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 int add_lexmin_eq(struct isl_tab *tab, isl_int *eq) WARN_UNUSED;
1291 static int 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)
1363 /* Add an inequality to the tableau, resolving violations using
1366 static struct isl_tab *add_lexmin_ineq(struct isl_tab *tab, isl_int *ineq)
1373 tab->bmap = isl_basic_map_add_ineq(tab->bmap, ineq);
1374 if (isl_tab_push(tab, isl_tab_undo_bmap_ineq) < 0)
1379 r = isl_tab_add_row(tab, ineq);
1382 tab->con[r].is_nonneg = 1;
1383 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1385 if (isl_tab_row_is_redundant(tab, tab->con[r].index)) {
1386 if (isl_tab_mark_redundant(tab, tab->con[r].index) < 0)
1391 if (restore_lexmin(tab) < 0)
1393 if (!tab->empty && tab->con[r].is_row &&
1394 isl_tab_row_is_redundant(tab, tab->con[r].index))
1395 if (isl_tab_mark_redundant(tab, tab->con[r].index) < 0)
1403 /* Check if the coefficients of the parameters are all integral.
1405 static int integer_parameter(struct isl_tab *tab, int row)
1409 unsigned off = 2 + tab->M;
1411 for (i = 0; i < tab->n_param; ++i) {
1412 /* Eliminated parameter */
1413 if (tab->var[i].is_row)
1415 col = tab->var[i].index;
1416 if (!isl_int_is_divisible_by(tab->mat->row[row][off + col],
1417 tab->mat->row[row][0]))
1420 for (i = 0; i < tab->n_div; ++i) {
1421 if (tab->var[tab->n_var - tab->n_div + i].is_row)
1423 col = tab->var[tab->n_var - tab->n_div + i].index;
1424 if (!isl_int_is_divisible_by(tab->mat->row[row][off + col],
1425 tab->mat->row[row][0]))
1431 /* Check if the coefficients of the non-parameter variables are all integral.
1433 static int integer_variable(struct isl_tab *tab, int row)
1436 unsigned off = 2 + tab->M;
1438 for (i = tab->n_dead; i < tab->n_col; ++i) {
1439 if (tab->col_var[i] >= 0 &&
1440 (tab->col_var[i] < tab->n_param ||
1441 tab->col_var[i] >= tab->n_var - tab->n_div))
1443 if (!isl_int_is_divisible_by(tab->mat->row[row][off + i],
1444 tab->mat->row[row][0]))
1450 /* Check if the constant term is integral.
1452 static int integer_constant(struct isl_tab *tab, int row)
1454 return isl_int_is_divisible_by(tab->mat->row[row][1],
1455 tab->mat->row[row][0]);
1458 #define I_CST 1 << 0
1459 #define I_PAR 1 << 1
1460 #define I_VAR 1 << 2
1462 /* Check for next (non-parameter) variable after "var" (first if var == -1)
1463 * that is non-integer and therefore requires a cut and return
1464 * the index of the variable.
1465 * For parametric tableaus, there are three parts in a row,
1466 * the constant, the coefficients of the parameters and the rest.
1467 * For each part, we check whether the coefficients in that part
1468 * are all integral and if so, set the corresponding flag in *f.
1469 * If the constant and the parameter part are integral, then the
1470 * current sample value is integral and no cut is required
1471 * (irrespective of whether the variable part is integral).
1473 static int next_non_integer_var(struct isl_tab *tab, int var, int *f)
1475 var = var < 0 ? tab->n_param : var + 1;
1477 for (; var < tab->n_var - tab->n_div; ++var) {
1480 if (!tab->var[var].is_row)
1482 row = tab->var[var].index;
1483 if (integer_constant(tab, row))
1484 ISL_FL_SET(flags, I_CST);
1485 if (integer_parameter(tab, row))
1486 ISL_FL_SET(flags, I_PAR);
1487 if (ISL_FL_ISSET(flags, I_CST) && ISL_FL_ISSET(flags, I_PAR))
1489 if (integer_variable(tab, row))
1490 ISL_FL_SET(flags, I_VAR);
1497 /* Check for first (non-parameter) variable that is non-integer and
1498 * therefore requires a cut and return the corresponding row.
1499 * For parametric tableaus, there are three parts in a row,
1500 * the constant, the coefficients of the parameters and the rest.
1501 * For each part, we check whether the coefficients in that part
1502 * are all integral and if so, set the corresponding flag in *f.
1503 * If the constant and the parameter part are integral, then the
1504 * current sample value is integral and no cut is required
1505 * (irrespective of whether the variable part is integral).
1507 static int first_non_integer_row(struct isl_tab *tab, int *f)
1509 int var = next_non_integer_var(tab, -1, f);
1511 return var < 0 ? -1 : tab->var[var].index;
1514 /* Add a (non-parametric) cut to cut away the non-integral sample
1515 * value of the given row.
1517 * If the row is given by
1519 * m r = f + \sum_i a_i y_i
1523 * c = - {-f/m} + \sum_i {a_i/m} y_i >= 0
1525 * The big parameter, if any, is ignored, since it is assumed to be big
1526 * enough to be divisible by any integer.
1527 * If the tableau is actually a parametric tableau, then this function
1528 * is only called when all coefficients of the parameters are integral.
1529 * The cut therefore has zero coefficients for the parameters.
1531 * The current value is known to be negative, so row_sign, if it
1532 * exists, is set accordingly.
1534 * Return the row of the cut or -1.
1536 static int add_cut(struct isl_tab *tab, int row)
1541 unsigned off = 2 + tab->M;
1543 if (isl_tab_extend_cons(tab, 1) < 0)
1545 r = isl_tab_allocate_con(tab);
1549 r_row = tab->mat->row[tab->con[r].index];
1550 isl_int_set(r_row[0], tab->mat->row[row][0]);
1551 isl_int_neg(r_row[1], tab->mat->row[row][1]);
1552 isl_int_fdiv_r(r_row[1], r_row[1], tab->mat->row[row][0]);
1553 isl_int_neg(r_row[1], r_row[1]);
1555 isl_int_set_si(r_row[2], 0);
1556 for (i = 0; i < tab->n_col; ++i)
1557 isl_int_fdiv_r(r_row[off + i],
1558 tab->mat->row[row][off + i], tab->mat->row[row][0]);
1560 tab->con[r].is_nonneg = 1;
1561 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1564 tab->row_sign[tab->con[r].index] = isl_tab_row_neg;
1566 return tab->con[r].index;
1569 /* Given a non-parametric tableau, add cuts until an integer
1570 * sample point is obtained or until the tableau is determined
1571 * to be integer infeasible.
1572 * As long as there is any non-integer value in the sample point,
1573 * we add appropriate cuts, if possible, for each of these
1574 * non-integer values and then resolve the violated
1575 * cut constraints using restore_lexmin.
1576 * If one of the corresponding rows is equal to an integral
1577 * combination of variables/constraints plus a non-integral constant,
1578 * then there is no way to obtain an integer point and we return
1579 * a tableau that is marked empty.
1581 static struct isl_tab *cut_to_integer_lexmin(struct isl_tab *tab)
1592 while ((var = next_non_integer_var(tab, -1, &flags)) != -1) {
1594 if (ISL_FL_ISSET(flags, I_VAR)) {
1595 if (isl_tab_mark_empty(tab) < 0)
1599 row = tab->var[var].index;
1600 row = add_cut(tab, row);
1603 } while ((var = next_non_integer_var(tab, var, &flags)) != -1);
1604 if (restore_lexmin(tab) < 0)
1615 /* Check whether all the currently active samples also satisfy the inequality
1616 * "ineq" (treated as an equality if eq is set).
1617 * Remove those samples that do not.
1619 static struct isl_tab *check_samples(struct isl_tab *tab, isl_int *ineq, int eq)
1627 isl_assert(tab->mat->ctx, tab->bmap, goto error);
1628 isl_assert(tab->mat->ctx, tab->samples, goto error);
1629 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var, goto error);
1632 for (i = tab->n_outside; i < tab->n_sample; ++i) {
1634 isl_seq_inner_product(ineq, tab->samples->row[i],
1635 1 + tab->n_var, &v);
1636 sgn = isl_int_sgn(v);
1637 if (eq ? (sgn == 0) : (sgn >= 0))
1639 tab = isl_tab_drop_sample(tab, i);
1651 /* Check whether the sample value of the tableau is finite,
1652 * i.e., either the tableau does not use a big parameter, or
1653 * all values of the variables are equal to the big parameter plus
1654 * some constant. This constant is the actual sample value.
1656 static int sample_is_finite(struct isl_tab *tab)
1663 for (i = 0; i < tab->n_var; ++i) {
1665 if (!tab->var[i].is_row)
1667 row = tab->var[i].index;
1668 if (isl_int_ne(tab->mat->row[row][0], tab->mat->row[row][2]))
1674 /* Check if the context tableau of sol has any integer points.
1675 * Leave tab in empty state if no integer point can be found.
1676 * If an integer point can be found and if moreover it is finite,
1677 * then it is added to the list of sample values.
1679 * This function is only called when none of the currently active sample
1680 * values satisfies the most recently added constraint.
1682 static struct isl_tab *check_integer_feasible(struct isl_tab *tab)
1684 struct isl_tab_undo *snap;
1690 snap = isl_tab_snap(tab);
1691 if (isl_tab_push_basis(tab) < 0)
1694 tab = cut_to_integer_lexmin(tab);
1698 if (!tab->empty && sample_is_finite(tab)) {
1699 struct isl_vec *sample;
1701 sample = isl_tab_get_sample_value(tab);
1703 tab = isl_tab_add_sample(tab, sample);
1706 if (!tab->empty && isl_tab_rollback(tab, snap) < 0)
1715 /* Check if any of the currently active sample values satisfies
1716 * the inequality "ineq" (an equality if eq is set).
1718 static int tab_has_valid_sample(struct isl_tab *tab, isl_int *ineq, int eq)
1726 isl_assert(tab->mat->ctx, tab->bmap, return -1);
1727 isl_assert(tab->mat->ctx, tab->samples, return -1);
1728 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var, return -1);
1731 for (i = tab->n_outside; i < tab->n_sample; ++i) {
1733 isl_seq_inner_product(ineq, tab->samples->row[i],
1734 1 + tab->n_var, &v);
1735 sgn = isl_int_sgn(v);
1736 if (eq ? (sgn == 0) : (sgn >= 0))
1741 return i < tab->n_sample;
1744 /* Add a div specified by "div" to the tableau "tab" and return
1745 * 1 if the div is obviously non-negative.
1747 static int context_tab_add_div(struct isl_tab *tab, struct isl_vec *div,
1748 int (*add_ineq)(void *user, isl_int *), void *user)
1752 struct isl_mat *samples;
1755 r = isl_tab_add_div(tab, div, add_ineq, user);
1758 nonneg = tab->var[r].is_nonneg;
1759 tab->var[r].frozen = 1;
1761 samples = isl_mat_extend(tab->samples,
1762 tab->n_sample, 1 + tab->n_var);
1763 tab->samples = samples;
1766 for (i = tab->n_outside; i < samples->n_row; ++i) {
1767 isl_seq_inner_product(div->el + 1, samples->row[i],
1768 div->size - 1, &samples->row[i][samples->n_col - 1]);
1769 isl_int_fdiv_q(samples->row[i][samples->n_col - 1],
1770 samples->row[i][samples->n_col - 1], div->el[0]);
1776 /* Add a div specified by "div" to both the main tableau and
1777 * the context tableau. In case of the main tableau, we only
1778 * need to add an extra div. In the context tableau, we also
1779 * need to express the meaning of the div.
1780 * Return the index of the div or -1 if anything went wrong.
