1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
|
/* LTO partitioning logic routines.
Copyright (C) 2009-2020 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "target.h"
#include "function.h"
#include "basic-block.h"
#include "tree.h"
#include "gimple.h"
#include "alloc-pool.h"
#include "stringpool.h"
#include "cgraph.h"
#include "lto-streamer.h"
#include "symbol-summary.h"
#include "tree-vrp.h"
#include "ipa-prop.h"
#include "ipa-fnsummary.h"
#include "lto-partition.h"
#include "sreal.h"
vec<ltrans_partition> ltrans_partitions;
static void add_symbol_to_partition (ltrans_partition part, symtab_node *node);
/* Helper for qsort; compare partitions and return one with smaller order. */
static int
cmp_partitions_order (const void *a, const void *b)
{
const struct ltrans_partition_def *pa
= *(struct ltrans_partition_def *const *)a;
const struct ltrans_partition_def *pb
= *(struct ltrans_partition_def *const *)b;
int ordera = -1, orderb = -1;
if (lto_symtab_encoder_size (pa->encoder))
ordera = lto_symtab_encoder_deref (pa->encoder, 0)->order;
if (lto_symtab_encoder_size (pb->encoder))
orderb = lto_symtab_encoder_deref (pb->encoder, 0)->order;
return orderb - ordera;
}
/* Create new partition with name NAME. */
static ltrans_partition
new_partition (const char *name)
{
ltrans_partition part = XCNEW (struct ltrans_partition_def);
part->encoder = lto_symtab_encoder_new (false);
part->name = name;
part->insns = 0;
part->symbols = 0;
ltrans_partitions.safe_push (part);
return part;
}
/* Free memory used by ltrans datastructures. */
void
free_ltrans_partitions (void)
{
unsigned int idx;
ltrans_partition part;
for (idx = 0; ltrans_partitions.iterate (idx, &part); idx++)
{
if (part->initializers_visited)
delete part->initializers_visited;
/* Symtab encoder is freed after streaming. */
free (part);
}
ltrans_partitions.release ();
}
/* Return true if symbol is already in some partition. */
static inline bool
symbol_partitioned_p (symtab_node *node)
{
return node->aux;
}
/* Add references into the partition. */
static void
add_references_to_partition (ltrans_partition part, symtab_node *node)
{
int i;
struct ipa_ref *ref = NULL;
/* Add all duplicated references to the partition. */
for (i = 0; node->iterate_reference (i, ref); i++)
if (ref->referred->get_partitioning_class () == SYMBOL_DUPLICATE)
add_symbol_to_partition (part, ref->referred);
/* References to a readonly variable may be constant foled into its value.
Recursively look into the initializers of the constant variable and add
references, too. */
else if (is_a <varpool_node *> (ref->referred)
&& (dyn_cast <varpool_node *> (ref->referred)
->ctor_useable_for_folding_p ())
&& !lto_symtab_encoder_in_partition_p (part->encoder, ref->referred))
{
if (!part->initializers_visited)
part->initializers_visited = new hash_set<symtab_node *>;
if (!part->initializers_visited->add (ref->referred))
add_references_to_partition (part, ref->referred);
}
}
/* Helper function for add_symbol_to_partition doing the actual dirty work
of adding NODE to PART. */
static bool
add_symbol_to_partition_1 (ltrans_partition part, symtab_node *node)
{
enum symbol_partitioning_class c = node->get_partitioning_class ();
struct ipa_ref *ref;
symtab_node *node1;
/* If NODE is already there, we have nothing to do. */
if (lto_symtab_encoder_in_partition_p (part->encoder, node))
return true;
/* non-duplicated aliases or tunks of a duplicated symbol needs to be output
just once.
