1 /*
2 * Copyright (c) 1983, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29 #include "gprof.h"
30 #include "libiberty.h"
31 #include "search_list.h"
32 #include "source.h"
33 #include "symtab.h"
34 #include "cg_arcs.h"
35 #include "cg_dfn.h"
36 #include "utils.h"
37
38 #define DFN_INCR_DEPTH (128)
39
40 typedef struct
41 {
42 Sym *sym;
43 int cycle_top;
44 }
45 DFN_Stack;
46
47 static bool is_numbered (Sym *);
48 static bool is_busy (Sym *);
49 static void find_cycle (Sym *);
50 static void pre_visit (Sym *);
51 static void post_visit (Sym *);
52
53 DFN_Stack *dfn_stack = NULL;
54 int dfn_maxdepth = 0;
55 int dfn_depth = 0;
56 int dfn_counter = DFN_NAN;
57
58
59 /*
60 * Is CHILD already numbered?
61 */
62 static bool
63 is_numbered (Sym *child)
64 {
65 return child->cg.top_order != DFN_NAN && child->cg.top_order != DFN_BUSY;
66 }
67
68
69 /*
70 * Is CHILD already busy?
71 */
72 static bool
73 is_busy (Sym *child)
74 {
75 if (child->cg.top_order == DFN_NAN)
76 {
77 return false;
78 }
79 return true;
80 }
81
82
83 /*
84 * CHILD is part of a cycle. Find the top caller into this cycle
85 * that is not part of the cycle and make all functions in cycle
86 * members of that cycle (top caller == caller with smallest
87 * depth-first number).
88 */
89 static void
90 find_cycle (Sym *child)
91 {
92 Sym *head = 0;
93 Sym *tail;
94 int cycle_top;
95 int cycle_index;
96
97 for (cycle_top = dfn_depth; cycle_top > 0; --cycle_top)
98 {
99 head = dfn_stack[cycle_top].sym;
100 if (child == head)
101 {
102 break;
103 }
104 if (child->cg.cyc.head != child && child->cg.cyc.head == head)
105 {
106 break;
107 }
108 }
109 if (cycle_top <= 0)
110 {
111 fprintf (stderr, "[find_cycle] couldn't find head of cycle\n");
112 done (1);
113 }
114 #ifdef DEBUG
115 if (debug_level & DFNDEBUG)
116 {
117 printf ("[find_cycle] dfn_depth %d cycle_top %d ",
118 dfn_depth, cycle_top);
119 if (head)
120 {
121 print_name (head);
122 }
123 else
124 {
125 printf ("<unknown>");
126 }
127 printf ("\n");
128 }
129 #endif
130 if (cycle_top == dfn_depth)
131 {
132 /*
133 * This is previous function, e.g. this calls itself. Sort of
134 * boring.
135 *
136 * Since we are taking out self-cycles elsewhere no need for
137 * the special case, here.
138 */
139 DBG (DFNDEBUG,
140 printf ("[find_cycle] ");
141 print_name (child);
142 printf ("\n"));
143 }
144 else
145 {
146 /*
147 * Glom intervening functions that aren't already glommed into
148 * this cycle. Things have been glommed when their cyclehead
149 * field points to the head of the cycle they are glommed
150 * into.
151 */
152 for (tail = head; tail->cg.cyc.next; tail = tail->cg.cyc.next)
153 {
154 /* void: chase down to tail of things already glommed */
155 DBG (DFNDEBUG,
156 printf ("[find_cycle] tail ");
157 print_name (tail);
158 printf ("\n"));
159 }
160 /*
161 * If what we think is the top of the cycle has a cyclehead
162 * field, then it's not really the head of the cycle, which is
163 * really what we want.
164 */
165 if (head->cg.cyc.head != head)
166 {
167 head = head->cg.cyc.head;
168 DBG (DFNDEBUG, printf ("[find_cycle] new cyclehead ");
169 print_name (head);
170 printf ("\n"));
171 }
172 for (cycle_index = cycle_top + 1; cycle_index <= dfn_depth; ++cycle_index)
173 {
174 child = dfn_stack[cycle_index].sym;
175 if (child->cg.cyc.head == child)
176 {
177 /*
178 * Not yet glommed anywhere, glom it and fix any
179 * children it has glommed.
