2 * Copyright 2010 INRIA Saclay
4 * Use of this software is governed by the GNU LGPLv2.1 license
6 * Written by Sven Verdoolaege, INRIA Saclay - Ile-de-France,
7 * Parc Club Orsay Universite, ZAC des vignes, 4 rue Jacques Monod,
12 #include "isl_map_private.h"
16 /* Given a map that represents a path with the length of the path
17 * encoded as the difference between the last output coordindate
18 * and the last input coordinate, set this length to either
19 * exactly "length" (if "exactly" is set) or at least "length"
20 * (if "exactly" is not set).
22 static __isl_give isl_map *set_path_length(__isl_take isl_map *map,
23 int exactly, int length)
26 struct isl_basic_map *bmap;
35 dim = isl_map_get_dim(map);
36 d = isl_dim_size(dim, isl_dim_in);
37 nparam = isl_dim_size(dim, isl_dim_param);
38 bmap = isl_basic_map_alloc_dim(dim, 0, 1, 1);
40 k = isl_basic_map_alloc_equality(bmap);
43 k = isl_basic_map_alloc_inequality(bmap);
48 isl_seq_clr(c, 1 + isl_basic_map_total_dim(bmap));
49 isl_int_set_si(c[0], -length);
50 isl_int_set_si(c[1 + nparam + d - 1], -1);
51 isl_int_set_si(c[1 + nparam + d + d - 1], 1);
53 bmap = isl_basic_map_finalize(bmap);
54 map = isl_map_intersect(map, isl_map_from_basic_map(bmap));
58 isl_basic_map_free(bmap);
63 /* Check whether the overapproximation of the power of "map" is exactly
64 * the power of "map". Let R be "map" and A_k the overapproximation.
65 * The approximation is exact if
68 * A_k = A_{k-1} \circ R k >= 2
70 * Since A_k is known to be an overapproximation, we only need to check
73 * A_k \subset A_{k-1} \circ R k >= 2
75 * In practice, "app" has an extra input and output coordinate
76 * to encode the length of the path. So, we first need to add
77 * this coordinate to "map" and set the length of the path to
80 static int check_power_exactness(__isl_take isl_map *map,
81 __isl_take isl_map *app)
87 map = isl_map_add(map, isl_dim_in, 1);
88 map = isl_map_add(map, isl_dim_out, 1);
89 map = set_path_length(map, 1, 1);
91 app_1 = set_path_length(isl_map_copy(app), 1, 1);
93 exact = isl_map_is_subset(app_1, map);
96 if (!exact || exact < 0) {
102 app_1 = set_path_length(isl_map_copy(app), 0, 1);
103 app_2 = set_path_length(app, 0, 2);
104 app_1 = isl_map_apply_range(map, app_1);
106 exact = isl_map_is_subset(app_2, app_1);
114 /* Check whether the overapproximation of the power of "map" is exactly
115 * the power of "map", possibly after projecting out the power (if "project"
118 * If "project" is set and if "steps" can only result in acyclic paths,
121 * A = R \cup (A \circ R)
123 * where A is the overapproximation with the power projected out, i.e.,
124 * an overapproximation of the transitive closure.
125 * More specifically, since A is known to be an overapproximation, we check
127 * A \subset R \cup (A \circ R)
129 * Otherwise, we check if the power is exact.
131 * Note that "app" has an extra input and output coordinate to encode
132 * the length of the part. If we are only interested in the transitive
133 * closure, then we can simply project out these coordinates first.
135 static int check_exactness(__isl_take isl_map *map, __isl_take isl_map *app,
143 return check_power_exactness(map, app);
145 d = isl_map_dim(map, isl_dim_in);
146 app = set_path_length(app, 0, 1);
147 app = isl_map_project_out(app, isl_dim_in, d, 1);
148 app = isl_map_project_out(app, isl_dim_out, d, 1);
150 test = isl_map_apply_range(isl_map_copy(map), isl_map_copy(app));
151 test = isl_map_union(test, isl_map_copy(map));
153 exact = isl_map_is_subset(app, test);
168 * The transitive closure implementation is based on the paper
169 * "Computing the Transitive Closure of a Union of Affine Integer
170 * Tuple Relations" by Anna Beletska, Denis Barthou, Wlodzimierz Bielecki and
174 /* Given a set of n offsets v_i (the rows of "steps"), construct a relation
175 * of the given dimension specification (Z^{n+1} -> Z^{n+1})
176 * that maps an element x to any element that can be reached
177 * by taking a non-negative number of steps along any of
178 * the extended offsets v'_i = [v_i 1].
181 * { [x] -> [y] : exists k_i >= 0, y = x + \sum_i k_i v'_i }
183 * For any element in this relation, the number of steps taken
184 * is equal to the difference in the final coordinates.
