llvm/docs/GoldPlugin.html - toolchain/llvm-project - Gitiles

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   <title>LLVM gold plugin</title>
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 <div class="doc_title">LLVM gold plugin</div>
 <ol>
   <li><a href="#introduction">Introduction</a></li>
   <li><a href="#build">How to build it</a></li>
   <li><a href="#usage">Usage</a></li>
   <li><a href="#licensing">Licensing</a></li>
 </ol>
 <div class="doc_author">Written by Nick Lewycky</div>

 <!--=========================================================================-->
 <div class="doc_section"><a name="introduction">Introduction</a></div>
 <!--=========================================================================-->
 <div class="doc_text">
   <p>Building with link time optimization requires cooperation with the
 system linker. LTO support on Linux systems requires that you use
 <a href="http://sourceware.org/binutils">gold</a> which supports for
 LTO via plugins. This is the same system used by the upcoming
 <a href="http://gcc.gnu.org/wiki/LinkTimeOptimization">GCC LTO</a>
 support.</p>
   <p>The LLVMgold plugin implements the gold
 <a href="http://gcc.gnu.org/wiki/whopr/driver">plugin interface</a> on
 top of
 <a href="http://llvm.org/docs/LinkTimeOptimization.html#lto">libLTO</a>.
 The same plugin can also be used by other tools such as <tt>ar</tt> and
 <tt>nm</tt>.
 </div>
 <!--=========================================================================-->
 <div class="doc_section"><a name="build">How to build it</a></div>
 <!--=========================================================================-->
 <div class="doc_text">
   <p>You need to build gold with plugin support and build the LLVMgold
 plugin.</p>
 <ul>
   <li>Build gold with plugin support:
     <pre class="doc_code">
 mkdir binutils
 cd binutils
 cvs -z 9 -d :pserver:anoncvs@sourceware.org:/cvs/src login
 <em>{enter "anoncvs" as the password}</em>
 cvs -z 9 -d :pserver:anoncvs@sourceware.org:/cvs/src co src
 mkdir build
 cd build
 ../src/configure --enable-gold --enable-plugins
 make all-gold
 </pre>
     That should leave you with binutils/build/gold/ld-new which supports the
 -plugin option.

     <li>Build LLVMgold. Configure LLVM with
     <tt>--with-binutils-include=/path/to/binutils/src/include</tt> and run
     <tt>make</tt>.
 </ul>
 </div>
 <!--=========================================================================-->
 <div class="doc_section"><a name="usage">Usage</a></div>
 <!--=========================================================================-->
 <div class="doc_text">
   <p>The linker takes a <tt>-plugin</tt> option that points to the path of
   the plugin <tt>.so</tt> file. To find out what link command <tt>gcc</tt>
   would run in a given situation, run <tt>gcc -v <em>[...]</em></tt> and look
   for the line where it runs <tt>collect2</tt>. Replace that with
   <tt>ld-new -plugin /path/to/LLVMgold.so</tt> to test it out. Once you're
   ready to switch to using gold, backup your existing <tt>/usr/bin/ld</tt>
   then replace it with <tt>ld-new</tt>.</p>
   <p>You can produce bitcode files from <tt>llvm-gcc</tt> using
   <tt>-emit-llvm</tt> or <tt>-flto</tt> or <tt>-O4</tt> which is equivalent
   to <tt>-O3 -flto</tt>.</p>
   <p><tt>llvm-gcc</tt> has a <tt>-use-gold-plugin</tt> option which looks
   for the gold plugin in the same directories as it looks for <tt>cc1</tt>.
   It will not look for an alternate linker, which is why you need gold to be
   the installed system linker in your path.</p>
 </div>
 <!--=========================================================================-->
 <div class="doc_section"><a name="licensing">Licensing</a></div>
 <!--=========================================================================-->
 <div class="doc_text">
 Gold is licensed under the GPLv3. LLVMgold uses the interface file
 <tt>plugin-api.h</tt> from gold which means that the resulting LLVMgold.so
 binary is also GPLv3. This can still be used to link non-GPLv3 programs just
 as much as gold could without the plugin.
 </div>

 <!-- *********************************************************************** -->
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   Written by the
   <a href="mailto:nicholas@metrix.on.ca">Nick Lewycky</a><br>
   <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
   Last modified: $Date: 2009-01-01 23:10:51 -0800 (Thu, 01 Jan 2009) $
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	<html>
	<head>
	<title>LLVM gold plugin</title>
	<link rel="stylesheet" href="llvm.css" type="text/css">
	</head>
	<body>

