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Document common linkage. 

llvm-svn: 51517
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Dale Johannesen 2008-05-23 23:13:41 +00:00
parent 78f37e6d28
commit 4188aadbb2
1 changed files with 15 additions and 7 deletions
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22
llvm/docs/LangRef.html
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@ -466,7 +466,7 @@ All Global Variables and Functions have one of the following types of linkage:
<dl>
<dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
<dt><tt><b><a name="linkage_internal">internal</a></b></tt>: </dt>
<dd>Global values with internal linkage are only directly accessible by
objects in the current module. In particular, linking code into a module with
@ -485,14 +485,22 @@ All Global Variables and Functions have one of the following types of linkage:
allowed to be discarded.
</dd>
<dt><tt><b><a name="linkage_common">common</a></b></tt>: </dt>
<dd>"<tt>common</tt>" linkage is exactly the same as <tt>linkonce</tt>
linkage, except that unreferenced <tt>common</tt> globals may not be
discarded. This is used for globals that may be emitted in multiple
translation units, but that are not guaranteed to be emitted into every
translation unit that uses them. One example of this is tentative
definitions in C, such as "<tt>int X;</tt>" at global scope.
</dd>
<dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
<dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
except that unreferenced <tt>weak</tt> globals may not be discarded. This is
used for globals that may be emitted in multiple translation units, but that
are not guaranteed to be emitted into every translation unit that uses them.
One example of this are common globals in C, such as "<tt>int X;</tt>" at
global scope.
<dd>"<tt>weak</tt>" linkage is the same as <tt>common</tt> linkage, except
that some targets may choose to emit different assembly sequences for them
for target-dependent reasons. This is used for globals that are declared
"weak" in C source code.
</dd>
<dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>