isl_ilp.c 24 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912
/*
 * Copyright 2008-2009 Katholieke Universiteit Leuven
 *
 * Use of this software is governed by the MIT license
 *
 * Written by Sven Verdoolaege, K.U.Leuven, Departement
 * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
 */

#include <isl_ctx_private.h>
#include <isl_map_private.h>
#include <isl/ilp.h>
#include <isl/union_set.h>
#include "isl_sample.h"
#include <isl_seq.h>
#include "isl_equalities.h"
#include <isl_aff_private.h>
#include <isl_local_space_private.h>
#include <isl_mat_private.h>
#include <isl_val_private.h>
#include <isl_vec_private.h>
#include <isl_lp_private.h>
#include <isl_ilp_private.h>

/* Given a basic set "bset", construct a basic set U such that for
 * each element x in U, the whole unit box positioned at x is inside
 * the given basic set.
 * Note that U may not contain all points that satisfy this property.
 *
 * We simply add the sum of all negative coefficients to the constant
 * term.  This ensures that if x satisfies the resulting constraints,
 * then x plus any sum of unit vectors satisfies the original constraints.
 */
static __isl_give isl_basic_set *unit_box_base_points(
	__isl_take isl_basic_set *bset)
{
	int i, j, k;
	struct isl_basic_set *unit_box = NULL;
	isl_size total;

	if (!bset)
		goto error;

	if (bset->n_eq != 0) {
		isl_space *space = isl_basic_set_get_space(bset);
		isl_basic_set_free(bset);
		return isl_basic_set_empty(space);
	}

	total = isl_basic_set_dim(bset, isl_dim_all);
	if (total < 0)
		goto error;
	unit_box = isl_basic_set_alloc_space(isl_basic_set_get_space(bset),
					0, 0, bset->n_ineq);

	for (i = 0; i < bset->n_ineq; ++i) {
		k = isl_basic_set_alloc_inequality(unit_box);
		if (k < 0)
			goto error;
		isl_seq_cpy(unit_box->ineq[k], bset->ineq[i], 1 + total);
		for (j = 0; j < total; ++j) {
			if (isl_int_is_nonneg(unit_box->ineq[k][1 + j]))
				continue;
			isl_int_add(unit_box->ineq[k][0],
				unit_box->ineq[k][0], unit_box->ineq[k][1 + j]);
		}
	}

	isl_basic_set_free(bset);
	return unit_box;
error:
	isl_basic_set_free(bset);
	isl_basic_set_free(unit_box);
	return NULL;
}

/* Find an integer point in "bset", preferably one that is
 * close to minimizing "f".
 *
 * We first check if we can easily put unit boxes inside bset.
 * If so, we take the best base point of any of the unit boxes we can find
 * and round it up to the nearest integer.
 * If not, we simply pick any integer point in "bset".
 */
static __isl_give isl_vec *initial_solution(__isl_keep isl_basic_set *bset,
	isl_int *f)
{
	enum isl_lp_result res;
	struct isl_basic_set *unit_box;
	struct isl_vec *sol;

	unit_box = unit_box_base_points(isl_basic_set_copy(bset));

	res = isl_basic_set_solve_lp(unit_box, 0, f, bset->ctx->one,
					NULL, NULL, &sol);
	if (res == isl_lp_ok) {
		isl_basic_set_free(unit_box);
		return isl_vec_ceil(sol);
	}

	isl_basic_set_free(unit_box);

	return isl_basic_set_sample_vec(isl_basic_set_copy(bset));
}

/* Restrict "bset" to those points with values for f in the interval [l, u].
 */
static __isl_give isl_basic_set *add_bounds(__isl_take isl_basic_set *bset,
	isl_int *f, isl_int l, isl_int u)
{
	int k;
	isl_size total;

	total = isl_basic_set_dim(bset, isl_dim_all);
	if (total < 0)
		return isl_basic_set_free(bset);
	bset = isl_basic_set_extend_constraints(bset, 0, 2);

	k = isl_basic_set_alloc_inequality(bset);
	if (k < 0)
		goto error;
	isl_seq_cpy(bset->ineq[k], f, 1 + total);
	isl_int_sub(bset->ineq[k][0], bset->ineq[k][0], l);

	k = isl_basic_set_alloc_inequality(bset);
	if (k < 0)
		goto error;
	isl_seq_neg(bset->ineq[k], f, 1 + total);
	isl_int_add(bset->ineq[k][0], bset->ineq[k][0], u);

