gcc/ipa-inline-transform.c

   1 /* Callgraph transformations to handle inlining
   2    Copyright (C) 2003, 2004, 2007, 2008, 2009, 2010, 2011
   3    Free Software Foundation, Inc.
   4    Contributed by Jan Hubicka
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 /* The inline decisions are stored in callgraph in "inline plan" and
  23    applied later.
  24
  25    To mark given call inline, use inline_call function.
  26    The function marks the edge inlinable and, if necessary, produces
  27    virtual clone in the callgraph representing the new copy of callee's
  28    function body.
  29
  30    The inline plan is applied on given function body by inline_transform.  */
  31
  32 #include "config.h"
  33 #include "system.h"
  34 #include "coretypes.h"
  35 #include "tm.h"
  36 #include "tree.h"
  37 #include "langhooks.h"
  38 #include "cgraph.h"
  39 #include "timevar.h"
  40 #include "output.h"
  41 #include "intl.h"
  42 #include "coverage.h"
  43 #include "ggc.h"
  44 #include "tree-flow.h"
  45 #include "ipa-prop.h"
  46 #include "ipa-inline.h"
  47 #include "tree-inline.h"
  48
  49 int ncalls_inlined;
  50 int nfunctions_inlined;
  51
  52 /* Scale frequency of NODE edges by FREQ_SCALE and increase loop nest
  53    by NEST.  */
  54
  55 static void
  56 update_noncloned_frequencies (struct cgraph_node *node,
  57                               int freq_scale, int nest)
  58 {
  59   struct cgraph_edge *e;
  60
  61   /* We do not want to ignore high loop nest after freq drops to 0.  */
  62   if (!freq_scale)
  63     freq_scale = 1;
  64   for (e = node->callees; e; e = e->next_callee)
  65     {
  66       e->loop_nest += nest;
  67       e->frequency = e->frequency * (gcov_type) freq_scale / CGRAPH_FREQ_BASE;
  68       if (e->frequency > CGRAPH_FREQ_MAX)
  69         e->frequency = CGRAPH_FREQ_MAX;
  70       if (!e->inline_failed)
  71         update_noncloned_frequencies (e->callee, freq_scale, nest);
  72     }
  73 }
  74
  75
  76 /* E is expected to be an edge being inlined.  Clone destination node of
  77    the edge and redirect it to the new clone.
  78    DUPLICATE is used for bookkeeping on whether we are actually creating new
  79    clones or re-using node originally representing out-of-line function call.
  80    */
  81
  82 void
  83 clone_inlined_nodes (struct cgraph_edge *e, bool duplicate,
  84                      bool update_original, int *overall_size)
  85 {
  86   HOST_WIDE_INT peak;
  87   struct inline_summary *caller_info, *callee_info;
  88
  89   if (duplicate)
  90     {
  91       /* We may eliminate the need for out-of-line copy to be output.
  92          In that case just go ahead and re-use it.  This is not just an
  93          memory optimization.  Making offline copy of fuction disappear
  94          from the program will improve future decisions on inlining.  */
  95       if (!e->callee->callers->next_caller
  96           /* Recursive inlining never wants the master clone to
  97              be overwritten.  */
  98           && update_original
  99           /* FIXME: When address is taken of DECL_EXTERNAL function we still
 100              can remove its offline copy, but we would need to keep unanalyzed
 101              node in the callgraph so references can point to it.  */
 102           && !e->callee->address_taken
 103           && cgraph_can_remove_if_no_direct_calls_p (e->callee)
 104           /* Inlining might enable more devirtualizing, so we want to remove
 105              those only after all devirtualizable virtual calls are processed.
 106              Lacking may edges in callgraph we just preserve them post
 107              inlining.  */
 108           && (!DECL_VIRTUAL_P (e->callee->decl)
 109               || (!DECL_COMDAT (e->callee->decl)
 110                   && !DECL_EXTERNAL (e->callee->decl)))
 111           /* Don't reuse if more than one function shares a comdat group.
