gprof/cg_dfn.c

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