[LLVMdev] Host target triple on Windows

[Zachary Turner]

What version of CMake are you using?  If it's 3.0, then it's possible that
they've gotten smarter.  I'm using 2.8, and I confirmed that even with an
empty directory, CMAKE_CL_64 in GetHostTriple() is never set regardless of
which toolchain is in use.


On Wed, Jul 30, 2014 at 10:22 AM, Hans Wennborg <hans at chromium.org> wrote:

> On Tue, Jul 29, 2014 at 5:38 PM, Zachary Turner <zturner at google.com>
> wrote:
> > I'm trying to figure out how to get, from CMake, the architecture of the
> > platform that I'm compiling LLVM for.  If I'm building LLVM on x86, I
> want
> > x86.  On x64 I want x86_64.  On arm arm.  etc.
> >
> > The best I can figure out so far is that I should use LLVM_HOST_TRIPLE,
> and
> > extract the first component of this.  At least if my understanding is
> > correct, I should have the following behavior:
> >
> > Compiling using 32-bit toolchain on Windows: LLVM_HOST_TRIPLE =
> > i686-pc-win32
> > Compiling using 64-bit toolchain on Windows: LLVM_HOST_TRIPLE =
> > x86_64-pc-win32
> >
> > This doesn't currently seem to work.  See, for example, the following
> output
> > from when I run CMake twice from the command line, once with an x86
> > toolchain and once with an x64 toolchain:
> >
> > D:\src\llvm\build\ninja>"c:\Program Files (x86)\Microsoft Visual Studio
> > 12.0\VC\vcvarsall.bat" x86
> >
> > D:\src\llvm\build\ninja>where cl
> > C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\cl.exe
> > C:\Program Files (x86)\Microsoft Visual Studio
> 12.0\VC\bin\x86_amd64\cl.exe
> >
> > D:\src\llvm\build\ninja>cmake ..\..
> > -- Target triple: i686-pc-win32
> > -- Native target architecture is X86
> >
> > D:\src\llvm\build\ninja>"c:\Program Files (x86)\Microsoft Visual Studio
> > 12.0\VC\vcvarsall.bat" x86_amd64
> >
> > D:\src\llvm\build\ninja>where cl
> > C:\Program Files (x86)\Microsoft Visual Studio
> 12.0\VC\bin\x86_amd64\cl.exe
> > C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\cl.exe
> >
> > D:\src\llvm\build\ninja>cmake ..\..
> > -- Target triple: i686-pc-win32
> > -- Native target architecture is X86
>
> Could this be due to CMake caching (and not updating that cache) the
> compiler it uses? If I run cmake in an empty directory, it seems to
> get the Target triple right:
>
> D:\src>mkdir build.x86 && cd build.x86
> D:\src\build.x86>"c:\Program Files (x86)\Microsoft Visual Studio
> 12.0\VC\vcvarsall.bat" x86
> D:\src\build.x86>cmake -GNinja ..\llvm
> [...]
> -- Target triple: i686-pc-win32
> -- Native target architecture is X86
>
> D:\src\build.x86>cd .. && mkdir build.amd64 && cd build.amd64
> D:\src\build.amd64>"c:\Program Files (x86)\Microsoft Visual Studio
> 12.0\VC\vcvarsall.bat" x86_amd64
> D:\src\build.amd64>cmake -GNinja ..\llvm
> [...]
> -- Target triple: x86_64-pc-win32
> -- Native target architecture is X86
>
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