2017-10-24 Paolo Carlini <paolo.carlini@oracle.com>
[official-gcc.git] / gcc / lto / lto-partition.c
blob3141ecec07c0efecc30a4cee9abf8ca0c95d0732
1 /* LTO partitioning logic routines.
2 Copyright (C) 2009-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
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 3, or (at your option) any later
9 version.
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.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "target.h"
24 #include "function.h"
25 #include "basic-block.h"
26 #include "tree.h"
27 #include "gimple.h"
28 #include "alloc-pool.h"
29 #include "stringpool.h"
30 #include "cgraph.h"
31 #include "lto-streamer.h"
32 #include "params.h"
33 #include "symbol-summary.h"
34 #include "tree-vrp.h"
35 #include "ipa-prop.h"
36 #include "ipa-fnsummary.h"
37 #include "lto-partition.h"
39 vec<ltrans_partition> ltrans_partitions;
41 static void add_symbol_to_partition (ltrans_partition part, symtab_node *node);
44 /* Create new partition with name NAME. */
46 static ltrans_partition
47 new_partition (const char *name)
49 ltrans_partition part = XCNEW (struct ltrans_partition_def);
50 part->encoder = lto_symtab_encoder_new (false);
51 part->name = name;
52 part->insns = 0;
53 part->symbols = 0;
54 ltrans_partitions.safe_push (part);
55 return part;
58 /* Free memory used by ltrans datastructures. */
60 void
61 free_ltrans_partitions (void)
63 unsigned int idx;
64 ltrans_partition part;
65 for (idx = 0; ltrans_partitions.iterate (idx, &part); idx++)
67 if (part->initializers_visited)
68 delete part->initializers_visited;
69 /* Symtab encoder is freed after streaming. */
70 free (part);
72 ltrans_partitions.release ();
75 /* Return true if symbol is already in some partition. */
77 static inline bool
78 symbol_partitioned_p (symtab_node *node)
80 return node->aux;
83 /* Add references into the partition. */
84 static void
85 add_references_to_partition (ltrans_partition part, symtab_node *node)
87 int i;
88 struct ipa_ref *ref = NULL;
90 /* Add all duplicated references to the partition. */
91 for (i = 0; node->iterate_reference (i, ref); i++)
92 if (ref->referred->get_partitioning_class () == SYMBOL_DUPLICATE)
93 add_symbol_to_partition (part, ref->referred);
94 /* References to a readonly variable may be constant foled into its value.
95 Recursively look into the initializers of the constant variable and add
96 references, too. */
97 else if (is_a <varpool_node *> (ref->referred)
98 && (dyn_cast <varpool_node *> (ref->referred)
99 ->ctor_useable_for_folding_p ()
100 || POINTER_BOUNDS_P (ref->referred->decl))
101 && !lto_symtab_encoder_in_partition_p (part->encoder, ref->referred))
103 if (!part->initializers_visited)
104 part->initializers_visited = new hash_set<symtab_node *>;
105 if (!part->initializers_visited->add (ref->referred))
106 add_references_to_partition (part, ref->referred);
110 /* Helper function for add_symbol_to_partition doing the actual dirty work
111 of adding NODE to PART. */
113 static bool
114 add_symbol_to_partition_1 (ltrans_partition part, symtab_node *node)
116 enum symbol_partitioning_class c = node->get_partitioning_class ();
117 struct ipa_ref *ref;
118 symtab_node *node1;
120 /* If NODE is already there, we have nothing to do. */
121 if (lto_symtab_encoder_in_partition_p (part->encoder, node))
122 return true;
124 /* non-duplicated aliases or tunks of a duplicated symbol needs to be output
125 just once.
127 Be lax about comdats; they may or may not be duplicated and we may
128 end up in need to duplicate keyed comdat because it has unkeyed alias. */
129 if (c == SYMBOL_PARTITION && !DECL_COMDAT (node->decl)
130 && symbol_partitioned_p (node))
131 return false;
133 /* Be sure that we never try to duplicate partitioned symbol
134 or add external symbol. */
135 gcc_assert (c != SYMBOL_EXTERNAL
136 && (c == SYMBOL_DUPLICATE || !symbol_partitioned_p (node)));
138 part->symbols++;
140 lto_set_symtab_encoder_in_partition (part->encoder, node);
142 if (symbol_partitioned_p (node))
144 node->in_other_partition = 1;
145 if (symtab->dump_file)
146 fprintf (symtab->dump_file,
147 "Symbol node %s now used in multiple partitions\n",
148 node->name ());
150 node->aux = (void *)((size_t)node->aux + 1);
152 if (cgraph_node *cnode = dyn_cast <cgraph_node *> (node))
154 struct cgraph_edge *e;
155 if (!node->alias)
156 part->insns += ipa_fn_summaries->get (cnode)->self_size;
158 /* Add all inline clones and callees that are duplicated. */
159 for (e = cnode->callees; e; e = e->next_callee)
160 if (!e->inline_failed)
161 add_symbol_to_partition_1 (part, e->callee);
162 else if (e->callee->get_partitioning_class () == SYMBOL_DUPLICATE)
163 add_symbol_to_partition (part, e->callee);
165 /* Add all thunks associated with the function. */
166 for (e = cnode->callers; e; e = e->next_caller)
167 if (e->caller->thunk.thunk_p && !e->caller->global.inlined_to)
168 add_symbol_to_partition_1 (part, e->caller);
170 /* Instrumented version is actually the same function.