Be lax about comdats; they may or may not be duplicated and we may
end up in need to duplicate keyed comdat because it has unkeyed alias. */
if (c == SYMBOL_PARTITION && !DECL_COMDAT (node->decl)
&& symbol_partitioned_p (node))
return false;
/* Be sure that we never try to duplicate partitioned symbol
or add external symbol. */
gcc_assert (c != SYMBOL_EXTERNAL
&& (c == SYMBOL_DUPLICATE || !symbol_partitioned_p (node)));
part->symbols++;
lto_set_symtab_encoder_in_partition (part->encoder, node);
if (symbol_partitioned_p (node))
{
node->in_other_partition = 1;
if (dump_file)
fprintf (dump_file,
"Symbol node %s now used in multiple partitions\n",
node->name ());
}
node->aux = (void *)((size_t)node->aux + 1);
if (cgraph_node *cnode = dyn_cast <cgraph_node *> (node))
{
struct cgraph_edge *e;
if (!node->alias && c == SYMBOL_PARTITION)
part->insns += ipa_size_summaries->get (cnode)->size;
/* Add all inline clones and callees that are duplicated. */
for (e = cnode->callees; e; e = e->next_callee)
if (!e->inline_failed)
add_symbol_to_partition_1 (part, e->callee);
else if (e->callee->get_partitioning_class () == SYMBOL_DUPLICATE)
add_symbol_to_partition (part, e->callee);
/* Add all thunks associated with the function. */
for (e = cnode->callers; e; e = e->next_caller)
if (e->caller->thunk.thunk_p && !e->caller->inlined_to)
add_symbol_to_partition_1 (part, e->caller);
}
add_references_to_partition (part, node);
/* Add all aliases associated with the symbol. */
FOR_EACH_ALIAS (node, ref)
if (!ref->referring->transparent_alias)
add_symbol_to_partition_1 (part, ref->referring);
else
{
struct ipa_ref *ref2;
/* We do not need to add transparent aliases if they are not used.
However we must add aliases of transparent aliases if they exist. */
FOR_EACH_ALIAS (ref->referring, ref2)
{
/* Nested transparent aliases are not permitted. */
gcc_checking_assert (!ref2->referring->transparent_alias);
add_symbol_to_partition_1 (part, ref2->referring);
}
}
/* Ensure that SAME_COMDAT_GROUP lists all allways added in a group. */
if (node->same_comdat_group)
for (node1 = node->same_comdat_group;
node1 != node; node1 = node1->same_comdat_group)
if (!node->alias)
{
bool added = add_symbol_to_partition_1 (part, node1);
gcc_assert (added);
}
return true;
}
/* If symbol NODE is really part of other symbol's definition (i.e. it is
internal label, thunk, alias or so), return the outer symbol.
When add_symbol_to_partition_1 is called on the outer symbol it must
eventually add NODE, too. */
static symtab_node *
contained_in_symbol (symtab_node *node)
{
/* There is no need to consider transparent aliases to be part of the
definition: they are only useful insite the partition they are output
and thus we will always see an explicit reference to it. */
if (node->transparent_alias)
return node;
if (cgraph_node *cnode = dyn_cast <cgraph_node *> (node))
{
cnode = cnode->function_symbol ();
if (cnode->inlined_to)
cnode = cnode->inlined_to;
return cnode;
}
else if (varpool_node *vnode = dyn_cast <varpool_node *> (node))
return vnode->ultimate_alias_target ();
return node;
}
/* Add symbol NODE to partition. When definition of NODE is part
of other symbol definition, add the other symbol, too. */
static void
add_symbol_to_partition (ltrans_partition part, symtab_node *node)
{
symtab_node *node1;
/* Verify that we do not try to duplicate something that cannot be. */
gcc_checking_assert (node->get_partitioning_class () == SYMBOL_DUPLICATE
|| !symbol_partitioned_p (node));
while ((node1 = contained_in_symbol (node)) != node)
node = node1;
/* If we have duplicated symbol contained in something we cannot duplicate,
we are very badly screwed. The other way is possible, so we do not
assert this in add_symbol_to_partition_1.
Be lax about comdats; they may or may not be duplicated and we may
end up in need to duplicate keyed comdat because it has unkeyed alias. */
gcc_assert (node->get_partitioning_class () == SYMBOL_DUPLICATE
|| DECL_COMDAT (node->decl)
|| !symbol_partitioned_p (node));
add_symbol_to_partition_1 (part, node);
}
/* Undo all additions until number of cgraph nodes in PARITION is N_CGRAPH_NODES
and number of varpool nodes is N_VARPOOL_NODES. */
static void
undo_partition (ltrans_partition partition, unsigned int n_nodes)
{
while (lto_symtab_encoder_size (partition->encoder) > (int)n_nodes)
{
symtab_node *node = lto_symtab_encoder_deref (partition->encoder,
n_nodes);
partition->symbols--;
cgraph_node *cnode;
/* After UNDO we no longer know what was visited. */
if (partition->initializers_visited)
delete partition->initializers_visited;
partition->initializers_visited = NULL;
if (!node->alias && (cnode = dyn_cast <cgraph_node *> (node))
&& node->get_partitioning_class () == SYMBOL_PARTITION)
partition->insns -= ipa_size_summaries->get (cnode)->size;
lto_symtab_encoder_delete_node (partition->encoder, node);
