/*

 * Copyright 2012      Ecole Normale Superieure

 * Copyright 2014      INRIA Rocquencourt

 *

 * Use of this software is governed by the MIT license

 *

 * Written by Sven Verdoolaege,

 * Ecole Normale Superieure, 45 rue d’Ulm, 75230 Paris, France

 * and Inria Paris - Rocquencourt, Domaine de Voluceau - Rocquencourt,

 * B.P. 105 - 78153 Le Chesnay, France

 */

#include <isl_ast_private.h>

#include <isl_ast_build_expr.h>

#include <isl_ast_build_private.h>

#include <isl_ast_graft_private.h>

static __isl_give isl_ast_graft *isl_ast_graft_copy(

	__isl_keep isl_ast_graft *graft);

#undef BASE

#define BASE ast_graft

#include <isl_list_templ.c>

#undef BASE

#define BASE ast_graft

#include <print_templ.c>

isl_ctx *isl_ast_graft_get_ctx(__isl_keep isl_ast_graft *graft)

{

	if (!graft)

		return NULL;

	return isl_basic_set_get_ctx(graft->enforced);

}

__isl_give isl_ast_node *isl_ast_graft_get_node(

	__isl_keep isl_ast_graft *graft)

{

	return graft ? isl_ast_node_copy(graft->node) : NULL;

}

/* Create a graft for "node" with no guards and no enforced conditions.

 */

__isl_give isl_ast_graft *isl_ast_graft_alloc(

	__isl_take isl_ast_node *node, __isl_keep isl_ast_build *build)

{

	isl_ctx *ctx;

	isl_space *space;

	isl_ast_graft *graft;

	if (!node)

		return NULL;

	ctx = isl_ast_node_get_ctx(node);

	graft = isl_calloc_type(ctx, isl_ast_graft);

	if (!graft)

		goto error;

	space = isl_ast_build_get_space(build, 1);

	graft->ref = 1;

	graft->node = node;

	graft->guard = isl_set_universe(isl_space_copy(space));

	graft->enforced = isl_basic_set_universe(space);

	if (!graft->guard || !graft->enforced)

		return isl_ast_graft_free(graft);

	return graft;

error:

	isl_ast_node_free(node);

	return NULL;

}

/* Create a graft with no guards and no enforced conditions

 * encapsulating a call to the domain element specified by "executed".

 * "executed" is assumed to be single-valued.

 */

__isl_give isl_ast_graft *isl_ast_graft_alloc_domain(

	__isl_take isl_map *executed, __isl_keep isl_ast_build *build)

{

	isl_ast_node *node;

	node = isl_ast_build_call_from_executed(build, executed);

	return isl_ast_graft_alloc(node, build);

}

static __isl_give isl_ast_graft *isl_ast_graft_copy(

	__isl_keep isl_ast_graft *graft)

{

	if (!graft)

		return NULL;

	graft->ref++;

	return graft;

}

/* Do all the grafts in "list" have the same guard and is this guard

 * independent of the current depth?

 */

static int equal_independent_guards(__isl_keep isl_ast_graft_list *list,

	__isl_keep isl_ast_build *build)

{

	int i, n;

	int depth;

	isl_ast_graft *graft_0;

	int equal = 1;

	int skip;

	graft_0 = isl_ast_graft_list_get_ast_graft(list, 0);

	if (!graft_0)

		return -1;

	depth = isl_ast_build_get_depth(build);

	skip = isl_set_involves_dims(graft_0->guard, isl_dim_set, depth, 1);

	if (skip < 0 || skip) {

		isl_ast_graft_free(graft_0);

		return skip < 0 ? -1 : 0;

	}

	n = isl_ast_graft_list_n_ast_graft(list);

	for (i = 1; i < n; ++i) {

		isl_ast_graft *graft;

		graft = isl_ast_graft_list_get_ast_graft(list, i);

		if (!graft)

			equal = -1;

		else

			equal = isl_set_is_equal(graft_0->guard, graft->guard);

		isl_ast_graft_free(graft);

		if (equal < 0 || !equal)

			break;

	}

	isl_ast_graft_free(graft_0);

	return equal;

}

/* Hoist "guard" out of the current level (given by "build").

