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/*
* Copyright 2006-2007 Universiteit Leiden
* Copyright 2008-2009 Katholieke Universiteit Leuven
* Copyright 2010 INRIA Saclay
*
* Use of this software is governed by the MIT license
*
* Written by Sven Verdoolaege, Leiden Institute of Advanced Computer Science,
* Universiteit Leiden, Niels Bohrweg 1, 2333 CA Leiden, The Netherlands
* and K.U.Leuven, Departement Computerwetenschappen, Celestijnenlaan 200A,
* B-3001 Leuven, Belgium
* and INRIA Saclay - Ile-de-France, Parc Club Orsay Universite,
* ZAC des vignes, 4 rue Jacques Monod, 91893 Orsay, France
*/
#include <isl_ctx_private.h>
#include <isl_map_private.h>
#include <isl/set.h>
#include <isl_seq.h>
#include <isl_morph.h>
#include <isl_factorization.h>
#include <isl_vertices_private.h>
#include <isl_polynomial_private.h>
#include <isl_options_private.h>
#include <isl_vec_private.h>
#include <isl_bernstein.h>
struct bernstein_data {
enum isl_fold type;
isl_qpolynomial *poly;
int check_tight;
isl_cell *cell;
isl_qpolynomial_fold *fold;
isl_qpolynomial_fold *fold_tight;
isl_pw_qpolynomial_fold *pwf;
isl_pw_qpolynomial_fold *pwf_tight;
};
static isl_bool vertex_is_integral(__isl_keep isl_basic_set *vertex)
{
isl_size nvar;
isl_size nparam;
int i;
nvar = isl_basic_set_dim(vertex, isl_dim_set);
nparam = isl_basic_set_dim(vertex, isl_dim_param);
if (nvar < 0 || nparam < 0)
return isl_bool_error;
for (i = 0; i < nvar; ++i) {
int r = nvar - 1 - i;
if (!isl_int_is_one(vertex->eq[r][1 + nparam + i]) &&
!isl_int_is_negone(vertex->eq[r][1 + nparam + i]))
return isl_bool_false;
}
return isl_bool_true;
}
static __isl_give isl_qpolynomial *vertex_coordinate(
__isl_keep isl_basic_set *vertex, int i, __isl_take isl_space *space)
{
isl_size nvar;
isl_size nparam;
isl_size total;
int r;
isl_int denom;
isl_qpolynomial *v;
isl_int_init(denom);
nvar = isl_basic_set_dim(vertex, isl_dim_set);
nparam = isl_basic_set_dim(vertex, isl_dim_param);
total = isl_basic_set_dim(vertex, isl_dim_all);
if (nvar < 0 || nparam < 0 || total < 0)
goto error;
r = nvar - 1 - i;
isl_int_set(denom, vertex->eq[r][1 + nparam + i]);
isl_assert(vertex->ctx, !isl_int_is_zero(denom), goto error);
if (isl_int_is_pos(denom))
isl_seq_neg(vertex->eq[r], vertex->eq[r], 1 + total);
else
isl_int_neg(denom, denom);
v = isl_qpolynomial_from_affine(space, vertex->eq[r], denom);
isl_int_clear(denom);
return v;
error:
isl_space_free(space);
isl_int_clear(denom);
return NULL;
}
/* Check whether the bound associated to the selection "k" is tight,
* which is the case if we select exactly one vertex (i.e., one of the
* exponents in "k" is exactly "d") and if that vertex
* is integral for all values of the parameters.
*
* If the degree "d" is zero, then there are no exponents.
* Since the polynomial is a constant expression in this case,
* the bound is necessarily tight.
