* doc/extend.texi (Size of an asm): Really move node to its position.
[official-gcc.git] / gcc / ipa-inline-transform.c
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1 /* Callgraph transformations to handle inlining
2 Copyright (C) 2003-2014 Free Software Foundation, Inc.
3 Contributed by Jan Hubicka
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
21 /* The inline decisions are stored in callgraph in "inline plan" and
22 applied later.
24 To mark given call inline, use inline_call function.
25 The function marks the edge inlinable and, if necessary, produces
26 virtual clone in the callgraph representing the new copy of callee's
27 function body.
29 The inline plan is applied on given function body by inline_transform. */
31 #include "config.h"
32 #include "system.h"
33 #include "coretypes.h"
34 #include "tm.h"
35 #include "tree.h"
36 #include "langhooks.h"
37 #include "intl.h"
38 #include "coverage.h"
39 #include "ggc.h"
40 #include "tree-cfg.h"
41 #include "ipa-prop.h"
42 #include "ipa-inline.h"
43 #include "tree-inline.h"
44 #include "tree-pass.h"
46 int ncalls_inlined;
47 int nfunctions_inlined;
48 bool speculation_removed;
50 /* Scale frequency of NODE edges by FREQ_SCALE. */
52 static void
53 update_noncloned_frequencies (struct cgraph_node *node,
54 int freq_scale)
56 struct cgraph_edge *e;
58 /* We do not want to ignore high loop nest after freq drops to 0. */
59 if (!freq_scale)
60 freq_scale = 1;
61 for (e = node->callees; e; e = e->next_callee)
63 e->frequency = e->frequency * (gcov_type) freq_scale / CGRAPH_FREQ_BASE;
64 if (e->frequency > CGRAPH_FREQ_MAX)
65 e->frequency = CGRAPH_FREQ_MAX;
66 if (!e->inline_failed)
67 update_noncloned_frequencies (e->callee, freq_scale);
69 for (e = node->indirect_calls; e; e = e->next_callee)
71 e->frequency = e->frequency * (gcov_type) freq_scale / CGRAPH_FREQ_BASE;
72 if (e->frequency > CGRAPH_FREQ_MAX)
73 e->frequency = CGRAPH_FREQ_MAX;
77 /* We removed or are going to remove the last call to NODE.
78 Return true if we can and want proactively remove the NODE now.
79 This is important to do, since we want inliner to know when offline
80 copy of function was removed. */
82 static bool
83 can_remove_node_now_p_1 (struct cgraph_node *node)
85 /* FIXME: When address is taken of DECL_EXTERNAL function we still
86 can remove its offline copy, but we would need to keep unanalyzed node in
87 the callgraph so references can point to it. */
88 return (!node->address_taken
89 && !ipa_ref_has_aliases_p (&node->ref_list)
90 && !node->used_as_abstract_origin
91 && cgraph_can_remove_if_no_direct_calls_p (node)
92 /* Inlining might enable more devirtualizing, so we want to remove
93 those only after all devirtualizable virtual calls are processed.
94 Lacking may edges in callgraph we just preserve them post
95 inlining. */
96 && !DECL_VIRTUAL_P (node->decl)
97 /* During early inlining some unanalyzed cgraph nodes might be in the
98 callgraph and they might reffer the function in question. */
99 && !cgraph_new_nodes);
102 /* We are going to eliminate last direct call to NODE (or alias of it) via edge E.
103 Verify that the NODE can be removed from unit and if it is contained in comdat
104 group that the whole comdat group is removable. */
106 static bool
107 can_remove_node_now_p (struct cgraph_node *node, struct cgraph_edge *e)
109 struct cgraph_node *next;
110 if (!can_remove_node_now_p_1 (node))
111 return false;
113 /* When we see same comdat group, we need to be sure that all
114 items can be removed. */
115 if (!node->same_comdat_group)
116 return true;
117 for (next = cgraph (node->same_comdat_group);
118 next != node; next = cgraph (next->same_comdat_group))
119 if ((next->callers && next->callers != e)
120 || !can_remove_node_now_p_1 (next))
121 return false;
122 return true;
126 /* E is expected to be an edge being inlined. Clone destination node of
127 the edge and redirect it to the new clone.
