2 * Copyright 2008-2009 Katholieke Universiteit Leuven
4 * Use of this software is governed by the GNU LGPLv2.1 license
6 * Written by Sven Verdoolaege, K.U.Leuven, Departement
7 * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
12 #include "isl_map_private.h"
16 #include "isl_equalities.h"
19 static struct isl_basic_set *uset_convex_hull_wrap_bounded(struct isl_set *set);
21 static void swap_ineq(struct isl_basic_map *bmap, unsigned i, unsigned j)
27 bmap->ineq[i] = bmap->ineq[j];
32 /* Return 1 if constraint c is redundant with respect to the constraints
33 * in bmap. If c is a lower [upper] bound in some variable and bmap
34 * does not have a lower [upper] bound in that variable, then c cannot
35 * be redundant and we do not need solve any lp.
37 int isl_basic_map_constraint_is_redundant(struct isl_basic_map **bmap,
38 isl_int *c, isl_int *opt_n, isl_int *opt_d)
40 enum isl_lp_result res;
47 total = isl_basic_map_total_dim(*bmap);
48 for (i = 0; i < total; ++i) {
50 if (isl_int_is_zero(c[1+i]))
52 sign = isl_int_sgn(c[1+i]);
53 for (j = 0; j < (*bmap)->n_ineq; ++j)
54 if (sign == isl_int_sgn((*bmap)->ineq[j][1+i]))
56 if (j == (*bmap)->n_ineq)
62 res = isl_basic_map_solve_lp(*bmap, 0, c, (*bmap)->ctx->one,
64 if (res == isl_lp_unbounded)
66 if (res == isl_lp_error)
68 if (res == isl_lp_empty) {
69 *bmap = isl_basic_map_set_to_empty(*bmap);
72 return !isl_int_is_neg(*opt_n);
75 int isl_basic_set_constraint_is_redundant(struct isl_basic_set **bset,
76 isl_int *c, isl_int *opt_n, isl_int *opt_d)
78 return isl_basic_map_constraint_is_redundant(
79 (struct isl_basic_map **)bset, c, opt_n, opt_d);
82 /* Compute the convex hull of a basic map, by removing the redundant
83 * constraints. If the minimal value along the normal of a constraint
84 * is the same if the constraint is removed, then the constraint is redundant.
86 * Alternatively, we could have intersected the basic map with the
87 * corresponding equality and the checked if the dimension was that
90 struct isl_basic_map *isl_basic_map_convex_hull(struct isl_basic_map *bmap)
97 bmap = isl_basic_map_gauss(bmap, NULL);
98 if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_EMPTY))
100 if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_NO_REDUNDANT))
102 if (bmap->n_ineq <= 1)
105 tab = isl_tab_from_basic_map(bmap);
106 tab = isl_tab_detect_implicit_equalities(tab);
107 if (isl_tab_detect_redundant(tab) < 0)
109 bmap = isl_basic_map_update_from_tab(bmap, tab);
111 ISL_F_SET(bmap, ISL_BASIC_MAP_NO_IMPLICIT);
112 ISL_F_SET(bmap, ISL_BASIC_MAP_NO_REDUNDANT);
116 isl_basic_map_free(bmap);
120 struct isl_basic_set *isl_basic_set_convex_hull(struct isl_basic_set *bset)
122 return (struct isl_basic_set *)
123 isl_basic_map_convex_hull((struct isl_basic_map *)bset);
126 /* Check if the set set is bound in the direction of the affine
127 * constraint c and if so, set the constant term such that the
128 * resulting constraint is a bounding constraint for the set.
130 static int uset_is_bound(struct isl_set *set, isl_int *c, unsigned len)
138 isl_int_init(opt_denom);
140 for (j = 0; j < set->n; ++j) {
141 enum isl_lp_result res;
143 if (ISL_F_ISSET(set->p[j], ISL_BASIC_SET_EMPTY))
146 res = isl_basic_set_solve_lp(set->p[j],
147 0, c, set->ctx->one, &opt, &opt_denom, NULL);
148 if (res == isl_lp_unbounded)
150 if (res == isl_lp_error)
152 if (res == isl_lp_empty) {
153 set->p[j] = isl_basic_set_set_to_empty(set->p[j]);
158 if (first || isl_int_is_neg(opt)) {
159 if (!isl_int_is_one(opt_denom))
160 isl_seq_scale(c, c, opt_denom, len);
161 isl_int_sub(c[0], c[0], opt);
166 isl_int_clear(opt_denom);
170 isl_int_clear(opt_denom);
174 struct isl_basic_set *isl_basic_set_set_rational(struct isl_basic_set *bset)
179 if (ISL_F_ISSET(bset, ISL_BASIC_MAP_RATIONAL))
182 bset = isl_basic_set_cow(bset);
186 ISL_F_SET(bset, ISL_BASIC_MAP_RATIONAL);
188 return isl_basic_set_finalize(bset);
191 static struct isl_set *isl_set_set_rational(struct isl_set *set)
195 set = isl_set_cow(set);
198 for (i = 0; i < set->n; ++i) {
199 set->p[i] = isl_basic_set_set_rational(set->p[i]);
209 static struct isl_basic_set *isl_basic_set_add_equality(
210 struct isl_basic_set *bset, isl_int *c)
215 if (ISL_F_ISSET(bset, ISL_BASIC_SET_EMPTY))
218 isl_assert(bset->ctx, isl_basic_set_n_param(bset) == 0, goto error);
219 isl_assert(bset->ctx, bset->n_div == 0, goto error);
220 dim = isl_basic_set_n_dim(bset);
221 bset = isl_basic_set_cow(bset);
222 bset = isl_basic_set_extend(bset, 0, dim, 0, 1, 0);
223 i = isl_basic_set_alloc_equality(bset);
226 isl_seq_cpy(bset->eq[i], c, 1 + dim);
229 isl_basic_set_free(bset);
233 static struct isl_set *isl_set_add_basic_set_equality(struct isl_set *set, isl_int *c)
237 set = isl_set_cow(set);
240 for (i = 0; i < set->n; ++i) {
241 set->p[i] = isl_basic_set_add_equality(set->p[i], c);
251 /* Given a union of basic sets, construct the constraints for wrapping
252 * a facet around one of its ridges.
253 * In particular, if each of n the d-dimensional basic sets i in "set"
254 * contains the origin, satisfies the constraints x_1 >= 0 and x_2 >= 0
255 * and is defined by the constraints
259 * then the resulting set is of dimension n*(1+d) and has as constraints
268 static struct isl_basic_set *wrap_constraints(struct isl_set *set)
270 struct isl_basic_set *lp;
274 unsigned dim, lp_dim;
279 dim = 1 + isl_set_n_dim(set);
282 for (i = 0; i < set->n; ++i) {
283 n_eq += set->p[i]->n_eq;
284 n_ineq += set->p[i]->n_ineq;
286 lp = isl_basic_set_alloc(set->ctx, 0, dim * set->n, 0, n_eq, n_ineq);
289 lp_dim = isl_basic_set_n_dim(lp);
290 k = isl_basic_set_alloc_equality(lp);
291 isl_int_set_si(lp->eq[k][0], -1);
292 for (i = 0; i < set->n; ++i) {
293 isl_int_set_si(lp->eq[k][1+dim*i], 0);
294 isl_int_set_si(lp->eq[k][1+dim*i+1], 1);
295 isl_seq_clr(lp->eq[k]+1+dim*i+2, dim-2);
297 for (i = 0; i < set->n; ++i) {
298 k = isl_basic_set_alloc_inequality(lp);
299 isl_seq_clr(lp->ineq[k], 1+lp_dim);
300 isl_int_set_si(lp->ineq[k][1+dim*i], 1);
302 for (j = 0; j < set->p[i]->n_eq; ++j) {
303 k = isl_basic_set_alloc_equality(lp);
304 isl_seq_clr(lp->eq[k], 1+dim*i);
305 isl_seq_cpy(lp->eq[k]+1+dim*i, set->p[i]->eq[j], dim);
306 isl_seq_clr(lp->eq[k]+1+dim*(i+1), dim*(set->n-i-1));
309 for (j = 0; j < set->p[i]->n_ineq; ++j) {
310 k = isl_basic_set_alloc_inequality(lp);
311 isl_seq_clr(lp->ineq[k], 1+dim*i);
312 isl_seq_cpy(lp->ineq[k]+1+dim*i, set->p[i]->ineq[j], dim);
313 isl_seq_clr(lp->ineq[k]+1+dim*(i+1), dim*(set->n-i-1));
319 /* Given a facet "facet" of the convex hull of "set" and a facet "ridge"
320 * of that facet, compute the other facet of the convex hull that contains
323 * We first transform the set such that the facet constraint becomes
327 * I.e., the facet lies in
331 * and on that facet, the constraint that defines the ridge is
335 * (This transformation is not strictly needed, all that is needed is
336 * that the ridge contains the origin.)
