1/*
2 * Copyright 2012      Ecole Normale Superieure
3 *
4 * Use of this software is governed by the MIT license
5 *
6 * Written by Sven Verdoolaege,
7 * Ecole Normale Superieure, 45 rue d’Ulm, 75230 Paris, France
8 */
9
10#include <isl_ast_private.h>
11#include <isl_ast_build_expr.h>
12#include <isl_ast_build_private.h>
13#include <isl_ast_graft_private.h>
14
15static __isl_give isl_ast_graft *isl_ast_graft_copy(
16	__isl_keep isl_ast_graft *graft);
17
18#undef BASE
19#define BASE ast_graft
20
21#include <isl_list_templ.c>
22
23#undef BASE
24#define BASE ast_graft
25#include <print_templ.c>
26
27isl_ctx *isl_ast_graft_get_ctx(__isl_keep isl_ast_graft *graft)
28{
29	if (!graft)
30		return NULL;
31	return isl_basic_set_get_ctx(graft->enforced);
32}
33
34__isl_give isl_ast_node *isl_ast_graft_get_node(
35	__isl_keep isl_ast_graft *graft)
36{
37	return graft ? isl_ast_node_copy(graft->node) : NULL;
38}
39
40/* Create a graft for "node" with no guards and no enforced conditions.
41 */
42__isl_give isl_ast_graft *isl_ast_graft_alloc(
43	__isl_take isl_ast_node *node, __isl_keep isl_ast_build *build)
44{
45	isl_ctx *ctx;
46	isl_space *space;
47	isl_ast_graft *graft;
48
49	if (!node)
50		return NULL;
51
52	ctx = isl_ast_node_get_ctx(node);
53	graft = isl_calloc_type(ctx, isl_ast_graft);
54	if (!graft)
55		goto error;
56
57	space = isl_ast_build_get_space(build, 1);
58
59	graft->ref = 1;
60	graft->node = node;
61	graft->guard = isl_set_universe(isl_space_copy(space));
62	graft->enforced = isl_basic_set_universe(space);
63
64	if (!graft->guard || !graft->enforced)
65		return isl_ast_graft_free(graft);
66
67	return graft;
68error:
69	isl_ast_node_free(node);
70	return NULL;
71}
72
73/* Create a graft with no guards and no enforced conditions
74 * encapsulating a call to the domain element specified by "executed".
75 * "executed" is assumed to be single-valued.
76 */
77__isl_give isl_ast_graft *isl_ast_graft_alloc_domain(
78	__isl_take isl_map *executed, __isl_keep isl_ast_build *build)
79{
80	isl_ast_node *node;
81
82	node = isl_ast_build_call_from_executed(build, executed);
83
84	return isl_ast_graft_alloc(node, build);
85}
86
87static __isl_give isl_ast_graft *isl_ast_graft_copy(
88	__isl_keep isl_ast_graft *graft)
89{
90	if (!graft)
91		return NULL;
92
93	graft->ref++;
94	return graft;
95}
96
97/* Do all the grafts in "list" have the same guard and is this guard
98 * independent of the current depth?
99 */
100static int equal_independent_guards(__isl_keep isl_ast_graft_list *list,
101	__isl_keep isl_ast_build *build)
102{
103	int i, n;
104	int depth;
105	isl_ast_graft *graft_0;
106	int equal = 1;
107	int skip;
108
109	graft_0 = isl_ast_graft_list_get_ast_graft(list, 0);
110	if (!graft_0)
111		return -1;
112
113	depth = isl_ast_build_get_depth(build);
114	skip = isl_set_involves_dims(graft_0->guard, isl_dim_set, depth, 1);
115	if (skip < 0 || skip) {
116		isl_ast_graft_free(graft_0);
117		return skip < 0 ? -1 : 0;
118	}
119
120	n = isl_ast_graft_list_n_ast_graft(list);
121	for (i = 1; i < n; ++i) {
122		isl_ast_graft *graft;
123		graft = isl_ast_graft_list_get_ast_graft(list, i);
124		if (!graft)
125			equal = -1;
126		else
127			equal = isl_set_is_equal(graft_0->guard, graft->guard);
128		isl_ast_graft_free(graft);
129		if (equal < 0 || !equal)
130			break;
131	}
132
133	isl_ast_graft_free(graft_0);
134
135	return equal;
136}
137
138/* Extract a common guard from the grafts in "list" that can be hoisted
139 * out of the current level.  If no such guard can be found, then return
140 * a universal set.
141 *
142 * If all the grafts in the list have the same guard and if this guard
143 * is independent of the current level, then it can be hoisted out.
144 * Otherwise, we return the unshifted simple hull of the guards.
145 *
146 * The special case for equal guards is needed in case those guards
147 * are non-convex.  Taking the simple hull would remove information
148 * and would not allow for these guards to be hoisted completely.