171 Therefore put it into the same partition. */
172 if (cnode->instrumented_version)
173 add_symbol_to_partition_1 (part, cnode->instrumented_version);
176 add_references_to_partition (part, node);
178 /* Add all aliases associated with the symbol. */
180 FOR_EACH_ALIAS (node, ref)
181 if (!ref->referring->transparent_alias)
182 add_symbol_to_partition_1 (part, ref->referring);
183 else
185 struct ipa_ref *ref2;
186 /* We do not need to add transparent aliases if they are not used.
187 However we must add aliases of transparent aliases if they exist. */
188 FOR_EACH_ALIAS (ref->referring, ref2)
190 /* Nested transparent aliases are not permitted. */
191 gcc_checking_assert (!ref2->referring->transparent_alias);
192 add_symbol_to_partition_1 (part, ref2->referring);
196 /* Ensure that SAME_COMDAT_GROUP lists all allways added in a group. */
197 if (node->same_comdat_group)
198 for (node1 = node->same_comdat_group;
199 node1 != node; node1 = node1->same_comdat_group)
200 if (!node->alias)
202 bool added = add_symbol_to_partition_1 (part, node1);
203 gcc_assert (added);
205 return true;
208 /* If symbol NODE is really part of other symbol's definition (i.e. it is
209 internal label, thunk, alias or so), return the outer symbol.
210 When add_symbol_to_partition_1 is called on the outer symbol it must
211 eventually add NODE, too. */
212 static symtab_node *
213 contained_in_symbol (symtab_node *node)
215 /* There is no need to consider transparent aliases to be part of the
216 definition: they are only useful insite the partition they are output
217 and thus we will always see an explicit reference to it. */
218 if (node->transparent_alias)
219 return node;
220 if (cgraph_node *cnode = dyn_cast <cgraph_node *> (node))
222 cnode = cnode->function_symbol ();
223 if (cnode->global.inlined_to)
224 cnode = cnode->global.inlined_to;
225 return cnode;
227 else if (varpool_node *vnode = dyn_cast <varpool_node *> (node))
228 return vnode->ultimate_alias_target ();
229 return node;
232 /* Add symbol NODE to partition. When definition of NODE is part
233 of other symbol definition, add the other symbol, too. */
235 static void
236 add_symbol_to_partition (ltrans_partition part, symtab_node *node)
238 symtab_node *node1;
240 /* Verify that we do not try to duplicate something that can not be. */
241 gcc_checking_assert (node->get_partitioning_class () == SYMBOL_DUPLICATE
242 || !symbol_partitioned_p (node));
244 while ((node1 = contained_in_symbol (node)) != node)
245 node = node1;
247 /* If we have duplicated symbol contained in something we can not duplicate,
248 we are very badly screwed. The other way is possible, so we do not
249 assert this in add_symbol_to_partition_1.
251 Be lax about comdats; they may or may not be duplicated and we may
252 end up in need to duplicate keyed comdat because it has unkeyed alias. */
254 gcc_assert (node->get_partitioning_class () == SYMBOL_DUPLICATE
255 || DECL_COMDAT (node->decl)
256 || !symbol_partitioned_p (node));
258 add_symbol_to_partition_1 (part, node);
261 /* Undo all additions until number of cgraph nodes in PARITION is N_CGRAPH_NODES
262 and number of varpool nodes is N_VARPOOL_NODES. */
264 static void
265 undo_partition (ltrans_partition partition, unsigned int n_nodes)
267 while (lto_symtab_encoder_size (partition->encoder) > (int)n_nodes)
269 symtab_node *node = lto_symtab_encoder_deref (partition->encoder,
270 n_nodes);
271 partition->symbols--;
272 cgraph_node *cnode;
274 /* After UNDO we no longer know what was visited. */
275 if (partition->initializers_visited)
276 delete partition->initializers_visited;
277 partition->initializers_visited = NULL;
279 if (!node->alias && (cnode = dyn_cast <cgraph_node *> (node)))
280 partition->insns -= ipa_fn_summaries->get (cnode)->self_size;
281 lto_symtab_encoder_delete_node (partition->encoder, node);
282 node->aux = (void *)((size_t)node->aux - 1);
286 /* Group cgrah nodes by input files. This is used mainly for testing
287 right now. */
289 void
290 lto_1_to_1_map (void)
292 symtab_node *node;
293 struct lto_file_decl_data *file_data;
294 hash_map<lto_file_decl_data *, ltrans_partition> pmap;
295 ltrans_partition partition;
296 int npartitions = 0;
298 FOR_EACH_SYMBOL (node)
300 if (node->get_partitioning_class () != SYMBOL_PARTITION
301 || symbol_partitioned_p (node))
302 continue;
304 file_data = node->lto_file_data;