338 * Since the ridge contains the origin, the cone of the convex hull
339 * will be of the form
344 * with this second constraint defining the new facet.
345 * The constant a is obtained by settting x_1 in the cone of the
346 * convex hull to 1 and minimizing x_2.
347 * Now, each element in the cone of the convex hull is the sum
348 * of elements in the cones of the basic sets.
349 * If a_i is the dilation factor of basic set i, then the problem
350 * we need to solve is
363 * the constraints of each (transformed) basic set.
364 * If a = n/d, then the constraint defining the new facet (in the transformed
367 * -n x_1 + d x_2 >= 0
369 * In the original space, we need to take the same combination of the
370 * corresponding constraints "facet" and "ridge".
372 * If a = -infty = "-1/0", then we just return the original facet constraint.
373 * This means that the facet is unbounded, but has a bounded intersection
374 * with the union of sets.
376 isl_int *isl_set_wrap_facet(__isl_keep isl_set *set,
377 isl_int *facet, isl_int *ridge)
380 struct isl_mat *T = NULL;
381 struct isl_basic_set *lp = NULL;
383 enum isl_lp_result res;
387 set = isl_set_copy(set);
388 set = isl_set_set_rational(set);
390 dim = 1 + isl_set_n_dim(set);
391 T = isl_mat_alloc(set->ctx, 3, dim);
394 isl_int_set_si(T->row[0][0], 1);
395 isl_seq_clr(T->row[0]+1, dim - 1);
396 isl_seq_cpy(T->row[1], facet, dim);
397 isl_seq_cpy(T->row[2], ridge, dim);
398 T = isl_mat_right_inverse(T);
399 set = isl_set_preimage(set, T);
403 lp = wrap_constraints(set);
404 obj = isl_vec_alloc(set->ctx, 1 + dim*set->n);
407 isl_int_set_si(obj->block.data[0], 0);
408 for (i = 0; i < set->n; ++i) {
409 isl_seq_clr(obj->block.data + 1 + dim*i, 2);
410 isl_int_set_si(obj->block.data[1 + dim*i+2], 1);
411 isl_seq_clr(obj->block.data + 1 + dim*i+3, dim-3);
415 res = isl_basic_set_solve_lp(lp, 0,
416 obj->block.data, set->ctx->one, &num, &den, NULL);
417 if (res == isl_lp_ok) {
418 isl_int_neg(num, num);
419 isl_seq_combine(facet, num, facet, den, ridge, dim);
424 isl_basic_set_free(lp);
426 isl_assert(set->ctx, res == isl_lp_ok || res == isl_lp_unbounded,
430 isl_basic_set_free(lp);
436 /* Compute the constraint of a facet of "set".
438 * We first compute the intersection with a bounding constraint
439 * that is orthogonal to one of the coordinate axes.
440 * If the affine hull of this intersection has only one equality,
441 * we have found a facet.
442 * Otherwise, we wrap the current bounding constraint around
443 * one of the equalities of the face (one that is not equal to
444 * the current bounding constraint).
445 * This process continues until we have found a facet.
446 * The dimension of the intersection increases by at least
447 * one on each iteration, so termination is guaranteed.
449 static __isl_give isl_mat *initial_facet_constraint(__isl_keep isl_set *set)
451 struct isl_set *slice = NULL;
452 struct isl_basic_set *face = NULL;
454 unsigned dim = isl_set_n_dim(set);
458 isl_assert(set->ctx, set->n > 0, goto error);
459 bounds = isl_mat_alloc(set->ctx, 1, 1 + dim);
463 isl_seq_clr(bounds->row[0], dim);
464 isl_int_set_si(bounds->row[0][1 + dim - 1], 1);
465 is_bound = uset_is_bound(set, bounds->row[0], 1 + dim);
466 isl_assert(set->ctx, is_bound == 1, goto error);
467 isl_seq_normalize(set->ctx, bounds->row[0], 1 + dim);
471 slice = isl_set_copy(set);
472 slice = isl_set_add_basic_set_equality(slice, bounds->row[0]);
473 face = isl_set_affine_hull(slice);
476 if (face->n_eq == 1) {
477 isl_basic_set_free(face);
480 for (i = 0; i < face->n_eq; ++i)
481 if (!isl_seq_eq(bounds->row[0], face->eq[i], 1 + dim) &&
482 !isl_seq_is_neg(bounds->row[0],
483 face->eq[i], 1 + dim))
485 isl_assert(set->ctx, i < face->n_eq, goto error);
486 if (!isl_set_wrap_facet(set, bounds->row[0], face->eq[i]))
488 isl_seq_normalize(set->ctx, bounds->row[0], bounds->n_col);
489 isl_basic_set_free(face);
494 isl_basic_set_free(face);
495 isl_mat_free(bounds);
499 /* Given the bounding constraint "c" of a facet of the convex hull of "set",
500 * compute a hyperplane description of the facet, i.e., compute the facets
503 * We compute an affine transformation that transforms the constraint
512 * by computing the right inverse U of a matrix that starts with the rows
525 * Since z_1 is zero, we can drop this variable as well as the corresponding
526 * column of U to obtain
534 * with Q' equal to Q, but without the corresponding row.
535 * After computing the facets of the facet in the z' space,
536 * we convert them back to the x space through Q.
538 static struct isl_basic_set *compute_facet(struct isl_set *set, isl_int *c)
540 struct isl_mat *m, *U, *Q;
541 struct isl_basic_set *facet = NULL;
546 set = isl_set_copy(set);
547 dim = isl_set_n_dim(set);
548 m = isl_mat_alloc(set->ctx, 2, 1 + dim);
551 isl_int_set_si(m->row[0][0], 1);
552 isl_seq_clr(m->row[0]+1, dim);
553 isl_seq_cpy(m->row[1], c, 1+dim);
554 U = isl_mat_right_inverse(m);
555 Q = isl_mat_right_inverse(isl_mat_copy(U));
556 U = isl_mat_drop_cols(U, 1, 1);
557 Q = isl_mat_drop_rows(Q, 1, 1);
558 set = isl_set_preimage(set, U);
559 facet = uset_convex_hull_wrap_bounded(set);
560 facet = isl_basic_set_preimage(facet, Q);
561 isl_assert(ctx, facet->n_eq == 0, goto error);
564 isl_basic_set_free(facet);
569 /* Given an initial facet constraint, compute the remaining facets.
570 * We do this by running through all facets found so far and computing
571 * the adjacent facets through wrapping, adding those facets that we
572 * hadn't already found before.
574 * For each facet we have found so far, we first compute its facets
575 * in the resulting convex hull. That is, we compute the ridges
576 * of the resulting convex hull contained in the facet.
577 * We also compute the corresponding facet in the current approximation
578 * of the convex hull. There is no need to wrap around the ridges
579 * in this facet since that would result in a facet that is already
580 * present in the current approximation.
582 * This function can still be significantly optimized by checking which of
583 * the facets of the basic sets are also facets of the convex hull and
584 * using all the facets so far to help in constructing the facets of the
587 * using the technique in section "3.1 Ridge Generation" of
588 * "Extended Convex Hull" by Fukuda et al.
590 static struct isl_basic_set *extend(struct isl_basic_set *hull,
595 struct isl_basic_set *facet = NULL;
596 struct isl_basic_set *hull_facet = NULL;
602 isl_assert(set->ctx, set->n > 0, goto error);
604 dim = isl_set_n_dim(set);
606 for (i = 0; i < hull->n_ineq; ++i) {
607 facet = compute_facet(set, hull->ineq[i]);
608 facet = isl_basic_set_add_equality(facet, hull->ineq[i]);
609 facet = isl_basic_set_gauss(facet, NULL);
610 facet = isl_basic_set_normalize_constraints(facet);
611 hull_facet = isl_basic_set_copy(hull);
612 hull_facet = isl_basic_set_add_equality(hull_facet, hull->ineq[i]);
613 hull_facet = isl_basic_set_gauss(hull_facet, NULL);
614 hull_facet = isl_basic_set_normalize_constraints(hull_facet);
617 hull = isl_basic_set_cow(hull);
618 hull = isl_basic_set_extend_dim(hull,
619 isl_dim_copy(hull->dim), 0, 0, facet->n_ineq);
620 for (j = 0; j < facet->n_ineq; ++j) {
621 for (f = 0; f < hull_facet->n_ineq; ++f)
622 if (isl_seq_eq(facet->ineq[j],
623 hull_facet->ineq[f], 1 + dim))
625 if (f < hull_facet->n_ineq)
627 k = isl_basic_set_alloc_inequality(hull);
630 isl_seq_cpy(hull->ineq[k], hull->ineq[i], 1+dim);
631 if (!isl_set_wrap_facet(set, hull->ineq[k], facet->ineq[j]))
634 isl_basic_set_free(hull_facet);
635 isl_basic_set_free(facet);
637 hull = isl_basic_set_simplify(hull);
638 hull = isl_basic_set_finalize(hull);
641 isl_basic_set_free(hull_facet);
642 isl_basic_set_free(facet);
643 isl_basic_set_free(hull);
647 /* Special case for computing the convex hull of a one dimensional set.