128 DUPLICATE is used for bookkeeping on whether we are actually creating new
129 clones or re-using node originally representing out-of-line function call.
130 By default the offline copy is removed, when it appears dead after inlining.
131 UPDATE_ORIGINAL prevents this transformation.
132 If OVERALL_SIZE is non-NULL, the size is updated to reflect the
133 transformation.
134 FREQ_SCALE specify the scaling of frequencies of call sites. */
136 void
137 clone_inlined_nodes (struct cgraph_edge *e, bool duplicate,
138 bool update_original, int *overall_size, int freq_scale)
140 struct cgraph_node *inlining_into;
141 struct cgraph_edge *next;
143 if (e->caller->global.inlined_to)
144 inlining_into = e->caller->global.inlined_to;
145 else
146 inlining_into = e->caller;
148 if (duplicate)
150 /* We may eliminate the need for out-of-line copy to be output.
151 In that case just go ahead and re-use it. This is not just an
152 memory optimization. Making offline copy of fuction disappear
153 from the program will improve future decisions on inlining. */
154 if (!e->callee->callers->next_caller
155 /* Recursive inlining never wants the master clone to
156 be overwritten. */
157 && update_original
158 && can_remove_node_now_p (e->callee, e))
160 /* TODO: When callee is in a comdat group, we could remove all of it,
161 including all inline clones inlined into it. That would however
162 need small function inlining to register edge removal hook to
163 maintain the priority queue.
165 For now we keep the ohter functions in the group in program until
166 cgraph_remove_unreachable_functions gets rid of them. */
167 gcc_assert (!e->callee->global.inlined_to);
168 symtab_dissolve_same_comdat_group_list (e->callee);
169 if (e->callee->definition && !DECL_EXTERNAL (e->callee->decl))
171 if (overall_size)
172 *overall_size -= inline_summary (e->callee)->size;
173 nfunctions_inlined++;
175 duplicate = false;
176 e->callee->externally_visible = false;
177 update_noncloned_frequencies (e->callee, e->frequency);
179 else
181 struct cgraph_node *n;
183 if (freq_scale == -1)
184 freq_scale = e->frequency;
185 n = cgraph_clone_node (e->callee, e->callee->decl,
186 e->count, freq_scale, update_original,
187 vNULL, true, inlining_into, NULL);
188 cgraph_redirect_edge_callee (e, n);
191 else
192 symtab_dissolve_same_comdat_group_list (e->callee);
194 e->callee->global.inlined_to = inlining_into;
196 /* Recursively clone all bodies. */
197 for (e = e->callee->callees; e; e = next)
199 next = e->next_callee;
200 if (!e->inline_failed)
201 clone_inlined_nodes (e, duplicate, update_original, overall_size, freq_scale);
202 if (e->speculative && !speculation_useful_p (e, true))
204 cgraph_resolve_speculation (e, NULL);
205 speculation_removed = true;
211 /* Mark edge E as inlined and update callgraph accordingly. UPDATE_ORIGINAL
212 specify whether profile of original function should be updated. If any new
213 indirect edges are discovered in the process, add them to NEW_EDGES, unless
214 it is NULL. If UPDATE_OVERALL_SUMMARY is false, do not bother to recompute overall
215 size of caller after inlining. Caller is required to eventually do it via
216 inline_update_overall_summary.