180 */
181 tail->cg.cyc.next = child;
182 child->cg.cyc.head = head;
183 DBG (DFNDEBUG, printf ("[find_cycle] glomming ");
184 print_name (child);
185 printf (" onto ");
186 print_name (head);
187 printf ("\n"));
188 for (tail = child; tail->cg.cyc.next; tail = tail->cg.cyc.next)
189 {
190 tail->cg.cyc.next->cg.cyc.head = head;
191 DBG (DFNDEBUG, printf ("[find_cycle] and its tail ");
192 print_name (tail->cg.cyc.next);
193 printf (" onto ");
194 print_name (head);
195 printf ("\n"));
196 }
197 }
198 else if (child->cg.cyc.head != head /* firewall */ )
199 {
200 fprintf (stderr, "[find_cycle] glommed, but not to head\n");
201 done (1);
202 }
203 }
204 }
205 }
206
207
208 /*
209 * Prepare for visiting the children of PARENT. Push a parent onto
210 * the stack and mark it busy.
211 */
212 static void
213 pre_visit (Sym *parent)
214 {
215 ++dfn_depth;
216
217 if (dfn_depth >= dfn_maxdepth)
218 {
219 dfn_maxdepth += DFN_INCR_DEPTH;
220 dfn_stack = (DFN_Stack *) xrealloc (dfn_stack,
221 dfn_maxdepth * sizeof *dfn_stack);
222 }
223
224 dfn_stack[dfn_depth].sym = parent;
225 dfn_stack[dfn_depth].cycle_top = dfn_depth;
226 parent->cg.top_order = DFN_BUSY;
227 DBG (DFNDEBUG, printf ("[pre_visit]\t\t%d:", dfn_depth);
228 print_name (parent);
229 printf ("\n"));
230 }
231
232
233 /*
234 * Done with visiting node PARENT. Pop PARENT off dfn_stack
235 * and number functions if PARENT is head of a cycle.
236 */
237 static void
238 post_visit (Sym *parent)
239 {
240 Sym *member;
241
242 DBG (DFNDEBUG, printf ("[post_visit]\t%d: ", dfn_depth);
243 print_name (parent);
244 printf ("\n"));
245 /*
246 * Number functions and things in their cycles unless the function
247 * is itself part of a cycle:
248 */
249 if (parent->cg.cyc.head == parent)
250 {
251 ++dfn_counter;
252 for (member = parent; member; member = member->cg.cyc.next)
253 {
254 member->cg.top_order = dfn_counter;
255 DBG (DFNDEBUG, printf ("[post_visit]\t\tmember ");
256 print_name (member);
257 printf ("-> cg.top_order = %d\n", dfn_counter));
258 }
259 }
260 else
261 {
262 DBG (DFNDEBUG, printf ("[post_visit]\t\tis part of a cycle\n"));
263 }
264 --dfn_depth;
265 }
266
267
268 /*
269 * Given this PARENT, depth first number its children.
270 */
271 void
272 cg_dfn (Sym *parent)
273 {
274 Arc *arc;
275
276 DBG (DFNDEBUG, printf ("[dfn] dfn( ");
277 print_name (parent);
278 printf (")\n"));
279 /*
280 * If we're already numbered, no need to look any further:
281 */
282 if (is_numbered (parent))
283 {
284 return;
285 }
286 /*
287 * If we're already busy, must be a cycle:
288 */
289 if (is_busy (parent))
290 {
291 find_cycle (parent);
292 return;
293 }
294 pre_visit (parent);
295 /*
296 * Recursively visit children:
297 */
298 for (arc = parent->cg.children; arc; arc = arc->next_child)
299 {
300 cg_dfn (arc->child);
301 }
302 post_visit (parent);
303 }