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 <stdio.h>
  20 #include "gprof.h"
  21 #include "cg_arcs.h"
  22 #include "cg_dfn.h"
  23 #include "symtab.h"
  24 #include "utils.h"
  25
  26 #define DFN_DEPTH       100
  27
  28 typedef struct
  29   {
  30     Sym *sym;
  31     int cycle_top;
  32   }
  33 DFN_Stack;
  34
  35 DFN_Stack dfn_stack[DFN_DEPTH];
  36 int dfn_depth = 0;
  37 int dfn_counter = DFN_NAN;
  38
  39
  40 /*
  41  * Is CHILD already numbered?
  42  */
  43 static bool
  44 DEFUN (is_numbered, (child), Sym * child)
  45 {
  46   return child->cg.top_order != DFN_NAN && child->cg.top_order != DFN_BUSY;
  47 }
  48
  49
  50 /*
  51  * Is CHILD already busy?
  52  */
  53 static bool
  54 DEFUN (is_busy, (child), Sym * child)
  55 {
  56   if (child->cg.top_order == DFN_NAN)
  57     {
  58       return FALSE;
  59     }
  60   return TRUE;
  61 }
  62
  63
  64 /*
  65  * CHILD is part of a cycle.  Find the top caller into this cycle
  66  * that is not part of the cycle and make all functions in cycle
  67  * members of that cycle (top caller == caller with smallest
  68  * depth-first number).
  69  */
  70 static void
  71 DEFUN (find_cycle, (child), Sym * child)
  72 {
  73   Sym *head = 0;
  74   Sym *tail;
  75   int cycle_top;
  76   int index;
  77
  78   for (cycle_top = dfn_depth; cycle_top > 0; --cycle_top)
  79     {
  80       head = dfn_stack[cycle_top].sym;
  81       if (child == head)
  82         {
  83           break;
  84         }
  85       if (child->cg.cyc.head != child && child->cg.cyc.head == head)
  86         {
  87           break;
  88         }
  89     }
  90   if (cycle_top <= 0)
  91     {
  92       fprintf (stderr, "[find_cycle] couldn't find head of cycle\n");
  93       done (1);
  94     }
  95 #ifdef DEBUG
  96   if (debug_level & DFNDEBUG)
  97     {
  98       printf ("[find_cycle] dfn_depth %d cycle_top %d ",
  99               dfn_depth, cycle_top);
 100       if (head)
 101         {
 102           print_name (head);
 103         }
 104       else
 105         {
 106           printf ("<unknown>");
 107         }
 108       printf ("\n");
 109     }
 110 #endif
 111   if (cycle_top == dfn_depth)
 112     {
 113       /*
 114        * This is previous function, e.g. this calls itself.  Sort of
 115        * boring.
 116        *
 117        * Since we are taking out self-cycles elsewhere no need for
 118        * the special case, here.
 119        */
 120       DBG (DFNDEBUG,
 121            printf ("[find_cycle] ");
 122            print_name (child);
 123            printf ("\n"));
 124     }
 125   else
 126     {
 127       /*
 128        * Glom intervening functions that aren't already glommed into
 129        * this cycle.  Things have been glommed when their cyclehead
 130        * field points to the head of the cycle they are glommed
 131        * into.
 132        */
 133       for (tail = head; tail->cg.cyc.next; tail = tail->cg.cyc.next)
 134         {
 135           /* void: chase down to tail of things already glommed */
 136           DBG (DFNDEBUG,
 137                printf ("[find_cycle] tail ");
 138                print_name (tail);
 139                printf ("\n"));
 140         }
 141       /*
 142        * If what we think is the top of the cycle has a cyclehead
 143        * field, then it's not really the head of the cycle, which is
 144        * really what we want.
 145        */
 146       if (head->cg.cyc.head != head)
 147         {
 148           head = head->cg.cyc.head;
 149           DBG (DFNDEBUG, printf ("[find_cycle] new cyclehead ");
 150                print_name (head);
 151                printf ("\n"));
 152         }
 153       for (index = cycle_top + 1; index <= dfn_depth; ++index)
 154         {
 155           child = dfn_stack[index].sym;
 156           if (child->cg.cyc.head == child)
 157             {
 158               /*
 159                * Not yet glommed anywhere, glom it and fix any
 160                * children it has glommed.