306 if (file_data)
308 ltrans_partition *slot = &pmap.get_or_insert (file_data);
309 if (*slot)
310 partition = *slot;
311 else
313 partition = new_partition (file_data->file_name);
314 *slot = partition;
315 npartitions++;
318 else if (!file_data && ltrans_partitions.length ())
319 partition = ltrans_partitions[0];
320 else
322 partition = new_partition ("");
323 pmap.put (NULL, partition);
324 npartitions++;
327 add_symbol_to_partition (partition, node);
330 /* If the cgraph is empty, create one cgraph node set so that there is still
331 an output file for any variables that need to be exported in a DSO. */
332 if (!npartitions)
333 new_partition ("empty");
337 /* Maximal partitioning. Put every new symbol into new partition if possible. */
339 void
340 lto_max_map (void)
342 symtab_node *node;
343 ltrans_partition partition;
344 int npartitions = 0;
346 FOR_EACH_SYMBOL (node)
348 if (node->get_partitioning_class () != SYMBOL_PARTITION
349 || symbol_partitioned_p (node))
350 continue;
351 partition = new_partition (node->asm_name ());
352 add_symbol_to_partition (partition, node);
353 npartitions++;
355 if (!npartitions)
356 new_partition ("empty");
359 /* Helper function for qsort; sort nodes by order. noreorder functions must have
360 been removed earlier. */
361 static int
362 node_cmp (const void *pa, const void *pb)
364 const struct cgraph_node *a = *(const struct cgraph_node * const *) pa;
365 const struct cgraph_node *b = *(const struct cgraph_node * const *) pb;
367 /* Profile reorder flag enables function reordering based on first execution
368 of a function. All functions with profile are placed in ascending
369 order at the beginning. */
371 if (flag_profile_reorder_functions)
373 /* Functions with time profile are sorted in ascending order. */
374 if (a->tp_first_run && b->tp_first_run)
375 return a->tp_first_run != b->tp_first_run
376 ? a->tp_first_run - b->tp_first_run
377 : a->order - b->order;
379 /* Functions with time profile are sorted before the functions
380 that do not have the profile. */
381 if (a->tp_first_run || b->tp_first_run)
382 return b->tp_first_run - a->tp_first_run;
385 return b->order - a->order;
388 /* Helper function for qsort; sort nodes by order. */
389 static int
390 varpool_node_cmp (const void *pa, const void *pb)
392 const symtab_node *a = *static_cast<const symtab_node * const *> (pa);
393 const symtab_node *b = *static_cast<const symtab_node * const *> (pb);
394 return b->order - a->order;
397 /* Add all symtab nodes from NEXT_NODE to PARTITION in order. */
399 static void
400 add_sorted_nodes (vec<symtab_node *> &next_nodes, ltrans_partition partition)
402 unsigned i;
403 symtab_node *node;
405 next_nodes.qsort (varpool_node_cmp);
406 FOR_EACH_VEC_ELT (next_nodes, i, node)
407 if (!symbol_partitioned_p (node))
408 add_symbol_to_partition (partition, node);
412 /* Group cgraph nodes into equally-sized partitions.
414 The partitioning algorithm is simple: nodes are taken in predefined order.
415 The order corresponds to the order we want functions to have in the final
416 output. In the future this will be given by function reordering pass, but
417 at the moment we use the topological order, which is a good approximation.
419 The goal is to partition this linear order into intervals (partitions) so
420 that all the partitions have approximately the same size and the number of
421 callgraph or IPA reference edges crossing boundaries is minimal.
423 This is a lot faster (O(n) in size of callgraph) than algorithms doing
424 priority-based graph clustering that are generally O(n^2) and, since
425 WHOPR is designed to make things go well across partitions, it leads
426 to good results.
428 We compute the expected size of a partition as:
430 max (total_size / lto_partitions, min_partition_size)
432 We use dynamic expected size of partition so small programs are partitioned
433 into enough partitions to allow use of multiple CPUs, while large programs
434 are not partitioned too much. Creating too many partitions significantly
435 increases the streaming overhead.
437 In the future, we would like to bound the maximal size of partitions so as
438 to prevent the LTRANS stage from consuming too much memory. At the moment,
439 however, the WPA stage is the most memory intensive for large benchmarks,
440 since too many types and declarations are read into memory.
