nexmon – Rev 1
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/*
* Copyright 2008-2009 Katholieke Universiteit Leuven
*
* Use of this software is governed by the GNU LGPLv2.1 license
*
* Written by Sven Verdoolaege, K.U.Leuven, Departement
* Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
*/
#include <assert.h>
#include <isl_map_private.h>
#include <isl/seq.h>
#include "isl_tab.h"
struct tab_lp {
struct isl_ctx *ctx;
struct isl_vec *row;
struct isl_tab *tab;
struct isl_tab_undo **stack;
isl_int *obj;
isl_int opt;
isl_int opt_denom;
isl_int tmp;
isl_int tmp2;
int neq;
unsigned dim;
/* number of constraints in initial product tableau */
int con_offset;
/* objective function has fixed or no integer value */
int is_fixed;
};
static struct tab_lp *init_lp(struct isl_tab *tab);
static void set_lp_obj(struct tab_lp *lp, isl_int *row, int dim);
static int solve_lp(struct tab_lp *lp);
static void get_obj_val(struct tab_lp* lp, mpq_t *F);
static void delete_lp(struct tab_lp *lp);
static int add_lp_row(struct tab_lp *lp, isl_int *row, int dim);
static void get_alpha(struct tab_lp* lp, int row, mpq_t *alpha);
static int del_lp_row(struct tab_lp *lp) WARN_UNUSED;
static int cut_lp_to_hyperplane(struct tab_lp *lp, isl_int *row);
#define GBR_LP struct tab_lp
#define GBR_type mpq_t
#define GBR_init(v) mpq_init(v)
#define GBR_clear(v) mpq_clear(v)
#define GBR_set(a,b) mpq_set(a,b)
#define GBR_set_ui(a,b) mpq_set_ui(a,b,1)
#define GBR_mul(a,b,c) mpq_mul(a,b,c)
#define GBR_lt(a,b) (mpq_cmp(a,b) < 0)
#define GBR_is_zero(a) (mpq_sgn(a) == 0)
#define GBR_floor(a,b) mpz_fdiv_q(a,mpq_numref(b),mpq_denref(b))
#define GBR_ceil(a,b) mpz_cdiv_q(a,mpq_numref(b),mpq_denref(b))
#define GBR_lp_init(P) init_lp(P)
#define GBR_lp_set_obj(lp, obj, dim) set_lp_obj(lp, obj, dim)
#define GBR_lp_solve(lp) solve_lp(lp)
#define GBR_lp_get_obj_val(lp, F) get_obj_val(lp, F)
#define GBR_lp_delete(lp) delete_lp(lp)
#define GBR_lp_next_row(lp) lp->neq
#define GBR_lp_add_row(lp, row, dim) add_lp_row(lp, row, dim)
#define GBR_lp_get_alpha(lp, row, alpha) get_alpha(lp, row, alpha)
#define GBR_lp_del_row(lp) del_lp_row(lp)
#define GBR_lp_is_fixed(lp) (lp)->is_fixed
#define GBR_lp_cut(lp, obj) cut_lp_to_hyperplane(lp, obj)
#include "basis_reduction_templ.c"
/* Set up a tableau for the Cartesian product of bset with itself.
* This could be optimized by first setting up a tableau for bset
* and then performing the Cartesian product on the tableau.
