X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=isl_sample.c;h=c6a0f314425b0bc2d4683589997a3034b652abe0;hb=de51a9bc4da5dd3f1f9f57c2362da6f9752c44e0;hp=13faa3b08060047da9cbe3ecfb85f16248d1c115;hpb=e18f50ef6f40c2325dcf07da8fc2f960e6f0f9b9;p=platform%2Fupstream%2Fisl.git

diff --git a/isl_sample.c b/isl_sample.c
index 13faa3b..c6a0f31 100644
--- a/isl_sample.c
+++ b/isl_sample.c
@@ -1,22 +1,25 @@
 /*
  * Copyright 2008-2009 Katholieke Universiteit Leuven
  *
- * Use of this software is governed by the GNU LGPLv2.1 license
+ * Use of this software is governed by the MIT license
  *
  * Written by Sven Verdoolaege, K.U.Leuven, Departement
  * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
  */
 
+#include <isl_ctx_private.h>
+#include <isl_map_private.h>
 #include "isl_sample.h"
 #include "isl_sample_piplib.h"
-#include "isl_vec.h"
-#include "isl_mat.h"
-#include "isl_seq.h"
-#include "isl_map_private.h"
+#include <isl/vec.h>
+#include <isl/mat.h>
+#include <isl/seq.h>
 #include "isl_equalities.h"
 #include "isl_tab.h"
 #include "isl_basis_reduction.h"
+#include <isl_factorization.h>
 #include <isl_point_private.h>
+#include <isl_options_private.h>
 
 static struct isl_vec *empty_sample(struct isl_basic_set *bset)
 {
@@ -55,12 +58,16 @@ static struct isl_vec *interval_sample(struct isl_basic_set *bset)
 	bset = isl_basic_set_simplify(bset);
 	if (!bset)
 		return NULL;
-	if (isl_basic_set_fast_is_empty(bset))
+	if (isl_basic_set_plain_is_empty(bset))
 		return empty_sample(bset);
 	if (bset->n_eq == 0 && bset->n_ineq == 0)
 		return zero_sample(bset);
 
 	sample = isl_vec_alloc(bset->ctx, 2);
+	if (!sample)
+		goto error;
+	if (!bset)
+		return NULL;
 	isl_int_set_si(sample->block.data[0], 1);
 
 	if (bset->n_eq > 0) {
@@ -340,6 +347,105 @@ static struct isl_mat *initial_basis(struct isl_tab *tab)
 	return Q;
 }
 
