Introduction

isl is a thread-safe C library for manipulating sets and relations of integer points bounded by affine constraints. The descriptions of the sets and relations may involve both parameters and existentially quantified variables. All computations are performed in exact integer arithmetic using GMP. The isl library offers functionality that is similar to that offered by the Omega and Omega+ libraries, but the underlying algorithms are in most cases completely different.

The library is by no means complete and some fairly basic functionality is still missing. Still, even in its current form, the library has been successfully used as a backend polyhedral library for the polyhedral scanner CLooG and as part of an equivalence checker of static affine programs. For bug reports, feature requests and questions, visit the the discussion group at http://groups.google.com/group/isl-development.

Backward Incompatible Changes

Changes since isl-0.02

Changes since isl-0.03

Changes since isl-0.04

Changes since isl-0.05

Changes since isl-0.06

Changes since isl-0.07

Changes since isl-0.09

Changes since isl-0.10

Changes since isl-0.12


License

isl is released under the MIT license.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Note that isl currently requires GMP, which is released under the GNU Lesser General Public License (LGPL). This means that code linked against isl is also linked against LGPL code.


Installation

The source of isl can be obtained either as a tarball or from the git repository. Both are available from http://freshmeat.net/projects/isl/. The installation process depends on how you obtained the source.

Installation from the git repository

  1. Clone or update the repository

    The first time the source is obtained, you need to clone the repository.

            git clone git://repo.or.cz/isl.git

    To obtain updates, you need to pull in the latest changes

            git pull
  2. Generate configure
            ./autogen.sh

After performing the above steps, continue with the Common installation instructions.

Common installation instructions

  1. Obtain GMP

    Building isl requires GMP, including its headers files. Your distribution may not provide these header files by default and you may need to install a package called gmp-devel or something similar. Alternatively, GMP can be built from source, available from http://gmplib.org/.

  2. Configure

    isl uses the standard autoconf configure script. To run it, just type

            ./configure

    optionally followed by some configure options. A complete list of options can be obtained by running

            ./configure --help

    Below we discuss some of the more common options.

    --prefix

    Installation prefix for isl

    --with-gmp-prefix

    Installation prefix for GMP (architecture-independent files).

    --with-gmp-exec-prefix

    Installation prefix for GMP (architecture-dependent files).

  3. Compile
            make
  4. Install (optional)
            make install


Integer Set Library

Initialization

All manipulations of integer sets and relations occur within the context of an isl_ctx. A given isl_ctx can only be used within a single thread. All arguments of a function are required to have been allocated within the same context. There are currently no functions available for moving an object from one isl_ctx to another isl_ctx. This means that there is currently no way of safely moving an object from one thread to another, unless the whole isl_ctx is moved.

An isl_ctx can be allocated using isl_ctx_alloc and freed using isl_ctx_free. All objects allocated within an isl_ctx should be freed before the isl_ctx itself is freed.

        isl_ctx *isl_ctx_alloc();
        void isl_ctx_free(isl_ctx *ctx);

Values

An isl_val represents an integer value, a rational value or one of three special values, infinity, negative infinity and NaN. Some predefined values can be created using the following functions.

        #include <isl/val.h>
        __isl_give isl_val *isl_val_zero(isl_ctx *ctx);
        __isl_give isl_val *isl_val_one(isl_ctx *ctx);
        __isl_give isl_val *isl_val_nan(isl_ctx *ctx);
        __isl_give isl_val *isl_val_infty(isl_ctx *ctx);
        __isl_give isl_val *isl_val_neginfty(isl_ctx *ctx);

Specific integer values can be created using the following functions.

        #include <isl/val.h>
        __isl_give isl_val *isl_val_int_from_si(isl_ctx *ctx,
                long i);
        __isl_give isl_val *isl_val_int_from_ui(isl_ctx *ctx,
                unsigned long u);
        __isl_give isl_val *isl_val_int_from_chunks(isl_ctx *ctx,
                size_t n, size_t size, const void *chunks);

The function isl_val_int_from_chunks constructs an isl_val from the n digits, each consisting of size bytes, stored at chunks. The least significant digit is assumed to be stored first.

Value objects can be copied and freed using the following functions.

        #include <isl/val.h>
        __isl_give isl_val *isl_val_copy(__isl_keep isl_val *v);
        void *isl_val_free(__isl_take isl_val *v);

They can be inspected using the following functions.

        #include <isl/val.h>
        isl_ctx *isl_val_get_ctx(__isl_keep isl_val *val);
        long isl_val_get_num_si(__isl_keep isl_val *v);
        long isl_val_get_den_si(__isl_keep isl_val *v);
        double isl_val_get_d(__isl_keep isl_val *v);
        size_t isl_val_n_abs_num_chunks(__isl_keep isl_val *v,
                size_t size);
        int isl_val_get_abs_num_chunks(__isl_keep isl_val *v,
                size_t size, void *chunks);

isl_val_n_abs_num_chunks returns the number of digits of size bytes needed to store the absolute value of the numerator of v. isl_val_get_abs_num_chunks stores these digits at chunks, which is assumed to have been preallocated by the caller. The least significant digit is stored first. Note that isl_val_get_num_si, isl_val_get_den_si, isl_val_get_d, isl_val_n_abs_num_chunks and isl_val_get_abs_num_chunks can only be applied to rational values.

An isl_val can be modified using the following function.

        #include <isl/val.h>
        __isl_give isl_val *isl_val_set_si(__isl_take isl_val *v,
                long i);

The following unary properties are defined on isl_vals.

        #include <isl/val.h>
        int isl_val_sgn(__isl_keep isl_val *v);
        int isl_val_is_zero(__isl_keep isl_val *v);
        int isl_val_is_one(__isl_keep isl_val *v);
        int isl_val_is_negone(__isl_keep isl_val *v);
        int isl_val_is_nonneg(__isl_keep isl_val *v);
        int isl_val_is_nonpos(__isl_keep isl_val *v);
        int isl_val_is_pos(__isl_keep isl_val *v);
        int isl_val_is_neg(__isl_keep isl_val *v);
        int isl_val_is_int(__isl_keep isl_val *v);
        int isl_val_is_rat(__isl_keep isl_val *v);
        int isl_val_is_nan(__isl_keep isl_val *v);
        int isl_val_is_infty(__isl_keep isl_val *v);
        int isl_val_is_neginfty(__isl_keep isl_val *v);

Note that the sign of NaN is undefined.

The following binary properties are defined on pairs of isl_vals.

        #include <isl/val.h>
        int isl_val_lt(__isl_keep isl_val *v1,
                __isl_keep isl_val *v2);
        int isl_val_le(__isl_keep isl_val *v1,
                __isl_keep isl_val *v2);
        int isl_val_gt(__isl_keep isl_val *v1,
                __isl_keep isl_val *v2);
        int isl_val_ge(__isl_keep isl_val *v1,
                __isl_keep isl_val *v2);
        int isl_val_eq(__isl_keep isl_val *v1,
                __isl_keep isl_val *v2);
        int isl_val_ne(__isl_keep isl_val *v1,
                __isl_keep isl_val *v2);

For integer isl_vals we additionally have the following binary property.

        #include <isl/val.h>
        int isl_val_is_divisible_by(__isl_keep isl_val *v1,
                __isl_keep isl_val *v2);

An isl_val can also be compared to an integer using the following function. The result is undefined for NaN.

        #include <isl/val.h>
        int isl_val_cmp_si(__isl_keep isl_val *v, long i);

The following unary operations are available on isl_vals.

        #include <isl/val.h>
        __isl_give isl_val *isl_val_abs(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_neg(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_floor(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_ceil(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_trunc(__isl_take isl_val *v);

The following binary operations are available on isl_vals.

        #include <isl/val.h>
        __isl_give isl_val *isl_val_abs(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_neg(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_floor(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_ceil(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_trunc(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_2exp(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_min(__isl_take isl_val *v1,
                __isl_take isl_val *v2);
        __isl_give isl_val *isl_val_max(__isl_take isl_val *v1,
                __isl_take isl_val *v2);
        __isl_give isl_val *isl_val_add(__isl_take isl_val *v1,
                __isl_take isl_val *v2);
        __isl_give isl_val *isl_val_add_ui(__isl_take isl_val *v1,
                unsigned long v2);
        __isl_give isl_val *isl_val_sub(__isl_take isl_val *v1,
                __isl_take isl_val *v2);
        __isl_give isl_val *isl_val_sub_ui(__isl_take isl_val *v1,
                unsigned long v2);
        __isl_give isl_val *isl_val_mul(__isl_take isl_val *v1,
                __isl_take isl_val *v2);
        __isl_give isl_val *isl_val_mul_ui(__isl_take isl_val *v1,
                unsigned long v2);
        __isl_give isl_val *isl_val_div(__isl_take isl_val *v1,
                __isl_take isl_val *v2);

On integer values, we additionally have the following operations.

        #include <isl/val.h>
        __isl_give isl_val *isl_val_2exp(__isl_take isl_val *v);
        __isl_give isl_val *isl_val_mod(__isl_take isl_val *v1,
                __isl_take isl_val *v2);
        __isl_give isl_val *isl_val_gcd(__isl_take isl_val *v1,
                __isl_take isl_val *v2);
        __isl_give isl_val *isl_val_gcdext(__isl_take isl_val *v1,
                __isl_take isl_val *v2, __isl_give isl_val **x,
                __isl_give isl_val **y);

The function isl_val_gcdext returns the greatest common divisor g of v1 and v2 as well as two integers *x and *y such that *x * v1 + *y * v2 = g.

A value can be read from input using

        #include <isl/val.h>
        __isl_give isl_val *isl_val_read_from_str(isl_ctx *ctx,
                const char *str);

A value can be printed using

        #include <isl/val.h>
        __isl_give isl_printer *isl_printer_print_val(
                __isl_take isl_printer *p, __isl_keep isl_val *v);

GMP specific functions

These functions are only available if isl has been compiled with GMP support.

Specific integer and rational values can be created from GMP values using the following functions.

        #include <isl/val_gmp.h>
        __isl_give isl_val *isl_val_int_from_gmp(isl_ctx *ctx,
                mpz_t z);
        __isl_give isl_val *isl_val_from_gmp(isl_ctx *ctx,
                const mpz_t n, const mpz_t d);

The numerator and denominator of a rational value can be extracted as GMP values using the following functions.

        #include <isl/val_gmp.h>
        int isl_val_get_num_gmp(__isl_keep isl_val *v, mpz_t z);
        int isl_val_get_den_gmp(__isl_keep isl_val *v, mpz_t z);

Sets and Relations

isl uses six types of objects for representing sets and relations, isl_basic_set, isl_basic_map, isl_set, isl_map, isl_union_set and isl_union_map. isl_basic_set and isl_basic_map represent sets and relations that can be described as a conjunction of affine constraints, while isl_set and isl_map represent unions of isl_basic_sets and isl_basic_maps, respectively. However, all isl_basic_sets or isl_basic_maps in the union need to live in the same space. isl_union_sets and isl_union_maps represent unions of isl_sets or isl_maps in different spaces, where spaces are considered different if they have a different number of dimensions and/or different names (see Spaces). The difference between sets and relations (maps) is that sets have one set of variables, while relations have two sets of variables, input variables and output variables.

Memory Management

Since a high-level operation on sets and/or relations usually involves several substeps and since the user is usually not interested in the intermediate results, most functions that return a new object will also release all the objects passed as arguments. If the user still wants to use one or more of these arguments after the function call, she should pass along a copy of the object rather than the object itself. The user is then responsible for making sure that the original object gets used somewhere else or is explicitly freed.

The arguments and return values of all documented functions are annotated to make clear which arguments are released and which arguments are preserved. In particular, the following annotations are used

__isl_give

__isl_give means that a new object is returned. The user should make sure that the returned pointer is used exactly once as a value for an __isl_take argument. In between, it can be used as a value for as many __isl_keep arguments as the user likes. There is one exception, and that is the case where the pointer returned is NULL. Is this case, the user is free to use it as an __isl_take argument or not.

__isl_take

__isl_take means that the object the argument points to is taken over by the function and may no longer be used by the user as an argument to any other function. The pointer value must be one returned by a function returning an __isl_give pointer. If the user passes in a NULL value, then this will be treated as an error in the sense that the function will not perform its usual operation. However, it will still make sure that all the other __isl_take arguments are released.

__isl_keep

__isl_keep means that the function will only use the object temporarily. After the function has finished, the user can still use it as an argument to other functions. A NULL value will be treated in the same way as a NULL value for an __isl_take argument.

Error Handling

isl supports different ways to react in case a runtime error is triggered. Runtime errors arise, e.g., if a function such as isl_map_intersect is called with two maps that have incompatible spaces. There are three possible ways to react on error: to warn, to continue or to abort.

The default behavior is to warn. In this mode, isl prints a warning, stores the last error in the corresponding isl_ctx and the function in which the error was triggered returns NULL. An error does not corrupt internal state, such that isl can continue to be used. isl also provides functions to read the last error and to reset the memory that stores the last error. The last error is only stored for information purposes. Its presence does not change the behavior of isl. Hence, resetting an error is not required to continue to use isl, but only to observe new errors.

        #include <isl/ctx.h>
        enum isl_error isl_ctx_last_error(isl_ctx *ctx);
        void isl_ctx_reset_error(isl_ctx *ctx);

Another option is to continue on error. This is similar to warn on error mode, except that isl does not print any warning. This allows a program to implement its own error reporting.

The last option is to directly abort the execution of the program from within the isl library. This makes it obviously impossible to recover from an error, but it allows to directly spot the error location. By aborting on error, debuggers break at the location the error occurred and can provide a stack trace. Other tools that automatically provide stack traces on abort or that do not want to continue execution after an error was triggered may also prefer to abort on error.

The on error behavior of isl can be specified by calling isl_options_set_on_error or by setting the command line option --isl-on-error. Valid arguments for the function call are ISL_ON_ERROR_WARN, ISL_ON_ERROR_CONTINUE and ISL_ON_ERROR_ABORT. The choices for the command line option are warn, continue and abort. It is also possible to query the current error mode.

        #include <isl/options.h>
        int isl_options_set_on_error(isl_ctx *ctx, int val);
        int isl_options_get_on_error(isl_ctx *ctx);

Identifiers

Identifiers are used to identify both individual dimensions and tuples of dimensions. They consist of an optional name and an optional user pointer. The name and the user pointer cannot both be NULL, however. Identifiers with the same name but different pointer values are considered to be distinct. Similarly, identifiers with different names but the same pointer value are also considered to be distinct. Equal identifiers are represented using the same object. Pairs of identifiers can therefore be tested for equality using the == operator. Identifiers can be constructed, copied, freed, inspected and printed using the following functions.

        #include <isl/id.h>
        __isl_give isl_id *isl_id_alloc(isl_ctx *ctx,
                __isl_keep const char *name, void *user);
        __isl_give isl_id *isl_id_set_free_user(
                __isl_take isl_id *id,
                __isl_give void (*free_user)(void *user));
        __isl_give isl_id *isl_id_copy(isl_id *id);
        void *isl_id_free(__isl_take isl_id *id);
        isl_ctx *isl_id_get_ctx(__isl_keep isl_id *id);
        void *isl_id_get_user(__isl_keep isl_id *id);
        __isl_keep const char *isl_id_get_name(__isl_keep isl_id *id);
        __isl_give isl_printer *isl_printer_print_id(
                __isl_take isl_printer *p, __isl_keep isl_id *id);

The callback set by isl_id_set_free_user is called on the user pointer when the last reference to the isl_id is freed. Note that isl_id_get_name returns a pointer to some internal data structure, so the result can only be used while the corresponding isl_id is alive.

Spaces

Whenever a new set, relation or similiar object is created from scratch, the space in which it lives needs to be specified using an isl_space. Each space involves zero or more parameters and zero, one or two tuples of set or input/output dimensions. The parameters and dimensions are identified by an isl_dim_type and a position. The type isl_dim_param refers to parameters, the type isl_dim_set refers to set dimensions (for spaces with a single tuple of dimensions) and the types isl_dim_in and isl_dim_out refer to input and output dimensions (for spaces with two tuples of dimensions). Local spaces (see Local Spaces) also contain dimensions of type isl_dim_div. Note that parameters are only identified by their position within a given object. Across different objects, parameters are (usually) identified by their names or identifiers. Only unnamed parameters are identified by their positions across objects. The use of unnamed parameters is discouraged.

        #include <isl/space.h>
        __isl_give isl_space *isl_space_alloc(isl_ctx *ctx,
                unsigned nparam, unsigned n_in, unsigned n_out);
        __isl_give isl_space *isl_space_params_alloc(isl_ctx *ctx,
                unsigned nparam);
        __isl_give isl_space *isl_space_set_alloc(isl_ctx *ctx,
                unsigned nparam, unsigned dim);
        __isl_give isl_space *isl_space_copy(__isl_keep isl_space *space);
        void *isl_space_free(__isl_take isl_space *space);
        unsigned isl_space_dim(__isl_keep isl_space *space,
                enum isl_dim_type type);

The space used for creating a parameter domain needs to be created using isl_space_params_alloc. For other sets, the space needs to be created using isl_space_set_alloc, while for a relation, the space needs to be created using isl_space_alloc. isl_space_dim can be used to find out the number of dimensions of each type in a space, where type may be isl_dim_param, isl_dim_in (only for relations), isl_dim_out (only for relations), isl_dim_set (only for sets) or isl_dim_all.

To check whether a given space is that of a set or a map or whether it is a parameter space, use these functions:

        #include <isl/space.h>
        int isl_space_is_params(__isl_keep isl_space *space);
        int isl_space_is_set(__isl_keep isl_space *space);
        int isl_space_is_map(__isl_keep isl_space *space);

Spaces can be compared using the following functions:

        #include <isl/space.h>
        int isl_space_is_equal(__isl_keep isl_space *space1,
                __isl_keep isl_space *space2);
        int isl_space_is_domain(__isl_keep isl_space *space1,
                __isl_keep isl_space *space2);
        int isl_space_is_range(__isl_keep isl_space *space1,
                __isl_keep isl_space *space2);

isl_space_is_domain checks whether the first argument is equal to the domain of the second argument. This requires in particular that the first argument is a set space and that the second argument is a map space.

It is often useful to create objects that live in the same space as some other object. This can be accomplished by creating the new objects (see Creating New Sets and Relations or Creating New (Piecewise) Quasipolynomials) based on the space of the original object.

        #include <isl/set.h>
        __isl_give isl_space *isl_basic_set_get_space(
                __isl_keep isl_basic_set *bset);
        __isl_give isl_space *isl_set_get_space(__isl_keep isl_set *set);
        #include <isl/union_set.h>
        __isl_give isl_space *isl_union_set_get_space(
                __isl_keep isl_union_set *uset);
        #include <isl/map.h>
        __isl_give isl_space *isl_basic_map_get_space(
                __isl_keep isl_basic_map *bmap);
        __isl_give isl_space *isl_map_get_space(__isl_keep isl_map *map);
        #include <isl/union_map.h>
        __isl_give isl_space *isl_union_map_get_space(
                __isl_keep isl_union_map *umap);
        #include <isl/constraint.h>
        __isl_give isl_space *isl_constraint_get_space(
                __isl_keep isl_constraint *constraint);
        #include <isl/polynomial.h>
        __isl_give isl_space *isl_qpolynomial_get_domain_space(
                __isl_keep isl_qpolynomial *qp);
        __isl_give isl_space *isl_qpolynomial_get_space(
                __isl_keep isl_qpolynomial *qp);
        __isl_give isl_space *isl_qpolynomial_fold_get_space(
                __isl_keep isl_qpolynomial_fold *fold);
        __isl_give isl_space *isl_pw_qpolynomial_get_domain_space(
                __isl_keep isl_pw_qpolynomial *pwqp);
        __isl_give isl_space *isl_pw_qpolynomial_get_space(
                __isl_keep isl_pw_qpolynomial *pwqp);
        __isl_give isl_space *isl_pw_qpolynomial_fold_get_domain_space(
                __isl_keep isl_pw_qpolynomial_fold *pwf);
        __isl_give isl_space *isl_pw_qpolynomial_fold_get_space(
                __isl_keep isl_pw_qpolynomial_fold *pwf);
        __isl_give isl_space *isl_union_pw_qpolynomial_get_space(
                __isl_keep isl_union_pw_qpolynomial *upwqp);
        __isl_give isl_space *isl_union_pw_qpolynomial_fold_get_space(
                __isl_keep isl_union_pw_qpolynomial_fold *upwf);
        #include <isl/val.h>
        __isl_give isl_space *isl_multi_val_get_space(
                __isl_keep isl_multi_val *mv);
        #include <isl/aff.h>
        __isl_give isl_space *isl_aff_get_domain_space(
                __isl_keep isl_aff *aff);
        __isl_give isl_space *isl_aff_get_space(
                __isl_keep isl_aff *aff);
        __isl_give isl_space *isl_pw_aff_get_domain_space(
                __isl_keep isl_pw_aff *pwaff);
        __isl_give isl_space *isl_pw_aff_get_space(
                __isl_keep isl_pw_aff *pwaff);
        __isl_give isl_space *isl_multi_aff_get_domain_space(
                __isl_keep isl_multi_aff *maff);
        __isl_give isl_space *isl_multi_aff_get_space(
                __isl_keep isl_multi_aff *maff);
        __isl_give isl_space *isl_pw_multi_aff_get_domain_space(
                __isl_keep isl_pw_multi_aff *pma);
        __isl_give isl_space *isl_pw_multi_aff_get_space(
                __isl_keep isl_pw_multi_aff *pma);
        __isl_give isl_space *isl_union_pw_multi_aff_get_space(
                __isl_keep isl_union_pw_multi_aff *upma);
        __isl_give isl_space *isl_multi_pw_aff_get_domain_space(
                __isl_keep isl_multi_pw_aff *mpa);
        __isl_give isl_space *isl_multi_pw_aff_get_space(
                __isl_keep isl_multi_pw_aff *mpa);
        #include <isl/point.h>
        __isl_give isl_space *isl_point_get_space(
                __isl_keep isl_point *pnt);

The identifiers or names of the individual dimensions may be set or read off using the following functions.

        #include <isl/space.h>
        __isl_give isl_space *isl_space_set_dim_id(
                __isl_take isl_space *space,
                enum isl_dim_type type, unsigned pos,
                __isl_take isl_id *id);
        int isl_space_has_dim_id(__isl_keep isl_space *space,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_id *isl_space_get_dim_id(
                __isl_keep isl_space *space,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_space *isl_space_set_dim_name(
                __isl_take isl_space *space,
                 enum isl_dim_type type, unsigned pos,
                 __isl_keep const char *name);
        int isl_space_has_dim_name(__isl_keep isl_space *space,
                enum isl_dim_type type, unsigned pos);
        __isl_keep const char *isl_space_get_dim_name(
                __isl_keep isl_space *space,
                enum isl_dim_type type, unsigned pos);

Note that isl_space_get_name returns a pointer to some internal data structure, so the result can only be used while the corresponding isl_space is alive. Also note that every function that operates on two sets or relations requires that both arguments have the same parameters. This also means that if one of the arguments has named parameters, then the other needs to have named parameters too and the names need to match. Pairs of isl_set, isl_map, isl_union_set and/or isl_union_map arguments may have different parameters (as long as they are named), in which case the result will have as parameters the union of the parameters of the arguments.

Given the identifier or name of a dimension (typically a parameter), its position can be obtained from the following function.

        #include <isl/space.h>
        int isl_space_find_dim_by_id(__isl_keep isl_space *space,
                enum isl_dim_type type, __isl_keep isl_id *id);
        int isl_space_find_dim_by_name(__isl_keep isl_space *space,
                enum isl_dim_type type, const char *name);

The identifiers or names of entire spaces may be set or read off using the following functions.

