gprof/cg_dfn.c

   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
  40 typedef struct
  41   {
  42     Sym *sym;
  43     int cycle_top;
  44   }
  45 DFN_Stack;
  46
  47 static boolean is_numbered PARAMS ((Sym *));
  48 static boolean is_busy PARAMS ((Sym *));
  49 static void find_cycle PARAMS ((Sym *));
  50 static void pre_visit PARAMS ((Sym *));
  51 static void post_visit PARAMS ((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 boolean
  63 is_numbered (child)
  64      Sym *child;
  65 {
  66   return child->cg.top_order != DFN_NAN && child->cg.top_order != DFN_BUSY;
  67 }
  68
  69
  70 /*
  71  * Is CHILD already busy?
  72  */
  73 static boolean
  74 is_busy (child)
  75      Sym *child;
  76 {
  77   if (child->cg.top_order == DFN_NAN)
  78     {
  79       return false;
  80     }
  81   return true;
  82 }
  83
  84
  85 /*
  86  * CHILD is part of a cycle.  Find the top caller into this cycle
  87  * that is not part of the cycle and make all functions in cycle
  88  * members of that cycle (top caller == caller with smallest
  89  * depth-first number).
  90  */
  91 static void
  92 find_cycle (child)
  93      Sym *child;
  94 {
  95   Sym *head = 0;
  96   Sym *tail;
  97   int cycle_top;
  98   int index;
  99
 100   for (cycle_top = dfn_depth; cycle_top > 0; --cycle_top)
 101     {
 102       head = dfn_stack[cycle_top].sym;
 103       if (child == head)
 104         {
 105           break;
 106         }
 107       if (child->cg.cyc.head != child && child->cg.cyc.head == head)
 108         {
 109           break;
 110         }
 111     }
 112   if (cycle_top <= 0)
 113     {
 114       fprintf (stderr, "[find_cycle] couldn't find head of cycle\n");
 115       done (1);
 116     }
 117 #ifdef DEBUG
 118   if (debug_level & DFNDEBUG)
 119     {
 120       printf ("[find_cycle] dfn_depth %d cycle_top %d ",
 121               dfn_depth, cycle_top);
 122       if (head)
 123         {
 124           print_name (head);
 125         }
 126       else
 127         {
 128           printf ("<unknown>");
 129         }
 130       printf ("\n");
 131     }
 132 #endif
 133   if (cycle_top == dfn_depth)
 134     {
 135       /*
 136        * This is previous function, e.g. this calls itself.  Sort of
 137        * boring.
 138        *
 139        * Since we are taking out self-cycles elsewhere no need for
 140        * the special case, here.
 141        */
 142       DBG (DFNDEBUG,
 143            printf ("[find_cycle] ");
 144            print_name (child);
 145            printf ("\n"));
 146     }
 147   else
 148     {
 149       /*
 150        * Glom intervening functions that aren't already glommed into
 151        * this cycle.  Things have been glommed when their cyclehead
 152        * field points to the head of the cycle they are glommed
 153        * into.
 154        */
 155       for (tail = head; tail->cg.cyc.next; tail = tail->cg.cyc.next)
 156         {
 157           /* void: chase down to tail of things already glommed */
 158           DBG (DFNDEBUG,
 159                printf ("[find_cycle] tail ");
 160                print_name (tail);
 161                printf ("\n"));
 162         }
 163       /*
 164        * If what we think is the top of the cycle has a cyclehead
 165        * field, then it's not really the head of the cycle, which is
 166        * really what we want.
 167        */
 168       if (head->cg.cyc.head != head)
 169         {
 170           head = head->cg.cyc.head;
 171           DBG (DFNDEBUG, printf ("[find_cycle] new cyclehead ");
 172                print_name (head);
 173                printf ("\n"));
 174         }
 175       for (index = cycle_top + 1; index <= dfn_depth; ++index)
 176         {
 177           child = dfn_stack[index].sym;
 178           if (child->cg.cyc.head == child)
 179             {
 180               /*
 181                * Not yet glommed anywhere, glom it and fix any
 182                * children it has glommed.
