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<p>This file documents the MELT plugin for GCC.
<br>
</p><p>Copyright © 2011 Free Software Foundation, Inc.
</p>
<p>Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being “Funding Free Software”, the Front-Cover
Texts being (a) (see below), and with the Back-Cover Texts being (b)
(see below). A copy of the license is included in the section entitled
“GNU Free Documentation License”.
</p>
<p>(a) The FSF’s Front-Cover Text is:
</p>
<p> A GNU Manual
</p>
<p>(b) The FSF’s Back-Cover Text is:
</p>
<p> You have freedom to copy and modify this GNU Manual, like GNU
software. Copies published by the Free Software Foundation raise
funds for GNU development.
</p><br>
<a name="Top"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Introduction"></a>
<h1 class="settitle">Introduction</h1>
<a name="index-introduction"></a>
<p>This manual documents briefly how to use the MELT plugin for GCC. The
use of the GNU compilers is documented in a separate manual.
See <a href="gcc.html#Top">(gcc)Top</a> section ‘Introduction’ in <cite>Using the GNU Compiler Collection (GCC)</cite>. The MELT plugin for GCC permits you to develop your specific
extensions of GCC in a powerful, lispy, domain specific language
(also called MELT).
</p>
<p>This manual is mainly a reference manual rather than a tutorial. It
discusses how to use the MELT plugin for GCC.
Additional tutorial information for GCC is linked to from
<a href="http://gcc.gnu.org/readings.html">http://gcc.gnu.org/readings.html</a> and for MELT is linked to from
<a href="http://gcc-melt.org/">http://gcc-melt.org/</a>.
</p>
<p>MELT documentation is made of a human written docuemtation (this
document) and of a machine generated documentation. The machine
generated documentation explains the MELT definitions (of functions,
classes, selectors, primitives, etc...). Since it is generated from a
GPLv3 source code, that generated documentation is released separately
under a GPLv3 license. (the main author of this document, Basile
Starynkevitch, understands that GPL and GFDL licenses are
incompatible, so merging these two documentations is inappropriate.).
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top"><a href="#MELT">1. MELT: Middle End Lisp Translator</a></td><td> </td><td align="left" valign="top"> the Middle End Lisp Translator.
</td></tr>
<tr><td align="left" valign="top"><a href="#Funding">Funding Free Software</a></td><td> </td><td align="left" valign="top"> How to help assure funding for free software.
</td></tr>
<tr><td align="left" valign="top"><a href="#GNU-Project">The GNU Project and GNU/Linux</a></td><td> </td><td align="left" valign="top"></td></tr>
<tr><td align="left" valign="top"><a href="#Copying">GNU General Public License</a></td><td> </td><td align="left" valign="top"> GNU General Public License says
how you can copy and share GCC.
</td></tr>
<tr><td align="left" valign="top"><a href="#GNU-Free-Documentation-License">GNU Free Documentation License</a></td><td> </td><td align="left" valign="top"> How you can copy and share this manual.
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-Option-Index">MELT Option Index</a></td><td> </td><td align="left" valign="top"> Index to MELT plugin command line options.
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-Concept-Index">MELT Concept Index</a></td><td> </td><td align="left" valign="top"> Index of MELT concepts and symbol names.
</td></tr>
</table>
<hr size="1">
<a name="MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Top" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Prerequisites" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Top" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT_003a-Middle-End-Lisp-Translator"></a>
<h1 class="chapter">1. MELT: Middle End Lisp Translator</h1>
<a name="index-MELT"></a>
<a name="index-Middle-End-Lisp-Translator"></a>
<p>The MELT branch introduces a powerful Lisp dialect to express middle-end
analyzers and passes. This chapter describes the dialect and how to use
it. A working knowledge of Scheme or Lisp is presupposed.
</p>
<p>See the <a href="http://gcc.gnu.org/wiki/MiddleEndLispTranslator">MELT wiki page</a> and
the <a href="http://gcc-melt.org">GCC MELT site</a>
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top"><a href="#MELT-Prerequisites">1.1 MELT Prerequisites</a></td><td> </td><td align="left" valign="top"> Prerequisites and topics not yet covered in this MELT chapter.
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-overview">1.2 MELT overview</a></td><td> </td><td align="left" valign="top"> An overview of MELT.
</td></tr>
<tr><td align="left" valign="top"><a href="#Building-the-MELT-branch">1.3 Building the MELT branch</a></td><td> </td><td align="left" valign="top"> Configuration and building requirements and instructions for MELT.
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-as-a-plugin">1.4 MELT as a plugin</a></td><td> </td><td align="left" valign="top"> Building and using MELT as a plugin.
</td></tr>
<tr><td align="left" valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td><td> </td><td align="left" valign="top"></td></tr>
<tr><td align="left" valign="top"><a href="#Tutorial-about-MELT">1.6 Tutorial about MELT</a></td><td> </td><td align="left" valign="top"> Tutorial describing MELT.
</td></tr>
<tr><td align="left" valign="top"><a href="#Reference-on-MELT">1.7 Reference on MELT</a></td><td> </td><td align="left" valign="top"> MELT language reference.
</td></tr>
<tr><td align="left" valign="top"><a href="#Writing-C-code-for-MELT">1.8 Writing C code for MELT</a></td><td> </td><td align="left" valign="top"> How to write C code for MELT.
</td></tr>
</table>
<hr size="6">
<a name="MELT-Prerequisites"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#MELT" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-overview" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#MELT" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-Prerequisites-1"></a>
<h2 class="section">1.1 MELT Prerequisites</h2>
<p>The reader is expected to have some working knowledge of some Lisp
dialect (Common Lisp, Emacs Lisp, Guile, ...). The reader is also
expected to be somehow familiar with the internal architecture of GCC
(i.e. knowing what GCC <em>gimple</em>-s and <em>tree</em>-s are).
</p>
<p>MELT is different of other Lisps, because it is tightly suited to GCC
internals. For that purpose, it has several peculiarities; MELT can:
</p>
<ul>
<li> handle two kind of things.
The MELT infrastructure can handle both MELT <em>values</em> (closures,
lists, objects, ...) and GCC <em>stuff</em> (plain long integers,
gimples, trees, ...), that it, datatypes appearing inside GCC. Both
<em>values</em> and <em>stuff</em> are called MELT <em>things</em>. Notice
that <em>stuff</em> is not handled polymorphically (due to a limitation
of the GCC Garbage Collector).
</li><li> generate C code.
MELT source code (either in ‘<tt>*.melt</tt>’ files, or inside memory) is
translated into C code suitable for GCC internals, in the style
expected inside GCC. That generated C code is compiled into a MELT
binary <em>module</em>, which is dynamically loaded by the MELT
infrastructure.
</li><li> provide linguistic devices.
The MELT language has several <em>linguistic devices</em> to generate C
code suitable for GCC internals, in the style expected by GCC. So MELT
code contains constructs to fit into GCC, and to define operators
related to GCC coding style.
</li></ul>
<hr size="6">
<a name="MELT-overview"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#MELT-Prerequisites" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#Building-the-MELT-branch" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#MELT" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-overview-1"></a>
<h2 class="section">1.2 MELT overview</h2>
<a name="index-MELT-overview"></a>
<p>Any MELT enabling compilation is really a long lasting compilation. It
is supposed that you use a powerful workstation (or laptop) with
enough memory (at least 4Gigabytes of RAM is receommended on a 64 bits
machine like x86-64), and that the MELT-enabled compilation will run a
lot slower than a simple <code>gcc -O1</code> compilation (hopefully doing
some useful stuff). Notice that a MELT-enabled compilation usually
generates C code, compile it (using another GCC compilation process)
to a dynamically loadable library, and load its into the MELT-enabled
GCC compilation process started by the user. In practice, the
compilation of the generated C code (which is much bigger than the
original MELT source) is the main bottleneck. Often, when using an
existing MELT module, no C code has to be generated (it already
exists).
</p>
<p>The MELT plugin or branch contains several (related) stuff. Everything
can be enabled or disabled at GCC run time:
</p>
<ol>
<li> a Lisp dialect compiled into C code, with which one can code
sophisticated or prototypical middle end passes.
</li><li> a runtime which extends the GCC infrastructure to support the
previous items, in particular a generational copying garbage
collector well suited for the lisp dialect above, which is build
above the existing GGC (which deals with old values).
</li></ol>
<p>MELT is bootstrapped, in the sense that the translation from the MELT
dialect to C is coded in MELT (hence the MELT generated C code is
available from the source code).
</p>
<p>The generated C code is including only one file <code>run-melt.h</code>
which includes many GCC include files internal to the compiler. It is
compiled into a dynamic library by a shell script
<code>*melt-cc-script*</code> which invokes the host GCC with appropriate
flags.
</p>
<p>MELT obviously need that the binary (dynamic libraries <code>warm*.so</code>)
for the MELT translator are already available. More generally, it uses
several kind of files:
</p>
<ol>
<li> the script used to compile generated C files info dynamically loadable stuff.
This script may be invoked by MELT GCC. In common cases, the first
argument to the script is the MELT generated input <code>*.c</code> file and
the second argument is the MELT loaded output <code>*.so</code> dynamic
library.
</li><li> an include directory (passed by <code>-I</code> to the compiler)
containing all the useful GCC headers. This directory is only written by
the installation procedure.
</li><li> a permanent generated C code directory
which contains some essential files, in particular the C form of the
MELT translated.
</li></ol>
<p>MELT can be used as a plugin for GCC (and can also be compiled as a
separate GCC branch). It uses some of the plugin machinery, even
inside the MELT branch.
</p>
<p>When using MELT, it is important in practice to give it a work
directory (where all generated C or object files go).
</p>
<hr size="6">
<a name="Building-the-MELT-branch"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#MELT-overview" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-as-a-plugin" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#MELT" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Building-the-MELT-branch-1"></a>
<h2 class="section">1.3 Building the MELT branch</h2>
<a name="index-Building-the-MELT-branch"></a>
<p>To compile the MELT branch, you need the Parma Polyhedra Library. The
Parma Polyhedra Library (PPL) is a free library available
<a href="http://www.cs.unipr.it/ppl/">here</a>, it is a C++ library (GPLv3
licensed) handling lattices like intervals etc. Also, the host
compiler (the compiler which compiles the source code of GCC), also
used to compile MELT generated C code during MELT enabled <code>gcc</code>
execution, should be some version of <code>gcc</code> (preferably a 4.x
version at least).
</p>
<p>Note that currently MELT is only compiled on Linux machines.
</p>
<p>MELT can also be used as a plugin to GCC (4.6).
</p>
<hr size="6">
<a name="MELT-as-a-plugin"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Building-the-MELT-branch" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#Invoking-MELT" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#MELT" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-as-a-plugin-1"></a>
<h2 class="section">1.4 MELT as a plugin</h2>
<a name="index-MELT-as-a-plugin"></a>
<p>MELT can be used as a plugin to a GCC 4.6 (or better?) binary
(i.e. future gcc 4.7) build with plugin enabled. You’ll need the GCC
headers available to plugins, ‘<tt>gengtype</tt>’ and its state file to
build and run the MELT plugin.
</p>
<p>Detailed instructions about building MELT as a plugin are available in
the MELT plugin source tarball.
</p>
<hr size="6">
<a name="Invoking-MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#MELT-as-a-plugin" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#Tutorial-about-MELT" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#MELT" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Invoking-MELT-1"></a>
<h2 class="section">1.5 Invoking MELT</h2>
<a name="index-Invoking-MELT"></a>
<p>Without any MELT specific program flags, the MELT variant of gcc
behave as the trunk. So to get or use MELT features, you need to pass
some special flags. Most of these flags are starting with
<code>-fmelt</code> for the MELT branch or with <code>-fplugin-melt-arg</code> for
the plugin. They for the middle-end of GCC so are common for every
source language (ie <code>gcc</code>, <code>g++</code> … commands) and
target.
</p>
<p>MELT is usually invoked while compiling a (C, C++, …) source
file but may occasionnally be invoked with an empty C input to perform
tasks which are not related to a particular GCC input source file. In
practice, you should pass an empty C file to <code>gcc</code> for that
purpose. In particular, the translation of a MELT file <code>foo.melt</code>
into C code <code>foo.c</code> is done with a special invocation like
<code>gcc -fmelt-mode=translatefile -fmelt-arg=foo.melt
-fmelt-secondarg=foo.c</code> (possibly with other options like some
appropriate <code>-fmelt-init=</code>). It is possible but deprecated to
invoke with <code>-fmelt-mode=compilefile</code> instead of
<code>-fmelt-mode=translatefile</code>. In other words, the MELT translator to C
<em>is not</em> a GCC front-end, like e.g. <code>g++</code> is a C++ front-end
of GCC.
</p>
<p>The table below lists all MELT specific options, in alphabetical
order. We list both MELT branch options like <code>-fmelt-arg=</code> and
MELT plugin option like <code>-fplugin-arg-melt-arg=</code>
</p>
<dl compact="compact">
<dt> <code>-fmelt-mode=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-mode=
</pre></td></tr></table>
<a name="index-fmelt_002dmode"></a>
<a name="index-fplugin_002darg_002dmelt_002dmode"></a>
<p>This flag (called the MELT mode flag) is required for every MELT
enabled compilation. If it is not given, no MELT specific processing
is done. If given, this gives the mode to be used before any
MELT passes. It uses the <code>:sysdata_mode_dict</code> field of
<code>INITIAL_SYSTEM_DATA</code> internal object of MELT to determine the
MELT function applied to execute the mode. If this application
returns nil, no GCC compilation occur (i.e. no <code>*.c</code> or
<code>*.cc</code> etc… source file is read). Hence, some modes may
be used for their side-effects. In particular, the compilation of MELT
lisp source file <code>*.melt</code> into C code <code>*.c</code> is done this
way.
</p>
<p>Several modes may be given by separating them with commas. They are
handled in that case in succession.
</p>
</dd>
<dt> <code>-fmelt-arg=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-arg=
</pre></td></tr></table>
<a name="index-fmelt_002darg_003d"></a>
<p>This gives the first argument string to MELT. It is incompatible with
the <code>-fmelt-arglist=</code> option.
</p>
</dd>
<dt> <code>-fmelt-arglist=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-arglist=
</pre></td></tr></table>
<a name="index-fmelt_002darglist_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002darglist_003d"></a>
<p>This gives the first argument list of strings to MELT. It is
incompatible with the <code>-fmelt-arg=</code> option. The string program
argument is split into a list of strings using the comma
separator. For example, <code>-fmelt-arglist=1,BB,3</code> makes a
three-element list argument with first string <code>1</code>, second string
<code>BB</code> and third string <code>3</code>. There is no way to give a
string subargument containing a comma.
</p>
</dd>
<dt> <code>-fmelt-print-settings=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-print-settings=
</pre></td></tr></table>
<a name="index-fmelt_002dprint_002dsettings_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dprint_002dsettings_003d"></a>
<p>The builtin settings (notably MELT builtin modules directory and MELT
builtin source directory) used by MELT are output in the given file,
which should be source-able by a Posix shell if you are lucky enough.
This is mostly useful in configuration, building, or packaging scripts.
</p>
</dd>
<dt> <code>-fmelt-coutput=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-coutput=
</pre></td></tr></table>
<a name="index-fmelt_002dcoutput_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dcoutput_003d"></a>
<p>This flag gives the name of the generated C file.
</p>
</dd>
<dt> <code>-fmelt-output=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-output=
</pre></td></tr></table>
<a name="index-fmelt_002dcoutput_003d-1"></a>
<a name="index-fplugin_002darg_002dmelt_002doutput_003d"></a>
<p>This flag gives the name of the generated files.
</p>
</dd>
<dt> <code>-fmelt-debug</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-debug
</pre></td></tr></table>
<a name="index-fmelt_002ddebug"></a>
<a name="index-fplugin_002darg_002dmelt_002ddebug"></a>
<p>This flag has no argument and asks for lot of debugging output. It is
only useful to debug MELT code and is unrelated to the <code>-g</code> flag
asking GCC to output debug information.
</p>
</dd>
<dt> <code>-fmelt-debugskip=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-debugskip=
</pre></td></tr></table>
<a name="index-fmelt_002ddebugskip_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002ddebugskip_003d"></a>
<p>This flag (only useful with <code>-fmelt-debug</code>) has an integer
argument. When <code>-fmelt-debug</code> is given with
<code>-fmelt-debugskip=1000</code> the first thousand debug messages are
skipped, so are not printed.
</p>
</dd>
<dt> <code>-fmelt-source-path=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-source-path=
</pre></td></tr></table>
<a name="index-fmelt_002dsource_002dpath_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dsource_002dpath_003d"></a>
<p>This flag sets the path (colon separated list of directories) for
sources (i.e. ‘<tt>*.melt</tt>’ and ‘<tt>*.c</tt>’). Otherwise use the
<code>GCCMELT_SOURCE_PATH</code> environment variable.
</p>
</dd>
<dt> <code>-fmelt-module-path=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-module-path=
</pre></td></tr></table>
<a name="index-fmelt_002dmodule_002dpath_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dmodule_002dpath_003d"></a>
<p>This flag sets the path (colon separated list of directories) for
MELT binary modules (i.e. ‘<tt>*.so</tt>’). Otherwise use the
<code>GCCMELT_MODULE_PATH</code> environment variable.
</p>
</dd>
<dt> <code>-fmelt-module-make-command=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-module-make-command=
</pre></td></tr></table>
<a name="index-fmelt_002dmodule_002dmake_002dcommand_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dmake_002dcommand_003d"></a>
<p>This flag defines the <code>make</code> command used to build MELT binary
modules (i.e. ‘<tt>*.so</tt>’). from a small set of generated C files. The
default is the GNU make utility used to build MELT, very often just
<code>make</code> or perhaps <code>gmake</code>.
</p>
</dd>
<dt> <code>-fmelt-module-makefile=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-module-makefile=
</pre></td></tr></table>
<a name="index-fmelt_002dmodule_002dmakefile_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dmakefile_003d"></a>
<p>This flag defines the makefile used to build MELT binary modules
(i.e. ‘<tt>*.so</tt>’). from a small set of generated C files. The default
is a file ‘<tt>melt-module.mk</tt>’.
</p>
</dd>
<dt> <code>-fmelt-module-cflags=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-module-cflags=
</pre></td></tr></table>
<a name="index-fmelt_002dmodule_002dcflags_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dcflags_003d"></a>
<p>This flag defines the <code>CFLAGS</code> passed to <code>make</code> to build
MELT binary modules. If not given, the environment variable
<code>GCCMELT_MODULE_CFLAGS</code> is used if it was set.
</p>
</dd>
<dt> <code>-fmelt-init=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-init=
</pre></td></tr></table>
<a name="index-fmelt_002dinit_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dinit_003d"></a>
<p>This flag sets the initial MELT modules. They are separated by
semi-colons or (on Unix only) colons. So <code>-fmelt-init=foo:bar</code>
or <code>'-fmelt-init=foo;bar'</code> (quotes are useful for the shell
running GCC) load first the <code>foo</code> module and then the <code>bar</code>
module. A module starting with an at sign <code>@</code> is handled as a
module list file. The <code>.modlis</code> extension is added, and then a
file is seeked by that name. This file is read line by line (with
empty or blank lines skipped, and comment lines starting with an hash
<code>#</code> skipped). Each line is the name of a module do be load in
sequence. For example, <code>-fmelt-init=@mylist:bar</code> with a file
‘<tt>mylist.modlis</tt>’ containing
</p><table><tr><td> </td><td><pre class="example"># file mylist.modlis ; just a comment
alpha
beta
</pre></td></tr></table>
<p>would have the same effect as <code>-fmelt-init=alpha:beta:bar</code>.
Notice that modules are seeked in several directories. The notation
<code>@@</code> is a shorthand for the default module list called
‘<tt>melt-default-modules.modlis</tt>’ and is the default value of this
flag.
</p>
</dd>
<dt> <code>-fmelt-extra=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-extra=
</pre></td></tr></table>
<a name="index-fmelt_002dextra_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dextra_003d"></a>
<p>This flag sets the extra MELT modules. They are separated by
semi-colons or (on Unix only) colons. Extra modules are also searched
in the current directory, and are loaded after processing of MELT
options. In practice, to use your own MELT module <code>foo</code> you
should pass <code>-fmelt-extra=foo</code> because your module needs the
default modules.
</p>
</dd>
<dt> <code>-fmelt-tempdir=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-tempdir=
</pre></td></tr></table>
<a name="index-fmelt_002dtempdir_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dmelt_002dtempdir_003d"></a>
<p>This flags sets the temporary MELT directory. If specified it is not
cleaned. If it does not exist, it is mkdir-ed and cleaned. Avoid
setting it to a non-empty directory which may contain files named like
MELT modules (such as ‘<tt>warmelt-*.so</tt>’ etc.).
</p>
</dd>
<dt> <code>-fmelt-option=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-option=
</pre></td></tr></table>
<a name="index-fmelt_002doption_003d"></a>
<p>This set some options for MELT. the argument is a comma separated
sequence of options settings, each being an option name possibly
followed by an equal sign and an option value. For example,
<code>-fmelt-option=foo,bar=x</code> set the option <code>foo</code> and the option
<code>bar</code> to <code>x</code>. An option name is case-insensitive and may
appear several times.
