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13===============
14Windows support
15===============
16
17LLD supports Windows operating system. When invoked as ``lld-link.exe`` or with
18``-flavor link``, the driver for Windows operating system is used to parse
19command line options, and it drives further linking processes. LLD accepts
20almost all command line options that the linker shipped with Microsoft Visual
21C++ (link.exe) supports.
22
23The current status is that LLD is used to link production builds of large
24real-world binaries such as Firefox and Chromium.
25
26Development status
27==================
28
29Driver
30  :good:`Mostly done`. Some exotic command line options that are not usually
31  used for application development, such as ``/DRIVER``, are not supported.
32
33Linking against DLL
34  :good:`Done`. LLD can read import libraries needed to link against DLL. Both
35  export-by-name and export-by-ordinal are supported.
36
37Linking against static library
38  :good:`Done`. The format of static library (.lib) on Windows is actually the
39  same as on Unix (.a). LLD can read it.
40
41Creating DLL
42  :good:`Done`. LLD creates a DLL if ``/DLL`` option is given. Exported
43  functions can be specified either via command line (``/EXPORT``) or via
44  module-definition file (.def). Both export-by-name and export-by-ordinal are
45  supported.
46
47Windows resource files support
48  :good:`Done`. If an ``.res`` file is given, LLD converts the file to a COFF
49  file using LLVM's Object library.
50
51Safe Structured Exception Handler (SEH)
52  :good:`Done` for both x86 and x64.
53
54Module-definition file
55  :partial:`Partially done`. LLD currently recognizes these directives:
56  ``EXPORTS``, ``HEAPSIZE``, ``STACKSIZE``, ``NAME``, and ``VERSION``.
57
58Debug info
59  :good:`Done`.  LLD can emit PDBs that are at parity with those generated by
60  link.exe.  However, LLD does not support /DEBUG:FASTLINK.
61
62
63Downloading LLD
64===============
65
66The Windows version of LLD is included in the `pre-built binaries of LLVM's
67releases <https://releases.llvm.org/download.html>`_ and in the `LLVM Snapshot
68Builds <https://llvm.org/builds/>`_.
69
70Building LLD
71============
72
73Using Visual Studio IDE/MSBuild
74-------------------------------
75
761. Check out LLVM and LLD from the LLVM SVN repository (or Git mirror),
77#. run ``cmake -G "Visual Studio 12" <llvm-source-dir>`` from VS command prompt,
78#. open LLVM.sln with Visual Studio, and
79#. build ``lld`` target in ``lld executables`` folder
80
81Alternatively, you can use msbuild if you don't like to work in an IDE::
82
83  msbuild LLVM.sln /m /target:"lld executables\lld"
84
85MSBuild.exe had been shipped as a component of the .NET framework, but since
862013 it's part of Visual Studio. You can find it at "C:\\Program Files
87(x86)\\msbuild".
88
89You can build LLD as a 64 bit application. To do that, open VS2013 x64 command
90prompt and run cmake for "Visual Studio 12 Win64" target.
91
92Using Ninja
93-----------
94
951. Check out LLVM and LLD from the LLVM SVN repository (or Git mirror),
96#. run ``cmake -G ninja <llvm-source-dir>`` from VS command prompt,
97#. run ``ninja lld``
98
99Extensions
100==========
101
102LLD flags
103---------
104
105* ``/build-id``: Always generate GUID hash. When PDB is generated, LLD uses PDB
106  content hash for GUID. Otherwise, LLD uses output binary content hash for GUID.
107  LLD also provides ``__buildid`` symbol pointing to the 16 bytes GUID hash if
108  there is a reference to it.
109