149 */
150static __isl_give isl_set *extract_hoistable_guard(
151	__isl_keep isl_ast_graft_list *list, __isl_keep isl_ast_build *build)
152{
153	int i, n;
154	int depth;
155	isl_ast_graft *graft_0;
156	int equal;
157	isl_set *guard;
158
159	if (!list || !build)
160		return NULL;
161
162	n = isl_ast_graft_list_n_ast_graft(list);
163	if (n == 0)
164		return isl_set_universe(isl_ast_build_get_space(build, 1));
165
166	equal = equal_independent_guards(list, build);
167	if (equal < 0)
168		return NULL;
169
170	graft_0 = isl_ast_graft_list_get_ast_graft(list, 0);
171	if (!graft_0)
172		return NULL;
173	guard = isl_set_copy(graft_0->guard);
174	isl_ast_graft_free(graft_0);
175	if (equal)
176		return guard;
177
178	depth = isl_ast_build_get_depth(build);
179	if (depth < isl_set_dim(guard, isl_dim_set)) {
180		guard = isl_set_remove_divs_involving_dims(guard,
181						isl_dim_set, depth, 1);
182		guard = isl_set_eliminate(guard, isl_dim_set, depth, 1);
183		guard = isl_set_compute_divs(guard);
184	}
185
186	for (i = 1; i < n; ++i) {
187		isl_ast_graft *graft;
188		isl_basic_set *hull;
189		int is_universe;
190
191		is_universe = isl_set_plain_is_universe(guard);
192		if (is_universe < 0)
193			guard = isl_set_free(guard);
194		if (is_universe)
195			break;
196
197		graft = isl_ast_graft_list_get_ast_graft(list, i);
198		if (!graft) {
199			guard = isl_set_free(guard);
200			break;
201		}
202		guard = isl_set_union(guard, isl_set_copy(graft->guard));
203		hull = isl_set_unshifted_simple_hull(guard);
204		guard = isl_set_from_basic_set(hull);
205		isl_ast_graft_free(graft);
206	}
207
208	return guard;
209}
210
211/* Internal data structure used inside insert_if.
212 *
213 * list is the list of guarded nodes created by each call to insert_if.
214 * node is the original node that is guarded by insert_if.
215 * build is the build in which the AST is constructed.
216 */
217struct isl_insert_if_data {
218	isl_ast_node_list *list;
219	isl_ast_node *node;
220	isl_ast_build *build;
221};
222
223static int insert_if(__isl_take isl_basic_set *bset, void *user);
224
225/* Insert an if node around "node" testing the condition encoded
226 * in guard "guard".
227 *
228 * If the user does not want any disjunctions in the if conditions
229 * and if "guard" does involve a disjunction, then we make the different
230 * disjuncts disjoint and insert an if node corresponding to each disjunct
231 * around a copy of "node".  The result is then a block node containing
232 * this sequence of guarded copies of "node".
233 */
234static __isl_give isl_ast_node *ast_node_insert_if(
235	__isl_take isl_ast_node *node, __isl_take isl_set *guard,
236	__isl_keep isl_ast_build *build)
237{
238	struct isl_insert_if_data data;
239	isl_ctx *ctx;
240
241	ctx = isl_ast_build_get_ctx(build);
242	if (isl_options_get_ast_build_allow_or(ctx) ||
243	    isl_set_n_basic_set(guard) <= 1) {
244		isl_ast_node *if_node;
245		isl_ast_expr *expr;
246
247		expr = isl_ast_build_expr_from_set(build, guard);
248
249		if_node = isl_ast_node_alloc_if(expr);
250		return isl_ast_node_if_set_then(if_node, node);
251	}
252
253	guard = isl_set_make_disjoint(guard);
254
255	data.list = isl_ast_node_list_alloc(ctx, 0);
256	data.node = node;
257	data.build = build;
258	if (isl_set_foreach_basic_set(guard, &insert_if, &data) < 0)
259		data.list = isl_ast_node_list_free(data.list);
260
261	isl_set_free(guard);
262	isl_ast_node_free(data.node);
263	return isl_ast_node_alloc_block(data.list);
264}
265
266/* Insert an if node around a copy of "data->node" testing the condition
267 * encoded in guard "bset" and add the result to data->list.
268 */
269static int insert_if(__isl_take isl_basic_set *bset, void *user)
270{
271	struct isl_insert_if_data *data = user;
272	isl_ast_node *node;
273	isl_set *set;
274
275	set = isl_set_from_basic_set(bset);
276	node = isl_ast_node_copy(data->node);
277	node = ast_node_insert_if(node, set, data->build);
278	data->list = isl_ast_node_list_add(data->list, node);
279
280	return 0;
281}
282
283/* Insert an if node around graft->node testing the condition encoded
284 * in guard "guard", assuming guard involves any conditions.
285 */
286static __isl_give isl_ast_graft *insert_if_node(
287	__isl_take isl_ast_graft *graft, __isl_take isl_set *guard,
288	__isl_keep isl_ast_build *build)
289{
290	int univ;
291
292	if (!graft)
293		goto error;
294
295	univ = isl_set_plain_is_universe(guard);
296	if (univ < 0)
297		goto error;
298	if (univ) {
299		isl_set_free(guard);
300		return graft;
301	}
302
303	build = isl_ast_build_copy(build);
304	build = isl_ast_build_set_enforced(build,
305					isl_ast_graft_get_enforced(graft));
306	graft->node = ast_node_insert_if(graft->node, guard, build);
307	isl_ast_build_free(build);
308
309	if (!graft->node)
310		return isl_ast_graft_free(graft);
311
312	return graft;
313error:
314	isl_set_free(guard);
315	return isl_ast_graft_free(graft);
316}
317
318/* Insert an if node around graft->node testing the condition encoded
319 * in graft->guard, assuming graft->guard involves any conditions.