442 The function implements a simple greedy algorithm. Nodes are being added
443 to the current partition until after 3/4 of the expected partition size is
444 reached. Past this threshold, we keep track of boundary size (number of
445 edges going to other partitions) and continue adding functions until after
446 the current partition has grown to twice the expected partition size. Then
447 the process is undone to the point where the minimal ratio of boundary size
448 and in-partition calls was reached. */
450 void
451 lto_balanced_map (int n_lto_partitions, int max_partition_size)
453 int n_nodes = 0;
454 int n_varpool_nodes = 0, varpool_pos = 0, best_varpool_pos = 0;
455 struct cgraph_node **order = XNEWVEC (cgraph_node *, symtab->cgraph_max_uid);
456 auto_vec<cgraph_node *> noreorder;
457 auto_vec<varpool_node *> varpool_order;
458 int i;
459 struct cgraph_node *node;
460 int original_total_size, total_size = 0, best_total_size = 0;
461 int partition_size;
462 ltrans_partition partition;
463 int last_visited_node = 0;
464 varpool_node *vnode;
465 int cost = 0, internal = 0;
466 int best_n_nodes = 0, best_i = 0, best_cost =
467 INT_MAX, best_internal = 0;
468 int npartitions;
469 int current_order = -1;
470 int noreorder_pos = 0;
472 FOR_EACH_VARIABLE (vnode)
473 gcc_assert (!vnode->aux);
475 FOR_EACH_DEFINED_FUNCTION (node)
476 if (node->get_partitioning_class () == SYMBOL_PARTITION)
478 if (node->no_reorder)
479 noreorder.safe_push (node);
480 else
481 order[n_nodes++] = node;
482 if (!node->alias)
483 total_size += ipa_fn_summaries->get (node)->size;
486 original_total_size = total_size;
488 /* Streaming works best when the source units do not cross partition
489 boundaries much. This is because importing function from a source
490 unit tends to import a lot of global trees defined there. We should
491 get better about minimizing the function bounday, but until that
492 things works smoother if we order in source order. */
493 qsort (order, n_nodes, sizeof (struct cgraph_node *), node_cmp);
494 noreorder.qsort (node_cmp);
496 if (symtab->dump_file)
498 for(i = 0; i < n_nodes; i++)
499 fprintf (symtab->dump_file, "Balanced map symbol order:%s:%u\n",
500 order[i]->name (), order[i]->tp_first_run);
501 for(i = 0; i < (int)noreorder.length(); i++)
502 fprintf (symtab->dump_file, "Balanced map symbol no_reorder:%s:%u\n",
503 noreorder[i]->name (), noreorder[i]->tp_first_run);
506 /* Collect all variables that should not be reordered. */
507 FOR_EACH_VARIABLE (vnode)
508 if (vnode->get_partitioning_class () == SYMBOL_PARTITION
509 && vnode->no_reorder)
510 varpool_order.safe_push (vnode);
511 n_varpool_nodes = varpool_order.length ();
512 varpool_order.qsort (varpool_node_cmp);
514 /* Compute partition size and create the first partition. */
515 if (PARAM_VALUE (MIN_PARTITION_SIZE) > max_partition_size)
516 fatal_error (input_location, "min partition size cannot be greater than max partition size");
518 partition_size = total_size / n_lto_partitions;
519 if (partition_size < PARAM_VALUE (MIN_PARTITION_SIZE))
520 partition_size = PARAM_VALUE (MIN_PARTITION_SIZE);
521 npartitions = 1;
522 partition = new_partition ("");
523 if (symtab->dump_file)
524 fprintf (symtab->dump_file, "Total unit size: %i, partition size: %i\n",
525 total_size, partition_size);
527 auto_vec<symtab_node *> next_nodes;
529 for (i = 0; i < n_nodes; i++)
531 if (symbol_partitioned_p (order[i]))
532 continue;
534 current_order = order[i]->order;
536 /* Output noreorder and varpool in program order first. */
537 next_nodes.truncate (0);
538 while (varpool_pos < n_varpool_nodes
539 && varpool_order[varpool_pos]->order < current_order)
540 next_nodes.safe_push (varpool_order[varpool_pos++]);
541 while (noreorder_pos < (int)noreorder.length ()
542 && noreorder[noreorder_pos]->order < current_order)
544 if (!noreorder[noreorder_pos]->alias)
545 total_size -= ipa_fn_summaries->get (noreorder[noreorder_pos])->size;
546 next_nodes.safe_push (noreorder[noreorder_pos++]);
548 add_sorted_nodes (next_nodes, partition);
550 if (!symbol_partitioned_p (order[i]))
551 add_symbol_to_partition (partition, order[i]);
552 if (!order[i]->alias)
553 total_size -= ipa_fn_summaries->get (order[i])->size;
556 /* Once we added a new node to the partition, we also want to add
557 all referenced variables unless they was already added into some
558 earlier partition.
559 add_symbol_to_partition adds possibly multiple nodes and
560 variables that are needed to satisfy needs of ORDER[i].
561 We remember last visited cgraph and varpool node from last iteration
562 of outer loop that allows us to process every new addition.
