[llvm-dev] How to build only the necessary components with MSVC

Liviu Prodea via llvm-dev
2019-04-05T19:36:11Z

I kind of figured it out and scripted the targets picking solution myself but
that 'LLVM_DISTRIBUTION_COMPONENTS' option is definitely better as it
should work with both MsBuild and ninja. Too bad this isn't in the docs
though:
https://llvm.org/docs/CMake.html#llvm-specific-variables   On Friday, April 5,
2019, 8:44:43 PM GMT+3, Chris Bieneman <chris.bieneman at me.com> wrote:

 You don't actually need to change your CMake configuration to reduce the
number of components you build. Just don't build the `all` target, instead
build the components you need.
Alternatively you can set the CMake variable `LLVM_DISTRIBUTION_COMPONENTS` to
the list of things you need, which will result in the generation of a
`distribution` target which will build just those pieces.
-Chris


On Mar 29, 2019, at 3:19 PM, Liviu Prodea via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
I configure LLVM build with this command
cd llvm-8.0.0.src & md buildsys-x64-MT & cd buildsys-x64-MT & cmake
-G "Ninja" -DLLVM_TARGETS_TO_BUILD=X86 -DCMAKE_BUILD_TYPE=Release
-DLLVM_USE_CRT_RELEASE=MT -DLLVM_ENABLE_RTTI=1 -DLLVM_ENABLE_TERMINFO=OFF
-DCMAKE_INSTALL_PREFIX=../x64-MT ..
The number of build objects grew with every major release to 1660 for LLVM 7 and
1761 for LLVM 8.

I only need the components requested here
https://gitlab.freedesktop.org/mesa/mesa/blob/master/scons/llvm.py#L103
After reading
https://llvm.org/devmtg/2015-04/slides/eurollvm-2015-build.pdf
and
https://llvm.org/docs/CMake.html
I found these options to be relevant: LLVM_DYLIB_COMPONENTS,
LLVM_BUILD_LLVM_DYLIB, LLVM_LINK_LLVM_DYLIB, LLVM_BUILD_TOOLS
and LLVM_INCLUDE_TOOLS. Unfortunately LLVM_DYLIB_COMPONENTS depends on
LLVM_BUILD_LLVM_DYLIB which doesn't support MSVC, I can turn off
LLVM_BUILD_TOOLS and LLVM_INCLUDE_TOOLS if I figure out how to filter unneeded
components as I would no longer need llvm-config anymore.
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