        #include <isl/space.h>
        __isl_give isl_space *isl_space_set_tuple_id(
                __isl_take isl_space *space,
                enum isl_dim_type type, __isl_take isl_id *id);
        __isl_give isl_space *isl_space_reset_tuple_id(
                __isl_take isl_space *space, enum isl_dim_type type);
        int isl_space_has_tuple_id(__isl_keep isl_space *space,
                enum isl_dim_type type);
        __isl_give isl_id *isl_space_get_tuple_id(
                __isl_keep isl_space *space, enum isl_dim_type type);
        __isl_give isl_space *isl_space_set_tuple_name(
                __isl_take isl_space *space,
                enum isl_dim_type type, const char *s);
        int isl_space_has_tuple_name(__isl_keep isl_space *space,
                enum isl_dim_type type);
        const char *isl_space_get_tuple_name(__isl_keep isl_space *space,
                enum isl_dim_type type);

The type argument needs to be one of isl_dim_in, isl_dim_out or isl_dim_set. As with isl_space_get_name, the isl_space_get_tuple_name function returns a pointer to some internal data structure. Binary operations require the corresponding spaces of their arguments to have the same name.

Spaces can be nested. In particular, the domain of a set or the domain or range of a relation can be a nested relation. The following functions can be used to construct and deconstruct such nested spaces.

        #include <isl/space.h>
        int isl_space_is_wrapping(__isl_keep isl_space *space);
        __isl_give isl_space *isl_space_wrap(__isl_take isl_space *space);
        __isl_give isl_space *isl_space_unwrap(__isl_take isl_space *space);

The input to isl_space_is_wrapping and isl_space_unwrap should be the space of a set, while that of isl_space_wrap should be the space of a relation. Conversely, the output of isl_space_unwrap is the space of a relation, while that of isl_space_wrap is the space of a set.

Spaces can be created from other spaces using the following functions.

        __isl_give isl_space *isl_space_domain(__isl_take isl_space *space);
        __isl_give isl_space *isl_space_from_domain(__isl_take isl_space *space);
        __isl_give isl_space *isl_space_range(__isl_take isl_space *space);
        __isl_give isl_space *isl_space_from_range(__isl_take isl_space *space);
        __isl_give isl_space *isl_space_domain_map(
                __isl_take isl_space *space);
        __isl_give isl_space *isl_space_range_map(
                __isl_take isl_space *space);
        __isl_give isl_space *isl_space_params(
                __isl_take isl_space *space);
        __isl_give isl_space *isl_space_set_from_params(
                __isl_take isl_space *space);
        __isl_give isl_space *isl_space_reverse(__isl_take isl_space *space);
        __isl_give isl_space *isl_space_join(__isl_take isl_space *left,
                __isl_take isl_space *right);
        __isl_give isl_space *isl_space_align_params(
                __isl_take isl_space *space1, __isl_take isl_space *space2)
        __isl_give isl_space *isl_space_insert_dims(__isl_take isl_space *space,
                enum isl_dim_type type, unsigned pos, unsigned n);
        __isl_give isl_space *isl_space_add_dims(__isl_take isl_space *space,
                enum isl_dim_type type, unsigned n);
        __isl_give isl_space *isl_space_drop_dims(__isl_take isl_space *space,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_space *isl_space_move_dims(__isl_take isl_space *space,
                enum isl_dim_type dst_type, unsigned dst_pos,
                enum isl_dim_type src_type, unsigned src_pos,
                unsigned n);
        __isl_give isl_space *isl_space_map_from_set(
                __isl_take isl_space *space);
        __isl_give isl_space *isl_space_map_from_domain_and_range(
                __isl_take isl_space *domain,
                __isl_take isl_space *range);
        __isl_give isl_space *isl_space_zip(__isl_take isl_space *space);
        __isl_give isl_space *isl_space_curry(
                __isl_take isl_space *space);
        __isl_give isl_space *isl_space_uncurry(
                __isl_take isl_space *space);

Note that if dimensions are added or removed from a space, then the name and the internal structure are lost.

Local Spaces

A local space is essentially a space with zero or more existentially quantified variables. The local space of a (constraint of a) basic set or relation can be obtained using the following functions.

        #include <isl/constraint.h>
        __isl_give isl_local_space *isl_constraint_get_local_space(
                __isl_keep isl_constraint *constraint);
        #include <isl/set.h>
        __isl_give isl_local_space *isl_basic_set_get_local_space(
                __isl_keep isl_basic_set *bset);
        #include <isl/map.h>
        __isl_give isl_local_space *isl_basic_map_get_local_space(
                __isl_keep isl_basic_map *bmap);

A new local space can be created from a space using

        #include <isl/local_space.h>
        __isl_give isl_local_space *isl_local_space_from_space(
                __isl_take isl_space *space);

They can be inspected, modified, copied and freed using the following functions.

        #include <isl/local_space.h>
        isl_ctx *isl_local_space_get_ctx(
                __isl_keep isl_local_space *ls);
        int isl_local_space_is_set(__isl_keep isl_local_space *ls);
        int isl_local_space_dim(__isl_keep isl_local_space *ls,
                enum isl_dim_type type);
        int isl_local_space_has_dim_id(
                __isl_keep isl_local_space *ls,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_id *isl_local_space_get_dim_id(
                __isl_keep isl_local_space *ls,
                enum isl_dim_type type, unsigned pos);
        int isl_local_space_has_dim_name(
                __isl_keep isl_local_space *ls,
                enum isl_dim_type type, unsigned pos)
        const char *isl_local_space_get_dim_name(
                __isl_keep isl_local_space *ls,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_local_space *isl_local_space_set_dim_name(
                __isl_take isl_local_space *ls,
                enum isl_dim_type type, unsigned pos, const char *s);
        __isl_give isl_local_space *isl_local_space_set_dim_id(
                __isl_take isl_local_space *ls,
                enum isl_dim_type type, unsigned pos,
                __isl_take isl_id *id);
        __isl_give isl_space *isl_local_space_get_space(
                __isl_keep isl_local_space *ls);
        __isl_give isl_aff *isl_local_space_get_div(
                __isl_keep isl_local_space *ls, int pos);
        __isl_give isl_local_space *isl_local_space_copy(
                __isl_keep isl_local_space *ls);
        void *isl_local_space_free(__isl_take isl_local_space *ls);

Note that isl_local_space_get_div can only be used on local spaces of sets.

Two local spaces can be compared using

        int isl_local_space_is_equal(__isl_keep isl_local_space *ls1,
                __isl_keep isl_local_space *ls2);

Local spaces can be created from other local spaces using the following functions.

        __isl_give isl_local_space *isl_local_space_domain(
                __isl_take isl_local_space *ls);
        __isl_give isl_local_space *isl_local_space_range(
                __isl_take isl_local_space *ls);
        __isl_give isl_local_space *isl_local_space_from_domain(
                __isl_take isl_local_space *ls);
        __isl_give isl_local_space *isl_local_space_intersect(
                __isl_take isl_local_space *ls1,
                __isl_take isl_local_space *ls2);
        __isl_give isl_local_space *isl_local_space_add_dims(
                __isl_take isl_local_space *ls,
                enum isl_dim_type type, unsigned n);
        __isl_give isl_local_space *isl_local_space_insert_dims(
                __isl_take isl_local_space *ls,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_local_space *isl_local_space_drop_dims(
                __isl_take isl_local_space *ls,
                enum isl_dim_type type, unsigned first, unsigned n);

Input and Output

isl supports its own input/output format, which is similar to the Omega format, but also supports the PolyLib format in some cases.

isl format

The isl format is similar to that of Omega, but has a different syntax for describing the parameters and allows for the definition of an existentially quantified variable as the integer division of an affine expression. For example, the set of integers i between 0 and n such that i % 10 <= 6 can be described as

        [n] -> { [i] : exists (a = [i/10] : 0 <= i and i <= n and
                                i - 10 a <= 6) }

A set or relation can have several disjuncts, separated by the keyword or. Each disjunct is either a conjunction of constraints or a projection (exists) of a conjunction of constraints. The constraints are separated by the keyword and.

PolyLib format

If the represented set is a union, then the first line contains a single number representing the number of disjuncts. Otherwise, a line containing the number 1 is optional.

Each disjunct is represented by a matrix of constraints. The first line contains two numbers representing the number of rows and columns, where the number of rows is equal to the number of constraints and the number of columns is equal to two plus the number of variables. The following lines contain the actual rows of the constraint matrix. In each row, the first column indicates whether the constraint is an equality (0) or inequality (1). The final column corresponds to the constant term.

If the set is parametric, then the coefficients of the parameters appear in the last columns before the constant column. The coefficients of any existentially quantified variables appear between those of the set variables and those of the parameters.

Extended PolyLib format

The extended PolyLib format is nearly identical to the PolyLib format. The only difference is that the line containing the number of rows and columns of a constraint matrix also contains four additional numbers: the number of output dimensions, the number of input dimensions, the number of local dimensions (i.e., the number of existentially quantified variables) and the number of parameters. For sets, the number of ``output'' dimensions is equal to the number of set dimensions, while the number of ``input'' dimensions is zero.

Input

        #include <isl/set.h>
        __isl_give isl_basic_set *isl_basic_set_read_from_file(
                isl_ctx *ctx, FILE *input);
        __isl_give isl_basic_set *isl_basic_set_read_from_str(
                isl_ctx *ctx, const char *str);
        __isl_give isl_set *isl_set_read_from_file(isl_ctx *ctx,
                FILE *input);
        __isl_give isl_set *isl_set_read_from_str(isl_ctx *ctx,
                const char *str);
        #include <isl/map.h>
        __isl_give isl_basic_map *isl_basic_map_read_from_file(
                isl_ctx *ctx, FILE *input);
        __isl_give isl_basic_map *isl_basic_map_read_from_str(
                isl_ctx *ctx, const char *str);
        __isl_give isl_map *isl_map_read_from_file(
                isl_ctx *ctx, FILE *input);
        __isl_give isl_map *isl_map_read_from_str(isl_ctx *ctx,
                const char *str);
        #include <isl/union_set.h>
        __isl_give isl_union_set *isl_union_set_read_from_file(
                isl_ctx *ctx, FILE *input);
        __isl_give isl_union_set *isl_union_set_read_from_str(
                isl_ctx *ctx, const char *str);
        #include <isl/union_map.h>
        __isl_give isl_union_map *isl_union_map_read_from_file(
                isl_ctx *ctx, FILE *input);
        __isl_give isl_union_map *isl_union_map_read_from_str(
                isl_ctx *ctx, const char *str);

The input format is autodetected and may be either the PolyLib format or the isl format.

Output

Before anything can be printed, an isl_printer needs to be created.

        __isl_give isl_printer *isl_printer_to_file(isl_ctx *ctx,
                FILE *file);
        __isl_give isl_printer *isl_printer_to_str(isl_ctx *ctx);
        void *isl_printer_free(__isl_take isl_printer *printer);
        __isl_give char *isl_printer_get_str(
                __isl_keep isl_printer *printer);

The printer can be inspected using the following functions.

        FILE *isl_printer_get_file(
                __isl_keep isl_printer *printer);
        int isl_printer_get_output_format(
                __isl_keep isl_printer *p);

The behavior of the printer can be modified in various ways

        __isl_give isl_printer *isl_printer_set_output_format(
                __isl_take isl_printer *p, int output_format);
        __isl_give isl_printer *isl_printer_set_indent(
                __isl_take isl_printer *p, int indent);
        __isl_give isl_printer *isl_printer_indent(
                __isl_take isl_printer *p, int indent);
        __isl_give isl_printer *isl_printer_set_prefix(
                __isl_take isl_printer *p, const char *prefix);
        __isl_give isl_printer *isl_printer_set_suffix(
                __isl_take isl_printer *p, const char *suffix);

The output_format may be either ISL_FORMAT_ISL, ISL_FORMAT_OMEGA, ISL_FORMAT_POLYLIB, ISL_FORMAT_EXT_POLYLIB or ISL_FORMAT_LATEX and defaults to ISL_FORMAT_ISL. Each line in the output is indented by indent (set by isl_printer_set_indent) spaces (default: 0), prefixed by prefix and suffixed by suffix. In the PolyLib format output, the coefficients of the existentially quantified variables appear between those of the set variables and those of the parameters. The function isl_printer_indent increases the indentation by the specified amount (which may be negative).

To actually print something, use

        #include <isl/printer.h>
        __isl_give isl_printer *isl_printer_print_double(
                __isl_take isl_printer *p, double d);
        #include <isl/set.h>
        __isl_give isl_printer *isl_printer_print_basic_set(
                __isl_take isl_printer *printer,
                __isl_keep isl_basic_set *bset);
        __isl_give isl_printer *isl_printer_print_set(
                __isl_take isl_printer *printer,
                __isl_keep isl_set *set);
        #include <isl/map.h>
        __isl_give isl_printer *isl_printer_print_basic_map(
                __isl_take isl_printer *printer,
                __isl_keep isl_basic_map *bmap);
        __isl_give isl_printer *isl_printer_print_map(
                __isl_take isl_printer *printer,
                __isl_keep isl_map *map);
        #include <isl/union_set.h>
        __isl_give isl_printer *isl_printer_print_union_set(
                __isl_take isl_printer *p,
                __isl_keep isl_union_set *uset);
        #include <isl/union_map.h>
        __isl_give isl_printer *isl_printer_print_union_map(
                __isl_take isl_printer *p,
                __isl_keep isl_union_map *umap);

When called on a file printer, the following function flushes the file. When called on a string printer, the buffer is cleared.

        __isl_give isl_printer *isl_printer_flush(
                __isl_take isl_printer *p);

Creating New Sets and Relations

isl has functions for creating some standard sets and relations.

A basic set or relation can be converted to a set or relation using the following functions.

        __isl_give isl_set *isl_set_from_basic_set(
                __isl_take isl_basic_set *bset);
        __isl_give isl_map *isl_map_from_basic_map(
                __isl_take isl_basic_map *bmap);

Sets and relations can be converted to union sets and relations using the following functions.

        __isl_give isl_union_set *isl_union_set_from_basic_set(
                __isl_take isl_basic_set *bset);
        __isl_give isl_union_map *isl_union_map_from_basic_map(
                __isl_take isl_basic_map *bmap);
        __isl_give isl_union_set *isl_union_set_from_set(
                __isl_take isl_set *set);
        __isl_give isl_union_map *isl_union_map_from_map(
                __isl_take isl_map *map);

The inverse conversions below can only be used if the input union set or relation is known to contain elements in exactly one space.

        __isl_give isl_set *isl_set_from_union_set(
                __isl_take isl_union_set *uset);
        __isl_give isl_map *isl_map_from_union_map(
                __isl_take isl_union_map *umap);

A zero-dimensional (basic) set can be constructed on a given parameter domain using the following function.

        __isl_give isl_basic_set *isl_basic_set_from_params(
                __isl_take isl_basic_set *bset);
        __isl_give isl_set *isl_set_from_params(
                __isl_take isl_set *set);

Sets and relations can be copied and freed again using the following functions.

        __isl_give isl_basic_set *isl_basic_set_copy(
                __isl_keep isl_basic_set *bset);
        __isl_give isl_set *isl_set_copy(__isl_keep isl_set *set);
        __isl_give isl_union_set *isl_union_set_copy(
                __isl_keep isl_union_set *uset);
        __isl_give isl_basic_map *isl_basic_map_copy(
                __isl_keep isl_basic_map *bmap);
        __isl_give isl_map *isl_map_copy(__isl_keep isl_map *map);
        __isl_give isl_union_map *isl_union_map_copy(
                __isl_keep isl_union_map *umap);
        void *isl_basic_set_free(__isl_take isl_basic_set *bset);
        void *isl_set_free(__isl_take isl_set *set);
        void *isl_union_set_free(__isl_take isl_union_set *uset);
        void *isl_basic_map_free(__isl_take isl_basic_map *bmap);
        void *isl_map_free(__isl_take isl_map *map);
        void *isl_union_map_free(__isl_take isl_union_map *umap);

Other sets and relations can be constructed by starting from a universe set or relation, adding equality and/or inequality constraints and then projecting out the existentially quantified variables, if any. Constraints can be constructed, manipulated and added to (or removed from) (basic) sets and relations using the following functions.

        #include <isl/constraint.h>
        __isl_give isl_constraint *isl_equality_alloc(
                __isl_take isl_local_space *ls);
        __isl_give isl_constraint *isl_inequality_alloc(
                __isl_take isl_local_space *ls);
        __isl_give isl_constraint *isl_constraint_set_constant_si(
                __isl_take isl_constraint *constraint, int v);
        __isl_give isl_constraint *isl_constraint_set_constant_val(
                __isl_take isl_constraint *constraint,
                __isl_take isl_val *v);
        __isl_give isl_constraint *isl_constraint_set_coefficient_si(
                __isl_take isl_constraint *constraint,
                enum isl_dim_type type, int pos, int v);
        __isl_give isl_constraint *
        isl_constraint_set_coefficient_val(
                __isl_take isl_constraint *constraint,
                enum isl_dim_type type, int pos, isl_val *v);
        __isl_give isl_basic_map *isl_basic_map_add_constraint(
                __isl_take isl_basic_map *bmap,
                __isl_take isl_constraint *constraint);
        __isl_give isl_basic_set *isl_basic_set_add_constraint(
                __isl_take isl_basic_set *bset,
                __isl_take isl_constraint *constraint);
        __isl_give isl_map *isl_map_add_constraint(
                __isl_take isl_map *map,
                __isl_take isl_constraint *constraint);
        __isl_give isl_set *isl_set_add_constraint(
                __isl_take isl_set *set,
                __isl_take isl_constraint *constraint);
        __isl_give isl_basic_set *isl_basic_set_drop_constraint(
                __isl_take isl_basic_set *bset,
                __isl_take isl_constraint *constraint);

For example, to create a set containing the even integers between 10 and 42, you would use the following code.

        isl_space *space;
        isl_local_space *ls;
        isl_constraint *c;
        isl_basic_set *bset;
        space = isl_space_set_alloc(ctx, 0, 2);
        bset = isl_basic_set_universe(isl_space_copy(space));
        ls = isl_local_space_from_space(space);
        c = isl_equality_alloc(isl_local_space_copy(ls));
        c = isl_constraint_set_coefficient_si(c, isl_dim_set, 0, -1);
        c = isl_constraint_set_coefficient_si(c, isl_dim_set, 1, 2);
        bset = isl_basic_set_add_constraint(bset, c);
        c = isl_inequality_alloc(isl_local_space_copy(ls));
        c = isl_constraint_set_constant_si(c, -10);
        c = isl_constraint_set_coefficient_si(c, isl_dim_set, 0, 1);
        bset = isl_basic_set_add_constraint(bset, c);
        c = isl_inequality_alloc(ls);
        c = isl_constraint_set_constant_si(c, 42);
        c = isl_constraint_set_coefficient_si(c, isl_dim_set, 0, -1);
        bset = isl_basic_set_add_constraint(bset, c);
        bset = isl_basic_set_project_out(bset, isl_dim_set, 1, 1);

Or, alternatively,

        isl_basic_set *bset;
        bset = isl_basic_set_read_from_str(ctx,
                "{[i] : exists (a : i = 2a and i >= 10 and i <= 42)}");

A basic set or relation can also be constructed from two matrices describing the equalities and the inequalities.

        __isl_give isl_basic_set *isl_basic_set_from_constraint_matrices(
                __isl_take isl_space *space,
                __isl_take isl_mat *eq, __isl_take isl_mat *ineq,
                enum isl_dim_type c1,
                enum isl_dim_type c2, enum isl_dim_type c3,
                enum isl_dim_type c4);
        __isl_give isl_basic_map *isl_basic_map_from_constraint_matrices(
                __isl_take isl_space *space,
                __isl_take isl_mat *eq, __isl_take isl_mat *ineq,
                enum isl_dim_type c1,
                enum isl_dim_type c2, enum isl_dim_type c3,
                enum isl_dim_type c4, enum isl_dim_type c5);

The isl_dim_type arguments indicate the order in which different kinds of variables appear in the input matrices and should be a permutation of isl_dim_cst, isl_dim_param, isl_dim_set and isl_dim_div for sets and of isl_dim_cst, isl_dim_param, isl_dim_in, isl_dim_out and isl_dim_div for relations.

A (basic or union) set or relation can also be constructed from a (union) (piecewise) (multiple) affine expression or a list of affine expressions (See Piecewise Quasi Affine Expressions and Piecewise Multiple Quasi Affine Expressions).

        __isl_give isl_basic_map *isl_basic_map_from_aff(
                __isl_take isl_aff *aff);
        __isl_give isl_map *isl_map_from_aff(
                __isl_take isl_aff *aff);
        __isl_give isl_set *isl_set_from_pw_aff(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_map *isl_map_from_pw_aff(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_basic_map *isl_basic_map_from_aff_list(
                __isl_take isl_space *domain_space,
                __isl_take isl_aff_list *list);
        __isl_give isl_basic_map *isl_basic_map_from_multi_aff(
                __isl_take isl_multi_aff *maff)
        __isl_give isl_map *isl_map_from_multi_aff(
                __isl_take isl_multi_aff *maff)
        __isl_give isl_set *isl_set_from_pw_multi_aff(
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_map *isl_map_from_pw_multi_aff(
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_set *isl_set_from_multi_pw_aff(
                __isl_take isl_multi_pw_aff *mpa);
        __isl_give isl_map *isl_map_from_multi_pw_aff(
                __isl_take isl_multi_pw_aff *mpa);
        __isl_give isl_union_map *
        isl_union_map_from_union_pw_multi_aff(
                __isl_take isl_union_pw_multi_aff *upma);

The domain_dim argument describes the domain of the resulting basic relation. It is required because the list may consist of zero affine expressions.

Inspecting Sets and Relations

Usually, the user should not have to care about the actual constraints of the sets and maps, but should instead apply the abstract operations explained in the following sections. Occasionally, however, it may be required to inspect the individual coefficients of the constraints. This section explains how to do so. In these cases, it may also be useful to have isl compute an explicit representation of the existentially quantified variables.

        __isl_give isl_set *isl_set_compute_divs(
                __isl_take isl_set *set);
        __isl_give isl_map *isl_map_compute_divs(
                __isl_take isl_map *map);
        __isl_give isl_union_set *isl_union_set_compute_divs(
                __isl_take isl_union_set *uset);
        __isl_give isl_union_map *isl_union_map_compute_divs(
                __isl_take isl_union_map *umap);

This explicit representation defines the existentially quantified variables as integer divisions of the other variables, possibly including earlier existentially quantified variables. An explicitly represented existentially quantified variable therefore has a unique value when the values of the other variables are known. If, furthermore, the same existentials, i.e., existentials with the same explicit representations, should appear in the same order in each of the disjuncts of a set or map, then the user should call either of the following functions.

        __isl_give isl_set *isl_set_align_divs(
                __isl_take isl_set *set);
        __isl_give isl_map *isl_map_align_divs(
                __isl_take isl_map *map);

Alternatively, the existentially quantified variables can be removed using the following functions, which compute an overapproximation.

        __isl_give isl_basic_set *isl_basic_set_remove_divs(
                __isl_take isl_basic_set *bset);
        __isl_give isl_basic_map *isl_basic_map_remove_divs(
                __isl_take isl_basic_map *bmap);
        __isl_give isl_set *isl_set_remove_divs(
                __isl_take isl_set *set);
        __isl_give isl_map *isl_map_remove_divs(
                __isl_take isl_map *map);

It is also possible to only remove those divs that are defined in terms of a given range of dimensions or only those for which no explicit representation is known.

