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824 lines
38 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<title>The LLVM Compiler Driver (llvmc)</title>
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<link rel="stylesheet" href="llvm.css" type="text/css">
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<meta name="author" content="Reid Spencer">
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<meta name="description"
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content="A description of the use and design of the LLVM Compiler Driver.">
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</head>
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<body>
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<div class="doc_title">The LLVM Compiler Driver (llvmc)</div>
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<p class="doc_warning">NOTE: This document is a work in progress!</p>
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<ol>
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<li><a href="#abstract">Abstract</a></li>
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<li><a href="#introduction">Introduction</a>
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<ol>
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<li><a href="#purpose">Purpose</a></li>
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<li><a href="#operation">Operation</a></li>
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<li><a href="#phases">Phases</a></li>
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<li><a href="#actions">Actions</a></li>
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</ol>
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</li>
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<li><a href="#configuration">Configuration</a>
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<ol>
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<li><a href="#overview">Overview</a></li>
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<li><a href="#filetypes">Configuration Files</a></li>
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<li><a href="#syntax">Syntax</a></li>
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<li><a href="#substitutions">Substitutions</a></li>
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<li><a href="#sample">Sample Config File</a></li>
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</ol>
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<li><a href="#glossary">Glossary</a>
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</ol>
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<div class="doc_author">
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<p>Written by <a href="mailto:rspencer@x10sys.com">Reid Spencer</a>
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</p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section"> <a name="abstract">Abstract</a></div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>This document describes the requirements, design, and configuration of the
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LLVM compiler driver, <tt>llvmc</tt>. The compiler driver knows about LLVM's
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tool set and can be configured to know about a variety of compilers for
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source languages. It uses this knowledge to execute the tools necessary
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to accomplish general compilation, optimization, and linking tasks. The main
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purpose of <tt>llvmc</tt> is to provide a simple and consistent interface to
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all compilation tasks. This reduces the burden on the end user who can just
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learn to use <tt>llvmc</tt> instead of the entire LLVM tool set and all the
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source language compilers compatible with LLVM.</p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section"> <a name="introduction">Introduction</a></div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>The <tt>llvmc</tt> <a href="#def_tool">tool</a> is a configurable compiler
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<a href="#def_driver">driver</a>. As such, it isn't a compiler, optimizer,
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or a linker itself but it drives (invokes) other software that perform those
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tasks. If you are familiar with the GNU Compiler Collection's <tt>gcc</tt>
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tool, <tt>llvmc</tt> is very similar.</p>
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<p>The following introductory sections will help you understand why this tool
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is necessary and what it does.</p>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsection"><a name="purpose">Purpose</a></div>
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<div class="doc_text">
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<p><tt>llvmc</tt> was invented to make compilation of user programs with
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LLVM-based tools easier. To accomplish this, <tt>llvmc</tt> strives to:</p>
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<ul>
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<li>Be the single point of access to most of the LLVM tool set.</li>
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<li>Hide the complexities of the LLVM tools through a single interface.</li>
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<li>Provide a consistent interface for compiling all languages.</li>
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</ul>
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<p>Additionally, <tt>llvmc</tt> makes it easier to write a compiler for use
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with LLVM, because it:</p>
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<ul>
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<li>Makes integration of existing non-LLVM tools simple.</li>
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<li>Extends the capabilities of minimal compiler tools by optimizing their
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output.</li>
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<li>Reduces the number of interfaces a compiler writer must know about
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before a working compiler can be completed (essentially only the VMCore
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interfaces need to be understood).</li>
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<li>Supports source language translator invocation via both dynamically
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loadable shared objects and invocation of an executable.</li>
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</ul>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsection"><a name="operation">Operation</a></div>
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<div class="doc_text">
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<p>At a high level, <tt>llvmc</tt> operation is very simple. The basic action
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taken by <tt>llvmc</tt> is to simply invoke some tool or set of tools to fill
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the user's request for compilation. Every execution of <tt>llvmc</tt>takes the
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following sequence of steps:</p>
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<dl>
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<dt><b>Collect Command Line Options</b></dt>
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<dd>The command line options provide the marching orders to <tt>llvmc</tt>
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on what actions it should perform. This is the request the user is making
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of <tt>llvmc</tt> and it is interpreted first. See the <tt>llvmc</tt>
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<a href="CommandGuide/html/llvmc.html">manual page</a> for details on the
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options.</dd>
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<dt><b>Read Configuration Files</b></dt>
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<dd>Based on the options and the suffixes of the filenames presented, a set
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of configuration files are read to configure the actions <tt>llvmc</tt> will
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take. Configuration files are provided by either LLVM or the
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compiler tools that <tt>llvmc</tt> invokes. These files determine what
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actions <tt>llvmc</tt> will take in response to the user's request. See
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the section on <a href="#configuration">configuration</a> for more details.
