  78         bitset_or (F[i], F[i], F[R[i][j]]);
  79       }
  80
  81   if (INDEX[i] == height)
  82     for (;;)
  83       {
  84         j = VERTICES[top--];
  85         INDEX[j] = infinity;
  86
  87         if (i == j)
  88           break;
  89
  90         bitset_copy (F[j], F[i]);
  91       }
  92 }
  93
  94
  95 void
  96 relation_digraph (relation r, size_t size, bitsetv *function)
  97 {
  98   unsigned int i;
  99
 100   infinity = size + 2;
 101   CALLOC (INDEX, size + 1);
 102   CALLOC (VERTICES, size + 1);
 103   top = 0;
 104
 105   R = r;
 106   F = *function;
 107
 108   for (i = 0; i < size; i++)
 109     INDEX[i] = 0;
 110
 111   for (i = 0; i < size; i++)
 112     if (INDEX[i] == 0 && R[i])
 113       traverse (i);
 114
 115   XFREE (INDEX);
 116   XFREE (VERTICES);
 117
 118   *function = F;
 119 }
 120
 121
 122 /*-------------------------------------------.
 123 | Destructively transpose R_ARG, of size N.  |
 124 `-------------------------------------------*/
 125
 126 void
 127 relation_transpose (relation *R_arg, int n)
 128 {
 129   /* The result. */
 130   relation new_R = CALLOC (new_R, n);
 131   /* END_R[I] -- next entry of NEW_R[I]. */
 132   relation end_R = CALLOC (end_R, n);
 133   /* NEDGES[I] -- total size of NEW_R[I]. */
 134   int *nedges = CALLOC (nedges, n);
 135   int i, j;
 136
 137   if (trace_flag & trace_sets)
 138     {
 139       fputs ("relation_transpose: input\n", stderr);
 140       relation_print (*R_arg, n, stderr);
 141     }
 142
 143   /* Count. */
 144   for (i = 0; i < n; i++)
 145     if ((*R_arg)[i])
 146       for (j = 0; (*R_arg)[i][j] >= 0; ++j)
 147         ++nedges[(*R_arg)[i][j]];
 148
 149   /* Allocate. */
 150   for (i = 0; i < n; i++)
 151     if (nedges[i] > 0)
 152       {
 153         relation_node *sp = CALLOC (sp, nedges[i] + 1);
 154         sp[nedges[i]] = -1;
 155         new_R[i] = sp;
 156         end_R[i] = sp;
 157       }
 158
 159   /* Store. */
 160   for (i = 0; i < n; i++)
 161     if ((*R_arg)[i])
 162       for (j = 0; (*R_arg)[i][j] >= 0; ++j)
 163         {
 164           *end_R[(*R_arg)[i][j]] = i;
 165           ++end_R[(*R_arg)[i][j]];
 166         }
 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     XFREE ((*R_arg)[i]);
 174   free (*R_arg);
 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 }