2 * Copyright 2008-2009 Katholieke Universiteit Leuven
3 * Copyright 2010 INRIA Saclay
5 * Use of this software is governed by the GNU LGPLv2.1 license
7 * Written by Sven Verdoolaege, K.U.Leuven, Departement
8 * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
9 * and INRIA Saclay - Ile-de-France, Parc Club Orsay Universite,
10 * ZAC des vignes, 4 rue Jacques Monod, 91893 Orsay, France
13 #include <isl_ctx_private.h>
14 #include "isl_map_private.h"
17 #include "isl_sample.h"
18 #include <isl_mat_private.h>
21 * The implementation of parametric integer linear programming in this file
22 * was inspired by the paper "Parametric Integer Programming" and the
23 * report "Solving systems of affine (in)equalities" by Paul Feautrier
26 * The strategy used for obtaining a feasible solution is different
27 * from the one used in isl_tab.c. In particular, in isl_tab.c,
28 * upon finding a constraint that is not yet satisfied, we pivot
29 * in a row that increases the constant term of the row holding the
30 * constraint, making sure the sample solution remains feasible
31 * for all the constraints it already satisfied.
32 * Here, we always pivot in the row holding the constraint,
33 * choosing a column that induces the lexicographically smallest
34 * increment to the sample solution.
36 * By starting out from a sample value that is lexicographically
37 * smaller than any integer point in the problem space, the first
38 * feasible integer sample point we find will also be the lexicographically
39 * smallest. If all variables can be assumed to be non-negative,
40 * then the initial sample value may be chosen equal to zero.
41 * However, we will not make this assumption. Instead, we apply
42 * the "big parameter" trick. Any variable x is then not directly
43 * used in the tableau, but instead it is represented by another
44 * variable x' = M + x, where M is an arbitrarily large (positive)
45 * value. x' is therefore always non-negative, whatever the value of x.
46 * Taking as initial sample value x' = 0 corresponds to x = -M,
47 * which is always smaller than any possible value of x.
49 * The big parameter trick is used in the main tableau and
50 * also in the context tableau if isl_context_lex is used.
51 * In this case, each tableaus has its own big parameter.
52 * Before doing any real work, we check if all the parameters
53 * happen to be non-negative. If so, we drop the column corresponding
54 * to M from the initial context tableau.
55 * If isl_context_gbr is used, then the big parameter trick is only
56 * used in the main tableau.
60 struct isl_context_op {
61 /* detect nonnegative parameters in context and mark them in tab */
62 struct isl_tab *(*detect_nonnegative_parameters)(
63 struct isl_context *context, struct isl_tab *tab);
64 /* return temporary reference to basic set representation of context */
65 struct isl_basic_set *(*peek_basic_set)(struct isl_context *context);
66 /* return temporary reference to tableau representation of context */
67 struct isl_tab *(*peek_tab)(struct isl_context *context);
68 /* add equality; check is 1 if eq may not be valid;
69 * update is 1 if we may want to call ineq_sign on context later.
71 void (*add_eq)(struct isl_context *context, isl_int *eq,
72 int check, int update);
73 /* add inequality; check is 1 if ineq may not be valid;
74 * update is 1 if we may want to call ineq_sign on context later.
76 void (*add_ineq)(struct isl_context *context, isl_int *ineq,
77 int check, int update);
78 /* check sign of ineq based on previous information.
79 * strict is 1 if saturation should be treated as a positive sign.
81 enum isl_tab_row_sign (*ineq_sign)(struct isl_context *context,
82 isl_int *ineq, int strict);
83 /* check if inequality maintains feasibility */
84 int (*test_ineq)(struct isl_context *context, isl_int *ineq);
85 /* return index of a div that corresponds to "div" */
86 int (*get_div)(struct isl_context *context, struct isl_tab *tab,
88 /* add div "div" to context and return non-negativity */
89 int (*add_div)(struct isl_context *context, struct isl_vec *div);
90 int (*detect_equalities)(struct isl_context *context,
92 /* return row index of "best" split */
93 int (*best_split)(struct isl_context *context, struct isl_tab *tab);
94 /* check if context has already been determined to be empty */
95 int (*is_empty)(struct isl_context *context);
96 /* check if context is still usable */
97 int (*is_ok)(struct isl_context *context);
98 /* save a copy/snapshot of context */
99 void *(*save)(struct isl_context *context);
100 /* restore saved context */
101 void (*restore)(struct isl_context *context, void *);
102 /* invalidate context */
103 void (*invalidate)(struct isl_context *context);
105 void (*free)(struct isl_context *context);
109 struct isl_context_op *op;
112 struct isl_context_lex {
113 struct isl_context context;
117 struct isl_partial_sol {
119 struct isl_basic_set *dom;
122 struct isl_partial_sol *next;
126 struct isl_sol_callback {
127 struct isl_tab_callback callback;
131 /* isl_sol is an interface for constructing a solution to
132 * a parametric integer linear programming problem.
133 * Every time the algorithm reaches a state where a solution
134 * can be read off from the tableau (including cases where the tableau
135 * is empty), the function "add" is called on the isl_sol passed
136 * to find_solutions_main.
138 * The context tableau is owned by isl_sol and is updated incrementally.
140 * There are currently two implementations of this interface,
141 * isl_sol_map, which simply collects the solutions in an isl_map
142 * and (optionally) the parts of the context where there is no solution
144 * isl_sol_for, which calls a user-defined function for each part of
153 struct isl_context *context;
154 struct isl_partial_sol *partial;
155 void (*add)(struct isl_sol *sol,
156 struct isl_basic_set *dom, struct isl_mat *M);
157 void (*add_empty)(struct isl_sol *sol, struct isl_basic_set *bset);
158 void (*free)(struct isl_sol *sol);
159 struct isl_sol_callback dec_level;
162 static void sol_free(struct isl_sol *sol)
164 struct isl_partial_sol *partial, *next;
167 for (partial = sol->partial; partial; partial = next) {
168 next = partial->next;
169 isl_basic_set_free(partial->dom);
170 isl_mat_free(partial->M);
176 /* Push a partial solution represented by a domain and mapping M
177 * onto the stack of partial solutions.
179 static void sol_push_sol(struct isl_sol *sol,
180 struct isl_basic_set *dom, struct isl_mat *M)
182 struct isl_partial_sol *partial;
184 if (sol->error || !dom)
187 partial = isl_alloc_type(dom->ctx, struct isl_partial_sol);
191 partial->level = sol->level;
194 partial->next = sol->partial;
196 sol->partial = partial;
200 isl_basic_set_free(dom);
204 /* Pop one partial solution from the partial solution stack and
205 * pass it on to sol->add or sol->add_empty.
207 static void sol_pop_one(struct isl_sol *sol)
209 struct isl_partial_sol *partial;
211 partial = sol->partial;
212 sol->partial = partial->next;
215 sol->add(sol, partial->dom, partial->M);
217 sol->add_empty(sol, partial->dom);
221 /* Return a fresh copy of the domain represented by the context tableau.
223 static struct isl_basic_set *sol_domain(struct isl_sol *sol)
225 struct isl_basic_set *bset;
230 bset = isl_basic_set_dup(sol->context->op->peek_basic_set(sol->context));
231 bset = isl_basic_set_update_from_tab(bset,
232 sol->context->op->peek_tab(sol->context));
237 /* Check whether two partial solutions have the same mapping, where n_div
238 * is the number of divs that the two partial solutions have in common.
240 static int same_solution(struct isl_partial_sol *s1, struct isl_partial_sol *s2,
246 if (!s1->M != !s2->M)
251 dim = isl_basic_set_total_dim(s1->dom) - s1->dom->n_div;
253 for (i = 0; i < s1->M->n_row; ++i) {
254 if (isl_seq_first_non_zero(s1->M->row[i]+1+dim+n_div,
255 s1->M->n_col-1-dim-n_div) != -1)
257 if (isl_seq_first_non_zero(s2->M->row[i]+1+dim+n_div,
258 s2->M->n_col-1-dim-n_div) != -1)
260 if (!isl_seq_eq(s1->M->row[i], s2->M->row[i], 1+dim+n_div))
266 /* Pop all solutions from the partial solution stack that were pushed onto
267 * the stack at levels that are deeper than the current level.
268 * If the two topmost elements on the stack have the same level
269 * and represent the same solution, then their domains are combined.
270 * This combined domain is the same as the current context domain
271 * as sol_pop is called each time we move back to a higher level.
273 static void sol_pop(struct isl_sol *sol)
275 struct isl_partial_sol *partial;
281 if (sol->level == 0) {
282 for (partial = sol->partial; partial; partial = sol->partial)
287 partial = sol->partial;
291 if (partial->level <= sol->level)
294 if (partial->next && partial->next->level == partial->level) {
295 n_div = isl_basic_set_dim(
296 sol->context->op->peek_basic_set(sol->context),
299 if (!same_solution(partial, partial->next, n_div)) {
303 struct isl_basic_set *bset;
305 bset = sol_domain(sol);
307 isl_basic_set_free(partial->next->dom);
308 partial->next->dom = bset;
309 partial->next->level = sol->level;
311 sol->partial = partial->next;
312 isl_basic_set_free(partial->dom);
313 isl_mat_free(partial->M);
320 static void sol_dec_level(struct isl_sol *sol)
330 static int sol_dec_level_wrap(struct isl_tab_callback *cb)
332 struct isl_sol_callback *callback = (struct isl_sol_callback *)cb;
334 sol_dec_level(callback->sol);
336 return callback->sol->error ? -1 : 0;
339 /* Move down to next level and push callback onto context tableau
340 * to decrease the level again when it gets rolled back across
341 * the current state. That is, dec_level will be called with
342 * the context tableau in the same state as it is when inc_level
345 static void sol_inc_level(struct isl_sol *sol)
353 tab = sol->context->op->peek_tab(sol->context);
354 if (isl_tab_push_callback(tab, &sol->dec_level.callback) < 0)
358 static void scale_rows(struct isl_mat *mat, isl_int m, int n_row)
362 if (isl_int_is_one(m))
365 for (i = 0; i < n_row; ++i)
366 isl_seq_scale(mat->row[i], mat->row[i], m, mat->n_col);
369 /* Add the solution identified by the tableau and the context tableau.
371 * The layout of the variables is as follows.
372 * tab->n_var is equal to the total number of variables in the input
373 * map (including divs that were copied from the context)
374 * + the number of extra divs constructed
375 * Of these, the first tab->n_param and the last tab->n_div variables
376 * correspond to the variables in the context, i.e.,
377 * tab->n_param + tab->n_div = context_tab->n_var
378 * tab->n_param is equal to the number of parameters and input
379 * dimensions in the input map
380 * tab->n_div is equal to the number of divs in the context
382 * If there is no solution, then call add_empty with a basic set
383 * that corresponds to the context tableau. (If add_empty is NULL,
386 * If there is a solution, then first construct a matrix that maps
387 * all dimensions of the context to the output variables, i.e.,
388 * the output dimensions in the input map.
389 * The divs in the input map (if any) that do not correspond to any
390 * div in the context do not appear in the solution.
391 * The algorithm will make sure that they have an integer value,
392 * but these values themselves are of no interest.
393 * We have to be careful not to drop or rearrange any divs in the
394 * context because that would change the meaning of the matrix.
396 * To extract the value of the output variables, it should be noted
397 * that we always use a big parameter M in the main tableau and so
398 * the variable stored in this tableau is not an output variable x itself, but
399 * x' = M + x (in case of minimization)
401 * x' = M - x (in case of maximization)
402 * If x' appears in a column, then its optimal value is zero,
403 * which means that the optimal value of x is an unbounded number
404 * (-M for minimization and M for maximization).
405 * We currently assume that the output dimensions in the original map
406 * are bounded, so this cannot occur.
407 * Similarly, when x' appears in a row, then the coefficient of M in that
408 * row is necessarily 1.
409 * If the row in the tableau represents
410 * d x' = c + d M + e(y)
411 * then, in case of minimization, the corresponding row in the matrix
414 * with a d = m, the (updated) common denominator of the matrix.
415 * In case of maximization, the row will be
418 static void sol_add(struct isl_sol *sol, struct isl_tab *tab)
420 struct isl_basic_set *bset = NULL;
421 struct isl_mat *mat = NULL;
426 if (sol->error || !tab)
429 if (tab->empty && !sol->add_empty)
432 bset = sol_domain(sol);
435 sol_push_sol(sol, bset, NULL);
441 mat = isl_mat_alloc(tab->mat->ctx, 1 + sol->n_out,
442 1 + tab->n_param + tab->n_div);
448 isl_seq_clr(mat->row[0] + 1, mat->n_col - 1);
449 isl_int_set_si(mat->row[0][0], 1);
450 for (row = 0; row < sol->n_out; ++row) {
451 int i = tab->n_param + row;
454 isl_seq_clr(mat->row[1 + row], mat->n_col);
455 if (!tab->var[i].is_row) {
457 isl_die(mat->ctx, isl_error_invalid,
458 "unbounded optimum", goto error2);
462 r = tab->var[i].index;
464 isl_int_ne(tab->mat->row[r][2], tab->mat->row[r][0]))
465 isl_die(mat->ctx, isl_error_invalid,
466 "unbounded optimum", goto error2);
467 isl_int_gcd(m, mat->row[0][0], tab->mat->row[r][0]);
468 isl_int_divexact(m, tab->mat->row[r][0], m);
469 scale_rows(mat, m, 1 + row);
470 isl_int_divexact(m, mat->row[0][0], tab->mat->row[r][0]);
471 isl_int_mul(mat->row[1 + row][0], m, tab->mat->row[r][1]);
472 for (j = 0; j < tab->n_param; ++j) {
474 if (tab->var[j].is_row)
476 col = tab->var[j].index;
477 isl_int_mul(mat->row[1 + row][1 + j], m,
478 tab->mat->row[r][off + col]);
480 for (j = 0; j < tab->n_div; ++j) {
482 if (tab->var[tab->n_var - tab->n_div+j].is_row)
484 col = tab->var[tab->n_var - tab->n_div+j].index;
485 isl_int_mul(mat->row[1 + row][1 + tab->n_param + j], m,
486 tab->mat->row[r][off + col]);
489 isl_seq_neg(mat->row[1 + row], mat->row[1 + row],
495 sol_push_sol(sol, bset, mat);
500 isl_basic_set_free(bset);
508 struct isl_set *empty;
511 static void sol_map_free(struct isl_sol_map *sol_map)
515 if (sol_map->sol.context)
516 sol_map->sol.context->op->free(sol_map->sol.context);
517 isl_map_free(sol_map->map);
518 isl_set_free(sol_map->empty);
522 static void sol_map_free_wrap(struct isl_sol *sol)
524 sol_map_free((struct isl_sol_map *)sol);
527 /* This function is called for parts of the context where there is
528 * no solution, with "bset" corresponding to the context tableau.
529 * Simply add the basic set to the set "empty".
531 static void sol_map_add_empty(struct isl_sol_map *sol,
532 struct isl_basic_set *bset)
536 isl_assert(bset->ctx, sol->empty, goto error);
538 sol->empty = isl_set_grow(sol->empty, 1);
539 bset = isl_basic_set_simplify(bset);
540 bset = isl_basic_set_finalize(bset);
541 sol->empty = isl_set_add_basic_set(sol->empty, isl_basic_set_copy(bset));
544 isl_basic_set_free(bset);
547 isl_basic_set_free(bset);
551 static void sol_map_add_empty_wrap(struct isl_sol *sol,
552 struct isl_basic_set *bset)
554 sol_map_add_empty((struct isl_sol_map *)sol, bset);
557 /* Add bset to sol's empty, but only if we are actually collecting
560 static void sol_map_add_empty_if_needed(struct isl_sol_map *sol,
561 struct isl_basic_set *bset)
564 sol_map_add_empty(sol, bset);
566 isl_basic_set_free(bset);
569 /* Given a basic map "dom" that represents the context and an affine
570 * matrix "M" that maps the dimensions of the context to the
571 * output variables, construct a basic map with the same parameters
572 * and divs as the context, the dimensions of the context as input
573 * dimensions and a number of output dimensions that is equal to
574 * the number of output dimensions in the input map.
576 * The constraints and divs of the context are simply copied
577 * from "dom". For each row
581 * is added, with d the common denominator of M.
