/* 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;
}
/* 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;
}