</p>
</dd>
<dt> <code>-fmelt-workdir=</code></dt>
<dd><table><tr><td> </td><td><pre class="smallexample">-fplugin-arg-melt-workdir=
</pre></td></tr></table>
<a name="index-fmelt_002dworkdir_003d"></a>
<a name="index-fplugin_002darg_002dmelt_002dmelt_002dworkdir_003d"></a>
<p>This flags sets the working MELT directory. If specified all generated
files go inside, and MELT modules are also loaded from it. Use that
flag if you don’t want MELT related generated files to clobber your
source tree.
</p>
</dd>
</dl>
<hr size="6">
<a name="Tutorial-about-MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Invoking-MELT" title="Previous section in reading order"> < </a>]</td>
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<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#MELT" title="Up section"> Up </a>]</td>
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<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Tutorial-about-MELT-1"></a>
<h2 class="section">1.6 Tutorial about MELT</h2>
<a name="index-Tutorial-about-MELT"></a>
<p>More up to date information may be found on <a href="http://gcc-melt.org">GCC MELT site</a>.
</p>
<p>As in all Lisps, parenthesis are important, so <code>a</code> and <code>(a)</code>
do not mean the same thing. The first stuff after an opening
parenthesis has usually an operator or syntactic keyword role.
</p>
<a name="index-upgrade_002dwarmelt-make-target-for-MELT"></a>
<p>MELT is a Lisp dialect translated into (unreadable, or at least
unfriendly) C code. Some MELT constructs, and some MELT limitations
(e.g. lack of tail-recursion) are related to this C
translatability. The MELT translator is itself written in MELT (files
‘<tt>gcc/melt/warmelt-*.melt</tt>’) and is bootstrapped; the translated C
files are in ‘<tt>gcc/warmelt-*-0.c</tt>’; they are quite big and are
distributed with the GCC source code; use the <code>upgrade-warmelt</code>
target of ‘<tt>gcc/Makefile.in</tt>’ to regenerate these C translations.
</p>
<p>MELT is closely related to GCC internal passes and internal middle-end
representations and runtime. Hence (in contrast to other LISP
dialects) <em>MELT is dealing with both boxed values and unboxed
stuff</em> (e.g. plain <code>long</code> integers as in C, but also <code>tree</code>s
and <code>gimple</code>s, etc…, as inside GCC, separating them using their
<em>ctype</em>). Keep always in mind the boxed versus unboxed
distinction. Because of that, and because of GCC runtime (in
particular the GGC garbage collector), MELT is neither polymorphic
(you cannot deal with unboxed stuff like with boxed values) nor
polytopic (no variable arguments facility).
</p>
<p>Some familiarity with other Lisp dialects and with GCC internals is
required to code in MELT.
</p>
<p>The MELT runtime contains a copying generational garbage collector
-GC- implemented in ‘<tt>gcc/melt-runtime.c</tt>’, backed up by the previously
existing GCC ordinary (precise, marking) garbage collector GGC. The
MELT-specific copying GC is designed for efficiency (but requires a
very specific C coding style, easy to achieve in generated C code, but
uncumfortable for human C developers), and handles well quick
allocation of many short-lived objects [which is not a goald of
GGC]. Therefore, <em>don’t be afraid of allocating a lot of values</em>
inside MELT code.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top"><a href="#Reserved-MELT-syntax-and-symbols">1.6.1 Reserved MELT syntax and symbols</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#Primitives-in-MELT">1.6.2 Primitives in MELT</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#Citerators-in-MELT">1.6.3 Citerators in MELT</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#Functions-in-MELT">1.6.4 Functions in MELT</a></td><td> </td><td align="left" valign="top">
</td></tr>
</table>
<p>This section has to be completed.
</p>
<hr size="6">
<a name="Reserved-MELT-syntax-and-symbols"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Tutorial-about-MELT" title="Previous section in reading order"> < </a>]</td>
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<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Tutorial-about-MELT" title="Up section"> Up </a>]</td>
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<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Reserved-MELT-syntax-and-symbols-1"></a>
<h3 class="subsection">1.6.1 Reserved MELT syntax and symbols</h3>
<p>The following symbols have specific MELT meaning. Use them only as
described here and avoid redefining them. <code>and assert_msg
comment compile_warning cond cppif
current_module_environment_container debug_msg defciterator defclass
definstance defprimitive defselector defun exit export_class
export_macro export_values fetch_predefined forever get_field if instance lambda
let make_instance match multicall or parent_module_environment progn
put_fields quote return setq store_predefined
unsafe_get_field unsafe_put_fields
update_current_module_environment_container</code>
</p>
<p>Also avoid symbols starting with <code>def</code>
</p>
<hr size="6">
<a name="Primitives-in-MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Reserved-MELT-syntax-and-symbols" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#Citerators-in-MELT" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Tutorial-about-MELT" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
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<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Primitives-in-MELT-1"></a>
<h3 class="subsection">1.6.2 Primitives in MELT</h3>
<a name="index-Primitive-in-MELT"></a>
<p>A MELT primitive defines an operator by specifying how to translate
into C each of its invocation. As a simple example, the less-than
integer operator <code><i</code> is defined as
</p><table><tr><td> </td><td><pre class="lisp">(defprimitive <i <span class="roman">; define the primitive </span>
(:long <span class="roman">; next formal arguments are longs</span>
a b) <span class="roman">; the two formal arguments</span>
:long <span class="roman">; the type of the result (also long)</span>
"((" a ") < (" b "))") <span class="roman">; how to expand into C code</span>
</pre></td></tr></table>
<p>Later on, a MELT expression like <code>(<i <var>a</var> <var>b</var>)</code> gets
translated into C code similar to <code>((curfnum[3]) < (curfnum[7]))</code>
where <code>curfun[3]</code><a name="DOCF1" href="#FOOT1">(1)</a> is the translation of the normalized
form<a name="DOCF2" href="#FOOT2">(2)</a> of <var>a</var>, etc.
</p>
<a name="index-unboxed-MELT-stuff"></a>
<a name="index-ctype-in-MELT"></a>
<p>Note that the above primitive accepts raw long integers (exactly the C
<code>long</code> type) and returns such a long integer [0 if
<code>((a)<(b))</code> was false in the C sense, and non-zero, perhaps -1,
if it was true]. We say that such integers are <em>unboxed</em> stuff
(we don’t speak of values in that case). The symbol <code>:long</code>
represents the C type <code>long</code> and we call it a <em>ctype</em>.
</p>
<hr size="6">
<a name="Citerators-in-MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Primitives-in-MELT" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#Functions-in-MELT" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Tutorial-about-MELT" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Citerators-in-MELT-1"></a>
<h3 class="subsection">1.6.3 Citerators in MELT</h3>
<a name="index-Citerator-in-MELT"></a>
<p>A MELT c-iterator or <em>citerator</em> is a construct which generalize
iterative loops (like the <code>for</code> in C). As a trivial example, to
iterate on positive integers till a limit, define
</p>
<table><tr><td> </td><td><pre class="lisp">(defciterator each-posint-till <span class="roman">; define each-posint-till citerator</span>
(:long lim) <span class="roman">; start formal argument is lim</span>
eachposint <span class="roman">; state symbol - uniquely substituted</span>
(:long cur) <span class="roman">; local formals</span>
( <span class="roman">; start of before expansion</span>
"long " eachposint ";"
" for (" eachposint"=0; "
eachposint "<" lim ";"
eachposint "++) {"
cur " = " eachposint;
)
( <span class="roman">; start of after expansion</span>
"}"
)
)
</pre></td></tr></table>
<p>When used in a MELT expression like <code>(each-posint-till (5) (:long
v) (print-long v))</code> -which has <code>:void</code> ctype because citerators
are only useful for their side-effects- the C translation is vaguely
similar (assuming <code>print-long</code> is a primitive expanding to
<code>printf(``%d\n'',<var>…</var>)</code> to something looking like
</p><table><tr><td> </td><td><pre class="example">curfnum[11] /*LIM*/ = 5;
{long eachposint_24;
for (eachposint_24=0; eachposint_24<curfnum[11]; eachposint_24++) {
curfnum[3] /*V*/ = eachposint_24;
printf("%d\n", curfnum[3] /*V*/);
}
}
</pre></td></tr></table>
<p>So the start formals is translated as some local variable in the MELT
frame, the state symbol <code>eachposint</code> is only used to generate a C
identifier (unique to each occurrence of the citerator) and the local
formals are translated to local variables bound inside the iterators
body.
</p>
<p>In practice, citerators are very useful for interfacing to the various
iterating idioms in GCC. A more realistic example is
</p><table><tr><td> </td><td><pre class="lisp"><span class="roman">;;;; iterate on a gimpleseq</span>
(defciterator each_in_gimpleseq
(:gimpleseq gseq) <span class="roman">;start formals</span>
eachgimplseq
(:gimple g) <span class="roman">;local formals</span>
( <span class="roman">;;; before expansion</span>
"gimple_stmt_iterator gsi_" eachgimplseq ";\n"
<span class="roman">;; test that <tt>gseq</tt> is not null to be safe</span>
"if (" gseq ") for (gsi_" eachgimplseq " = gsi_start (" gseq
"); !gsi_end_p (gsi_" eachgimplseq ");"
" gsi_next (&gsi_" eachgimplseq ")) {\n"
g " = gsi_stmt (gsi_" eachgimplseq ");"
)
( <span class="roman">;;; after expansion</span>
"}"
)
)
</pre></td></tr></table>
<hr size="6">
<a name="Functions-in-MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Citerators-in-MELT" title="Previous section in reading order"> < </a>]</td>
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<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Functions-in-MELT-1"></a>
<h3 class="subsection">1.6.4 Functions in MELT</h3>
<a name="index-Function-in-MELT"></a>
<p>As in many lisp dialect (e.g. Common Lisp) MELT functions are defined
using the <code>defun</code> construct. The first argument (and the primary
result) of all MELT function should always be a value, so it is not
possible to give an unboxed <code>gimple</code> stuff to a function; hence
we box it (pack it into a MELT value) before passing it as an
argument.
</p>
<p>The following define a second-order function (actually defined in
‘<tt>ana-base.melt</tt>’) called <code>do_each_gimpleseq</code> which gets two
arguments, the first being itself a MELT function and the second being
an unobxed <code>gimple</code> stuff, and apply the first argument to boxes
packing each <code>gimple</code> inside the given <code>gimpleseq</code>.
</p>
<table><tr><td> </td><td><pre class="lisp"><span class="roman">;; apply a function to each boxed gimple in a gimple seq</span>
(defun do_each_gimpleseq (f :gimpleseq gseq)
(each_in_gimpleseq
(gseq) (:gimple g)
(let ( (gplval (make_gimple discr_gimple g)) )
(f gplval)))
)
</pre></td></tr></table>
<p>This function is only useful for its side effect (calling a function
for each member of a <code>gimpleseq</code>). It returns the nil value.
</p>
<p>The real translation to C of the above is a quite big and messy C
function, actually:
</p>
<pre class="verbatim">static melt_ptr_t
rout_9_DO_EACH_GIMPLESEQ (meltclosure_ptr_t closp_,
melt_ptr_t firstargp_, const char xargdescr_[],
union meltparam_un *xargtab_,
const char xresdescr_[],
union meltparam_un *xrestab_)
{
#if ENABLE_CHECKING
static long call_counter__;
long thiscallcounter__ ATTRIBUTE_UNUSED = ++call_counter__;
#define callcount thiscallcounter__
#else
#define callcount 0L
#endif
struct frame_rout_9_DO_EACH_GIMPLESEQ_st
{
unsigned nbvar;
#if ENABLE_CHECKING
const char *flocs;
#endif
struct meltclosure_st *clos;
struct excepth_melt_st *exh;
struct callframe_melt_st *prev;
#define CURFRAM_NBVARPTR 5
void *varptr[5];
/*no varnum*/
#define CURFRAM_NBVARNUM /*none*/0
/*others*/
gimple_seq loc_CTYPE_GIMPLESEQ__o0;
gimple loc_CTYPE_GIMPLE__o1;
long _spare_;
}
curfram__;
memset (&curfram__, 0, sizeof (curfram__));
curfram__.nbvar = 5;
curfram__.clos = closp_;
curfram__.prev = (struct callframe_melt_st *) melt_topframe;
melt_topframe = (struct callframe_melt_st *) &curfram__;
melt_trace_start ("DO_EACH_GIMPLESEQ", callcount);
</pre>
<p>The generated C function has a strange C formal arguments list (every
applicable routine has the same signature in C. All arguments except
the first are passed in an array of union, described by a short
constant string, one character per argument, encoding its
ctype. Secondary results are handled likewise). Some code is only
enabled with <code>#if ENABLE_CHECKING</code> when GCC is configured for
debugging (not for release). The MELT call frame is declared
explicitly as a structure called <code>curfram__</code>, and is properly
initialized, and set as the <code>melt_topframe</code>. The
<code>melt_trace_strart MELT_LOCATION callcount</code> C macros are
significant only when <code>#if ENABLE_CHECKING</code>.
</p>
<pre class="verbatim"> /*getarg#0 */
MELT_LOCATION ("ana-base.melt:436:/ getarg");
#ifndef MELTGCC_NOLINENUMBERING
#line 436 "ana-base.melt" /**::getarg::**/
#endif /*MELTGCC_NOLINENUMBERING */
/*_.F__V2*/ curfptr[1] = (melt_ptr_t) firstargp_;
</pre>
<p>We start to fetch the first argument into the current frame, since
<code>curfptr</code> is actually a C macro defined as
<code>curfram__.varptr</code>. The <code>MELT_LOCATION</code> macro call
(significant only when checking was enabled, and setting the
<code>flocs</code> field of the current frame in that case) and the
<code>#line</code> directive<a name="DOCF3" href="#FOOT3">(3)</a> refer to the MELT source
location. For clarity, we now skip them, but there are <em>lots of
such positional information</em> in the generated C code. Note that a
single MELT source line is producing many C code lines (hence the line
numbering seen in a debugger might be slightly wrong), and that some
comments are generated (notably explaining what each <code>curfptr</code>
occurrence means).
</p>
<pre class="verbatim"> /*getarg#1 */
if (xargdescr_[0] != BPAR_GIMPLESEQ)
goto lab_endgetargs;
curfram__.loc_CTYPE_GIMPLESEQ__o0 = xargtab_[0].bp_gimpleseq;
goto lab_endgetargs;
lab_endgetargs:;
</pre>
<p>The second argument is likewise fetched, only if the actual argument
is of <code>gimpleseq</code> ctype. The useless goto is optimized by any
serious C compiler (like gcc).
</p>
<pre class="verbatim">/*block*/
{
/*citerblock EACH_IN_GIMPLESEQ */
{
gimple_stmt_iterator gsi_cit1__EACHGIMPLSEQ;
if ( /*_?*/ curfram__.loc_CTYPE_GIMPLESEQ__o0)
for (gsi_cit1__EACHGIMPLSEQ =
gsi_start ( /*_?*/ curfram__.loc_CTYPE_GIMPLESEQ__o0);
!gsi_end_p (gsi_cit1__EACHGIMPLSEQ);
gsi_next (&gsi_cit1__EACHGIMPLSEQ))
{
/*_?*/ curfram__.loc_CTYPE_GIMPLE__o1 =
gsi_stmt (gsi_cit1__EACHGIMPLSEQ);
/*block */
{
/*_.GPLVAL__V4*/ curfptr[3] =
(meltgc_new_gimple
((meltobject_ptr_t)
(( /*!DISCR_GIMPLE */ curfrout->tabval[0])),
( /*_?*/ curfram__.loc_CTYPE_GIMPLE__o1)));;
</pre>
<p>This is the beginning of a block generated by a citerator. It contains
the translation of the <code>make_gimple</code> primitive use as a call to
the <code>meltgc_new_gimple</code> C function.
</p>
<pre class="verbatim"> /*apply */
{
/*_.F__V5*/ curfptr[4] =
melt_apply ((meltclosure_ptr_t)
( /*_.F__V2*/ curfptr[1]),
(melt_ptr_t) ( /*_.GPLVAL__V4*/
curfptr[3]),
"", (union meltparam_un *) 0,
"", (union meltparam_un *) 0);
};
</pre>
<p>This is the translation of the application of <code>f</code>. Since there
only one argument and no secundary results, we pass null <code>union
meltparam_un</code> pointers described by empty strings to follow the
pecular conventions required by
<code>melt_apply</code><a name="DOCF4" href="#FOOT4">(4)</a> and
respected by MELT generated C functions implementing MELT routines.
</p>
<pre class="verbatim"> /*epilog */
/*clear *//*_.GPLVAL__V4*/ curfptr[3] = 0;
/*clear *//*_.F__V5*/ curfptr[4] = 0;
};
}
/*citerepilog */
/*clear *//*_?*/ curfram__.loc_CTYPE_GIMPLE__o1 = 0;
/*clear *//*_.LET___V3*/ curfptr[2] = 0;
} /*endciterblock EACH_IN_GIMPLESEQ */
</pre>
<p>Some MELT local variables are explicitly cleared. This helps the MELT
garbege collector. The block generated for the citerator is ended,
again by clearing some locals.
</p>
<pre class="verbatim"> /*epilog */ };
goto labend_rout;
labend_rout:
melt_trace_end ("DO_EACH_GIMPLESEQ", callcount);
melt_topframe = (struct callframe_melt_st *) curfram__.prev;
return (melt_ptr_t) ( /*noretval */ NULL);
#undef callcount
#undef CURFRAM_NBVARNUM
#undef CURFRAM_NBVARPTR
} /*end rout_9_DO_EACH_GIMPLESEQ */
</pre>
<p>This is the whole function epilog. The MELT top frame is popped, and
the previous is reinstated.
</p>
<p>Of course, nobody wants to read or understand the generated code
above.
</p>
<p>In practice, such second-order functions (second order because they
are functionals, consuming function arguments) are often used with
anonymous functions using the <code>lambda</code> construct, eg
</p><table><tr><td> </td><td><pre class="lisp">(do_each_gimpleseq
(lambda (boxgimp) <span class="roman">;anonymous function with argument boxgimp</span>
(let ( (:long gimp
<span class="roman">; fetch the content of the boxed gimple value as an unboxed stuff</span>
(gimple_content boxgimp)) )
<var>…. do something with <code>gimp</code> stuff ….</var>
))
bgs <span class="roman">; some boxed gimple value</span>
)
</pre></td></tr></table>
<hr size="6">
<a name="Reference-on-MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Functions-in-MELT" title="Previous section in reading order"> < </a>]</td>
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<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Reference-on-MELT-1"></a>
<h2 class="section">1.7 Reference on MELT</h2>
<a name="index-Reference-on-MELT"></a>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top"><a href="#Lexical-MELT-conventions">1.7.1 Lexical MELT conventions</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#Main-MELT-syntax-and-features">1.7.2 Main MELT syntax and features</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-modules-and-translation">1.7.3 MELT modules and translation</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#Writing-GCC-passes-in-MELT">1.7.4 Writing GCC passes in MELT</a></td><td> </td><td align="left" valign="top">
</td></tr>
</table>
<hr size="6">
<a name="Lexical-MELT-conventions"></a>
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<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Lexical-MELT-conventions-1"></a>
<h3 class="subsection">1.7.1 Lexical MELT conventions</h3>
<p>It is recommended to edit MELT files with a Lisp-aware editor
(e.g. the GNU emacs Lisp mode).
</p>
<p>As in Lisp dialects:
</p>
<ul>
<li> parenthesis
are essential and should be matched. It is an error to add extra right
parenthesis.
</li><li> brackets
are like parenthesis but should be matched (but you probably don’t
want to use them). <code>[a b]</code> is the same as <code>(a b)</code> but both
<code>[a b)</code> and <code>(a b]</code> are incorrect.
</li><li> comments
start with a semicolon (<code>;</code>) to the end of the line. This is the
prefered way to put comments in MELT file.
</li><li> block comments
start with hash-bar (<code>#|</code>), may take several lines, and end with
bar-hash (<code>|#</code>). Don’t nest block comments.
</li><li> space
characters are token sepators, but indentation does not matter (we
strongly recommend the MELT code to be properly indented, e.g. using
Emacs Lisp mode, for readability purposes).
</li><li> case
is insensitive; words, i.e. identifiers and keywords are all converted
to uppercases.
</li><li> strings
are denoted like in C between double quotes, with backslashes escaping
(eg double-backslash <code>\\</code> to represent a single backslash,
backslash doublequote <code>\"</code> to represent a doublequote, backslash t
<code>\t</code> for a tab, , and <code>\xfe</code> to represent the character
coded 0xfe in hex, etc. In addition, a backslash-leftbrace <code> \{
</code> read verbatim all characters up to the first rightbrace <code> }
</code>. A string with the last doublequote followed by an underscore like
<code>"do that"_</code> is localized using the <code>gettext</code> host system
function; this could be useful for some user messages (to be
translated to other languages like french).
</li><li> symbols
(i.e. identifiers) are case insensitive and may contain non
alphanumerical characters like <code>_+-*/<>=!?:%~&@$</code>. It is advised
to use these special characters sparingly. Symbols cannot start with
any of <code>?%</code>. Because symbols are related to their C translation,
is advised to avoid digits after underscores in symbols like
<code>x_12</code> and to have each symbol contain at least one letter
(e.g. use <code><i</code> instead of <code><</code>).
