Add a source-2-source compiler example to the documentation

[cloog.git] / doc / cloog.texi

\input texinfo
@c %
@c %  /**-----------------------------------------------------------------**
@c %   **                              CLooG                              **
@c %   **-----------------------------------------------------------------**
@c %   **                            cloog.texi                           **
@c %   **-----------------------------------------------------------------**
@c %   **                   First version: july 6th 2002                  **
@c %   **-----------------------------------------------------------------**/
@c %
@c % release 1.0: September 17th 2002
@c % release 1.1: December   5th 2002
@c % release 1.2: April     22th 2003
@c % release 2.0: November  21th 2005 (and now in texinfo instead of LaTeX)
@c % release 2.1: October   15th 2007
@c %
@c %/**************************************************************************
@c % *               CLooG : the Chunky Loop Generator (experimental)         *
@c % **************************************************************************/
@c %/* CAUTION: the English used is probably the worst you ever read, please
@c % *          feel free to correct and improve it !
@c % */

@c %\textit{"I found the ultimate transformation functions, optimization for
@c %static control programs is now a closed problem, I have \textnormal{just}
@c %to generate the target code !"} 



@c % /*************************************************************************
@c %  *                              PART I: HEADER                           *
@c %  *************************************************************************/
@c %**start of header
@setfilename cloog.info
@settitle CLooG - a loop generator for scanning polyhedra

@set EDITION 2.1.2
@include gitversion.texi
@set UPDATED July 27th 2015
@setchapternewpage odd

@c %**end of header

@c % /*************************************************************************
@c %  *                 PART II: SUMMARY DESCRIPTION AND COPYRIGHT            *
@c %  *************************************************************************/

@copying
This manual is for CLooG version @value{VERSION}, a software
which generates loops for scanning Z-polyhedra. That is, CLooG produces a
code visiting each integral point of a union of parametrized
polyhedra. CLooG is designed to avoid control overhead and to produce a very
efficient code.

It would be quite kind to refer the following paper in any publication that
results from the use of the CLooG software or its library:

@example
@@InProceedings@{Bas04,
@ @ author =@ @ @ @ @{C. Bastoul@},
@ @ title =@ @ @ @ @ @{Code Generation in the Polyhedral Model
@ @ @ @ @ @ @ @ @ @ @ @ @ @ @ Is Easier Than You Think@},
@ @ booktitle = @{PACT'13 IEEE International Conference on
@ @ @ @ @ @ @ @ @ @ @ @ @ @ @ Parallel Architecture and Compilation Techniques@},
@ @ year =@ @ @ @ @ @ 2004,
@ @ pages =@ @ @ @ @ @{7--16@},
@ @ month =@ @ @ @ @ @{september@},
@ @ address =@ @ @ @{Juan-les-Pins@}
@}
@end example

Copyright @copyright{} 2002-2014 C@'edric Bastoul.

@c quotation
Permission is granted to copy, distribute and/or modify this document under
the terms of the GNU Free Documentation License, Version 1.2 
published by the Free Software Foundation. To receive a copy of the
GNU Free Documentation License, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA  02111-1307 USA.
@c end quotation
@end copying

@c % /*************************************************************************
@c %  *                 PART III: TITLEPAGE, CONTENTS, COPYRIGHT              *
@c %  *************************************************************************/
@titlepage
@title CLooG
@subtitle A Loop Generator For Scanning Polyhedra
@subtitle Edition @value{EDITION}, for CLooG @value{VERSION}
@subtitle @value{UPDATED}
@author C@'edric Bastoul
     
@c The following two commands start the copyright page.
@page
@noindent (September 2001)
@table @code
@item C@'edric Bastoul
SCHEDULES GENERATE !!! I just need to apply them now, where can I find
a good code generator ?!
     
@item Paul Feautrier
Hmmm. I fear that if you want something powerful enough, you'll have to
write it yourself !
@end table

@vskip 0pt plus 1filll
@insertcopying
@end titlepage
     
@c Output the table of contents at the beginning.
@contents

@c % /*************************************************************************
@c %  *                     PART IV: TOP NODE AND MASTER MENU                 *
@c %  *************************************************************************/
@ifnottex
@node Top
@top CLooG
     
@insertcopying
@end ifnottex

@menu
* Introduction::
* CLooG Software::
* CLooG Library::
@c * Hacking::
* Installing::
* Documentation::
* References::
@end menu
 


@c % /*************************************************************************
@c %  *                       PART V: BODY OF THE DOCUMENT                    *
@c %  *************************************************************************/

@c %  ****************************** INTRODUCTION ******************************
@node Introduction
@chapter Introduction
CLooG is a free software and library generating loops for scanning Z-polyhedra.
That is, it finds a code (e.g. in C, FORTRAN...) that reaches each integral
point of one or more parameterized polyhedra. CLooG has been originally
written to solve the code generation problem for optimizing compilers based on
the polytope model. Nevertheless it is used now in various area, e.g., to build
control automata for high-level synthesis or to find the best polynomial
approximation of a function. CLooG may help in any situation where scanning
polyhedra matters. It uses the best state-of-the-art code generation
algorithm known as the Quiller@'e et al. algorithm (@pxref{Qui00})
with our own improvements and extensions (@pxref{Bas04}).
The user has full control on generated code quality.
On one hand, generated code size has to be tuned for sake of
readability or instruction cache use. On the other hand, we must ensure that
a bad control management does not hamper performance of the generated code,
for instance by producing redundant guards or complex loop bounds.
CLooG is specially designed to avoid control overhead and to produce a very
efficient code.

CLooG stands for @emph{Chunky Loop Generator}: it is a part of the Chunky
project, a research tool for data locality improvement (@pxref{Bas03a}).
It is designed
also to be the back-end of automatic parallelizers like LooPo (@pxref{Gri04}).
Thus it is very
compilable code oriented and provides powerful program transformation
facilities. Mainly, it allows the user to specify very general schedules where, 
e.g., unimodularity or invertibility of the transformation doesn't matter.

The current version is still under
evaluation, and there is no guarantee that the upward compatibility
will be respected (but the previous API has been stable for two years,
we hope this one will be as successful -and we believe it-).
A lot of reports are necessary to freeze the library
API and the input file shape. Most API changes from 0.12.x to 0.14.x
have been requested by the users themselves.
Thus you are very welcome and encouraged
to post reports on bugs, wishes, critics, comments, suggestions or
successful experiences in the forum of @code{http://www.CLooG.org}
or to send them to cedric.bastoul@@inria.fr directly.

@menu
* Basics::
* Scattering::
@end menu

@node Basics
@section Basically, what's the point ?
If you want to use CLooG, this is because you want to scan or to find
something inside the integral points of a set of polyhedra. There are many
reasons for that. Maybe you need the generated code itself because it
actually implements a very smart program transformation you found.
Maybe you want to use the generated code
because you know that the solution of your problem belongs to the integral
points of those damned polyhedra and you don't know which one. Maybe you just
want to know if a polyhedron has integral points depending on some parameters,
which is the lexicographic minimum, maximum, the third on the basis of the
left etc. Probably you have your own reasons to use CLooG.

Let us illustrate a basic use of CLooG. Suppose we have a set of affine
constraints that describes a part of a whatever-dimensional space,
called a @strong{domain}, and we
want to scan it. Let us consider for instance the following set of constraints
where @samp{i}
and @samp{j} are the unknown (the two dimensions of the space) and
@samp{m} and @samp{n} are the parameters (some symbolic constants):
@example
@group
2<=i<=n
2<=j<=m
j<=n+2-i
@end group
@end example
Let us also consider that we have a partial knowledge of the parameter values,
called the @strong{context}, expressed as affine constraints as well,
for instance:
@example
@group
m>=2
n>=2
@end group
@end example
Note that using parameters is optional, if you are not comfortable with
parameter manipulation, just replace them with any scalar value that fits
@code{m>=2} and @code{n>=2}.
A graphical representation of this part of the 2-dimensional space, where
the integral points are represented using heavy dots would be for instance:

@image{images/basic,6cm}

The affine constraints of both the domain and the context are what we will
provide to CLooG as input (in a particular shape that will be described later).
The output of CLooG is a pseudo-code to scan the integral points of the
input domain according to the context:
@example
@group
for (i=2;i<=n;i++) @{
  for (j=2;j<=min(m,-i+n+2);j++) @{    
    S1(i,j) ;
  @}
@}
@end group
@end example
If you felt such a basic example is yet interesting, there is a good chance
that CLooG is appropriate for you. CLooG can do much more: scanning several
polyhedra or unions of polyhedra at the same time, applying general affine
transformations to the polyhedra, generate compilable code etc. Welcome
to the CLooG's user's guide !

@node Scattering
@section Defining a Scanning Order: Scattering Functions
In CLooG, domains only define the set of integral points to scan and their
coordinates. In particular, CLooG is free to choose the scanning order for
generating the most efficient code. This means, for optimizing/parallelizing
compiler people, that CLooG doesn't make any speculation on dependences on and
between statements (by the way, it's not its job !).
For instance, if an user give to
CLooG only two domains @code{S1:1<=i<=n}, @code{S2:1<=i<=n} and the context
@code{n>=1}, the following pseudo-codes are considered to be equivalent:

@example
@group
/* A convenient target pseudo-code. */
for (i=1;i<=N;i++) @{
 S1(i) ;
@}
for (i=1;i<=N;i++) @{
 S2(i) ;
@}
@end group
@end example

@example
@group
/* Another convenient target pseudo-code. */
for (i=1;i<=N;i++) @{
 S1(i) ;
 S2(i) ;
@}
@end group
@end example

The default behaviour
of CLooG is to generate the second one, since it is optimized in control. 
It is right if there are no data dependences
between @code{S1} and @code{S2}, but wrong otherwise. 

Thus it is often useful to force scanning to respect a given order. This can be
done in CLooG by using @strong{scattering functions}. Scattering is a
shortcut for scheduling, allocation, chunking functions and the like we can
find in the restructuring compilation literature. There are a lot of reasons
to scatter the integral points of the domains (i.e. the statement instances
of a program, for compilation people), parallelization or optimization are good
examples. For instance, if the user wants for any reason to set some
precedence constraints between the statements of our example above
in order to force the generation of the
first code, he can do it easily by setting (for example) the following
scheduling functions:

@tex
$$\theta _{S1}(i) =  (1)$$
$$\theta _{S2}(j) =  (2)$$
@end tex

@ifnottex
@example
@group
T_S1(i) = (1)
T_S2(j) = (2)
@end group
@end example
@end ifnottex

This scattering means that each integral point of the domain @code{S1}
is scanned at logical date @code{1} while each integral point of the domain
@code{S2} is scanned at logical date @code{2}. As a result, the whole
domain @code{S1} is scanned before domain @code{S2} and the first code in our
example is generated.

The user can set every kind of affine scanning order thanks to the
scattering functions. Each domain has its own scattering function and
each scattering function may be multi-dimensional. A multi-dimensional logical
date may be seen as classical date (year,month,day,hour,minute,etc.) where
the first dimensions are the most significant. Each scattering dimension
may depend linearly on the original dimensions (e.g., @code{i}), the
parameters (e.g., @code{n}) ans scalars (e.g., @code{2}).

A very useful example of multi-dimensional scattering functions is, for
compilation people, the scheduling of the original program.
The basic data to use for code generation are statement iteration domains.
As we saw, these data are not sufficient to rebuild the original
program (what is the ordering between instances of different statements ?).
The missing data can be put in the scattering functions as the original
scheduling. The method to compute it is quite simple (@pxref{Fea92}). The idea is to
build an abstract syntax tree of the program and to read the scheduling for
each statement. For instance, let us consider the following implementation of
a Cholesky factorization:

@example
@group
/* A Cholesky factorization kernel. */
for (i=1;i<=N;i++) @{
  for (j=1;j<=i-1;j++) @{
    a[i][i] -= a[i][j] ;           /* S1 */
  @}
  a[i][i] = sqrt(a[i][i]) ;        /* S2 */
  for (j=i+1;j<=N;j++) @{
    for (k=1;k<=i-1;k++) @{
      a[j][i] -= a[j][k]*a[i][k] ; /* S3 */
    @}
    a[j][i] /= a[i][i] ;           /* S4 */
    @}
  @}
@}
@end group
@end example

The corresponding abstract syntax tree is given in the following figure.
It directly gives the scattering functions (schedules) for all the
statements of the program.