	return bset;
error:
	isl_basic_set_free(bset);
	return NULL;
}

/* Find an integer point in "bset" that minimizes f (in any) such that
 * the value of f lies inside the interval [l, u].
 * Return this integer point if it can be found.
 * Otherwise, return sol.
 *
 * We perform a number of steps until l > u.
 * In each step, we look for an integer point with value in either
 * the whole interval [l, u] or half of the interval [l, l+floor(u-l-1/2)].
 * The choice depends on whether we have found an integer point in the
 * previous step.  If so, we look for the next point in half of the remaining
 * interval.
 * If we find a point, the current solution is updated and u is set
 * to its value minus 1.
 * If no point can be found, we update l to the upper bound of the interval
 * we checked (u or l+floor(u-l-1/2)) plus 1.
 */
static __isl_give isl_vec *solve_ilp_search(__isl_keep isl_basic_set *bset,
	isl_int *f, isl_int *opt, __isl_take isl_vec *sol, isl_int l, isl_int u)
{
	isl_int tmp;
	int divide = 1;

	isl_int_init(tmp);

	while (isl_int_le(l, u)) {
		struct isl_basic_set *slice;
		struct isl_vec *sample;

		if (!divide)
			isl_int_set(tmp, u);
		else {
			isl_int_sub(tmp, u, l);
			isl_int_fdiv_q_ui(tmp, tmp, 2);
			isl_int_add(tmp, tmp, l);
		}
		slice = add_bounds(isl_basic_set_copy(bset), f, l, tmp);
		sample = isl_basic_set_sample_vec(slice);
		if (!sample) {
			isl_vec_free(sol);
			sol = NULL;
			break;
		}
		if (sample->size > 0) {
			isl_vec_free(sol);
			sol = sample;
			isl_seq_inner_product(f, sol->el, sol->size, opt);
			isl_int_sub_ui(u, *opt, 1);
			divide = 1;
		} else {
			isl_vec_free(sample);
			if (!divide)
				break;
			isl_int_add_ui(l, tmp, 1);
			divide = 0;
		}
	}

	isl_int_clear(tmp);

	return sol;
}

/* Find an integer point in "bset" that minimizes f (if any).
 * If sol_p is not NULL then the integer point is returned in *sol_p.
 * The optimal value of f is returned in *opt.
 *
 * The algorithm maintains a currently best solution and an interval [l, u]
 * of values of f for which integer solutions could potentially still be found.
 * The initial value of the best solution so far is any solution.
 * The initial value of l is minimal value of f over the rationals
 * (rounded up to the nearest integer).
 * The initial value of u is the value of f at the initial solution minus 1.
 *
 * We then call solve_ilp_search to perform a binary search on the interval.
 */
static enum isl_lp_result solve_ilp(__isl_keep isl_basic_set *bset,
	isl_int *f, isl_int *opt, __isl_give isl_vec **sol_p)
{
	enum isl_lp_result res;
	isl_int l, u;
	struct isl_vec *sol;

	res = isl_basic_set_solve_lp(bset, 0, f, bset->ctx->one,
					opt, NULL, &sol);
	if (res == isl_lp_ok && isl_int_is_one(sol->el[0])) {
		if (sol_p)
			*sol_p = sol;
		else
			isl_vec_free(sol);
		return isl_lp_ok;
	}
	isl_vec_free(sol);
	if (res == isl_lp_error || res == isl_lp_empty)
		return res;

	sol = initial_solution(bset, f);
	if (!sol)
		return isl_lp_error;
	if (sol->size == 0) {
		isl_vec_free(sol);
		return isl_lp_empty;
	}
	if (res == isl_lp_unbounded) {
		isl_vec_free(sol);
		return isl_lp_unbounded;
	}

	isl_int_init(l);
	isl_int_init(u);

	isl_int_set(l, *opt);

	isl_seq_inner_product(f, sol->el, sol->size, opt);
	isl_int_sub_ui(u, *opt, 1);

	sol = solve_ilp_search(bset, f, opt, sol, l, u);
	if (!sol)
		res = isl_lp_error;

	isl_int_clear(l);
	isl_int_clear(u);

	if (sol_p)
		*sol_p = sol;
	else
		isl_vec_free(sol);

