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 DFN_Stack *dfn_stack = NULL;
  38 int dfn_maxdepth = 0;
  39 int dfn_depth = 0;
  40 int dfn_counter = DFN_NAN;
  41
  42
  43 /*
  44  * Is CHILD already numbered?
  45  */
  46 static bool
  47 DEFUN (is_numbered, (child), Sym * child)
  48 {
  49   return child->cg.top_order != DFN_NAN && child->cg.top_order != DFN_BUSY;
  50 }
  51
  52
  53 /*
  54  * Is CHILD already busy?
  55  */
  56 static bool
  57 DEFUN (is_busy, (child), Sym * child)
  58 {
  59   if (child->cg.top_order == DFN_NAN)
  60     {
  61       return FALSE;
  62     }
  63   return TRUE;
  64 }
  65
  66
  67 /*
  68  * CHILD is part of a cycle.  Find the top caller into this cycle
  69  * that is not part of the cycle and make all functions in cycle
  70  * members of that cycle (top caller == caller with smallest
  71  * depth-first number).
  72  */
  73 static void
  74 DEFUN (find_cycle, (child), Sym * child)
  75 {
  76   Sym *head = 0;
  77   Sym *tail;
  78   int cycle_top;
  79   int index;
  80
  81   for (cycle_top = dfn_depth; cycle_top > 0; --cycle_top)
  82     {
  83       head = dfn_stack[cycle_top].sym;
  84       if (child == head)
  85         {
  86           break;
  87         }
  88       if (child->cg.cyc.head != child && child->cg.cyc.head == head)
  89         {
  90           break;
  91         }
  92     }
  93   if (cycle_top <= 0)
  94     {
  95       fprintf (stderr, "[find_cycle] couldn't find head of cycle\n");
  96       done (1);
  97     }
  98 #ifdef DEBUG
  99   if (debug_level & DFNDEBUG)
 100     {
 101       printf ("[find_cycle] dfn_depth %d cycle_top %d ",
 102               dfn_depth, cycle_top);
 103       if (head)
 104         {
 105           print_name (head);
 106         }
 107       else
 108         {
 109           printf ("<unknown>");
 110         }
 111       printf ("\n");
 112     }
 113 #endif
 114   if (cycle_top == dfn_depth)
 115     {
 116       /*
 117        * This is previous function, e.g. this calls itself.  Sort of
 118        * boring.
 119        *
 120        * Since we are taking out self-cycles elsewhere no need for
 121        * the special case, here.
 122        */
 123       DBG (DFNDEBUG,
 124            printf ("[find_cycle] ");
 125            print_name (child);
 126            printf ("\n"));
 127     }
 128   else
 129     {
 130       /*
 131        * Glom intervening functions that aren't already glommed into
 132        * this cycle.  Things have been glommed when their cyclehead
 133        * field points to the head of the cycle they are glommed
 134        * into.
 135        */
 136       for (tail = head; tail->cg.cyc.next; tail = tail->cg.cyc.next)
 137         {
 138           /* void: chase down to tail of things already glommed */
 139           DBG (DFNDEBUG,
 140                printf ("[find_cycle] tail ");
 141                print_name (tail);
 142                printf ("\n"));
 143         }
 144       /*
 145        * If what we think is the top of the cycle has a cyclehead
 146        * field, then it's not really the head of the cycle, which is
 147        * really what we want.
 148        */
 149       if (head->cg.cyc.head != head)
 150         {
 151           head = head->cg.cyc.head;
 152           DBG (DFNDEBUG, printf ("[find_cycle] new cyclehead ");
 153                print_name (head);
 154                printf ("\n"));
 155         }
 156       for (index = cycle_top + 1; index <= dfn_depth; ++index)
 157         {
 158           child = dfn_stack[index].sym;
 159           if (child->cg.cyc.head == child)
 160             {
 161               /*
 162                * Not yet glommed anywhere, glom it and fix any
 163                * children it has glommed.
