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 "libiberty.h"
30#include "gprof.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
40typedef struct
41  {
42    Sym *sym;
43    int cycle_top;
44  }
45DFN_Stack;
46
47static bfd_boolean is_numbered (Sym *);
48static bfd_boolean is_busy (Sym *);
49static void find_cycle (Sym *);
50static void pre_visit (Sym *);
51static void post_visit (Sym *);
52
53DFN_Stack *dfn_stack = NULL;
54int dfn_maxdepth = 0;
55int dfn_depth = 0;
56int dfn_counter = DFN_NAN;
57
58
59/*
60 * Is CHILD already numbered?
61 */
62static bfd_boolean
63is_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 */
72static bfd_boolean
73is_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 */
89static void
90find_cycle (Sym *child)
91{
92  Sym *head = 0;
93  Sym *tail;
94  int cycle_top;
95  int 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 (index = cycle_top + 1; index <= dfn_depth; ++index)
173	{
174	  child = dfn_stack[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 */
212static void
213pre_visit (Sym *parent)
214{
215  ++dfn_depth;
216
217  if (dfn_depth >= dfn_maxdepth)
218    {
219      dfn_maxdepth += DFN_INCR_DEPTH;
220      dfn_stack = xrealloc (dfn_stack, dfn_maxdepth * sizeof *dfn_stack);
221    }
222
223  dfn_stack[dfn_depth].sym = parent;
224  dfn_stack[dfn_depth].cycle_top = dfn_depth;
225  parent->cg.top_order = DFN_BUSY;
226  DBG (DFNDEBUG, printf ("[pre_visit]\t\t%d:", dfn_depth);
227       print_name (parent);
228       printf ("\n"));
229}
230
231
232/*
233 * Done with visiting node PARENT.  Pop PARENT off dfn_stack
234 * and number functions if PARENT is head of a cycle.
235 */
236static void
237post_visit (Sym *parent)
238{
239  Sym *member;
240
241  DBG (DFNDEBUG, printf ("[post_visit]\t%d: ", dfn_depth);
242       print_name (parent);
243       printf ("\n"));
244  /*
245   * Number functions and things in their cycles unless the function
246   * is itself part of a cycle:
247   */
248  if (parent->cg.cyc.head == parent)
249    {
250      ++dfn_counter;
251      for (member = parent; member; member = member->cg.cyc.next)
252	{
253	  member->cg.top_order = dfn_counter;
254	  DBG (DFNDEBUG, printf ("[post_visit]\t\tmember ");
255	       print_name (member);
256	       printf ("-> cg.top_order = %d\n", dfn_counter));
257	}
258    }
259  else
260    {
261      DBG (DFNDEBUG, printf ("[post_visit]\t\tis part of a cycle\n"));
262    }
263  --dfn_depth;
264}
265
266
267/*
268 * Given this PARENT, depth first number its children.
269 */
270void
271cg_dfn (Sym *parent)
272{
273  Arc *arc;
274
275  DBG (DFNDEBUG, printf ("[dfn] dfn( ");
276       print_name (parent);
277       printf (")\n"));
278  /*
279   * If we're already numbered, no need to look any further:
280   */
281  if (is_numbered (parent))
282    {
283      return;
284    }
285  /*
286   * If we're already busy, must be a cycle:
287   */
288  if (is_busy (parent))
289    {
290      find_cycle (parent);
291      return;
292    }
293  pre_visit (parent);
294  /*
295   * Recursively visit children:
296   */
297  for (arc = parent->cg.children; arc; arc = arc->next_child)
298    {
299      cg_dfn (arc->child);
300    }
301  post_visit (parent);
302}
303