583 static void sol_map_add(struct isl_sol_map *sol,
584 struct isl_basic_set *dom, struct isl_mat *M)
587 struct isl_basic_map *bmap = NULL;
588 isl_basic_set *context_bset;
596 if (sol->sol.error || !dom || !M)
599 n_out = sol->sol.n_out;
600 n_eq = dom->n_eq + n_out;
601 n_ineq = dom->n_ineq;
603 nparam = isl_basic_set_total_dim(dom) - n_div;
604 total = isl_map_dim(sol->map, isl_dim_all);
605 bmap = isl_basic_map_alloc_dim(isl_map_get_dim(sol->map),
606 n_div, n_eq, 2 * n_div + n_ineq);
609 if (sol->sol.rational)
610 ISL_F_SET(bmap, ISL_BASIC_MAP_RATIONAL);
611 for (i = 0; i < dom->n_div; ++i) {
612 int k = isl_basic_map_alloc_div(bmap);
615 isl_seq_cpy(bmap->div[k], dom->div[i], 1 + 1 + nparam);
616 isl_seq_clr(bmap->div[k] + 1 + 1 + nparam, total - nparam);
617 isl_seq_cpy(bmap->div[k] + 1 + 1 + total,
618 dom->div[i] + 1 + 1 + nparam, i);
620 for (i = 0; i < dom->n_eq; ++i) {
621 int k = isl_basic_map_alloc_equality(bmap);
624 isl_seq_cpy(bmap->eq[k], dom->eq[i], 1 + nparam);
625 isl_seq_clr(bmap->eq[k] + 1 + nparam, total - nparam);
626 isl_seq_cpy(bmap->eq[k] + 1 + total,
627 dom->eq[i] + 1 + nparam, n_div);
629 for (i = 0; i < dom->n_ineq; ++i) {
630 int k = isl_basic_map_alloc_inequality(bmap);
633 isl_seq_cpy(bmap->ineq[k], dom->ineq[i], 1 + nparam);
634 isl_seq_clr(bmap->ineq[k] + 1 + nparam, total - nparam);
635 isl_seq_cpy(bmap->ineq[k] + 1 + total,
636 dom->ineq[i] + 1 + nparam, n_div);
638 for (i = 0; i < M->n_row - 1; ++i) {
639 int k = isl_basic_map_alloc_equality(bmap);
642 isl_seq_cpy(bmap->eq[k], M->row[1 + i], 1 + nparam);
643 isl_seq_clr(bmap->eq[k] + 1 + nparam, n_out);
644 isl_int_neg(bmap->eq[k][1 + nparam + i], M->row[0][0]);
645 isl_seq_cpy(bmap->eq[k] + 1 + nparam + n_out,
646 M->row[1 + i] + 1 + nparam, n_div);
648 bmap = isl_basic_map_simplify(bmap);
649 bmap = isl_basic_map_finalize(bmap);
650 sol->map = isl_map_grow(sol->map, 1);
651 sol->map = isl_map_add_basic_map(sol->map, bmap);
654 isl_basic_set_free(dom);
658 isl_basic_set_free(dom);
660 isl_basic_map_free(bmap);
664 static void sol_map_add_wrap(struct isl_sol *sol,
665 struct isl_basic_set *dom, struct isl_mat *M)
667 sol_map_add((struct isl_sol_map *)sol, dom, M);
671 /* Store the "parametric constant" of row "row" of tableau "tab" in "line",
672 * i.e., the constant term and the coefficients of all variables that
673 * appear in the context tableau.
674 * Note that the coefficient of the big parameter M is NOT copied.
675 * The context tableau may not have a big parameter and even when it
676 * does, it is a different big parameter.
678 static void get_row_parameter_line(struct isl_tab *tab, int row, isl_int *line)
681 unsigned off = 2 + tab->M;
683 isl_int_set(line[0], tab->mat->row[row][1]);
684 for (i = 0; i < tab->n_param; ++i) {
685 if (tab->var[i].is_row)
686 isl_int_set_si(line[1 + i], 0);
688 int col = tab->var[i].index;
689 isl_int_set(line[1 + i], tab->mat->row[row][off + col]);
692 for (i = 0; i < tab->n_div; ++i) {
693 if (tab->var[tab->n_var - tab->n_div + i].is_row)
694 isl_int_set_si(line[1 + tab->n_param + i], 0);
696 int col = tab->var[tab->n_var - tab->n_div + i].index;
697 isl_int_set(line[1 + tab->n_param + i],
698 tab->mat->row[row][off + col]);
703 /* Check if rows "row1" and "row2" have identical "parametric constants",
704 * as explained above.
705 * In this case, we also insist that the coefficients of the big parameter
706 * be the same as the values of the constants will only be the same
707 * if these coefficients are also the same.
709 static int identical_parameter_line(struct isl_tab *tab, int row1, int row2)
712 unsigned off = 2 + tab->M;
714 if (isl_int_ne(tab->mat->row[row1][1], tab->mat->row[row2][1]))
717 if (tab->M && isl_int_ne(tab->mat->row[row1][2],
718 tab->mat->row[row2][2]))
721 for (i = 0; i < tab->n_param + tab->n_div; ++i) {
722 int pos = i < tab->n_param ? i :
723 tab->n_var - tab->n_div + i - tab->n_param;
726 if (tab->var[pos].is_row)
728 col = tab->var[pos].index;
729 if (isl_int_ne(tab->mat->row[row1][off + col],
730 tab->mat->row[row2][off + col]))
736 /* Return an inequality that expresses that the "parametric constant"
737 * should be non-negative.
738 * This function is only called when the coefficient of the big parameter
741 static struct isl_vec *get_row_parameter_ineq(struct isl_tab *tab, int row)
743 struct isl_vec *ineq;
745 ineq = isl_vec_alloc(tab->mat->ctx, 1 + tab->n_param + tab->n_div);
749 get_row_parameter_line(tab, row, ineq->el);
751 ineq = isl_vec_normalize(ineq);
756 /* Return a integer division for use in a parametric cut based on the given row.
757 * In particular, let the parametric constant of the row be
761 * where y_0 = 1, but none of the y_i corresponds to the big parameter M.
762 * The div returned is equal to
764 * floor(\sum_i {-a_i} y_i) = floor((\sum_i (-a_i mod d) y_i)/d)
766 static struct isl_vec *get_row_parameter_div(struct isl_tab *tab, int row)
770 div = isl_vec_alloc(tab->mat->ctx, 1 + 1 + tab->n_param + tab->n_div);
774 isl_int_set(div->el[0], tab->mat->row[row][0]);
775 get_row_parameter_line(tab, row, div->el + 1);
776 div = isl_vec_normalize(div);
777 isl_seq_neg(div->el + 1, div->el + 1, div->size - 1);
778 isl_seq_fdiv_r(div->el + 1, div->el + 1, div->el[0], div->size - 1);
783 /* Return a integer division for use in transferring an integrality constraint
785 * In particular, let the parametric constant of the row be
789 * where y_0 = 1, but none of the y_i corresponds to the big parameter M.
790 * The the returned div is equal to
792 * floor(\sum_i {a_i} y_i) = floor((\sum_i (a_i mod d) y_i)/d)
794 static struct isl_vec *get_row_split_div(struct isl_tab *tab, int row)
798 div = isl_vec_alloc(tab->mat->ctx, 1 + 1 + tab->n_param + tab->n_div);
802 isl_int_set(div->el[0], tab->mat->row[row][0]);
803 get_row_parameter_line(tab, row, div->el + 1);
804 div = isl_vec_normalize(div);
805 isl_seq_fdiv_r(div->el + 1, div->el + 1, div->el[0], div->size - 1);
810 /* Construct and return an inequality that expresses an upper bound
812 * In particular, if the div is given by
816 * then the inequality expresses
820 static struct isl_vec *ineq_for_div(struct isl_basic_set *bset, unsigned div)
824 struct isl_vec *ineq;
829 total = isl_basic_set_total_dim(bset);
830 div_pos = 1 + total - bset->n_div + div;
832 ineq = isl_vec_alloc(bset->ctx, 1 + total);
836 isl_seq_cpy(ineq->el, bset->div[div] + 1, 1 + total);
837 isl_int_neg(ineq->el[div_pos], bset->div[div][0]);
841 /* Given a row in the tableau and a div that was created
842 * using get_row_split_div and that been constrained to equality, i.e.,
844 * d = floor(\sum_i {a_i} y_i) = \sum_i {a_i} y_i
846 * replace the expression "\sum_i {a_i} y_i" in the row by d,
847 * i.e., we subtract "\sum_i {a_i} y_i" and add 1 d.
848 * The coefficients of the non-parameters in the tableau have been
849 * verified to be integral. We can therefore simply replace coefficient b
850 * by floor(b). For the coefficients of the parameters we have
851 * floor(a_i) = a_i - {a_i}, while for the other coefficients, we have
854 static struct isl_tab *set_row_cst_to_div(struct isl_tab *tab, int row, int div)
856 isl_seq_fdiv_q(tab->mat->row[row] + 1, tab->mat->row[row] + 1,
857 tab->mat->row[row][0], 1 + tab->M + tab->n_col);
859 isl_int_set_si(tab->mat->row[row][0], 1);
861 if (tab->var[tab->n_var - tab->n_div + div].is_row) {
862 int drow = tab->var[tab->n_var - tab->n_div + div].index;
864 isl_assert(tab->mat->ctx,
865 isl_int_is_one(tab->mat->row[drow][0]), goto error);
866 isl_seq_combine(tab->mat->row[row] + 1,
867 tab->mat->ctx->one, tab->mat->row[row] + 1,
868 tab->mat->ctx->one, tab->mat->row[drow] + 1,
869 1 + tab->M + tab->n_col);
871 int dcol = tab->var[tab->n_var - tab->n_div + div].index;
873 isl_int_set_si(tab->mat->row[row][2 + tab->M + dcol], 1);
882 /* Check if the (parametric) constant of the given row is obviously
883 * negative, meaning that we don't need to consult the context tableau.
884 * If there is a big parameter and its coefficient is non-zero,
885 * then this coefficient determines the outcome.
886 * Otherwise, we check whether the constant is negative and
887 * all non-zero coefficients of parameters are negative and
888 * belong to non-negative parameters.
890 static int is_obviously_neg(struct isl_tab *tab, int row)
894 unsigned off = 2 + tab->M;
897 if (isl_int_is_pos(tab->mat->row[row][2]))
899 if (isl_int_is_neg(tab->mat->row[row][2]))
903 if (isl_int_is_nonneg(tab->mat->row[row][1]))
905 for (i = 0; i < tab->n_param; ++i) {
906 /* Eliminated parameter */
907 if (tab->var[i].is_row)
909 col = tab->var[i].index;
910 if (isl_int_is_zero(tab->mat->row[row][off + col]))
912 if (!tab->var[i].is_nonneg)
914 if (isl_int_is_pos(tab->mat->row[row][off + col]))
917 for (i = 0; i < tab->n_div; ++i) {
918 if (tab->var[tab->n_var - tab->n_div + i].is_row)
920 col = tab->var[tab->n_var - tab->n_div + i].index;
921 if (isl_int_is_zero(tab->mat->row[row][off + col]))
923 if (!tab->var[tab->n_var - tab->n_div + i].is_nonneg)
925 if (isl_int_is_pos(tab->mat->row[row][off + col]))
931 /* Check if the (parametric) constant of the given row is obviously
932 * non-negative, meaning that we don't need to consult the context tableau.
933 * If there is a big parameter and its coefficient is non-zero,
934 * then this coefficient determines the outcome.
935 * Otherwise, we check whether the constant is non-negative and
936 * all non-zero coefficients of parameters are positive and
937 * belong to non-negative parameters.
939 static int is_obviously_nonneg(struct isl_tab *tab, int row)
943 unsigned off = 2 + tab->M;
946 if (isl_int_is_pos(tab->mat->row[row][2]))
948 if (isl_int_is_neg(tab->mat->row[row][2]))
952 if (isl_int_is_neg(tab->mat->row[row][1]))
954 for (i = 0; i < tab->n_param; ++i) {
955 /* Eliminated parameter */
956 if (tab->var[i].is_row)
958 col = tab->var[i].index;
959 if (isl_int_is_zero(tab->mat->row[row][off + col]))
961 if (!tab->var[i].is_nonneg)
963 if (isl_int_is_neg(tab->mat->row[row][off + col]))
966 for (i = 0; i < tab->n_div; ++i) {
967 if (tab->var[tab->n_var - tab->n_div + i].is_row)
969 col = tab->var[tab->n_var - tab->n_div + i].index;
970 if (isl_int_is_zero(tab->mat->row[row][off + col]))
972 if (!tab->var[tab->n_var - tab->n_div + i].is_nonneg)
974 if (isl_int_is_neg(tab->mat->row[row][off + col]))
980 /* Given a row r and two columns, return the column that would
981 * lead to the lexicographically smallest increment in the sample
982 * solution when leaving the basis in favor of the row.
983 * Pivoting with column c will increment the sample value by a non-negative
984 * constant times a_{V,c}/a_{r,c}, with a_{V,c} the elements of column c
985 * corresponding to the non-parametric variables.
986 * If variable v appears in a column c_v, the a_{v,c} = 1 iff c = c_v,
987 * with all other entries in this virtual row equal to zero.
988 * If variable v appears in a row, then a_{v,c} is the element in column c
991 * Let v be the first variable with a_{v,c1}/a_{r,c1} != a_{v,c2}/a_{r,c2}.
992 * Then if a_{v,c1}/a_{r,c1} < a_{v,c2}/a_{r,c2}, i.e.,
993 * a_{v,c2} a_{r,c1} - a_{v,c1} a_{r,c2} > 0, c1 results in the minimal
994 * increment. Otherwise, it's c2.
996 static int lexmin_col_pair(struct isl_tab *tab,
997 int row, int col1, int col2, isl_int tmp)
1002 tr = tab->mat->row[row] + 2 + tab->M;
1004 for (i = tab->n_param; i < tab->n_var - tab->n_div; ++i) {
1008 if (!tab->var[i].is_row) {
1009 if (tab->var[i].index == col1)
1011 if (tab->var[i].index == col2)
1016 if (tab->var[i].index == row)
1019 r = tab->mat->row[tab->var[i].index] + 2 + tab->M;
1020 s1 = isl_int_sgn(r[col1]);
1021 s2 = isl_int_sgn(r[col2]);
1022 if (s1 == 0 && s2 == 0)
1029 isl_int_mul(tmp, r[col2], tr[col1]);
1030 isl_int_submul(tmp, r[col1], tr[col2]);
1031 if (isl_int_is_pos(tmp))
1033 if (isl_int_is_neg(tmp))
1039 /* Given a row in the tableau, find and return the column that would
1040 * result in the lexicographically smallest, but positive, increment
1041 * in the sample point.
1042 * If there is no such column, then return tab->n_col.
1043 * If anything goes wrong, return -1.
1045 static int lexmin_pivot_col(struct isl_tab *tab, int row)
1048 int col = tab->n_col;
1052 tr = tab->mat->row[row] + 2 + tab->M;
1056 for (j = tab->n_dead; j < tab->n_col; ++j) {
1057 if (tab->col_var[j] >= 0 &&
1058 (tab->col_var[j] < tab->n_param ||
1059 tab->col_var[j] >= tab->n_var - tab->n_div))
1062 if (!isl_int_is_pos(tr[j]))
1065 if (col == tab->n_col)
1068 col = lexmin_col_pair(tab, row, col, j, tmp);
1069 isl_assert(tab->mat->ctx, col >= 0, goto error);
1079 /* Return the first known violated constraint, i.e., a non-negative
1080 * constraint that currently has an either obviously negative value
1081 * or a previously determined to be negative value.
1083 * If any constraint has a negative coefficient for the big parameter,
1084 * if any, then we return one of these first.
1086 static int first_neg(struct isl_tab *tab)
1091 for (row = tab->n_redundant; row < tab->n_row; ++row) {
1092 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
1094 if (!isl_int_is_neg(tab->mat->row[row][2]))
1097 tab->row_sign[row] = isl_tab_row_neg;
1100 for (row = tab->n_redundant; row < tab->n_row; ++row) {
1101 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
1103 if (tab->row_sign) {
1104 if (tab->row_sign[row] == 0 &&
1105 is_obviously_neg(tab, row))
1106 tab->row_sign[row] = isl_tab_row_neg;
1107 if (tab->row_sign[row] != isl_tab_row_neg)
1109 } else if (!is_obviously_neg(tab, row))
1116 /* Check whether the invariant that all columns are lexico-positive
1117 * is satisfied. This function is not called from the current code
1118 * but is useful during debugging.
