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| author | Chris Lattner <sabre@nondot.org> | 2009-08-05 05:21:07 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2009-08-05 05:21:07 +0000 |
| commit | 26d054d903488d956c23a17d78b6bc8cbd9553cb (patch) | |
| tree | 6b4c81395f4dab5e0e31865699f082c693c68d6e /docs | |
| parent | 831f6f6d2ae5a1ad988c8328404b052b7985ce31 (diff) | |
| download | llvm-26d054d903488d956c23a17d78b6bc8cbd9553cb.tar.gz llvm-26d054d903488d956c23a17d78b6bc8cbd9553cb.tar.bz2 llvm-26d054d903488d956c23a17d78b6bc8cbd9553cb.tar.xz | |
Clarify common linkage and the requirements on it. Enforce
them in the verifier.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78160 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/LangRef.html | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/docs/LangRef.html b/docs/LangRef.html index 33fc7d4ff6..52ec97888d 100644 --- a/docs/LangRef.html +++ b/docs/LangRef.html @@ -552,19 +552,22 @@ define i32 @main() { <i>; i32()* </ translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are allowed to be discarded.</dd> + <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt> + <dd>"<tt>weak</tt>" linkage has the same merging semantics as + <tt>linkonce</tt> linkage, except that unreferenced globals with + <tt>weak</tt> linkage may not be discarded. This is used for globals that + are declared "weak" in C source code.</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> + <dd>"<tt>common</tt>" linkage is most similar to "<tt>weak</tt>" linkage, but + they are used for tentative definitions in C, such as "<tt>int X;</tt>" at + global scope. + Symbols with "<tt>common</tt>" linkage are merged in the same way as + <tt>weak symbols</tt>, and they may not be deleted if unreferenced. + Further, <tt>common</tt> symbols may not have an explicit section, and + must have a zero initializer. Functions and aliases may not have common + linkage.</dd> - <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt> - <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> <dd>"<tt>appending</tt>" linkage may only be applied to global variables of |