648 * We simply collect the lower and upper bounds of each basic set
649 * and the biggest of those.
651 static struct isl_basic_set *convex_hull_1d(struct isl_set *set)
653 struct isl_mat *c = NULL;
654 isl_int *lower = NULL;
655 isl_int *upper = NULL;
658 struct isl_basic_set *hull;
660 for (i = 0; i < set->n; ++i) {
661 set->p[i] = isl_basic_set_simplify(set->p[i]);
665 set = isl_set_remove_empty_parts(set);
668 isl_assert(set->ctx, set->n > 0, goto error);
669 c = isl_mat_alloc(set->ctx, 2, 2);
673 if (set->p[0]->n_eq > 0) {
674 isl_assert(set->ctx, set->p[0]->n_eq == 1, goto error);
677 if (isl_int_is_pos(set->p[0]->eq[0][1])) {
678 isl_seq_cpy(lower, set->p[0]->eq[0], 2);
679 isl_seq_neg(upper, set->p[0]->eq[0], 2);
681 isl_seq_neg(lower, set->p[0]->eq[0], 2);
682 isl_seq_cpy(upper, set->p[0]->eq[0], 2);
685 for (j = 0; j < set->p[0]->n_ineq; ++j) {
686 if (isl_int_is_pos(set->p[0]->ineq[j][1])) {
688 isl_seq_cpy(lower, set->p[0]->ineq[j], 2);
691 isl_seq_cpy(upper, set->p[0]->ineq[j], 2);
698 for (i = 0; i < set->n; ++i) {
699 struct isl_basic_set *bset = set->p[i];
703 for (j = 0; j < bset->n_eq; ++j) {
707 isl_int_mul(a, lower[0], bset->eq[j][1]);
708 isl_int_mul(b, lower[1], bset->eq[j][0]);
709 if (isl_int_lt(a, b) && isl_int_is_pos(bset->eq[j][1]))
710 isl_seq_cpy(lower, bset->eq[j], 2);
711 if (isl_int_gt(a, b) && isl_int_is_neg(bset->eq[j][1]))
712 isl_seq_neg(lower, bset->eq[j], 2);
715 isl_int_mul(a, upper[0], bset->eq[j][1]);
716 isl_int_mul(b, upper[1], bset->eq[j][0]);
717 if (isl_int_lt(a, b) && isl_int_is_pos(bset->eq[j][1]))
718 isl_seq_neg(upper, bset->eq[j], 2);
719 if (isl_int_gt(a, b) && isl_int_is_neg(bset->eq[j][1]))
720 isl_seq_cpy(upper, bset->eq[j], 2);
723 for (j = 0; j < bset->n_ineq; ++j) {
724 if (isl_int_is_pos(bset->ineq[j][1]))
726 if (isl_int_is_neg(bset->ineq[j][1]))
728 if (lower && isl_int_is_pos(bset->ineq[j][1])) {
729 isl_int_mul(a, lower[0], bset->ineq[j][1]);
730 isl_int_mul(b, lower[1], bset->ineq[j][0]);
731 if (isl_int_lt(a, b))
732 isl_seq_cpy(lower, bset->ineq[j], 2);
734 if (upper && isl_int_is_neg(bset->ineq[j][1])) {
735 isl_int_mul(a, upper[0], bset->ineq[j][1]);
736 isl_int_mul(b, upper[1], bset->ineq[j][0]);
737 if (isl_int_gt(a, b))
738 isl_seq_cpy(upper, bset->ineq[j], 2);
749 hull = isl_basic_set_alloc(set->ctx, 0, 1, 0, 0, 2);
750 hull = isl_basic_set_set_rational(hull);
754 k = isl_basic_set_alloc_inequality(hull);
755 isl_seq_cpy(hull->ineq[k], lower, 2);
758 k = isl_basic_set_alloc_inequality(hull);
759 isl_seq_cpy(hull->ineq[k], upper, 2);
761 hull = isl_basic_set_finalize(hull);
771 /* Project out final n dimensions using Fourier-Motzkin */
772 static struct isl_set *set_project_out(struct isl_ctx *ctx,
773 struct isl_set *set, unsigned n)
775 return isl_set_remove_dims(set, isl_set_n_dim(set) - n, n);
778 static struct isl_basic_set *convex_hull_0d(struct isl_set *set)
780 struct isl_basic_set *convex_hull;
785 if (isl_set_is_empty(set))
786 convex_hull = isl_basic_set_empty(isl_dim_copy(set->dim));
788 convex_hull = isl_basic_set_universe(isl_dim_copy(set->dim));
793 /* Compute the convex hull of a pair of basic sets without any parameters or
794 * integer divisions using Fourier-Motzkin elimination.
795 * The convex hull is the set of all points that can be written as
796 * the sum of points from both basic sets (in homogeneous coordinates).
797 * We set up the constraints in a space with dimensions for each of
798 * the three sets and then project out the dimensions corresponding
799 * to the two original basic sets, retaining only those corresponding
800 * to the convex hull.
802 static struct isl_basic_set *convex_hull_pair_elim(struct isl_basic_set *bset1,
803 struct isl_basic_set *bset2)
806 struct isl_basic_set *bset[2];
807 struct isl_basic_set *hull = NULL;
810 if (!bset1 || !bset2)
813 dim = isl_basic_set_n_dim(bset1);
814 hull = isl_basic_set_alloc(bset1->ctx, 0, 2 + 3 * dim, 0,
815 1 + dim + bset1->n_eq + bset2->n_eq,
816 2 + bset1->n_ineq + bset2->n_ineq);
819 for (i = 0; i < 2; ++i) {
820 for (j = 0; j < bset[i]->n_eq; ++j) {
821 k = isl_basic_set_alloc_equality(hull);
824 isl_seq_clr(hull->eq[k], (i+1) * (1+dim));
825 isl_seq_clr(hull->eq[k]+(i+2)*(1+dim), (1-i)*(1+dim));
826 isl_seq_cpy(hull->eq[k]+(i+1)*(1+dim), bset[i]->eq[j],
829 for (j = 0; j < bset[i]->n_ineq; ++j) {
830 k = isl_basic_set_alloc_inequality(hull);
833 isl_seq_clr(hull->ineq[k], (i+1) * (1+dim));
834 isl_seq_clr(hull->ineq[k]+(i+2)*(1+dim), (1-i)*(1+dim));
835 isl_seq_cpy(hull->ineq[k]+(i+1)*(1+dim),
836 bset[i]->ineq[j], 1+dim);
838 k = isl_basic_set_alloc_inequality(hull);
841 isl_seq_clr(hull->ineq[k], 1+2+3*dim);
842 isl_int_set_si(hull->ineq[k][(i+1)*(1+dim)], 1);
844 for (j = 0; j < 1+dim; ++j) {
845 k = isl_basic_set_alloc_equality(hull);
848 isl_seq_clr(hull->eq[k], 1+2+3*dim);
849 isl_int_set_si(hull->eq[k][j], -1);
850 isl_int_set_si(hull->eq[k][1+dim+j], 1);
851 isl_int_set_si(hull->eq[k][2*(1+dim)+j], 1);
853 hull = isl_basic_set_set_rational(hull);
854 hull = isl_basic_set_remove_dims(hull, dim, 2*(1+dim));
855 hull = isl_basic_set_convex_hull(hull);
856 isl_basic_set_free(bset1);
857 isl_basic_set_free(bset2);
860 isl_basic_set_free(bset1);
861 isl_basic_set_free(bset2);
862 isl_basic_set_free(hull);
866 /* Is the set bounded for each value of the parameters?
868 int isl_basic_set_is_bounded(__isl_keep isl_basic_set *bset)
875 if (isl_basic_set_fast_is_empty(bset))
878 tab = isl_tab_from_recession_cone(bset, 1);
879 bounded = isl_tab_cone_is_bounded(tab);
884 /* Is the set bounded for each value of the parameters?
886 int isl_set_is_bounded(__isl_keep isl_set *set)
893 for (i = 0; i < set->n; ++i) {
894 int bounded = isl_basic_set_is_bounded(set->p[i]);
895 if (!bounded || bounded < 0)
901 /* Compute the lineality space of the convex hull of bset1 and bset2.
903 * We first compute the intersection of the recession cone of bset1
904 * with the negative of the recession cone of bset2 and then compute
905 * the linear hull of the resulting cone.