1120 static void check_lexpos(struct isl_tab *tab)
1122 unsigned off = 2 + tab->M;
1127 for (col = tab->n_dead; col < tab->n_col; ++col) {
1128 if (tab->col_var[col] >= 0 &&
1129 (tab->col_var[col] < tab->n_param ||
1130 tab->col_var[col] >= tab->n_var - tab->n_div))
1132 for (var = tab->n_param; var < tab->n_var - tab->n_div; ++var) {
1133 if (!tab->var[var].is_row) {
1134 if (tab->var[var].index == col)
1139 row = tab->var[var].index;
1140 if (isl_int_is_zero(tab->mat->row[row][off + col]))
1142 if (isl_int_is_pos(tab->mat->row[row][off + col]))
1144 fprintf(stderr, "lexneg column %d (row %d)\n",
1147 if (var >= tab->n_var - tab->n_div)
1148 fprintf(stderr, "zero column %d\n", col);
1152 /* Resolve all known or obviously violated constraints through pivoting.
1153 * In particular, as long as we can find any violated constraint, we
1154 * look for a pivoting column that would result in the lexicographically
1155 * smallest increment in the sample point. If there is no such column
1156 * then the tableau is infeasible.
1158 static int restore_lexmin(struct isl_tab *tab) WARN_UNUSED;
1159 static int restore_lexmin(struct isl_tab *tab)
1167 while ((row = first_neg(tab)) != -1) {
1168 col = lexmin_pivot_col(tab, row);
1169 if (col >= tab->n_col) {
1170 if (isl_tab_mark_empty(tab) < 0)
1176 if (isl_tab_pivot(tab, row, col) < 0)
1182 /* Given a row that represents an equality, look for an appropriate
1184 * In particular, if there are any non-zero coefficients among
1185 * the non-parameter variables, then we take the last of these
1186 * variables. Eliminating this variable in terms of the other
1187 * variables and/or parameters does not influence the property
1188 * that all column in the initial tableau are lexicographically
1189 * positive. The row corresponding to the eliminated variable
1190 * will only have non-zero entries below the diagonal of the
1191 * initial tableau. That is, we transform
1197 * If there is no such non-parameter variable, then we are dealing with
1198 * pure parameter equality and we pick any parameter with coefficient 1 or -1
1199 * for elimination. This will ensure that the eliminated parameter
1200 * always has an integer value whenever all the other parameters are integral.
1201 * If there is no such parameter then we return -1.
1203 static int last_var_col_or_int_par_col(struct isl_tab *tab, int row)
1205 unsigned off = 2 + tab->M;
1208 for (i = tab->n_var - tab->n_div - 1; i >= 0 && i >= tab->n_param; --i) {
1210 if (tab->var[i].is_row)
1212 col = tab->var[i].index;
1213 if (col <= tab->n_dead)
1215 if (!isl_int_is_zero(tab->mat->row[row][off + col]))
1218 for (i = tab->n_dead; i < tab->n_col; ++i) {
1219 if (isl_int_is_one(tab->mat->row[row][off + i]))
1221 if (isl_int_is_negone(tab->mat->row[row][off + i]))
1227 /* Add an equality that is known to be valid to the tableau.
1228 * We first check if we can eliminate a variable or a parameter.
1229 * If not, we add the equality as two inequalities.
1230 * In this case, the equality was a pure parameter equality and there
1231 * is no need to resolve any constraint violations.
1233 static struct isl_tab *add_lexmin_valid_eq(struct isl_tab *tab, isl_int *eq)
1240 r = isl_tab_add_row(tab, eq);
1244 r = tab->con[r].index;
1245 i = last_var_col_or_int_par_col(tab, r);
1247 tab->con[r].is_nonneg = 1;
1248 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1250 isl_seq_neg(eq, eq, 1 + tab->n_var);
1251 r = isl_tab_add_row(tab, eq);
1254 tab->con[r].is_nonneg = 1;
1255 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1258 if (isl_tab_pivot(tab, r, i) < 0)
1260 if (isl_tab_kill_col(tab, i) < 0)
1271 /* Check if the given row is a pure constant.
1273 static int is_constant(struct isl_tab *tab, int row)
1275 unsigned off = 2 + tab->M;
1277 return isl_seq_first_non_zero(tab->mat->row[row] + off + tab->n_dead,
1278 tab->n_col - tab->n_dead) == -1;
1281 /* Add an equality that may or may not be valid to the tableau.
1282 * If the resulting row is a pure constant, then it must be zero.
1283 * Otherwise, the resulting tableau is empty.
1285 * If the row is not a pure constant, then we add two inequalities,
1286 * each time checking that they can be satisfied.
1287 * In the end we try to use one of the two constraints to eliminate
1290 static struct isl_tab *add_lexmin_eq(struct isl_tab *tab, isl_int *eq) WARN_UNUSED;
1291 static struct isl_tab *add_lexmin_eq(struct isl_tab *tab, isl_int *eq)
1295 struct isl_tab_undo *snap;
1299 snap = isl_tab_snap(tab);
1300 r1 = isl_tab_add_row(tab, eq);
1303 tab->con[r1].is_nonneg = 1;
1304 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r1]) < 0)
1307 row = tab->con[r1].index;
1308 if (is_constant(tab, row)) {
1309 if (!isl_int_is_zero(tab->mat->row[row][1]) ||
1310 (tab->M && !isl_int_is_zero(tab->mat->row[row][2]))) {
1311 if (isl_tab_mark_empty(tab) < 0)
1315 if (isl_tab_rollback(tab, snap) < 0)
1320 if (restore_lexmin(tab) < 0)
1325 isl_seq_neg(eq, eq, 1 + tab->n_var);
1327 r2 = isl_tab_add_row(tab, eq);
1330 tab->con[r2].is_nonneg = 1;
1331 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r2]) < 0)
1334 if (restore_lexmin(tab) < 0)
1339 if (!tab->con[r1].is_row) {
1340 if (isl_tab_kill_col(tab, tab->con[r1].index) < 0)
1342 } else if (!tab->con[r2].is_row) {
1343 if (isl_tab_kill_col(tab, tab->con[r2].index) < 0)
1348 tab->bmap = isl_basic_map_add_ineq(tab->bmap, eq);
1349 if (isl_tab_push(tab, isl_tab_undo_bmap_ineq) < 0)
1351 isl_seq_neg(eq, eq, 1 + tab->n_var);
1352 tab->bmap = isl_basic_map_add_ineq(tab->bmap, eq);
1353 isl_seq_neg(eq, eq, 1 + tab->n_var);
1354 if (isl_tab_push(tab, isl_tab_undo_bmap_ineq) < 0)
1366 /* Add an inequality to the tableau, resolving violations using
1369 static struct isl_tab *add_lexmin_ineq(struct isl_tab *tab, isl_int *ineq)
1376 tab->bmap = isl_basic_map_add_ineq(tab->bmap, ineq);
1377 if (isl_tab_push(tab, isl_tab_undo_bmap_ineq) < 0)
1382 r = isl_tab_add_row(tab, ineq);
1385 tab->con[r].is_nonneg = 1;
1386 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1388 if (isl_tab_row_is_redundant(tab, tab->con[r].index)) {
1389 if (isl_tab_mark_redundant(tab, tab->con[r].index) < 0)
1394 if (restore_lexmin(tab) < 0)
1396 if (!tab->empty && tab->con[r].is_row &&
1397 isl_tab_row_is_redundant(tab, tab->con[r].index))
1398 if (isl_tab_mark_redundant(tab, tab->con[r].index) < 0)
1406 /* Check if the coefficients of the parameters are all integral.
1408 static int integer_parameter(struct isl_tab *tab, int row)
1412 unsigned off = 2 + tab->M;
1414 for (i = 0; i < tab->n_param; ++i) {
1415 /* Eliminated parameter */
1416 if (tab->var[i].is_row)
1418 col = tab->var[i].index;
1419 if (!isl_int_is_divisible_by(tab->mat->row[row][off + col],
1420 tab->mat->row[row][0]))
1423 for (i = 0; i < tab->n_div; ++i) {
1424 if (tab->var[tab->n_var - tab->n_div + i].is_row)
1426 col = tab->var[tab->n_var - tab->n_div + i].index;
1427 if (!isl_int_is_divisible_by(tab->mat->row[row][off + col],
1428 tab->mat->row[row][0]))
1434 /* Check if the coefficients of the non-parameter variables are all integral.
1436 static int integer_variable(struct isl_tab *tab, int row)
1439 unsigned off = 2 + tab->M;
1441 for (i = tab->n_dead; i < tab->n_col; ++i) {
1442 if (tab->col_var[i] >= 0 &&
1443 (tab->col_var[i] < tab->n_param ||
1444 tab->col_var[i] >= tab->n_var - tab->n_div))
1446 if (!isl_int_is_divisible_by(tab->mat->row[row][off + i],
1447 tab->mat->row[row][0]))
1453 /* Check if the constant term is integral.
1455 static int integer_constant(struct isl_tab *tab, int row)
1457 return isl_int_is_divisible_by(tab->mat->row[row][1],
1458 tab->mat->row[row][0]);
1461 #define I_CST 1 << 0
1462 #define I_PAR 1 << 1
1463 #define I_VAR 1 << 2
1465 /* Check for next (non-parameter) variable after "var" (first if var == -1)
1466 * that is non-integer and therefore requires a cut and return
1467 * the index of the variable.
1468 * For parametric tableaus, there are three parts in a row,
1469 * the constant, the coefficients of the parameters and the rest.
1470 * For each part, we check whether the coefficients in that part
1471 * are all integral and if so, set the corresponding flag in *f.
1472 * If the constant and the parameter part are integral, then the
1473 * current sample value is integral and no cut is required
1474 * (irrespective of whether the variable part is integral).
1476 static int next_non_integer_var(struct isl_tab *tab, int var, int *f)
1478 var = var < 0 ? tab->n_param : var + 1;
1480 for (; var < tab->n_var - tab->n_div; ++var) {
1483 if (!tab->var[var].is_row)
1485 row = tab->var[var].index;
1486 if (integer_constant(tab, row))
1487 ISL_FL_SET(flags, I_CST);
1488 if (integer_parameter(tab, row))
1489 ISL_FL_SET(flags, I_PAR);
1490 if (ISL_FL_ISSET(flags, I_CST) && ISL_FL_ISSET(flags, I_PAR))
1492 if (integer_variable(tab, row))
1493 ISL_FL_SET(flags, I_VAR);
1500 /* Check for first (non-parameter) variable that is non-integer and
1501 * therefore requires a cut and return the corresponding row.
1502 * For parametric tableaus, there are three parts in a row,
1503 * the constant, the coefficients of the parameters and the rest.
1504 * For each part, we check whether the coefficients in that part
1505 * are all integral and if so, set the corresponding flag in *f.
1506 * If the constant and the parameter part are integral, then the
1507 * current sample value is integral and no cut is required
1508 * (irrespective of whether the variable part is integral).
1510 static int first_non_integer_row(struct isl_tab *tab, int *f)
1512 int var = next_non_integer_var(tab, -1, f);
1514 return var < 0 ? -1 : tab->var[var].index;
1517 /* Add a (non-parametric) cut to cut away the non-integral sample
1518 * value of the given row.
1520 * If the row is given by
1522 * m r = f + \sum_i a_i y_i
1526 * c = - {-f/m} + \sum_i {a_i/m} y_i >= 0
1528 * The big parameter, if any, is ignored, since it is assumed to be big
1529 * enough to be divisible by any integer.
1530 * If the tableau is actually a parametric tableau, then this function
1531 * is only called when all coefficients of the parameters are integral.
1532 * The cut therefore has zero coefficients for the parameters.
1534 * The current value is known to be negative, so row_sign, if it
1535 * exists, is set accordingly.
1537 * Return the row of the cut or -1.
1539 static int add_cut(struct isl_tab *tab, int row)
1544 unsigned off = 2 + tab->M;
1546 if (isl_tab_extend_cons(tab, 1) < 0)
1548 r = isl_tab_allocate_con(tab);
1552 r_row = tab->mat->row[tab->con[r].index];
1553 isl_int_set(r_row[0], tab->mat->row[row][0]);
1554 isl_int_neg(r_row[1], tab->mat->row[row][1]);
1555 isl_int_fdiv_r(r_row[1], r_row[1], tab->mat->row[row][0]);
1556 isl_int_neg(r_row[1], r_row[1]);
1558 isl_int_set_si(r_row[2], 0);
1559 for (i = 0; i < tab->n_col; ++i)
1560 isl_int_fdiv_r(r_row[off + i],
1561 tab->mat->row[row][off + i], tab->mat->row[row][0]);
1563 tab->con[r].is_nonneg = 1;
1564 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1567 tab->row_sign[tab->con[r].index] = isl_tab_row_neg;
1569 return tab->con[r].index;
1572 /* Given a non-parametric tableau, add cuts until an integer
1573 * sample point is obtained or until the tableau is determined
1574 * to be integer infeasible.
1575 * As long as there is any non-integer value in the sample point,
1576 * we add appropriate cuts, if possible, for each of these
1577 * non-integer values and then resolve the violated
1578 * cut constraints using restore_lexmin.
1579 * If one of the corresponding rows is equal to an integral
1580 * combination of variables/constraints plus a non-integral constant,
1581 * then there is no way to obtain an integer point and we return
1582 * a tableau that is marked empty.
1584 static struct isl_tab *cut_to_integer_lexmin(struct isl_tab *tab)
1595 while ((var = next_non_integer_var(tab, -1, &flags)) != -1) {
1597 if (ISL_FL_ISSET(flags, I_VAR)) {
1598 if (isl_tab_mark_empty(tab) < 0)
1602 row = tab->var[var].index;
1603 row = add_cut(tab, row);
1606 } while ((var = next_non_integer_var(tab, var, &flags)) != -1);
1607 if (restore_lexmin(tab) < 0)
1618 /* Check whether all the currently active samples also satisfy the inequality
1619 * "ineq" (treated as an equality if eq is set).
1620 * Remove those samples that do not.
1622 static struct isl_tab *check_samples(struct isl_tab *tab, isl_int *ineq, int eq)
1630 isl_assert(tab->mat->ctx, tab->bmap, goto error);
1631 isl_assert(tab->mat->ctx, tab->samples, goto error);
1632 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var, goto error);
1635 for (i = tab->n_outside; i < tab->n_sample; ++i) {
1637 isl_seq_inner_product(ineq, tab->samples->row[i],
1638 1 + tab->n_var, &v);
1639 sgn = isl_int_sgn(v);
1640 if (eq ? (sgn == 0) : (sgn >= 0))
1642 tab = isl_tab_drop_sample(tab, i);
1654 /* Check whether the sample value of the tableau is finite,
1655 * i.e., either the tableau does not use a big parameter, or
1656 * all values of the variables are equal to the big parameter plus
1657 * some constant. This constant is the actual sample value.
1659 static int sample_is_finite(struct isl_tab *tab)
1666 for (i = 0; i < tab->n_var; ++i) {
1668 if (!tab->var[i].is_row)
1670 row = tab->var[i].index;
1671 if (isl_int_ne(tab->mat->row[row][0], tab->mat->row[row][2]))
1677 /* Check if the context tableau of sol has any integer points.
1678 * Leave tab in empty state if no integer point can be found.
1679 * If an integer point can be found and if moreover it is finite,
1680 * then it is added to the list of sample values.
1682 * This function is only called when none of the currently active sample
1683 * values satisfies the most recently added constraint.
1685 static struct isl_tab *check_integer_feasible(struct isl_tab *tab)
1687 struct isl_tab_undo *snap;
1693 snap = isl_tab_snap(tab);
1694 if (isl_tab_push_basis(tab) < 0)
1697 tab = cut_to_integer_lexmin(tab);
1701 if (!tab->empty && sample_is_finite(tab)) {
1702 struct isl_vec *sample;
1704 sample = isl_tab_get_sample_value(tab);
1706 tab = isl_tab_add_sample(tab, sample);
1709 if (!tab->empty && isl_tab_rollback(tab, snap) < 0)
1718 /* Check if any of the currently active sample values satisfies
1719 * the inequality "ineq" (an equality if eq is set).
1721 static int tab_has_valid_sample(struct isl_tab *tab, isl_int *ineq, int eq)
1729 isl_assert(tab->mat->ctx, tab->bmap, return -1);
1730 isl_assert(tab->mat->ctx, tab->samples, return -1);
1731 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var, return -1);
1734 for (i = tab->n_outside; i < tab->n_sample; ++i) {
1736 isl_seq_inner_product(ineq, tab->samples->row[i],
1737 1 + tab->n_var, &v);
1738 sgn = isl_int_sgn(v);
1739 if (eq ? (sgn == 0) : (sgn >= 0))
1744 return i < tab->n_sample;
1747 /* Add a div specified by "div" to the tableau "tab" and return
1748 * 1 if the div is obviously non-negative.