</li><li> the quote character
<code>'</code> is special. <code>'x</code> is parsed the same as <code>(quote x)</code>.
</li><li> the backquote character
<code>`</code> is special. <code>`x</code> means the same as <code>(backquote x)</code>
</li><li> the comma character
<code>,</code> is special. So <code>,x</code> means <code>(comma x)</code> and <code>,(a
b)</code> is <code>(comma (a b))</code>
</li><li> the question mark chararacter
<code>?</code> is special when is is the first of a token (it may appear
inside a symbol otherwise). For instance, <code>?x</code> means
<code>(question x)</code> but <code>x?</code> is a symbol of two characters. So
<code>?y?</code> is bad taste but means <code>(question y?)</code>
</li><li> the hash character
<code>#</code> is special. In particular, <code>#|</code> starts multiline
comments; <code>#\space</code> is the integer code of the space character;
<code>#b10</code> is a binary number (i.e. two), <code>#o12</code> is octal (ie
ten), <code>#xffff</code> is hexadecimal number (ie 65535). <code>#{</code>
starts macrostrings.
</li><li> macro strings
<a name="index-macro-string-in-MELT"></a>
To avoid escaping many C-like caracters in C code chunks used for
primitives, c-iterators, c-matchers etc.. an alternative multi-line
lexical construct exist: the macro string started with <code>#{</code> and
ending with <code>}#</code> possibly on a different line with <code>$</code>
escapes like in C. For example, the <code>#{if ($A>0) printf("%s",
$B);}# </code> macrostring is parsed exactly as the 5-elements s-expression
<code> ("if (" A ">0) printf(\"%s\", " B ");")</code>. In a macrostring, all
caracters are taken as is, except the dollar sign <code>$</code>; the
macro-string itself is always read as an S-expr. When a dollar is
followed by alphanumerical (or underscore) caracters like a C
identifier, it is parsed as a symbol. If it is followed by an hash
<code>#</code> caracter, that hash-character is skipped and terminate the
symbol. The <code>$.</code> sequence is skipped and ignored, the
double-dollar <code>$$</code> is read as a single dollar, the <code>$#</code> is
read as a single hash <code>#</code>.
<p>A macro-string starting with the four characters <code>#{$'</code> is
expanded into a <code>(quote <var>...</var>)</code> expression and should
preferably not contain symbols like <code>$<var>symb</var></code>. This special
meaning of <code>$'</code> is only relevant when appearing at the very start
of the macro-string.
</p>
</li><li> braces
<code>{</code> and <code>}</code> are special.
</li><li> numbers
are integers in decimal like <code>-123</code> or <code>+22</code> or
<code>33</code>. Notice that <code>1.2</code> is illegal; it is not a floating
point number.
</li><li> colons
(i.e. <code>:</code>) starts constant (lisp-like) keywords which always evaluate to themselves.
</li></ul>
<p>Contrarily to some or most other Lisp dialects:
</p>
<ul class="toc">
<li>- don’t use the dot
for cons-ing, e.g. <code>(a b . c)</code> is not legal.
</li><li>- strings
may contain escaped braces with special verbatim-like meaning.
</li><li>- a string
whose ending doublequote is immediately followed by an underscore
(e.g. <code>"example of international"_</code>) is localized by calling
<code>gettext</code> at read time.
</li></ul>
<hr size="6">
<a name="Main-MELT-syntax-and-features"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Lexical-MELT-conventions" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-formals" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Reference-on-MELT" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Funding" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Main-MELT-syntax-and-features-1"></a>
<h3 class="subsection">1.7.2 Main MELT syntax and features</h3>
<p>We list each key symbol in alphabetical order and provide a short
derscription. Familiarity with some Lisp or Scheme dialect is
required.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top"><a href="#MELT-formals">1.7.2.1 MELT formals</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-ctypes">1.7.2.2 MELT ctypes</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-objects-and-classes">1.7.2.4 MELT objects and classes</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-function-application">1.7.2.5 MELT function application</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-function-abstraction-and-closures">1.7.2.6 MELT function abstraction and closures</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-message-sending">1.7.2.7 MELT message sending</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td><td> </td><td align="left" valign="top">
</td></tr>
</table>
<hr size="6">
<a name="MELT-formals"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Main-MELT-syntax-and-features" title="Previous section in reading order"> < </a>]</td>
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<a name="MELT-formals-1"></a>
<h4 class="subsubsection">1.7.2.1 MELT formals</h4>
<p>A formal argument list is a possibly empty list (between
parenthesis). This list contains either ctype keywords or formal
names. A ctype keyword apply to all further formals (until another
ctype keyword, or end of formal arguments list. Ctypes have a keyword
and are each described by a predefined instance (of
<code>CLASS_CTYPE</code>) with a name conventionnally starting with
<code>ctype_</code>.
<a name="index-ctype-MELT-keyword"></a>
[For experts: to add a new ctype, define a <code>BGLOB_CTYPE_*</code>
predefined in ‘<tt>gcc/melt.h</tt>’ and an instance in
‘<tt>warmelt-first.melt</tt>’ using <code>install_ctype_descr</code>, then
regenerate all the ‘<tt>gcc/warmelt-*.c</tt>’ files]
</p>
<hr size="6">
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<a name="MELT-ctypes-1"></a>
<h4 class="subsubsection">1.7.2.2 MELT ctypes</h4>
<p>Here are the list of ctype-s.
<a name="index-ctype-in-MELT-1"></a>
</p>
<ul>
<li> <code>:value</code> (ctype instance <code>ctype_value</code>)
This ctype is for MELT [boxed] values. It is the default ctype of arguments.
</li><li> <code>:long</code> (ctype instance <code>ctype_long</code>)
This ctype is for unboxed long integers; it is also used for conditions and tests.
</li><li> <code>:tree</code> (ctype instance <code>ctype_tree</code>)
This ctype is for GCC <code>tree</code> raw pointers, as in ‘<tt>gcc/tree.h</tt>’.
</li><li> <code>:gimple</code> (ctype instance <code>ctype_gimple</code>)
This ctype is for GCC <code>gimple</code> raw tuple pointers, as in ‘<tt>gcc/gimple.h</tt>’.
</li><li> <code>:gimpleseq</code> (ctype instance <code>ctype_gimple</code>)
This ctype is for GCC <code>gimple_seq</code> raw pointers, representing
sequences of gimple instructions, as in ‘<tt>gcc/gimple.h</tt>’
</li><li> <code>:basicblock</code> (ctype instance <code>ctype_basicblock</code>)
This ctype is for GCC <code>basic_block</code> raw pointers, representing
basic blocks, as in ‘<tt>gcc/basic-block.h</tt>’
</li><li> <code>:edge</code> (ctype instance <code>ctype_edge</code>)
This ctype is for GCC <code>edge</code> raw pointers, representing edges of
the control flow graph, as in ‘<tt>gcc/basic-block.h</tt>’
</li><li> <code>:void</code> (ctype instance <code>ctype_void</code>)
This ctype is the same as C <code>void</code> type. It should not be the
type of formal arguments. It is only useful as the result type of
side-effecting primitives.
</li><li> <code>:cstring</code> (ctype instance <code>ctype_cstring</code>)
This ctype is only for constant strings (like <code>const char[]</code> in
C). It is not possible to build an unboxed <code>:cstring</code>. Every
<code>:cstring</code> variable may only be bound to constant strings (not to
something inside some heap).
</li></ul>
<p>MELT formal arguments appear in <code>lambda defun defprimitive
defciterator multicall</code> forms. The first formal argument of
<code>defun lambda multicall</code> constructs should -if given- be a
<code>:value</code>. Ctype-s also appear in <code>let</code> bindings. Each MELT
expression (or constant or variable) has a ctype (usually
<code>:value</code>).
</p>
<p>The <code>:value</code> ctype is the only ctype for boxed values. Every
other ctype is for unboxed stuff.
</p>
<hr size="6">
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<a name="MELT-boxed-values-1"></a>
<h4 class="subsubsection">1.7.2.3 MELT boxed values</h4>
<a name="index-minor-MELT-garbage-collection"></a>
<a name="index-full-MELT-garbage-collection"></a>
<a name="index-values-in-MELT"></a>
<a name="index-boxed-values-in-MELT"></a>
<p>Most data manipulated by MELT code are values. Values are allocated in
the nursery generation of MELT heap, and are later (if alive) copied
into GGC heap. A <em>minor MELT garbage collection</em>, which runs
quickly and often, only copies live values (in particular, local
variables of MELT functions) out of the nursery, into the GGC heap. A
<em>full MELT garbage collection</em> also invokes the GGC collector, so
scans the entire heap.
</p>
<p>MELT boxed values can be one of:
</p>
<ul>
<li> nil
<a name="index-nil-MELT-value"></a>
(represented by the C <code>NULL</code> pointer and noted <code>()</code> in MELT)
is a value. It is the initial or default value everywhere.
</li><li> multiples
<a name="index-multiple-MELT-value"></a>
(or MELT tuples) - they are a fixed array of values agglomerated as a
multiple.
</li><li> closures
<a name="index-closure-MELT-value"></a>
(or MELT functional values) represent a functional value, containing a
routine and closed values; the only way of making closures is thru the
<code>lambda</code> and <code>defun</code> syntactic constructs.
</li><li> routines
<a name="index-routine-MELT-value"></a>
are the reification of MELT functions (generated internally).
</li><li> lists
<a name="index-list-MELT-value"></a>
are singly linked lists of pairs. Efficient access to the first and
last pair of the list are provided. Unlike in many other Lisps, lists
are not simply pairs (but implemented as the grouping of the first and
last pair contained in the list), so appending a list to another one,
or a single value at the beginning or the end of a list, is a simple
operation. Lists are never circular and have a finite length.
</li><li> pairs
<a name="index-pair-MELT-value"></a>
are like CONS pairs in most other Lisps. In particular, a list knows
its first and last pair. The head of a pair is an arbitrary boxed
value, but its tail is a pair or nil.
</li><li> triples
<a name="index-triple-MELT-value"></a>
(rarely used) have arbitrary head and middle values, but the tail is a
triple or nil. They could be used like A-lists’ nodes in Lisp.
</li><li> integers
<a name="index-integer-MELT-value"></a>
(are actually boxed longs).
</li><li> strings
<a name="index-string-MELT-value"></a>
(are like boxed cstrings; they are immutable, so the characters inside
them do not change; they are terminated by a null byte, like in C).
</li><li> string-buffers
<a name="index-string_002dbuffer-MELT-value"></a>
(are mutable buffers of strings and may grow appropriately; they are a
bit like C++ string streams).
</li><li> boxes
<a name="index-box-MELT-value"></a>
(like references in ML, are mutable boxed containers).
</li><li> objects
<a name="index-object-MELT-value"></a>
have values in their fields (or slots) and are described below; each
MELT object has a class (which is also a MELT object), which are
organized in a single-inheritance class hierarchy rooted at
<code>CLASS_ROOT</code>.
</li><li> mixints
<a name="index-mixints-MELT-value"></a>
are mixing an arbitrary mutable MELT value and an integer.
</li><li> mixlocs
<a name="index-mixlocs-MELT-value"></a>
(for experts; they are mixing an arbitrary mutable MELT value and a
<code>location_t</code> indicating a location inside e.g. a MELT or C source
file).
</li><li> object maps
<a name="index-object-map-MELT-value"></a>
are an hashtable association between MELT objects and arbitrary MELT
non-null [boxed] values.
</li><li> string maps
<a name="index-string-map-MELT-value"></a>
are an hashtable dictionnary mapping strings to arbitrary non-null
MELT values.
</li><li> boxed ctypes
<a name="index-boxed-ctype-MELT-value"></a>
Each <em>ctype</em> has its boxed representation, which is a value
containing the raw (unboxed) <em>ctype</em> like <code>gimple</code> etc..
</li><li> boxed ctype maps
<a name="index-boxed-ctype-map-MELT-value"></a>
Each <em>ctype</em> [except <code>:long :void :cstring</code>] has its boxed
map, an hash table associating (non-null) stuff of the given ctype
with arbitrary non-null MELT [boxed] values. For example, a gimple map
associate GCC <code>gimple</code>s to arbitrary MELT non-null values
(usually MELT objects). This is very useful to represent a
relationship (conceptually an attribute) between <code>gimple</code>s and
MELT values such as objects without having to enhance the definition
of the <code>gimple</code> structure inside ‘<tt>gcc/gimple.h</tt>’
</li><li> special values
<a name="index-special-MELT-values"></a>
They are useful to represent stuff like MPFR things (arbitrary
precision numbers), PPL coefficients, etc… The MELT runtime is able
to run a sort of destructing C function when a special value is no
more used, so the handling of special values is more expensive than
for other values.
</li></ul>
<p>Notice that (contrarily to most other lisps) MELT symbols and MELT
s-expressions are both objects (respectively of class
<code>CLASS_SYMBOL</code> and <code>CLASS_SEXPR</code>). The reader function
(which is not as versatile as in CommonLisp) deals with them.
</p>
<p>Adding additional MELT value types require enhancing the
‘<tt>gcc/melt.h</tt>’ and ‘<tt>gcc/melt.c</tt>’ files.
</p>
<a name="index-discriminant-for-MELT-values"></a>
<p>Each MELT [boxed] value starts with a <em>discriminant</em>. This
discriminant is a MELT object (it cannot be nil). The nil value has
conceptually its own discriminant <code>DISCR_NULLRECV</code>, but is of
course represented by C <code>NULL</code> pointer. Discriminants are used by
the garbage collector (precisely to discriminate various MELT boxed
data types using the object number of their discriminant), and by the
MELT message sending machinery (hence messages sent to the nil MELT
value are processed using the <code>DISCR_NULLRECV</code>
discriminant). Each kind of MELT value has its own discriminant, but
sometimes it is useful to have several discriminants possible for the
same kind of MELT value. For example, MELT strings can have
<code>DISCR_STRING</code> or <code>DISCR_VERBATIMSTRING</code> etc., and verbatim
strings are handled specially (in particular when printing them inside
generated C code). Every MELT [boxed] value has an immutable
discriminant, set at the time of the value’s creation.
</p>
<p>Conventionally MELT non-object values have a primitive to test them
called like <code>is_*</code>, a primitive to build them called like
<code>make_*</code> [which takes a discriminant as the first argument], and
the accessing and modifying primitives share a common prefix. In
particular, object maps are tested with <code>is_mapobject</code>, built
with <code>make_mapobject</code>, accessed with <code>mapobject_get</code> and
updated using the <code>mapobject_put</code> and <code>mapobject_remove</code>
primitives. For more details, look into file
‘<tt>gcc/melt/warmelt-first.melt</tt>’.
</p>
<hr size="6">
<a name="MELT-objects-and-classes"></a>
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<a name="MELT-objects-and-classes-1"></a>
<h4 class="subsubsection">1.7.2.4 MELT objects and classes</h4>
<a name="index-object-MELT-values"></a>
<a name="index-MELT-objects"></a>
<p>An important (and common) kind of MELT [boxed] values are MELT
objects. A MELT object contains exactly
</p>
<ul>
<li> the discriminant or class
<a name="index-MELT-classes"></a>
<a name="index-class-in-MELT"></a>
of the object; as every [boxed] value, MELT objects starts with a
discriminant; for objects, it is their <em>class</em>, which is an
object itself. We say “<var>Cl</var> is the class of <var>Ob</var>” or
equivalently “<var>Ob</var> is a [direct] instance of <var>Cl</var>” when
<var>Ob</var> is a MELT object of discriminant <var>Cl</var>.
</li><li> the hash code
of the object is an unsigned non-zero (more or less random, immutable
i.e. fixed) integer, given at object build time (i.e. instanciation
time).
</li><li> the object number
or <em>objnum</em> of the object is a small unsigned short integer. It
is usually assigned at object build time. For discriminants <var>Di</var>,
their objnum is also called the <em>magic number</em> of the values
<var>Va</var> of the given discriminant <var>Di</var>.
</li><li> the object length
or size is the number of slots or fields of the objects. All objects
<var>Ob</var> of a given class <var>Cl</var> have the same fixed number of slots
(no more than 32767 slots and almost always a lot less, e.g. at most a
dozen). Some objects could have a length of 0 (if their class is the
<code>CLASS_ROOT</code> or has no direct or inherited fields), but this is
very unusual.
</li><li> the object slots
or object fields are the values contained inside the object. These
fields may be mutable; their number is fixed (it is the object
length).
</li></ul>
<p>In practice, every object’s slot is described by a field object (of
class <code>CLASS_FIELD</code>) inside the object’s class.
</p>
<p>Every discriminant (in particular every class) is an object with the following fields (or slots):
</p><ul>
<li> <code>prop_table</code>
is the property object map associating objects to values, and usable as a P-list.
</li><li> <code>named_name</code>
is the boxed string naming the discriminant.
</li><li> <code>disc_methodict</code>
is an object map associating selectors to closures (method implementations).
</li><li> <code>disc_super</code>
is the super-discriminant (or the super-class for objects)
</li></ul>
<p>The root discriminant is <code>DISCR_ANYRECV</code>. The discriminant of the
nil value is <code>DISCR_NULLRECV</code>. Other types of values have
discriminants like <code>DISCR_ANYRECV DISCR_BASICBLOCK DISCR_BOX
DISCR_CHARINTEGER DISCR_CLOSURE DISCR_EDGE DISCR_GIMPLE
DISCR_GIMPLESEQ DISCR_INTEGER DISCR_LIST DISCR_MAPBASICBLOCKS
DISCR_MAPEDGES DISCR_MAPGIMPLES DISCR_MAPGIMPLESEQS DISCR_MAPOBJECTS
DISCR_MAPSTRINGS DISCR_MAPTREES DISCR_METHODMAP DISCR_MIXEDINT
DISCR_MIXEDLOC DISCR_MULTIPLE DISCR_NAMESTRING DISCR_NULLRECV
DISCR_PAIR DISCR_ROUTINE DISCR_SEQCLASS DISCR_SEQFIELD DISCR_STRBUF
DISCR_STRING DISCR_TREE DISCR_VERBATIMSTRING</code>. Some discriminants are
specialized by having a meaningful (i.e. not <code>DISCR_ANYRECV</code>)
super-discriminant (i.e. the value inside the <code>:disc_super</code>
slot). For example, <code>DISCR_METHODMAP</code> is used for object maps
which are method maps (mapping a selector to a function implementing a
method), instead of the plain <code>DISCR_MAPOBJECTS</code>. [For experts:]
It is possible to make additional discriminants using
<code>definstance</code> with <code>CLASS_DISCR</code> as the class.
</p>
<p>Classes are discriminants, but in addition have the following fields
(or slots):
</p><ul>
<li> <code>class_ancestors</code>
is the multiple (of discriminant <code>DISCR_SEQCLASS</code>) of the
classes’ ancestors. Testing that a given object has some given class
as its direct class or indirect ancestor is quick (<code>is_a</code>
primitive in MELT, <code>melt_is_instance_of</code> function in C code).
</li><li> <code>class_fields</code>
is the multiple (of <code>DISCR_SEQFIELD</code>) of the classes’ fields
(both inherited from ancestors or own to the class).
</li><li> <code>class_objnumdescr</code>
is usable for describing the objnum of instances.
</li><li> <code>class_data</code>
is an additional slot for holding class data.
</li></ul>
<p>Fields are slot descriptors (objects of <code>CLASS_FIELD</code>), they are
named (so inherit fields <code>prop_table named_name</code>). Their objnum
is their index, their specific slots are
</p><ul>
<li> <code>fld_ownclass</code>
gives the class defining the field.
</li><li> <code>fld_typinfo</code>
can be used for describing the field’s type in instances.
</li></ul>
<p>Beware that the structure of classes, fields and discriminants is
described not only in ‘<tt>warmelt-first.melt</tt>’ but also “built-in”
in files ‘<tt>melt.c</tt>’ and ‘<tt>melt.h</tt>’ so changing them is
very tricky.
</p>
<p>Fields should have a <em>globally unique</em> name. Conventionally,
fields common to the same class share a common prefix for their name.
</p>
<p>The <code>defclass</code> construct builds and fills class and fields
objects. Don’t make instances of <code>CLASS_CLASS</code> or
<code>CLASS_FIELD</code> otherwise!
</p>
<p>Objects are built using the <code>make_instance</code> construct, or
statically using <code>definstance</code>. In addition, <code>defselector
defclass</code> also statically build objects (likes classes and fields).
</p>
<p>Exporting a class means exporting the class object and its own fields.
</p>
<hr size="6">
<a name="MELT-function-application"></a>
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<a name="MELT-function-application-1"></a>
<h4 class="subsubsection">1.7.2.5 MELT function application</h4>
<p>Function applications are noted <code>(<var>fun</var> <var>args</var>
<var>…</var>)</code>. There may be no arguments, e.g. just
<code>(<var>fun</var>)</code>. If arguments are given, the first argument must be
a <code>:value</code>. So <code>(f 1 x)</code> is incorrect (because <code>1</code> is
an unboxed <code>:long</code>); use <code>(f x 1)</code> instead. Usually, the
<var>fun</var>ction is just a variable bound to a function, but it may be a
more complex expression, like <code>((if (p x) f g) x y)</code> which,
depending on the test <code>(p x)</code> applies either <code>f</code> or <code>g</code>
to <code>x y</code>.
