Partial ppc64le JIT available again for Firefox 115ESR

I've been rehabilitating the old ppc64le JIT against more current Firefoxes and there is now available a set of patches you can apply to the current 115ESR. This does not yet include support for Ion or Wasm; the first still has some regressions, and the second has multiple outright crashes. Still, even with just the Baseline Interpreter and Baseline Compiler it is several times faster on benchmarks than the interpreter-only 115. I've included also the relevant LTO-PGO and WebRTC patches so you can just apply the changesets numerically and build. The patches and the needed .mozconfigs for either building an optimized browser or a debug JS shell (should you want to poke around) are in this Github issue.

While this passes everything that is expected to pass, you may still experience issues using it, and you should not consider it supported. Always backup your profile first. But it's now an option for those of you who were using the previous set of patches against 91ESR.


  1. Good to hear about the Jit Compiler. I do not currently own a Power Isa machine, but hope to do so one day, so i am grateful for the work.

  2. Thank you for 'reviving' the old JIT support. I still reverted back to the 91ESR if a website was not usable without JIT. Now I can finally update that and fully switch to 115.

    Thank you, I really appreciate the amount of work you put into this!

    1. I have survived my workday today with JITed 115, so it's looking good. Fedora RPMs should appear soon in Thanks, Dan

    2. Man, that copr is nice. Thanks - I'm looking forward to what the future brings and excited that Firefox feels so much better already.


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