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Add a quickstart example.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65789 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2009-03-01 21:55:10 +00:00
parent f45a82890e
commit f3888ba23f
1 changed files with 56 additions and 1 deletions
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docs/GoldPlugin.html
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@ -11,7 +11,10 @@
<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="#usage">Usage</a>
<ul>
<li><a href="#example1">Example of link time optimization</a></li>
</ul></li>
<li><a href="#licensing">Licensing</a></li>
</ol>
<div class="doc_author">Written by Nick Lewycky</div>
@ -80,6 +83,58 @@ make all-gold
linker, which is why you need gold to be the installed system linker in your
path.</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 &lt;stdio.h&gt;
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 &lt;stdio.h&gt;
extern void foo2(void);
void foo1(void) {
foo2();
}
void foo4(void) {
printf("Foo4");
}
--- command lines ---
$ llvm-gcc -flto a.c -c -o a.o # &lt;-- a.o is LLVM bitcode file
$ llvm-gcc b.c -c -o b.o # &lt;-- b.o is native object file
$ llvm-gcc -use-gold-plugin a.o b.o -o main # &lt;-- 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="licensing">Licensing</a></div>
<!--=========================================================================-->