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</dd>
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<dt><b>Determine Phases To Execute</b></dt>
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<dd>Based on the command line options and configuration files,
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<tt>llvmc</tt> determines the compilation <a href="#phases">phases</a> that
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must be executed by the user's request. This is the primary work of
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<tt>llvmc</tt>.</dd>
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<dt><b>Determine Actions To Execute</b></dt>
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<dd>Each <a href="#phases">phase</a> to be executed can result in the
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invocation of one or more <a href="#actions">actions</a>. An action is
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either a whole program or a function in a dynamically linked shared library.
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In this step, <tt>llvmc</tt> determines the sequence of actions that must be
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executed. Actions will always be executed in a deterministic order.</dd>
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<dt><b>Execute Actions</b></dt>
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<dd>The <a href="#actions">actions</a> necessary to support the user's
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original request are executed sequentially and deterministically. All
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actions result in either the invocation of a whole program to perform the
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action or the loading of a dynamically linkable shared library and invocation
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of a standard interface function within that library.</dd>
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<dt><b>Termination</b></dt>
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<dd>If any action fails (returns a non-zero result code), <tt>llvmc</tt>
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also fails and returns the result code from the failing action. If
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everything succeeds, <tt>llvmc</tt> will return a zero result code.</dd>
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</dl>
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<p><tt>llvmc</tt>'s operation must be simple, regular and predictable.
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Developers need to be able to rely on it to take a consistent approach to
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compilation. For example, the invocation:</p>
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<code>
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llvmc -O2 x.c y.c z.c -o xyz</code>
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<p>must produce <i>exactly</i> the same results as:</p>
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<pre><tt>
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llvmc -O2 x.c -o x.o
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llvmc -O2 y.c -o y.o
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llvmc -O2 z.c -o z.o
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llvmc -O2 x.o y.o z.o -o xyz</tt></pre>
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<p>To accomplish this, <tt>llvmc</tt> uses a very simple goal oriented
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procedure to do its work. The overall goal is to produce a functioning
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executable. To accomplish this, <tt>llvmc</tt> always attempts to execute a
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series of compilation <a href="#def_phase">phases</a> in the same sequence.
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However, the user's options to <tt>llvmc</tt> can cause the sequence of phases
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to start in the middle or finish early.</p>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsection"><a name="phases"></a>Phases </div>
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<div class="doc_text">
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<p><tt>llvmc</tt> breaks every compilation task into the following five
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distinct phases:</p>
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<dl><dt><b>Preprocessing</b></dt><dd>Not all languages support preprocessing;
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but for those that do, this phase can be invoked. This phase is for
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languages that provide combining, filtering, or otherwise altering with the
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source language input before the translator parses it. Although C and C++
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are the most common users of this phase, other languages may provide their
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own preprocessor (whether its the C pre-processor or not).</dd>
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</dl>
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<dl><dt><b>Translation</b></dt><dd>The translation phase converts the source
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language input into something that LLVM can interpret and use for
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downstream phases. The translation is essentially from "non-LLVM form" to
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"LLVM form".</dd>
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</dl>
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<dl><dt><b>Optimization</b></dt><dd>Once an LLVM Module has been obtained from
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the translation phase, the program enters the optimization phase. This phase
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attempts to optimize all of the input provided on the command line according
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to the options provided.</dd>
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</dl>
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<dl><dt><b>Linking</b></dt><dd>The inputs are combined to form a complete
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program.</dd>
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</dl>
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<p>The following table shows the inputs, outputs, and command line options
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applicabe to each phase.</p>
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<table>
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<tr>
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<th style="width: 10%">Phase</th>
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<th style="width: 25%">Inputs</th>
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<th style="width: 25%">Outputs</th>
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<th style="width: 40%">Options</th>
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</tr>
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<tr><td><b>Preprocessing</b></td>
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<td class="td_left"><ul><li>Source Language File</li></ul></td>
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<td class="td_left"><ul><li>Source Language File</li></ul></td>
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<td class="td_left"><dl>
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<dt><tt>-E</tt></dt>
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<dd>Stops the compilation after preprocessing</dd>
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</dl></td>
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</tr>
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<tr>
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<td><b>Translation</b></td>
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<td class="td_left"><ul>
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<li>Source Language File</li>
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</ul></td>
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<td class="td_left"><ul>
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<li>LLVM Assembly</li>
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<li>LLVM Bytecode</li>
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<li>LLVM C++ IR</li>
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</ul></td>
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<td class="td_left"><dl>
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<dt><tt>-c</tt></dt>
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<dd>Stops the compilation after translation so that optimization and
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linking are not done.</dd>
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<dt><tt>-S</tt></dt>
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<dd>Stops the compilation before object code is written so that only
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assembly code remains.</dd>
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</dl></td>
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</tr>