564 At the same time we compute size of the boundary into COST. Every
565 callgraph or IPA reference edge leaving the partition contributes into
566 COST. Every edge inside partition was earlier computed as one leaving
567 it and thus we need to subtract it from COST. */
568 while (last_visited_node < lto_symtab_encoder_size (partition->encoder))
570 symtab_node *refs_node;
571 int j;
572 struct ipa_ref *ref = NULL;
573 symtab_node *snode = lto_symtab_encoder_deref (partition->encoder,
574 last_visited_node);
576 if (cgraph_node *node = dyn_cast <cgraph_node *> (snode))
578 struct cgraph_edge *edge;
580 refs_node = node;
582 last_visited_node++;
584 gcc_assert (node->definition || node->weakref);
586 /* Compute boundary cost of callgraph edges. */
587 for (edge = node->callees; edge; edge = edge->next_callee)
588 if (edge->callee->definition)
590 int edge_cost = edge->frequency;
591 int index;
593 if (!edge_cost)
594 edge_cost = 1;
595 gcc_assert (edge_cost > 0);
596 index = lto_symtab_encoder_lookup (partition->encoder,
597 edge->callee);
598 if (index != LCC_NOT_FOUND
599 && index < last_visited_node - 1)
600 cost -= edge_cost, internal += edge_cost;
601 else
602 cost += edge_cost;
604 for (edge = node->callers; edge; edge = edge->next_caller)
606 int edge_cost = edge->frequency;
607 int index;
609 gcc_assert (edge->caller->definition);
610 if (!edge_cost)
611 edge_cost = 1;
612 gcc_assert (edge_cost > 0);
613 index = lto_symtab_encoder_lookup (partition->encoder,
614 edge->caller);
615 if (index != LCC_NOT_FOUND
616 && index < last_visited_node - 1)
617 cost -= edge_cost;
618 else
619 cost += edge_cost;
622 else
624 refs_node = snode;
625 last_visited_node++;
628 /* Compute boundary cost of IPA REF edges and at the same time look into
629 variables referenced from current partition and try to add them. */
630 for (j = 0; refs_node->iterate_reference (j, ref); j++)
631 if (is_a <varpool_node *> (ref->referred))
633 int index;
635 vnode = dyn_cast <varpool_node *> (ref->referred);
636 if (!vnode->definition)
637 continue;
638 if (!symbol_partitioned_p (vnode)
639 && !vnode->no_reorder
640 && vnode->get_partitioning_class () == SYMBOL_PARTITION)
641 add_symbol_to_partition (partition, vnode);
642 index = lto_symtab_encoder_lookup (partition->encoder,
643 vnode);
644 if (index != LCC_NOT_FOUND
645 && index < last_visited_node - 1)
646 cost--, internal++;
647 else
648 cost++;
650 else
652 int index;
654 node = dyn_cast <cgraph_node *> (ref->referred);
655 if (!node->definition)
656 continue;
657 index = lto_symtab_encoder_lookup (partition->encoder,
658 node);
659 if (index != LCC_NOT_FOUND
660 && index < last_visited_node - 1)
661 cost--, internal++;
662 else
663 cost++;
665 for (j = 0; refs_node->iterate_referring (j, ref); j++)
666 if (is_a <varpool_node *> (ref->referring))
668 int index;
670 vnode = dyn_cast <varpool_node *> (ref->referring);
671 gcc_assert (vnode->definition);
672 /* It is better to couple variables with their users,
673 because it allows them to be removed. Coupling
674 with objects they refer to only helps to reduce
675 number of symbols promoted to hidden. */
676 if (!symbol_partitioned_p (vnode)
677 && !vnode->no_reorder
678 && !vnode->can_remove_if_no_refs_p ()
679 && vnode->get_partitioning_class () == SYMBOL_PARTITION)
680 add_symbol_to_partition (partition, vnode);
681 index = lto_symtab_encoder_lookup (partition->encoder,
682 vnode);
683 if (index != LCC_NOT_FOUND
684 && index < last_visited_node - 1)
685 cost--;
686 else
687 cost++;
689 else
691 int index;
693 node = dyn_cast <cgraph_node *> (ref->referring);
694 gcc_assert (node->definition);
695 index = lto_symtab_encoder_lookup (partition->encoder,
696 node);
697 if (index != LCC_NOT_FOUND
698 && index < last_visited_node - 1)
699 cost--;
700 else
701 cost++;
705 /* If the partition is large enough, start looking for smallest boundary cost. */
706 if (partition->insns < partition_size * 3 / 4
707 || best_cost == INT_MAX
708 || ((!cost
709 || (best_internal * (HOST_WIDE_INT) cost
710 > (internal * (HOST_WIDE_INT)best_cost)))
711 && partition->insns < partition_size * 5 / 4))
713 best_cost = cost;
714 best_internal = internal;
715 best_i = i;
716 best_n_nodes = lto_symtab_encoder_size (partition->encoder);
717 best_total_size = total_size;
718 best_varpool_pos = varpool_pos;
720 if (symtab->dump_file)
721 fprintf (symtab->dump_file, "Step %i: added %s/%i, size %i, cost %i/%i "
722 "best %i/%i, step %i\n", i,
723 order[i]->name (), order[i]->order,
724 partition->insns, cost, internal,
725 best_cost, best_internal, best_i);
726 /* Partition is too large, unwind into step when best cost was reached and
727 start new partition. */
728 if (partition->insns > 2 * partition_size
729 || partition->insns > max_partition_size)
731 if (best_i != i)
733 if (symtab->dump_file)
734 fprintf (symtab->dump_file, "Unwinding %i insertions to step %i\n",
735 i - best_i, best_i);
736 undo_partition (partition, best_n_nodes);
737 varpool_pos = best_varpool_pos;
739 i = best_i;
740 /* When we are finished, avoid creating empty partition. */
