isl backend: support existentially quantified variables in domains

[cloog.git] / source / isl / constraints.c

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <cloog/isl/cloog.h>
#include <cloog/isl/backend.h>
#include <isl_set.h>


#define ALLOC(type) (type*)malloc(sizeof(type))
#define ALLOCN(type,n) (type*)malloc((n)*sizeof(type))


/******************************************************************************
 *                             Memory leaks hunting                           *
 ******************************************************************************/


/**
 * These global variables are devoted to memory leaks hunting in the PolyLib
 * backend.  The isl backend has its own memory leak detection facilities.
 */
int cloog_matrix_allocated = 0;
int cloog_matrix_freed = 0;
int cloog_matrix_max = 0;


void cloog_constraint_set_free(CloogConstraintSet *constraints)
{
        isl_basic_set_free(constraints);
}


int cloog_constraint_set_contains_level(CloogConstraintSet *constraints,
                        int level, int nb_parameters)
{
        return isl_basic_set_n_dim(constraints) >= level;
}

struct cloog_isl_dim {
        enum isl_dim_type type;
        int               pos;
};

static struct cloog_isl_dim set_cloog_dim_to_isl_dim(
                                        CloogConstraintSet *bset, int pos)
{
        enum isl_dim_type types[] = { isl_dim_set, isl_dim_div, isl_dim_param };
        int i;
        struct cloog_isl_dim ci_dim;

        for (i = 0; i < 3; ++i) {
                unsigned dim = isl_basic_set_dim(bset, types[i]);
                if (pos < dim) {
                        ci_dim.type = types[i];
                        ci_dim.pos = pos;
                        return ci_dim;
                }
                pos -= dim;
        }
        assert(0);
}

/* Check if the variable at position level is defined by an
 * equality.  If so, return the row number.  Otherwise, return -1.
 */
CloogConstraint cloog_constraint_set_defining_equality(
        CloogConstraintSet *bset, int level)
{
        struct isl_constraint *c;
        struct cloog_isl_dim dim;

        dim = set_cloog_dim_to_isl_dim(bset, level - 1);
        if (isl_basic_set_has_defining_equality(bset, dim.type, dim.pos, &c))
                return c;
        else
                return NULL;
}


/* Check if the variable (e) at position level is defined by a
 * pair of inequalities
 *               <a, i> + -m e +  <b, p> + k1 >= 0
 *              <-a, i> +  m e + <-b, p> + k2 >= 0
 * with 0 <= k1 + k2 < m
 * If so return the row number of the upper bound and set *lower
 * to the row number of the lower bound.  If not, return -1.
 *
 * If the variable at position level occurs in any other constraint,
 * then we currently return -1.  The modulo guard that we would generate
 * would still be correct, but we would also need to generate
 * guards corresponding to the other constraints, and this has not
 * been implemented yet.
 */
CloogConstraint cloog_constraint_set_defining_inequalities(
        CloogConstraintSet *bset,
        int level, CloogConstraint *lower, int nb_par)
{
        struct isl_constraint *upper;
        struct isl_constraint *c;
        struct cloog_isl_dim dim;

        dim = set_cloog_dim_to_isl_dim(bset, level - 1);
        if (!isl_basic_set_has_defining_inequalities(bset, dim.type, dim.pos,
                                                                lower, &upper))
                return cloog_constraint_invalid();
        for (c = isl_basic_set_first_constraint(isl_basic_set_copy(bset)); c;
             c = isl_constraint_next(c)) {
                if (isl_constraint_is_equal(c, *lower))
                        continue;
                if (isl_constraint_is_equal(c, upper))
                        continue;
                if (cloog_constraint_involves(c, level-1)) {
                        isl_constraint_free(*lower);
                        isl_constraint_free(upper);
                        *lower = NULL;
                        isl_constraint_free(c);
                        return NULL;
                }
        }
        return upper;
}

int cloog_constraint_set_total_dimension(CloogConstraintSet *constraints)
{
        return isl_basic_set_total_dim(constraints);
}

int cloog_constraint_set_n_iterators(CloogConstraintSet *constraints, int n_par)
{
        return isl_basic_set_n_dim(constraints);
}


/******************************************************************************
 *                        Equalities spreading functions                      *
 ******************************************************************************/


/* Equalities are stored inside a CloogMatrix data structure called "equal".
 * This matrix has (nb_scattering + nb_iterators + 1) rows (i.e. total
 * dimensions + 1, the "+ 1" is because a statement can be included inside an
 * external loop without iteration domain), and (nb_scattering + nb_iterators +
 * nb_parameters + 2) columns (all unknowns plus the scalar plus the equality
 * type). The ith row corresponds to the equality "= 0" for the ith dimension
 * iterator. The first column gives the equality type (0: no equality, then
 * EQTYPE_* -see pprint.h-). At each recursion of pprint, if an equality for
 * the current level is found, the corresponding row is updated. Then the
 * equality if it exists is used to simplify expressions (e.g. if we have 
 * "i+1" while we know that "i=2", we simplify it in "3"). At the end of
 * the pprint call, the corresponding row is reset to zero.
 */