320 */
321static __isl_give isl_ast_graft *insert_pending_guard_node(
322	__isl_take isl_ast_graft *graft, __isl_keep isl_ast_build *build)
323{
324	if (!graft)
325		return NULL;
326
327	return insert_if_node(graft, isl_set_copy(graft->guard), build);
328}
329
330/* Replace graft->enforced by "enforced".
331 */
332__isl_give isl_ast_graft *isl_ast_graft_set_enforced(
333	__isl_take isl_ast_graft *graft, __isl_take isl_basic_set *enforced)
334{
335	if (!graft || !enforced)
336		goto error;
337
338	isl_basic_set_free(graft->enforced);
339	graft->enforced = enforced;
340
341	return graft;
342error:
343	isl_basic_set_free(enforced);
344	return isl_ast_graft_free(graft);
345}
346
347/* Update "enforced" such that it only involves constraints that are
348 * also enforced by "graft".
349 */
350static __isl_give isl_basic_set *update_enforced(
351	__isl_take isl_basic_set *enforced, __isl_keep isl_ast_graft *graft,
352	int depth)
353{
354	isl_basic_set *enforced_g;
355
356	enforced_g = isl_ast_graft_get_enforced(graft);
357	if (depth < isl_basic_set_dim(enforced_g, isl_dim_set))
358		enforced_g = isl_basic_set_eliminate(enforced_g,
359							isl_dim_set, depth, 1);
360	enforced_g = isl_basic_set_remove_unknown_divs(enforced_g);
361	enforced_g = isl_basic_set_align_params(enforced_g,
362				isl_basic_set_get_space(enforced));
363	enforced = isl_basic_set_align_params(enforced,
364				isl_basic_set_get_space(enforced_g));
365	enforced = isl_set_simple_hull(isl_basic_set_union(enforced,
366						enforced_g));
367
368	return enforced;
369}
370
371/* Extend the node at *body with node.
372 *
373 * If body points to the else branch, then *body may still be NULL.
374 * If so, we simply attach node to this else branch.
375 * Otherwise, we attach a list containing the statements already
376 * attached at *body followed by node.
377 */
378static void extend_body(__isl_keep isl_ast_node **body,
379	__isl_take isl_ast_node *node)
380{
381	isl_ast_node_list *list;
382
383	if  (!*body) {
384		*body = node;
385		return;
386	}
387
388	if ((*body)->type == isl_ast_node_block) {
389		list = isl_ast_node_block_get_children(*body);
390		isl_ast_node_free(*body);
391	} else
392		list = isl_ast_node_list_from_ast_node(*body);
393	list = isl_ast_node_list_add(list, node);
394	*body = isl_ast_node_alloc_block(list);
395}
396
397/* Merge "graft" into the last graft of "list".
398 * body points to the then or else branch of an if node in that last graft.
399 *
400 * We attach graft->node to this branch and update the enforced
401 * set of the last graft of "list" to take into account the enforced
402 * set of "graft".
403 */
404static __isl_give isl_ast_graft_list *graft_extend_body(
405	__isl_take isl_ast_graft_list *list,
406	__isl_keep isl_ast_node **body, __isl_take isl_ast_graft *graft,
407	__isl_keep isl_ast_build *build)
408{
409	int n;
410	int depth;
411	isl_ast_graft *last;
412	isl_space *space;
413	isl_basic_set *enforced;
414
415	if (!list || !graft)
416		goto error;
417	extend_body(body, isl_ast_node_copy(graft->node));
418	if (!*body)
419		goto error;
420
421	n = isl_ast_graft_list_n_ast_graft(list);
422	last = isl_ast_graft_list_get_ast_graft(list, n - 1);
423
424	depth = isl_ast_build_get_depth(build);
425	space = isl_ast_build_get_space(build, 1);
426	enforced = isl_basic_set_empty(space);
427	enforced = update_enforced(enforced, last, depth);
428	enforced = update_enforced(enforced, graft, depth);
429	last = isl_ast_graft_set_enforced(last, enforced);
430
431	list = isl_ast_graft_list_set_ast_graft(list, n - 1, last);
432	isl_ast_graft_free(graft);
433	return list;
434error:
435	isl_ast_graft_free(graft);
436	return isl_ast_graft_list_free(list);
437}
438
439/* Merge "graft" into the last graft of "list", attaching graft->node
440 * to the then branch of "last_if".
441 */
442static __isl_give isl_ast_graft_list *extend_then(
443	__isl_take isl_ast_graft_list *list,
444	__isl_keep isl_ast_node *last_if, __isl_take isl_ast_graft *graft,
445	__isl_keep isl_ast_build *build)
446{
447	return graft_extend_body(list, &last_if->u.i.then, graft, build);
448}
449
450/* Merge "graft" into the last graft of "list", attaching graft->node
451 * to the else branch of "last_if".
452 */
453static __isl_give isl_ast_graft_list *extend_else(
454	__isl_take isl_ast_graft_list *list,
455	__isl_keep isl_ast_node *last_if, __isl_take isl_ast_graft *graft,
456	__isl_keep isl_ast_build *build)
457{
458	return graft_extend_body(list, &last_if->u.i.else_node, graft, build);
459}
460
461/* This data structure keeps track of an if node.