 *

 * In particular, eliminate the dimension corresponding to the current depth.

 */

static __isl_give isl_set *hoist_guard(__isl_take isl_set *guard,

	__isl_keep isl_ast_build *build)

{

	int depth;

	depth = isl_ast_build_get_depth(build);

	if (depth < isl_set_dim(guard, isl_dim_set)) {

		guard = isl_set_remove_divs_involving_dims(guard,

						isl_dim_set, depth, 1);

		guard = isl_set_eliminate(guard, isl_dim_set, depth, 1);

		guard = isl_set_compute_divs(guard);

	}

	return guard;

}

/* Extract a common guard from the grafts in "list" that can be hoisted

 * out of the current level.  If no such guard can be found, then return

 * a universal set.

 *

 * If all the grafts in the list have the same guard and if this guard

 * is independent of the current level, then it can be hoisted out.

 * If there is only one graft in the list and if its guard

 * depends on the current level, then we eliminate this level and

 * return the result.

 *

 * Otherwise, we return the unshifted simple hull of the guards.

 * In order to be able to hoist as many constraints as possible,

 * but at the same time avoid hoisting constraints that did not

 * appear in the guards in the first place, we intersect the guards

 * with all the information that is available (i.e., the domain

 * from the build and the enforced constraints of the graft) and

 * compute the unshifted hull of the result using only constraints

 * from the original guards.

 * In particular, intersecting the guards with other known information

 * allows us to hoist guards that are only explicit is some of

 * the grafts and implicit in the others.

 *

 * The special case for equal guards is needed in case those guards

 * are non-convex.  Taking the simple hull would remove information

 * and would not allow for these guards to be hoisted completely.

 */

__isl_give isl_set *isl_ast_graft_list_extract_hoistable_guard(

	__isl_keep isl_ast_graft_list *list, __isl_keep isl_ast_build *build)

{

	int i, n;

	int equal;

	isl_ctx *ctx;

	isl_set *guard;

	isl_set_list *set_list;

	isl_basic_set *hull;

	if (!list || !build)

		return NULL;

	n = isl_ast_graft_list_n_ast_graft(list);

	if (n == 0)

		return isl_set_universe(isl_ast_build_get_space(build, 1));

	equal = equal_independent_guards(list, build);

	if (equal < 0)

		return NULL;

	if (equal || n == 1) {

		isl_ast_graft *graft_0;

		graft_0 = isl_ast_graft_list_get_ast_graft(list, 0);

		if (!graft_0)

			return NULL;

		guard = isl_set_copy(graft_0->guard);

		if (!equal)

			guard = hoist_guard(guard, build);

		isl_ast_graft_free(graft_0);

		return guard;

	}

	ctx = isl_ast_build_get_ctx(build);

	set_list = isl_set_list_alloc(ctx, n);

	guard = isl_set_empty(isl_ast_build_get_space(build, 1));

	for (i = 0; i < n; ++i) {

		isl_ast_graft *graft;

		isl_basic_set *enforced;

		isl_set *guard_i;

		graft = isl_ast_graft_list_get_ast_graft(list, i);

		enforced = isl_ast_graft_get_enforced(graft);

		guard_i = isl_set_copy(graft->guard);

		isl_ast_graft_free(graft);

		set_list = isl_set_list_add(set_list, isl_set_copy(guard_i));

		guard_i = isl_set_intersect(guard_i,

					    isl_set_from_basic_set(enforced));

		guard_i = isl_set_intersect(guard_i,

					    isl_ast_build_get_domain(build));

		guard = isl_set_union(guard, guard_i);

	}

	hull = isl_set_unshifted_simple_hull_from_set_list(guard, set_list);

	guard = isl_set_from_basic_set(hull);

	return hoist_guard(guard, build);

}

/* Internal data structure used inside insert_if.

 *

 * list is the list of guarded nodes created by each call to insert_if.

 * node is the original node that is guarded by insert_if.

 * build is the build in which the AST is constructed.