</p>
<p>The application of a non-function returns null. The
<code>melt_apply</code> C function doing the application checks that the
applied function is indeed a function (ie a closure). Function
applications are never tail-recursive; they always consume some stack
space.
</p>
<p>Named functions are defined using the <code>defun</code> construct, using a
Common Lisp like syntax (not the Scheme <code>define</code>). If the formal
arguments list is not empty, its first element (the first formal
argument of a named or anonymous function) should be a <code>:value</code>.
</p>
<p>Functions are not polytopic nor polymorphic; their signature is
essentially fixed. They should expect a fixed number of arguments
[there is no variable argument facility in MELT], each with a defined
ctype (the first argument should be a <code>:value</code>), and return a
fixed number of results (the first result should be a <code>:value</code>)
each with a defined ctype. An argument which has not the expected
ctype or is missing is initialized to null or 0. Likewise a secundary
result which has not the expected ctype is ignored or set to null or
0.
</p>
<p>A function should [always] return a primary result of ctype
<code>:value</code> and may also return secondary results (using the
<code>return</code> construct). The only way of getting the secondary
results of a function call (or a message send) is thrue the
<code>multicall</code> construct, which binds all the results of the call or
send to the formal arguments in the <code>multicall</code>. Function
applications not done in a <code>multicall</code> have all their secondary
results (if any) ignored.
</p>
<hr size="6">
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<a name="MELT-function-abstraction-and-closures-1"></a>
<h4 class="subsubsection">1.7.2.6 MELT function abstraction and closures</h4>
<p>Function abstraction (i.e. making anonymous functions) is done using
the <code>lambda</code> construct. <em>Only values can be closed</em>, hence
it is not possible to close a non-boxed value, so <code>(let ( (:long
one 1) ) (lambda (a) (f a one)))</code> is incorrect (and rejected by the
MELT translator).
</p>
<p>Actually, every MELT function is really a closure, so <code>defun</code>
binds a name to the closure which is the named function.
</p>
<p>Closures are <code>:value</code>s. Use the <code>is_closure</code> primitive to
test tha a given value is indeed a closure. The only way of building
closures is thru <code>lambda</code> or <code>defun</code>. Closures contain a
routine pointer (routines are also <code>:values</code>) and closed
values. [For experts] the size of a closure is available thru the
<code>closure_size</code> primitive. Its routine is available thru
<code>closure_routine</code> primitive. To get its n-th closed value, use
the <code>closure_nth</code> primitive. At MELT runtime, each MELT call
frame for MELT function application (or message sending) knows its
closure.
</p>
<p>Routines correspond to MELT generated C functions (with their constant
values).
</p>
<hr size="6">
<a name="MELT-message-sending"></a>
<table cellpadding="1" cellspacing="1" border="0">
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<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-message-sending-1"></a>
<h4 class="subsubsection">1.7.2.7 MELT message sending</h4>
<p>A message invocation is done using the construct
<code>(<var>selector-name</var> <var>reciever</var> <var>args</var> <var>…</var>)</code>. This
construct is syntactically the same as function (or primitive)
application, and is discriminated by the fact that the
<var>selector-name</var> has been previously defined with
<code>defselector</code> or is imported as bound to an instance of
<code>CLASS_SELECTOR</code>. The selector should be such a name and cannot
be an expression. The <var>reciever</var> can be any <code>:value</code> (even
null). The <var>args</var> are optional and can have any ctype (but a
selector should have a fixed and well defined signature). Use
<code>export_values</code> to export selectors.
</p>
<p>A method is just a functional value, installed thru the
<code>install_method</code> function. This function expects a discriminant
or class, a selector, and a function (the method). Method installation
is very dynamic and can be done at any time.
</p>
<p>A message invocation (i.e. an expression starting with a selector) can
be done on any boxed value. If it is an object, its class is used;
otherwise its discriminant is used (so <code>DISCR_NULLRECV</code> is used
when sending to nil). To send a message of selector <var>sel</var> (an
instance of <code>CLASS_SELECTOR</code>) to a reciever <var>recv</var> of
discriminant (e.g. the class of an object) <var>dis</var>, the following
procedure is used:
</p>
<ul>
<li> <var>dis</var> should be a discriminant;
if it is not an instance of <code>CLASS_DISCR</code>, stop and do nothing.
</li><li> get the <code>discr_methodmap</code> slot of <var>dis</var>;
it should be an object map (i.e. a “dictionnary” of methods) that we
call <var>md</var>.
</li><li> get the method <var>meth</var>
associated to <var>sel</var> in <var>md</var>; if <var>meth</var> is a function
(i.e. a boxed MELT closure), apply <var>meth</var> to the reciever
<var>recv</var> and any additional arguments. This ends the message
invocation.
</li><li> otherwise,
no method is found, so replace <var>dis</var> by its super-discriminant
(its slot <code>disc_super</code>) and repeat again. Hence, methods are also
looked in superclasses, etc… so are properly inherited.
</li></ul>
<p>Notice that message invocation is more dynamic (hence slower) than
e.g. C++ virtual member functions, and that method maps can be
upgraded at any time.
</p>
<hr size="6">
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</tr></table>
<a name="MELT-syntax-constructs-1"></a>
<h4 class="subsubsection">1.7.2.8 MELT syntax constructs</h4>
<p>The table below gives MELT syntax constructs, in alphabetical
order. [Experts can add new constructs using macros, and implementing
appropriate methods in the MELT translator].
</p>
<dl compact="compact">
<dt> <code>and</code></dt>
<dd><a name="index-and-MELT-syntax"></a>
<p><code>(and <var>e1</var> <var>e2</var> <var>e3</var> <var>…</var>)</code> is (like in all
Lisps) used for sequential conjunction; it is the same as <code>(if
<var>e1</var> (if <var>e2</var> <var>e3</var>))</code> etc… Any number (at least one) of
conjuncts are possible. All the conjuncts (<var>e1</var> <var>…</var>) should
have the same ctype (usually <code>:value</code>).
</p>
</dd>
<dt> <code>assert_msg</code></dt>
<dd><a name="index-assert_005fmsg-MELT-syntax"></a>
<a name="index-assert_005ffailed-MELT-primitive"></a>
<p><code>(assert_msg <var>msg</var> <var>check</var>)</code> aborts when <var>check</var> is
false (using the <code>assert_failed</code> primitive, giving the source file
position) and displays the given <var>msg</var>, when GCC is built for
debugging with <code>ENABLE_CHECK</code>. If GCC is not built for debugging,
neither operand is used. The entire <code>assert_msg</code> expression
evaluates to nil.
</p>
</dd>
<dt> <code>comment</code></dt>
<dd><a name="index-comment-MELT-syntax"></a>
<p><code>(comment <var>msg</var>)</code> evaluates to nil and output the <var>msg</var>
as a C comment in the C translation. Don’t use <code>*/</code> or <code>*/</code>
in <var>msg</var>. When a <code>comment</code> appears at the beginning of a MELT
compilation unit, it appears at the beginning of the generated C file;
this is useful for making copyright notices appear both in the MELT
source file and the generated C code.
</p>
</dd>
<dt> <code>compile_warning</code></dt>
<dd><a name="index-compile_005fwarning-MELT-syntax"></a>
<p><code>(compile_warning <var>msg</var> <var>exp</var>)</code> evaluates like <var>exp</var> but also
emits a message at MELT compilation time. Intended use is similar to
<code>#warning</code> in C.
</p>
</dd>
<dt> <code>cond</code></dt>
<dd><a name="index-cond-MELT-syntax"></a>
<p><code>(cond <var>condition1</var> <var>condition2</var> <var>…</var>)</code> is -like in
all Lisps- a conditional evaluation. Each condition is
<code>(<var>test</var> <var>then1</var> <var>then2</var> <var>…</var> <var>thenk</var>)</code> so
the <var>test</var> is evaluated. If it is true, all the <var>then</var>s are
evaluated in sequence, and the last is the result of the whole
<code>cond</code> expression. The last condition can be <code>(:else
<var>else1</var> <var>…</var> <var>elsek</var>)</code>; if no previous test succeeded,
all the <var>else</var>s are sequentially evaluated, and the last of them
is the whole <code>cond</code> result. Notice that <code>(cond (<var>test1</var>
<var>then1</var>) (<var>test2</var> <var>then2a</var> <var>then2b</var>) (:else
<var>else1</var> <var>else2</var> <var>else3</var>))</code> is the same as <code>(if
<var>test1</var> <var>then1</var> (if <var>test2</var> (progn <var>then2a</var>
<var>then2b</var>) (progn <var>else1</var> <var>else2</var>)))</code>.
</p>
</dd>
<dt> <code>cppif</code></dt>
<dd><a name="index-cppif-MELT-syntax"></a>
<p>[for experts] <code>(cppif <var>name</var> <var>then-cpp</var> <var>else-cpp</var>)</code> is translated
using a C directive <code>#if <var>name</var></code> to the translation of
<var>then-cpp</var> or <var>else-cpp</var>.
</p>
</dd>
<dt> <code>current_module_environment_container</code></dt>
<dd><a name="index-current_005fmodule_005fenvironment_005fcontainer-MELT-syntax"></a>
<p>[for experts] <code>(current_module_environment_container)</code> evaluates
to an object of <code>CLASS_CONTAINER</code> containing the current module
environment.
</p>
</dd>
<dt> <code>debug_msg</code></dt>
<dd><a name="index-debug_005fmsg-MELT-syntax"></a>
<p><code>(debug_msg <var>expv</var> <var>msg</var> [<var>count</var>])</code> -where the
<var>count</var> expression (of ctype <code>:long</code>) is usually ommitted- is
useful for debugging ouput of the value of <var>expv</var> (with the
<code>-fmelt-debug</code> program option) to output, using the
<code>debug_msg_fun</code> function. The entire <code>debug_msg</code> expression
is somehow equivalent to <code>(cppif ENABLE_CHECKING (debug_msg_fun
<var>expv msg count filename lineno</var>) ())</code> and evaluates to nil.
</p>
</dd>
<dt> <code>defciterator</code></dt>
<dd><a name="index-defciterator-MELT-syntax"></a>
<p>The form <code>(defciterator <var>iter-name</var> <var>start-formals</var>
<var>state-symbol</var> <var>local-formals</var> <var>before-expansion</var>
<var>after-expansion</var>)</code> defines a C-iterator named
<var>iter-name</var>. The <var>start-formals</var> is a [binding] list of formal
arguments [given to the C-iterator]. The <var>state-symbol</var> is usable
in the expansions, where it is expanded to a unique C identifier. The
<var>local-formals</var> is a [binding] list of variables local to the
expanded block. The <var>before-expansion</var> and <var>after-expansion</var>
are lists of items like strings (appearing as is in the C expansion)
or symbols (either from the start formals, or the local formals, or
the state symbol).
</p>
</dd>
<dt> <code>defclass</code></dt>
<dd><a name="index-defclass-MELT-syntax"></a>
<p>The form <code>(defclass <var>class-name</var> [:predef <var>predefined</var>]
[:super <var>superclass-name</var>] :fields <var>fields-list</var>)</code> defines a
class named <var>class-name</var> of super-class named
<var>superclass-name</var> with the given <var>fields-list</var> (a list of
field names) and an optional <var>predefined</var> name (for predefined
classes [giving a <var>predefined</var> is for experts]).
</p>
</dd>
<dt> <code>defcmatcher</code></dt>
<dd><a name="index-defcmatcher-MELT-syntax_002e"></a>
<p>The form <code>(defcmatcher <var>cmatcher-name</var> <var>match&in-formals</var>
<var>out-formals</var> <var>state-sym</var> <var>test-expansion</var>
<var>fill-expansion</var> <var>oper-expansion</var>)</code> defined a matching
construct by its C translation. The <var>match&in-formals</var> gives the
matched thing ctype (as the first formal argument, either a boxed
value or a raw stuff) and input arguments (rest of formals). The
<var>out-formals</var> are the signature of the deconstructed things. The
<var>test-expansion</var> expands (as a C boolean-like expression) to the
test part of the match. The <var>fill-expansion</var> expands (as a
sequence of C instructions) to the deconstructing part. The
<var>oper-expansion</var> is used, much like in primitives, when the
<var>cmatcher-name</var> appears as an operator in an expression context.
</p>
</dd>
<dt> <code>definstance</code></dt>
<dd><a name="index-definstance-MELT-syntax"></a>
<p>The form <code>(definstance <var>instance-name</var> <var>class-name</var>
[:predef <var>predefined</var>] [:obj_num <var>object-number</var>]
<var>:field-name</var> <var>field-value</var> <var>…</var>)</code> statically defines an
instance of name <var>instance-name</var> of the class
<var>class-name</var>. [expert usage: a <var>predefined</var> name and an
<var>object-number</var> may also be given].
</p>
</dd>
<dt> <code>defprimitive</code></dt>
<dd><a name="index-defprimitive-MELT-syntax"></a>
<p>The form <code>(defprimitive <var>primitive-name</var>
<var>formals-arglist</var> <var>ctype</var> <var>expansion</var> <var>…</var>)</code>
statically defines a C primitive named <var>primitive-name</var> of a given
<var>formals-list</var> and given return <var>ctype</var>. The <var>expansion</var>-s
are either strings or formal names.
</p>
</dd>
<dt> <code>defselector</code></dt>
<dd><a name="index-defselector-MELT-syntax"></a>
<p>The form <code>(defprimitive <var>selector-name</var> <var>selector-class</var>
<var>:field-name</var> <var>field-value</var> <var>…</var>)</code> defines a
selector. Usually <var>selector-class</var> is <code>CLASS_SELECTOR</code>, and
no other <var>field</var>s are given. Once a name is bound to a selector,
every further occurrence of that name in operator position is
considered as a message invocation.
</p>
</dd>
<dt> <code>defun</code></dt>
<dd><a name="index-defun-MELT-syntax"></a>
<p>The form <code>(defun <var>function-name</var> <var>formals-list</var>
<var>body</var> <var>…</var>)</code> define a function named
<code>function-name</code>. The ctype of the first (if any) formal argument
(in the <var>formals-list</var>) should be a <code>:value</code>. The
<code>function-name</code> can appear in the given <var>body</var> (for
recursion).
</p>
</dd>
<dt> <code>exit</code></dt>
<dd><a name="index-exit-MELT-syntax"></a>
<p>The form <code>(exit <var>loop-label</var> <var>expr</var> <var>…</var>)</code>, only
used inside <code>forever</code> loops, causes the lexically enclosing
<code>forever</code> loop named by <var>loop-label</var> to be exited, after
evaluation of the <var>expr</var>s. The last such value (or nil if no
<var>expr</var> is given) is the result returned by the <code>forever</code>
loop. <code>exit</code> forms are similar to Ada’s <code>exit</code> or C
<code>break</code> (not to <code>longjmp</code>). The <code>exit</code> should be local
to the containing procedure: it cannot jump across <code>lambda</code>s.
</p>
</dd>
<dt> <code>export_class</code></dt>
<dd><a name="index-export_005fclass-MELT-syntax"></a>
<p>The form <code>(export_class <var>class-name</var> <var>…</var>)</code> export all
the given <var>class-name</var>s and their fields.
</p>
</dd>
<dt> <code>export_macro</code></dt>
<dd><a name="index-export_005fmacro-MELT-syntax"></a>
<p>[For experts] The form <code>(export_macro <var>macro-symbol</var>
<var>expander</var>)</code> exports a macro binding for the given
<var>macro-symbol</var> with the <var>expander</var> function. The macro
<code>macro-symbol</code> is defined in the environment exported by the
current module, so is available in other modules only (but not in the
current one).
</p>
</dd>
<dt> <code>export_patmacro</code></dt>
<dd><a name="index-export_005fpatmacro-MELT-syntax"></a>
<p>[For experts, not implemented] The form <code>(export_patmacro
<var>patmacro-symbol</var> <var>pat-expander</var> <var>mac-expander</var>)</code> exports
a pattern macro binding for the given <var>patmacro-symbol</var> with the
<var>pat-expander</var> as a pattern expanding function (used in patterns)
and the <var>mac-expander</var> as a macro expanding function (used in
expressions).
</p>
</dd>
<dt> <code>export_values</code></dt>
<dd><a name="index-export_005fvalues-MELT-syntax"></a>
<p>The form <code>(export_values <var>exported-name</var> <var>…</var>)</code> export
all the names, as values, given as arguments. For classes,
<code>export_class</code> should be used, otherwise the fields are not
exported.
</p>
</dd>
<dt> <code>fetch_predefined</code></dt>
<dd><a name="index-fetch_005fpredefined-MELT-syntax"></a>
<p>[For experts] <code>(fetch_predefined <var>predefined-name-or-number</var>)</code>
</p>
</dd>
<dt> <code>forever</code></dt>
<dd><a name="index-forever-MELT-syntax"></a>
<p><code>(forever <var>label-name</var> <var>body</var> <var>…</var>)</code> when
evaluated, the bodies are evaluated in sequence, and indefinitely
re-evaluated again. The only way of getting out from a <code>forever</code>
loop is with <code>exit</code> (using the given <var>label-name</var>, lexically
inside the body) or <code>return</code>. Avoid using a bound variable name
as a <var>label-name</var>.
</p>
</dd>
<dt> <code>get_field</code></dt>
<dd><a name="index-get_005ffield-MELT-syntax"></a>
<p><code>(unsafe_get_field <var>:field-name</var> <var>expr</var>)</code> retrieves the
field named <var>:field-name</var> from the object returned by <var>expr</var>
expression. If it is not an appropriate object (of the class owning
the <var>:field-name</var>) , gives nil.
</p>
</dd>
<dt> <code>if</code></dt>
<dd><a name="index-if-MELT-syntax"></a>
<p><code>(if <var>test</var> <var>then-exp</var> [<var>else-exp</var>])</code>. When
evaluated, the <var>test</var> is first evaluated. If it is true, the
<var>then-exp</var> is evaluated and is the result of the whole
<code>if</code>. If it is false (either 0 if ctype-d <code>:long</code>, or the
null pointer for <code>:value</code> and other ctypes), the optional
<var>else-exp</var> is evaluated (or 0 or null) and is the result of the
whole <code>if</code>. Both the <var>then-exp</var> and the <var>else-exp</var> (if
given) should have the same ctype.
</p>
</dd>
<dt> <code>instance</code></dt>
<dd><a name="index-instance-MELT-syntax"></a>
<p><code>(instance <var>class-name</var> [<var>:field-name</var> <var>field-value</var>]
<var>…</var>)</code> is a constrctive expression for instances, where the
<var>class-name</var> is the name of a class (it cannot be a complex
expression but should be a class statically known) and where each
<var>:field-name</var> keyword (starting with a colon) is the name of some
field (direct or inherited) of the class and the following
<var>field-value</var> is an expression giving its initial value; the
result of <code>instance</code> is a freshly built instance of the given
<var>class-name</var> initialized with the fields (fields which are not
mentionned are initialized with nil).
</p>
</dd>
<dt> <code>lambda</code></dt>
<dd><a name="index-lambda-MELT-syntax"></a>
<p><code>(lambda <var>formal-args</var> <var>body</var> <var>…</var>)</code> is a
constructive expression for function abstraction, it returns a
closure, the anonymous function taking <var>formal-args</var> as arguments
and evaluating sequentially the <var>body</var> expressions, returning the
value of the last one. The first argument of a function and the first
result that it is returning should be a <code>:value</code>.
</p>
</dd>
<dt> <code>let</code></dt>
<dd><a name="index-let-MELT-syntax"></a>
<p><code>(let (<var>let-binding</var> <var>…</var>) <var>body</var> <var>…</var>) is a
sequential binding construct (closer to <code>let*</code> in other
Lisps)</code>. The first operand should be a list of
<var>let-binding</var>s. Others operands make the <var>body</var>, evaluated in
sequence with the new bindings applied with lexical scoping. A
<var>let-binding</var> is an optional <em>ctype</em> (<code>:value</code> by
default) followed by a variable name (ie a symbol) followed by one
expression. Variables bound by previous <var>let-binding</var>s are visible
in the expression inside the current <var>let-binding</var> (so recursion
is not permitted like with <code>flet</code> or <code>letrec</code> in some
Lisps). Notice that a <var>let-binding</var> can bind a variable to unboxed
stuff (like a plain long integer). The result of the whole <code>let</code>
expression is the result of the evaluation of the last body
expression, done with the new bindings.
</p>
</dd>
<dt> <code>letrec</code></dt>
<dd><a name="index-letrec-MELT-syntax"></a>
<p><code>(let (<var>letrec-binding</var> <var>…</var>) <var>body</var> <var>…</var>)</code> is a
recursive binding construct. The letrec bindings should only bind
<em>constructive expressions</em>, that is <code>lambda</code>-s, <code>tuple</code>-s,
<code>instance</code>-s and <code>list</code>-s.
</p>
</dd>
<dt> <code>list</code></dt>
<dd><a name="index-list-MELT-syntax"></a>
<p><code>(list <var>expr</var> <var>…</var>)</code> is a constructive expressions
for lists. It returns a tuple
made of the arguments.