1782 static int add_div(struct isl_tab *tab, struct isl_context *context,
1783 struct isl_vec *div)
1788 if ((nonneg = context->op->add_div(context, div)) < 0)
1791 if (!context->op->is_ok(context))
1794 if (isl_tab_extend_vars(tab, 1) < 0)
1796 r = isl_tab_allocate_var(tab);
1800 tab->var[r].is_nonneg = 1;
1801 tab->var[r].frozen = 1;
1804 return tab->n_div - 1;
1806 context->op->invalidate(context);
1810 static int find_div(struct isl_tab *tab, isl_int *div, isl_int denom)
1813 unsigned total = isl_basic_map_total_dim(tab->bmap);
1815 for (i = 0; i < tab->bmap->n_div; ++i) {
1816 if (isl_int_ne(tab->bmap->div[i][0], denom))
1818 if (!isl_seq_eq(tab->bmap->div[i] + 1, div, 1 + total))
1825 /* Return the index of a div that corresponds to "div".
1826 * We first check if we already have such a div and if not, we create one.
1828 static int get_div(struct isl_tab *tab, struct isl_context *context,
1829 struct isl_vec *div)
1832 struct isl_tab *context_tab = context->op->peek_tab(context);
1837 d = find_div(context_tab, div->el + 1, div->el[0]);
1841 return add_div(tab, context, div);
1844 /* Add a parametric cut to cut away the non-integral sample value
1846 * Let a_i be the coefficients of the constant term and the parameters
1847 * and let b_i be the coefficients of the variables or constraints
1848 * in basis of the tableau.
1849 * Let q be the div q = floor(\sum_i {-a_i} y_i).
1851 * The cut is expressed as
1853 * c = \sum_i -{-a_i} y_i + \sum_i {b_i} x_i + q >= 0
1855 * If q did not already exist in the context tableau, then it is added first.
1856 * If q is in a column of the main tableau then the "+ q" can be accomplished
1857 * by setting the corresponding entry to the denominator of the constraint.
1858 * If q happens to be in a row of the main tableau, then the corresponding
1859 * row needs to be added instead (taking care of the denominators).
1860 * Note that this is very unlikely, but perhaps not entirely impossible.
1862 * The current value of the cut is known to be negative (or at least
1863 * non-positive), so row_sign is set accordingly.
1865 * Return the row of the cut or -1.
1867 static int add_parametric_cut(struct isl_tab *tab, int row,
1868 struct isl_context *context)
1870 struct isl_vec *div;
1877 unsigned off = 2 + tab->M;
1882 div = get_row_parameter_div(tab, row);
1887 d = context->op->get_div(context, tab, div);
1891 if (isl_tab_extend_cons(tab, 1) < 0)
1893 r = isl_tab_allocate_con(tab);
1897 r_row = tab->mat->row[tab->con[r].index];
1898 isl_int_set(r_row[0], tab->mat->row[row][0]);
1899 isl_int_neg(r_row[1], tab->mat->row[row][1]);
1900 isl_int_fdiv_r(r_row[1], r_row[1], tab->mat->row[row][0]);
1901 isl_int_neg(r_row[1], r_row[1]);
1903 isl_int_set_si(r_row[2], 0);
1904 for (i = 0; i < tab->n_param; ++i) {
1905 if (tab->var[i].is_row)
1907 col = tab->var[i].index;
1908 isl_int_neg(r_row[off + col], tab->mat->row[row][off + col]);
1909 isl_int_fdiv_r(r_row[off + col], r_row[off + col],
1910 tab->mat->row[row][0]);
1911 isl_int_neg(r_row[off + col], r_row[off + col]);
1913 for (i = 0; i < tab->n_div; ++i) {
1914 if (tab->var[tab->n_var - tab->n_div + i].is_row)
1916 col = tab->var[tab->n_var - tab->n_div + i].index;
1917 isl_int_neg(r_row[off + col], tab->mat->row[row][off + col]);
1918 isl_int_fdiv_r(r_row[off + col], r_row[off + col],
1919 tab->mat->row[row][0]);
1920 isl_int_neg(r_row[off + col], r_row[off + col]);
1922 for (i = 0; i < tab->n_col; ++i) {
1923 if (tab->col_var[i] >= 0 &&
1924 (tab->col_var[i] < tab->n_param ||
1925 tab->col_var[i] >= tab->n_var - tab->n_div))
1927 isl_int_fdiv_r(r_row[off + i],
1928 tab->mat->row[row][off + i], tab->mat->row[row][0]);
1930 if (tab->var[tab->n_var - tab->n_div + d].is_row) {
1932 int d_row = tab->var[tab->n_var - tab->n_div + d].index;
1934 isl_int_gcd(gcd, tab->mat->row[d_row][0], r_row[0]);
1935 isl_int_divexact(r_row[0], r_row[0], gcd);
1936 isl_int_divexact(gcd, tab->mat->row[d_row][0], gcd);
1937 isl_seq_combine(r_row + 1, gcd, r_row + 1,
1938 r_row[0], tab->mat->row[d_row] + 1,
1939 off - 1 + tab->n_col);
1940 isl_int_mul(r_row[0], r_row[0], tab->mat->row[d_row][0]);
1943 col = tab->var[tab->n_var - tab->n_div + d].index;
1944 isl_int_set(r_row[off + col], tab->mat->row[row][0]);
1947 tab->con[r].is_nonneg = 1;
1948 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1951 tab->row_sign[tab->con[r].index] = isl_tab_row_neg;
1955 row = tab->con[r].index;
1957 if (d >= n && context->op->detect_equalities(context, tab) < 0)
1963 /* Construct a tableau for bmap that can be used for computing
1964 * the lexicographic minimum (or maximum) of bmap.
1965 * If not NULL, then dom is the domain where the minimum
1966 * should be computed. In this case, we set up a parametric
1967 * tableau with row signs (initialized to "unknown").
1968 * If M is set, then the tableau will use a big parameter.
1969 * If max is set, then a maximum should be computed instead of a minimum.
1970 * This means that for each variable x, the tableau will contain the variable
1971 * x' = M - x, rather than x' = M + x. This in turn means that the coefficient
1972 * of the variables in all constraints are negated prior to adding them
1975 static struct isl_tab *tab_for_lexmin(struct isl_basic_map *bmap,
1976 struct isl_basic_set *dom, unsigned M, int max)
1979 struct isl_tab *tab;
1981 tab = isl_tab_alloc(bmap->ctx, 2 * bmap->n_eq + bmap->n_ineq + 1,
1982 isl_basic_map_total_dim(bmap), M);
1986 tab->rational = ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL);
1988 tab->n_param = isl_basic_set_total_dim(dom) - dom->n_div;
1989 tab->n_div = dom->n_div;
1990 tab->row_sign = isl_calloc_array(bmap->ctx,
1991 enum isl_tab_row_sign, tab->mat->n_row);
1995 if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_EMPTY)) {
1996 if (isl_tab_mark_empty(tab) < 0)
2001 for (i = tab->n_param; i < tab->n_var - tab->n_div; ++i) {
2002 tab->var[i].is_nonneg = 1;
2003 tab->var[i].frozen = 1;
2005 for (i = 0; i < bmap->n_eq; ++i) {
2007 isl_seq_neg(bmap->eq[i] + 1 + tab->n_param,
2008 bmap->eq[i] + 1 + tab->n_param,
2009 tab->n_var - tab->n_param - tab->n_div);
2010 tab = add_lexmin_valid_eq(tab, bmap->eq[i]);
2012 isl_seq_neg(bmap->eq[i] + 1 + tab->n_param,
2013 bmap->eq[i] + 1 + tab->n_param,
2014 tab->n_var - tab->n_param - tab->n_div);
2015 if (!tab || tab->empty)
2018 if (bmap->n_eq && restore_lexmin(tab) < 0)
2020 for (i = 0; i < bmap->n_ineq; ++i) {
2022 isl_seq_neg(bmap->ineq[i] + 1 + tab->n_param,
2023 bmap->ineq[i] + 1 + tab->n_param,
2024 tab->n_var - tab->n_param - tab->n_div);
2025 tab = add_lexmin_ineq(tab, bmap->ineq[i]);
2027 isl_seq_neg(bmap->ineq[i] + 1 + tab->n_param,
2028 bmap->ineq[i] + 1 + tab->n_param,
2029 tab->n_var - tab->n_param - tab->n_div);
2030 if (!tab || tab->empty)
2039 /* Given a main tableau where more than one row requires a split,
2040 * determine and return the "best" row to split on.
2042 * Given two rows in the main tableau, if the inequality corresponding
2043 * to the first row is redundant with respect to that of the second row
2044 * in the current tableau, then it is better to split on the second row,
2045 * since in the positive part, both row will be positive.
2046 * (In the negative part a pivot will have to be performed and just about
2047 * anything can happen to the sign of the other row.)
2049 * As a simple heuristic, we therefore select the row that makes the most
2050 * of the other rows redundant.
2052 * Perhaps it would also be useful to look at the number of constraints
2053 * that conflict with any given constraint.
2055 static int best_split(struct isl_tab *tab, struct isl_tab *context_tab)
2057 struct isl_tab_undo *snap;
2063 if (isl_tab_extend_cons(context_tab, 2) < 0)
2066 snap = isl_tab_snap(context_tab);
2068 for (split = tab->n_redundant; split < tab->n_row; ++split) {
2069 struct isl_tab_undo *snap2;
2070 struct isl_vec *ineq = NULL;
2074 if (!isl_tab_var_from_row(tab, split)->is_nonneg)
2076 if (tab->row_sign[split] != isl_tab_row_any)
2079 ineq = get_row_parameter_ineq(tab, split);
2082 ok = isl_tab_add_ineq(context_tab, ineq->el) >= 0;
2087 snap2 = isl_tab_snap(context_tab);
2089 for (row = tab->n_redundant; row < tab->n_row; ++row) {
2090 struct isl_tab_var *var;
2094 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
2096 if (tab->row_sign[row] != isl_tab_row_any)
2099 ineq = get_row_parameter_ineq(tab, row);
2102 ok = isl_tab_add_ineq(context_tab, ineq->el) >= 0;
2106 var = &context_tab->con[context_tab->n_con - 1];
2107 if (!context_tab->empty &&
2108 !isl_tab_min_at_most_neg_one(context_tab, var))
2110 if (isl_tab_rollback(context_tab, snap2) < 0)
2113 if (best == -1 || r > best_r) {
2117 if (isl_tab_rollback(context_tab, snap) < 0)
2124 static struct isl_basic_set *context_lex_peek_basic_set(
2125 struct isl_context *context)
2127 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2130 return isl_tab_peek_bset(clex->tab);
2133 static struct isl_tab *context_lex_peek_tab(struct isl_context *context)
2135 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2139 static void context_lex_extend(struct isl_context *context, int n)
2141 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2144 if (isl_tab_extend_cons(clex->tab, n) >= 0)
2146 isl_tab_free(clex->tab);
2150 static void context_lex_add_eq(struct isl_context *context, isl_int *eq,
2151 int check, int update)
2153 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2154 if (isl_tab_extend_cons(clex->tab, 2) < 0)
2156 if (add_lexmin_eq(clex->tab, eq) < 0)
2159 int v = tab_has_valid_sample(clex->tab, eq, 1);
2163 clex->tab = check_integer_feasible(clex->tab);
2166 clex->tab = check_samples(clex->tab, eq, 1);
2169 isl_tab_free(clex->tab);
2173 static void context_lex_add_ineq(struct isl_context *context, isl_int *ineq,
2174 int check, int update)
2176 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2177 if (isl_tab_extend_cons(clex->tab, 1) < 0)
2179 clex->tab = add_lexmin_ineq(clex->tab, ineq);
2181 int v = tab_has_valid_sample(clex->tab, ineq, 0);
2185 clex->tab = check_integer_feasible(clex->tab);
2188 clex->tab = check_samples(clex->tab, ineq, 0);
2191 isl_tab_free(clex->tab);
2195 static int context_lex_add_ineq_wrap(void *user, isl_int *ineq)
2197 struct isl_context *context = (struct isl_context *)user;
2198 context_lex_add_ineq(context, ineq, 0, 0);
2199 return context->op->is_ok(context) ? 0 : -1;
2202 /* Check which signs can be obtained by "ineq" on all the currently
2203 * active sample values. See row_sign for more information.