 164                */
 165               tail->cg.cyc.next = child;
 166               child->cg.cyc.head = head;
 167               DBG (DFNDEBUG, printf ("[find_cycle] glomming ");
 168                    print_name (child);
 169                    printf (" onto ");
 170                    print_name (head);
 171                    printf ("\n"));
 172               for (tail = child; tail->cg.cyc.next; tail = tail->cg.cyc.next)
 173                 {
 174                   tail->cg.cyc.next->cg.cyc.head = head;
 175                   DBG (DFNDEBUG, printf ("[find_cycle] and its tail ");
 176                        print_name (tail->cg.cyc.next);
 177                        printf (" onto ");
 178                        print_name (head);
 179                        printf ("\n"));
 180                 }
 181             }
 182           else if (child->cg.cyc.head != head /* firewall */ )
 183             {
 184               fprintf (stderr, "[find_cycle] glommed, but not to head\n");
 185               done (1);
 186             }
 187         }
 188     }
 189 }
 190
 191
 192 /*
 193  * Prepare for visiting the children of PARENT.  Push a parent onto
 194  * the stack and mark it busy.
 195  */
 196 static void
 197 DEFUN (pre_visit, (parent), Sym * parent)
 198 {
 199   ++dfn_depth;
 200
 201   if (dfn_depth >= dfn_maxdepth)
 202     {
 203       dfn_maxdepth += DFN_INCR_DEPTH;
 204       dfn_stack = xrealloc (dfn_stack, dfn_maxdepth * sizeof *dfn_stack);
 205     }
 206
 207   dfn_stack[dfn_depth].sym = parent;
 208   dfn_stack[dfn_depth].cycle_top = dfn_depth;
 209   parent->cg.top_order = DFN_BUSY;
 210   DBG (DFNDEBUG, printf ("[pre_visit]\t\t%d:", dfn_depth);
 211        print_name (parent);
 212        printf ("\n"));
 213 }
 214
 215
 216 /*
 217  * Done with visiting node PARENT.  Pop PARENT off dfn_stack
 218  * and number functions if PARENT is head of a cycle.
 219  */
 220 static void
 221 DEFUN (post_visit, (parent), Sym * parent)
 222 {
 223   Sym *member;
 224
 225   DBG (DFNDEBUG, printf ("[post_visit]\t%d: ", dfn_depth);
 226        print_name (parent);
 227        printf ("\n"));
 228   /*
 229    * Number functions and things in their cycles unless the function
 230    * is itself part of a cycle:
 231    */
 232   if (parent->cg.cyc.head == parent)
 233     {
 234       ++dfn_counter;
 235       for (member = parent; member; member = member->cg.cyc.next)
 236         {
 237           member->cg.top_order = dfn_counter;
 238           DBG (DFNDEBUG, printf ("[post_visit]\t\tmember ");
 239                print_name (member);
 240                printf ("-> cg.top_order = %d\n", dfn_counter));
 241         }
 242     }
 243   else
 244     {
 245       DBG (DFNDEBUG, printf ("[post_visit]\t\tis part of a cycle\n"));
 246     }
 247   --dfn_depth;
 248 }
 249
 250
 251 /*
 252  * Given this PARENT, depth first number its children.
 253  */
 254 void
 255 DEFUN (cg_dfn, (parent), Sym * parent)
 256 {
 257   Arc *arc;
 258
 259   DBG (DFNDEBUG, printf ("[dfn] dfn( ");
 260        print_name (parent);
 261        printf (")\n"));
 262   /*
 263    * If we're already numbered, no need to look any further:
 264    */
 265   if (is_numbered (parent))
 266     {
 267       return;
 268     }
 269   /*
 270    * If we're already busy, must be a cycle:
 271    */
 272   if (is_busy (parent))
 273     {
 274       find_cycle (parent);
 275       return;
 276     }
 277   pre_visit (parent);
 278   /*
 279    * Recursively visit children:
 280    */
 281   for (arc = parent->cg.children; arc; arc = arc->next_child)
 282     {
 283       cg_dfn (arc->child);
 284     }
 285   post_visit (parent);
 286 }