1 #include "isl_map_private.h"
4 #include "isl_sample.h"
7 * The implementation of parametric integer linear programming in this file
8 * was inspired by the paper "Parametric Integer Programming" and the
9 * report "Solving systems of affine (in)equalities" by Paul Feautrier
12 * The strategy used for obtaining a feasible solution is different
13 * from the one used in isl_tab.c. In particular, in isl_tab.c,
14 * upon finding a constraint that is not yet satisfied, we pivot
15 * in a row that increases the constant term of row holding the
16 * constraint, making sure the sample solution remains feasible
17 * for all the constraints it already satisfied.
18 * Here, we always pivot in the row holding the constraint,
19 * choosing a column that induces the lexicographically smallest
20 * increment to the sample solution.
22 * By starting out from a sample value that is lexicographically
23 * smaller than any integer point in the problem space, the first
24 * feasible integer sample point we find will also be the lexicographically
25 * smallest. If all variables can be assumed to be non-negative,
26 * then the initial sample value may be chosen equal to zero.
27 * However, we will not make this assumption. Instead, we apply
28 * the "big parameter" trick. Any variable x is then not directly
29 * used in the tableau, but instead it its represented by another
30 * variable x' = M + x, where M is an arbitrarily large (positive)
31 * value. x' is therefore always non-negative, whatever the value of x.
32 * Taking as initial smaple value x' = 0 corresponds to x = -M,
33 * which is always smaller than any possible value of x.
35 * The big parameter trick is used in the main tableau and
36 * also in the context tableau if isl_context_lex is used.
37 * In this case, each tableaus has its own big parameter.
38 * Before doing any real work, we check if all the parameters
39 * happen to be non-negative. If so, we drop the column corresponding
40 * to M from the initial context tableau.
41 * If isl_context_gbr is used, then the big parameter trick is only
42 * used in the main tableau.
46 struct isl_context_op {
47 /* detect nonnegative parameters in context and mark them in tab */
48 struct isl_tab *(*detect_nonnegative_parameters)(
49 struct isl_context *context, struct isl_tab *tab);
50 /* return temporary reference to basic set representation of context */
51 struct isl_basic_set *(*peek_basic_set)(struct isl_context *context);
52 /* return temporary reference to tableau representation of context */
53 struct isl_tab *(*peek_tab)(struct isl_context *context);
54 /* add equality; check is 1 if eq may not be valid;
55 * update is 1 if we may want to call ineq_sign on context later.
57 void (*add_eq)(struct isl_context *context, isl_int *eq,
58 int check, int update);
59 /* add inequality; check is 1 if ineq may not be valid;
60 * update is 1 if we may want to call ineq_sign on context later.
62 void (*add_ineq)(struct isl_context *context, isl_int *ineq,
63 int check, int update);
64 /* check sign of ineq based on previous information.
65 * strict is 1 if saturation should be treated as a positive sign.
67 enum isl_tab_row_sign (*ineq_sign)(struct isl_context *context,
68 isl_int *ineq, int strict);
69 /* check if inequality maintains feasibility */
70 int (*test_ineq)(struct isl_context *context, isl_int *ineq);
71 /* return index of a div that corresponds to "div" */
72 int (*get_div)(struct isl_context *context, struct isl_tab *tab,
74 /* add div "div" to context and return index and non-negativity */
75 int (*add_div)(struct isl_context *context, struct isl_vec *div,
77 int (*detect_equalities)(struct isl_context *context,
79 /* return row index of "best" split */
80 int (*best_split)(struct isl_context *context, struct isl_tab *tab);
81 /* check if context has already been determined to be empty */
82 int (*is_empty)(struct isl_context *context);
83 /* check if context is still usable */
84 int (*is_ok)(struct isl_context *context);
85 /* save a copy/snapshot of context */
86 void *(*save)(struct isl_context *context);
87 /* restore saved context */
88 void (*restore)(struct isl_context *context, void *);
89 /* invalidate context */
90 void (*invalidate)(struct isl_context *context);
92 void (*free)(struct isl_context *context);
96 struct isl_context_op *op;
99 struct isl_context_lex {
100 struct isl_context context;
104 /* isl_sol is an interface for constructing a solution to
105 * a parametric integer linear programming problem.
106 * Every time the algorithm reaches a state where a solution
107 * can be read off from the tableau (including cases where the tableau
108 * is empty), the function "add" is called on the isl_sol passed
109 * to find_solutions_main.
111 * The context tableau is owned by isl_sol and is updated incrementally.
113 * There are currently two implementations of this interface,
114 * isl_sol_map, which simply collects the solutions in an isl_map
115 * and (optionally) the parts of the context where there is no solution
117 * isl_sol_for, which calls a user-defined function for each part of
121 struct isl_context *context;
122 struct isl_sol *(*add)(struct isl_sol *sol, struct isl_tab *tab);
123 void (*free)(struct isl_sol *sol);
126 static void sol_free(struct isl_sol *sol)
136 struct isl_set *empty;
140 static void sol_map_free(struct isl_sol_map *sol_map)
142 if (sol_map->sol.context)
143 sol_map->sol.context->op->free(sol_map->sol.context);
144 isl_map_free(sol_map->map);
145 isl_set_free(sol_map->empty);
149 static void sol_map_free_wrap(struct isl_sol *sol)
151 sol_map_free((struct isl_sol_map *)sol);
154 static struct isl_sol_map *add_empty(struct isl_sol_map *sol)
156 struct isl_basic_set *bset;
160 sol->empty = isl_set_grow(sol->empty, 1);
161 bset = sol->sol.context->op->peek_basic_set(sol->sol.context);
162 bset = isl_basic_set_copy(bset);
163 bset = isl_basic_set_simplify(bset);
164 bset = isl_basic_set_finalize(bset);
165 sol->empty = isl_set_add(sol->empty, bset);
174 /* Add the solution identified by the tableau and the context tableau.
176 * The layout of the variables is as follows.
177 * tab->n_var is equal to the total number of variables in the input
178 * map (including divs that were copied from the context)
179 * + the number of extra divs constructed
180 * Of these, the first tab->n_param and the last tab->n_div variables
181 * correspond to the variables in the context, i.e.,
182 * tab->n_param + tab->n_div = context_tab->n_var
183 * tab->n_param is equal to the number of parameters and input
184 * dimensions in the input map
185 * tab->n_div is equal to the number of divs in the context
187 * If there is no solution, then the basic set corresponding to the
188 * context tableau is added to the set "empty".
190 * Otherwise, a basic map is constructed with the same parameters
191 * and divs as the context, the dimensions of the context as input
192 * dimensions and a number of output dimensions that is equal to
193 * the number of output dimensions in the input map.
194 * The divs in the input map (if any) that do not correspond to any
195 * div in the context do not appear in the solution.
196 * The algorithm will make sure that they have an integer value,
197 * but these values themselves are of no interest.
199 * The constraints and divs of the context are simply copied
200 * fron context_tab->bset.
201 * To extract the value of the output variables, it should be noted
202 * that we always use a big parameter M and so the variable stored
203 * in the tableau is not an output variable x itself, but
204 * x' = M + x (in case of minimization)
206 * x' = M - x (in case of maximization)
207 * If x' appears in a column, then its optimal value is zero,
208 * which means that the optimal value of x is an unbounded number
209 * (-M for minimization and M for maximization).
210 * We currently assume that the output dimensions in the original map
211 * are bounded, so this cannot occur.
212 * Similarly, when x' appears in a row, then the coefficient of M in that
213 * row is necessarily 1.
214 * If the row represents
215 * d x' = c + d M + e(y)
216 * then, in case of minimization, an equality
217 * c + e(y) - d x' = 0
218 * is added, and in case of maximization,
219 * c + e(y) + d x' = 0
221 static struct isl_sol_map *sol_map_add(struct isl_sol_map *sol,
225 struct isl_basic_map *bmap = NULL;
226 isl_basic_set *context_bset;
239 return add_empty(sol);
241 context_bset = sol->sol.context->op->peek_basic_set(sol->sol.context);
243 n_out = isl_map_dim(sol->map, isl_dim_out);
244 n_eq = context_bset->n_eq + n_out;
245 n_ineq = context_bset->n_ineq;
246 nparam = tab->n_param;
247 total = isl_map_dim(sol->map, isl_dim_all);
248 bmap = isl_basic_map_alloc_dim(isl_map_get_dim(sol->map),
249 tab->n_div, n_eq, 2 * tab->n_div + n_ineq);
254 ISL_F_SET(bmap, ISL_BASIC_MAP_RATIONAL);
255 for (i = 0; i < context_bset->n_div; ++i) {
256 int k = isl_basic_map_alloc_div(bmap);
259 isl_seq_cpy(bmap->div[k],
260 context_bset->div[i], 1 + 1 + nparam);
261 isl_seq_clr(bmap->div[k] + 1 + 1 + nparam, total - nparam);
262 isl_seq_cpy(bmap->div[k] + 1 + 1 + total,
263 context_bset->div[i] + 1 + 1 + nparam, i);
265 for (i = 0; i < context_bset->n_eq; ++i) {
266 int k = isl_basic_map_alloc_equality(bmap);
269 isl_seq_cpy(bmap->eq[k], context_bset->eq[i], 1 + nparam);
270 isl_seq_clr(bmap->eq[k] + 1 + nparam, total - nparam);
271 isl_seq_cpy(bmap->eq[k] + 1 + total,
272 context_bset->eq[i] + 1 + nparam, n_div);
274 for (i = 0; i < context_bset->n_ineq; ++i) {
275 int k = isl_basic_map_alloc_inequality(bmap);
278 isl_seq_cpy(bmap->ineq[k],
279 context_bset->ineq[i], 1 + nparam);
280 isl_seq_clr(bmap->ineq[k] + 1 + nparam, total - nparam);
281 isl_seq_cpy(bmap->ineq[k] + 1 + total,
282 context_bset->ineq[i] + 1 + nparam, n_div);
284 for (i = tab->n_param; i < total; ++i) {
285 int k = isl_basic_map_alloc_equality(bmap);
288 isl_seq_clr(bmap->eq[k] + 1, isl_basic_map_total_dim(bmap));
289 if (!tab->var[i].is_row) {
291 isl_assert(bmap->ctx, !tab->M, goto error);
292 isl_int_set_si(bmap->eq[k][0], 0);
294 isl_int_set_si(bmap->eq[k][1 + i], 1);
296 isl_int_set_si(bmap->eq[k][1 + i], -1);
299 row = tab->var[i].index;
302 isl_assert(bmap->ctx,
303 isl_int_eq(tab->mat->row[row][2],
304 tab->mat->row[row][0]),
306 isl_int_set(bmap->eq[k][0], tab->mat->row[row][1]);
307 for (j = 0; j < tab->n_param; ++j) {
309 if (tab->var[j].is_row)
311 col = tab->var[j].index;
312 isl_int_set(bmap->eq[k][1 + j],
313 tab->mat->row[row][off + col]);
315 for (j = 0; j < tab->n_div; ++j) {
317 if (tab->var[tab->n_var - tab->n_div+j].is_row)
319 col = tab->var[tab->n_var - tab->n_div+j].index;
320 isl_int_set(bmap->eq[k][1 + total + j],
321 tab->mat->row[row][off + col]);
324 isl_int_set(bmap->eq[k][1 + i],
325 tab->mat->row[row][0]);
327 isl_int_neg(bmap->eq[k][1 + i],
328 tab->mat->row[row][0]);
331 bmap = isl_basic_map_simplify(bmap);
332 bmap = isl_basic_map_finalize(bmap);
333 sol->map = isl_map_grow(sol->map, 1);
334 sol->map = isl_map_add(sol->map, bmap);
339 isl_basic_map_free(bmap);
344 static struct isl_sol *sol_map_add_wrap(struct isl_sol *sol,
347 return (struct isl_sol *)sol_map_add((struct isl_sol_map *)sol, tab);
351 /* Store the "parametric constant" of row "row" of tableau "tab" in "line",
352 * i.e., the constant term and the coefficients of all variables that
353 * appear in the context tableau.
354 * Note that the coefficient of the big parameter M is NOT copied.
355 * The context tableau may not have a big parameter and even when it
356 * does, it is a different big parameter.
358 static void get_row_parameter_line(struct isl_tab *tab, int row, isl_int *line)
361 unsigned off = 2 + tab->M;
363 isl_int_set(line[0], tab->mat->row[row][1]);
364 for (i = 0; i < tab->n_param; ++i) {
365 if (tab->var[i].is_row)
366 isl_int_set_si(line[1 + i], 0);
368 int col = tab->var[i].index;
369 isl_int_set(line[1 + i], tab->mat->row[row][off + col]);
372 for (i = 0; i < tab->n_div; ++i) {
373 if (tab->var[tab->n_var - tab->n_div + i].is_row)
374 isl_int_set_si(line[1 + tab->n_param + i], 0);
376 int col = tab->var[tab->n_var - tab->n_div + i].index;
377 isl_int_set(line[1 + tab->n_param + i],
378 tab->mat->row[row][off + col]);
383 /* Check if rows "row1" and "row2" have identical "parametric constants",
384 * as explained above.
385 * In this case, we also insist that the coefficients of the big parameter
386 * be the same as the values of the constants will only be the same
387 * if these coefficients are also the same.
