/* Compute the affine hull of "bset", where "cone" is the recession cone * of "bset". * * We first compute a unimodular transformation that puts the unbounded * directions in the last dimensions. In particular, we take a transformation * that maps all equalities to equalities (in HNF) on the first dimensions. * Let x be the original dimensions and y the transformed, with y_1 bounded * and y_2 unbounded. * * [ y_1 ] [ y_1 ] [ Q_1 ] * x = U [ y_2 ] [ y_2 ] = [ Q_2 ] x * * Let's call the input basic set S. We compute S' = preimage(S, U) * and drop the final dimensions including any constraints involving them. * This results in set S''. * Then we compute the affine hull A'' of S''. * Let F y_1 >= g be the constraint system of A''. In the transformed * space the y_2 are unbounded, so we can add them back without any constraints, * resulting in * * [ y_1 ] * [ F 0 ] [ y_2 ] >= g * or * [ Q_1 ] * [ F 0 ] [ Q_2 ] x >= g * or * F Q_1 x >= g * * The affine hull in the original space is then obtained as * A = preimage(A'', Q_1). */ static struct isl_basic_set *affine_hull_with_cone(struct isl_basic_set *bset, struct isl_basic_set *cone) { unsigned total; unsigned cone_dim; struct isl_basic_set *hull; struct isl_mat *M, *U, *Q; if (!bset || !cone) goto error; total = isl_basic_set_total_dim(cone); cone_dim = total - cone->n_eq; M = isl_mat_sub_alloc6(bset->ctx, cone->eq, 0, cone->n_eq, 1, total); M = isl_mat_left_hermite(M, 0, &U, &Q); if (!M) goto error; isl_mat_free(M); U = isl_mat_lin_to_aff(U); bset = isl_basic_set_preimage(bset, isl_mat_copy(U)); bset = isl_basic_set_drop_constraints_involving(bset, total - cone_dim, cone_dim); bset = isl_basic_set_drop_dims(bset, total - cone_dim, cone_dim); Q = isl_mat_lin_to_aff(Q); Q = isl_mat_drop_rows(Q, 1 + total - cone_dim, cone_dim); if (bset && bset->sample && bset->sample->size == 1 + total) bset->sample = isl_mat_vec_product(isl_mat_copy(Q), bset->sample); hull = uset_affine_hull_bounded(bset); if (!hull) isl_mat_free(U); else { struct isl_vec *sample = isl_vec_copy(hull->sample); U = isl_mat_drop_cols(U, 1 + total - cone_dim, cone_dim); if (sample && sample->size > 0) sample = isl_mat_vec_product(U, sample); else isl_mat_free(U); hull = isl_basic_set_preimage(hull, Q); if (hull) { isl_vec_free(hull->sample); hull->sample = sample; } else isl_vec_free(sample); } isl_basic_set_free(cone); return hull; error: isl_basic_set_free(bset); isl_basic_set_free(cone); return NULL; }
/* Look for all equalities satisfied by the integer points in bmap * that are independent of the equalities already explicitly available * in bmap. * * We first remove all equalities already explicitly available, * then look for additional equalities in the reduced space * and then transform the result to the original space. * The original equalities are _not_ added to this set. This is * the responsibility of the calling function. * The resulting basic set has all meaning about the dimensions removed. * In particular, dimensions that correspond to existential variables * in bmap and that are found to be fixed are not removed. */ static struct isl_basic_set *equalities_in_underlying_set( struct isl_basic_map *bmap) { struct isl_mat *T1 = NULL; struct isl_mat *T2 = NULL; struct isl_basic_set *bset = NULL; struct isl_basic_set *hull = NULL; bset = isl_basic_map_underlying_set(bmap); if (!bset) return NULL; if (bset->n_eq) bset = isl_basic_set_remove_equalities(bset, &T1, &T2); if (!bset) goto error; hull = uset_affine_hull(bset); if (!T2) return hull; if (!hull) { isl_mat_free(T1); isl_mat_free(T2); } else { struct isl_vec *sample = isl_vec_copy(hull->sample); if (sample && sample->size > 0) sample = isl_mat_vec_product(T1, sample); else isl_mat_free(T1); hull = isl_basic_set_preimage(hull, T2); if (hull) { isl_vec_free(hull->sample); hull->sample = sample; } else isl_vec_free(sample); } return hull; error: isl_mat_free(T2); isl_basic_set_free(bset); isl_basic_set_free(hull); return NULL; }
/* Use the n equalities of bset to unimodularly transform the * variables x such that n transformed variables x1' have a constant value * and rewrite the constraints of bset in terms of the remaining * transformed variables x2'. The matrix pointed to by T maps * the new variables x2' back to the original variables x, while T2 * maps the original variables to the new variables. */ static struct isl_basic_set *compress_variables( struct isl_basic_set *bset, struct isl_mat **T, struct isl_mat **T2) { struct isl_mat *B, *TC; unsigned dim; if (T) *T = NULL; if (T2) *T2 = NULL; if (!bset) goto error; isl_assert(bset->ctx, isl_basic_set_n_param(bset) == 0, goto error); isl_assert(bset->ctx, bset->n_div == 0, goto error); dim = isl_basic_set_n_dim(bset); isl_assert(bset->ctx, bset->n_eq <= dim, goto error); if (bset->n_eq == 0) return bset; B = isl_mat_sub_alloc6(bset->ctx, bset->eq, 0, bset->n_eq, 0, 1 + dim); TC = isl_mat_variable_compression(B, T2); if (!TC) goto error; if (TC->n_col == 0) { isl_mat_free(TC); if (T2) { isl_mat_free(*T2); *T2 = NULL; } return isl_basic_set_set_to_empty(bset); } bset = isl_basic_set_preimage(bset, T ? isl_mat_copy(TC) : TC); if (T) *T = TC; return bset; error: isl_basic_set_free(bset); return NULL; }