 */

struct isl_insert_if_data {

	isl_ast_node_list *list;

	isl_ast_node *node;

	isl_ast_build *build;

};

static int insert_if(__isl_take isl_basic_set *bset, void *user);

/* Insert an if node around "node" testing the condition encoded

 * in guard "guard".

 *

 * If the user does not want any disjunctions in the if conditions

 * and if "guard" does involve a disjunction, then we make the different

 * disjuncts disjoint and insert an if node corresponding to each disjunct

 * around a copy of "node".  The result is then a block node containing

 * this sequence of guarded copies of "node".

 */

static __isl_give isl_ast_node *ast_node_insert_if(

	__isl_take isl_ast_node *node, __isl_take isl_set *guard,

	__isl_keep isl_ast_build *build)

{

	struct isl_insert_if_data data;

	isl_ctx *ctx;

	ctx = isl_ast_build_get_ctx(build);

	if (isl_options_get_ast_build_allow_or(ctx) ||

	    isl_set_n_basic_set(guard) <= 1) {

		isl_ast_node *if_node;

		isl_ast_expr *expr;

		expr = isl_ast_build_expr_from_set(build, guard);

		if_node = isl_ast_node_alloc_if(expr);

		return isl_ast_node_if_set_then(if_node, node);

	}

	guard = isl_set_make_disjoint(guard);

	data.list = isl_ast_node_list_alloc(ctx, 0);

	data.node = node;

	data.build = build;

	if (isl_set_foreach_basic_set(guard, &insert_if, &data) < 0)

		data.list = isl_ast_node_list_free(data.list);

	isl_set_free(guard);

	isl_ast_node_free(data.node);

	return isl_ast_node_alloc_block(data.list);

}

/* Insert an if node around a copy of "data->node" testing the condition

 * encoded in guard "bset" and add the result to data->list.

 */

static int insert_if(__isl_take isl_basic_set *bset, void *user)

{

	struct isl_insert_if_data *data = user;

	isl_ast_node *node;

	isl_set *set;

	set = isl_set_from_basic_set(bset);

	node = isl_ast_node_copy(data->node);

	node = ast_node_insert_if(node, set, data->build);

	data->list = isl_ast_node_list_add(data->list, node);

	return 0;

}

/* Insert an if node around graft->node testing the condition encoded

 * in guard "guard", assuming guard involves any conditions.

 */

static __isl_give isl_ast_graft *insert_if_node(

	__isl_take isl_ast_graft *graft, __isl_take isl_set *guard,

	__isl_keep isl_ast_build *build)

{

	int univ;

	if (!graft)

		goto error;

	univ = isl_set_plain_is_universe(guard);

	if (univ < 0)

		goto error;

	if (univ) {

		isl_set_free(guard);

		return graft;

	}

	build = isl_ast_build_copy(build);

	graft->node = ast_node_insert_if(graft->node, guard, build);

	isl_ast_build_free(build);

	if (!graft->node)

		return isl_ast_graft_free(graft);

	return graft;

error:

	isl_set_free(guard);

	return isl_ast_graft_free(graft);

}

/* Insert an if node around graft->node testing the condition encoded

 * in graft->guard, assuming graft->guard involves any conditions.

 */

static __isl_give isl_ast_graft *insert_pending_guard_node(

	__isl_take isl_ast_graft *graft, __isl_keep isl_ast_build *build)

{

	if (!graft)

		return NULL;

	return insert_if_node(graft, isl_set_copy(graft->guard), build);

}

/* Replace graft->enforced by "enforced".

 */

__isl_give isl_ast_graft *isl_ast_graft_set_enforced(

	__isl_take isl_ast_graft *graft, __isl_take isl_basic_set *enforced)

{

	if (!graft || !enforced)

		goto error;

	isl_basic_set_free(graft->enforced);

	graft->enforced = enforced;

	return graft;

error:

	isl_basic_set_free(enforced);

	return isl_ast_graft_free(graft);

}

/* Update "enforced" such that it only involves constraints that are

 * also enforced by "graft".