389 static int identical_parameter_line(struct isl_tab *tab, int row1, int row2)
392 unsigned off = 2 + tab->M;
394 if (isl_int_ne(tab->mat->row[row1][1], tab->mat->row[row2][1]))
397 if (tab->M && isl_int_ne(tab->mat->row[row1][2],
398 tab->mat->row[row2][2]))
401 for (i = 0; i < tab->n_param + tab->n_div; ++i) {
402 int pos = i < tab->n_param ? i :
403 tab->n_var - tab->n_div + i - tab->n_param;
406 if (tab->var[pos].is_row)
408 col = tab->var[pos].index;
409 if (isl_int_ne(tab->mat->row[row1][off + col],
410 tab->mat->row[row2][off + col]))
416 /* Return an inequality that expresses that the "parametric constant"
417 * should be non-negative.
418 * This function is only called when the coefficient of the big parameter
421 static struct isl_vec *get_row_parameter_ineq(struct isl_tab *tab, int row)
423 struct isl_vec *ineq;
425 ineq = isl_vec_alloc(tab->mat->ctx, 1 + tab->n_param + tab->n_div);
429 get_row_parameter_line(tab, row, ineq->el);
431 ineq = isl_vec_normalize(ineq);
436 /* Return a integer division for use in a parametric cut based on the given row.
437 * In particular, let the parametric constant of the row be
441 * where y_0 = 1, but none of the y_i corresponds to the big parameter M.
442 * The div returned is equal to
444 * floor(\sum_i {-a_i} y_i) = floor((\sum_i (-a_i mod d) y_i)/d)
446 static struct isl_vec *get_row_parameter_div(struct isl_tab *tab, int row)
450 div = isl_vec_alloc(tab->mat->ctx, 1 + 1 + tab->n_param + tab->n_div);
454 isl_int_set(div->el[0], tab->mat->row[row][0]);
455 get_row_parameter_line(tab, row, div->el + 1);
456 div = isl_vec_normalize(div);
457 isl_seq_neg(div->el + 1, div->el + 1, div->size - 1);
458 isl_seq_fdiv_r(div->el + 1, div->el + 1, div->el[0], div->size - 1);
463 /* Return a integer division for use in transferring an integrality constraint
465 * In particular, let the parametric constant of the row be
469 * where y_0 = 1, but none of the y_i corresponds to the big parameter M.
470 * The the returned div is equal to
472 * floor(\sum_i {a_i} y_i) = floor((\sum_i (a_i mod d) y_i)/d)
474 static struct isl_vec *get_row_split_div(struct isl_tab *tab, int row)
478 div = isl_vec_alloc(tab->mat->ctx, 1 + 1 + tab->n_param + tab->n_div);
482 isl_int_set(div->el[0], tab->mat->row[row][0]);
483 get_row_parameter_line(tab, row, div->el + 1);
484 div = isl_vec_normalize(div);
485 isl_seq_fdiv_r(div->el + 1, div->el + 1, div->el[0], div->size - 1);
490 /* Construct and return an inequality that expresses an upper bound
492 * In particular, if the div is given by
496 * then the inequality expresses
500 static struct isl_vec *ineq_for_div(struct isl_basic_set *bset, unsigned div)
504 struct isl_vec *ineq;
509 total = isl_basic_set_total_dim(bset);
510 div_pos = 1 + total - bset->n_div + div;
512 ineq = isl_vec_alloc(bset->ctx, 1 + total);
516 isl_seq_cpy(ineq->el, bset->div[div] + 1, 1 + total);
517 isl_int_neg(ineq->el[div_pos], bset->div[div][0]);
521 /* Given a row in the tableau and a div that was created
522 * using get_row_split_div and that been constrained to equality, i.e.,
524 * d = floor(\sum_i {a_i} y_i) = \sum_i {a_i} y_i
526 * replace the expression "\sum_i {a_i} y_i" in the row by d,
527 * i.e., we subtract "\sum_i {a_i} y_i" and add 1 d.
528 * The coefficients of the non-parameters in the tableau have been
529 * verified to be integral. We can therefore simply replace coefficient b
530 * by floor(b). For the coefficients of the parameters we have
531 * floor(a_i) = a_i - {a_i}, while for the other coefficients, we have
534 static struct isl_tab *set_row_cst_to_div(struct isl_tab *tab, int row, int div)
536 isl_seq_fdiv_q(tab->mat->row[row] + 1, tab->mat->row[row] + 1,
537 tab->mat->row[row][0], 1 + tab->M + tab->n_col);
539 isl_int_set_si(tab->mat->row[row][0], 1);
541 if (tab->var[tab->n_var - tab->n_div + div].is_row) {
542 int drow = tab->var[tab->n_var - tab->n_div + div].index;
544 isl_assert(tab->mat->ctx,
545 isl_int_is_one(tab->mat->row[drow][0]), goto error);
546 isl_seq_combine(tab->mat->row[row] + 1,
547 tab->mat->ctx->one, tab->mat->row[row] + 1,
548 tab->mat->ctx->one, tab->mat->row[drow] + 1,
549 1 + tab->M + tab->n_col);
551 int dcol = tab->var[tab->n_var - tab->n_div + div].index;
553 isl_int_set_si(tab->mat->row[row][2 + tab->M + dcol], 1);
562 /* Check if the (parametric) constant of the given row is obviously
563 * negative, meaning that we don't need to consult the context tableau.
564 * If there is a big parameter and its coefficient is non-zero,
565 * then this coefficient determines the outcome.
566 * Otherwise, we check whether the constant is negative and
567 * all non-zero coefficients of parameters are negative and
568 * belong to non-negative parameters.
570 static int is_obviously_neg(struct isl_tab *tab, int row)
574 unsigned off = 2 + tab->M;
577 if (isl_int_is_pos(tab->mat->row[row][2]))
579 if (isl_int_is_neg(tab->mat->row[row][2]))
583 if (isl_int_is_nonneg(tab->mat->row[row][1]))
585 for (i = 0; i < tab->n_param; ++i) {
586 /* Eliminated parameter */
587 if (tab->var[i].is_row)
589 col = tab->var[i].index;
590 if (isl_int_is_zero(tab->mat->row[row][off + col]))
592 if (!tab->var[i].is_nonneg)
594 if (isl_int_is_pos(tab->mat->row[row][off + col]))
597 for (i = 0; i < tab->n_div; ++i) {
598 if (tab->var[tab->n_var - tab->n_div + i].is_row)
600 col = tab->var[tab->n_var - tab->n_div + i].index;
601 if (isl_int_is_zero(tab->mat->row[row][off + col]))
603 if (!tab->var[tab->n_var - tab->n_div + i].is_nonneg)
605 if (isl_int_is_pos(tab->mat->row[row][off + col]))
611 /* Check if the (parametric) constant of the given row is obviously
612 * non-negative, meaning that we don't need to consult the context tableau.
613 * If there is a big parameter and its coefficient is non-zero,
614 * then this coefficient determines the outcome.
615 * Otherwise, we check whether the constant is non-negative and
616 * all non-zero coefficients of parameters are positive and
617 * belong to non-negative parameters.
619 static int is_obviously_nonneg(struct isl_tab *tab, int row)
623 unsigned off = 2 + tab->M;
626 if (isl_int_is_pos(tab->mat->row[row][2]))
628 if (isl_int_is_neg(tab->mat->row[row][2]))
632 if (isl_int_is_neg(tab->mat->row[row][1]))
634 for (i = 0; i < tab->n_param; ++i) {
635 /* Eliminated parameter */
636 if (tab->var[i].is_row)
638 col = tab->var[i].index;
639 if (isl_int_is_zero(tab->mat->row[row][off + col]))
641 if (!tab->var[i].is_nonneg)
643 if (isl_int_is_neg(tab->mat->row[row][off + col]))
646 for (i = 0; i < tab->n_div; ++i) {
647 if (tab->var[tab->n_var - tab->n_div + i].is_row)
649 col = tab->var[tab->n_var - tab->n_div + i].index;
650 if (isl_int_is_zero(tab->mat->row[row][off + col]))
652 if (!tab->var[tab->n_var - tab->n_div + i].is_nonneg)
654 if (isl_int_is_neg(tab->mat->row[row][off + col]))
660 /* Given a row r and two columns, return the column that would
661 * lead to the lexicographically smallest increment in the sample
662 * solution when leaving the basis in favor of the row.
663 * Pivoting with column c will increment the sample value by a non-negative
664 * constant times a_{V,c}/a_{r,c}, with a_{V,c} the elements of column c
665 * corresponding to the non-parametric variables.
666 * If variable v appears in a column c_v, the a_{v,c} = 1 iff c = c_v,
667 * with all other entries in this virtual row equal to zero.
668 * If variable v appears in a row, then a_{v,c} is the element in column c
671 * Let v be the first variable with a_{v,c1}/a_{r,c1} != a_{v,c2}/a_{r,c2}.
672 * Then if a_{v,c1}/a_{r,c1} < a_{v,c2}/a_{r,c2}, i.e.,
673 * a_{v,c2} a_{r,c1} - a_{v,c1} a_{r,c2} > 0, c1 results in the minimal
674 * increment. Otherwise, it's c2.
676 static int lexmin_col_pair(struct isl_tab *tab,
677 int row, int col1, int col2, isl_int tmp)
682 tr = tab->mat->row[row] + 2 + tab->M;
684 for (i = tab->n_param; i < tab->n_var - tab->n_div; ++i) {
688 if (!tab->var[i].is_row) {
689 if (tab->var[i].index == col1)
691 if (tab->var[i].index == col2)
696 if (tab->var[i].index == row)
699 r = tab->mat->row[tab->var[i].index] + 2 + tab->M;
700 s1 = isl_int_sgn(r[col1]);
701 s2 = isl_int_sgn(r[col2]);
702 if (s1 == 0 && s2 == 0)
709 isl_int_mul(tmp, r[col2], tr[col1]);
710 isl_int_submul(tmp, r[col1], tr[col2]);
711 if (isl_int_is_pos(tmp))
713 if (isl_int_is_neg(tmp))
719 /* Given a row in the tableau, find and return the column that would
720 * result in the lexicographically smallest, but positive, increment
721 * in the sample point.
722 * If there is no such column, then return tab->n_col.
723 * If anything goes wrong, return -1.
725 static int lexmin_pivot_col(struct isl_tab *tab, int row)
728 int col = tab->n_col;
732 tr = tab->mat->row[row] + 2 + tab->M;
736 for (j = tab->n_dead; j < tab->n_col; ++j) {
737 if (tab->col_var[j] >= 0 &&
738 (tab->col_var[j] < tab->n_param ||
739 tab->col_var[j] >= tab->n_var - tab->n_div))
742 if (!isl_int_is_pos(tr[j]))
745 if (col == tab->n_col)
748 col = lexmin_col_pair(tab, row, col, j, tmp);
749 isl_assert(tab->mat->ctx, col >= 0, goto error);
759 /* Return the first known violated constraint, i.e., a non-negative
760 * contraint that currently has an either obviously negative value
761 * or a previously determined to be negative value.
763 * If any constraint has a negative coefficient for the big parameter,
764 * if any, then we return one of these first.
766 static int first_neg(struct isl_tab *tab)
771 for (row = tab->n_redundant; row < tab->n_row; ++row) {
772 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
774 if (isl_int_is_neg(tab->mat->row[row][2]))
777 for (row = tab->n_redundant; row < tab->n_row; ++row) {
778 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
781 if (tab->row_sign[row] == 0 &&
782 is_obviously_neg(tab, row))
783 tab->row_sign[row] = isl_tab_row_neg;
784 if (tab->row_sign[row] != isl_tab_row_neg)
786 } else if (!is_obviously_neg(tab, row))
793 /* Resolve all known or obviously violated constraints through pivoting.
794 * In particular, as long as we can find any violated constraint, we
795 * look for a pivoting column that would result in the lexicographicallly
796 * smallest increment in the sample point. If there is no such column
797 * then the tableau is infeasible.
799 static struct isl_tab *restore_lexmin(struct isl_tab *tab);
800 static struct isl_tab *restore_lexmin(struct isl_tab *tab)
808 while ((row = first_neg(tab)) != -1) {
809 col = lexmin_pivot_col(tab, row);
810 if (col >= tab->n_col)
811 return isl_tab_mark_empty(tab);
814 if (isl_tab_pivot(tab, row, col) < 0)
823 /* Given a row that represents an equality, look for an appropriate
825 * In particular, if there are any non-zero coefficients among
826 * the non-parameter variables, then we take the last of these
827 * variables. Eliminating this variable in terms of the other
828 * variables and/or parameters does not influence the property
829 * that all column in the initial tableau are lexicographically
830 * positive. The row corresponding to the eliminated variable
831 * will only have non-zero entries below the diagonal of the
832 * initial tableau. That is, we transform
838 * If there is no such non-parameter variable, then we are dealing with
839 * pure parameter equality and we pick any parameter with coefficient 1 or -1
840 * for elimination. This will ensure that the eliminated parameter
841 * always has an integer value whenever all the other parameters are integral.
842 * If there is no such parameter then we return -1.
844 static int last_var_col_or_int_par_col(struct isl_tab *tab, int row)
846 unsigned off = 2 + tab->M;
849 for (i = tab->n_var - tab->n_div - 1; i >= 0 && i >= tab->n_param; --i) {
851 if (tab->var[i].is_row)
853 col = tab->var[i].index;
854 if (col <= tab->n_dead)
856 if (!isl_int_is_zero(tab->mat->row[row][off + col]))
859 for (i = tab->n_dead; i < tab->n_col; ++i) {
860 if (isl_int_is_one(tab->mat->row[row][off + i]))
862 if (isl_int_is_negone(tab->mat->row[row][off + i]))
868 /* Add an equality that is known to be valid to the tableau.
869 * We first check if we can eliminate a variable or a parameter.
870 * If not, we add the equality as two inequalities.