+/* Compute the minimum of the current ("level") basis row over "tab"
+ * and store the result in position "level" of "min".
+ */
+static enum isl_lp_result compute_min(isl_ctx *ctx, struct isl_tab *tab,
+	__isl_keep isl_vec *min, int level)
+{
+	return isl_tab_min(tab, tab->basis->row[1 + level],
+			    ctx->one, &min->el[level], NULL, 0);
+}
+
+/* Compute the maximum of the current ("level") basis row over "tab"
+ * and store the result in position "level" of "max".
+ */
+static enum isl_lp_result compute_max(isl_ctx *ctx, struct isl_tab *tab,
+	__isl_keep isl_vec *max, int level)
+{
+	enum isl_lp_result res;
+	unsigned dim = tab->n_var;
+
+	isl_seq_neg(tab->basis->row[1 + level] + 1,
+		    tab->basis->row[1 + level] + 1, dim);
+	res = isl_tab_min(tab, tab->basis->row[1 + level],
+		    ctx->one, &max->el[level], NULL, 0);
+	isl_seq_neg(tab->basis->row[1 + level] + 1,
+		    tab->basis->row[1 + level] + 1, dim);
+	isl_int_neg(max->el[level], max->el[level]);
+
+	return res;
+}
+
+/* Perform a greedy search for an integer point in the set represented
+ * by "tab", given that the minimal rational value (rounded up to the
+ * nearest integer) at "level" is smaller than the maximal rational
+ * value (rounded down to the nearest integer).
+ *
+ * Return 1 if we have found an integer point (if tab->n_unbounded > 0
+ * then we may have only found integer values for the bounded dimensions
+ * and it is the responsibility of the caller to extend this solution
+ * to the unbounded dimensions).
+ * Return 0 if greedy search did not result in a solution.
+ * Return -1 if some error occurred.
+ *
+ * We assign a value half-way between the minimum and the maximum
+ * to the current dimension and check if the minimal value of the
+ * next dimension is still smaller than (or equal) to the maximal value.
+ * We continue this process until either
+ * - the minimal value (rounded up) is greater than the maximal value
+ *	(rounded down).  In this case, greedy search has failed.
+ * - we have exhausted all bounded dimensions, meaning that we have
+ *	found a solution.
+ * - the sample value of the tableau is integral.
+ * - some error has occurred.
+ */
+static int greedy_search(isl_ctx *ctx, struct isl_tab *tab,
+	__isl_keep isl_vec *min, __isl_keep isl_vec *max, int level)
+{
+	struct isl_tab_undo *snap;
+	enum isl_lp_result res;
+
+	snap = isl_tab_snap(tab);
+
+	do {
+		isl_int_add(tab->basis->row[1 + level][0],
+			    min->el[level], max->el[level]);
+		isl_int_fdiv_q_ui(tab->basis->row[1 + level][0],
+			    tab->basis->row[1 + level][0], 2);
+		isl_int_neg(tab->basis->row[1 + level][0],
+			    tab->basis->row[1 + level][0]);
+		if (isl_tab_add_valid_eq(tab, tab->basis->row[1 + level]) < 0)
+			return -1;
+		isl_int_set_si(tab->basis->row[1 + level][0], 0);
+
+		if (++level >= tab->n_var - tab->n_unbounded)
+			return 1;
+		if (isl_tab_sample_is_integer(tab))
+			return 1;
+
+		res = compute_min(ctx, tab, min, level);
+		if (res == isl_lp_error)
+			return -1;
+		if (res != isl_lp_ok)
+			isl_die(ctx, isl_error_internal,
+				"expecting bounded rational solution",
+				return -1);
+		res = compute_max(ctx, tab, max, level);
+		if (res == isl_lp_error)
+			return -1;
+		if (res != isl_lp_ok)
+			isl_die(ctx, isl_error_internal,
+				"expecting bounded rational solution",
+				return -1);
+	} while (isl_int_le(min->el[level], max->el[level]));
+
+	if (isl_tab_rollback(tab, snap) < 0)
+		return -1;
+
+	return 0;
+}
+
 /* Given a tableau representing a set, find and return
  * an integer point in the set, if there is any.
  *
@@ -379,6 +485,9 @@ static struct isl_mat *initial_basis(struct isl_tab *tab)
  * basis vector.  "init" is true if we want the first value at the current
  * level and false if we want the next value.
  *
+ * At the start of each level, we first check if we can find a solution
+ * using greedy search.  If not, we continue with the exhaustive search.
+ *
  * The initial basis is the identity matrix.  If the range in some direction
  * contains more than one integer value, we perform basis reduction based
  * on the value of ctx->opt->gbr
@@ -448,34 +557,38 @@ struct isl_vec *isl_tab_sample(struct isl_tab *tab)
 	reduced = 0;
 