907 static struct isl_basic_set *induced_lineality_space(
908 struct isl_basic_set *bset1, struct isl_basic_set *bset2)
911 struct isl_basic_set *lin = NULL;
914 if (!bset1 || !bset2)
917 dim = isl_basic_set_total_dim(bset1);
918 lin = isl_basic_set_alloc_dim(isl_basic_set_get_dim(bset1), 0,
919 bset1->n_eq + bset2->n_eq,
920 bset1->n_ineq + bset2->n_ineq);
921 lin = isl_basic_set_set_rational(lin);
924 for (i = 0; i < bset1->n_eq; ++i) {
925 k = isl_basic_set_alloc_equality(lin);
928 isl_int_set_si(lin->eq[k][0], 0);
929 isl_seq_cpy(lin->eq[k] + 1, bset1->eq[i] + 1, dim);
931 for (i = 0; i < bset1->n_ineq; ++i) {
932 k = isl_basic_set_alloc_inequality(lin);
935 isl_int_set_si(lin->ineq[k][0], 0);
936 isl_seq_cpy(lin->ineq[k] + 1, bset1->ineq[i] + 1, dim);
938 for (i = 0; i < bset2->n_eq; ++i) {
939 k = isl_basic_set_alloc_equality(lin);
942 isl_int_set_si(lin->eq[k][0], 0);
943 isl_seq_neg(lin->eq[k] + 1, bset2->eq[i] + 1, dim);
945 for (i = 0; i < bset2->n_ineq; ++i) {
946 k = isl_basic_set_alloc_inequality(lin);
949 isl_int_set_si(lin->ineq[k][0], 0);
950 isl_seq_neg(lin->ineq[k] + 1, bset2->ineq[i] + 1, dim);
953 isl_basic_set_free(bset1);
954 isl_basic_set_free(bset2);
955 return isl_basic_set_affine_hull(lin);
957 isl_basic_set_free(lin);
958 isl_basic_set_free(bset1);
959 isl_basic_set_free(bset2);
963 static struct isl_basic_set *uset_convex_hull(struct isl_set *set);
965 /* Given a set and a linear space "lin" of dimension n > 0,
966 * project the linear space from the set, compute the convex hull
967 * and then map the set back to the original space.
973 * describe the linear space. We first compute the Hermite normal
974 * form H = M U of M = H Q, to obtain
978 * The last n rows of H will be zero, so the last n variables of x' = Q x
979 * are the one we want to project out. We do this by transforming each
980 * basic set A x >= b to A U x' >= b and then removing the last n dimensions.
981 * After computing the convex hull in x'_1, i.e., A' x'_1 >= b',
982 * we transform the hull back to the original space as A' Q_1 x >= b',
983 * with Q_1 all but the last n rows of Q.
985 static struct isl_basic_set *modulo_lineality(struct isl_set *set,
986 struct isl_basic_set *lin)
988 unsigned total = isl_basic_set_total_dim(lin);
990 struct isl_basic_set *hull;
991 struct isl_mat *M, *U, *Q;
995 lin_dim = total - lin->n_eq;
996 M = isl_mat_sub_alloc(set->ctx, lin->eq, 0, lin->n_eq, 1, total);
997 M = isl_mat_left_hermite(M, 0, &U, &Q);
1001 isl_basic_set_free(lin);
1003 Q = isl_mat_drop_rows(Q, Q->n_row - lin_dim, lin_dim);
1005 U = isl_mat_lin_to_aff(U);
1006 Q = isl_mat_lin_to_aff(Q);
1008 set = isl_set_preimage(set, U);
1009 set = isl_set_remove_dims(set, total - lin_dim, lin_dim);
1010 hull = uset_convex_hull(set);
1011 hull = isl_basic_set_preimage(hull, Q);
1015 isl_basic_set_free(lin);
1020 /* Given two polyhedra with as constraints h_{ij} x >= 0 in homegeneous space,
1021 * set up an LP for solving
1023 * \sum_j \alpha_{1j} h_{1j} = \sum_j \alpha_{2j} h_{2j}
1025 * \alpha{i0} corresponds to the (implicit) positivity constraint 1 >= 0
1026 * The next \alpha{ij} correspond to the equalities and come in pairs.
1027 * The final \alpha{ij} correspond to the inequalities.
1029 static struct isl_basic_set *valid_direction_lp(
1030 struct isl_basic_set *bset1, struct isl_basic_set *bset2)
1032 struct isl_dim *dim;
1033 struct isl_basic_set *lp;
1038 if (!bset1 || !bset2)
1040 d = 1 + isl_basic_set_total_dim(bset1);
1042 2 * bset1->n_eq + bset1->n_ineq + 2 * bset2->n_eq + bset2->n_ineq;
1043 dim = isl_dim_set_alloc(bset1->ctx, 0, n);
1044 lp = isl_basic_set_alloc_dim(dim, 0, d, n);
1047 for (i = 0; i < n; ++i) {
1048 k = isl_basic_set_alloc_inequality(lp);
1051 isl_seq_clr(lp->ineq[k] + 1, n);
1052 isl_int_set_si(lp->ineq[k][0], -1);
1053 isl_int_set_si(lp->ineq[k][1 + i], 1);
1055 for (i = 0; i < d; ++i) {
1056 k = isl_basic_set_alloc_equality(lp);
1060 isl_int_set_si(lp->eq[k][n++], 0);
1061 /* positivity constraint 1 >= 0 */
1062 isl_int_set_si(lp->eq[k][n++], i == 0);
1063 for (j = 0; j < bset1->n_eq; ++j) {
1064 isl_int_set(lp->eq[k][n++], bset1->eq[j][i]);
1065 isl_int_neg(lp->eq[k][n++], bset1->eq[j][i]);
1067 for (j = 0; j < bset1->n_ineq; ++j)
1068 isl_int_set(lp->eq[k][n++], bset1->ineq[j][i]);
1069 /* positivity constraint 1 >= 0 */
1070 isl_int_set_si(lp->eq[k][n++], -(i == 0));
1071 for (j = 0; j < bset2->n_eq; ++j) {
1072 isl_int_neg(lp->eq[k][n++], bset2->eq[j][i]);
1073 isl_int_set(lp->eq[k][n++], bset2->eq[j][i]);
1075 for (j = 0; j < bset2->n_ineq; ++j)
1076 isl_int_neg(lp->eq[k][n++], bset2->ineq[j][i]);
1078 lp = isl_basic_set_gauss(lp, NULL);
1079 isl_basic_set_free(bset1);
1080 isl_basic_set_free(bset2);
1083 isl_basic_set_free(bset1);
1084 isl_basic_set_free(bset2);
1088 /* Compute a vector s in the homogeneous space such that <s, r> > 0
1089 * for all rays in the homogeneous space of the two cones that correspond
1090 * to the input polyhedra bset1 and bset2.
1092 * We compute s as a vector that satisfies
1094 * s = \sum_j \alpha_{ij} h_{ij} for i = 1,2 (*)
1096 * with h_{ij} the normals of the facets of polyhedron i
1097 * (including the "positivity constraint" 1 >= 0) and \alpha_{ij}
1098 * strictly positive numbers. For simplicity we impose \alpha_{ij} >= 1.
1099 * We first set up an LP with as variables the \alpha{ij}.
1100 * In this formulation, for each polyhedron i,
1101 * the first constraint is the positivity constraint, followed by pairs
1102 * of variables for the equalities, followed by variables for the inequalities.
1103 * We then simply pick a feasible solution and compute s using (*).
1105 * Note that we simply pick any valid direction and make no attempt
1106 * to pick a "good" or even the "best" valid direction.
1108 static struct isl_vec *valid_direction(
1109 struct isl_basic_set *bset1, struct isl_basic_set *bset2)
1111 struct isl_basic_set *lp;
1112 struct isl_tab *tab;
1113 struct isl_vec *sample = NULL;
1114 struct isl_vec *dir;
1119 if (!bset1 || !bset2)
1121 lp = valid_direction_lp(isl_basic_set_copy(bset1),
1122 isl_basic_set_copy(bset2));
1123 tab = isl_tab_from_basic_set(lp);
1124 sample = isl_tab_get_sample_value(tab);
1126 isl_basic_set_free(lp);
1129 d = isl_basic_set_total_dim(bset1);
1130 dir = isl_vec_alloc(bset1->ctx, 1 + d);
1133 isl_seq_clr(dir->block.data + 1, dir->size - 1);
1135 /* positivity constraint 1 >= 0 */
1136 isl_int_set(dir->block.data[0], sample->block.data[n++]);
1137 for (i = 0; i < bset1->n_eq; ++i) {
1138 isl_int_sub(sample->block.data[n],
1139 sample->block.data[n], sample->block.data[n+1]);
1140 isl_seq_combine(dir->block.data,
1141 bset1->ctx->one, dir->block.data,
1142 sample->block.data[n], bset1->eq[i], 1 + d);
1146 for (i = 0; i < bset1->n_ineq; ++i)
1147 isl_seq_combine(dir->block.data,
1148 bset1->ctx->one, dir->block.data,
1149 sample->block.data[n++], bset1->ineq[i], 1 + d);
1150 isl_vec_free(sample);
1151 isl_seq_normalize(bset1->ctx, dir->el, dir->size);
1152 isl_basic_set_free(bset1);
1153 isl_basic_set_free(bset2);
1156 isl_vec_free(sample);
1157 isl_basic_set_free(bset1);
1158 isl_basic_set_free(bset2);
1162 /* Given a polyhedron b_i + A_i x >= 0 and a map T = S^{-1},
1163 * compute b_i' + A_i' x' >= 0, with
1165 * [ b_i A_i ] [ y' ] [ y' ]
1166 * [ 1 0 ] S^{-1} [ x' ] >= 0 or [ b_i' A_i' ] [ x' ] >= 0
1168 * In particular, add the "positivity constraint" and then perform
1171 static struct isl_basic_set *homogeneous_map(struct isl_basic_set *bset,
1178 bset = isl_basic_set_extend_constraints(bset, 0, 1);
1179 k = isl_basic_set_alloc_inequality(bset);
1182 isl_seq_clr(bset->ineq[k] + 1, isl_basic_set_total_dim(bset));
1183 isl_int_set_si(bset->ineq[k][0], 1);
1184 bset = isl_basic_set_preimage(bset, T);
1188 isl_basic_set_free(bset);
1192 /* Compute the convex hull of a pair of basic sets without any parameters or
1193 * integer divisions, where the convex hull is known to be pointed,
1194 * but the basic sets may be unbounded.
