pre-merge checks ready for beta testing

Dear LLVM developers,

To sign up for the pre-merge beta testing, please add yourself to the “pre-merge beta testing” project [2] on Phabricator.

I started setting up pre-merge tests for LLVM on Phabricator [1]. The goal is to test patches and catch bugs BEFORE a patch is merged into the master branch. This should improve the stability of the master branch.

When discussing this on the LLVM dev meeting in San Jose in October during several round tables, quite a few people were interested in using this feature rather earlier than later. While the setup is far from perfect and the long term operation and infrastructure is still to be clarified, I would like to start with a beta testing phase.

The current features and usage are explained in [1]. If you find a bug, please raise an issue at [3].