</p>
</dd>
<dt> <code>match</code></dt>
<dd><a name="index-match-MELT-syntax"></a>
<p><code>(match <var>expr</var> <var>match-case</var> <var>…</var> )</code> <em>NOT
IMPLEMENTED YET</em> Do a pattern match. Evaluate <var>expr</var> and for the
first maching <var>match-case</var>, do its body. There is no <code>:else</code>
clause, use the joker pattern <code>?_</code> for that purpose. A
<var>match-case</var> is a simple match case <code>(<var>pattern</var>
<var>body</var> <var>…</var>)</code> where <var>body</var> is evaluated with the
pattern variables appearing in <var>pattern</var> bound. A <var>match-cas</var>
can be a when match case <code>(:when <var>pattern</var> <var>when-cond</var>
<var>body</var> <var>…</var>)</code> where the body is done when that pattern
matches and the <var>when-cond</var> (evaluated with the pattern variables
bound) is a true condition.
</p>
</dd>
<dt> <code>multicall</code></dt>
<dd><a name="index-multicall-MELT-syntax"></a>
<p><code>(multicall (<var>result-formals</var>) <var>call-expr</var> <var>body</var>
<var>…</var>)</code> is the only way to retrieve multiple (one primary and
some secondary) results from a function application or a message
invocation <var>call-expr</var> (which should syntactically be an
application or an invocation, not anything else). The
<var>result-formals</var> are syntactically like formal arguments;
See section <a href="#MELT-formals">MELT formals</a>. The first result formal should be of ctype
<code>:value</code>. Secondary result formals which are not matching the
ctype of the actual secondary result are cleared. The bindings of the
result formals are local to the <code>multicall</code> expression and usable
in the <var>body</var> sequence.
</p>
</dd>
<dt> <code>or</code></dt>
<dd><a name="index-or-MELT-syntax"></a>
<p><code>(or <var>e1</var> <var>e2</var> <var>e3</var> <var>…</var>)</code> is the sequential
disjunction of <var>e1</var> <var>…</var> (at least one disjunct). In
particular <code>(or <var>a</var> <var>b</var>)</code> is the same as <code>(if
<var>a</var> <var>a</var> <var>b</var>)</code> except that <var>a</var> is evaluated once. All
the disjuncts should have the same ctype (usually <code>:value</code>).
</p>
</dd>
<dt> <code>parent_module_environment</code></dt>
<dd><a name="index-parent_005fmodule_005fenvironment-MELT-syntax"></a>
<p>[For experts] <code>(parent_module_environment)</code> return the parent
module’s environment.
</p>
</dd>
<dt> <code>progn</code></dt>
<dd><a name="index-progn-MELT-syntax"></a>
<p><code>(progn <var>e1</var> <var>e2</var> <var>…</var> <var>en</var>)</code> evaluates
successfully <var>e1</var> then <var>e2</var> and return the value of the last
<var>en</var>.
</p>
</dd>
<dt> <code>put_fields</code></dt>
<dd><a name="index-put_005ffields-MELT-syntax_002e"></a>
<p><code>(put_fields <var>obj</var> <var>:field-name1</var> <var>val1</var>
<var>…</var>)</code> updates the object value of <var>obj</var> by changing its
field named <var>:field-name1</var> to the value of <var>val1</var> etc…
(all the fields are updated at once). It is safe, in the sense that if
<var>obj</var> is not an object of the appropriate class, nothing happens.
</p>
</dd>
<dt> <code>quote</code></dt>
<dd><a name="index-quote-MELT-syntax"></a>
<p><code>(quote x)</code> is the same as <code>'x</code> and returns the symbol
<code>x</code> itself (as an instance of <code>CLASS_SYMBOL</code>). When applied
to an integer, like <code>'1</code>, it gives a constant boxed integer value
(of <code>DISCR_INTEGER</code>). When applied to a string, like
<code>'"string"</code>, it gives a constant boxed string value (of
<code>DISCR_STRING</code>). Therefore, when passed as an actual argument (to
a primitive, a function, ...) <code>'1</code> (a boxed integer value) is not
the same as <code>1</code> (a raw integer stuff), and likewise <code>'"abc"</code>
is a boxed string value, different of <code>"abc"</code> (a raw string
stuff). This is very different from other Lisps! Only symbols,
strings, integers can be quoted.
</p>
</dd>
<dt> <code>return</code></dt>
<dd><a name="index-return-MELT-syntax"></a>
<p><code>(return <var>e1</var> <var>…</var>)</code> return from the entire containing
function (i.e. <code>defun</code> or <code>lambda</code>). The first expression
<var>e1</var> should be of ctype <code>:value</code> and is evaluated as the
primary result. Other expressions are evaluated (and can have
different ctypes) and returned as secondary results. A <code>(return)</code>
without argument is a convenience for returning the nil value. The
ctype of the <code>return</code> is <code>:value</code> even if the <code>return</code>
expression itself does not gives a value (because it breaks the
control flow), hence <code>(or (return) 'x)</code> is acceptable but
tasteless.
</p>
</dd>
<dt> <code>setq</code></dt>
<dd><a name="index-setq-MELT-syntax"></a>
<p><code>(setq <var>var</var> <var>exp</var>)</code> assigns to the local variable
<var>var</var> the value of <var>exp</var> (which is also the value of the
entire <code>setq</code> expression). Both <var>var</var> and <var>exp</var> should
have the same ctype.
</p>
</dd>
<dt> <code>store_predefined</code></dt>
<dd><a name="index-store_005fpredefined-MELT-syntax"></a>
<p>[Expert] <code>(store_predefined <var>predef-name-or-number</var>
<var>expr</var>)</code> Don’t use it if you don’t understand.
</p>
</dd>
<dt> <code>tuple</code></dt>
<dd><a name="index-tuple-MELT-syntax"></a>
<p><code>(tuple <var>expr</var> <var>…</var>)</code> is a constructive expressions
for tuples (or multiples). It returns a tuple made of the arguments.
</p>
</dd>
<dt> <code>unsafe_get_field</code></dt>
<dd><a name="index-unsafe_005fget_005ffield-MELT-syntax"></a>
<p><code>(unsafe_get_field <var>:field-name</var> <var>expr</var>)</code> retrieves the
field named <var>:field-name</var> from the object returned by <var>expr</var>
expression (of ctype <code>:value</code>). If <var>expr</var> does not evaluates
to an object instance (directly or indirectly) of the class defining
the <var>:field-name</var> the behavior is undefined, and unsafe (GCC
usually crashes).
</p>
</dd>
<dt> <code>unsafe_put_fields</code></dt>
<dd><a name="index-unsafe_005fput_005ffields-MELT-syntax"></a>
<p><code>(unsafe_put_fields <var>obj</var> <var>:field-name1</var> <var>val1</var>
<var>…</var>)</code> updates the object value of <var>obj</var> by changing its
field named <var>:field-name1</var> to the value of <var>val1</var> etc… (all
the fields are updated at once). If <var>obj</var> is not an object of the
appropriate class for the fields, the behavior is undefined and unsafe
(usually GCC crashes).
</p>
</dd>
<dt> <code>update_current_module_environment_container</code></dt>
<dd><a name="index-update_005fcurrent_005fmodule_005fenvironment_005fcontainer-MELT-syntax"></a>
<p>[Expert] <code>(update_current_module_environment_container)</code> don’t
use it if you don’t understand.
</p>
</dd>
</dl>
<hr size="6">
<a name="MELT-modules-and-translation"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#MELT-syntax-constructs" title="Previous section in reading order"> < </a>]</td>
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<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-modules-and-translation-1"></a>
<h3 class="subsection">1.7.3 MELT modules and translation</h3>
<p>[for experts mostly; familiarity with the notions of bindings and
environments is expected.]
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top"><a href="#MELT-environments-and-bindings">1.7.3.1 MELT environments and bindings</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#translating-a-MELT-module">1.7.3.2 translating a MELT module</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-module-initialization-and-exports">1.7.3.3 MELT module initialization and exports</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td><td> </td><td align="left" valign="top">
</td></tr>
</table>
<hr size="6">
<a name="MELT-environments-and-bindings"></a>
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<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-environments-and-bindings-1"></a>
<h4 class="subsubsection">1.7.3.1 MELT environments and bindings</h4>
<p>A MELT module uses previously available bindings (imported values,
etc..) and provides its own bindings (exported values,
etc..). Bindings are objects (of superclass <code>CLASS_ANY_BINDING</code>,
e.g. of some class like <code>CLASS_VALUE_BINDING</code>
<code>CLASS_MACRO_BINDING</code> <code>CLASS_PATMACRO_BINDING</code>
<code>CLASS_INSTANCE_BINDING</code> etc…). Bindings are grouped in
environments (themselves objects of class
<code>CLASS_ENVIRONMENT</code>). Each environment is linked to its
parent. So a MELT module is initialized in its parent module
environment and gives its own module environment.
</p>
<p>Hence MELT environments are objects with a <code>env_bind</code> field (the
object map of bindings), a <code>env_prev</code> field (the previous
environment), etc… All bindings are objects with a <code>binder</code>
field (the bound “name”, e.g. a symbol, used as the key in the
binding map of environments).
</p>
<p>User MELT code is ordinarily not supposed to explicitly change
environments and bindings (but they are changed implicitly at module
initialization).
</p>
<hr size="6">
<a name="translating-a-MELT-module"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#MELT-environments-and-bindings" title="Previous section in reading order"> < </a>]</td>
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<td valign="middle" align="left"> </td>
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<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="translating-a-MELT-module-1"></a>
<h4 class="subsubsection">1.7.3.2 translating a MELT module</h4>
<a name="index-translation-of-MELT"></a>
<p>A MELT file ‘<tt><var>foo</var>.melt</tt>’ [which can be viewed as defining the
<var>foo</var> MELT module] is translated into a C source
‘<tt><var>foo</var>.c</tt>’ which is then compiled into a dynamically loadable
shared library - usually ‘<tt><var>foo</var>.so</tt>’ on Linux. The translation
to C is done using <code>cc1</code> or <code>gcc -c</code>
with the <code>-fmelt-mode=translatefile -fmelt-arg=<var>foo</var>.melt
-fmelt-secondarg=<var>foo</var>.c</code> options. The generated file
<var>foo</var>.c is usually quite big (and only <code>#include</code>-ing one
file, <code>"run-melt.h"</code> which includes all the rest). It
essentially contains one static C function (of signature compatible
with <code>melt_apply</code>) for each <code>defun</code> or <code>lambda</code>
function in MELT, and one big exported <code>start_module_melt</code> C
function which does all the initializations, and some other stuff. The
initialization code builds all the required data (quoted symbols,
closures, classes, fields, boxed strings, static instances defined
thru <code>definstance</code> etc..); MELT modules have no data outside of
this <code>start_module_melt</code> function.
</p>
<p>The start function <code>start_module_melt</code> (which is found by
dynamic loading of the module, usually thru <code>dlopen</code> and
<code>dlsym</code> or their equivalent, and called only once) expects a
parent environment and returns the newly filled module
environment<a name="DOCF5" href="#FOOT5">(5)</a>.
</p>
<p>To generate a MELT binary module from a MELT source file, use
<code>-fmelt-mode=translatetomodule</code>.
</p>
<hr size="6">
<a name="MELT-module-initialization-and-exports"></a>
<table cellpadding="1" cellspacing="1" border="0">
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<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-module-initialization-and-exports-1"></a>
<h4 class="subsubsection">1.7.3.3 MELT module initialization and exports</h4>
<a name="index-modules-in-MELT"></a>
<p>Names defined (as a function thru <code>defun</code>, as a class thru
<code>defclass</code>, as a field, etc…) are not visible outside their
module (to further MELT modules loaded afterwards) unless they are
<em>exported</em>. Most names (e.g. functions, selectors, instances) are
exported as values using the <code>export_values</code> construct. Classes
are usually exported using <code>export_class</code><a name="DOCF6" href="#FOOT6">(6)</a>, which also exports all the own
fields of the exported class (but inherited fields are not exported,
unless their class was <code>export_class</code>-ed).
</p>
<p>Advanced users can extend the MELT language by exporting macros using
the <code>export_macro</code> construct, which gets a macro name and its
macro expander function, which takes as arguments the source
expression (of <code>CLASS_SEXPR</code>), the environment (of
<code>CLASS_ENVIRONMENT</code>), the current expander, and produces an
instance of a subclass of <code>CLASS_SRC</code>.
</p>
<hr size="6">
<a name="MELT-translation-steps"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#MELT-module-initialization-and-exports" title="Previous section in reading order"> < </a>]</td>
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<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-modules-and-translation" title="Up section"> Up </a>]</td>
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<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-translation-steps-1"></a>
<h4 class="subsubsection">1.7.3.4 MELT translation steps</h4>
<p>The generated C code is of much lower level than the MELT source. The
MELT source code is usually in a file but can be elsewhere (a list or
s-exprs in memory).
</p>
<p>The generated C code interacts with MELT runtime and garbage
collector; in particular, every value -even temporary ones- should be
explicitly stored in MELT frames known by the GC. Hence, MELT
expressions are quickly normalized : <code>(f (g x) y)</code> becomes
something similar to <i><b>let</b> gg = g x <b>in</b> f gg y</i><a name="DOCF7" href="#FOOT7">(7)</a> where <i>gg</i> is a fresh variable
(actually an instance of <code>CLASS_CLONEDSYMBOL</code>).
</p>
<a name="index-reader-in-MELT"></a>
<a name="index-s_002dexpression-in-MELT"></a>
<p>The <em>reader</em>, or some other source, provides a list of
s-expressions to be translated. Each such s-expression is an instance
of <code>CLASS_SEXPR</code> so has <code>prop_table loca_location
sexp_contents</code> as fields. The <code>:loca_location</code> field is a mixloc
giving the staring position and file of the s-expr. The
<code>:sexp_contents</code> is a list value containing the s-expression
elements. Leafs are read specifically, e.g. boxed integers (of
<code>DISCR_INTEGER</code>) for integers, or symbols (instances of
<code>CLASS_SYMBOL</code>) or keywords (instances of <code>CLASS_KEYWORD</code>,
etc. All these classes are defined in ‘<tt>warmelt-first.melt</tt>’.
</p>
<a name="index-macro_002dexpansion-in-MELT"></a>
<p>Then s-expressions are <em>macro-expanded</em> into objects of
subclasses of <code>CLASS_SRC</code>. Standard macros (in particular all the
constructs defined above, see section <a href="#MELT-syntax-constructs">MELT syntax constructs</a>.) are defined
in ‘<tt>warmelt-macro.melt</tt>’. For instance, the <code>if</code> macro is
expanded by the <code>mexpand_if</code> expander function (private to
‘<tt>warmelt-macro.melt</tt>’) which makes an instance of
<code>CLASS_SRC_IFELSE</code> with fields <code>:src_loc sif_test :sif_then
:sif_else</code> and this <code>mexpand_if</code> expander is given to
<code>export_macro</code>. Macro expanders might need some of
<code>expand_apply lambda_arg_bindings macroexpand_1</code> …
functions defined in ‘<tt>warmelt-macro.melt</tt>’.
</p>
<a name="index-normalization-in-MELT"></a>
<a name="index-nrep-in-MELT"></a>
<p>After macro-expansion, the expanded source code (instances of some
subclass of <code>CLASS_SRC</code>) is <em>normalized</em> into instances of
subclasses of <code>CLASS_NREP</code> (for normal representations,
i.e. <em>nrep</em>s) by code in ‘<tt>warmelt-normal.melt</tt>’. Normal
expressions are not nested, so we separate simple nreps from complex
normal expressions (<code>CLASS_NREP_SIMPLE</code> vs
<code>CLASS_NREP_EXPR</code>). Normalization means not only adding extra
internal lets (i.e. instances of <code>CLASS_NREP_LET</code> but sometimes
computing additional information, such as the ctype of many
expressions. Normalization is in particular done with the
<code>normal_exp</code> selector (returning the nrep primarily and
secundarily a list of additional bindings), and other utilities such
as <code>normalize_tuple get_ctype wrap_normal_letseq</code> etc… For
instance the normalization of <code>if</code> constructs is done in the
<code>normal_exp</code> method for <code>CLASS_SRC_IF</code>, in a private
function called <code>normexp_if</code> which returns an instance of
<code>CLASS_NREP_IF</code> with fields <code>:nrep_loc nif_test :nif_then
:nif_else :nif_ctyp</code> and a list of additional normal bindings (of
<code>CLASS_NORMLET_BINDING</code>). Macro-expansion and normalization
sometimes give simpler representations; e.g. all of <code>if and or</code>
constructs get normalized as instances of <code>CLASS_NREP_IF</code>.
</p>
<a name="index-code-generation-in-MELT"></a>
<a name="index-objcode-in-MELT"></a>
<p>After normalization, nreps (which are expression-like) are transformed
in the “code generation”<a name="DOCF8" href="#FOOT8">(8)</a> step
into instruction-like representations called <em>objcode</em>s .
instances of subclasses of <code>CLASS_OBJCODE</code>. This happens in
‘<tt>warmelt-genobj.melt</tt>’ using the <code>compile_obj</code> selector,
which, applied to nreps and a generation context (a merge of various
info), produce objcodes. Moving from nreps expressions to instructions
involve very often putting a destination on an nrep thru the
<code>put_objdest</code> selector.
</p>
<a name="index-code-output-in-MELT"></a>
<p>At last, the objcode is output, within the ‘<tt>warmelt-outobj.melt</tt>’
file, in two string-buffers (one for the header part, one for the body
part) using several selectors like <code>output_c_code
output_c_declinit output_c_initfill output_c_initpredef</code>. Only once
all objcodes has been output in string buffers is it actually spilled
to the generated C file, all at once.
</p>
<p>Advanced users can extend the MELT language by implementing extensions
at various levels of the MELT translator.
</p>
<p>Several important data or functions are available thru the
<code>initial_system_data</code> instance (the only instance of
<code>CLASS_SYSTEM_DATA</code>), including the exporting and importing
machinery, the fresh module environment maker, the symbols and
keywords dictionnaries and internizers.
</p>
<p>All the MELT translation occur in ‘<tt>warmelt-*.melt</tt>’ files which
generate their ‘<tt>warmelt-*.c</tt>’ counterparts (these generated files
are distributed with GCC sources). Be careful to minimize the
interaction between these files and the rest of GCC (in particular,
avoid having a strong dependecies between GCC internal data
representations - like <code>gimple</code>) to be able to regenerate the
translating and translated files ‘<tt>warmelt-*.c</tt>’ from
‘<tt>warmelt-*.melt</tt>’ even when GCC internal passes
evolve<a name="DOCF9" href="#FOOT9">(9)</a>.
</p>
<hr size="6">
<a name="Writing-GCC-passes-in-MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
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</tr></table>
<a name="Writing-GCC-passes-in-MELT-1"></a>
<h3 class="subsection">1.7.4 Writing GCC passes in MELT</h3>
<p>[For experts, knowing about GCC passes in general]
</p>
<p>GCC passes can be written in MELT. See the ‘<tt>ana-*.melt</tt>’ files.
</p>
<hr size="6">
<a name="Writing-C-code-for-MELT"></a>
<table cellpadding="1" cellspacing="1" border="0">
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</tr></table>
<a name="Writing-C-code-for-MELT-1"></a>
<h2 class="section">1.8 Writing C code for MELT</h2>
<p>[For experts] Sometimes (i.e. to implement a new primitive) it may be
necessary to write some C code for MELT. We describe here the coding
conventions to follow, in particular because MELT has a copying
generational garbage collector (which changes pointers when copying
values out of the nursery).
</p>
<p>Above all, <em>avoid coding in C</em> (a cumbersome task) and
<em>prefer writing MELT code</em> when possible.
</p>
<p>Remember that MELT pointers can move at every allocation and every
MELT related call.
</p>
<p>First, a real example. To box a long integer into a MELT value, MELT
code have to use the <code>make_integerbox</code> defined in
‘<tt>warmelt-first.melt</tt>’ as
</p><table><tr><td> </td><td><pre class="lisp">(defprimitive make_integerbox (discr :long n) :value
#{(meltgc_new_int((meltobject_ptr_t)(" discr "), (" n ")))}#
</pre></td></tr></table>
<p>If the passed <code>discr</code> is not a discriminant for boxed integers,
<code>make_integerbox</code> gives nil.
</p>
<p>To get the boxed integer’s content, use the <code>getint</code> primitive in
MELT. To test if a value is a boxed integer, use the
<code>is_integerbox</code> primitive.
</p>
<p>The <code>meltgc_new_int</code> routine is implemented in
‘<tt>melt.c</tt>’ with the following code. We give it entirely, with
additional comments
</p>
<pre class="verbatim">melt_ptr_t
meltgc_new_int (meltobject_ptr_t discr_p, long num)
{
MELT_ENTERFRAME (2, NULL);
#define newintv curfram__.varptr[0]
#define discrv curfram__.varptr[1]
#define object_discrv ((meltobject_ptr_t)(discrv))
#define int_newintv ((struct meltint_st*)(newintv))
</pre><p>We first create a MELT frame using the <code>MELT_ENTERFRAME</code> macro
which creates, initialize the frame and install it at top. The first
argument is the number of local MELT values, the second argument is
the current MELT closure (so is <code>NULL</code> for C code which is not
the code of a routine). Instead of writing <code>curfram__.varptr[0]</code>
we <code>#define</code> some more descriptive names for readability. The
frame is initially filled with nil values. The value pointer arguments
(here <code>discr_p</code>) of the C function are conventionally named with
a <code>_p</code> suffix. Every local MELT value should be inside your
<code>curfram__.varptr</code> array.