1750 static int context_tab_add_div(struct isl_tab *tab, struct isl_vec *div,
1751 int (*add_ineq)(void *user, isl_int *), void *user)
1755 struct isl_mat *samples;
1758 r = isl_tab_add_div(tab, div, add_ineq, user);
1761 nonneg = tab->var[r].is_nonneg;
1762 tab->var[r].frozen = 1;
1764 samples = isl_mat_extend(tab->samples,
1765 tab->n_sample, 1 + tab->n_var);
1766 tab->samples = samples;
1769 for (i = tab->n_outside; i < samples->n_row; ++i) {
1770 isl_seq_inner_product(div->el + 1, samples->row[i],
1771 div->size - 1, &samples->row[i][samples->n_col - 1]);
1772 isl_int_fdiv_q(samples->row[i][samples->n_col - 1],
1773 samples->row[i][samples->n_col - 1], div->el[0]);
1779 /* Add a div specified by "div" to both the main tableau and
1780 * the context tableau. In case of the main tableau, we only
1781 * need to add an extra div. In the context tableau, we also
1782 * need to express the meaning of the div.
1783 * Return the index of the div or -1 if anything went wrong.
1785 static int add_div(struct isl_tab *tab, struct isl_context *context,
1786 struct isl_vec *div)
1791 if ((nonneg = context->op->add_div(context, div)) < 0)
1794 if (!context->op->is_ok(context))
1797 if (isl_tab_extend_vars(tab, 1) < 0)
1799 r = isl_tab_allocate_var(tab);
1803 tab->var[r].is_nonneg = 1;
1804 tab->var[r].frozen = 1;
1807 return tab->n_div - 1;
1809 context->op->invalidate(context);
1813 static int find_div(struct isl_tab *tab, isl_int *div, isl_int denom)
1816 unsigned total = isl_basic_map_total_dim(tab->bmap);
1818 for (i = 0; i < tab->bmap->n_div; ++i) {
1819 if (isl_int_ne(tab->bmap->div[i][0], denom))
1821 if (!isl_seq_eq(tab->bmap->div[i] + 1, div, 1 + total))
1828 /* Return the index of a div that corresponds to "div".
1829 * We first check if we already have such a div and if not, we create one.
1831 static int get_div(struct isl_tab *tab, struct isl_context *context,
1832 struct isl_vec *div)
1835 struct isl_tab *context_tab = context->op->peek_tab(context);
1840 d = find_div(context_tab, div->el + 1, div->el[0]);
1844 return add_div(tab, context, div);
1847 /* Add a parametric cut to cut away the non-integral sample value
1849 * Let a_i be the coefficients of the constant term and the parameters
1850 * and let b_i be the coefficients of the variables or constraints
1851 * in basis of the tableau.
1852 * Let q be the div q = floor(\sum_i {-a_i} y_i).
1854 * The cut is expressed as
1856 * c = \sum_i -{-a_i} y_i + \sum_i {b_i} x_i + q >= 0
1858 * If q did not already exist in the context tableau, then it is added first.
1859 * If q is in a column of the main tableau then the "+ q" can be accomplished
1860 * by setting the corresponding entry to the denominator of the constraint.
1861 * If q happens to be in a row of the main tableau, then the corresponding
1862 * row needs to be added instead (taking care of the denominators).
1863 * Note that this is very unlikely, but perhaps not entirely impossible.
1865 * The current value of the cut is known to be negative (or at least
1866 * non-positive), so row_sign is set accordingly.
1868 * Return the row of the cut or -1.
1870 static int add_parametric_cut(struct isl_tab *tab, int row,
1871 struct isl_context *context)
1873 struct isl_vec *div;
1880 unsigned off = 2 + tab->M;
1885 div = get_row_parameter_div(tab, row);
1890 d = context->op->get_div(context, tab, div);
1894 if (isl_tab_extend_cons(tab, 1) < 0)
1896 r = isl_tab_allocate_con(tab);
1900 r_row = tab->mat->row[tab->con[r].index];
1901 isl_int_set(r_row[0], tab->mat->row[row][0]);
1902 isl_int_neg(r_row[1], tab->mat->row[row][1]);
1903 isl_int_fdiv_r(r_row[1], r_row[1], tab->mat->row[row][0]);
1904 isl_int_neg(r_row[1], r_row[1]);
1906 isl_int_set_si(r_row[2], 0);
1907 for (i = 0; i < tab->n_param; ++i) {
1908 if (tab->var[i].is_row)
1910 col = tab->var[i].index;
1911 isl_int_neg(r_row[off + col], tab->mat->row[row][off + col]);
1912 isl_int_fdiv_r(r_row[off + col], r_row[off + col],
1913 tab->mat->row[row][0]);
1914 isl_int_neg(r_row[off + col], r_row[off + col]);
1916 for (i = 0; i < tab->n_div; ++i) {
1917 if (tab->var[tab->n_var - tab->n_div + i].is_row)
1919 col = tab->var[tab->n_var - tab->n_div + i].index;
1920 isl_int_neg(r_row[off + col], tab->mat->row[row][off + col]);
1921 isl_int_fdiv_r(r_row[off + col], r_row[off + col],
1922 tab->mat->row[row][0]);
1923 isl_int_neg(r_row[off + col], r_row[off + col]);
1925 for (i = 0; i < tab->n_col; ++i) {
1926 if (tab->col_var[i] >= 0 &&
1927 (tab->col_var[i] < tab->n_param ||
1928 tab->col_var[i] >= tab->n_var - tab->n_div))
1930 isl_int_fdiv_r(r_row[off + i],
1931 tab->mat->row[row][off + i], tab->mat->row[row][0]);
1933 if (tab->var[tab->n_var - tab->n_div + d].is_row) {
1935 int d_row = tab->var[tab->n_var - tab->n_div + d].index;
1937 isl_int_gcd(gcd, tab->mat->row[d_row][0], r_row[0]);
1938 isl_int_divexact(r_row[0], r_row[0], gcd);
1939 isl_int_divexact(gcd, tab->mat->row[d_row][0], gcd);
1940 isl_seq_combine(r_row + 1, gcd, r_row + 1,
1941 r_row[0], tab->mat->row[d_row] + 1,
1942 off - 1 + tab->n_col);
1943 isl_int_mul(r_row[0], r_row[0], tab->mat->row[d_row][0]);
1946 col = tab->var[tab->n_var - tab->n_div + d].index;
1947 isl_int_set(r_row[off + col], tab->mat->row[row][0]);
1950 tab->con[r].is_nonneg = 1;
1951 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1954 tab->row_sign[tab->con[r].index] = isl_tab_row_neg;
1958 row = tab->con[r].index;
1960 if (d >= n && context->op->detect_equalities(context, tab) < 0)
1966 /* Construct a tableau for bmap that can be used for computing
1967 * the lexicographic minimum (or maximum) of bmap.
1968 * If not NULL, then dom is the domain where the minimum
1969 * should be computed. In this case, we set up a parametric
1970 * tableau with row signs (initialized to "unknown").
1971 * If M is set, then the tableau will use a big parameter.
1972 * If max is set, then a maximum should be computed instead of a minimum.
1973 * This means that for each variable x, the tableau will contain the variable
1974 * x' = M - x, rather than x' = M + x. This in turn means that the coefficient
1975 * of the variables in all constraints are negated prior to adding them
1978 static struct isl_tab *tab_for_lexmin(struct isl_basic_map *bmap,
1979 struct isl_basic_set *dom, unsigned M, int max)
1982 struct isl_tab *tab;
1984 tab = isl_tab_alloc(bmap->ctx, 2 * bmap->n_eq + bmap->n_ineq + 1,
1985 isl_basic_map_total_dim(bmap), M);
1989 tab->rational = ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL);
1991 tab->n_param = isl_basic_set_total_dim(dom) - dom->n_div;
1992 tab->n_div = dom->n_div;
1993 tab->row_sign = isl_calloc_array(bmap->ctx,
1994 enum isl_tab_row_sign, tab->mat->n_row);
1998 if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_EMPTY)) {
1999 if (isl_tab_mark_empty(tab) < 0)
2004 for (i = tab->n_param; i < tab->n_var - tab->n_div; ++i) {
2005 tab->var[i].is_nonneg = 1;
2006 tab->var[i].frozen = 1;
2008 for (i = 0; i < bmap->n_eq; ++i) {
2010 isl_seq_neg(bmap->eq[i] + 1 + tab->n_param,
2011 bmap->eq[i] + 1 + tab->n_param,
2012 tab->n_var - tab->n_param - tab->n_div);
2013 tab = add_lexmin_valid_eq(tab, bmap->eq[i]);
2015 isl_seq_neg(bmap->eq[i] + 1 + tab->n_param,
2016 bmap->eq[i] + 1 + tab->n_param,
2017 tab->n_var - tab->n_param - tab->n_div);
2018 if (!tab || tab->empty)
2021 if (bmap->n_eq && restore_lexmin(tab) < 0)
2023 for (i = 0; i < bmap->n_ineq; ++i) {
2025 isl_seq_neg(bmap->ineq[i] + 1 + tab->n_param,
2026 bmap->ineq[i] + 1 + tab->n_param,
2027 tab->n_var - tab->n_param - tab->n_div);
2028 tab = add_lexmin_ineq(tab, bmap->ineq[i]);
2030 isl_seq_neg(bmap->ineq[i] + 1 + tab->n_param,
2031 bmap->ineq[i] + 1 + tab->n_param,
2032 tab->n_var - tab->n_param - tab->n_div);
2033 if (!tab || tab->empty)
2042 /* Given a main tableau where more than one row requires a split,
2043 * determine and return the "best" row to split on.
2045 * Given two rows in the main tableau, if the inequality corresponding
2046 * to the first row is redundant with respect to that of the second row
2047 * in the current tableau, then it is better to split on the second row,
2048 * since in the positive part, both row will be positive.
2049 * (In the negative part a pivot will have to be performed and just about
2050 * anything can happen to the sign of the other row.)
2052 * As a simple heuristic, we therefore select the row that makes the most
2053 * of the other rows redundant.
2055 * Perhaps it would also be useful to look at the number of constraints
2056 * that conflict with any given constraint.
2058 static int best_split(struct isl_tab *tab, struct isl_tab *context_tab)
2060 struct isl_tab_undo *snap;
2066 if (isl_tab_extend_cons(context_tab, 2) < 0)
2069 snap = isl_tab_snap(context_tab);
2071 for (split = tab->n_redundant; split < tab->n_row; ++split) {
2072 struct isl_tab_undo *snap2;
2073 struct isl_vec *ineq = NULL;
2077 if (!isl_tab_var_from_row(tab, split)->is_nonneg)
2079 if (tab->row_sign[split] != isl_tab_row_any)
2082 ineq = get_row_parameter_ineq(tab, split);
2085 ok = isl_tab_add_ineq(context_tab, ineq->el) >= 0;
2090 snap2 = isl_tab_snap(context_tab);
2092 for (row = tab->n_redundant; row < tab->n_row; ++row) {
2093 struct isl_tab_var *var;
2097 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
2099 if (tab->row_sign[row] != isl_tab_row_any)
2102 ineq = get_row_parameter_ineq(tab, row);
2105 ok = isl_tab_add_ineq(context_tab, ineq->el) >= 0;
2109 var = &context_tab->con[context_tab->n_con - 1];
2110 if (!context_tab->empty &&
2111 !isl_tab_min_at_most_neg_one(context_tab, var))
2113 if (isl_tab_rollback(context_tab, snap2) < 0)
2116 if (best == -1 || r > best_r) {
2120 if (isl_tab_rollback(context_tab, snap) < 0)
2127 static struct isl_basic_set *context_lex_peek_basic_set(
2128 struct isl_context *context)
2130 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2133 return isl_tab_peek_bset(clex->tab);
2136 static struct isl_tab *context_lex_peek_tab(struct isl_context *context)
2138 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2142 static void context_lex_extend(struct isl_context *context, int n)
2144 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2147 if (isl_tab_extend_cons(clex->tab, n) >= 0)
2149 isl_tab_free(clex->tab);
2153 static void context_lex_add_eq(struct isl_context *context, isl_int *eq,
2154 int check, int update)
2156 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2157 if (isl_tab_extend_cons(clex->tab, 2) < 0)
2159 clex->tab = add_lexmin_eq(clex->tab, eq);
2161 int v = tab_has_valid_sample(clex->tab, eq, 1);
2165 clex->tab = check_integer_feasible(clex->tab);
2168 clex->tab = check_samples(clex->tab, eq, 1);
2171 isl_tab_free(clex->tab);
2175 static void context_lex_add_ineq(struct isl_context *context, isl_int *ineq,
2176 int check, int update)
2178 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2179 if (isl_tab_extend_cons(clex->tab, 1) < 0)
2181 clex->tab = add_lexmin_ineq(clex->tab, ineq);
2183 int v = tab_has_valid_sample(clex->tab, ineq, 0);
2187 clex->tab = check_integer_feasible(clex->tab);
2190 clex->tab = check_samples(clex->tab, ineq, 0);
2193 isl_tab_free(clex->tab);
2197 static int context_lex_add_ineq_wrap(void *user, isl_int *ineq)
2199 struct isl_context *context = (struct isl_context *)user;
2200 context_lex_add_ineq(context, ineq, 0, 0);
2201 return context->op->is_ok(context) ? 0 : -1;
2204 /* Check which signs can be obtained by "ineq" on all the currently
2205 * active sample values. See row_sign for more information.
2207 static enum isl_tab_row_sign tab_ineq_sign(struct isl_tab *tab, isl_int *ineq,
2213 enum isl_tab_row_sign res = isl_tab_row_unknown;
2215 isl_assert(tab->mat->ctx, tab->samples, return isl_tab_row_unknown);
2216 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var,
2217 return isl_tab_row_unknown);
2220 for (i = tab->n_outside; i < tab->n_sample; ++i) {
2221 isl_seq_inner_product(tab->samples->row[i], ineq,
2222 1 + tab->n_var, &tmp);
2223 sgn = isl_int_sgn(tmp);
2224 if (sgn > 0 || (sgn == 0 && strict)) {
2225 if (res == isl_tab_row_unknown)
2226 res = isl_tab_row_pos;
2227 if (res == isl_tab_row_neg)
2228 res = isl_tab_row_any;
2231 if (res == isl_tab_row_unknown)
2232 res = isl_tab_row_neg;
2233 if (res == isl_tab_row_pos)
2234 res = isl_tab_row_any;
2236 if (res == isl_tab_row_any)
2244 static enum isl_tab_row_sign context_lex_ineq_sign(struct isl_context *context,
2245 isl_int *ineq, int strict)
2247 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2248 return tab_ineq_sign(clex->tab, ineq, strict);
2251 /* Check whether "ineq" can be added to the tableau without rendering
2254 static int context_lex_test_ineq(struct isl_context *context, isl_int *ineq)
2256 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2257 struct isl_tab_undo *snap;
2263 if (isl_tab_extend_cons(clex->tab, 1) < 0)
2266 snap = isl_tab_snap(clex->tab);
2267 if (isl_tab_push_basis(clex->tab) < 0)
2269 clex->tab = add_lexmin_ineq(clex->tab, ineq);
2270 clex->tab = check_integer_feasible(clex->tab);
2273 feasible = !clex->tab->empty;
2274 if (isl_tab_rollback(clex->tab, snap) < 0)
2280 static int context_lex_get_div(struct isl_context *context, struct isl_tab *tab,
2281 struct isl_vec *div)
2283 return get_div(tab, context, div);
2286 /* Add a div specified by "div" to the context tableau and return
2287 * 1 if the div is obviously non-negative.
2288 * context_tab_add_div will always return 1, because all variables
2289 * in a isl_context_lex tableau are non-negative.
2290 * However, if we are using a big parameter in the context, then this only
2291 * reflects the non-negativity of the variable used to _encode_ the
2292 * div, i.e., div' = M + div, so we can't draw any conclusions.