1196 * We turn this problem into the computation of a convex hull of a pair
1197 * _bounded_ polyhedra by "changing the direction of the homogeneous
1198 * dimension". This idea is due to Matthias Koeppe.
1200 * Consider the cones in homogeneous space that correspond to the
1201 * input polyhedra. The rays of these cones are also rays of the
1202 * polyhedra if the coordinate that corresponds to the homogeneous
1203 * dimension is zero. That is, if the inner product of the rays
1204 * with the homogeneous direction is zero.
1205 * The cones in the homogeneous space can also be considered to
1206 * correspond to other pairs of polyhedra by chosing a different
1207 * homogeneous direction. To ensure that both of these polyhedra
1208 * are bounded, we need to make sure that all rays of the cones
1209 * correspond to vertices and not to rays.
1210 * Let s be a direction such that <s, r> > 0 for all rays r of both cones.
1211 * Then using s as a homogeneous direction, we obtain a pair of polytopes.
1212 * The vector s is computed in valid_direction.
1214 * Note that we need to consider _all_ rays of the cones and not just
1215 * the rays that correspond to rays in the polyhedra. If we were to
1216 * only consider those rays and turn them into vertices, then we
1217 * may inadvertently turn some vertices into rays.
1219 * The standard homogeneous direction is the unit vector in the 0th coordinate.
1220 * We therefore transform the two polyhedra such that the selected
1221 * direction is mapped onto this standard direction and then proceed
1222 * with the normal computation.
1223 * Let S be a non-singular square matrix with s as its first row,
1224 * then we want to map the polyhedra to the space
1226 * [ y' ] [ y ] [ y ] [ y' ]
1227 * [ x' ] = S [ x ] i.e., [ x ] = S^{-1} [ x' ]
1229 * We take S to be the unimodular completion of s to limit the growth
1230 * of the coefficients in the following computations.
1232 * Let b_i + A_i x >= 0 be the constraints of polyhedron i.
1233 * We first move to the homogeneous dimension
1235 * b_i y + A_i x >= 0 [ b_i A_i ] [ y ] [ 0 ]
1236 * y >= 0 or [ 1 0 ] [ x ] >= [ 0 ]
1238 * Then we change directoin
1240 * [ b_i A_i ] [ y' ] [ y' ]
1241 * [ 1 0 ] S^{-1} [ x' ] >= 0 or [ b_i' A_i' ] [ x' ] >= 0
1243 * Then we compute the convex hull of the polytopes b_i' + A_i' x' >= 0
1244 * resulting in b' + A' x' >= 0, which we then convert back
1247 * [ b' A' ] S [ x ] >= 0 or [ b A ] [ x ] >= 0
1249 * The polyhedron b + A x >= 0 is then the convex hull of the input polyhedra.
1251 static struct isl_basic_set *convex_hull_pair_pointed(
1252 struct isl_basic_set *bset1, struct isl_basic_set *bset2)
1254 struct isl_ctx *ctx = NULL;
1255 struct isl_vec *dir = NULL;
1256 struct isl_mat *T = NULL;
1257 struct isl_mat *T2 = NULL;
1258 struct isl_basic_set *hull;
1259 struct isl_set *set;
1261 if (!bset1 || !bset2)
1264 dir = valid_direction(isl_basic_set_copy(bset1),
1265 isl_basic_set_copy(bset2));
1268 T = isl_mat_alloc(bset1->ctx, dir->size, dir->size);
1271 isl_seq_cpy(T->row[0], dir->block.data, dir->size);
1272 T = isl_mat_unimodular_complete(T, 1);
1273 T2 = isl_mat_right_inverse(isl_mat_copy(T));
1275 bset1 = homogeneous_map(bset1, isl_mat_copy(T2));
1276 bset2 = homogeneous_map(bset2, T2);
1277 set = isl_set_alloc_dim(isl_basic_set_get_dim(bset1), 2, 0);
1278 set = isl_set_add_basic_set(set, bset1);
1279 set = isl_set_add_basic_set(set, bset2);
1280 hull = uset_convex_hull(set);
1281 hull = isl_basic_set_preimage(hull, T);
1288 isl_basic_set_free(bset1);
1289 isl_basic_set_free(bset2);
1293 static struct isl_basic_set *uset_convex_hull_wrap(struct isl_set *set);
1294 static struct isl_basic_set *modulo_affine_hull(
1295 struct isl_set *set, struct isl_basic_set *affine_hull);
1297 /* Compute the convex hull of a pair of basic sets without any parameters or
1298 * integer divisions.
1300 * This function is called from uset_convex_hull_unbounded, which
1301 * means that the complete convex hull is unbounded. Some pairs
1302 * of basic sets may still be bounded, though.
1303 * They may even lie inside a lower dimensional space, in which
1304 * case they need to be handled inside their affine hull since
1305 * the main algorithm assumes that the result is full-dimensional.
1307 * If the convex hull of the two basic sets would have a non-trivial
1308 * lineality space, we first project out this lineality space.
1310 static struct isl_basic_set *convex_hull_pair(struct isl_basic_set *bset1,
1311 struct isl_basic_set *bset2)
1313 isl_basic_set *lin, *aff;
1314 int bounded1, bounded2;
1316 aff = isl_set_affine_hull(isl_basic_set_union(isl_basic_set_copy(bset1),
1317 isl_basic_set_copy(bset2)));
1321 return modulo_affine_hull(isl_basic_set_union(bset1, bset2), aff);
1322 isl_basic_set_free(aff);
1324 bounded1 = isl_basic_set_is_bounded(bset1);
1325 bounded2 = isl_basic_set_is_bounded(bset2);
1327 if (bounded1 < 0 || bounded2 < 0)
1330 if (bounded1 && bounded2)
1331 uset_convex_hull_wrap(isl_basic_set_union(bset1, bset2));
1333 if (bounded1 || bounded2)
1334 return convex_hull_pair_pointed(bset1, bset2);
1336 lin = induced_lineality_space(isl_basic_set_copy(bset1),
1337 isl_basic_set_copy(bset2));
1340 if (isl_basic_set_is_universe(lin)) {
1341 isl_basic_set_free(bset1);
1342 isl_basic_set_free(bset2);
1345 if (lin->n_eq < isl_basic_set_total_dim(lin)) {
1346 struct isl_set *set;
1347 set = isl_set_alloc_dim(isl_basic_set_get_dim(bset1), 2, 0);
1348 set = isl_set_add_basic_set(set, bset1);
1349 set = isl_set_add_basic_set(set, bset2);
1350 return modulo_lineality(set, lin);
1352 isl_basic_set_free(lin);
1354 return convex_hull_pair_pointed(bset1, bset2);
1356 isl_basic_set_free(bset1);
1357 isl_basic_set_free(bset2);
1361 /* Compute the lineality space of a basic set.
1362 * We currently do not allow the basic set to have any divs.
1363 * We basically just drop the constants and turn every inequality
1366 struct isl_basic_set *isl_basic_set_lineality_space(struct isl_basic_set *bset)
1369 struct isl_basic_set *lin = NULL;
1374 isl_assert(bset->ctx, bset->n_div == 0, goto error);
1375 dim = isl_basic_set_total_dim(bset);
1377 lin = isl_basic_set_alloc_dim(isl_basic_set_get_dim(bset), 0, dim, 0);
1380 for (i = 0; i < bset->n_eq; ++i) {
1381 k = isl_basic_set_alloc_equality(lin);
1384 isl_int_set_si(lin->eq[k][0], 0);
1385 isl_seq_cpy(lin->eq[k] + 1, bset->eq[i] + 1, dim);
1387 lin = isl_basic_set_gauss(lin, NULL);
1390 for (i = 0; i < bset->n_ineq && lin->n_eq < dim; ++i) {
1391 k = isl_basic_set_alloc_equality(lin);
1394 isl_int_set_si(lin->eq[k][0], 0);
1395 isl_seq_cpy(lin->eq[k] + 1, bset->ineq[i] + 1, dim);
1396 lin = isl_basic_set_gauss(lin, NULL);
1400 isl_basic_set_free(bset);
1403 isl_basic_set_free(lin);
1404 isl_basic_set_free(bset);
1408 /* Compute the (linear) hull of the lineality spaces of the basic sets in the
1409 * "underlying" set "set".