2205 static enum isl_tab_row_sign tab_ineq_sign(struct isl_tab *tab, isl_int *ineq,
2211 enum isl_tab_row_sign res = isl_tab_row_unknown;
2213 isl_assert(tab->mat->ctx, tab->samples, return isl_tab_row_unknown);
2214 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var,
2215 return isl_tab_row_unknown);
2218 for (i = tab->n_outside; i < tab->n_sample; ++i) {
2219 isl_seq_inner_product(tab->samples->row[i], ineq,
2220 1 + tab->n_var, &tmp);
2221 sgn = isl_int_sgn(tmp);
2222 if (sgn > 0 || (sgn == 0 && strict)) {
2223 if (res == isl_tab_row_unknown)
2224 res = isl_tab_row_pos;
2225 if (res == isl_tab_row_neg)
2226 res = isl_tab_row_any;
2229 if (res == isl_tab_row_unknown)
2230 res = isl_tab_row_neg;
2231 if (res == isl_tab_row_pos)
2232 res = isl_tab_row_any;
2234 if (res == isl_tab_row_any)
2242 static enum isl_tab_row_sign context_lex_ineq_sign(struct isl_context *context,
2243 isl_int *ineq, int strict)
2245 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2246 return tab_ineq_sign(clex->tab, ineq, strict);
2249 /* Check whether "ineq" can be added to the tableau without rendering
2252 static int context_lex_test_ineq(struct isl_context *context, isl_int *ineq)
2254 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2255 struct isl_tab_undo *snap;
2261 if (isl_tab_extend_cons(clex->tab, 1) < 0)
2264 snap = isl_tab_snap(clex->tab);
2265 if (isl_tab_push_basis(clex->tab) < 0)
2267 clex->tab = add_lexmin_ineq(clex->tab, ineq);
2268 clex->tab = check_integer_feasible(clex->tab);
2271 feasible = !clex->tab->empty;
2272 if (isl_tab_rollback(clex->tab, snap) < 0)
2278 static int context_lex_get_div(struct isl_context *context, struct isl_tab *tab,
2279 struct isl_vec *div)
2281 return get_div(tab, context, div);
2284 /* Add a div specified by "div" to the context tableau and return
2285 * 1 if the div is obviously non-negative.
2286 * context_tab_add_div will always return 1, because all variables
2287 * in a isl_context_lex tableau are non-negative.
2288 * However, if we are using a big parameter in the context, then this only
2289 * reflects the non-negativity of the variable used to _encode_ the
2290 * div, i.e., div' = M + div, so we can't draw any conclusions.
2292 static int context_lex_add_div(struct isl_context *context, struct isl_vec *div)
2294 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2296 nonneg = context_tab_add_div(clex->tab, div,
2297 context_lex_add_ineq_wrap, context);
2305 static int context_lex_detect_equalities(struct isl_context *context,
2306 struct isl_tab *tab)
2311 static int context_lex_best_split(struct isl_context *context,
2312 struct isl_tab *tab)
2314 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2315 struct isl_tab_undo *snap;
2318 snap = isl_tab_snap(clex->tab);
2319 if (isl_tab_push_basis(clex->tab) < 0)
2321 r = best_split(tab, clex->tab);
2323 if (r >= 0 && isl_tab_rollback(clex->tab, snap) < 0)
2329 static int context_lex_is_empty(struct isl_context *context)
2331 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2334 return clex->tab->empty;
2337 static void *context_lex_save(struct isl_context *context)
2339 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2340 struct isl_tab_undo *snap;
2342 snap = isl_tab_snap(clex->tab);
2343 if (isl_tab_push_basis(clex->tab) < 0)
2345 if (isl_tab_save_samples(clex->tab) < 0)
2351 static void context_lex_restore(struct isl_context *context, void *save)
2353 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2354 if (isl_tab_rollback(clex->tab, (struct isl_tab_undo *)save) < 0) {
2355 isl_tab_free(clex->tab);
2360 static int context_lex_is_ok(struct isl_context *context)
2362 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2366 /* For each variable in the context tableau, check if the variable can
2367 * only attain non-negative values. If so, mark the parameter as non-negative
2368 * in the main tableau. This allows for a more direct identification of some
2369 * cases of violated constraints.
2371 static struct isl_tab *tab_detect_nonnegative_parameters(struct isl_tab *tab,
2372 struct isl_tab *context_tab)
2375 struct isl_tab_undo *snap;
2376 struct isl_vec *ineq = NULL;
2377 struct isl_tab_var *var;
2380 if (context_tab->n_var == 0)
2383 ineq = isl_vec_alloc(tab->mat->ctx, 1 + context_tab->n_var);
2387 if (isl_tab_extend_cons(context_tab, 1) < 0)
2390 snap = isl_tab_snap(context_tab);
2393 isl_seq_clr(ineq->el, ineq->size);
2394 for (i = 0; i < context_tab->n_var; ++i) {
2395 isl_int_set_si(ineq->el[1 + i], 1);
2396 if (isl_tab_add_ineq(context_tab, ineq->el) < 0)
2398 var = &context_tab->con[context_tab->n_con - 1];
2399 if (!context_tab->empty &&
2400 !isl_tab_min_at_most_neg_one(context_tab, var)) {
2402 if (i >= tab->n_param)
2403 j = i - tab->n_param + tab->n_var - tab->n_div;
2404 tab->var[j].is_nonneg = 1;
2407 isl_int_set_si(ineq->el[1 + i], 0);
2408 if (isl_tab_rollback(context_tab, snap) < 0)
2412 if (context_tab->M && n == context_tab->n_var) {
2413 context_tab->mat = isl_mat_drop_cols(context_tab->mat, 2, 1);
2425 static struct isl_tab *context_lex_detect_nonnegative_parameters(
2426 struct isl_context *context, struct isl_tab *tab)
2428 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2429 struct isl_tab_undo *snap;
2434 snap = isl_tab_snap(clex->tab);
2435 if (isl_tab_push_basis(clex->tab) < 0)
2438 tab = tab_detect_nonnegative_parameters(tab, clex->tab);
2440 if (isl_tab_rollback(clex->tab, snap) < 0)
2449 static void context_lex_invalidate(struct isl_context *context)
2451 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2452 isl_tab_free(clex->tab);
2456 static void context_lex_free(struct isl_context *context)
2458 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2459 isl_tab_free(clex->tab);
2463 struct isl_context_op isl_context_lex_op = {
2464 context_lex_detect_nonnegative_parameters,
2465 context_lex_peek_basic_set,
2466 context_lex_peek_tab,
2468 context_lex_add_ineq,
2469 context_lex_ineq_sign,
2470 context_lex_test_ineq,
2471 context_lex_get_div,
2472 context_lex_add_div,
2473 context_lex_detect_equalities,
2474 context_lex_best_split,
2475 context_lex_is_empty,
2478 context_lex_restore,
2479 context_lex_invalidate,
2483 static struct isl_tab *context_tab_for_lexmin(struct isl_basic_set *bset)
2485 struct isl_tab *tab;
2487 bset = isl_basic_set_cow(bset);
2490 tab = tab_for_lexmin((struct isl_basic_map *)bset, NULL, 1, 0);
2493 if (isl_tab_track_bset(tab, bset) < 0)
2495 tab = isl_tab_init_samples(tab);
2498 isl_basic_set_free(bset);
2502 static struct isl_context *isl_context_lex_alloc(struct isl_basic_set *dom)
2504 struct isl_context_lex *clex;
2509 clex = isl_alloc_type(dom->ctx, struct isl_context_lex);
2513 clex->context.op = &isl_context_lex_op;
2515 clex->tab = context_tab_for_lexmin(isl_basic_set_copy(dom));
2516 if (restore_lexmin(clex->tab) < 0)
2518 clex->tab = check_integer_feasible(clex->tab);
2522 return &clex->context;
2524 clex->context.op->free(&clex->context);
2528 struct isl_context_gbr {
2529 struct isl_context context;
2530 struct isl_tab *tab;
2531 struct isl_tab *shifted;
2532 struct isl_tab *cone;
2535 static struct isl_tab *context_gbr_detect_nonnegative_parameters(
2536 struct isl_context *context, struct isl_tab *tab)
2538 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2541 return tab_detect_nonnegative_parameters(tab, cgbr->tab);
2544 static struct isl_basic_set *context_gbr_peek_basic_set(
2545 struct isl_context *context)
2547 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2550 return isl_tab_peek_bset(cgbr->tab);
2553 static struct isl_tab *context_gbr_peek_tab(struct isl_context *context)
2555 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2559 /* Initialize the "shifted" tableau of the context, which
2560 * contains the constraints of the original tableau shifted
2561 * by the sum of all negative coefficients. This ensures
2562 * that any rational point in the shifted tableau can
2563 * be rounded up to yield an integer point in the original tableau.
2565 static void gbr_init_shifted(struct isl_context_gbr *cgbr)
2568 struct isl_vec *cst;
2569 struct isl_basic_set *bset = isl_tab_peek_bset(cgbr->tab);
2570 unsigned dim = isl_basic_set_total_dim(bset);
2572 cst = isl_vec_alloc(cgbr->tab->mat->ctx, bset->n_ineq);
2576 for (i = 0; i < bset->n_ineq; ++i) {
2577 isl_int_set(cst->el[i], bset->ineq[i][0]);
2578 for (j = 0; j < dim; ++j) {
2579 if (!isl_int_is_neg(bset->ineq[i][1 + j]))
2581 isl_int_add(bset->ineq[i][0], bset->ineq[i][0],
2582 bset->ineq[i][1 + j]);
2586 cgbr->shifted = isl_tab_from_basic_set(bset);
2588 for (i = 0; i < bset->n_ineq; ++i)
2589 isl_int_set(bset->ineq[i][0], cst->el[i]);
2594 /* Check if the shifted tableau is non-empty, and if so
2595 * use the sample point to construct an integer point
2596 * of the context tableau.