CloogEqualities *cloog_equal_alloc(int n, int nb_levels, int nb_parameters)
{
        int i;
        CloogEqualities *equal = ALLOC(CloogEqualities);

        equal->total_dim = nb_levels - 1 + nb_parameters;
        equal->n = n;
        equal->constraints = ALLOCN(struct isl_basic_set *, n);
        equal->types = ALLOCN(int, n);
        for (i = 0; i < n; ++i) {
                equal->constraints[i] = NULL;
                equal->types[i] = EQTYPE_NONE;
        }
        return equal;
}

int cloog_equal_total_dimension(CloogEqualities *equal)
{
        return equal->total_dim;
}

void cloog_equal_free(CloogEqualities *equal)
{
        int i;

        for (i = 0; i < equal->n; ++i)
                isl_basic_set_free(equal->constraints[i]);
        free(equal->constraints);
        free(equal->types);
        free(equal);
}

int cloog_equal_count(CloogEqualities *equal)
{
        return equal->n;
}


/**
 * cloog_constraint_equal_type function :
 * This function returns the type of the equality in the constraint (line) of
 * (constraints) for the element (level). An equality is 'constant' iff all
 * other
 * factors are null except the constant one. It is a 'pure item' iff one and
 * only one factor is non null and is 1 or -1. Otherwise it is an 'affine
 * expression'.
 * For instance:
 *   i = -13 is constant, i = j, j = -M are pure items,
 *   j = 2*M, i = j+1 are affine expressions.
 * When the equality comes from a 'one time loop', (line) is ONE_TIME_LOOP.
 * This case require a specific treatment since we have to study all the
 * constraints.
 * - constraints is the matrix of constraints,
 * - level is the column number in equal of the element which is 'equal to',
 * - line is the line number in equal of the constraint we want to study;
 *   if it is -1, all lines must be studied.
 */
static int cloog_constraint_equal_type(CloogConstraint constraint, int level)
{ 
        int i;
        isl_int c;
        int type = EQTYPE_NONE;
    
        isl_int_init(c);
        isl_constraint_get_constant(constraint, &c);
        if (!isl_int_is_zero(c))
                type = EQTYPE_CONSTANT;
        for (i = 0; i < isl_constraint_dim(constraint, isl_dim_param); ++i) {
                isl_constraint_get_coefficient(constraint, isl_dim_param, i, &c);
                if (isl_int_is_zero(c))
                        continue;
                if ((!isl_int_is_one(c) && !isl_int_is_negone(c)) ||
                    type != EQTYPE_NONE) {
                        type = EQTYPE_EXAFFINE;
                        break;
                }
                type = EQTYPE_PUREITEM;
        }
        for (i = 0; i < isl_constraint_dim(constraint, isl_dim_set); ++i) {
                if (i == level - 1)
                        continue;
                isl_constraint_get_coefficient(constraint, isl_dim_set, i, &c);
                if (isl_int_is_zero(c))
                        continue;
                if ((!isl_int_is_one(c) && !isl_int_is_negone(c)) ||
                    type != EQTYPE_NONE) {
                        type = EQTYPE_EXAFFINE;
                        break;
                }
                type = EQTYPE_PUREITEM;
        }
        for (i = 0; i < isl_constraint_dim(constraint, isl_dim_div); ++i) {
                isl_constraint_get_coefficient(constraint, isl_dim_div, i, &c);
                if (isl_int_is_zero(c))
                        continue;
                if ((!isl_int_is_one(c) && !isl_int_is_negone(c)) ||
                    type != EQTYPE_NONE) {
                        type = EQTYPE_EXAFFINE;
                        break;
                }
                type = EQTYPE_PUREITEM;
        }
        isl_int_clear(c);

        if (type == EQTYPE_NONE)
                type = EQTYPE_CONSTANT;

        return type;
}


int cloog_equal_type(CloogEqualities *equal, int level)
{
        return equal->types[level-1];
}


