Building and hacking LDC on Windows using MSVC

Windows MSVC x86/x64 are first class targets for LDC. This page documents how to build, test and hack LDC2 on Windows.

LDC binaries

If you just want to download the very latest LDC binaries, head over to the GitHub CI release.

Advice

It is hard for us to keep these wiki pages up-to-date. If you run into trouble, have a look at the build scripts for our Continuous Integration platforms: the Azure Pipelines scripts for Ubuntu Linux and macOS and Windows are always up-to-date with the latest build setup.

Building LDC

Required software

• Windows, of course!
• Visual Studio or stand-alone Build Tools ≥ 2015. Make sure to install the Visual C++ toolchain.
• A D compiler (the ltsmaster git branch does not need a D compiler to build). DMD as host compiler isn't supported on Windows, make sure to use LDC.
• git ≥ 2.0 (I use PortableGit)
• Python (I use Winpython)
• CMake ≥ 3.4.3
• Ninja, a neat little and fast build system
• cURL DLL (just use a prebuilt one ≥ 7.65.3-2)
  • Put the 64/32-bit libcurl.dll in a PATH directory (e.g., C:\LDC\LDC-x64\bin).
• For running the testsuite:
  • GNU make (prebuilt v4.2.1)
  • If you get line-ending related grep errors during the DMD tests: a working GNU grep (prebuilt v3.0)

Shell environment

I use a little batch file to set up my LDC build environment. It's located in the root of my LDC environment: C:\LDC\shell.cmd. It sets up the PATH environment variable (I've installed the portable tools into C:\LDC\Tools) and then spawns a new x64 Native Tools Command Prompt for VS 2017 with a below-normal process priority, so that my system stays responsive while building. I use a shortcut on my desktop to this batch file. Please adjust it to your needs (and note that %~dp0 is the directory containing the script, i.e., C:\LDC\).

@echo off
set PATH=%~dp0LDC-x64\bin;%~dp0LLVM-x64\bin;%~dp0Tools\Ninja 1.9.0;%~dp0Tools\make-4.2.1;%~dp0Tools\grep-3.0;C:\Program Files\Git\usr\bin;C:\Program Files\Git\bin;%~dp0Tools\cmake-3.15.2-win64-x64\bin;%~dp0Tools\Winpython64-3.7.4.0Zero\python-3.7.4.amd64;%PATH%
:: set D host compiler
set DMD=%~dp0ldc2-1.17.0-windows-multilib\bin\ldmd2.exe
:: set a few environment variables for dmd-testsuite
set OS=windows
set MODEL=64
set DMD_TESTSUITE_MAKE_ARGS=-j4
if not exist "%TERM%" set TERM=msys
start /belownormal %comspec% /k "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\Tools\VsDevCmd.bat" -arch=x64

Use -arch=x86 in the last line and set MODEL=32 if you want to build a 32-bit LDC.

Open a shell by executing the batch file.

• Running cl should display the banner from the MS compiler.
• Running link /version should display the banner from the MS linker.
• Running git --version should display the banner from git.
• Running python --version should display the banner from Python.
• Running cmake --version should display the banner from CMake.
• Running ninja --version should display the Ninja version.
• Running where libcurl.dll should find a file.
• Running make --version should display the banner from GNU make (only required for the tests).

Building LLVM

Building LLVM takes quite a while. You may want to download a prebuilt version from here; note that the C++ compiler has changed from MS to clang since v7.0.0-2, so either use an older LLVM version or use clang for building LDC (see CI scripts). We use these prebuilt packages for CI and the official release packages. Just extract the archive into C:\LDC\LLVM-x64 and then skip this section. In case you encounter linking errors when building LDC, you probably use a different MSVC/clang toolchain version and will need to build LLVM yourself.

