Firefox 96 on Power

Firefox 96 is out and after some usage of it I think I agree it's definitely lessened the load on the main thread, which is one of the lead features in this release (and our heavily multicore POWER9 systems can pick up the slack for everything else). There are also multiple improvements to HTML and CSS. Some of you with Emacs muscle memory will want to read the Developer section of the Release Notes, though (I have the Command key mapped instead so I can still use Mac muscle memory: set ui.key.accelKey to 91). Fortunately it all builds out of the box using the PGO-LTO patch and .mozconfigs from Firefox 95.

In Power ISA JIT news, the patches and JIT backend have been merged into my copy of Firefox 97 and I'm ensuring it builds and passes tests before working on the third and final stage, the optimizing compiler. This will test some code paths that haven't been tested before, so I do expect this will be slower, but we're still aiming to get this done by May in time to get into the Firefox tree for the next ESR (102). Once I have the base in, there will be a new branch on Github you can work with (and contribute to!). I'm gratified to hear from folks who have tested the current 2-stage JIT in 91ESR and it looks like it's working well. More to come soon.