/**
 * cloog_equal_add function:
 * This function updates the row (level-1) of the equality matrix (equal) with
 * the row that corresponds to the row (line) of the matrix (matrix).
 * - equal is the matrix of equalities,
 * - matrix is the matrix of constraints,
 * - level is the column number in matrix of the element which is 'equal to',
 * - line is the line number in matrix of the constraint we want to study,
 * - the infos structure gives the user all options on code printing and more.
 **
 * line is set to and invalid constraint for equalities that CLooG itself has
 * discovered because the lower and upper bound of a loop happened to be equal.
 * This situation shouldn't happen in the isl port since isl should
 * have found the equality itself.
 */
void cloog_equal_add(CloogEqualities *equal, CloogConstraintSet *matrix,
                        int level, CloogConstraint line, int nb_par)
{ 
        struct isl_basic_set *bset;
        unsigned nparam;
        assert(cloog_constraint_is_valid(line));
  
        equal->types[level-1] = cloog_constraint_equal_type(line, level);
        bset = isl_basic_set_from_constraint(isl_constraint_copy(line));
        nparam = isl_basic_set_n_param(bset);
        bset = isl_basic_set_extend(bset, nparam,
                                    equal->total_dim - nparam, 0, 0, 0);
        bset = isl_basic_set_finalize(bset);
        equal->constraints[level-1] = bset;
}


/**
 * cloog_equal_del function :
 * This function reset the equality corresponding to the iterator (level)
 * in the equality matrix (equal).
 * - July 2nd 2002: first version. 
 */
void cloog_equal_del(CloogEqualities *equal, int level)
{ 
        equal->types[level-1] = EQTYPE_NONE;
        isl_basic_set_free(equal->constraints[level-1]);
        equal->constraints[level-1] = NULL;
}



/******************************************************************************
 *                            Processing functions                            *
 ******************************************************************************/

/**
 * Function cloog_constraint_set_normalize:
 * This function will modify the constraint system in such a way that when
 * there is an equality depending on the element at level 'level', there are
 * no more (in)equalities depending on this element.
 *
 * The simplified form of isl automatically satisfies this condition.
 */
void cloog_constraint_set_normalize(CloogConstraintSet *matrix, int level)
{
}



/**
 * cloog_constraint_set_copy function:
 * this functions builds and returns a "hard copy" (not a pointer copy) of a
 * CloogConstraintSet data structure.
 */
CloogConstraintSet *cloog_constraint_set_copy(CloogConstraintSet *bset)
{
        return isl_basic_set_dup(bset);
}


/**
 * cloog_constraint_set_simplify function:
 * this function simplify all constraints inside the matrix "matrix" thanks to
 * an equality matrix "equal" that gives for some elements of the affine
 * constraint an equality with other elements, preferably constants.
 * For instance, if a row of the matrix contains i+j+3>=0 and the equality
 * matrix gives i=n and j=2, the constraint is simplified to n+3>=0. The
 * simplified constraints are returned back inside a new simplified matrix.
 * - matrix is the set of constraints to simplify,
 * - equal is the matrix of equalities,
 * - level is a level we don't want to simplify (-1 if none),
 * - nb_par is the number of parameters of the program.
 **
 * isl should have performed these simplifications already in isl_set_gist.
 */
CloogConstraintSet *cloog_constraint_set_simplify(CloogConstraintSet *matrix,
        CloogEqualities *equal, int level, int nb_par)
{
        return cloog_constraint_set_copy(matrix);
}


static struct cloog_isl_dim constraint_cloog_dim_to_isl_dim(
                                        CloogConstraint constraint, int pos)
{
        enum isl_dim_type types[] = { isl_dim_set, isl_dim_div, isl_dim_param };
        int i;
        struct cloog_isl_dim ci_dim;

        for (i = 0; i < 3; ++i) {
                unsigned dim = isl_constraint_dim(constraint, types[i]);
                if (pos < dim) {
                        ci_dim.type = types[i];
                        ci_dim.pos = pos;
                        return ci_dim;
                }
                pos -= dim;
        }
        assert(0);
}

static struct clast_expr *div_expr(CloogConstraint constraint, int pos,
                                        CloogNames *names)
{
        int i, nb_elts;
        unsigned dim = cloog_constraint_total_dimension(constraint);
        cloog_int_t c;
        struct clast_reduction *r;
        struct clast_expr *e = NULL;
        struct isl_div *div;

        div = isl_constraint_div(constraint, pos);

        cloog_int_init(c);
        for (i = 0, nb_elts = 0; i < dim; ++i) {
                struct cloog_isl_dim dim;

                dim = constraint_cloog_dim_to_isl_dim(constraint, i);
                isl_div_get_coefficient(div, dim.type, dim.pos, &c);
                if (!cloog_int_is_zero(c))
                        ++nb_elts;
        }
        isl_div_get_constant(div, &c);
        if (!cloog_int_is_zero(c))
                ++nb_elts;

        r = new_clast_reduction(clast_red_sum, nb_elts);
        for (i = 0, nb_elts = 0; i < dim; ++i) {
                struct clast_expr *v;
                struct cloog_isl_dim dim;

                dim = constraint_cloog_dim_to_isl_dim(constraint, i);
                isl_div_get_coefficient(div, dim.type, dim.pos, &c);
                if (cloog_int_is_zero(c))
                        continue;

                v = cloog_constraint_variable_expr(constraint, 1 + i, names);

