AMD to phase out 3DNow! multimedia instruction set

[fellix_bg]

3DNow!™ instructions are being deprecated

AMD introduced the 3DNow!™ instruction set back in the K6-2 days to do Single Instruction Multiple Data (SIMD) instructions, otherwise known as vectorized instructions. These were mainly used for graphics intensive applications and even audio processing. Since then, we have added many SIMD instruction sets to our processors, such as the widely used Streaming SIMD Extensions (SSE) instruction set and its successive versions.

3DNow! instructions are being deprecated and will not be supported in certain upcoming AMD processors. In those processors, the 3DNow! Instructions feature flag bit will not be set.

[Manicdan]

lol intel adds more media support, amd removes some. an interesting day indeed

[nn_step]

Looks like AMD is working hard to clean up their implementations with a huge focus on forward support.

Since largely very few applications made use of 3DNow, it is only logical to remove it.

[Chumbucket843]

it's much more efficient to drop 40 instructions rather than integrating old implementations into new designs like bulldozer. maybe someday we can drop mmx too.

[Kingcarcas]

Out with the legacy crud getting in the way of progress!

[fellix_bg]

The whole x87 FPU/SIMD stack should be ditched at once, but sadly then we won't have software PhysX...

[RaZz!]

Looks like AMD is working hard to clean up their implementations with a huge focus on forward support.

Since largely very few applications made use of 3DNow, it is only logical to remove it.

even if an application (which are games most of the time anyways) uses 3dnow - today's cpus are more than fast enough to run these apps even without optimized instruction sets. so i don't think it's a big loss.

[Calmatory]

Most, if not all the 3DNow! functionality has been replaced with SSE variants.

[nn_step]

even if an application (which are games most of the time anyways) uses 3dnow - today's cpus are more than fast enough to run these apps even without optimized instruction sets. so i don't think it's a big loss.

Well if you want to be completely honest, there are large swaths of instructions included in x86 that are rarely used.

Some good examples:

x87 [Only intentional malice or mental retardation would employ its use; since most compilers intentionally avoid it.]

MMX [Only binary code older than SSE2 would dare make use of it]

binary coded decimal instructions [I have yet to find a single application that uses them.]

Repeated String Operations [Haven't see code using it in a long time]

and for the curious a list of the most commonly used x86 instructions:

http://www.jegerlehner.ch/intel/IntelCodeTable.pdf

[Iconyu]

Well if you want to be completely honest, there are large swaths of instructions included in x86 that are rarely used.

Some good examples:

x87 [Only intentional malice or mental retardation would employ its use; since most compilers intentionally avoid it.]

MMX [Only binary code older than SSE2 would dare make use of it]

binary coded decimal instructions [I have yet to find a single application that uses them.]

Repeated String Operations [Haven't see code using it in a long time]

and for the curious a list of the most commonly used x86 instructions:

http://www.jegerlehner.ch/intel/IntelCodeTable.pdf

Could instructions using these be emulated?

[informal]

Most, if not all the 3DNow! functionality has been replaced with SSE variants.

Exactly.
Plus the BD front end would have to support 21 3Dnow instructions which are already covered in SSE or MMX sets. BD will have a full support for MMX,SSE1-3,SSSE3,SSE4.x , AVX,XOP,LWP and AES .Dropping the 3dnow support was expected(they even,for now,dropped "new" CVT16 from BD cores).

There is a table at AMD's programmers manual that illustrates the coverage of 3Dnow by other intr. sets.

[nn_step]

Could instructions using these be emulated?

yes, it is extremely trivial to do that. However as of yet, only a subset of them are not worthwhile to still keep in microcode. [Which is dirt cheap]

I honestly expect over the next 10 years to see a large segment of these instructions to be dropped or simply emulated around.

For example x86_64 long mode eliminates several instructions that previously horded some precious opcode space.

However It is felt that AMD made a mistake by keeping x87 in long mode.

If AMD and Intel, just sat down together and cleaned up AVX; we could very quickly see a much cleaner API.