        __isl_give isl_basic_set *
        isl_basic_set_remove_divs_involving_dims(
                __isl_take isl_basic_set *bset,
                enum isl_dim_type type,
                unsigned first, unsigned n);
        __isl_give isl_basic_map *
        isl_basic_map_remove_divs_involving_dims(
                __isl_take isl_basic_map *bmap,
                enum isl_dim_type type,
                unsigned first, unsigned n);
        __isl_give isl_set *isl_set_remove_divs_involving_dims(
                __isl_take isl_set *set, enum isl_dim_type type,
                unsigned first, unsigned n);
        __isl_give isl_map *isl_map_remove_divs_involving_dims(
                __isl_take isl_map *map, enum isl_dim_type type,
                unsigned first, unsigned n);
        __isl_give isl_basic_set *
        isl_basic_set_remove_unknown_divs(
                __isl_take isl_basic_set *bset);
        __isl_give isl_set *isl_set_remove_unknown_divs(
                __isl_take isl_set *set);
        __isl_give isl_map *isl_map_remove_unknown_divs(
                __isl_take isl_map *map);

To iterate over all the sets or maps in a union set or map, use

        int isl_union_set_foreach_set(__isl_keep isl_union_set *uset,
                int (*fn)(__isl_take isl_set *set, void *user),
                void *user);
        int isl_union_map_foreach_map(__isl_keep isl_union_map *umap,
                int (*fn)(__isl_take isl_map *map, void *user),
                void *user);

The number of sets or maps in a union set or map can be obtained from

        int isl_union_set_n_set(__isl_keep isl_union_set *uset);
        int isl_union_map_n_map(__isl_keep isl_union_map *umap);

To extract the set or map in a given space from a union, use

        __isl_give isl_set *isl_union_set_extract_set(
                __isl_keep isl_union_set *uset,
                __isl_take isl_space *space);
        __isl_give isl_map *isl_union_map_extract_map(
                __isl_keep isl_union_map *umap,
                __isl_take isl_space *space);

To iterate over all the basic sets or maps in a set or map, use

        int isl_set_foreach_basic_set(__isl_keep isl_set *set,
                int (*fn)(__isl_take isl_basic_set *bset, void *user),
                void *user);
        int isl_map_foreach_basic_map(__isl_keep isl_map *map,
                int (*fn)(__isl_take isl_basic_map *bmap, void *user),
                void *user);

The callback function fn should return 0 if successful and -1 if an error occurs. In the latter case, or if any other error occurs, the above functions will return -1.

It should be noted that isl does not guarantee that the basic sets or maps passed to fn are disjoint. If this is required, then the user should call one of the following functions first.

        __isl_give isl_set *isl_set_make_disjoint(
                __isl_take isl_set *set);
        __isl_give isl_map *isl_map_make_disjoint(
                __isl_take isl_map *map);

The number of basic sets in a set can be obtained from

        int isl_set_n_basic_set(__isl_keep isl_set *set);

To iterate over the constraints of a basic set or map, use

        #include <isl/constraint.h>
        int isl_basic_set_n_constraint(
                __isl_keep isl_basic_set *bset);
        int isl_basic_set_foreach_constraint(
                __isl_keep isl_basic_set *bset,
                int (*fn)(__isl_take isl_constraint *c, void *user),
                void *user);
        int isl_basic_map_foreach_constraint(
                __isl_keep isl_basic_map *bmap,
                int (*fn)(__isl_take isl_constraint *c, void *user),
                void *user);
        void *isl_constraint_free(__isl_take isl_constraint *c);

Again, the callback function fn should return 0 if successful and -1 if an error occurs. In the latter case, or if any other error occurs, the above functions will return -1. The constraint c represents either an equality or an inequality. Use the following function to find out whether a constraint represents an equality. If not, it represents an inequality.

        int isl_constraint_is_equality(
                __isl_keep isl_constraint *constraint);

The coefficients of the constraints can be inspected using the following functions.

        int isl_constraint_is_lower_bound(
                __isl_keep isl_constraint *constraint,
                enum isl_dim_type type, unsigned pos);
        int isl_constraint_is_upper_bound(
                __isl_keep isl_constraint *constraint,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_val *isl_constraint_get_constant_val(
                __isl_keep isl_constraint *constraint);
        __isl_give isl_val *isl_constraint_get_coefficient_val(
                __isl_keep isl_constraint *constraint,
                enum isl_dim_type type, int pos);
        int isl_constraint_involves_dims(
                __isl_keep isl_constraint *constraint,
                enum isl_dim_type type, unsigned first, unsigned n);

The explicit representations of the existentially quantified variables can be inspected using the following function. Note that the user is only allowed to use this function if the inspected set or map is the result of a call to isl_set_compute_divs or isl_map_compute_divs. The existentially quantified variable is equal to the floor of the returned affine expression. The affine expression itself can be inspected using the functions in Piecewise Quasi Affine Expressions.

        __isl_give isl_aff *isl_constraint_get_div(
                __isl_keep isl_constraint *constraint, int pos);

To obtain the constraints of a basic set or map in matrix form, use the following functions.

        __isl_give isl_mat *isl_basic_set_equalities_matrix(
                __isl_keep isl_basic_set *bset,
                enum isl_dim_type c1, enum isl_dim_type c2,
                enum isl_dim_type c3, enum isl_dim_type c4);
        __isl_give isl_mat *isl_basic_set_inequalities_matrix(
                __isl_keep isl_basic_set *bset,
                enum isl_dim_type c1, enum isl_dim_type c2,
                enum isl_dim_type c3, enum isl_dim_type c4);
        __isl_give isl_mat *isl_basic_map_equalities_matrix(
                __isl_keep isl_basic_map *bmap,
                enum isl_dim_type c1,
                enum isl_dim_type c2, enum isl_dim_type c3,
                enum isl_dim_type c4, enum isl_dim_type c5);
        __isl_give isl_mat *isl_basic_map_inequalities_matrix(
                __isl_keep isl_basic_map *bmap,
                enum isl_dim_type c1,
                enum isl_dim_type c2, enum isl_dim_type c3,
                enum isl_dim_type c4, enum isl_dim_type c5);

The isl_dim_type arguments dictate the order in which different kinds of variables appear in the resulting matrix and should be a permutation of isl_dim_cst, isl_dim_param, isl_dim_in, isl_dim_out and isl_dim_div.

The number of parameters, input, output or set dimensions can be obtained using the following functions.

        unsigned isl_basic_set_dim(__isl_keep isl_basic_set *bset,
                enum isl_dim_type type);
        unsigned isl_basic_map_dim(__isl_keep isl_basic_map *bmap,
                enum isl_dim_type type);
        unsigned isl_set_dim(__isl_keep isl_set *set,
                enum isl_dim_type type);
        unsigned isl_map_dim(__isl_keep isl_map *map,
                enum isl_dim_type type);

To check whether the description of a set or relation depends on one or more given dimensions, it is not necessary to iterate over all constraints. Instead the following functions can be used.

        int isl_basic_set_involves_dims(
                __isl_keep isl_basic_set *bset,
                enum isl_dim_type type, unsigned first, unsigned n);
        int isl_set_involves_dims(__isl_keep isl_set *set,
                enum isl_dim_type type, unsigned first, unsigned n);
        int isl_basic_map_involves_dims(
                __isl_keep isl_basic_map *bmap,
                enum isl_dim_type type, unsigned first, unsigned n);
        int isl_map_involves_dims(__isl_keep isl_map *map,
                enum isl_dim_type type, unsigned first, unsigned n);

Similarly, the following functions can be used to check whether a given dimension is involved in any lower or upper bound.

        int isl_set_dim_has_any_lower_bound(__isl_keep isl_set *set,
                enum isl_dim_type type, unsigned pos);
        int isl_set_dim_has_any_upper_bound(__isl_keep isl_set *set,
                enum isl_dim_type type, unsigned pos);

Note that these functions return true even if there is a bound on the dimension on only some of the basic sets of set. To check if they have a bound for all of the basic sets in set, use the following functions instead.

        int isl_set_dim_has_lower_bound(__isl_keep isl_set *set,
                enum isl_dim_type type, unsigned pos);
        int isl_set_dim_has_upper_bound(__isl_keep isl_set *set,
                enum isl_dim_type type, unsigned pos);

The identifiers or names of the domain and range spaces of a set or relation can be read off or set using the following functions.

        __isl_give isl_set *isl_set_set_tuple_id(
                __isl_take isl_set *set, __isl_take isl_id *id);
        __isl_give isl_set *isl_set_reset_tuple_id(
                __isl_take isl_set *set);
        int isl_set_has_tuple_id(__isl_keep isl_set *set);
        __isl_give isl_id *isl_set_get_tuple_id(
                __isl_keep isl_set *set);
        __isl_give isl_map *isl_map_set_tuple_id(
                __isl_take isl_map *map, enum isl_dim_type type,
                __isl_take isl_id *id);
        __isl_give isl_map *isl_map_reset_tuple_id(
                __isl_take isl_map *map, enum isl_dim_type type);
        int isl_map_has_tuple_id(__isl_keep isl_map *map,
                enum isl_dim_type type);
        __isl_give isl_id *isl_map_get_tuple_id(
                __isl_keep isl_map *map, enum isl_dim_type type);
        const char *isl_basic_set_get_tuple_name(
                __isl_keep isl_basic_set *bset);
        __isl_give isl_basic_set *isl_basic_set_set_tuple_name(
                __isl_take isl_basic_set *set, const char *s);
        int isl_set_has_tuple_name(__isl_keep isl_set *set);
        const char *isl_set_get_tuple_name(
                __isl_keep isl_set *set);
        const char *isl_basic_map_get_tuple_name(
                __isl_keep isl_basic_map *bmap,
                enum isl_dim_type type);
        __isl_give isl_basic_map *isl_basic_map_set_tuple_name(
                __isl_take isl_basic_map *bmap,
                enum isl_dim_type type, const char *s);
        int isl_map_has_tuple_name(__isl_keep isl_map *map,
                enum isl_dim_type type);
        const char *isl_map_get_tuple_name(
                __isl_keep isl_map *map,
                enum isl_dim_type type);

As with isl_space_get_tuple_name, the value returned points to an internal data structure. The identifiers, positions or names of individual dimensions can be read off using the following functions.

        __isl_give isl_id *isl_basic_set_get_dim_id(
                __isl_keep isl_basic_set *bset,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_set *isl_set_set_dim_id(
                __isl_take isl_set *set, enum isl_dim_type type,
                unsigned pos, __isl_take isl_id *id);
        int isl_set_has_dim_id(__isl_keep isl_set *set,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_id *isl_set_get_dim_id(
                __isl_keep isl_set *set, enum isl_dim_type type,
                unsigned pos);
        int isl_basic_map_has_dim_id(
                __isl_keep isl_basic_map *bmap,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_map *isl_map_set_dim_id(
                __isl_take isl_map *map, enum isl_dim_type type,
                unsigned pos, __isl_take isl_id *id);
        int isl_map_has_dim_id(__isl_keep isl_map *map,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_id *isl_map_get_dim_id(
                __isl_keep isl_map *map, enum isl_dim_type type,
                unsigned pos);
        int isl_set_find_dim_by_id(__isl_keep isl_set *set,
                enum isl_dim_type type, __isl_keep isl_id *id);
        int isl_map_find_dim_by_id(__isl_keep isl_map *map,
                enum isl_dim_type type, __isl_keep isl_id *id);
        int isl_set_find_dim_by_name(__isl_keep isl_set *set,
                enum isl_dim_type type, const char *name);
        int isl_map_find_dim_by_name(__isl_keep isl_map *map,
                enum isl_dim_type type, const char *name);
        const char *isl_constraint_get_dim_name(
                __isl_keep isl_constraint *constraint,
                enum isl_dim_type type, unsigned pos);
        const char *isl_basic_set_get_dim_name(
                __isl_keep isl_basic_set *bset,
                enum isl_dim_type type, unsigned pos);
        int isl_set_has_dim_name(__isl_keep isl_set *set,
                enum isl_dim_type type, unsigned pos);
        const char *isl_set_get_dim_name(
                __isl_keep isl_set *set,
                enum isl_dim_type type, unsigned pos);
        const char *isl_basic_map_get_dim_name(
                __isl_keep isl_basic_map *bmap,
                enum isl_dim_type type, unsigned pos);
        int isl_map_has_dim_name(__isl_keep isl_map *map,
                enum isl_dim_type type, unsigned pos);
        const char *isl_map_get_dim_name(
                __isl_keep isl_map *map,
                enum isl_dim_type type, unsigned pos);

These functions are mostly useful to obtain the identifiers, positions or names of the parameters. Identifiers of individual dimensions are essentially only useful for printing. They are ignored by all other operations and may not be preserved across those operations.

Properties

Unary Properties

Binary Properties

Unary Operations

Binary Operations

The two arguments of a binary operation not only need to live in the same isl_ctx, they currently also need to have the same (number of) parameters.

Basic Operations

Lexicographic Optimization

Given a (basic) set set (or bset) and a zero-dimensional domain dom, the following functions compute a set that contains the lexicographic minimum or maximum of the elements in set (or bset) for those values of the parameters that satisfy dom. If empty is not NULL, then *empty is assigned a set that contains the parameter values in dom for which set (or bset) has no elements. In other words, the union of the parameter values for which the result is non-empty and of *empty is equal to dom.

        __isl_give isl_set *isl_basic_set_partial_lexmin(
                __isl_take isl_basic_set *bset,
                __isl_take isl_basic_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_set *isl_basic_set_partial_lexmax(
                __isl_take isl_basic_set *bset,
                __isl_take isl_basic_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_set *isl_set_partial_lexmin(
                __isl_take isl_set *set, __isl_take isl_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_set *isl_set_partial_lexmax(
                __isl_take isl_set *set, __isl_take isl_set *dom,
                __isl_give isl_set **empty);

Given a (basic) set set (or bset), the following functions simply return a set containing the lexicographic minimum or maximum of the elements in set (or bset). In case of union sets, the optimum is computed per space.

        __isl_give isl_set *isl_basic_set_lexmin(
                __isl_take isl_basic_set *bset);
        __isl_give isl_set *isl_basic_set_lexmax(
                __isl_take isl_basic_set *bset);
        __isl_give isl_set *isl_set_lexmin(
                __isl_take isl_set *set);
        __isl_give isl_set *isl_set_lexmax(
                __isl_take isl_set *set);
        __isl_give isl_union_set *isl_union_set_lexmin(
                __isl_take isl_union_set *uset);
        __isl_give isl_union_set *isl_union_set_lexmax(
                __isl_take isl_union_set *uset);

Given a (basic) relation map (or bmap) and a domain dom, the following functions compute a relation that maps each element of dom to the single lexicographic minimum or maximum of the elements that are associated to that same element in map (or bmap). If empty is not NULL, then *empty is assigned a set that contains the elements in dom that do not map to any elements in map (or bmap). In other words, the union of the domain of the result and of *empty is equal to dom.

        __isl_give isl_map *isl_basic_map_partial_lexmax(
                __isl_take isl_basic_map *bmap,
                __isl_take isl_basic_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_map *isl_basic_map_partial_lexmin(
                __isl_take isl_basic_map *bmap,
                __isl_take isl_basic_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_map *isl_map_partial_lexmax(
                __isl_take isl_map *map, __isl_take isl_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_map *isl_map_partial_lexmin(
                __isl_take isl_map *map, __isl_take isl_set *dom,
                __isl_give isl_set **empty);

Given a (basic) map map (or bmap), the following functions simply return a map mapping each element in the domain of map (or bmap) to the lexicographic minimum or maximum of all elements associated to that element. In case of union relations, the optimum is computed per space.

        __isl_give isl_map *isl_basic_map_lexmin(
                __isl_take isl_basic_map *bmap);
        __isl_give isl_map *isl_basic_map_lexmax(
                __isl_take isl_basic_map *bmap);
        __isl_give isl_map *isl_map_lexmin(
                __isl_take isl_map *map);
        __isl_give isl_map *isl_map_lexmax(
                __isl_take isl_map *map);
        __isl_give isl_union_map *isl_union_map_lexmin(
                __isl_take isl_union_map *umap);
        __isl_give isl_union_map *isl_union_map_lexmax(
                __isl_take isl_union_map *umap);

The following functions return their result in the form of a piecewise multi-affine expression (See Piecewise Multiple Quasi Affine Expressions), but are otherwise equivalent to the corresponding functions returning a basic set or relation.

        __isl_give isl_pw_multi_aff *
        isl_basic_map_lexmin_pw_multi_aff(
                __isl_take isl_basic_map *bmap);
        __isl_give isl_pw_multi_aff *
        isl_basic_set_partial_lexmin_pw_multi_aff(
                __isl_take isl_basic_set *bset,
                __isl_take isl_basic_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_pw_multi_aff *
        isl_basic_set_partial_lexmax_pw_multi_aff(
                __isl_take isl_basic_set *bset,
                __isl_take isl_basic_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_pw_multi_aff *
        isl_basic_map_partial_lexmin_pw_multi_aff(
                __isl_take isl_basic_map *bmap,
                __isl_take isl_basic_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_pw_multi_aff *
        isl_basic_map_partial_lexmax_pw_multi_aff(
                __isl_take isl_basic_map *bmap,
                __isl_take isl_basic_set *dom,
                __isl_give isl_set **empty);
        __isl_give isl_pw_multi_aff *isl_set_lexmin_pw_multi_aff(
                __isl_take isl_set *set);
        __isl_give isl_pw_multi_aff *isl_set_lexmax_pw_multi_aff(
                __isl_take isl_set *set);
        __isl_give isl_pw_multi_aff *isl_map_lexmin_pw_multi_aff(
                __isl_take isl_map *map);
        __isl_give isl_pw_multi_aff *isl_map_lexmax_pw_multi_aff(
                __isl_take isl_map *map);

Lists

Lists are defined over several element types, including isl_val, isl_id, isl_aff, isl_pw_aff, isl_constraint, isl_basic_set, isl_set, isl_ast_expr and isl_ast_node. Here we take lists of isl_sets as an example. Lists can be created, copied, modified and freed using the following functions.

        #include <isl/list.h>
        __isl_give isl_set_list *isl_set_list_from_set(
                __isl_take isl_set *el);
        __isl_give isl_set_list *isl_set_list_alloc(
                isl_ctx *ctx, int n);
        __isl_give isl_set_list *isl_set_list_copy(
                __isl_keep isl_set_list *list);
        __isl_give isl_set_list *isl_set_list_insert(
                __isl_take isl_set_list *list, unsigned pos,
                __isl_take isl_set *el);
        __isl_give isl_set_list *isl_set_list_add(
                __isl_take isl_set_list *list,
                __isl_take isl_set *el);
        __isl_give isl_set_list *isl_set_list_drop(
                __isl_take isl_set_list *list,
                unsigned first, unsigned n);
        __isl_give isl_set_list *isl_set_list_set_set(
                __isl_take isl_set_list *list, int index,
                __isl_take isl_set *set);
        __isl_give isl_set_list *isl_set_list_concat(
                __isl_take isl_set_list *list1,
                __isl_take isl_set_list *list2);
        __isl_give isl_set_list *isl_set_list_sort(
                __isl_take isl_set_list *list,
                int (*cmp)(__isl_keep isl_set *a,
                        __isl_keep isl_set *b, void *user),
                void *user);
        void *isl_set_list_free(__isl_take isl_set_list *list);

isl_set_list_alloc creates an empty list with a capacity for n elements. isl_set_list_from_set creates a list with a single element.

Lists can be inspected using the following functions.

        #include <isl/list.h>
        isl_ctx *isl_set_list_get_ctx(__isl_keep isl_set_list *list);
        int isl_set_list_n_set(__isl_keep isl_set_list *list);
        __isl_give isl_set *isl_set_list_get_set(
                __isl_keep isl_set_list *list, int index);
        int isl_set_list_foreach(__isl_keep isl_set_list *list,
                int (*fn)(__isl_take isl_set *el, void *user),
                void *user);
        int isl_set_list_foreach_scc(__isl_keep isl_set_list *list,
                int (*follows)(__isl_keep isl_set *a,
                        __isl_keep isl_set *b, void *user),
                void *follows_user
                int (*fn)(__isl_take isl_set *el, void *user),
                void *fn_user);

The function isl_set_list_foreach_scc calls fn on each of the strongly connected components of the graph with as vertices the elements of list and a directed edge from vertex b to vertex a iff follows(a, b) returns 1. The callbacks follows and fn should return -1 on error.

Lists can be printed using

        #include <isl/list.h>
        __isl_give isl_printer *isl_printer_print_set_list(
                __isl_take isl_printer *p,
                __isl_keep isl_set_list *list);

Associative arrays

Associative arrays map isl objects of a specific type to isl objects of some (other) specific type. They are defined for several pairs of types, including (isl_map, isl_basic_set), (isl_id, isl_ast_expr) and. (isl_id, isl_pw_aff). Here, we take associative arrays that map isl_ids to isl_ast_exprs as an example.

Associative arrays can be created, copied and freed using the following functions.

        #include <isl/id_to_ast_expr.h>
        __isl_give id_to_ast_expr *isl_id_to_ast_expr_alloc(
                isl_ctx *ctx, int min_size);
        __isl_give id_to_ast_expr *isl_id_to_ast_expr_copy(
                __isl_keep id_to_ast_expr *id2expr);
        void *isl_id_to_ast_expr_free(
                __isl_take id_to_ast_expr *id2expr);

The min_size argument to isl_id_to_ast_expr_alloc can be used to specify the expected size of the associative array. The associative array will be grown automatically as needed.

Associative arrays can be inspected using the following functions.

        #include <isl/id_to_ast_expr.h>
        isl_ctx *isl_id_to_ast_expr_get_ctx(
                __isl_keep id_to_ast_expr *id2expr);
        int isl_id_to_ast_expr_has(
                __isl_keep id_to_ast_expr *id2expr,
                __isl_keep isl_id *key);
        __isl_give isl_ast_expr *isl_id_to_ast_expr_get(
                __isl_keep id_to_ast_expr *id2expr,
                __isl_take isl_id *key);
        int isl_id_to_ast_expr_foreach(
                __isl_keep id_to_ast_expr *id2expr,
                int (*fn)(__isl_take isl_id *key,
                        __isl_take isl_ast_expr *val, void *user),
                void *user);

They can be modified using the following function.

        #include <isl/id_to_ast_expr.h>
        __isl_give id_to_ast_expr *isl_id_to_ast_expr_set(
                __isl_take id_to_ast_expr *id2expr,
                __isl_take isl_id *key,
                __isl_take isl_ast_expr *val);

Associative arrays can be printed using the following function.

        #include <isl/id_to_ast_expr.h>
        __isl_give isl_printer *isl_printer_print_id_to_ast_expr(
                __isl_take isl_printer *p,
                __isl_keep id_to_ast_expr *id2expr);

Multiple Values

An isl_multi_val object represents a sequence of zero or more values, living in a set space.

An isl_multi_val can be constructed from an isl_val_list using the following function

        #include <isl/val.h>
        __isl_give isl_multi_val *isl_multi_val_from_val_list(
                __isl_take isl_space *space,
                __isl_take isl_val_list *list);

The zero multiple value (with value zero for each set dimension) can be created using the following function.