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<tr>
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<td><b>Optimization</b></td>
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<td class="td_left"><ul>
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<li>LLVM Assembly</li>
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<li>LLVM Bytecode</li>
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</ul></td>
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<td class="td_left"><ul>
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<li>LLVM Bytecode</li>
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</ul></td>
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<td class="td_left"><dl>
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<dt><tt>-Ox</tt>
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<dd>This group of options controls the amount of optimization
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performed.</dd>
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</dl></td>
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</tr>
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<tr>
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<td><b>Linking</b></td>
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<td class="td_left"><ul>
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<li>LLVM Bytecode</li>
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<li>Native Object Code</li>
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<li>LLVM Library</li>
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<li>Native Library</li>
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</ul></td>
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<td class="td_left"><ul>
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<li>LLVM Bytecode Executable</li>
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<li>Native Executable</li>
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</ul></td>
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<td class="td_left"><dl>
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<dt><tt>-L</tt></dt><dd>Specifies a path for library search.</dd>
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<dt><tt>-l</tt></dt><dd>Specifies a library to link in.</dd>
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</dl></td>
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</tr>
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</table>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsection"><a name="actions"></a>Actions</div>
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<div class="doc_text">
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<p>An action, with regard to <tt>llvmc</tt> is a basic operation that it takes
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in order to fulfill the user's request. Each phase of compilation will invoke
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zero or more actions in order to accomplish that phase.</p>
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<p>Actions come in two forms:</p>
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<ul>
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<li>Invokable Executables</li>
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<li>Functions in a shared library</li>
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</ul>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section"><a name="configuration">Configuration</a></div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>This section of the document describes the configuration files used by
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<tt>llvmc</tt>. Configuration information is relatively static for a
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given release of LLVM and a compiler tool. However, the details may
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change from release to release of either. Users are encouraged to simply use
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the various options of the <tt>llvmc</tt> command and ignore the configuration
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of the tool. These configuration files are for compiler writers and LLVM
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developers. Those wishing to simply use <tt>llvmc</tt> don't need to understand
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this section but it may be instructive on how the tool works.</p>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsection"><a name="overview"></a>Overview</div>
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<div class="doc_text">
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<p><tt>llvmc</tt> is highly configurable both on the command line and in
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configuration files. The options it understands are generic, consistent and
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simple by design. Furthermore, the <tt>llvmc</tt> options apply to the
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compilation of any LLVM enabled programming language. To be enabled as a
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supported source language compiler, a compiler writer must provide a
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configuration file that tells <tt>llvmc</tt> how to invoke the compiler
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and what its capabilities are. The purpose of the configuration files then
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is to allow compiler writers to specify to <tt>llvmc</tt> how the compiler
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should be invoked. Users may but are not advised to alter the compiler's
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<tt>llvmc</tt> configuration.</p>
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<p>Because <tt>llvmc</tt> just invokes other programs, it must deal with the
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available command line options for those programs regardless of whether they
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were written for LLVM or not. Furthermore, not all compiler tools will
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have the same capabilities. Some compiler tools will simply generate LLVM assembly
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code, others will be able to generate fully optimized byte code. In general,
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<tt>llvmc</tt> doesn't make any assumptions about the capabilities or command
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line options of a sub-tool. It simply uses the details found in the
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configuration files and leaves it to the compiler writer to specify the
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configuration correctly.</p>
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<p>This approach means that new compiler tools can be up and working very
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quickly. As a first cut, a tool can simply compile its source to raw
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(unoptimized) bytecode or LLVM assembly and <tt>llvmc</tt> can be configured
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to pick up the slack (translate LLVM assembly to bytecode, optimize the
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bytecode, generate native assembly, link, etc.). In fact, the compiler tools
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need not use any LLVM libraries, and it could be written in any language
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(instead of C++). The configuration data will allow the full range of
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optimization, assembly, and linking capabilities that LLVM provides to be added
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to these kinds of tools. Enabling the rapid development of front-ends is one
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of the primary goals of <tt>llvmc</tt>.</p>
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<p>As a compiler tool matures, it may utilize the LLVM libraries and tools
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to more efficiently produce optimized bytecode directly in a single compilation
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and optimization program. In these cases, multiple tools would not be needed
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and the configuration data for the compiler would change.</p>
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<p>Configuring <tt>llvmc</tt> to the needs and capabilities of a source language
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compiler is relatively straight-forward. A compiler writer must provide a
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definition of what to do for each of the five compilation phases for each of
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the optimization levels. The specification consists simply of prototypical
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command lines into which <tt>llvmc</tt> can substitute command line
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arguments and file names. Note that any given phase can be completely blank if
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the source language's compiler combines multiple phases into a single program.