462 *
463 * "node" is the actual if-node
464 * "guard" is the original, non-simplified guard of the node
465 * "complement" is the complement of "guard" in the context of outer if nodes
466 */
467struct isl_if_node {
468	isl_ast_node *node;
469	isl_set *guard;
470	isl_set *complement;
471};
472
473/* Given a list of "n" if nodes, clear those starting at "first"
474 * and return "first" (i.e., the updated size of the array).
475 */
476static int clear_if_nodes(struct isl_if_node *if_node, int first, int n)
477{
478	int i;
479
480	for (i = first; i < n; ++i) {
481		isl_set_free(if_node[i].guard);
482		isl_set_free(if_node[i].complement);
483	}
484
485	return first;
486}
487
488/* For each graft in "list",
489 * insert an if node around graft->node testing the condition encoded
490 * in graft->guard, assuming graft->guard involves any conditions.
491 *
492 * We keep track of a list of generated if nodes that can be extended
493 * without changing the order of the elements in "list".
494 * If the guard of a graft is a subset of either the guard or its complement
495 * of one of those if nodes, then the node
496 * of the new graft is inserted into the then or else branch of the last graft
497 * and the current graft is discarded.
498 * The guard of the node is then simplified based on the conditions
499 * enforced at that then or else branch.
500 * Otherwise, the current graft is appended to the list.
501 *
502 * We only construct else branches if allowed by the user.
503 */
504static __isl_give isl_ast_graft_list *insert_pending_guard_nodes(
505	__isl_take isl_ast_graft_list *list,
506	__isl_keep isl_ast_build *build)
507{
508	int i, j, n, n_if;
509	int allow_else;
510	isl_ctx *ctx;
511	isl_ast_graft_list *res;
512	struct isl_if_node *if_node = NULL;
513
514	if (!build || !list)
515		return isl_ast_graft_list_free(list);
516
517	ctx = isl_ast_build_get_ctx(build);
518	n = isl_ast_graft_list_n_ast_graft(list);
519
520	allow_else = isl_options_get_ast_build_allow_else(ctx);
521
522	n_if = 0;
523	if (n > 1) {
524		if_node = isl_alloc_array(ctx, struct isl_if_node, n - 1);
525		if (!if_node)
526			return isl_ast_graft_list_free(list);
527	}
528
529	res = isl_ast_graft_list_alloc(ctx, n);
530
531	for (i = 0; i < n; ++i) {
532		isl_set *guard;
533		isl_ast_graft *graft;
534		int subset, found_then, found_else;
535		isl_ast_node *node;
536
537		graft = isl_ast_graft_list_get_ast_graft(list, i);
538		if (!graft)
539			break;
540		subset = 0;
541		found_then = found_else = -1;
542		if (n_if > 0) {
543			isl_set *test;
544			test = isl_set_copy(graft->guard);
545			test = isl_set_intersect(test,
546						isl_set_copy(build->domain));
547			for (j = n_if - 1; j >= 0; --j) {
548				subset = isl_set_is_subset(test,
549							if_node[j].guard);
550				if (subset < 0 || subset) {
551					found_then = j;
552					break;
553				}
554				if (!allow_else)
555					continue;
556				subset = isl_set_is_subset(test,
557							if_node[j].complement);
558				if (subset < 0 || subset) {
559					found_else = j;
560					break;
561				}
562			}
563			n_if = clear_if_nodes(if_node, j + 1, n_if);
564			isl_set_free(test);
565		}
566		if (subset < 0) {
567			graft = isl_ast_graft_free(graft);
568			break;
569		}
570
571		guard = isl_set_copy(graft->guard);
572		if (found_then >= 0)
573			graft->guard = isl_set_gist(graft->guard,
574				isl_set_copy(if_node[found_then].guard));
575		else if (found_else >= 0)
576			graft->guard = isl_set_gist(graft->guard,
577				isl_set_copy(if_node[found_else].complement));
578
579		node = graft->node;
580		if (!graft->guard)
581			graft = isl_ast_graft_free(graft);
582		graft = insert_pending_guard_node(graft, build);
583		if (graft && graft->node != node && i != n - 1) {
584			isl_set *set;
585			if_node[n_if].node = graft->node;
586			if_node[n_if].guard = guard;
587			if (found_then >= 0)
588				set = if_node[found_then].guard;
589			else if (found_else >= 0)
590				set = if_node[found_else].complement;
591			else
592				set = build->domain;
593			set = isl_set_copy(set);
594			set = isl_set_subtract(set, isl_set_copy(guard));
595			if_node[n_if].complement = set;
596			n_if++;
597		} else
598			isl_set_free(guard);
599		if (!graft)
600			break;
601
602		if (found_then >= 0)
603			res = extend_then(res, if_node[found_then].node,
604						graft, build);
605		else if (found_else >= 0)
606			res = extend_else(res, if_node[found_else].node,
607						graft, build);
608		else
609			res = isl_ast_graft_list_add(res, graft);
610	}
611	if (i < n)
612		res = isl_ast_graft_list_free(res);
613
614	isl_ast_graft_list_free(list);
615	clear_if_nodes(if_node, 0, n_if);
616	free(if_node);
617	return res;
618}
619
620/* Collect the nodes contained in the grafts in "list" in a node list.
