Line data Source code
1 : /* Routines to implement minimum-cost maximal flow algorithm used to smooth
2 : basic block and edge frequency counts.
3 : Copyright (C) 2008-2026 Free Software Foundation, Inc.
4 : Contributed by Paul Yuan (yingbo.com@gmail.com) and
5 : Vinodha Ramasamy (vinodha@google.com).
6 :
7 : This file is part of GCC.
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 : /* References:
23 : [1] "Feedback-directed Optimizations in GCC with Estimated Edge Profiles
24 : from Hardware Event Sampling", Vinodha Ramasamy, Paul Yuan, Dehao Chen,
25 : and Robert Hundt; GCC Summit 2008.
26 : [2] "Complementing Missing and Inaccurate Profiling Using a Minimum Cost
27 : Circulation Algorithm", Roy Levin, Ilan Newman and Gadi Haber;
28 : HiPEAC '08.
29 :
30 : Algorithm to smooth basic block and edge counts:
31 : 1. create_fixup_graph: Create fixup graph by translating function CFG into
32 : a graph that satisfies MCF algorithm requirements.
33 : 2. find_max_flow: Find maximal flow.
34 : 3. compute_residual_flow: Form residual network.
35 : 4. Repeat:
36 : cancel_negative_cycle: While G contains a negative cost cycle C, reverse
37 : the flow on the found cycle by the minimum residual capacity in that
38 : cycle.
39 : 5. Form the minimal cost flow
40 : f(u,v) = rf(v, u).
41 : 6. adjust_cfg_counts: Update initial edge weights with corrected weights.
42 : delta(u.v) = f(u,v) -f(v,u).
43 : w*(u,v) = w(u,v) + delta(u,v). */
44 :
45 : #include "config.h"
46 : #include "system.h"
47 : #include "coretypes.h"
48 : #include "backend.h"
49 : #include "profile.h"
50 : #include "dumpfile.h"
51 :
52 : /* CAP_INFINITY: Constant to represent infinite capacity. */
53 : #define CAP_INFINITY INTTYPE_MAXIMUM (int64_t)
54 :
55 : /* COST FUNCTION. */
56 : #define K_POS(b) ((b))
57 : #define K_NEG(b) (50 * (b))
58 : #define COST(k, w) ((k) / mcf_ln ((w) + 2))
59 : /* Limit the number of iterations for cancel_negative_cycles() to ensure
60 : reasonable compile time. */
61 : #define MAX_ITER(n, e) 10 + (1000000 / ((n) * (e)))
62 : enum edge_type
63 : {
64 : INVALID_EDGE,
65 : VERTEX_SPLIT_EDGE, /* Edge to represent vertex with w(e) = w(v). */
66 : REDIRECT_EDGE, /* Edge after vertex transformation. */
67 : REVERSE_EDGE,
68 : SOURCE_CONNECT_EDGE, /* Single edge connecting to single source. */
69 : SINK_CONNECT_EDGE, /* Single edge connecting to single sink. */
70 : BALANCE_EDGE, /* Edge connecting with source/sink: cp(e) = 0. */
71 : REDIRECT_NORMALIZED_EDGE, /* Normalized edge for a redirect edge. */
72 : REVERSE_NORMALIZED_EDGE /* Normalized edge for a reverse edge. */
73 : };
74 :
75 : /* Structure to represent an edge in the fixup graph. */
76 : struct fixup_edge_type
77 : {
78 : int src;
79 : int dest;
80 : /* Flag denoting type of edge and attributes for the flow field. */
81 : edge_type type;
82 : bool is_rflow_valid;
83 : /* Index to the normalization vertex added for this edge. */
84 : int norm_vertex_index;
85 : /* Flow for this edge. */
86 : gcov_type flow;
87 : /* Residual flow for this edge - used during negative cycle canceling. */
88 : gcov_type rflow;
89 : gcov_type weight;
90 : gcov_type cost;
91 : gcov_type max_capacity;
92 : };
93 :
94 : typedef fixup_edge_type *fixup_edge_p;
95 :
96 :
97 : /* Structure to represent a vertex in the fixup graph. */
98 : struct fixup_vertex_type
99 : {
100 : vec<fixup_edge_p> succ_edges;
101 : };
102 :
103 : typedef fixup_vertex_type *fixup_vertex_p;
104 :
105 : /* Fixup graph used in the MCF algorithm. */
106 : struct fixup_graph_type
107 : {
108 : /* Current number of vertices for the graph. */
109 : int num_vertices;
110 : /* Current number of edges for the graph. */
111 : int num_edges;
112 : /* Index of new entry vertex. */
113 : int new_entry_index;
114 : /* Index of new exit vertex. */
115 : int new_exit_index;
116 : /* Fixup vertex list. Adjacency list for fixup graph. */
117 : fixup_vertex_p vertex_list;
118 : /* Fixup edge list. */
119 : fixup_edge_p edge_list;
120 : };
121 :
122 : struct queue_type
123 : {
124 : int *queue;
125 : int head;
126 : int tail;
127 : int size;
128 : };
129 :
130 : /* Structure used in the maximal flow routines to find augmenting path. */
131 : struct augmenting_path_type
132 : {
133 : /* Queue used to hold vertex indices. */
134 : queue_type queue_list;
135 : /* Vector to hold chain of pred vertex indices in augmenting path. */
136 : int *bb_pred;
137 : /* Vector that indicates if basic block i has been visited. */
138 : int *is_visited;
139 : };
140 :
141 :
142 : /* Function definitions. */
143 :
144 : /* Dump routines to aid debugging. */
145 :
146 : /* Print basic block with index N for FIXUP_GRAPH in n' and n'' format. */
147 :
148 : static void
149 0 : print_basic_block (FILE *file, fixup_graph_type *fixup_graph, int n)
150 : {
151 0 : if (n == ENTRY_BLOCK)
152 0 : fputs ("ENTRY", file);
153 0 : else if (n == ENTRY_BLOCK + 1)
154 0 : fputs ("ENTRY''", file);
155 0 : else if (n == 2 * EXIT_BLOCK)
156 0 : fputs ("EXIT", file);
157 0 : else if (n == 2 * EXIT_BLOCK + 1)
158 0 : fputs ("EXIT''", file);
159 0 : else if (n == fixup_graph->new_exit_index)
160 0 : fputs ("NEW_EXIT", file);
161 0 : else if (n == fixup_graph->new_entry_index)
162 0 : fputs ("NEW_ENTRY", file);
163 : else
164 : {
165 0 : fprintf (file, "%d", n / 2);
166 0 : if (n % 2)
167 0 : fputs ("''", file);
168 : else
169 0 : fputs ("'", file);
170 : }
171 0 : }
172 :
173 :
174 : /* Print edge S->D for given fixup_graph with n' and n'' format.