@image{images/tree,6cm}

@tex
$$
\hbox{$ \cases{ \theta _{S1}(i,j)^T    &$=  (0,i,0,j,0)^T$\cr
                \theta _{S2}(i)        &$=  (0,i,1)^T$\cr
                \theta _{S3}(i,j,k)^T  &$=  (0,i,2,j,0,k,0)^T$\cr
                \theta _{S4}(i,j)^T    &$=  (0,i,2,j,1)^T$}$}
$$
@end tex

@ifnottex
@example
@group
T_S1(i,j)^T   = (0,i,0,j,0)^T
T_S2(i)       = (0,i,1)^T
T_S3(i,j,k)^T = (0,i,2,j,0,k,0)^T
T_S4(i,j)^T   = (0,i,2,j,1)^T
@end group
@end example
@end ifnottex

These schedules depend on the iterators and give for each instance of each
statement a unique execution date. Using such scattering functions allow
CLooG to re-generate the input code. 





@c %  ***********************Using the CLooG Software **************************
@node CLooG Software
@chapter Using the CLooG Software


@menu
* A First Example::
* Writing The Input File::
* Calling CLooG::
* CLooG Options::
* Full Example::
@end menu

@c %/*************************************************************************
@c % *                              A FIRST EXAMPLE                          *
@c % *************************************************************************/
@node A First Example
@section A First Example
CLooG takes as input a file that must be written accordingly to a grammar
described in depth in a further section (@pxref{Writing The Input File}). 
Moreover it supports many options to tune the target code presentation or
quality as discussed in a dedicated section (@pxref{Calling CLooG}).
However, a basic use
of CLooG is not very complex and we present in this section how to generate the
code corresponding to a basic example discussed earlier (@pxref{Basics}).

The problem is to find the code that scans a 2-dimensional polyhedron
where @samp{i} and @samp{j} are the unknown (the two dimensions of the space)
and @samp{m} and @samp{n} are the parameters (the symbolic constants),
defined by the following set of constraints:
@example
@group
2<=i<=n
2<=j<=m
j<=n+2-i
@end group
@end example
@noindent We also consider a partial knowledge of the parameter values,
expressed thanks to the following affine constraints:
@example
@group
m>=2
n>=2
@end group
@end example

An input file that corresponds to this problem, and asks for a generated
code in C, may be the following. Note that we do not describe here precisely
the structure and the components of this file (@pxref{Writing The Input File}
 for such information, if you feel it necessary):

@example
# ---------------------- CONTEXT ----------------------
c # language is C

# Context (constraints on two parameters)
2 4                   # 2 lines and 4 columns
# eq/in m  n  1         eq/in: 1 for inequality >=0, 0 for equality =0
    1   1  0 -2       # 1*m + 0*n -2*1 >= 0, i.e. m>=2
    1   0  1 -2       # 0*m + 1*n -2*1 >= 0, i.e. n>=2

1 # We want to set manually the parameter names
m n                   # parameter names

# --------------------- STATEMENTS --------------------
1 # Number of statements

1 # First statement: one domain
# First domain
5 6                   # 5 lines and 6 columns
# eq/in i  j  m  n  1 
    1   1  0  0  0 -2 # i >= 2
    1  -1  0  0  1  0 # i <= n
    1   0  1  0  0 -2 # j >= 2
    1   0 -1  1  0  0 # j <= m
    1  -1 -1  0  1  2 # n+2-i>=j
0  0  0               # for future options

1 # We want to set manually the iterator names
i j                   # iterator names

# --------------------- SCATTERING --------------------
0 # No scattering functions
@end example

This file may be called @samp{basic.cloog}
(this example is provided in the CLooG distribution as
@code{test/manual_basic.cloog}) and we can ask CLooG to process it
and to generate the code by a simple calling to CLooG with this file as input:
@samp{cloog basic.cloog}. By default, CLooG will print the generated code in
the standard output:

@example
@group
/* Generated by CLooG v@value{VERSION} in 0.00s. */
for (i=2;i<=n;i++) @{
  for (j=2;j<=min(m,-i+n+2);j++) @{    
    S1(i,j) ;
  @}
@}
@end group
@end example

@c %/*************************************************************************
@c % *                                Input file                             *
@c % *************************************************************************/
@node Writing The Input File
@section Writing The Input File
The input text file contains a problem description, i.e. the context,
the domains and the scattering functions.
Because CLooG is very 'compilable code generation oriented', we can associate
some additional informations to each domain. We call this association a
@emph{statement}. The set of all informations is 
called a @emph{program}. The input file respects the grammar below
(terminals are preceded by "_"):

@example
File             ::= Program
Program          ::= Context Statements Scattering
Context          ::= Language      Domain_union   Naming
Statements       ::= Nb_statements Statement_list Naming
Scatterings      ::= Nb_functions  Scattering_list Naming
Naming           ::= Option Name_list
Name_list        ::= _String   Name_list      | (void)
Statement_list   ::= Statement Statement_list | (void)
Domain_list      ::= _Domain   Domain_list    | (void)
Scattering_list  ::= Domain_union Scattering_list | (void)
Statement        ::= Iteration_domain 0 0 0
Iteration_domain ::= Domain_union
Domain_union     ::= Nb_domains Domain_list
Option           ::= 0 | 1
Language         ::= c | f
Nb_statements    ::= _Integer
Nb_domains       ::= _Integer
Nb_functions     ::= _Integer
@end example

Note: if there is only one domain in a @samp{Domain_union},
i.e., if @samp{Nb_domains} is 1, then this 1 may be omitted.

@itemize @bullet
@item  @samp{Context} represents the informations that are
       shared by all the statements. It consists on
       the language used (which can be @samp{c} for C or @samp{f} for FORTRAN 90)
       and the global constraints on parameters.
       These constraints are essential
       since they give to CLooG the number of parameters. If there is no
       parameter or no constraints on parameters, just give a constraint
       always satisfied like @math{1 \geq 0}. @samp{Naming} sets the parameter
       names.
       If the naming option @samp{Option} is 1, parameter names will be read
       on the next line. There must be exactly as many names as parameters.
       If the naming option @samp{Option} is 0, parameter names are
       automatically generated. The name of the first parameter will
       be @samp{M}, and the name of the @math{(n+1)^{th}} parameter directly
       follows the name of the @math{n^{th}} parameter in ASCII code.
       It is the user responsibility to ensure that parameter names,
       iterators and scattering dimension names are different. 
@item  @samp{Statements} represents the informations on the statements.
       @samp{Nb_statements} is the number of statements in the program, 
       i.e. the number of @samp{Statement} items in the @samp{Statement_list}.
       @samp{Statement} represents the informations on a given statement.
       To each statement is associated a domain
       (the statement iteration domain: @samp{Iteration_domain}) and three
       zeroes that represents future options.
       @samp{Naming} sets the iterator names. If the naming option
       @samp{Option} is 1, the iterator names
       will be read on the next line. There must be exactly as many names as
       nesting level in the deepest iteration domain. If the naming option
       @samp{Option} is 0, iterator names are automatically generated.
       The iterator name of the outermost loop will be @samp{i}, and the
       iterator name of the loop at level @math{n+1} directly follows the 
       iterator name of the loop at level @math{n} in ASCII code. 
@item  @samp{Scatterings} represents the informations on scattering functions.
       @samp{Nb_functions} is the number of functions (it must be
       equal to the number of statements or 0 if there is no scattering
       function). The functions themselves are represented through
       @samp{Scattering_list}.
       @samp{Naming} sets the scattering dimension names. If the naming option
       @samp{Option} is 1, the scattering dimension names will be read on the
       next line.
       There must be exactly as many names as scattering dimensions. If the
       naming option @samp{Option} is 0, scattering dimension names are automatically
       generated. The name of the @math{n^{th}} scattering dimension
       will be @samp{cn}.
@end itemize

@menu
* Domain Representation::
* Scattering Representation::
@end menu

@node Domain Representation
@subsection Domain Representation
As shown by the grammar, the input file describes the various informations
thanks to characters, integers and domains. Each domain is defined by a set of
constraints in the PolyLib format (@pxref{Wil93}). They have the
following syntax:
@enumerate
@item some optional comment lines beginning with @samp{#},
@item the row and column numbers, possibly followed by comments,
@item the constraint rows, each row corresponds to a constraint the
      domain have to satisfy. Each row must be on a single line and is possibly
      followed by comments. The constraint is an equality @math{p(x) = 0} if the
      first element is 0, an inequality  @math{p(x) \geq 0} if the first element
      is 1. The next elements are the unknown coefficients, followed by
      the parameter coefficients. The last element is the constant factor.
@end enumerate
For instance, assuming that @samp{i}, @samp{j} and @samp{k} are iterators and
@samp{m} and @samp{n} are parameters, the domain defined by the following
constraints :

@tex
$$
\hbox{$ \cases{ -i     + m &$\geq 0$\cr
                    -j + n &$\geq 0$\cr
                 i + j - k &$\geq 0$}$}
$$
@end tex

@ifnottex
@example
@group
   -i + m >= 0
   -j + n >= 0
i + j - k >= 0
@end group
@end example
@end ifnottex

@noindent can be written in the input file as follows :

@example
@group
# This is the domain
3 7                      # 3 lines and 7 columns
# eq/in i  j  k  m  n  1 
    1  -1  0  0  1  0  0 #    -i + m >= 0
    1   0 -1  0  0  1  0 #    -j + n >= 0
    1   1  1 -1  0  0  0 # i + j - k >= 0
@end group
@end example

Each iteration domain @samp{Iteration_domain} of a given statement
is a union of polyhedra
@samp{Domain_union}. A union is defined by its number of elements
@samp{Nb_domains} and the elements themselves @samp{Domain_list}.
For instance, let us consider the following pseudo-code:

@example
@group
for (i=1;i<=n;i++) @{
  if ((i >= m) || (i <= 2*m))
    S1 ;
  for (j=i+1;j<=m;j++)
    S2 ;
@} 
@end group
@end example

@noindent The iteration domain of @samp{S1} can be divided into two
polyhedra and written in the input file as follows:

@example
@group
2 # Number of polyhedra in the union
# First domain
3 5                # 3 lines and 5 columns
# eq/in i  m  n  1 
    1   1  0  0 -1 #  i >= 1
    1  -1  0  1  0 #  i <= n
    1   1 -1  0  0 #  i >= m
# Second domain
3 5                # 3 lines and 5 columns
# eq/in i  m  n  1 
    1   1  0  0 -1 #  i >= 1
    1  -1  0  1  0 #  i <= n
    1  -1  2  0  0 #  i <= 2*m
@end group
@end example

@node Scattering Representation
@subsection Scattering Function Representation
Scattering functions are depicted in the input file thanks a representation
very close to the domain one.
An integer gives the number of functions @samp{Nb_functions} and each function
is represented by a domain. Each line of the domain corresponds to an equality
defining a dimension of the function. Note that at present
(CLooG @value{VERSION})
@strong{all functions must have the same scattering dimension number}. If a
user wants to set scattering functions with different dimensionality, he has
to complete the smaller one with zeroes to reach the maximum dimensionality.
For instance, let us consider the following code and
scheduling functions:

@example
@group
for (i=1;i<=n;i++) @{
  if ((i >= m) || (i <= 2*m))
    S1 ;
  for (j=i+1;j<=m;j++)
    S2 ;
@} 
@end group
@end example