 */

static __isl_give isl_basic_set *update_enforced(

	__isl_take isl_basic_set *enforced, __isl_keep isl_ast_graft *graft,

	int depth)

{

	isl_basic_set *enforced_g;

	enforced_g = isl_ast_graft_get_enforced(graft);

	if (depth < isl_basic_set_dim(enforced_g, isl_dim_set))

		enforced_g = isl_basic_set_eliminate(enforced_g,

							isl_dim_set, depth, 1);

	enforced_g = isl_basic_set_remove_unknown_divs(enforced_g);

	enforced_g = isl_basic_set_align_params(enforced_g,

				isl_basic_set_get_space(enforced));

	enforced = isl_basic_set_align_params(enforced,

				isl_basic_set_get_space(enforced_g));

	enforced = isl_set_simple_hull(isl_basic_set_union(enforced,

						enforced_g));

	return enforced;

}

/* Extend the node at *body with node.

 *

 * If body points to the else branch, then *body may still be NULL.

 * If so, we simply attach node to this else branch.

 * Otherwise, we attach a list containing the statements already

 * attached at *body followed by node.

 */

static void extend_body(__isl_keep isl_ast_node **body,

	__isl_take isl_ast_node *node)

{

	isl_ast_node_list *list;

	if  (!*body) {

		*body = node;

		return;

	}

	if ((*body)->type == isl_ast_node_block) {

		list = isl_ast_node_block_get_children(*body);

		isl_ast_node_free(*body);

	} else

		list = isl_ast_node_list_from_ast_node(*body);

	list = isl_ast_node_list_add(list, node);

	*body = isl_ast_node_alloc_block(list);

}

/* Merge "graft" into the last graft of "list".

 * body points to the then or else branch of an if node in that last graft.

 *

 * We attach graft->node to this branch and update the enforced

 * set of the last graft of "list" to take into account the enforced

 * set of "graft".

 */

static __isl_give isl_ast_graft_list *graft_extend_body(

	__isl_take isl_ast_graft_list *list,

	__isl_keep isl_ast_node **body, __isl_take isl_ast_graft *graft,

	__isl_keep isl_ast_build *build)

{

	int n;

	int depth;

	isl_ast_graft *last;

	isl_space *space;

	isl_basic_set *enforced;

	if (!list || !graft)

		goto error;

	extend_body(body, isl_ast_node_copy(graft->node));

	if (!*body)

		goto error;

	n = isl_ast_graft_list_n_ast_graft(list);

	last = isl_ast_graft_list_get_ast_graft(list, n - 1);

	depth = isl_ast_build_get_depth(build);

	space = isl_ast_build_get_space(build, 1);

	enforced = isl_basic_set_empty(space);

	enforced = update_enforced(enforced, last, depth);

	enforced = update_enforced(enforced, graft, depth);

	last = isl_ast_graft_set_enforced(last, enforced);

	list = isl_ast_graft_list_set_ast_graft(list, n - 1, last);

	isl_ast_graft_free(graft);

	return list;

error:

	isl_ast_graft_free(graft);

	return isl_ast_graft_list_free(list);

}

/* Merge "graft" into the last graft of "list", attaching graft->node

 * to the then branch of "last_if".

 */

static __isl_give isl_ast_graft_list *extend_then(

	__isl_take isl_ast_graft_list *list,

	__isl_keep isl_ast_node *last_if, __isl_take isl_ast_graft *graft,

	__isl_keep isl_ast_build *build)

{

	return graft_extend_body(list, &last_if->u.i.then, graft, build);

}

/* Merge "graft" into the last graft of "list", attaching graft->node

 * to the else branch of "last_if".

 */

static __isl_give isl_ast_graft_list *extend_else(

	__isl_take isl_ast_graft_list *list,

	__isl_keep isl_ast_node *last_if, __isl_take isl_ast_graft *graft,

	__isl_keep isl_ast_build *build)

{

	return graft_extend_body(list, &last_if->u.i.else_node, graft, build);

}

/* This data structure keeps track of an if node.