175 : PARAMETERS:
176 : S is the index of the source vertex of the edge (input) and
177 : D is the index of the destination vertex of the edge (input) for the given
178 : fixup_graph (input). */
179 :
180 : static void
181 0 : print_edge (FILE *file, fixup_graph_type *fixup_graph, int s, int d)
182 : {
183 0 : print_basic_block (file, fixup_graph, s);
184 0 : fputs ("->", file);
185 0 : print_basic_block (file, fixup_graph, d);
186 0 : }
187 :
188 :
189 : /* Dump out the attributes of a given edge FEDGE in the fixup_graph to a
190 : file. */
191 : static void
192 0 : dump_fixup_edge (FILE *file, fixup_graph_type *fixup_graph, fixup_edge_p fedge)
193 : {
194 0 : if (!fedge)
195 : {
196 0 : fputs ("NULL fixup graph edge.\n", file);
197 0 : return;
198 : }
199 :
200 0 : print_edge (file, fixup_graph, fedge->src, fedge->dest);
201 0 : fputs (": ", file);
202 :
203 0 : if (fedge->type)
204 : {
205 0 : fprintf (file, "flow/capacity=%" PRId64 "/",
206 : fedge->flow);
207 0 : if (fedge->max_capacity == CAP_INFINITY)
208 0 : fputs ("+oo,", file);
209 : else
210 0 : fprintf (file, "%" PRId64 ",", fedge->max_capacity);
211 : }
212 :
213 0 : if (fedge->is_rflow_valid)
214 : {
215 0 : if (fedge->rflow == CAP_INFINITY)
216 0 : fputs (" rflow=+oo.", file);
217 : else
218 0 : fprintf (file, " rflow=%" PRId64 ",", fedge->rflow);
219 : }
220 :
221 0 : fprintf (file, " cost=%" PRId64 ".", fedge->cost);
222 :
223 0 : fprintf (file, "\t(%d->%d)", fedge->src, fedge->dest);
224 :
225 0 : if (fedge->type)
226 : {
227 0 : switch (fedge->type)
228 : {
229 0 : case VERTEX_SPLIT_EDGE:
230 0 : fputs (" @VERTEX_SPLIT_EDGE", file);
231 0 : break;
232 :
233 0 : case REDIRECT_EDGE:
234 0 : fputs (" @REDIRECT_EDGE", file);
235 0 : break;
236 :
237 0 : case SOURCE_CONNECT_EDGE:
238 0 : fputs (" @SOURCE_CONNECT_EDGE", file);
239 0 : break;
240 :
241 0 : case SINK_CONNECT_EDGE:
242 0 : fputs (" @SINK_CONNECT_EDGE", file);
243 0 : break;
244 :
245 0 : case REVERSE_EDGE:
246 0 : fputs (" @REVERSE_EDGE", file);
247 0 : break;
248 :
249 0 : case BALANCE_EDGE:
250 0 : fputs (" @BALANCE_EDGE", file);
251 0 : break;
252 :
253 0 : case REDIRECT_NORMALIZED_EDGE:
254 0 : case REVERSE_NORMALIZED_EDGE:
255 0 : fputs (" @NORMALIZED_EDGE", file);
256 0 : break;
257 :
258 0 : default:
259 0 : fputs (" @INVALID_EDGE", file);
260 0 : break;
261 : }
262 : }
263 0 : fputs ("\n", file);
264 : }
265 :
266 :
267 : /* Print out the edges and vertices of the given FIXUP_GRAPH, into the dump
268 : file. The input string MSG is printed out as a heading. */
269 :
270 : static void
271 0 : dump_fixup_graph (FILE *file, fixup_graph_type *fixup_graph, const char *msg)
272 : {
273 0 : int i, j;
274 0 : int fnum_vertices, fnum_edges;
275 :
276 0 : fixup_vertex_p fvertex_list, pfvertex;
277 0 : fixup_edge_p pfedge;
278 :
279 0 : gcc_assert (fixup_graph);
280 0 : fvertex_list = fixup_graph->vertex_list;
281 0 : fnum_vertices = fixup_graph->num_vertices;
282 0 : fnum_edges = fixup_graph->num_edges;
283 :
284 0 : fprintf (file, "\nDump fixup graph for %s(): %s.\n",
285 : current_function_name (), msg);
286 0 : fprintf (file,
287 : "There are %d vertices and %d edges. new_exit_index is %d.\n\n",
288 : fnum_vertices, fnum_edges, fixup_graph->new_exit_index);
289 :
290 0 : for (i = 0; i < fnum_vertices; i++)
291 : {
292 0 : pfvertex = fvertex_list + i;
293 0 : fprintf (file, "vertex_list[%d]: %d succ fixup edges.\n",
294 : i, pfvertex->succ_edges.length ());
295 :
296 0 : for (j = 0; pfvertex->succ_edges.iterate (j, &pfedge);
297 : j++)
298 : {
299 : /* Distinguish forward edges and backward edges in the residual flow
300 : network. */
301 0 : if (pfedge->type)
302 0 : fputs ("(f) ", file);
303 0 : else if (pfedge->is_rflow_valid)
304 0 : fputs ("(b) ", file);
305 0 : dump_fixup_edge (file, fixup_graph, pfedge);
306 : }
307 : }
308 :
309 0 : fputs ("\n", file);
310 0 : }
311 :
312 :
313 : /* Utility routines. */
314 : /* ln() implementation: approximate calculation. Returns ln of X. */
315 :
316 : static double
317 0 : mcf_ln (double x)
318 : {
319 : #define E 2.71828
320 0 : int l = 1;
321 0 : double m = E;
322 :
323 0 : gcc_assert (x >= 0);
324 :
325 0 : while (m < x)
326 : {
327 0 : m *= E;
328 0 : l++;
329 : }
330 :
331 0 : return l;
332 : }
333 :
334 :
335 : /* sqrt() implementation: based on open source QUAKE3 code (magic sqrt
336 : implementation) by John Carmack. Returns sqrt of X. */
337 :
338 : static double
339 0 : mcf_sqrt (double x)
340 : {
341 : #define MAGIC_CONST1 0x1fbcf800
342 : #define MAGIC_CONST2 0x5f3759df
343 0 : union {
344 : int intPart;
345 : float floatPart;
346 : } convertor, convertor2;
347 :
348 0 : gcc_assert (x >= 0);
349 :
350 0 : convertor.floatPart = x;
351 0 : convertor2.floatPart = x;
352 0 : convertor.intPart = MAGIC_CONST1 + (convertor.intPart >> 1);
353 0 : convertor2.intPart = MAGIC_CONST2 - (convertor2.intPart >> 1);
354 :
355 0 : return 0.5f * (convertor.floatPart + (x * convertor2.floatPart));
356 : }
357 :
358 :
359 : /* Common code shared between add_fixup_edge and add_rfixup_edge. Adds an edge
360 : (SRC->DEST) to the edge_list maintained in FIXUP_GRAPH with cost of the edge
361 : added set to COST. */