2294 static int context_lex_add_div(struct isl_context *context, struct isl_vec *div)
2296 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2298 nonneg = context_tab_add_div(clex->tab, div,
2299 context_lex_add_ineq_wrap, context);
2307 static int context_lex_detect_equalities(struct isl_context *context,
2308 struct isl_tab *tab)
2313 static int context_lex_best_split(struct isl_context *context,
2314 struct isl_tab *tab)
2316 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2317 struct isl_tab_undo *snap;
2320 snap = isl_tab_snap(clex->tab);
2321 if (isl_tab_push_basis(clex->tab) < 0)
2323 r = best_split(tab, clex->tab);
2325 if (r >= 0 && isl_tab_rollback(clex->tab, snap) < 0)
2331 static int context_lex_is_empty(struct isl_context *context)
2333 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2336 return clex->tab->empty;
2339 static void *context_lex_save(struct isl_context *context)
2341 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2342 struct isl_tab_undo *snap;
2344 snap = isl_tab_snap(clex->tab);
2345 if (isl_tab_push_basis(clex->tab) < 0)
2347 if (isl_tab_save_samples(clex->tab) < 0)
2353 static void context_lex_restore(struct isl_context *context, void *save)
2355 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2356 if (isl_tab_rollback(clex->tab, (struct isl_tab_undo *)save) < 0) {
2357 isl_tab_free(clex->tab);
2362 static int context_lex_is_ok(struct isl_context *context)
2364 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2368 /* For each variable in the context tableau, check if the variable can
2369 * only attain non-negative values. If so, mark the parameter as non-negative
2370 * in the main tableau. This allows for a more direct identification of some
2371 * cases of violated constraints.
2373 static struct isl_tab *tab_detect_nonnegative_parameters(struct isl_tab *tab,
2374 struct isl_tab *context_tab)
2377 struct isl_tab_undo *snap;
2378 struct isl_vec *ineq = NULL;
2379 struct isl_tab_var *var;
2382 if (context_tab->n_var == 0)
2385 ineq = isl_vec_alloc(tab->mat->ctx, 1 + context_tab->n_var);
2389 if (isl_tab_extend_cons(context_tab, 1) < 0)
2392 snap = isl_tab_snap(context_tab);
2395 isl_seq_clr(ineq->el, ineq->size);
2396 for (i = 0; i < context_tab->n_var; ++i) {
2397 isl_int_set_si(ineq->el[1 + i], 1);
2398 if (isl_tab_add_ineq(context_tab, ineq->el) < 0)
2400 var = &context_tab->con[context_tab->n_con - 1];
2401 if (!context_tab->empty &&
2402 !isl_tab_min_at_most_neg_one(context_tab, var)) {
2404 if (i >= tab->n_param)
2405 j = i - tab->n_param + tab->n_var - tab->n_div;
2406 tab->var[j].is_nonneg = 1;
2409 isl_int_set_si(ineq->el[1 + i], 0);
2410 if (isl_tab_rollback(context_tab, snap) < 0)
2414 if (context_tab->M && n == context_tab->n_var) {
2415 context_tab->mat = isl_mat_drop_cols(context_tab->mat, 2, 1);
2427 static struct isl_tab *context_lex_detect_nonnegative_parameters(
2428 struct isl_context *context, struct isl_tab *tab)
2430 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2431 struct isl_tab_undo *snap;
2436 snap = isl_tab_snap(clex->tab);
2437 if (isl_tab_push_basis(clex->tab) < 0)
2440 tab = tab_detect_nonnegative_parameters(tab, clex->tab);
2442 if (isl_tab_rollback(clex->tab, snap) < 0)
2451 static void context_lex_invalidate(struct isl_context *context)
2453 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2454 isl_tab_free(clex->tab);
2458 static void context_lex_free(struct isl_context *context)
2460 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2461 isl_tab_free(clex->tab);
2465 struct isl_context_op isl_context_lex_op = {
2466 context_lex_detect_nonnegative_parameters,
2467 context_lex_peek_basic_set,
2468 context_lex_peek_tab,
2470 context_lex_add_ineq,
2471 context_lex_ineq_sign,
2472 context_lex_test_ineq,
2473 context_lex_get_div,
2474 context_lex_add_div,
2475 context_lex_detect_equalities,
2476 context_lex_best_split,
2477 context_lex_is_empty,
2480 context_lex_restore,
2481 context_lex_invalidate,
2485 static struct isl_tab *context_tab_for_lexmin(struct isl_basic_set *bset)
2487 struct isl_tab *tab;
2489 bset = isl_basic_set_cow(bset);
2492 tab = tab_for_lexmin((struct isl_basic_map *)bset, NULL, 1, 0);
2495 if (isl_tab_track_bset(tab, bset) < 0)
2497 tab = isl_tab_init_samples(tab);
2500 isl_basic_set_free(bset);
2504 static struct isl_context *isl_context_lex_alloc(struct isl_basic_set *dom)
2506 struct isl_context_lex *clex;
2511 clex = isl_alloc_type(dom->ctx, struct isl_context_lex);
2515 clex->context.op = &isl_context_lex_op;
2517 clex->tab = context_tab_for_lexmin(isl_basic_set_copy(dom));
2518 if (restore_lexmin(clex->tab) < 0)
2520 clex->tab = check_integer_feasible(clex->tab);
2524 return &clex->context;
2526 clex->context.op->free(&clex->context);
2530 struct isl_context_gbr {
2531 struct isl_context context;
2532 struct isl_tab *tab;
2533 struct isl_tab *shifted;
2534 struct isl_tab *cone;
2537 static struct isl_tab *context_gbr_detect_nonnegative_parameters(
2538 struct isl_context *context, struct isl_tab *tab)
2540 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2543 return tab_detect_nonnegative_parameters(tab, cgbr->tab);
2546 static struct isl_basic_set *context_gbr_peek_basic_set(
2547 struct isl_context *context)
2549 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2552 return isl_tab_peek_bset(cgbr->tab);
2555 static struct isl_tab *context_gbr_peek_tab(struct isl_context *context)
2557 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2561 /* Initialize the "shifted" tableau of the context, which
2562 * contains the constraints of the original tableau shifted
2563 * by the sum of all negative coefficients. This ensures
2564 * that any rational point in the shifted tableau can
2565 * be rounded up to yield an integer point in the original tableau.
2567 static void gbr_init_shifted(struct isl_context_gbr *cgbr)
2570 struct isl_vec *cst;
2571 struct isl_basic_set *bset = isl_tab_peek_bset(cgbr->tab);
2572 unsigned dim = isl_basic_set_total_dim(bset);
2574 cst = isl_vec_alloc(cgbr->tab->mat->ctx, bset->n_ineq);
2578 for (i = 0; i < bset->n_ineq; ++i) {
2579 isl_int_set(cst->el[i], bset->ineq[i][0]);
2580 for (j = 0; j < dim; ++j) {
2581 if (!isl_int_is_neg(bset->ineq[i][1 + j]))
2583 isl_int_add(bset->ineq[i][0], bset->ineq[i][0],
2584 bset->ineq[i][1 + j]);
2588 cgbr->shifted = isl_tab_from_basic_set(bset);
2590 for (i = 0; i < bset->n_ineq; ++i)
2591 isl_int_set(bset->ineq[i][0], cst->el[i]);
2596 /* Check if the shifted tableau is non-empty, and if so
2597 * use the sample point to construct an integer point
2598 * of the context tableau.
2600 static struct isl_vec *gbr_get_shifted_sample(struct isl_context_gbr *cgbr)
2602 struct isl_vec *sample;
2605 gbr_init_shifted(cgbr);
2608 if (cgbr->shifted->empty)
2609 return isl_vec_alloc(cgbr->tab->mat->ctx, 0);
2611 sample = isl_tab_get_sample_value(cgbr->shifted);
2612 sample = isl_vec_ceil(sample);
2617 static struct isl_basic_set *drop_constant_terms(struct isl_basic_set *bset)
2624 for (i = 0; i < bset->n_eq; ++i)
2625 isl_int_set_si(bset->eq[i][0], 0);
2627 for (i = 0; i < bset->n_ineq; ++i)
2628 isl_int_set_si(bset->ineq[i][0], 0);
2633 static int use_shifted(struct isl_context_gbr *cgbr)
2635 return cgbr->tab->bmap->n_eq == 0 && cgbr->tab->bmap->n_div == 0;
2638 static struct isl_vec *gbr_get_sample(struct isl_context_gbr *cgbr)
2640 struct isl_basic_set *bset;
2641 struct isl_basic_set *cone;
2643 if (isl_tab_sample_is_integer(cgbr->tab))
2644 return isl_tab_get_sample_value(cgbr->tab);
2646 if (use_shifted(cgbr)) {
2647 struct isl_vec *sample;
2649 sample = gbr_get_shifted_sample(cgbr);
2650 if (!sample || sample->size > 0)
2653 isl_vec_free(sample);
2657 bset = isl_tab_peek_bset(cgbr->tab);
2658 cgbr->cone = isl_tab_from_recession_cone(bset, 0);
2661 if (isl_tab_track_bset(cgbr->cone, isl_basic_set_dup(bset)) < 0)
2664 if (isl_tab_detect_implicit_equalities(cgbr->cone) < 0)
2667 if (cgbr->cone->n_dead == cgbr->cone->n_col) {
2668 struct isl_vec *sample;
2669 struct isl_tab_undo *snap;
2671 if (cgbr->tab->basis) {
2672 if (cgbr->tab->basis->n_col != 1 + cgbr->tab->n_var) {
2673 isl_mat_free(cgbr->tab->basis);
2674 cgbr->tab->basis = NULL;
2676 cgbr->tab->n_zero = 0;
2677 cgbr->tab->n_unbounded = 0;
2680 snap = isl_tab_snap(cgbr->tab);
2682 sample = isl_tab_sample(cgbr->tab);
2684 if (isl_tab_rollback(cgbr->tab, snap) < 0) {
2685 isl_vec_free(sample);
2692 cone = isl_basic_set_dup(isl_tab_peek_bset(cgbr->cone));
2693 cone = drop_constant_terms(cone);
2694 cone = isl_basic_set_update_from_tab(cone, cgbr->cone);
2695 cone = isl_basic_set_underlying_set(cone);
2696 cone = isl_basic_set_gauss(cone, NULL);
2698 bset = isl_basic_set_dup(isl_tab_peek_bset(cgbr->tab));
2699 bset = isl_basic_set_update_from_tab(bset, cgbr->tab);
2700 bset = isl_basic_set_underlying_set(bset);
2701 bset = isl_basic_set_gauss(bset, NULL);
2703 return isl_basic_set_sample_with_cone(bset, cone);
2706 static void check_gbr_integer_feasible(struct isl_context_gbr *cgbr)
2708 struct isl_vec *sample;
2713 if (cgbr->tab->empty)
2716 sample = gbr_get_sample(cgbr);
2720 if (sample->size == 0) {
2721 isl_vec_free(sample);
2722 if (isl_tab_mark_empty(cgbr->tab) < 0)
2727 cgbr->tab = isl_tab_add_sample(cgbr->tab, sample);
2731 isl_tab_free(cgbr->tab);
2735 static struct isl_tab *add_gbr_eq(struct isl_tab *tab, isl_int *eq)
2742 if (isl_tab_extend_cons(tab, 2) < 0)
2745 if (isl_tab_add_eq(tab, eq) < 0)
2754 static void context_gbr_add_eq(struct isl_context *context, isl_int *eq,
2755 int check, int update)
2757 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2759 cgbr->tab = add_gbr_eq(cgbr->tab, eq);
2761 if (cgbr->cone && cgbr->cone->n_col != cgbr->cone->n_dead) {
2762 if (isl_tab_extend_cons(cgbr->cone, 2) < 0)
2764 if (isl_tab_add_eq(cgbr->cone, eq) < 0)
2769 int v = tab_has_valid_sample(cgbr->tab, eq, 1);
2773 check_gbr_integer_feasible(cgbr);
2776 cgbr->tab = check_samples(cgbr->tab, eq, 1);
2779 isl_tab_free(cgbr->tab);
2783 static void add_gbr_ineq(struct isl_context_gbr *cgbr, isl_int *ineq)
2788 if (isl_tab_extend_cons(cgbr->tab, 1) < 0)
2791 if (isl_tab_add_ineq(cgbr->tab, ineq) < 0)
2794 if (cgbr->shifted && !cgbr->shifted->empty && use_shifted(cgbr)) {
2797 dim = isl_basic_map_total_dim(cgbr->tab->bmap);
2799 if (isl_tab_extend_cons(cgbr->shifted, 1) < 0)
2802 for (i = 0; i < dim; ++i) {
2803 if (!isl_int_is_neg(ineq[1 + i]))
2805 isl_int_add(ineq[0], ineq[0], ineq[1 + i]);
2808 if (isl_tab_add_ineq(cgbr->shifted, ineq) < 0)
2811 for (i = 0; i < dim; ++i) {
2812 if (!isl_int_is_neg(ineq[1 + i]))
2814 isl_int_sub(ineq[0], ineq[0], ineq[1 + i]);
2818 if (cgbr->cone && cgbr->cone->n_col != cgbr->cone->n_dead) {
2819 if (isl_tab_extend_cons(cgbr->cone, 1) < 0)
2821 if (isl_tab_add_ineq(cgbr->cone, ineq) < 0)
2827 isl_tab_free(cgbr->tab);
2831 static void context_gbr_add_ineq(struct isl_context *context, isl_int *ineq,
2832 int check, int update)
2834 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2836 add_gbr_ineq(cgbr, ineq);
2841 int v = tab_has_valid_sample(cgbr->tab, ineq, 0);
2845 check_gbr_integer_feasible(cgbr);
2848 cgbr->tab = check_samples(cgbr->tab, ineq, 0);
2851 isl_tab_free(cgbr->tab);
2855 static int context_gbr_add_ineq_wrap(void *user, isl_int *ineq)
2857 struct isl_context *context = (struct isl_context *)user;
2858 context_gbr_add_ineq(context, ineq, 0, 0);
2859 return context->op->is_ok(context) ? 0 : -1;
2862 static enum isl_tab_row_sign context_gbr_ineq_sign(struct isl_context *context,
2863 isl_int *ineq, int strict)
2865 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2866 return tab_ineq_sign(cgbr->tab, ineq, strict);
2869 /* Check whether "ineq" can be added to the tableau without rendering
2872 static int context_gbr_test_ineq(struct isl_context *context, isl_int *ineq)
2874 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2875 struct isl_tab_undo *snap;
2876 struct isl_tab_undo *shifted_snap = NULL;
2877 struct isl_tab_undo *cone_snap = NULL;
2883 if (isl_tab_extend_cons(cgbr->tab, 1) < 0)
2886 snap = isl_tab_snap(cgbr->tab);
2888 shifted_snap = isl_tab_snap(cgbr->shifted);
2890 cone_snap = isl_tab_snap(cgbr->cone);
2891 add_gbr_ineq(cgbr, ineq);
2892 check_gbr_integer_feasible(cgbr);
2895 feasible = !cgbr->tab->empty;
2896 if (isl_tab_rollback(cgbr->tab, snap) < 0)
2899 if (isl_tab_rollback(cgbr->shifted, shifted_snap))
2901 } else if (cgbr->shifted) {
2902 isl_tab_free(cgbr->shifted);
2903 cgbr->shifted = NULL;
2906 if (isl_tab_rollback(cgbr->cone, cone_snap))
2908 } else if (cgbr->cone) {
2909 isl_tab_free(cgbr->cone);
2916 /* Return the column of the last of the variables associated to
2917 * a column that has a non-zero coefficient.
2918 * This function is called in a context where only coefficients
2919 * of parameters or divs can be non-zero.
2921 static int last_non_zero_var_col(struct isl_tab *tab, isl_int *p)
2925 unsigned dim = tab->n_var - tab->n_param - tab->n_div;
2927 if (tab->n_var == 0)
2930 for (i = tab->n_var - 1; i >= 0; --i) {
2931 if (i >= tab->n_param && i < tab->n_var - tab->n_div)
2933 if (tab->var[i].is_row)
2935 col = tab->var[i].index;
2936 if (!isl_int_is_zero(p[col]))
2943 /* Look through all the recently added equalities in the context
2944 * to see if we can propagate any of them to the main tableau.
2946 * The newly added equalities in the context are encoded as pairs
2947 * of inequalities starting at inequality "first".