871 * In this case, the equality was a pure parameter equality and there
872 * is no need to resolve any constraint violations.
874 static struct isl_tab *add_lexmin_valid_eq(struct isl_tab *tab, isl_int *eq)
881 r = isl_tab_add_row(tab, eq);
885 r = tab->con[r].index;
886 i = last_var_col_or_int_par_col(tab, r);
888 tab->con[r].is_nonneg = 1;
889 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
891 isl_seq_neg(eq, eq, 1 + tab->n_var);
892 r = isl_tab_add_row(tab, eq);
895 tab->con[r].is_nonneg = 1;
896 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
899 if (isl_tab_pivot(tab, r, i) < 0)
901 if (isl_tab_kill_col(tab, i) < 0)
905 tab = restore_lexmin(tab);
914 /* Check if the given row is a pure constant.
916 static int is_constant(struct isl_tab *tab, int row)
918 unsigned off = 2 + tab->M;
920 return isl_seq_first_non_zero(tab->mat->row[row] + off + tab->n_dead,
921 tab->n_col - tab->n_dead) == -1;
924 /* Add an equality that may or may not be valid to the tableau.
925 * If the resulting row is a pure constant, then it must be zero.
926 * Otherwise, the resulting tableau is empty.
928 * If the row is not a pure constant, then we add two inequalities,
929 * each time checking that they can be satisfied.
930 * In the end we try to use one of the two constraints to eliminate
933 static struct isl_tab *add_lexmin_eq(struct isl_tab *tab, isl_int *eq)
937 struct isl_tab_undo *snap;
941 snap = isl_tab_snap(tab);
942 r1 = isl_tab_add_row(tab, eq);
945 tab->con[r1].is_nonneg = 1;
946 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r1]) < 0)
949 row = tab->con[r1].index;
950 if (is_constant(tab, row)) {
951 if (!isl_int_is_zero(tab->mat->row[row][1]) ||
952 (tab->M && !isl_int_is_zero(tab->mat->row[row][2])))
953 return isl_tab_mark_empty(tab);
954 if (isl_tab_rollback(tab, snap) < 0)
959 tab = restore_lexmin(tab);
960 if (!tab || tab->empty)
963 isl_seq_neg(eq, eq, 1 + tab->n_var);
965 r2 = isl_tab_add_row(tab, eq);
968 tab->con[r2].is_nonneg = 1;
969 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r2]) < 0)
972 tab = restore_lexmin(tab);
973 if (!tab || tab->empty)
976 if (!tab->con[r1].is_row) {
977 if (isl_tab_kill_col(tab, tab->con[r1].index) < 0)
979 } else if (!tab->con[r2].is_row) {
980 if (isl_tab_kill_col(tab, tab->con[r2].index) < 0)
982 } else if (isl_int_is_zero(tab->mat->row[tab->con[r1].index][1])) {
983 unsigned off = 2 + tab->M;
985 int row = tab->con[r1].index;
986 i = isl_seq_first_non_zero(tab->mat->row[row]+off+tab->n_dead,
987 tab->n_col - tab->n_dead);
989 if (isl_tab_pivot(tab, row, tab->n_dead + i) < 0)
991 if (isl_tab_kill_col(tab, tab->n_dead + i) < 0)
997 tab->bset = isl_basic_set_add_ineq(tab->bset, eq);
998 if (isl_tab_push(tab, isl_tab_undo_bset_ineq) < 0)
1000 isl_seq_neg(eq, eq, 1 + tab->n_var);
1001 tab->bset = isl_basic_set_add_ineq(tab->bset, eq);
1002 isl_seq_neg(eq, eq, 1 + tab->n_var);
1003 if (isl_tab_push(tab, isl_tab_undo_bset_ineq) < 0)
1015 /* Add an inequality to the tableau, resolving violations using
1018 static struct isl_tab *add_lexmin_ineq(struct isl_tab *tab, isl_int *ineq)
1025 tab->bset = isl_basic_set_add_ineq(tab->bset, ineq);
1026 if (isl_tab_push(tab, isl_tab_undo_bset_ineq) < 0)
1031 r = isl_tab_add_row(tab, ineq);
1034 tab->con[r].is_nonneg = 1;
1035 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1037 if (isl_tab_row_is_redundant(tab, tab->con[r].index)) {
1038 if (isl_tab_mark_redundant(tab, tab->con[r].index) < 0)
1043 tab = restore_lexmin(tab);
1044 if (tab && !tab->empty && tab->con[r].is_row &&
1045 isl_tab_row_is_redundant(tab, tab->con[r].index))
1046 if (isl_tab_mark_redundant(tab, tab->con[r].index) < 0)
1054 /* Check if the coefficients of the parameters are all integral.
1056 static int integer_parameter(struct isl_tab *tab, int row)
1060 unsigned off = 2 + tab->M;
1062 for (i = 0; i < tab->n_param; ++i) {
1063 /* Eliminated parameter */
1064 if (tab->var[i].is_row)
1066 col = tab->var[i].index;
1067 if (!isl_int_is_divisible_by(tab->mat->row[row][off + col],
1068 tab->mat->row[row][0]))
1071 for (i = 0; i < tab->n_div; ++i) {
1072 if (tab->var[tab->n_var - tab->n_div + i].is_row)
1074 col = tab->var[tab->n_var - tab->n_div + i].index;
1075 if (!isl_int_is_divisible_by(tab->mat->row[row][off + col],
1076 tab->mat->row[row][0]))
1082 /* Check if the coefficients of the non-parameter variables are all integral.
1084 static int integer_variable(struct isl_tab *tab, int row)
1087 unsigned off = 2 + tab->M;
1089 for (i = 0; i < tab->n_col; ++i) {
1090 if (tab->col_var[i] >= 0 &&
1091 (tab->col_var[i] < tab->n_param ||
1092 tab->col_var[i] >= tab->n_var - tab->n_div))
1094 if (!isl_int_is_divisible_by(tab->mat->row[row][off + i],
1095 tab->mat->row[row][0]))
1101 /* Check if the constant term is integral.
1103 static int integer_constant(struct isl_tab *tab, int row)
1105 return isl_int_is_divisible_by(tab->mat->row[row][1],
1106 tab->mat->row[row][0]);
1109 #define I_CST 1 << 0
1110 #define I_PAR 1 << 1
1111 #define I_VAR 1 << 2
1113 /* Check for first (non-parameter) variable that is non-integer and
1114 * therefore requires a cut.
1115 * For parametric tableaus, there are three parts in a row,
1116 * the constant, the coefficients of the parameters and the rest.
1117 * For each part, we check whether the coefficients in that part
1118 * are all integral and if so, set the corresponding flag in *f.
1119 * If the constant and the parameter part are integral, then the
1120 * current sample value is integral and no cut is required
1121 * (irrespective of whether the variable part is integral).
1123 static int first_non_integer(struct isl_tab *tab, int *f)
1127 for (i = tab->n_param; i < tab->n_var - tab->n_div; ++i) {
1130 if (!tab->var[i].is_row)
1132 row = tab->var[i].index;
1133 if (integer_constant(tab, row))
1134 ISL_FL_SET(flags, I_CST);
1135 if (integer_parameter(tab, row))
1136 ISL_FL_SET(flags, I_PAR);
1137 if (ISL_FL_ISSET(flags, I_CST) && ISL_FL_ISSET(flags, I_PAR))
1139 if (integer_variable(tab, row))
1140 ISL_FL_SET(flags, I_VAR);
1147 /* Add a (non-parametric) cut to cut away the non-integral sample
1148 * value of the given row.
1150 * If the row is given by
1152 * m r = f + \sum_i a_i y_i
1156 * c = - {-f/m} + \sum_i {a_i/m} y_i >= 0
1158 * The big parameter, if any, is ignored, since it is assumed to be big
1159 * enough to be divisible by any integer.
1160 * If the tableau is actually a parametric tableau, then this function
1161 * is only called when all coefficients of the parameters are integral.
1162 * The cut therefore has zero coefficients for the parameters.
1164 * The current value is known to be negative, so row_sign, if it
1165 * exists, is set accordingly.
1167 * Return the row of the cut or -1.
1169 static int add_cut(struct isl_tab *tab, int row)
1174 unsigned off = 2 + tab->M;
1176 if (isl_tab_extend_cons(tab, 1) < 0)
1178 r = isl_tab_allocate_con(tab);
1182 r_row = tab->mat->row[tab->con[r].index];
1183 isl_int_set(r_row[0], tab->mat->row[row][0]);
1184 isl_int_neg(r_row[1], tab->mat->row[row][1]);
1185 isl_int_fdiv_r(r_row[1], r_row[1], tab->mat->row[row][0]);
1186 isl_int_neg(r_row[1], r_row[1]);
1188 isl_int_set_si(r_row[2], 0);
1189 for (i = 0; i < tab->n_col; ++i)
1190 isl_int_fdiv_r(r_row[off + i],
1191 tab->mat->row[row][off + i], tab->mat->row[row][0]);
1193 tab->con[r].is_nonneg = 1;
1194 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1197 tab->row_sign[tab->con[r].index] = isl_tab_row_neg;
1199 return tab->con[r].index;
1202 /* Given a non-parametric tableau, add cuts until an integer
1203 * sample point is obtained or until the tableau is determined
1204 * to be integer infeasible.
1205 * As long as there is any non-integer value in the sample point,
1206 * we add an appropriate cut, if possible and resolve the violated
1207 * cut constraint using restore_lexmin.
1208 * If one of the corresponding rows is equal to an integral
1209 * combination of variables/constraints plus a non-integral constant,
1210 * then there is no way to obtain an integer point an we return
1211 * a tableau that is marked empty.
1213 static struct isl_tab *cut_to_integer_lexmin(struct isl_tab *tab)
1223 while ((row = first_non_integer(tab, &flags)) != -1) {
1224 if (ISL_FL_ISSET(flags, I_VAR))
1225 return isl_tab_mark_empty(tab);
1226 row = add_cut(tab, row);
1229 tab = restore_lexmin(tab);
1230 if (!tab || tab->empty)
1239 /* Check whether all the currently active samples also satisfy the inequality
1240 * "ineq" (treated as an equality if eq is set).
1241 * Remove those samples that do not.
1243 static struct isl_tab *check_samples(struct isl_tab *tab, isl_int *ineq, int eq)
1251 isl_assert(tab->mat->ctx, tab->bset, goto error);
1252 isl_assert(tab->mat->ctx, tab->samples, goto error);
1253 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var, goto error);
1256 for (i = tab->n_outside; i < tab->n_sample; ++i) {
1258 isl_seq_inner_product(ineq, tab->samples->row[i],
1259 1 + tab->n_var, &v);
1260 sgn = isl_int_sgn(v);
1261 if (eq ? (sgn == 0) : (sgn >= 0))
1263 tab = isl_tab_drop_sample(tab, i);
1275 /* Check whether the sample value of the tableau is finite,
1276 * i.e., either the tableau does not use a big parameter, or
1277 * all values of the variables are equal to the big parameter plus
1278 * some constant. This constant is the actual sample value.
1280 static int sample_is_finite(struct isl_tab *tab)
1287 for (i = 0; i < tab->n_var; ++i) {
1289 if (!tab->var[i].is_row)
1291 row = tab->var[i].index;
1292 if (isl_int_ne(tab->mat->row[row][0], tab->mat->row[row][2]))
1298 /* Check if the context tableau of sol has any integer points.
1299 * Leave tab in empty state if no integer point can be found.
1300 * If an integer point can be found and if moreover it is finite,
1301 * then it is added to the list of sample values.
1303 * This function is only called when none of the currently active sample
1304 * values satisfies the most recently added constraint.
1306 static struct isl_tab *check_integer_feasible(struct isl_tab *tab)
1308 struct isl_tab_undo *snap;
1314 snap = isl_tab_snap(tab);
1315 if (isl_tab_push_basis(tab) < 0)
1318 tab = cut_to_integer_lexmin(tab);
1322 if (!tab->empty && sample_is_finite(tab)) {
1323 struct isl_vec *sample;
1325 sample = isl_tab_get_sample_value(tab);
1327 tab = isl_tab_add_sample(tab, sample);
1330 if (!tab->empty && isl_tab_rollback(tab, snap) < 0)
1339 /* Check if any of the currently active sample values satisfies
1340 * the inequality "ineq" (an equality if eq is set).
1342 static int tab_has_valid_sample(struct isl_tab *tab, isl_int *ineq, int eq)
1350 isl_assert(tab->mat->ctx, tab->bset, return -1);
1351 isl_assert(tab->mat->ctx, tab->samples, return -1);
1352 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var, return -1);
1355 for (i = tab->n_outside; i < tab->n_sample; ++i) {
1357 isl_seq_inner_product(ineq, tab->samples->row[i],
1358 1 + tab->n_var, &v);
1359 sgn = isl_int_sgn(v);
1360 if (eq ? (sgn == 0) : (sgn >= 0))
1365 return i < tab->n_sample;
1368 /* For a div d = floor(f/m), add the constraints
1371 * -(f-(m-1)) + m d >= 0
1373 * Note that the second constraint is the negation of
1377 static void add_div_constraints(struct isl_context *context, unsigned div)
1381 struct isl_vec *ineq;
1382 struct isl_basic_set *bset;
1384 bset = context->op->peek_basic_set(context);
1388 total = isl_basic_set_total_dim(bset);
1389 div_pos = 1 + total - bset->n_div + div;
1391 ineq = ineq_for_div(bset, div);
1395 context->op->add_ineq(context, ineq->el, 0, 0);
1397 isl_seq_neg(ineq->el, bset->div[div] + 1, 1 + total);
1398 isl_int_set(ineq->el[div_pos], bset->div[div][0]);
1399 isl_int_add(ineq->el[0], ineq->el[0], ineq->el[div_pos]);
1400 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
1402 context->op->add_ineq(context, ineq->el, 0, 0);
1408 context->op->invalidate(context);
1411 /* Add a div specifed by "div" to the tableau "tab" and return
1412 * the index of the new div. *nonneg is set to 1 if the div
1413 * is obviously non-negative.