2598 static struct isl_vec *gbr_get_shifted_sample(struct isl_context_gbr *cgbr)
2600 struct isl_vec *sample;
2603 gbr_init_shifted(cgbr);
2606 if (cgbr->shifted->empty)
2607 return isl_vec_alloc(cgbr->tab->mat->ctx, 0);
2609 sample = isl_tab_get_sample_value(cgbr->shifted);
2610 sample = isl_vec_ceil(sample);
2615 static struct isl_basic_set *drop_constant_terms(struct isl_basic_set *bset)
2622 for (i = 0; i < bset->n_eq; ++i)
2623 isl_int_set_si(bset->eq[i][0], 0);
2625 for (i = 0; i < bset->n_ineq; ++i)
2626 isl_int_set_si(bset->ineq[i][0], 0);
2631 static int use_shifted(struct isl_context_gbr *cgbr)
2633 return cgbr->tab->bmap->n_eq == 0 && cgbr->tab->bmap->n_div == 0;
2636 static struct isl_vec *gbr_get_sample(struct isl_context_gbr *cgbr)
2638 struct isl_basic_set *bset;
2639 struct isl_basic_set *cone;
2641 if (isl_tab_sample_is_integer(cgbr->tab))
2642 return isl_tab_get_sample_value(cgbr->tab);
2644 if (use_shifted(cgbr)) {
2645 struct isl_vec *sample;
2647 sample = gbr_get_shifted_sample(cgbr);
2648 if (!sample || sample->size > 0)
2651 isl_vec_free(sample);
2655 bset = isl_tab_peek_bset(cgbr->tab);
2656 cgbr->cone = isl_tab_from_recession_cone(bset, 0);
2659 if (isl_tab_track_bset(cgbr->cone, isl_basic_set_dup(bset)) < 0)
2662 if (isl_tab_detect_implicit_equalities(cgbr->cone) < 0)
2665 if (cgbr->cone->n_dead == cgbr->cone->n_col) {
2666 struct isl_vec *sample;
2667 struct isl_tab_undo *snap;
2669 if (cgbr->tab->basis) {
2670 if (cgbr->tab->basis->n_col != 1 + cgbr->tab->n_var) {
2671 isl_mat_free(cgbr->tab->basis);
2672 cgbr->tab->basis = NULL;
2674 cgbr->tab->n_zero = 0;
2675 cgbr->tab->n_unbounded = 0;
2678 snap = isl_tab_snap(cgbr->tab);
2680 sample = isl_tab_sample(cgbr->tab);
2682 if (isl_tab_rollback(cgbr->tab, snap) < 0) {
2683 isl_vec_free(sample);
2690 cone = isl_basic_set_dup(isl_tab_peek_bset(cgbr->cone));
2691 cone = drop_constant_terms(cone);
2692 cone = isl_basic_set_update_from_tab(cone, cgbr->cone);
2693 cone = isl_basic_set_underlying_set(cone);
2694 cone = isl_basic_set_gauss(cone, NULL);
2696 bset = isl_basic_set_dup(isl_tab_peek_bset(cgbr->tab));
2697 bset = isl_basic_set_update_from_tab(bset, cgbr->tab);
2698 bset = isl_basic_set_underlying_set(bset);
2699 bset = isl_basic_set_gauss(bset, NULL);
2701 return isl_basic_set_sample_with_cone(bset, cone);
2704 static void check_gbr_integer_feasible(struct isl_context_gbr *cgbr)
2706 struct isl_vec *sample;
2711 if (cgbr->tab->empty)
2714 sample = gbr_get_sample(cgbr);
2718 if (sample->size == 0) {
2719 isl_vec_free(sample);
2720 if (isl_tab_mark_empty(cgbr->tab) < 0)
2725 cgbr->tab = isl_tab_add_sample(cgbr->tab, sample);
2729 isl_tab_free(cgbr->tab);
2733 static struct isl_tab *add_gbr_eq(struct isl_tab *tab, isl_int *eq)
2740 if (isl_tab_extend_cons(tab, 2) < 0)
2743 if (isl_tab_add_eq(tab, eq) < 0)
2752 static void context_gbr_add_eq(struct isl_context *context, isl_int *eq,
2753 int check, int update)
2755 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2757 cgbr->tab = add_gbr_eq(cgbr->tab, eq);
2759 if (cgbr->cone && cgbr->cone->n_col != cgbr->cone->n_dead) {
2760 if (isl_tab_extend_cons(cgbr->cone, 2) < 0)
2762 if (isl_tab_add_eq(cgbr->cone, eq) < 0)
2767 int v = tab_has_valid_sample(cgbr->tab, eq, 1);
2771 check_gbr_integer_feasible(cgbr);
2774 cgbr->tab = check_samples(cgbr->tab, eq, 1);
2777 isl_tab_free(cgbr->tab);
2781 static void add_gbr_ineq(struct isl_context_gbr *cgbr, isl_int *ineq)
2786 if (isl_tab_extend_cons(cgbr->tab, 1) < 0)
2789 if (isl_tab_add_ineq(cgbr->tab, ineq) < 0)
2792 if (cgbr->shifted && !cgbr->shifted->empty && use_shifted(cgbr)) {
2795 dim = isl_basic_map_total_dim(cgbr->tab->bmap);
2797 if (isl_tab_extend_cons(cgbr->shifted, 1) < 0)
2800 for (i = 0; i < dim; ++i) {
2801 if (!isl_int_is_neg(ineq[1 + i]))
2803 isl_int_add(ineq[0], ineq[0], ineq[1 + i]);
2806 if (isl_tab_add_ineq(cgbr->shifted, ineq) < 0)
2809 for (i = 0; i < dim; ++i) {
2810 if (!isl_int_is_neg(ineq[1 + i]))
2812 isl_int_sub(ineq[0], ineq[0], ineq[1 + i]);
2816 if (cgbr->cone && cgbr->cone->n_col != cgbr->cone->n_dead) {
2817 if (isl_tab_extend_cons(cgbr->cone, 1) < 0)
2819 if (isl_tab_add_ineq(cgbr->cone, ineq) < 0)
2825 isl_tab_free(cgbr->tab);
2829 static void context_gbr_add_ineq(struct isl_context *context, isl_int *ineq,
2830 int check, int update)
2832 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2834 add_gbr_ineq(cgbr, ineq);
2839 int v = tab_has_valid_sample(cgbr->tab, ineq, 0);
2843 check_gbr_integer_feasible(cgbr);
2846 cgbr->tab = check_samples(cgbr->tab, ineq, 0);
2849 isl_tab_free(cgbr->tab);
2853 static int context_gbr_add_ineq_wrap(void *user, isl_int *ineq)
2855 struct isl_context *context = (struct isl_context *)user;
2856 context_gbr_add_ineq(context, ineq, 0, 0);
2857 return context->op->is_ok(context) ? 0 : -1;
2860 static enum isl_tab_row_sign context_gbr_ineq_sign(struct isl_context *context,
2861 isl_int *ineq, int strict)
2863 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2864 return tab_ineq_sign(cgbr->tab, ineq, strict);
2867 /* Check whether "ineq" can be added to the tableau without rendering
2870 static int context_gbr_test_ineq(struct isl_context *context, isl_int *ineq)
2872 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2873 struct isl_tab_undo *snap;
2874 struct isl_tab_undo *shifted_snap = NULL;
2875 struct isl_tab_undo *cone_snap = NULL;
2881 if (isl_tab_extend_cons(cgbr->tab, 1) < 0)
2884 snap = isl_tab_snap(cgbr->tab);
2886 shifted_snap = isl_tab_snap(cgbr->shifted);
2888 cone_snap = isl_tab_snap(cgbr->cone);
2889 add_gbr_ineq(cgbr, ineq);
2890 check_gbr_integer_feasible(cgbr);
2893 feasible = !cgbr->tab->empty;
2894 if (isl_tab_rollback(cgbr->tab, snap) < 0)
2897 if (isl_tab_rollback(cgbr->shifted, shifted_snap))
2899 } else if (cgbr->shifted) {
2900 isl_tab_free(cgbr->shifted);
2901 cgbr->shifted = NULL;
2904 if (isl_tab_rollback(cgbr->cone, cone_snap))
2906 } else if (cgbr->cone) {
2907 isl_tab_free(cgbr->cone);
2914 /* Return the column of the last of the variables associated to
2915 * a column that has a non-zero coefficient.
2916 * This function is called in a context where only coefficients
2917 * of parameters or divs can be non-zero.
2919 static int last_non_zero_var_col(struct isl_tab *tab, isl_int *p)
2923 unsigned dim = tab->n_var - tab->n_param - tab->n_div;
2925 if (tab->n_var == 0)
2928 for (i = tab->n_var - 1; i >= 0; --i) {
2929 if (i >= tab->n_param && i < tab->n_var - tab->n_div)
2931 if (tab->var[i].is_row)
2933 col = tab->var[i].index;
2934 if (!isl_int_is_zero(p[col]))
2941 /* Look through all the recently added equalities in the context
2942 * to see if we can propagate any of them to the main tableau.
2944 * The newly added equalities in the context are encoded as pairs
2945 * of inequalities starting at inequality "first".
2947 * We tentatively add each of these equalities to the main tableau
2948 * and if this happens to result in a row with a final coefficient
2949 * that is one or negative one, we use it to kill a column
2950 * in the main tableau. Otherwise, we discard the tentatively
2953 static void propagate_equalities(struct isl_context_gbr *cgbr,
2954 struct isl_tab *tab, unsigned first)
2957 struct isl_vec *eq = NULL;
2959 eq = isl_vec_alloc(tab->mat->ctx, 1 + tab->n_var);
2963 if (isl_tab_extend_cons(tab, (cgbr->tab->bmap->n_ineq - first)/2) < 0)
2966 isl_seq_clr(eq->el + 1 + tab->n_param,
2967 tab->n_var - tab->n_param - tab->n_div);
2968 for (i = first; i < cgbr->tab->bmap->n_ineq; i += 2) {
2971 struct isl_tab_undo *snap;
2972 snap = isl_tab_snap(tab);
2974 isl_seq_cpy(eq->el, cgbr->tab->bmap->ineq[i], 1 + tab->n_param);
2975 isl_seq_cpy(eq->el + 1 + tab->n_var - tab->n_div,
2976 cgbr->tab->bmap->ineq[i] + 1 + tab->n_param,
2979 r = isl_tab_add_row(tab, eq->el);
2982 r = tab->con[r].index;
2983 j = last_non_zero_var_col(tab, tab->mat->row[r] + 2 + tab->M);
2984 if (j < 0 || j < tab->n_dead ||
2985 !isl_int_is_one(tab->mat->row[r][0]) ||
2986 (!isl_int_is_one(tab->mat->row[r][2 + tab->M + j]) &&
2987 !isl_int_is_negone(tab->mat->row[r][2 + tab->M + j]))) {
2988 if (isl_tab_rollback(tab, snap) < 0)
2992 if (isl_tab_pivot(tab, r, j) < 0)
2994 if (isl_tab_kill_col(tab, j) < 0)
2997 if (restore_lexmin(tab) < 0)
3006 isl_tab_free(cgbr->tab);
3010 static int context_gbr_detect_equalities(struct isl_context *context,
3011 struct isl_tab *tab)
3013 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3014 struct isl_ctx *ctx;
3016 enum isl_lp_result res;
3019 ctx = cgbr->tab->mat->ctx;
3022 struct isl_basic_set *bset = isl_tab_peek_bset(cgbr->tab);
3023 cgbr->cone = isl_tab_from_recession_cone(bset, 0);
3026 if (isl_tab_track_bset(cgbr->cone, isl_basic_set_dup(bset)) < 0)
3029 if (isl_tab_detect_implicit_equalities(cgbr->cone) < 0)
3032 n_ineq = cgbr->tab->bmap->n_ineq;
3033 cgbr->tab = isl_tab_detect_equalities(cgbr->tab, cgbr->cone);
3034 if (cgbr->tab && cgbr->tab->bmap->n_ineq > n_ineq)
3035 propagate_equalities(cgbr, tab, n_ineq);
3039 isl_tab_free(cgbr->tab);
3044 static int context_gbr_get_div(struct isl_context *context, struct isl_tab *tab,
3045 struct isl_vec *div)
3047 return get_div(tab, context, div);
3050 static int context_gbr_add_div(struct isl_context *context, struct isl_vec *div)
3052 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3056 if (isl_tab_extend_cons(cgbr->cone, 3) < 0)
3058 if (isl_tab_extend_vars(cgbr->cone, 1) < 0)
3060 if (isl_tab_allocate_var(cgbr->cone) <0)
3063 cgbr->cone->bmap = isl_basic_map_extend_dim(cgbr->cone->bmap,
3064 isl_basic_map_get_dim(cgbr->cone->bmap), 1, 0, 2);
3065 k = isl_basic_map_alloc_div(cgbr->cone->bmap);
3068 isl_seq_cpy(cgbr->cone->bmap->div[k], div->el, div->size);
3069 if (isl_tab_push(cgbr->cone, isl_tab_undo_bmap_div) < 0)
3072 return context_tab_add_div(cgbr->tab, div,
3073 context_gbr_add_ineq_wrap, context);
3076 static int context_gbr_best_split(struct isl_context *context,
3077 struct isl_tab *tab)
3079 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3080 struct isl_tab_undo *snap;
