This also adds a dedicated channel for ungoogled-chromium that enables
us to update ungoogled-chromium independently of chromium.
TODO: Automate ungoogled-chromium updates via update.py (currently it
needs to be updated manually).
Note: Unfortunately this changes the ungoogled-chromium derivation
because common.nix passes the channel as an argument to
stdenv.mkDerivation (this makes it more difficult to verify this commit
but the result should remain the same).
I used nix-instantiate to verify that the derivations for chromium and
ungoogled-chromium remain unchanged (only the meta attributes change
slightly as I added myself as ungoogled-chromium to receive
notifications for PRs/issues).
The gn version depends on the channel and new gn versions aren't always
backward compatible. Therefore we should also include it in
upstream-info.json (I've scoped it under "deps" as we'll likely have to
add more like this in the future).
LLD: https://lld.llvm.org/
When you link a large program on a multicore machine, you can expect that LLD runs more than twice as fast as the GNU gold linker. Your mileage may vary, though.
Link-time optimization (LTO) is supported by default.
Some default settings have been tuned for the 21st century. For example, the stack is marked as non-executable by default to tighten security.
LTO & ThinLTO: https://clang.llvm.org/docs/ThinLTO.html
LTO (Link Time Optimization) achieves better runtime performance through whole-program analysis and cross-module optimization. However, monolithic LTO implements this by merging all input into a single module, which is not scalable in time or memory, and also prevents fast incremental compiles. ThinLTO is a new approach that is designed to scale like a non-LTO build, while retaining most of the performance achievement of full LTO.
PGO: https://llvm.org/docs/HowToBuildWithPGO.htmlhttps://blog.chromium.org/2020/08/chrome-just-got-faster-with-profile.html
Allows your compiler to better optimize code for how it actually runs. Users report that applying this to Clang and LLVM can decrease overall compile time by 20%.
Because PGO uses real usage scenarios that match the workflows of Chrome users around the world, the most common tasks get prioritized and made faster. Delivers up to 10% faster page loads.
CFI: https://clang.llvm.org/docs/ControlFlowIntegrity.htmlhttps://www.chromium.org/developers/testing/control-flow-integrity
Aborts the program upon detecting certain forms of undefined behavior that can potentially allow attackers to subvert the program’s control flow. These schemes have been optimized for performance, allowing developers to enable them in release builds.
By default, a program compiled with CFI will crash with SIGILL if it detects a CFI violation.
Additionally:
Use minizip instead of zlib. Chromium says zlib but actually uses minizip.
Remove old unused workarounds.
Make shell scripts POSIX compliant.
Update documentation URLs.
Prepare for using system libraries.
This should also fix VA-API for chromiumBeta (though that part needs
some cleanup). However, chromiumDev likely still fails due to the
absence of dirmd (not included in the tarball so far, we might have to
package and add it as a dependency).
Wanted to do this for a long time to collect important knowledge and
make it easier to pass maintainership.
Only time will tell if this'll be useful or become outdated instead.