621 */
622static __isl_give isl_ast_node_list *extract_node_list(
623	__isl_keep isl_ast_graft_list *list)
624{
625	int i, n;
626	isl_ctx *ctx;
627	isl_ast_node_list *node_list;
628
629	if (!list)
630		return NULL;
631	ctx = isl_ast_graft_list_get_ctx(list);
632	n = isl_ast_graft_list_n_ast_graft(list);
633	node_list = isl_ast_node_list_alloc(ctx, n);
634	for (i = 0; i < n; ++i) {
635		isl_ast_node *node;
636		isl_ast_graft *graft;
637
638		graft = isl_ast_graft_list_get_ast_graft(list, i);
639		node = isl_ast_graft_get_node(graft);
640		node_list = isl_ast_node_list_add(node_list, node);
641		isl_ast_graft_free(graft);
642	}
643
644	return node_list;
645}
646
647/* Look for shared enforced constraints by all the elements in "list"
648 * on outer loops (with respect to the current depth) and return the result.
649 *
650 * We assume that the number of children is at least one.
651 */
652static __isl_give isl_basic_set *extract_shared_enforced(
653	__isl_keep isl_ast_graft_list *list,
654	__isl_keep isl_ast_build *build)
655{
656	int i, n;
657	int depth;
658	isl_space *space;
659	isl_basic_set *enforced;
660
661	if (!list)
662		return NULL;
663
664	n = isl_ast_graft_list_n_ast_graft(list);
665	if (n == 0)
666		isl_die(isl_ast_graft_list_get_ctx(list), isl_error_invalid,
667			"for node should have at least one child",
668			return NULL);
669
670	space = isl_ast_build_get_space(build, 1);
671	enforced = isl_basic_set_empty(space);
672
673	depth = isl_ast_build_get_depth(build);
674	for (i = 0; i < n; ++i) {
675		isl_ast_graft *graft;
676
677		graft = isl_ast_graft_list_get_ast_graft(list, i);
678		enforced = update_enforced(enforced, graft, depth);
679		isl_ast_graft_free(graft);
680	}
681
682	return enforced;
683}
684
685/* Record "guard" in "graft" so that it will be enforced somewhere
686 * up the tree.  If the graft already has a guard, then it may be partially
687 * redundant in combination with the new guard and in the context
688 * of build->domain.  We therefore (re)compute the gist of the intersection
689 * and coalesce the result.
690 */
691static __isl_give isl_ast_graft *store_guard(__isl_take isl_ast_graft *graft,
692	__isl_take isl_set *guard, __isl_keep isl_ast_build *build)
693{
694	int is_universe;
695
696	if (!graft)
697		goto error;
698
699	is_universe = isl_set_plain_is_universe(guard);
700	if (is_universe < 0)
701		goto error;
702	if (is_universe) {
703		isl_set_free(guard);
704		return graft;
705	}
706
707	graft->guard = isl_set_intersect(graft->guard, guard);
708	graft->guard = isl_ast_build_compute_gist(build, graft->guard);
709	graft->guard = isl_set_coalesce(graft->guard);
710	if (!graft->guard)
711		return isl_ast_graft_free(graft);
712
713	return graft;
714error:
715	isl_set_free(guard);
716	return isl_ast_graft_free(graft);
717}
718
719/* For each graft in "list", replace its guard with the gist with
720 * respect to "context".
721 */
722static __isl_give isl_ast_graft_list *gist_guards(
723	__isl_take isl_ast_graft_list *list, __isl_keep isl_set *context)
724{
725	int i, n;
726
727	if (!list)
728		return NULL;
729
730	n = isl_ast_graft_list_n_ast_graft(list);
731	for (i = 0; i < n; ++i) {
732		isl_ast_graft *graft;
733
734		graft = isl_ast_graft_list_get_ast_graft(list, i);
735		if (!graft)
736			break;
737		graft->guard = isl_set_gist(graft->guard,
738						isl_set_copy(context));
739		if (!graft->guard)
740			graft = isl_ast_graft_free(graft);
741		list = isl_ast_graft_list_set_ast_graft(list, i, graft);
742	}
743	if (i < n)
744		return isl_ast_graft_list_free(list);
745
746	return list;
747}
748
749/* Combine the grafts in the list into a single graft.
750 *
751 * If "up" is set then the resulting graft will be used at an outer level.
752 * In this case, "build" refers to the outer level, while "sub_build"
753 * refers to the inner level.  If "up" is not set, then the same build
754 * should be passed to both arguments.
755 *
756 * The guard is initialized to the shared guard of the list elements (if any),
757 * provided it does not depend on the current dimension.
758 * The guards in the elements are then simplified with respect to the
759 * hoisted guard and materialized as if nodes around the contained AST nodes
760 * in the context of "sub_build".
761 *
762 * The enforced set is initialized to the simple hull of the enforced sets
763 * of the elements, provided the ast_build_exploit_nested_bounds option is set
764 * or the new graft will be used at the same level.
765 *
766 * The node is initialized to either a block containing the nodes of "list"
767 * or, if there is only a single element, the node of that element.