@tex
$$
\hbox{$ \cases{ \theta _{S1}(i)      &$=  (i,0)^T$\cr
                \theta _{S2}(i,j)^T  &$=  (n,i+j)^T$}$}
$$
@end tex

@ifnottex
@example
@group
T_S1(i)     = (i,0)^T
T_S2(i,j)^T = (n,i+j)^T
@end group
@end example
@end ifnottex


@noindent This scheduling can be written in the input file as follows:

@example
@group
2 # Number of scattering functions
# First function
2 7                          # 2 lines and 7 columns
# eq/in c1 c2  i  m  n  1 
    0    1  0 -1  0  0  0    #  c1 = i
    0    0  1  0  0  0  0    #  c2 = 0
# Second function
2 8                          # 2 lines and 8 columns
# eq/in c1 c2  i  j  m  n  1 
    0    1  0  0  0  0 -1  0 #  c1 = n
    0    0  1 -1 -1  0  0  0 #  c2 = i+j
@end group
@end example
The complete input file for the user who wants to generate the code for this
example with the preceding scheduling would be
(this file is provided in the CLooG distribution
as @code{test/manual_scattering.cloog}:

@example
# ---------------------- CONTEXT ----------------------
c # language is C

# Context (no constraints on two parameters)
1 4                   # 1 lines and 4 columns
# eq/in m  n  1
    1   0  0  0       # 0 >= 0, always true

1 # We want to set manually the parameter names
m n                   # parameter names

# --------------------- STATEMENTS --------------------
2 # Number of statements

2 # First statement: two domains
# First domain
3 5                   # 3 lines and 5 columns
# eq/in i  m  n  1
    1   1  0  0 -1    # i >= 1
    1  -1  0  1  0    # i <= n
    1   1 -1  0  0    # i >= m
# Second domain
3 5                   # 3 lines and 5 columns
# eq/in i  m  n  1 
    1   1  0  0 -1    # i >= 1
    1  -1  0  1  0    # i <= n
    1  -1  2  0  0    # i <= 2*m
0  0  0               # for future options
 
1 # Second statement: one domain
4 6                   # 4 lines and 6 columns
# eq/in i  j  m  n  1 
    1   1  0  0  0 -1 # i >= 1
    1  -1  0  0  1  0 # i <= n
    1  -1  1  0  0 -1 # j >= i+1
    1   0 -1  1  0  0 # j <= m
0  0  0               # for future options

1 # We want to set manually the iterator names
i j                   # iterator names

# --------------------- SCATTERING --------------------
2 # Scattering functions
# First function
2 7                   # 2 lines and 7 columns
# eq/in p1 p2  i  m  n  1 
    0    1  0 -1  0  0  0    # p1 = i
    0    0  1  0  0  0  0    # p2 = 0
# Second function
2 8                   # 2 lines and 8 columns
# eq/in p1 p2  i  j  m  n  1 
    0    1  0  0  0  0 -1  0 # p1 = n
    0    0  1 -1 -1  0  0  0 # p2 = i+j

1 # We want to set manually the scattering dimension names
p1 p2                 # scattering dimension names
@end example


@c %/*************************************************************************
@c % *                             Calling CLooG                             *
@c % *************************************************************************/
@node Calling CLooG
@section Calling CLooG
CLooG is called by the following command:
@example
       cloog [ options | file ]
@end example
The default behavior of CLooG is to read the input informations from a file and
to print the generated code or pseudo-code on the standard output.
CLooG's behavior and the output code shape is under the user control thanks
to many options which are detailed a further section (@pxref{CLooG Options}).
@code{file} is the input file. @code{stdin} is a special value: when used,
input is standard input. For instance, we can call CLooG to treat the
input file @code{basic.cloog} with default options by typing:
@code{cloog basic.cloog} or @code{more basic.cloog | cloog stdin}.

@c %/*************************************************************************
@c % *                             CLooG Options                             *
@c % *************************************************************************/
@node CLooG Options
@section CLooG Options

@menu
* Last Depth to Optimize Control::
* First Depth to Optimize Control::
* Statement-wise First and Last Depths to Optimize Control
* Simplify Convex Hull::
* Once Time Loop Elimination::
* Equality Spreading::
* First Level for Spreading::
* Statement Block::
* Loop Strides::
* Unrolling::
* Compilable Code::
* Output::
* OpenScop::
* Help::
* Version ::
* Quiet ::
@end menu

@node Last Depth to Optimize Control
@subsection Last Depth to Optimize Control @code{-l <depth>}

@code{-l <depth>}: this option sets the last loop depth to be optimized in
control. The higher this depth, the less control overhead.
For instance, with some input file, a user can generate
different pseudo-codes with different @code{depth} values as shown below.
@example
@group
/* Generated using a given input file and @strong{option -l 1} */
for (i=0;i<=M;i++) @{
  S1 ;
  for (j=0;j<=N;j++) @{
    S2 ;
  @}
  for (j=0;j<=N;j++) @{
    S3 ;
  @}
  S4 ;
@}
@end group
@end example
@example
@group
/* Generated using the same input file but @strong{option -l 2} */
for (i=0;i<=M;i++) @{
  S1 ;
  for (j=0;j<=N;j++) @{
    S2 ;
    S3 ;
  @}
  S4 ;
@}
@end group
@end example
     In this example we can see that this option can change the operation
     execution order between statements. Let us remind that CLooG does not
     make any speculation on dependences between statements
     (@pxref{Scattering}). Thus if nothing (i.e. scattering functions)
     forbids this, CLooG considers the above codes to be equivalent.
     If there is no scattering functions, the minimum value for @code{depth}
     is 1 (in the case of 0, the user doesn't really need a loop generator !),
     and the number of scattering dimensions otherwise (CLooG will warn the
     user if he doesn't respect such constraint).
     The maximum value for depth is -1 (infinity).
     Default value is infinity.

@node First Depth to Optimize Control
@subsection First Depth to Optimize Control @code{-f <depth>}

     @code{-f <depth>}: this option sets the first loop depth to be optimized
     in control. The lower this depth, the less control overhead (and the longer
     the generated code). For instance, with some input file, a user
     can generate different pseudo-codes with different @code{depth} values
     as shown below.
     The minimum value for @code{depth} is 1, and the
     maximum value is -1 (infinity).
     Default value is 1.
@example
@group
/* Generated using a given input file and @strong{option -f 3} */
for (i=1;i<=N;i++) @{
  for (j=1;j<=M;j++) @{
    S1 ;
    if (j >= 10) @{
      S2 ;
    @}
  @}
@}
@end group
@end example
@example
@group
/* Generated using the same input file but @strong{option -f 2} */
for (i=1;i<=N;i++) @{
  for (j=1;j<=9;j++) @{
    S1 ;
  @}
  for (j=10;j<=M;j++) @{
    S1 ;
    S2 ;
  @}
@}
@end group
@end example

@node Statement-wise First and Last Depths to Optimize Control
@subsection Statement-wise First and Last Depths to Optimize Control @code{options->fs, options->ls}

option->f/l (command-line arguments: -f and -l) provide first and last levels to optimize
control overhead at a global level (across the entire program / all statements)
by separating / splitting loops. option->fs/ls allow the equivalent of setting
-f/-l options on a statement-wise basis. Integer arrays options->fs, options->ls should
be allocated by the user with options->fs_ls_size set to the number of elements (always equal
to the number of statements).  For any
given loop, the first and last depths of all statements under it are looked at
to determine if the loop should be separated (max across all fs' and ls' is
taken). A user has to set fs meaningfully, i.e., for eg., if two statements i &
j have a fused loop and fs[i], fs[j] specify separation for that level for stmt
i but not for stmt j, the input is ambiguous and we will in this case not
separate (since a max is taken). options->fs/ls override f/l; if fs/ls are not
set or are set inconsistently (max across ls[i] < max across fs[i]), f/l take
over.

fs/ls can only be set via the library interface for now.

@node Simple Convex Hull
@subsection  Simple Convex Hull @code{-sh <boolean>}

     @code{-sh <boolean>}: this option enables (@code{boolean=1})
     or forbids (@code{boolean=0}) the use of an overapproximation
     of the convex hull that may be easier to compute
     (especially in the isl backend) and that may result in
     simpler bounds.
     This option works only for generated code without
     code duplication (it means, you have to tune @code{-f} and
     @code{-l} options first to generate only a loop nest with internal
     guards). For instance, with the input file @code{test/union.cloog}, a user
     can generate different pseudo-codes  as shown below.
     Default value is 0.
@example
@group
/* Generated using test/union.cloog and @strong{option -f -1 -l 2 -override} */
for (i=0;i<=11;i++) @{
  for (j=max(0,5*i-50);j<=min(15,5*i+10);j++) @{
    if ((i <= 10) && (j <= 10)) @{
      S1 ;
    @}
    if ((i >= 1) && (j >= 5)) @{
      S2 ;
    @}
  @}
@}
@end group
@end example
@example
@group
/* Generated using the same input file but @strong{option -sh 1 -f -1 -l 2 -override} */
for (i=0;i<=11;i++) @{
  for (j=0;j<=15;j++) @{
    if ((i <= 10) && (j <= 10)) @{
      S1 ;
    @}
    if ((i >= 1) && (j >= 5)) @{
      S2 ;
    @}
  @}
@}
@end group
@end example

@node Once Time Loop Elimination
@subsection Once Time Loop Elimination @code{-otl <boolean>}

     @code{-otl <boolean>}: this option allows (@code{boolean=1}) or
     forbids (@code{boolean=0}) the simplification of loops running
     once. Default value is 1.
@example
@group
/* Generated using a given input file and @strong{option -otl 0} */
for (j=i+1;j<=i+1;j++) @{
  S1 ;
@}
@end group
@end example
@example
@group
/* Generated using the same input file but @strong{option -otl 1} */
j = i+1 ;
S1 ;
@end group
@end example


@node Equality Spreading 
@subsection Equality Spreading @code{-esp <boolean>}

     @code{-esp <boolean>}: this option allows (@code{boolean=1}) or
     forbids (@code{boolean=0}) values spreading when there
     are equalities. Default value is 1.
@example
@group
/* Generated using a given input file and @strong{option -esp 0} */
i = M+2 ;
j = N ;
for (k=i;k<=j+M;k++) @{
  S1 ;
@}
@end group
@end example
@example
@group
/* Generated using the same input file but @strong{option -esp 1} */
for (k=M+2;k<=N+M;k++) @{
  S1(i = M+2, j = N) ;
@}
@end group
@end example


@node First Level for Spreading 
@subsection First Level for Spreading @code{-fsp <level>}

     @code{-fsp <level>}: it can be useful to set a
     first level to begin equality spreading. Particularly when using
     scattering functions, the user may want to see the scattering dimension
     values instead of spreading or hiding them. If user has set a
     spreading, @code{level} is
     the first level to start it. Default value is 1.
@example
@group
/* Generated using a given input file and @strong{option -fsp 1} */
for (j=0;j<=N+M;j++) @{
  S1(i = N) ;
@}
for (j=0;j<=N+M;j++) @{
  S1(i = M) ;
@}
@end group
@end example
@example
@group
/* Generated using the same input file but @strong{option -fsp 2} */
c1 = N ;
for (j=0;j<=c1+M;j++) @{
  S1(i = c1) ;
@}
c1 = M ;
for (j=0;j<=N+c1;j++) @{
  S1(i = c1) ;
@}
@end group
@end example


@node Statement Block  
@subsection Statement Block @code{-block <boolean>}

     @code{-block <boolean>}: this option allows (@code{boolean=1}) to
     create a statement block for each new iterator, even if there is only
     an equality. This can be useful in order to parse the generated
     pseudo-code. When @code{boolean} is set to 0 or when the generation
     language is FORTRAN, this feature is disabled. Default value is 0.
@example
@group
/* Generated using a given input file and @strong{option -block 0} */
i = M+2 ;
j = N ;
S1 ;
@end group
@end example
@example
@group
/* Generated using the same input file but @strong{option -block 1} */
@{ i = M+2 ;
  @{ j = N ;
    S1 ;
  @}
@}
@end group
@end example


@node Loop Strides 
@subsection Loop Strides @code{-strides <boolean>}

     @code{-strides <boolean>}: this options allows (@code{boolean=1}) to
     handle non-unit strides for loop increments. This can remove a lot of
     guards and make the generated code more efficient. Default value is 0.
@example
@group
/* Generated using a given input file and @strong{option -strides 0} */
for (i=1;i<=n;i++) @{
  if (i%2 == 0) @{
    S1(j = i/2) ;
  @}
  if (i%4 == 0) @{
    S2(j = i/4) ;
  @}
@}
@end group
@end example
@example
@group
/* Generated using the same input file but @strong{option -strides 1} */
for (i=2;i<=n;i+=2) @{
  S1(j = i/2) ;
  if (i%4 == 0) @{
    S2(j = i/4) ;
  @}
@}
@end group
@end example


@node Unrolling
@subsection First Depth to Unroll @code{-first-unroll <depth>}

    @code{-first-unroll <depth>}: this option sets the first loop depth
    to unroll.  Note that a loop is only unrolled when it is supported
    by the backend.  In case of the isl backend, a loop is unrolled
    if it has a lower bound that can only be incremented
    a fixed (non-parametric) amount of times.