*/
static struct isl_tab *gbr_tab(struct isl_tab *tab, struct isl_vec *row)
{
unsigned dim;
struct isl_tab *prod;
if (!tab || !row)
return NULL;
dim = tab->n_var;
prod = isl_tab_product(tab, tab);
if (isl_tab_extend_cons(prod, 3 * dim + 1) < 0) {
isl_tab_free(prod);
return NULL;
}
return prod;
}
static struct tab_lp *init_lp(struct isl_tab *tab)
{
struct tab_lp *lp = NULL;
if (!tab)
return NULL;
lp = isl_calloc_type(tab->mat->ctx, struct tab_lp);
if (!lp)
return NULL;
isl_int_init(lp->opt);
isl_int_init(lp->opt_denom);
isl_int_init(lp->tmp);
isl_int_init(lp->tmp2);
lp->dim = tab->n_var;
lp->ctx = tab->mat->ctx;
isl_ctx_ref(lp->ctx);
lp->stack = isl_alloc_array(lp->ctx, struct isl_tab_undo *, lp->dim);
lp->row = isl_vec_alloc(lp->ctx, 1 + 2 * lp->dim);
if (!lp->row)
goto error;
lp->tab = gbr_tab(tab, lp->row);
if (!lp->tab)
goto error;
lp->con_offset = lp->tab->n_con;
lp->obj = NULL;
lp->neq = 0;
return lp;
error:
delete_lp(lp);
return NULL;
}
static void set_lp_obj(struct tab_lp *lp, isl_int *row, int dim)
{
lp->obj = row;
}
static int solve_lp(struct tab_lp *lp)
{
enum isl_lp_result res;
unsigned flags = 0;
lp->is_fixed = 0;
isl_int_set_si(lp->row->el[0], 0);
isl_seq_cpy(lp->row->el + 1, lp->obj, lp->dim);
isl_seq_neg(lp->row->el + 1 + lp->dim, lp->obj, lp->dim);
if (lp->neq)
flags = ISL_TAB_SAVE_DUAL;
res = isl_tab_min(lp->tab, lp->row->el, lp->ctx->one,
&lp->opt, &lp->opt_denom, flags);
isl_int_mul_ui(lp->opt_denom, lp->opt_denom, 2);
if (isl_int_abs_lt(lp->opt, lp->opt_denom)) {
struct isl_vec *sample = isl_tab_get_sample_value(lp->tab);
if (!sample)
return -1;
isl_seq_inner_product(lp->obj, sample->el + 1, lp->dim, &lp->tmp);
isl_seq_inner_product(lp->obj, sample->el + 1 + lp->dim, lp->dim, &lp->tmp2);
isl_int_cdiv_q(lp->tmp, lp->tmp, sample->el[0]);
isl_int_fdiv_q(lp->tmp2, lp->tmp2, sample->el[0]);
if (isl_int_ge(lp->tmp, lp->tmp2))
lp->is_fixed = 1;
isl_vec_free(sample);
}
isl_int_divexact_ui(lp->opt_denom, lp->opt_denom, 2);
if (res != isl_lp_ok)
return -1;
return 0;
}
/* The current objective function has a fixed (or no) integer value.
* Cut the tableau to the hyperplane that fixes this value in
* both halves of the tableau.
* Return 1 if the resulting tableau is empty.
*/
static int cut_lp_to_hyperplane(struct tab_lp *lp, isl_int *row)
{
enum isl_lp_result res;
isl_int_set_si(lp->row->el[0], 0);
isl_seq_cpy(lp->row->el + 1, row, lp->dim);
isl_seq_clr(lp->row->el + 1 + lp->dim, lp->dim);
res = isl_tab_min(lp->tab, lp->row->el, lp->ctx->one,
&lp->tmp, NULL, 0);
if (res != isl_lp_ok)
return -1;
isl_int_neg(lp->row->el[0], lp->tmp);
if (isl_tab_add_eq(lp->tab, lp->row->el) < 0)
return -1;
isl_seq_cpy(lp->row->el + 1 + lp->dim, row, lp->dim);
isl_seq_clr(lp->row->el + 1, lp->dim);
if (isl_tab_add_eq(lp->tab, lp->row->el) < 0)
return -1;
lp->con_offset += 2;
return lp->tab->empty;
}
static void get_obj_val(struct tab_lp* lp, mpq_t *F)
{
isl_int_neg(mpq_numref(*F), lp->opt);
isl_int_set(mpq_denref(*F), lp->opt_denom);
}
static void delete_lp(struct tab_lp *lp)
{
if (!lp)
return;
isl_int_clear(lp->opt);
isl_int_clear(lp->opt_denom);
isl_int_clear(lp->tmp);
isl_int_clear(lp->tmp2);
isl_vec_free(lp->row);
free(lp->stack);
isl_tab_free(lp->tab);
isl_ctx_deref(lp->ctx);
free(lp);
}
static int add_lp_row(struct tab_lp *lp, isl_int *row, int dim)
{
lp->stack[lp->neq] = isl_tab_snap(lp->tab);
isl_int_set_si(lp->row->el[0], 0);
isl_seq_cpy(lp->row->el + 1, row, lp->dim);
isl_seq_neg(lp->row->el + 1 + lp->dim, row, lp->dim);
if (isl_tab_add_valid_eq(lp->tab, lp->row->el) < 0)
return -1;
return lp->neq++;
}
static void get_alpha(struct tab_lp* lp, int row, mpq_t *alpha)
{
row += lp->con_offset;
isl_int_neg(mpq_numref(*alpha), lp->tab->dual->el[1 + row]);
isl_int_set(mpq_denref(*alpha), lp->tab->dual->el[0]);
}
static int del_lp_row(struct tab_lp *lp)
{
lp->neq--;
return isl_tab_rollback(lp->tab, lp->stack[lp->neq]);
}