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For example, quite often pre-processing, translation, and optimization are
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combined into a single program. The specification for such a compiler would have
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blank entries for pre-processing and translation but a full command line for
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optimization.</p>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsection"><a name="filetypes">Configuration Files</a></div>
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<div class="doc_subsubsection"><a name="filecontents">File Contents</a></div>
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<div class="doc_text">
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<p>Each configuration file provides the details for a single source language
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that is to be compiled. This configuration information tells <tt>llvmc</tt>
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how to invoke the language's pre-processor, translator, optimizer, assembler
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and linker. Note that a given source language needn't provide all these tools
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as many of them exist in llvm currently.</p>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsubsection"><a name="dirsearch">Directory Search</a></div>
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<div class="doc_text">
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<p><tt>llvmc</tt> always looks for files of a specific name. It uses the
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first file with the name its looking for by searching directories in the
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following order:<br/>
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<ol>
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<li>Any directory specified by the <tt>-config-dir</tt> option will be
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checked first.</li>
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<li>If the environment variable LLVM_CONFIG_DIR is set, and it contains
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the name of a valid directory, that directory will be searched next.</li>
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<li>If the user's home directory (typically <tt>/home/user</tt> contains
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a sub-directory named <tt>.llvm</tt> and that directory contains a
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sub-directory named <tt>etc</tt> then that directory will be tried
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next.</li>
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<li>If the LLVM installation directory (typically <tt>/usr/local/llvm</tt>
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contains a sub-directory named <tt>etc</tt> then that directory will be
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tried last.</li>
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<li>A standard "system" directory will be searched next. This is typically
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<tt>/etc/llvm</tt> on UNIX™ and <tt>C:\WINNT</tt> on Microsoft
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Windows™.</li>
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<li>If the configuration file sought still can't be found, <tt>llvmc</tt>
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will print an error message and exit.</li>
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</ol>
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<p>The first file found in this search will be used. Other files with the
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same name will be ignored even if they exist in one of the subsequent search
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locations.</p>
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</div>
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|
<div class="doc_subsubsection"><a name="filenames">File Names</a></div>
|
|
<div class="doc_text">
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|
<p>In the directories searched, each configuration file is given a specific
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name to foster faster lookup (so llvmc doesn't have to do directory searches).
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The name of a given language specific configuration file is simply the same
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as the suffix used to identify files containing source in that language.
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|
For example, a configuration file for C++ source might be named
|
|
<tt>cpp</tt>, <tt>C</tt>, or <tt>cxx</tt>. For languages that support multiple
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file suffixes, multiple (probably identical) files (or symbolic links) will
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need to be provided.</p>
|
|
</div>
|
|
|
|
<div class="doc_subsubsection"><a name="whatgetsread">What Gets Read</a></div>
|
|