*/
static isl_bool is_tight(int *k, int n, int d, isl_cell *cell)
{
int i;
if (d == 0)
return isl_bool_true;
for (i = 0; i < n; ++i) {
int v;
if (!k[i])
continue;
if (k[i] != d)
return isl_bool_false;
v = cell->ids[n - 1 - i];
return vertex_is_integral(cell->vertices->v[v].vertex);
}
return isl_bool_false;
}
static isl_stat add_fold(__isl_take isl_qpolynomial *b, __isl_keep isl_set *dom,
int *k, int n, int d, struct bernstein_data *data)
{
isl_qpolynomial_fold *fold;
isl_bool tight;
fold = isl_qpolynomial_fold_alloc(data->type, b);
tight = isl_bool_false;
if (data->check_tight)
tight = is_tight(k, n, d, data->cell);
if (tight < 0)
return isl_stat_error;
if (tight)
data->fold_tight = isl_qpolynomial_fold_fold_on_domain(dom,
data->fold_tight, fold);
else
data->fold = isl_qpolynomial_fold_fold_on_domain(dom,
data->fold, fold);
return isl_stat_ok;
}
/* Extract the coefficients of the Bernstein base polynomials and store
* them in data->fold and data->fold_tight.
*
* In particular, the coefficient of each monomial
* of multi-degree (k[0], k[1], ..., k[n-1]) is divided by the corresponding
* multinomial coefficient d!/k[0]! k[1]! ... k[n-1]!
*
* c[i] contains the coefficient of the selected powers of the first i+1 vars.
* multinom[i] contains the partial multinomial coefficient.
*/
static isl_stat extract_coefficients(isl_qpolynomial *poly,
__isl_keep isl_set *dom, struct bernstein_data *data)
{
int i;
int d;
isl_size n;
isl_ctx *ctx;
isl_qpolynomial **c = NULL;
int *k = NULL;
int *left = NULL;
isl_vec *multinom = NULL;
n = isl_qpolynomial_dim(poly, isl_dim_in);
if (n < 0)
return isl_stat_error;
ctx = isl_qpolynomial_get_ctx(poly);
d = isl_qpolynomial_degree(poly);
isl_assert(ctx, n >= 2, return isl_stat_error);
c = isl_calloc_array(ctx, isl_qpolynomial *, n);
k = isl_alloc_array(ctx, int, n);
left = isl_alloc_array(ctx, int, n);
multinom = isl_vec_alloc(ctx, n);
if (!c || !k || !left || !multinom)
goto error;
isl_int_set_si(multinom->el[0], 1);
for (k[0] = d; k[0] >= 0; --k[0]) {
int i = 1;
isl_qpolynomial_free(c[0]);
c[0] = isl_qpolynomial_coeff(poly, isl_dim_in, n - 1, k[0]);
left[0] = d - k[0];
k[1] = -1;
isl_int_set(multinom->el[1], multinom->el[0]);
while (i > 0) {
if (i == n - 1) {
int j;
isl_space *space;
isl_qpolynomial *b;
isl_qpolynomial *f;
for (j = 2; j <= left[i - 1]; ++j)
isl_int_divexact_ui(multinom->el[i],
multinom->el[i], j);
b = isl_qpolynomial_coeff(c[i - 1], isl_dim_in,
n - 1 - i, left[i - 1]);
b = isl_qpolynomial_project_domain_on_params(b);
space = isl_qpolynomial_get_domain_space(b);
f = isl_qpolynomial_rat_cst_on_domain(space,
ctx->one, multinom->el[i]);
b = isl_qpolynomial_mul(b, f);
k[n - 1] = left[n - 2];
if (add_fold(b, dom, k, n, d, data) < 0)
goto error;
--i;
continue;
}
if (k[i] >= left[i - 1]) {
--i;
continue;
}
++k[i];
if (k[i])
isl_int_divexact_ui(multinom->el[i],
multinom->el[i], k[i]);
isl_qpolynomial_free(c[i]);
c[i] = isl_qpolynomial_coeff(c[i - 1], isl_dim_in,
n - 1 - i, k[i]);
left[i] = left[i - 1] - k[i];
k[i + 1] = -1;
isl_int_set(multinom->el[i + 1], multinom->el[i]);
++i;
}
isl_int_mul_ui(multinom->el[0], multinom->el[0], k[0]);
}
for (i = 0; i < n; ++i)
isl_qpolynomial_free(c[i]);
isl_vec_free(multinom);
free(left);
free(k);
free(c);
return isl_stat_ok;
error:
isl_vec_free(multinom);
free(left);
free(k);
if (c)
for (i = 0; i < n; ++i)
isl_qpolynomial_free(c[i]);
free(c);
return isl_stat_error;
}
/* Perform bernstein expansion on the parametric vertices that are active
* on "cell".