3083 snap = isl_tab_snap(cgbr->tab);
3084 r = best_split(tab, cgbr->tab);
3086 if (r >= 0 && isl_tab_rollback(cgbr->tab, snap) < 0)
3092 static int context_gbr_is_empty(struct isl_context *context)
3094 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3097 return cgbr->tab->empty;
3100 struct isl_gbr_tab_undo {
3101 struct isl_tab_undo *tab_snap;
3102 struct isl_tab_undo *shifted_snap;
3103 struct isl_tab_undo *cone_snap;
3106 static void *context_gbr_save(struct isl_context *context)
3108 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3109 struct isl_gbr_tab_undo *snap;
3111 snap = isl_alloc_type(cgbr->tab->mat->ctx, struct isl_gbr_tab_undo);
3115 snap->tab_snap = isl_tab_snap(cgbr->tab);
3116 if (isl_tab_save_samples(cgbr->tab) < 0)
3120 snap->shifted_snap = isl_tab_snap(cgbr->shifted);
3122 snap->shifted_snap = NULL;
3125 snap->cone_snap = isl_tab_snap(cgbr->cone);
3127 snap->cone_snap = NULL;
3135 static void context_gbr_restore(struct isl_context *context, void *save)
3137 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3138 struct isl_gbr_tab_undo *snap = (struct isl_gbr_tab_undo *)save;
3141 if (isl_tab_rollback(cgbr->tab, snap->tab_snap) < 0) {
3142 isl_tab_free(cgbr->tab);
3146 if (snap->shifted_snap) {
3147 if (isl_tab_rollback(cgbr->shifted, snap->shifted_snap) < 0)
3149 } else if (cgbr->shifted) {
3150 isl_tab_free(cgbr->shifted);
3151 cgbr->shifted = NULL;
3154 if (snap->cone_snap) {
3155 if (isl_tab_rollback(cgbr->cone, snap->cone_snap) < 0)
3157 } else if (cgbr->cone) {
3158 isl_tab_free(cgbr->cone);
3167 isl_tab_free(cgbr->tab);
3171 static int context_gbr_is_ok(struct isl_context *context)
3173 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3177 static void context_gbr_invalidate(struct isl_context *context)
3179 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3180 isl_tab_free(cgbr->tab);
3184 static void context_gbr_free(struct isl_context *context)
3186 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
3187 isl_tab_free(cgbr->tab);
3188 isl_tab_free(cgbr->shifted);
3189 isl_tab_free(cgbr->cone);
3193 struct isl_context_op isl_context_gbr_op = {
3194 context_gbr_detect_nonnegative_parameters,
3195 context_gbr_peek_basic_set,
3196 context_gbr_peek_tab,
3198 context_gbr_add_ineq,
3199 context_gbr_ineq_sign,
3200 context_gbr_test_ineq,
3201 context_gbr_get_div,
3202 context_gbr_add_div,
3203 context_gbr_detect_equalities,
3204 context_gbr_best_split,
3205 context_gbr_is_empty,
3208 context_gbr_restore,
3209 context_gbr_invalidate,
3213 static struct isl_context *isl_context_gbr_alloc(struct isl_basic_set *dom)
3215 struct isl_context_gbr *cgbr;
3220 cgbr = isl_calloc_type(dom->ctx, struct isl_context_gbr);
3224 cgbr->context.op = &isl_context_gbr_op;
3226 cgbr->shifted = NULL;
3228 cgbr->tab = isl_tab_from_basic_set(dom);
3229 cgbr->tab = isl_tab_init_samples(cgbr->tab);
3232 if (isl_tab_track_bset(cgbr->tab,
3233 isl_basic_set_cow(isl_basic_set_copy(dom))) < 0)
3235 check_gbr_integer_feasible(cgbr);
3237 return &cgbr->context;
3239 cgbr->context.op->free(&cgbr->context);
3243 static struct isl_context *isl_context_alloc(struct isl_basic_set *dom)
3248 if (dom->ctx->opt->context == ISL_CONTEXT_LEXMIN)
3249 return isl_context_lex_alloc(dom);
3251 return isl_context_gbr_alloc(dom);
3254 /* Construct an isl_sol_map structure for accumulating the solution.
3255 * If track_empty is set, then we also keep track of the parts
3256 * of the context where there is no solution.
3257 * If max is set, then we are solving a maximization, rather than
3258 * a minimization problem, which means that the variables in the
3259 * tableau have value "M - x" rather than "M + x".
3261 static struct isl_sol_map *sol_map_init(struct isl_basic_map *bmap,
3262 struct isl_basic_set *dom, int track_empty, int max)
3264 struct isl_sol_map *sol_map = NULL;
3269 sol_map = isl_calloc_type(bmap->ctx, struct isl_sol_map);
3273 sol_map->sol.rational = ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL);
3274 sol_map->sol.dec_level.callback.run = &sol_dec_level_wrap;
3275 sol_map->sol.dec_level.sol = &sol_map->sol;
3276 sol_map->sol.max = max;
3277 sol_map->sol.n_out = isl_basic_map_dim(bmap, isl_dim_out);
3278 sol_map->sol.add = &sol_map_add_wrap;
3279 sol_map->sol.add_empty = track_empty ? &sol_map_add_empty_wrap : NULL;
3280 sol_map->sol.free = &sol_map_free_wrap;
3281 sol_map->map = isl_map_alloc_dim(isl_basic_map_get_dim(bmap), 1,
3286 sol_map->sol.context = isl_context_alloc(dom);
3287 if (!sol_map->sol.context)
3291 sol_map->empty = isl_set_alloc_dim(isl_basic_set_get_dim(dom),
3292 1, ISL_SET_DISJOINT);
3293 if (!sol_map->empty)
3297 isl_basic_set_free(dom);
3300 isl_basic_set_free(dom);
3301 sol_map_free(sol_map);
3305 /* Check whether all coefficients of (non-parameter) variables
3306 * are non-positive, meaning that no pivots can be performed on the row.
3308 static int is_critical(struct isl_tab *tab, int row)
3311 unsigned off = 2 + tab->M;
3313 for (j = tab->n_dead; j < tab->n_col; ++j) {
3314 if (tab->col_var[j] >= 0 &&
3315 (tab->col_var[j] < tab->n_param ||
3316 tab->col_var[j] >= tab->n_var - tab->n_div))
3319 if (isl_int_is_pos(tab->mat->row[row][off + j]))
3326 /* Check whether the inequality represented by vec is strict over the integers,
3327 * i.e., there are no integer values satisfying the constraint with
3328 * equality. This happens if the gcd of the coefficients is not a divisor
3329 * of the constant term. If so, scale the constraint down by the gcd
3330 * of the coefficients.
3332 static int is_strict(struct isl_vec *vec)
3338 isl_seq_gcd(vec->el + 1, vec->size - 1, &gcd);
3339 if (!isl_int_is_one(gcd)) {
3340 strict = !isl_int_is_divisible_by(vec->el[0], gcd);
3341 isl_int_fdiv_q(vec->el[0], vec->el[0], gcd);
3342 isl_seq_scale_down(vec->el + 1, vec->el + 1, gcd, vec->size-1);
3349 /* Determine the sign of the given row of the main tableau.
3350 * The result is one of
3351 * isl_tab_row_pos: always non-negative; no pivot needed
3352 * isl_tab_row_neg: always non-positive; pivot
3353 * isl_tab_row_any: can be both positive and negative; split
3355 * We first handle some simple cases
3356 * - the row sign may be known already
3357 * - the row may be obviously non-negative
3358 * - the parametric constant may be equal to that of another row
3359 * for which we know the sign. This sign will be either "pos" or
3360 * "any". If it had been "neg" then we would have pivoted before.
3362 * If none of these cases hold, we check the value of the row for each
3363 * of the currently active samples. Based on the signs of these values
3364 * we make an initial determination of the sign of the row.
3366 * all zero -> unk(nown)
3367 * all non-negative -> pos
3368 * all non-positive -> neg
3369 * both negative and positive -> all
3371 * If we end up with "all", we are done.
3372 * Otherwise, we perform a check for positive and/or negative
3373 * values as follows.
3375 * samples neg unk pos
3381 * There is no special sign for "zero", because we can usually treat zero
3382 * as either non-negative or non-positive, whatever works out best.
3383 * However, if the row is "critical", meaning that pivoting is impossible
3384 * then we don't want to limp zero with the non-positive case, because
3385 * then we we would lose the solution for those values of the parameters
3386 * where the value of the row is zero. Instead, we treat 0 as non-negative
3387 * ensuring a split if the row can attain both zero and negative values.
3388 * The same happens when the original constraint was one that could not
3389 * be satisfied with equality by any integer values of the parameters.
3390 * In this case, we normalize the constraint, but then a value of zero
3391 * for the normalized constraint is actually a positive value for the
3392 * original constraint, so again we need to treat zero as non-negative.
3393 * In both these cases, we have the following decision tree instead:
3395 * all non-negative -> pos
3396 * all negative -> neg
3397 * both negative and non-negative -> all
3405 static enum isl_tab_row_sign row_sign(struct isl_tab *tab,
3406 struct isl_sol *sol, int row)
3408 struct isl_vec *ineq = NULL;
3409 enum isl_tab_row_sign res = isl_tab_row_unknown;
3414 if (tab->row_sign[row] != isl_tab_row_unknown)
3415 return tab->row_sign[row];
3416 if (is_obviously_nonneg(tab, row))
3417 return isl_tab_row_pos;
3418 for (row2 = tab->n_redundant; row2 < tab->n_row; ++row2) {
3419 if (tab->row_sign[row2] == isl_tab_row_unknown)
3421 if (identical_parameter_line(tab, row, row2))
3422 return tab->row_sign[row2];
3425 critical = is_critical(tab, row);
3427 ineq = get_row_parameter_ineq(tab, row);
3431 strict = is_strict(ineq);
3433 res = sol->context->op->ineq_sign(sol->context, ineq->el,
3434 critical || strict);
3436 if (res == isl_tab_row_unknown || res == isl_tab_row_pos) {
3437 /* test for negative values */
3439 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3440 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3442 feasible = sol->context->op->test_ineq(sol->context, ineq->el);
3446 res = isl_tab_row_pos;
3448 res = (res == isl_tab_row_unknown) ? isl_tab_row_neg
3450 if (res == isl_tab_row_neg) {
3451 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3452 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3456 if (res == isl_tab_row_neg) {
3457 /* test for positive values */
3459 if (!critical && !strict)
3460 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3462 feasible = sol->context->op->test_ineq(sol->context, ineq->el);
3466 res = isl_tab_row_any;
3473 return isl_tab_row_unknown;
3476 static void find_solutions(struct isl_sol *sol, struct isl_tab *tab);
3478 /* Find solutions for values of the parameters that satisfy the given
3481 * We currently take a snapshot of the context tableau that is reset
3482 * when we return from this function, while we make a copy of the main
3483 * tableau, leaving the original main tableau untouched.