	return res;
}

static enum isl_lp_result solve_ilp_with_eq(__isl_keep isl_basic_set *bset,
	int max, isl_int *f, isl_int *opt, __isl_give isl_vec **sol_p)
{
	isl_size dim;
	enum isl_lp_result res;
	struct isl_mat *T = NULL;
	struct isl_vec *v;

	bset = isl_basic_set_copy(bset);
	dim = isl_basic_set_dim(bset, isl_dim_all);
	if (dim < 0)
		goto error;
	v = isl_vec_alloc(bset->ctx, 1 + dim);
	if (!v)
		goto error;
	isl_seq_cpy(v->el, f, 1 + dim);
	bset = isl_basic_set_remove_equalities(bset, &T, NULL);
	v = isl_vec_mat_product(v, isl_mat_copy(T));
	if (!v)
		goto error;
	res = isl_basic_set_solve_ilp(bset, max, v->el, opt, sol_p);
	isl_vec_free(v);
	if (res == isl_lp_ok && sol_p) {
		*sol_p = isl_mat_vec_product(T, *sol_p);
		if (!*sol_p)
			res = isl_lp_error;
	} else
		isl_mat_free(T);
	isl_basic_set_free(bset);
	return res;
error:
	isl_mat_free(T);
	isl_basic_set_free(bset);
	return isl_lp_error;
}

/* Find an integer point in "bset" that minimizes (or maximizes if max is set)
 * f (if any).
 * If sol_p is not NULL then the integer point is returned in *sol_p.
 * The optimal value of f is returned in *opt.
 *
 * If there is any equality among the points in "bset", then we first
 * project it out.  Otherwise, we continue with solve_ilp above.
 */
enum isl_lp_result isl_basic_set_solve_ilp(__isl_keep isl_basic_set *bset,
	int max, isl_int *f, isl_int *opt, __isl_give isl_vec **sol_p)
{
	isl_size dim;
	enum isl_lp_result res;

	if (sol_p)
		*sol_p = NULL;

	if (isl_basic_set_check_no_params(bset) < 0)
		return isl_lp_error;

	if (isl_basic_set_plain_is_empty(bset))
		return isl_lp_empty;

	if (bset->n_eq)
		return solve_ilp_with_eq(bset, max, f, opt, sol_p);

	dim = isl_basic_set_dim(bset, isl_dim_all);
	if (dim < 0)
		return isl_lp_error;

	if (max)
		isl_seq_neg(f, f, 1 + dim);

	res = solve_ilp(bset, f, opt, sol_p);

	if (max) {
		isl_seq_neg(f, f, 1 + dim);
		isl_int_neg(*opt, *opt);
	}

	return res;
}

static enum isl_lp_result basic_set_opt(__isl_keep isl_basic_set *bset, int max,
	__isl_keep isl_aff *obj, isl_int *opt)
{
	enum isl_lp_result res;

	if (!obj)
		return isl_lp_error;
	bset = isl_basic_set_copy(bset);
	bset = isl_basic_set_underlying_set(bset);
	res = isl_basic_set_solve_ilp(bset, max, obj->v->el + 1, opt, NULL);
	isl_basic_set_free(bset);
	return res;
}

enum isl_lp_result isl_basic_set_opt(__isl_keep isl_basic_set *bset, int max,
	__isl_keep isl_aff *obj, isl_int *opt)
{
	int *exp1 = NULL;
	int *exp2 = NULL;
	isl_ctx *ctx;
	isl_mat *bset_div = NULL;
	isl_mat *div = NULL;
	enum isl_lp_result res;
	isl_size bset_n_div, obj_n_div;

	if (!bset || !obj)
		return isl_lp_error;

	ctx = isl_aff_get_ctx(obj);
	if (!isl_space_is_equal(bset->dim, obj->ls->dim))
		isl_die(ctx, isl_error_invalid,
			"spaces don't match", return isl_lp_error);
	if (!isl_int_is_one(obj->v->el[0]))
		isl_die(ctx, isl_error_unsupported,
			"expecting integer affine expression",
			return isl_lp_error);

	bset_n_div = isl_basic_set_dim(bset, isl_dim_div);
	obj_n_div = isl_aff_dim(obj, isl_dim_div);
	if (bset_n_div < 0 || obj_n_div < 0)
		return isl_lp_error;
	if (bset_n_div == 0 && obj_n_div == 0)
		return basic_set_opt(bset, max, obj, opt);