741 while (i < n_nodes - 1 && symbol_partitioned_p (order[i + 1]))
742 i++;
743 if (i == n_nodes - 1)
744 break;
745 partition = new_partition ("");
746 last_visited_node = 0;
747 total_size = best_total_size;
748 cost = 0;
750 if (symtab->dump_file)
751 fprintf (symtab->dump_file, "New partition\n");
752 best_n_nodes = 0;
753 best_cost = INT_MAX;
755 /* Since the size of partitions is just approximate, update the size after
756 we finished current one. */
757 if (npartitions < n_lto_partitions)
758 partition_size = total_size / (n_lto_partitions - npartitions);
759 else
760 partition_size = INT_MAX;
762 if (partition_size < PARAM_VALUE (MIN_PARTITION_SIZE))
763 partition_size = PARAM_VALUE (MIN_PARTITION_SIZE);
764 npartitions ++;
768 next_nodes.truncate (0);
770 /* Varables that are not reachable from the code go into last partition. */
771 FOR_EACH_VARIABLE (vnode)
772 if (vnode->get_partitioning_class () == SYMBOL_PARTITION
773 && !symbol_partitioned_p (vnode))
774 next_nodes.safe_push (vnode);
776 /* Output remaining ordered symbols. */
777 while (varpool_pos < n_varpool_nodes)
778 next_nodes.safe_push (varpool_order[varpool_pos++]);
779 while (noreorder_pos < (int)noreorder.length ())
780 next_nodes.safe_push (noreorder[noreorder_pos++]);
781 add_sorted_nodes (next_nodes, partition);
783 free (order);
785 if (symtab->dump_file)
787 fprintf (symtab->dump_file, "\nPartition sizes:\n");
788 unsigned partitions = ltrans_partitions.length ();
790 for (unsigned i = 0; i < partitions ; i++)
792 ltrans_partition p = ltrans_partitions[i];
793 fprintf (symtab->dump_file, "partition %d contains %d (%2.2f%%)"
794 " symbols and %d (%2.2f%%) insns\n", i, p->symbols,
795 100.0 * p->symbols / n_nodes, p->insns,
796 100.0 * p->insns / original_total_size);
799 fprintf (symtab->dump_file, "\n");
803 /* Return true if we must not change the name of the NODE. The name as
804 extracted from the corresponding decl should be passed in NAME. */
806 static bool
807 must_not_rename (symtab_node *node, const char *name)
809 /* Our renaming machinery do not handle more than one change of assembler name.
810 We should not need more than one anyway. */
811 if (node->lto_file_data
812 && lto_get_decl_name_mapping (node->lto_file_data, name) != name)
814 if (symtab->dump_file)
815 fprintf (symtab->dump_file,
816 "Not privatizing symbol name: %s. It privatized already.\n",
817 name);
818 return true;
820 /* Avoid mangling of already mangled clones.
821 ??? should have a flag whether a symbol has a 'private' name already,
822 since we produce some symbols like that i.e. for global constructors
823 that are not really clones. */
824 if (node->unique_name)
826 if (symtab->dump_file)
827 fprintf (symtab->dump_file,
828 "Not privatizing symbol name: %s. Has unique name.\n",
829 name);
830 return true;
832 return false;
835 /* If we are an offload compiler, we may have to rewrite symbols to be
836 valid on this target. Return either PTR or a modified version of it. */
838 static const char *
839 maybe_rewrite_identifier (const char *ptr)
841 #if defined ACCEL_COMPILER && (defined NO_DOT_IN_LABEL || defined NO_DOLLAR_IN_LABEL)
842 #ifndef NO_DOT_IN_LABEL
843 char valid = '.';
844 const char reject[] = "$";
845 #elif !defined NO_DOLLAR_IN_LABEL
846 char valid = '$';
847 const char reject[] = ".";
848 #else
849 char valid = '_';
850 const char reject[] = ".$";
851 #endif
853 char *copy = NULL;
854 const char *match = ptr;
855 for (;;)
857 size_t off = strcspn (match, reject);
858 if (match[off] == '\0')
859 break;
860 if (copy == NULL)
862 copy = xstrdup (ptr);
863 match = copy;
865 copy[off] = valid;
867 return match;
868 #else
869 return ptr;
870 #endif
873 /* Ensure that the symbol in NODE is valid for the target, and if not,
874 rewrite it. */
876 static void
877 validize_symbol_for_target (symtab_node *node)
879 tree decl = node->decl;
880 const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
882 if (must_not_rename (node, name))
883 return;
885 const char *name2 = maybe_rewrite_identifier (name);
886 if (name2 != name)
888 symtab->change_decl_assembler_name (decl, get_identifier (name2));
889 if (node->lto_file_data)
890 lto_record_renamed_decl (node->lto_file_data, name,
891 IDENTIFIER_POINTER
892 (DECL_ASSEMBLER_NAME (decl)));
896 /* Helper for privatize_symbol_name. Mangle NODE symbol name
897 represented by DECL. */
899 static bool
900 privatize_symbol_name_1 (symtab_node *node, tree decl)
902 const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
904 if (must_not_rename (node, name))
905 return false;
907 name = maybe_rewrite_identifier (name);
908 symtab->change_decl_assembler_name (decl,
909 clone_function_name_1 (name,
910 "lto_priv"));
912 if (node->lto_file_data)
913 lto_record_renamed_decl (node->lto_file_data, name,
914 IDENTIFIER_POINTER
915 (DECL_ASSEMBLER_NAME (decl)));
917 if (symtab->dump_file)
918 fprintf (symtab->dump_file,
919 "Privatizing symbol name: %s -> %s\n",
920 name, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)));
922 return true;
925 /* Mangle NODE symbol name into a local name.