        #include <isl/val.h>
        __isl_give isl_multi_val *isl_multi_val_zero(
                __isl_take isl_space *space);

Multiple values can be copied and freed using

        #include <isl/val.h>
        __isl_give isl_multi_val *isl_multi_val_copy(
                __isl_keep isl_multi_val *mv);
        void *isl_multi_val_free(__isl_take isl_multi_val *mv);

They can be inspected using

        #include <isl/val.h>
        isl_ctx *isl_multi_val_get_ctx(
                __isl_keep isl_multi_val *mv);
        unsigned isl_multi_val_dim(__isl_keep isl_multi_val *mv,
                enum isl_dim_type type);
        __isl_give isl_val *isl_multi_val_get_val(
                __isl_keep isl_multi_val *mv, int pos);
        int isl_multi_val_find_dim_by_id(
                __isl_keep isl_multi_val *mv,
                enum isl_dim_type type, __isl_keep isl_id *id);
        __isl_give isl_id *isl_multi_val_get_dim_id(
                __isl_keep isl_multi_val *mv,
                enum isl_dim_type type, unsigned pos);
        const char *isl_multi_val_get_tuple_name(
                __isl_keep isl_multi_val *mv,
                enum isl_dim_type type);
        int isl_multi_val_has_tuple_id(__isl_keep isl_multi_val *mv,
                enum isl_dim_type type);
        __isl_give isl_id *isl_multi_val_get_tuple_id(
                __isl_keep isl_multi_val *mv,
                enum isl_dim_type type);
        __isl_give isl_multi_val *isl_multi_val_reset_tuple_id(
                __isl_take isl_multi_val *mv,
                enum isl_dim_type type);

They can be modified using

        #include <isl/val.h>
        __isl_give isl_multi_val *isl_multi_val_set_val(
                __isl_take isl_multi_val *mv, int pos,
                __isl_take isl_val *val);
        __isl_give isl_multi_val *isl_multi_val_set_dim_name(
                __isl_take isl_multi_val *mv,
                enum isl_dim_type type, unsigned pos, const char *s);
        __isl_give isl_multi_val *isl_multi_val_set_dim_id(
                __isl_take isl_multi_val *mv,
                enum isl_dim_type type, unsigned pos,
                __isl_take isl_id *id);
        __isl_give isl_multi_val *isl_multi_val_set_tuple_name(
                __isl_take isl_multi_val *mv,
                enum isl_dim_type type, const char *s);
        __isl_give isl_multi_val *isl_multi_val_set_tuple_id(
                __isl_take isl_multi_val *mv,
                enum isl_dim_type type, __isl_take isl_id *id);
        __isl_give isl_multi_val *isl_multi_val_insert_dims(
                __isl_take isl_multi_val *mv,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_multi_val *isl_multi_val_add_dims(
                __isl_take isl_multi_val *mv,
                enum isl_dim_type type, unsigned n);
        __isl_give isl_multi_val *isl_multi_val_drop_dims(
                __isl_take isl_multi_val *mv,
                enum isl_dim_type type, unsigned first, unsigned n);

Operations include

        #include <isl/val.h>
        __isl_give isl_multi_val *isl_multi_val_align_params(
                __isl_take isl_multi_val *mv,
                __isl_take isl_space *model);
        __isl_give isl_multi_val *isl_multi_val_from_range(
                __isl_take isl_multi_val *mv);
        __isl_give isl_multi_val *isl_multi_val_range_splice(
                __isl_take isl_multi_val *mv1, unsigned pos,
                __isl_take isl_multi_val *mv2);
        __isl_give isl_multi_val *isl_multi_val_range_product(
                __isl_take isl_multi_val *mv1,
                __isl_take isl_multi_val *mv2);
        __isl_give isl_multi_val *isl_multi_val_flat_range_product(
                __isl_take isl_multi_val *mv1,
                __isl_take isl_multi_aff *mv2);
        __isl_give isl_multi_val *isl_multi_val_product(
                __isl_take isl_multi_val *mv1,
                __isl_take isl_multi_val *mv2);
        __isl_give isl_multi_val *isl_multi_val_add_val(
                __isl_take isl_multi_val *mv,
                __isl_take isl_val *v);
        __isl_give isl_multi_val *isl_multi_val_mod_val(
                __isl_take isl_multi_val *mv,
                __isl_take isl_val *v);
        __isl_give isl_multi_val *isl_multi_val_scale_val(
                __isl_take isl_multi_val *mv,
                __isl_take isl_val *v);
        __isl_give isl_multi_val *isl_multi_val_scale_multi_val(
                __isl_take isl_multi_val *mv1,
                __isl_take isl_multi_val *mv2);
        __isl_give isl_multi_val *
        isl_multi_val_scale_down_multi_val(
                __isl_take isl_multi_val *mv1,
                __isl_take isl_multi_val *mv2);

A multiple value can be printed using

        __isl_give isl_printer *isl_printer_print_multi_val(
                __isl_take isl_printer *p,
                __isl_keep isl_multi_val *mv);

Vectors

Vectors can be created, copied and freed using the following functions.

        #include <isl/vec.h>
        __isl_give isl_vec *isl_vec_alloc(isl_ctx *ctx,
                unsigned size);
        __isl_give isl_vec *isl_vec_copy(__isl_keep isl_vec *vec);
        void *isl_vec_free(__isl_take isl_vec *vec);

Note that the elements of a newly created vector may have arbitrary values. The elements can be changed and inspected using the following functions.

        isl_ctx *isl_vec_get_ctx(__isl_keep isl_vec *vec);
        int isl_vec_size(__isl_keep isl_vec *vec);
        __isl_give isl_val *isl_vec_get_element_val(
                __isl_keep isl_vec *vec, int pos);
        __isl_give isl_vec *isl_vec_set_element_si(
                __isl_take isl_vec *vec, int pos, int v);
        __isl_give isl_vec *isl_vec_set_element_val(
                __isl_take isl_vec *vec, int pos,
                __isl_take isl_val *v);
        __isl_give isl_vec *isl_vec_set_si(__isl_take isl_vec *vec,
                int v);
        __isl_give isl_vec *isl_vec_set_val(
                __isl_take isl_vec *vec, __isl_take isl_val *v);
        int isl_vec_cmp_element(__isl_keep isl_vec *vec1,
                __isl_keep isl_vec *vec2, int pos);

isl_vec_get_element will return a negative value if anything went wrong. In that case, the value of *v is undefined.

The following function can be used to concatenate two vectors.

        __isl_give isl_vec *isl_vec_concat(__isl_take isl_vec *vec1,
                __isl_take isl_vec *vec2);

Matrices

Matrices can be created, copied and freed using the following functions.

        #include <isl/mat.h>
        __isl_give isl_mat *isl_mat_alloc(isl_ctx *ctx,
                unsigned n_row, unsigned n_col);
        __isl_give isl_mat *isl_mat_copy(__isl_keep isl_mat *mat);
        void *isl_mat_free(__isl_take isl_mat *mat);

Note that the elements of a newly created matrix may have arbitrary values. The elements can be changed and inspected using the following functions.

        isl_ctx *isl_mat_get_ctx(__isl_keep isl_mat *mat);
        int isl_mat_rows(__isl_keep isl_mat *mat);
        int isl_mat_cols(__isl_keep isl_mat *mat);
        __isl_give isl_val *isl_mat_get_element_val(
                __isl_keep isl_mat *mat, int row, int col);
        __isl_give isl_mat *isl_mat_set_element_si(__isl_take isl_mat *mat,
                int row, int col, int v);
        __isl_give isl_mat *isl_mat_set_element_val(
                __isl_take isl_mat *mat, int row, int col,
                __isl_take isl_val *v);

isl_mat_get_element will return a negative value if anything went wrong. In that case, the value of *v is undefined.

The following function can be used to compute the (right) inverse of a matrix, i.e., a matrix such that the product of the original and the inverse (in that order) is a multiple of the identity matrix. The input matrix is assumed to be of full row-rank.

        __isl_give isl_mat *isl_mat_right_inverse(__isl_take isl_mat *mat);

The following function can be used to compute the (right) kernel (or null space) of a matrix, i.e., a matrix such that the product of the original and the kernel (in that order) is the zero matrix.

        __isl_give isl_mat *isl_mat_right_kernel(__isl_take isl_mat *mat);

Piecewise Quasi Affine Expressions

The zero quasi affine expression or the quasi affine expression that is equal to a given value or a specified dimension on a given domain can be created using

        __isl_give isl_aff *isl_aff_zero_on_domain(
                __isl_take isl_local_space *ls);
        __isl_give isl_pw_aff *isl_pw_aff_zero_on_domain(
                __isl_take isl_local_space *ls);
        __isl_give isl_aff *isl_aff_val_on_domain(
                __isl_take isl_local_space *ls,
                __isl_take isl_val *val);
        __isl_give isl_aff *isl_aff_var_on_domain(
                __isl_take isl_local_space *ls,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_pw_aff *isl_pw_aff_var_on_domain(
                __isl_take isl_local_space *ls,
                enum isl_dim_type type, unsigned pos);

Note that the space in which the resulting objects live is a map space with the given space as domain and a one-dimensional range.

An empty piecewise quasi affine expression (one with no cells) or a piecewise quasi affine expression with a single cell can be created using the following functions.

        #include <isl/aff.h>
        __isl_give isl_pw_aff *isl_pw_aff_empty(
                __isl_take isl_space *space);
        __isl_give isl_pw_aff *isl_pw_aff_alloc(
                __isl_take isl_set *set, __isl_take isl_aff *aff);
        __isl_give isl_pw_aff *isl_pw_aff_from_aff(
                __isl_take isl_aff *aff);

A piecewise quasi affine expression that is equal to 1 on a set and 0 outside the set can be created using the following function.

        #include <isl/aff.h>
        __isl_give isl_pw_aff *isl_set_indicator_function(
                __isl_take isl_set *set);

Quasi affine expressions can be copied and freed using

        #include <isl/aff.h>
        __isl_give isl_aff *isl_aff_copy(__isl_keep isl_aff *aff);
        void *isl_aff_free(__isl_take isl_aff *aff);
        __isl_give isl_pw_aff *isl_pw_aff_copy(
                __isl_keep isl_pw_aff *pwaff);
        void *isl_pw_aff_free(__isl_take isl_pw_aff *pwaff);

A (rational) bound on a dimension can be extracted from an isl_constraint using the following function. The constraint is required to have a non-zero coefficient for the specified dimension.

        #include <isl/constraint.h>
        __isl_give isl_aff *isl_constraint_get_bound(
                __isl_keep isl_constraint *constraint,
                enum isl_dim_type type, int pos);

The entire affine expression of the constraint can also be extracted using the following function.

        #include <isl/constraint.h>
        __isl_give isl_aff *isl_constraint_get_aff(
                __isl_keep isl_constraint *constraint);

Conversely, an equality constraint equating the affine expression to zero or an inequality constraint enforcing the affine expression to be non-negative, can be constructed using

        __isl_give isl_constraint *isl_equality_from_aff(
                __isl_take isl_aff *aff);
        __isl_give isl_constraint *isl_inequality_from_aff(
                __isl_take isl_aff *aff);

The expression can be inspected using

        #include <isl/aff.h>
        isl_ctx *isl_aff_get_ctx(__isl_keep isl_aff *aff);
        int isl_aff_dim(__isl_keep isl_aff *aff,
                enum isl_dim_type type);
        __isl_give isl_local_space *isl_aff_get_domain_local_space(
                __isl_keep isl_aff *aff);
        __isl_give isl_local_space *isl_aff_get_local_space(
                __isl_keep isl_aff *aff);
        const char *isl_aff_get_dim_name(__isl_keep isl_aff *aff,
                enum isl_dim_type type, unsigned pos);
        const char *isl_pw_aff_get_dim_name(
                __isl_keep isl_pw_aff *pa,
                enum isl_dim_type type, unsigned pos);
        int isl_pw_aff_has_dim_id(__isl_keep isl_pw_aff *pa,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_id *isl_pw_aff_get_dim_id(
                __isl_keep isl_pw_aff *pa,
                enum isl_dim_type type, unsigned pos);
        int isl_pw_aff_has_tuple_id(__isl_keep isl_pw_aff *pa,
                enum isl_dim_type type);
        __isl_give isl_id *isl_pw_aff_get_tuple_id(
                __isl_keep isl_pw_aff *pa,
                enum isl_dim_type type);
        __isl_give isl_val *isl_aff_get_constant_val(
                __isl_keep isl_aff *aff);
        __isl_give isl_val *isl_aff_get_coefficient_val(
                __isl_keep isl_aff *aff,
                enum isl_dim_type type, int pos);
        __isl_give isl_val *isl_aff_get_denominator_val(
                __isl_keep isl_aff *aff);
        __isl_give isl_aff *isl_aff_get_div(
                __isl_keep isl_aff *aff, int pos);
        int isl_pw_aff_n_piece(__isl_keep isl_pw_aff *pwaff);
        int isl_pw_aff_foreach_piece(__isl_keep isl_pw_aff *pwaff,
                int (*fn)(__isl_take isl_set *set,
                          __isl_take isl_aff *aff,
                          void *user), void *user);
        int isl_aff_is_cst(__isl_keep isl_aff *aff);
        int isl_pw_aff_is_cst(__isl_keep isl_pw_aff *pwaff);
        int isl_aff_involves_dims(__isl_keep isl_aff *aff,
                enum isl_dim_type type, unsigned first, unsigned n);
        int isl_pw_aff_involves_dims(__isl_keep isl_pw_aff *pwaff,
                enum isl_dim_type type, unsigned first, unsigned n);
        isl_ctx *isl_pw_aff_get_ctx(__isl_keep isl_pw_aff *pwaff);
        unsigned isl_pw_aff_dim(__isl_keep isl_pw_aff *pwaff,
                enum isl_dim_type type);
        int isl_pw_aff_is_empty(__isl_keep isl_pw_aff *pwaff);

It can be modified using

        #include <isl/aff.h>
        __isl_give isl_pw_aff *isl_pw_aff_set_tuple_id(
                __isl_take isl_pw_aff *pwaff,
                enum isl_dim_type type, __isl_take isl_id *id);
        __isl_give isl_aff *isl_aff_set_dim_name(
                __isl_take isl_aff *aff, enum isl_dim_type type,
                unsigned pos, const char *s);
        __isl_give isl_aff *isl_aff_set_dim_id(
                __isl_take isl_aff *aff, enum isl_dim_type type,
                unsigned pos, __isl_take isl_id *id);
        __isl_give isl_pw_aff *isl_pw_aff_set_dim_id(
                __isl_take isl_pw_aff *pma,
                enum isl_dim_type type, unsigned pos,
                __isl_take isl_id *id);
        __isl_give isl_aff *isl_aff_set_constant_si(
                __isl_take isl_aff *aff, int v);
        __isl_give isl_aff *isl_aff_set_constant_val(
                __isl_take isl_aff *aff, __isl_take isl_val *v);
        __isl_give isl_aff *isl_aff_set_coefficient_si(
                __isl_take isl_aff *aff,
                enum isl_dim_type type, int pos, int v);
        __isl_give isl_aff *isl_aff_set_coefficient_val(
                __isl_take isl_aff *aff,
                enum isl_dim_type type, int pos,
                __isl_take isl_val *v);
        __isl_give isl_aff *isl_aff_add_constant_si(
                __isl_take isl_aff *aff, int v);
        __isl_give isl_aff *isl_aff_add_constant_val(
                __isl_take isl_aff *aff, __isl_take isl_val *v);
        __isl_give isl_aff *isl_aff_add_constant_num_si(
                __isl_take isl_aff *aff, int v);
        __isl_give isl_aff *isl_aff_add_coefficient_si(
                __isl_take isl_aff *aff,
                enum isl_dim_type type, int pos, int v);
        __isl_give isl_aff *isl_aff_add_coefficient_val(
                __isl_take isl_aff *aff,
                enum isl_dim_type type, int pos,
                __isl_take isl_val *v);
        __isl_give isl_aff *isl_aff_insert_dims(
                __isl_take isl_aff *aff,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_pw_aff *isl_pw_aff_insert_dims(
                __isl_take isl_pw_aff *pwaff,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_aff *isl_aff_add_dims(
                __isl_take isl_aff *aff,
                enum isl_dim_type type, unsigned n);
        __isl_give isl_pw_aff *isl_pw_aff_add_dims(
                __isl_take isl_pw_aff *pwaff,
                enum isl_dim_type type, unsigned n);
        __isl_give isl_aff *isl_aff_drop_dims(
                __isl_take isl_aff *aff,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_pw_aff *isl_pw_aff_drop_dims(
                __isl_take isl_pw_aff *pwaff,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_aff *isl_aff_move_dims(
                __isl_take isl_aff *aff,
                enum isl_dim_type dst_type, unsigned dst_pos,
                enum isl_dim_type src_type, unsigned src_pos,
                unsigned n);
        __isl_give isl_pw_aff *isl_pw_aff_move_dims(
                __isl_take isl_pw_aff *pa,
                enum isl_dim_type dst_type, unsigned dst_pos,
                enum isl_dim_type src_type, unsigned src_pos,
                unsigned n);

Note that isl_aff_set_constant_si and isl_aff_set_coefficient_si set the numerator of the constant or coefficient, while isl_aff_set_constant_val and isl_aff_set_coefficient_val set the constant or coefficient as a whole. The add_constant and add_coefficient functions add an integer or rational value to the possibly rational constant or coefficient. The add_constant_num functions add an integer value to the numerator.

To check whether an affine expressions is obviously zero or (obviously) equal to some other affine expression, use

        #include <isl/aff.h>
        int isl_aff_plain_is_zero(__isl_keep isl_aff *aff);
        int isl_aff_plain_is_equal(__isl_keep isl_aff *aff1,
                __isl_keep isl_aff *aff2);
        int isl_pw_aff_plain_is_equal(
                __isl_keep isl_pw_aff *pwaff1,
                __isl_keep isl_pw_aff *pwaff2);
        int isl_pw_aff_is_equal(__isl_keep isl_pw_aff *pa1,
                __isl_keep isl_pw_aff *pa2);

Operations include

        #include <isl/aff.h>
        __isl_give isl_aff *isl_aff_add(__isl_take isl_aff *aff1,
                __isl_take isl_aff *aff2);
        __isl_give isl_pw_aff *isl_pw_aff_add(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_pw_aff *isl_pw_aff_min(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_pw_aff *isl_pw_aff_max(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_aff *isl_aff_sub(__isl_take isl_aff *aff1,
                __isl_take isl_aff *aff2);
        __isl_give isl_pw_aff *isl_pw_aff_sub(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_aff *isl_aff_neg(__isl_take isl_aff *aff);
        __isl_give isl_pw_aff *isl_pw_aff_neg(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_aff *isl_aff_ceil(__isl_take isl_aff *aff);
        __isl_give isl_pw_aff *isl_pw_aff_ceil(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_aff *isl_aff_floor(__isl_take isl_aff *aff);
        __isl_give isl_pw_aff *isl_pw_aff_floor(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_aff *isl_aff_mod_val(__isl_take isl_aff *aff,
                __isl_take isl_val *mod);
        __isl_give isl_pw_aff *isl_pw_aff_mod_val(
                __isl_take isl_pw_aff *pa,
                __isl_take isl_val *mod);
        __isl_give isl_aff *isl_aff_scale_val(__isl_take isl_aff *aff,
                __isl_take isl_val *v);
        __isl_give isl_pw_aff *isl_pw_aff_scale_val(
                __isl_take isl_pw_aff *pa, __isl_take isl_val *v);
        __isl_give isl_aff *isl_aff_scale_down_ui(
                __isl_take isl_aff *aff, unsigned f);
        __isl_give isl_aff *isl_aff_scale_down_val(
                __isl_take isl_aff *aff, __isl_take isl_val *v);
        __isl_give isl_pw_aff *isl_pw_aff_scale_down_val(
                __isl_take isl_pw_aff *pa,
                __isl_take isl_val *f);
        __isl_give isl_pw_aff *isl_pw_aff_list_min(
                __isl_take isl_pw_aff_list *list);
        __isl_give isl_pw_aff *isl_pw_aff_list_max(
                __isl_take isl_pw_aff_list *list);
        __isl_give isl_pw_aff *isl_pw_aff_coalesce(
                __isl_take isl_pw_aff *pwqp);
        __isl_give isl_aff *isl_aff_align_params(
                __isl_take isl_aff *aff,
                __isl_take isl_space *model);
        __isl_give isl_pw_aff *isl_pw_aff_align_params(
                __isl_take isl_pw_aff *pwaff,
                __isl_take isl_space *model);
        __isl_give isl_aff *isl_aff_project_domain_on_params(
                __isl_take isl_aff *aff);
        __isl_give isl_pw_aff *isl_pw_aff_from_range(
                __isl_take isl_pw_aff *pwa);
        __isl_give isl_aff *isl_aff_gist_params(
                __isl_take isl_aff *aff,
                __isl_take isl_set *context);
        __isl_give isl_aff *isl_aff_gist(__isl_take isl_aff *aff,
                __isl_take isl_set *context);
        __isl_give isl_pw_aff *isl_pw_aff_gist_params(
                __isl_take isl_pw_aff *pwaff,
                __isl_take isl_set *context);
        __isl_give isl_pw_aff *isl_pw_aff_gist(
                __isl_take isl_pw_aff *pwaff,
                __isl_take isl_set *context);
        __isl_give isl_set *isl_pw_aff_domain(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_set *isl_pw_aff_params(
                __isl_take isl_pw_aff *pwa);
        __isl_give isl_pw_aff *isl_pw_aff_intersect_domain(
                __isl_take isl_pw_aff *pa,
                __isl_take isl_set *set);
        __isl_give isl_pw_aff *isl_pw_aff_intersect_params(
                __isl_take isl_pw_aff *pa,
                __isl_take isl_set *set);
        __isl_give isl_aff *isl_aff_mul(__isl_take isl_aff *aff1,
                __isl_take isl_aff *aff2);
        __isl_give isl_aff *isl_aff_div(__isl_take isl_aff *aff1,
                __isl_take isl_aff *aff2);
        __isl_give isl_pw_aff *isl_pw_aff_mul(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_pw_aff *isl_pw_aff_div(
                __isl_take isl_pw_aff *pa1,
                __isl_take isl_pw_aff *pa2);
        __isl_give isl_pw_aff *isl_pw_aff_tdiv_q(
                __isl_take isl_pw_aff *pa1,
                __isl_take isl_pw_aff *pa2);
        __isl_give isl_pw_aff *isl_pw_aff_tdiv_r(
                __isl_take isl_pw_aff *pa1,
                __isl_take isl_pw_aff *pa2);

When multiplying two affine expressions, at least one of the two needs to be a constant. Similarly, when dividing an affine expression by another, the second expression needs to be a constant. isl_pw_aff_tdiv_q computes the quotient of an integer division with rounding towards zero. isl_pw_aff_tdiv_r computes the corresponding remainder.

        #include <isl/aff.h>
        __isl_give isl_aff *isl_aff_pullback_aff(
                __isl_take isl_aff *aff1,
                __isl_take isl_aff *aff2);
        __isl_give isl_aff *isl_aff_pullback_multi_aff(
                __isl_take isl_aff *aff,
                __isl_take isl_multi_aff *ma);
        __isl_give isl_pw_aff *isl_pw_aff_pullback_multi_aff(
                __isl_take isl_pw_aff *pa,
                __isl_take isl_multi_aff *ma);
        __isl_give isl_pw_aff *isl_pw_aff_pullback_pw_multi_aff(
                __isl_take isl_pw_aff *pa,
                __isl_take isl_pw_multi_aff *pma);

These functions precompose the input expression by the given isl_aff, isl_multi_aff or isl_pw_multi_aff. In other words, the isl_aff, isl_multi_aff or isl_pw_multi_aff is plugged into the (piecewise) affine expression. Objects of type isl_multi_aff are described in Piecewise Multiple Quasi Affine Expressions.

        #include <isl/aff.h>
        __isl_give isl_basic_set *isl_aff_zero_basic_set(
                __isl_take isl_aff *aff);
        __isl_give isl_basic_set *isl_aff_neg_basic_set(
                __isl_take isl_aff *aff);
        __isl_give isl_basic_set *isl_aff_le_basic_set(
                __isl_take isl_aff *aff1, __isl_take isl_aff *aff2);
        __isl_give isl_basic_set *isl_aff_ge_basic_set(
                __isl_take isl_aff *aff1, __isl_take isl_aff *aff2);
        __isl_give isl_set *isl_pw_aff_eq_set(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_set *isl_pw_aff_ne_set(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_set *isl_pw_aff_le_set(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_set *isl_pw_aff_lt_set(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_set *isl_pw_aff_ge_set(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_set *isl_pw_aff_gt_set(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_set *isl_pw_aff_list_eq_set(
                __isl_take isl_pw_aff_list *list1,
                __isl_take isl_pw_aff_list *list2);
        __isl_give isl_set *isl_pw_aff_list_ne_set(
                __isl_take isl_pw_aff_list *list1,
                __isl_take isl_pw_aff_list *list2);
        __isl_give isl_set *isl_pw_aff_list_le_set(
                __isl_take isl_pw_aff_list *list1,
                __isl_take isl_pw_aff_list *list2);
        __isl_give isl_set *isl_pw_aff_list_lt_set(
                __isl_take isl_pw_aff_list *list1,
                __isl_take isl_pw_aff_list *list2);
        __isl_give isl_set *isl_pw_aff_list_ge_set(
                __isl_take isl_pw_aff_list *list1,
                __isl_take isl_pw_aff_list *list2);
        __isl_give isl_set *isl_pw_aff_list_gt_set(
                __isl_take isl_pw_aff_list *list1,
                __isl_take isl_pw_aff_list *list2);

The function isl_aff_neg_basic_set returns a basic set containing those elements in the domain space of aff where aff is negative. The function isl_aff_ge_basic_set returns a basic set containing those elements in the shared space of aff1 and aff2 where aff1 is greater than or equal to aff2. The function isl_pw_aff_ge_set returns a set containing those elements in the shared domain of pwaff1 and pwaff2 where pwaff1 is greater than or equal to pwaff2. The functions operating on isl_pw_aff_list apply the corresponding isl_pw_aff function to each pair of elements in the two lists.

