MC: Implement COFF .linkonce directive
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185753 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/Extensions.rst b/docs/Extensions.rst
index 062804a..78ff874 100644
--- a/docs/Extensions.rst
+++ b/docs/Extensions.rst
@@ -4,7 +4,6 @@
.. contents::
:local:
- :depth: 1
.. toctree::
:hidden:
@@ -21,6 +20,9 @@
X86/COFF-Dependent
------------------
+Relocations
+^^^^^^^^^^^
+
The following additional relocation type is supported:
**@IMGREL** (AT&T syntax only) generates an image-relative relocation that
@@ -37,3 +39,55 @@
.long fun@IMGREL
.long (fun@imgrel + 0x3F)
.long $unwind$fun@imgrel
+
+
+``.linkonce`` Directive
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+
+ ``.linkonce [ comdat type [ section identifier ] ]``
+
+Supported COMDAT types:
+
+``discard``
+ Discards duplicate sections with the same COMDAT symbol. This is the default
+ if no type is specified.
+
+``one_only``
+ If the symbol is defined multiple times, the linker issues an error.
+
+``same_size``
+ Duplicates are discarded, but the linker issues an error if any have
+ different sizes.
+
+``same_contents``
+ Duplicates are discarded, but the linker issues an error if any duplicates
+ do not have exactly the same content.
+
+``associative``
+ Links the section if a certain other COMDAT section is linked. This other
+ section is indicated by its section identifier following the comdat type.
+ The following restrictions apply to the associated section:
+
+ 1. It must be the name of a section already defined.
+ 2. It must differ from the current section.
+ 3. It must be a COMDAT section.
+ 4. It cannot be another associative COMDAT section.
+
+``largest``
+ Links the largest section from among the duplicates.
+
+``newest``
+ Links the newest section from among the duplicates.
+
+
+.. code-block:: gas
+
+ .section .text$foo
+ .linkonce
+ ...
+
+ .section .xdata$foo
+ .linkonce associative .text$foo
+ ...