362 :
363 : static fixup_edge_p
364 0 : add_edge (fixup_graph_type *fixup_graph, int src, int dest, gcov_type cost)
365 : {
366 0 : fixup_vertex_p curr_vertex = fixup_graph->vertex_list + src;
367 0 : fixup_edge_p curr_edge = fixup_graph->edge_list + fixup_graph->num_edges;
368 0 : curr_edge->src = src;
369 0 : curr_edge->dest = dest;
370 0 : curr_edge->cost = cost;
371 0 : fixup_graph->num_edges++;
372 0 : if (dump_file)
373 0 : dump_fixup_edge (dump_file, fixup_graph, curr_edge);
374 0 : curr_vertex->succ_edges.safe_push (curr_edge);
375 0 : return curr_edge;
376 : }
377 :
378 :
379 : /* Add a fixup edge (src->dest) with attributes TYPE, WEIGHT, COST and
380 : MAX_CAPACITY to the edge_list in the fixup graph. */
381 :
382 : static void
383 0 : add_fixup_edge (fixup_graph_type *fixup_graph, int src, int dest,
384 : edge_type type, gcov_type weight, gcov_type cost,
385 : gcov_type max_capacity)
386 : {
387 0 : fixup_edge_p curr_edge = add_edge (fixup_graph, src, dest, cost);
388 0 : curr_edge->type = type;
389 0 : curr_edge->weight = weight;
390 0 : curr_edge->max_capacity = max_capacity;
391 0 : }
392 :
393 :
394 : /* Add a residual edge (SRC->DEST) with attributes RFLOW and COST
395 : to the fixup graph. */
396 :
397 : static void
398 0 : add_rfixup_edge (fixup_graph_type *fixup_graph, int src, int dest,
399 : gcov_type rflow, gcov_type cost)
400 : {
401 0 : fixup_edge_p curr_edge = add_edge (fixup_graph, src, dest, cost);
402 0 : curr_edge->rflow = rflow;
403 0 : curr_edge->is_rflow_valid = true;
404 : /* This edge is not a valid edge - merely used to hold residual flow. */
405 0 : curr_edge->type = INVALID_EDGE;
406 0 : }
407 :
408 :
409 : /* Return the pointer to fixup edge SRC->DEST or NULL if edge does not
410 : exist in the FIXUP_GRAPH. */
411 :
412 : static fixup_edge_p
413 0 : find_fixup_edge (fixup_graph_type *fixup_graph, int src, int dest)
414 : {
415 0 : int j;
416 0 : fixup_edge_p pfedge;
417 0 : fixup_vertex_p pfvertex;
418 :
419 0 : gcc_assert (src < fixup_graph->num_vertices);
420 :
421 0 : pfvertex = fixup_graph->vertex_list + src;
422 :
423 0 : for (j = 0; pfvertex->succ_edges.iterate (j, &pfedge);
424 : j++)
425 0 : if (pfedge->dest == dest)
426 : return pfedge;
427 :
428 : return NULL;
429 : }
430 :
431 :
432 : /* Cleanup routine to free structures in FIXUP_GRAPH. */
433 :
434 : static void
435 0 : delete_fixup_graph (fixup_graph_type *fixup_graph)
436 : {
437 0 : int i;
438 0 : int fnum_vertices = fixup_graph->num_vertices;
439 0 : fixup_vertex_p pfvertex = fixup_graph->vertex_list;
440 :
441 0 : for (i = 0; i < fnum_vertices; i++, pfvertex++)
442 0 : pfvertex->succ_edges.release ();
443 :
444 0 : free (fixup_graph->vertex_list);
445 0 : free (fixup_graph->edge_list);
446 0 : }
447 :
448 :
449 : /* Creates a fixup graph FIXUP_GRAPH from the function CFG. */
450 :
451 : static void
452 0 : create_fixup_graph (fixup_graph_type *fixup_graph)
453 : {
454 0 : double sqrt_avg_vertex_weight = 0;
455 0 : double total_vertex_weight = 0;
456 0 : double k_pos = 0;
457 0 : double k_neg = 0;
458 : /* Vector to hold D(v) = sum_out_edges(v) - sum_in_edges(v). */
459 0 : gcov_type *diff_out_in = NULL;
460 0 : gcov_type supply_value = 1, demand_value = 0;
461 0 : gcov_type fcost = 0;
462 0 : int new_entry_index = 0, new_exit_index = 0;
463 0 : int i = 0, j = 0;
464 0 : int new_index = 0;
465 0 : basic_block bb;
466 0 : edge e;
467 0 : edge_iterator ei;
468 0 : fixup_edge_p pfedge, r_pfedge;
469 0 : fixup_edge_p fedge_list;
470 0 : int fnum_edges;
471 :
472 : /* Each basic_block will be split into 2 during vertex transformation. */
473 0 : int fnum_vertices_after_transform = 2 * n_basic_blocks_for_fn (cfun);
474 0 : int fnum_edges_after_transform =
475 0 : n_edges_for_fn (cfun) + n_basic_blocks_for_fn (cfun);
476 :
477 : /* Count the new SOURCE and EXIT vertices to be added. */
478 0 : int fmax_num_vertices =
479 0 : (fnum_vertices_after_transform + n_edges_for_fn (cfun)
480 0 : + n_basic_blocks_for_fn (cfun) + 2);
481 :
482 : /* In create_fixup_graph: Each basic block and edge can be split into 3
483 : edges. Number of balance edges = n_basic_blocks. So after
484 : create_fixup_graph:
485 : max_edges = 4 * n_basic_blocks + 3 * n_edges
486 : Accounting for residual flow edges
487 : max_edges = 2 * (4 * n_basic_blocks + 3 * n_edges)
488 : = 8 * n_basic_blocks + 6 * n_edges
489 : < 8 * n_basic_blocks + 8 * n_edges. */
490 0 : int fmax_num_edges = 8 * (n_basic_blocks_for_fn (cfun) +
491 : n_edges_for_fn (cfun));
492 :
493 : /* Initial num of vertices in the fixup graph. */
494 0 : fixup_graph->num_vertices = n_basic_blocks_for_fn (cfun);
495 :
496 : /* Fixup graph vertex list. */
497 0 : fixup_graph->vertex_list =
498 0 : (fixup_vertex_p) xcalloc (fmax_num_vertices, sizeof (fixup_vertex_type));
499 :
500 : /* Fixup graph edge list. */
501 0 : fixup_graph->edge_list =
502 0 : (fixup_edge_p) xcalloc (fmax_num_edges, sizeof (fixup_edge_type));
503 :
504 0 : diff_out_in =
505 0 : (gcov_type *) xcalloc (1 + fnum_vertices_after_transform,
506 : sizeof (gcov_type));
507 :
508 : /* Compute constants b, k_pos, k_neg used in the cost function calculation.