2949 * We tentatively add each of these equalities to the main tableau
2950 * and if this happens to result in a row with a final coefficient
2951 * that is one or negative one, we use it to kill a column
2952 * in the main tableau. Otherwise, we discard the tentatively
2955 static void propagate_equalities(struct isl_context_gbr *cgbr,
2956 struct isl_tab *tab, unsigned first)
2959 struct isl_vec *eq = NULL;
2961 eq = isl_vec_alloc(tab->mat->ctx, 1 + tab->n_var);
2965 if (isl_tab_extend_cons(tab, (cgbr->tab->bmap->n_ineq - first)/2) < 0)
2968 isl_seq_clr(eq->el + 1 + tab->n_param,
2969 tab->n_var - tab->n_param - tab->n_div);
2970 for (i = first; i < cgbr->tab->bmap->n_ineq; i += 2) {
2973 struct isl_tab_undo *snap;
2974 snap = isl_tab_snap(tab);
2976 isl_seq_cpy(eq->el, cgbr->tab->bmap->ineq[i], 1 + tab->n_param);
2977 isl_seq_cpy(eq->el + 1 + tab->n_var - tab->n_div,
2978 cgbr->tab->bmap->ineq[i] + 1 + tab->n_param,
2981 r = isl_tab_add_row(tab, eq->el);
2984 r = tab->con[r].index;
2985 j = last_non_zero_var_col(tab, tab->mat->row[r] + 2 + tab->M);
2986 if (j < 0 || j < tab->n_dead ||
2987 !isl_int_is_one(tab->mat->row[r][0]) ||
2988 (!isl_int_is_one(tab->mat->row[r][2 + tab->M + j]) &&
2989 !isl_int_is_negone(tab->mat->row[r][2 + tab->M + j]))) {
2990 if (isl_tab_rollback(tab, snap) < 0)
2994 if (isl_tab_pivot(tab, r, j) < 0)
2996 if (isl_tab_kill_col(tab, j) < 0)
2999 if (restore_lexmin(tab) < 0)
3008 isl_tab_free(cgbr->tab);
3012 static int context_gbr_detect_equalities(struct isl_context *context,
3013 struct isl_tab *tab)
3015 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3016 struct isl_ctx *ctx;
3018 enum isl_lp_result res;
3021 ctx = cgbr->tab->mat->ctx;
3024 struct isl_basic_set *bset = isl_tab_peek_bset(cgbr->tab);
3025 cgbr->cone = isl_tab_from_recession_cone(bset, 0);
3028 if (isl_tab_track_bset(cgbr->cone, isl_basic_set_dup(bset)) < 0)
3031 if (isl_tab_detect_implicit_equalities(cgbr->cone) < 0)
3034 n_ineq = cgbr->tab->bmap->n_ineq;
3035 cgbr->tab = isl_tab_detect_equalities(cgbr->tab, cgbr->cone);
3036 if (cgbr->tab && cgbr->tab->bmap->n_ineq > n_ineq)
3037 propagate_equalities(cgbr, tab, n_ineq);
3041 isl_tab_free(cgbr->tab);
3046 static int context_gbr_get_div(struct isl_context *context, struct isl_tab *tab,
3047 struct isl_vec *div)
3049 return get_div(tab, context, div);
3052 static int context_gbr_add_div(struct isl_context *context, struct isl_vec *div)
3054 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3058 if (isl_tab_extend_cons(cgbr->cone, 3) < 0)
3060 if (isl_tab_extend_vars(cgbr->cone, 1) < 0)
3062 if (isl_tab_allocate_var(cgbr->cone) <0)
3065 cgbr->cone->bmap = isl_basic_map_extend_dim(cgbr->cone->bmap,
3066 isl_basic_map_get_dim(cgbr->cone->bmap), 1, 0, 2);
3067 k = isl_basic_map_alloc_div(cgbr->cone->bmap);
3070 isl_seq_cpy(cgbr->cone->bmap->div[k], div->el, div->size);
3071 if (isl_tab_push(cgbr->cone, isl_tab_undo_bmap_div) < 0)
3074 return context_tab_add_div(cgbr->tab, div,
3075 context_gbr_add_ineq_wrap, context);
3078 static int context_gbr_best_split(struct isl_context *context,
3079 struct isl_tab *tab)
3081 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3082 struct isl_tab_undo *snap;
3085 snap = isl_tab_snap(cgbr->tab);
3086 r = best_split(tab, cgbr->tab);
3088 if (r >= 0 && isl_tab_rollback(cgbr->tab, snap) < 0)
3094 static int context_gbr_is_empty(struct isl_context *context)
3096 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3099 return cgbr->tab->empty;
3102 struct isl_gbr_tab_undo {
3103 struct isl_tab_undo *tab_snap;
3104 struct isl_tab_undo *shifted_snap;
3105 struct isl_tab_undo *cone_snap;
3108 static void *context_gbr_save(struct isl_context *context)
3110 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3111 struct isl_gbr_tab_undo *snap;
3113 snap = isl_alloc_type(cgbr->tab->mat->ctx, struct isl_gbr_tab_undo);
3117 snap->tab_snap = isl_tab_snap(cgbr->tab);
3118 if (isl_tab_save_samples(cgbr->tab) < 0)
3122 snap->shifted_snap = isl_tab_snap(cgbr->shifted);
3124 snap->shifted_snap = NULL;
3127 snap->cone_snap = isl_tab_snap(cgbr->cone);
3129 snap->cone_snap = NULL;
3137 static void context_gbr_restore(struct isl_context *context, void *save)
3139 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3140 struct isl_gbr_tab_undo *snap = (struct isl_gbr_tab_undo *)save;
3143 if (isl_tab_rollback(cgbr->tab, snap->tab_snap) < 0) {
3144 isl_tab_free(cgbr->tab);
3148 if (snap->shifted_snap) {
3149 if (isl_tab_rollback(cgbr->shifted, snap->shifted_snap) < 0)
3151 } else if (cgbr->shifted) {
3152 isl_tab_free(cgbr->shifted);
3153 cgbr->shifted = NULL;
3156 if (snap->cone_snap) {
3157 if (isl_tab_rollback(cgbr->cone, snap->cone_snap) < 0)
3159 } else if (cgbr->cone) {
3160 isl_tab_free(cgbr->cone);
3169 isl_tab_free(cgbr->tab);
3173 static int context_gbr_is_ok(struct isl_context *context)
3175 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3179 static void context_gbr_invalidate(struct isl_context *context)
3181 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3182 isl_tab_free(cgbr->tab);
3186 static void context_gbr_free(struct isl_context *context)
3188 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3189 isl_tab_free(cgbr->tab);
3190 isl_tab_free(cgbr->shifted);
3191 isl_tab_free(cgbr->cone);
3195 struct isl_context_op isl_context_gbr_op = {
3196 context_gbr_detect_nonnegative_parameters,
3197 context_gbr_peek_basic_set,
3198 context_gbr_peek_tab,
3200 context_gbr_add_ineq,
3201 context_gbr_ineq_sign,
3202 context_gbr_test_ineq,
3203 context_gbr_get_div,
3204 context_gbr_add_div,
3205 context_gbr_detect_equalities,
3206 context_gbr_best_split,
3207 context_gbr_is_empty,
3210 context_gbr_restore,
3211 context_gbr_invalidate,
3215 static struct isl_context *isl_context_gbr_alloc(struct isl_basic_set *dom)
3217 struct isl_context_gbr *cgbr;
3222 cgbr = isl_calloc_type(dom->ctx, struct isl_context_gbr);
3226 cgbr->context.op = &isl_context_gbr_op;
3228 cgbr->shifted = NULL;
3230 cgbr->tab = isl_tab_from_basic_set(dom);
3231 cgbr->tab = isl_tab_init_samples(cgbr->tab);
3234 if (isl_tab_track_bset(cgbr->tab,
3235 isl_basic_set_cow(isl_basic_set_copy(dom))) < 0)
3237 check_gbr_integer_feasible(cgbr);
3239 return &cgbr->context;
3241 cgbr->context.op->free(&cgbr->context);
3245 static struct isl_context *isl_context_alloc(struct isl_basic_set *dom)
3250 if (dom->ctx->opt->context == ISL_CONTEXT_LEXMIN)
3251 return isl_context_lex_alloc(dom);
3253 return isl_context_gbr_alloc(dom);
3256 /* Construct an isl_sol_map structure for accumulating the solution.
3257 * If track_empty is set, then we also keep track of the parts
3258 * of the context where there is no solution.
3259 * If max is set, then we are solving a maximization, rather than
3260 * a minimization problem, which means that the variables in the
3261 * tableau have value "M - x" rather than "M + x".
3263 static struct isl_sol_map *sol_map_init(struct isl_basic_map *bmap,
3264 struct isl_basic_set *dom, int track_empty, int max)
3266 struct isl_sol_map *sol_map = NULL;
3271 sol_map = isl_calloc_type(bmap->ctx, struct isl_sol_map);
3275 sol_map->sol.rational = ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL);
3276 sol_map->sol.dec_level.callback.run = &sol_dec_level_wrap;
3277 sol_map->sol.dec_level.sol = &sol_map->sol;
3278 sol_map->sol.max = max;
3279 sol_map->sol.n_out = isl_basic_map_dim(bmap, isl_dim_out);
3280 sol_map->sol.add = &sol_map_add_wrap;
3281 sol_map->sol.add_empty = track_empty ? &sol_map_add_empty_wrap : NULL;
3282 sol_map->sol.free = &sol_map_free_wrap;
3283 sol_map->map = isl_map_alloc_dim(isl_basic_map_get_dim(bmap), 1,
3288 sol_map->sol.context = isl_context_alloc(dom);
3289 if (!sol_map->sol.context)
3293 sol_map->empty = isl_set_alloc_dim(isl_basic_set_get_dim(dom),
3294 1, ISL_SET_DISJOINT);
3295 if (!sol_map->empty)
3299 isl_basic_set_free(dom);
3302 isl_basic_set_free(dom);
3303 sol_map_free(sol_map);
3307 /* Check whether all coefficients of (non-parameter) variables
3308 * are non-positive, meaning that no pivots can be performed on the row.
3310 static int is_critical(struct isl_tab *tab, int row)
3313 unsigned off = 2 + tab->M;
3315 for (j = tab->n_dead; j < tab->n_col; ++j) {
3316 if (tab->col_var[j] >= 0 &&
3317 (tab->col_var[j] < tab->n_param ||
3318 tab->col_var[j] >= tab->n_var - tab->n_div))
3321 if (isl_int_is_pos(tab->mat->row[row][off + j]))
3328 /* Check whether the inequality represented by vec is strict over the integers,
3329 * i.e., there are no integer values satisfying the constraint with
3330 * equality. This happens if the gcd of the coefficients is not a divisor
3331 * of the constant term. If so, scale the constraint down by the gcd
3332 * of the coefficients.
3334 static int is_strict(struct isl_vec *vec)
3340 isl_seq_gcd(vec->el + 1, vec->size - 1, &gcd);
3341 if (!isl_int_is_one(gcd)) {
3342 strict = !isl_int_is_divisible_by(vec->el[0], gcd);
3343 isl_int_fdiv_q(vec->el[0], vec->el[0], gcd);
3344 isl_seq_scale_down(vec->el + 1, vec->el + 1, gcd, vec->size-1);
3351 /* Determine the sign of the given row of the main tableau.
3352 * The result is one of
3353 * isl_tab_row_pos: always non-negative; no pivot needed
3354 * isl_tab_row_neg: always non-positive; pivot
3355 * isl_tab_row_any: can be both positive and negative; split
3357 * We first handle some simple cases
3358 * - the row sign may be known already
3359 * - the row may be obviously non-negative
3360 * - the parametric constant may be equal to that of another row
3361 * for which we know the sign. This sign will be either "pos" or
3362 * "any". If it had been "neg" then we would have pivoted before.
3364 * If none of these cases hold, we check the value of the row for each
3365 * of the currently active samples. Based on the signs of these values
3366 * we make an initial determination of the sign of the row.
3368 * all zero -> unk(nown)
3369 * all non-negative -> pos
3370 * all non-positive -> neg
3371 * both negative and positive -> all
3373 * If we end up with "all", we are done.
3374 * Otherwise, we perform a check for positive and/or negative
3375 * values as follows.
3377 * samples neg unk pos
3383 * There is no special sign for "zero", because we can usually treat zero
3384 * as either non-negative or non-positive, whatever works out best.
3385 * However, if the row is "critical", meaning that pivoting is impossible
3386 * then we don't want to limp zero with the non-positive case, because
3387 * then we we would lose the solution for those values of the parameters
3388 * where the value of the row is zero. Instead, we treat 0 as non-negative
3389 * ensuring a split if the row can attain both zero and negative values.
3390 * The same happens when the original constraint was one that could not
3391 * be satisfied with equality by any integer values of the parameters.
3392 * In this case, we normalize the constraint, but then a value of zero
3393 * for the normalized constraint is actually a positive value for the
3394 * original constraint, so again we need to treat zero as non-negative.
3395 * In both these cases, we have the following decision tree instead:
3397 * all non-negative -> pos
3398 * all negative -> neg
3399 * both negative and non-negative -> all
3407 static enum isl_tab_row_sign row_sign(struct isl_tab *tab,
3408 struct isl_sol *sol, int row)
3410 struct isl_vec *ineq = NULL;
3411 enum isl_tab_row_sign res = isl_tab_row_unknown;
3416 if (tab->row_sign[row] != isl_tab_row_unknown)
3417 return tab->row_sign[row];
3418 if (is_obviously_nonneg(tab, row))
3419 return isl_tab_row_pos;
3420 for (row2 = tab->n_redundant; row2 < tab->n_row; ++row2) {
3421 if (tab->row_sign[row2] == isl_tab_row_unknown)
3423 if (identical_parameter_line(tab, row, row2))
3424 return tab->row_sign[row2];
3427 critical = is_critical(tab, row);
3429 ineq = get_row_parameter_ineq(tab, row);
3433 strict = is_strict(ineq);
3435 res = sol->context->op->ineq_sign(sol->context, ineq->el,
3436 critical || strict);
3438 if (res == isl_tab_row_unknown || res == isl_tab_row_pos) {
3439 /* test for negative values */
3441 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3442 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3444 feasible = sol->context->op->test_ineq(sol->context, ineq->el);
3448 res = isl_tab_row_pos;
3450 res = (res == isl_tab_row_unknown) ? isl_tab_row_neg
3452 if (res == isl_tab_row_neg) {
3453 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3454 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3458 if (res == isl_tab_row_neg) {
3459 /* test for positive values */
3461 if (!critical && !strict)
3462 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3464 feasible = sol->context->op->test_ineq(sol->context, ineq->el);
3468 res = isl_tab_row_any;
3475 return isl_tab_row_unknown;
3478 static void find_solutions(struct isl_sol *sol, struct isl_tab *tab);
3480 /* Find solutions for values of the parameters that satisfy the given
3483 * We currently take a snapshot of the context tableau that is reset
3484 * when we return from this function, while we make a copy of the main
3485 * tableau, leaving the original main tableau untouched.
3486 * These are fairly arbitrary choices. Making a copy also of the context
3487 * tableau would obviate the need to undo any changes made to it later,
3488 * while taking a snapshot of the main tableau could reduce memory usage.
3489 * If we were to switch to taking a snapshot of the main tableau,
3490 * we would have to keep in mind that we need to save the row signs
3491 * and that we need to do this before saving the current basis
3492 * such that the basis has been restore before we restore the row signs.
3494 static void find_in_pos(struct isl_sol *sol, struct isl_tab *tab, isl_int *ineq)
3500 saved = sol->context->op->save(sol->context);
3502 tab = isl_tab_dup(tab);
3506 sol->context->op->add_ineq(sol->context, ineq, 0, 1);
3508 find_solutions(sol, tab);
3511 sol->context->op->restore(sol->context, saved);
3517 /* Record the absence of solutions for those values of the parameters
3518 * that do not satisfy the given inequality with equality.
3520 static void no_sol_in_strict(struct isl_sol *sol,
3521 struct isl_tab *tab, struct isl_vec *ineq)
3526 if (!sol->context || sol->error)
3528 saved = sol->context->op->save(sol->context);
3530 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3532 sol->context->op->add_ineq(sol->context, ineq->el, 1, 0);
3541 isl_int_add_ui(ineq->el[0], ineq->el[0], 1);
3543 sol->context->op->restore(sol->context, saved);
3549 /* Compute the lexicographic minimum of the set represented by the main
3550 * tableau "tab" within the context "sol->context_tab".
3551 * On entry the sample value of the main tableau is lexicographically
3552 * less than or equal to this lexicographic minimum.
3553 * Pivots are performed until a feasible point is found, which is then
3554 * necessarily equal to the minimum, or until the tableau is found to
3555 * be infeasible. Some pivots may need to be performed for only some
3556 * feasible values of the context tableau. If so, the context tableau
3557 * is split into a part where the pivot is needed and a part where it is not.