1415 static int context_tab_add_div(struct isl_tab *tab, struct isl_vec *div,
1421 struct isl_mat *samples;
1423 for (i = 0; i < tab->n_var; ++i) {
1424 if (isl_int_is_zero(div->el[2 + i]))
1426 if (!tab->var[i].is_nonneg)
1429 *nonneg = i == tab->n_var;
1431 if (isl_tab_extend_cons(tab, 3) < 0)
1433 if (isl_tab_extend_vars(tab, 1) < 0)
1435 r = isl_tab_allocate_var(tab);
1439 tab->var[r].is_nonneg = 1;
1440 tab->var[r].frozen = 1;
1442 samples = isl_mat_extend(tab->samples,
1443 tab->n_sample, 1 + tab->n_var);
1444 tab->samples = samples;
1447 for (i = tab->n_outside; i < samples->n_row; ++i) {
1448 isl_seq_inner_product(div->el + 1, samples->row[i],
1449 div->size - 1, &samples->row[i][samples->n_col - 1]);
1450 isl_int_fdiv_q(samples->row[i][samples->n_col - 1],
1451 samples->row[i][samples->n_col - 1], div->el[0]);
1454 tab->bset = isl_basic_set_extend_dim(tab->bset,
1455 isl_basic_set_get_dim(tab->bset), 1, 0, 2);
1456 k = isl_basic_set_alloc_div(tab->bset);
1459 isl_seq_cpy(tab->bset->div[k], div->el, div->size);
1460 if (isl_tab_push(tab, isl_tab_undo_bset_div) < 0)
1466 /* Add a div specified by "div" to both the main tableau and
1467 * the context tableau. In case of the main tableau, we only
1468 * need to add an extra div. In the context tableau, we also
1469 * need to express the meaning of the div.
1470 * Return the index of the div or -1 if anything went wrong.
1472 static int add_div(struct isl_tab *tab, struct isl_context *context,
1473 struct isl_vec *div)
1479 k = context->op->add_div(context, div, &nonneg);
1483 add_div_constraints(context, k);
1484 if (!context->op->is_ok(context))
1487 if (isl_tab_extend_vars(tab, 1) < 0)
1489 r = isl_tab_allocate_var(tab);
1493 tab->var[r].is_nonneg = 1;
1494 tab->var[r].frozen = 1;
1497 return tab->n_div - 1;
1499 context->op->invalidate(context);
1503 static int find_div(struct isl_tab *tab, isl_int *div, isl_int denom)
1506 unsigned total = isl_basic_set_total_dim(tab->bset);
1508 for (i = 0; i < tab->bset->n_div; ++i) {
1509 if (isl_int_ne(tab->bset->div[i][0], denom))
1511 if (!isl_seq_eq(tab->bset->div[i] + 1, div, total))
1518 /* Return the index of a div that corresponds to "div".
1519 * We first check if we already have such a div and if not, we create one.
1521 static int get_div(struct isl_tab *tab, struct isl_context *context,
1522 struct isl_vec *div)
1525 struct isl_tab *context_tab = context->op->peek_tab(context);
1530 d = find_div(context_tab, div->el + 1, div->el[0]);
1534 return add_div(tab, context, div);
1537 /* Add a parametric cut to cut away the non-integral sample value
1539 * Let a_i be the coefficients of the constant term and the parameters
1540 * and let b_i be the coefficients of the variables or constraints
1541 * in basis of the tableau.
1542 * Let q be the div q = floor(\sum_i {-a_i} y_i).
1544 * The cut is expressed as
1546 * c = \sum_i -{-a_i} y_i + \sum_i {b_i} x_i + q >= 0
1548 * If q did not already exist in the context tableau, then it is added first.
1549 * If q is in a column of the main tableau then the "+ q" can be accomplished
1550 * by setting the corresponding entry to the denominator of the constraint.
1551 * If q happens to be in a row of the main tableau, then the corresponding
1552 * row needs to be added instead (taking care of the denominators).
1553 * Note that this is very unlikely, but perhaps not entirely impossible.
1555 * The current value of the cut is known to be negative (or at least
1556 * non-positive), so row_sign is set accordingly.
1558 * Return the row of the cut or -1.
1560 static int add_parametric_cut(struct isl_tab *tab, int row,
1561 struct isl_context *context)
1563 struct isl_vec *div;
1570 unsigned off = 2 + tab->M;
1575 div = get_row_parameter_div(tab, row);
1580 d = context->op->get_div(context, tab, div);
1584 if (isl_tab_extend_cons(tab, 1) < 0)
1586 r = isl_tab_allocate_con(tab);
1590 r_row = tab->mat->row[tab->con[r].index];
1591 isl_int_set(r_row[0], tab->mat->row[row][0]);
1592 isl_int_neg(r_row[1], tab->mat->row[row][1]);
1593 isl_int_fdiv_r(r_row[1], r_row[1], tab->mat->row[row][0]);
1594 isl_int_neg(r_row[1], r_row[1]);
1596 isl_int_set_si(r_row[2], 0);
1597 for (i = 0; i < tab->n_param; ++i) {
1598 if (tab->var[i].is_row)
1600 col = tab->var[i].index;
1601 isl_int_neg(r_row[off + col], tab->mat->row[row][off + col]);
1602 isl_int_fdiv_r(r_row[off + col], r_row[off + col],
1603 tab->mat->row[row][0]);
1604 isl_int_neg(r_row[off + col], r_row[off + col]);
1606 for (i = 0; i < tab->n_div; ++i) {
1607 if (tab->var[tab->n_var - tab->n_div + i].is_row)
1609 col = tab->var[tab->n_var - tab->n_div + i].index;
1610 isl_int_neg(r_row[off + col], tab->mat->row[row][off + col]);
1611 isl_int_fdiv_r(r_row[off + col], r_row[off + col],
1612 tab->mat->row[row][0]);
1613 isl_int_neg(r_row[off + col], r_row[off + col]);
1615 for (i = 0; i < tab->n_col; ++i) {
1616 if (tab->col_var[i] >= 0 &&
1617 (tab->col_var[i] < tab->n_param ||
1618 tab->col_var[i] >= tab->n_var - tab->n_div))
1620 isl_int_fdiv_r(r_row[off + i],
1621 tab->mat->row[row][off + i], tab->mat->row[row][0]);
1623 if (tab->var[tab->n_var - tab->n_div + d].is_row) {
1625 int d_row = tab->var[tab->n_var - tab->n_div + d].index;
1627 isl_int_gcd(gcd, tab->mat->row[d_row][0], r_row[0]);
1628 isl_int_divexact(r_row[0], r_row[0], gcd);
1629 isl_int_divexact(gcd, tab->mat->row[d_row][0], gcd);
1630 isl_seq_combine(r_row + 1, gcd, r_row + 1,
1631 r_row[0], tab->mat->row[d_row] + 1,
1632 off - 1 + tab->n_col);
1633 isl_int_mul(r_row[0], r_row[0], tab->mat->row[d_row][0]);
1636 col = tab->var[tab->n_var - tab->n_div + d].index;
1637 isl_int_set(r_row[off + col], tab->mat->row[row][0]);
1640 tab->con[r].is_nonneg = 1;
1641 if (isl_tab_push_var(tab, isl_tab_undo_nonneg, &tab->con[r]) < 0)
1644 tab->row_sign[tab->con[r].index] = isl_tab_row_neg;
1648 row = tab->con[r].index;
1650 if (d >= n && context->op->detect_equalities(context, tab) < 0)
1656 /* Construct a tableau for bmap that can be used for computing
1657 * the lexicographic minimum (or maximum) of bmap.
1658 * If not NULL, then dom is the domain where the minimum
1659 * should be computed. In this case, we set up a parametric
1660 * tableau with row signs (initialized to "unknown").
1661 * If M is set, then the tableau will use a big parameter.
1662 * If max is set, then a maximum should be computed instead of a minimum.
1663 * This means that for each variable x, the tableau will contain the variable
1664 * x' = M - x, rather than x' = M + x. This in turn means that the coefficient
1665 * of the variables in all constraints are negated prior to adding them
1668 static struct isl_tab *tab_for_lexmin(struct isl_basic_map *bmap,
1669 struct isl_basic_set *dom, unsigned M, int max)
1672 struct isl_tab *tab;
1674 tab = isl_tab_alloc(bmap->ctx, 2 * bmap->n_eq + bmap->n_ineq + 1,
1675 isl_basic_map_total_dim(bmap), M);
1679 tab->rational = ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL);
1681 tab->n_param = isl_basic_set_total_dim(dom) - dom->n_div;
1682 tab->n_div = dom->n_div;
1683 tab->row_sign = isl_calloc_array(bmap->ctx,
1684 enum isl_tab_row_sign, tab->mat->n_row);
1688 if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_EMPTY))
1689 return isl_tab_mark_empty(tab);
1691 for (i = tab->n_param; i < tab->n_var - tab->n_div; ++i) {
1692 tab->var[i].is_nonneg = 1;
1693 tab->var[i].frozen = 1;
1695 for (i = 0; i < bmap->n_eq; ++i) {
1697 isl_seq_neg(bmap->eq[i] + 1 + tab->n_param,
1698 bmap->eq[i] + 1 + tab->n_param,
1699 tab->n_var - tab->n_param - tab->n_div);
1700 tab = add_lexmin_valid_eq(tab, bmap->eq[i]);
1702 isl_seq_neg(bmap->eq[i] + 1 + tab->n_param,
1703 bmap->eq[i] + 1 + tab->n_param,
1704 tab->n_var - tab->n_param - tab->n_div);
1705 if (!tab || tab->empty)
1708 for (i = 0; i < bmap->n_ineq; ++i) {
1710 isl_seq_neg(bmap->ineq[i] + 1 + tab->n_param,
1711 bmap->ineq[i] + 1 + tab->n_param,
1712 tab->n_var - tab->n_param - tab->n_div);
1713 tab = add_lexmin_ineq(tab, bmap->ineq[i]);
1715 isl_seq_neg(bmap->ineq[i] + 1 + tab->n_param,
1716 bmap->ineq[i] + 1 + tab->n_param,
1717 tab->n_var - tab->n_param - tab->n_div);
1718 if (!tab || tab->empty)
1727 /* Given a main tableau where more than one row requires a split,
1728 * determine and return the "best" row to split on.
1730 * Given two rows in the main tableau, if the inequality corresponding
1731 * to the first row is redundant with respect to that of the second row
1732 * in the current tableau, then it is better to split on the second row,
1733 * since in the positive part, both row will be positive.
1734 * (In the negative part a pivot will have to be performed and just about
1735 * anything can happen to the sign of the other row.)
1737 * As a simple heuristic, we therefore select the row that makes the most
1738 * of the other rows redundant.
1740 * Perhaps it would also be useful to look at the number of constraints
1741 * that conflict with any given constraint.
1743 static int best_split(struct isl_tab *tab, struct isl_tab *context_tab)
1745 struct isl_tab_undo *snap;
1751 if (isl_tab_extend_cons(context_tab, 2) < 0)
1754 snap = isl_tab_snap(context_tab);
1756 for (split = tab->n_redundant; split < tab->n_row; ++split) {
1757 struct isl_tab_undo *snap2;
1758 struct isl_vec *ineq = NULL;
1761 if (!isl_tab_var_from_row(tab, split)->is_nonneg)
1763 if (tab->row_sign[split] != isl_tab_row_any)
1766 ineq = get_row_parameter_ineq(tab, split);
1769 context_tab = isl_tab_add_ineq(context_tab, ineq->el);
1772 snap2 = isl_tab_snap(context_tab);
1774 for (row = tab->n_redundant; row < tab->n_row; ++row) {
1775 struct isl_tab_var *var;
1779 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
1781 if (tab->row_sign[row] != isl_tab_row_any)
1784 ineq = get_row_parameter_ineq(tab, row);
1787 context_tab = isl_tab_add_ineq(context_tab, ineq->el);
1789 var = &context_tab->con[context_tab->n_con - 1];
1790 if (!context_tab->empty &&
1791 !isl_tab_min_at_most_neg_one(context_tab, var))
1793 if (isl_tab_rollback(context_tab, snap2) < 0)
1796 if (best == -1 || r > best_r) {
1800 if (isl_tab_rollback(context_tab, snap) < 0)
1807 static struct isl_basic_set *context_lex_peek_basic_set(
1808 struct isl_context *context)
1810 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1813 return clex->tab->bset;
1816 static struct isl_tab *context_lex_peek_tab(struct isl_context *context)
1818 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1822 static void context_lex_extend(struct isl_context *context, int n)
1824 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1827 if (isl_tab_extend_cons(clex->tab, n) >= 0)
1829 isl_tab_free(clex->tab);
1833 static void context_lex_add_eq(struct isl_context *context, isl_int *eq,
1834 int check, int update)
1836 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1837 if (isl_tab_extend_cons(clex->tab, 2) < 0)
1839 clex->tab = add_lexmin_eq(clex->tab, eq);
1841 int v = tab_has_valid_sample(clex->tab, eq, 1);
1845 clex->tab = check_integer_feasible(clex->tab);
1848 clex->tab = check_samples(clex->tab, eq, 1);
1851 isl_tab_free(clex->tab);
1855 static void context_lex_add_ineq(struct isl_context *context, isl_int *ineq,
1856 int check, int update)
1858 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1859 if (isl_tab_extend_cons(clex->tab, 1) < 0)
1861 clex->tab = add_lexmin_ineq(clex->tab, ineq);
1863 int v = tab_has_valid_sample(clex->tab, ineq, 0);
1867 clex->tab = check_integer_feasible(clex->tab);
1870 clex->tab = check_samples(clex->tab, ineq, 0);
1873 isl_tab_free(clex->tab);
1877 /* Check which signs can be obtained by "ineq" on all the currently
1878 * active sample values. See row_sign for more information.