1411 static struct isl_basic_set *uset_combined_lineality_space(struct isl_set *set)
1414 struct isl_set *lin = NULL;
1419 struct isl_dim *dim = isl_set_get_dim(set);
1421 return isl_basic_set_empty(dim);
1424 lin = isl_set_alloc_dim(isl_set_get_dim(set), set->n, 0);
1425 for (i = 0; i < set->n; ++i)
1426 lin = isl_set_add_basic_set(lin,
1427 isl_basic_set_lineality_space(isl_basic_set_copy(set->p[i])));
1429 return isl_set_affine_hull(lin);
1432 /* Compute the convex hull of a set without any parameters or
1433 * integer divisions.
1434 * In each step, we combined two basic sets until only one
1435 * basic set is left.
1436 * The input basic sets are assumed not to have a non-trivial
1437 * lineality space. If any of the intermediate results has
1438 * a non-trivial lineality space, it is projected out.
1440 static struct isl_basic_set *uset_convex_hull_unbounded(struct isl_set *set)
1442 struct isl_basic_set *convex_hull = NULL;
1444 convex_hull = isl_set_copy_basic_set(set);
1445 set = isl_set_drop_basic_set(set, convex_hull);
1448 while (set->n > 0) {
1449 struct isl_basic_set *t;
1450 t = isl_set_copy_basic_set(set);
1453 set = isl_set_drop_basic_set(set, t);
1456 convex_hull = convex_hull_pair(convex_hull, t);
1459 t = isl_basic_set_lineality_space(isl_basic_set_copy(convex_hull));
1462 if (isl_basic_set_is_universe(t)) {
1463 isl_basic_set_free(convex_hull);
1467 if (t->n_eq < isl_basic_set_total_dim(t)) {
1468 set = isl_set_add_basic_set(set, convex_hull);
1469 return modulo_lineality(set, t);
1471 isl_basic_set_free(t);
1477 isl_basic_set_free(convex_hull);
1481 /* Compute an initial hull for wrapping containing a single initial
1483 * This function assumes that the given set is bounded.
1485 static struct isl_basic_set *initial_hull(struct isl_basic_set *hull,
1486 struct isl_set *set)
1488 struct isl_mat *bounds = NULL;
1494 bounds = initial_facet_constraint(set);
1497 k = isl_basic_set_alloc_inequality(hull);
1500 dim = isl_set_n_dim(set);
1501 isl_assert(set->ctx, 1 + dim == bounds->n_col, goto error);
1502 isl_seq_cpy(hull->ineq[k], bounds->row[0], bounds->n_col);
1503 isl_mat_free(bounds);
1507 isl_basic_set_free(hull);
1508 isl_mat_free(bounds);
1512 struct max_constraint {
1518 static int max_constraint_equal(const void *entry, const void *val)
1520 struct max_constraint *a = (struct max_constraint *)entry;
1521 isl_int *b = (isl_int *)val;
1523 return isl_seq_eq(a->c->row[0] + 1, b, a->c->n_col - 1);
1526 static void update_constraint(struct isl_ctx *ctx, struct isl_hash_table *table,
1527 isl_int *con, unsigned len, int n, int ineq)
1529 struct isl_hash_table_entry *entry;
1530 struct max_constraint *c;
1533 c_hash = isl_seq_get_hash(con + 1, len);
1534 entry = isl_hash_table_find(ctx, table, c_hash, max_constraint_equal,
1540 isl_hash_table_remove(ctx, table, entry);
1544 if (isl_int_gt(c->c->row[0][0], con[0]))
1546 if (isl_int_eq(c->c->row[0][0], con[0])) {
1551 c->c = isl_mat_cow(c->c);
1552 isl_int_set(c->c->row[0][0], con[0]);
1556 /* Check whether the constraint hash table "table" constains the constraint
1559 static int has_constraint(struct isl_ctx *ctx, struct isl_hash_table *table,
1560 isl_int *con, unsigned len, int n)
1562 struct isl_hash_table_entry *entry;
1563 struct max_constraint *c;
1566 c_hash = isl_seq_get_hash(con + 1, len);
1567 entry = isl_hash_table_find(ctx, table, c_hash, max_constraint_equal,
1574 return isl_int_eq(c->c->row[0][0], con[0]);
1577 /* Check for inequality constraints of a basic set without equalities
1578 * such that the same or more stringent copies of the constraint appear
1579 * in all of the basic sets. Such constraints are necessarily facet
1580 * constraints of the convex hull.
1582 * If the resulting basic set is by chance identical to one of
1583 * the basic sets in "set", then we know that this basic set contains
1584 * all other basic sets and is therefore the convex hull of set.
1585 * In this case we set *is_hull to 1.
1587 static struct isl_basic_set *common_constraints(struct isl_basic_set *hull,
1588 struct isl_set *set, int *is_hull)
1591 int min_constraints;
1593 struct max_constraint *constraints = NULL;
1594 struct isl_hash_table *table = NULL;
1599 for (i = 0; i < set->n; ++i)
1600 if (set->p[i]->n_eq == 0)
1604 min_constraints = set->p[i]->n_ineq;
1606 for (i = best + 1; i < set->n; ++i) {
1607 if (set->p[i]->n_eq != 0)
1609 if (set->p[i]->n_ineq >= min_constraints)
1611 min_constraints = set->p[i]->n_ineq;
1614 constraints = isl_calloc_array(hull->ctx, struct max_constraint,
1618 table = isl_alloc_type(hull->ctx, struct isl_hash_table);
1619 if (isl_hash_table_init(hull->ctx, table, min_constraints))
1622 total = isl_dim_total(set->dim);
1623 for (i = 0; i < set->p[best]->n_ineq; ++i) {
1624 constraints[i].c = isl_mat_sub_alloc(hull->ctx,
1625 set->p[best]->ineq + i, 0, 1, 0, 1 + total);
1626 if (!constraints[i].c)
1628 constraints[i].ineq = 1;
1630 for (i = 0; i < min_constraints; ++i) {
1631 struct isl_hash_table_entry *entry;
1633 c_hash = isl_seq_get_hash(constraints[i].c->row[0] + 1, total);
1634 entry = isl_hash_table_find(hull->ctx, table, c_hash,
1635 max_constraint_equal, constraints[i].c->row[0] + 1, 1);
1638 isl_assert(hull->ctx, !entry->data, goto error);
1639 entry->data = &constraints[i];
1643 for (s = 0; s < set->n; ++s) {
1647 for (i = 0; i < set->p[s]->n_eq; ++i) {
1648 isl_int *eq = set->p[s]->eq[i];
1649 for (j = 0; j < 2; ++j) {
1650 isl_seq_neg(eq, eq, 1 + total);
1651 update_constraint(hull->ctx, table,
1655 for (i = 0; i < set->p[s]->n_ineq; ++i) {
1656 isl_int *ineq = set->p[s]->ineq[i];
1657 update_constraint(hull->ctx, table, ineq, total, n,
1658 set->p[s]->n_eq == 0);
1663 for (i = 0; i < min_constraints; ++i) {
1664 if (constraints[i].count < n)
1666 if (!constraints[i].ineq)
1668 j = isl_basic_set_alloc_inequality(hull);
1671 isl_seq_cpy(hull->ineq[j], constraints[i].c->row[0], 1 + total);
1674 for (s = 0; s < set->n; ++s) {
1675 if (set->p[s]->n_eq)
1677 if (set->p[s]->n_ineq != hull->n_ineq)
1679 for (i = 0; i < set->p[s]->n_ineq; ++i) {
1680 isl_int *ineq = set->p[s]->ineq[i];
1681 if (!has_constraint(hull->ctx, table, ineq, total, n))
1684 if (i == set->p[s]->n_ineq)
1688 isl_hash_table_clear(table);
1689 for (i = 0; i < min_constraints; ++i)
1690 isl_mat_free(constraints[i].c);
1695 isl_hash_table_clear(table);
1698 for (i = 0; i < min_constraints; ++i)
1699 isl_mat_free(constraints[i].c);
1704 /* Create a template for the convex hull of "set" and fill it up
1705 * obvious facet constraints, if any. If the result happens to
1706 * be the convex hull of "set" then *is_hull is set to 1.