	<div class="doc_title">LLVM gold plugin</div>
	<ol>
	<li><a href="#introduction">Introduction</a></li>
	<li><a href="#build">How to build it</a></li>
	<li><a href="#usage">Usage</a></li>
	<li><a href="#licensing">Licensing</a></li>
	</ol>
	<div class="doc_author">Written by Nick Lewycky</div>

	<!--=========================================================================-->
	<div class="doc_section"><a name="introduction">Introduction</a></div>
	<!--=========================================================================-->
	<div class="doc_text">
	<p>Building with link time optimization requires cooperation with the
	system linker. LTO support on Linux systems requires that you use
	<a href="http://sourceware.org/binutils">gold</a> which supports for
	LTO via plugins. This is the same system used by the upcoming
	<a href="http://gcc.gnu.org/wiki/LinkTimeOptimization">GCC LTO</a>
	support.</p>
	<p>The LLVMgold plugin implements the gold
	<a href="http://gcc.gnu.org/wiki/whopr/driver">plugin interface</a> on
	top of
	<a href="http://llvm.org/docs/LinkTimeOptimization.html#lto">libLTO</a>.
	The same plugin can also be used by other tools such as <tt>ar</tt> and
	<tt>nm</tt>.
	</div>
	<!--=========================================================================-->
	<div class="doc_section"><a name="build">How to build it</a></div>
	<!--=========================================================================-->
	<div class="doc_text">
	<p>You need to build gold with plugin support and build the LLVMgold
	plugin.</p>
	<ul>
	<li>Build gold with plugin support:
	<pre class="doc_code">
	mkdir binutils
	cd binutils
	cvs -z 9 -d :pserver:anoncvs@sourceware.org:/cvs/src login
	<em>{enter "anoncvs" as the password}</em>
	cvs -z 9 -d :pserver:anoncvs@sourceware.org:/cvs/src co src
	mkdir build
	cd build
	../src/configure --enable-gold --enable-plugins
	make all-gold
	</pre>
	That should leave you with binutils/build/gold/ld-new which supports the
	-plugin option.

	<li>Build LLVMgold. Configure LLVM with
	<tt>--with-binutils-include=/path/to/binutils/src/include</tt> and run
	<tt>make</tt>.
	</ul>
	</div>
	<!--=========================================================================-->
	<div class="doc_section"><a name="usage">Usage</a></div>
	<!--=========================================================================-->
	<div class="doc_text">
	<p>The linker takes a <tt>-plugin</tt> option that points to the path of
	the plugin <tt>.so</tt> file. To find out what link command <tt>gcc</tt>
	would run in a given situation, run <tt>gcc -v <em>[...]</em></tt> and look
	for the line where it runs <tt>collect2</tt>. Replace that with
	<tt>ld-new -plugin /path/to/LLVMgold.so</tt> to test it out. Once you're
	ready to switch to using gold, backup your existing <tt>/usr/bin/ld</tt>
	then replace it with <tt>ld-new</tt>.</p>
	<p>You can produce bitcode files from <tt>llvm-gcc</tt> using
	<tt>-emit-llvm</tt> or <tt>-flto</tt> or <tt>-O4</tt> which is equivalent
	to <tt>-O3 -flto</tt>.</p>
	<p><tt>llvm-gcc</tt> has a <tt>-use-gold-plugin</tt> option which looks
	for the gold plugin in the same directories as it looks for <tt>cc1</tt>.
	It will not look for an alternate linker, which is why you need gold to be
	the installed system linker in your path.</p>
	</div>
	<!--=========================================================================-->
	<div class="doc_section"><a name="licensing">Licensing</a></div>
	<!--=========================================================================-->
	<div class="doc_text">
	Gold is licensed under the GPLv3. LLVMgold uses the interface file
	<tt>plugin-api.h</tt> from gold which means that the resulting LLVMgold.so
	binary is also GPLv3. This can still be used to link non-GPLv3 programs just
	as much as gold could without the plugin.
	</div>

	<!-- *********************************************************************** -->
	<hr>
	<address>
	<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
	src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
	<a href="http://validator.w3.org/check/referer"><img
	src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
	Written by the
	<a href="mailto:nicholas@metrix.on.ca">Nick Lewycky</a><br>
	<a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
	Last modified: $Date: 2009-01-01 23:10:51 -0800 (Thu, 01 Jan 2009) $
	</address>
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