1880 static enum isl_tab_row_sign tab_ineq_sign(struct isl_tab *tab, isl_int *ineq,
1886 int res = isl_tab_row_unknown;
1888 isl_assert(tab->mat->ctx, tab->samples, return 0);
1889 isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var, return 0);
1892 for (i = tab->n_outside; i < tab->n_sample; ++i) {
1893 isl_seq_inner_product(tab->samples->row[i], ineq,
1894 1 + tab->n_var, &tmp);
1895 sgn = isl_int_sgn(tmp);
1896 if (sgn > 0 || (sgn == 0 && strict)) {
1897 if (res == isl_tab_row_unknown)
1898 res = isl_tab_row_pos;
1899 if (res == isl_tab_row_neg)
1900 res = isl_tab_row_any;
1903 if (res == isl_tab_row_unknown)
1904 res = isl_tab_row_neg;
1905 if (res == isl_tab_row_pos)
1906 res = isl_tab_row_any;
1908 if (res == isl_tab_row_any)
1916 static enum isl_tab_row_sign context_lex_ineq_sign(struct isl_context *context,
1917 isl_int *ineq, int strict)
1919 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1920 return tab_ineq_sign(clex->tab, ineq, strict);
1923 /* Check whether "ineq" can be added to the tableau without rendering
1926 static int context_lex_test_ineq(struct isl_context *context, isl_int *ineq)
1928 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1929 struct isl_tab_undo *snap;
1935 if (isl_tab_extend_cons(clex->tab, 1) < 0)
1938 snap = isl_tab_snap(clex->tab);
1939 if (isl_tab_push_basis(clex->tab) < 0)
1941 clex->tab = add_lexmin_ineq(clex->tab, ineq);
1942 clex->tab = check_integer_feasible(clex->tab);
1945 feasible = !clex->tab->empty;
1946 if (isl_tab_rollback(clex->tab, snap) < 0)
1952 static int context_lex_get_div(struct isl_context *context, struct isl_tab *tab,
1953 struct isl_vec *div)
1955 return get_div(tab, context, div);
1958 static int context_lex_add_div(struct isl_context *context, struct isl_vec *div,
1961 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1962 return context_tab_add_div(clex->tab, div, nonneg);
1965 static int context_lex_detect_equalities(struct isl_context *context,
1966 struct isl_tab *tab)
1971 static int context_lex_best_split(struct isl_context *context,
1972 struct isl_tab *tab)
1974 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1975 struct isl_tab_undo *snap;
1978 snap = isl_tab_snap(clex->tab);
1979 if (isl_tab_push_basis(clex->tab) < 0)
1981 r = best_split(tab, clex->tab);
1983 if (isl_tab_rollback(clex->tab, snap) < 0)
1989 static int context_lex_is_empty(struct isl_context *context)
1991 struct isl_context_lex *clex = (struct isl_context_lex *)context;
1994 return clex->tab->empty;
1997 static void *context_lex_save(struct isl_context *context)
1999 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2000 struct isl_tab_undo *snap;
2002 snap = isl_tab_snap(clex->tab);
2003 if (isl_tab_push_basis(clex->tab) < 0)
2005 if (isl_tab_save_samples(clex->tab) < 0)
2011 static void context_lex_restore(struct isl_context *context, void *save)
2013 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2014 if (isl_tab_rollback(clex->tab, (struct isl_tab_undo *)save) < 0) {
2015 isl_tab_free(clex->tab);
2020 static int context_lex_is_ok(struct isl_context *context)
2022 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2026 /* For each variable in the context tableau, check if the variable can
2027 * only attain non-negative values. If so, mark the parameter as non-negative
2028 * in the main tableau. This allows for a more direct identification of some
2029 * cases of violated constraints.
2031 static struct isl_tab *tab_detect_nonnegative_parameters(struct isl_tab *tab,
2032 struct isl_tab *context_tab)
2035 struct isl_tab_undo *snap;
2036 struct isl_vec *ineq = NULL;
2037 struct isl_tab_var *var;
2040 if (context_tab->n_var == 0)
2043 ineq = isl_vec_alloc(tab->mat->ctx, 1 + context_tab->n_var);
2047 if (isl_tab_extend_cons(context_tab, 1) < 0)
2050 snap = isl_tab_snap(context_tab);
2053 isl_seq_clr(ineq->el, ineq->size);
2054 for (i = 0; i < context_tab->n_var; ++i) {
2055 isl_int_set_si(ineq->el[1 + i], 1);
2056 context_tab = isl_tab_add_ineq(context_tab, ineq->el);
2057 var = &context_tab->con[context_tab->n_con - 1];
2058 if (!context_tab->empty &&
2059 !isl_tab_min_at_most_neg_one(context_tab, var)) {
2061 if (i >= tab->n_param)
2062 j = i - tab->n_param + tab->n_var - tab->n_div;
2063 tab->var[j].is_nonneg = 1;
2066 isl_int_set_si(ineq->el[1 + i], 0);
2067 if (isl_tab_rollback(context_tab, snap) < 0)
2071 if (context_tab->M && n == context_tab->n_var) {
2072 context_tab->mat = isl_mat_drop_cols(context_tab->mat, 2, 1);
2084 static struct isl_tab *context_lex_detect_nonnegative_parameters(
2085 struct isl_context *context, struct isl_tab *tab)
2087 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2088 struct isl_tab_undo *snap;
2090 snap = isl_tab_snap(clex->tab);
2091 if (isl_tab_push_basis(clex->tab) < 0)
2094 tab = tab_detect_nonnegative_parameters(tab, clex->tab);
2096 if (isl_tab_rollback(clex->tab, snap) < 0)
2105 static void context_lex_invalidate(struct isl_context *context)
2107 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2108 isl_tab_free(clex->tab);
2112 static void context_lex_free(struct isl_context *context)
2114 struct isl_context_lex *clex = (struct isl_context_lex *)context;
2115 isl_tab_free(clex->tab);
2119 struct isl_context_op isl_context_lex_op = {
2120 context_lex_detect_nonnegative_parameters,
2121 context_lex_peek_basic_set,
2122 context_lex_peek_tab,
2124 context_lex_add_ineq,
2125 context_lex_ineq_sign,
2126 context_lex_test_ineq,
2127 context_lex_get_div,
2128 context_lex_add_div,
2129 context_lex_detect_equalities,
2130 context_lex_best_split,
2131 context_lex_is_empty,
2134 context_lex_restore,
2135 context_lex_invalidate,
2139 static struct isl_tab *context_tab_for_lexmin(struct isl_basic_set *bset)
2141 struct isl_tab *tab;
2143 bset = isl_basic_set_cow(bset);
2146 tab = tab_for_lexmin((struct isl_basic_map *)bset, NULL, 1, 0);
2150 tab = isl_tab_init_samples(tab);
2153 isl_basic_set_free(bset);
2157 static struct isl_context *isl_context_lex_alloc(struct isl_basic_set *dom)
2159 struct isl_context_lex *clex;
2164 clex = isl_alloc_type(dom->ctx, struct isl_context_lex);
2168 clex->context.op = &isl_context_lex_op;
2170 clex->tab = context_tab_for_lexmin(isl_basic_set_copy(dom));
2171 clex->tab = restore_lexmin(clex->tab);
2172 clex->tab = check_integer_feasible(clex->tab);
2176 return &clex->context;
2178 clex->context.op->free(&clex->context);
2182 struct isl_context_gbr {
2183 struct isl_context context;
2184 struct isl_tab *tab;
2185 struct isl_tab *shifted;
2186 struct isl_tab *cone;
2189 static struct isl_tab *context_gbr_detect_nonnegative_parameters(
2190 struct isl_context *context, struct isl_tab *tab)
2192 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2193 return tab_detect_nonnegative_parameters(tab, cgbr->tab);
2196 static struct isl_basic_set *context_gbr_peek_basic_set(
2197 struct isl_context *context)
2199 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2202 return cgbr->tab->bset;
2205 static struct isl_tab *context_gbr_peek_tab(struct isl_context *context)
2207 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2211 /* Initialize the "shifted" tableau of the context, which
2212 * contains the constraints of the original tableau shifted
2213 * by the sum of all negative coefficients. This ensures
2214 * that any rational point in the shifted tableau can
2215 * be rounded up to yield an integer point in the original tableau.
2217 static void gbr_init_shifted(struct isl_context_gbr *cgbr)
2220 struct isl_vec *cst;
2221 struct isl_basic_set *bset = cgbr->tab->bset;
2222 unsigned dim = isl_basic_set_total_dim(bset);
2224 cst = isl_vec_alloc(cgbr->tab->mat->ctx, bset->n_ineq);
2228 for (i = 0; i < bset->n_ineq; ++i) {
2229 isl_int_set(cst->el[i], bset->ineq[i][0]);
2230 for (j = 0; j < dim; ++j) {
2231 if (!isl_int_is_neg(bset->ineq[i][1 + j]))
2233 isl_int_add(bset->ineq[i][0], bset->ineq[i][0],
2234 bset->ineq[i][1 + j]);
2238 cgbr->shifted = isl_tab_from_basic_set(bset);
2240 for (i = 0; i < bset->n_ineq; ++i)
2241 isl_int_set(bset->ineq[i][0], cst->el[i]);
2246 /* Check if the shifted tableau is non-empty, and if so
2247 * use the sample point to construct an integer point
2248 * of the context tableau.
