/* 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.
* Otherwise, we return the unshifted simple hull of the guards.
*
* 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.
*/
static __isl_give isl_set *extract_hoistable_guard(
__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;
isl_set *guard;
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;
graft_0 = isl_ast_graft_list_get_ast_graft(list, 0);
if (!graft_0)
return NULL;
guard = isl_set_copy(graft_0->guard);
isl_ast_graft_free(graft_0);
if (equal)
return guard;
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);
}
for (i = 1; i < n; ++i) {
isl_ast_graft *graft;
isl_basic_set *hull;
int is_universe;
is_universe = isl_set_plain_is_universe(guard);
if (is_universe < 0)
guard = isl_set_free(guard);
if (is_universe)
break;
graft = isl_ast_graft_list_get_ast_graft(list, i);
if (!graft) {
guard = isl_set_free(guard);
break;
}
guard = isl_set_union(guard, isl_set_copy(graft->guard));
hull = isl_set_unshifted_simple_hull(guard);
guard = isl_set_from_basic_set(hull);
isl_ast_graft_free(graft);
}
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);
}
/* 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);
}
/* 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);
if (isl_set_dim(graft_0->guard, isl_dim_set) <= depth)
skip = 0;
else
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;
}