926 This is necessary to do
927 1) if two or more static vars of same assembler name
928 are merged into single ltrans unit.
929 2) if previously static var was promoted hidden to avoid possible conflict
930 with symbols defined out of the LTO world. */
932 static bool
933 privatize_symbol_name (symtab_node *node)
935 if (!privatize_symbol_name_1 (node, node->decl))
936 return false;
938 /* We could change name which is a target of transparent alias
939 chain of instrumented function name. Fix alias chain if so .*/
940 if (cgraph_node *cnode = dyn_cast <cgraph_node *> (node))
942 tree iname = NULL_TREE;
943 if (cnode->instrumentation_clone)
945 /* If we want to privatize instrumentation clone
946 then we also need to privatize original function. */
947 if (cnode->instrumented_version)
948 privatize_symbol_name (cnode->instrumented_version);
949 else
950 privatize_symbol_name_1 (cnode, cnode->orig_decl);
951 iname = DECL_ASSEMBLER_NAME (cnode->decl);
952 TREE_CHAIN (iname) = DECL_ASSEMBLER_NAME (cnode->orig_decl);
954 else if (cnode->instrumented_version
955 && cnode->instrumented_version->orig_decl == cnode->decl)
957 iname = DECL_ASSEMBLER_NAME (cnode->instrumented_version->decl);
958 TREE_CHAIN (iname) = DECL_ASSEMBLER_NAME (cnode->decl);
962 return true;
965 /* Promote variable VNODE to be static. */
967 static void
968 promote_symbol (symtab_node *node)
970 /* We already promoted ... */
971 if (DECL_VISIBILITY (node->decl) == VISIBILITY_HIDDEN
972 && DECL_VISIBILITY_SPECIFIED (node->decl)
973 && TREE_PUBLIC (node->decl))
975 validize_symbol_for_target (node);
976 return;
979 gcc_checking_assert (!TREE_PUBLIC (node->decl)
980 && !DECL_EXTERNAL (node->decl));
981 /* Be sure that newly public symbol does not conflict with anything already
982 defined by the non-LTO part. */
983 privatize_symbol_name (node);
984 TREE_PUBLIC (node->decl) = 1;
985 DECL_VISIBILITY (node->decl) = VISIBILITY_HIDDEN;
986 DECL_VISIBILITY_SPECIFIED (node->decl) = true;
987 if (symtab->dump_file)
988 fprintf (symtab->dump_file,
989 "Promoting as hidden: %s (%s)\n", node->name (),
990 IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl)));
992 /* Promoting a symbol also promotes all transparent aliases with exception
993 of weakref where the visibility flags are always wrong and set to
994 !PUBLIC. */
995 ipa_ref *ref;
996 for (unsigned i = 0; node->iterate_direct_aliases (i, ref); i++)
998 struct symtab_node *alias = ref->referring;
999 if (alias->transparent_alias && !alias->weakref)
1001 TREE_PUBLIC (alias->decl) = 1;
1002 DECL_VISIBILITY (alias->decl) = VISIBILITY_HIDDEN;
1003 DECL_VISIBILITY_SPECIFIED (alias->decl) = true;
1004 if (symtab->dump_file)
1005 fprintf (symtab->dump_file,
1006 "Promoting alias as hidden: %s\n",
1007 IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl)));
1009 gcc_assert (!alias->weakref || TREE_PUBLIC (alias->decl));
1013 /* Return true if NODE needs named section even if it won't land in
1014 the partition symbol table.