</p>
<pre class="verbatim"> discrv = (void *) discr_p;
</pre><p>Every value passed as a C argument should be immediately copied into
the MELT frame (i.e. as a local value) and the C argument should not
be used directly afterwards. So never use <code>_p</code> suffixed arguments
after have copied them inside the frame.
</p>
<pre class="verbatim"> if (melt_magic_discr ((melt_ptr_t) (discrv)) != OBMAG_OBJECT)
goto end;
if (object_discrv->object_magic != OBMAG_INT)
goto end;
</pre><p>We try to be safe, so we at least test that the discriminant is an
object. We could have tested that it is indeed an instance of
<code>CLASS_DISCR</code> but that would be slower but safer. However we do
test that the discriminant’s magic is indeed
<code>OBMAG_INT</code><a name="DOCF10" href="#FOOT10">(10)</a>. If either test fail, we return nil by
<code>goto end</code>. We cannot code a direct <code>return</code> statement,
because that would not pop the topmost MELT frame.
</p>
<pre class="verbatim"> newintv = meltgc_allocate (sizeof (struct meltint_st), 0);
int_newintv->discr = object_discrv;
int_newintv->val = num;
</pre><p>We allocate space in the nursery with <code>meltgc_allocate</code>. This
C function sometimes trigger MELT garbage collection, so may move any
pointer inside any MELT frames. The first argument to
<code>meltgc_allocate</code> is the <code>sizeof</code> of the fixed part of
the value, and the second is the size of its trailing variable
part. The allocated zone should be immediately filled to make a valid
MELT value.
</p>
<pre class="verbatim">end:
MELT_EXITFRAME ();
return (melt_ptr_t) newintv;
#undef newintv
#undef discrv
#undef int_newintv
#undef object_discrv
}
</pre><p>We end by popping the current MELT frame and retuning. Popping the
frame should always be done, so conventionally we use an <code>end:</code>
label. To be good citizens for further C functions, we
<code>#undef</code>-ing every C macro defined for readability.
</p>
<p>More generally, every C function which may (directly or in any deeply
called function) trigger the MELT garbage collector should follow
these rules:
</p>
<ol>
<li> avoid coding in C.
The whole purpose of MELT is to make coding more fun.
</li><li> make an explicit MELT frame and enter it.
The C routine should start by making a frame usually with
<code>MELT_ENTERFRAME</code> macro (which expands to a C declaration
followed by some C statements, so should be the last “declaration”
like stuff in your function). For readability, you want to define C
macros (conventionally ending with <code>v</code>) to access the local
values in your frame instead of <code>curfram__.varptr[<var>index</var>]</code>.
</li><li> put every value in the MELT frame.
This means that every value should be kept in a local inside the MELT
frame, accessed thru <code>curfram__</code>. In particular, <em>nesting
function calls is prohibited</em>; never code <code>f(g(x))</code> if <code>g</code>
may trigger a MELT garbage collection; use a local value for
<code>g(x)</code> instead, and avoid declaring any MELT value as a C local.
</li><li> try to code safely.
Unless you have specific reasons to avoid that, try to test MELT
values before using them.
</li><li> notify on MELT updates.
When a MELT value is updated by changing some MELT pointer inside it,
you have to notify the garbage collector (write barrier) using the
<code>meltgc_touch</code> function (taking as argument the modified MELT
value) or the <code>meltgc_touch_dest</code> (also given the new MELT
pointer inside). These functions has to be called just after writing
the MELT pointer into the data. They can call the MELT garbage
collector (which may change any local value in the MELT frame).
</li><li> allocate MELT data appropriately.
Use <code>meltgc_allocate</code>, or preferably some existing allocating
function (like <code>meltgc_new_*</code>) to allocate new MELT
values. Never forget that such an allocation may trigger the MELT GC
and change every local pointer in the current MELT frame
<code>curfram__</code>. Most C functions which may directly or indirectly
trigger a MELT garbage collection are prefixed with <code>meltgc</code>
(but <code>melt_apply</code> could also trigger that).
</li><li> don’t use longjmp,
because <code>longjmp</code> won’t pop the MELT frames.
</li><li> always exit the MELT frame
explicitly using <code>MELT_EXITFRAME()</code> macro, which usually is
the last statement of your function (so avoid <code>return</code>-ing
before, hence always use a <code>goto end</code> instead.
</li><li> avoid using global MELT values.
If you really need some, use the <code>MELTGOB</code> or <code>MELTG</code>
macros. Adding additional MELT globals is tricky (edit files
‘<tt>melt.h</tt>’ and ‘<tt>warmelt-normal.melt</tt>’). Using existing MELT
globals is simpler, e.g. <code>MELTGOB(DISCR_LIST)</code> to fetch the
predefined discriminant <code>DISCR_LIST</code>.
</li><li> apply MELT functions and send MELT messages
using <code>melt_apply</code> and <code>meltgc_send</code> with their
pecular calling conventions (constant string describing array of
unions).
</li></ol>
<hr size="6">
<a name="Funding"></a>
<table cellpadding="1" cellspacing="1" border="0">
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<td valign="middle" align="left"> </td>
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</tr></table>
<a name="Funding-Free-Software"></a>
<h1 class="unnumbered">Funding Free Software</h1>
<p>If you want to have more free software a few years from now, it makes
sense for you to help encourage people to contribute funds for its
development. The most effective approach known is to encourage
commercial redistributors to donate.
</p>
<p>Users of free software systems can boost the pace of development by
encouraging for-a-fee distributors to donate part of their selling price
to free software developers—the Free Software Foundation, and others.
</p>
<p>The way to convince distributors to do this is to demand it and expect
it from them. So when you compare distributors, judge them partly by
how much they give to free software development. Show distributors
they must compete to be the one who gives the most.
</p>
<p>To make this approach work, you must insist on numbers that you can
compare, such as, “We will donate ten dollars to the Frobnitz project
for each disk sold.” Don’t be satisfied with a vague promise, such as
“A portion of the profits are donated,” since it doesn’t give a basis
for comparison.
</p>
<p>Even a precise fraction “of the profits from this disk” is not very
meaningful, since creative accounting and unrelated business decisions
can greatly alter what fraction of the sales price counts as profit.
If the price you pay is $50, ten percent of the profit is probably
less than a dollar; it might be a few cents, or nothing at all.
</p>
<p>Some redistributors do development work themselves. This is useful too;
but to keep everyone honest, you need to inquire how much they do, and
what kind. Some kinds of development make much more long-term
difference than others. For example, maintaining a separate version of
a program contributes very little; maintaining the standard version of a
program for the whole community contributes much. Easy new ports
contribute little, since someone else would surely do them; difficult
ports such as adding a new CPU to the GNU Compiler Collection contribute more;
major new features or packages contribute the most.
</p>
<p>By establishing the idea that supporting further development is “the
proper thing to do” when distributing free software for a fee, we can
assure a steady flow of resources into making more free software.
</p>
<table><tr><td> </td><td><pre class="display">Copyright © 1994 Free Software Foundation, Inc.
Verbatim copying and redistribution of this section is permitted
without royalty; alteration is not permitted.
</pre></td></tr></table>
<hr size="6">
<a name="GNU-Project"></a>
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<a name="The-GNU-Project-and-GNU_002fLinux"></a>
<h1 class="unnumbered">The GNU Project and GNU/Linux</h1>
<p>The GNU Project was launched in 1984 to develop a complete Unix-like
operating system which is free software: the GNU system. (GNU is a
recursive acronym for “GNU’s Not Unix”; it is pronounced
“guh-NEW”.) Variants of the GNU operating system, which use the
kernel Linux, are now widely used; though these systems are often
referred to as “Linux”, they are more accurately called GNU/Linux
systems.
</p>
<p>For more information, see:
</p><table><tr><td> </td><td><pre class="smallexample"><a href="http://www.gnu.org/">http://www.gnu.org/</a>
<a href="http://www.gnu.org/gnu/linux-and-gnu.html">http://www.gnu.org/gnu/linux-and-gnu.html</a>
</pre></td></tr></table>
<hr size="6">
<a name="Copying"></a>
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<td valign="middle" align="left"> </td>
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</tr></table>
<a name="GNU-General-Public-License"></a>
<h1 class="unnumbered">GNU General Public License</h1>
<p align="center"> Version 3, 29 June 2007
</p>
<table><tr><td> </td><td><pre class="display">Copyright © 2007 Free Software Foundation, Inc. <a href="http://fsf.org/">http://fsf.org/</a>
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
</pre></td></tr></table>
<a name="Preamble"></a>
<h2 class="heading">Preamble</h2>
<p>The GNU General Public License is a free, copyleft license for
software and other kinds of works.
</p>
<p>The licenses for most software and other practical works are designed
to take away your freedom to share and change the works. By contrast,
the GNU General Public License is intended to guarantee your freedom
to share and change all versions of a program–to make sure it remains
free software for all its users. We, the Free Software Foundation,
use the GNU General Public License for most of our software; it
applies also to any other work released this way by its authors. You
can apply it to your programs, too.
</p>
<p>When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
them if you wish), that you receive source code or can get it if you
want it, that you can change the software or use pieces of it in new
free programs, and that you know you can do these things.
</p>
<p>To protect your rights, we need to prevent others from denying you
these rights or asking you to surrender the rights. Therefore, you
have certain responsibilities if you distribute copies of the
software, or if you modify it: responsibilities to respect the freedom
of others.
</p>
<p>For example, if you distribute copies of such a program, whether
gratis or for a fee, you must pass on to the recipients the same
freedoms that you received. You must make sure that they, too,
receive or can get the source code. And you must show them these
terms so they know their rights.
</p>
<p>Developers that use the GNU GPL protect your rights with two steps:
(1) assert copyright on the software, and (2) offer you this License
giving you legal permission to copy, distribute and/or modify it.
</p>
<p>For the developers’ and authors’ protection, the GPL clearly explains
that there is no warranty for this free software. For both users’ and
authors’ sake, the GPL requires that modified versions be marked as
changed, so that their problems will not be attributed erroneously to
authors of previous versions.
</p>
<p>Some devices are designed to deny users access to install or run
modified versions of the software inside them, although the
manufacturer can do so. This is fundamentally incompatible with the
aim of protecting users’ freedom to change the software. The
systematic pattern of such abuse occurs in the area of products for
individuals to use, which is precisely where it is most unacceptable.
Therefore, we have designed this version of the GPL to prohibit the
practice for those products. If such problems arise substantially in
other domains, we stand ready to extend this provision to those
domains in future versions of the GPL, as needed to protect the
freedom of users.
</p>
<p>Finally, every program is threatened constantly by software patents.
States should not allow patents to restrict development and use of
software on general-purpose computers, but in those that do, we wish
to avoid the special danger that patents applied to a free program
could make it effectively proprietary. To prevent this, the GPL
assures that patents cannot be used to render the program non-free.
</p>
<p>The precise terms and conditions for copying, distribution and
modification follow.
</p>
<a name="TERMS-AND-CONDITIONS"></a>
<h2 class="heading">TERMS AND CONDITIONS</h2>
<ol>
<li> Definitions.
<p>“This License” refers to version 3 of the GNU General Public License.
</p>
<p>“Copyright” also means copyright-like laws that apply to other kinds
of works, such as semiconductor masks.
</p>
<p>“The Program” refers to any copyrightable work licensed under this
License. Each licensee is addressed as “you”. “Licensees” and
“recipients” may be individuals or organizations.
</p>
<p>To “modify” a work means to copy from or adapt all or part of the work
in a fashion requiring copyright permission, other than the making of
an exact copy. The resulting work is called a “modified version” of
the earlier work or a work “based on” the earlier work.
</p>
<p>A “covered work” means either the unmodified Program or a work based
on the Program.
</p>
<p>To “propagate” a work means to do anything with it that, without
permission, would make you directly or secondarily liable for
infringement under applicable copyright law, except executing it on a
computer or modifying a private copy. Propagation includes copying,
distribution (with or without modification), making available to the
public, and in some countries other activities as well.
</p>
<p>To “convey” a work means any kind of propagation that enables other
parties to make or receive copies. Mere interaction with a user
through a computer network, with no transfer of a copy, is not
conveying.
</p>
<p>An interactive user interface displays “Appropriate Legal Notices” to
the extent that it includes a convenient and prominently visible
feature that (1) displays an appropriate copyright notice, and (2)
tells the user that there is no warranty for the work (except to the
extent that warranties are provided), that licensees may convey the
work under this License, and how to view a copy of this License. If
the interface presents a list of user commands or options, such as a
menu, a prominent item in the list meets this criterion.
</p>
</li><li> Source Code.
<p>The “source code” for a work means the preferred form of the work for
making modifications to it. “Object code” means any non-source form
of a work.
</p>
<p>A “Standard Interface” means an interface that either is an official
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interfaces specified for a particular programming language, one that
is widely used among developers working in that language.
</p>
<p>The “System Libraries” of an executable work include anything, other
than the work as a whole, that (a) is included in the normal form of
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Component, and (b) serves only to enable use of the work with that
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implementation is available to the public in source code form. A
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(kernel, window system, and so on) of the specific operating system
(if any) on which the executable work runs, or a compiler used to
produce the work, or an object code interpreter used to run it.
</p>
<p>The “Corresponding Source” for a work in object code form means all
the source code needed to generate, install, and (for an executable
work) run the object code and to modify the work, including scripts to
control those activities. However, it does not include the work’s
System Libraries, or general-purpose tools or generally available free
programs which are used unmodified in performing those activities but
which are not part of the work. For example, Corresponding Source
includes interface definition files associated with source files for
the work, and the source code for shared libraries and dynamically
linked subprograms that the work is specifically designed to require,
such as by intimate data communication or control flow between those
subprograms and other parts of the work.
</p>
<p>The Corresponding Source need not include anything that users can
regenerate automatically from other parts of the Corresponding Source.
</p>
<p>The Corresponding Source for a work in source code form is that same
work.
</p>
</li><li> Basic Permissions.
<p>All rights granted under this License are granted for the term of
copyright on the Program, and are irrevocable provided the stated
conditions are met. This License explicitly affirms your unlimited
permission to run the unmodified Program. The output from running a
covered work is covered by this License only if the output, given its
content, constitutes a covered work. This License acknowledges your
rights of fair use or other equivalent, as provided by copyright law.
</p>
<p>You may make, run and propagate covered works that you do not convey,
without conditions so long as your license otherwise remains in force.
You may convey covered works to others for the sole purpose of having
them make modifications exclusively for you, or provide you with
facilities for running those works, provided that you comply with the
terms of this License in conveying all material for which you do not
control copyright. Those thus making or running the covered works for
you must do so exclusively on your behalf, under your direction and
control, on terms that prohibit them from making any copies of your
copyrighted material outside their relationship with you.
</p>
<p>Conveying under any other circumstances is permitted solely under the
conditions stated below. Sublicensing is not allowed; section 10
makes it unnecessary.
</p>
</li><li> Protecting Users’ Legal Rights From Anti-Circumvention Law.
<p>No covered work shall be deemed part of an effective technological
measure under any applicable law fulfilling obligations under article
11 of the WIPO copyright treaty adopted on 20 December 1996, or
similar laws prohibiting or restricting circumvention of such
measures.
</p>
<p>When you convey a covered work, you waive any legal power to forbid
circumvention of technological measures to the extent such
circumvention is effected by exercising rights under this License with
respect to the covered work, and you disclaim any intention to limit
operation or modification of the work as a means of enforcing, against
the work’s users, your or third parties’ legal rights to forbid
circumvention of technological measures.
</p>
</li><li> Conveying Verbatim Copies.
<p>You may convey verbatim copies of the Program’s source code as you
receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy an appropriate copyright notice;
keep intact all notices stating that this License and any
non-permissive terms added in accord with section 7 apply to the code;
keep intact all notices of the absence of any warranty; and give all
recipients a copy of this License along with the Program.
</p>
<p>You may charge any price or no price for each copy that you convey,
and you may offer support or warranty protection for a fee.
</p>
</li><li> Conveying Modified Source Versions.
<p>You may convey a work based on the Program, or the modifications to
produce it from the Program, in the form of source code under the
terms of section 4, provided that you also meet all of these
conditions:
</p>
<ol>
<li>
The work must carry prominent notices stating that you modified it,
and giving a relevant date.
</li><li>
The work must carry prominent notices stating that it is released
under this License and any conditions added under section 7. This
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notices”.
</li><li>
You must license the entire work, as a whole, under this License to
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therefore apply, along with any applicable section 7 additional terms,
to the whole of the work, and all its parts, regardless of how they
are packaged. This License gives no permission to license the work in
any other way, but it does not invalidate such permission if you have
separately received it.
</li><li>
If the work has interactive user interfaces, each must display
Appropriate Legal Notices; however, if the Program has interactive
interfaces that do not display Appropriate Legal Notices, your work
need not make them do so.
</li></ol>
<p>A compilation of a covered work with other separate and independent
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in or on a volume of a storage or distribution medium, is called an
“aggregate” if the compilation and its resulting copyright are not
used to limit the access or legal rights of the compilation’s users
beyond what the individual works permit. Inclusion of a covered work
in an aggregate does not cause this License to apply to the other
parts of the aggregate.
</p>
</li><li> Conveying Non-Source Forms.
<p>You may convey a covered work in object code form under the terms of
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Corresponding Source under the terms of this License, in one of these
ways:
</p>
<ol>
<li>
Convey the object code in, or embodied in, a physical product
(including a physical distribution medium), accompanied by the
Corresponding Source fixed on a durable physical medium customarily
used for software interchange.
</li><li>
Convey the object code in, or embodied in, a physical product
(including a physical distribution medium), accompanied by a written
offer, valid for at least three years and valid for as long as you
offer spare parts or customer support for that product model, to give
anyone who possesses the object code either (1) a copy of the
Corresponding Source for all the software in the product that is
covered by this License, on a durable physical medium customarily used
for software interchange, for a price no more than your reasonable
cost of physically performing this conveying of source, or (2) access
to copy the Corresponding Source from a network server at no charge.
</li><li>
Convey individual copies of the object code with a copy of the written
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allowed only occasionally and noncommercially, and only if you
received the object code with such an offer, in accord with subsection
6b.
</li><li>
Convey the object code by offering access from a designated place
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next to the object code saying where to find the Corresponding Source.
Regardless of what server hosts the Corresponding Source, you remain
obligated to ensure that it is available for as long as needed to
satisfy these requirements.
</li><li>
Convey the object code using peer-to-peer transmission, provided you
inform other peers where the object code and Corresponding Source of
the work are being offered to the general public at no charge under
subsection 6d.
</li></ol>
<p>A separable portion of the object code, whose source code is excluded
from the Corresponding Source as a System Library, need not be
included in conveying the object code work.
</p>
<p>A “User Product” is either (1) a “consumer product”, which means any
tangible personal property which is normally used for personal,
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“normally used” refers to a typical or common use of that class of
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to use, the product. A product is a consumer product regardless of
whether the product has substantial commercial, industrial or
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mode of use of the product.
</p>
<p>“Installation Information” for a User Product means any methods,
procedures, authorization keys, or other information required to
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Product from a modified version of its Corresponding Source. The
information must suffice to ensure that the continued functioning of
the modified object code is in no case prevented or interfered with
solely because modification has been made.
</p>
<p>If you convey an object code work under this section in, or with, or
specifically for use in, a User Product, and the conveying occurs as
part of a transaction in which the right of possession and use of the
User Product is transferred to the recipient in perpetuity or for a
fixed term (regardless of how the transaction is characterized), the
Corresponding Source conveyed under this section must be accompanied
by the Installation Information. But this requirement does not apply
if neither you nor any third party retains the ability to install
modified object code on the User Product (for example, the work has
been installed in ROM).
</p>
<p>The requirement to provide Installation Information does not include a
requirement to continue to provide support service, warranty, or
updates for a work that has been modified or installed by the
recipient, or for the User Product in which it has been modified or
installed. Access to a network may be denied when the modification
itself materially and adversely affects the operation of the network
or violates the rules and protocols for communication across the
network.
</p>
<p>Corresponding Source conveyed, and Installation Information provided,
in accord with this section must be in a format that is publicly
documented (and with an implementation available to the public in
source code form), and must require no special password or key for
unpacking, reading or copying.
</p>
</li><li> Additional Terms.
<p>“Additional permissions” are terms that supplement the terms of this
License by making exceptions from one or more of its conditions.
Additional permissions that are applicable to the entire Program shall
be treated as though they were included in this License, to the extent
that they are valid under applicable law. If additional permissions
apply only to part of the Program, that part may be used separately
under those permissions, but the entire Program remains governed by
this License without regard to the additional permissions.
</p>
<p>When you convey a copy of a covered work, you may at your option
remove any additional permissions from that copy, or from any part of
it. (Additional permissions may be written to require their own
removal in certain cases when you modify the work.) You may place
additional permissions on material, added by you to a covered work,
for which you have or can give appropriate copyright permission.
</p>
<p>Notwithstanding any other provision of this License, for material you
add to a covered work, you may (if authorized by the copyright holders
of that material) supplement the terms of this License with terms:
</p>
<ol>
<li>
Disclaiming warranty or limiting liability differently from the terms
of sections 15 and 16 of this License; or
</li><li>
Requiring preservation of specified reasonable legal notices or author
attributions in that material or in the Appropriate Legal Notices
displayed by works containing it; or
</li><li>
Prohibiting misrepresentation of the origin of that material, or
requiring that modified versions of such material be marked in
reasonable ways as different from the original version; or
</li><li>
Limiting the use for publicity purposes of names of licensors or
authors of the material; or
</li><li>
Declining to grant rights under trademark law for use of some trade
names, trademarks, or service marks; or
</li><li>
Requiring indemnification of licensors and authors of that material by
anyone who conveys the material (or modified versions of it) with
contractual assumptions of liability to the recipient, for any
liability that these contractual assumptions directly impose on those
licensors and authors.