	bset = isl_basic_set_copy(bset);
	obj = isl_aff_copy(obj);

	bset_div = isl_basic_set_get_divs(bset);
	exp1 = isl_alloc_array(ctx, int, bset_n_div);
	exp2 = isl_alloc_array(ctx, int, obj_n_div);
	if (!bset_div || (bset_n_div && !exp1) || (obj_n_div && !exp2))
		goto error;

	div = isl_merge_divs(bset_div, obj->ls->div, exp1, exp2);

	bset = isl_basic_set_expand_divs(bset, isl_mat_copy(div), exp1);
	obj = isl_aff_expand_divs(obj, isl_mat_copy(div), exp2);

	res = basic_set_opt(bset, max, obj, opt);

	isl_mat_free(bset_div);
	isl_mat_free(div);
	free(exp1);
	free(exp2);
	isl_basic_set_free(bset);
	isl_aff_free(obj);

	return res;
error:
	isl_mat_free(div);
	isl_mat_free(bset_div);
	free(exp1);
	free(exp2);
	isl_basic_set_free(bset);
	isl_aff_free(obj);
	return isl_lp_error;
}

/* Compute the minimum (maximum if max is set) of the integer affine
 * expression obj over the points in set and put the result in *opt.
 *
 * The parameters are assumed to have been aligned.
 */
static enum isl_lp_result isl_set_opt_aligned(__isl_keep isl_set *set, int max,
	__isl_keep isl_aff *obj, isl_int *opt)
{
	int i;
	enum isl_lp_result res;
	int empty = 1;
	isl_int opt_i;

	if (!set || !obj)
		return isl_lp_error;
	if (set->n == 0)
		return isl_lp_empty;

	res = isl_basic_set_opt(set->p[0], max, obj, opt);
	if (res == isl_lp_error || res == isl_lp_unbounded)
		return res;
	if (set->n == 1)
		return res;
	if (res == isl_lp_ok)
		empty = 0;

	isl_int_init(opt_i);
	for (i = 1; i < set->n; ++i) {
		res = isl_basic_set_opt(set->p[i], max, obj, &opt_i);
		if (res == isl_lp_error || res == isl_lp_unbounded) {
			isl_int_clear(opt_i);
			return res;
		}
		if (res == isl_lp_empty)
			continue;
		empty = 0;
		if (max ? isl_int_gt(opt_i, *opt) : isl_int_lt(opt_i, *opt))
			isl_int_set(*opt, opt_i);
	}
	isl_int_clear(opt_i);

	return empty ? isl_lp_empty : isl_lp_ok;
}

/* Compute the minimum (maximum if max is set) of the integer affine
 * expression obj over the points in set and put the result in *opt.
 */
enum isl_lp_result isl_set_opt(__isl_keep isl_set *set, int max,
	__isl_keep isl_aff *obj, isl_int *opt)
{
	enum isl_lp_result res;
	isl_bool aligned;

	if (!set || !obj)
		return isl_lp_error;

	aligned = isl_set_space_has_equal_params(set, obj->ls->dim);
	if (aligned < 0)
		return isl_lp_error;
	if (aligned)
		return isl_set_opt_aligned(set, max, obj, opt);

	set = isl_set_copy(set);
	obj = isl_aff_copy(obj);
	set = isl_set_align_params(set, isl_aff_get_domain_space(obj));
	obj = isl_aff_align_params(obj, isl_set_get_space(set));

	res = isl_set_opt_aligned(set, max, obj, opt);

	isl_set_free(set);
	isl_aff_free(obj);

	return res;
}

/* Convert the result of a function that returns an isl_lp_result
 * to an isl_val.  The numerator of "v" is set to the optimal value
 * if lp_res is isl_lp_ok.  "max" is set if a maximum was computed.
 *
 * Return "v" with denominator set to 1 if lp_res is isl_lp_ok.
 * Return NULL on error.
 * Return a NaN if lp_res is isl_lp_empty.
 * Return infinity or negative infinity if lp_res is isl_lp_unbounded,
 * depending on "max".
 */
static __isl_give isl_val *convert_lp_result(enum isl_lp_result lp_res,
	__isl_take isl_val *v, int max)
{
	isl_ctx *ctx;

	if (lp_res == isl_lp_ok) {
		isl_int_set_si(v->d, 1);
		return isl_val_normalize(v);
	}
	ctx = isl_val_get_ctx(v);
	isl_val_free(v);
	if (lp_res == isl_lp_error)
		return NULL;
	if (lp_res == isl_lp_empty)
		return isl_val_nan(ctx);
	if (max)
		return isl_val_infty(ctx);
	else
		return isl_val_neginfty(ctx);
}