@node Compilable Code
@subsection Compilable Code @code{-compilable <value>}

     @code{-compilable <value>}: this options allows (@code{value} is not 0)
     to generate a compilable code where all parameters have the integral value
     @code{value}. This option creates a macro for each statement. Since
     CLooG do not know anything about the statement sources, it fills the
     macros with a basic increment that computes the total number of
     scanned integral points. The user may change easily the macros according
     to his own needs. This option is possible only if the generated code is
     in C. Default value is 0.
@example
@group
/* Generated using a given input file and @strong{option -compilable 0} */
for (i=0;i<=n;i++) @{
  for (j=0;j<=n;j++) @{
    S1 ;
    S2 ;
  @}
  S3 ;
@}
@end group
@end example
@example
/* Generated using the same input file but @strong{option -compilable 10} */
/* DON'T FORGET TO USE -lm OPTION TO COMPILE. */

/* Useful headers. */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

/* Parameter value. */
#define PARVAL 10

/* Statement macros (please set). */
#define S1(i,j) @{total++;@}
#define S2(i,j) @{total++;@}
#define S3(i)   @{total++;@}

int main() @{
  /* Original iterators. */
  int i, j ;
  /* Parameters. */
  int n=PARVAL, total=0 ;

  for (i=0;i<=n;i++) @{
    for (j=0;j<=n;j++) @{
      S1(i,j) ;
      S2(i,j) ;
    @}
    S3(i) ;
  @}

  printf("Number of integral points: %d.\n",total) ;
  return 0 ;
@}
@end example

@node Callable Code
@subsection Callable Code @code{-callable <boolean>}

     @code{-callable <boolean>}: if @code{boolean=1}, then a @code{test}
     function will be generated that has the parameters as arguments.
     Similarly to the @code{-compilable} option,
     a macro for each statement is generated.  The generated definitions of
     these macros are as used during the correctness testing, but they
     can easily be changed by the user to suit her own needs.
     This option is only available if the target language is C.
     The default value is 0.

@example
/* Generated from double.cloog with @strong{option -callable 0} */
for (i=0;i<=M;i++) @{
  S1 ;
  for (j=0;j<=N;j++) @{
    S2 ;
    S3 ;
  @}
  S4 ;
@}
@end example
@example
/* Generated from double.cloog with @strong{option -callable 1} */
extern void hash(int);

/* Useful macros. */
#define floord(n,d) (((n)<0) ? ((n)-(d)+1)/(d) : (n)/(d))
#define ceild(n,d)  (((n)<0) ? (n)/(d) : ((n)+(d)+1)/(d))
#define max(x,y)    ((x) > (y) ? (x) : (y))
#define min(x,y)    ((x) < (y) ? (x) : (y))

#define S1(i) @{ hash(1); hash(i); @}
#define S2(i,j) @{ hash(2); hash(i); hash(j); @}
#define S3(i,j) @{ hash(3); hash(i); hash(j); @}
#define S4(i) @{ hash(4); hash(i); @}

void test(int M, int N)
@{
  /* Original iterators. */
  int i, j;
  for (i=0;i<=M;i++) @{
    S1(i) ;
    for (j=0;j<=N;j++) @{
      S2(i,j) ;
      S3(i,j) ;
    @}
    S4(i) ;
  @}
@}
@end example

@node Output
@subsection Output @code{-o <output>}

     @code{-o <output>}: this option sets the output file. @code{stdout} is a
     special value: when used, output is standard output.
     Default value is @code{stdout}.

@node OpenScop
@subsection OpenScop @code{-openscop}

     @code{-openscop}: this option states that the input file complies to
     the OpenScop specification instead of the native file format
     (@pxref{Bas11}). This option is available only if the OpenScop
     support has been enabled at compile time (@pxref{Optional Features}).
     The following OpenScop extensions are supported by CLooG
     (for the details about those extensions, @pxref{Bas11}):
     @itemize @bullet
     @item @emph{scatnames} to set the scattering dimension names.
     @item @emph{coordinates} to inject the generated code at the
           place of a given SCoP in a given file. The use of
           this extension is disabled when the options
           @emph{-compilable} or @emph{-callable} are set.
     @item @emph{loop} to add loop decorations such as OpenMP
           or vectorization pragmas.
     @end itemize

@node Help
@subsection Help @code{--help} or @code{-h}

     @code{--help} or @code{-h}: this option ask CLooG to print a short help.

@node Version
@subsection Version @code{--version} or @code{-v}

     @code{--version} or @code{-v}: this option ask CLooG to print some version
     informations.

@node Quiet
@subsection Quiet @code{--quiet} or @code{-q}

     @code{--quiet} or @code{-q}: this option tells CLooG not to print
     any informational messages.


@c %/*************************************************************************
@c % *                           A Full Example                              *
@c % *************************************************************************/
@node Full Example
@section A Full Example

Let us consider the allocation problem of a Gaussian elimination, i.e. we want
to distribute the various statement instances of the compute kernel onto
different processors. The original code is the following:
@example
@group
for (i=1;j<=N-1;i++) @{
  for (j=i+1;j<=N;j++) @{
    c[i][j] = a[j][i]/a[i][i] ;    /* S1 */
    for (k=i+1;k<=N;k++) @{
      a[j][k] -= c[i][j]*a[i][k] ; /* S2 */
    @}
  @}
@}
@end group
@end example

@noindent The best affine allocation functions can be found by any good automatic
parallelizer like LooPo (@pxref{Gri04}):

@tex
$$
\hbox{$ \cases{ \theta _{S1}(i,j)^T    &$=  (i)$\cr
                \theta _{S2}(i,j,k)^T  &$=  (k)$}$}
$$
@end tex

@ifnottex
@example
@group
T_S1(i,j)^T   = (i)
T_S2(i,j,k)^T = (k)
@end group
@end example
@end ifnottex

@noindent To ensure that on each processor, the set of statement instances is
executed according to the original ordering, we add as minor scattering
dimensions the original scheduling (@pxref{Scattering}):

@tex
$$
\hbox{$ \cases{ \theta _{S1}(i,j)^T    &$=  (i,0,i,0,j,0)^T$\cr
                \theta _{S2}(i,j,k)^T  &$=  (k,0,i,0,j,1,k,0)^T$}$}
$$
@end tex

@ifnottex
@example
@group
T_S1(i,j)^T   = (i,0,i,0,j,0)^T
T_S2(i,j,k)^T = (k,0,i,0,j,1,k,0)^T
@end group
@end example
@end ifnottex

@noindent To ensure that the scattering functions have the same dimensionality, we
complete the first function with zeroes
(this is a CLooG @value{VERSION} and previous versions requirement,
it should be removed in a future version, don't worry it's absolutely legal !):

@tex
$$
\hbox{$ \cases{ \theta _{S1}(i,j)^T    &$=  (i,0,i,0,j,0,0,0)^T$\cr
                \theta _{S2}(i,j,k)^T  &$=  (k,0,i,0,j,1,k,0)^T$}$}
$$
@end tex

@ifnottex
@example
@group
T_S1(i,j)^T   = (i,0,i,0,j,0,0,0)^T
T_S2(i,j,k)^T = (k,0,i,0,j,1,k,0)^T
@end group
@end example
@end ifnottex

@noindent The input file corresponding to this code generation problem
could be (this file is provided in the CLooG distribution
as @code{test/manual_gauss.cloog}:

@example
# ---------------------- CONTEXT ----------------------
c # language is C

# Context (no constraints on one parameter)
1 3                     # 1 line and 3 columns    
# eq/in n  1
    1   0  0            # 0 >= 0, always true

1 # We want to set manually the parameter name
n                       # parameter name

# --------------------- STATEMENTS --------------------
2 # Number of statements

1 # First statement: one domain
4 5                     # 4 lines and 3 columns
# eq/in i  j  n  1
    1   1  0  0 -1      # i >= 1
    1  -1  0  1 -1      # i <= n-1
    1  -1  1  0 -1      # j >= i+1
    1   0 -1  1  0      # j <= n
0  0  0                 # for future options
 
1
# Second statement: one domain
6 6                     # 6 lines and 3 columns
# eq/in i  j  k  n  1
    1   1  0  0  0 -1   # i >= 1
    1  -1  0  0  1 -1   # i <= n-1
    1  -1  1  0  0 -1   # j >= i+1
    1   0 -1  0  1  0   # j <= n
    1  -1  0  1  0 -1   # k >= i+1
    1   0  0 -1  1  0   # k <= n
0  0  0                 # for future options

0 # We let CLooG set the iterator names

# --------------------- SCATTERING --------------------
2 # Scattering functions
# First function
8 13                    # 3 lines and 3 columns
# eq/in p1 p2 p3 p4 p5 p6 p7 p8  i  j  n  1
    0    1  0  0  0  0  0  0  0 -1  0  0  0     # p1 = i
    0    0  1  0  0  0  0  0  0  0  0  0  0     # p2 = 0
    0    0  0  1  0  0  0  0  0 -1  0  0  0     # p3 = i
    0    0  0  0  1  0  0  0  0  0  0  0  0     # p4 = 0
    0    0  0  0  0  1  0  0  0  0 -1  0  0     # p5 = j
    0    0  0  0  0  0  1  0  0  0  0  0  0     # p6 = 0
    0    0  0  0  0  0  0  1  0  0  0  0  0     # p7 = 0
    0    0  0  0  0  0  0  0  1  0  0  0  0     # p8 = 0
# Second function
8 14                    # 3 lines and 3 columns
# eq/in p1 p2 p3 p4 p5 p6 p7 p8  i  j  k  n  1
    0    1  0  0  0  0  0  0  0  0  0 -1  0  0  # p1 = k
    0    0  1  0  0  0  0  0  0  0  0  0  0  0  # p2 = 0
    0    0  0  1  0  0  0  0  0 -1  0  0  0  0  # p3 = i
    0    0  0  0  1  0  0  0  0  0  0  0  0  0  # p4 = 0
    0    0  0  0  0  1  0  0  0  0 -1  0  0  0  # p5 = j
    0    0  0  0  0  0  1  0  0  0  0  0  0 -1  # p6 = 1
    0    0  0  0  0  0  0  1  0  0  0 -1  0  0  # p7 = k
    0    0  0  0  0  0  0  0  1  0  0  0  0  0  # p8 = 0

1 # We want to set manually the scattering dimension names
p1 p2 p3 p4 p5 p6 p7 p8 # scattering dimension names
@end example

Calling CLooG, with for instance the command line
@code{cloog -fsp 2 gauss.cloog} for a better view
of the allocation (the processor number is given by @code{p1}),
will result on the following target code that actually implements
the transformation. A minor processing on the dimension @code{p1}
to implement, e.g., MPI calls, which is not shown here may
result in dramatic speedups !