186 static __isl_give isl_map *path_along_steps(__isl_take isl_dim *dim,
187 __isl_keep isl_mat *steps)
190 struct isl_basic_map *path = NULL;
198 d = isl_dim_size(dim, isl_dim_in);
200 nparam = isl_dim_size(dim, isl_dim_param);
202 path = isl_basic_map_alloc_dim(isl_dim_copy(dim), n, d, n);
204 for (i = 0; i < n; ++i) {
205 k = isl_basic_map_alloc_div(path);
208 isl_assert(steps->ctx, i == k, goto error);
209 isl_int_set_si(path->div[k][0], 0);
212 for (i = 0; i < d; ++i) {
213 k = isl_basic_map_alloc_equality(path);
216 isl_seq_clr(path->eq[k], 1 + isl_basic_map_total_dim(path));
217 isl_int_set_si(path->eq[k][1 + nparam + i], 1);
218 isl_int_set_si(path->eq[k][1 + nparam + d + i], -1);
220 for (j = 0; j < n; ++j)
221 isl_int_set_si(path->eq[k][1 + nparam + 2 * d + j], 1);
223 for (j = 0; j < n; ++j)
224 isl_int_set(path->eq[k][1 + nparam + 2 * d + j],
228 for (i = 0; i < n; ++i) {
229 k = isl_basic_map_alloc_inequality(path);
232 isl_seq_clr(path->ineq[k], 1 + isl_basic_map_total_dim(path));
233 isl_int_set_si(path->ineq[k][1 + nparam + 2 * d + i], 1);
238 path = isl_basic_map_simplify(path);
239 path = isl_basic_map_finalize(path);
240 return isl_map_from_basic_map(path);
243 isl_basic_map_free(path);
252 /* Return PURE_PARAM if only the coefficients of the parameters are non-zero.
253 * Return PURE_VAR if only the coefficients of the set variables are non-zero.
254 * Return MIXED if only the coefficients of the parameters and the set
255 * variables are non-zero and if moreover the parametric constant
256 * can never attain positive values.
257 * Return IMPURE otherwise.
259 static int purity(__isl_keep isl_basic_set *bset, isl_int *c, int *div_purity,
270 n_div = isl_basic_set_dim(bset, isl_dim_div);
271 d = isl_basic_set_dim(bset, isl_dim_set);
272 nparam = isl_basic_set_dim(bset, isl_dim_param);
274 for (i = 0; i < n_div; ++i) {
275 if (isl_int_is_zero(c[1 + nparam + d + i]))
277 switch (div_purity[i]) {
278 case PURE_PARAM: p = 1; break;
279 case PURE_VAR: v = 1; break;
280 default: return IMPURE;
283 if (!p && isl_seq_first_non_zero(c + 1, nparam) == -1)
285 if (!v && isl_seq_first_non_zero(c + 1 + nparam, d) == -1)
290 bset = isl_basic_set_copy(bset);
291 bset = isl_basic_set_cow(bset);
292 bset = isl_basic_set_extend_constraints(bset, 0, 1);
293 k = isl_basic_set_alloc_inequality(bset);
296 isl_seq_clr(bset->ineq[k], 1 + isl_basic_set_total_dim(bset));
297 isl_seq_cpy(bset->ineq[k], c, 1 + nparam);
298 for (i = 0; i < n_div; ++i) {
299 if (div_purity[i] != PURE_PARAM)
301 isl_int_set(bset->ineq[k][1 + nparam + d + i],
302 c[1 + nparam + d + i]);
304 isl_int_sub_ui(bset->ineq[k][0], bset->ineq[k][0], 1);
305 empty = isl_basic_set_is_empty(bset);
306 isl_basic_set_free(bset);
308 return empty < 0 ? -1 : empty ? MIXED : IMPURE;
310 isl_basic_set_free(bset);
314 /* Return an array of integers indicating the type of each div in bset.
315 * If the div is (recursively) defined in terms of only the parameters,
316 * then the type is PURE_PARAM.
317 * If the div is (recursively) defined in terms of only the set variables,
318 * then the type is PURE_VAR.
319 * Otherwise, the type is IMPURE.
321 static __isl_give int *get_div_purity(__isl_keep isl_basic_set *bset)
332 n_div = isl_basic_set_dim(bset, isl_dim_div);
333 d = isl_basic_set_dim(bset, isl_dim_set);
334 nparam = isl_basic_set_dim(bset, isl_dim_param);
336 div_purity = isl_alloc_array(bset->ctx, int, n_div);
340 for (i = 0; i < bset->n_div; ++i) {
342 if (isl_int_is_zero(bset->div[i][0])) {
343 div_purity[i] = IMPURE;
346 if (isl_seq_first_non_zero(bset->div[i] + 2, nparam) != -1)
348 if (isl_seq_first_non_zero(bset->div[i] + 2 + nparam, d) != -1)
350 for (j = 0; j < i; ++j) {
351 if (isl_int_is_zero(bset->div[i][2 + nparam + d + j]))
353 switch (div_purity[j]) {
354 case PURE_PARAM: p = 1; break;
355 case PURE_VAR: v = 1; break;
356 default: p = v = 1; break;
359 div_purity[i] = v ? p ? IMPURE : PURE_VAR : PURE_PARAM;
365 /* Given a path with the as yet unconstrained length at position "pos",
366 * check if setting the length to zero results in only the identity
369 int empty_path_is_identity(__isl_keep isl_basic_map *path, unsigned pos)
371 isl_basic_map *test = NULL;
372 isl_basic_map *id = NULL;
376 test = isl_basic_map_copy(path);
377 test = isl_basic_map_extend_constraints(test, 1, 0);
378 k = isl_basic_map_alloc_equality(test);
381 isl_seq_clr(test->eq[k], 1 + isl_basic_map_total_dim(test));
382 isl_int_set_si(test->eq[k][pos], 1);
383 id = isl_basic_map_identity(isl_dim_domain(isl_basic_map_get_dim(path)));
384 is_id = isl_basic_map_is_subset(test, id);
385 isl_basic_map_free(test);
386 isl_basic_map_free(id);
389 isl_basic_map_free(test);
393 __isl_give isl_basic_map *add_delta_constraints(__isl_take isl_basic_map *path,
394 __isl_keep isl_basic_set *delta, unsigned off, unsigned nparam,
395 unsigned d, int *div_purity, int eq)
398 int n = eq ? delta->n_eq : delta->n_ineq;
399 isl_int **delta_c = eq ? delta->eq : delta->ineq;
400 isl_int **path_c = eq ? path->eq : path->ineq;
403 n_div = isl_basic_set_dim(delta, isl_dim_div);
405 for (i = 0; i < n; ++i) {
406 int p = purity(delta, delta_c[i], div_purity, eq);
412 k = isl_basic_map_alloc_equality(path);
414 k = isl_basic_map_alloc_inequality(path);
417 isl_seq_clr(path_c[k], 1 + isl_basic_map_total_dim(path));
419 isl_seq_cpy(path_c[k] + off,
420 delta_c[i] + 1 + nparam, d);
421 isl_int_set(path_c[k][off + d], delta_c[i][0]);
422 } else if (p == PURE_PARAM) {
423 isl_seq_cpy(path_c[k], delta_c[i], 1 + nparam);
425 isl_seq_cpy(path_c[k] + off,
426 delta_c[i] + 1 + nparam, d);
427 isl_seq_cpy(path_c[k], delta_c[i], 1 + nparam);
429 isl_seq_cpy(path_c[k] + off - n_div,
430 delta_c[i] + 1 + nparam + d, n_div);
435 isl_basic_map_free(path);
439 /* Given a set of offsets "delta", construct a relation of the
440 * given dimension specification (Z^{n+1} -> Z^{n+1}) that
441 * is an overapproximation of the relations that
442 * maps an element x to any element that can be reached
443 * by taking a non-negative number of steps along any of
444 * the elements in "delta".
