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How to use OpenBLAS in Microsoft Visual Studio

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Tyler edited this page Mar 10, 2017 · 71 revisions

As of OpenBLAS v0.2.15, we support MinGW and Visual Studio (using CMake to generate visual studio solution files) to build OpenBLAS on Windows.

##1. MinGW

The resulting library can be used in Visual Studio, but it can only be linked dynamically. This configuration has not been thoroughly tested and should be considered experimental.

Incompatible x86 calling conventions

Due to incompatibilities between the calling conventions of MinGW and Visual Studio you will need to make the following modifications ( 32-bit only ):

  1. Use the newer GCC 4.7.0. The older GCC (<4.7.0) has an ABI incompatibility for returning aggregate structures larger than 8 bytes with MSVC.

Build OpenBLAS on Windows OS

  1. Install the MinGW (GCC) compiler suite, either 32-bit (http://www.mingw.org/) or 64-bit (http://mingw-w64.sourceforge.net/). In addition, please install MSYS with MinGW.
  2. Build OpenBLAS in the MSYS shell. Usually, you can just type "make". OpenBLAS will detect the compiler and CPU automatically.
  3. After the build is complete, OpenBLAS will generate the static library "libopenblas.a" and the shared dll library "libopenblas.dll" in the folder. You can type "make PREFIX=/your/installation/path install" to install the library to a certain location.

[Notice] We suggest using official MingWin or MingWin-w64 compilers. A user reported that s/he met Unhandled exception by other compiler suite. https://groups.google.com/forum/#!topic/openblas-users/me2S4LkE55w

Generate import library (before 0.2.10 version)

  1. First, you will need to have the lib.exe tool in the Visual Studio command prompt.
  2. Open the command prompt and type cd OPENBLAS_TOP_DIR/exports, where OPENBLAS_TOP_DIR is the main folder of your OpenBLAS installation.
  3. For a 32-bit library, type lib /machine:i386 /def:libopenblas.def. For 64-bit, type lib /machine:X64 /def:libopenblas.def.
  4. This will generate the import library "libopenblas.lib" and the export library "libopenblas.exp" in OPENBLAS_TOP_DIR/exports. Although these two files have the same name, they are totally different.

Generate import library (0.2.10 and after version)

  1. OpenBLAS already generated the import library "libopenblas.dll.a" for "libopenblas.dll".

Use OpenBLAS .dll library in Visual Studio

  1. Copy the import library (before 0.2.10: "OPENBLAS_TOP_DIR/exports/libopenblas.lib", 0.2.10 and after: "OPENBLAS_TOP_DIR/libopenblas.dll.a") and .dll library "libopenblas.dll" into the same folder(The folder of your project that is going to use the BLAS library. You may need to add the libopenblas.dll.a to the linker input list: properties->Linker->Input).
  2. Please follow the documentation about using third-party .dll libraries in MS Visual Studio 2008 or 2010. Make sure to link against a library for the correct architecture. For example, you may receive an error such as "The application was unable to start correctly (0xc000007b)" which typically indicates a mismatch between 32/64-bit libraries.

[Notice] If you need CBLAS, you should include cblas.h in /your/installation/path/include in Visual Studio. Please read this page.

Limitations

  • Both static and dynamic linking are supported with MinGW. With Visual Studio, however, only dynamic linking is supported and so you should use the import library.
  • Debugging from Visual Studio does not work because MinGW and Visual Studio have incompatible formats for debug information (PDB vs. DWARF/STABS). You should either debug with GDB on the command-line or with a visual frontend, for instance Eclipse or Qt Creator.

##2. CMake and Visual Studio

Since OpenBLAS 0.2.15 version, we support CMake experimentally. The user can use CMake at Windows, Linux, or Mac OSX. For Windows, we tested the library with Visual Studio 2012 and 2013.

[Notice] Because Visual Studio cannot recognize AT&T assembly language, OpenBLAS only uses the C kernels for Visual Studio native build. Thus, the performance is not good compared to MinGW build.

##1. Install CMake at Windows ##2. Use CMake to generate Visual Studio solution files

# do this from powershell so cmake can find visual studio
cmake -G "Visual Studio 14 Win64" .

##3. Build the solution at Visual Studio

Note that this step depends on perl, so you'll need to install perl for windows, and put perl on your path so VS can start perl (http://stackoverflow.com/questions/3051049/active-perl-installation-on-windows-operating-system).

Step 2 will build the OpenBLAS solution, open it in VS, and build the projects. Note that the dependencies do not seem to be automatically configured: if you try to build libopenblas directly, it will fail with a message saying that some .obj files aren't found, but if you build the projects libopenblas depends on before building libopenblas, the build will succeed.

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