node->aux = (void *)((size_t)node->aux - 1);
}
}
/* Group cgrah nodes by input files. This is used mainly for testing
right now. */
void
lto_1_to_1_map (void)
{
symtab_node *node;
struct lto_file_decl_data *file_data;
hash_map<lto_file_decl_data *, ltrans_partition> pmap;
ltrans_partition partition;
int npartitions = 0;
FOR_EACH_SYMBOL (node)
{
if (node->get_partitioning_class () != SYMBOL_PARTITION
|| symbol_partitioned_p (node))
continue;
file_data = node->lto_file_data;
if (file_data)
{
ltrans_partition *slot = &pmap.get_or_insert (file_data);
if (*slot)
partition = *slot;
else
{
partition = new_partition (file_data->file_name);
*slot = partition;
npartitions++;
}
}
else if (!file_data && ltrans_partitions.length ())
partition = ltrans_partitions[0];
else
{
partition = new_partition ("");
pmap.put (NULL, partition);
npartitions++;
}
add_symbol_to_partition (partition, node);
}
/* If the cgraph is empty, create one cgraph node set so that there is still
an output file for any variables that need to be exported in a DSO. */
if (!npartitions)
new_partition ("empty");
/* Order partitions by order of symbols because they are linked into binary
that way. */
ltrans_partitions.qsort (cmp_partitions_order);
}
/* Maximal partitioning. Put every new symbol into new partition if possible. */
void
lto_max_map (void)
{
symtab_node *node;
ltrans_partition partition;
int npartitions = 0;
FOR_EACH_SYMBOL (node)
{
if (node->get_partitioning_class () != SYMBOL_PARTITION
|| symbol_partitioned_p (node))
continue;
partition = new_partition (node->asm_name ());
add_symbol_to_partition (partition, node);
npartitions++;
}
if (!npartitions)
new_partition ("empty");
}
/* Helper function for qsort; sort nodes by order. */
static int
node_cmp (const void *pa, const void *pb)
{
const symtab_node *a = *static_cast<const symtab_node * const *> (pa);
const symtab_node *b = *static_cast<const symtab_node * const *> (pb);
return b->order - a->order;
}
/* Add all symtab nodes from NEXT_NODE to PARTITION in order. */
static void
add_sorted_nodes (vec<symtab_node *> &next_nodes, ltrans_partition partition)
{
unsigned i;
symtab_node *node;
next_nodes.qsort (node_cmp);
FOR_EACH_VEC_ELT (next_nodes, i, node)
if (!symbol_partitioned_p (node))
add_symbol_to_partition (partition, node);
}
/* Return true if we should account reference from N1 to N2 in cost
of partition boundary. */
bool
account_reference_p (symtab_node *n1, symtab_node *n2)
{
if (cgraph_node *cnode = dyn_cast <cgraph_node *> (n1))
n1 = cnode;
/* Do not account references from aliases - they are never split across
partitions. */
if (n1->alias)
return false;
/* Do not account recursion - the code below will handle it incorrectly
otherwise. Do not account references to external symbols: they will
never become local. Finally do not account references to duplicated
symbols: they will be always local. */
if (n1 == n2
|| !n2->definition
|| n2->get_partitioning_class () != SYMBOL_PARTITION)
return false;
/* If referring node is external symbol do not account it to boundary
cost. Those are added into units only to enable possible constant
folding and devirtulization.
Here we do not know if it will ever be added to some partition
(this is decided by compute_ltrans_boundary) and second it is not
that likely that constant folding will actually use the reference. */
if (contained_in_symbol (n1)
->get_partitioning_class () == SYMBOL_EXTERNAL)
return false;
return true;
}
/* Group cgraph nodes into equally-sized partitions.
The partitioning algorithm is simple: nodes are taken in predefined order.
The order corresponds to the order we want functions to have in the final
output. In the future this will be given by function reordering pass, but
at the moment we use the topological order, which is a good approximation.
The goal is to partition this linear order into intervals (partitions) so
that all the partitions have approximately the same size and the number of
callgraph or IPA reference edges crossing boundaries is minimal.
This is a lot faster (O(n) in size of callgraph) than algorithms doing
priority-based graph clustering that are generally O(n^2) and, since
WHOPR is designed to make things go well across partitions, it leads
to good results.
We compute the expected size of a partition as:
max (total_size / lto_partitions, min_partition_size)
We use dynamic expected size of partition so small programs are partitioned
into enough partitions to allow use of multiple CPUs, while large programs
are not partitioned too much. Creating too many partitions significantly
increases the streaming overhead.
In the future, we would like to bound the maximal size of partitions so as
to prevent the LTRANS stage from consuming too much memory. At the moment,
however, the WPA stage is the most memory intensive for large benchmarks,
since too many types and declarations are read into memory.