3559 * Whenever we enter the main loop, the main tableau is such that no
3560 * "obvious" pivots need to be performed on it, where "obvious" means
3561 * that the given row can be seen to be negative without looking at
3562 * the context tableau. In particular, for non-parametric problems,
3563 * no pivots need to be performed on the main tableau.
3564 * The caller of find_solutions is responsible for making this property
3565 * hold prior to the first iteration of the loop, while restore_lexmin
3566 * is called before every other iteration.
3568 * Inside the main loop, we first examine the signs of the rows of
3569 * the main tableau within the context of the context tableau.
3570 * If we find a row that is always non-positive for all values of
3571 * the parameters satisfying the context tableau and negative for at
3572 * least one value of the parameters, we perform the appropriate pivot
3573 * and start over. An exception is the case where no pivot can be
3574 * performed on the row. In this case, we require that the sign of
3575 * the row is negative for all values of the parameters (rather than just
3576 * non-positive). This special case is handled inside row_sign, which
3577 * will say that the row can have any sign if it determines that it can
3578 * attain both negative and zero values.
3580 * If we can't find a row that always requires a pivot, but we can find
3581 * one or more rows that require a pivot for some values of the parameters
3582 * (i.e., the row can attain both positive and negative signs), then we split
3583 * the context tableau into two parts, one where we force the sign to be
3584 * non-negative and one where we force is to be negative.
3585 * The non-negative part is handled by a recursive call (through find_in_pos).
3586 * Upon returning from this call, we continue with the negative part and
3587 * perform the required pivot.
3589 * If no such rows can be found, all rows are non-negative and we have
3590 * found a (rational) feasible point. If we only wanted a rational point
3592 * Otherwise, we check if all values of the sample point of the tableau
3593 * are integral for the variables. If so, we have found the minimal
3594 * integral point and we are done.
3595 * If the sample point is not integral, then we need to make a distinction
3596 * based on whether the constant term is non-integral or the coefficients
3597 * of the parameters. Furthermore, in order to decide how to handle
3598 * the non-integrality, we also need to know whether the coefficients
3599 * of the other columns in the tableau are integral. This leads
3600 * to the following table. The first two rows do not correspond
3601 * to a non-integral sample point and are only mentioned for completeness.
3603 * constant parameters other
3606 * int int rat | -> no problem
3608 * rat int int -> fail
3610 * rat int rat -> cut
3613 * rat rat rat | -> parametric cut
3616 * rat rat int | -> split context
3618 * If the parametric constant is completely integral, then there is nothing
3619 * to be done. If the constant term is non-integral, but all the other
3620 * coefficient are integral, then there is nothing that can be done
3621 * and the tableau has no integral solution.
3622 * If, on the other hand, one or more of the other columns have rational
3623 * coefficients, but the parameter coefficients are all integral, then
3624 * we can perform a regular (non-parametric) cut.
3625 * Finally, if there is any parameter coefficient that is non-integral,
3626 * then we need to involve the context tableau. There are two cases here.
3627 * If at least one other column has a rational coefficient, then we
3628 * can perform a parametric cut in the main tableau by adding a new
3629 * integer division in the context tableau.
3630 * If all other columns have integral coefficients, then we need to
3631 * enforce that the rational combination of parameters (c + \sum a_i y_i)/m
3632 * is always integral. We do this by introducing an integer division
3633 * q = floor((c + \sum a_i y_i)/m) and stipulating that its argument should
3634 * always be integral in the context tableau, i.e., m q = c + \sum a_i y_i.
3635 * Since q is expressed in the tableau as
3636 * c + \sum a_i y_i - m q >= 0
3637 * -c - \sum a_i y_i + m q + m - 1 >= 0
3638 * it is sufficient to add the inequality
3639 * -c - \sum a_i y_i + m q >= 0
3640 * In the part of the context where this inequality does not hold, the
3641 * main tableau is marked as being empty.
3643 static void find_solutions(struct isl_sol *sol, struct isl_tab *tab)
3645 struct isl_context *context;
3648 if (!tab || sol->error)
3651 context = sol->context;
3655 if (context->op->is_empty(context))
3658 for (r = 0; r >= 0 && tab && !tab->empty; r = restore_lexmin(tab)) {
3661 enum isl_tab_row_sign sgn;
3665 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3666 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
3668 sgn = row_sign(tab, sol, row);
3671 tab->row_sign[row] = sgn;
3672 if (sgn == isl_tab_row_any)
3674 if (sgn == isl_tab_row_any && split == -1)
3676 if (sgn == isl_tab_row_neg)
3679 if (row < tab->n_row)
3682 struct isl_vec *ineq;
3684 split = context->op->best_split(context, tab);
3687 ineq = get_row_parameter_ineq(tab, split);
3691 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3692 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
3694 if (tab->row_sign[row] == isl_tab_row_any)
3695 tab->row_sign[row] = isl_tab_row_unknown;
3697 tab->row_sign[split] = isl_tab_row_pos;
3699 find_in_pos(sol, tab, ineq->el);
3700 tab->row_sign[split] = isl_tab_row_neg;
3702 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3703 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3705 context->op->add_ineq(context, ineq->el, 0, 1);
3713 row = first_non_integer_row(tab, &flags);
3716 if (ISL_FL_ISSET(flags, I_PAR)) {
3717 if (ISL_FL_ISSET(flags, I_VAR)) {
3718 if (isl_tab_mark_empty(tab) < 0)
3722 row = add_cut(tab, row);
3723 } else if (ISL_FL_ISSET(flags, I_VAR)) {
3724 struct isl_vec *div;
3725 struct isl_vec *ineq;
3727 div = get_row_split_div(tab, row);
3730 d = context->op->get_div(context, tab, div);
3734 ineq = ineq_for_div(context->op->peek_basic_set(context), d);
3738 no_sol_in_strict(sol, tab, ineq);
3739 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3740 context->op->add_ineq(context, ineq->el, 1, 1);
3742 if (sol->error || !context->op->is_ok(context))
3744 tab = set_row_cst_to_div(tab, row, d);
3745 if (context->op->is_empty(context))
3748 row = add_parametric_cut(tab, row, context);
3763 /* Compute the lexicographic minimum of the set represented by the main
3764 * tableau "tab" within the context "sol->context_tab".
3766 * As a preprocessing step, we first transfer all the purely parametric
3767 * equalities from the main tableau to the context tableau, i.e.,
3768 * parameters that have been pivoted to a row.
3769 * These equalities are ignored by the main algorithm, because the
3770 * corresponding rows may not be marked as being non-negative.
3771 * In parts of the context where the added equality does not hold,
3772 * the main tableau is marked as being empty.
3774 static void find_solutions_main(struct isl_sol *sol, struct isl_tab *tab)
3783 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3787 if (tab->row_var[row] < 0)
3789 if (tab->row_var[row] >= tab->n_param &&
3790 tab->row_var[row] < tab->n_var - tab->n_div)
3792 if (tab->row_var[row] < tab->n_param)
3793 p = tab->row_var[row];
3795 p = tab->row_var[row]
3796 + tab->n_param - (tab->n_var - tab->n_div);
3798 eq = isl_vec_alloc(tab->mat->ctx, 1+tab->n_param+tab->n_div);
3801 get_row_parameter_line(tab, row, eq->el);
3802 isl_int_neg(eq->el[1 + p], tab->mat->row[row][0]);
3803 eq = isl_vec_normalize(eq);
3806 no_sol_in_strict(sol, tab, eq);
3808 isl_seq_neg(eq->el, eq->el, eq->size);
3810 no_sol_in_strict(sol, tab, eq);
3811 isl_seq_neg(eq->el, eq->el, eq->size);
3813 sol->context->op->add_eq(sol->context, eq->el, 1, 1);
3817 if (isl_tab_mark_redundant(tab, row) < 0)
3820 if (sol->context->op->is_empty(sol->context))
3823 row = tab->n_redundant - 1;
3826 find_solutions(sol, tab);
3837 static void sol_map_find_solutions(struct isl_sol_map *sol_map,
3838 struct isl_tab *tab)
3840 find_solutions_main(&sol_map->sol, tab);
3843 /* Check if integer division "div" of "dom" also occurs in "bmap".
3844 * If so, return its position within the divs.
3845 * If not, return -1.
3847 static int find_context_div(struct isl_basic_map *bmap,
3848 struct isl_basic_set *dom, unsigned div)
3851 unsigned b_dim = isl_dim_total(bmap->dim);
3852 unsigned d_dim = isl_dim_total(dom->dim);
3854 if (isl_int_is_zero(dom->div[div][0]))
3856 if (isl_seq_first_non_zero(dom->div[div] + 2 + d_dim, dom->n_div) != -1)
3859 for (i = 0; i < bmap->n_div; ++i) {
3860 if (isl_int_is_zero(bmap->div[i][0]))
3862 if (isl_seq_first_non_zero(bmap->div[i] + 2 + d_dim,
3863 (b_dim - d_dim) + bmap->n_div) != -1)
3865 if (isl_seq_eq(bmap->div[i], dom->div[div], 2 + d_dim))
3871 /* The correspondence between the variables in the main tableau,
3872 * the context tableau, and the input map and domain is as follows.
3873 * The first n_param and the last n_div variables of the main tableau
3874 * form the variables of the context tableau.
3875 * In the basic map, these n_param variables correspond to the
3876 * parameters and the input dimensions. In the domain, they correspond
3877 * to the parameters and the set dimensions.
3878 * The n_div variables correspond to the integer divisions in the domain.
3879 * To ensure that everything lines up, we may need to copy some of the
3880 * integer divisions of the domain to the map. These have to be placed
3881 * in the same order as those in the context and they have to be placed
3882 * after any other integer divisions that the map may have.
3883 * This function performs the required reordering.
3885 static struct isl_basic_map *align_context_divs(struct isl_basic_map *bmap,
3886 struct isl_basic_set *dom)
3892 for (i = 0; i < dom->n_div; ++i)
3893 if (find_context_div(bmap, dom, i) != -1)
3895 other = bmap->n_div - common;
3896 if (dom->n_div - common > 0) {
3897 bmap = isl_basic_map_extend_dim(bmap, isl_dim_copy(bmap->dim),
3898 dom->n_div - common, 0, 0);
3902 for (i = 0; i < dom->n_div; ++i) {
3903 int pos = find_context_div(bmap, dom, i);
3905 pos = isl_basic_map_alloc_div(bmap);
3908 isl_int_set_si(bmap->div[pos][0], 0);
3910 if (pos != other + i)
3911 isl_basic_map_swap_div(bmap, pos, other + i);
3915 isl_basic_map_free(bmap);
3919 /* Base case of isl_tab_basic_map_partial_lexopt, after removing
3920 * some obvious symmetries.
3922 * We make sure the divs in the domain are properly ordered,
3923 * because they will be added one by one in the given order
3924 * during the construction of the solution map.
3926 static __isl_give isl_map *basic_map_partial_lexopt_base(
3927 __isl_take isl_basic_map *bmap, __isl_take isl_basic_set *dom,
3928 __isl_give isl_set **empty, int max)
3930 isl_map *result = NULL;
3931 struct isl_tab *tab;
3932 struct isl_sol_map *sol_map = NULL;
3933 struct isl_context *context;
3936 dom = isl_basic_set_order_divs(dom);
3937 bmap = align_context_divs(bmap, dom);
3939 sol_map = sol_map_init(bmap, dom, !!empty, max);
3943 context = sol_map->sol.context;
3944 if (isl_basic_set_fast_is_empty(context->op->peek_basic_set(context)))
3946 else if (isl_basic_map_fast_is_empty(bmap))
3947 sol_map_add_empty_if_needed(sol_map,
3948 isl_basic_set_copy(context->op->peek_basic_set(context)));
3950 tab = tab_for_lexmin(bmap,
3951 context->op->peek_basic_set(context), 1, max);
3952 tab = context->op->detect_nonnegative_parameters(context, tab);
3953 sol_map_find_solutions(sol_map, tab);
3955 if (sol_map->sol.error)
3958 result = isl_map_copy(sol_map->map);
3960 *empty = isl_set_copy(sol_map->empty);
3961 sol_free(&sol_map->sol);
3962 isl_basic_map_free(bmap);
3965 sol_free(&sol_map->sol);
3966 isl_basic_map_free(bmap);
3970 /* Structure used during detection of parallel constraints.
3971 * n_in: number of "input" variables: isl_dim_param + isl_dim_in
3972 * n_out: number of "output" variables: isl_dim_out + isl_dim_div
3973 * val: the coefficients of the output variables
3975 struct isl_constraint_equal_info {
3976 isl_basic_map *bmap;
3982 /* Check whether the coefficients of the output variables
3983 * of the constraint in "entry" are equal to info->val.
3985 static int constraint_equal(const void *entry, const void *val)
3987 isl_int **row = (isl_int **)entry;
3988 const struct isl_constraint_equal_info *info = val;
3990 return isl_seq_eq((*row) + 1 + info->n_in, info->val, info->n_out);
3993 /* Check whether "bmap" has a pair of constraints that have
3994 * the same coefficients for the output variables.
3995 * Note that the coefficients of the existentially quantified
3996 * variables need to be zero since the existentially quantified
3997 * of the result are usually not the same as those of the input.
3998 * the isl_dim_out and isl_dim_div dimensions.
3999 * If so, return 1 and return the row indices of the two constraints
4000 * in *first and *second.
4002 static int parallel_constraints(__isl_keep isl_basic_map *bmap,
4003 int *first, int *second)
4006 isl_ctx *ctx = isl_basic_map_get_ctx(bmap);
4007 struct isl_hash_table *table = NULL;
4008 struct isl_hash_table_entry *entry;
4009 struct isl_constraint_equal_info info;
4013 ctx = isl_basic_map_get_ctx(bmap);
4014 table = isl_hash_table_alloc(ctx, bmap->n_ineq);
4018 info.n_in = isl_basic_map_dim(bmap, isl_dim_param) +
4019 isl_basic_map_dim(bmap, isl_dim_in);
4021 n_out = isl_basic_map_dim(bmap, isl_dim_out);
4022 n_div = isl_basic_map_dim(bmap, isl_dim_div);
4023 info.n_out = n_out + n_div;
4024 for (i = 0; i < bmap->n_ineq; ++i) {
4027 info.val = bmap->ineq[i] + 1 + info.n_in;
4028 if (isl_seq_first_non_zero(info.val, n_out) < 0)
4030 if (isl_seq_first_non_zero(info.val + n_out, n_div) >= 0)
4032 hash = isl_seq_get_hash(info.val, info.n_out);
4033 entry = isl_hash_table_find(ctx, table, hash,
4034 constraint_equal, &info, 1);
4039 entry->data = &bmap->ineq[i];
4042 if (i < bmap->n_ineq) {
4043 *first = ((isl_int **)entry->data) - bmap->ineq;
4047 isl_hash_table_free(ctx, table);
4049 return i < bmap->n_ineq;
4051 isl_hash_table_free(ctx, table);
4055 /* Given a set of upper bounds on the last "input" variable m,
4056 * construct a set that assigns the minimal upper bound to m, i.e.,
4057 * construct a set that divides the space into cells where one
4058 * of the upper bounds is smaller than all the others and assign
4059 * this upper bound to m.
4061 * In particular, if there are n bounds b_i, then the result
4062 * consists of n basic sets, each one of the form
4065 * b_i <= b_j for j > i
4066 * b_i < b_j for j < i
4068 static __isl_give isl_set *set_minimum(__isl_take isl_dim *dim,
4069 __isl_take isl_mat *var)
4072 isl_basic_set *bset = NULL;
4074 isl_set *set = NULL;
4079 ctx = isl_dim_get_ctx(dim);
4080 set = isl_set_alloc_dim(isl_dim_copy(dim),
4081 var->n_row, ISL_SET_DISJOINT);
4083 for (i = 0; i < var->n_row; ++i) {
4084 bset = isl_basic_set_alloc_dim(isl_dim_copy(dim), 0,
4086 k = isl_basic_set_alloc_equality(bset);
4089 isl_seq_cpy(bset->eq[k], var->row[i], var->n_col);
4090 isl_int_set_si(bset->eq[k][var->n_col], -1);
4091 for (j = 0; j < var->n_row; ++j) {
4094 k = isl_basic_set_alloc_inequality(bset);
4097 isl_seq_combine(bset->ineq[k], ctx->one, var->row[j],
4098 ctx->negone, var->row[i],
4100 isl_int_set_si(bset->ineq[k][var->n_col], 0);
4102 isl_int_sub_ui(bset->ineq[k][0],
4103 bset->ineq[k][0], 1);
4105 bset = isl_basic_set_finalize(bset);
4106 set = isl_set_add_basic_set(set, bset);
4113 isl_basic_set_free(bset);
4120 /* Given that the last input variable of "bmap" represents the minimum
4121 * of the bounds in "cst", check whether we need to split the domain
4122 * based on which bound attains the minimum.
