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| author | mike-m <mikem.llvm@gmail.com> | 2010-05-06 23:45:43 +0000 |
|---|---|---|
| committer | mike-m <mikem.llvm@gmail.com> | 2010-05-06 23:45:43 +0000 |
| commit | 68cb31901c590cabceee6e6356d62c84142114cb (patch) | |
| tree | 6444bddc975b662fbe47d63cd98a7b776a407c1a /docs/GoldPlugin.html | |
| parent | c26ae5ab7e2d65b67c97524e66f50ce86445dec7 (diff) | |
| download | external_llvm-68cb31901c590cabceee6e6356d62c84142114cb.zip external_llvm-68cb31901c590cabceee6e6356d62c84142114cb.tar.gz external_llvm-68cb31901c590cabceee6e6356d62c84142114cb.tar.bz2 | |
Overhauled llvm/clang docs builds. Closes PR6613.
NOTE: 2nd part changeset for cfe trunk to follow.
*** PRE-PATCH ISSUES ADDRESSED
- clang api docs fail build from objdir
- clang/llvm api docs collide in install PREFIX/
- clang/llvm main docs collide in install
- clang/llvm main docs have full of hard coded destination
assumptions and make use of absolute root in static html files;
namely CommandGuide tools hard codes a website destination
for cross references and some html cross references assume
website root paths
*** IMPROVEMENTS
- bumped Doxygen from 1.4.x -> 1.6.3
- splits llvm/clang docs into 'main' and 'api' (doxygen) build trees
- provide consistent, reliable doc builds for both main+api docs
- support buid vs. install vs. website intentions
- support objdir builds
- document targets with 'make help'
- correct clean and uninstall operations
- use recursive dir delete only where absolutely necessary
- added call function fn.RMRF which safeguards against botched 'rm -rf';
if any target (or any variable is evaluated) which attempts
to remove any dirs which match a hard-coded 'safelist', a verbose
error will be printed and make will error-stop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103213 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/GoldPlugin.html')
| -rw-r--r-- | docs/GoldPlugin.html | 213 |
1 files changed, 0 insertions, 213 deletions
diff --git a/docs/GoldPlugin.html b/docs/GoldPlugin.html deleted file mode 100644 index 66e099b..0000000 --- a/docs/GoldPlugin.html +++ /dev/null @@ -1,213 +0,0 @@ -<!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> - <ul> - <li><a href="#example1">Example of link time optimization</a></li> - <li><a href="#lto_autotools">Quickstart for using LTO with autotooled projects</a></li> - </ul></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 from the -system linker. LTO support on Linux systems requires that you use -the <a href="http://sourceware.org/binutils">gold linker</a> which supports -LTO via plugins. This is the same mechanism used by the -<a href="http://gcc.gnu.org/wiki/LinkTimeOptimization">GCC LTO</a> -project.</p> - <p>The LLVM gold plugin implements the -<a href="http://gcc.gnu.org/wiki/whopr/driver">gold 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 have gold with plugin support and build the LLVMgold -plugin. Check whether you have gold running <tt>/usr/bin/ld -v</tt>. It will -report “GNU gold” or else “GNU ld” if not. If you have -gold, check for plugin support by running <tt>/usr/bin/ld -plugin</tt>. If it -complains “missing argument” then you have plugin support. If not, -such as an “unknown option” error then you will either need to -build gold or install a version with plugin support.</p> -<ul> - <li>To 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 <tt>binutils/build/gold/ld-new</tt> which supports the <tt>-plugin</tt> option. It also built would have -<tt>binutils/build/binutils/ar</tt> and <tt>nm-new</tt> which support plugins -but don't have a visible -plugin option, instead relying on the gold plugin -being present in <tt>../lib/bfd-plugins</tt> relative to where the binaries are -placed. - <li>Build the LLVMgold plugin: 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/libLLVMgold.