The function implements a simple greedy algorithm. Nodes are being added
to the current partition until after 3/4 of the expected partition size is
reached. Past this threshold, we keep track of boundary size (number of
edges going to other partitions) and continue adding functions until after
the current partition has grown to twice the expected partition size. Then
the process is undone to the point where the minimal ratio of boundary size
and in-partition calls was reached. */
void
lto_balanced_map (int n_lto_partitions, int max_partition_size)
{
int n_varpool_nodes = 0, varpool_pos = 0, best_varpool_pos = 0;
auto_vec <cgraph_node *> order (symtab->cgraph_count);
auto_vec<cgraph_node *> noreorder;
auto_vec<varpool_node *> varpool_order;
struct cgraph_node *node;
int64_t original_total_size, total_size = 0;
int64_t partition_size;
ltrans_partition partition;
int last_visited_node = 0;
varpool_node *vnode;
int64_t cost = 0, internal = 0;
unsigned int best_n_nodes = 0, best_i = 0;
int64_t best_cost = -1, best_internal = 0, best_size = 0;
int npartitions;
int current_order = -1;
int noreorder_pos = 0;
FOR_EACH_VARIABLE (vnode)
gcc_assert (!vnode->aux);
FOR_EACH_DEFINED_FUNCTION (node)
if (node->get_partitioning_class () == SYMBOL_PARTITION)
{
if (node->no_reorder)
noreorder.safe_push (node);
else
order.safe_push (node);
if (!node->alias)
total_size += ipa_size_summaries->get (node)->size;
}
original_total_size = total_size;
/* Streaming works best when the source units do not cross partition
boundaries much. This is because importing function from a source
unit tends to import a lot of global trees defined there. We should
get better about minimizing the function bounday, but until that
things works smoother if we order in source order. */
order.qsort (tp_first_run_node_cmp);
noreorder.qsort (node_cmp);
if (dump_file)
{
for (unsigned i = 0; i < order.length (); i++)
fprintf (dump_file, "Balanced map symbol order:%s:%u\n",
order[i]->name (), order[i]->tp_first_run);
for (unsigned i = 0; i < noreorder.length (); i++)
fprintf (dump_file, "Balanced map symbol no_reorder:%s:%u\n",
noreorder[i]->name (), noreorder[i]->tp_first_run);
}
/* Collect all variables that should not be reordered. */
FOR_EACH_VARIABLE (vnode)
if (vnode->get_partitioning_class () == SYMBOL_PARTITION
&& vnode->no_reorder)
varpool_order.safe_push (vnode);
n_varpool_nodes = varpool_order.length ();
varpool_order.qsort (node_cmp);
/* Compute partition size and create the first partition. */
if (param_min_partition_size > max_partition_size)
fatal_error (input_location, "min partition size cannot be greater "
"than max partition size");
partition_size = total_size / n_lto_partitions;
if (partition_size < param_min_partition_size)
partition_size = param_min_partition_size;
npartitions = 1;
partition = new_partition ("");
if (dump_file)
fprintf (dump_file, "Total unit size: %" PRId64 ", partition size: %" PRId64 "\n",
total_size, partition_size);
auto_vec<symtab_node *> next_nodes;
for (unsigned i = 0; i < order.length (); i++)
{
if (symbol_partitioned_p (order[i]))
continue;
current_order = order[i]->order;
/* Output noreorder and varpool in program order first. */
next_nodes.truncate (0);
while (varpool_pos < n_varpool_nodes
&& varpool_order[varpool_pos]->order < current_order)
next_nodes.safe_push (varpool_order[varpool_pos++]);
while (noreorder_pos < (int)noreorder.length ()
&& noreorder[noreorder_pos]->order < current_order)
next_nodes.safe_push (noreorder[noreorder_pos++]);
add_sorted_nodes (next_nodes, partition);
if (!symbol_partitioned_p (order[i]))
add_symbol_to_partition (partition, order[i]);
/* Once we added a new node to the partition, we also want to add
all referenced variables unless they was already added into some
earlier partition.
add_symbol_to_partition adds possibly multiple nodes and
variables that are needed to satisfy needs of ORDER[i].
We remember last visited cgraph and varpool node from last iteration
of outer loop that allows us to process every new addition.