3484 * These are fairly arbitrary choices. Making a copy also of the context
3485 * tableau would obviate the need to undo any changes made to it later,
3486 * while taking a snapshot of the main tableau could reduce memory usage.
3487 * If we were to switch to taking a snapshot of the main tableau,
3488 * we would have to keep in mind that we need to save the row signs
3489 * and that we need to do this before saving the current basis
3490 * such that the basis has been restore before we restore the row signs.
3492 static void find_in_pos(struct isl_sol *sol, struct isl_tab *tab, isl_int *ineq)
3498 saved = sol->context->op->save(sol->context);
3500 tab = isl_tab_dup(tab);
3504 sol->context->op->add_ineq(sol->context, ineq, 0, 1);
3506 find_solutions(sol, tab);
3509 sol->context->op->restore(sol->context, saved);
3515 /* Record the absence of solutions for those values of the parameters
3516 * that do not satisfy the given inequality with equality.
3518 static void no_sol_in_strict(struct isl_sol *sol,
3519 struct isl_tab *tab, struct isl_vec *ineq)
3524 if (!sol->context || sol->error)
3526 saved = sol->context->op->save(sol->context);
3528 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3530 sol->context->op->add_ineq(sol->context, ineq->el, 1, 0);
3539 isl_int_add_ui(ineq->el[0], ineq->el[0], 1);
3541 sol->context->op->restore(sol->context, saved);
3547 /* Compute the lexicographic minimum of the set represented by the main
3548 * tableau "tab" within the context "sol->context_tab".
3549 * On entry the sample value of the main tableau is lexicographically
3550 * less than or equal to this lexicographic minimum.
3551 * Pivots are performed until a feasible point is found, which is then
3552 * necessarily equal to the minimum, or until the tableau is found to
3553 * be infeasible. Some pivots may need to be performed for only some
3554 * feasible values of the context tableau. If so, the context tableau
3555 * is split into a part where the pivot is needed and a part where it is not.
3557 * Whenever we enter the main loop, the main tableau is such that no
3558 * "obvious" pivots need to be performed on it, where "obvious" means
3559 * that the given row can be seen to be negative without looking at
3560 * the context tableau. In particular, for non-parametric problems,
3561 * no pivots need to be performed on the main tableau.
3562 * The caller of find_solutions is responsible for making this property
3563 * hold prior to the first iteration of the loop, while restore_lexmin
3564 * is called before every other iteration.
3566 * Inside the main loop, we first examine the signs of the rows of
3567 * the main tableau within the context of the context tableau.
3568 * If we find a row that is always non-positive for all values of
3569 * the parameters satisfying the context tableau and negative for at
3570 * least one value of the parameters, we perform the appropriate pivot
3571 * and start over. An exception is the case where no pivot can be
3572 * performed on the row. In this case, we require that the sign of
3573 * the row is negative for all values of the parameters (rather than just
3574 * non-positive). This special case is handled inside row_sign, which
3575 * will say that the row can have any sign if it determines that it can
3576 * attain both negative and zero values.
3578 * If we can't find a row that always requires a pivot, but we can find
3579 * one or more rows that require a pivot for some values of the parameters
3580 * (i.e., the row can attain both positive and negative signs), then we split
3581 * the context tableau into two parts, one where we force the sign to be
3582 * non-negative and one where we force is to be negative.
3583 * The non-negative part is handled by a recursive call (through find_in_pos).
3584 * Upon returning from this call, we continue with the negative part and
3585 * perform the required pivot.
3587 * If no such rows can be found, all rows are non-negative and we have
3588 * found a (rational) feasible point. If we only wanted a rational point
3590 * Otherwise, we check if all values of the sample point of the tableau
3591 * are integral for the variables. If so, we have found the minimal
3592 * integral point and we are done.
3593 * If the sample point is not integral, then we need to make a distinction
3594 * based on whether the constant term is non-integral or the coefficients
3595 * of the parameters. Furthermore, in order to decide how to handle
3596 * the non-integrality, we also need to know whether the coefficients
3597 * of the other columns in the tableau are integral. This leads
3598 * to the following table. The first two rows do not correspond
3599 * to a non-integral sample point and are only mentioned for completeness.
3601 * constant parameters other
3604 * int int rat | -> no problem
3606 * rat int int -> fail
3608 * rat int rat -> cut
3611 * rat rat rat | -> parametric cut
3614 * rat rat int | -> split context
3616 * If the parametric constant is completely integral, then there is nothing
3617 * to be done. If the constant term is non-integral, but all the other
3618 * coefficient are integral, then there is nothing that can be done
3619 * and the tableau has no integral solution.
3620 * If, on the other hand, one or more of the other columns have rational
3621 * coefficients, but the parameter coefficients are all integral, then
3622 * we can perform a regular (non-parametric) cut.
3623 * Finally, if there is any parameter coefficient that is non-integral,
3624 * then we need to involve the context tableau. There are two cases here.
3625 * If at least one other column has a rational coefficient, then we
3626 * can perform a parametric cut in the main tableau by adding a new
3627 * integer division in the context tableau.
3628 * If all other columns have integral coefficients, then we need to
3629 * enforce that the rational combination of parameters (c + \sum a_i y_i)/m
3630 * is always integral. We do this by introducing an integer division
3631 * q = floor((c + \sum a_i y_i)/m) and stipulating that its argument should
3632 * always be integral in the context tableau, i.e., m q = c + \sum a_i y_i.
3633 * Since q is expressed in the tableau as
3634 * c + \sum a_i y_i - m q >= 0
3635 * -c - \sum a_i y_i + m q + m - 1 >= 0
3636 * it is sufficient to add the inequality
3637 * -c - \sum a_i y_i + m q >= 0
3638 * In the part of the context where this inequality does not hold, the
3639 * main tableau is marked as being empty.
3641 static void find_solutions(struct isl_sol *sol, struct isl_tab *tab)
3643 struct isl_context *context;
3646 if (!tab || sol->error)
3649 context = sol->context;
3653 if (context->op->is_empty(context))
3656 for (r = 0; r >= 0 && tab && !tab->empty; r = restore_lexmin(tab)) {
3659 enum isl_tab_row_sign sgn;
3663 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3664 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
3666 sgn = row_sign(tab, sol, row);
3669 tab->row_sign[row] = sgn;
3670 if (sgn == isl_tab_row_any)
3672 if (sgn == isl_tab_row_any && split == -1)
3674 if (sgn == isl_tab_row_neg)
3677 if (row < tab->n_row)
3680 struct isl_vec *ineq;
3682 split = context->op->best_split(context, tab);
3685 ineq = get_row_parameter_ineq(tab, split);
3689 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3690 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
3692 if (tab->row_sign[row] == isl_tab_row_any)
3693 tab->row_sign[row] = isl_tab_row_unknown;
3695 tab->row_sign[split] = isl_tab_row_pos;
3697 find_in_pos(sol, tab, ineq->el);
3698 tab->row_sign[split] = isl_tab_row_neg;
3700 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3701 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3703 context->op->add_ineq(context, ineq->el, 0, 1);
3711 row = first_non_integer_row(tab, &flags);
3714 if (ISL_FL_ISSET(flags, I_PAR)) {
3715 if (ISL_FL_ISSET(flags, I_VAR)) {
3716 if (isl_tab_mark_empty(tab) < 0)
3720 row = add_cut(tab, row);
3721 } else if (ISL_FL_ISSET(flags, I_VAR)) {
3722 struct isl_vec *div;
3723 struct isl_vec *ineq;
3725 div = get_row_split_div(tab, row);
3728 d = context->op->get_div(context, tab, div);
3732 ineq = ineq_for_div(context->op->peek_basic_set(context), d);
3736 no_sol_in_strict(sol, tab, ineq);
3737 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3738 context->op->add_ineq(context, ineq->el, 1, 1);
3740 if (sol->error || !context->op->is_ok(context))
3742 tab = set_row_cst_to_div(tab, row, d);
3743 if (context->op->is_empty(context))
3746 row = add_parametric_cut(tab, row, context);
3761 /* Compute the lexicographic minimum of the set represented by the main
3762 * tableau "tab" within the context "sol->context_tab".
3764 * As a preprocessing step, we first transfer all the purely parametric
3765 * equalities from the main tableau to the context tableau, i.e.,
3766 * parameters that have been pivoted to a row.
3767 * These equalities are ignored by the main algorithm, because the
3768 * corresponding rows may not be marked as being non-negative.
3769 * In parts of the context where the added equality does not hold,
3770 * the main tableau is marked as being empty.
3772 static void find_solutions_main(struct isl_sol *sol, struct isl_tab *tab)
3781 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3785 if (tab->row_var[row] < 0)
3787 if (tab->row_var[row] >= tab->n_param &&
3788 tab->row_var[row] < tab->n_var - tab->n_div)
3790 if (tab->row_var[row] < tab->n_param)
3791 p = tab->row_var[row];
3793 p = tab->row_var[row]
3794 + tab->n_param - (tab->n_var - tab->n_div);
3796 eq = isl_vec_alloc(tab->mat->ctx, 1+tab->n_param+tab->n_div);
3799 get_row_parameter_line(tab, row, eq->el);
3800 isl_int_neg(eq->el[1 + p], tab->mat->row[row][0]);
3801 eq = isl_vec_normalize(eq);
3804 no_sol_in_strict(sol, tab, eq);
3806 isl_seq_neg(eq->el, eq->el, eq->size);
3808 no_sol_in_strict(sol, tab, eq);
3809 isl_seq_neg(eq->el, eq->el, eq->size);
3811 sol->context->op->add_eq(sol->context, eq->el, 1, 1);
3815 if (isl_tab_mark_redundant(tab, row) < 0)
3818 if (sol->context->op->is_empty(sol->context))
3821 row = tab->n_redundant - 1;
3824 find_solutions(sol, tab);
3835 static void sol_map_find_solutions(struct isl_sol_map *sol_map,
3836 struct isl_tab *tab)
3838 find_solutions_main(&sol_map->sol, tab);
3841 /* Check if integer division "div" of "dom" also occurs in "bmap".
3842 * If so, return its position within the divs.
3843 * If not, return -1.
3845 static int find_context_div(struct isl_basic_map *bmap,
3846 struct isl_basic_set *dom, unsigned div)
3849 unsigned b_dim = isl_dim_total(bmap->dim);
3850 unsigned d_dim = isl_dim_total(dom->dim);
3852 if (isl_int_is_zero(dom->div[div][0]))
3854 if (isl_seq_first_non_zero(dom->div[div] + 2 + d_dim, dom->n_div) != -1)
3857 for (i = 0; i < bmap->n_div; ++i) {
3858 if (isl_int_is_zero(bmap->div[i][0]))
3860 if (isl_seq_first_non_zero(bmap->div[i] + 2 + d_dim,
3861 (b_dim - d_dim) + bmap->n_div) != -1)
3863 if (isl_seq_eq(bmap->div[i], dom->div[div], 2 + d_dim))
3869 /* The correspondence between the variables in the main tableau,
3870 * the context tableau, and the input map and domain is as follows.
3871 * The first n_param and the last n_div variables of the main tableau
3872 * form the variables of the context tableau.
3873 * In the basic map, these n_param variables correspond to the
3874 * parameters and the input dimensions. In the domain, they correspond
3875 * to the parameters and the set dimensions.
3876 * The n_div variables correspond to the integer divisions in the domain.
3877 * To ensure that everything lines up, we may need to copy some of the
3878 * integer divisions of the domain to the map. These have to be placed
3879 * in the same order as those in the context and they have to be placed
3880 * after any other integer divisions that the map may have.
3881 * This function performs the required reordering.