</li></ol>
<p>All other non-permissive additional terms are considered “further
restrictions” within the meaning of section 10. If the Program as you
received it, or any part of it, contains a notice stating that it is
governed by this License along with a term that is a further
restriction, you may remove that term. If a license document contains
a further restriction but permits relicensing or conveying under this
License, you may add to a covered work material governed by the terms
of that license document, provided that the further restriction does
not survive such relicensing or conveying.
</p>
<p>If you add terms to a covered work in accord with this section, you
must place, in the relevant source files, a statement of the
additional terms that apply to those files, or a notice indicating
where to find the applicable terms.
</p>
<p>Additional terms, permissive or non-permissive, may be stated in the
form of a separately written license, or stated as exceptions; the
above requirements apply either way.
</p>
</li><li> Termination.
<p>You may not propagate or modify a covered work except as expressly
provided under this License. Any attempt otherwise to propagate or
modify it is void, and will automatically terminate your rights under
this License (including any patent licenses granted under the third
paragraph of section 11).
</p>
<p>However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
</p>
<p>Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
</p>
<p>Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License. If your rights have been terminated and not permanently
reinstated, you do not qualify to receive new licenses for the same
material under section 10.
</p>
</li><li> Acceptance Not Required for Having Copies.
<p>You are not required to accept this License in order to receive or run
a copy of the Program. Ancillary propagation of a covered work
occurring solely as a consequence of using peer-to-peer transmission
to receive a copy likewise does not require acceptance. However,
nothing other than this License grants you permission to propagate or
modify any covered work. These actions infringe copyright if you do
not accept this License. Therefore, by modifying or propagating a
covered work, you indicate your acceptance of this License to do so.
</p>
</li><li> Automatic Licensing of Downstream Recipients.
<p>Each time you convey a covered work, the recipient automatically
receives a license from the original licensors, to run, modify and
propagate that work, subject to this License. You are not responsible
for enforcing compliance by third parties with this License.
</p>
<p>An “entity transaction” is a transaction transferring control of an
organization, or substantially all assets of one, or subdividing an
organization, or merging organizations. If propagation of a covered
work results from an entity transaction, each party to that
transaction who receives a copy of the work also receives whatever
licenses to the work the party’s predecessor in interest had or could
give under the previous paragraph, plus a right to possession of the
Corresponding Source of the work from the predecessor in interest, if
the predecessor has it or can get it with reasonable efforts.
</p>
<p>You may not impose any further restrictions on the exercise of the
rights granted or affirmed under this License. For example, you may
not impose a license fee, royalty, or other charge for exercise of
rights granted under this License, and you may not initiate litigation
(including a cross-claim or counterclaim in a lawsuit) alleging that
any patent claim is infringed by making, using, selling, offering for
sale, or importing the Program or any portion of it.
</p>
</li><li> Patents.
<p>A “contributor” is a copyright holder who authorizes use under this
License of the Program or a work on which the Program is based. The
work thus licensed is called the contributor’s “contributor version”.
</p>
<p>A contributor’s “essential patent claims” are all patent claims owned
or controlled by the contributor, whether already acquired or
hereafter acquired, that would be infringed by some manner, permitted
by this License, of making, using, or selling its contributor version,
but do not include claims that would be infringed only as a
consequence of further modification of the contributor version. For
purposes of this definition, “control” includes the right to grant
patent sublicenses in a manner consistent with the requirements of
this License.
</p>
<p>Each contributor grants you a non-exclusive, worldwide, royalty-free
patent license under the contributor’s essential patent claims, to
make, use, sell, offer for sale, import and otherwise run, modify and
propagate the contents of its contributor version.
</p>
<p>In the following three paragraphs, a “patent license” is any express
agreement or commitment, however denominated, not to enforce a patent
(such as an express permission to practice a patent or covenant not to
sue for patent infringement). To “grant” such a patent license to a
party means to make such an agreement or commitment not to enforce a
patent against the party.
</p>
<p>If you convey a covered work, knowingly relying on a patent license,
and the Corresponding Source of the work is not available for anyone
to copy, free of charge and under the terms of this License, through a
publicly available network server or other readily accessible means,
then you must either (1) cause the Corresponding Source to be so
available, or (2) arrange to deprive yourself of the benefit of the
patent license for this particular work, or (3) arrange, in a manner
consistent with the requirements of this License, to extend the patent
license to downstream recipients. “Knowingly relying” means you have
actual knowledge that, but for the patent license, your conveying the
covered work in a country, or your recipient’s use of the covered work
in a country, would infringe one or more identifiable patents in that
country that you have reason to believe are valid.
</p>
<p>If, pursuant to or in connection with a single transaction or
arrangement, you convey, or propagate by procuring conveyance of, a
covered work, and grant a patent license to some of the parties
receiving the covered work authorizing them to use, propagate, modify
or convey a specific copy of the covered work, then the patent license
you grant is automatically extended to all recipients of the covered
work and works based on it.
</p>
<p>A patent license is “discriminatory” if it does not include within the
scope of its coverage, prohibits the exercise of, or is conditioned on
the non-exercise of one or more of the rights that are specifically
granted under this License. You may not convey a covered work if you
are a party to an arrangement with a third party that is in the
business of distributing software, under which you make payment to the
third party based on the extent of your activity of conveying the
work, and under which the third party grants, to any of the parties
who would receive the covered work from you, a discriminatory patent
license (a) in connection with copies of the covered work conveyed by
you (or copies made from those copies), or (b) primarily for and in
connection with specific products or compilations that contain the
covered work, unless you entered into that arrangement, or that patent
license was granted, prior to 28 March 2007.
</p>
<p>Nothing in this License shall be construed as excluding or limiting
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.
</p>
</li><li> No Surrender of Others’ Freedom.
<p>If conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License. If you cannot convey
a covered work so as to satisfy simultaneously your obligations under
this License and any other pertinent obligations, then as a
consequence you may not convey it at all. For example, if you agree
to terms that obligate you to collect a royalty for further conveying
from those to whom you convey the Program, the only way you could
satisfy both those terms and this License would be to refrain entirely
from conveying the Program.
</p>
</li><li> Use with the GNU Affero General Public License.
<p>Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
under version 3 of the GNU Affero General Public License into a single
combined work, and to convey the resulting work. The terms of this
License will continue to apply to the part which is the covered work,
but the special requirements of the GNU Affero General Public License,
section 13, concerning interaction through a network will apply to the
combination as such.
</p>
</li><li> Revised Versions of this License.
<p>The Free Software Foundation may publish revised and/or new versions
of the GNU General Public License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.
</p>
<p>Each version is given a distinguishing version number. If the Program
specifies that a certain numbered version of the GNU General Public
License “or any later version” applies to it, you have the option of
following the terms and conditions either of that numbered version or
of any later version published by the Free Software Foundation. If
the Program does not specify a version number of the GNU General
Public License, you may choose any version ever published by the Free
Software Foundation.
</p>
<p>If the Program specifies that a proxy can decide which future versions
of the GNU General Public License can be used, that proxy’s public
statement of acceptance of a version permanently authorizes you to
choose that version for the Program.
</p>
<p>Later license versions may give you additional or different
permissions. However, no additional obligations are imposed on any
author or copyright holder as a result of your choosing to follow a
later version.
</p>
</li><li> Disclaimer of Warranty.
<p>THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT
WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND
PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE
DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR
CORRECTION.
</p>
</li><li> Limitation of Liability.
<p>IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR
CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT
NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR
LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM
TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER
PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
</p>
</li><li> Interpretation of Sections 15 and 16.
<p>If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
an absolute waiver of all civil liability in connection with the
Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.
</p>
</li></ol>
<a name="END-OF-TERMS-AND-CONDITIONS"></a>
<h2 class="heading">END OF TERMS AND CONDITIONS</h2>
<a name="How-to-Apply-These-Terms-to-Your-New-Programs"></a>
<h2 class="heading">How to Apply These Terms to Your New Programs</h2>
<p>If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.
</p>
<p>To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the “copyright” line and a pointer to where the full notice is found.
</p>
<table><tr><td> </td><td><pre class="smallexample"><var>one line to give the program's name and a brief idea of what it does.</var>
Copyright (C) <var>year</var> <var>name of author</var>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
This program 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <a href="http://www.gnu.org/licenses/">http://www.gnu.org/licenses/</a>.
</pre></td></tr></table>
<p>Also add information on how to contact you by electronic and paper mail.
</p>
<p>If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:
</p>
<table><tr><td> </td><td><pre class="smallexample"><var>program</var> Copyright (C) <var>year</var> <var>name of author</var>
This program comes with ABSOLUTELY NO WARRANTY; for details type ‘<samp>show w</samp>’.
This is free software, and you are welcome to redistribute it
under certain conditions; type ‘<samp>show c</samp>’ for details.
</pre></td></tr></table>
<p>The hypothetical commands ‘<samp>show w</samp>’ and ‘<samp>show c</samp>’ should show
the appropriate parts of the General Public License. Of course, your
program’s commands might be different; for a GUI interface, you would
use an “about box”.
</p>
<p>You should also get your employer (if you work as a programmer) or school,
if any, to sign a “copyright disclaimer” for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<a href="http://www.gnu.org/licenses/">http://www.gnu.org/licenses/</a>.
</p>
<p>The GNU General Public License does not permit incorporating your
program into proprietary programs. If your program is a subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use
the GNU Lesser General Public License instead of this License. But
first, please read <a href="http://www.gnu.org/philosophy/why-not-lgpl.html">http://www.gnu.org/philosophy/why-not-lgpl.html</a>.
</p>
<hr size="6">
<a name="GNU-Free-Documentation-License"></a>
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<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="GNU-Free-Documentation-License-1"></a>
<h1 class="unnumbered">GNU Free Documentation License</h1>
<a name="index-FDL_002c-GNU-Free-Documentation-License"></a>
<p align="center"> Version 1.3, 3 November 2008
</p>
<table><tr><td> </td><td><pre class="display">Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<a href="http://fsf.org/">http://fsf.org/</a>
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></td></tr></table>
<ol>
<li>
PREAMBLE
<p>The purpose of this License is to make a manual, textbook, or other
functional and useful document <em>free</em> in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.
</p>
<p>This License is a kind of “copyleft”, which means that derivative
works of the document must themselves be free in the same sense. It
complements the GNU General Public License, which is a copyleft
license designed for free software.
</p>
<p>We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does. But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book. We recommend this License
principally for works whose purpose is instruction or reference.
</p>
</li><li>
APPLICABILITY AND DEFINITIONS
<p>This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License. Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein. The “Document”, below,
refers to any such manual or work. Any member of the public is a
licensee, and is addressed as “you”. You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.
</p>
<p>A “Modified Version” of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
</p>
<p>A “Secondary Section” is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document’s overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject. (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.) The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.
</p>
<p>The “Invariant Sections” are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License. If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant. The Document may contain zero
Invariant Sections. If the Document does not identify any Invariant
Sections then there are none.
</p>
<p>The “Cover Texts” are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License. A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.
</p>
<p>A “Transparent” copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters. A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text. A copy that is not “Transparent” is called “Opaque”.
</p>
<p>Examples of suitable formats for Transparent copies include plain
<small>ASCII</small> without markup, Texinfo input format, LaTeX input
format, <acronym>SGML</acronym> or <acronym>XML</acronym> using a publicly available
<acronym>DTD</acronym>, and standard-conforming simple <acronym>HTML</acronym>,
PostScript or <acronym>PDF</acronym> designed for human modification. Examples
of transparent image formats include <acronym>PNG</acronym>, <acronym>XCF</acronym> and
<acronym>JPG</acronym>. Opaque formats include proprietary formats that can be
read and edited only by proprietary word processors, <acronym>SGML</acronym> or
<acronym>XML</acronym> for which the <acronym>DTD</acronym> and/or processing tools are
not generally available, and the machine-generated <acronym>HTML</acronym>,
PostScript or <acronym>PDF</acronym> produced by some word processors for
output purposes only.
</p>
<p>The “Title Page” means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page. For works in
formats which do not have any title page as such, “Title Page” means
the text near the most prominent appearance of the work’s title,
preceding the beginning of the body of the text.
</p>
<p>The “publisher” means any person or entity that distributes copies
of the Document to the public.
</p>
<p>A section “Entitled XYZ” means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language. (Here XYZ stands for a
specific section name mentioned below, such as “Acknowledgements”,
“Dedications”, “Endorsements”, or “History”.) To “Preserve the Title”
of such a section when you modify the Document means that it remains a
section “Entitled XYZ” according to this definition.
</p>
<p>The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document. These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.
</p>
</li><li>
VERBATIM COPYING
<p>You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License. You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute. However, you may accept
compensation in exchange for copies. If you distribute a large enough
number of copies you must also follow the conditions in section 3.
</p>
<p>You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
</p>
</li><li>
COPYING IN QUANTITY
<p>If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document’s license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover. Both covers must also clearly and legibly identify
you as the publisher of these copies. The front cover must present
the full title with all words of the title equally prominent and
visible. You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
</p>
<p>If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.
</p>
<p>If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.
</p>
<p>It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.
</p>
</li><li>
MODIFICATIONS
<p>You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it. In addition, you must do these things in the Modified Version:
</p>
<ol>
<li>
Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document). You may use the same title as a previous version
if the original publisher of that version gives permission.
</li><li>
List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five),
unless they release you from this requirement.
</li><li>
State on the Title page the name of the publisher of the
Modified Version, as the publisher.
</li><li>
Preserve all the copyright notices of the Document.
</li><li>
Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.
</li><li>
Include, immediately after the copyright notices, a license notice
giving the public permission to use the Modified Version under the
terms of this License, in the form shown in the Addendum below.
</li><li>
Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document’s license notice.
</li><li>
Include an unaltered copy of this License.
</li><li>
Preserve the section Entitled “History”, Preserve its Title, and add
to it an item stating at least the title, year, new authors, and
publisher of the Modified Version as given on the Title Page. If
there is no section Entitled “History” in the Document, create one
stating the title, year, authors, and publisher of the Document as
given on its Title Page, then add an item describing the Modified
Version as stated in the previous sentence.
</li><li>
Preserve the network location, if any, given in the Document for
public access to a Transparent copy of the Document, and likewise
the network locations given in the Document for previous versions
it was based on. These may be placed in the “History” section.
You may omit a network location for a work that was published at
least four years before the Document itself, or if the original
publisher of the version it refers to gives permission.
</li><li>
For any section Entitled “Acknowledgements” or “Dedications”, Preserve
the Title of the section, and preserve in the section all the
substance and tone of each of the contributor acknowledgements and/or
dedications given therein.
</li><li>
Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles. Section numbers
or the equivalent are not considered part of the section titles.
</li><li>
Delete any section Entitled “Endorsements”. Such a section
may not be included in the Modified Version.
</li><li>
Do not retitle any existing section to be Entitled “Endorsements” or
to conflict in title with any Invariant Section.
</li><li>
Preserve any Warranty Disclaimers.
</li></ol>
<p>If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant. To do this, add their titles to the
list of Invariant Sections in the Modified Version’s license notice.
These titles must be distinct from any other section titles.
</p>
<p>You may add a section Entitled “Endorsements”, provided it contains
nothing but endorsements of your Modified Version by various
parties—for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.
</p>
<p>You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version. Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity. If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.
</p>
<p>The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.
</p>
</li><li>
COMBINING DOCUMENTS
<p>You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
Invariant Sections of all of the original documents, unmodified, and
list them all as Invariant Sections of your combined work in its
license notice, and that you preserve all their Warranty Disclaimers.
</p>
<p>The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy. If there are multiple Invariant Sections with the same name but
different contents, make the title of each such section unique by
adding at the end of it, in parentheses, the name of the original
author or publisher of that section if known, or else a unique number.
Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.
</p>
<p>In the combination, you must combine any sections Entitled “History”
in the various original documents, forming one section Entitled
“History”; likewise combine any sections Entitled “Acknowledgements”,
and any sections Entitled “Dedications”. You must delete all
sections Entitled “Endorsements.”
</p>
</li><li>
COLLECTIONS OF DOCUMENTS
<p>You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this
License in the various documents with a single copy that is included in
the collection, provided that you follow the rules of this License for
verbatim copying of each of the documents in all other respects.
</p>
<p>You may extract a single document from such a collection, and distribute
it individually under this License, provided you insert a copy of this
License into the extracted document, and follow this License in all
other respects regarding verbatim copying of that document.
</p>
</li><li>
AGGREGATION WITH INDEPENDENT WORKS
<p>A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, is called an “aggregate” if the copyright
resulting from the compilation is not used to limit the legal rights
of the compilation’s users beyond what the individual works permit.
When the Document is included in an aggregate, this License does not
apply to the other works in the aggregate which are not themselves
derivative works of the Document.
</p>
<p>If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half of
the entire aggregate, the Document’s Cover Texts may be placed on
covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form.
Otherwise they must appear on printed covers that bracket the whole
aggregate.
</p>
</li><li>
TRANSLATION
<p>Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers. In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.
</p>
<p>If a section in the Document is Entitled “Acknowledgements”,
“Dedications”, or “History”, the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
</p>
</li><li>
TERMINATION
<p>You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.
</p>
<p>However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
</p>
<p>Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
</p>
<p>Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License. If your rights have been terminated and not permanently
reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.
</p>
</li><li>
FUTURE REVISIONS OF THIS LICENSE
<p>The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
<a href="http://www.gnu.org/copyleft/">http://www.gnu.org/copyleft/</a>.
</p>
<p>Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License “or any later version” applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation. If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation. If the Document
specifies that a proxy can decide which future versions of this
License can be used, that proxy’s public statement of acceptance of a
version permanently authorizes you to choose that version for the
Document.
</p>
</li><li>
RELICENSING
<p>“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server. A
“Massive Multiauthor Collaboration” (or “MMC”) contained in the
site means any set of copyrightable works thus published on the MMC
site.
</p>
<p>“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
</p>
<p>“Incorporate” means to publish or republish a Document, in whole or
in part, as part of another Document.
</p>
<p>An MMC is “eligible for relicensing” if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole
or in part into the MMC, (1) had no cover texts or invariant sections,
and (2) were thus incorporated prior to November 1, 2008.
</p>
<p>The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.
</p>
</li></ol>
<hr size="6">
<a name="ADDENDUM_003a-How-to-use-this-License-for-your-documents"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#GNU-Free-Documentation-License" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#GNU-Free-Documentation-License" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#GNU-Free-Documentation-License" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<h2 class="unnumberedsec">ADDENDUM: How to use this License for your documents</h2>
<p>To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
</p>
<table><tr><td> </td><td><pre class="smallexample"> Copyright (C) <var>year</var> <var>your name</var>.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
</pre></td></tr></table>
<p>If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the “with...Texts.” line with this:
</p>
<table><tr><td> </td><td><pre class="smallexample"> with the Invariant Sections being <var>list their titles</var>, with
the Front-Cover Texts being <var>list</var>, and with the Back-Cover Texts
being <var>list</var>.
</pre></td></tr></table>
<p>If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
</p>
<p>If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
</p>
<hr size="6">
<a name="MELT-Option-Index"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#ADDENDUM_003a-How-to-use-this-License-for-your-documents" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Concept-Index" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#GNU-Free-Documentation-License" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Top" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Concept-Index" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-Option-Index-1"></a>
<h1 class="unnumbered">MELT Option Index</h1>
<p>MELT plugin’s command line options are indexed here without any
initial ‘<samp>-</samp>’ or ‘<samp>--</samp>’. Where an option has both positive and
negative forms (such as ‘<samp>-f<var>option</var></samp>’ and
‘<samp>-fno-<var>option</var></samp>’), relevant entries in the manual are
indexed under the most appropriate form; it may sometimes be useful to
look up both forms. Each option has a plugin form
‘<samp>-fplugin-melt-arg-<var>option</var></samp>’ and a MELT branch form
‘<samp>-fmelt-<var>option</var></samp>’ which is used in the GCC experimental
MELT branch.