At the same time we compute size of the boundary into COST. Every
callgraph or IPA reference edge leaving the partition contributes into
COST. Every edge inside partition was earlier computed as one leaving
it and thus we need to subtract it from COST. */
while (last_visited_node < lto_symtab_encoder_size (partition->encoder))
{
int j;
struct ipa_ref *ref = NULL;
symtab_node *snode = lto_symtab_encoder_deref (partition->encoder,
last_visited_node);
if (cgraph_node *node = dyn_cast <cgraph_node *> (snode))
{
struct cgraph_edge *edge;
last_visited_node++;
gcc_assert (node->definition || node->weakref);
/* Compute boundary cost of callgraph edges. */
for (edge = node->callees; edge; edge = edge->next_callee)
/* Inline edges will always end up local. */
if (edge->inline_failed
&& account_reference_p (node, edge->callee))
{
int edge_cost = edge->frequency ();
int index;
if (!edge_cost)
edge_cost = 1;
gcc_assert (edge_cost > 0);
index = lto_symtab_encoder_lookup (partition->encoder,
edge->callee);
if (index != LCC_NOT_FOUND
&& index < last_visited_node - 1)
cost -= edge_cost, internal += edge_cost;
else
cost += edge_cost;
}
for (edge = node->callers; edge; edge = edge->next_caller)
if (edge->inline_failed
&& account_reference_p (edge->caller, node))
{
int edge_cost = edge->frequency ();
int index;
gcc_assert (edge->caller->definition);
if (!edge_cost)
edge_cost = 1;
gcc_assert (edge_cost > 0);
index = lto_symtab_encoder_lookup (partition->encoder,
edge->caller);
if (index != LCC_NOT_FOUND
&& index < last_visited_node - 1)
cost -= edge_cost, internal += edge_cost;
else
cost += edge_cost;
}
}
else
last_visited_node++;
/* Compute boundary cost of IPA REF edges and at the same time look into
variables referenced from current partition and try to add them. */
for (j = 0; snode->iterate_reference (j, ref); j++)
if (!account_reference_p (snode, ref->referred))
;
else if (is_a <varpool_node *> (ref->referred))
{
int index;
vnode = dyn_cast <varpool_node *> (ref->referred);
if (!symbol_partitioned_p (vnode)
&& !vnode->no_reorder
&& vnode->get_partitioning_class () == SYMBOL_PARTITION)
add_symbol_to_partition (partition, vnode);
index = lto_symtab_encoder_lookup (partition->encoder,
vnode);
if (index != LCC_NOT_FOUND
&& index < last_visited_node - 1)
cost--, internal++;
else
cost++;
}
else
{
int index;
node = dyn_cast <cgraph_node *> (ref->referred);
index = lto_symtab_encoder_lookup (partition->encoder,
node);
if (index != LCC_NOT_FOUND
&& index < last_visited_node - 1)
cost--, internal++;
else
cost++;
}
for (j = 0; snode->iterate_referring (j, ref); j++)
if (!account_reference_p (ref->referring, snode))
;
else if (is_a <varpool_node *> (ref->referring))
{
int index;
vnode = dyn_cast <varpool_node *> (ref->referring);
gcc_assert (vnode->definition);
/* It is better to couple variables with their users,
because it allows them to be removed. Coupling
with objects they refer to only helps to reduce
number of symbols promoted to hidden. */
if (!symbol_partitioned_p (vnode)
&& !vnode->no_reorder
&& !vnode->can_remove_if_no_refs_p ()
&& vnode->get_partitioning_class () == SYMBOL_PARTITION)
add_symbol_to_partition (partition, vnode);
index = lto_symtab_encoder_lookup (partition->encoder,
vnode);
if (index != LCC_NOT_FOUND
&& index < last_visited_node - 1)
cost--, internal++;
else
cost++;
}
else
{
int index;
node = dyn_cast <cgraph_node *> (ref->referring);
gcc_assert (node->definition);
index = lto_symtab_encoder_lookup (partition->encoder,
node);
if (index != LCC_NOT_FOUND
&& index < last_visited_node - 1)
cost--, internal++;
else
cost++;
}
}
gcc_assert (cost >= 0 && internal >= 0);
/* If the partition is large enough, start looking for smallest boundary cost.
If partition still seems too small (less than 7/8 of target weight) accept
any cost. If partition has right size, optimize for highest internal/cost.