3883 static struct isl_basic_map *align_context_divs(struct isl_basic_map *bmap,
3884 struct isl_basic_set *dom)
3890 for (i = 0; i < dom->n_div; ++i)
3891 if (find_context_div(bmap, dom, i) != -1)
3893 other = bmap->n_div - common;
3894 if (dom->n_div - common > 0) {
3895 bmap = isl_basic_map_extend_dim(bmap, isl_dim_copy(bmap->dim),
3896 dom->n_div - common, 0, 0);
3900 for (i = 0; i < dom->n_div; ++i) {
3901 int pos = find_context_div(bmap, dom, i);
3903 pos = isl_basic_map_alloc_div(bmap);
3906 isl_int_set_si(bmap->div[pos][0], 0);
3908 if (pos != other + i)
3909 isl_basic_map_swap_div(bmap, pos, other + i);
3913 isl_basic_map_free(bmap);
3917 /* Base case of isl_tab_basic_map_partial_lexopt, after removing
3918 * some obvious symmetries.
3920 * We make sure the divs in the domain are properly ordered,
3921 * because they will be added one by one in the given order
3922 * during the construction of the solution map.
3924 static __isl_give isl_map *basic_map_partial_lexopt_base(
3925 __isl_take isl_basic_map *bmap, __isl_take isl_basic_set *dom,
3926 __isl_give isl_set **empty, int max)
3928 isl_map *result = NULL;
3929 struct isl_tab *tab;
3930 struct isl_sol_map *sol_map = NULL;
3931 struct isl_context *context;
3934 dom = isl_basic_set_order_divs(dom);
3935 bmap = align_context_divs(bmap, dom);
3937 sol_map = sol_map_init(bmap, dom, !!empty, max);
3941 context = sol_map->sol.context;
3942 if (isl_basic_set_fast_is_empty(context->op->peek_basic_set(context)))
3944 else if (isl_basic_map_fast_is_empty(bmap))
3945 sol_map_add_empty_if_needed(sol_map,
3946 isl_basic_set_copy(context->op->peek_basic_set(context)));
3948 tab = tab_for_lexmin(bmap,
3949 context->op->peek_basic_set(context), 1, max);
3950 tab = context->op->detect_nonnegative_parameters(context, tab);
3951 sol_map_find_solutions(sol_map, tab);
3953 if (sol_map->sol.error)
3956 result = isl_map_copy(sol_map->map);
3958 *empty = isl_set_copy(sol_map->empty);
3959 sol_free(&sol_map->sol);
3960 isl_basic_map_free(bmap);
3963 sol_free(&sol_map->sol);
3964 isl_basic_map_free(bmap);
3968 /* Structure used during detection of parallel constraints.
3969 * n_in: number of "input" variables: isl_dim_param + isl_dim_in
3970 * n_out: number of "output" variables: isl_dim_out + isl_dim_div
3971 * val: the coefficients of the output variables
3973 struct isl_constraint_equal_info {
3974 isl_basic_map *bmap;
3980 /* Check whether the coefficients of the output variables
3981 * of the constraint in "entry" are equal to info->val.
3983 static int constraint_equal(const void *entry, const void *val)
3985 isl_int **row = (isl_int **)entry;
3986 const struct isl_constraint_equal_info *info = val;
3988 return isl_seq_eq((*row) + 1 + info->n_in, info->val, info->n_out);
3991 /* Check whether "bmap" has a pair of constraints that have
3992 * the same coefficients for the output variables.
3993 * Note that the coefficients of the existentially quantified
3994 * variables need to be zero since the existentially quantified
3995 * of the result are usually not the same as those of the input.
3996 * the isl_dim_out and isl_dim_div dimensions.
3997 * If so, return 1 and return the row indices of the two constraints
3998 * in *first and *second.
4000 static int parallel_constraints(__isl_keep isl_basic_map *bmap,
4001 int *first, int *second)
4004 isl_ctx *ctx = isl_basic_map_get_ctx(bmap);
4005 struct isl_hash_table *table = NULL;
4006 struct isl_hash_table_entry *entry;
4007 struct isl_constraint_equal_info info;
4011 ctx = isl_basic_map_get_ctx(bmap);
4012 table = isl_hash_table_alloc(ctx, bmap->n_ineq);
4016 info.n_in = isl_basic_map_dim(bmap, isl_dim_param) +
4017 isl_basic_map_dim(bmap, isl_dim_in);
4019 n_out = isl_basic_map_dim(bmap, isl_dim_out);
4020 n_div = isl_basic_map_dim(bmap, isl_dim_div);
4021 info.n_out = n_out + n_div;
4022 for (i = 0; i < bmap->n_ineq; ++i) {
4025 info.val = bmap->ineq[i] + 1 + info.n_in;
4026 if (isl_seq_first_non_zero(info.val, n_out) < 0)
4028 if (isl_seq_first_non_zero(info.val + n_out, n_div) >= 0)
4030 hash = isl_seq_get_hash(info.val, info.n_out);
4031 entry = isl_hash_table_find(ctx, table, hash,
4032 constraint_equal, &info, 1);
4037 entry->data = &bmap->ineq[i];
4040 if (i < bmap->n_ineq) {
4041 *first = ((isl_int **)entry->data) - bmap->ineq;
4045 isl_hash_table_free(ctx, table);
4047 return i < bmap->n_ineq;
4049 isl_hash_table_free(ctx, table);
4053 /* Given a set of upper bounds on the last "input" variable m,
4054 * construct a set that assigns the minimal upper bound to m, i.e.,
4055 * construct a set that divides the space into cells where one
4056 * of the upper bounds is smaller than all the others and assign
4057 * this upper bound to m.
4059 * In particular, if there are n bounds b_i, then the result
4060 * consists of n basic sets, each one of the form
4063 * b_i <= b_j for j > i
4064 * b_i < b_j for j < i
4066 static __isl_give isl_set *set_minimum(__isl_take isl_dim *dim,
4067 __isl_take isl_mat *var)
4070 isl_basic_set *bset = NULL;
4072 isl_set *set = NULL;
4077 ctx = isl_dim_get_ctx(dim);
4078 set = isl_set_alloc_dim(isl_dim_copy(dim),
4079 var->n_row, ISL_SET_DISJOINT);
4081 for (i = 0; i < var->n_row; ++i) {
4082 bset = isl_basic_set_alloc_dim(isl_dim_copy(dim), 0,
4084 k = isl_basic_set_alloc_equality(bset);
4087 isl_seq_cpy(bset->eq[k], var->row[i], var->n_col);
4088 isl_int_set_si(bset->eq[k][var->n_col], -1);
4089 for (j = 0; j < var->n_row; ++j) {
4092 k = isl_basic_set_alloc_inequality(bset);
4095 isl_seq_combine(bset->ineq[k], ctx->one, var->row[j],
4096 ctx->negone, var->row[i],
4098 isl_int_set_si(bset->ineq[k][var->n_col], 0);
4100 isl_int_sub_ui(bset->ineq[k][0],
4101 bset->ineq[k][0], 1);
4103 bset = isl_basic_set_finalize(bset);
4104 set = isl_set_add_basic_set(set, bset);
4111 isl_basic_set_free(bset);
4118 /* Given that the last input variable of "bmap" represents the minimum
4119 * of the bounds in "cst", check whether we need to split the domain
4120 * based on which bound attains the minimum.
4122 * A split is needed when the minimum appears in an integer division
4123 * or in an equality. Otherwise, it is only needed if it appears in
4124 * an upper bound that is different from the upper bounds on which it
4127 static int need_split_map(__isl_keep isl_basic_map *bmap,
4128 __isl_keep isl_mat *cst)
4134 pos = cst->n_col - 1;
4135 total = isl_basic_map_dim(bmap, isl_dim_all);
4137 for (i = 0; i < bmap->n_div; ++i)
4138 if (!isl_int_is_zero(bmap->div[i][2 + pos]))
4141 for (i = 0; i < bmap->n_eq; ++i)
4142 if (!isl_int_is_zero(bmap->eq[i][1 + pos]))
4145 for (i = 0; i < bmap->n_ineq; ++i) {
4146 if (isl_int_is_nonneg(bmap->ineq[i][1 + pos]))
4148 if (!isl_int_is_negone(bmap->ineq[i][1 + pos]))
4150 if (isl_seq_first_non_zero(bmap->ineq[i] + 1 + pos + 1,
4151 total - pos - 1) >= 0)
4154 for (j = 0; j < cst->n_row; ++j)
4155 if (isl_seq_eq(bmap->ineq[i], cst->row[j], cst->n_col))
4157 if (j >= cst->n_row)
4164 static int need_split_set(__isl_keep isl_basic_set *bset,
4165 __isl_keep isl_mat *cst)
4167 return need_split_map((isl_basic_map *)bset, cst);
4170 /* Given a set of which the last set variable is the minimum
4171 * of the bounds in "cst", split each basic set in the set
4172 * in pieces where one of the bounds is (strictly) smaller than the others.
4173 * This subdivision is given in "min_expr".
4174 * The variable is subsequently projected out.
4176 * We only do the split when it is needed.
4177 * For example if the last input variable m = min(a,b) and the only
4178 * constraints in the given basic set are lower bounds on m,
4179 * i.e., l <= m = min(a,b), then we can simply project out m
4180 * to obtain l <= a and l <= b, without having to split on whether
4181 * m is equal to a or b.
4183 static __isl_give isl_set *split(__isl_take isl_set *empty,
4184 __isl_take isl_set *min_expr, __isl_take isl_mat *cst)
4191 if (!empty || !min_expr || !cst)
4194 n_in = isl_set_dim(empty, isl_dim_set);
4195 dim = isl_set_get_dim(empty);
4196 dim = isl_dim_drop(dim, isl_dim_set, n_in - 1, 1);
4197 res = isl_set_empty(dim);
4199 for (i = 0; i < empty->n; ++i) {
4202 set = isl_set_from_basic_set(isl_basic_set_copy(empty->p[i]));
4203 if (need_split_set(empty->p[i], cst))
4204 set = isl_set_intersect(set, isl_set_copy(min_expr));
4205 set = isl_set_remove_dims(set, isl_dim_set, n_in - 1, 1);
4207 res = isl_set_union_disjoint(res, set);
4210 isl_set_free(empty);
4211 isl_set_free(min_expr);
4215 isl_set_free(empty);
4216 isl_set_free(min_expr);
4221 /* Given a map of which the last input variable is the minimum
4222 * of the bounds in "cst", split each basic set in the set
4223 * in pieces where one of the bounds is (strictly) smaller than the others.
4224 * This subdivision is given in "min_expr".
4225 * The variable is subsequently projected out.
4227 * The implementation is essentially the same as that of "split".
4229 static __isl_give isl_map *split_domain(__isl_take isl_map *opt,
4230 __isl_take isl_set *min_expr, __isl_take isl_mat *cst)
4237 if (!opt || !min_expr || !cst)
4240 n_in = isl_map_dim(opt, isl_dim_in);
4241 dim = isl_map_get_dim(opt);
4242 dim = isl_dim_drop(dim, isl_dim_in, n_in - 1, 1);
4243 res = isl_map_empty(dim);
4245 for (i = 0; i < opt->n; ++i) {
4248 map = isl_map_from_basic_map(isl_basic_map_copy(opt->p[i]));
4249 if (need_split_map(opt->p[i], cst))
4250 map = isl_map_intersect_domain(map,
4251 isl_set_copy(min_expr));
4252 map = isl_map_remove_dims(map, isl_dim_in, n_in - 1, 1);
4254 res = isl_map_union_disjoint(res, map);
4258 isl_set_free(min_expr);
4263 isl_set_free(min_expr);
4268 static __isl_give isl_map *basic_map_partial_lexopt(
4269 __isl_take isl_basic_map *bmap, __isl_take isl_basic_set *dom,
4270 __isl_give isl_set **empty, int max);
4272 /* Given a basic map with at least two parallel constraints (as found
4273 * by the function parallel_constraints), first look for more constraints
4274 * parallel to the two constraint and replace the found list of parallel
4275 * constraints by a single constraint with as "input" part the minimum
4276 * of the input parts of the list of constraints. Then, recursively call
4277 * basic_map_partial_lexopt (possibly finding more parallel constraints)
4278 * and plug in the definition of the minimum in the result.