4124 * A split is needed when the minimum appears in an integer division
4125 * or in an equality. Otherwise, it is only needed if it appears in
4126 * an upper bound that is different from the upper bounds on which it
4129 static int need_split_map(__isl_keep isl_basic_map *bmap,
4130 __isl_keep isl_mat *cst)
4136 pos = cst->n_col - 1;
4137 total = isl_basic_map_dim(bmap, isl_dim_all);
4139 for (i = 0; i < bmap->n_div; ++i)
4140 if (!isl_int_is_zero(bmap->div[i][2 + pos]))
4143 for (i = 0; i < bmap->n_eq; ++i)
4144 if (!isl_int_is_zero(bmap->eq[i][1 + pos]))
4147 for (i = 0; i < bmap->n_ineq; ++i) {
4148 if (isl_int_is_nonneg(bmap->ineq[i][1 + pos]))
4150 if (!isl_int_is_negone(bmap->ineq[i][1 + pos]))
4152 if (isl_seq_first_non_zero(bmap->ineq[i] + 1 + pos + 1,
4153 total - pos - 1) >= 0)
4156 for (j = 0; j < cst->n_row; ++j)
4157 if (isl_seq_eq(bmap->ineq[i], cst->row[j], cst->n_col))
4159 if (j >= cst->n_row)
4166 static int need_split_set(__isl_keep isl_basic_set *bset,
4167 __isl_keep isl_mat *cst)
4169 return need_split_map((isl_basic_map *)bset, cst);
4172 /* Given a set of which the last set variable is the minimum
4173 * of the bounds in "cst", split each basic set in the set
4174 * in pieces where one of the bounds is (strictly) smaller than the others.
4175 * This subdivision is given in "min_expr".
4176 * The variable is subsequently projected out.
4178 * We only do the split when it is needed.
4179 * For example if the last input variable m = min(a,b) and the only
4180 * constraints in the given basic set are lower bounds on m,
4181 * i.e., l <= m = min(a,b), then we can simply project out m
4182 * to obtain l <= a and l <= b, without having to split on whether
4183 * m is equal to a or b.
4185 static __isl_give isl_set *split(__isl_take isl_set *empty,
4186 __isl_take isl_set *min_expr, __isl_take isl_mat *cst)
4193 if (!empty || !min_expr || !cst)
4196 n_in = isl_set_dim(empty, isl_dim_set);
4197 dim = isl_set_get_dim(empty);
4198 dim = isl_dim_drop(dim, isl_dim_set, n_in - 1, 1);
4199 res = isl_set_empty(dim);
4201 for (i = 0; i < empty->n; ++i) {
4204 set = isl_set_from_basic_set(isl_basic_set_copy(empty->p[i]));
4205 if (need_split_set(empty->p[i], cst))
4206 set = isl_set_intersect(set, isl_set_copy(min_expr));
4207 set = isl_set_remove_dims(set, isl_dim_set, n_in - 1, 1);
4209 res = isl_set_union_disjoint(res, set);
4212 isl_set_free(empty);
4213 isl_set_free(min_expr);
4217 isl_set_free(empty);
4218 isl_set_free(min_expr);
4223 /* Given a map of which the last input variable is the minimum
4224 * of the bounds in "cst", split each basic set in the set
4225 * in pieces where one of the bounds is (strictly) smaller than the others.
4226 * This subdivision is given in "min_expr".
4227 * The variable is subsequently projected out.
4229 * The implementation is essentially the same as that of "split".
4231 static __isl_give isl_map *split_domain(__isl_take isl_map *opt,
4232 __isl_take isl_set *min_expr, __isl_take isl_mat *cst)
4239 if (!opt || !min_expr || !cst)
4242 n_in = isl_map_dim(opt, isl_dim_in);
4243 dim = isl_map_get_dim(opt);
4244 dim = isl_dim_drop(dim, isl_dim_in, n_in - 1, 1);
4245 res = isl_map_empty(dim);
4247 for (i = 0; i < opt->n; ++i) {
4250 map = isl_map_from_basic_map(isl_basic_map_copy(opt->p[i]));
4251 if (need_split_map(opt->p[i], cst))
4252 map = isl_map_intersect_domain(map,
4253 isl_set_copy(min_expr));
4254 map = isl_map_remove_dims(map, isl_dim_in, n_in - 1, 1);
4256 res = isl_map_union_disjoint(res, map);
4260 isl_set_free(min_expr);
4265 isl_set_free(min_expr);
4270 static __isl_give isl_map *basic_map_partial_lexopt(
4271 __isl_take isl_basic_map *bmap, __isl_take isl_basic_set *dom,
4272 __isl_give isl_set **empty, int max);
4274 /* Given a basic map with at least two parallel constraints (as found
4275 * by the function parallel_constraints), first look for more constraints
4276 * parallel to the two constraint and replace the found list of parallel
4277 * constraints by a single constraint with as "input" part the minimum
4278 * of the input parts of the list of constraints. Then, recursively call
4279 * basic_map_partial_lexopt (possibly finding more parallel constraints)
4280 * and plug in the definition of the minimum in the result.
4282 * More specifically, given a set of constraints
4286 * Replace this set by a single constraint
4290 * with u a new parameter with constraints
4294 * Any solution to the new system is also a solution for the original system
4297 * a x >= -u >= -b_i(p)
4299 * Moreover, m = min_i(b_i(p)) satisfies the constraints on u and can
4300 * therefore be plugged into the solution.
4302 static __isl_give isl_map *basic_map_partial_lexopt_symm(
4303 __isl_take isl_basic_map *bmap, __isl_take isl_basic_set *dom,
4304 __isl_give isl_set **empty, int max, int first, int second)
4308 unsigned n_in, n_out, n_div;
4310 isl_vec *var = NULL;
4311 isl_mat *cst = NULL;
4314 isl_dim *map_dim, *set_dim;
4316 map_dim = isl_basic_map_get_dim(bmap);
4317 set_dim = empty ? isl_basic_set_get_dim(dom) : NULL;
4319 n_in = isl_basic_map_dim(bmap, isl_dim_param) +
4320 isl_basic_map_dim(bmap, isl_dim_in);
4321 n_out = isl_basic_map_dim(bmap, isl_dim_all) - n_in;
4323 ctx = isl_basic_map_get_ctx(bmap);
4324 list = isl_alloc_array(ctx, int, bmap->n_ineq);
4325 var = isl_vec_alloc(ctx, n_out);
4331 isl_seq_cpy(var->el, bmap->ineq[first] + 1 + n_in, n_out);
4332 for (i = second + 1, n = 2; i < bmap->n_ineq; ++i) {
4333 if (isl_seq_eq(var->el, bmap->ineq[i] + 1 + n_in, n_out))
4337 cst = isl_mat_alloc(ctx, n, 1 + n_in);
4341 for (i = 0; i < n; ++i)
4342 isl_seq_cpy(cst->row[i], bmap->ineq[list[i]], 1 + n_in);
4344 bmap = isl_basic_map_cow(bmap);
4347 for (i = n - 1; i >= 0; --i)
4348 if (isl_basic_map_drop_inequality(bmap, list[i]) < 0)
4351 bmap = isl_basic_map_add(bmap, isl_dim_in, 1);
4352 bmap = isl_basic_map_extend_constraints(bmap, 0, 1);
4353 k = isl_basic_map_alloc_inequality(bmap);
4356 isl_seq_clr(bmap->ineq[k], 1 + n_in);
4357 isl_int_set_si(bmap->ineq[k][1 + n_in], 1);
4358 isl_seq_cpy(bmap->ineq[k] + 1 + n_in + 1, var->el, n_out);
4359 bmap = isl_basic_map_finalize(bmap);
4361 n_div = isl_basic_set_dim(dom, isl_dim_div);
4362 dom = isl_basic_set_add(dom, isl_dim_set, 1);
4363 dom = isl_basic_set_extend_constraints(dom, 0, n);
4364 for (i = 0; i < n; ++i) {
4365 k = isl_basic_set_alloc_inequality(dom);
4368 isl_seq_cpy(dom->ineq[k], cst->row[i], 1 + n_in);
4369 isl_int_set_si(dom->ineq[k][1 + n_in], -1);
4370 isl_seq_clr(dom->ineq[k] + 1 + n_in + 1, n_div);
4373 min_expr = set_minimum(isl_basic_set_get_dim(dom), isl_mat_copy(cst));
4378 opt = basic_map_partial_lexopt(bmap, dom, empty, max);
4381 *empty = split(*empty,
4382 isl_set_copy(min_expr), isl_mat_copy(cst));
4383 *empty = isl_set_reset_dim(*empty, set_dim);
4386 opt = split_domain(opt, min_expr, cst);
4387 opt = isl_map_reset_dim(opt, map_dim);
4391 isl_dim_free(map_dim);
4392 isl_dim_free(set_dim);
4396 isl_basic_set_free(dom);
4397 isl_basic_map_free(bmap);
4401 /* Recursive part of isl_tab_basic_map_partial_lexopt, after detecting
4402 * equalities and removing redundant constraints.
4404 * We first check if there are any parallel constraints (left).
4405 * If not, we are in the base case.
4406 * If there are parallel constraints, we replace them by a single
4407 * constraint in basic_map_partial_lexopt_symm and then call
4408 * this function recursively to look for more parallel constraints.
4410 static __isl_give isl_map *basic_map_partial_lexopt(
4411 __isl_take isl_basic_map *bmap, __isl_take isl_basic_set *dom,
4412 __isl_give isl_set **empty, int max)
4420 if (bmap->ctx->opt->pip_symmetry)
4421 par = parallel_constraints(bmap, &first, &second);
4425 return basic_map_partial_lexopt_base(bmap, dom, empty, max);
4427 return basic_map_partial_lexopt_symm(bmap, dom, empty, max,
4430 isl_basic_set_free(dom);
4431 isl_basic_map_free(bmap);
4435 /* Compute the lexicographic minimum (or maximum if "max" is set)
4436 * of "bmap" over the domain "dom" and return the result as a map.
4437 * If "empty" is not NULL, then *empty is assigned a set that
4438 * contains those parts of the domain where there is no solution.
4439 * If "bmap" is marked as rational (ISL_BASIC_MAP_RATIONAL),
4440 * then we compute the rational optimum. Otherwise, we compute
4441 * the integral optimum.
4443 * We perform some preprocessing. As the PILP solver does not
4444 * handle implicit equalities very well, we first make sure all
4445 * the equalities are explicitly available.
4447 * We also add context constraints to the basic map and remove
4448 * redundant constraints. This is only needed because of the
4449 * way we handle simple symmetries. In particular, we currently look
4450 * for symmetries on the constraints, before we set up the main tableau.
4451 * It is then no good to look for symmetries on possibly redundant constraints.
4453 struct isl_map *isl_tab_basic_map_partial_lexopt(
4454 struct isl_basic_map *bmap, struct isl_basic_set *dom,
4455 struct isl_set **empty, int max)
4462 isl_assert(bmap->ctx,
4463 isl_basic_map_compatible_domain(bmap, dom), goto error);
4465 if (isl_basic_set_dim(dom, isl_dim_all) == 0)
4466 return basic_map_partial_lexopt(bmap, dom, empty, max);
4468 bmap = isl_basic_map_intersect_domain(bmap, isl_basic_set_copy(dom));
4469 bmap = isl_basic_map_detect_equalities(bmap);
4470 bmap = isl_basic_map_remove_redundancies(bmap);
4472 return basic_map_partial_lexopt(bmap, dom, empty, max);
4474 isl_basic_set_free(dom);
4475 isl_basic_map_free(bmap);
4479 struct isl_sol_for {
4481 int (*fn)(__isl_take isl_basic_set *dom,
4482 __isl_take isl_mat *map, void *user);
4486 static void sol_for_free(struct isl_sol_for *sol_for)
4488 if (sol_for->sol.context)
4489 sol_for->sol.context->op->free(sol_for->sol.context);
4493 static void sol_for_free_wrap(struct isl_sol *sol)
4495 sol_for_free((struct isl_sol_for *)sol);
4498 /* Add the solution identified by the tableau and the context tableau.
4500 * See documentation of sol_add for more details.
4502 * Instead of constructing a basic map, this function calls a user
4503 * defined function with the current context as a basic set and
4504 * an affine matrix representing the relation between the input and output.
4505 * The number of rows in this matrix is equal to one plus the number
4506 * of output variables. The number of columns is equal to one plus
4507 * the total dimension of the context, i.e., the number of parameters,
4508 * input variables and divs. Since some of the columns in the matrix
4509 * may refer to the divs, the basic set is not simplified.
4510 * (Simplification may reorder or remove divs.)
4512 static void sol_for_add(struct isl_sol_for *sol,
4513 struct isl_basic_set *dom, struct isl_mat *M)
4515 if (sol->sol.error || !dom || !M)
4518 dom = isl_basic_set_simplify(dom);
4519 dom = isl_basic_set_finalize(dom);
4521 if (sol->fn(isl_basic_set_copy(dom), isl_mat_copy(M), sol->user) < 0)
4524 isl_basic_set_free(dom);
4528 isl_basic_set_free(dom);
4533 static void sol_for_add_wrap(struct isl_sol *sol,
4534 struct isl_basic_set *dom, struct isl_mat *M)
4536 sol_for_add((struct isl_sol_for *)sol, dom, M);
4539 static struct isl_sol_for *sol_for_init(struct isl_basic_map *bmap, int max,
4540 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
4544 struct isl_sol_for *sol_for = NULL;
4545 struct isl_dim *dom_dim;
4546 struct isl_basic_set *dom = NULL;
4548 sol_for = isl_calloc_type(bmap->ctx, struct isl_sol_for);
4552 dom_dim = isl_dim_domain(isl_dim_copy(bmap->dim));
4553 dom = isl_basic_set_universe(dom_dim);
4555 sol_for->sol.rational = ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL);
4556 sol_for->sol.dec_level.callback.run = &sol_dec_level_wrap;
4557 sol_for->sol.dec_level.sol = &sol_for->sol;
4559 sol_for->user = user;
4560 sol_for->sol.max = max;
4561 sol_for->sol.n_out = isl_basic_map_dim(bmap, isl_dim_out);
4562 sol_for->sol.add = &sol_for_add_wrap;
4563 sol_for->sol.add_empty = NULL;
4564 sol_for->sol.free = &sol_for_free_wrap;
4566 sol_for->sol.context = isl_context_alloc(dom);
4567 if (!sol_for->sol.context)
4570 isl_basic_set_free(dom);
4573 isl_basic_set_free(dom);
4574 sol_for_free(sol_for);
4578 static void sol_for_find_solutions(struct isl_sol_for *sol_for,
4579 struct isl_tab *tab)
4581 find_solutions_main(&sol_for->sol, tab);
4584 int isl_basic_map_foreach_lexopt(__isl_keep isl_basic_map *bmap, int max,
4585 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
4589 struct isl_sol_for *sol_for = NULL;
4591 bmap = isl_basic_map_copy(bmap);
4595 bmap = isl_basic_map_detect_equalities(bmap);
4596 sol_for = sol_for_init(bmap, max, fn, user);
4598 if (isl_basic_map_fast_is_empty(bmap))
4601 struct isl_tab *tab;
4602 struct isl_context *context = sol_for->sol.context;
4603 tab = tab_for_lexmin(bmap,
4604 context->op->peek_basic_set(context), 1, max);
4605 tab = context->op->detect_nonnegative_parameters(context, tab);
4606 sol_for_find_solutions(sol_for, tab);
4607 if (sol_for->sol.error)
4611 sol_free(&sol_for->sol);
4612 isl_basic_map_free(bmap);
4615 sol_free(&sol_for->sol);
4616 isl_basic_map_free(bmap);
4620 int isl_basic_map_foreach_lexmin(__isl_keep isl_basic_map *bmap,
4621 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
4625 return isl_basic_map_foreach_lexopt(bmap, 0, fn, user);
4628 int isl_basic_map_foreach_lexmax(__isl_keep isl_basic_map *bmap,
4629 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
4633 return isl_basic_map_foreach_lexopt(bmap, 1, fn, user);