2250 static struct isl_vec *gbr_get_shifted_sample(struct isl_context_gbr *cgbr)
2252 struct isl_vec *sample;
2255 gbr_init_shifted(cgbr);
2258 if (cgbr->shifted->empty)
2259 return isl_vec_alloc(cgbr->tab->mat->ctx, 0);
2261 sample = isl_tab_get_sample_value(cgbr->shifted);
2262 sample = isl_vec_ceil(sample);
2267 static struct isl_basic_set *drop_constant_terms(struct isl_basic_set *bset)
2274 for (i = 0; i < bset->n_eq; ++i)
2275 isl_int_set_si(bset->eq[i][0], 0);
2277 for (i = 0; i < bset->n_ineq; ++i)
2278 isl_int_set_si(bset->ineq[i][0], 0);
2283 static int use_shifted(struct isl_context_gbr *cgbr)
2285 return cgbr->tab->bset->n_eq == 0 && cgbr->tab->bset->n_div == 0;
2288 static struct isl_vec *gbr_get_sample(struct isl_context_gbr *cgbr)
2290 struct isl_basic_set *bset;
2291 struct isl_basic_set *cone;
2293 if (isl_tab_sample_is_integer(cgbr->tab))
2294 return isl_tab_get_sample_value(cgbr->tab);
2296 if (use_shifted(cgbr)) {
2297 struct isl_vec *sample;
2299 sample = gbr_get_shifted_sample(cgbr);
2300 if (!sample || sample->size > 0)
2303 isl_vec_free(sample);
2307 cgbr->cone = isl_tab_from_recession_cone(cgbr->tab->bset);
2310 cgbr->cone->bset = isl_basic_set_dup(cgbr->tab->bset);
2312 cgbr->cone = isl_tab_detect_implicit_equalities(cgbr->cone);
2316 if (cgbr->cone->n_dead == cgbr->cone->n_col) {
2317 struct isl_vec *sample;
2318 struct isl_tab_undo *snap;
2320 if (cgbr->tab->basis) {
2321 if (cgbr->tab->basis->n_col != 1 + cgbr->tab->n_var) {
2322 isl_mat_free(cgbr->tab->basis);
2323 cgbr->tab->basis = NULL;
2325 cgbr->tab->n_zero = 0;
2326 cgbr->tab->n_unbounded = 0;
2330 snap = isl_tab_snap(cgbr->tab);
2332 sample = isl_tab_sample(cgbr->tab);
2334 if (isl_tab_rollback(cgbr->tab, snap) < 0) {
2335 isl_vec_free(sample);
2342 cone = isl_basic_set_dup(cgbr->cone->bset);
2343 cone = drop_constant_terms(cone);
2344 cone = isl_basic_set_update_from_tab(cone, cgbr->cone);
2345 cone = isl_basic_set_underlying_set(cone);
2346 cone = isl_basic_set_gauss(cone, NULL);
2348 bset = isl_basic_set_dup(cgbr->tab->bset);
2349 bset = isl_basic_set_update_from_tab(bset, cgbr->tab);
2350 bset = isl_basic_set_underlying_set(bset);
2351 bset = isl_basic_set_gauss(bset, NULL);
2353 return isl_basic_set_sample_with_cone(bset, cone);
2356 static void check_gbr_integer_feasible(struct isl_context_gbr *cgbr)
2358 struct isl_vec *sample;
2363 if (cgbr->tab->empty)
2366 sample = gbr_get_sample(cgbr);
2370 if (sample->size == 0) {
2371 isl_vec_free(sample);
2372 cgbr->tab = isl_tab_mark_empty(cgbr->tab);
2376 cgbr->tab = isl_tab_add_sample(cgbr->tab, sample);
2380 isl_tab_free(cgbr->tab);
2384 static struct isl_tab *add_gbr_eq(struct isl_tab *tab, isl_int *eq)
2391 if (isl_tab_extend_cons(tab, 2) < 0)
2394 tab = isl_tab_add_eq(tab, eq);
2402 static void context_gbr_add_eq(struct isl_context *context, isl_int *eq,
2403 int check, int update)
2405 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2407 cgbr->tab = add_gbr_eq(cgbr->tab, eq);
2409 if (cgbr->cone && cgbr->cone->n_col != cgbr->cone->n_dead) {
2410 if (isl_tab_extend_cons(cgbr->cone, 2) < 0)
2412 cgbr->cone = isl_tab_add_eq(cgbr->cone, eq);
2416 int v = tab_has_valid_sample(cgbr->tab, eq, 1);
2420 check_gbr_integer_feasible(cgbr);
2423 cgbr->tab = check_samples(cgbr->tab, eq, 1);
2426 isl_tab_free(cgbr->tab);
2430 static void add_gbr_ineq(struct isl_context_gbr *cgbr, isl_int *ineq)
2435 if (isl_tab_extend_cons(cgbr->tab, 1) < 0)
2438 cgbr->tab = isl_tab_add_ineq(cgbr->tab, ineq);
2440 if (cgbr->shifted && !cgbr->shifted->empty && use_shifted(cgbr)) {
2443 dim = isl_basic_set_total_dim(cgbr->tab->bset);
2445 if (isl_tab_extend_cons(cgbr->shifted, 1) < 0)
2448 for (i = 0; i < dim; ++i) {
2449 if (!isl_int_is_neg(ineq[1 + i]))
2451 isl_int_add(ineq[0], ineq[0], ineq[1 + i]);
2454 cgbr->shifted = isl_tab_add_ineq(cgbr->shifted, ineq);
2456 for (i = 0; i < dim; ++i) {
2457 if (!isl_int_is_neg(ineq[1 + i]))
2459 isl_int_sub(ineq[0], ineq[0], ineq[1 + i]);
2463 if (cgbr->cone && cgbr->cone->n_col != cgbr->cone->n_dead) {
2464 if (isl_tab_extend_cons(cgbr->cone, 1) < 0)
2466 cgbr->cone = isl_tab_add_ineq(cgbr->cone, ineq);
2471 isl_tab_free(cgbr->tab);
2475 static void context_gbr_add_ineq(struct isl_context *context, isl_int *ineq,
2476 int check, int update)
2478 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2480 add_gbr_ineq(cgbr, ineq);
2485 int v = tab_has_valid_sample(cgbr->tab, ineq, 0);
2489 check_gbr_integer_feasible(cgbr);
2492 cgbr->tab = check_samples(cgbr->tab, ineq, 0);
2495 isl_tab_free(cgbr->tab);
2499 static enum isl_tab_row_sign context_gbr_ineq_sign(struct isl_context *context,
2500 isl_int *ineq, int strict)
2502 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2503 return tab_ineq_sign(cgbr->tab, ineq, strict);
2506 /* Check whether "ineq" can be added to the tableau without rendering
2509 static int context_gbr_test_ineq(struct isl_context *context, isl_int *ineq)
2511 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2512 struct isl_tab_undo *snap;
2513 struct isl_tab_undo *shifted_snap = NULL;
2514 struct isl_tab_undo *cone_snap = NULL;
2520 if (isl_tab_extend_cons(cgbr->tab, 1) < 0)
2523 snap = isl_tab_snap(cgbr->tab);
2525 shifted_snap = isl_tab_snap(cgbr->shifted);
2527 cone_snap = isl_tab_snap(cgbr->cone);
2528 add_gbr_ineq(cgbr, ineq);
2529 check_gbr_integer_feasible(cgbr);
2532 feasible = !cgbr->tab->empty;
2533 if (isl_tab_rollback(cgbr->tab, snap) < 0)
2536 if (isl_tab_rollback(cgbr->shifted, shifted_snap))
2538 } else if (cgbr->shifted) {
2539 isl_tab_free(cgbr->shifted);
2540 cgbr->shifted = NULL;
2543 if (isl_tab_rollback(cgbr->cone, cone_snap))
2545 } else if (cgbr->cone) {
2546 isl_tab_free(cgbr->cone);
2553 /* Return the column of the last of the variables associated to
2554 * a column that has a non-zero coefficient.
2555 * This function is called in a context where only coefficients
2556 * of parameters or divs can be non-zero.
2558 static int last_non_zero_var_col(struct isl_tab *tab, isl_int *p)
2562 unsigned dim = tab->n_var - tab->n_param - tab->n_div;
2564 if (tab->n_var == 0)
2567 for (i = tab->n_var - 1; i >= 0; --i) {
2568 if (i >= tab->n_param && i < tab->n_var - tab->n_div)
2570 if (tab->var[i].is_row)
2572 col = tab->var[i].index;
2573 if (!isl_int_is_zero(p[col]))
2580 /* Look through all the recently added equalities in the context
2581 * to see if we can propagate any of them to the main tableau.
2583 * The newly added equalities in the context are encoded as pairs
2584 * of inequalities starting at inequality "first".
2586 * We tentatively add each of these equalities to the main tableau
2587 * and if this happens to result in a row with a final coefficient
2588 * that is one or negative one, we use it to kill a column
2589 * in the main tableau. Otherwise, we discard the tentatively
2592 static void propagate_equalities(struct isl_context_gbr *cgbr,
2593 struct isl_tab *tab, unsigned first)
2596 struct isl_vec *eq = NULL;
2598 eq = isl_vec_alloc(tab->mat->ctx, 1 + tab->n_var);
2602 if (isl_tab_extend_cons(tab, (cgbr->tab->bset->n_ineq - first)/2) < 0)
2605 isl_seq_clr(eq->el + 1 + tab->n_param,
2606 tab->n_var - tab->n_param - tab->n_div);
2607 for (i = first; i < cgbr->tab->bset->n_ineq; i += 2) {
2610 struct isl_tab_undo *snap;
2611 snap = isl_tab_snap(tab);
2613 isl_seq_cpy(eq->el, cgbr->tab->bset->ineq[i], 1 + tab->n_param);
2614 isl_seq_cpy(eq->el + 1 + tab->n_var - tab->n_div,
2615 cgbr->tab->bset->ineq[i] + 1 + tab->n_param,
2618 r = isl_tab_add_row(tab, eq->el);
2621 r = tab->con[r].index;
2622 j = last_non_zero_var_col(tab, tab->mat->row[r] + 2 + tab->M);
2623 if (j < 0 || j < tab->n_dead ||
2624 !isl_int_is_one(tab->mat->row[r][0]) ||
2625 (!isl_int_is_one(tab->mat->row[r][2 + tab->M + j]) &&
2626 !isl_int_is_negone(tab->mat->row[r][2 + tab->M + j]))) {
2627 if (isl_tab_rollback(tab, snap) < 0)
2631 if (isl_tab_pivot(tab, r, j) < 0)
2633 if (isl_tab_kill_col(tab, j) < 0)
2636 tab = restore_lexmin(tab);
2644 isl_tab_free(cgbr->tab);
2648 static int context_gbr_detect_equalities(struct isl_context *context,
2649 struct isl_tab *tab)
2651 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2652 struct isl_ctx *ctx;
2654 enum isl_lp_result res;
2657 ctx = cgbr->tab->mat->ctx;
2660 cgbr->cone = isl_tab_from_recession_cone(cgbr->tab->bset);
2663 cgbr->cone->bset = isl_basic_set_dup(cgbr->tab->bset);
2665 cgbr->cone = isl_tab_detect_implicit_equalities(cgbr->cone);
2667 n_ineq = cgbr->tab->bset->n_ineq;
2668 cgbr->tab = isl_tab_detect_equalities(cgbr->tab, cgbr->cone);
2669 if (cgbr->tab && cgbr->tab->bset->n_ineq > n_ineq)
2670 propagate_equalities(cgbr, tab, n_ineq);
2674 isl_tab_free(cgbr->tab);
2679 static int context_gbr_get_div(struct isl_context *context, struct isl_tab *tab,
2680 struct isl_vec *div)
2682 return get_div(tab, context, div);
2685 static int context_gbr_add_div(struct isl_context *context, struct isl_vec *div,
2688 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2692 if (isl_tab_extend_cons(cgbr->cone, 3) < 0)
2694 if (isl_tab_extend_vars(cgbr->cone, 1) < 0)
2696 if (isl_tab_allocate_var(cgbr->cone) <0)
2699 cgbr->cone->bset = isl_basic_set_extend_dim(cgbr->cone->bset,
2700 isl_basic_set_get_dim(cgbr->cone->bset), 1, 0, 2);
2701 k = isl_basic_set_alloc_div(cgbr->cone->bset);
2704 isl_seq_cpy(cgbr->cone->bset->div[k], div->el, div->size);
2705 if (isl_tab_push(cgbr->cone, isl_tab_undo_bset_div) < 0)
2708 return context_tab_add_div(cgbr->tab, div, nonneg);
2711 static int context_gbr_best_split(struct isl_context *context,
2712 struct isl_tab *tab)
2714 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2715 struct isl_tab_undo *snap;
2718 snap = isl_tab_snap(cgbr->tab);
2719 r = best_split(tab, cgbr->tab);
2721 if (isl_tab_rollback(cgbr->tab, snap) < 0)
2727 static int context_gbr_is_empty(struct isl_context *context)
2729 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2732 return cgbr->tab->empty;
2735 struct isl_gbr_tab_undo {
2736 struct isl_tab_undo *tab_snap;
2737 struct isl_tab_undo *shifted_snap;
2738 struct isl_tab_undo *cone_snap;
2741 static void *context_gbr_save(struct isl_context *context)
2743 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2744 struct isl_gbr_tab_undo *snap;
2746 snap = isl_alloc_type(cgbr->tab->mat->ctx, struct isl_gbr_tab_undo);
2750 snap->tab_snap = isl_tab_snap(cgbr->tab);
2751 if (isl_tab_save_samples(cgbr->tab) < 0)
2755 snap->shifted_snap = isl_tab_snap(cgbr->shifted);
2757 snap->shifted_snap = NULL;
2760 snap->cone_snap = isl_tab_snap(cgbr->cone);
2762 snap->cone_snap = NULL;
2770 static void context_gbr_restore(struct isl_context *context, void *save)
2772 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2773 struct isl_gbr_tab_undo *snap = (struct isl_gbr_tab_undo *)save;
2776 if (isl_tab_rollback(cgbr->tab, snap->tab_snap) < 0) {
2777 isl_tab_free(cgbr->tab);
2781 if (snap->shifted_snap) {
2782 if (isl_tab_rollback(cgbr->shifted, snap->shifted_snap) < 0)
2784 } else if (cgbr->shifted) {
2785 isl_tab_free(cgbr->shifted);
2786 cgbr->shifted = NULL;
2789 if (snap->cone_snap) {
2790 if (isl_tab_rollback(cgbr->cone, snap->cone_snap) < 0)
2792 } else if (cgbr->cone) {
2793 isl_tab_free(cgbr->cone);
2802 isl_tab_free(cgbr->tab);
2806 static int context_gbr_is_ok(struct isl_context *context)
2808 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2812 static void context_gbr_invalidate(struct isl_context *context)
2814 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2815 isl_tab_free(cgbr->tab);
2819 static void context_gbr_free(struct isl_context *context)
2821 struct isl_context_gbr *cgbr = (struct isl_context_gbr *)context;
2822 isl_tab_free(cgbr->tab);
2823 isl_tab_free(cgbr->shifted);
2824 isl_tab_free(cgbr->cone);
2828 struct isl_context_op isl_context_gbr_op = {
2829 context_gbr_detect_nonnegative_parameters,
2830 context_gbr_peek_basic_set,
2831 context_gbr_peek_tab,
2833 context_gbr_add_ineq,
2834 context_gbr_ineq_sign,
2835 context_gbr_test_ineq,
2836 context_gbr_get_div,
2837 context_gbr_add_div,
2838 context_gbr_detect_equalities,
2839 context_gbr_best_split,
2840 context_gbr_is_empty,
2843 context_gbr_restore,
2844 context_gbr_invalidate,
2848 static struct isl_context *isl_context_gbr_alloc(struct isl_basic_set *dom)
2850 struct isl_context_gbr *cgbr;
2855 cgbr = isl_calloc_type(dom->ctx, struct isl_context_gbr);
2859 cgbr->context.op = &isl_context_gbr_op;
2861 cgbr->shifted = NULL;
2863 cgbr->tab = isl_tab_from_basic_set(dom);
2864 cgbr->tab = isl_tab_init_samples(cgbr->tab);
2867 cgbr->tab->bset = isl_basic_set_cow(isl_basic_set_copy(dom));
2868 if (!cgbr->tab->bset)
2870 check_gbr_integer_feasible(cgbr);
2872 return &cgbr->context;
2874 cgbr->context.op->free(&cgbr->context);
2878 static struct isl_context *isl_context_alloc(struct isl_basic_set *dom)
2883 if (dom->ctx->context == ISL_CONTEXT_LEXMIN)
2884 return isl_context_lex_alloc(dom);
2886 return isl_context_gbr_alloc(dom);
2889 /* Construct an isl_sol_map structure for accumulating the solution.
2890 * If track_empty is set, then we also keep track of the parts
2891 * of the context where there is no solution.
2892 * If max is set, then we are solving a maximization, rather than
2893 * a minimization problem, which means that the variables in the
2894 * tableau have value "M - x" rather than "M + x".