/* Return the minimum (maximum if max is set) of the integer affine
 * expression "obj" over the points in "bset".
 *
 * Return infinity or negative infinity if the optimal value is unbounded and
 * NaN if "bset" is empty.
 *
 * Call isl_basic_set_opt and translate the results.
 */
__isl_give isl_val *isl_basic_set_opt_val(__isl_keep isl_basic_set *bset,
	int max, __isl_keep isl_aff *obj)
{
	isl_ctx *ctx;
	isl_val *res;
	enum isl_lp_result lp_res;

	if (!bset || !obj)
		return NULL;

	ctx = isl_aff_get_ctx(obj);
	res = isl_val_alloc(ctx);
	if (!res)
		return NULL;
	lp_res = isl_basic_set_opt(bset, max, obj, &res->n);
	return convert_lp_result(lp_res, res, max);
}

/* Return the maximum of the integer affine
 * expression "obj" over the points in "bset".
 *
 * Return infinity or negative infinity if the optimal value is unbounded and
 * NaN if "bset" is empty.
 */
__isl_give isl_val *isl_basic_set_max_val(__isl_keep isl_basic_set *bset,
	__isl_keep isl_aff *obj)
{
	return isl_basic_set_opt_val(bset, 1, obj);
}

/* Return the minimum (maximum if max is set) of the integer affine
 * expression "obj" over the points in "set".
 *
 * Return infinity or negative infinity if the optimal value is unbounded and
 * NaN if "set" is empty.
 *
 * Call isl_set_opt and translate the results.
 */
__isl_give isl_val *isl_set_opt_val(__isl_keep isl_set *set, int max,
	__isl_keep isl_aff *obj)
{
	isl_ctx *ctx;
	isl_val *res;
	enum isl_lp_result lp_res;

	if (!set || !obj)
		return NULL;

	ctx = isl_aff_get_ctx(obj);
	res = isl_val_alloc(ctx);
	if (!res)
		return NULL;
	lp_res = isl_set_opt(set, max, obj, &res->n);
	return convert_lp_result(lp_res, res, max);
}

/* Return the minimum of the integer affine
 * expression "obj" over the points in "set".
 *
 * Return infinity or negative infinity if the optimal value is unbounded and
 * NaN if "set" is empty.
 */
__isl_give isl_val *isl_set_min_val(__isl_keep isl_set *set,
	__isl_keep isl_aff *obj)
{
	return isl_set_opt_val(set, 0, obj);
}

/* Return the maximum of the integer affine
 * expression "obj" over the points in "set".
 *
 * Return infinity or negative infinity if the optimal value is unbounded and
 * NaN if "set" is empty.
 */
__isl_give isl_val *isl_set_max_val(__isl_keep isl_set *set,
	__isl_keep isl_aff *obj)
{
	return isl_set_opt_val(set, 1, obj);
}

/* Return the optimum (min or max depending on "max") of "v1" and "v2",
 * where either may be NaN, signifying an uninitialized value.
 * That is, if either is NaN, then return the other one.
 */
static __isl_give isl_val *val_opt(__isl_take isl_val *v1,
	__isl_take isl_val *v2, int max)
{
	if (!v1 || !v2)
		goto error;
	if (isl_val_is_nan(v1)) {
		isl_val_free(v1);
		return v2;
	}
	if (isl_val_is_nan(v2)) {
		isl_val_free(v2);
		return v1;
	}
	if (max)
		return isl_val_max(v1, v2);
	else
		return isl_val_min(v1, v2);
error:
	isl_val_free(v1);
	isl_val_free(v2);
	return NULL;
}

/* Internal data structure for isl_pw_aff_opt_val.
 *
 * "max" is set if the maximum should be computed.
 * "res" contains the current optimum and is initialized to NaN.
 */
struct isl_pw_aff_opt_data {
	int max;

	isl_val *res;
};