509 : b = sqrt(avg_vertex_weight(cfg)); k_pos = b; k_neg = 50b. */
510 0 : FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
511 0 : total_vertex_weight += bb_gcov_count (bb);
512 :
513 0 : sqrt_avg_vertex_weight = mcf_sqrt (total_vertex_weight /
514 0 : n_basic_blocks_for_fn (cfun));
515 :
516 0 : k_pos = K_POS (sqrt_avg_vertex_weight);
517 0 : k_neg = K_NEG (sqrt_avg_vertex_weight);
518 :
519 : /* 1. Vertex Transformation: Split each vertex v into two vertices v' and v'',
520 : connected by an edge e from v' to v''. w(e) = w(v). */
521 :
522 0 : if (dump_file)
523 0 : fprintf (dump_file, "\nVertex transformation:\n");
524 :
525 0 : FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb)
526 : {
527 : /* v'->v'': index1->(index1+1). */
528 0 : i = 2 * bb->index;
529 0 : fcost = (gcov_type) COST (k_pos, bb_gcov_count (bb));
530 0 : add_fixup_edge (fixup_graph, i, i + 1, VERTEX_SPLIT_EDGE, bb_gcov_count (bb),
531 : fcost, CAP_INFINITY);
532 0 : fixup_graph->num_vertices++;
533 :
534 0 : FOR_EACH_EDGE (e, ei, bb->succs)
535 : {
536 : /* Edges with ignore attribute set should be treated like they don't
537 : exist. */
538 0 : if (EDGE_INFO (e) && EDGE_INFO (e)->ignore)
539 0 : continue;
540 0 : j = 2 * e->dest->index;
541 0 : fcost = (gcov_type) COST (k_pos, edge_gcov_count (e));
542 0 : add_fixup_edge (fixup_graph, i + 1, j, REDIRECT_EDGE, edge_gcov_count (e),
543 : fcost, CAP_INFINITY);
544 : }
545 : }
546 :
547 : /* After vertex transformation. */
548 0 : gcc_assert (fixup_graph->num_vertices == fnum_vertices_after_transform);
549 : /* Redirect edges are not added for edges with ignore attribute. */
550 0 : gcc_assert (fixup_graph->num_edges <= fnum_edges_after_transform);
551 :
552 0 : fnum_edges_after_transform = fixup_graph->num_edges;
553 :
554 : /* 2. Initialize D(v). */
555 0 : for (i = 0; i < fnum_edges_after_transform; i++)
556 : {
557 0 : pfedge = fixup_graph->edge_list + i;
558 0 : diff_out_in[pfedge->src] += pfedge->weight;
559 0 : diff_out_in[pfedge->dest] -= pfedge->weight;
560 : }
561 :
562 : /* Entry block - vertex indices 0, 1; EXIT block - vertex indices 2, 3. */
563 0 : for (i = 0; i <= 3; i++)
564 0 : diff_out_in[i] = 0;
565 :
566 : /* 3. Add reverse edges: needed to decrease counts during smoothing. */
567 0 : if (dump_file)
568 0 : fprintf (dump_file, "\nReverse edges:\n");
569 0 : for (i = 0; i < fnum_edges_after_transform; i++)
570 : {
571 0 : pfedge = fixup_graph->edge_list + i;
572 0 : if ((pfedge->src == 0) || (pfedge->src == 2))
573 0 : continue;
574 0 : r_pfedge = find_fixup_edge (fixup_graph, pfedge->dest, pfedge->src);
575 0 : if (!r_pfedge && pfedge->weight)
576 : {
577 : /* Skip adding reverse edges for edges with w(e) = 0, as its maximum
578 : capacity is 0. */
579 0 : fcost = (gcov_type) COST (k_neg, pfedge->weight);
580 0 : add_fixup_edge (fixup_graph, pfedge->dest, pfedge->src,
581 : REVERSE_EDGE, 0, fcost, pfedge->weight);
582 : }
583 : }
584 :
585 : /* 4. Create single source and sink. Connect new source vertex s' to function
586 : entry block. Connect sink vertex t' to function exit. */
587 0 : if (dump_file)
588 0 : fprintf (dump_file, "\ns'->S, T->t':\n");
589 :
590 0 : new_entry_index = fixup_graph->new_entry_index = fixup_graph->num_vertices;
591 0 : fixup_graph->num_vertices++;
592 : /* Set supply_value to 1 to avoid zero count function ENTRY. */
593 0 : add_fixup_edge (fixup_graph, new_entry_index, ENTRY_BLOCK, SOURCE_CONNECT_EDGE,
594 : 1 /* supply_value */, 0, 1 /* supply_value */);
595 :
596 : /* Create new exit with EXIT_BLOCK as single pred. */
597 0 : new_exit_index = fixup_graph->new_exit_index = fixup_graph->num_vertices;
598 0 : fixup_graph->num_vertices++;
599 0 : add_fixup_edge (fixup_graph, 2 * EXIT_BLOCK + 1, new_exit_index,
600 : SINK_CONNECT_EDGE,
601 : 0 /* demand_value */, 0, 0 /* demand_value */);
602 :
603 : /* Connect vertices with unbalanced D(v) to source/sink. */
604 0 : if (dump_file)
605 0 : fprintf (dump_file, "\nD(v) balance:\n");
606 : /* Skip vertices for ENTRY (0, 1) and EXIT (2,3) blocks, so start with i = 4.
607 : diff_out_in[v''] will be 0, so skip v'' vertices, hence i += 2. */
608 0 : for (i = 4; i < new_entry_index; i += 2)
609 : {
610 0 : if (diff_out_in[i] > 0)
611 : {
612 0 : add_fixup_edge (fixup_graph, i, new_exit_index, BALANCE_EDGE, 0, 0,
613 : diff_out_in[i]);
614 0 : demand_value += diff_out_in[i];
615 : }
616 0 : else if (diff_out_in[i] < 0)
617 : {
618 0 : add_fixup_edge (fixup_graph, new_entry_index, i, BALANCE_EDGE, 0, 0,
619 : -diff_out_in[i]);
620 0 : supply_value -= diff_out_in[i];
621 : }
622 : }
623 :
624 : /* Set supply = demand. */
625 0 : if (dump_file)
626 : {
627 0 : fprintf (dump_file, "\nAdjust supply and demand:\n");
628 0 : fprintf (dump_file, "supply_value=%" PRId64 "\n",
629 : supply_value);
630 0 : fprintf (dump_file, "demand_value=%" PRId64 "\n",
631 : demand_value);
632 : }
633 :
634 0 : if (demand_value > supply_value)
635 : {
636 0 : pfedge = find_fixup_edge (fixup_graph, new_entry_index, ENTRY_BLOCK);
637 0 : pfedge->max_capacity += (demand_value - supply_value);
638 : }
639 : else
640 : {
641 0 : pfedge = find_fixup_edge (fixup_graph, 2 * EXIT_BLOCK + 1, new_exit_index);
642 0 : pfedge->max_capacity += (supply_value - demand_value);
643 : }
644 :
645 : /* 6. Normalize edges: remove anti-parallel edges. Anti-parallel edges are
646 : created by the vertex transformation step from self-edges in the original
647 : CFG and by the reverse edges added earlier. */
648 0 : if (dump_file)
649 0 : fprintf (dump_file, "\nNormalize edges:\n");
650 :