<div class="doc_text">
|
|
<p>Which configuration files are read depends on the command line options and
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|
the suffixes of the file names provided on <tt>llvmc</tt>'s command line. Note
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that the <tt>-x LANGUAGE</tt> option alters the language that <tt>llvmc</tt>
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uses for the subsequent files on the command line. Only the configuration
|
|
files actually needed to complete <tt>llvmc</tt>'s task are read. Other
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language specific files will be ignored.</p>
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</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
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|
<div class="doc_subsection"><a name="syntax"></a>Syntax</div>
|
|
<div class="doc_text">
|
|
<p>The syntax of the configuration files is very simple and somewhat
|
|
compatible with Java's property files. Here are the syntax rules:</p>
|
|
<ul>
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<li>The file encoding is ASCII.</li>
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|
<li>The file is line oriented. There should be one configuration definition
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|
per line. Lines are terminated by the newline (0x0A) and/or carriage return
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characters (0x0D)</li>
|
|
<li>A backslash (<tt>\</tt>) before a newline causes the newline to be
|
|
ignored. This is useful for line continuation of long definitions. A
|
|
backslash anywhere else is recognized as a backslash.</li>
|
|
<li>A configuration item consists of a name, an <tt>=</tt> and a value.</li>
|
|
<li>A name consists of a sequence of identifiers separated by period.</li>
|
|
<li>An identifier consists of specific keywords made up of only lower case
|
|
and upper case letters (e.g. <tt>lang.name</tt>).</li>
|
|
<li>Values come in four flavors: booleans, integers, commands and
|
|
strings.</li>
|
|
<li>Valid "false" boolean values are <tt>false False FALSE no No NO
|
|
off Off</tt> and <tt>OFF</tt>.</li>
|
|
<li>Valid "true" boolean values are <tt>true True TRUE yes Yes YES
|
|
on On</tt> and <tt>ON</tt>.</li>
|
|
<li>Integers are simply sequences of digits.</li>
|
|
<li>Commands start with a program name and are followed by a sequence of
|
|
words that are passed to that program as command line arguments. Program
|
|
arguments that begin and end with the <tt>%</tt> sign will have their value
|
|
substituted. Program names beginning with <tt>/</tt> are considered to be
|
|
absolute. Otherwise the <tt>PATH</tt> will be applied to find the program to
|
|
execute.</li>
|
|
<li>Strings are composed of multiple sequences of characters from the
|
|
character class <tt>[-A-Za-z0-9_:%+/\\|,]</tt> separated by white
|
|
space.</li>
|
|
<li>White space on a line is folded. Multiple blanks or tabs will be
|
|
reduced to a single blank.</li>
|
|
<li>White space before the configuration item's name is ignored.</li>
|
|
<li>White space on either side of the <tt>=</tt> is ignored.</li>
|
|
<li>White space in a string value is used to separate the individual
|
|
components of the string value but otherwise ignored.</li>
|
|
<li>Comments are introduced by the <tt>#</tt> character. Everything after a
|
|
<tt>#</tt> and before the end of line is ignored.</li>
|
|
</ul>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsection"><a name="items">Configuration Items</a></div>
|
|
<div class="doc_text">
|
|
<p>The table below provides definitions of the allowed configuration items
|
|
that may appear in a configuration file. Every item has a default value and
|
|
does not need to appear in the configuration file. Missing items will have the
|
|
default value. Each identifier may appear as all lower case, first letter
|
|
capitalized or all upper case.</p>
|
|
<table>
|
|
<tbody>
|
|
<tr>
|
|
<th>Name</th>
|
|
<th>Value Type</th>
|
|
<th>Description</th>
|
|
<th>Default</th>
|
|
</tr>
|
|
<tr><td colspan="4"><h4>LLVMC ITEMS</h4></td></tr>
|
|
<tr>
|
|
<td><b>version</b></td>
|
|
<td>string</td>
|
|
<td class="td_left">Provides the version string for the contents of this
|
|
configuration file. What is accepted as a legal configuration file
|
|
will change over time and this item tells <tt>llvmc</tt> which version
|
|
should be expected.</td>
|
|
<td><i>b</i></td>
|
|
</tr>
|
|
<tr><td colspan="4"><h4>LANG ITEMS</h4></td></tr>
|
|
<tr>
|
|
<td><b>lang.name</b></td>
|
|
<td>string</td>
|
|
<td class="td_left">Provides the common name for a language definition.
|
|
For example "C++", "Pascal", "FORTRAN", etc.</td>
|
|
<td><i>blank</i></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>lang.opt1</b></td>
|
|
<td>string</td>
|
|
<td class="td_left">Specifies the parameters to give the optimizer when
|
|
<tt>-O1</tt> is specified on the <tt>llvmc</tt> command line.</td>
|
|
<td><tt>-simplifycfg -instcombine -mem2reg</tt></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>lang.opt2</b></td>
|
|
<td>string</td>
|
|
<td class="td_left">Specifies the parameters to give the optimizer when
|
|
<tt>-O2</tt> is specified on the <tt>llvmc</tt> command line.</td>
|
|