@example
if (n >= 2) @{
  p1 = 1 ;
  for (p5=2;p5<=n;p5++) @{
    S1(i = 1,j = p5) ;
  @}
@}
for (p1=2;p1<=n-1;p1++) @{
  for (p3=1;p3<=p1-1;p3++) @{
    for (p5=p3+1;p5<=n;p5++) @{
      S2(i = p3,j = p5,k = p1) ;
    @}
  @}
  for (p5=p1+1;p5<=n;p5++) @{
    S1(i = p1,j = p5) ;
  @}
@}
if (n >= 2) @{
  p1 = n ;
  for (p3=1;p3<=n-1;p3++) @{
    for (p5=p3+1;p5<=n;p5++) @{
      S2(i = p3,j = p5,k = n) ;
    @}
  @}
@}
@end example


@c %/*************************************************************************
@c % *                           A Full Example                              *
@c % *************************************************************************/
@node CLooG Library
@chapter Using the CLooG Library
The CLooG Library was implemented to allow the user to call CLooG
directly from his programs, without file accesses or system calls. The
user only needs to link his programs with C libraries. The CLooG
library mainly provides one function (@code{cloog_clast_create_from_input})
which takes as input the problem
description with some options, and returns the data structure corresponding
to the generated code (a @code{struct clast_stmt} structure)
which is more or less an abstract syntax tree.
The user can work with this data structure and/or use
our pretty printing function to write the final code in either C or FORTRAN.
Some other functions are provided for convenience reasons.
These functions as well as the data structures are described in this section.

@menu
* CLooG Data Structures::
* CLooG Output::
* Retrieving version information::
* Example of Library Utilization::
@end menu


@node CLooG Data Structures
@section CLooG Data Structures Description
In this section, we describe the data structures used by the loop
generator to represent and to process a code generation problem.

@menu
* CloogState::
* CloogMatrix::
* CloogDomain::
* CloogScattering::
* CloogUnionDomain::
* CloogStatement::
* CloogOptions::
* CloogInput::
@end menu


@node CloogState
@subsection CloogState
@example
@group
CloogState *cloog_state_malloc(void);
void cloog_state_free(CloogState *state);
@end group
@end example

@noindent The @code{CloogState} structure is (implicitly) needed to perform
any CLooG operation.  It should be created using @code{cloog_state_malloc}
before any other CLooG objects are created and destroyed using
@code{cloog_state_free} after all objects have been freed.
It is allowed to use more than one @code{CloogState} structure at
the same time, but an object created within the state of a one
@code{CloogState} structure is not allowed to interact with an object
created within the state of an other @code{CloogState} structure.

@menu
* CloogState/isl::
@end menu

@node CloogState/isl
@subsubsection isl

@example
#include <cloog/isl/cloog.h>
CloogState *cloog_isl_state_malloc(isl_ctx *ctx);
@end example

@noindent
When using the isl backend, CLooG will internally create many isl objects.
If the user creates any CLooG objects from isl objects (e.g.,
through @code{cloog_domain_from_isl_set} below), then the user needs
to make sure that these isl objects live in the same @code{isl_ctx}
as those created by CLooG internally.  The best way to ensure this
property is to pass the @code{isl_ctx} created by the user to CLooG
by calling @code{cloog_isl_state_malloc} to create a @code{CloogState}.
Note that this makes the created @code{CloogState} a user of the
given @code{isl_ctx}, meaning that the @code{CloogState} needs to
be freed before the @code{isl_ctx} is freed.


@node CloogMatrix
@subsection CloogMatrix

@noindent The @code{CloogMatrix} structure is equivalent to the PolyLib
@code{Matrix} data structure (@pxref{Wil93}). This structure is devoted to
represent a set of constraints.

@example
@group
struct cloogmatrix
@{ unsigned NbRows ;    /* Number of rows. */
  unsigned NbColumns ; /* Number of columns. */
  cloog_int_t **p;     /* Array of pointers to the matrix rows. */
  cloog_int_t *p_Init; /* Matrix rows contiguously in memory. */
@};
typedef struct cloogmatrix CloogMatrix;

CloogMatrix *cloog_matrix_alloc(unsigned NbRows, unsigned NbColumns);
void cloog_matrix_print(FILE *foo, CloogMatrix *m);
void cloog_matrix_free(CloogMatrix *matrix);
@end group
@end example

@noindent The whole matrix is stored in memory row after row at the
@code{p_Init} address. @code{p} is an array of pointers where
@code{p[i]} points to the first element of the @math{i^{th}} row.
@code{NbRows} and @code{NbColumns} are respectively the number of
rows and columns of the matrix. 
Each row corresponds to a constraint. The first element of each row is an
equality/inequality tag. The
constraint is an equality @math{p(x) = 0} if the first element is 0, but it is
an inequality @math{p(x) \geq 0} if the first element is 1.
The next elements are the coefficients of the unknowns,
followed by the coefficients of the parameters, and finally the constant term.
For instance, the following three constraints:

@tex
$$
\hbox{$ \cases{ -i + m       &$= 0$\cr
                -j + n       &$\geq 0$\cr
                 j + i - k   &$\geq 0$}$}
$$
@end tex

@ifnottex
@example
@group
    -i + m  = 0
    -j + n >= 0
 i + j - k >= 0
@end group
@end example
@end ifnottex

@noindent would be represented by the following rows:

@example
@group
# eq/in  i   j   k   m   n   cst
    0    0  -1   0   1   0    0 
    1   -1   0   0   0   1    0 
    1    1   1  -1   0   0    0 
@end group
@end example

@noindent To be able to provide different precision version (CLooG
supports 32 bits, 64 bits and arbitrary precision through the GMP library),
the @code{cloog_int_t} type depends on the configuration options (it may be
@code{long int} for 32 bits version, @code{long long int} for 64 bits version,
and @code{mpz_t} for multiple precision version).

@node CloogDomain
@subsection CloogDomain
@example
@group
CloogDomain *cloog_domain_union_read(CloogState *state,
                                     FILE *input, int nb_parameters);
CloogDomain *cloog_domain_from_cloog_matrix(CloogState *state,
                                    CloogMatrix *matrix, int nb_par);
void cloog_domain_free(CloogDomain *domain);
@end group
@end example

@noindent @code{CloogDomain} is an opaque type representing a polyhedral
domain (a union of polyhedra).
A @code{CloogDomain} can be read
from a file using @code{cloog_domain_union_read} or
converted from a @code{CloogMatrix}.
The input format for @code{cloog_domain_union_read}
is that of @ref{Domain Representation}.
The function @code{cloog_domain_from_cloog_matrix} takes a @code{CloogState}, a
@code{CloogMatrix} and @code{int} as input and returns a pointer to a
@code{CloogDomain}. @code{matrix} describes the domain and @code{nb_par} is the
number of parameters in this domain. The input data structures are neither
modified nor freed.
The @code{CloogDomain} can be freed using @code{cloog_domain_free}.
There are also some backend dependent functions for creating
@code{CloogDomain}s.

@menu
* CloogDomain/PolyLib::
* CloogDomain/isl::
@end menu

@node CloogDomain/PolyLib
@subsubsection PolyLib

@example
#include <cloog/polylib/cloog.h>
CloogDomain *cloog_domain_from_polylib_polyhedron(CloogState *state,
                                        Polyhedron *, int nb_par);
@end example
@noindent
The function @code{cloog_domain_from_polylib_polyhedron} takes a PolyLib
@code{Polyhedron} as input and returns a pointer to a @code{CloogDomain}.
The @code{nb_par} parameter indicates the number of parameters
in the domain.  The input data structure if neither modified nor freed.

@node CloogDomain/isl
@subsubsection isl

@example
#include <cloog/isl/cloog.h>
CloogDomain *cloog_domain_from_isl_set(__isl_take isl_set *set);
__isl_give isl_set *isl_set_from_cloog_domain(CloogDomain *domain);
@end example
@noindent
The function @code{cloog_domain_from_isl_set} takes an
@code{isl_set} as input and returns a pointer to a @code{CloogDomain}.
The function consumes a reference to the given @code{isl_set}.
Similarly, @code{isl_set_from_cloog_domain} consumes a reference
to a @code{CloogDomain} and returns an @code{isl_set}.


@node CloogScattering
@subsection CloogScattering
@example
@group
CloogScattering *cloog_domain_read_scattering(CloogDomain *domain,
                                              FILE *foo);
CloogScattering *cloog_scattering_from_cloog_matrix(CloogState *state,
                         CloogMatrix *matrix, int nb_scat, int nb_par);
void cloog_scattering_free(CloogScattering *);
@end group
@end example

@noindent
The @code{CloogScattering} type represents a scattering function.
A @code{CloogScattering} for a given @code{CloogDomain} can be read
from a file using @code{cloog_scattering_read} or converted
from a @code{CloogMatrix} using @code{cloog_scattering_from_cloog_matrix}.
The function @code{cloog_scattering_from_cloog_matrix} takes a
@code{CloogState}, a @code{CloogMatrix} and two @code{int}s as input and
returns a
pointer to a @code{CloogScattering}.
@code{matrix} describes the scattering, while @code{nb_scat} and
@code{nb_par} are the number of scattering dimensions and
the number of parameters, respectively. The input data structures are
neither modified nor freed.
A @code{CloogScattering} can be freed using @code{cloog_scattering_free}.
There are also some backend dependent functions for creating
@code{CloogScattering}s.

@menu
* CloogScattering/PolyLib::
* CloogScattering/isl::
@end menu

@node CloogScattering/PolyLib
@subsubsection PolyLib

@example
#include <cloog/polylib/cloog.h>
CloogScattering *cloog_scattering_from_polylib_polyhedron(
        CloogState *state, Polyhedron *polyhedron, int nb_par);
@end example
@noindent
The function @code{cloog_scattering_from_polylib_polyhedron} takes a PolyLib
@code{Polyhedron} as input and returns a pointer to a @code{CloogScattering}.
The @code{nb_par} parameter indicates the number of parameters
in the domain.  The input data structure if neither modified nor freed.

@node CloogScattering/isl
@subsubsection isl

@example
#include <cloog/isl/cloog.h>
CloogScattering *cloog_scattering_from_isl_map(__isl_take isl_map *map);
@end example
@noindent
The function @code{cloog_scattering_from_isl_map} takes an
@code{isl_map} as input and returns a pointer to a @code{CloogScattering}.
The output dimensions of the @code{isl_map} correspond to the
scattering dimensions, while the input dimensions correspond to the
domain dimensions.
The function consumes a reference to the given @code{isl_map}.


@node CloogUnionDomain
@subsection CloogUnionDomain
@example
@group
enum cloog_dim_type @{ CLOOG_PARAM, CLOOG_ITER, CLOOG_SCAT @};

CloogUnionDomain *cloog_union_domain_alloc(int nb_par);
CloogUnionDomain *cloog_union_domain_add_domain(CloogUnionDomain *ud,
        const char *name, CloogDomain *domain,
        CloogScattering *scattering, void *usr);
CloogUnionDomain *cloog_union_domain_set_name(CloogUnionDomain *ud,
        enum cloog_dim_type type, int index, const char *name);
void cloog_union_domain_free(CloogUnionDomain *ud);
@end group
@end example

@noindent A @code{CloogUnionDomain} structure represents a union
of scattered named domains.  A @code{CloogUnionDomain} is
initialized by a call to @code{cloog_union_domain_alloc},
after which domains can be added using @code{cloog_union_domain_add_domain}.