651 0 : fnum_edges = fixup_graph->num_edges;
652 0 : fedge_list = fixup_graph->edge_list;
653 :
654 0 : for (i = 0; i < fnum_edges; i++)
655 : {
656 0 : pfedge = fedge_list + i;
657 0 : r_pfedge = find_fixup_edge (fixup_graph, pfedge->dest, pfedge->src);
658 0 : if (((pfedge->type == VERTEX_SPLIT_EDGE)
659 0 : || (pfedge->type == REDIRECT_EDGE)) && r_pfedge)
660 : {
661 0 : new_index = fixup_graph->num_vertices;
662 0 : fixup_graph->num_vertices++;
663 :
664 0 : if (dump_file)
665 : {
666 0 : fprintf (dump_file, "\nAnti-parallel edge:\n");
667 0 : dump_fixup_edge (dump_file, fixup_graph, pfedge);
668 0 : dump_fixup_edge (dump_file, fixup_graph, r_pfedge);
669 0 : fprintf (dump_file, "New vertex is %d.\n", new_index);
670 0 : fprintf (dump_file, "------------------\n");
671 : }
672 :
673 0 : pfedge->cost /= 2;
674 0 : pfedge->norm_vertex_index = new_index;
675 0 : if (dump_file)
676 : {
677 0 : fprintf (dump_file, "After normalization:\n");
678 0 : dump_fixup_edge (dump_file, fixup_graph, pfedge);
679 : }
680 :
681 : /* Add a new fixup edge: new_index->src. */
682 0 : add_fixup_edge (fixup_graph, new_index, pfedge->src,
683 : REVERSE_NORMALIZED_EDGE, 0, r_pfedge->cost,
684 : r_pfedge->max_capacity);
685 0 : gcc_assert (fixup_graph->num_vertices <= fmax_num_vertices);
686 :
687 : /* Edge: r_pfedge->src -> r_pfedge->dest
688 : ==> r_pfedge->src -> new_index. */
689 0 : r_pfedge->dest = new_index;
690 0 : r_pfedge->type = REVERSE_NORMALIZED_EDGE;
691 0 : r_pfedge->cost = pfedge->cost;
692 0 : r_pfedge->max_capacity = pfedge->max_capacity;
693 0 : if (dump_file)
694 0 : dump_fixup_edge (dump_file, fixup_graph, r_pfedge);
695 : }
696 : }
697 :
698 0 : if (dump_file)
699 0 : dump_fixup_graph (dump_file, fixup_graph, "After create_fixup_graph()");
700 :
701 : /* Cleanup. */
702 0 : free (diff_out_in);
703 0 : }
704 :
705 :
706 : /* Allocates space for the structures in AUGMENTING_PATH. The space needed is
707 : proportional to the number of nodes in the graph, which is given by
708 : GRAPH_SIZE. */
709 :
710 : static void
711 0 : init_augmenting_path (augmenting_path_type *augmenting_path, int graph_size)
712 : {
713 0 : augmenting_path->queue_list.queue = (int *)
714 0 : xcalloc (graph_size + 2, sizeof (int));
715 0 : augmenting_path->queue_list.size = graph_size + 2;
716 0 : augmenting_path->bb_pred = (int *) xcalloc (graph_size, sizeof (int));
717 0 : augmenting_path->is_visited = (int *) xcalloc (graph_size, sizeof (int));
718 0 : }
719 :
720 : /* Free the structures in AUGMENTING_PATH. */
721 : static void
722 0 : free_augmenting_path (augmenting_path_type *augmenting_path)
723 : {
724 0 : free (augmenting_path->queue_list.queue);
725 0 : free (augmenting_path->bb_pred);
726 0 : free (augmenting_path->is_visited);
727 0 : }
728 :
729 :
730 : /* Queue routines. Assumes queue will never overflow. */
731 :
732 : static void
733 0 : init_queue (queue_type *queue_list)
734 : {
735 0 : gcc_assert (queue_list);
736 0 : queue_list->head = 0;
737 0 : queue_list->tail = 0;
738 0 : }
739 :
740 : /* Return true if QUEUE_LIST is empty. */
741 : static bool
742 0 : is_empty (queue_type *queue_list)
743 : {
744 0 : return (queue_list->head == queue_list->tail);
745 : }
746 :
747 : /* Insert element X into QUEUE_LIST. */
748 : static void
749 0 : enqueue (queue_type *queue_list, int x)
750 : {
751 0 : gcc_assert (queue_list->tail < queue_list->size);
752 0 : queue_list->queue[queue_list->tail] = x;
753 0 : (queue_list->tail)++;
754 0 : }
755 :
756 : /* Return the first element in QUEUE_LIST. */
757 : static int
758 0 : dequeue (queue_type *queue_list)
759 : {
760 0 : int x;
761 0 : gcc_assert (queue_list->head >= 0);
762 0 : x = queue_list->queue[queue_list->head];
763 0 : (queue_list->head)++;
764 0 : return x;
765 : }
766 :
767 :
768 : /* Finds a negative cycle in the residual network using
769 : the Bellman-Ford algorithm. The flow on the found cycle is reversed by the
770 : minimum residual capacity of that cycle. ENTRY and EXIT vertices are not
771 : considered.
772 :
773 : Parameters:
774 : FIXUP_GRAPH - Residual graph (input/output)
775 : The following are allocated/freed by the caller:
776 : PI - Vector to hold predecessors in path (pi = pred index)
777 : D - D[I] holds minimum cost of path from i to sink
778 : CYCLE - Vector to hold the minimum cost cycle
779 :
780 : Return:
781 : true if a negative cycle was found, false otherwise. */
782 :
783 : static bool
784 0 : cancel_negative_cycle (fixup_graph_type *fixup_graph,
785 : int *pi, gcov_type *d, int *cycle)
786 : {
787 0 : int i, j, k;
788 0 : int fnum_vertices, fnum_edges;
789 0 : fixup_edge_p fedge_list, pfedge, r_pfedge;
790 0 : bool found_cycle = false;
791 0 : int cycle_start = 0, cycle_end = 0;
792 0 : gcov_type sum_cost = 0, cycle_flow = 0;
793 0 : int new_entry_index;
794 0 : bool propagated = false;
795 :
796 0 : gcc_assert (fixup_graph);
797 0 : fnum_vertices = fixup_graph->num_vertices;
798 0 : fnum_edges = fixup_graph->num_edges;
799 0 : fedge_list = fixup_graph->edge_list;
800 0 : new_entry_index = fixup_graph->new_entry_index;
801 :
802 : /* Initialize. */
803 : /* Skip ENTRY. */
804 0 : for (i = 1; i < fnum_vertices; i++)
805 : {
806 0 : d[i] = CAP_INFINITY;
807 0 : pi[i] = -1;
808 0 : cycle[i] = -1;
809 : }
810 0 : d[ENTRY_BLOCK] = 0;
811 :
812 : /* Relax. */
813 0 : for (k = 1; k < fnum_vertices; k++)
814 : {
815 : propagated = false;
816 0 : for (i = 0; i < fnum_edges; i++)
817 : {
818 0 : pfedge = fedge_list + i;
819 0 : if (pfedge->src == new_entry_index)
820 0 : continue;
821 0 : if (pfedge->is_rflow_valid && pfedge->rflow