4280 * More specifically, given a set of constraints
4284 * Replace this set by a single constraint
4288 * with u a new parameter with constraints
4292 * Any solution to the new system is also a solution for the original system
4295 * a x >= -u >= -b_i(p)
4297 * Moreover, m = min_i(b_i(p)) satisfies the constraints on u and can
4298 * therefore be plugged into the solution.
4300 static __isl_give isl_map *basic_map_partial_lexopt_symm(
4301 __isl_take isl_basic_map *bmap, __isl_take isl_basic_set *dom,
4302 __isl_give isl_set **empty, int max, int first, int second)
4306 unsigned n_in, n_out, n_div;
4308 isl_vec *var = NULL;
4309 isl_mat *cst = NULL;
4312 isl_dim *map_dim, *set_dim;
4314 map_dim = isl_basic_map_get_dim(bmap);
4315 set_dim = empty ? isl_basic_set_get_dim(dom) : NULL;
4317 n_in = isl_basic_map_dim(bmap, isl_dim_param) +
4318 isl_basic_map_dim(bmap, isl_dim_in);
4319 n_out = isl_basic_map_dim(bmap, isl_dim_all) - n_in;
4321 ctx = isl_basic_map_get_ctx(bmap);
4322 list = isl_alloc_array(ctx, int, bmap->n_ineq);
4323 var = isl_vec_alloc(ctx, n_out);
4329 isl_seq_cpy(var->el, bmap->ineq[first] + 1 + n_in, n_out);
4330 for (i = second + 1, n = 2; i < bmap->n_ineq; ++i) {
4331 if (isl_seq_eq(var->el, bmap->ineq[i] + 1 + n_in, n_out))
4335 cst = isl_mat_alloc(ctx, n, 1 + n_in);
4339 for (i = 0; i < n; ++i)
4340 isl_seq_cpy(cst->row[i], bmap->ineq[list[i]], 1 + n_in);
4342 bmap = isl_basic_map_cow(bmap);
4345 for (i = n - 1; i >= 0; --i)
4346 if (isl_basic_map_drop_inequality(bmap, list[i]) < 0)
4349 bmap = isl_basic_map_add(bmap, isl_dim_in, 1);
4350 bmap = isl_basic_map_extend_constraints(bmap, 0, 1);
4351 k = isl_basic_map_alloc_inequality(bmap);
4354 isl_seq_clr(bmap->ineq[k], 1 + n_in);
4355 isl_int_set_si(bmap->ineq[k][1 + n_in], 1);
4356 isl_seq_cpy(bmap->ineq[k] + 1 + n_in + 1, var->el, n_out);
4357 bmap = isl_basic_map_finalize(bmap);
4359 n_div = isl_basic_set_dim(dom, isl_dim_div);
4360 dom = isl_basic_set_add(dom, isl_dim_set, 1);
4361 dom = isl_basic_set_extend_constraints(dom, 0, n);
4362 for (i = 0; i < n; ++i) {
4363 k = isl_basic_set_alloc_inequality(dom);
4366 isl_seq_cpy(dom->ineq[k], cst->row[i], 1 + n_in);
4367 isl_int_set_si(dom->ineq[k][1 + n_in], -1);
4368 isl_seq_clr(dom->ineq[k] + 1 + n_in + 1, n_div);
4371 min_expr = set_minimum(isl_basic_set_get_dim(dom), isl_mat_copy(cst));
4376 opt = basic_map_partial_lexopt(bmap, dom, empty, max);
4379 *empty = split(*empty,
4380 isl_set_copy(min_expr), isl_mat_copy(cst));
4381 *empty = isl_set_reset_dim(*empty, set_dim);
4384 opt = split_domain(opt, min_expr, cst);
4385 opt = isl_map_reset_dim(opt, map_dim);
4389 isl_dim_free(map_dim);
4390 isl_dim_free(set_dim);
4394 isl_basic_set_free(dom);
4395 isl_basic_map_free(bmap);
4399 /* Recursive part of isl_tab_basic_map_partial_lexopt, after detecting
4400 * equalities and removing redundant constraints.
4402 * We first check if there are any parallel constraints (left).
4403 * If not, we are in the base case.
4404 * If there are parallel constraints, we replace them by a single
4405 * constraint in basic_map_partial_lexopt_symm and then call
4406 * this function recursively to look for more parallel constraints.
4408 static __isl_give isl_map *basic_map_partial_lexopt(
4409 __isl_take isl_basic_map *bmap, __isl_take isl_basic_set *dom,
4410 __isl_give isl_set **empty, int max)
4418 if (bmap->ctx->opt->pip_symmetry)
4419 par = parallel_constraints(bmap, &first, &second);
4423 return basic_map_partial_lexopt_base(bmap, dom, empty, max);
4425 return basic_map_partial_lexopt_symm(bmap, dom, empty, max,
4428 isl_basic_set_free(dom);
4429 isl_basic_map_free(bmap);
4433 /* Compute the lexicographic minimum (or maximum if "max" is set)
4434 * of "bmap" over the domain "dom" and return the result as a map.
4435 * If "empty" is not NULL, then *empty is assigned a set that
4436 * contains those parts of the domain where there is no solution.
4437 * If "bmap" is marked as rational (ISL_BASIC_MAP_RATIONAL),
4438 * then we compute the rational optimum. Otherwise, we compute
4439 * the integral optimum.
4441 * We perform some preprocessing. As the PILP solver does not
4442 * handle implicit equalities very well, we first make sure all
4443 * the equalities are explicitly available.
4445 * We also add context constraints to the basic map and remove
4446 * redundant constraints. This is only needed because of the
4447 * way we handle simple symmetries. In particular, we currently look
4448 * for symmetries on the constraints, before we set up the main tableau.
4449 * It is then no good to look for symmetries on possibly redundant constraints.
4451 struct isl_map *isl_tab_basic_map_partial_lexopt(
4452 struct isl_basic_map *bmap, struct isl_basic_set *dom,
4453 struct isl_set **empty, int max)
4460 isl_assert(bmap->ctx,
4461 isl_basic_map_compatible_domain(bmap, dom), goto error);
4463 if (isl_basic_set_dim(dom, isl_dim_all) == 0)
4464 return basic_map_partial_lexopt(bmap, dom, empty, max);
4466 bmap = isl_basic_map_intersect_domain(bmap, isl_basic_set_copy(dom));
4467 bmap = isl_basic_map_detect_equalities(bmap);
4468 bmap = isl_basic_map_remove_redundancies(bmap);
4470 return basic_map_partial_lexopt(bmap, dom, empty, max);
4472 isl_basic_set_free(dom);
4473 isl_basic_map_free(bmap);
4477 struct isl_sol_for {
4479 int (*fn)(__isl_take isl_basic_set *dom,
4480 __isl_take isl_mat *map, void *user);
4484 static void sol_for_free(struct isl_sol_for *sol_for)
4486 if (sol_for->sol.context)
4487 sol_for->sol.context->op->free(sol_for->sol.context);
4491 static void sol_for_free_wrap(struct isl_sol *sol)
4493 sol_for_free((struct isl_sol_for *)sol);
4496 /* Add the solution identified by the tableau and the context tableau.
4498 * See documentation of sol_add for more details.
4500 * Instead of constructing a basic map, this function calls a user
4501 * defined function with the current context as a basic set and
4502 * an affine matrix representing the relation between the input and output.
4503 * The number of rows in this matrix is equal to one plus the number
4504 * of output variables. The number of columns is equal to one plus
4505 * the total dimension of the context, i.e., the number of parameters,
4506 * input variables and divs. Since some of the columns in the matrix
4507 * may refer to the divs, the basic set is not simplified.
4508 * (Simplification may reorder or remove divs.)
4510 static void sol_for_add(struct isl_sol_for *sol,
4511 struct isl_basic_set *dom, struct isl_mat *M)
4513 if (sol->sol.error || !dom || !M)
4516 dom = isl_basic_set_simplify(dom);
4517 dom = isl_basic_set_finalize(dom);
4519 if (sol->fn(isl_basic_set_copy(dom), isl_mat_copy(M), sol->user) < 0)
4522 isl_basic_set_free(dom);
4526 isl_basic_set_free(dom);
4531 static void sol_for_add_wrap(struct isl_sol *sol,
4532 struct isl_basic_set *dom, struct isl_mat *M)
4534 sol_for_add((struct isl_sol_for *)sol, dom, M);
4537 static struct isl_sol_for *sol_for_init(struct isl_basic_map *bmap, int max,
4538 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
4542 struct isl_sol_for *sol_for = NULL;
4543 struct isl_dim *dom_dim;
4544 struct isl_basic_set *dom = NULL;
4546 sol_for = isl_calloc_type(bmap->ctx, struct isl_sol_for);
4550 dom_dim = isl_dim_domain(isl_dim_copy(bmap->dim));
4551 dom = isl_basic_set_universe(dom_dim);
4553 sol_for->sol.rational = ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL);
4554 sol_for->sol.dec_level.callback.run = &sol_dec_level_wrap;
4555 sol_for->sol.dec_level.sol = &sol_for->sol;
4557 sol_for->user = user;
4558 sol_for->sol.max = max;
4559 sol_for->sol.n_out = isl_basic_map_dim(bmap, isl_dim_out);
4560 sol_for->sol.add = &sol_for_add_wrap;
4561 sol_for->sol.add_empty = NULL;
4562 sol_for->sol.free = &sol_for_free_wrap;
4564 sol_for->sol.context = isl_context_alloc(dom);
4565 if (!sol_for->sol.context)
4568 isl_basic_set_free(dom);
4571 isl_basic_set_free(dom);
4572 sol_for_free(sol_for);
4576 static void sol_for_find_solutions(struct isl_sol_for *sol_for,
4577 struct isl_tab *tab)
4579 find_solutions_main(&sol_for->sol, tab);
4582 int isl_basic_map_foreach_lexopt(__isl_keep isl_basic_map *bmap, int max,
4583 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
4587 struct isl_sol_for *sol_for = NULL;
4589 bmap = isl_basic_map_copy(bmap);
4593 bmap = isl_basic_map_detect_equalities(bmap);
4594 sol_for = sol_for_init(bmap, max, fn, user);
4596 if (isl_basic_map_fast_is_empty(bmap))
4599 struct isl_tab *tab;
4600 struct isl_context *context = sol_for->sol.context;
4601 tab = tab_for_lexmin(bmap,
4602 context->op->peek_basic_set(context), 1, max);
4603 tab = context->op->detect_nonnegative_parameters(context, tab);
4604 sol_for_find_solutions(sol_for, tab);
4605 if (sol_for->sol.error)
4609 sol_free(&sol_for->sol);
4610 isl_basic_map_free(bmap);
4613 sol_free(&sol_for->sol);
4614 isl_basic_map_free(bmap);
4618 int isl_basic_map_foreach_lexmin(__isl_keep isl_basic_map *bmap,
4619 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
4623 return isl_basic_map_foreach_lexopt(bmap, 0, fn, user);
4626 int isl_basic_map_foreach_lexmax(__isl_keep isl_basic_map *bmap,
4627 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
4631 return isl_basic_map_foreach_lexopt(bmap, 1, fn, user);