@code{cloog_union_domain_alloc} takes the number of parameters as input.
@code{cloog_union_domain_add_domain} takes a previously created
@code{CloogUnionDomain} as input along with an optional name,
a domain, an optional scattering function and a user pointer.
The name may be @code{NULL} and is duplicated if it is not.
If no name is specified, then the statements will be named according
to the order in which they were added.
@code{domain} and @code{scattering} are taken over
by the @code{CloogUnionDomain}.  @code{scattering} may be @code{NULL},
but it must be consistently @code{NULL} or not over all calls
to @code{cloog_union_domain_add_domain}.
@code{cloog_union_domain_set_name} can be used to set the names
of parameters, iterators and scattering dimensions.
The names of iterators and scattering dimensions can only be set
after all domains have been added.

There is also a backend dependent function for creating
@code{CloogUnionDomain}s.

@menu
* CloogUnionDomain/isl::
@end menu

@node CloogUnionDomain/isl
@subsubsection isl

@example
#include <cloog/isl/cloog.h>
CloogUnionDomain *cloog_union_domain_from_isl_union_map(
        __isl_take isl_union_map *umap);
CloogUnionDomain *cloog_union_domain_from_isl_set(
        __isl_take isl_set *set);
@end example
@noindent
The function @code{cloog_union_domain_from_isl_union_map} takes a
@code{isl_union_map} as input and returns a pointer
to a @code{CloogUnionDomain}.
The input is a mapping from different
spaces (different tuple names and possibly different dimensions)
to a common space.  The iteration domains are set to the domains
in each space.  The statement names are set to the names of the
spaces.  The parameter names of the result are set to those of
the input, but the iterator and scattering dimension names are
left unspecified.
The function consumes a reference to the given @code{isl_union_map}.  The
function @code{cloog_union_domain_from_isl_set} is similar, but takes an
unscattered domain as input. It is not defined for an union_set, because the
order of iterations from two different isl_sets is undefined, if no scattering
is provided.


@node CloogStatement
@subsection CloogStatement
@example
@group
struct cloogstatement
@{ int number ;                  /* The statement unique number. */
  char *name;                   /* Name of the statement. */
  void * usr ;                  /* Pointer for user's convenience. */
  struct cloogstatement * next ;/* Next element of the linked list. */
@} ;
typedef struct cloogstatement CloogStatement ;

CloogStatement *cloog_statement_malloc(CloogState *state);
void cloog_statement_print(FILE *, CloogStatement *);
void cloog_statement_free(CloogStatement *);
@end group
@end example

@noindent The @code{CloogStatement} structure represents a @code{NULL}
terminated linked
list of statements. In CLooG, a statement is only defined by its unique
number (@code{number}). The user can use the pointer @code{usr} for his
own convenience to link his own statement representation to the
corresponding @code{CloogStatement} structure. The whole management of the
@code{usr} pointer is under the responsibility of the user, in particular,
CLooG never tries to print, to allocate or to free a memory block pointed
by @code{usr}. 



@node CloogOptions
@subsection CloogOptions
@example
@group
struct cloogoptions
@{ int l;                     /* -l option.                                */
  int f;                     /* -f option.                                 */
  int *ls;                   /* Statement-wise l option                    */
  int *fs;                   /* Statement-wise f option                    */
  int fs_ls_size;            /* Size of the fs and ls arrays (same size)   */
  int strides;               /* -strides option.                           */
  int sh;                    /* -sh option.                                */
  int first_unroll;          /* -first-unroll option.                      */
  int esp;                   /* -esp option.                               */
  int fsp;                   /* -fsp option.                               */
  int otl;                   /* -otl option.                               */
  int block;                 /* -block option.                             */
  int compilable;            /* -compilable option.                        */
  int language;              /* CLOOG_LANGUAGE_C or CLOOG_LANGUAGE_FORTRAN */
  int save_domains;          /* Save unsimplified copy of domain.          */
@} ;
typedef struct cloogoptions CloogOptions ;

CloogOptions *cloog_options_malloc(CloogState *state);
void cloog_options_print(FILE *foo, CloogOptions *options);
void cloog_options_free(CloogOptions *options);
@end group
@end example

@noindent The @code{CloogOptions} structure contains all the possible options to
rule CLooG's behaviour (@pxref{Calling CLooG}).
As a reminder, the default values are:
@itemize @bullet
@item @math{l = -1} (optimize control until the innermost loops),
@item @math{f = 1} (optimize control from the outermost loops),
@item @math{ls/fs = NULL} and @math{fs\_ls\_size = 0} (statement-wise l/f are not set),
@item @math{strides = 0} (use only unit strides),
@item @math{sh = 0} (do not compute simple convex hulls),
@item @math{first\_unroll = -1} (do not perform unrolling),
@item @math{esp = 1} (spread complex equalities),
@item @math{fsp = 1} (start to spread from the first iterators),
@item @math{otl = 1} (simplify loops running only once).
@item @math{block = 0} (do not make statement blocks when not necessary).
@item @math{compilable = 0} (do not generate a compilable code).
@end itemize 

The @code{save_domains} option is only useful for users of the CLooG
library.  This option defaults to 0, but when it is set, the @code{domain}
field of each @code{clast_user_stmt} will be set to the set of values for the
scattering dimensions for which this instance of the user statement is executed.
The @code{domain} field of each @code{clast_for} contains the set of values for
the scattering dimensions for which an instance of a user statement is executed
inside the @code{clast_for}. It is only available if the @code{clast_for}
enumerates a scattering dimension.

@node CloogInput
@subsection CloogInput
@example
@group
CloogInput *cloog_input_read(FILE *file, CloogOptions *options);
CloogInput *cloog_input_alloc(CloogDomain *context,
                                CloogUnionDomain *ud);
void cloog_input_free(CloogInput *input);

void cloog_input_dump_cloog(FILE *, CloogInput *, CloogOptions *);
@end group
@end example

@noindent A @code{CloogInput} structure represents the input to CLooG.
It is essentially a @code{CloogUnionDomain} along with a context
@code{CloogDomain}.  A @code{CloogInput} can be created from
a @code{CloogDomain} and a @code{CloogUnionDomains} using
@code{cloog_input_alloc}, or it can be read from a CLooG input
file using @code{cloog_input_read}.  The latter also modifies
the @code{language} field of the @code{CloogOptions} structure.
The constructed @code{CloogInput} can be used as input
to a @code{cloog_clast_create_from_input} call.

A @code{CloogInput} data structure and a @code{CloogOptions} contain
the same information as a .cloog file. This function dumps the .cloog
description of the given data structures into a file.

@node Dump CLooG Input File Function
@subsection Dump CLooG Input File Function
@example
@end example

@node CLooG Output
@section CLooG Output

@noindent
Given a description of the input,
an AST corresponding to the @code{CloogInput} can be constructed
using @code{cloog_clast_create_from_input} and destroyed using
@code{free_clast_stmt}.
@example
struct clast_stmt *cloog_clast_create_from_input(CloogInput *input,
                                      CloogOptions *options);
void free_clast_stmt(struct clast_stmt *s);
@end example
@noindent
@code{clast_stmt} represents a linked list of ``statements''.
@example
struct clast_stmt @{
    const struct clast_stmt_op    *op;
    struct clast_stmt   *next;
@};
@end example
@noindent
The entries in the list are not of type @code{clast_stmt} itself,
but of some larger type.  The following statement types are defined
by CLooG.

@example
struct clast_root @{
    struct clast_stmt   stmt;
    CloogNames *        names;
@};
struct clast_root *new_clast_root(CloogNames *names);

struct clast_assignment @{
    struct clast_stmt   stmt;
    const char *        LHS;
    struct clast_expr * RHS;
@};
struct clast_assignment *new_clast_assignment(const char *lhs,
                                              struct clast_expr *rhs);

struct clast_block @{
    struct clast_stmt   stmt;
    struct clast_stmt * body;
@};
struct clast_block *new_clast_block(void);

struct clast_user_stmt @{
    struct clast_stmt   stmt;
    CloogDomain *       domain;
    CloogStatement *    statement;
    struct clast_stmt * substitutions;
@};
struct clast_user_stmt *new_clast_user_stmt(CloogDomain *domain,
    CloogStatement *stmt, struct clast_stmt *subs);

struct clast_for @{
    struct clast_stmt   stmt;
    CloogDomain *       domain;
    const char *        iterator;
    struct clast_expr * LB;
    struct clast_expr * UB;
    cloog_int_t         stride;
    struct clast_stmt * body;
@};
struct clast_for *new_clast_for(CloogDomain *domain, const char *it,
                                struct clast_expr *LB, struct clast_expr *UB,
                                cloog_int_t stride);

struct clast_guard @{
    struct clast_stmt   stmt;
    struct clast_stmt * then;
    int                 n;
    struct clast_equation       eq[1];
@};
struct clast_guard *new_clast_guard(int n);
@end example
@noindent
The @code{clast_stmt} returned by @code{cloog_clast_create}
is a @code{clast_root}.
It contains a placeholder for all the variable names that appear
in the AST and a (list of) nested statement(s).

@noindent
A @code{clast_assignment} assigns the value given by
the @code{clast_expr} @code{RHS} to a variable named @code{LHS}.

@noindent
A @code{clast_block} groups a list of statements into one statement.
These statements are only generated if the @code{block} option is set,
@pxref{Statement Block} and @ref{CloogOptions}.

@noindent
A @code{clast_user_stmt} represents a call to a statement specified
by the user, @pxref{CloogStatement}.
@code{substitutions} is a list of @code{clast_assignment} statements
assigning an expression in terms of the scattering dimensions to
each of the original iterators in the original order.
The @code{LHS}s of these assignments are left blank (@code{NULL}).
The @code{domain} is set to @code{NULL} if the @code{save_domains} option
is not set.  Otherwise, it is set to the set
of values for the scattering dimensions
for which this instance of the user statement is executed.
Note that unless the @code{noscalars} option has been set, the
constant scattering dimensions may have been removed from this set.

@noindent
A @code{clast_for} represents a for loop, iterating @code{body} for each
value of @code{iterator} between @code{LB} and @code{UB} in steps
of size @code{stride}.
The @code{domain} is set to @code{NULL} if the @code{save_domains} option is not
set.  Otherwise, it is set to the set of values for the scattering dimensions
for which a user statement is executed inside this @code{clast_for}.  Note that
unless the @code{noscalars} option has been set, the constant scattering
dimensions may have been removed from this set.

@noindent
A @code{clast_guard} represents the guarded execution of the @code{then}
(list of) statement(s) by a conjunction of @code{n} (in)equalities.
Each (in)equality is represented by a @code{clast_equation}.
@example
struct clast_equation @{
    struct clast_expr * LHS;
    struct clast_expr * RHS;
    int                 sign;
@};
@end example
@noindent
The condition expressed by a @code{clast_equation} is
@code{LHS <= RHS}, @code{LHS == RHS} or @code{LHS >= RHS}
depending on whether @code{sign} is less than zero, equal
to zero, or greater than zero.

The dynamic type of a @code{clast_stmt} can be determined
using the macro @code{CLAST_STMT_IS_A(stmt,type)},
where @code{stmt} is a pointer to a @code{clast_stmt}
and @code{type} is one of @code{stmt_root}, @code{stmt_ass},
@code{stmt_user}, @code{stmt_block}, @code{stmt_for} or
@code{stmt_guard}.
Users are allowed to define their own statement types by
assigning the @code{op} field of the statements a pointer
to a @code{clast_stmt_op} structure.
@example
struct clast_stmt_op @{
    void (*free)(struct clast_stmt *);
@};
@end example
@noindent
The @code{free} field of this structure should point
to a function that frees the user defined statement.