*
* data->poly has been homogenized in the calling function.
*
* We plug in the barycentric coordinates for the set variables
*
* \vec x = \sum_i \alpha_i v_i(\vec p)
*
* and the constant "1 = \sum_i \alpha_i" for the homogeneous dimension.
* Next, we extract the coefficients of the Bernstein base polynomials.
*/
static isl_stat bernstein_coefficients_cell(__isl_take isl_cell *cell,
void *user)
{
int i, j;
struct bernstein_data *data = (struct bernstein_data *)user;
isl_space *space_param;
isl_space *space_dst;
isl_qpolynomial *poly = data->poly;
isl_size n_in;
unsigned nvar;
int n_vertices;
isl_qpolynomial **subs;
isl_pw_qpolynomial_fold *pwf;
isl_set *dom;
isl_ctx *ctx;
n_in = isl_qpolynomial_dim(poly, isl_dim_in);
if (n_in < 0)
goto error;
nvar = n_in - 1;
n_vertices = cell->n_vertices;
ctx = isl_qpolynomial_get_ctx(poly);
if (n_vertices > nvar + 1 && ctx->opt->bernstein_triangulate)
return isl_cell_foreach_simplex(cell,
&bernstein_coefficients_cell, user);
subs = isl_alloc_array(ctx, isl_qpolynomial *, 1 + nvar);
if (!subs)
goto error;
space_param = isl_basic_set_get_space(cell->dom);
space_dst = isl_qpolynomial_get_domain_space(poly);
space_dst = isl_space_add_dims(space_dst, isl_dim_set, n_vertices);
for (i = 0; i < 1 + nvar; ++i)
subs[i] =
isl_qpolynomial_zero_on_domain(isl_space_copy(space_dst));
for (i = 0; i < n_vertices; ++i) {
isl_qpolynomial *c;
c = isl_qpolynomial_var_on_domain(isl_space_copy(space_dst),
isl_dim_set, 1 + nvar + i);
for (j = 0; j < nvar; ++j) {
int k = cell->ids[i];
isl_qpolynomial *v;
v = vertex_coordinate(cell->vertices->v[k].vertex, j,
isl_space_copy(space_param));
v = isl_qpolynomial_add_dims(v, isl_dim_in,
1 + nvar + n_vertices);
v = isl_qpolynomial_mul(v, isl_qpolynomial_copy(c));
subs[1 + j] = isl_qpolynomial_add(subs[1 + j], v);
}
subs[0] = isl_qpolynomial_add(subs[0], c);
}
isl_space_free(space_dst);
poly = isl_qpolynomial_copy(poly);
poly = isl_qpolynomial_add_dims(poly, isl_dim_in, n_vertices);
poly = isl_qpolynomial_substitute(poly, isl_dim_in, 0, 1 + nvar, subs);
poly = isl_qpolynomial_drop_dims(poly, isl_dim_in, 0, 1 + nvar);
data->cell = cell;
dom = isl_set_from_basic_set(isl_basic_set_copy(cell->dom));
data->fold = isl_qpolynomial_fold_empty(data->type,
isl_space_copy(space_param));
data->fold_tight = isl_qpolynomial_fold_empty(data->type, space_param);
if (extract_coefficients(poly, dom, data) < 0) {
data->fold = isl_qpolynomial_fold_free(data->fold);
data->fold_tight = isl_qpolynomial_fold_free(data->fold_tight);
}
pwf = isl_pw_qpolynomial_fold_alloc(data->type, isl_set_copy(dom),
data->fold);
data->pwf = isl_pw_qpolynomial_fold_fold(data->pwf, pwf);
pwf = isl_pw_qpolynomial_fold_alloc(data->type, dom, data->fold_tight);
data->pwf_tight = isl_pw_qpolynomial_fold_fold(data->pwf_tight, pwf);
isl_qpolynomial_free(poly);
isl_cell_free(cell);
for (i = 0; i < 1 + nvar; ++i)
isl_qpolynomial_free(subs[i]);
free(subs);
return isl_stat_ok;
error:
isl_cell_free(cell);
return isl_stat_error;
}
/* Base case of applying bernstein expansion.
