QF14 summary

[classilla]

https://ehsanakhgari.org/blog/2017-06-23/quantum-flow-engineering-newsletter-14

Much less applies to us now, and this may be the last summary he issues.

Easy:
https://hg.mozilla.org/mozilla-central/rev/50c745be6bd1
https://hg.mozilla.org/mozilla-central/rev/c36dabb0aba6
https://hg.mozilla.org/mozilla-central/rev/c0bb73483afb

[classilla]

A little more difficult but apparently very helpful:
https://hg.mozilla.org/mozilla-central/rev/8c7dd6a9e935

[classilla]

This can be done very simply: we just rewrite callPreBarrier in MacroAssembler.h (which is the equivalent function) with a PPC-only variant that does the null check. We can optimize the short branch at the same time.
https://hg.mozilla.org/mozilla-central/rev/231bd9d90fb3

[classilla]

Another easy one.
https://hg.mozilla.org/mozilla-central/rev/1fd504b9feed

[classilla]

The callPreBarrier change regressed benchmarks. I guess the check is too expensive.