/* Update the optimum in data->res with respect to the affine function
 * "aff" defined over "set".
 */
static isl_stat piece_opt(__isl_take isl_set *set, __isl_take isl_aff *aff,
	void *user)
{
	struct isl_pw_aff_opt_data *data = user;
	isl_val *opt;

	opt = isl_set_opt_val(set, data->max, aff);
	isl_set_free(set);
	isl_aff_free(aff);

	data->res = val_opt(data->res, opt, data->max);
	if (!data->res)
		return isl_stat_error;

	return isl_stat_ok;
}

/* Return the minimum (maximum if "max" is set) of the integer piecewise affine
 * expression "pa" over its definition domain.
 *
 * Return infinity or negative infinity if the optimal value is unbounded and
 * NaN if the domain of "pa" is empty.
 *
 * Initialize the result to NaN and then update it for each of the pieces
 * in "pa".
 */
static __isl_give isl_val *isl_pw_aff_opt_val(__isl_take isl_pw_aff *pa,
	int max)
{
	struct isl_pw_aff_opt_data data = { max };

	data.res = isl_val_nan(isl_pw_aff_get_ctx(pa));
	if (isl_pw_aff_foreach_piece(pa, &piece_opt, &data) < 0)
		data.res = isl_val_free(data.res);

	isl_pw_aff_free(pa);
	return data.res;
}

#undef TYPE
#define TYPE isl_pw_multi_aff
#include "isl_ilp_opt_multi_val_templ.c"

#undef TYPE
#define TYPE isl_multi_pw_aff
#include "isl_ilp_opt_multi_val_templ.c"

/* Internal data structure for isl_union_pw_aff_opt_val.
 *
 * "max" is set if the maximum should be computed.
 * "res" contains the current optimum and is initialized to NaN.
 */
struct isl_union_pw_aff_opt_data {
	int max;

	isl_val *res;
};

/* Update the optimum in data->res with the optimum of "pa".
 */
static isl_stat pw_aff_opt(__isl_take isl_pw_aff *pa, void *user)
{
	struct isl_union_pw_aff_opt_data *data = user;
	isl_val *opt;

	opt = isl_pw_aff_opt_val(pa, data->max);

	data->res = val_opt(data->res, opt, data->max);
	if (!data->res)
		return isl_stat_error;

	return isl_stat_ok;
}

/* Return the minimum (maximum if "max" is set) of the integer piecewise affine
 * expression "upa" over its definition domain.
 *
 * Return infinity or negative infinity if the optimal value is unbounded and
 * NaN if the domain of the expression is empty.
 *
 * Initialize the result to NaN and then update it
 * for each of the piecewise affine expressions in "upa".
 */
static __isl_give isl_val *isl_union_pw_aff_opt_val(
	__isl_take isl_union_pw_aff *upa, int max)
{
	struct isl_union_pw_aff_opt_data data = { max };

	data.res = isl_val_nan(isl_union_pw_aff_get_ctx(upa));
	if (isl_union_pw_aff_foreach_pw_aff(upa, &pw_aff_opt, &data) < 0)
		data.res = isl_val_free(data.res);
	isl_union_pw_aff_free(upa);

	return data.res;
}

/* Return the minimum of the integer piecewise affine
 * expression "upa" over its definition domain.
 *
 * Return negative infinity if the optimal value is unbounded and
 * NaN if the domain of the expression is empty.
 */
__isl_give isl_val *isl_union_pw_aff_min_val(__isl_take isl_union_pw_aff *upa)
{
	return isl_union_pw_aff_opt_val(upa, 0);
}

/* Return the maximum of the integer piecewise affine
 * expression "upa" over its definition domain.
 *
 * Return infinity if the optimal value is unbounded and
 * NaN if the domain of the expression is empty.
 */
__isl_give isl_val *isl_union_pw_aff_max_val(__isl_take isl_union_pw_aff *upa)
{
	return isl_union_pw_aff_opt_val(upa, 1);
}