 	while (level >= 0) {
-		int empty = 0;
 		if (init) {
-			res = isl_tab_min(tab, tab->basis->row[1 + level],
-				    ctx->one, &min->el[level], NULL, 0);
-			if (res == isl_lp_empty)
-				empty = 1;
-			isl_assert(ctx, res != isl_lp_unbounded, goto error);
+			int choice;
+
+			res = compute_min(ctx, tab, min, level);
 			if (res == isl_lp_error)
 				goto error;
-			if (!empty && isl_tab_sample_is_integer(tab))
+			if (res != isl_lp_ok)
+				isl_die(ctx, isl_error_internal,
+					"expecting bounded rational solution",
+					goto error);
+			if (isl_tab_sample_is_integer(tab))
 				break;
-			isl_seq_neg(tab->basis->row[1 + level] + 1,
-				    tab->basis->row[1 + level] + 1, dim);
-			res = isl_tab_min(tab, tab->basis->row[1 + level],
-				    ctx->one, &max->el[level], NULL, 0);
-			isl_seq_neg(tab->basis->row[1 + level] + 1,
-				    tab->basis->row[1 + level] + 1, dim);
-			isl_int_neg(max->el[level], max->el[level]);
-			if (res == isl_lp_empty)
-				empty = 1;
-			isl_assert(ctx, res != isl_lp_unbounded, goto error);
+			res = compute_max(ctx, tab, max, level);
 			if (res == isl_lp_error)
 				goto error;
-			if (!empty && isl_tab_sample_is_integer(tab))
+			if (res != isl_lp_ok)
+				isl_die(ctx, isl_error_internal,
+					"expecting bounded rational solution",
+					goto error);
+			if (isl_tab_sample_is_integer(tab))
 				break;
-			if (!empty && !reduced &&
-			    ctx->opt->gbr != ISL_GBR_NEVER &&
-			    isl_int_lt(min->el[level], max->el[level])) {
+			choice = isl_int_lt(min->el[level], max->el[level]);
+			if (choice) {
+				int g;
+				g = greedy_search(ctx, tab, min, max, level);
+				if (g < 0)
+					goto error;
+				if (g)
+					break;
+			}
+			if (!reduced && choice &&
+			    ctx->opt->gbr != ISL_GBR_NEVER) {
 				unsigned gbr_only_first;
 				if (ctx->opt->gbr == ISL_GBR_ONCE)
 					ctx->opt->gbr = ISL_GBR_NEVER;
@@ -495,7 +608,7 @@ struct isl_vec *isl_tab_sample(struct isl_tab *tab)
 		} else
 			isl_int_add_ui(min->el[level], min->el[level], 1);
 
-		if (empty || isl_int_gt(min->el[level], max->el[level])) {
+		if (isl_int_gt(min->el[level], max->el[level])) {
 			level--;
 			init = 0;
 			if (level >= 0)
@@ -504,7 +617,8 @@ struct isl_vec *isl_tab_sample(struct isl_tab *tab)
 			continue;
 		}
 		isl_int_neg(tab->basis->row[1 + level][0], min->el[level]);
-		tab = isl_tab_add_valid_eq(tab, tab->basis->row[1 + level]);
+		if (isl_tab_add_valid_eq(tab, tab->basis->row[1 + level]) < 0)
+			goto error;
 		isl_int_set_si(tab->basis->row[1 + level][0], 0);
 		if (level + tab->n_unbounded < dim - 1) {
 			++level;
@@ -541,6 +655,76 @@ error:
 	return NULL;
 }
 
+static struct isl_vec *sample_bounded(struct isl_basic_set *bset);
+
+/* Compute a sample point of the given basic set, based on the given,
+ * non-trivial factorization.
+ */
+static __isl_give isl_vec *factored_sample(__isl_take isl_basic_set *bset,
+	__isl_take isl_factorizer *f)
+{
+	int i, n;
+	isl_vec *sample = NULL;
+	isl_ctx *ctx;
+	unsigned nparam;
+	unsigned nvar;
+
+	ctx = isl_basic_set_get_ctx(bset);
+	if (!ctx)
+		goto error;
+
+	nparam = isl_basic_set_dim(bset, isl_dim_param);
+	nvar = isl_basic_set_dim(bset, isl_dim_set);
+
+	sample = isl_vec_alloc(ctx, 1 + isl_basic_set_total_dim(bset));
+	if (!sample)
+		goto error;
+	isl_int_set_si(sample->el[0], 1);
+
+	bset = isl_morph_basic_set(isl_morph_copy(f->morph), bset);
+
+	for (i = 0, n = 0; i < f->n_group; ++i) {
+		isl_basic_set *bset_i;
+		isl_vec *sample_i;
+
+		bset_i = isl_basic_set_copy(bset);
+		bset_i = isl_basic_set_drop_constraints_involving(bset_i,
+			    nparam + n + f->len[i], nvar - n - f->len[i]);
+		bset_i = isl_basic_set_drop_constraints_involving(bset_i,
+			    nparam, n);
+		bset_i = isl_basic_set_drop(bset_i, isl_dim_set,
+			    n + f->len[i], nvar - n - f->len[i]);
+		bset_i = isl_basic_set_drop(bset_i, isl_dim_set, 0, n);
+
+		sample_i = sample_bounded(bset_i);
+		if (!sample_i)
+			goto error;
+		if (sample_i->size == 0) {
+			isl_basic_set_free(bset);
+			isl_factorizer_free(f);
+			isl_vec_free(sample);
+			return sample_i;
+		}
+		isl_seq_cpy(sample->el + 1 + nparam + n,
+			    sample_i->el + 1, f->len[i]);
+		isl_vec_free(sample_i);
+
+		n += f->len[i];
+	}
+
+	f->morph = isl_morph_inverse(f->morph);
+	sample = isl_morph_vec(isl_morph_copy(f->morph), sample);
+
+	isl_basic_set_free(bset);
+	isl_factorizer_free(f);
+	return sample;
+error:
+	isl_basic_set_free(bset);
+	isl_factorizer_free(f);
+	isl_vec_free(sample);
+	return NULL;
+}
+
 /* Given a basic set that is known to be bounded, find and return
  * an integer point in the basic set, if there is any.
  *
@@ -554,11 +738,12 @@ static struct isl_vec *sample_bounded(struct isl_basic_set *bset)
 	struct isl_ctx *ctx;
 	struct isl_vec *sample;
 	struct isl_tab *tab = NULL;
+	isl_factorizer *f;
 
