Re: enabling/disabling AltiVec in Firefox and derived browsers (ArcticFox)

[Riccardo Mottola <riccardo.mottola@libero.it>]

Hi Gabriel,


Gabriel Paubert wrote:
> This is going to be hopelessly slow. The point of SIMD is to process
> quickly vast amounts of data, the overhead of every single emulated
> instructions is counted in hundreds of cycles.
>
> IMHO, the only solution is to:
> a) only use SIMD in library code
> b) compile 2 or 3 versions of libraries: no SIMD, VMX and/or VSX
> c) put each library in a different directory
> d) at run time, select the path to load the libraries from CPU
>    capabilities

Emulation at kernel level is painfully slow, like FPU emulation - while
here you want maximum speed for that code. Already not having vector
instructions is a penalty, but an optimized build can still be usable.

yes enabling runtime libraries could be done, requires extensive work in
upstream code.

An easier version is the path that TenFourFox and other follow: just
provide two binaries, which is what I intend to do with ArcticFox.
However if Debian wants to come up with the pain of two (or more?) FF
packages

Riccardo