2896 static struct isl_sol_map *sol_map_init(struct isl_basic_map *bmap,
2897 struct isl_basic_set *dom, int track_empty, int max)
2899 struct isl_sol_map *sol_map;
2901 sol_map = isl_calloc_type(bset->ctx, struct isl_sol_map);
2906 sol_map->sol.add = &sol_map_add_wrap;
2907 sol_map->sol.free = &sol_map_free_wrap;
2908 sol_map->map = isl_map_alloc_dim(isl_basic_map_get_dim(bmap), 1,
2913 sol_map->sol.context = isl_context_alloc(dom);
2914 if (!sol_map->sol.context)
2918 sol_map->empty = isl_set_alloc_dim(isl_basic_set_get_dim(dom),
2919 1, ISL_SET_DISJOINT);
2920 if (!sol_map->empty)
2924 isl_basic_set_free(dom);
2927 isl_basic_set_free(dom);
2928 sol_map_free(sol_map);
2932 /* Check whether all coefficients of (non-parameter) variables
2933 * are non-positive, meaning that no pivots can be performed on the row.
2935 static int is_critical(struct isl_tab *tab, int row)
2938 unsigned off = 2 + tab->M;
2940 for (j = tab->n_dead; j < tab->n_col; ++j) {
2941 if (tab->col_var[j] >= 0 &&
2942 (tab->col_var[j] < tab->n_param ||
2943 tab->col_var[j] >= tab->n_var - tab->n_div))
2946 if (isl_int_is_pos(tab->mat->row[row][off + j]))
2953 /* Check whether the inequality represented by vec is strict over the integers,
2954 * i.e., there are no integer values satisfying the constraint with
2955 * equality. This happens if the gcd of the coefficients is not a divisor
2956 * of the constant term. If so, scale the constraint down by the gcd
2957 * of the coefficients.
2959 static int is_strict(struct isl_vec *vec)
2965 isl_seq_gcd(vec->el + 1, vec->size - 1, &gcd);
2966 if (!isl_int_is_one(gcd)) {
2967 strict = !isl_int_is_divisible_by(vec->el[0], gcd);
2968 isl_int_fdiv_q(vec->el[0], vec->el[0], gcd);
2969 isl_seq_scale_down(vec->el + 1, vec->el + 1, gcd, vec->size-1);
2976 /* Determine the sign of the given row of the main tableau.
2977 * The result is one of
2978 * isl_tab_row_pos: always non-negative; no pivot needed
2979 * isl_tab_row_neg: always non-positive; pivot
2980 * isl_tab_row_any: can be both positive and negative; split
2982 * We first handle some simple cases
2983 * - the row sign may be known already
2984 * - the row may be obviously non-negative
2985 * - the parametric constant may be equal to that of another row
2986 * for which we know the sign. This sign will be either "pos" or
2987 * "any". If it had been "neg" then we would have pivoted before.
2989 * If none of these cases hold, we check the value of the row for each
2990 * of the currently active samples. Based on the signs of these values
2991 * we make an initial determination of the sign of the row.
2993 * all zero -> unk(nown)
2994 * all non-negative -> pos
2995 * all non-positive -> neg
2996 * both negative and positive -> all
2998 * If we end up with "all", we are done.
2999 * Otherwise, we perform a check for positive and/or negative
3000 * values as follows.
3002 * samples neg unk pos
3008 * There is no special sign for "zero", because we can usually treat zero
3009 * as either non-negative or non-positive, whatever works out best.
3010 * However, if the row is "critical", meaning that pivoting is impossible
3011 * then we don't want to limp zero with the non-positive case, because
3012 * then we we would lose the solution for those values of the parameters
3013 * where the value of the row is zero. Instead, we treat 0 as non-negative
3014 * ensuring a split if the row can attain both zero and negative values.
3015 * The same happens when the original constraint was one that could not
3016 * be satisfied with equality by any integer values of the parameters.
3017 * In this case, we normalize the constraint, but then a value of zero
3018 * for the normalized constraint is actually a positive value for the
3019 * original constraint, so again we need to treat zero as non-negative.
3020 * In both these cases, we have the following decision tree instead:
3022 * all non-negative -> pos
3023 * all negative -> neg
3024 * both negative and non-negative -> all
3032 static enum isl_tab_row_sign row_sign(struct isl_tab *tab,
3033 struct isl_sol *sol, int row)
3035 struct isl_vec *ineq = NULL;
3036 int res = isl_tab_row_unknown;
3041 if (tab->row_sign[row] != isl_tab_row_unknown)
3042 return tab->row_sign[row];
3043 if (is_obviously_nonneg(tab, row))
3044 return isl_tab_row_pos;
3045 for (row2 = tab->n_redundant; row2 < tab->n_row; ++row2) {
3046 if (tab->row_sign[row2] == isl_tab_row_unknown)
3048 if (identical_parameter_line(tab, row, row2))
3049 return tab->row_sign[row2];
3052 critical = is_critical(tab, row);
3054 ineq = get_row_parameter_ineq(tab, row);
3058 strict = is_strict(ineq);
3060 res = sol->context->op->ineq_sign(sol->context, ineq->el,
3061 critical || strict);
3063 if (res == isl_tab_row_unknown || res == isl_tab_row_pos) {
3064 /* test for negative values */
3066 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3067 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3069 feasible = sol->context->op->test_ineq(sol->context, ineq->el);
3073 res = isl_tab_row_pos;
3075 res = (res == isl_tab_row_unknown) ? isl_tab_row_neg
3077 if (res == isl_tab_row_neg) {
3078 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3079 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3083 if (res == isl_tab_row_neg) {
3084 /* test for positive values */
3086 if (!critical && !strict)
3087 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3089 feasible = sol->context->op->test_ineq(sol->context, ineq->el);
3093 res = isl_tab_row_any;
3103 static struct isl_sol *find_solutions(struct isl_sol *sol, struct isl_tab *tab);
3105 /* Find solutions for values of the parameters that satisfy the given
3108 * We currently take a snapshot of the context tableau that is reset
3109 * when we return from this function, while we make a copy of the main
3110 * tableau, leaving the original main tableau untouched.
3111 * These are fairly arbitrary choices. Making a copy also of the context
3112 * tableau would obviate the need to undo any changes made to it later,
3113 * while taking a snapshot of the main tableau could reduce memory usage.
3114 * If we were to switch to taking a snapshot of the main tableau,
3115 * we would have to keep in mind that we need to save the row signs
3116 * and that we need to do this before saving the current basis
3117 * such that the basis has been restore before we restore the row signs.
3119 static struct isl_sol *find_in_pos(struct isl_sol *sol,
3120 struct isl_tab *tab, isl_int *ineq)
3126 saved = sol->context->op->save(sol->context);
3128 tab = isl_tab_dup(tab);
3132 sol->context->op->add_ineq(sol->context, ineq, 0, 1);
3134 sol = find_solutions(sol, tab);
3136 sol->context->op->restore(sol->context, saved);
3143 /* Record the absence of solutions for those values of the parameters
3144 * that do not satisfy the given inequality with equality.
3146 static struct isl_sol *no_sol_in_strict(struct isl_sol *sol,
3147 struct isl_tab *tab, struct isl_vec *ineq)
3154 saved = sol->context->op->save(sol->context);
3156 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3158 sol->context->op->add_ineq(sol->context, ineq->el, 1, 0);
3164 sol = sol->add(sol, tab);
3167 isl_int_add_ui(ineq->el[0], ineq->el[0], 1);
3169 sol->context->op->restore(sol->context, saved);
3176 /* Compute the lexicographic minimum of the set represented by the main
3177 * tableau "tab" within the context "sol->context_tab".
3178 * On entry the sample value of the main tableau is lexicographically
3179 * less than or equal to this lexicographic minimum.
3180 * Pivots are performed until a feasible point is found, which is then
3181 * necessarily equal to the minimum, or until the tableau is found to
3182 * be infeasible. Some pivots may need to be performed for only some
3183 * feasible values of the context tableau. If so, the context tableau
3184 * is split into a part where the pivot is needed and a part where it is not.
3186 * Whenever we enter the main loop, the main tableau is such that no
3187 * "obvious" pivots need to be performed on it, where "obvious" means
3188 * that the given row can be seen to be negative without looking at
3189 * the context tableau. In particular, for non-parametric problems,
3190 * no pivots need to be performed on the main tableau.
3191 * The caller of find_solutions is responsible for making this property
3192 * hold prior to the first iteration of the loop, while restore_lexmin
3193 * is called before every other iteration.
3195 * Inside the main loop, we first examine the signs of the rows of
3196 * the main tableau within the context of the context tableau.
3197 * If we find a row that is always non-positive for all values of
3198 * the parameters satisfying the context tableau and negative for at
3199 * least one value of the parameters, we perform the appropriate pivot
3200 * and start over. An exception is the case where no pivot can be
3201 * performed on the row. In this case, we require that the sign of
3202 * the row is negative for all values of the parameters (rather than just
3203 * non-positive). This special case is handled inside row_sign, which
3204 * will say that the row can have any sign if it determines that it can
3205 * attain both negative and zero values.
3207 * If we can't find a row that always requires a pivot, but we can find
3208 * one or more rows that require a pivot for some values of the parameters
3209 * (i.e., the row can attain both positive and negative signs), then we split
3210 * the context tableau into two parts, one where we force the sign to be
3211 * non-negative and one where we force is to be negative.
3212 * The non-negative part is handled by a recursive call (through find_in_pos).
3213 * Upon returning from this call, we continue with the negative part and
3214 * perform the required pivot.
3216 * If no such rows can be found, all rows are non-negative and we have
3217 * found a (rational) feasible point. If we only wanted a rational point
3219 * Otherwise, we check if all values of the sample point of the tableau
3220 * are integral for the variables. If so, we have found the minimal
3221 * integral point and we are done.
3222 * If the sample point is not integral, then we need to make a distinction
3223 * based on whether the constant term is non-integral or the coefficients
3224 * of the parameters. Furthermore, in order to decide how to handle
3225 * the non-integrality, we also need to know whether the coefficients
3226 * of the other columns in the tableau are integral. This leads
3227 * to the following table. The first two rows do not correspond
3228 * to a non-integral sample point and are only mentioned for completeness.
3230 * constant parameters other
3233 * int int rat | -> no problem
3235 * rat int int -> fail
3237 * rat int rat -> cut
3240 * rat rat rat | -> parametric cut
3243 * rat rat int | -> split context
3245 * If the parametric constant is completely integral, then there is nothing
3246 * to be done. If the constant term is non-integral, but all the other
3247 * coefficient are integral, then there is nothing that can be done
3248 * and the tableau has no integral solution.
3249 * If, on the other hand, one or more of the other columns have rational
3250 * coeffcients, but the parameter coefficients are all integral, then
3251 * we can perform a regular (non-parametric) cut.
3252 * Finally, if there is any parameter coefficient that is non-integral,
3253 * then we need to involve the context tableau. There are two cases here.
3254 * If at least one other column has a rational coefficient, then we
3255 * can perform a parametric cut in the main tableau by adding a new
3256 * integer division in the context tableau.
3257 * If all other columns have integral coefficients, then we need to
3258 * enforce that the rational combination of parameters (c + \sum a_i y_i)/m
3259 * is always integral. We do this by introducing an integer division
3260 * q = floor((c + \sum a_i y_i)/m) and stipulating that its argument should
3261 * always be integral in the context tableau, i.e., m q = c + \sum a_i y_i.
3262 * Since q is expressed in the tableau as
3263 * c + \sum a_i y_i - m q >= 0
3264 * -c - \sum a_i y_i + m q + m - 1 >= 0
3265 * it is sufficient to add the inequality
3266 * -c - \sum a_i y_i + m q >= 0
3267 * In the part of the context where this inequality does not hold, the
3268 * main tableau is marked as being empty.
3270 static struct isl_sol *find_solutions(struct isl_sol *sol, struct isl_tab *tab)
3272 struct isl_context *context;
3277 context = sol->context;
3281 if (context->op->is_empty(context))
3284 for (; tab && !tab->empty; tab = restore_lexmin(tab)) {
3291 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3292 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
3294 sgn = row_sign(tab, sol, row);
3297 tab->row_sign[row] = sgn;
3298 if (sgn == isl_tab_row_any)
3300 if (sgn == isl_tab_row_any && split == -1)
3302 if (sgn == isl_tab_row_neg)
3305 if (row < tab->n_row)
3308 struct isl_vec *ineq;
3310 split = context->op->best_split(context, tab);
3313 ineq = get_row_parameter_ineq(tab, split);
3317 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3318 if (!isl_tab_var_from_row(tab, row)->is_nonneg)
3320 if (tab->row_sign[row] == isl_tab_row_any)
3321 tab->row_sign[row] = isl_tab_row_unknown;
3323 tab->row_sign[split] = isl_tab_row_pos;
3324 sol = find_in_pos(sol, tab, ineq->el);
3325 tab->row_sign[split] = isl_tab_row_neg;
3327 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3328 isl_int_sub_ui(ineq->el[0], ineq->el[0], 1);
3329 context->op->add_ineq(context, ineq->el, 0, 1);
3337 row = first_non_integer(tab, &flags);
3340 if (ISL_FL_ISSET(flags, I_PAR)) {
3341 if (ISL_FL_ISSET(flags, I_VAR)) {
3342 tab = isl_tab_mark_empty(tab);
3345 row = add_cut(tab, row);
3346 } else if (ISL_FL_ISSET(flags, I_VAR)) {
3347 struct isl_vec *div;
3348 struct isl_vec *ineq;
3350 div = get_row_split_div(tab, row);
3353 d = context->op->get_div(context, tab, div);
3357 ineq = ineq_for_div(context->op->peek_basic_set(context), d);
3358 sol = no_sol_in_strict(sol, tab, ineq);
3359 isl_seq_neg(ineq->el, ineq->el, ineq->size);
3360 context->op->add_ineq(context, ineq->el, 1, 1);
3362 if (!sol || !context->op->is_ok(context))
3364 tab = set_row_cst_to_div(tab, row, d);
3366 row = add_parametric_cut(tab, row, context);
3371 sol = sol->add(sol, tab);
3380 /* Compute the lexicographic minimum of the set represented by the main
3381 * tableau "tab" within the context "sol->context_tab".