        #include <isl/aff.h>
        __isl_give isl_set *isl_pw_aff_nonneg_set(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_set *isl_pw_aff_zero_set(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_set *isl_pw_aff_non_zero_set(
                __isl_take isl_pw_aff *pwaff);

The function isl_pw_aff_nonneg_set returns a set containing those elements in the domain of pwaff where pwaff is non-negative.

        #include <isl/aff.h>
        __isl_give isl_pw_aff *isl_pw_aff_cond(
                __isl_take isl_pw_aff *cond,
                __isl_take isl_pw_aff *pwaff_true,
                __isl_take isl_pw_aff *pwaff_false);

The function isl_pw_aff_cond performs a conditional operator and returns an expression that is equal to pwaff_true for elements where cond is non-zero and equal to pwaff_false for elements where cond is zero.

        #include <isl/aff.h>
        __isl_give isl_pw_aff *isl_pw_aff_union_min(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_pw_aff *isl_pw_aff_union_max(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);
        __isl_give isl_pw_aff *isl_pw_aff_union_add(
                __isl_take isl_pw_aff *pwaff1,
                __isl_take isl_pw_aff *pwaff2);

The function isl_pw_aff_union_max computes a piecewise quasi-affine expression with a domain that is the union of those of pwaff1 and pwaff2 and such that on each cell, the quasi-affine expression is the maximum of those of pwaff1 and pwaff2. If only one of pwaff1 or pwaff2 is defined on a given cell, then the associated expression is the defined one.

An expression can be read from input using

        #include <isl/aff.h>
        __isl_give isl_aff *isl_aff_read_from_str(
                isl_ctx *ctx, const char *str);
        __isl_give isl_pw_aff *isl_pw_aff_read_from_str(
                isl_ctx *ctx, const char *str);

An expression can be printed using

        #include <isl/aff.h>
        __isl_give isl_printer *isl_printer_print_aff(
                __isl_take isl_printer *p, __isl_keep isl_aff *aff);
        __isl_give isl_printer *isl_printer_print_pw_aff(
                __isl_take isl_printer *p,
                __isl_keep isl_pw_aff *pwaff);

Piecewise Multiple Quasi Affine Expressions

An isl_multi_aff object represents a sequence of zero or more affine expressions, all defined on the same domain space. Similarly, an isl_multi_pw_aff object represents a sequence of zero or more piecewise affine expressions.

An isl_multi_aff can be constructed from a single isl_aff or an isl_aff_list using the following functions. Similarly for isl_multi_pw_aff and isl_pw_multi_aff.

        #include <isl/aff.h>
        __isl_give isl_multi_aff *isl_multi_aff_from_aff(
                __isl_take isl_aff *aff);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_from_multi_aff(
                __isl_take isl_multi_aff *ma);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_from_pw_aff(
                __isl_take isl_pw_aff *pa);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_from_pw_aff(
                __isl_take isl_pw_aff *pa);
        __isl_give isl_multi_aff *isl_multi_aff_from_aff_list(
                __isl_take isl_space *space,
                __isl_take isl_aff_list *list);

An isl_multi_pw_aff can be converted to an isl_pw_multi_aff using the function isl_pw_multi_aff_from_multi_pw_aff below. Note however that the domain of the result is the intersection of the domains of the input. The reverse conversion is exact.

        #include <isl/aff.h>
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_from_multi_pw_aff(
                __isl_take isl_multi_pw_aff *mpa);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_from_pw_multi_aff(
                __isl_take isl_pw_multi_aff *pma);

An empty piecewise multiple quasi affine expression (one with no cells), the zero piecewise multiple quasi affine expression (with value zero for each output dimension), a piecewise multiple quasi affine expression with a single cell (with either a universe or a specified domain) or a zero-dimensional piecewise multiple quasi affine expression on a given domain can be created using the following functions.

        #include <isl/aff.h>
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_empty(
                __isl_take isl_space *space);
        __isl_give isl_multi_aff *isl_multi_aff_zero(
                __isl_take isl_space *space);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_zero(
                __isl_take isl_space *space);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_zero(
                __isl_take isl_space *space);
        __isl_give isl_multi_aff *isl_multi_aff_identity(
                __isl_take isl_space *space);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_identity(
                __isl_take isl_space *space);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_identity(
                __isl_take isl_space *space);
        __isl_give isl_multi_aff *isl_multi_aff_domain_map(
                __isl_take isl_space *space);
        __isl_give isl_multi_aff *isl_multi_aff_range_map(
                __isl_take isl_space *space);
        __isl_give isl_multi_aff *isl_multi_aff_project_out_map(
                __isl_take isl_space *space,
                enum isl_dim_type type,
                unsigned first, unsigned n);
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_project_out_map(
                __isl_take isl_space *space,
                enum isl_dim_type type,
                unsigned first, unsigned n);
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_from_multi_aff(
                __isl_take isl_multi_aff *ma);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_alloc(
                __isl_take isl_set *set,
                __isl_take isl_multi_aff *maff);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_from_domain(
                __isl_take isl_set *set);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_empty(
                __isl_take isl_space *space);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_add_pw_multi_aff(
                __isl_take isl_union_pw_multi_aff *upma,
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_from_domain(
                __isl_take isl_union_set *uset);

A piecewise multiple quasi affine expression can also be initialized from an isl_set or isl_map, provided the isl_set is a singleton and the isl_map is single-valued. In case of a conversion from an isl_union_set or an isl_union_map to an isl_union_pw_multi_aff, these properties need to hold in each space.

        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_from_set(
                __isl_take isl_set *set);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_from_map(
                __isl_take isl_map *map);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_from_union_set(
                __isl_take isl_union_set *uset);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_from_union_map(
                __isl_take isl_union_map *umap);

Multiple quasi affine expressions can be copied and freed using

        #include <isl/aff.h>
        __isl_give isl_multi_aff *isl_multi_aff_copy(
                __isl_keep isl_multi_aff *maff);
        void *isl_multi_aff_free(__isl_take isl_multi_aff *maff);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_copy(
                __isl_keep isl_pw_multi_aff *pma);
        void *isl_pw_multi_aff_free(
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_copy(
                __isl_keep isl_union_pw_multi_aff *upma);
        void *isl_union_pw_multi_aff_free(
                __isl_take isl_union_pw_multi_aff *upma);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_copy(
                __isl_keep isl_multi_pw_aff *mpa);
        void *isl_multi_pw_aff_free(
                __isl_take isl_multi_pw_aff *mpa);

The expression can be inspected using

        #include <isl/aff.h>
        isl_ctx *isl_multi_aff_get_ctx(
                __isl_keep isl_multi_aff *maff);
        isl_ctx *isl_pw_multi_aff_get_ctx(
                __isl_keep isl_pw_multi_aff *pma);
        isl_ctx *isl_union_pw_multi_aff_get_ctx(
                __isl_keep isl_union_pw_multi_aff *upma);
        isl_ctx *isl_multi_pw_aff_get_ctx(
                __isl_keep isl_multi_pw_aff *mpa);
        unsigned isl_multi_aff_dim(__isl_keep isl_multi_aff *maff,
                enum isl_dim_type type);
        unsigned isl_pw_multi_aff_dim(
                __isl_keep isl_pw_multi_aff *pma,
                enum isl_dim_type type);
        unsigned isl_multi_pw_aff_dim(
                __isl_keep isl_multi_pw_aff *mpa,
                enum isl_dim_type type);
        __isl_give isl_aff *isl_multi_aff_get_aff(
                __isl_keep isl_multi_aff *multi, int pos);
        __isl_give isl_pw_aff *isl_pw_multi_aff_get_pw_aff(
                __isl_keep isl_pw_multi_aff *pma, int pos);
        __isl_give isl_pw_aff *isl_multi_pw_aff_get_pw_aff(
                __isl_keep isl_multi_pw_aff *mpa, int pos);
        int isl_multi_aff_find_dim_by_id(
                __isl_keep isl_multi_aff *ma,
                enum isl_dim_type type, __isl_keep isl_id *id);
        int isl_multi_pw_aff_find_dim_by_id(
                __isl_keep isl_multi_pw_aff *mpa,
                enum isl_dim_type type, __isl_keep isl_id *id);
        const char *isl_pw_multi_aff_get_dim_name(
                __isl_keep isl_pw_multi_aff *pma,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_id *isl_multi_aff_get_dim_id(
                __isl_keep isl_multi_aff *ma,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_id *isl_pw_multi_aff_get_dim_id(
                __isl_keep isl_pw_multi_aff *pma,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_id *isl_multi_pw_aff_get_dim_id(
                __isl_keep isl_multi_pw_aff *mpa,
                enum isl_dim_type type, unsigned pos);
        const char *isl_multi_aff_get_tuple_name(
                __isl_keep isl_multi_aff *multi,
                enum isl_dim_type type);
        int isl_pw_multi_aff_has_tuple_name(
                __isl_keep isl_pw_multi_aff *pma,
                enum isl_dim_type type);
        const char *isl_pw_multi_aff_get_tuple_name(
                __isl_keep isl_pw_multi_aff *pma,
                enum isl_dim_type type);
        int isl_multi_aff_has_tuple_id(__isl_keep isl_multi_aff *ma,
                enum isl_dim_type type);
        int isl_pw_multi_aff_has_tuple_id(
                __isl_keep isl_pw_multi_aff *pma,
                enum isl_dim_type type);
        int isl_multi_pw_aff_has_tuple_id(
                __isl_keep isl_multi_pw_aff *mpa,
                enum isl_dim_type type);
        __isl_give isl_id *isl_multi_aff_get_tuple_id(
                __isl_keep isl_multi_aff *ma,
                enum isl_dim_type type);
        __isl_give isl_id *isl_pw_multi_aff_get_tuple_id(
                __isl_keep isl_pw_multi_aff *pma,
                enum isl_dim_type type);
        __isl_give isl_id *isl_multi_pw_aff_get_tuple_id(
                __isl_keep isl_multi_pw_aff *mpa,
                enum isl_dim_type type);
        __isl_give isl_multi_aff *isl_multi_aff_reset_tuple_id(
                __isl_take isl_multi_aff *ma,
                enum isl_dim_type type);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_reset_tuple_id(
                __isl_take isl_multi_pw_aff *mpa,
                enum isl_dim_type type);
        int isl_pw_multi_aff_foreach_piece(
                __isl_keep isl_pw_multi_aff *pma,
                int (*fn)(__isl_take isl_set *set,
                            __isl_take isl_multi_aff *maff,
                            void *user), void *user);
        int isl_union_pw_multi_aff_foreach_pw_multi_aff(
                __isl_keep isl_union_pw_multi_aff *upma,
                int (*fn)(__isl_take isl_pw_multi_aff *pma,
                            void *user), void *user);

It can be modified using

        #include <isl/aff.h>
        __isl_give isl_multi_aff *isl_multi_aff_set_aff(
                __isl_take isl_multi_aff *multi, int pos,
                __isl_take isl_aff *aff);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_set_pw_aff(
                __isl_take isl_pw_multi_aff *pma, unsigned pos,
                __isl_take isl_pw_aff *pa);
        __isl_give isl_multi_aff *isl_multi_aff_set_dim_name(
                __isl_take isl_multi_aff *maff,
                enum isl_dim_type type, unsigned pos, const char *s);
        __isl_give isl_multi_aff *isl_multi_aff_set_dim_id(
                __isl_take isl_multi_aff *maff,
                enum isl_dim_type type, unsigned pos,
                __isl_take isl_id *id);
        __isl_give isl_multi_aff *isl_multi_aff_set_tuple_name(
                __isl_take isl_multi_aff *maff,
                enum isl_dim_type type, const char *s);
        __isl_give isl_multi_aff *isl_multi_aff_set_tuple_id(
                __isl_take isl_multi_aff *maff,
                enum isl_dim_type type, __isl_take isl_id *id);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_set_tuple_id(
                __isl_take isl_pw_multi_aff *pma,
                enum isl_dim_type type, __isl_take isl_id *id);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_set_dim_name(
                __isl_take isl_multi_pw_aff *mpa,
                enum isl_dim_type type, unsigned pos, const char *s);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_set_dim_id(
                __isl_take isl_multi_pw_aff *mpa,
                enum isl_dim_type type, unsigned pos,
                __isl_take isl_id *id);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_set_tuple_name(
                __isl_take isl_multi_pw_aff *mpa,
                enum isl_dim_type type, const char *s);
        __isl_give isl_multi_aff *isl_multi_aff_insert_dims(
                __isl_take isl_multi_aff *ma,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_multi_aff *isl_multi_aff_add_dims(
                __isl_take isl_multi_aff *ma,
                enum isl_dim_type type, unsigned n);
        __isl_give isl_multi_aff *isl_multi_aff_drop_dims(
                __isl_take isl_multi_aff *maff,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_drop_dims(
                __isl_take isl_pw_multi_aff *pma,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_insert_dims(
                __isl_take isl_multi_pw_aff *mpa,
                enum isl_dim_type type, unsigned first, unsigned n);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_add_dims(
                __isl_take isl_multi_pw_aff *mpa,
                enum isl_dim_type type, unsigned n);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_move_dims(
                __isl_take isl_multi_pw_aff *pma,
                enum isl_dim_type dst_type, unsigned dst_pos,
                enum isl_dim_type src_type, unsigned src_pos,
                unsigned n);

To check whether two multiple affine expressions are (obviously) equal to each other, use

        int isl_multi_aff_plain_is_equal(__isl_keep isl_multi_aff *maff1,
                __isl_keep isl_multi_aff *maff2);
        int isl_pw_multi_aff_plain_is_equal(
                __isl_keep isl_pw_multi_aff *pma1,
                __isl_keep isl_pw_multi_aff *pma2);
        int isl_multi_pw_aff_plain_is_equal(
                __isl_keep isl_multi_pw_aff *mpa1,
                __isl_keep isl_multi_pw_aff *mpa2);
        int isl_multi_pw_aff_is_equal(
                __isl_keep isl_multi_pw_aff *mpa1,
                __isl_keep isl_multi_pw_aff *mpa2);

Operations include

        #include <isl/aff.h>
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_union_lexmin(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_union_lexmax(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_multi_aff *isl_multi_aff_add(
                __isl_take isl_multi_aff *maff1,
                __isl_take isl_multi_aff *maff2);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_add(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_union_pw_multi_aff *isl_union_pw_multi_aff_add(
                __isl_take isl_union_pw_multi_aff *upma1,
                __isl_take isl_union_pw_multi_aff *upma2);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_union_add(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_multi_aff *isl_multi_aff_sub(
                __isl_take isl_multi_aff *ma1,
                __isl_take isl_multi_aff *ma2);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_sub(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_union_pw_multi_aff *isl_union_pw_multi_aff_sub(
                __isl_take isl_union_pw_multi_aff *upma1,
                __isl_take isl_union_pw_multi_aff *upma2);

isl_multi_aff_sub subtracts the second argument from the first.

        __isl_give isl_multi_aff *isl_multi_aff_scale_val(
                __isl_take isl_multi_aff *ma,
                __isl_take isl_val *v);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_scale_val(
                __isl_take isl_pw_multi_aff *pma,
                __isl_take isl_val *v);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_scale_val(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_val *v);
        __isl_give isl_multi_aff *isl_multi_aff_scale_multi_val(
                __isl_take isl_multi_aff *ma,
                __isl_take isl_multi_val *mv);
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_scale_multi_val(
                __isl_take isl_pw_multi_aff *pma,
                __isl_take isl_multi_val *mv);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_scale_multi_val(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_multi_val *mv);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_scale_multi_val(
                __isl_take isl_union_pw_multi_aff *upma,
                __isl_take isl_multi_val *mv);
        __isl_give isl_multi_aff *
        isl_multi_aff_scale_down_multi_val(
                __isl_take isl_multi_aff *ma,
                __isl_take isl_multi_val *mv);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_scale_down_multi_val(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_multi_val *mv);

isl_multi_aff_scale_multi_val scales the elements of ma by the corresponding elements of mv.

        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_fix_si(
                __isl_take isl_pw_multi_aff *pma,
                enum isl_dim_type type, unsigned pos, int value);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_intersect_params(
                __isl_take isl_pw_multi_aff *pma,
                __isl_take isl_set *set);
        __isl_give isl_set *isl_multi_pw_aff_domain(
                __isl_take isl_multi_pw_aff *mpa);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_intersect_params(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_set *set);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_intersect_domain(
                __isl_take isl_pw_multi_aff *pma,
                __isl_take isl_set *set);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_intersect_domain(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_set *domain);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_intersect_domain(
                __isl_take isl_union_pw_multi_aff *upma,
                __isl_take isl_union_set *uset);
        __isl_give isl_multi_aff *isl_multi_aff_lift(
                __isl_take isl_multi_aff *maff,
                __isl_give isl_local_space **ls);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_coalesce(
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_coalesce(
                __isl_take isl_multi_pw_aff *mpa);
        __isl_give isl_multi_aff *isl_multi_aff_align_params(
                __isl_take isl_multi_aff *multi,
                __isl_take isl_space *model);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_align_params(
                __isl_take isl_pw_multi_aff *pma,
                __isl_take isl_space *model);
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_project_domain_on_params(
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_multi_aff *isl_multi_aff_gist_params(
                __isl_take isl_multi_aff *maff,
                __isl_take isl_set *context);
        __isl_give isl_multi_aff *isl_multi_aff_gist(
                __isl_take isl_multi_aff *maff,
                __isl_take isl_set *context);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_gist_params(
                __isl_take isl_pw_multi_aff *pma,
                __isl_take isl_set *set);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_gist(
                __isl_take isl_pw_multi_aff *pma,
                __isl_take isl_set *set);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_gist_params(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_set *set);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_gist(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_set *set);
        __isl_give isl_multi_aff *isl_multi_aff_from_range(
                __isl_take isl_multi_aff *ma);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_from_range(
                __isl_take isl_multi_pw_aff *mpa);
        __isl_give isl_set *isl_pw_multi_aff_domain(
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_union_set *isl_union_pw_multi_aff_domain(
                __isl_take isl_union_pw_multi_aff *upma);
        __isl_give isl_multi_aff *isl_multi_aff_range_splice(
                __isl_take isl_multi_aff *ma1, unsigned pos,
                __isl_take isl_multi_aff *ma2);
        __isl_give isl_multi_aff *isl_multi_aff_splice(
                __isl_take isl_multi_aff *ma1,
                unsigned in_pos, unsigned out_pos,
                __isl_take isl_multi_aff *ma2);
        __isl_give isl_multi_aff *isl_multi_aff_range_product(
                __isl_take isl_multi_aff *ma1,
                __isl_take isl_multi_aff *ma2);
        __isl_give isl_multi_aff *isl_multi_aff_flat_range_product(
                __isl_take isl_multi_aff *ma1,
                __isl_take isl_multi_aff *ma2);
        __isl_give isl_multi_aff *isl_multi_aff_product(
                __isl_take isl_multi_aff *ma1,
                __isl_take isl_multi_aff *ma2);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_product(
                __isl_take isl_multi_pw_aff *mpa1,
                __isl_take isl_multi_pw_aff *mpa2);
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_range_product(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_flat_range_product(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_product(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_flat_range_product(
                __isl_take isl_union_pw_multi_aff *upma1,
                __isl_take isl_union_pw_multi_aff *upma2);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_range_splice(
                __isl_take isl_multi_pw_aff *mpa1, unsigned pos,
                __isl_take isl_multi_pw_aff *mpa2);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_splice(
                __isl_take isl_multi_pw_aff *mpa1,
                unsigned in_pos, unsigned out_pos,
                __isl_take isl_multi_pw_aff *mpa2);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_range_product(
                __isl_take isl_multi_pw_aff *mpa1,
                __isl_take isl_multi_pw_aff *mpa2);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_flat_range_product(
                __isl_take isl_multi_pw_aff *mpa1,
                __isl_take isl_multi_pw_aff *mpa2);

If the ls argument of isl_multi_aff_lift is not NULL, then it is assigned the local space that lies at the basis of the lifting applied.

        #include <isl/aff.h>
        __isl_give isl_multi_aff *isl_multi_aff_pullback_multi_aff(
                __isl_take isl_multi_aff *ma1,
                __isl_take isl_multi_aff *ma2);
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_pullback_multi_aff(
                __isl_take isl_pw_multi_aff *pma,
                __isl_take isl_multi_aff *ma);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_pullback_multi_aff(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_multi_aff *ma);
        __isl_give isl_pw_multi_aff *
        isl_pw_multi_aff_pullback_pw_multi_aff(
                __isl_take isl_pw_multi_aff *pma1,
                __isl_take isl_pw_multi_aff *pma2);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_pullback_pw_multi_aff(
                __isl_take isl_multi_pw_aff *mpa,
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_multi_pw_aff *
        isl_multi_pw_aff_pullback_multi_pw_aff(
                __isl_take isl_multi_pw_aff *mpa1,
                __isl_take isl_multi_pw_aff *mpa2);

The function isl_multi_aff_pullback_multi_aff precomposes ma1 by ma2. In other words, ma2 is plugged into ma1.

        __isl_give isl_set *isl_multi_aff_lex_le_set(
                __isl_take isl_multi_aff *ma1,
                __isl_take isl_multi_aff *ma2);
        __isl_give isl_set *isl_multi_aff_lex_ge_set(
                __isl_take isl_multi_aff *ma1,
                __isl_take isl_multi_aff *ma2);

The function isl_multi_aff_lex_le_set returns a set containing those elements in the shared domain space where ma1 is lexicographically smaller than or equal to ma2.

An expression can be read from input using

        #include <isl/aff.h>
        __isl_give isl_multi_aff *isl_multi_aff_read_from_str(
                isl_ctx *ctx, const char *str);
        __isl_give isl_pw_multi_aff *isl_pw_multi_aff_read_from_str(
                isl_ctx *ctx, const char *str);
        __isl_give isl_multi_pw_aff *isl_multi_pw_aff_read_from_str(
                isl_ctx *ctx, const char *str);
        __isl_give isl_union_pw_multi_aff *
        isl_union_pw_multi_aff_read_from_str(
                isl_ctx *ctx, const char *str);

An expression can be printed using

        #include <isl/aff.h>
        __isl_give isl_printer *isl_printer_print_multi_aff(
                __isl_take isl_printer *p,
                __isl_keep isl_multi_aff *maff);
        __isl_give isl_printer *isl_printer_print_pw_multi_aff(
                __isl_take isl_printer *p,
                __isl_keep isl_pw_multi_aff *pma);
        __isl_give isl_printer *isl_printer_print_union_pw_multi_aff(
                __isl_take isl_printer *p,
                __isl_keep isl_union_pw_multi_aff *upma);
        __isl_give isl_printer *isl_printer_print_multi_pw_aff(
                __isl_take isl_printer *p,
                __isl_keep isl_multi_pw_aff *mpa);

Points

Points are elements of a set. They can be used to construct simple sets (boxes) or they can be used to represent the individual elements of a set. The zero point (the origin) can be created using

        __isl_give isl_point *isl_point_zero(__isl_take isl_space *space);

The coordinates of a point can be inspected, set and changed using

        __isl_give isl_val *isl_point_get_coordinate_val(
                __isl_keep isl_point *pnt,
                enum isl_dim_type type, int pos);
        __isl_give isl_point *isl_point_set_coordinate_val(
                __isl_take isl_point *pnt,
                enum isl_dim_type type, int pos,
                __isl_take isl_val *v);
        __isl_give isl_point *isl_point_add_ui(
                __isl_take isl_point *pnt,
                enum isl_dim_type type, int pos, unsigned val);
        __isl_give isl_point *isl_point_sub_ui(
                __isl_take isl_point *pnt,
                enum isl_dim_type type, int pos, unsigned val);

Other properties can be obtained using

        isl_ctx *isl_point_get_ctx(__isl_keep isl_point *pnt);

Points can be copied or freed using

        __isl_give isl_point *isl_point_copy(
                __isl_keep isl_point *pnt);
        void isl_point_free(__isl_take isl_point *pnt);

A singleton set can be created from a point using

        __isl_give isl_basic_set *isl_basic_set_from_point(
                __isl_take isl_point *pnt);
        __isl_give isl_set *isl_set_from_point(
                __isl_take isl_point *pnt);

and a box can be created from two opposite extremal points using

        __isl_give isl_basic_set *isl_basic_set_box_from_points(
                __isl_take isl_point *pnt1,
                __isl_take isl_point *pnt2);
        __isl_give isl_set *isl_set_box_from_points(
                __isl_take isl_point *pnt1,
                __isl_take isl_point *pnt2);

All elements of a bounded (union) set can be enumerated using the following functions.

        int isl_set_foreach_point(__isl_keep isl_set *set,
                int (*fn)(__isl_take isl_point *pnt, void *user),
                void *user);
        int isl_union_set_foreach_point(__isl_keep isl_union_set *uset,
                int (*fn)(__isl_take isl_point *pnt, void *user),
                void *user);

The function fn is called for each integer point in set with as second argument the last argument of the isl_set_foreach_point call. The function fn should return 0 on success and -1 on failure. In the latter case, isl_set_foreach_point will stop enumerating and return -1 as well. If the enumeration is performed successfully and to completion, then isl_set_foreach_point returns 0.