218 Return true iff any new callgraph edges were discovered as a
219 result of inlining. */
221 bool
222 inline_call (struct cgraph_edge *e, bool update_original,
223 vec<cgraph_edge_p> *new_edges,
224 int *overall_size, bool update_overall_summary)
226 int old_size = 0, new_size = 0;
227 struct cgraph_node *to = NULL;
228 struct cgraph_edge *curr = e;
229 struct cgraph_node *callee = cgraph_function_or_thunk_node (e->callee, NULL);
230 bool new_edges_found = false;
232 #ifdef ENABLE_CHECKING
233 int estimated_growth = estimate_edge_growth (e);
234 bool predicated = inline_edge_summary (e)->predicate != NULL;
235 #endif
237 speculation_removed = false;
238 /* Don't inline inlined edges. */
239 gcc_assert (e->inline_failed);
240 /* Don't even think of inlining inline clone. */
241 gcc_assert (!callee->global.inlined_to);
243 e->inline_failed = CIF_OK;
244 DECL_POSSIBLY_INLINED (callee->decl) = true;
246 to = e->caller;
247 if (to->global.inlined_to)
248 to = to->global.inlined_to;
250 /* If aliases are involved, redirect edge to the actual destination and
251 possibly remove the aliases. */
252 if (e->callee != callee)
254 struct cgraph_node *alias = e->callee, *next_alias;
255 cgraph_redirect_edge_callee (e, callee);
256 while (alias && alias != callee)
258 if (!alias->callers
259 && can_remove_node_now_p (alias, e))
261 next_alias = cgraph_alias_target (alias);
262 cgraph_remove_node (alias);
263 alias = next_alias;
265 else
266 break;
270 clone_inlined_nodes (e, true, update_original, overall_size, e->frequency);
272 gcc_assert (curr->callee->global.inlined_to == to);
274 old_size = inline_summary (to)->size;
275 inline_merge_summary (e);
276 if (optimize)
277 new_edges_found = ipa_propagate_indirect_call_infos (curr, new_edges);
278 if (update_overall_summary)
279 inline_update_overall_summary (to);
280 new_size = inline_summary (to)->size;
282 if (callee->calls_comdat_local)
283 to->calls_comdat_local = true;
284 else if (to->calls_comdat_local && symtab_comdat_local_p (callee))
286 struct cgraph_edge *se = to->callees;
287 for (; se; se = se->next_callee)
288 if (se->inline_failed && symtab_comdat_local_p (se->callee))
289 break;
290 if (se == NULL)
291 to->calls_comdat_local = false;
294 #ifdef ENABLE_CHECKING
295 /* Verify that estimated growth match real growth. Allow off-by-one
296 error due to INLINE_SIZE_SCALE roudoff errors. */
297 gcc_assert (!update_overall_summary || !overall_size || new_edges_found
298 || abs (estimated_growth - (new_size - old_size)) <= 1
299 || speculation_removed
300 /* FIXME: a hack. Edges with false predicate are accounted
301 wrong, we should remove them from callgraph. */
302 || predicated);
303 #endif
305 /* Account the change of overall unit size; external functions will be
306 removed and are thus not accounted. */
307 if (overall_size
308 && !DECL_EXTERNAL (to->decl))
309 *overall_size += new_size - old_size;
310 ncalls_inlined++;
312 /* This must happen after inline_merge_summary that rely on jump
313 functions of callee to not be updated. */
314 return new_edges_found;
318 /* Copy function body of NODE and redirect all inline clones to it.
319 This is done before inline plan is applied to NODE when there are
320 still some inline clones if it.