<td><i>TBD</i></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>lang.opt3</b></td>
|
|
<td>string</td>
|
|
<td class="td_left">Specifies the parameters to give the optimizer when
|
|
<tt>-O3</tt> is specified on the <tt>llvmc</tt> command line.</td>
|
|
<td><i>TBD</i></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>lang.opt4</b></td>
|
|
<td>string</td>
|
|
<td class="td_left">Specifies the parameters to give the optimizer when
|
|
<tt>-O4</tt> is specified on the <tt>llvmc</tt> command line.</td>
|
|
<td><i>TBD</i></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>lang.opt5</b></td>
|
|
<td>string</td>
|
|
<td class="td_left">Specifies the parameters to give the optimizer when
|
|
<tt>-O5</tt> is specified on the <tt>llvmc</tt> command line.</td>
|
|
<td><i>TBD</i></td>
|
|
</tr>
|
|
<tr><td colspan="4"><h4>PREPROCESSOR ITEMS</h4></td></tr>
|
|
<tr>
|
|
<td><b>preprocessor.command</b></td>
|
|
<td>command</td>
|
|
<td class="td_left">This provides the command prototype that will be used
|
|
to run the preprocessor. This is generally only used with the
|
|
<tt>-E</tt> option.</td>
|
|
<td><blank></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>preprocessor.required</b></td>
|
|
<td>boolean</td>
|
|
<td class="td_left">This item specifies whether the pre-processing phase
|
|
is required by the language. If the value is true, then the
|
|
<tt>preprocessor.command</tt> value must not be blank. With this option,
|
|
<tt>llvmc</tt> will always run the preprocessor as it assumes that the
|
|
translation and optimization phases don't know how to pre-process their
|
|
input.</td>
|
|
<td>false</td>
|
|
</tr>
|
|
<tr><td colspan="4"><h4>TRANSLATOR ITEMS</h4></td></tr>
|
|
<tr>
|
|
<td><b>translator.command</b></td>
|
|
<td>command</td>
|
|
<td class="td_left">This provides the command prototype that will be used
|
|
to run the translator. Valid substitutions are <tt>%in%</tt> for the
|
|
input file and <tt>%out%</tt> for the output file.</td>
|
|
<td><blank></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>translator.output</b></td>
|
|
<td><tt>bytecode</tt> or <tt>assembly</tt></td>
|
|
<td class="td_left">This item specifies the kind of output the language's
|
|
translator generates.</td>
|
|
<td><tt>bytecode</tt></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>translator.preprocesses</b></td>
|
|
<td>boolean</td>
|
|
<td class="td_left">Indicates that the translator also preprocesses. If
|
|
this is true, then <tt>llvmc</tt> will skip the pre-processing phase
|
|
whenever the final phase is not pre-processing.</td>
|
|
<td><tt>false</tt></td>
|
|
</tr>
|
|
<tr><td colspan="4"><h4>OPTIMIZER ITEMS</h4></td></tr>
|
|
<tr>
|
|
<td><b>optimizer.command</b></td>
|
|
<td>command</td>
|
|
<td class="td_left">This provides the command prototype that will be used
|
|
to run the optimizer. Valid substitutions are <tt>%in%</tt> for the
|
|
input file and <tt>%out%</tt> for the output file.</td>
|
|
<td><blank></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>optimizer.output</b></td>
|
|
<td><tt>bytecode</tt> or <tt>assembly</tt></td>
|
|
<td class="td_left">This item specifies the kind of output the language's
|
|
optimizer generates. Valid values are "assembly" and "bytecode"</td>
|
|
<td><tt>bytecode</tt></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>optimizer.preprocesses</b></td>
|
|
<td>boolean</td>
|
|
<td class="td_left">Indicates that the optimizer also preprocesses. If
|
|
this is true, then <tt>llvmc</tt> will skip the pre-processing phase
|
|
whenever the final phase is optimization or later.</td>
|
|
<td><tt>false</tt></td>
|
|
</tr>
|
|
<tr>
|
|
<td><b>optimizer.translates</b></td>
|
|
<td>boolean</td>
|
|
<td class="td_left">Indicates that the optimizer also translates. If
|
|
this is true, then <tt>llvmc</tt> will skip the translation phase
|
|
whenever the final phase is optimization or later.</td>
|
|
<td><tt>false</tt></td>
|
|
</tr>
|
|
<tr><td colspan="4"><h4>ASSEMBLER ITEMS</h4></td></tr>
|
|
<tr>
|
|
<td><b>assembler.command</b></td>
|
|
<td>command</td>
|
|
<td class="td_left">This provides the command prototype that will be used
|
|
to run the assembler. Valid substitutions are <tt>%in%</tt> for the
|
|
input file and <tt>%out%</tt> for the output file.</td>
|
|
<td><blank></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsection"><a name="substitutions">Substitutions</a></div>
|
|
<div class="doc_text">
|
|
<p>On any configruation item that ends in <tt>command</tt>, you must
|
|
specify substitution tokens. Substitution tokens begin and end with a percent
|
|
sign (<tt>%</tt>) and are replaced by the corresponding text. Any substitution
|
|
token may be given on any <tt>command</tt> line but some are more useful than
|
|
others. In particular each command <em>should</em> have both an <tt>%in%</tt>
|
|
and an <tt>%out%</tt> substittution. The table below provides definitions of
|
|
each of the allowed substitution tokens.</p>
|
|
<table>
|
|
<tbody>
|
|
<tr>
|
|
<th>Substitution Token</th>
|
|
<th>Replacement Description</th>
|
|
</tr>
|
|
<tr>
|
|
<td><tt>%args%</tt></td>
|
|
<td class="td_left">Replaced with all the tool-specific arguments given
|
|
to <tt>llvmc</tt> via the <tt>-T</tt> set of options. This just allows
|
|
you to place these arguments in the correct place on the command line.