*
* We compute the chamber decomposition of the parametric polytope "bset"
* and then perform bernstein expansion on the parametric vertices
* that are active on each chamber.
*
* If the polynomial does not depend on the set variables
* (and in particular if the number of set variables is zero)
* then the bound is equal to the polynomial and
* no actual bernstein expansion needs to be performed.
*/
static __isl_give isl_pw_qpolynomial_fold *bernstein_coefficients_base(
__isl_take isl_basic_set *bset,
__isl_take isl_qpolynomial *poly, struct bernstein_data *data,
isl_bool *tight)
{
int degree;
isl_size nvar;
isl_space *space;
isl_vertices *vertices;
isl_bool covers;
nvar = isl_basic_set_dim(bset, isl_dim_set);
if (nvar < 0)
bset = isl_basic_set_free(bset);
if (nvar == 0)
return isl_qpolynomial_cst_bound(bset, poly, data->type, tight);
degree = isl_qpolynomial_degree(poly);
if (degree < -1)
bset = isl_basic_set_free(bset);
if (degree <= 0)
return isl_qpolynomial_cst_bound(bset, poly, data->type, tight);
space = isl_basic_set_get_space(bset);
space = isl_space_params(space);
space = isl_space_from_domain(space);
space = isl_space_add_dims(space, isl_dim_set, 1);
data->pwf = isl_pw_qpolynomial_fold_zero(isl_space_copy(space),
data->type);
data->pwf_tight = isl_pw_qpolynomial_fold_zero(space, data->type);
data->poly = isl_qpolynomial_homogenize(isl_qpolynomial_copy(poly));
vertices = isl_basic_set_compute_vertices(bset);
if (isl_vertices_foreach_disjoint_cell(vertices,
&bernstein_coefficients_cell, data) < 0)
data->pwf = isl_pw_qpolynomial_fold_free(data->pwf);
isl_vertices_free(vertices);
isl_qpolynomial_free(data->poly);
isl_basic_set_free(bset);
isl_qpolynomial_free(poly);
covers = isl_pw_qpolynomial_fold_covers(data->pwf_tight, data->pwf);
if (covers < 0)
goto error;
if (tight)
*tight = covers;
if (covers) {
isl_pw_qpolynomial_fold_free(data->pwf);
return data->pwf_tight;
}
data->pwf = isl_pw_qpolynomial_fold_fold(data->pwf, data->pwf_tight);
return data->pwf;
error:
isl_pw_qpolynomial_fold_free(data->pwf_tight);
isl_pw_qpolynomial_fold_free(data->pwf);
return NULL;
}
/* Apply bernstein expansion recursively by working in on len[i]
* set variables at a time, with i ranging from n_group - 1 to 0.
*/
static __isl_give isl_pw_qpolynomial_fold *bernstein_coefficients_recursive(
__isl_take isl_pw_qpolynomial *pwqp,
int n_group, int *len, struct bernstein_data *data, isl_bool *tight)
{
int i;
isl_size nparam;
isl_size nvar;
isl_pw_qpolynomial_fold *pwf;
nparam = isl_pw_qpolynomial_dim(pwqp, isl_dim_param);
nvar = isl_pw_qpolynomial_dim(pwqp, isl_dim_in);
if (nparam < 0 || nvar < 0)
goto error;
pwqp = isl_pw_qpolynomial_move_dims(pwqp, isl_dim_param, nparam,
isl_dim_in, 0, nvar - len[n_group - 1]);
pwf = isl_pw_qpolynomial_bound(pwqp, data->type, tight);
for (i = n_group - 2; i >= 0; --i) {
nparam = isl_pw_qpolynomial_fold_dim(pwf, isl_dim_param);
if (nparam < 0)
return isl_pw_qpolynomial_fold_free(pwf);
pwf = isl_pw_qpolynomial_fold_move_dims(pwf, isl_dim_in, 0,
isl_dim_param, nparam - len[i], len[i]);
if (tight && !*tight)
tight = NULL;
pwf = isl_pw_qpolynomial_fold_bound(pwf, tight);