 *

 * "node" is the actual if-node

 * "guard" is the original, non-simplified guard of the node

 * "complement" is the complement of "guard" in the context of outer if nodes

 */

struct isl_if_node {

	isl_ast_node *node;

	isl_set *guard;

	isl_set *complement;

};

/* Given a list of "n" if nodes, clear those starting at "first"

 * and return "first" (i.e., the updated size of the array).

 */

static int clear_if_nodes(struct isl_if_node *if_node, int first, int n)

{

	int i;

	for (i = first; i < n; ++i) {

		isl_set_free(if_node[i].guard);

		isl_set_free(if_node[i].complement);

	}

	return first;

}

/* For each graft in "list",

 * insert an if node around graft->node testing the condition encoded

 * in graft->guard, assuming graft->guard involves any conditions.

 *

 * We keep track of a list of generated if nodes that can be extended

 * without changing the order of the elements in "list".

 * If the guard of a graft is a subset of either the guard or its complement

 * of one of those if nodes, then the node

 * of the new graft is inserted into the then or else branch of the last graft

 * and the current graft is discarded.

 * The guard of the node is then simplified based on the conditions

 * enforced at that then or else branch.

 * Otherwise, the current graft is appended to the list.

 *

 * We only construct else branches if allowed by the user.

 */

static __isl_give isl_ast_graft_list *insert_pending_guard_nodes(

	__isl_take isl_ast_graft_list *list,

	__isl_keep isl_ast_build *build)

{

	int i, j, n, n_if;

	int allow_else;

	isl_ctx *ctx;

	isl_ast_graft_list *res;

	struct isl_if_node *if_node = NULL;

	if (!build || !list)

		return isl_ast_graft_list_free(list);

	ctx = isl_ast_build_get_ctx(build);

	n = isl_ast_graft_list_n_ast_graft(list);

	allow_else = isl_options_get_ast_build_allow_else(ctx);

	n_if = 0;

	if (n > 1) {

		if_node = isl_alloc_array(ctx, struct isl_if_node, n - 1);

		if (!if_node)

			return isl_ast_graft_list_free(list);

	}

	res = isl_ast_graft_list_alloc(ctx, n);

	for (i = 0; i < n; ++i) {

		isl_set *guard;

		isl_ast_graft *graft;

		int subset, found_then, found_else;

		isl_ast_node *node;

		graft = isl_ast_graft_list_get_ast_graft(list, i);

		if (!graft)

			break;

		subset = 0;

		found_then = found_else = -1;

		if (n_if > 0) {

			isl_set *test;

			test = isl_set_copy(graft->guard);

			test = isl_set_intersect(test,

						isl_set_copy(build->domain));

			for (j = n_if - 1; j >= 0; --j) {

				subset = isl_set_is_subset(test,

							if_node[j].guard);

				if (subset < 0 || subset) {

					found_then = j;

					break;

				}

				if (!allow_else)

					continue;

				subset = isl_set_is_subset(test,

							if_node[j].complement);

				if (subset < 0 || subset) {

					found_else = j;

					break;

				}

			}

			n_if = clear_if_nodes(if_node, j + 1, n_if);

			isl_set_free(test);

		}

		if (subset < 0) {

			graft = isl_ast_graft_free(graft);

			break;

		}

		guard = isl_set_copy(graft->guard);

		if (found_then >= 0)

			graft->guard = isl_set_gist(graft->guard,

				isl_set_copy(if_node[found_then].guard));

		else if (found_else >= 0)

			graft->guard = isl_set_gist(graft->guard,

				isl_set_copy(if_node[found_else].complement));

		node = graft->node;

		if (!graft->guard)

			graft = isl_ast_graft_free(graft);

		graft = insert_pending_guard_node(graft, build);

		if (graft && graft->node != node && i != n - 1) {

			isl_set *set;

			if_node[n_if].node = graft->node;

			if_node[n_if].guard = guard;

			if (found_then >= 0)

				set = if_node[found_then].guard;

			else if (found_else >= 0)

				set = if_node[found_else].complement;

			else

				set = build->domain;

			set = isl_set_copy(set);

			set = isl_set_subtract(set, isl_set_copy(guard));

			if_node[n_if].complement = set;

			n_if++;