822 0 : && d[pfedge->src] != CAP_INFINITY
823 0 : && (d[pfedge->dest] > d[pfedge->src] + pfedge->cost))
824 : {
825 0 : d[pfedge->dest] = d[pfedge->src] + pfedge->cost;
826 0 : pi[pfedge->dest] = pfedge->src;
827 0 : propagated = true;
828 : }
829 : }
830 0 : if (!propagated)
831 : break;
832 : }
833 :
834 0 : if (!propagated)
835 : /* No negative cycles exist. */
836 : return 0;
837 :
838 : /* Detect. */
839 0 : for (i = 0; i < fnum_edges; i++)
840 : {
841 0 : pfedge = fedge_list + i;
842 0 : if (pfedge->src == new_entry_index)
843 0 : continue;
844 0 : if (pfedge->is_rflow_valid && pfedge->rflow
845 0 : && d[pfedge->src] != CAP_INFINITY
846 0 : && (d[pfedge->dest] > d[pfedge->src] + pfedge->cost))
847 : {
848 : found_cycle = true;
849 : break;
850 : }
851 : }
852 :
853 0 : if (!found_cycle)
854 : return 0;
855 :
856 : /* Augment the cycle with the cycle's minimum residual capacity. */
857 0 : found_cycle = false;
858 0 : cycle[0] = pfedge->dest;
859 0 : j = pfedge->dest;
860 :
861 0 : for (i = 1; i < fnum_vertices; i++)
862 : {
863 0 : j = pi[j];
864 0 : cycle[i] = j;
865 0 : for (k = 0; k < i; k++)
866 : {
867 0 : if (cycle[k] == j)
868 : {
869 : /* cycle[k] -> ... -> cycle[i]. */
870 : cycle_start = k;
871 : cycle_end = i;
872 : found_cycle = true;
873 : break;
874 : }
875 : }
876 0 : if (found_cycle)
877 : break;
878 : }
879 :
880 0 : gcc_assert (cycle[cycle_start] == cycle[cycle_end]);
881 0 : if (dump_file)
882 0 : fprintf (dump_file, "\nNegative cycle length is %d:\n",
883 : cycle_end - cycle_start);
884 :
885 : sum_cost = 0;
886 : cycle_flow = CAP_INFINITY;
887 0 : for (k = cycle_start; k < cycle_end; k++)
888 : {
889 0 : pfedge = find_fixup_edge (fixup_graph, cycle[k + 1], cycle[k]);
890 0 : cycle_flow = MIN (cycle_flow, pfedge->rflow);
891 0 : sum_cost += pfedge->cost;
892 0 : if (dump_file)
893 0 : fprintf (dump_file, "%d ", cycle[k]);
894 : }
895 :
896 0 : if (dump_file)
897 : {
898 0 : fprintf (dump_file, "%d", cycle[k]);
899 0 : fprintf (dump_file,
900 : ": (%" PRId64 ", %" PRId64
901 : ")\n", sum_cost, cycle_flow);
902 0 : fprintf (dump_file,
903 : "Augment cycle with %" PRId64 "\n",
904 : cycle_flow);
905 : }
906 :
907 0 : for (k = cycle_start; k < cycle_end; k++)
908 : {
909 0 : pfedge = find_fixup_edge (fixup_graph, cycle[k + 1], cycle[k]);
910 0 : r_pfedge = find_fixup_edge (fixup_graph, cycle[k], cycle[k + 1]);
911 0 : pfedge->rflow -= cycle_flow;
912 0 : if (pfedge->type)
913 0 : pfedge->flow += cycle_flow;
914 0 : r_pfedge->rflow += cycle_flow;
915 0 : if (r_pfedge->type)
916 0 : r_pfedge->flow -= cycle_flow;
917 : }
918 :
919 : return true;
920 : }
921 :
922 :
923 : /* Computes the residual flow for FIXUP_GRAPH by setting the rflow field of
924 : the edges. ENTRY and EXIT vertices should not be considered. */
925 :
926 : static void
927 0 : compute_residual_flow (fixup_graph_type *fixup_graph)
928 : {
929 0 : int i;
930 0 : int fnum_edges;
931 0 : fixup_edge_p fedge_list, pfedge;
932 :
933 0 : gcc_assert (fixup_graph);
934 :
935 0 : if (dump_file)
936 0 : fputs ("\ncompute_residual_flow():\n", dump_file);
937 :
938 0 : fnum_edges = fixup_graph->num_edges;
939 0 : fedge_list = fixup_graph->edge_list;
940 :
941 0 : for (i = 0; i < fnum_edges; i++)
942 : {
943 0 : pfedge = fedge_list + i;
944 0 : pfedge->rflow = pfedge->max_capacity - pfedge->flow;
945 0 : pfedge->is_rflow_valid = true;
946 0 : add_rfixup_edge (fixup_graph, pfedge->dest, pfedge->src, pfedge->flow,
947 0 : -pfedge->cost);
948 : }
949 0 : }
950 :
951 :
952 : /* Uses Edmonds-Karp algorithm - BFS to find augmenting path from SOURCE to
953 : SINK. The fields in the edge vector in the FIXUP_GRAPH are not modified by
954 : this routine. The vector bb_pred in the AUGMENTING_PATH structure is updated
955 : to reflect the path found.
956 : Returns: 0 if no augmenting path is found, 1 otherwise. */
957 :
958 : static int
959 0 : find_augmenting_path (fixup_graph_type *fixup_graph,
960 : augmenting_path_type *augmenting_path, int source,
961 : int sink)
962 : {
963 0 : int u = 0;
964 0 : int i;
965 0 : fixup_vertex_p fvertex_list, pfvertex;
966 0 : fixup_edge_p pfedge;
967 0 : int *bb_pred, *is_visited;
968 0 : queue_type *queue_list;
969 :
970 0 : gcc_assert (augmenting_path);
971 0 : bb_pred = augmenting_path->bb_pred;
972 0 : gcc_assert (bb_pred);
973 0 : is_visited = augmenting_path->is_visited;
974 0 : gcc_assert (is_visited);
975 0 : queue_list = &(augmenting_path->queue_list);
976 :
977 0 : gcc_assert (fixup_graph);
978 :
979 0 : fvertex_list = fixup_graph->vertex_list;
980 :
981 0 : for (u = 0; u < fixup_graph->num_vertices; u++)
982 0 : is_visited[u] = 0;
983 :
984 0 : init_queue (queue_list);
985 0 : enqueue (queue_list, source);
986 0 : bb_pred[source] = -1;
987 :
988 0 : while (!is_empty (queue_list))
989 : {
990 0 : u = dequeue (queue_list);
991 0 : is_visited[u] = 1;
992 0 : pfvertex = fvertex_list + u;
993 0 : for (i = 0; pfvertex->succ_edges.iterate (i, &pfedge);
994 : i++)
995 : {
996 0 : int dest = pfedge->dest;
997 0 : if ((pfedge->rflow > 0) && (is_visited[dest] == 0))
998 : {
999 0 : enqueue (queue_list, dest);
1000 0 : bb_pred[dest] = u;
1001 0 : is_visited[dest] = 1;
1002 0 : if (dest == sink)
1003 : return 1;
1004 : }
1005 : }
1006 : }
1007 :
1008 : return 0;
1009 : }
1010 :
1011 :
1012 : /* Routine to find the maximal flow:
1013 : Algorithm:
1014 : 1. Initialize flow to 0
1015 : 2. Find an augmenting path form source to sink.
1016 : 3. Send flow equal to the path's residual capacity along the edges of this path.
1017 : 4. Repeat steps 2 and 3 until no new augmenting path is found.