|
|
If the <tt>%args%</tt> option does not appear on your command line,
|
|
then you are explicitly disallowing the <tt>-T</tt> option for your
|
|
tool.
|
|
</td>
|
|
<tr>
|
|
<td><tt>%force%</tt></td>
|
|
<td class="td_left">Replaced with the <tt>-f</tt> option if it was
|
|
specified on the <tt>llvmc</tt> command line. This is intended to tell
|
|
the compiler tool to force the overwrite of output files.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td><tt>%in%</tt></td>
|
|
<td class="td_left">Replaced with the full path of the input file. You
|
|
needn't worry about the cascading of file names. <tt>llvmc</tt> will
|
|
create temporary files and ensure that the output of one phase is the
|
|
input to the next phase.</td>
|
|
</tr>
|
|
<tr>
|
|
<td><tt>%opt%</tt></td>
|
|
<td class="td_left">Replaced with the optimization options for the
|
|
tool. If the tool understands the <tt>-O</tt> options then that will
|
|
be passed. Otherwise, the <tt>lang.optN</tt> series of configuration
|
|
items will specify which arguments are to be given.</td>
|
|
</tr>
|
|
<tr>
|
|
<td><tt>%out%</tt></td>
|
|
<td class="td_left">Replaced with the full path of the output file.
|
|
Note that this is not necessarily the output file specified with the
|
|
<tt>-o</tt> option on <tt>llvmc</tt>'s command line. It might be a
|
|
temporary file that will be passed to a subsequent phase's input.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td><tt>%stats%</tt></td>
|
|
<td class="td_left">If your command accepts the <tt>-stats</tt> option,
|
|
use this substitution token. If the user requested <tt>-stats</tt>
|
|
from the <tt>llvmc</tt> command line then this token will be replaced
|
|
with <tt>-stats</tt>, otherwise it will be ignored.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td><tt>%target%</tt></td>
|
|
<td class="td_left">Replaced with the name of the target "machine" for
|
|
which code should be generated. The value used here is taken from the
|
|
<tt>llvmc</tt> option <tt>-march</tt>.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td><tt>%time%</tt></td>
|
|
<td class="td_left">If your command accepts the <tt>-time-passes</tt>
|
|
option, use this substitution token. If the user requested
|
|
<tt>-time-passes</tt> from the <tt>llvmc</tt> command line then this
|
|
token will be replaced with <tt>-time-passes</tt>, otherwise it will
|
|
be ignored.
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsection"><a name="sample">Sample Config File</a></div>