768 */
769static __isl_give isl_ast_graft *ast_graft_list_fuse(
770	__isl_take isl_ast_graft_list *list, __isl_keep isl_ast_build *build,
771	__isl_keep isl_ast_build *sub_build, int up)
772{
773	isl_ctx *ctx;
774	isl_ast_node *node;
775	isl_ast_graft *graft;
776	isl_ast_node_list *node_list;
777	isl_set *guard;
778
779	if (!list)
780		return NULL;
781
782	ctx = isl_ast_build_get_ctx(build);
783	guard = extract_hoistable_guard(list, build);
784	list = gist_guards(list, guard);
785	list = insert_pending_guard_nodes(list, sub_build);
786
787	node_list = extract_node_list(list);
788	node = isl_ast_node_from_ast_node_list(node_list);
789
790	graft = isl_ast_graft_alloc(node, build);
791
792	if (!up || isl_options_get_ast_build_exploit_nested_bounds(ctx)) {
793		isl_basic_set *enforced;
794		enforced = extract_shared_enforced(list, build);
795		graft = isl_ast_graft_enforce(graft, enforced);
796	}
797
798	graft = store_guard(graft, guard, build);
799
800	isl_ast_graft_list_free(list);
801	return graft;
802}
803
804/* Combine the grafts in the list into a single graft.
805 * Return a list containing this single graft.
806 * If the original list is empty, then return an empty list.
807 */
808__isl_give isl_ast_graft_list *isl_ast_graft_list_fuse(
809	__isl_take isl_ast_graft_list *list,
810	__isl_keep isl_ast_build *build)
811{
812	isl_ast_graft *graft;
813
814	if (!list)
815		return NULL;
816	if (isl_ast_graft_list_n_ast_graft(list) <= 1)
817		return list;
818	graft = ast_graft_list_fuse(list, build, build, 0);
819	return isl_ast_graft_list_from_ast_graft(graft);
820}
821
822/* Combine the two grafts into a single graft.
823 * Return a list containing this single graft.
824 */
825static __isl_give isl_ast_graft *isl_ast_graft_fuse(
826	__isl_take isl_ast_graft *graft1, __isl_take isl_ast_graft *graft2,
827	__isl_keep isl_ast_build *build)
828{
829	isl_ctx *ctx;
830	isl_ast_graft_list *list;
831
832	ctx = isl_ast_build_get_ctx(build);
833
834	list = isl_ast_graft_list_alloc(ctx, 2);
835	list = isl_ast_graft_list_add(list, graft1);
836	list = isl_ast_graft_list_add(list, graft2);
837
838	return ast_graft_list_fuse(list, build, build, 0);
839}
840
841/* Allocate a graft for the current level based on the list of grafts
842 * of the inner level.
843 * "build" represents the context of the current level.
844 * "sub_build" represents the context of the inner level.
845 *
846 * The node is initialized to either a block containing the nodes of "children"
847 * or, if there is only a single child, the node of that child.
848 * If the current level requires a for node, it should be inserted by
849 * a subsequent call to isl_ast_graft_insert_for.
850 */
851__isl_give isl_ast_graft *isl_ast_graft_alloc_level(
852	__isl_take isl_ast_graft_list *children,
853	__isl_keep isl_ast_build *build, __isl_keep isl_ast_build *sub_build)
854{
855	return ast_graft_list_fuse(children, build, sub_build, 1);
856}
857
858/* Insert a for node enclosing the current graft->node.
859 */
860__isl_give isl_ast_graft *isl_ast_graft_insert_for(
861	__isl_take isl_ast_graft *graft, __isl_take isl_ast_node *node)
862{
863	if (!graft)
864		goto error;
865
866	graft->node = isl_ast_node_for_set_body(node, graft->node);
867	if (!graft->node)
868		return isl_ast_graft_free(graft);
869
870	return graft;
871error:
872	isl_ast_node_free(node);
873	isl_ast_graft_free(graft);
874	return NULL;
875}
876
877/* Represent the graft list as an AST node.
878 * This operation drops the information about guards in the grafts, so
879 * if there are any pending guards, then they are materialized as if nodes.
880 */
881__isl_give isl_ast_node *isl_ast_node_from_graft_list(
882	__isl_take isl_ast_graft_list *list,
883	__isl_keep isl_ast_build *build)
884{
885	isl_ast_node_list *node_list;
886
887	list = insert_pending_guard_nodes(list, build);
888	node_list = extract_node_list(list);
889	isl_ast_graft_list_free(list);
890
891	return isl_ast_node_from_ast_node_list(node_list);
892}
893
894void *isl_ast_graft_free(__isl_take isl_ast_graft *graft)
895{
896	if (!graft)
897		return NULL;
898
899	if (--graft->ref > 0)
900		return NULL;
901
902	isl_ast_node_free(graft->node);
903	isl_set_free(graft->guard);
904	isl_basic_set_free(graft->enforced);
905	free(graft);
906
907	return NULL;
908}
909
910/* Record that the grafted tree enforces
911 * "enforced" by intersecting graft->enforced with "enforced".