Later we stop building partition if its size is 9/8 of the target wight. */
if (partition->insns < partition_size * 7 / 8
|| best_cost == -1
|| (!cost
|| ((sreal)best_internal * (sreal) cost
< ((sreal) internal * (sreal)best_cost))))
{
best_cost = cost;
best_internal = internal;
best_size = partition->insns;
best_i = i;
best_n_nodes = lto_symtab_encoder_size (partition->encoder);
best_varpool_pos = varpool_pos;
}
if (dump_file)
fprintf (dump_file, "Step %i: added %s, size %i, "
"cost %" PRId64 "/%" PRId64 " "
"best %" PRId64 "/%" PRId64", step %i\n", i,
order[i]->dump_name (),
partition->insns, cost, internal,
best_cost, best_internal, best_i);
/* Partition is too large, unwind into step when best cost was reached and
start new partition. */
if (partition->insns > 9 * partition_size / 8
|| partition->insns > max_partition_size)
{
if (best_i != i)
{
if (dump_file)
fprintf (dump_file, "Unwinding %i insertions to step %i\n",
i - best_i, best_i);
undo_partition (partition, best_n_nodes);
varpool_pos = best_varpool_pos;
}
gcc_assert (best_size == partition->insns);
i = best_i;
if (dump_file)
fprintf (dump_file,
"Partition insns: %i (want %" PRId64 ")\n",
partition->insns, partition_size);
/* When we are finished, avoid creating empty partition. */
while (i < order.length () - 1 && symbol_partitioned_p (order[i + 1]))
i++;
if (i == order.length () - 1)
break;
total_size -= partition->insns;
partition = new_partition ("");
last_visited_node = 0;
cost = 0;
if (dump_file)
fprintf (dump_file, "New partition\n");
best_n_nodes = 0;
best_cost = -1;
/* Since the size of partitions is just approximate, update the size after
we finished current one. */
if (npartitions < n_lto_partitions)
partition_size = total_size / (n_lto_partitions - npartitions);
else
/* Watch for overflow. */
partition_size = INT_MAX / 16;
if (dump_file)
fprintf (dump_file,
"Total size: %" PRId64 " partition_size: %" PRId64 "\n",
total_size, partition_size);
if (partition_size < param_min_partition_size)
partition_size = param_min_partition_size;
npartitions ++;
}
}
next_nodes.truncate (0);
/* Varables that are not reachable from the code go into last partition. */
FOR_EACH_VARIABLE (vnode)
if (vnode->get_partitioning_class () == SYMBOL_PARTITION
&& !symbol_partitioned_p (vnode))
next_nodes.safe_push (vnode);
/* Output remaining ordered symbols. */
while (varpool_pos < n_varpool_nodes)
next_nodes.safe_push (varpool_order[varpool_pos++]);
while (noreorder_pos < (int)noreorder.length ())
next_nodes.safe_push (noreorder[noreorder_pos++]);
/* For one partition the cost of boundary should be 0 unless we added final
symbols here (these are not accounted) or we have accounting bug. */
gcc_assert (next_nodes.length () || npartitions != 1 || !best_cost || best_cost == -1);
add_sorted_nodes (next_nodes, partition);
if (dump_file)
{
fprintf (dump_file, "\nPartition sizes:\n");
unsigned partitions = ltrans_partitions.length ();
for (unsigned i = 0; i < partitions ; i++)
{
ltrans_partition p = ltrans_partitions[i];
fprintf (dump_file, "partition %d contains %d (%2.2f%%)"
" symbols and %d (%2.2f%%) insns\n", i, p->symbols,
100.0 * p->symbols / order.length (), p->insns,
100.0 * p->insns / original_total_size);
}
fprintf (dump_file, "\n");
}
}
/* Return true if we must not change the name of the NODE. The name as
extracted from the corresponding decl should be passed in NAME. */
static bool
must_not_rename (symtab_node *node, const char *name)
{
/* Our renaming machinery do not handle more than one change of assembler name.
We should not need more than one anyway. */
if (node->lto_file_data
&& lto_get_decl_name_mapping (node->lto_file_data, name) != name)
{
if (dump_file)
fprintf (dump_file,
"Not privatizing symbol name: %s. It privatized already.\n",
name);
return true;
}
/* Avoid mangling of already mangled clones.