/* Return a list of minima (maxima if "max" is set)
 * for each of the expressions in "mupa" over their domains.
 *
 * An element in the list is infinity or negative infinity if the optimal
 * value of the corresponding expression is unbounded and
 * NaN if the domain of the expression is empty.
 *
 * Iterate over all the expressions in "mupa" and collect the results.
 */
static __isl_give isl_multi_val *isl_multi_union_pw_aff_opt_multi_val(
	__isl_take isl_multi_union_pw_aff *mupa, int max)
{
	int i;
	isl_size n;
	isl_multi_val *mv;

	n = isl_multi_union_pw_aff_size(mupa);
	if (n < 0)
		mupa = isl_multi_union_pw_aff_free(mupa);
	if (!mupa)
		return NULL;

	mv = isl_multi_val_zero(isl_multi_union_pw_aff_get_space(mupa));

	for (i = 0; i < n; ++i) {
		isl_val *v;
		isl_union_pw_aff *upa;

		upa = isl_multi_union_pw_aff_get_union_pw_aff(mupa, i);
		v = isl_union_pw_aff_opt_val(upa, max);
		mv = isl_multi_val_set_val(mv, i, v);
	}

	isl_multi_union_pw_aff_free(mupa);
	return mv;
}

/* Return a list of minima (maxima if "max" is set) over the points in "uset"
 * for each of the expressions in "obj".
 *
 * An element in the list is infinity or negative infinity if the optimal
 * value of the corresponding expression is unbounded and
 * NaN if the intersection of "uset" with the domain of the expression
 * is empty.
 */
static __isl_give isl_multi_val *isl_union_set_opt_multi_union_pw_aff(
	__isl_keep isl_union_set *uset, int max,
	__isl_keep isl_multi_union_pw_aff *obj)
{
	uset = isl_union_set_copy(uset);
	obj = isl_multi_union_pw_aff_copy(obj);
	obj = isl_multi_union_pw_aff_intersect_domain(obj, uset);
	return isl_multi_union_pw_aff_opt_multi_val(obj, max);
}

/* Return a list of minima over the points in "uset"
 * for each of the expressions in "obj".
 *
 * An element in the list is infinity or negative infinity if the optimal
 * value of the corresponding expression is unbounded and
 * NaN if the intersection of "uset" with the domain of the expression
 * is empty.
 */
__isl_give isl_multi_val *isl_union_set_min_multi_union_pw_aff(
	__isl_keep isl_union_set *uset, __isl_keep isl_multi_union_pw_aff *obj)
{
	return isl_union_set_opt_multi_union_pw_aff(uset, 0, obj);
}

/* Return a list of minima
 * for each of the expressions in "mupa" over their domains.
 *
 * An element in the list is negative infinity if the optimal
 * value of the corresponding expression is unbounded and
 * NaN if the domain of the expression is empty.
 */
__isl_give isl_multi_val *isl_multi_union_pw_aff_min_multi_val(
	__isl_take isl_multi_union_pw_aff *mupa)
{
	return isl_multi_union_pw_aff_opt_multi_val(mupa, 0);
}

/* Return a list of maxima
 * for each of the expressions in "mupa" over their domains.
 *
 * An element in the list is infinity if the optimal
 * value of the corresponding expression is unbounded and
 * NaN if the domain of the expression is empty.
 */
__isl_give isl_multi_val *isl_multi_union_pw_aff_max_multi_val(
	__isl_take isl_multi_union_pw_aff *mupa)
{
	return isl_multi_union_pw_aff_opt_multi_val(mupa, 1);
}

#undef BASE
#define BASE	basic_set
#include "isl_ilp_opt_val_templ.c"

/* Return the maximal value attained by the given set dimension,
 * independently of the parameter values and of any other dimensions.
 *
 * Return infinity if the optimal value is unbounded and
 * NaN if "bset" is empty.
 */
__isl_give isl_val *isl_basic_set_dim_max_val(__isl_take isl_basic_set *bset,
	int pos)
{
	return isl_basic_set_dim_opt_val(bset, 1, pos);
}

#undef BASE
#define BASE	set
#include "isl_ilp_opt_val_templ.c"

/* Return the minimal value attained by the given set dimension,
 * independently of the parameter values and of any other dimensions.
 *
 * Return negative infinity if the optimal value is unbounded and
 * NaN if "set" is empty.
 */
__isl_give isl_val *isl_set_dim_min_val(__isl_take isl_set *set, int pos)
{
	return isl_set_dim_opt_val(set, 0, pos);
}

/* Return the maximal value attained by the given set dimension,
 * independently of the parameter values and of any other dimensions.
 *
 * Return infinity if the optimal value is unbounded and
 * NaN if "set" is empty.
 */
__isl_give isl_val *isl_set_dim_max_val(__isl_take isl_set *set, int pos)
{
	return isl_set_dim_opt_val(set, 1, pos);
}