[freeloader]

Glad to see some of the "old legacy" instruction sets being removed from new gen CPUs.

[Neova]

While I appreciate companies trying to bring out innovation such as 3Dnow!, it makes sense to drop unused or outdated functions when it has been surpassed (dominated) with a broader standard in SSE.

One (eventual) instruction set to rule them all would make life easier on developers to optimize for.

[RVWinkle]

While I appreciate companies trying to bring out innovation such as 3Dnow!, it makes sense to drop unused or outdated functions when it has been surpassed (dominated) with a broader standard in SSE.

One (eventual) instruction set to rule them all would make life easier on developers to optimize for.

I wonder what we could call this Reduced Instruction Set Computing?

[Manabu]

MMX [Only binary code older than SSE2 would dare make use of it]

binary coded decimal instructions [I have yet to find a single application that uses them.]

MMX is still faster than SSEx in many functions on current CPUs. x264 use varying degrees of MMX acording to the CPU architeture, except for nehalem based cpus. There, IIRC, SSEx seems better for all cases. For Core 1 and Pentium-M, MMX is faster for almost all cases. Compilers also still optimize using MMX, it seems. Some software is optimized only in MMX, because supporting old cpus adequatedly was put as more important than be a bit faster on some newer CPUs.

[aka1nas]

I am pretty sure that 3dNow! and MMX are both unusable while in x86-64 mode anyway, so this doesn't actually affect anyone unless they are still running a 32-bit OS.

[xVeinx]

I am pretty sure that 3dNow! and MMX are both unusable while in x86-64 mode anyway, so this doesn't actually affect anyone unless they are still running a 32-bit OS.

Which is 90% of window's users...

[ajaidev]

it's much more efficient to drop 40 instructions rather than integrating old implementations into new designs like bulldozer. maybe someday we can drop mmx too.

Sooner than you think...

[zanzabar]

lol intel adds more media support, amd removes some. an interesting day indeed

3dnow has almost nothing to do with media support, intel is adding in a new unit for transcoding they are not adding instructions.

it's much more efficient to drop 40 instructions rather than integrating old implementations into new designs like bulldozer. maybe someday we can drop mmx too.

u wont see MMX gone until we have no more bioses or boot loaders, the only thing that it dose anymore is keep the internal commands encrypted and people with low lvl code wont be happy when u can just probe a command.

Which is 90% of window's users...

windows 7 is supposed to be over 50% 64bit, visa has a good chunk 64bit, almost all servers that are not running propriety legacy programs on windows are 64bit (08 r2 is not even on x86)

if this makes the chips better then im all for it, but if they just check a bit to disable it when its there, then i dont see the point.

[RejZoR]

But will older games work if we drop 3DNow! and maybe MMX someday? I mean i know CPU's are fast enough, but will it even work if there is no required instructions, but the game requires them? Are there any fallbacks or it works anyway, just slower back in it's days (but wouldn't make much diffference today n fast CPU's)?

[zanzabar]

But will older games work if we drop 3DNow! and maybe MMX someday? I mean i know CPU's are fast enough, but will it even work if there is no required instructions, but the game requires them? Are there any fallbacks or it works anyway, just slower back in it's days (but wouldn't make much diffference today n fast CPU's)?

im sure that there could be driver emulation, u can run dos box emulation for older stuff and some of those commands they use arnt in windows anymore, and u can emulate most parts of PPC and other ibm stuff so i dont see why this could not.

[[XC] Lead Head]

But will older games work if we drop 3DNow! and maybe MMX someday? I mean i know CPU's are fast enough, but will it even work if there is no required instructions, but the game requires them? Are there any fallbacks or it works anyway, just slower back in it's days (but wouldn't make much diffference today n fast CPU's)?

Intel never had 3DNow! and games work just fine on them.

[mAJORD]

So much for this!

http://www.youtube.com/watch?v=KBG7HRQpPIg


Whenever I think of 3dNow! I think of Quake 2 patch.. As someone mentioned, anything using 3dnow! would work just as well without it.

[zalbard]

Good move. There is too much mess as is. About time we standardise things more.