|
|
<div class="doc_text">
|
|
<p>Since an example is always instructive, here's how the Stacker language
|
|
configuration file looks.</p>
|
|
<pre><tt>
|
|
# Stacker Configuration File For llvmc
|
|
|
|
##########################################################
|
|
# Language definitions
|
|
##########################################################
|
|
lang.name=Stacker
|
|
lang.opt1=-simplifycfg -instcombine -mem2reg
|
|
lang.opt2=-simplifycfg -instcombine -mem2reg -load-vn \
|
|
-gcse -dse -scalarrepl -sccp
|
|
lang.opt3=-simplifycfg -instcombine -mem2reg -load-vn \
|
|
-gcse -dse -scalarrepl -sccp -branch-combine -adce \
|
|
-globaldce -inline -licm
|
|
lang.opt4=-simplifycfg -instcombine -mem2reg -load-vn \
|
|
-gcse -dse -scalarrepl -sccp -ipconstprop \
|
|
-branch-combine -adce -globaldce -inline -licm
|
|
lang.opt5=-simplifycfg -instcombine -mem2reg --load-vn \
|
|
-gcse -dse scalarrepl -sccp -ipconstprop \
|
|
-branch-combine -adce -globaldce -inline -licm \
|
|
-block-placement
|
|
|
|
##########################################################
|
|
# Pre-processor definitions
|
|
##########################################################
|
|
|
|
# Stacker doesn't have a preprocessor but the following
|
|
# allows the -E option to be supported
|
|
preprocessor.command=cp %in% %out%
|
|
preprocessor.required=false
|
|
|
|
##########################################################
|
|
# Translator definitions
|
|
##########################################################
|
|
|
|
# To compile stacker source, we just run the stacker
|
|
# compiler with a default stack size of 2048 entries.
|
|
translator.command=stkrc -s 2048 %in% -o %out% %time% \
|
|
%stats% %force% %args%
|
|
|
|
# stkrc doesn't preprocess but we set this to true so
|
|
# that we don't run the cp command by default.
|
|
translator.preprocesses=true
|
|
|
|
# The translator is required to run.
|
|
translator.required=true
|
|
|
|
# stkrc doesn't handle the -On options
|
|
translator.output=bytecode
|
|
|
|
##########################################################
|
|
# Optimizer definitions
|
|
##########################################################
|
|
|
|
# For optimization, we use the LLVM "opt" program
|
|
optimizer.command=opt %in% -o %out% %opt% %time% %stats% \
|
|
%force% %args%
|
|
|
|
optimizer.required = true
|
|
|
|
# opt doesn't translate
|
|
optimizer.translates = no
|
|
|
|
# opt doesn't preprocess
|
|
optimizer.preprocesses=no
|
|
|
|
# opt produces bytecode
|
|
optimizer.output = bc
|
|
|
|
##########################################################
|
|
# Assembler definitions
|
|
##########################################################
|
|
assembler.command=llc %in% -o %out% %target% %time% %stats%
|
|
</tt></pre>
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section"><a name="glossary">Glossary</a></div>
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_text">
|
|
<p>This document uses precise terms in reference to the various artifacts and
|
|
concepts related to compilation. The terms used throughout this document are
|
|
defined below.</p>
|
|
<dl>
|
|
<dt><a name="def_assembly"><b>assembly</b></a></dt>
|
|
<dd>A compilation <a href="#def_phase">phase</a> in which LLVM bytecode or
|
|
LLVM assembly code is assembled to a native code format (either target
|
|
specific aseembly language or the platform's native object file format).
|
|
</dd>
|
|
|
|
<dt><a name="def_compiler"><b>compiler</b></a></dt>
|
|
<dd>Refers to any program that can be invoked by <tt>llvmc</tt> to accomplish
|
|
the work of one or more compilation <a href="#def_phase">phases</a>.</dd>
|
|
|
|
<dt><a name="def_driver"><b>driver</b></a></dt>
|
|
<dd>Refers to <tt>llvmc</tt> itself.</dd>
|
|
|
|
<dt><a name="def_linking"><b>linking</b></a></dt>
|
|
<dd>A compilation <a href="#def_phase">phase</a> in which LLVM bytecode files
|
|
and (optionally) native system libraries are combined to form a complete
|
|
executable program.</dd>
|
|
|
|
<dt><a name="def_optimization"><b>optimization</b></a></dt>
|
|
<dd>A compilation <a href="#def_phase">phase</a> in which LLVM bytecode is
|
|
optimized.</dd>
|
|
|
|
<dt><a name="def_phase"><b>phase</b></a></dt>
|
|
<dd>Refers to any one of the five compilation phases that that
|
|
<tt>llvmc</tt> supports. The five phases are:
|
|
<a href="#def_preprocessing">preprocessing</a>,
|
|
<a href="#def_translation">translation</a>,
|
|
<a href="#def_optimization">optimization</a>,
|
|
<a href="#def_assembly">assembly</a>,
|
|
<a href="#def_linking">linking</a>.</dd>
|
|
|
|
<dt><a name="def_sourcelanguage"><b>source language</b></a></dt>
|
|
<dd>Any common programming language (e.g. C, C++, Java, Stacker, ML,
|
|
FORTRAN). These languages are distinguished from any of the lower level
|
|
languages (such as LLVM or native assembly), by the fact that a
|
|
<a href="#def_translation">translation</a> <a href="#def_phase">phase</a>
|
|
is required before LLVM can be applied.</dd>
|
|
|
|
<dt><a name="def_tool"><b>tool</b></a></dt>
|
|
<dd>Refers to any program in the LLVM tool set.</dd>
|
|
|
|
<dt><a name="def_translation"><b>translation</b></a></dt>
|
|
<dd>A compilation <a href="#def_phase">phase</a> in which
|
|
<a href="#def_sourcelanguage">source language</a> code is translated into
|
|
either LLVM assembly language or LLVM bytecode.</dd>
|
|
</dl>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
<hr>
|
|
<address> <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a><a
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href="http://validator.w3.org/check/referer"><img
|
|
src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a><a
|
|
href="mailto:rspencer@x10sys.com">Reid Spencer</a><br>
|
|
<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
|
|
Last modified: $Date$
|
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</address>
|
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