 112              If the other function(s) are needed, we need to emit even
 113              this function out of line.  */
 114           && !e->callee->same_comdat_group
 115           /* During early inlining some unanalyzed cgraph nodes might be in the
 116              callgraph and they might reffer the function in question.  */
 117           && !cgraph_new_nodes)
 118         {
 119           gcc_assert (!e->callee->global.inlined_to);
 120           if (e->callee->analyzed && !DECL_EXTERNAL (e->callee->decl))
 121             {
 122               if (overall_size)
 123                 *overall_size -= inline_summary (e->callee)->size;
 124               nfunctions_inlined++;
 125             }
 126           duplicate = false;
 127           e->callee->local.externally_visible = false;
 128           update_noncloned_frequencies (e->callee, e->frequency, e->loop_nest);
 129         }
 130       else
 131         {
 132           struct cgraph_node *n;
 133           n = cgraph_clone_node (e->callee, e->callee->decl,
 134                                  e->count, e->frequency, e->loop_nest,
 135                                  update_original, NULL);
 136           cgraph_redirect_edge_callee (e, n);
 137         }
 138     }
 139
 140   callee_info = inline_summary (e->callee);
 141   caller_info = inline_summary (e->caller);
 142
 143   if (e->caller->global.inlined_to)
 144     e->callee->global.inlined_to = e->caller->global.inlined_to;
 145   else
 146     e->callee->global.inlined_to = e->caller;
 147   callee_info->stack_frame_offset
 148     = caller_info->stack_frame_offset
 149       + caller_info->estimated_self_stack_size;
 150   peak = callee_info->stack_frame_offset
 151       + callee_info->estimated_self_stack_size;
 152   if (inline_summary (e->callee->global.inlined_to)->estimated_stack_size
 153       < peak)
 154     inline_summary (e->callee->global.inlined_to)->estimated_stack_size = peak;
 155   cgraph_propagate_frequency (e->callee);
 156
 157   /* Recursively clone all bodies.  */
 158   for (e = e->callee->callees; e; e = e->next_callee)
 159     if (!e->inline_failed)
 160       clone_inlined_nodes (e, duplicate, update_original, overall_size);
 161 }
 162
 163
 164 /* Mark edge E as inlined and update callgraph accordingly.  UPDATE_ORIGINAL
 165    specify whether profile of original function should be updated.  If any new
 166    indirect edges are discovered in the process, add them to NEW_EDGES, unless
 167    it is NULL.  Return true iff any new callgraph edges were discovered as a
 168    result of inlining.  */
 169
 170 bool
 171 inline_call (struct cgraph_edge *e, bool update_original,
 172              VEC (cgraph_edge_p, heap) **new_edges,
 173              int *overall_size)
 174 {
 175   int old_size = 0, new_size = 0;
 176   struct cgraph_node *to = NULL;
 177   struct cgraph_edge *curr = e;
 178
 179   /* Don't inline inlined edges.  */
 180   gcc_assert (e->inline_failed);
 181   /* Don't even think of inlining inline clone.  */
 182   gcc_assert (!e->callee->global.inlined_to);
 183
 184   e->inline_failed = CIF_OK;
 185   DECL_POSSIBLY_INLINED (e->callee->decl) = true;
 186
 187   to = e->caller;
 188   if (to->global.inlined_to)
 189     to = to->global.inlined_to;
 190   old_size = inline_summary (to)->size;
 191   inline_merge_summary (e);
 192   new_size = inline_summary (to)->size;
 193
 194   clone_inlined_nodes (e, true, update_original, overall_size);
 195
 196   gcc_assert (curr->callee->global.inlined_to == to);
 197   if (overall_size && new_size > old_size)
 198     *overall_size += new_size - old_size;
 199   ncalls_inlined++;
 200
 201   if (flag_indirect_inlining && optimize)
 202     return ipa_propagate_indirect_call_infos (curr, new_edges);
 203   else
 204     return false;
 205 }
 206
 207
 208 /* Copy function body of NODE and redirect all inline clones to it.
 209    This is done before inline plan is applied to NODE when there are
 210    still some inline clones if it.