		} else

			isl_set_free(guard);

		if (!graft)

			break;

		if (found_then >= 0)

			res = extend_then(res, if_node[found_then].node,

						graft, build);

		else if (found_else >= 0)

			res = extend_else(res, if_node[found_else].node,

						graft, build);

		else

			res = isl_ast_graft_list_add(res, graft);

	}

	if (i < n)

		res = isl_ast_graft_list_free(res);

	isl_ast_graft_list_free(list);

	clear_if_nodes(if_node, 0, n_if);

	free(if_node);

	return res;

}

/* Collect the nodes contained in the grafts in "list" in a node list.

 */

static __isl_give isl_ast_node_list *extract_node_list(

	__isl_keep isl_ast_graft_list *list)

{

	int i, n;

	isl_ctx *ctx;

	isl_ast_node_list *node_list;

	if (!list)

		return NULL;

	ctx = isl_ast_graft_list_get_ctx(list);

	n = isl_ast_graft_list_n_ast_graft(list);

	node_list = isl_ast_node_list_alloc(ctx, n);

	for (i = 0; i < n; ++i) {

		isl_ast_node *node;

		isl_ast_graft *graft;

		graft = isl_ast_graft_list_get_ast_graft(list, i);

		node = isl_ast_graft_get_node(graft);

		node_list = isl_ast_node_list_add(node_list, node);

		isl_ast_graft_free(graft);

	}

	return node_list;

}

/* Look for shared enforced constraints by all the elements in "list"

 * on outer loops (with respect to the current depth) and return the result.

 *

 * We assume that the number of children is at least one.

 */

__isl_give isl_basic_set *isl_ast_graft_list_extract_shared_enforced(

	__isl_keep isl_ast_graft_list *list,

	__isl_keep isl_ast_build *build)

{

	int i, n;

	int depth;

	isl_space *space;

	isl_basic_set *enforced;

	if (!list)

		return NULL;

	n = isl_ast_graft_list_n_ast_graft(list);

	if (n == 0)

		isl_die(isl_ast_graft_list_get_ctx(list), isl_error_invalid,

			"for node should have at least one child",

			return NULL);

	space = isl_ast_build_get_space(build, 1);

	enforced = isl_basic_set_empty(space);

	depth = isl_ast_build_get_depth(build);

	for (i = 0; i < n; ++i) {

		isl_ast_graft *graft;

		graft = isl_ast_graft_list_get_ast_graft(list, i);

		enforced = update_enforced(enforced, graft, depth);

		isl_ast_graft_free(graft);

	}

	return enforced;

}

/* Record "guard" in "graft" so that it will be enforced somewhere

 * up the tree.  If the graft already has a guard, then it may be partially

 * redundant in combination with the new guard and in the context

 * the generated constraints of "build".  In fact, the new guard

 * may in itself have some redundant constraints.

 * We therefore (re)compute the gist of the intersection

 * and coalesce the result.

 */

static __isl_give isl_ast_graft *store_guard(__isl_take isl_ast_graft *graft,

	__isl_take isl_set *guard, __isl_keep isl_ast_build *build)

{

	int is_universe;

	if (!graft)

		goto error;

	is_universe = isl_set_plain_is_universe(guard);

	if (is_universe < 0)

		goto error;

	if (is_universe) {

		isl_set_free(guard);

		return graft;

	}

	graft->guard = isl_set_intersect(graft->guard, guard);

	graft->guard = isl_set_gist(graft->guard,

				    isl_ast_build_get_generated(build));

	graft->guard = isl_set_coalesce(graft->guard);

	if (!graft->guard)

		return isl_ast_graft_free(graft);

	return graft;

error:

	isl_set_free(guard);

	return isl_ast_graft_free(graft);

}

/* For each graft in "list", replace its guard with the gist with

 * respect to "context".