 	if (!bset)
 		return NULL;
 
-	if (isl_basic_set_fast_is_empty(bset))
+	if (isl_basic_set_plain_is_empty(bset))
 		return empty_sample(bset);
 
 	dim = isl_basic_set_total_dim(bset);
@@ -569,9 +754,16 @@ static struct isl_vec *sample_bounded(struct isl_basic_set *bset)
 	if (bset->n_eq > 0)
 		return sample_eq(bset, sample_bounded);
 
+	f = isl_basic_set_factorizer(bset);
+	if (!f)
+		goto error;
+	if (f->n_group != 0)
+		return factored_sample(bset, f);
+	isl_factorizer_free(f);
+		
 	ctx = bset->ctx;
 
-	tab = isl_tab_from_basic_set(bset);
+	tab = isl_tab_from_basic_set(bset, 1);
 	if (tab && tab->empty) {
 		isl_tab_free(tab);
 		ISL_F_SET(bset, ISL_BASIC_SET_EMPTY);
@@ -580,12 +772,9 @@ static struct isl_vec *sample_bounded(struct isl_basic_set *bset)
 		return sample;
 	}
 
-	if (isl_tab_track_bset(tab, isl_basic_set_copy(bset)) < 0)
-		goto error;
 	if (!ISL_F_ISSET(bset, ISL_BASIC_SET_NO_IMPLICIT))
-		tab = isl_tab_detect_implicit_equalities(tab);
-	if (!tab)
-		goto error;
+		if (isl_tab_detect_implicit_equalities(tab) < 0)
+			goto error;
 
 	sample = isl_tab_sample(tab);
 	if (!sample)
@@ -661,7 +850,7 @@ static struct isl_vec *rational_sample(struct isl_basic_set *bset)
 	if (!bset)
 		return NULL;
 
-	tab = isl_tab_from_basic_set(bset);
+	tab = isl_tab_from_basic_set(bset, 0);
 	sample = isl_tab_get_sample_value(tab);
 	isl_tab_free(tab);
 
@@ -718,7 +907,7 @@ static struct isl_basic_set *shift_cone(struct isl_basic_set *cone,
 
 	total = isl_basic_set_total_dim(cone);
 
-	shift = isl_basic_set_alloc_dim(isl_basic_set_get_dim(cone),
+	shift = isl_basic_set_alloc_space(isl_basic_set_get_space(cone),
 					0, 0, cone->n_ineq);
 
 	for (i = 0; i < cone->n_ineq; ++i) {
@@ -778,7 +967,8 @@ static struct isl_vec *round_up_in_cone(struct isl_vec *vec,
 
 	total = isl_basic_set_total_dim(cone);
 	cone = isl_basic_set_preimage(cone, U);
-	cone = isl_basic_set_remove_dims(cone, 0, total - (vec->size - 1));
+	cone = isl_basic_set_remove_dims(cone, isl_dim_set,
+					 0, total - (vec->size - 1));
 
 	cone = shift_cone(cone, vec);
 