To obtain a single point of a (basic) set, use

        __isl_give isl_point *isl_basic_set_sample_point(
                __isl_take isl_basic_set *bset);
        __isl_give isl_point *isl_set_sample_point(
                __isl_take isl_set *set);

If set does not contain any (integer) points, then the resulting point will be ``void'', a property that can be tested using

        int isl_point_is_void(__isl_keep isl_point *pnt);

Piecewise Quasipolynomials

A piecewise quasipolynomial is a particular kind of function that maps a parametric point to a rational value. More specifically, a quasipolynomial is a polynomial expression in greatest integer parts of affine expressions of parameters and variables. A piecewise quasipolynomial is a subdivision of a given parametric domain into disjoint cells with a quasipolynomial associated to each cell. The value of the piecewise quasipolynomial at a given point is the value of the quasipolynomial associated to the cell that contains the point. Outside of the union of cells, the value is assumed to be zero. For example, the piecewise quasipolynomial

        [n] -> { [x] -> ((1 + n) - x) : x <= n and x >= 0 }

maps x to 1 + n - x for values of x between 0 and n. A given piecewise quasipolynomial has a fixed domain dimension. Union piecewise quasipolynomials are used to contain piecewise quasipolynomials defined over different domains. Piecewise quasipolynomials are mainly used by the barvinok library for representing the number of elements in a parametric set or map. For example, the piecewise quasipolynomial above represents the number of points in the map

        [n] -> { [x] -> [y] : x,y >= 0 and 0 <= x + y <= n }

Input and Output

Piecewise quasipolynomials can be read from input using

        __isl_give isl_union_pw_qpolynomial *
        isl_union_pw_qpolynomial_read_from_str(
                isl_ctx *ctx, const char *str);

Quasipolynomials and piecewise quasipolynomials can be printed using the following functions.

        __isl_give isl_printer *isl_printer_print_qpolynomial(
                __isl_take isl_printer *p,
                __isl_keep isl_qpolynomial *qp);
        __isl_give isl_printer *isl_printer_print_pw_qpolynomial(
                __isl_take isl_printer *p,
                __isl_keep isl_pw_qpolynomial *pwqp);
        __isl_give isl_printer *isl_printer_print_union_pw_qpolynomial(
                __isl_take isl_printer *p,
                __isl_keep isl_union_pw_qpolynomial *upwqp);

The output format of the printer needs to be set to either ISL_FORMAT_ISL or ISL_FORMAT_C. For isl_printer_print_union_pw_qpolynomial, only ISL_FORMAT_ISL is supported. In case of printing in ISL_FORMAT_C, the user may want to set the names of all dimensions

        __isl_give isl_qpolynomial *isl_qpolynomial_set_dim_name(
                __isl_take isl_qpolynomial *qp,
                enum isl_dim_type type, unsigned pos,
                const char *s);
        __isl_give isl_pw_qpolynomial *
        isl_pw_qpolynomial_set_dim_name(
                __isl_take isl_pw_qpolynomial *pwqp,
                enum isl_dim_type type, unsigned pos,
                const char *s);

Creating New (Piecewise) Quasipolynomials

Some simple quasipolynomials can be created using the following functions. More complicated quasipolynomials can be created by applying operations such as addition and multiplication on the resulting quasipolynomials

        __isl_give isl_qpolynomial *isl_qpolynomial_zero_on_domain(
                __isl_take isl_space *domain);
        __isl_give isl_qpolynomial *isl_qpolynomial_one_on_domain(
                __isl_take isl_space *domain);
        __isl_give isl_qpolynomial *isl_qpolynomial_infty_on_domain(
                __isl_take isl_space *domain);
        __isl_give isl_qpolynomial *isl_qpolynomial_neginfty_on_domain(
                __isl_take isl_space *domain);
        __isl_give isl_qpolynomial *isl_qpolynomial_nan_on_domain(
                __isl_take isl_space *domain);
        __isl_give isl_qpolynomial *isl_qpolynomial_val_on_domain(
                __isl_take isl_space *domain,
                __isl_take isl_val *val);
        __isl_give isl_qpolynomial *isl_qpolynomial_var_on_domain(
                __isl_take isl_space *domain,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_qpolynomial *isl_qpolynomial_from_aff(
                __isl_take isl_aff *aff);

Note that the space in which a quasipolynomial lives is a map space with a one-dimensional range. The domain argument in some of the functions above corresponds to the domain of this map space.

The zero piecewise quasipolynomial or a piecewise quasipolynomial with a single cell can be created using the following functions. Multiple of these single cell piecewise quasipolynomials can be combined to create more complicated piecewise quasipolynomials.

        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_zero(
                __isl_take isl_space *space);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_alloc(
                __isl_take isl_set *set,
                __isl_take isl_qpolynomial *qp);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_from_qpolynomial(
                __isl_take isl_qpolynomial *qp);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_from_pw_aff(
                __isl_take isl_pw_aff *pwaff);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_zero(
                __isl_take isl_space *space);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_from_pw_qpolynomial(
                __isl_take isl_pw_qpolynomial *pwqp);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_add_pw_qpolynomial(
                __isl_take isl_union_pw_qpolynomial *upwqp,
                __isl_take isl_pw_qpolynomial *pwqp);

Quasipolynomials can be copied and freed again using the following functions.

        __isl_give isl_qpolynomial *isl_qpolynomial_copy(
                __isl_keep isl_qpolynomial *qp);
        void *isl_qpolynomial_free(__isl_take isl_qpolynomial *qp);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_copy(
                __isl_keep isl_pw_qpolynomial *pwqp);
        void *isl_pw_qpolynomial_free(
                __isl_take isl_pw_qpolynomial *pwqp);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_copy(
                __isl_keep isl_union_pw_qpolynomial *upwqp);
        void *isl_union_pw_qpolynomial_free(
                __isl_take isl_union_pw_qpolynomial *upwqp);

Inspecting (Piecewise) Quasipolynomials

To iterate over all piecewise quasipolynomials in a union piecewise quasipolynomial, use the following function

        int isl_union_pw_qpolynomial_foreach_pw_qpolynomial(
                __isl_keep isl_union_pw_qpolynomial *upwqp,
                int (*fn)(__isl_take isl_pw_qpolynomial *pwqp, void *user),
                void *user);

To extract the piecewise quasipolynomial in a given space from a union, use

        __isl_give isl_pw_qpolynomial *
        isl_union_pw_qpolynomial_extract_pw_qpolynomial(
                __isl_keep isl_union_pw_qpolynomial *upwqp,
                __isl_take isl_space *space);

To iterate over the cells in a piecewise quasipolynomial, use either of the following two functions

        int isl_pw_qpolynomial_foreach_piece(
                __isl_keep isl_pw_qpolynomial *pwqp,
                int (*fn)(__isl_take isl_set *set,
                          __isl_take isl_qpolynomial *qp,
                          void *user), void *user);
        int isl_pw_qpolynomial_foreach_lifted_piece(
                __isl_keep isl_pw_qpolynomial *pwqp,
                int (*fn)(__isl_take isl_set *set,
                          __isl_take isl_qpolynomial *qp,
                          void *user), void *user);

As usual, the function fn should return 0 on success and -1 on failure. The difference between isl_pw_qpolynomial_foreach_piece and isl_pw_qpolynomial_foreach_lifted_piece is that isl_pw_qpolynomial_foreach_lifted_piece will first compute unique representations for all existentially quantified variables and then turn these existentially quantified variables into extra set variables, adapting the associated quasipolynomial accordingly. This means that the set passed to fn will not have any existentially quantified variables, but that the dimensions of the sets may be different for different invocations of fn.

The constant term of a quasipolynomial can be extracted using

        __isl_give isl_val *isl_qpolynomial_get_constant_val(
                __isl_keep isl_qpolynomial *qp);

To iterate over all terms in a quasipolynomial, use

        int isl_qpolynomial_foreach_term(
                __isl_keep isl_qpolynomial *qp,
                int (*fn)(__isl_take isl_term *term,
                          void *user), void *user);

The terms themselves can be inspected and freed using these functions

        unsigned isl_term_dim(__isl_keep isl_term *term,
                enum isl_dim_type type);
        __isl_give isl_val *isl_term_get_coefficient_val(
                __isl_keep isl_term *term);
        int isl_term_get_exp(__isl_keep isl_term *term,
                enum isl_dim_type type, unsigned pos);
        __isl_give isl_aff *isl_term_get_div(
                __isl_keep isl_term *term, unsigned pos);
        void isl_term_free(__isl_take isl_term *term);

Each term is a product of parameters, set variables and integer divisions. The function isl_term_get_exp returns the exponent of a given dimensions in the given term.

Properties of (Piecewise) Quasipolynomials

To check whether two union piecewise quasipolynomials are obviously equal, use

        int isl_union_pw_qpolynomial_plain_is_equal(
                __isl_keep isl_union_pw_qpolynomial *upwqp1,
                __isl_keep isl_union_pw_qpolynomial *upwqp2);

Operations on (Piecewise) Quasipolynomials

        __isl_give isl_qpolynomial *isl_qpolynomial_scale_val(
                __isl_take isl_qpolynomial *qp,
                __isl_take isl_val *v);
        __isl_give isl_qpolynomial *isl_qpolynomial_neg(
                __isl_take isl_qpolynomial *qp);
        __isl_give isl_qpolynomial *isl_qpolynomial_add(
                __isl_take isl_qpolynomial *qp1,
                __isl_take isl_qpolynomial *qp2);
        __isl_give isl_qpolynomial *isl_qpolynomial_sub(
                __isl_take isl_qpolynomial *qp1,
                __isl_take isl_qpolynomial *qp2);
        __isl_give isl_qpolynomial *isl_qpolynomial_mul(
                __isl_take isl_qpolynomial *qp1,
                __isl_take isl_qpolynomial *qp2);
        __isl_give isl_qpolynomial *isl_qpolynomial_pow(
                __isl_take isl_qpolynomial *qp, unsigned exponent);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_fix_val(
                __isl_take isl_pw_qpolynomial *pwqp,
                enum isl_dim_type type, unsigned n,
                __isl_take isl_val *v);
        __isl_give isl_pw_qpolynomial *
        isl_pw_qpolynomial_scale_val(
                __isl_take isl_pw_qpolynomial *pwqp,
                __isl_take isl_val *v);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_add(
                __isl_take isl_pw_qpolynomial *pwqp1,
                __isl_take isl_pw_qpolynomial *pwqp2);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_sub(
                __isl_take isl_pw_qpolynomial *pwqp1,
                __isl_take isl_pw_qpolynomial *pwqp2);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_add_disjoint(
                __isl_take isl_pw_qpolynomial *pwqp1,
                __isl_take isl_pw_qpolynomial *pwqp2);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_neg(
                __isl_take isl_pw_qpolynomial *pwqp);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_mul(
                __isl_take isl_pw_qpolynomial *pwqp1,
                __isl_take isl_pw_qpolynomial *pwqp2);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_pow(
                __isl_take isl_pw_qpolynomial *pwqp, unsigned exponent);
        __isl_give isl_union_pw_qpolynomial *
        isl_union_pw_qpolynomial_scale_val(
                __isl_take isl_union_pw_qpolynomial *upwqp,
                __isl_take isl_val *v);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_add(
                __isl_take isl_union_pw_qpolynomial *upwqp1,
                __isl_take isl_union_pw_qpolynomial *upwqp2);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_sub(
                __isl_take isl_union_pw_qpolynomial *upwqp1,
                __isl_take isl_union_pw_qpolynomial *upwqp2);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_mul(
                __isl_take isl_union_pw_qpolynomial *upwqp1,
                __isl_take isl_union_pw_qpolynomial *upwqp2);
        __isl_give isl_val *isl_pw_qpolynomial_eval(
                __isl_take isl_pw_qpolynomial *pwqp,
                __isl_take isl_point *pnt);
        __isl_give isl_val *isl_union_pw_qpolynomial_eval(
                __isl_take isl_union_pw_qpolynomial *upwqp,
                __isl_take isl_point *pnt);
        __isl_give isl_set *isl_pw_qpolynomial_domain(
                __isl_take isl_pw_qpolynomial *pwqp);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_intersect_domain(
                __isl_take isl_pw_qpolynomial *pwpq,
                __isl_take isl_set *set);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_intersect_params(
                __isl_take isl_pw_qpolynomial *pwpq,
                __isl_take isl_set *set);
        __isl_give isl_union_set *isl_union_pw_qpolynomial_domain(
                __isl_take isl_union_pw_qpolynomial *upwqp);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_intersect_domain(
                __isl_take isl_union_pw_qpolynomial *upwpq,
                __isl_take isl_union_set *uset);
        __isl_give isl_union_pw_qpolynomial *
        isl_union_pw_qpolynomial_intersect_params(
                __isl_take isl_union_pw_qpolynomial *upwpq,
                __isl_take isl_set *set);
        __isl_give isl_qpolynomial *isl_qpolynomial_align_params(
                __isl_take isl_qpolynomial *qp,
                __isl_take isl_space *model);
        __isl_give isl_qpolynomial *isl_qpolynomial_project_domain_on_params(
                __isl_take isl_qpolynomial *qp);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_project_domain_on_params(
                __isl_take isl_pw_qpolynomial *pwqp);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_coalesce(
                __isl_take isl_union_pw_qpolynomial *upwqp);
        __isl_give isl_qpolynomial *isl_qpolynomial_gist_params(
                __isl_take isl_qpolynomial *qp,
                __isl_take isl_set *context);
        __isl_give isl_qpolynomial *isl_qpolynomial_gist(
                __isl_take isl_qpolynomial *qp,
                __isl_take isl_set *context);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_gist_params(
                __isl_take isl_pw_qpolynomial *pwqp,
                __isl_take isl_set *context);
        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_gist(
                __isl_take isl_pw_qpolynomial *pwqp,
                __isl_take isl_set *context);
        __isl_give isl_union_pw_qpolynomial *
        isl_union_pw_qpolynomial_gist_params(
                __isl_take isl_union_pw_qpolynomial *upwqp,
                __isl_take isl_set *context);
        __isl_give isl_union_pw_qpolynomial *isl_union_pw_qpolynomial_gist(
                __isl_take isl_union_pw_qpolynomial *upwqp,
                __isl_take isl_union_set *context);

The gist operation applies the gist operation to each of the cells in the domain of the input piecewise quasipolynomial. The context is also exploited to simplify the quasipolynomials associated to each cell.

        __isl_give isl_pw_qpolynomial *isl_pw_qpolynomial_to_polynomial(
                __isl_take isl_pw_qpolynomial *pwqp, int sign);
        __isl_give isl_union_pw_qpolynomial *
        isl_union_pw_qpolynomial_to_polynomial(
                __isl_take isl_union_pw_qpolynomial *upwqp, int sign);

Approximate each quasipolynomial by a polynomial. If sign is positive, the polynomial will be an overapproximation. If sign is negative, it will be an underapproximation. If sign is zero, the approximation will lie somewhere in between.

Bounds on Piecewise Quasipolynomials and Piecewise Quasipolynomial Reductions

A piecewise quasipolynomial reduction is a piecewise reduction (or fold) of quasipolynomials. In particular, the reduction can be maximum or a minimum. The objects are mainly used to represent the result of an upper or lower bound on a quasipolynomial over its domain, i.e., as the result of the following function.

        __isl_give isl_pw_qpolynomial_fold *isl_pw_qpolynomial_bound(
                __isl_take isl_pw_qpolynomial *pwqp,
                enum isl_fold type, int *tight);
        __isl_give isl_union_pw_qpolynomial_fold *isl_union_pw_qpolynomial_bound(
                __isl_take isl_union_pw_qpolynomial *upwqp,
                enum isl_fold type, int *tight);

The type argument may be either isl_fold_min or isl_fold_max. If tight is not NULL, then *tight is set to 1 is the returned bound is known be tight, i.e., for each value of the parameters there is at least one element in the domain that reaches the bound. If the domain of pwqp is not wrapping, then the bound is computed over all elements in that domain and the result has a purely parametric domain. If the domain of pwqp is wrapping, then the bound is computed over the range of the wrapped relation. The domain of the wrapped relation becomes the domain of the result.

A (piecewise) quasipolynomial reduction can be copied or freed using the following functions.

        __isl_give isl_qpolynomial_fold *isl_qpolynomial_fold_copy(
                __isl_keep isl_qpolynomial_fold *fold);
        __isl_give isl_pw_qpolynomial_fold *isl_pw_qpolynomial_fold_copy(
                __isl_keep isl_pw_qpolynomial_fold *pwf);
        __isl_give isl_union_pw_qpolynomial_fold *isl_union_pw_qpolynomial_fold_copy(
                __isl_keep isl_union_pw_qpolynomial_fold *upwf);
        void isl_qpolynomial_fold_free(
                __isl_take isl_qpolynomial_fold *fold);
        void *isl_pw_qpolynomial_fold_free(
                __isl_take isl_pw_qpolynomial_fold *pwf);
        void *isl_union_pw_qpolynomial_fold_free(
                __isl_take isl_union_pw_qpolynomial_fold *upwf);

Printing Piecewise Quasipolynomial Reductions

Piecewise quasipolynomial reductions can be printed using the following function.

        __isl_give isl_printer *isl_printer_print_pw_qpolynomial_fold(
                __isl_take isl_printer *p,
                __isl_keep isl_pw_qpolynomial_fold *pwf);
        __isl_give isl_printer *isl_printer_print_union_pw_qpolynomial_fold(
                __isl_take isl_printer *p,
                __isl_keep isl_union_pw_qpolynomial_fold *upwf);

For isl_printer_print_pw_qpolynomial_fold, output format of the printer needs to be set to either ISL_FORMAT_ISL or ISL_FORMAT_C. For isl_printer_print_union_pw_qpolynomial_fold, output format of the printer needs to be set to ISL_FORMAT_ISL. In case of printing in ISL_FORMAT_C, the user may want to set the names of all dimensions

        __isl_give isl_pw_qpolynomial_fold *
        isl_pw_qpolynomial_fold_set_dim_name(
                __isl_take isl_pw_qpolynomial_fold *pwf,
                enum isl_dim_type type, unsigned pos,
                const char *s);

Inspecting (Piecewise) Quasipolynomial Reductions

To iterate over all piecewise quasipolynomial reductions in a union piecewise quasipolynomial reduction, use the following function

        int isl_union_pw_qpolynomial_fold_foreach_pw_qpolynomial_fold(
                __isl_keep isl_union_pw_qpolynomial_fold *upwf,
                int (*fn)(__isl_take isl_pw_qpolynomial_fold *pwf,
                            void *user), void *user);

To iterate over the cells in a piecewise quasipolynomial reduction, use either of the following two functions

        int isl_pw_qpolynomial_fold_foreach_piece(
                __isl_keep isl_pw_qpolynomial_fold *pwf,
                int (*fn)(__isl_take isl_set *set,
                          __isl_take isl_qpolynomial_fold *fold,
                          void *user), void *user);
        int isl_pw_qpolynomial_fold_foreach_lifted_piece(
                __isl_keep isl_pw_qpolynomial_fold *pwf,
                int (*fn)(__isl_take isl_set *set,
                          __isl_take isl_qpolynomial_fold *fold,
                          void *user), void *user);

See Inspecting (Piecewise) Quasipolynomials for an explanation of the difference between these two functions.

To iterate over all quasipolynomials in a reduction, use

        int isl_qpolynomial_fold_foreach_qpolynomial(
                __isl_keep isl_qpolynomial_fold *fold,
                int (*fn)(__isl_take isl_qpolynomial *qp,
                          void *user), void *user);

Properties of Piecewise Quasipolynomial Reductions

To check whether two union piecewise quasipolynomial reductions are obviously equal, use

        int isl_union_pw_qpolynomial_fold_plain_is_equal(
                __isl_keep isl_union_pw_qpolynomial_fold *upwf1,
                __isl_keep isl_union_pw_qpolynomial_fold *upwf2);

Operations on Piecewise Quasipolynomial Reductions

        __isl_give isl_qpolynomial_fold *isl_qpolynomial_fold_scale_val(
                __isl_take isl_qpolynomial_fold *fold,
                __isl_take isl_val *v);
        __isl_give isl_pw_qpolynomial_fold *
        isl_pw_qpolynomial_fold_scale_val(
                __isl_take isl_pw_qpolynomial_fold *pwf,
                __isl_take isl_val *v);
        __isl_give isl_union_pw_qpolynomial_fold *
        isl_union_pw_qpolynomial_fold_scale_val(
                __isl_take isl_union_pw_qpolynomial_fold *upwf,
                __isl_take isl_val *v);
        __isl_give isl_pw_qpolynomial_fold *isl_pw_qpolynomial_fold_add(
                __isl_take isl_pw_qpolynomial_fold *pwf1,
                __isl_take isl_pw_qpolynomial_fold *pwf2);
        __isl_give isl_pw_qpolynomial_fold *isl_pw_qpolynomial_fold_fold(
                __isl_take isl_pw_qpolynomial_fold *pwf1,
                __isl_take isl_pw_qpolynomial_fold *pwf2);
        __isl_give isl_union_pw_qpolynomial_fold *isl_union_pw_qpolynomial_fold_fold(
                __isl_take isl_union_pw_qpolynomial_fold *upwf1,
                __isl_take isl_union_pw_qpolynomial_fold *upwf2);
        __isl_give isl_val *isl_pw_qpolynomial_fold_eval(
                __isl_take isl_pw_qpolynomial_fold *pwf,
                __isl_take isl_point *pnt);
        __isl_give isl_val *isl_union_pw_qpolynomial_fold_eval(
                __isl_take isl_union_pw_qpolynomial_fold *upwf,
                __isl_take isl_point *pnt);
        __isl_give isl_pw_qpolynomial_fold *
        isl_pw_qpolynomial_fold_intersect_params(
                __isl_take isl_pw_qpolynomial_fold *pwf,
                __isl_take isl_set *set);
        __isl_give isl_union_set *isl_union_pw_qpolynomial_fold_domain(
                __isl_take isl_union_pw_qpolynomial_fold *upwf);
        __isl_give isl_union_pw_qpolynomial_fold *isl_union_pw_qpolynomial_fold_intersect_domain(
                __isl_take isl_union_pw_qpolynomial_fold *upwf,
                __isl_take isl_union_set *uset);
        __isl_give isl_union_pw_qpolynomial_fold *
        isl_union_pw_qpolynomial_fold_intersect_params(
                __isl_take isl_union_pw_qpolynomial_fold *upwf,
                __isl_take isl_set *set);
        __isl_give isl_pw_qpolynomial_fold *isl_pw_qpolynomial_fold_project_domain_on_params(
                __isl_take isl_pw_qpolynomial_fold *pwf);
        __isl_give isl_pw_qpolynomial_fold *isl_pw_qpolynomial_fold_coalesce(
                __isl_take isl_pw_qpolynomial_fold *pwf);
        __isl_give isl_union_pw_qpolynomial_fold *isl_union_pw_qpolynomial_fold_coalesce(
                __isl_take isl_union_pw_qpolynomial_fold *upwf);
        __isl_give isl_qpolynomial_fold *isl_qpolynomial_fold_gist_params(
                __isl_take isl_qpolynomial_fold *fold,
                __isl_take isl_set *context);
        __isl_give isl_qpolynomial_fold *isl_qpolynomial_fold_gist(
                __isl_take isl_qpolynomial_fold *fold,
                __isl_take isl_set *context);
        __isl_give isl_pw_qpolynomial_fold *isl_pw_qpolynomial_fold_gist(
                __isl_take isl_pw_qpolynomial_fold *pwf,
                __isl_take isl_set *context);
        __isl_give isl_pw_qpolynomial_fold *isl_pw_qpolynomial_fold_gist_params(
                __isl_take isl_pw_qpolynomial_fold *pwf,
                __isl_take isl_set *context);
        __isl_give isl_union_pw_qpolynomial_fold *isl_union_pw_qpolynomial_fold_gist(
                __isl_take isl_union_pw_qpolynomial_fold *upwf,
                __isl_take isl_union_set *context);
        __isl_give isl_union_pw_qpolynomial_fold *
        isl_union_pw_qpolynomial_fold_gist_params(
                __isl_take isl_union_pw_qpolynomial_fold *upwf,
                __isl_take isl_set *context);

The gist operation applies the gist operation to each of the cells in the domain of the input piecewise quasipolynomial reduction. In future, the operation will also exploit the context to simplify the quasipolynomial reductions associated to each cell.