}
return pwf;
error:
isl_pw_qpolynomial_free(pwqp);
return NULL;
}
static __isl_give isl_pw_qpolynomial_fold *bernstein_coefficients_factors(
__isl_take isl_basic_set *bset,
__isl_take isl_qpolynomial *poly, struct bernstein_data *data,
isl_bool *tight)
{
isl_factorizer *f;
isl_set *set;
isl_pw_qpolynomial *pwqp;
isl_pw_qpolynomial_fold *pwf;
f = isl_basic_set_factorizer(bset);
if (!f)
goto error;
if (f->n_group == 0) {
isl_factorizer_free(f);
return bernstein_coefficients_base(bset, poly, data, tight);
}
set = isl_set_from_basic_set(bset);
pwqp = isl_pw_qpolynomial_alloc(set, poly);
pwqp = isl_pw_qpolynomial_morph_domain(pwqp, isl_morph_copy(f->morph));
pwf = bernstein_coefficients_recursive(pwqp, f->n_group, f->len, data,
tight);
isl_factorizer_free(f);
return pwf;
error:
isl_basic_set_free(bset);
isl_qpolynomial_free(poly);
return NULL;
}
static __isl_give isl_pw_qpolynomial_fold *bernstein_coefficients_full_recursive(
__isl_take isl_basic_set *bset,
__isl_take isl_qpolynomial *poly, struct bernstein_data *data,
isl_bool *tight)
{
int i;
int *len;
isl_size nvar;
isl_pw_qpolynomial_fold *pwf;
isl_set *set;
isl_pw_qpolynomial *pwqp;
nvar = isl_basic_set_dim(bset, isl_dim_set);
if (nvar < 0 || !poly)
goto error;
len = isl_alloc_array(bset->ctx, int, nvar);
if (nvar && !len)
goto error;
for (i = 0; i < nvar; ++i)
len[i] = 1;
set = isl_set_from_basic_set(bset);
pwqp = isl_pw_qpolynomial_alloc(set, poly);
pwf = bernstein_coefficients_recursive(pwqp, nvar, len, data, tight);
free(len);
return pwf;
error:
isl_basic_set_free(bset);
isl_qpolynomial_free(poly);
return NULL;
}
/* Compute a bound on the polynomial defined over the parametric polytope
* using bernstein expansion and store the result
* in bound->pwf and bound->pwf_tight.
*
* If bernstein_recurse is set to ISL_BERNSTEIN_FACTORS, we check if
* the polytope can be factorized and apply bernstein expansion recursively
* on the factors.
* If bernstein_recurse is set to ISL_BERNSTEIN_INTERVALS, we apply
* bernstein expansion recursively on each dimension.
* Otherwise, we apply bernstein expansion on the entire polytope.
*/
isl_stat isl_qpolynomial_bound_on_domain_bernstein(
__isl_take isl_basic_set *bset, __isl_take isl_qpolynomial *poly,
struct isl_bound *bound)
{
struct bernstein_data data;
isl_pw_qpolynomial_fold *pwf;
isl_size nvar;
isl_bool tight = isl_bool_false;
isl_bool *tp = bound->check_tight ? &tight : NULL;
nvar = isl_basic_set_dim(bset, isl_dim_set);
if (nvar < 0 || !poly)
goto error;
data.type = bound->type;
data.check_tight = bound->check_tight;
if (bset->ctx->opt->bernstein_recurse & ISL_BERNSTEIN_FACTORS)
pwf = bernstein_coefficients_factors(bset, poly, &data, tp);
else if (nvar > 1 &&
(bset->ctx->opt->bernstein_recurse & ISL_BERNSTEIN_INTERVALS))
pwf = bernstein_coefficients_full_recursive(bset, poly, &data, tp);
else
pwf = bernstein_coefficients_base(bset, poly, &data, tp);
if (tight)
return isl_bound_add_tight(bound, pwf);
else
return isl_bound_add(bound, pwf);
error:
isl_basic_set_free(bset);
isl_qpolynomial_free(poly);
return isl_stat_error;
}
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