912 */
913__isl_give isl_ast_graft *isl_ast_graft_enforce(
914	__isl_take isl_ast_graft *graft, __isl_take isl_basic_set *enforced)
915{
916	if (!graft || !enforced)
917		goto error;
918
919	enforced = isl_basic_set_align_params(enforced,
920				isl_basic_set_get_space(graft->enforced));
921	graft->enforced = isl_basic_set_align_params(graft->enforced,
922				isl_basic_set_get_space(enforced));
923	graft->enforced = isl_basic_set_intersect(graft->enforced, enforced);
924	if (!graft->enforced)
925		return isl_ast_graft_free(graft);
926
927	return graft;
928error:
929	isl_basic_set_free(enforced);
930	return isl_ast_graft_free(graft);
931}
932
933__isl_give isl_basic_set *isl_ast_graft_get_enforced(
934	__isl_keep isl_ast_graft *graft)
935{
936	return graft ? isl_basic_set_copy(graft->enforced) : NULL;
937}
938
939__isl_give isl_set *isl_ast_graft_get_guard(__isl_keep isl_ast_graft *graft)
940{
941	return graft ? isl_set_copy(graft->guard) : NULL;
942}
943
944/* Record that "guard" needs to be inserted in "graft".
945 *
946 * We first simplify the guard in the context of the enforced set and
947 * then we store the guard in case we may be able
948 * to hoist it to higher levels and/or combine it with those of other grafts.
949 */
950__isl_give isl_ast_graft *isl_ast_graft_add_guard(
951	__isl_take isl_ast_graft *graft,
952	__isl_take isl_set *guard, __isl_keep isl_ast_build *build)
953{
954	isl_basic_set *enforced;
955
956	if (!graft || !build)
957		goto error;
958
959	enforced = isl_basic_set_copy(graft->enforced);
960	guard = isl_set_gist(guard, isl_set_from_basic_set(enforced));
961
962	graft = store_guard(graft, guard, build);
963
964	return graft;
965error:
966	isl_set_free(guard);
967	isl_ast_graft_free(graft);
968	return NULL;
969}
970
971/* Reformulate the "graft", which was generated in the context
972 * of an inner code generation, in terms of the outer code generation
973 * AST build.
974 *
975 * If "product" is set, then the domain of the inner code generation build is
976 *
977 *	[O -> S]
978 *
979 * with O the domain of the outer code generation build.
980 * We essentially need to project out S.
981 *
982 * If "product" is not set, then we need to project the domains onto
983 * their parameter spaces.
984 */
985__isl_give isl_ast_graft *isl_ast_graft_unembed(__isl_take isl_ast_graft *graft,
986	int product)
987{
988	isl_basic_set *enforced;
989
990	if (!graft)
991		return NULL;
992
993	if (product) {
994		enforced = graft->enforced;
995		enforced = isl_basic_map_domain(isl_basic_set_unwrap(enforced));
996		graft->enforced = enforced;
997		graft->guard = isl_map_domain(isl_set_unwrap(graft->guard));
998	} else {
999		graft->enforced = isl_basic_set_params(graft->enforced);
1000		graft->guard = isl_set_params(graft->guard);
1001	}
1002	graft->guard = isl_set_compute_divs(graft->guard);
1003
1004	if (!graft->enforced || !graft->guard)
1005		return isl_ast_graft_free(graft);
1006
1007	return graft;
1008}
1009
1010/* Reformulate the grafts in "list", which were generated in the context
1011 * of an inner code generation, in terms of the outer code generation
1012 * AST build.
1013 */
1014__isl_give isl_ast_graft_list *isl_ast_graft_list_unembed(
1015	__isl_take isl_ast_graft_list *list, int product)
1016{
1017	int i, n;
1018
1019	n = isl_ast_graft_list_n_ast_graft(list);
1020	for (i = 0; i < n; ++i) {
1021		isl_ast_graft *graft;
1022
1023		graft = isl_ast_graft_list_get_ast_graft(list, i);
1024		graft = isl_ast_graft_unembed(graft, product);
1025		list = isl_ast_graft_list_set_ast_graft(list, i, graft);
1026	}
1027
1028	return list;
1029}
1030
1031/* Compute the preimage of "graft" under the function represented by "ma".
1032 * In other words, plug in "ma" in "enforced" and "guard" fields of "graft".
1033 */
1034__isl_give isl_ast_graft *isl_ast_graft_preimage_multi_aff(
1035	__isl_take isl_ast_graft *graft, __isl_take isl_multi_aff *ma)
1036{
1037	isl_basic_set *enforced;
1038
1039	if (!graft)
1040		return NULL;
1041
1042	enforced = graft->enforced;
1043	graft->enforced = isl_basic_set_preimage_multi_aff(enforced,
1044						isl_multi_aff_copy(ma));
1045	graft->guard = isl_set_preimage_multi_aff(graft->guard, ma);
1046
1047	if (!graft->enforced || !graft->guard)
1048		return isl_ast_graft_free(graft);
1049
1050	return graft;
1051}
1052
1053/* Compute the preimage of all the grafts in "list" under
1054 * the function represented by "ma".
1055 */
1056__isl_give isl_ast_graft_list *isl_ast_graft_list_preimage_multi_aff(
1057	__isl_take isl_ast_graft_list *list, __isl_take isl_multi_aff *ma)
1058{
1059	int i, n;
1060
1061	n = isl_ast_graft_list_n_ast_graft(list);
1062	for (i = 0; i < n; ++i) {
1063		isl_ast_graft *graft;
1064
1065		graft = isl_ast_graft_list_get_ast_graft(list, i);
1066		graft = isl_ast_graft_preimage_multi_aff(graft,
1067						    isl_multi_aff_copy(ma));
1068		list = isl_ast_graft_list_set_ast_graft(list, i, graft);
1069	}
1070
1071	isl_multi_aff_free(ma);
1072	return list;
1073}
1074
1075/* Compare two grafts based on their guards.