 */

static __isl_give isl_ast_graft_list *gist_guards(

	__isl_take isl_ast_graft_list *list, __isl_keep isl_set *context)

{

	int i, n;

	if (!list)

		return NULL;

	n = isl_ast_graft_list_n_ast_graft(list);

	for (i = 0; i < n; ++i) {

		isl_ast_graft *graft;

		graft = isl_ast_graft_list_get_ast_graft(list, i);

		if (!graft)

			break;

		graft->guard = isl_set_gist(graft->guard,

						isl_set_copy(context));

		if (!graft->guard)

			graft = isl_ast_graft_free(graft);

		list = isl_ast_graft_list_set_ast_graft(list, i, graft);

	}

	if (i < n)

		return isl_ast_graft_list_free(list);

	return list;

}

/* For each graft in "list", replace its guard with the gist with

 * respect to "context".

 */

__isl_give isl_ast_graft_list *isl_ast_graft_list_gist_guards(

	__isl_take isl_ast_graft_list *list, __isl_take isl_set *context)

{

	list = gist_guards(list, context);

	isl_set_free(context);

	return list;

}

/* Allocate a graft in "build" based on the list of grafts in "sub_build".

 * "guard" and "enforced" are the guard and enforced constraints

 * of the allocated graft.  The guard is used to simplify the guards

 * of the elements in "list".

 *

 * The node is initialized to either a block containing the nodes of "children"

 * or, if there is only a single child, the node of that child.

 * If the current level requires a for node, it should be inserted by

 * a subsequent call to isl_ast_graft_insert_for.

 */

__isl_give isl_ast_graft *isl_ast_graft_alloc_from_children(

	__isl_take isl_ast_graft_list *list, __isl_take isl_set *guard,

	__isl_take isl_basic_set *enforced, __isl_keep isl_ast_build *build,

	__isl_keep isl_ast_build *sub_build)

{

	isl_ast_build *guard_build;

	isl_ast_node *node;

	isl_ast_node_list *node_list;

	isl_ast_graft *graft;

	guard_build = isl_ast_build_copy(sub_build);

	guard_build = isl_ast_build_replace_pending_by_guard(guard_build,

						isl_set_copy(guard));

	list = gist_guards(list, guard);

	list = insert_pending_guard_nodes(list, guard_build);

	isl_ast_build_free(guard_build);

	node_list = extract_node_list(list);

	node = isl_ast_node_from_ast_node_list(node_list);

	isl_ast_graft_list_free(list);

	graft = isl_ast_graft_alloc(node, build);

	graft = store_guard(graft, guard, build);

	graft = isl_ast_graft_enforce(graft, enforced);

	return graft;

}

/* Combine the grafts in the list into a single graft.

 *

 * The guard is initialized to the shared guard of the list elements (if any),

 * provided it does not depend on the current dimension.

 * The guards in the elements are then simplified with respect to the

 * hoisted guard and materialized as if nodes around the contained AST nodes

 * in the context of "sub_build".

 *

 * The enforced set is initialized to the simple hull of the enforced sets

 * of the elements, provided the ast_build_exploit_nested_bounds option is set

 * or the new graft will be used at the same level.

 *

 * The node is initialized to either a block containing the nodes of "list"

 * or, if there is only a single element, the node of that element.

 */

static __isl_give isl_ast_graft *ast_graft_list_fuse(

	__isl_take isl_ast_graft_list *list, __isl_keep isl_ast_build *build)

{

	isl_ast_graft *graft;

	isl_basic_set *enforced;

	isl_set *guard;

	if (!list)

		return NULL;

	enforced = isl_ast_graft_list_extract_shared_enforced(list, build);

	guard = isl_ast_graft_list_extract_hoistable_guard(list, build);

	graft = isl_ast_graft_alloc_from_children(list, guard, enforced,

						    build, build);

	return graft;

}

/* Combine the grafts in the list into a single graft.

 * Return a list containing this single graft.

 * If the original list is empty, then return an empty list.

 */

__isl_give isl_ast_graft_list *isl_ast_graft_list_fuse(

	__isl_take isl_ast_graft_list *list,

	__isl_keep isl_ast_build *build)

{

	isl_ast_graft *graft;

	if (!list)

		return NULL;

	if (isl_ast_graft_list_n_ast_graft(list) <= 1)

		return list;