# Windows support

LLD supports Windows operating system. When invoked as `lld-link.exe` or with `-flavor link`, the driver for Windows operating system is used to parse command line options, and it drives further linking processes. LLD accepts almost all command line options that the linker shipped with Microsoft Visual C++ (link.exe) supports.

The current status is that LLD can link itself on Windows x86/x64 using Visual C++ 2013 as the compiler.

## Development status

Driver
  Mostly done. Some exotic command line options that are not usually used for application develompent, such as `/DRIVER`, are not supported. Options for Windows 8 app store are not recognized too (e.g. `/APPCONTAINER`).
Linking against DLL
  Done. LLD can read import libraries needed to link against DLL. Both export-by-name and export-by-ordinal are supported.
Linking against static library
  Done. The format of static library (.lib) on Windows is actually the same as on Unix (.a). LLD can read it.
Creating DLL
  Done. LLD creates a DLL if `/DLL` option is given. Exported functions can be specified either via command line (`/EXPORT`) or via module-definition file (.def). Both export-by-name and export-by-ordinal are supported. LLD uses Microsoft `lib.exe` tool to create an import library file.
Windows resource files support
  Done. If an `.rc` file is given, LLD converts the file to a COFF file using some external commands and link it. Specifically, `rc.exe` is used to compile a resource file (.rc) to a compiled resource (.res) file. `rescvt.exe` is then used to convert a compiled resource file to a COFF object file section. Both tools are shipped with MSVC.
Safe Structured Exception Handler (SEH)
  Done for both x86 and x64.
Module-definition file
  Partially done. LLD currently recognizes these directives: `EXPORTS`, `HEAPSIZE`, `STACKSIZE`, `NAME`, and `VERSION`.
Debug info
  No progress has been made. Microsoft linker can interpret the CodeGen debug info (old-style debug info) and PDB to emit an .pdb file. LLD doesn’t support neither.

## Building LLD

### Using Visual Studio IDE/MSBuild

1. Check out LLVM and LLD from the LLVM SVN repository (or Git mirror),
2. run `cmake -G "Visual Studio 12" <llvm-source-dir>` from VS command prompt,
3. open LLVM.sln with Visual Studio, and
4. build `lld` target in `lld executables` folder

Alternatively, you can use msbuild if you don’t like to work in an IDE:

    msbuild LLVM.sln /m /target:"lld executables\lld"

MSBuild.exe had been shipped as a component of the .NET framework, but since 2013 it’s part of Visual Studio. You can find it at “C:\Program Files (x86)\msbuild”.

You can build LLD as a 64 bit application. To do that, open VS2013 x64 command prompt and run cmake for “Visual Studio 12 Win64” target.

### Using Ninja

1. Check out LLVM and LLD from the LLVM SVN repository (or Git mirror),
2. run `cmake -G ninja <llvm-source-dir>` from VS command prompt,
3. run `ninja lld`