445 * That is, construct an approximation of
447 * { [x] -> [y] : exists f \in \delta, k \in Z :
448 * y = x + k [f, 1] and k >= 0 }
450 * For any element in this relation, the number of steps taken
451 * is equal to the difference in the final coordinates.
453 * In particular, let delta be defined as
455 * \delta = [p] -> { [x] : A x + a >= and B p + b >= 0 and
456 * C x + C'p + c >= 0 and
457 * D x + D'p + d >= 0 }
459 * where the constraints C x + C'p + c >= 0 are such that the parametric
460 * constant term of each constraint j, "C_j x + C'_j p + c_j",
461 * can never attain positive values, then the relation is constructed as
463 * { [x] -> [y] : exists [f, k] \in Z^{n+1} : y = x + f and
464 * A f + k a >= 0 and B p + b >= 0 and
465 * C f + C'p + c >= 0 and k >= 1 }
466 * union { [x] -> [x] }
468 * If the zero-length paths happen to correspond exactly to the identity
469 * mapping, then we return
471 * { [x] -> [y] : exists [f, k] \in Z^{n+1} : y = x + f and
472 * A f + k a >= 0 and B p + b >= 0 and
473 * C f + C'p + c >= 0 and k >= 0 }
477 * Existentially quantified variables in \delta are handled by
478 * classifying them as independent of the parameters, purely
479 * parameter dependent and others. Constraints containing
480 * any of the other existentially quantified variables are removed.
481 * This is safe, but leads to an additional overapproximation.
483 static __isl_give isl_map *path_along_delta(__isl_take isl_dim *dim,
484 __isl_take isl_basic_set *delta)
486 isl_basic_map *path = NULL;
493 int *div_purity = NULL;
497 n_div = isl_basic_set_dim(delta, isl_dim_div);
498 d = isl_basic_set_dim(delta, isl_dim_set);
499 nparam = isl_basic_set_dim(delta, isl_dim_param);
500 path = isl_basic_map_alloc_dim(isl_dim_copy(dim), n_div + d + 1,
501 d + 1 + delta->n_eq, delta->n_ineq + 1);
502 off = 1 + nparam + 2 * (d + 1) + n_div;
504 for (i = 0; i < n_div + d + 1; ++i) {
505 k = isl_basic_map_alloc_div(path);
508 isl_int_set_si(path->div[k][0], 0);
511 for (i = 0; i < d + 1; ++i) {
512 k = isl_basic_map_alloc_equality(path);
515 isl_seq_clr(path->eq[k], 1 + isl_basic_map_total_dim(path));
516 isl_int_set_si(path->eq[k][1 + nparam + i], 1);
517 isl_int_set_si(path->eq[k][1 + nparam + d + 1 + i], -1);
518 isl_int_set_si(path->eq[k][off + i], 1);
521 div_purity = get_div_purity(delta);
525 path = add_delta_constraints(path, delta, off, nparam, d, div_purity, 1);
526 path = add_delta_constraints(path, delta, off, nparam, d, div_purity, 0);
528 is_id = empty_path_is_identity(path, off + d);
532 k = isl_basic_map_alloc_inequality(path);
535 isl_seq_clr(path->ineq[k], 1 + isl_basic_map_total_dim(path));
537 isl_int_set_si(path->ineq[k][0], -1);
538 isl_int_set_si(path->ineq[k][off + d], 1);
541 isl_basic_set_free(delta);
542 path = isl_basic_map_finalize(path);
545 return isl_map_from_basic_map(path);
547 return isl_basic_map_union(path,
548 isl_basic_map_identity(isl_dim_domain(dim)));
552 isl_basic_set_free(delta);
553 isl_basic_map_free(path);
557 /* Given a dimenion specification Z^{n+1} -> Z^{n+1} and a parameter "param",
558 * construct a map that equates the parameter to the difference
559 * in the final coordinates and imposes that this difference is positive.