1076 */
1077static int cmp_graft(__isl_keep isl_ast_graft *a, __isl_keep isl_ast_graft *b,
1078	void *user)
1079{
1080	return isl_set_plain_cmp(a->guard, b->guard);
1081}
1082
1083/* Order the elements in "list" based on their guards.
1084 */
1085__isl_give isl_ast_graft_list *isl_ast_graft_list_sort_guard(
1086	__isl_take isl_ast_graft_list *list)
1087{
1088	return isl_ast_graft_list_sort(list, &cmp_graft, NULL);
1089}
1090
1091/* Merge the given two lists into a single list of grafts,
1092 * merging grafts with the same guard into a single graft.
1093 *
1094 * "list2" has been sorted using isl_ast_graft_list_sort.
1095 * "list1" may be the result of a previous call to isl_ast_graft_list_merge
1096 * and may therefore not be completely sorted.
1097 *
1098 * The elements in "list2" need to be executed after those in "list1",
1099 * but if the guard of a graft in "list2" is disjoint from the guards
1100 * of some final elements in "list1", then it can be moved up to before
1101 * those final elements.
1102 *
1103 * In particular, we look at each element g of "list2" in turn
1104 * and move it up beyond elements of "list1" that would be sorted
1105 * after g as long as each of these elements has a guard that is disjoint
1106 * from that of g.
1107 *
1108 * We do not allow the second or any later element of "list2" to be moved
1109 * before a previous elements of "list2" even if the reason that
1110 * that element didn't move up further was that its guard was not disjoint
1111 * from that of the previous element in "list1".
1112 */
1113__isl_give isl_ast_graft_list *isl_ast_graft_list_merge(
1114	__isl_take isl_ast_graft_list *list1,
1115	__isl_take isl_ast_graft_list *list2,
1116	__isl_keep isl_ast_build *build)
1117{
1118	int i, j, first;
1119
1120	if (!list1 || !list2 || !build)
1121		goto error;
1122	if (list2->n == 0) {
1123		isl_ast_graft_list_free(list2);
1124		return list1;
1125	}
1126	if (list1->n == 0) {
1127		isl_ast_graft_list_free(list1);
1128		return list2;
1129	}
1130
1131	first = 0;
1132	for (i = 0; i < list2->n; ++i) {
1133		isl_ast_graft *graft;
1134		graft = isl_ast_graft_list_get_ast_graft(list2, i);
1135		if (!graft)
1136			break;
1137
1138		for (j = list1->n; j >= 0; --j) {
1139			int cmp, disjoint;
1140			isl_ast_graft *graft_j;
1141
1142			if (j == first)
1143				cmp = -1;
1144			else
1145				cmp = isl_set_plain_cmp(list1->p[j - 1]->guard,
1146							graft->guard);
1147			if (cmp > 0) {
1148				disjoint = isl_set_is_disjoint(graft->guard,
1149							list1->p[j - 1]->guard);
1150				if (disjoint < 0) {
1151					list1 = isl_ast_graft_list_free(list1);
1152					break;
1153				}
1154				if (!disjoint)
1155					cmp = -1;
1156			}
1157			if (cmp > 0)
1158				continue;
1159			if (cmp < 0) {
1160				list1 = isl_ast_graft_list_insert(list1, j,
1161								graft);
1162				break;
1163			}
1164
1165			--j;
1166
1167			graft_j = isl_ast_graft_list_get_ast_graft(list1, j);
1168			graft_j = isl_ast_graft_fuse(graft_j, graft, build);
1169			list1 = isl_ast_graft_list_set_ast_graft(list1, j,
1170								graft_j);
1171			break;
1172		}
1173
1174		if (j < 0)
1175			isl_die(isl_ast_build_get_ctx(build),
1176				isl_error_internal,
1177				"element failed to get inserted", break);
1178
1179		first = j + 1;
1180		if (!list1)
1181			break;
1182	}
1183	if (i < list2->n)
1184		list1 = isl_ast_graft_list_free(list1);
1185	isl_ast_graft_list_free(list2);
1186
1187	return list1;
1188error:
1189	isl_ast_graft_list_free(list1);
1190	isl_ast_graft_list_free(list2);
1191	return NULL;
1192}
1193
1194__isl_give isl_printer *isl_printer_print_ast_graft(__isl_take isl_printer *p,
1195	__isl_keep isl_ast_graft *graft)
1196{
1197	if (!p)
1198		return NULL;
1199	if (!graft)
1200		return isl_printer_free(p);
1201
1202	p = isl_printer_print_str(p, "(");
1203	p = isl_printer_print_str(p, "guard: ");
1204	p = isl_printer_print_set(p, graft->guard);
1205	p = isl_printer_print_str(p, ", ");
1206	p = isl_printer_print_str(p, "enforced: ");
1207	p = isl_printer_print_basic_set(p, graft->enforced);
1208	p = isl_printer_print_str(p, ", ");
1209	p = isl_printer_print_str(p, "node: ");
1210	p = isl_printer_print_ast_node(p, graft->node);
1211	p = isl_printer_print_str(p, ")");
1212
1213	return p;
1214}
1215