• Download an LLVM source tarball (llvm-x.y.z.src.tar.xz). We maintain an LLVM fork with minimal modifications; vanilla LLVM can be used as well.
• Extract it into C:\LDC (e.g., with 7-Zip), so that you end up with the source tree in e.g. C:\LDC\llvm-8.0.0.src.
• cd C:\LDC
• Create a build directory: md build-llvm-x64
• Change into it: cd build-llvm-x64

• Use a command like this (in one line) to create the Ninja build files:

  cmake -G Ninja ..\llvm-8.0.0.src
        -DCMAKE_INSTALL_PREFIX="C:\LDC\LLVM-x64"
        -DCMAKE_BUILD_TYPE=RelWithDebInfo -DLLVM_USE_CRT_RELWITHDEBINFO=MT
        -DLLVM_ENABLE_ASSERTIONS=ON
        -DLLVM_TARGETS_TO_BUILD=AArch64;ARM;Mips;MSP430;NVPTX;PowerPC;X86
        -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=RISCV;WebAssembly
        -DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-pc-windows-msvc
        -DCOMPILER_RT_INCLUDE_TESTS=OFF

  Use -DCMAKE_BUILD_TYPE=Debug to build a debug version (and probably use -DLLVM_USE_CRT_DEBUG=MTd then). The LLVM page on CMake documents other variables you can change. For a 32-bit build, use -DLLVM_DEFAULT_TARGET_TRIPLE=i686-pc-windows-msvc.

• Build LLVM: ninja
• Install it (to C:\LDC\LLVM-x64): ninja install
• Note that you'll need to keep the C:\LDC\build-llvm-x64 directory in order to keep the LLVM debuginfos (.pdb files) available.

Building LDC

• cd C:\LDC
• git clone --recursive https://github.com/ldc-developers/ldc.git
• md build-ldc-x64
• cd build-ldc-x64

• Use a command like this (in one line) to create the Ninja build files:

  cmake -G Ninja ..\ldc
        -DCMAKE_INSTALL_PREFIX="C:\LDC\LDC-x64"
        -DCMAKE_BUILD_TYPE=RelWithDebInfo
        -DLLVM_ROOT_DIR="C:/LDC/LLVM-x64"

  You can specify the D host compiler explicitly by adding -DD_COMPILER=c:\path\to\ldmd2.exe.

• Build LDC and the default libraries: ninja. The binaries end up in C:\LDC\build-ldc-x64\bin.
• If you want to install it (to C:\LDC\LDC-x64): ninja install

Tests

For troubleshooting, be sure to examine the file C:\LDC\build-ldc-x64\Testing\Temporary\LastTest.log after a ctest invokation.

Running the LDC D unit tests

• cd C:\LDC\build-ldc-x64
• ctest --output-on-failure -R ldc2-unittest

Running the LIT (LLVM Integrated Tester) tests

You'll need to have lit installed for Python:

• Upgrade pip: python -m pip install -U pip
• Install lit: python -m pip install lit
• Make sure it works: python -c "import lit; lit.main();" --version

To run the tests from your build dir you can do:

• cd C:\LDC\build-ldc-x64
• ctest -V -R lit-tests

or you can go to the tests folder inside your build dir, and run the runlit.py script:

• cd C:\LDC\build-ldc-x64\tests
• python runlit.py -v .

The second way is convenient for running individual tests:

• python runlit.py -v codegen/align.d

Running the druntime/Phobos unit tests and druntime standalone tests

• cd C:\LDC\build-ldc-x64
• Build the unit tests: ninja all-test-runners
• Run the tests, excluding LDC unit tests, LIT tests and dmd-testsuite: ctest --output-on-failure -E "dmd-testsuite|lit-tests|ldc2-unittest"

Running the dmd-testsuite tests

• Set some environment variables for dmd-testsuite's Makefile:
  • OS and MODEL
    • set OS=windows (since v1.17, previously win{32,64})
    • set MODEL={32,64}
  • DMD_TESTSUITE_MAKE_ARGS enables parallel execution, e.g.
    • set DMD_TESTSUITE_MAKE_ARGS=-j4
• cd C:\LDC\build-ldc-x64
• ctest -V -R dmd-testsuite
  • Debug only: ctest -V -R dmd-testsuite-debug
  • Release only: ctest -V -R dmd-testsuite -E -debug

Developing/debugging LDC/LLVM with Visual Studio

Be sure to use Rainer's great Visual D plugin for VS.

• cd C:\LDC
• md vs-ldc-x64
• cd vs-ldc-x64
• Use the CMake command from the Build LDC section, but use the VS generator instead of Ninja this time: cmake -G "Visual Studio 15 Win64" ...

This creates the VS 2017 solution C:\LDC\vs-ldc-x64\ldc.sln. A Visual Studio solution for LLVM can be created the same way.

I don't recommend building LDC/LLVM with VS directly; I only use VS for development/debugging and build in the shell with Ninja.

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Windows MSVC