1708 static struct isl_basic_set *proto_hull(struct isl_set *set, int *is_hull)
1710 struct isl_basic_set *hull;
1715 for (i = 0; i < set->n; ++i) {
1716 n_ineq += set->p[i]->n_eq;
1717 n_ineq += set->p[i]->n_ineq;
1719 hull = isl_basic_set_alloc_dim(isl_dim_copy(set->dim), 0, 0, n_ineq);
1720 hull = isl_basic_set_set_rational(hull);
1723 return common_constraints(hull, set, is_hull);
1726 static struct isl_basic_set *uset_convex_hull_wrap(struct isl_set *set)
1728 struct isl_basic_set *hull;
1731 hull = proto_hull(set, &is_hull);
1732 if (hull && !is_hull) {
1733 if (hull->n_ineq == 0)
1734 hull = initial_hull(hull, set);
1735 hull = extend(hull, set);
1742 /* Compute the convex hull of a set without any parameters or
1743 * integer divisions. Depending on whether the set is bounded,
1744 * we pass control to the wrapping based convex hull or
1745 * the Fourier-Motzkin elimination based convex hull.
1746 * We also handle a few special cases before checking the boundedness.
1748 static struct isl_basic_set *uset_convex_hull(struct isl_set *set)
1750 struct isl_basic_set *convex_hull = NULL;
1751 struct isl_basic_set *lin;
1753 if (isl_set_n_dim(set) == 0)
1754 return convex_hull_0d(set);
1756 set = isl_set_coalesce(set);
1757 set = isl_set_set_rational(set);
1764 convex_hull = isl_basic_set_copy(set->p[0]);
1768 if (isl_set_n_dim(set) == 1)
1769 return convex_hull_1d(set);
1771 if (isl_set_is_bounded(set))
1772 return uset_convex_hull_wrap(set);
1774 lin = uset_combined_lineality_space(isl_set_copy(set));
1777 if (isl_basic_set_is_universe(lin)) {
1781 if (lin->n_eq < isl_basic_set_total_dim(lin))
1782 return modulo_lineality(set, lin);
1783 isl_basic_set_free(lin);
1785 return uset_convex_hull_unbounded(set);
1788 isl_basic_set_free(convex_hull);
1792 /* This is the core procedure, where "set" is a "pure" set, i.e.,
1793 * without parameters or divs and where the convex hull of set is
1794 * known to be full-dimensional.
1796 static struct isl_basic_set *uset_convex_hull_wrap_bounded(struct isl_set *set)
1798 struct isl_basic_set *convex_hull = NULL;
1800 if (isl_set_n_dim(set) == 0) {
1801 convex_hull = isl_basic_set_universe(isl_dim_copy(set->dim));
1803 convex_hull = isl_basic_set_set_rational(convex_hull);
1807 set = isl_set_set_rational(set);
1811 set = isl_set_coalesce(set);
1815 convex_hull = isl_basic_set_copy(set->p[0]);
1819 if (isl_set_n_dim(set) == 1)
1820 return convex_hull_1d(set);
1822 return uset_convex_hull_wrap(set);
1828 /* Compute the convex hull of set "set" with affine hull "affine_hull",
1829 * We first remove the equalities (transforming the set), compute the
1830 * convex hull of the transformed set and then add the equalities back
1831 * (after performing the inverse transformation.
1833 static struct isl_basic_set *modulo_affine_hull(
1834 struct isl_set *set, struct isl_basic_set *affine_hull)
1838 struct isl_basic_set *dummy;
1839 struct isl_basic_set *convex_hull;
1841 dummy = isl_basic_set_remove_equalities(
1842 isl_basic_set_copy(affine_hull), &T, &T2);
1845 isl_basic_set_free(dummy);
1846 set = isl_set_preimage(set, T);
1847 convex_hull = uset_convex_hull(set);
1848 convex_hull = isl_basic_set_preimage(convex_hull, T2);
1849 convex_hull = isl_basic_set_intersect(convex_hull, affine_hull);
1852 isl_basic_set_free(affine_hull);
1857 /* Compute the convex hull of a map.
1859 * The implementation was inspired by "Extended Convex Hull" by Fukuda et al.,
1860 * specifically, the wrapping of facets to obtain new facets.
1862 struct isl_basic_map *isl_map_convex_hull(struct isl_map *map)
1864 struct isl_basic_set *bset;
1865 struct isl_basic_map *model = NULL;
1866 struct isl_basic_set *affine_hull = NULL;
1867 struct isl_basic_map *convex_hull = NULL;
1868 struct isl_set *set = NULL;
1869 struct isl_ctx *ctx;
1876 convex_hull = isl_basic_map_empty_like_map(map);
1881 map = isl_map_detect_equalities(map);
1882 map = isl_map_align_divs(map);
1883 model = isl_basic_map_copy(map->p[0]);
1884 set = isl_map_underlying_set(map);
1888 affine_hull = isl_set_affine_hull(isl_set_copy(set));
1891 if (affine_hull->n_eq != 0)
1892 bset = modulo_affine_hull(set, affine_hull);
1894 isl_basic_set_free(affine_hull);
1895 bset = uset_convex_hull(set);
1898 convex_hull = isl_basic_map_overlying_set(bset, model);
1900 ISL_F_SET(convex_hull, ISL_BASIC_MAP_NO_IMPLICIT);
1901 ISL_F_SET(convex_hull, ISL_BASIC_MAP_ALL_EQUALITIES);
1902 ISL_F_CLR(convex_hull, ISL_BASIC_MAP_RATIONAL);
1906 isl_basic_map_free(model);
1910 struct isl_basic_set *isl_set_convex_hull(struct isl_set *set)
1912 return (struct isl_basic_set *)
1913 isl_map_convex_hull((struct isl_map *)set);
1916 struct sh_data_entry {
1917 struct isl_hash_table *table;
1918 struct isl_tab *tab;
1921 /* Holds the data needed during the simple hull computation.
1923 * n the number of basic sets in the original set
1924 * hull_table a hash table of already computed constraints
1925 * in the simple hull
1926 * p for each basic set,
1927 * table a hash table of the constraints
1928 * tab the tableau corresponding to the basic set
1931 struct isl_ctx *ctx;
1933 struct isl_hash_table *hull_table;
1934 struct sh_data_entry p[1];
1937 static void sh_data_free(struct sh_data *data)
1943 isl_hash_table_free(data->ctx, data->hull_table);
1944 for (i = 0; i < data->n; ++i) {
1945 isl_hash_table_free(data->ctx, data->p[i].table);
1946 isl_tab_free(data->p[i].tab);
1951 struct ineq_cmp_data {
1956 static int has_ineq(const void *entry, const void *val)
1958 isl_int *row = (isl_int *)entry;
1959 struct ineq_cmp_data *v = (struct ineq_cmp_data *)val;
1961 return isl_seq_eq(row + 1, v->p + 1, v->len) ||
1962 isl_seq_is_neg(row + 1, v->p + 1, v->len);
1965 static int hash_ineq(struct isl_ctx *ctx, struct isl_hash_table *table,
1966 isl_int *ineq, unsigned len)
1969 struct ineq_cmp_data v;
1970 struct isl_hash_table_entry *entry;
1974 c_hash = isl_seq_get_hash(ineq + 1, len);
1975 entry = isl_hash_table_find(ctx, table, c_hash, has_ineq, &v, 1);
1982 /* Fill hash table "table" with the constraints of "bset".
1983 * Equalities are added as two inequalities.
1984 * The value in the hash table is a pointer to the (in)equality of "bset".
1986 static int hash_basic_set(struct isl_hash_table *table,
1987 struct isl_basic_set *bset)
1990 unsigned dim = isl_basic_set_total_dim(bset);
1992 for (i = 0; i < bset->n_eq; ++i) {
1993 for (j = 0; j < 2; ++j) {
1994 isl_seq_neg(bset->eq[i], bset->eq[i], 1 + dim);
1995 if (hash_ineq(bset->ctx, table, bset->eq[i], dim) < 0)
1999 for (i = 0; i < bset->n_ineq; ++i) {
2000 if (hash_ineq(bset->ctx, table, bset->ineq[i], dim) < 0)
2006 static struct sh_data *sh_data_alloc(struct isl_set *set, unsigned n_ineq)
2008 struct sh_data *data;
2011 data = isl_calloc(set->ctx, struct sh_data,
2012 sizeof(struct sh_data) +
2013 (set->n - 1) * sizeof(struct sh_data_entry));
2016 data->ctx = set->ctx;
2018 data->hull_table = isl_hash_table_alloc(set->ctx, n_ineq);
2019 if (!data->hull_table)
2021 for (i = 0; i < set->n; ++i) {
2022 data->p[i].table = isl_hash_table_alloc(set->ctx,
2023 2 * set->p[i]->n_eq + set->p[i]->n_ineq);
2024 if (!data->p[i].table)
2026 if (hash_basic_set(data->p[i].table, set->p[i]) < 0)
2035 /* Check if inequality "ineq" is a bound for basic set "j" or if
2036 * it can be relaxed (by increasing the constant term) to become
2037 * a bound for that basic set. In the latter case, the constant
2039 * Return 1 if "ineq" is a bound
2040 * 0 if "ineq" may attain arbitrarily small values on basic set "j"
2041 * -1 if some error occurred
2043 static int is_bound(struct sh_data *data, struct isl_set *set, int j,
2046 enum isl_lp_result res;
2049 if (!data->p[j].tab) {
2050 data->p[j].tab = isl_tab_from_basic_set(set->p[j]);
2051 if (!data->p[j].tab)
2057 res = isl_tab_min(data->p[j].tab, ineq, data->ctx->one,
2059 if (res == isl_lp_ok && isl_int_is_neg(opt))
2060 isl_int_sub(ineq[0], ineq[0], opt);
2064 return (res == isl_lp_ok || res == isl_lp_empty) ? 1 :
2065 res == isl_lp_unbounded ? 0 : -1;
2068 /* Check if inequality "ineq" from basic set "i" can be relaxed to
2069 * become a bound on the whole set. If so, add the (relaxed) inequality
2072 * We first check if "hull" already contains a translate of the inequality.