        __isl_give isl_pw_qpolynomial_fold *
        isl_set_apply_pw_qpolynomial_fold(
                __isl_take isl_set *set,
                __isl_take isl_pw_qpolynomial_fold *pwf,
                int *tight);
        __isl_give isl_pw_qpolynomial_fold *
        isl_map_apply_pw_qpolynomial_fold(
                __isl_take isl_map *map,
                __isl_take isl_pw_qpolynomial_fold *pwf,
                int *tight);
        __isl_give isl_union_pw_qpolynomial_fold *
        isl_union_set_apply_union_pw_qpolynomial_fold(
                __isl_take isl_union_set *uset,
                __isl_take isl_union_pw_qpolynomial_fold *upwf,
                int *tight);
        __isl_give isl_union_pw_qpolynomial_fold *
        isl_union_map_apply_union_pw_qpolynomial_fold(
                __isl_take isl_union_map *umap,
                __isl_take isl_union_pw_qpolynomial_fold *upwf,
                int *tight);

The functions taking a map compose the given map with the given piecewise quasipolynomial reduction. That is, compute a bound (of the same type as pwf or upwf itself) over all elements in the intersection of the range of the map and the domain of the piecewise quasipolynomial reduction as a function of an element in the domain of the map. The functions taking a set compute a bound over all elements in the intersection of the set and the domain of the piecewise quasipolynomial reduction.

Parametric Vertex Enumeration

The parametric vertex enumeration described in this section is mainly intended to be used internally and by the barvinok library.

        #include <isl/vertices.h>
        __isl_give isl_vertices *isl_basic_set_compute_vertices(
                __isl_keep isl_basic_set *bset);

The function isl_basic_set_compute_vertices performs the actual computation of the parametric vertices and the chamber decomposition and store the result in an isl_vertices object. This information can be queried by either iterating over all the vertices or iterating over all the chambers or cells and then iterating over all vertices that are active on the chamber.

        int isl_vertices_foreach_vertex(
                __isl_keep isl_vertices *vertices,
                int (*fn)(__isl_take isl_vertex *vertex, void *user),
                void *user);
        int isl_vertices_foreach_cell(
                __isl_keep isl_vertices *vertices,
                int (*fn)(__isl_take isl_cell *cell, void *user),
                void *user);
        int isl_cell_foreach_vertex(__isl_keep isl_cell *cell,
                int (*fn)(__isl_take isl_vertex *vertex, void *user),
                void *user);

Other operations that can be performed on an isl_vertices object are the following.

        isl_ctx *isl_vertices_get_ctx(
                __isl_keep isl_vertices *vertices);
        int isl_vertices_get_n_vertices(
                __isl_keep isl_vertices *vertices);
        void isl_vertices_free(__isl_take isl_vertices *vertices);

Vertices can be inspected and destroyed using the following functions.

        isl_ctx *isl_vertex_get_ctx(__isl_keep isl_vertex *vertex);
        int isl_vertex_get_id(__isl_keep isl_vertex *vertex);
        __isl_give isl_basic_set *isl_vertex_get_domain(
                __isl_keep isl_vertex *vertex);
        __isl_give isl_basic_set *isl_vertex_get_expr(
                __isl_keep isl_vertex *vertex);
        void isl_vertex_free(__isl_take isl_vertex *vertex);

isl_vertex_get_expr returns a singleton parametric set describing the vertex, while isl_vertex_get_domain returns the activity domain of the vertex. Note that isl_vertex_get_domain and isl_vertex_get_expr return rational basic sets, so they should mainly be used for inspection and should not be mixed with integer sets.

Chambers can be inspected and destroyed using the following functions.

        isl_ctx *isl_cell_get_ctx(__isl_keep isl_cell *cell);
        __isl_give isl_basic_set *isl_cell_get_domain(
                __isl_keep isl_cell *cell);
        void isl_cell_free(__isl_take isl_cell *cell);


Polyhedral Compilation Library

This section collects functionality in isl that has been specifically designed for use during polyhedral compilation.

Dependence Analysis

isl contains specialized functionality for performing array dataflow analysis. That is, given a sink access relation and a collection of possible source access relations, isl can compute relations that describe for each iteration of the sink access, which iteration of which of the source access relations was the last to access the same data element before the given iteration of the sink access. The resulting dependence relations map source iterations to the corresponding sink iterations. To compute standard flow dependences, the sink should be a read, while the sources should be writes. If any of the source accesses are marked as being may accesses, then there will be a dependence from the last must access and from any may access that follows this last must access. In particular, if all sources are may accesses, then memory based dependence analysis is performed. If, on the other hand, all sources are must accesses, then value based dependence analysis is performed.

        #include <isl/flow.h>
        typedef int (*isl_access_level_before)(void *first, void *second);
        __isl_give isl_access_info *isl_access_info_alloc(
                __isl_take isl_map *sink,
                void *sink_user, isl_access_level_before fn,
                int max_source);
        __isl_give isl_access_info *isl_access_info_add_source(
                __isl_take isl_access_info *acc,
                __isl_take isl_map *source, int must,
                void *source_user);
        void *isl_access_info_free(__isl_take isl_access_info *acc);
        __isl_give isl_flow *isl_access_info_compute_flow(
                __isl_take isl_access_info *acc);
        int isl_flow_foreach(__isl_keep isl_flow *deps,
                int (*fn)(__isl_take isl_map *dep, int must,
                          void *dep_user, void *user),
                void *user);
        __isl_give isl_map *isl_flow_get_no_source(
                __isl_keep isl_flow *deps, int must);
        void isl_flow_free(__isl_take isl_flow *deps);

The function isl_access_info_compute_flow performs the actual dependence analysis. The other functions are used to construct the input for this function or to read off the output.

The input is collected in an isl_access_info, which can be created through a call to isl_access_info_alloc. The arguments to this functions are the sink access relation sink, a token sink_user used to identify the sink access to the user, a callback function for specifying the relative order of source and sink accesses, and the number of source access relations that will be added. The callback function has type int (*)(void *first, void *second). The function is called with two user supplied tokens identifying either a source or the sink and it should return the shared nesting level and the relative order of the two accesses. In particular, let n be the number of loops shared by the two accesses. If first precedes second textually, then the function should return 2 * n + 1; otherwise, it should return 2 * n. The sources can be added to the isl_access_info by performing (at most) max_source calls to isl_access_info_add_source. must indicates whether the source is a must access or a may access. Note that a multi-valued access relation should only be marked must if every iteration in the domain of the relation accesses all elements in its image. The source_user token is again used to identify the source access. The range of the source access relation source should have the same dimension as the range of the sink access relation. The isl_access_info_free function should usually not be called explicitly, because it is called implicitly by isl_access_info_compute_flow.

The result of the dependence analysis is collected in an isl_flow. There may be elements of the sink access for which no preceding source access could be found or for which all preceding sources are may accesses. The relations containing these elements can be obtained through calls to isl_flow_get_no_source, the first with must set and the second with must unset. In the case of standard flow dependence analysis, with the sink a read and the sources must writes, the first relation corresponds to the reads from uninitialized array elements and the second relation is empty. The actual flow dependences can be extracted using isl_flow_foreach. This function will call the user-specified callback function fn for each non-empty dependence between a source and the sink. The callback function is called with four arguments, the actual flow dependence relation mapping source iterations to sink iterations, a boolean that indicates whether it is a must or may dependence, a token identifying the source and an additional void * with value equal to the third argument of the isl_flow_foreach call. A dependence is marked must if it originates from a must source and if it is not followed by any may sources.

After finishing with an isl_flow, the user should call isl_flow_free to free all associated memory.

A higher-level interface to dependence analysis is provided by the following function.

        #include <isl/flow.h>
        int isl_union_map_compute_flow(__isl_take isl_union_map *sink,
                __isl_take isl_union_map *must_source,
                __isl_take isl_union_map *may_source,
                __isl_take isl_union_map *schedule,
                __isl_give isl_union_map **must_dep,
                __isl_give isl_union_map **may_dep,
                __isl_give isl_union_map **must_no_source,
                __isl_give isl_union_map **may_no_source);

The arrays are identified by the tuple names of the ranges of the accesses. The iteration domains by the tuple names of the domains of the accesses and of the schedule. The relative order of the iteration domains is given by the schedule. The relations returned through must_no_source and may_no_source are subsets of sink. Any of must_dep, may_dep, must_no_source or may_no_source may be NULL, but a NULL value for any of the other arguments is treated as an error.

Interaction with Dependence Analysis

During the dependence analysis, we frequently need to perform the following operation. Given a relation between sink iterations and potential source iterations from a particular source domain, what is the last potential source iteration corresponding to each sink iteration. It can sometimes be convenient to adjust the set of potential source iterations before or after each such operation. The prototypical example is fuzzy array dataflow analysis, where we need to analyze if, based on data-dependent constraints, the sink iteration can ever be executed without one or more of the corresponding potential source iterations being executed. If so, we can introduce extra parameters and select an unknown but fixed source iteration from the potential source iterations. To be able to perform such manipulations, isl provides the following function.

        #include <isl/flow.h>
        typedef __isl_give isl_restriction *(*isl_access_restrict)(
                __isl_keep isl_map *source_map,
                __isl_keep isl_set *sink, void *source_user,
                void *user);
        __isl_give isl_access_info *isl_access_info_set_restrict(
                __isl_take isl_access_info *acc,
                isl_access_restrict fn, void *user);

The function isl_access_info_set_restrict should be called before calling isl_access_info_compute_flow and registers a callback function that will be called any time isl is about to compute the last potential source. The first argument is the (reverse) proto-dependence, mapping sink iterations to potential source iterations. The second argument represents the sink iterations for which we want to compute the last source iteration. The third argument is the token corresponding to the source and the final argument is the token passed to isl_access_info_set_restrict. The callback is expected to return a restriction on either the input or the output of the operation computing the last potential source. If the input needs to be restricted then restrictions are needed for both the source and the sink iterations. The sink iterations and the potential source iterations will be intersected with these sets. If the output needs to be restricted then only a restriction on the source iterations is required. If any error occurs, the callback should return NULL. An isl_restriction object can be created, freed and inspected using the following functions.

        #include <isl/flow.h>
        __isl_give isl_restriction *isl_restriction_input(
                __isl_take isl_set *source_restr,
                __isl_take isl_set *sink_restr);
        __isl_give isl_restriction *isl_restriction_output(
                __isl_take isl_set *source_restr);
        __isl_give isl_restriction *isl_restriction_none(
                __isl_take isl_map *source_map);
        __isl_give isl_restriction *isl_restriction_empty(
                __isl_take isl_map *source_map);
        void *isl_restriction_free(
                __isl_take isl_restriction *restr);
        isl_ctx *isl_restriction_get_ctx(
                __isl_keep isl_restriction *restr);

isl_restriction_none and isl_restriction_empty are special cases of isl_restriction_input. isl_restriction_none is essentially equivalent to

        isl_restriction_input(isl_set_universe(
            isl_space_range(isl_map_get_space(source_map))),
                            isl_set_universe(
            isl_space_domain(isl_map_get_space(source_map))));

whereas isl_restriction_empty is essentially equivalent to

        isl_restriction_input(isl_set_empty(
            isl_space_range(isl_map_get_space(source_map))),
                            isl_set_universe(
            isl_space_domain(isl_map_get_space(source_map))));

Scheduling

The functionality described in this section is fairly new and may be subject to change.

The following function can be used to compute a schedule for a union of domains. By default, the algorithm used to construct the schedule is similar to that of Pluto. Alternatively, Feautrier's multi-dimensional scheduling algorithm can be selected. The generated schedule respects all validity dependences. That is, all dependence distances over these dependences in the scheduled space are lexicographically positive. The default algorithm tries to minimize the dependence distances over proximity dependences. Moreover, it tries to obtain sequences (bands) of schedule dimensions for groups of domains where the dependence distances have only non-negative values. When using Feautrier's algorithm, the proximity dependence distances are only minimized during the extension to a full-dimensional schedule.

        #include <isl/schedule.h>
        __isl_give isl_schedule *isl_union_set_compute_schedule(
                __isl_take isl_union_set *domain,
                __isl_take isl_union_map *validity,
                __isl_take isl_union_map *proximity);
        void *isl_schedule_free(__isl_take isl_schedule *sched);

A mapping from the domains to the scheduled space can be obtained from an isl_schedule using the following function.

        __isl_give isl_union_map *isl_schedule_get_map(
                __isl_keep isl_schedule *sched);

A representation of the schedule can be printed using


        __isl_give isl_printer *isl_printer_print_schedule(
                __isl_take isl_printer *p,
                __isl_keep isl_schedule *schedule);

A representation of the schedule as a forest of bands can be obtained using the following function.

        __isl_give isl_band_list *isl_schedule_get_band_forest(
                __isl_keep isl_schedule *schedule);

The individual bands can be visited in depth-first post-order using the following function.

        #include <isl/schedule.h>
        int isl_schedule_foreach_band(
                __isl_keep isl_schedule *sched,
                int (*fn)(__isl_keep isl_band *band, void *user),
                void *user);

The list can be manipulated as explained in Lists. The bands inside the list can be copied and freed using the following functions.

        #include <isl/band.h>
        __isl_give isl_band *isl_band_copy(
                __isl_keep isl_band *band);
        void *isl_band_free(__isl_take isl_band *band);

Each band contains zero or more scheduling dimensions. These are referred to as the members of the band. The section of the schedule that corresponds to the band is referred to as the partial schedule of the band. For those nodes that participate in a band, the outer scheduling dimensions form the prefix schedule, while the inner scheduling dimensions form the suffix schedule. That is, if we take a cut of the band forest, then the union of the concatenations of the prefix, partial and suffix schedules of each band in the cut is equal to the entire schedule (modulo some possible padding at the end with zero scheduling dimensions). The properties of a band can be inspected using the following functions.

        #include <isl/band.h>
        isl_ctx *isl_band_get_ctx(__isl_keep isl_band *band);
        int isl_band_has_children(__isl_keep isl_band *band);
        __isl_give isl_band_list *isl_band_get_children(
                __isl_keep isl_band *band);
        __isl_give isl_union_map *isl_band_get_prefix_schedule(
                __isl_keep isl_band *band);
        __isl_give isl_union_map *isl_band_get_partial_schedule(
                __isl_keep isl_band *band);
        __isl_give isl_union_map *isl_band_get_suffix_schedule(
                __isl_keep isl_band *band);
        int isl_band_n_member(__isl_keep isl_band *band);
        int isl_band_member_is_zero_distance(
                __isl_keep isl_band *band, int pos);
        int isl_band_list_foreach_band(
                __isl_keep isl_band_list *list,
                int (*fn)(__isl_keep isl_band *band, void *user),
                void *user);

Note that a scheduling dimension is considered to be ``zero distance'' if it does not carry any proximity dependences within its band. That is, if the dependence distances of the proximity dependences are all zero in that direction (for fixed iterations of outer bands). Like isl_schedule_foreach_band, the function isl_band_list_foreach_band calls fn on the bands in depth-first post-order.

A band can be tiled using the following function.

        #include <isl/band.h>
        int isl_band_tile(__isl_keep isl_band *band,
                __isl_take isl_vec *sizes);
        int isl_options_set_tile_scale_tile_loops(isl_ctx *ctx,
                int val);
        int isl_options_get_tile_scale_tile_loops(isl_ctx *ctx);
        int isl_options_set_tile_shift_point_loops(isl_ctx *ctx,
                int val);
        int isl_options_get_tile_shift_point_loops(isl_ctx *ctx);

The isl_band_tile function tiles the band using the given tile sizes inside its schedule. A new child band is created to represent the point loops and it is inserted between the modified band and its children. The tile_scale_tile_loops option specifies whether the tile loops iterators should be scaled by the tile sizes. If the tile_shift_point_loops option is set, then the point loops are shifted to start at zero.

A band can be split into two nested bands using the following function.

        int isl_band_split(__isl_keep isl_band *band, int pos);

The resulting outer band contains the first pos dimensions of band while the inner band contains the remaining dimensions.

A representation of the band can be printed using

        #include <isl/band.h>
        __isl_give isl_printer *isl_printer_print_band(
                __isl_take isl_printer *p,
                __isl_keep isl_band *band);

Options

        #include <isl/schedule.h>
        int isl_options_set_schedule_max_coefficient(
                isl_ctx *ctx, int val);
        int isl_options_get_schedule_max_coefficient(
                isl_ctx *ctx);
        int isl_options_set_schedule_max_constant_term(
                isl_ctx *ctx, int val);
        int isl_options_get_schedule_max_constant_term(
                isl_ctx *ctx);
        int isl_options_set_schedule_fuse(isl_ctx *ctx, int val);
        int isl_options_get_schedule_fuse(isl_ctx *ctx);
        int isl_options_set_schedule_maximize_band_depth(
                isl_ctx *ctx, int val);
        int isl_options_get_schedule_maximize_band_depth(
                isl_ctx *ctx);
        int isl_options_set_schedule_outer_zero_distance(
                isl_ctx *ctx, int val);
        int isl_options_get_schedule_outer_zero_distance(
                isl_ctx *ctx);
        int isl_options_set_schedule_split_scaled(
                isl_ctx *ctx, int val);
        int isl_options_get_schedule_split_scaled(
                isl_ctx *ctx);
        int isl_options_set_schedule_algorithm(
                isl_ctx *ctx, int val);
        int isl_options_get_schedule_algorithm(
                isl_ctx *ctx);
        int isl_options_set_schedule_separate_components(
                isl_ctx *ctx, int val);
        int isl_options_get_schedule_separate_components(
                isl_ctx *ctx);

AST Generation

This section describes the isl functionality for generating ASTs that visit all the elements in a domain in an order specified by a schedule. In particular, given a isl_union_map, an AST is generated that visits all the elements in the domain of the isl_union_map according to the lexicographic order of the corresponding image element(s). If the range of the isl_union_map consists of elements in more than one space, then each of these spaces is handled separately in an arbitrary order. It should be noted that the image elements only specify the order in which the corresponding domain elements should be visited. No direct relation between the image elements and the loop iterators in the generated AST should be assumed.

Each AST is generated within a build. The initial build simply specifies the constraints on the parameters (if any) and can be created, inspected, copied and freed using the following functions.

        #include <isl/ast_build.h>
        __isl_give isl_ast_build *isl_ast_build_from_context(
                __isl_take isl_set *set);
        isl_ctx *isl_ast_build_get_ctx(
                __isl_keep isl_ast_build *build);
        __isl_give isl_ast_build *isl_ast_build_copy(
                __isl_keep isl_ast_build *build);
        void *isl_ast_build_free(
                __isl_take isl_ast_build *build);

The set argument is usually a parameter set with zero or more parameters. More isl_ast_build functions are described in Nested AST Generation and Fine-grained Control over AST Generation. Finally, the AST itself can be constructed using the following function.

        #include <isl/ast_build.h>
        __isl_give isl_ast_node *isl_ast_build_ast_from_schedule(
                __isl_keep isl_ast_build *build,
                __isl_take isl_union_map *schedule);

Inspecting the AST

The basic properties of an AST node can be obtained as follows.

        #include <isl/ast.h>
        isl_ctx *isl_ast_node_get_ctx(
                __isl_keep isl_ast_node *node);
        enum isl_ast_node_type isl_ast_node_get_type(
                __isl_keep isl_ast_node *node);

The type of an AST node is one of isl_ast_node_for, isl_ast_node_if, isl_ast_node_block or isl_ast_node_user. An isl_ast_node_for represents a for node. An isl_ast_node_if represents an if node. An isl_ast_node_block represents a compound node. An isl_ast_node_user represents an expression statement. An expression statement typically corresponds to a domain element, i.e., one of the elements that is visited by the AST.

Each type of node has its own additional properties.

        #include <isl/ast.h>
        __isl_give isl_ast_expr *isl_ast_node_for_get_iterator(
                __isl_keep isl_ast_node *node);
        __isl_give isl_ast_expr *isl_ast_node_for_get_init(
                __isl_keep isl_ast_node *node);
        __isl_give isl_ast_expr *isl_ast_node_for_get_cond(
                __isl_keep isl_ast_node *node);
        __isl_give isl_ast_expr *isl_ast_node_for_get_inc(
                __isl_keep isl_ast_node *node);
        __isl_give isl_ast_node *isl_ast_node_for_get_body(
                __isl_keep isl_ast_node *node);
        int isl_ast_node_for_is_degenerate(
                __isl_keep isl_ast_node *node);

An isl_ast_for is considered degenerate if it is known to execute exactly once.

        #include <isl/ast.h>
        __isl_give isl_ast_expr *isl_ast_node_if_get_cond(
                __isl_keep isl_ast_node *node);
        __isl_give isl_ast_node *isl_ast_node_if_get_then(
                __isl_keep isl_ast_node *node);
        int isl_ast_node_if_has_else(
                __isl_keep isl_ast_node *node);
        __isl_give isl_ast_node *isl_ast_node_if_get_else(
                __isl_keep isl_ast_node *node);
        __isl_give isl_ast_node_list *
        isl_ast_node_block_get_children(
                __isl_keep isl_ast_node *node);
        __isl_give isl_ast_expr *isl_ast_node_user_get_expr(
                __isl_keep isl_ast_node *node);

Each of the returned isl_ast_exprs can in turn be inspected using the following functions.

        #include <isl/ast.h>
        isl_ctx *isl_ast_expr_get_ctx(
                __isl_keep isl_ast_expr *expr);
        enum isl_ast_expr_type isl_ast_expr_get_type(
                __isl_keep isl_ast_expr *expr);

The type of an AST expression is one of isl_ast_expr_op, isl_ast_expr_id or isl_ast_expr_int. An isl_ast_expr_op represents the result of an operation. An isl_ast_expr_id represents an identifier. An isl_ast_expr_int represents an integer value.

Each type of expression has its own additional properties.