@@ -823,28 +1013,6 @@ error:
 	return NULL;
 }
 
-/* Drop all constraints in bset that involve any of the dimensions
- * first to first+n-1.
- */
-static struct isl_basic_set *drop_constraints_involving
-	(struct isl_basic_set *bset, unsigned first, unsigned n)
-{
-	int i;
-
-	if (!bset)
-		return NULL;
-
-	bset = isl_basic_set_cow(bset);
-
-	for (i = bset->n_ineq - 1; i >= 0; --i) {
-		if (isl_seq_first_non_zero(bset->ineq[i] + 1 + first, n) == -1)
-			continue;
-		isl_basic_set_drop_inequality(bset, i);
-	}
-
-	return bset;
-}
-
 /* Give a basic set "bset" with recession cone "cone", compute and
  * return an integer point in bset, if any.
  *
@@ -900,7 +1068,7 @@ __isl_give isl_vec *isl_basic_set_sample_with_cone(
 	total = isl_basic_set_total_dim(cone);
 	cone_dim = total - cone->n_eq;
 
-	M = isl_mat_sub_alloc(bset->ctx, cone->eq, 0, cone->n_eq, 1, total);
+	M = isl_mat_sub_alloc6(bset->ctx, cone->eq, 0, cone->n_eq, 1, total);
 	M = isl_mat_left_hermite(M, 0, &U, NULL);
 	if (!M)
 		goto error;
@@ -910,7 +1078,8 @@ __isl_give isl_vec *isl_basic_set_sample_with_cone(
 	bset = isl_basic_set_preimage(bset, isl_mat_copy(U));
 
 	bounded = isl_basic_set_copy(bset);
-	bounded = drop_constraints_involving(bounded, total - cone_dim, cone_dim);
+	bounded = isl_basic_set_drop_constraints_involving(bounded,
+						   total - cone_dim, cone_dim);
 	bounded = isl_basic_set_drop_dims(bounded, total - cone_dim, cone_dim);
 	sample = sample_bounded(bounded);
 	if (!sample || sample->size == 0) {
@@ -1072,12 +1241,17 @@ static struct isl_vec *gbr_sample(struct isl_basic_set *bset)
 	dim = isl_basic_set_total_dim(bset);
 
 	cone = isl_basic_set_recession_cone(isl_basic_set_copy(bset));
+	if (!cone)
+		goto error;
 
 	if (cone->n_eq < dim)
 		return isl_basic_set_sample_with_cone(bset, cone);
 
 	isl_basic_set_free(cone);
 	return sample_bounded(bset);
+error:
+	isl_basic_set_free(bset);
+	return NULL;
 }
 
 static struct isl_vec *pip_sample(struct isl_basic_set *bset)
@@ -1109,7 +1283,7 @@ static struct isl_vec *basic_set_sample(struct isl_basic_set *bset, int bounded)
 		return NULL;
 
 	ctx = bset->ctx;
-	if (isl_basic_set_fast_is_empty(bset))
+	if (isl_basic_set_plain_is_empty(bset))
 		return empty_sample(bset);
 
 	dim = isl_basic_set_n_dim(bset);
@@ -1219,6 +1393,11 @@ error:
 	return NULL;
 }
 
+__isl_give isl_basic_set *isl_basic_set_sample(__isl_take isl_basic_set *bset)
+{
+	return isl_basic_map_sample(bset);
+}
+
 __isl_give isl_basic_map *isl_map_sample(__isl_take isl_map *map)
 {
 	int i;
@@ -1252,9 +1431,9 @@ __isl_give isl_basic_set *isl_set_sample(__isl_take isl_set *set)
 __isl_give isl_point *isl_basic_set_sample_point(__isl_take isl_basic_set *bset)
 {
 	isl_vec *vec;
-	isl_dim *dim;
+	isl_space *dim;
 
-	dim = isl_basic_set_get_dim(bset);
+	dim = isl_basic_set_get_space(bset);
 	bset = isl_basic_set_underlying_set(bset);
 	vec = isl_basic_set_sample_vec(bset);
 
@@ -1278,7 +1457,7 @@ __isl_give isl_point *isl_set_sample_point(__isl_take isl_set *set)
 		isl_point_free(pnt);
 	}
 	if (i == set->n)
-		pnt = isl_point_void(isl_set_get_dim(set));
+		pnt = isl_point_void(isl_set_get_space(set));
 
 	isl_set_free(set);
 	return pnt;