??? should have a flag whether a symbol has a 'private' name already,
since we produce some symbols like that i.e. for global constructors
that are not really clones. */
if (node->unique_name)
{
if (dump_file)
fprintf (dump_file,
"Not privatizing symbol name: %s. Has unique name.\n",
name);
return true;
}
return false;
}
/* If we are an offload compiler, we may have to rewrite symbols to be
valid on this target. Return either PTR or a modified version of it. */
static const char *
maybe_rewrite_identifier (const char *ptr)
{
#if defined ACCEL_COMPILER && (defined NO_DOT_IN_LABEL || defined NO_DOLLAR_IN_LABEL)
#ifndef NO_DOT_IN_LABEL
char valid = '.';
const char reject[] = "$";
#elif !defined NO_DOLLAR_IN_LABEL
char valid = '$';
const char reject[] = ".";
#else
char valid = '_';
const char reject[] = ".$";
#endif
char *copy = NULL;
const char *match = ptr;
for (;;)
{
size_t off = strcspn (match, reject);
if (match[off] == '\0')
break;
if (copy == NULL)
{
copy = xstrdup (ptr);
match = copy;
}
copy[off] = valid;
}
return match;
#else
return ptr;
#endif
}
/* Ensure that the symbol in NODE is valid for the target, and if not,
rewrite it. */
static void
validize_symbol_for_target (symtab_node *node)
{
tree decl = node->decl;
const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
if (must_not_rename (node, name))
return;
const char *name2 = maybe_rewrite_identifier (name);
if (name2 != name)
{
symtab->change_decl_assembler_name (decl, get_identifier (name2));
if (node->lto_file_data)
lto_record_renamed_decl (node->lto_file_data, name,
IDENTIFIER_POINTER
(DECL_ASSEMBLER_NAME (decl)));
}
}
/* Maps symbol names to unique lto clone counters. */
static hash_map<const char *, unsigned> *lto_clone_numbers;
/* Helper for privatize_symbol_name. Mangle NODE symbol name
represented by DECL. */
static bool
privatize_symbol_name_1 (symtab_node *node, tree decl)
{
const char *name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
if (must_not_rename (node, name))
return false;
name = maybe_rewrite_identifier (name);
unsigned &clone_number = lto_clone_numbers->get_or_insert (name);
symtab->change_decl_assembler_name (decl,
clone_function_name (
name, "lto_priv", clone_number));
clone_number++;
if (node->lto_file_data)
lto_record_renamed_decl (node->lto_file_data, name,
IDENTIFIER_POINTER
(DECL_ASSEMBLER_NAME (decl)));
if (dump_file)
fprintf (dump_file,
"Privatizing symbol name: %s -> %s\n",
name, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)));
return true;
}
/* Mangle NODE symbol name into a local name.
This is necessary to do
1) if two or more static vars of same assembler name
are merged into single ltrans unit.
2) if previously static var was promoted hidden to avoid possible conflict
with symbols defined out of the LTO world. */
static bool
privatize_symbol_name (symtab_node *node)
{
if (!privatize_symbol_name_1 (node, node->decl))
return false;
return true;
}
/* Promote variable VNODE to be static. */
static void
promote_symbol (symtab_node *node)
{
/* We already promoted ... */
if (DECL_VISIBILITY (node->decl) == VISIBILITY_HIDDEN
&& DECL_VISIBILITY_SPECIFIED (node->decl)
&& TREE_PUBLIC (node->decl))
{
validize_symbol_for_target (node);
return;
}
gcc_checking_assert (!TREE_PUBLIC (node->decl)
&& !DECL_EXTERNAL (node->decl));
/* Be sure that newly public symbol does not conflict with anything already
defined by the non-LTO part. */
privatize_symbol_name (node);
TREE_PUBLIC (node->decl) = 1;
DECL_VISIBILITY (node->decl) = VISIBILITY_HIDDEN;
DECL_VISIBILITY_SPECIFIED (node->decl) = true;
if (dump_file)
fprintf (dump_file,
"Promoting as hidden: %s (%s)\n", node->name (),
IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl)));
/* Promoting a symbol also promotes all transparent aliases with exception
of weakref where the visibility flags are always wrong and set to
!PUBLIC. */
ipa_ref *ref;
for (unsigned i = 0; node->iterate_direct_aliases (i, ref); i++)
{
struct symtab_node *alias = ref->referring;
if (alias->transparent_alias && !alias->weakref)
{
TREE_PUBLIC (alias->decl) = 1;
DECL_VISIBILITY (alias->decl) = VISIBILITY_HIDDEN;
DECL_VISIBILITY_SPECIFIED (alias->decl) = true;
if (dump_file)
fprintf (dump_file,
"Promoting alias as hidden: %s\n",
IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl)));
}
gcc_assert (!alias->weakref || TREE_PUBLIC (alias->decl));
}
}
/* Return true if NODE needs named section even if it won't land in
the partition symbol table.
