gcc/ipa.c

   1 /* Basic IPA optimizations and utilities.
   2    Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to the Free
  18 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301, USA.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "cgraph.h"
  26
  27 /* Fill array order with all nodes with output flag set in the reverse
  28    topological order.  */
  29
  30 int
  31 cgraph_postorder (struct cgraph_node **order)
  32 {
  33   struct cgraph_node *node, *node2;
  34   int stack_size = 0;
  35   int order_pos = 0;
  36   struct cgraph_edge *edge, last;
  37
  38   struct cgraph_node **stack =
  39     xcalloc (cgraph_n_nodes, sizeof (struct cgraph_node *));
  40
  41   /* We have to deal with cycles nicely, so use a depth first traversal
  42      output algorithm.  Ignore the fact that some functions won't need
  43      to be output and put them into order as well, so we get dependencies
  44      right through intline functions.  */
  45   for (node = cgraph_nodes; node; node = node->next)
  46     node->aux = NULL;
  47   for (node = cgraph_nodes; node; node = node->next)
  48     if (!node->aux)
  49       {
  50         node2 = node;
  51         if (!node->callers)
  52           node->aux = &last;
  53         else
  54           node->aux = node->callers;
  55         while (node2)
  56           {
  57             while (node2->aux != &last)
  58               {
  59                 edge = node2->aux;
  60                 if (edge->next_caller)
  61                   node2->aux = edge->next_caller;
  62                 else
  63                   node2->aux = &last;
  64                 if (!edge->caller->aux)
  65                   {
  66                     if (!edge->caller->callers)
  67                       edge->caller->aux = &last;
  68                     else
  69                       edge->caller->aux = edge->caller->callers;
  70                     stack[stack_size++] = node2;
  71                     node2 = edge->caller;
  72                     break;
  73                   }
  74               }
  75             if (node2->aux == &last)
  76               {
  77                 order[order_pos++] = node2;
  78                 if (stack_size)
  79                   node2 = stack[--stack_size];
  80                 else
  81                   node2 = NULL;
  82               }
  83           }
  84       }
  85   free (stack);
  86   for (node = cgraph_nodes; node; node = node->next)
  87     node->aux = NULL;
  88   return order_pos;
  89 }
  90
  91 /* Perform reachability analysis and reclaim all unreachable nodes.
  92    If BEFORE_INLINING_P is true this function is called before inlining
  93    decisions has been made.  If BEFORE_INLINING_P is false this function also
  94    removes unneeded bodies of extern inline functions.  */
  95
  96 bool
  97 cgraph_remove_unreachable_nodes (bool before_inlining_p, FILE *dump_file)
  98 {
  99   struct cgraph_node *first = (void *) 1;
 100   struct cgraph_node *node;
 101   bool changed = false;
 102   int insns = 0;
 103
 104 #ifdef ENABLE_CHECKING
 105   verify_cgraph ();
 106 #endif
 107   if (dump_file)
 108     fprintf (dump_file, "\nReclaiming functions:");
 109 #ifdef ENABLE_CHECKING
 110   for (node = cgraph_nodes; node; node = node->next)
 111     gcc_assert (!node->aux);
 112 #endif
 113   for (node = cgraph_nodes; node; node = node->next)
 114     if (node->needed && !node->global.inlined_to
 115         && ((!DECL_EXTERNAL (node->decl))
 116             || !node->analyzed
 117             || before_inlining_p))
 118       {
 119         node->aux = first;
 120         first = node;
 121       }
 122     else
 123       gcc_assert (!node->aux);
 124
 125   /* Perform reachability analysis.  As a special case do not consider
 126      extern inline functions not inlined as live because we won't output
 127      them at all.  */
 128   while (first != (void *) 1)
 129     {
 130       struct cgraph_edge *e;
 131       node = first;
 132       first = first->aux;
 133
 134       for (e = node->callees; e; e = e->next_callee)
 135         if (!e->callee->aux
 136             && node->analyzed
 137             && (!e->inline_failed || !e->callee->analyzed
 138                 || (!DECL_EXTERNAL (e->callee->decl))
 139                 || before_inlining_p))
 140           {
 141             e->callee->aux = first;
 142             first = e->callee;
 143           }
 144     }
 145
 146   /* Remove unreachable nodes.  Extern inline functions need special care;
 147      Unreachable extern inline functions shall be removed.
 148      Reachable extern inline functions we never inlined shall get their bodies
 149      eliminated.
 150      Reachable extern inline functions we sometimes inlined will be turned into
 151      unanalyzed nodes so they look like for true extern functions to the rest
 152      of code.  Body of such functions is released via remove_node once the
 153      inline clones are eliminated.  */
 154   for (node = cgraph_nodes; node; node = node->next)
 155     {
 156       if (!node->aux)
 157         {
 158           int local_insns;
 159           tree decl = node->decl;
 160
 161           node->global.inlined_to = NULL;
 162           if (DECL_STRUCT_FUNCTION (decl))
 163             local_insns = node->local.self_insns;
 164           else
 165             local_insns = 0;
 166           if (dump_file)
 167             fprintf (dump_file, " %s", cgraph_node_name (node));
 168           if (!node->analyzed || !DECL_EXTERNAL (node->decl)
 169               || before_inlining_p)
 170             cgraph_remove_node (node);
 171           else
 172             {
 173               struct cgraph_edge *e;
 174
 175               for (e = node->callers; e; e = e->next_caller)
 176                 if (e->caller->aux)
 177                   break;
 178               if (e || node->needed)
 179                 {
 180                   struct cgraph_node *clone;
 181
 182                   for (clone = node->next_clone; clone;
 183                        clone = clone->next_clone)
 184                     if (clone->aux)
 185                       break;
 186                   if (!clone)
 187                     {
 188                       DECL_SAVED_TREE (node->decl) = NULL;
 189                       DECL_STRUCT_FUNCTION (node->decl) = NULL;
 190                       DECL_INITIAL (node->decl) = error_mark_node;
 191                       node->analyzed = false;
 192                     }
 193                   cgraph_node_remove_callees (node);
 194                   node->analyzed = false;
 195                 }
 196               else
 197                 cgraph_remove_node (node);
 198             }
 199           if (!DECL_SAVED_TREE (decl))
 200             insns += local_insns;
 201           changed = true;
 202         }
 203     }
 204   for (node = cgraph_nodes; node; node = node->next)
 205     node->aux = NULL;
 206   if (dump_file)
 207     fprintf (dump_file, "\nReclaimed %i insns", insns);
 208   return changed;
 209 }