</p>
<table><tr><th valign="top">Jump to: </th><td><a href="#MELT-Option-Index-1_op_letter-F" class="summary-letter"><b>F</b></a>
</td></tr></table>
<table border="0" class="index-op">
<tr><td></td><th align="left">Index Entry</th><th align="left"> Section</th></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Option-Index-1_op_letter-F">F</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002darg_003d"><code>fmelt-arg=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002darglist_003d"><code>fmelt-arglist=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dcoutput_003d"><code>fmelt-coutput=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dcoutput_003d-1"><code>fmelt-coutput=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002ddebug"><code>fmelt-debug</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002ddebugskip_003d"><code>fmelt-debugskip=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dextra_003d"><code>fmelt-extra=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dinit_003d"><code>fmelt-init=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dmode"><code>fmelt-mode</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dmodule_002dcflags_003d"><code>fmelt-module-cflags=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dmodule_002dmake_002dcommand_003d"><code>fmelt-module-make-command=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dmodule_002dmakefile_003d"><code>fmelt-module-makefile=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dmodule_002dpath_003d"><code>fmelt-module-path=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002doption_003d"><code>fmelt-option=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dprint_002dsettings_003d"><code>fmelt-print-settings=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dsource_002dpath_003d"><code>fmelt-source-path=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dtempdir_003d"><code>fmelt-tempdir=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fmelt_002dworkdir_003d"><code>fmelt-workdir=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002darglist_003d"><code>fplugin-arg-melt-arglist=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dcflags_003d"><code>fplugin-arg-melt-cflags=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dcoutput_003d"><code>fplugin-arg-melt-coutput=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002ddebug"><code>fplugin-arg-melt-debug</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002ddebugskip_003d"><code>fplugin-arg-melt-debugskip=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dextra_003d"><code>fplugin-arg-melt-extra=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dinit_003d"><code>fplugin-arg-melt-init=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dmake_002dcommand_003d"><code>fplugin-arg-melt-make-command=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dmakefile_003d"><code>fplugin-arg-melt-makefile=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dmelt_002dtempdir_003d"><code>fplugin-arg-melt-melt-tempdir=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dmelt_002dworkdir_003d"><code>fplugin-arg-melt-melt-workdir=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dmode"><code>fplugin-arg-melt-mode</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dmodule_002dpath_003d"><code>fplugin-arg-melt-module-path=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002doutput_003d"><code>fplugin-arg-melt-output=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dprint_002dsettings_003d"><code>fplugin-arg-melt-print-settings=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fplugin_002darg_002dmelt_002dsource_002dpath_003d"><code>fplugin-arg-melt-source-path=</code></a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
</table>
<table><tr><th valign="top">Jump to: </th><td><a href="#MELT-Option-Index-1_op_letter-F" class="summary-letter"><b>F</b></a>
</td></tr></table>
<hr size="6">
<a name="MELT-Concept-Index"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[ > ]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Top" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[ >> ]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="MELT-Concept-Index-1"></a>
<h1 class="unnumbered">MELT Concept Index</h1>
<table><tr><th valign="top">Jump to: </th><td><a href="#MELT-Concept-Index-1_cp_letter-A" class="summary-letter"><b>A</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-B" class="summary-letter"><b>B</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-C" class="summary-letter"><b>C</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-D" class="summary-letter"><b>D</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-E" class="summary-letter"><b>E</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-F" class="summary-letter"><b>F</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-G" class="summary-letter"><b>G</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-I" class="summary-letter"><b>I</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-L" class="summary-letter"><b>L</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-M" class="summary-letter"><b>M</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-N" class="summary-letter"><b>N</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-O" class="summary-letter"><b>O</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-P" class="summary-letter"><b>P</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-Q" class="summary-letter"><b>Q</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-R" class="summary-letter"><b>R</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-S" class="summary-letter"><b>S</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-T" class="summary-letter"><b>T</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-U" class="summary-letter"><b>U</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-V" class="summary-letter"><b>V</b></a>
</td></tr></table>
<table border="0" class="index-cp">
<tr><td></td><th align="left">Index Entry</th><th align="left"> Section</th></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-A">A</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-and-MELT-syntax"><code>and</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-assert_005ffailed-MELT-primitive"><code>assert_failed</code> MELT primitive</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-assert_005fmsg-MELT-syntax"><code>assert_msg</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-B">B</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-box-MELT-value">box MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-boxed-ctype-map-MELT-value">boxed ctype map MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-boxed-ctype-MELT-value">boxed ctype MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-boxed-values-in-MELT">boxed values in MELT</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Building-the-MELT-branch">Building the MELT branch</a></td><td valign="top"><a href="#Building-the-MELT-branch">1.3 Building the MELT branch</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-C">C</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-Citerator-in-MELT">Citerator in MELT</a></td><td valign="top"><a href="#Citerators-in-MELT">1.6.3 Citerators in MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-class-in-MELT">class in MELT</a></td><td valign="top"><a href="#MELT-objects-and-classes">1.7.2.4 MELT objects and classes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-closure-MELT-value">closure MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-code-generation-in-MELT">code generation in MELT</a></td><td valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-code-output-in-MELT">code output in MELT</a></td><td valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-comment-MELT-syntax"><code>comment</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-compile_005fwarning-MELT-syntax"><code>compile_warning</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-cond-MELT-syntax"><code>cond</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-cppif-MELT-syntax"><code>cppif</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-ctype-in-MELT">ctype in MELT</a></td><td valign="top"><a href="#Primitives-in-MELT">1.6.2 Primitives in MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-ctype-in-MELT-1">ctype in MELT</a></td><td valign="top"><a href="#MELT-ctypes">1.7.2.2 MELT ctypes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-ctype-MELT-keyword">ctype MELT keyword</a></td><td valign="top"><a href="#MELT-formals">1.7.2.1 MELT formals</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-current_005fmodule_005fenvironment_005fcontainer-MELT-syntax"><code>current_module_environment_container</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-D">D</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-debug_005fmsg-MELT-syntax"><code>debug_msg</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-defciterator-MELT-syntax"><code>defciterator</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-defclass-MELT-syntax"><code>defclass</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-defcmatcher-MELT-syntax_002e"><code>defcmatcher</code> MELT syntax.</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-definstance-MELT-syntax"><code>definstance</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-defprimitive-MELT-syntax"><code>defprimitive</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-defselector-MELT-syntax"><code>defselector</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-defun-MELT-syntax"><code>defun</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-discriminant-for-MELT-values">discriminant for MELT values</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-E">E</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-exit-MELT-syntax"><code>exit</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-export_005fclass-MELT-syntax"><code>export_class</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-export_005fmacro-MELT-syntax"><code>export_macro</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-export_005fpatmacro-MELT-syntax"><code>export_patmacro</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-export_005fvalues-MELT-syntax"><code>export_values</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-F">F</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-FDL_002c-GNU-Free-Documentation-License">FDL, GNU Free Documentation License</a></td><td valign="top"><a href="#GNU-Free-Documentation-License">GNU Free Documentation License</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-fetch_005fpredefined-MELT-syntax"><code>fetch_predefined</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-forever-MELT-syntax"><code>forever</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-full-MELT-garbage-collection">full MELT garbage collection</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Function-in-MELT">Function in MELT</a></td><td valign="top"><a href="#Functions-in-MELT">1.6.4 Functions in MELT</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-G">G</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-get_005ffield-MELT-syntax"><code>get_field</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-I">I</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-if-MELT-syntax"><code>if</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-instance-MELT-syntax"><code>instance</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-integer-MELT-value">integer MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-introduction">introduction</a></td><td valign="top"><a href="#Top">Introduction</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Invoking-MELT">Invoking MELT</a></td><td valign="top"><a href="#Invoking-MELT">1.5 Invoking MELT</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-L">L</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-lambda-MELT-syntax"><code>lambda</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-let-MELT-syntax"><code>let</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-letrec-MELT-syntax"><code>letrec</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-list-MELT-syntax"><code>list</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-list-MELT-value">list MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-M">M</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-macro-string-in-MELT">macro string in MELT</a></td><td valign="top"><a href="#Lexical-MELT-conventions">1.7.1 Lexical MELT conventions</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-macro_002dexpansion-in-MELT">macro-expansion in MELT</a></td><td valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-match-MELT-syntax"><code>match</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-MELT">MELT</a></td><td valign="top"><a href="#MELT">1. MELT: Middle End Lisp Translator</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-MELT-as-a-plugin">MELT as a plugin</a></td><td valign="top"><a href="#MELT-as-a-plugin">1.4 MELT as a plugin</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-MELT-classes">MELT classes</a></td><td valign="top"><a href="#MELT-objects-and-classes">1.7.2.4 MELT objects and classes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-MELT-objects">MELT objects</a></td><td valign="top"><a href="#MELT-objects-and-classes">1.7.2.4 MELT objects and classes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-MELT-overview">MELT overview</a></td><td valign="top"><a href="#MELT-overview">1.2 MELT overview</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Middle-End-Lisp-Translator">Middle End Lisp Translator</a></td><td valign="top"><a href="#MELT">1. MELT: Middle End Lisp Translator</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-minor-MELT-garbage-collection">minor MELT garbage collection</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-mixints-MELT-value">mixints MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-mixlocs-MELT-value">mixlocs MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-modules-in-MELT">modules in MELT</a></td><td valign="top"><a href="#MELT-module-initialization-and-exports">1.7.3.3 MELT module initialization and exports</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-multicall-MELT-syntax"><code>multicall</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-multiple-MELT-value">multiple MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-N">N</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-nil-MELT-value">nil MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-normalization-in-MELT">normalization in MELT</a></td><td valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-nrep-in-MELT">nrep in MELT</a></td><td valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-O">O</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-objcode-in-MELT">objcode in MELT</a></td><td valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-object-map-MELT-value">object map MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-object-MELT-value">object MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-object-MELT-values">object MELT values</a></td><td valign="top"><a href="#MELT-objects-and-classes">1.7.2.4 MELT objects and classes</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-or-MELT-syntax"><code>or</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-P">P</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-pair-MELT-value">pair MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-parent_005fmodule_005fenvironment-MELT-syntax"><code>parent_module_environment</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Primitive-in-MELT">Primitive in MELT</a></td><td valign="top"><a href="#Primitives-in-MELT">1.6.2 Primitives in MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-progn-MELT-syntax"><code>progn</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-put_005ffields-MELT-syntax_002e"><code>put_fields</code> MELT syntax.</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-Q">Q</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-quote-MELT-syntax"><code>quote</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-R">R</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-reader-in-MELT">reader in MELT</a></td><td valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Reference-on-MELT">Reference on MELT</a></td><td valign="top"><a href="#Reference-on-MELT">1.7 Reference on MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-return-MELT-syntax"><code>return</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-routine-MELT-value">routine MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-S">S</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-s_002dexpression-in-MELT">s-expression in MELT</a></td><td valign="top"><a href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-setq-MELT-syntax"><code>setq</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-special-MELT-values">special MELT values</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-store_005fpredefined-MELT-syntax"><code>store_predefined</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-string-map-MELT-value">string map MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-string-MELT-value">string MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-string_002dbuffer-MELT-value">string-buffer MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-T">T</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-translation-of-MELT">translation of MELT</a></td><td valign="top"><a href="#translating-a-MELT-module">1.7.3.2 translating a MELT module</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-triple-MELT-value">triple MELT value</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-tuple-MELT-syntax"><code>tuple</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-Tutorial-about-MELT">Tutorial about MELT</a></td><td valign="top"><a href="#Tutorial-about-MELT">1.6 Tutorial about MELT</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-U">U</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-unboxed-MELT-stuff">unboxed MELT stuff</a></td><td valign="top"><a href="#Primitives-in-MELT">1.6.2 Primitives in MELT</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-unsafe_005fget_005ffield-MELT-syntax"><code>unsafe_get_field</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-unsafe_005fput_005ffields-MELT-syntax"><code>unsafe_put_fields</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-update_005fcurrent_005fmodule_005fenvironment_005fcontainer-MELT-syntax"><code>update_current_module_environment_container</code> MELT syntax</a></td><td valign="top"><a href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-upgrade_002dwarmelt-make-target-for-MELT"><code>upgrade-warmelt</code> make target for MELT</a></td><td valign="top"><a href="#Tutorial-about-MELT">1.6 Tutorial about MELT</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
<tr><th><a name="MELT-Concept-Index-1_cp_letter-V">V</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-values-in-MELT">values in MELT</a></td><td valign="top"><a href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></td></tr>
<tr><td colspan="3"> <hr></td></tr>
</table>
<table><tr><th valign="top">Jump to: </th><td><a href="#MELT-Concept-Index-1_cp_letter-A" class="summary-letter"><b>A</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-B" class="summary-letter"><b>B</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-C" class="summary-letter"><b>C</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-D" class="summary-letter"><b>D</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-E" class="summary-letter"><b>E</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-F" class="summary-letter"><b>F</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-G" class="summary-letter"><b>G</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-I" class="summary-letter"><b>I</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-L" class="summary-letter"><b>L</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-M" class="summary-letter"><b>M</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-N" class="summary-letter"><b>N</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-O" class="summary-letter"><b>O</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-P" class="summary-letter"><b>P</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-Q" class="summary-letter"><b>Q</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-R" class="summary-letter"><b>R</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-S" class="summary-letter"><b>S</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-T" class="summary-letter"><b>T</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-U" class="summary-letter"><b>U</b></a>
<a href="#MELT-Concept-Index-1_cp_letter-V" class="summary-letter"><b>V</b></a>
</td></tr></table>
<hr size="6">
<a name="SEC_Foot"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<h1>Footnotes</h1>
<h3><a name="FOOT1" href="#DOCF1">(1)</a></h3>
<p><code>curfnum</code> is a C macro expanding
to <code>curframe__.varnum</code>
</p><h3><a name="FOOT2" href="#DOCF2">(2)</a></h3>
<p>The C code for the normalization of <var>a</var> which
assigns <code>curfnum[3]</code> occurs before, so translating MELT to C is
not a simple rewriting algorithm..
</p><h3><a name="FOOT3" href="#DOCF3">(3)</a></h3>
<p>The <code>#line</code> directive can be
disabled by compiling the generated C with
<code>-DMELTGCC_NOLINENUMBERING</code>.
</p><h3><a name="FOOT4" href="#DOCF4">(4)</a></h3>
<p><code>melt_apply</code> is a short inlined
function defined in ‘<tt>gcc/melt.h</tt>’ which checks that the applied
value is indeed a MELT function closure and calls its routine.
</p><h3><a name="FOOT5" href="#DOCF5">(5)</a></h3>
<p>There is an ordered sequence of MELT modules, the
very first, <code>warmelt-first</code>, being translated specially and gets
a nil parent.
</p><h3><a name="FOOT6" href="#DOCF6">(6)</a></h3>
<p>If a class is
exported using <code>export_value</code> -almost always a mistake-, its
fields are not visible outside.
</p><h3><a name="FOOT7" href="#DOCF7">(7)</a></h3>
<p>We
use ML like syntax to emphasize that this is only an internal MELT
representation, not an s-expr!
</p><h3><a name="FOOT8" href="#DOCF8">(8)</a></h3>
<p>this is not a proper term, since
the generated code is only a representation of low level C code.
</p><h3><a name="FOOT9" href="#DOCF9">(9)</a></h3>
<p>using the <code>upgrade-warmelt</code> make target.
</p><h3><a name="FOOT10" href="#DOCF10">(10)</a></h3>
<p>It is essential to ensure that every MELT
value has the good magic numer in its discriminant. Violating that
would crash GCC MELT.
</p><hr size="1">
<a name="SEC_Contents"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<h1>Table of Contents</h1>
<div class="contents">
<ul class="toc">
<li><a name="toc-MELT_003a-Middle-End-Lisp-Translator" href="#MELT">1. MELT: Middle End Lisp Translator</a>
<ul class="toc">
<li><a name="toc-MELT-Prerequisites-1" href="#MELT-Prerequisites">1.1 MELT Prerequisites</a></li>
<li><a name="toc-MELT-overview-1" href="#MELT-overview">1.2 MELT overview</a></li>
<li><a name="toc-Building-the-MELT-branch-1" href="#Building-the-MELT-branch">1.3 Building the MELT branch</a></li>
<li><a name="toc-MELT-as-a-plugin-1" href="#MELT-as-a-plugin">1.4 MELT as a plugin</a></li>
<li><a name="toc-Invoking-MELT-1" href="#Invoking-MELT">1.5 Invoking MELT</a></li>
<li><a name="toc-Tutorial-about-MELT-1" href="#Tutorial-about-MELT">1.6 Tutorial about MELT</a>
<ul class="toc">
<li><a name="toc-Reserved-MELT-syntax-and-symbols-1" href="#Reserved-MELT-syntax-and-symbols">1.6.1 Reserved MELT syntax and symbols</a></li>
<li><a name="toc-Primitives-in-MELT-1" href="#Primitives-in-MELT">1.6.2 Primitives in MELT</a></li>
<li><a name="toc-Citerators-in-MELT-1" href="#Citerators-in-MELT">1.6.3 Citerators in MELT</a></li>
<li><a name="toc-Functions-in-MELT-1" href="#Functions-in-MELT">1.6.4 Functions in MELT</a></li>
</ul></li>
<li><a name="toc-Reference-on-MELT-1" href="#Reference-on-MELT">1.7 Reference on MELT</a>
<ul class="toc">
<li><a name="toc-Lexical-MELT-conventions-1" href="#Lexical-MELT-conventions">1.7.1 Lexical MELT conventions</a></li>
<li><a name="toc-Main-MELT-syntax-and-features-1" href="#Main-MELT-syntax-and-features">1.7.2 Main MELT syntax and features</a>
<ul class="toc">
<li><a name="toc-MELT-formals-1" href="#MELT-formals">1.7.2.1 MELT formals</a></li>
<li><a name="toc-MELT-ctypes-1" href="#MELT-ctypes">1.7.2.2 MELT ctypes</a></li>
<li><a name="toc-MELT-boxed-values-1" href="#MELT-boxed-values">1.7.2.3 MELT boxed values</a></li>
<li><a name="toc-MELT-objects-and-classes-1" href="#MELT-objects-and-classes">1.7.2.4 MELT objects and classes</a></li>
<li><a name="toc-MELT-function-application-1" href="#MELT-function-application">1.7.2.5 MELT function application</a></li>
<li><a name="toc-MELT-function-abstraction-and-closures-1" href="#MELT-function-abstraction-and-closures">1.7.2.6 MELT function abstraction and closures</a></li>
<li><a name="toc-MELT-message-sending-1" href="#MELT-message-sending">1.7.2.7 MELT message sending</a></li>
<li><a name="toc-MELT-syntax-constructs-1" href="#MELT-syntax-constructs">1.7.2.8 MELT syntax constructs</a></li>
</ul></li>
<li><a name="toc-MELT-modules-and-translation-1" href="#MELT-modules-and-translation">1.7.3 MELT modules and translation</a>
<ul class="toc">
<li><a name="toc-MELT-environments-and-bindings-1" href="#MELT-environments-and-bindings">1.7.3.1 MELT environments and bindings</a></li>
<li><a name="toc-translating-a-MELT-module-1" href="#translating-a-MELT-module">1.7.3.2 translating a MELT module</a></li>
<li><a name="toc-MELT-module-initialization-and-exports-1" href="#MELT-module-initialization-and-exports">1.7.3.3 MELT module initialization and exports</a></li>
<li><a name="toc-MELT-translation-steps-1" href="#MELT-translation-steps">1.7.3.4 MELT translation steps</a></li>
</ul></li>
<li><a name="toc-Writing-GCC-passes-in-MELT-1" href="#Writing-GCC-passes-in-MELT">1.7.4 Writing GCC passes in MELT</a></li>
</ul></li>
<li><a name="toc-Writing-C-code-for-MELT-1" href="#Writing-C-code-for-MELT">1.8 Writing C code for MELT</a></li>
</ul></li>
<li><a name="toc-Funding-Free-Software" href="#Funding">Funding Free Software</a></li>
<li><a name="toc-The-GNU-Project-and-GNU_002fLinux" href="#GNU-Project">The GNU Project and GNU/Linux</a></li>
<li><a name="toc-GNU-General-Public-License" href="#Copying">GNU General Public License</a></li>
<li><a name="toc-GNU-Free-Documentation-License-1" href="#GNU-Free-Documentation-License">GNU Free Documentation License</a>
<ul class="toc">
<li><a name="toc-ADDENDUM_003a-How-to-use-this-License-for-your-documents" href="#ADDENDUM_003a-How-to-use-this-License-for-your-documents">ADDENDUM: How to use this License for your documents</a></li>
</ul></li>
<li><a name="toc-MELT-Option-Index-1" href="#MELT-Option-Index">MELT Option Index</a></li>
<li><a name="toc-MELT-Concept-Index-1" href="#MELT-Concept-Index">MELT Concept Index</a></li>
</ul>
</div>
<hr size="1">
<a name="SEC_Overview"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<h1>Short Table of Contents</h1>
<div class="shortcontents">
<ul class="toc">
<li><a name="stoc-MELT_003a-Middle-End-Lisp-Translator" href="#MELT">1. MELT: Middle End Lisp Translator</a></li>
<li><a name="stoc-Funding-Free-Software" href="#Funding">Funding Free Software</a></li>
<li><a name="stoc-The-GNU-Project-and-GNU_002fLinux" href="#GNU-Project">The GNU Project and GNU/Linux</a></li>
<li><a name="stoc-GNU-General-Public-License" href="#Copying">GNU General Public License</a></li>
<li><a name="stoc-GNU-Free-Documentation-License-1" href="#GNU-Free-Documentation-License">GNU Free Documentation License</a></li>
<li><a name="stoc-MELT-Option-Index-1" href="#MELT-Option-Index">MELT Option Index</a></li>
<li><a name="stoc-MELT-Concept-Index-1" href="#MELT-Concept-Index">MELT Concept Index</a></li>
</ul>
</div>
<hr size="1">
<a name="SEC_About"></a>
<table cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="#MELT-Option-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="#SEC_About" title="About (help)"> ? </a>]</td>
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<h1>About This Document</h1>
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where the <strong> Example </strong> assumes that the current position is at <strong> Subsubsection One-Two-Three </strong> of a document of the following structure:
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