1018 :
1019 : Parameters:
1020 : SOURCE: index of source vertex (input)
1021 : SINK: index of sink vertex (input)
1022 : FIXUP_GRAPH: adjacency matrix representing the graph. The flow of the edges will be
1023 : set to have a valid maximal flow by this routine. (input)
1024 : Return: Maximum flow possible. */
1025 :
1026 : static gcov_type
1027 0 : find_max_flow (fixup_graph_type *fixup_graph, int source, int sink)
1028 : {
1029 0 : int fnum_edges;
1030 0 : augmenting_path_type augmenting_path;
1031 0 : int *bb_pred;
1032 0 : gcov_type max_flow = 0;
1033 0 : int i, u;
1034 0 : fixup_edge_p fedge_list, pfedge, r_pfedge;
1035 :
1036 0 : gcc_assert (fixup_graph);
1037 :
1038 0 : fnum_edges = fixup_graph->num_edges;
1039 0 : fedge_list = fixup_graph->edge_list;
1040 :
1041 : /* Initialize flow to 0. */
1042 0 : for (i = 0; i < fnum_edges; i++)
1043 : {
1044 0 : pfedge = fedge_list + i;
1045 0 : pfedge->flow = 0;
1046 : }
1047 :
1048 0 : compute_residual_flow (fixup_graph);
1049 :
1050 0 : init_augmenting_path (&augmenting_path, fixup_graph->num_vertices);
1051 :
1052 0 : bb_pred = augmenting_path.bb_pred;
1053 0 : while (find_augmenting_path (fixup_graph, &augmenting_path, source, sink))
1054 : {
1055 : /* Determine the amount by which we can increment the flow. */
1056 : gcov_type increment = CAP_INFINITY;
1057 0 : for (u = sink; u != source; u = bb_pred[u])
1058 : {
1059 0 : pfedge = find_fixup_edge (fixup_graph, bb_pred[u], u);
1060 0 : increment = MIN (increment, pfedge->rflow);
1061 : }
1062 0 : max_flow += increment;
1063 :
1064 : /* Now increment the flow. EXIT vertex index is 1. */
1065 0 : for (u = sink; u != source; u = bb_pred[u])
1066 : {
1067 0 : pfedge = find_fixup_edge (fixup_graph, bb_pred[u], u);
1068 0 : r_pfedge = find_fixup_edge (fixup_graph, u, bb_pred[u]);
1069 0 : if (pfedge->type)
1070 : {
1071 : /* forward edge. */
1072 0 : pfedge->flow += increment;
1073 0 : pfedge->rflow -= increment;
1074 0 : r_pfedge->rflow += increment;
1075 : }
1076 : else
1077 : {
1078 : /* backward edge. */
1079 0 : gcc_assert (r_pfedge->type);
1080 0 : r_pfedge->rflow += increment;
1081 0 : r_pfedge->flow -= increment;
1082 0 : pfedge->rflow -= increment;
1083 : }
1084 : }
1085 :
1086 0 : if (dump_file)
1087 : {
1088 0 : fprintf (dump_file, "\nDump augmenting path:\n");
1089 0 : for (u = sink; u != source; u = bb_pred[u])
1090 : {
1091 0 : print_basic_block (dump_file, fixup_graph, u);
1092 0 : fprintf (dump_file, "<-");
1093 : }
1094 0 : fprintf (dump_file,
1095 : "ENTRY (path_capacity=%" PRId64 ")\n",
1096 : increment);
1097 0 : fprintf (dump_file,
1098 : "Network flow is %" PRId64 ".\n",
1099 : max_flow);
1100 : }
1101 : }
1102 :
1103 0 : free_augmenting_path (&augmenting_path);
1104 0 : if (dump_file)
1105 0 : dump_fixup_graph (dump_file, fixup_graph, "After find_max_flow()");
1106 0 : return max_flow;
1107 : }
1108 :
1109 :
1110 : /* Computes the corrected edge and basic block weights using FIXUP_GRAPH
1111 : after applying the find_minimum_cost_flow() routine. */
1112 :
1113 : static void
1114 0 : adjust_cfg_counts (fixup_graph_type *fixup_graph)
1115 : {
1116 0 : basic_block bb;
1117 0 : edge e;
1118 0 : edge_iterator ei;
1119 0 : int i, j;
1120 0 : fixup_edge_p pfedge, pfedge_n;
1121 :
1122 0 : gcc_assert (fixup_graph);
1123 :
1124 0 : if (dump_file)
1125 0 : fprintf (dump_file, "\nadjust_cfg_counts():\n");
1126 :
1127 0 : FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun),
1128 : EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
1129 : {
1130 0 : i = 2 * bb->index;
1131 :
1132 : /* Fixup BB. */
1133 0 : if (dump_file)
1134 0 : fprintf (dump_file,
1135 0 : "BB%d: %" PRId64 "", bb->index, bb_gcov_count (bb));
1136 :
1137 0 : pfedge = find_fixup_edge (fixup_graph, i, i + 1);
1138 0 : if (pfedge->flow)
1139 : {
1140 0 : bb_gcov_count (bb) += pfedge->flow;
1141 0 : if (dump_file)
1142 : {
1143 0 : fprintf (dump_file, " + %" PRId64 "(",
1144 : pfedge->flow);
1145 0 : print_edge (dump_file, fixup_graph, i, i + 1);
1146 0 : fprintf (dump_file, ")");
1147 : }
1148 : }
1149 :
1150 0 : pfedge_n =
1151 0 : find_fixup_edge (fixup_graph, i + 1, pfedge->norm_vertex_index);
1152 : /* Deduct flow from normalized reverse edge. */
1153 0 : if (pfedge->norm_vertex_index && pfedge_n->flow)
1154 : {
1155 0 : bb_gcov_count (bb) -= pfedge_n->flow;
1156 0 : if (dump_file)
1157 : {
1158 0 : fprintf (dump_file, " - %" PRId64 "(",
1159 : pfedge_n->flow);
1160 0 : print_edge (dump_file, fixup_graph, i + 1,
1161 : pfedge->norm_vertex_index);
1162 0 : fprintf (dump_file, ")");
1163 : }
1164 : }
1165 0 : if (dump_file)
1166 0 : fprintf (dump_file, " = %" PRId64 "\n", bb_gcov_count (bb));
1167 :
1168 : /* Fixup edge. */
1169 0 : FOR_EACH_EDGE (e, ei, bb->succs)
1170 : {
1171 : /* Treat edges with ignore attribute set as if they don't exist. */
1172 0 : if (EDGE_INFO (e) && EDGE_INFO (e)->ignore)
1173 0 : continue;
1174 :
1175 0 : j = 2 * e->dest->index;
1176 0 : if (dump_file)
1177 0 : fprintf (dump_file, "%d->%d: %" PRId64 "",
1178 0 : bb->index, e->dest->index, edge_gcov_count (e));
1179 :
1180 0 : pfedge = find_fixup_edge (fixup_graph, i + 1, j);
1181 :
1182 0 : if (bb->index != e->dest->index)
1183 : {
1184 : /* Non-self edge. */
1185 0 : if (pfedge->flow)
1186 : {
1187 0 : edge_gcov_count (e) += pfedge->flow;
1188 0 : if (dump_file)
1189 : {
1190 0 : fprintf (dump_file, " + %" PRId64 "(",
1191 : pfedge->flow);
1192 0 : print_edge (dump_file, fixup_graph, i + 1, j);
1193 0 : fprintf (dump_file, ")");
1194 : }
1195 : }
1196 :
1197 0 : pfedge_n =
1198 0 : find_fixup_edge (fixup_graph, j, pfedge->norm_vertex_index);
1199 : /* Deduct flow from normalized reverse edge. */
1200 0 : if (pfedge->norm_vertex_index && pfedge_n->flow)
1201 : {
1202 0 : edge_gcov_count (e) -= pfedge_n->flow;
1203 0 : if (dump_file)
1204 : {
1205 0 : fprintf (dump_file, " - %" PRId64 "(",
1206 : pfedge_n->flow);
1207 0 : print_edge (dump_file, fixup_graph, j,
