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| author | Nick Lewycky <nicholas@mxc.ca> | 2009-03-01 09:38:29 +0000 |
|---|---|---|
| committer | Nick Lewycky <nicholas@mxc.ca> | 2009-03-01 09:38:29 +0000 |
| commit | dc600fa01abc133795e9b1dc37196318e4463e4c (patch) | |
| tree | 6f2db43804e8d69a24a615f9b51d024af64004e7 | |
| parent | 942eecefc9f218916b390979a80eda8f19c08c64 (diff) | |
| download | external_llvm-dc600fa01abc133795e9b1dc37196318e4463e4c.zip external_llvm-dc600fa01abc133795e9b1dc37196318e4463e4c.tar.gz external_llvm-dc600fa01abc133795e9b1dc37196318e4463e4c.tar.bz2 | |
First pass at a document describing how to achieve LTO on Linux with gold.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65766 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | docs/GoldPlugin.html | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/docs/GoldPlugin.html b/docs/GoldPlugin.html new file mode 100644 index 0000000..2808dfa --- /dev/null +++ b/docs/GoldPlugin.html @@ -0,0 +1,105 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" + "http://www.w3.org/TR/html4/strict.dtd"> +<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. To support LTO on Linux systems, we requires that you use +<a href="http://sourceware.org/binutils">gold</a> which has support 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> +</body> +</html> |