        #include <isl/ast.h>
        enum isl_ast_op_type isl_ast_expr_get_op_type(
                __isl_keep isl_ast_expr *expr);
        int isl_ast_expr_get_op_n_arg(__isl_keep isl_ast_expr *expr);
        __isl_give isl_ast_expr *isl_ast_expr_get_op_arg(
                __isl_keep isl_ast_expr *expr, int pos);
        int isl_ast_node_foreach_ast_op_type(
                __isl_keep isl_ast_node *node,
                int (*fn)(enum isl_ast_op_type type, void *user),
                void *user);

isl_ast_expr_get_op_type returns the type of the operation performed. isl_ast_expr_get_op_n_arg returns the number of arguments. isl_ast_expr_get_op_arg returns the specified argument. isl_ast_node_foreach_ast_op_type calls fn for each distinct isl_ast_op_type that appears in node. The operation type is one of the following.

isl_ast_op_and

Logical and of two arguments. Both arguments can be evaluated.

isl_ast_op_and_then

Logical and of two arguments. The second argument can only be evaluated if the first evaluates to true.

isl_ast_op_or

Logical or of two arguments. Both arguments can be evaluated.

isl_ast_op_or_else

Logical or of two arguments. The second argument can only be evaluated if the first evaluates to false.

isl_ast_op_max

Maximum of two or more arguments.

isl_ast_op_min

Minimum of two or more arguments.

isl_ast_op_minus

Change sign.

isl_ast_op_add

Sum of two arguments.

isl_ast_op_sub

Difference of two arguments.

isl_ast_op_mul

Product of two arguments.

isl_ast_op_div

Exact division. That is, the result is known to be an integer.

isl_ast_op_fdiv_q

Result of integer division, rounded towards negative infinity.

isl_ast_op_pdiv_q

Result of integer division, where dividend is known to be non-negative.

isl_ast_op_pdiv_r

Remainder of integer division, where dividend is known to be non-negative.

isl_ast_op_cond

Conditional operator defined on three arguments. If the first argument evaluates to true, then the result is equal to the second argument. Otherwise, the result is equal to the third argument. The second and third argument may only be evaluated if the first argument evaluates to true and false, respectively. Corresponds to a ? b : c in C.

isl_ast_op_select

Conditional operator defined on three arguments. If the first argument evaluates to true, then the result is equal to the second argument. Otherwise, the result is equal to the third argument. The second and third argument may be evaluated independently of the value of the first argument. Corresponds to a * b + (1 - a) * c in C.

isl_ast_op_eq

Equality relation.

isl_ast_op_le

Less than or equal relation.

isl_ast_op_lt

Less than relation.

isl_ast_op_ge

Greater than or equal relation.

isl_ast_op_gt

Greater than relation.

isl_ast_op_call

A function call. The number of arguments of the isl_ast_expr is one more than the number of arguments in the function call, the first argument representing the function being called.

isl_ast_op_access

An array access. The number of arguments of the isl_ast_expr is one more than the number of index expressions in the array access, the first argument representing the array being accessed.

        #include <isl/ast.h>
        __isl_give isl_id *isl_ast_expr_get_id(
                __isl_keep isl_ast_expr *expr);

Return the identifier represented by the AST expression.

        #include <isl/ast.h>
        __isl_give isl_val *isl_ast_expr_get_val(
                __isl_keep isl_ast_expr *expr);

Return the integer represented by the AST expression.

Properties of ASTs

        #include <isl/ast.h>
        int isl_ast_expr_is_equal(__isl_keep isl_ast_expr *expr1,
                __isl_keep isl_ast_expr *expr2);

Check if two isl_ast_exprs are equal to each other.

Manipulating and printing the AST

AST nodes can be copied and freed using the following functions.

        #include <isl/ast.h>
        __isl_give isl_ast_node *isl_ast_node_copy(
                __isl_keep isl_ast_node *node);
        void *isl_ast_node_free(__isl_take isl_ast_node *node);

AST expressions can be copied and freed using the following functions.

        #include <isl/ast.h>
        __isl_give isl_ast_expr *isl_ast_expr_copy(
                __isl_keep isl_ast_expr *expr);
        void *isl_ast_expr_free(__isl_take isl_ast_expr *expr);

New AST expressions can be created either directly or within the context of an isl_ast_build.

        #include <isl/ast.h>
        __isl_give isl_ast_expr *isl_ast_expr_from_val(
                __isl_take isl_val *v);
        __isl_give isl_ast_expr *isl_ast_expr_from_id(
                __isl_take isl_id *id);
        __isl_give isl_ast_expr *isl_ast_expr_neg(
                __isl_take isl_ast_expr *expr);
        __isl_give isl_ast_expr *isl_ast_expr_add(
                __isl_take isl_ast_expr *expr1,
                __isl_take isl_ast_expr *expr2);
        __isl_give isl_ast_expr *isl_ast_expr_sub(
                __isl_take isl_ast_expr *expr1,
                __isl_take isl_ast_expr *expr2);
        __isl_give isl_ast_expr *isl_ast_expr_mul(
                __isl_take isl_ast_expr *expr1,
                __isl_take isl_ast_expr *expr2);
        __isl_give isl_ast_expr *isl_ast_expr_div(
                __isl_take isl_ast_expr *expr1,
                __isl_take isl_ast_expr *expr2);
        __isl_give isl_ast_expr *isl_ast_expr_and(
                __isl_take isl_ast_expr *expr1,
                __isl_take isl_ast_expr *expr2)
        __isl_give isl_ast_expr *isl_ast_expr_or(
                __isl_take isl_ast_expr *expr1,
                __isl_take isl_ast_expr *expr2)
        __isl_give isl_ast_expr *isl_ast_expr_access(
                __isl_take isl_ast_expr *array,
                __isl_take isl_ast_expr_list *indices);
        __isl_give isl_ast_expr *isl_ast_expr_substitute_ids(
                __isl_take isl_ast_expr *expr,
                __isl_take isl_id_to_ast_expr *id2expr);

The function isl_ast_expr_substitute_ids replaces the subexpressions of expr of type isl_ast_expr_id by the corresponding expression in id2expr, if there is any.

        #include <isl/ast_build.h>
        __isl_give isl_ast_expr *isl_ast_build_expr_from_pw_aff(
                __isl_keep isl_ast_build *build,
                __isl_take isl_pw_aff *pa);
        __isl_give isl_ast_expr *
        isl_ast_build_access_from_pw_multi_aff(
                __isl_keep isl_ast_build *build,
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_ast_expr *
        isl_ast_build_access_from_multi_pw_aff(
                __isl_keep isl_ast_build *build,
                __isl_take isl_multi_pw_aff *mpa);
        __isl_give isl_ast_expr *
        isl_ast_build_call_from_pw_multi_aff(
                __isl_keep isl_ast_build *build,
                __isl_take isl_pw_multi_aff *pma);
        __isl_give isl_ast_expr *
        isl_ast_build_call_from_multi_pw_aff(
                __isl_keep isl_ast_build *build,
                __isl_take isl_multi_pw_aff *mpa);

The domains of pa, mpa and pma should correspond to the schedule space of build. The tuple id of mpa or pma is used as the array being accessed or the function being called.

User specified data can be attached to an isl_ast_node and obtained from the same isl_ast_node using the following functions.

        #include <isl/ast.h>
        __isl_give isl_ast_node *isl_ast_node_set_annotation(
                __isl_take isl_ast_node *node,
                __isl_take isl_id *annotation);
        __isl_give isl_id *isl_ast_node_get_annotation(
                __isl_keep isl_ast_node *node);

Basic printing can be performed using the following functions.

        #include <isl/ast.h>
        __isl_give isl_printer *isl_printer_print_ast_expr(
                __isl_take isl_printer *p,
                __isl_keep isl_ast_expr *expr);
        __isl_give isl_printer *isl_printer_print_ast_node(
                __isl_take isl_printer *p,
                __isl_keep isl_ast_node *node);

More advanced printing can be performed using the following functions.

        #include <isl/ast.h>
        __isl_give isl_printer *isl_ast_op_type_print_macro(
                enum isl_ast_op_type type,
                __isl_take isl_printer *p);
        __isl_give isl_printer *isl_ast_node_print_macros(
                __isl_keep isl_ast_node *node,
                __isl_take isl_printer *p);
        __isl_give isl_printer *isl_ast_node_print(
                __isl_keep isl_ast_node *node,
                __isl_take isl_printer *p,
                __isl_take isl_ast_print_options *options);
        __isl_give isl_printer *isl_ast_node_for_print(
                __isl_keep isl_ast_node *node,
                __isl_take isl_printer *p,
                __isl_take isl_ast_print_options *options);
        __isl_give isl_printer *isl_ast_node_if_print(
                __isl_keep isl_ast_node *node,
                __isl_take isl_printer *p,
                __isl_take isl_ast_print_options *options);

While printing an isl_ast_node in ISL_FORMAT_C, isl may print out an AST that makes use of macros such as floord, min and max. isl_ast_op_type_print_macro prints out the macro corresponding to a specific isl_ast_op_type. isl_ast_node_print_macros scans the isl_ast_node for expressions where these macros would be used and prints out the required macro definitions. Essentially, isl_ast_node_print_macros calls isl_ast_node_foreach_ast_op_type with isl_ast_op_type_print_macro as function argument. isl_ast_node_print, isl_ast_node_for_print and isl_ast_node_if_print print an isl_ast_node in ISL_FORMAT_C, but allow for some extra control through an isl_ast_print_options object. This object can be created using the following functions.

        #include <isl/ast.h>
        __isl_give isl_ast_print_options *
        isl_ast_print_options_alloc(isl_ctx *ctx);
        __isl_give isl_ast_print_options *
        isl_ast_print_options_copy(
                __isl_keep isl_ast_print_options *options);
        void *isl_ast_print_options_free(
                __isl_take isl_ast_print_options *options);
        __isl_give isl_ast_print_options *
        isl_ast_print_options_set_print_user(
                __isl_take isl_ast_print_options *options,
                __isl_give isl_printer *(*print_user)(
                        __isl_take isl_printer *p,
                        __isl_take isl_ast_print_options *options,
                        __isl_keep isl_ast_node *node, void *user),
                void *user);
        __isl_give isl_ast_print_options *
        isl_ast_print_options_set_print_for(
                __isl_take isl_ast_print_options *options,
                __isl_give isl_printer *(*print_for)(
                        __isl_take isl_printer *p,
                        __isl_take isl_ast_print_options *options,
                        __isl_keep isl_ast_node *node, void *user),
                void *user);

The callback set by isl_ast_print_options_set_print_user is called whenever a node of type isl_ast_node_user needs to be printed. The callback set by isl_ast_print_options_set_print_for is called whenever a node of type isl_ast_node_for needs to be printed. Note that isl_ast_node_for_print will not call the callback set by isl_ast_print_options_set_print_for on the node on which isl_ast_node_for_print is called, but only on nested nodes of type isl_ast_node_for. It is therefore safe to call isl_ast_node_for_print from within the callback set by isl_ast_print_options_set_print_for.

The following option determines the type to be used for iterators while printing the AST.

        int isl_options_set_ast_iterator_type(
                isl_ctx *ctx, const char *val);
        const char *isl_options_get_ast_iterator_type(
                isl_ctx *ctx);

Options

        #include <isl/ast_build.h>
        int isl_options_set_ast_build_atomic_upper_bound(
                isl_ctx *ctx, int val);
        int isl_options_get_ast_build_atomic_upper_bound(
                isl_ctx *ctx);
        int isl_options_set_ast_build_prefer_pdiv(isl_ctx *ctx,
                int val);
        int isl_options_get_ast_build_prefer_pdiv(isl_ctx *ctx);
        int isl_options_set_ast_build_exploit_nested_bounds(
                isl_ctx *ctx, int val);
        int isl_options_get_ast_build_exploit_nested_bounds(
                isl_ctx *ctx);
        int isl_options_set_ast_build_group_coscheduled(
                isl_ctx *ctx, int val);
        int isl_options_get_ast_build_group_coscheduled(
                isl_ctx *ctx);
        int isl_options_set_ast_build_scale_strides(
                isl_ctx *ctx, int val);
        int isl_options_get_ast_build_scale_strides(
                isl_ctx *ctx);
        int isl_options_set_ast_build_allow_else(isl_ctx *ctx,
                int val);
        int isl_options_get_ast_build_allow_else(isl_ctx *ctx);
        int isl_options_set_ast_build_allow_or(isl_ctx *ctx,
                int val);
        int isl_options_get_ast_build_allow_or(isl_ctx *ctx);

Fine-grained Control over AST Generation

Besides specifying the constraints on the parameters, an isl_ast_build object can be used to control various aspects of the AST generation process. The most prominent way of control is through ``options'', which can be set using the following function.

        #include <isl/ast_build.h>
        __isl_give isl_ast_build *
        isl_ast_build_set_options(
                __isl_take isl_ast_build *control,
                __isl_take isl_union_map *options);

The options are encoded in an <isl_union_map>. The domain of this union relation refers to the schedule domain, i.e., the range of the schedule passed to isl_ast_build_ast_from_schedule. In the case of nested AST generation (see Nested AST Generation), the domain of options should refer to the extra piece of the schedule. That is, it should be equal to the range of the wrapped relation in the range of the schedule. The range of the options can consist of elements in one or more spaces, the names of which determine the effect of the option. The values of the range typically also refer to the schedule dimension to which the option applies. In case of nested AST generation (see Nested AST Generation), these values refer to the position of the schedule dimension within the innermost AST generation. The constraints on the domain elements of the option should only refer to this dimension and earlier dimensions. We consider the following spaces.

separation_class

This space is a wrapped relation between two one dimensional spaces. The input space represents the schedule dimension to which the option applies and the output space represents the separation class. While constructing a loop corresponding to the specified schedule dimension(s), the AST generator will try to generate separate loops for domain elements that are assigned different classes. If only some of the elements are assigned a class, then those elements that are not assigned any class will be treated as belonging to a class that is separate from the explicitly assigned classes. The typical use case for this option is to separate full tiles from partial tiles. The other options, described below, are applied after the separation into classes.

As an example, consider the separation into full and partial tiles of a tiling of a triangular domain. Take, for example, the domain

        { A[i,j] : 0 <= i,j and i + j <= 100 }

and a tiling into tiles of 10 by 10. The input to the AST generator is then the schedule

        { A[i,j] -> [([i/10]),[j/10],i,j] : 0 <= i,j and
                                                i + j <= 100 }

Without any options, the following AST is generated

        for (int c0 = 0; c0 <= 10; c0 += 1)
          for (int c1 = 0; c1 <= -c0 + 10; c1 += 1)
            for (int c2 = 10 * c0;
                 c2 <= min(-10 * c1 + 100, 10 * c0 + 9);
                 c2 += 1)
              for (int c3 = 10 * c1;
                   c3 <= min(10 * c1 + 9, -c2 + 100);
                   c3 += 1)
                A(c2, c3);

Separation into full and partial tiles can be obtained by assigning a class, say 0, to the full tiles. The full tiles are represented by those values of the first and second schedule dimensions for which there are values of the third and fourth dimensions to cover an entire tile. That is, we need to specify the following option

        { [a,b,c,d] -> separation_class[[0]->[0]] :
                exists b': 0 <= 10a,10b' and
                           10a+9+10b'+9 <= 100;
          [a,b,c,d] -> separation_class[[1]->[0]] :
                0 <= 10a,10b and 10a+9+10b+9 <= 100 }

which simplifies to

        { [a, b, c, d] -> separation_class[[1] -> [0]] :
                a >= 0 and b >= 0 and b <= 8 - a;
          [a, b, c, d] -> separation_class[[0] -> [0]] :
                a >= 0 and a <= 8 }

With this option, the generated AST is as follows

        {
          for (int c0 = 0; c0 <= 8; c0 += 1) {
            for (int c1 = 0; c1 <= -c0 + 8; c1 += 1)
              for (int c2 = 10 * c0;
                   c2 <= 10 * c0 + 9; c2 += 1)
                for (int c3 = 10 * c1;
                     c3 <= 10 * c1 + 9; c3 += 1)
                  A(c2, c3);
            for (int c1 = -c0 + 9; c1 <= -c0 + 10; c1 += 1)
              for (int c2 = 10 * c0;
                   c2 <= min(-10 * c1 + 100, 10 * c0 + 9);
                   c2 += 1)
                for (int c3 = 10 * c1;
                     c3 <= min(-c2 + 100, 10 * c1 + 9);
                     c3 += 1)
                  A(c2, c3);
          }
          for (int c0 = 9; c0 <= 10; c0 += 1)
            for (int c1 = 0; c1 <= -c0 + 10; c1 += 1)
              for (int c2 = 10 * c0;
                   c2 <= min(-10 * c1 + 100, 10 * c0 + 9);
                   c2 += 1)
                for (int c3 = 10 * c1;
                     c3 <= min(10 * c1 + 9, -c2 + 100);
                     c3 += 1)
                  A(c2, c3);
        }
separate

This is a single-dimensional space representing the schedule dimension(s) to which ``separation'' should be applied. Separation tries to split a loop into several pieces if this can avoid the generation of guards inside the loop. See also the atomic option.

atomic

This is a single-dimensional space representing the schedule dimension(s) for which the domains should be considered ``atomic''. That is, the AST generator will make sure that any given domain space will only appear in a single loop at the specified level.

Consider the following schedule

        { a[i] -> [i] : 0 <= i < 10;
          b[i] -> [i+1] : 0 <= i < 10 }

If the following option is specified

        { [i] -> separate[x] }

then the following AST will be generated

        {
          a(0);
          for (int c0 = 1; c0 <= 9; c0 += 1) {
            a(c0);
            b(c0 - 1);
          }
          b(9);
        }

If, on the other hand, the following option is specified

        { [i] -> atomic[x] }

then the following AST will be generated

        for (int c0 = 0; c0 <= 10; c0 += 1) {
          if (c0 <= 9)
            a(c0);
          if (c0 >= 1)
            b(c0 - 1);
        }

If neither atomic nor separate is specified, then the AST generator may produce either of these two results or some intermediate form.

unroll

This is a single-dimensional space representing the schedule dimension(s) that should be completely unrolled. To obtain a partial unrolling, the user should apply an additional strip-mining to the schedule and fully unroll the inner loop.

Additional control is available through the following functions.

        #include <isl/ast_build.h>
        __isl_give isl_ast_build *
        isl_ast_build_set_iterators(
                __isl_take isl_ast_build *control,
                __isl_take isl_id_list *iterators);

The function isl_ast_build_set_iterators allows the user to specify a list of iterator isl_ids to be used as iterators. If the input schedule is injective, then the number of elements in this list should be as large as the dimension of the schedule space, but no direct correspondence should be assumed between dimensions and elements. If the input schedule is not injective, then an additional number of isl_ids equal to the largest dimension of the input domains may be required. If the number of provided isl_ids is insufficient, then additional names are automatically generated.

        #include <isl/ast_build.h>
        __isl_give isl_ast_build *
        isl_ast_build_set_create_leaf(
                __isl_take isl_ast_build *control,
                __isl_give isl_ast_node *(*fn)(
                        __isl_take isl_ast_build *build,
                        void *user), void *user);

The isl_ast_build_set_create_leaf function allows for the specification of a callback that should be called whenever the AST generator arrives at an element of the schedule domain. The callback should return an AST node that should be inserted at the corresponding position of the AST. The default action (when the callback is not set) is to continue generating parts of the AST to scan all the domain elements associated to the schedule domain element and to insert user nodes, ``calling'' the domain element, for each of them. The build argument contains the current state of the isl_ast_build. To ease nested AST generation (see Nested AST Generation), all control information that is specific to the current AST generation such as the options and the callbacks has been removed from this isl_ast_build. The callback would typically return the result of a nested AST generation or a user defined node created using the following function.

        #include <isl/ast.h>
        __isl_give isl_ast_node *isl_ast_node_alloc_user(
                __isl_take isl_ast_expr *expr);
        #include <isl/ast_build.h>
        __isl_give isl_ast_build *
        isl_ast_build_set_at_each_domain(
                __isl_take isl_ast_build *build,
                __isl_give isl_ast_node *(*fn)(
                        __isl_take isl_ast_node *node,
                        __isl_keep isl_ast_build *build,
                        void *user), void *user);
        __isl_give isl_ast_build *
        isl_ast_build_set_before_each_for(
                __isl_take isl_ast_build *build,
                __isl_give isl_id *(*fn)(
                        __isl_keep isl_ast_build *build,
                        void *user), void *user);
        __isl_give isl_ast_build *
        isl_ast_build_set_after_each_for(
                __isl_take isl_ast_build *build,
                __isl_give isl_ast_node *(*fn)(
                        __isl_take isl_ast_node *node,
                        __isl_keep isl_ast_build *build,
                        void *user), void *user);

The callback set by isl_ast_build_set_at_each_domain will be called for each domain AST node. The callbacks set by isl_ast_build_set_before_each_for and isl_ast_build_set_after_each_for will be called for each for AST node. The first will be called in depth-first pre-order, while the second will be called in depth-first post-order. Since isl_ast_build_set_before_each_for is called before the for node is actually constructed, it is only passed an isl_ast_build. The returned isl_id will be added as an annotation (using isl_ast_node_set_annotation) to the constructed for node. In particular, if the user has also specified an after_each_for callback, then the annotation can be retrieved from the node passed to that callback using isl_ast_node_get_annotation. All callbacks should NULL on failure. The given isl_ast_build can be used to create new isl_ast_expr objects using isl_ast_build_expr_from_pw_aff or isl_ast_build_call_from_pw_multi_aff.

Nested AST Generation

isl allows the user to create an AST within the context of another AST. These nested ASTs are created using the same isl_ast_build_ast_from_schedule function that is used to create the outer AST. The build argument should be an isl_ast_build passed to a callback set by isl_ast_build_set_create_leaf. The space of the range of the schedule argument should refer to this build. In particular, the space should be a wrapped relation and the domain of this wrapped relation should be the same as that of the range of the schedule returned by isl_ast_build_get_schedule below. In practice, the new schedule is typically created by calling isl_union_map_range_product on the old schedule and some extra piece of the schedule. The space of the schedule domain is also available from the isl_ast_build.

        #include <isl/ast_build.h>
        __isl_give isl_union_map *isl_ast_build_get_schedule(
                __isl_keep isl_ast_build *build);
        __isl_give isl_space *isl_ast_build_get_schedule_space(
                __isl_keep isl_ast_build *build);
        __isl_give isl_ast_build *isl_ast_build_restrict(
                __isl_take isl_ast_build *build,
                __isl_take isl_set *set);

The isl_ast_build_get_schedule function returns a (partial) schedule for the domains elements for which part of the AST still needs to be generated in the current build. In particular, the domain elements are mapped to those iterations of the loops enclosing the current point of the AST generation inside which the domain elements are executed. No direct correspondence between the input schedule and this schedule should be assumed. The space obtained from isl_ast_build_get_schedule_space can be used to create a set for isl_ast_build_restrict to intersect with the current build. In particular, the set passed to isl_ast_build_restrict can have additional parameters. The ids of the set dimensions in the space returned by isl_ast_build_get_schedule_space correspond to the iterators of the already generated loops. The user should not rely on the ids of the output dimensions of the relations in the union relation returned by isl_ast_build_get_schedule having any particular value.


Applications

Although isl is mainly meant to be used as a library, it also contains some basic applications that use some of the functionality of isl. The input may be specified in either the isl format or the PolyLib format.

isl_polyhedron_sample

isl_polyhedron_sample takes a polyhedron as input and prints an integer element of the polyhedron, if there is any. The first column in the output is the denominator and is always equal to 1. If the polyhedron contains no integer points, then a vector of length zero is printed.

isl_pip

isl_pip takes the same input as the example program from the piplib distribution, i.e., a set of constraints on the parameters, a line containing only -1 and finally a set of constraints on a parametric polyhedron. The coefficients of the parameters appear in the last columns (but before the final constant column). The output is the lexicographic minimum of the parametric polyhedron. As isl currently does not have its own output format, the output is just a dump of the internal state.

isl_polyhedron_minimize

isl_polyhedron_minimize computes the minimum of some linear or affine objective function over the integer points in a polyhedron. If an affine objective function is given, then the constant should appear in the last column.

isl_polytope_scan

Given a polytope, isl_polytope_scan prints all integer points in the polytope.

isl_codegen

Given a schedule, a context set and an options relation, isl_codegen prints out an AST that scans the domain elements of the schedule in the order of their image(s) taking into account the constraints in the context set.