                r->elts[nb_elts++] = &new_clast_term(c, v)->expr;
        }
        isl_div_get_constant(div, &c);
        if (!cloog_int_is_zero(c))
                r->elts[nb_elts++] = &new_clast_term(c, NULL)->expr;

        isl_div_get_denominator(div, &c);
        e = &new_clast_binary(clast_bin_fdiv, &r->expr, c)->expr;

        cloog_int_clear(c);

        return e;
}

/**
 * Return clast_expr corresponding to the variable "level" (1 based) in
 * the given constraint.
 */
struct clast_expr *cloog_constraint_variable_expr(CloogConstraint constraint,
        int level, CloogNames *names)
{
        struct cloog_isl_dim dim;
        const char *name;

        assert(constraint);

        dim = constraint_cloog_dim_to_isl_dim(constraint, level - 1);
        if (dim.type == isl_dim_div)
                return div_expr(constraint, dim.pos, names);

        if (dim.type == isl_dim_set)
                name = cloog_names_name_at_level(names, level);
        else
                name = names->parameters[dim.pos];

        return &new_clast_name(name)->expr;
}


/**
 * Return true if constraint c involves variable v (zero-based).
 */
int cloog_constraint_involves(CloogConstraint constraint, int v)
{
        isl_int c;
        int res;

        isl_int_init(c);
        cloog_constraint_coefficient_get(constraint, v, &c);
        res = !isl_int_is_zero(c);
        isl_int_clear(c);
        return res;
}

int cloog_constraint_is_lower_bound(CloogConstraint constraint, int v)
{
        isl_int c;
        int res;

        isl_int_init(c);
        cloog_constraint_coefficient_get(constraint, v, &c);
        res = isl_int_is_pos(c);
        isl_int_clear(c);
        return res;
}

int cloog_constraint_is_upper_bound(CloogConstraint constraint, int v)
{
        isl_int c;
        int res;

        isl_int_init(c);
        cloog_constraint_coefficient_get(constraint, v, &c);
        res = isl_int_is_neg(c);
        isl_int_clear(c);
        return res;
}

int cloog_constraint_is_equality(CloogConstraint constraint)
{
        return isl_constraint_is_equality(constraint);
}

void cloog_constraint_clear(CloogConstraint constraint)
{
        isl_constraint_clear(constraint);
}

void cloog_constraint_coefficient_get(CloogConstraint constraint,
                        int var, cloog_int_t *val)
{
        struct cloog_isl_dim dim;

        if (!constraint)
                return;

        dim = constraint_cloog_dim_to_isl_dim(constraint, var);
        isl_constraint_get_coefficient(constraint, dim.type, dim.pos, val);
}

void cloog_constraint_coefficient_set(CloogConstraint constraint,
                        int var, cloog_int_t val)
{
        struct cloog_isl_dim dim;

        assert(constraint);

        dim = constraint_cloog_dim_to_isl_dim(constraint, var);
        isl_constraint_set_coefficient(constraint, dim.type, dim.pos, val);
}

void cloog_constraint_constant_get(CloogConstraint constraint, cloog_int_t *val)
{
        isl_constraint_get_constant(constraint, val);
}

/**
 * Copy the coefficient of constraint c into dst in PolyLib order,
 * i.e., first the coefficients of the variables, then the coefficients
 * of the parameters and finally the constant.
 */
void cloog_constraint_copy_coefficients(CloogConstraint constraint,
                                        cloog_int_t *dst)
{
        int i;
        unsigned dim;

        dim = isl_constraint_dim(constraint, isl_dim_all);

        for (i = 0; i < dim; ++i)
                cloog_constraint_coefficient_get(constraint, i, dst+i);
        cloog_constraint_constant_get(constraint, dst+dim);
}

CloogConstraint cloog_constraint_invalid(void)
{
        return NULL;
}

int cloog_constraint_is_valid(CloogConstraint constraint)
{
        return constraint != NULL;
}

int cloog_constraint_total_dimension(CloogConstraint constraint)
{
        return isl_constraint_dim(constraint, isl_dim_all);
}

CloogConstraint cloog_constraint_first(CloogConstraintSet *constraints)
{
        return isl_basic_set_first_constraint(isl_basic_set_copy(constraints));
}

CloogConstraint cloog_constraint_next(CloogConstraint constraint)
{
        return isl_constraint_next(constraint);
}

CloogConstraint cloog_constraint_copy(CloogConstraint constraint)
{
        return isl_constraint_copy(constraint);
}

void cloog_constraint_release(CloogConstraint constraint)
{
        isl_constraint_free(constraint);
}

CloogConstraint cloog_equal_constraint(CloogEqualities *equal, int j)
{
        return isl_basic_set_first_constraint(
                        isl_basic_set_copy(equal->constraints[j]));
}