562 * { [x,x_s] -> [y,y_s] : k = y_s - x_s > 0 }
564 static __isl_give isl_map *equate_parameter_to_length(__isl_take isl_dim *dim,
567 struct isl_basic_map *bmap;
572 d = isl_dim_size(dim, isl_dim_in);
573 nparam = isl_dim_size(dim, isl_dim_param);
574 bmap = isl_basic_map_alloc_dim(dim, 0, 1, 1);
575 k = isl_basic_map_alloc_equality(bmap);
578 isl_seq_clr(bmap->eq[k], 1 + isl_basic_map_total_dim(bmap));
579 isl_int_set_si(bmap->eq[k][1 + param], -1);
580 isl_int_set_si(bmap->eq[k][1 + nparam + d - 1], -1);
581 isl_int_set_si(bmap->eq[k][1 + nparam + d + d - 1], 1);
583 k = isl_basic_map_alloc_inequality(bmap);
586 isl_seq_clr(bmap->ineq[k], 1 + isl_basic_map_total_dim(bmap));
587 isl_int_set_si(bmap->ineq[k][1 + param], 1);
588 isl_int_set_si(bmap->ineq[k][0], -1);
590 bmap = isl_basic_map_finalize(bmap);
591 return isl_map_from_basic_map(bmap);
593 isl_basic_map_free(bmap);
597 /* Check whether "path" is acyclic, where the last coordinates of domain
598 * and range of path encode the number of steps taken.
599 * That is, check whether
601 * { d | d = y - x and (x,y) in path }
603 * does not contain any element with positive last coordinate (positive length)
604 * and zero remaining coordinates (cycle).
606 static int is_acyclic(__isl_take isl_map *path)
611 struct isl_set *delta;
613 delta = isl_map_deltas(path);
614 dim = isl_set_dim(delta, isl_dim_set);
615 for (i = 0; i < dim; ++i) {
617 delta = isl_set_lower_bound_si(delta, isl_dim_set, i, 1);
619 delta = isl_set_fix_si(delta, isl_dim_set, i, 0);
622 acyclic = isl_set_is_empty(delta);
628 /* Given a union of basic maps R = \cup_i R_i \subseteq D \times D
629 * and a dimension specification (Z^{n+1} -> Z^{n+1}),
630 * construct a map that is an overapproximation of the map
631 * that takes an element from the space D \times Z to another
632 * element from the same space, such that the first n coordinates of the
633 * difference between them is a sum of differences between images
634 * and pre-images in one of the R_i and such that the last coordinate
635 * is equal to the number of steps taken.
638 * \Delta_i = { y - x | (x, y) in R_i }
640 * then the constructed map is an overapproximation of
642 * { (x) -> (x + d) | \exists k_i >= 0, \delta_i \in \Delta_i :
643 * d = (\sum_i k_i \delta_i, \sum_i k_i) }
645 * The elements of the singleton \Delta_i's are collected as the
646 * rows of the steps matrix. For all these \Delta_i's together,
647 * a single path is constructed.
648 * For each of the other \Delta_i's, we compute an overapproximation
649 * of the paths along elements of \Delta_i.
650 * Since each of these paths performs an addition, composition is
651 * symmetric and we can simply compose all resulting paths in any order.
653 static __isl_give isl_map *construct_extended_path(__isl_take isl_dim *dim,
654 __isl_keep isl_map *map, int *project)
656 struct isl_mat *steps = NULL;
657 struct isl_map *path = NULL;
661 d = isl_map_dim(map, isl_dim_in);
663 path = isl_map_identity(isl_dim_domain(isl_dim_copy(dim)));
665 steps = isl_mat_alloc(map->ctx, map->n, d);
670 for (i = 0; i < map->n; ++i) {
671 struct isl_basic_set *delta;
673 delta = isl_basic_map_deltas(isl_basic_map_copy(map->p[i]));
675 for (j = 0; j < d; ++j) {
678 fixed = isl_basic_set_fast_dim_is_fixed(delta, j,
681 isl_basic_set_free(delta);
690 path = isl_map_apply_range(path,
691 path_along_delta(isl_dim_copy(dim), delta));
692 path = isl_map_coalesce(path);
694 isl_basic_set_free(delta);
701 path = isl_map_apply_range(path,
702 path_along_steps(isl_dim_copy(dim), steps));
705 if (project && *project) {
706 *project = is_acyclic(isl_map_copy(path));
721 /* Given a union of basic maps R = \cup_i R_i \subseteq D \times D
722 * and a dimension specification (Z^{n+1} -> Z^{n+1}),
723 * construct a map that is an overapproximation of the map
724 * that takes an element from the dom R \times Z to an
725 * element from ran R \times Z, such that the first n coordinates of the
726 * difference between them is a sum of differences between images
727 * and pre-images in one of the R_i and such that the last coordinate
728 * is equal to the number of steps taken.
