Hi,

Why are we assuming that it's not safe to use sse4 but it IS safe to use sse2? Isn't sse4 kind of old already?

Thanks!

nesdavid
Why are we assuming that it's not safe to use sse4 but it IS safe to use sse2? Isn't sse4 kind of old already?

Steam hardware survey, which naturally only covers people who use steam and have not opted out of the survey, says the following:


[table]
[tr]
[td]Opcodes[/td]
[td]%[/td]
[/tr]
[tr][td]SSE2[/td][td]99.98[/td][/tr]
[tr][td]SSE3[/td][td]99.88[/td][/tr]
[tr][td]SSE4.1[/td][td]77.23[/td][/tr]
[tr][td]SSE4.2[/td][td]72.30[/td][/tr]
[tr][td]SSE4a[/td][td]22.61[/td][/tr]
[/table]

Which to me says that SSE2 is standard, SSE3 is pretty safe, but SSE4's are less common.

That was the info I was looking for, thanks a lot!

Yes, given the current installed base, it's safe to assume that you can use SSE2 (and possibly even SSE3) as the default path, but you can't really use SSE4 and above without assuming that some users might not have it. You can still use it, but you have to check for it and only use that path in the code if the machine has it, so you still need to have an SSE2 or 3 fallback path.

- Casey