@noindent
A @code{clast_expr} can be an identifier, a term,
a binary expression or a reduction.
@example
enum clast_expr_type @{
    clast_expr_name,
    clast_expr_term,
    clast_expr_bin,
    clast_expr_red
@};
struct clast_expr @{
    enum clast_expr_type type;
@};
void free_clast_expr(struct clast_expr *e);
@end example

@noindent
Identifiers are of subtype @code{clast_name}.
@example
struct clast_name @{
    struct clast_expr   expr;
    const char *        name;
@};
struct clast_name *new_clast_name(const char *name);
void free_clast_name(struct clast_name *t);
@end example
@noindent
The character string pointed to by @code{name} is
assumed to be part of the @code{CloogNames} structure
in the root of the clast as is therefore not copied.

@noindent
Terms are of type @code{clast_term}.
@example
struct clast_term @{
    struct clast_expr   expr;
    cloog_int_t         val;
    struct clast_expr  *var;
@};
struct clast_term *new_clast_term(cloog_int_t c, struct clast_expr *v);
void free_clast_term(struct clast_term *t);
@end example
@noindent
If @code{var} is set to @code{NULL}, then the term represents
the integer value @code{val}.  Otherwise, it represents
the term @code{val * var}.
@code{new_clast_term} simply copies the @code{v} pointer
without copying the underlying @code{clast_expr}.
@code{free_clast_term}, on the other hand, recursively frees
@code{var}.

@noindent
Binary expressions are of type @code{clast_bin_type} and
represent either the floor of a division (fdiv),
the ceil of a division (cdiv), an exact division or
the remainder of an fdiv.
@example
enum clast_bin_type @{ clast_bin_fdiv, clast_bin_cdiv, 
                      clast_bin_div, clast_bin_mod @};
struct clast_binary @{
    struct clast_expr   expr;
    enum clast_bin_type type;
    struct clast_expr*  LHS;
    cloog_int_t         RHS;
@};
struct clast_binary *new_clast_binary(enum clast_bin_type t, 
                          struct clast_expr *lhs, cloog_int_t rhs);
void free_clast_binary(struct clast_binary *b);
@end example

@noindent
Reductions are of type @code{clast_reduction} and
can represent either the sum, the minimum or the maximum
of its elements.
@example
enum clast_red_type @{ clast_red_sum, clast_red_min, clast_red_max @};
struct clast_reduction @{
    struct clast_expr   expr;
    enum clast_red_type type;
    int                 n;
    struct clast_expr*  elts[1];
@};
struct clast_reduction *new_clast_reduction(enum clast_red_type t,
                                            int n);
void free_clast_reduction(struct clast_reduction *r);
@end example

@node Retrieving version information
@section Retrieving version information
CLooG provides static and dynamic version checks to assist on
including a compatible version of the library.
A static version check at compile time can be achieved by
querying the version constants defined in @code{version.h}:

@itemize @bullet
@item @code{CLOOG_VERSION_MAJOR}
@item @code{CLOOG_VERSION_MINOR}
@item @code{CLOOG_VERSION_REVISION}
@end itemize

This way it is possible to ensure the included headers are of the
correct version. It is still possible that the installed CLooG
library version differs from the installed headers.
In order to avoid this, a dynamic version check is provided with
the functions:

@example
@group
int cloog_version_major(void);
int cloog_version_minor(void);
int cloog_version_revision(void);
@end group
@end example

By using both the static and the dynamic version check, it is possible
to match CLooG's header version with the library's version.

@node Example of Library Utilization
@section Example of Library Utilization
@menu
* Basic Library Utilization::
* Scanning isl Sets::
* Source to Source Compiler::
@end menu

@node Basic Library Utilization
@subsection Basic Library Utilization
Here is a basic example showing how it is possible to use the CLooG library,
assuming that a standard installation has been done.
The following C program reads a CLooG input file on the standard input,
then prints the solution on the standard output.
Options are preselected to the default values of the CLooG software.
This example is provided in the @code{example} directory of the
CLooG distribution.
@example
/* example.c */
# include <stdio.h>
# include <cloog/cloog.h>

int main() @{
  CloogState *state;
  CloogInput *input;
  CloogOptions *options ;
  struct clast_stmt *root;
  
  /* Setting options and reading program informations. */
  state = cloog_state_malloc();
  options = cloog_options_malloc(state);
  input = cloog_input_read(stdin, options);

  /* Generating and printing the code. */
  root = cloog_clast_create_from_input(input, options);
  clast_pprint(stdout, root, 0, options);

  cloog_clast_free(root);
  cloog_options_free(options) ;
  cloog_state_free(state);
  return 0;
@}
@end example

@noindent The compilation (with default isl/GMP version installed)
command could be:
@example
gcc -DCLOOG_INT_GMP example.c -lcloog-isl -o example
@end example
@noindent A calling command with the input file test.cloog could be:
@example
more test.cloog | ./example
@end example

@node Scanning isl Sets
@subsection Scanning isl Sets
Here is an isl-level example to prepare a convenient input, to generate the
Clast of the scanning code for this input, to pretty-print the code and to
de-allocate memory in a clean way. This example is provided in the
@code{example} directory of the CLooG distribution.

@example
/* example-isl.c */
#include <cloog/cloog.h>
#include <cloog/isl/cloog.h>

/* Input problem */
int nb_parameters = 1;
char *parameter_name[]  = @{"N"@};
char *iterator_name[]   = @{"i", "j"@};
char *scattering_name[] = @{"t0", "t1", "t2"@};
char *str_context       = "[N] -> @{ : N > 0@}";
char *str_domain1       = "[N] -> @{[i, j] : 0 <= i < N and 0 <= j < N@}";
char *str_domain2       = "[N] -> @{[i, j] : 0 <= i < N and 0 <= j < N@}";
char *str_scattering1   = "[N] -> @{[i, j] -> [0, i + j, j]@}";
char *str_scattering2   = "[N] -> @{[i, j] -> [1, i,    -j]@}";

int main() @{
  isl_ctx *ctx;
  isl_set *set_context, *set1, *set2;
  isl_map *map1, *map2;
  CloogDomain *context, *domain1, *domain2;
  CloogScattering *scattering1, *scattering2;
  CloogUnionDomain *domains;
  CloogInput *input;
  CloogState *state;
  CloogOptions *options;
  struct clast_stmt *root;

  /* Build isl structures for context, sets and mapping */
  ctx = isl_ctx_alloc();
  set_context = isl_set_read_from_str(ctx, str_context);
  set1 = isl_set_read_from_str(ctx, str_domain1);
  set2 = isl_set_read_from_str(ctx, str_domain2);
  map1 = isl_map_read_from_str(ctx, str_scattering1);
  map2 = isl_map_read_from_str(ctx, str_scattering2);

  /* Translate them to CLooG context, domains and scattering */
  context = cloog_domain_from_isl_set(set_context);
  domain1 = cloog_domain_from_isl_set(set1);
  domain2 = cloog_domain_from_isl_set(set2);
  scattering1 = cloog_scattering_from_isl_map(map1);
  scattering2 = cloog_scattering_from_isl_map(map2);

  /* Prepare the list of domains to scan */
  domains = cloog_union_domain_alloc(nb_parameters);
  cloog_union_domain_add_domain(domains,"S1",domain1,scattering1,NULL);
  cloog_union_domain_add_domain(domains,"S2",domain2,scattering2,NULL);
  cloog_union_domain_set_name(domains,CLOOG_PARAM,0,parameter_name[0]);
  cloog_union_domain_set_name(domains,CLOOG_ITER, 0,iterator_name[0]);
  cloog_union_domain_set_name(domains,CLOOG_ITER, 1,iterator_name[1]);
  cloog_union_domain_set_name(domains,CLOOG_SCAT, 0,scattering_name[0]);
  cloog_union_domain_set_name(domains,CLOOG_SCAT, 1,scattering_name[1]);
  cloog_union_domain_set_name(domains,CLOOG_SCAT, 2,scattering_name[2]);

  /* Build the input, generate a scanning code AST and print the code */
  input = cloog_input_alloc(context, domains);
  state = cloog_isl_state_malloc(ctx);
  options = cloog_options_malloc(state);
  root = cloog_clast_create_from_input(input, options);
  clast_pprint(stdout, root, 0, options);

  /* Recycle allocated memory */
  cloog_clast_free(root);
  cloog_options_free(options);
  cloog_state_free(state);
  isl_ctx_free(ctx);
@}
@end example

@noindent The compilation (with default isl/GMP version installed)
command could be:
@example
gcc -DCLOOG_INT_GMP example-isl.c -lcloog-isl -o example-isl
@end example
@noindent A calling command could be:
@example
./example-isl
@end example

@node Source to Source Compiler
@subsection Source to Source Compiler
Here is an example of a source (to polyhedra) to source compiler. It uses the
Clan library to raise a SCoP from C to the OpenScop representation, and CLooG
to translate back the SCoP to C. You may analyze the polyhedral representation
and apply optimizing transformation to that representation to build your own
high-level optimizing compiler. That example requires to install Clan, OpenScop
and to build CLooG with the OpenScop support. This example is provided in the
@code{example} directory of the CLooG distribution.

@example
/* poc.c A complete C to polyhedra to C compiler */
#include <stdlib.h>
#include <osl/osl.h>
#include <clan/clan.h>
#include <cloog/cloog.h>

/* Use the Clan library to convert a SCoP from C to OpenScop */
osl_scop_p read_scop_from_c(FILE* input, char* input_name) @{
  clan_options_p clanoptions;
  osl_scop_p scop;

  clanoptions = clan_options_malloc();
  clanoptions->precision = OSL_PRECISION_MP;
  CLAN_strdup(clanoptions->name, input_name);
  scop = clan_scop_extract(input, clanoptions);
  clan_options_free(clanoptions);
  return scop;
@}

/* Use the CLooG library to output a SCoP from OpenScop to C */
void print_scop_to_c(FILE* output, osl_scop_p scop) @{
  CloogState* state;
  CloogOptions* options;
  CloogInput* input;
  struct clast_stmt* clast;

  state = cloog_state_malloc();
  options = cloog_options_malloc(state);
  options->openscop = 1;
  cloog_options_copy_from_osl_scop(scop, options);
  input = cloog_input_from_osl_scop(options->state, scop);
  clast = cloog_clast_create_from_input(input, options);
  clast_pprint(output, clast, 0, options);
  
  cloog_clast_free(clast);
  options->scop = NULL; // don't free the scop
  cloog_options_free(options);
  cloog_state_free(state); // the input is freed inside
@}

int main(int argc, char* argv[]) @{
  osl_scop_p scop;
  FILE* input;

  if ((argc < 2) || (argc > 2)) @{
    fprintf(stderr, "usage: %s file.c\n", argv[0]);
    exit(0);
  @}

  if (argc == 1)
    input = stdin;
  else
    input = fopen(argv[1], "r");

  if (input == NULL) @{
    fprintf(stderr, "cannot open input file\n");
    exit(0);
  @}

  scop = read_scop_from_c(input, argv[1]);
  osl_scop_print(stdout, scop);

  // UPDATE THE SCOP IN A SMART WAY HERE 

  print_scop_to_c(stdout, scop);
  osl_scop_free(scop);
  
  fclose(input);
  return 0;
@}
@end example

@noindent The compilation (with default isl/GMP with OpenScop support
version installed, along with the OpenScop library and Clan library)
command could be:
@example
gcc -DCLOOG_INT_GMP poc.c -lcloog-isl -lclan -losl -o poc
@end example
@noindent A calling command could be:
@example
./poc scop.c
@end example


@c %  ******************************** HACKING *********************************
@c @node Hacking
@c @chapter Hacking CLooG

@c @menu
@c * Program organization::
@c * Special Options::
@c * CLooG Coding Standards::
@c @end menu

@c @node Program organization
@c @section Program organization

@c @node Special Options
@c @section Special Options

@c @node CLooG Coding Standards
@c @section CLooG Coding Standards


@c %  ****************************** INSTALLING ********************************
@node Installing
@chapter Installing CLooG

@menu
* License::
* Requirements::
* Basic Installation::
* Optional Features::
* Uninstallation::
@end menu

@node License
@section License
First of all, it would be very kind to refer the following paper in any
publication that result from the use of the CLooG software or its library,
@pxref{Bas04} (a bibtex entry is provided behind the title page of this
manual, along with copyright notice, and in the CLooG home
@code{http://www.CLooG.org}.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.
@code{http://www.gnu.org/licenses/lgpl-2.1.html}

Note, though, that if you link CLooG against a GPL library such
as the PolyLib backend, then the combination becomes GPL too.
In particular, a CLooG library based on the PolyLib backend
is GPL version 2 only.
Since the isl backend is LGPL, linking against it does not affect
the license of CLooG.