731 * \Delta_i = { y - x | (x, y) in R_i }
733 * then the constructed map is an overapproximation of
735 * { (x) -> (x + d) | \exists k_i >= 1, \delta_i \in \Delta_i :
736 * d = (\sum_i k_i \delta_i, \sum_i k_i) and
737 * x in dom R and x + d in ran R }
739 static __isl_give isl_map *construct_component(__isl_take isl_dim *dim,
740 __isl_keep isl_map *map, int *exact, int project)
742 struct isl_set *domain = NULL;
743 struct isl_set *range = NULL;
744 struct isl_set *overlap;
745 struct isl_map *app = NULL;
746 struct isl_map *path = NULL;
748 domain = isl_map_domain(isl_map_copy(map));
749 domain = isl_set_coalesce(domain);
750 range = isl_map_range(isl_map_copy(map));
751 range = isl_set_coalesce(range);
752 overlap = isl_set_intersect(isl_set_copy(domain), isl_set_copy(range));
753 if (isl_set_is_empty(overlap) == 1) {
754 isl_set_free(domain);
756 isl_set_free(overlap);
759 map = isl_map_copy(map);
760 map = isl_map_add(map, isl_dim_in, 1);
761 map = isl_map_add(map, isl_dim_out, 1);
762 map = set_path_length(map, 1, 1);
765 isl_set_free(overlap);
766 app = isl_map_from_domain_and_range(domain, range);
767 app = isl_map_add(app, isl_dim_in, 1);
768 app = isl_map_add(app, isl_dim_out, 1);
770 path = construct_extended_path(isl_dim_copy(dim), map,
771 exact && *exact ? &project : NULL);
772 app = isl_map_intersect(app, path);
774 if (exact && *exact &&
775 (*exact = check_exactness(isl_map_copy(map), isl_map_copy(app),
780 app = set_path_length(app, 0, 1);
788 /* Structure for representing the nodes in the graph being traversed
789 * using Tarjan's algorithm.
790 * index represents the order in which nodes are visited.
791 * min_index is the index of the root of a (sub)component.
792 * on_stack indicates whether the node is currently on the stack.
794 struct basic_map_sort_node {
799 /* Structure for representing the graph being traversed
800 * using Tarjan's algorithm.
801 * len is the number of nodes
802 * node is an array of nodes
803 * stack contains the nodes on the path from the root to the current node
804 * sp is the stack pointer
805 * index is the index of the last node visited
806 * order contains the elements of the components separated by -1
807 * op represents the current position in order
809 struct basic_map_sort {
811 struct basic_map_sort_node *node;
819 static void basic_map_sort_free(struct basic_map_sort *s)
829 static struct basic_map_sort *basic_map_sort_alloc(struct isl_ctx *ctx, int len)
831 struct basic_map_sort *s;
834 s = isl_calloc_type(ctx, struct basic_map_sort);
838 s->node = isl_alloc_array(ctx, struct basic_map_sort_node, len);
841 for (i = 0; i < len; ++i)
842 s->node[i].index = -1;
843 s->stack = isl_alloc_array(ctx, int, len);
846 s->order = isl_alloc_array(ctx, int, 2 * len);
856 basic_map_sort_free(s);
860 /* Check whether in the computation of the transitive closure
861 * "bmap1" (R_1) should follow (or be part of the same component as)
864 * That is check whether
872 * If so, then there is no reason for R_1 to immediately follow R_2
875 static int basic_map_follows(__isl_keep isl_basic_map *bmap1,
876 __isl_keep isl_basic_map *bmap2)
878 struct isl_map *map12 = NULL;
879 struct isl_map *map21 = NULL;
882 map21 = isl_map_from_basic_map(
883 isl_basic_map_apply_range(
884 isl_basic_map_copy(bmap2),
885 isl_basic_map_copy(bmap1)));
886 subset = isl_map_is_empty(map21);
894 map12 = isl_map_from_basic_map(
895 isl_basic_map_apply_range(
896 isl_basic_map_copy(bmap1),
897 isl_basic_map_copy(bmap2)));
899 subset = isl_map_is_subset(map21, map12);
904 return subset < 0 ? -1 : !subset;
910 /* Perform Tarjan's algorithm for computing the strongly connected components
911 * in the graph with the disjuncts of "map" as vertices and with an
912 * edge between any pair of disjuncts such that the first has
913 * to be applied after the second.
915 static int power_components_tarjan(struct basic_map_sort *s,
916 __isl_keep isl_map *map, int i)
920 s->node[i].index = s->index;
921 s->node[i].min_index = s->index;
922 s->node[i].on_stack = 1;
924 s->stack[s->sp++] = i;
926 for (j = s->len - 1; j >= 0; --j) {
931 if (s->node[j].index >= 0 &&
932 (!s->node[j].on_stack ||
933 s->node[j].index > s->node[i].min_index))
936 f = basic_map_follows(map->p[i], map->p[j]);
942 if (s->node[j].index < 0) {
943 power_components_tarjan(s, map, j);
944 if (s->node[j].min_index < s->node[i].min_index)
945 s->node[i].min_index = s->node[j].min_index;
946 } else if (s->node[j].index < s->node[i].min_index)
947 s->node[i].min_index = s->node[j].index;
950 if (s->node[i].index != s->node[i].min_index)
954 j = s->stack[--s->sp];
955 s->node[j].on_stack = 0;
956 s->order[s->op++] = j;
958 s->order[s->op++] = -1;
963 /* Given a union of basic maps R = \cup_i R_i \subseteq D \times D
964 * and a dimension specification (Z^{n+1} -> Z^{n+1}),
965 * construct a map that is an overapproximation of the map
966 * that takes an element from the dom R \times Z to an
967 * element from ran R \times Z, such that the first n coordinates of the
968 * difference between them is a sum of differences between images
969 * and pre-images in one of the R_i and such that the last coordinate
970 * is equal to the number of steps taken.
973 * \Delta_i = { y - x | (x, y) in R_i }
975 * then the constructed map is an overapproximation of
977 * { (x) -> (x + d) | \exists k_i >= 0, \delta_i \in \Delta_i :
978 * d = (\sum_i k_i \delta_i, \sum_i k_i) and
979 * x in dom R and x + d in ran R }
981 * We first split the map into strongly connected components, perform
982 * the above on each component and then join the results in the correct
983 * order, at each join also taking in the union of both arguments
984 * to allow for paths that do not go through one of the two arguments.
