[llvm-dev] llvmbuildectomy

Serge Guelton via llvm-dev llvm-dev at lists.llvm.org
Fri Oct 9 09:51:02 PDT 2020

Hi Folks,

Although LLVM now relies on cmake for its build configuration, it still calls an
external Python script, namely llvm-build, to manage component dependecies,
activation or deactivation of target componenents and generating description for

This system is documented in http://llvm.org/docs/CommandGuide/llvm-build.html
and https://llvm.org/docs/LLVMBuild.html.

Several features of the system are either undocumented, obsolete or redundant
with the cmake description (sometimes all at once!). For instance the
LLVMBuild.txt under tools/ don't seem relevant anymore. And the
–write-make-fragment for Makefile comptibility no longer makes sense.

The whole thing also adds a dependency on Python in our core Build system (leaving
aside documentation, that is).

I have a patch that seems to work for the default configuration, submited here:


It's basically a conversion of the Python script to plain cmake, with some
(unused (?)) feature removed.

It still require proper documentation, some cleaning and official doc update,
but now that the approach is somehow validated technically, I'd like to know if
people interact with llvm-build at all, have expectations etc, other than « LLVM
builds ».

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