1016 FIXME: we should really not use named sections for inline clones
1017 and master clones. */
1019 static bool
1020 may_need_named_section_p (lto_symtab_encoder_t encoder, symtab_node *node)
1022 struct cgraph_node *cnode = dyn_cast <cgraph_node *> (node);
1023 if (!cnode)
1024 return false;
1025 if (node->real_symbol_p ())
1026 return false;
1027 return (!encoder
1028 || (lto_symtab_encoder_lookup (encoder, node) != LCC_NOT_FOUND
1029 && lto_symtab_encoder_encode_body_p (encoder,
1030 cnode)));
1033 /* If NODE represents a static variable. See if there are other variables
1034 of the same name in partition ENCODER (or in whole compilation unit if
1035 ENCODER is NULL) and if so, mangle the statics. Always mangle all
1036 conflicting statics, so we reduce changes of silently miscompiling
1037 asm statements referring to them by symbol name. */
1039 static void
1040 rename_statics (lto_symtab_encoder_t encoder, symtab_node *node)
1042 tree decl = node->decl;
1043 symtab_node *s;
1044 tree name = DECL_ASSEMBLER_NAME (decl);
1046 /* See if this is static symbol. */
1047 if (((node->externally_visible && !node->weakref)
1048 /* FIXME: externally_visible is somewhat illogically not set for
1049 external symbols (i.e. those not defined). Remove this test
1050 once this is fixed. */
1051 || DECL_EXTERNAL (node->decl)
1052 || !node->real_symbol_p ())
1053 && !may_need_named_section_p (encoder, node))
1054 return;
1056 /* Now walk symbols sharing the same name and see if there are any conflicts.
1057 (all types of symbols counts here, since we can not have static of the
1058 same name as external or public symbol.) */
1059 for (s = symtab_node::get_for_asmname (name);
1060 s; s = s->next_sharing_asm_name)
1061 if ((s->real_symbol_p () || may_need_named_section_p (encoder, s))
1062 && s->decl != node->decl
1063 && (!encoder
1064 || lto_symtab_encoder_lookup (encoder, s) != LCC_NOT_FOUND))
1065 break;
1067 /* OK, no confict, so we have nothing to do. */
1068 if (!s)
1069 return;
1071 if (symtab->dump_file)
1072 fprintf (symtab->dump_file,
1073 "Renaming statics with asm name: %s\n", node->name ());
1075 /* Assign every symbol in the set that shares the same ASM name an unique
1076 mangled name. */
1077 for (s = symtab_node::get_for_asmname (name); s;)
1078 if ((!s->externally_visible || s->weakref)
1079 /* Transparent aliases having same name as target are renamed at a
1080 time their target gets new name. Transparent aliases that use
1081 separate assembler name require the name to be unique. */
1082 && (!s->transparent_alias || !s->definition || s->weakref
1083 || !symbol_table::assembler_names_equal_p
1084 (IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (s->decl)),
1085 IDENTIFIER_POINTER
1086 (DECL_ASSEMBLER_NAME (s->get_alias_target()->decl))))
1087 && ((s->real_symbol_p ()
1088 && !DECL_EXTERNAL (s->decl)
1089 && !TREE_PUBLIC (s->decl))
1090 || may_need_named_section_p (encoder, s))
1091 && (!encoder
1092 || lto_symtab_encoder_lookup (encoder, s) != LCC_NOT_FOUND))
1094 if (privatize_symbol_name (s))
1095 /* Re-start from beginning since we do not know how many
1096 symbols changed a name. */
1097 s = symtab_node::get_for_asmname (name);
1098 else s = s->next_sharing_asm_name;
1100 else s = s->next_sharing_asm_name;
1103 /* Find out all static decls that need to be promoted to global because
1104 of cross file sharing. This function must be run in the WPA mode after
1105 all inlinees are added. */
1107 void
1108 lto_promote_cross_file_statics (void)
1110 unsigned i, n_sets;
1112 gcc_assert (flag_wpa);
1114 lto_stream_offload_p = false;
1115 select_what_to_stream ();
1117 /* First compute boundaries. */
1118 n_sets = ltrans_partitions.length ();
1119 for (i = 0; i < n_sets; i++)
1121 ltrans_partition part
1122 = ltrans_partitions[i];
1123 part->encoder = compute_ltrans_boundary (part->encoder);
1126 /* Look at boundaries and promote symbols as needed. */
1127 for (i = 0; i < n_sets; i++)
1129 lto_symtab_encoder_iterator lsei;
1130 lto_symtab_encoder_t encoder = ltrans_partitions[i]->encoder;
1132 for (lsei = lsei_start (encoder); !lsei_end_p (lsei);
1133 lsei_next (&lsei))
1135 symtab_node *node = lsei_node (lsei);
1137 /* If symbol is static, rename it if its assembler name
1138 clashes with anything else in this unit. */
1139 rename_statics (encoder, node);
1141 /* No need to promote if symbol already is externally visible ... */
1142 if (node->externally_visible
1143 /* ... or if it is part of current partition ... */
1144 || lto_symtab_encoder_in_partition_p (encoder, node)
1145 /* ... or if we do not partition it. This mean that it will
1146 appear in every partition referencing it. */
1147 || node->get_partitioning_class () != SYMBOL_PARTITION)
1149 validize_symbol_for_target (node);
1150 continue;
1153 promote_symbol (node);
1158 /* Rename statics in the whole unit in the case that
1159 we do -flto-partition=none. */
1161 void
1162 lto_promote_statics_nonwpa (void)
1164 symtab_node *node;
1165 FOR_EACH_SYMBOL (node)
1167 rename_statics (NULL, node);
1168 validize_symbol_for_target (node);