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1 /* Binary relations.
2 
3    Copyright (C) 2002, 2004-2005, 2009-2012 Free Software Foundation,
4    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
relation_print(relation r,relation_node size,FILE * out)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
traverse(relation_node i)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
relation_digraph(relation r,relation_node size,bitsetv * function)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
relation_transpose(relation * R_arg,relation_node n)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 }
184