 161                */
 162               tail->cg.cyc.next = child;
 163               child->cg.cyc.head = head;
 164               DBG (DFNDEBUG, printf ("[find_cycle] glomming ");
 165                    print_name (child);
 166                    printf (" onto ");
 167                    print_name (head);
 168                    printf ("\n"));
 169               for (tail = child; tail->cg.cyc.next; tail = tail->cg.cyc.next)
 170                 {
 171                   tail->cg.cyc.next->cg.cyc.head = head;
 172                   DBG (DFNDEBUG, printf ("[find_cycle] and its tail ");
 173                        print_name (tail->cg.cyc.next);
 174                        printf (" onto ");
 175                        print_name (head);
 176                        printf ("\n"));
 177                 }
 178             }
 179           else if (child->cg.cyc.head != head /* firewall */ )
 180             {
 181               fprintf (stderr, "[find_cycle] glommed, but not to head\n");
 182               done (1);
 183             }
 184         }
 185     }
 186 }
 187
 188
 189 /*
 190  * Prepare for visiting the children of PARENT.  Push a parent onto
 191  * the stack and mark it busy.
 192  */
 193 static void
 194 DEFUN (pre_visit, (parent), Sym * parent)
 195 {
 196   ++dfn_depth;
 197   if (dfn_depth >= DFN_DEPTH)
 198     {
 199       fprintf (stderr, "[pre_visit] dfn_stack overflow\n");
 200       done (1);
 201     }
 202   dfn_stack[dfn_depth].sym = parent;
 203   dfn_stack[dfn_depth].cycle_top = dfn_depth;
 204   parent->cg.top_order = DFN_BUSY;
 205   DBG (DFNDEBUG, printf ("[pre_visit]\t\t%d:", dfn_depth);
 206        print_name (parent);
 207        printf ("\n"));
 208 }
 209
 210
 211 /*
 212  * Done with visiting node PARENT.  Pop PARENT off dfn_stack
 213  * and number functions if PARENT is head of a cycle.
 214  */
 215 static void
 216 DEFUN (post_visit, (parent), Sym * parent)
 217 {
 218   Sym *member;
 219
 220   DBG (DFNDEBUG, printf ("[post_visit]\t%d: ", dfn_depth);
 221        print_name (parent);
 222        printf ("\n"));
 223   /*
 224    * Number functions and things in their cycles unless the function
 225    * is itself part of a cycle:
 226    */
 227   if (parent->cg.cyc.head == parent)
 228     {
 229       ++dfn_counter;
 230       for (member = parent; member; member = member->cg.cyc.next)
 231         {
 232           member->cg.top_order = dfn_counter;
 233           DBG (DFNDEBUG, printf ("[post_visit]\t\tmember ");
 234                print_name (member);
 235                printf ("-> cg.top_order = %d\n", dfn_counter));
 236         }
 237     }
 238   else
 239     {
 240       DBG (DFNDEBUG, printf ("[post_visit]\t\tis part of a cycle\n"));
 241     }
 242   --dfn_depth;
 243 }
 244
 245
 246 /*
 247  * Given this PARENT, depth first number its children.
 248  */
 249 void
 250 DEFUN (cg_dfn, (parent), Sym * parent)
 251 {
 252   Arc *arc;
 253
 254   DBG (DFNDEBUG, printf ("[dfn] dfn( ");
 255        print_name (parent);
 256        printf (")\n"));
 257   /*
 258    * If we're already numbered, no need to look any further:
 259    */
 260   if (is_numbered (parent))
 261     {
 262       return;
 263     }
 264   /*
 265    * If we're already busy, must be a cycle:
 266    */
 267   if (is_busy (parent))
 268     {
 269       find_cycle (parent);
 270       return;
 271     }
 272   pre_visit (parent);
 273   /*
 274    * Recursively visit children:
 275    */
 276   for (arc = parent->cg.children; arc; arc = arc->next_child)
 277     {
 278       cg_dfn (arc->child);
 279     }
 280   post_visit (parent);
 281 }