Bug#877445: Certain sites crash Firefox on pre-SSE2 CPUs

[Fanael Linithien]

2017-10-01 23:10 GMT+02:00 Sylvestre Ledru <sylvestre at debian.org>:
> However, if I were, I would won't fix this bug. CPU without SSE2 are now
> rare

Well, my ThinkPad T23 still works and despite the claims of some
people, is still perfectly capable of browsing the web ;)

> and the performance drop for not using SSE2 being enough that it should
> remain enabled by default

Sure, but if that's the case, I'd argue that the Debian Firefox
package should instead drop all pretense of supporting pre-SSE2 CPUs
and just be compiled with -msse2 throughout. As things stand, Debian
does try to support pre-SSE2 CPUs, unlike the binaries provided by
Mozilla themselves.

> (AFAIK, this is done at build time, not at runtime).

IIRC most of it is done at runtime (and you still need runtime
checking for SSE3 and newer, AVX, etc anyway), and the checks are
almost free in practice thanks to branch prediction.