@node Requirements
@section Requirements

CLooG can be used with one of two possible backends,
one using isl and one using PolyLib.
The isl library is included in the CLooG distribution,
while the PolyLib library needs to be obtained separately.
On the other hand, isl requires GMP, while PolyLib can be
compiled with or without the use of GMP.
The user therefore needs to install at least one of
PolyLib or GMP.

@menu
* PolyLib::
* GMP Library::
@end menu


@node PolyLib
@subsection PolyLib (optional)
To successfully install CLooG with the PolyLib backend,
the user first needs to install PolyLib
version 5.22.1 or above (default 64 bits version is satisfying
as well as 32 bits or GMP multiple precision version).
Polylib can be downloaded freely
at @code{http://icps.u-strasbg.fr/PolyLib/} or
@code{http://www.irisa.fr/polylib/}. Once downloaded and unpacked
(e.g. using the @samp{tar -zxvf polylib-5.22.3.tar.gz} command),
the user can compile
it by typing the following commands on the PolyLib's root directory:

@itemize @bullet
@item @code{./configure}
@item @code{make}
@item And as root: @code{make install}
@end itemize

Alternatively, the latest development version can be obtained from the
git repository:
@itemize @bullet
@item @code{git clone git://repo.or.cz/polylib.git}
@item @code{cd polylib}
@item @code{./autogen.sh}
@item @code{./configure}
@item @code{make}
@item And as root: @code{make install}
@end itemize

The PolyLib default installation is @code{/usr/local}. This directory may
not be inside your library path. To fix the problem, the user should set
@example
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib
@end example
@noindent if your shell is, e.g., bash or
@example
setenv LD_LIBRARY_PATH $LD_LIBRARY_PATH:/usr/local/lib
@end example
@noindent if your shell is, e.g., tcsh. Add the line to your .bashrc or .tcshrc (or
whatever convenient file) to make this change permanent. Another solution
is to ask PolyLib to install in the standard path by using the prefix
option of the configure script:
@samp{./configure --prefix=/usr}.

CLooG makes intensive calls to polyhedral operations, and PolyLib
functions do the job. Polylib is a free library written in C for the
manipulation of polyhedra. The library is operating on objects like
vectors, matrices, lattices, polyhedra, Z-polyhedra, unions of
polyhedra and a lot of other intermediary structures. It provides
functions for all the important operations on these structures. 

@node GMP Library
@subsection GMP Library (optional)

To be able to deal with insanely large coefficient, the user will need to
install the GNU Multiple Precision Library (GMP for short) version 4.1.4
or above. It can be freely downloaded from @code{http://www.swox.com/gmp}.
Note that the isl backend currently requires GMP.
The user can compile GMP by typing the following commands on the GMP root
directory:

@itemize @bullet
@item @code{./configure}
@item @code{make}
@item And as root: @code{make install}
@end itemize

The GMP default installation is @code{/usr/local}, the same method to
fix a library path problem applies as with PolyLib (@pxref{PolyLib}).

If you want to use the PolyLib backend, then
PolyLib has to be built using the GMP library by specifying the option
@samp{--with-libgmp=PATH_TO_GMP} to the PolyLib configure script
(where @code{PATH_TO_GMP} is @code{/usr/local} if you did not change the GMP
installation directory). Then you have to set the convenient CLooG configure
script options to build the GMP version (@pxref{Optional Features}).


@node Basic Installation
@section CLooG Basic Installation

Once downloaded and unpacked
(e.g. using the @samp{tar -zxvf cloog-@value{VERSION}.tar.gz} command),
you can compile CLooG by typing the following commands on the CLooG's root
directory:

@itemize @bullet
@item @code{./configure}
@item @code{make}
@item And as root: @code{make install}
@end itemize

Alternatively, the latest development version can be obtained from the
git repository:
@itemize @bullet
@item @code{git clone git://repo.or.cz/cloog.git}
@item @code{cd cloog}
@item @code{./get_submodules.sh}
@item @code{./autogen.sh}
@item @code{./configure}
@item @code{make}
@item And as root: @code{make install}
@end itemize

Depending on which backend you want to use and where they
are located, you may need to pass some
options to the configure script, @pxref{Optional Features}.

The program binaries and object files can be removed from the
source code directory by typing @code{make clean}. To also remove the
files that the @code{configure} script created (so you can compile the
package for a different kind of computer) type @code{make distclean}.

Both the CLooG software and library have been successfully compiled
on the following systems:
@itemize @bullet
@item PC's under Linux, with the @code{gcc} compiler,
@item PC's under Windows (Cygwin), with the @code{gcc} compiler,
@item Sparc and UltraSparc Stations, with the @code{gcc} compiler.
@end itemize

@node Optional Features 
@section Optional Features  
The @code{configure} shell script attempts to guess correct values for
various system-dependent variables and user options used during compilation.
It uses those values to create the @code{Makefile}. Various user options
are provided by the CLooG's configure script. They are summarized in the
following list and may be printed by typing @code{./configure --help} in the
CLooG top-level directory.

@itemize @bullet
@item By default, the installation directory is @code{/usr/local}:
@code{make install} will install the package's files in
@code{/usr/local/bin}, @code{/usr/local/lib} and @code{/usr/local/include}.
The user can specify an installation prefix other than @code{/usr/local} by
giving @code{configure} the option @code{--prefix=PATH}.

@item By default, the isl backend will use the version of isl
that is @code{bundled} together with CLooG.
Using the @code{--with-isl} option of @code{configure}
the user can specify that @code{no} isl,
a previously installed (@code{system}) isl or a @code{build} isl
should be used.
In the latter case, the user should also specify the build location
using @code{--with-isl-builddir=PATH}.
In case of an installed isl,
the installation location can be specified using the
@code{--with-isl-prefix=PATH} and
@code{--with-isl-exec-prefix=PATH} options of @code{configure}.

@item By default, the PolyLib backend will use an installed
(@code{system}) PolyLib, if any.
The installation location can be specified using the
@code{--with-polylib-prefix=PATH} and
@code{--with-polylib-exec-prefix=PATH} options of @code{configure}.
Using the @code{--with-polylib} option of @code{configure}
the user can specify that @code{no} PolyLib or a @code{build} PolyLib
should be used.
In the latter case, the user should also specify the build location
using @code{--with-polylib-builddir=PATH}.

@item By default, the PolyLib backend of CLooG is built
in 64bits version if such version of the
PolyLib is found by @code{configure}. If the only existing version of the
PolyLib is the 32bits or if the user give to @code{configure} the option
@code{--with-bits=32}, the 32bits version of CLooG will be compiled. In the
same way, the option @code{--with-bits=gmp} have to be used to build
the multiple precision version.

@item By default, @code{configure} will look for the GMP library
(necessary to build the multiple precision version) in standard
locations. If necessary, the user can specify the GMP path by giving
@code{configure} the option @code{--with-gmp-prefix=PATH} and/or
@code{--with-gmp-exec-prefix=PATH}.

@item By default, the OpenScop Library (osl) support is not enabled.
@c @code{configure} will use the bundled OpenScop Library (osl).
Using the @code{--with-osl} option of @code{configure}
the user can specify that @code{no} osl,
a previously installed (@code{system}) osl, a @code{bundled} osl, or a
@code{build} osl should be used.
In the latter case, the user should also specify the build location
using @code{--with-osl-builddir=PATH}.
In case of an installed osl,
the installation location can be specified using the
@code{--with-osl-prefix=PATH} and
@code{--with-osl-exec-prefix=PATH} options of @code{configure}.
@end itemize

@node Uninstallation 
@section Uninstallation  
The user can easily remove the CLooG software and library from his system
by typing (as root if necessary) from the CLooG top-level directory
@code{make uninstall}.

@c %  **************************** DOCUMENTATION ******************************
@node Documentation
@chapter Documentation
The CLooG distribution provides several documentation sources. First, the
source code itself is as documented as possible. The code comments use a
Doxygen-compatible presentation (something similar to what JavaDoc does for
JAVA). The user may install Doxygen
(see @code{http://www.stack.nl/~dimitri/doxygen}) to automatically
generate a technical documentation by typing @code{make doc} or
@code{doxygen ./autoconf/Doxyfile} at the CLooG top-level directory after
running the configure script (@pxref{Installing}). Doxygen will generate
documentation sources (in HTML, LaTeX and man) in the @code{doc/source}
directory of the CLooG distribution.

The Texinfo sources of the present document are also provided in the @code{doc}
directory. You can build it in either DVI format (by typing
@code{texi2dvi cloog.texi}) or PDF format
(by typing @code{texi2pdf cloog.texi}) or HTML format
(by typing @code{makeinfo --html cloog.texi}, using @code{--no-split}
option to generate a single HTML file) or info format
(by typing @code{makeinfo cloog.texi}).

@c %  ****************************** REFERENCES ********************************
@node References
@chapter References

@itemize
@item
@anchor{Bas03a}[Bas03a] C. Bastoul, P. Feautrier. Improving data locality
by chunking. CC'12 International Conference on Compiler Construction,
LNCS 2622, pages 320-335, Warsaw, april 2003. 

@item
@anchor{Bas03b}[Bas03b] C. Bastoul. Efficient code generation for automatic
parallelization and optimization. ISPDC'03 IEEE International Symposium on
Parallel and Distributed Computing, pages 23-30, Ljubljana, october 2003. 

@item
@anchor{Bas04}[Bas04] C. Bastoul. Code Generation in the Polyhedral Model
Is Easier Than You Think. PACT'13 IEEE International Conference on Parallel
Architecture and Compilation Techniques, pages 7-16, Juan-les-Pins,
september 2004.

@item
@anchor{Bas11}[Bas11] C. Bastoul. A Specification and a Library for Data 
Exchange in Polyhedral Compilation Tools. Technical Report,
Paris-Sud University, France, September 2011.

@item
@anchor{Fea92}[Fea92] P. Feautrier Some efficient solutions to the affine
scheduling problem, part II: multidimensional time.
International Journal of Parallel Programming, 21(6):389--420, December 1992.

@item
@anchor{Gri04}[Gri04] M. Griebl. Automatic parallelization of loop programs
for distributed memory architectures. Habilitation Thesis. Facult@"at f@"ur
Mathematik und Informatik, Universit@"at Passau, 2004.
@emph{http://www.infosun.fmi.uni-passau.de/cl/loopo/}

@item
@anchor{Qui00}[Qui00] F. Quiller@'e, S. Rajopadhye, and D. Wilde.
Generation of efficient nested loops from polyhedra.
International Journal of Parallel Programming, 28(5):469-498,
october 2000.

@item
@anchor{Wil93}[Wil93] Doran K. Wilde.
A library for doing polyhedral operations.
Technical Report 785, IRISA, Rennes, France, 1993.

@end itemize




@c % /*************************************************************************
@c %  *                       PART VI: END OF THE DOCUMENT                    *
@c %  *************************************************************************/
@c @unnumbered Index
     
@c @printindex cp
     
@bye