986 static __isl_give isl_map *construct_power_components(__isl_take isl_dim *dim,
987 __isl_keep isl_map *map, int *exact, int project)
990 struct isl_map *path = NULL;
991 struct basic_map_sort *s = NULL;
996 return construct_component(dim, map, exact, project);
998 s = basic_map_sort_alloc(map->ctx, map->n);
1001 for (i = map->n - 1; i >= 0; --i) {
1002 if (s->node[i].index >= 0)
1004 if (power_components_tarjan(s, map, i) < 0)
1010 path = isl_map_empty(isl_dim_copy(dim));
1012 struct isl_map *comp;
1013 isl_map *path_comp, *path_comb;
1014 comp = isl_map_alloc_dim(isl_map_get_dim(map), n, 0);
1015 while (s->order[i] != -1) {
1016 comp = isl_map_add_basic_map(comp,
1017 isl_basic_map_copy(map->p[s->order[i]]));
1021 path_comp = construct_component(isl_dim_copy(dim), comp,
1023 path_comb = isl_map_apply_range(isl_map_copy(path),
1024 isl_map_copy(path_comp));
1025 path = isl_map_union(path, path_comp);
1026 path = isl_map_union(path, path_comb);
1031 basic_map_sort_free(s);
1036 basic_map_sort_free(s);
1041 /* Given a union of basic maps R = \cup_i R_i \subseteq D \times D,
1042 * construct a map that is an overapproximation of the map
1043 * that takes an element from the space D to another
1044 * element from the same space, such that the difference between
1045 * them is a strictly positive sum of differences between images
1046 * and pre-images in one of the R_i.
1047 * The number of differences in the sum is equated to parameter "param".
1050 * \Delta_i = { y - x | (x, y) in R_i }
1052 * then the constructed map is an overapproximation of
1054 * { (x) -> (x + d) | \exists k_i >= 0, \delta_i \in \Delta_i :
1055 * d = \sum_i k_i \delta_i and k = \sum_i k_i > 0 }
1058 * { (x) -> (x + d) | \exists k_i >= 0, \delta_i \in \Delta_i :
1059 * d = \sum_i k_i \delta_i and \sum_i k_i > 0 }
1061 * if "project" is set.
1063 * We first construct an extended mapping with an extra coordinate
1064 * that indicates the number of steps taken. In particular,
1065 * the difference in the last coordinate is equal to the number
1066 * of steps taken to move from a domain element to the corresponding
1068 * In the final step, this difference is equated to the parameter "param"
1069 * and made positive (unless project is set).
1070 * The extra coordinates are subsequently projected out.
1072 static __isl_give isl_map *construct_power(__isl_keep isl_map *map,
1073 unsigned param, int *exact, int project)
1075 struct isl_map *app = NULL;
1076 struct isl_map *diff;
1077 struct isl_dim *dim = NULL;
1083 dim = isl_map_get_dim(map);
1085 d = isl_dim_size(dim, isl_dim_in);
1086 dim = isl_dim_add(dim, isl_dim_in, 1);
1087 dim = isl_dim_add(dim, isl_dim_out, 1);
1089 app = construct_power_components(isl_dim_copy(dim), map,
1095 diff = equate_parameter_to_length(dim, param);
1096 app = isl_map_intersect(app, diff);
1098 app = isl_map_project_out(app, isl_dim_in, d, 1);
1099 app = isl_map_project_out(app, isl_dim_out, d, 1);
1104 /* Compute the positive powers of "map", or an overapproximation.
1105 * The power is given by parameter "param". If the result is exact,
1106 * then *exact is set to 1.
1108 * If project is set, then we are actually interested in the transitive
1109 * closure, so we can use a more relaxed exactness check.
1110 * The lengths of the paths are also projected out instead of being
1111 * equated to "param" (which is then ignored in this case).
1113 static __isl_give isl_map *map_power(__isl_take isl_map *map, unsigned param,
1114 int *exact, int project)
1116 struct isl_map *app = NULL;
1121 map = isl_map_coalesce(map);
1125 if (isl_map_fast_is_empty(map))
1128 isl_assert(map->ctx, project || param < isl_map_dim(map, isl_dim_param),
1130 isl_assert(map->ctx,
1131 isl_map_dim(map, isl_dim_in) == isl_map_dim(map, isl_dim_out),
1134 app = construct_power(map, param, exact, project);
1144 /* Compute the positive powers of "map", or an overapproximation.
1145 * The power is given by parameter "param". If the result is exact,
1146 * then *exact is set to 1.
1148 __isl_give isl_map *isl_map_power(__isl_take isl_map *map, unsigned param,
1151 return map_power(map, param, exact, 0);
1154 /* Check whether equality i of bset is a pure stride constraint
1155 * on a single dimensions, i.e., of the form
1159 * with k a constant and e an existentially quantified variable.