1208 : pfedge->norm_vertex_index);
1209 0 : fprintf (dump_file, ")");
1210 : }
1211 : }
1212 : }
1213 : else
1214 : {
1215 : /* Handle self edges. Self edge is split with a normalization
1216 : vertex. Here i=j. */
1217 0 : pfedge = find_fixup_edge (fixup_graph, j, i + 1);
1218 0 : pfedge_n =
1219 0 : find_fixup_edge (fixup_graph, i + 1, pfedge->norm_vertex_index);
1220 0 : edge_gcov_count (e) += pfedge_n->flow;
1221 0 : bb_gcov_count (bb) += pfedge_n->flow;
1222 0 : if (dump_file)
1223 : {
1224 0 : fprintf (dump_file, "(self edge)");
1225 0 : fprintf (dump_file, " + %" PRId64 "(",
1226 : pfedge_n->flow);
1227 0 : print_edge (dump_file, fixup_graph, i + 1,
1228 : pfedge->norm_vertex_index);
1229 0 : fprintf (dump_file, ")");
1230 : }
1231 : }
1232 :
1233 0 : if (bb_gcov_count (bb))
1234 0 : e->probability = profile_probability::probability_in_gcov_type
1235 0 : (edge_gcov_count (e), bb_gcov_count (bb));
1236 0 : if (dump_file)
1237 : {
1238 0 : fprintf (dump_file, " = %" PRId64 "\t",
1239 0 : edge_gcov_count (e));
1240 0 : e->probability.dump (dump_file);
1241 0 : fprintf (dump_file, "\n");
1242 : }
1243 : }
1244 : }
1245 :
1246 0 : bb_gcov_count (ENTRY_BLOCK_PTR_FOR_FN (cfun)) =
1247 0 : sum_edge_counts (ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs);
1248 0 : bb_gcov_count (EXIT_BLOCK_PTR_FOR_FN (cfun)) =
1249 0 : sum_edge_counts (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds);
1250 :
1251 : /* Compute edge probabilities. */
1252 0 : FOR_ALL_BB_FN (bb, cfun)
1253 : {
1254 0 : if (bb_gcov_count (bb))
1255 : {
1256 0 : FOR_EACH_EDGE (e, ei, bb->succs)
1257 0 : e->probability = profile_probability::probability_in_gcov_type
1258 0 : (edge_gcov_count (e), bb_gcov_count (bb));
1259 : }
1260 : }
1261 :
1262 0 : if (dump_file)
1263 : {
1264 0 : fprintf (dump_file, "\nCheck %s() CFG flow conservation:\n",
1265 : current_function_name ());
1266 0 : FOR_EACH_BB_FN (bb, cfun)
1267 : {
1268 0 : if ((bb_gcov_count (bb) != sum_edge_counts (bb->preds))
1269 0 : || (bb_gcov_count (bb) != sum_edge_counts (bb->succs)))
1270 : {
1271 0 : fprintf (dump_file,
1272 : "BB%d(%" PRId64 ") **INVALID**: ",
1273 0 : bb->index, bb_gcov_count (bb));
1274 0 : fprintf (stderr,
1275 : "******** BB%d(%" PRId64
1276 0 : ") **INVALID**: \n", bb->index, bb_gcov_count (bb));
1277 0 : fprintf (dump_file, "in_edges=%" PRId64 " ",
1278 : sum_edge_counts (bb->preds));
1279 0 : fprintf (dump_file, "out_edges=%" PRId64 "\n",
1280 : sum_edge_counts (bb->succs));
1281 : }
1282 : }
1283 : }
1284 0 : }
1285 :
1286 :
1287 : /* Implements the negative cycle canceling algorithm to compute a minimum cost
1288 : flow.
1289 : Algorithm:
1290 : 1. Find maximal flow.
1291 : 2. Form residual network
1292 : 3. Repeat:
1293 : While G contains a negative cost cycle C, reverse the flow on the found cycle
1294 : by the minimum residual capacity in that cycle.
1295 : 4. Form the minimal cost flow
1296 : f(u,v) = rf(v, u)
1297 : Input:
1298 : FIXUP_GRAPH - Initial fixup graph.
1299 : The flow field is modified to represent the minimum cost flow. */
1300 :
1301 : static void
1302 0 : find_minimum_cost_flow (fixup_graph_type *fixup_graph)
1303 : {
1304 : /* Holds the index of predecessor in path. */
1305 0 : int *pred;
1306 : /* Used to hold the minimum cost cycle. */
1307 0 : int *cycle;
1308 : /* Used to record the number of iterations of cancel_negative_cycle. */
1309 0 : int iteration;
1310 : /* Vector d[i] holds the minimum cost of path from i to sink. */
1311 0 : gcov_type *d;
1312 0 : int fnum_vertices;
1313 0 : int new_exit_index;
1314 0 : int new_entry_index;
1315 :
1316 0 : gcc_assert (fixup_graph);
1317 0 : fnum_vertices = fixup_graph->num_vertices;
1318 0 : new_exit_index = fixup_graph->new_exit_index;
1319 0 : new_entry_index = fixup_graph->new_entry_index;
1320 :
1321 0 : find_max_flow (fixup_graph, new_entry_index, new_exit_index);
1322 :
1323 : /* Initialize the structures for find_negative_cycle(). */
1324 0 : pred = (int *) xcalloc (fnum_vertices, sizeof (int));
1325 0 : d = (gcov_type *) xcalloc (fnum_vertices, sizeof (gcov_type));
1326 0 : cycle = (int *) xcalloc (fnum_vertices, sizeof (int));
1327 :
1328 : /* Repeatedly find and cancel negative cost cycles, until
1329 : no more negative cycles exist. This also updates the flow field
1330 : to represent the minimum cost flow so far. */
1331 0 : iteration = 0;
1332 0 : while (cancel_negative_cycle (fixup_graph, pred, d, cycle))
1333 : {
1334 0 : iteration++;
1335 0 : if (iteration > MAX_ITER (fixup_graph->num_vertices,
1336 : fixup_graph->num_edges))
1337 : break;
1338 : }
1339 :
1340 0 : if (dump_file)
1341 0 : dump_fixup_graph (dump_file, fixup_graph,
1342 : "After find_minimum_cost_flow()");
1343 :
1344 : /* Cleanup structures. */
1345 0 : free (pred);
1346 0 : free (d);
1347 0 : free (cycle);
1348 0 : }
1349 :
1350 :
1351 : /* Compute the sum of the edge counts in TO_EDGES. */
1352 :
1353 : gcov_type
1354 4888 : sum_edge_counts (vec<edge, va_gc> *to_edges)
1355 : {
1356 4888 : gcov_type sum = 0;
1357 4888 : edge e;
1358 4888 : edge_iterator ei;
1359 :
1360 11751 : FOR_EACH_EDGE (e, ei, to_edges)
1361 : {
1362 6863 : if (EDGE_INFO (e) && EDGE_INFO (e)->ignore)
1363 32 : continue;
1364 6831 : sum += edge_gcov_count (e);
1365 : }
1366 4888 : return sum;
1367 : }
1368 :
1369 :
1370 : /* Main routine. Smoothes the initial assigned basic block and edge counts using
1371 : a minimum cost flow algorithm, to ensure that the flow consistency rule is
1372 : obeyed: sum of outgoing edges = sum of incoming edges for each basic
1373 : block. */
1374 :
1375 : void
1376 0 : mcf_smooth_cfg (void)
1377 : {
1378 0 : fixup_graph_type fixup_graph;
1379 0 : memset (&fixup_graph, 0, sizeof (fixup_graph));
1380 0 : create_fixup_graph (&fixup_graph);
1381 0 : find_minimum_cost_flow (&fixup_graph);
1382 0 : adjust_cfg_counts (&fixup_graph);
1383 0 : delete_fixup_graph (&fixup_graph);
1384 0 : }
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