 211
 212    This is neccesary because inline decisions are not really transitive
 213    and the other inline clones may have different bodies.  */
 214
 215 static struct cgraph_node *
 216 save_inline_function_body (struct cgraph_node *node)
 217 {
 218   struct cgraph_node *first_clone, *n;
 219
 220   if (dump_file)
 221     fprintf (dump_file, "\nSaving body of %s for later reuse\n",
 222              cgraph_node_name (node));
 223
 224   gcc_assert (node == cgraph_get_node (node->decl));
 225
 226   /* first_clone will be turned into real function.  */
 227   first_clone = node->clones;
 228   first_clone->decl = copy_node (node->decl);
 229   cgraph_insert_node_to_hashtable (first_clone);
 230   gcc_assert (first_clone == cgraph_get_node (first_clone->decl));
 231
 232   /* Now reshape the clone tree, so all other clones descends from
 233      first_clone.  */
 234   if (first_clone->next_sibling_clone)
 235     {
 236       for (n = first_clone->next_sibling_clone; n->next_sibling_clone; n = n->next_sibling_clone)
 237         n->clone_of = first_clone;
 238       n->clone_of = first_clone;
 239       n->next_sibling_clone = first_clone->clones;
 240       if (first_clone->clones)
 241         first_clone->clones->prev_sibling_clone = n;
 242       first_clone->clones = first_clone->next_sibling_clone;
 243       first_clone->next_sibling_clone->prev_sibling_clone = NULL;
 244       first_clone->next_sibling_clone = NULL;
 245       gcc_assert (!first_clone->prev_sibling_clone);
 246     }
 247   first_clone->clone_of = NULL;
 248
 249   /* Now node in question has no clones.  */
 250   node->clones = NULL;
 251
 252   /* Inline clones share decl with the function they are cloned
 253      from.  Walk the whole clone tree and redirect them all to the
 254      new decl.  */
 255   if (first_clone->clones)
 256     for (n = first_clone->clones; n != first_clone;)
 257       {
 258         gcc_assert (n->decl == node->decl);
 259         n->decl = first_clone->decl;
 260         if (n->clones)
 261           n = n->clones;
 262         else if (n->next_sibling_clone)
 263           n = n->next_sibling_clone;
 264         else
 265           {
 266             while (n != first_clone && !n->next_sibling_clone)
 267               n = n->clone_of;
 268             if (n != first_clone)
 269               n = n->next_sibling_clone;
 270           }
 271       }
 272
 273   /* Copy the OLD_VERSION_NODE function tree to the new version.  */
 274   tree_function_versioning (node->decl, first_clone->decl, NULL, true, NULL,
 275                             NULL, NULL);
 276
 277   /* The function will be short lived and removed after we inline all the clones,
 278      but make it internal so we won't confuse ourself.  */
 279   DECL_EXTERNAL (first_clone->decl) = 0;
 280   DECL_COMDAT_GROUP (first_clone->decl) = NULL_TREE;
 281   TREE_PUBLIC (first_clone->decl) = 0;
 282   DECL_COMDAT (first_clone->decl) = 0;
 283   VEC_free (ipa_opt_pass, heap,
 284             first_clone->ipa_transforms_to_apply);
 285   first_clone->ipa_transforms_to_apply = NULL;
 286
 287 #ifdef ENABLE_CHECKING
 288   verify_cgraph_node (first_clone);
 289 #endif
 290   return first_clone;
 291 }
 292
 293
 294 /* Apply inline plan to function.  */
 295
 296 unsigned int
 297 inline_transform (struct cgraph_node *node)
 298 {
 299   unsigned int todo = 0;
 300   struct cgraph_edge *e;
 301   bool inline_p = false;
 302
 303   /* FIXME: Currently the pass manager is adding inline transform more than
 304      once to some clones.  This needs revisiting after WPA cleanups.  */
 305   if (cfun->after_inlining)
 306     return 0;
 307
 308   /* We might need the body of this function so that we can expand
 309      it inline somewhere else.  */
 310   if (cgraph_preserve_function_body_p (node->decl))
 311     save_inline_function_body (node);
 312
 313   for (e = node->callees; e; e = e->next_callee)
 314     {
 315       cgraph_redirect_edge_call_stmt_to_callee (e);
 316       if (!e->inline_failed || warn_inline)
 317         inline_p = true;
 318     }
 319
 320   if (inline_p)
 321     {
 322       timevar_push (TV_INTEGRATION);
 323       todo = optimize_inline_calls (current_function_decl);
 324       timevar_pop (TV_INTEGRATION);
 325     }
 326   cfun->always_inline_functions_inlined = true;
 327   cfun->after_inlining = true;
 328   return todo | execute_fixup_cfg ();
 329 }