3DNow! has become 3DNo More!
It really doesn't feel like it was that long ago when AMD introduced its own SIMD extensions called 3DNow!, but it's been long enough now that the chip company is sending the technology out to pasture.
AMD announced last week that 3DNow! is deprecated and will not be supported in certain upcoming AMD processors and will not have that feature flag bit set.
What does this mean for those who make software using these AMD instructions?
If your software used 3DNow! instructions at any point in time you should confirm that you only take that code path after checking to see if the feature is supported during runtime, using CPUID.
Most likely, your code already has another code path to take, such as an SSE path, if 3DNow! instructions are not supported. To reiterate, make sure that the code uses feature bits to determine when the code should take this path. If the code uses the vendorID string rather than a feature bit to make the path determination, AMD processors that support SSE may end up taking a slower path as a result.
Read the full post from the AMD developer blog.
It would be interesting to know which products currently available or in development would explicitly call 3DNow! code and therefore suffer performance penalties or even break. Perhaps benchmarking and diagnostic tools would explicitly call 3DNow! code.
A bit of nostalgia. Remember Quake II, running on an AMD K6-2 and 3DFX Voodoo card? Both the game and the actual graphics card drivers were 3DNow Optimised, and the result was quite something.
An extract from AMD's literature..
http://www.amd.com/us/press-releases/Pages/Press_Release_911.aspx
SUNNYVALE, CA -- 7/6/1998 -- Quake II, one of the computer gaming industry's most popular titles, is now optimized for AMD's 3DNow!™ technology via software update available from AMD. This update, combined with optimized Voodoo2 device drivers (Glide 2.5), takes advantage of the new 3DNow!™ instructions used in AMD's latest microprocessor, the AMD-K6®-2.
..AMD's own performance lab has determined that the AMD-K6-2/300MHz processor-based system outperforms an equally configured Pentium II/300MHz system, without the optimized drivers, in every comparable test configuration. Not only does the AMD-K6-2 processor win head to head, in certain benchmark tests it's 3D performance can outperform the competition when configured with only one 3D graphics accelerator card versus the competition's two 3D graphics accelerator cards. In all test configurations of 640 x 480, an AMD-K6-2/300MHz processor with a SINGLE Voodoo2 3D graphics accelerator card OUTPERFORMED Pentium II/300MHz with DUAL SLI Voodoo2 3D graphics accelerator cards!
Wiki Article: http://en.wikipedia.org/wiki/3DNow!
Despite the PII's stronger FPU and MMX support it had no additional SIMD support until the arrival of the Pentium III with SSE. The AMD solution performed perform great like many of my friends who couldn't afford Intel, I chose the AMD route. Games like Quake II and Project IGI ran sweet on an AMD K6-2 and 3DFX Voodoo II card. I lost a lost of hours of daylight playing those games and I'm sure many other folks here will have fonder memories of those times.