1161 static int is_eq_stride(__isl_keep isl_basic_set *bset, int i)
1173 if (!isl_int_is_zero(bset->eq[i][0]))
1176 nparam = isl_basic_set_dim(bset, isl_dim_param);
1177 d = isl_basic_set_dim(bset, isl_dim_set);
1178 n_div = isl_basic_set_dim(bset, isl_dim_div);
1180 if (isl_seq_first_non_zero(bset->eq[i] + 1, nparam) != -1)
1182 pos1 = isl_seq_first_non_zero(bset->eq[i] + 1 + nparam, d);
1185 if (isl_seq_first_non_zero(bset->eq[i] + 1 + nparam + pos1 + 1,
1186 d - pos1 - 1) != -1)
1189 pos2 = isl_seq_first_non_zero(bset->eq[i] + 1 + nparam + d, n_div);
1192 if (isl_seq_first_non_zero(bset->eq[i] + 1 + nparam + d + pos2 + 1,
1193 n_div - pos2 - 1) != -1)
1195 if (!isl_int_is_one(bset->eq[i][1 + nparam + pos1]) &&
1196 !isl_int_is_negone(bset->eq[i][1 + nparam + pos1]))
1202 /* Given a map, compute the smallest superset of this map that is of the form
1204 * { i -> j : L <= j - i <= U and exists a_p: j_p - i_p = M_p a_p }
1206 * (where p ranges over the (non-parametric) dimensions),
1207 * compute the transitive closure of this map, i.e.,
1209 * { i -> j : exists k > 0:
1210 * k L <= j - i <= k U and exists a: j_p - i_p = M_p a_p }
1212 * and intersect domain and range of this transitive closure with
1213 * domain and range of the original map.
1215 * If with_id is set, then try to include as much of the identity mapping
1216 * as possible, by computing
1218 * { i -> j : exists k >= 0:
1219 * k L <= j - i <= k U and exists a: j_p - i_p = M_p a_p }
1221 * instead (i.e., allow k = 0) and by intersecting domain and range
1222 * with the union of the domain and the range of the original map.
1224 * In practice, we compute the difference set
1226 * delta = { j - i | i -> j in map },
1228 * look for stride constraint on the individual dimensions and compute
1229 * (constant) lower and upper bounds for each individual dimension,
1230 * adding a constraint for each bound not equal to infinity.
1232 static __isl_give isl_map *box_closure(__isl_take isl_map *map, int with_id)
1241 isl_set *domain = NULL;
1242 isl_set *range = NULL;
1243 isl_map *app = NULL;
1244 isl_basic_set *aff = NULL;
1245 isl_basic_map *bmap = NULL;
1246 isl_vec *obj = NULL;
1251 delta = isl_map_deltas(isl_map_copy(map));
1253 aff = isl_set_affine_hull(isl_set_copy(delta));
1256 dim = isl_map_get_dim(map);
1257 d = isl_dim_size(dim, isl_dim_in);
1258 nparam = isl_dim_size(dim, isl_dim_param);
1259 total = isl_dim_total(dim);
1260 bmap = isl_basic_map_alloc_dim(dim,
1261 aff->n_div + 1, aff->n_div, 2 * d + 1);
1262 for (i = 0; i < aff->n_div + 1; ++i) {
1263 k = isl_basic_map_alloc_div(bmap);
1266 isl_int_set_si(bmap->div[k][0], 0);
1268 for (i = 0; i < aff->n_eq; ++i) {
1269 if (!is_eq_stride(aff, i))
1271 k = isl_basic_map_alloc_equality(bmap);
1274 isl_seq_clr(bmap->eq[k], 1 + nparam);
1275 isl_seq_cpy(bmap->eq[k] + 1 + nparam + d,
1276 aff->eq[i] + 1 + nparam, d);
1277 isl_seq_neg(bmap->eq[k] + 1 + nparam,
1278 aff->eq[i] + 1 + nparam, d);
1279 isl_seq_cpy(bmap->eq[k] + 1 + nparam + 2 * d,
1280 aff->eq[i] + 1 + nparam + d, aff->n_div);
1281 isl_int_set_si(bmap->eq[k][1 + total + aff->n_div], 0);
1283 obj = isl_vec_alloc(map->ctx, 1 + nparam + d);
1286 isl_seq_clr(obj->el, 1 + nparam + d);
1287 for (i = 0; i < d; ++ i) {
1288 enum isl_lp_result res;
1290 isl_int_set_si(obj->el[1 + nparam + i], 1);
1292 res = isl_set_solve_lp(delta, 0, obj->el, map->ctx->one, &opt,
1294 if (res == isl_lp_error)
1296 if (res == isl_lp_ok) {
1297 k = isl_basic_map_alloc_inequality(bmap);
1300 isl_seq_clr(bmap->ineq[k],
1301 1 + nparam + 2 * d + bmap->n_div);
1302 isl_int_set_si(bmap->ineq[k][1 + nparam + i], -1);
1303 isl_int_set_si(bmap->ineq[k][1 + nparam + d + i], 1);
1304 isl_int_neg(bmap->ineq[k][1 + nparam + 2 * d + aff->n_div], opt);
1307 res = isl_set_solve_lp(delta, 1, obj->el, map->ctx->one, &opt,
1309 if (res == isl_lp_error)
1311 if (res == isl_lp_ok) {
1312 k = isl_basic_map_alloc_inequality(bmap);
1315 isl_seq_clr(bmap->ineq[k],
1316 1 + nparam + 2 * d + bmap->n_div);
1317 isl_int_set_si(bmap->ineq[k][1 + nparam + i], 1);
1318 isl_int_set_si(bmap->ineq[k][1 + nparam + d + i], -1);
1319 isl_int_set(bmap->ineq[k][1 + nparam + 2 * d + aff->n_div], opt);
1322 isl_int_set_si(obj->el[1 + nparam + i], 0);
1324 k = isl_basic_map_alloc_inequality(bmap);
1327 isl_seq_clr(bmap->ineq[k],
1328 1 + nparam + 2 * d + bmap->n_div);
1330 isl_int_set_si(bmap->ineq[k][0], -1);
1331 isl_int_set_si(bmap->ineq[k][1 + nparam + 2 * d + aff->n_div], 1);
1333 domain = isl_map_domain(isl_map_copy(map));
1334 domain = isl_set_coalesce(domain);
1335 range = isl_map_range(isl_map_copy(map));
1336 range = isl_set_coalesce(range);
1338 domain = isl_set_union(domain, range);
1339 domain = isl_set_coalesce(domain);
1340 range = isl_set_copy(domain);
1342 app = isl_map_from_domain_and_range(domain, range);
1345 isl_basic_set_free(aff);
1347 bmap = isl_basic_map_finalize(bmap);
1348 isl_set_free(delta);
1351 map = isl_map_from_basic_map(bmap);
1352 map = isl_map_intersect(map, app);
1357 isl_basic_map_free(bmap);
1358 isl_basic_set_free(aff);
1360 isl_set_free(delta);
1365 /* Check whether app is the transitive closure of map.
