src/relation.c

   1 /* Binary relations.
   2    Copyright (C) 2002 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 i, j;
  32
  33   for (i = 0; i < size; ++i)
  34     {
  35       fprintf (out, "%3d: ", i);
  36       if (r[i])
  37         for (j = 0; r[i][j] != -1; ++j)
  38           fprintf (out, "%3d ", r[i][j]);
  39       fputc ('\n', out);
  40     }
  41   fputc ('\n', out);
  42 }
  43
  44
  45 /*---------------------------------------------------------------.
  46 | digraph & traverse.                                            |
  47 |                                                                |
  48 | The following variables are used as common storage between the |
  49 | two.                                                           |
  50 `---------------------------------------------------------------*/
  51
  52 static relation R;
  53 static relation_nodes INDEX;
  54 static relation_nodes VERTICES;
  55 static int top;
  56 static int infinity;
  57 static bitsetv F;
  58
  59 static void
  60 traverse (int i)
  61 {
  62   int j;
  63   int height;
  64
  65   VERTICES[++top] = i;
  66   INDEX[i] = height = top;
  67
  68   if (R[i])
  69     for (j = 0; R[i][j] >= 0; ++j)
  70       {
  71         if (INDEX[R[i][j]] == 0)
  72           traverse (R[i][j]);
  73
  74         if (INDEX[i] > INDEX[R[i][j]])
  75           INDEX[i] = INDEX[R[i][j]];
  76
  77         bitset_or (F[i], F[i], F[R[i][j]]);
  78       }
  79
  80   if (INDEX[i] == height)
  81     for (;;)
  82       {
  83         j = VERTICES[top--];
  84         INDEX[j] = infinity;
  85
  86         if (i == j)
  87           break;
  88
  89         bitset_copy (F[j], F[i]);
  90       }
  91 }
  92
  93
  94 void
  95 relation_digraph (relation r, size_t size, bitsetv *function)
  96 {
  97   unsigned i;
  98
  99   infinity = size + 2;
 100   INDEX = XCALLOC (relation_node, size + 1);
 101   VERTICES = XCALLOC (relation_node, size + 1);
 102   top = 0;
 103
 104   R = r;
 105   F = *function;
 106
 107   for (i = 0; i < size; i++)
 108     INDEX[i] = 0;
 109
 110   for (i = 0; i < size; i++)
 111     if (INDEX[i] == 0 && R[i])
 112       traverse (i);
 113
 114   XFREE (INDEX);
 115   XFREE (VERTICES);
 116
 117   *function = F;
 118 }
 119
 120
 121 /*-------------------------------------------.
 122 | Destructively transpose R_ARG, of size N.  |
 123 `-------------------------------------------*/
 124
 125 void
 126 relation_transpose (relation *R_arg, int n)
 127 {
 128   /* The result. */
 129   relation new_R = XCALLOC (relation_nodes, n);
 130   /* END_R[I] -- next entry of NEW_R[I]. */
 131   relation end_R = XCALLOC (relation_nodes, n);
 132   /* NEDGES[I] -- total size of NEW_R[I]. */
 133   int *nedges = XCALLOC (int, n);
 134   int i, j;
 135
 136   if (trace_flag & trace_sets)
 137     {
 138       fputs ("relation_transpose: input\n", stderr);
 139       relation_print (*R_arg, n, stderr);
 140     }
 141
 142   /* Count. */
 143   for (i = 0; i < n; i++)
 144     if ((*R_arg)[i])
 145       for (j = 0; (*R_arg)[i][j] >= 0; ++j)
 146         ++nedges[(*R_arg)[i][j]];
 147
 148   /* Allocate. */
 149   for (i = 0; i < n; i++)
 150     if (nedges[i] > 0)
 151       {
 152         relation_node *sp = XCALLOC (relation_node, nedges[i] + 1);
 153         sp[nedges[i]] = -1;
 154         new_R[i] = sp;
 155         end_R[i] = sp;
 156       }
 157
 158   /* Store. */
 159   for (i = 0; i < n; i++)
 160     if ((*R_arg)[i])
 161       for (j = 0; (*R_arg)[i][j] >= 0; ++j)
 162         {
 163           *end_R[(*R_arg)[i][j]] = i;
 164           ++end_R[(*R_arg)[i][j]];
 165         }
 166
 167   free (nedges);
 168   free (end_R);
 169
 170   /* Free the input: it is replaced with the result. */
 171   for (i = 0; i < n; i++)
 172     XFREE ((*R_arg)[i]);
 173   free (*R_arg);
 174
 175   if (trace_flag & trace_sets)
 176     {
 177       fputs ("relation_transpose: output\n", stderr);
 178       relation_print (new_R, n, stderr);
 179     }
 180
 181   *R_arg = new_R;
 182 }