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 the <tt>-O4</tt> flag which is - synonymous with <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> and - passes the <tt>-plugin</tt> option to ld. It will not look for an alternate - linker, which is why you need gold to be the installed system linker in your - path.</p> - <p>If you want <tt>ar</tt> and <tt>nm</tt> to work seamlessly as well, install - <tt>libLLVMgold.so</tt> to <tt>/usr/lib/bfd-plugins</tt>. If you built your - own gold, be sure to install the <tt>ar</tt> and <tt>nm-new</tt> you built to - <tt>/usr/bin</tt>. - <p> -</div> - -<!-- ======================================================================= --> -<div class="doc_subsection"> - <a name="example1">Example of link time optimization</a> -</div> - -<div class="doc_text"> - <p>The following example shows a worked example of the gold plugin mixing - LLVM bitcode and native code. -<pre class="doc_code"> ---- a.c --- -#include <stdio.h> - -extern void foo1(void); -extern void foo4(void); - -void foo2(void) { - printf("Foo2\n"); -} - -void foo3(void) { - foo4(); -} - -int main(void) { - foo1(); -} - ---- b.c --- -#include <stdio.h> - -extern void foo2(void); - -void foo1(void) { - foo2(); -} - -void foo4(void) { - printf("Foo4"); -} - ---- command lines --- -$ llvm-gcc -flto a.c -c -o a.o # <-- a.o is LLVM bitcode file -$ ar q a.a a.o # <-- a.a is an archive with LLVM bitcode -$ llvm-gcc b.c -c -o b.o # <-- b.o is native object file -$ llvm-gcc -use-gold-plugin a.a b.o -o main # <-- link with LLVMgold plugin -</pre> - <p>Gold informs the plugin that foo3 is never referenced outside the IR, - leading LLVM to delete that function. However, unlike in the - <a href="http://llvm.org/docs/LinkTimeOptimization.html#example1">libLTO - example</a> gold does not currently eliminate foo4.</p> -</div> - -<!--=========================================================================--> -<div class="doc_section"><a name="lto_autotools">Quickstart for using LTO with autotooled projects</a></div> -<!--=========================================================================--> -<div class="doc_text"> - <p>Once your system <tt>ld</tt>, <tt>ar</tt> and <tt>nm</tt> all support LLVM - bitcode, everything is in place for an easy to use LTO build of autotooled - projects:</p> - <ul> - <li>Follow the instructions <a href="#build">on how to build libLLVMgold.so</a>.</li> - <li>Install the newly built binutils to <tt>$PREFIX</tt></li> - <li>Copy <tt>Release/lib/libLLVMgold.so</tt> to - <tt>$PREFIX/libexec/gcc/x86_64-unknown-linux-gnu/4.2.1/</tt> and - <tt>$PREFIX/lib/bfd-plugins/</tt></li> - <li>Set environment variables (<tt>$PREFIX</tt> is where you installed llvm-gcc and - binutils): - <pre class="doc_code"> -export CC="$PREFIX/bin/llvm-gcc -use-gold-plugin" -export CXX="$PREFIX/bin/llvm-g++ -use-gold-plugin" -export AR="$PREFIX/bin/ar" -export NM="$PREFIX/bin/nm" -export RANLIB=/bin/true #ranlib is not needed, and doesn't support .bc files in .a -export CFLAGS="-O4" -</pre> - </li> - <li>Or you can just set your path: - <pre class="doc_code"> -export PATH="$PREFIX/bin:$PATH" -export CC="llvm-gcc -use-gold-plugin" -export CXX="llvm-g++ -use-gold-plugin" -export RANLIB=/bin/true -export CFLAGS="-O4" -</pre> - </li> - <li>Configure & build the project as usual: <tt>./configure && make && make check</tt> </li> - </ul> - <p> The environment variable settings may work for non-autotooled projects - too, but you may need to set the <tt>LD</tt> environment variable as well.</p> -</div> - -<!--=========================================================================--> -<div class="doc_section"><a name="licensing">Licensing</a></div> -<!--=========================================================================--> -<div class="doc_text"> - <p>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.</p> -</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> - <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: 2010-04-16 23:58:21 -0800 (Fri, 16 Apr 2010) $ -</address> -</body> -</html> |