1366 * In particular, check that app is acyclic and, if so,
1369 * app \subset (map \cup (map \circ app))
1371 static int check_exactness_omega(__isl_keep isl_map *map,
1372 __isl_keep isl_map *app)
1376 int is_empty, is_exact;
1380 delta = isl_map_deltas(isl_map_copy(app));
1381 d = isl_set_dim(delta, isl_dim_set);
1382 for (i = 0; i < d; ++i)
1383 delta = isl_set_fix_si(delta, isl_dim_set, i, 0);
1384 is_empty = isl_set_is_empty(delta);
1385 isl_set_free(delta);
1391 test = isl_map_apply_range(isl_map_copy(app), isl_map_copy(map));
1392 test = isl_map_union(test, isl_map_copy(map));
1393 is_exact = isl_map_is_subset(app, test);
1399 /* Check if basic map M_i can be combined with all the other
1400 * basic maps such that
1404 * can be computed as
1406 * M_i \cup (\cup_{j \ne i} M_i^* \circ M_j \circ M_i^*)^+
1408 * In particular, check if we can compute a compact representation
1411 * M_i^* \circ M_j \circ M_i^*
1414 * Let M_i^? be an extension of M_i^+ that allows paths
1415 * of length zero, i.e., the result of box_closure(., 1).
1416 * The criterion, as proposed by Kelly et al., is that
1417 * id = M_i^? - M_i^+ can be represented as a basic map
1420 * id \circ M_j \circ id = M_j
1424 * If this function returns 1, then tc and qc are set to
1425 * M_i^+ and M_i^?, respectively.
1427 static int can_be_split_off(__isl_keep isl_map *map, int i,
1428 __isl_give isl_map **tc, __isl_give isl_map **qc)
1430 isl_map *map_i, *id;
1433 map_i = isl_map_from_basic_map(isl_basic_map_copy(map->p[i]));
1434 *tc = box_closure(isl_map_copy(map_i), 0);
1435 *qc = box_closure(map_i, 1);
1436 id = isl_map_subtract(isl_map_copy(*qc), isl_map_copy(*tc));
1440 if (id->n != 1 || (*qc)->n != 1)
1443 for (j = 0; j < map->n; ++j) {
1444 isl_map *map_j, *test;
1449 map_j = isl_map_from_basic_map(
1450 isl_basic_map_copy(map->p[j]));
1451 test = isl_map_apply_range(isl_map_copy(id),
1452 isl_map_copy(map_j));
1453 test = isl_map_apply_range(test, isl_map_copy(id));
1454 is_ok = isl_map_is_equal(test, map_j);
1455 isl_map_free(map_j);
1483 /* Compute an overapproximation of the transitive closure of "map"
1484 * using a variation of the algorithm from
1485 * "Transitive Closure of Infinite Graphs and its Applications"
1488 * We first check whether we can can split of any basic map M_i and
1495 * M_i \cup (\cup_{j \ne i} M_i^* \circ M_j \circ M_i^*)^+
1497 * using a recursive call on the remaining map.
1499 * If not, we simply call box_closure on the whole map.
1501 static __isl_give isl_map *compute_closure_omega(__isl_take isl_map *map)
1508 return box_closure(map, 0);
1510 map = isl_map_cow(map);
1514 for (i = 0; i < map->n; ++i) {
1517 ok = can_be_split_off(map, i, &tc, &qc);
1523 isl_basic_map_free(map->p[i]);
1524 if (i != map->n - 1)
1525 map->p[i] = map->p[map->n - 1];
1528 map = isl_map_apply_range(isl_map_copy(qc), map);
1529 map = isl_map_apply_range(map, qc);
1531 return isl_map_union(tc, compute_closure_omega(map));
1534 return box_closure(map, 0);
1540 /* Compute an overapproximation of the transitive closure of "map"
1541 * using a variation of the algorithm from
1542 * "Transitive Closure of Infinite Graphs and its Applications"
1543 * by Kelly et al. and check whether the result is definitely exact.
1545 static __isl_give isl_map *transitive_closure_omega(__isl_take isl_map *map,
1550 app = compute_closure_omega(isl_map_copy(map));
1553 *exact = check_exactness_omega(map, app);
1559 /* Compute the transitive closure of "map", or an overapproximation.
1560 * If the result is exact, then *exact is set to 1.
1561 * Simply use map_power to compute the powers of map, but tell
1562 * it to project out the lengths of the paths instead of equating
1563 * the length to a parameter.
1565 __isl_give isl_map *isl_map_transitive_closure(__isl_take isl_map *map,
1573 if (map->ctx->opt->closure == ISL_CLOSURE_OMEGA)
1574 return transitive_closure_omega(map, exact);
1576 param = isl_map_dim(map, isl_dim_param);
1577 map = map_power(map, param, exact, 1);