2073 * If so, we are done.
2074 * Then, we check if any of the previous basic sets contains a translate
2075 * of the inequality. If so, then we have already considered this
2076 * inequality and we are done.
2077 * Otherwise, for each basic set other than "i", we check if the inequality
2078 * is a bound on the basic set.
2079 * For previous basic sets, we know that they do not contain a translate
2080 * of the inequality, so we directly call is_bound.
2081 * For following basic sets, we first check if a translate of the
2082 * inequality appears in its description and if so directly update
2083 * the inequality accordingly.
2085 static struct isl_basic_set *add_bound(struct isl_basic_set *hull,
2086 struct sh_data *data, struct isl_set *set, int i, isl_int *ineq)
2089 struct ineq_cmp_data v;
2090 struct isl_hash_table_entry *entry;
2096 v.len = isl_basic_set_total_dim(hull);
2098 c_hash = isl_seq_get_hash(ineq + 1, v.len);
2100 entry = isl_hash_table_find(hull->ctx, data->hull_table, c_hash,
2105 for (j = 0; j < i; ++j) {
2106 entry = isl_hash_table_find(hull->ctx, data->p[j].table,
2107 c_hash, has_ineq, &v, 0);
2114 k = isl_basic_set_alloc_inequality(hull);
2115 isl_seq_cpy(hull->ineq[k], ineq, 1 + v.len);
2119 for (j = 0; j < i; ++j) {
2121 bound = is_bound(data, set, j, hull->ineq[k]);
2128 isl_basic_set_free_inequality(hull, 1);
2132 for (j = i + 1; j < set->n; ++j) {
2135 entry = isl_hash_table_find(hull->ctx, data->p[j].table,
2136 c_hash, has_ineq, &v, 0);
2138 ineq_j = entry->data;
2139 neg = isl_seq_is_neg(ineq_j + 1,
2140 hull->ineq[k] + 1, v.len);
2142 isl_int_neg(ineq_j[0], ineq_j[0]);
2143 if (isl_int_gt(ineq_j[0], hull->ineq[k][0]))
2144 isl_int_set(hull->ineq[k][0], ineq_j[0]);
2146 isl_int_neg(ineq_j[0], ineq_j[0]);
2149 bound = is_bound(data, set, j, hull->ineq[k]);
2156 isl_basic_set_free_inequality(hull, 1);
2160 entry = isl_hash_table_find(hull->ctx, data->hull_table, c_hash,
2164 entry->data = hull->ineq[k];
2168 isl_basic_set_free(hull);
2172 /* Check if any inequality from basic set "i" can be relaxed to
2173 * become a bound on the whole set. If so, add the (relaxed) inequality
2176 static struct isl_basic_set *add_bounds(struct isl_basic_set *bset,
2177 struct sh_data *data, struct isl_set *set, int i)
2180 unsigned dim = isl_basic_set_total_dim(bset);
2182 for (j = 0; j < set->p[i]->n_eq; ++j) {
2183 for (k = 0; k < 2; ++k) {
2184 isl_seq_neg(set->p[i]->eq[j], set->p[i]->eq[j], 1+dim);
2185 bset = add_bound(bset, data, set, i, set->p[i]->eq[j]);
2188 for (j = 0; j < set->p[i]->n_ineq; ++j)
2189 bset = add_bound(bset, data, set, i, set->p[i]->ineq[j]);
2193 /* Compute a superset of the convex hull of set that is described
2194 * by only translates of the constraints in the constituents of set.
2196 static struct isl_basic_set *uset_simple_hull(struct isl_set *set)
2198 struct sh_data *data = NULL;
2199 struct isl_basic_set *hull = NULL;
2207 for (i = 0; i < set->n; ++i) {
2210 n_ineq += 2 * set->p[i]->n_eq + set->p[i]->n_ineq;
2213 hull = isl_basic_set_alloc_dim(isl_dim_copy(set->dim), 0, 0, n_ineq);
2217 data = sh_data_alloc(set, n_ineq);
2221 for (i = 0; i < set->n; ++i)
2222 hull = add_bounds(hull, data, set, i);
2230 isl_basic_set_free(hull);
2235 /* Compute a superset of the convex hull of map that is described
2236 * by only translates of the constraints in the constituents of map.
2238 struct isl_basic_map *isl_map_simple_hull(struct isl_map *map)
2240 struct isl_set *set = NULL;
2241 struct isl_basic_map *model = NULL;
2242 struct isl_basic_map *hull;
2243 struct isl_basic_map *affine_hull;
2244 struct isl_basic_set *bset = NULL;
2249 hull = isl_basic_map_empty_like_map(map);
2254 hull = isl_basic_map_copy(map->p[0]);
2259 map = isl_map_detect_equalities(map);
2260 affine_hull = isl_map_affine_hull(isl_map_copy(map));
2261 map = isl_map_align_divs(map);
2262 model = isl_basic_map_copy(map->p[0]);
2264 set = isl_map_underlying_set(map);
2266 bset = uset_simple_hull(set);
2268 hull = isl_basic_map_overlying_set(bset, model);
2270 hull = isl_basic_map_intersect(hull, affine_hull);
2271 hull = isl_basic_map_convex_hull(hull);
2272 ISL_F_SET(hull, ISL_BASIC_MAP_NO_IMPLICIT);
2273 ISL_F_SET(hull, ISL_BASIC_MAP_ALL_EQUALITIES);
2278 struct isl_basic_set *isl_set_simple_hull(struct isl_set *set)
2280 return (struct isl_basic_set *)
2281 isl_map_simple_hull((struct isl_map *)set);
2284 /* Given a set "set", return parametric bounds on the dimension "dim".
2286 static struct isl_basic_set *set_bounds(struct isl_set *set, int dim)
2288 unsigned set_dim = isl_set_dim(set, isl_dim_set);
2289 set = isl_set_copy(set);
2290 set = isl_set_eliminate_dims(set, dim + 1, set_dim - (dim + 1));
2291 set = isl_set_eliminate_dims(set, 0, dim);
2292 return isl_set_convex_hull(set);
2295 /* Computes a "simple hull" and then check if each dimension in the
2296 * resulting hull is bounded by a symbolic constant. If not, the
2297 * hull is intersected with the corresponding bounds on the whole set.
2299 struct isl_basic_set *isl_set_bounded_simple_hull(struct isl_set *set)
2302 struct isl_basic_set *hull;
2303 unsigned nparam, left;
2304 int removed_divs = 0;
2306 hull = isl_set_simple_hull(isl_set_copy(set));
2310 nparam = isl_basic_set_dim(hull, isl_dim_param);
2311 for (i = 0; i < isl_basic_set_dim(hull, isl_dim_set); ++i) {
2312 int lower = 0, upper = 0;
2313 struct isl_basic_set *bounds;
2315 left = isl_basic_set_total_dim(hull) - nparam - i - 1;
2316 for (j = 0; j < hull->n_eq; ++j) {
2317 if (isl_int_is_zero(hull->eq[j][1 + nparam + i]))
2319 if (isl_seq_first_non_zero(hull->eq[j]+1+nparam+i+1,
2326 for (j = 0; j < hull->n_ineq; ++j) {
2327 if (isl_int_is_zero(hull->ineq[j][1 + nparam + i]))
2329 if (isl_seq_first_non_zero(hull->ineq[j]+1+nparam+i+1,
2331 isl_seq_first_non_zero(hull->ineq[j]+1+nparam,
2334 if (isl_int_is_pos(hull->ineq[j][1 + nparam + i]))
2345 if (!removed_divs) {
2346 set = isl_set_remove_divs(set);
2351 bounds = set_bounds(set, i);
2352 hull = isl_basic_set_intersect(hull, bounds);