3383 * As a preprocessing step, we first transfer all the purely parametric
3384 * equalities from the main tableau to the context tableau, i.e.,
3385 * parameters that have been pivoted to a row.
3386 * These equalities are ignored by the main algorithm, because the
3387 * corresponding rows may not be marked as being non-negative.
3388 * In parts of the context where the added equality does not hold,
3389 * the main tableau is marked as being empty.
3391 static struct isl_sol *find_solutions_main(struct isl_sol *sol,
3392 struct isl_tab *tab)
3396 for (row = tab->n_redundant; row < tab->n_row; ++row) {
3400 if (tab->row_var[row] < 0)
3402 if (tab->row_var[row] >= tab->n_param &&
3403 tab->row_var[row] < tab->n_var - tab->n_div)
3405 if (tab->row_var[row] < tab->n_param)
3406 p = tab->row_var[row];
3408 p = tab->row_var[row]
3409 + tab->n_param - (tab->n_var - tab->n_div);
3411 eq = isl_vec_alloc(tab->mat->ctx, 1+tab->n_param+tab->n_div);
3412 get_row_parameter_line(tab, row, eq->el);
3413 isl_int_neg(eq->el[1 + p], tab->mat->row[row][0]);
3414 eq = isl_vec_normalize(eq);
3416 sol = no_sol_in_strict(sol, tab, eq);
3418 isl_seq_neg(eq->el, eq->el, eq->size);
3419 sol = no_sol_in_strict(sol, tab, eq);
3420 isl_seq_neg(eq->el, eq->el, eq->size);
3422 sol->context->op->add_eq(sol->context, eq->el, 1, 1);
3426 if (isl_tab_mark_redundant(tab, row) < 0)
3429 if (sol->context->op->is_empty(sol->context))
3432 row = tab->n_redundant - 1;
3435 return find_solutions(sol, tab);
3442 static struct isl_sol_map *sol_map_find_solutions(struct isl_sol_map *sol_map,
3443 struct isl_tab *tab)
3445 return (struct isl_sol_map *)find_solutions_main(&sol_map->sol, tab);
3448 /* Check if integer division "div" of "dom" also occurs in "bmap".
3449 * If so, return its position within the divs.
3450 * If not, return -1.
3452 static int find_context_div(struct isl_basic_map *bmap,
3453 struct isl_basic_set *dom, unsigned div)
3456 unsigned b_dim = isl_dim_total(bmap->dim);
3457 unsigned d_dim = isl_dim_total(dom->dim);
3459 if (isl_int_is_zero(dom->div[div][0]))
3461 if (isl_seq_first_non_zero(dom->div[div] + 2 + d_dim, dom->n_div) != -1)
3464 for (i = 0; i < bmap->n_div; ++i) {
3465 if (isl_int_is_zero(bmap->div[i][0]))
3467 if (isl_seq_first_non_zero(bmap->div[i] + 2 + d_dim,
3468 (b_dim - d_dim) + bmap->n_div) != -1)
3470 if (isl_seq_eq(bmap->div[i], dom->div[div], 2 + d_dim))
3476 /* The correspondence between the variables in the main tableau,
3477 * the context tableau, and the input map and domain is as follows.
3478 * The first n_param and the last n_div variables of the main tableau
3479 * form the variables of the context tableau.
3480 * In the basic map, these n_param variables correspond to the
3481 * parameters and the input dimensions. In the domain, they correspond
3482 * to the parameters and the set dimensions.
3483 * The n_div variables correspond to the integer divisions in the domain.
3484 * To ensure that everything lines up, we may need to copy some of the
3485 * integer divisions of the domain to the map. These have to be placed
3486 * in the same order as those in the context and they have to be placed
3487 * after any other integer divisions that the map may have.
3488 * This function performs the required reordering.
3490 static struct isl_basic_map *align_context_divs(struct isl_basic_map *bmap,
3491 struct isl_basic_set *dom)
3497 for (i = 0; i < dom->n_div; ++i)
3498 if (find_context_div(bmap, dom, i) != -1)
3500 other = bmap->n_div - common;
3501 if (dom->n_div - common > 0) {
3502 bmap = isl_basic_map_extend_dim(bmap, isl_dim_copy(bmap->dim),
3503 dom->n_div - common, 0, 0);
3507 for (i = 0; i < dom->n_div; ++i) {
3508 int pos = find_context_div(bmap, dom, i);
3510 pos = isl_basic_map_alloc_div(bmap);
3513 isl_int_set_si(bmap->div[pos][0], 0);
3515 if (pos != other + i)
3516 isl_basic_map_swap_div(bmap, pos, other + i);
3520 isl_basic_map_free(bmap);
3524 /* Compute the lexicographic minimum (or maximum if "max" is set)
3525 * of "bmap" over the domain "dom" and return the result as a map.
3526 * If "empty" is not NULL, then *empty is assigned a set that
3527 * contains those parts of the domain where there is no solution.
3528 * If "bmap" is marked as rational (ISL_BASIC_MAP_RATIONAL),
3529 * then we compute the rational optimum. Otherwise, we compute
3530 * the integral optimum.
3532 * We perform some preprocessing. As the PILP solver does not
3533 * handle implicit equalities very well, we first make sure all
3534 * the equalities are explicitly available.
3535 * We also make sure the divs in the domain are properly order,
3536 * because they will be added one by one in the given order
3537 * during the construction of the solution map.
3539 struct isl_map *isl_tab_basic_map_partial_lexopt(
3540 struct isl_basic_map *bmap, struct isl_basic_set *dom,
3541 struct isl_set **empty, int max)
3543 struct isl_tab *tab;
3544 struct isl_map *result = NULL;
3545 struct isl_sol_map *sol_map = NULL;
3546 struct isl_context *context;
3553 isl_assert(bmap->ctx,
3554 isl_basic_map_compatible_domain(bmap, dom), goto error);
3556 bmap = isl_basic_map_detect_equalities(bmap);
3559 dom = isl_basic_set_order_divs(dom);
3560 bmap = align_context_divs(bmap, dom);
3562 sol_map = sol_map_init(bmap, dom, !!empty, max);
3566 context = sol_map->sol.context;
3567 if (isl_basic_set_fast_is_empty(context->op->peek_basic_set(context)))
3569 else if (isl_basic_map_fast_is_empty(bmap))
3570 sol_map = add_empty(sol_map);
3572 tab = tab_for_lexmin(bmap,
3573 context->op->peek_basic_set(context), 1, max);
3574 tab = context->op->detect_nonnegative_parameters(context, tab);
3575 sol_map = sol_map_find_solutions(sol_map, tab);
3580 result = isl_map_copy(sol_map->map);
3582 *empty = isl_set_copy(sol_map->empty);
3583 sol_map_free(sol_map);
3584 isl_basic_map_free(bmap);
3587 sol_map_free(sol_map);
3588 isl_basic_map_free(bmap);
3592 struct isl_sol_for {
3594 int (*fn)(__isl_take isl_basic_set *dom,
3595 __isl_take isl_mat *map, void *user);
3600 static void sol_for_free(struct isl_sol_for *sol_for)
3602 if (sol_for->sol.context)
3603 sol_for->sol.context->op->free(sol_for->sol.context);
3607 static void sol_for_free_wrap(struct isl_sol *sol)
3609 sol_for_free((struct isl_sol_for *)sol);
3612 /* Add the solution identified by the tableau and the context tableau.
3614 * See documentation of sol_map_add for more details.
3616 * Instead of constructing a basic map, this function calls a user
3617 * defined function with the current context as a basic set and
3618 * an affine matrix reprenting the relation between the input and output.
3619 * The number of rows in this matrix is equal to one plus the number
3620 * of output variables. The number of columns is equal to one plus
3621 * the total dimension of the context, i.e., the number of parameters,
3622 * input variables and divs. Since some of the columns in the matrix
3623 * may refer to the divs, the basic set is not simplified.
3624 * (Simplification may reorder or remove divs.)
3626 static struct isl_sol_for *sol_for_add(struct isl_sol_for *sol,
3627 struct isl_tab *tab)
3629 struct isl_basic_set *bset;
3630 struct isl_mat *mat = NULL;
3643 n_out = tab->n_var - tab->n_param - tab->n_div;
3644 mat = isl_mat_alloc(tab->mat->ctx, 1 + n_out, 1 + tab->n_param + tab->n_div);
3648 isl_seq_clr(mat->row[0] + 1, mat->n_col - 1);
3649 isl_int_set_si(mat->row[0][0], 1);
3650 for (row = 0; row < n_out; ++row) {
3651 int i = tab->n_param + row;
3654 isl_seq_clr(mat->row[1 + row], mat->n_col);
3655 if (!tab->var[i].is_row)
3658 r = tab->var[i].index;
3661 isl_assert(mat->ctx, isl_int_eq(tab->mat->row[r][2],
3662 tab->mat->row[r][0]),
3664 isl_int_set(mat->row[1 + row][0], tab->mat->row[r][1]);
3665 for (j = 0; j < tab->n_param; ++j) {
3667 if (tab->var[j].is_row)
3669 col = tab->var[j].index;
3670 isl_int_set(mat->row[1 + row][1 + j],
3671 tab->mat->row[r][off + col]);
3673 for (j = 0; j < tab->n_div; ++j) {
3675 if (tab->var[tab->n_var - tab->n_div+j].is_row)
3677 col = tab->var[tab->n_var - tab->n_div+j].index;
3678 isl_int_set(mat->row[1 + row][1 + tab->n_param + j],
3679 tab->mat->row[r][off + col]);
3681 if (!isl_int_is_one(tab->mat->row[r][0]))
3682 isl_seq_scale_down(mat->row[1 + row], mat->row[1 + row],
3683 tab->mat->row[r][0], mat->n_col);
3685 isl_seq_neg(mat->row[1 + row], mat->row[1 + row],
3689 bset = sol->sol.context->op->peek_basic_set(sol->sol.context);
3690 bset = isl_basic_set_dup(bset);
3691 bset = isl_basic_set_finalize(bset);
3693 if (sol->fn(bset, isl_mat_copy(mat), sol->user) < 0)
3700 sol_free(&sol->sol);
3704 static struct isl_sol *sol_for_add_wrap(struct isl_sol *sol,
3705 struct isl_tab *tab)
3707 return (struct isl_sol *)sol_for_add((struct isl_sol_for *)sol, tab);
3710 static struct isl_sol_for *sol_for_init(struct isl_basic_map *bmap, int max,
3711 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
3715 struct isl_sol_for *sol_for = NULL;
3716 struct isl_dim *dom_dim;
3717 struct isl_basic_set *dom = NULL;
3719 sol_for = isl_calloc_type(bset->ctx, struct isl_sol_for);
3723 dom_dim = isl_dim_domain(isl_dim_copy(bmap->dim));
3724 dom = isl_basic_set_universe(dom_dim);
3727 sol_for->user = user;
3729 sol_for->sol.add = &sol_for_add_wrap;
3730 sol_for->sol.free = &sol_for_free_wrap;
3732 sol_for->sol.context = isl_context_alloc(dom);
3733 if (!sol_for->sol.context)
3736 isl_basic_set_free(dom);
3739 isl_basic_set_free(dom);
3740 sol_for_free(sol_for);
3744 static struct isl_sol_for *sol_for_find_solutions(struct isl_sol_for *sol_for,
3745 struct isl_tab *tab)
3747 return (struct isl_sol_for *)find_solutions_main(&sol_for->sol, tab);
3750 int isl_basic_map_foreach_lexopt(__isl_keep isl_basic_map *bmap, int max,
3751 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
3755 struct isl_sol_for *sol_for = NULL;
3757 bmap = isl_basic_map_copy(bmap);
3761 bmap = isl_basic_map_detect_equalities(bmap);
3762 sol_for = sol_for_init(bmap, max, fn, user);
3764 if (isl_basic_map_fast_is_empty(bmap))
3767 struct isl_tab *tab;
3768 struct isl_context *context = sol_for->sol.context;
3769 tab = tab_for_lexmin(bmap,
3770 context->op->peek_basic_set(context), 1, max);
3771 tab = context->op->detect_nonnegative_parameters(context, tab);
3772 sol_for = sol_for_find_solutions(sol_for, tab);
3777 sol_for_free(sol_for);
3778 isl_basic_map_free(bmap);
3781 sol_for_free(sol_for);
3782 isl_basic_map_free(bmap);
3786 int isl_basic_map_foreach_lexmin(__isl_keep isl_basic_map *bmap,
3787 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
3791 return isl_basic_map_foreach_lexopt(bmap, 0, fn, user);
3794 int isl_basic_map_foreach_lexmax(__isl_keep isl_basic_map *bmap,
3795 int (*fn)(__isl_take isl_basic_set *dom, __isl_take isl_mat *map,
3799 return isl_basic_map_foreach_lexopt(bmap, 1, fn, user);