FIXME: we should really not use named sections for inline clones
and master clones. */
static bool
may_need_named_section_p (lto_symtab_encoder_t encoder, symtab_node *node)
{
struct cgraph_node *cnode = dyn_cast <cgraph_node *> (node);
if (!cnode)
return false;
if (node->real_symbol_p ())
return false;
return (!encoder
|| (lto_symtab_encoder_lookup (encoder, node) != LCC_NOT_FOUND
&& lto_symtab_encoder_encode_body_p (encoder,
cnode)));
}
/* If NODE represents a static variable. See if there are other variables
of the same name in partition ENCODER (or in whole compilation unit if
ENCODER is NULL) and if so, mangle the statics. Always mangle all
conflicting statics, so we reduce changes of silently miscompiling
asm statements referring to them by symbol name. */
static void
rename_statics (lto_symtab_encoder_t encoder, symtab_node *node)
{
tree decl = node->decl;
symtab_node *s;
tree name = DECL_ASSEMBLER_NAME (decl);
/* See if this is static symbol. */
if (((node->externally_visible && !node->weakref)
/* FIXME: externally_visible is somewhat illogically not set for
external symbols (i.e. those not defined). Remove this test
once this is fixed. */
|| DECL_EXTERNAL (node->decl)
|| !node->real_symbol_p ())
&& !may_need_named_section_p (encoder, node))
return;
/* Now walk symbols sharing the same name and see if there are any conflicts.
(all types of symbols counts here, since we cannot have static of the
same name as external or public symbol.) */
for (s = symtab_node::get_for_asmname (name);
s; s = s->next_sharing_asm_name)
if ((s->real_symbol_p () || may_need_named_section_p (encoder, s))
&& s->decl != node->decl
&& (!encoder
|| lto_symtab_encoder_lookup (encoder, s) != LCC_NOT_FOUND))
break;
/* OK, no confict, so we have nothing to do. */
if (!s)
return;
if (dump_file)
fprintf (dump_file,
"Renaming statics with asm name: %s\n", node->name ());
/* Assign every symbol in the set that shares the same ASM name an unique
mangled name. */
for (s = symtab_node::get_for_asmname (name); s;)
if ((!s->externally_visible || s->weakref)
/* Transparent aliases having same name as target are renamed at a
time their target gets new name. Transparent aliases that use
separate assembler name require the name to be unique. */
&& (!s->transparent_alias || !s->definition || s->weakref
|| !symbol_table::assembler_names_equal_p
(IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (s->decl)),
IDENTIFIER_POINTER
(DECL_ASSEMBLER_NAME (s->get_alias_target()->decl))))
&& ((s->real_symbol_p ()
&& !DECL_EXTERNAL (s->decl)
&& !TREE_PUBLIC (s->decl))
|| may_need_named_section_p (encoder, s))
&& (!encoder
|| lto_symtab_encoder_lookup (encoder, s) != LCC_NOT_FOUND))
{
if (privatize_symbol_name (s))
/* Re-start from beginning since we do not know how many
symbols changed a name. */
s = symtab_node::get_for_asmname (name);
else s = s->next_sharing_asm_name;
}
else s = s->next_sharing_asm_name;
}
/* Find out all static decls that need to be promoted to global because
of cross file sharing. This function must be run in the WPA mode after
all inlinees are added. */
void
lto_promote_cross_file_statics (void)
{
unsigned i, n_sets;
gcc_assert (flag_wpa);
lto_stream_offload_p = false;
select_what_to_stream ();
/* First compute boundaries. */
n_sets = ltrans_partitions.length ();
for (i = 0; i < n_sets; i++)
{
ltrans_partition part
= ltrans_partitions[i];
part->encoder = compute_ltrans_boundary (part->encoder);
}
lto_clone_numbers = new hash_map<const char *, unsigned>;
/* Look at boundaries and promote symbols as needed. */
for (i = 0; i < n_sets; i++)
{
lto_symtab_encoder_iterator lsei;
lto_symtab_encoder_t encoder = ltrans_partitions[i]->encoder;
for (lsei = lsei_start (encoder); !lsei_end_p (lsei);
lsei_next (&lsei))
{
symtab_node *node = lsei_node (lsei);
/* If symbol is static, rename it if its assembler name
clashes with anything else in this unit. */
rename_statics (encoder, node);
/* No need to promote if symbol already is externally visible ... */
if (node->externally_visible
/* ... or if it is part of current partition ... */
|| lto_symtab_encoder_in_partition_p (encoder, node)
/* ... or if we do not partition it. This mean that it will
appear in every partition referencing it. */
|| node->get_partitioning_class () != SYMBOL_PARTITION)
{
validize_symbol_for_target (node);
continue;
}
promote_symbol (node);
}
}
delete lto_clone_numbers;
}
/* Rename statics in the whole unit in the case that
we do -flto-partition=none. */
void
lto_promote_statics_nonwpa (void)
{
symtab_node *node;
lto_clone_numbers = new hash_map<const char *, unsigned>;
FOR_EACH_SYMBOL (node)
{
rename_statics (NULL, node);
validize_symbol_for_target (node);
}
delete lto_clone_numbers;
}
|