 183                */
 184               tail->cg.cyc.next = child;
 185               child->cg.cyc.head = head;
 186               DBG (DFNDEBUG, printf ("[find_cycle] glomming ");
 187                    print_name (child);
 188                    printf (" onto ");
 189                    print_name (head);
 190                    printf ("\n"));
 191               for (tail = child; tail->cg.cyc.next; tail = tail->cg.cyc.next)
 192                 {
 193                   tail->cg.cyc.next->cg.cyc.head = head;
 194                   DBG (DFNDEBUG, printf ("[find_cycle] and its tail ");
 195                        print_name (tail->cg.cyc.next);
 196                        printf (" onto ");
 197                        print_name (head);
 198                        printf ("\n"));
 199                 }
 200             }
 201           else if (child->cg.cyc.head != head /* firewall */ )
 202             {
 203               fprintf (stderr, "[find_cycle] glommed, but not to head\n");
 204               done (1);
 205             }
 206         }
 207     }
 208 }
 209
 210
 211 /*
 212  * Prepare for visiting the children of PARENT.  Push a parent onto
 213  * the stack and mark it busy.
 214  */
 215 static void
 216 pre_visit (parent)
 217      Sym *parent;
 218 {
 219   ++dfn_depth;
 220
 221   if (dfn_depth >= dfn_maxdepth)
 222     {
 223       dfn_maxdepth += DFN_INCR_DEPTH;
 224       dfn_stack = xrealloc (dfn_stack, dfn_maxdepth * sizeof *dfn_stack);
 225     }
 226
 227   dfn_stack[dfn_depth].sym = parent;
 228   dfn_stack[dfn_depth].cycle_top = dfn_depth;
 229   parent->cg.top_order = DFN_BUSY;
 230   DBG (DFNDEBUG, printf ("[pre_visit]\t\t%d:", dfn_depth);
 231        print_name (parent);
 232        printf ("\n"));
 233 }
 234
 235
 236 /*
 237  * Done with visiting node PARENT.  Pop PARENT off dfn_stack
 238  * and number functions if PARENT is head of a cycle.
 239  */
 240 static void
 241 post_visit (parent)
 242      Sym *parent;
 243 {
 244   Sym *member;
 245
 246   DBG (DFNDEBUG, printf ("[post_visit]\t%d: ", dfn_depth);
 247        print_name (parent);
 248        printf ("\n"));
 249   /*
 250    * Number functions and things in their cycles unless the function
 251    * is itself part of a cycle:
 252    */
 253   if (parent->cg.cyc.head == parent)
 254     {
 255       ++dfn_counter;
 256       for (member = parent; member; member = member->cg.cyc.next)
 257         {
 258           member->cg.top_order = dfn_counter;
 259           DBG (DFNDEBUG, printf ("[post_visit]\t\tmember ");
 260                print_name (member);
 261                printf ("-> cg.top_order = %d\n", dfn_counter));
 262         }
 263     }
 264   else
 265     {
 266       DBG (DFNDEBUG, printf ("[post_visit]\t\tis part of a cycle\n"));
 267     }
 268   --dfn_depth;
 269 }
 270
 271
 272 /*
 273  * Given this PARENT, depth first number its children.
 274  */
 275 void
 276 cg_dfn (parent)
 277      Sym *parent;
 278 {
 279   Arc *arc;
 280
 281   DBG (DFNDEBUG, printf ("[dfn] dfn( ");
 282        print_name (parent);
 283        printf (")\n"));
 284   /*
 285    * If we're already numbered, no need to look any further:
 286    */
 287   if (is_numbered (parent))
 288     {
 289       return;
 290     }
 291   /*
 292    * If we're already busy, must be a cycle:
 293    */
 294   if (is_busy (parent))
 295     {
 296       find_cycle (parent);
 297       return;
 298     }
 299   pre_visit (parent);
 300   /*
 301    * Recursively visit children:
 302    */
 303   for (arc = parent->cg.children; arc; arc = arc->next_child)
 304     {
 305       cg_dfn (arc->child);
 306     }
 307   post_visit (parent);
 308 }