322 This is necessary because inline decisions are not really transitive
323 and the other inline clones may have different bodies. */
325 static struct cgraph_node *
326 save_inline_function_body (struct cgraph_node *node)
328 struct cgraph_node *first_clone, *n;
330 if (dump_file)
331 fprintf (dump_file, "\nSaving body of %s for later reuse\n",
332 node->name ());
334 gcc_assert (node == cgraph_get_node (node->decl));
336 /* first_clone will be turned into real function. */
337 first_clone = node->clones;
338 first_clone->decl = copy_node (node->decl);
339 symtab_insert_node_to_hashtable (first_clone);
340 gcc_assert (first_clone == cgraph_get_node (first_clone->decl));
342 /* Now reshape the clone tree, so all other clones descends from
343 first_clone. */
344 if (first_clone->next_sibling_clone)
346 for (n = first_clone->next_sibling_clone; n->next_sibling_clone; n = n->next_sibling_clone)
347 n->clone_of = first_clone;
348 n->clone_of = first_clone;
349 n->next_sibling_clone = first_clone->clones;
350 if (first_clone->clones)
351 first_clone->clones->prev_sibling_clone = n;
352 first_clone->clones = first_clone->next_sibling_clone;
353 first_clone->next_sibling_clone->prev_sibling_clone = NULL;
354 first_clone->next_sibling_clone = NULL;
355 gcc_assert (!first_clone->prev_sibling_clone);
357 first_clone->clone_of = NULL;
359 /* Now node in question has no clones. */
360 node->clones = NULL;
362 /* Inline clones share decl with the function they are cloned
363 from. Walk the whole clone tree and redirect them all to the
364 new decl. */
365 if (first_clone->clones)
366 for (n = first_clone->clones; n != first_clone;)
368 gcc_assert (n->decl == node->decl);
369 n->decl = first_clone->decl;
370 if (n->clones)
371 n = n->clones;
372 else if (n->next_sibling_clone)
373 n = n->next_sibling_clone;
374 else
376 while (n != first_clone && !n->next_sibling_clone)
377 n = n->clone_of;
378 if (n != first_clone)
379 n = n->next_sibling_clone;
383 /* Copy the OLD_VERSION_NODE function tree to the new version. */
384 tree_function_versioning (node->decl, first_clone->decl,
385 NULL, true, NULL, false,
386 NULL, NULL);
388 /* The function will be short lived and removed after we inline all the clones,
389 but make it internal so we won't confuse ourself. */
390 DECL_EXTERNAL (first_clone->decl) = 0;
391 TREE_PUBLIC (first_clone->decl) = 0;
392 DECL_COMDAT (first_clone->decl) = 0;
393 first_clone->ipa_transforms_to_apply.release ();
395 /* When doing recursive inlining, the clone may become unnecessary.
396 This is possible i.e. in the case when the recursive function is proved to be
397 non-throwing and the recursion happens only in the EH landing pad.
398 We can not remove the clone until we are done with saving the body.
399 Remove it now. */
400 if (!first_clone->callers)
402 cgraph_remove_node_and_inline_clones (first_clone, NULL);
403 first_clone = NULL;
405 #ifdef ENABLE_CHECKING
406 else
407 verify_cgraph_node (first_clone);
408 #endif
409 return first_clone;
412 /* Return true when function body of DECL still needs to be kept around
413 for later re-use. */
414 static bool
415 preserve_function_body_p (struct cgraph_node *node)
417 gcc_assert (cgraph_global_info_ready);
418 gcc_assert (!node->alias && !node->thunk.thunk_p);
420 /* Look if there is any clone around. */
421 if (node->clones)
422 return true;
423 return false;
426 /* Apply inline plan to function. */
428 unsigned int
429 inline_transform (struct cgraph_node *node)
431 unsigned int todo = 0;
432 struct cgraph_edge *e, *next;
434 /* FIXME: Currently the pass manager is adding inline transform more than
435 once to some clones. This needs revisiting after WPA cleanups. */
436 if (cfun->after_inlining)
437 return 0;
439 /* We might need the body of this function so that we can expand
440 it inline somewhere else. */
441 if (preserve_function_body_p (node))
442 save_inline_function_body (node);
444 for (e = node->callees; e; e = next)
446 next = e->next_callee;
447 cgraph_redirect_edge_call_stmt_to_callee (e);
449 ipa_remove_all_references (&node->ref_list);
451 timevar_push (TV_INTEGRATION);
452 if (node->callees && optimize)
453 todo = optimize_inline_calls (current_function_decl);
454 timevar_pop (TV_INTEGRATION);
456 cfun->always_inline_functions_inlined = true;
457 cfun->after_inlining = true;
458 todo |= execute_fixup_cfg ();
460 if (!(todo & TODO_update_ssa_any))
461 /* Redirecting edges might lead to a need for vops to be recomputed. */
462 todo |= TODO_update_ssa_only_virtuals;
464 return todo;