tcatm's 4-way SSE2 for Linux 32/64-bit is in 0.3.10

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0.3.10 has tcatm's 4-way SSE2 as an option switch.

Use the switch "-4way" to turn it on.  Without the switch you get Crypto++ ASM SHA-256.

I could only get this working with Linux.

Get 0.3.10 from

Please report back your CPU and results!  I think it's pretty clear that Core 2 and lower are slower, i5 faster.  I don't think we've heard any i7 results yet.  We need to know about the different models of AMD or other less common CPUs.
I hope someone can test an i5 or AMD to check that I built it right.  I don't have either to test with.

I'm also curious if it performs much worse on 32-bit linux vs 64-bit.
I just uploaded a quick build so testers can check if I built it right.  (I don't have an i5 or AMD)  If it checks out, I'll put together the full package and do all the release stuff.
I propose to compile sha256.cpp with -O3 -march=amdfamk10 (will work on 32bit and 64bit) as only CPUs supporting this instruction set (AMD Phenom, Intel i5 and newer) benefit from -4way and it'll improve performance by ~9%.
GCC 4.3.3 doesn't support -march=amdfamk10.  I get:
sha256.cpp:1: error: bad value (amdfamk10) for -march= switch

With 4way, I get significantly better performance when I have all my virtual cores enabled. I think I get about the same amount of hashes when hyper threading is turned off with or without 4way.
Hey, you may be onto something!

hyperthreading didn't help before because all the work was in the arithmetic and logic units, which the hyperthreads share.

tcatm's SSE2 code must be a mix of normal x86 instructions and SSE2 instructions, so while one is doing x86 code, the other can do SSE2.

How much of an improvement do you get with hyperthreading?

Some numbers?  What CPU is that?
try -march=amdfam10
That works.

That's strange...  are we sure that's the same thing?  tcatm, try amdfam10 and make sure you get the same speed measurement.
cpu family : 6
model : 26
model name : Genuine Intel(R) CPU             000  @ 3.20GHz
stepping : 4
cpu family 6 model 26 stepping 4 is an Intel Core i7.
That's a 23% speedup with -4way, 63% total speedup with -4way + hyperthreading.
33% faster with hyperthreading than without it.
I wrapped sha256.cpp in
#endif // FOURWAYSSE2

try it now.
Any non-Mac i5 love?
Windows i5 64-bit got slower here.
That's the first I've heard anyone say i5 was slower.  Everyone else has said 4way was faster on i5.  Moreso with hyperthreading enabled.

And i5, at least on my macbookpro
Good, so I take it that's a confirmation that it's working on Mac as well?

Laszlo told me he did compile in the -4way stuff on Mac, so the -4way switch is also available to try on Mac.  I don't think makefile.osx on SVN has it yet, just the built version.
Thanks for clearing that up.  I read the link someone posted about AMD making that change around 2007, but I didn't know what the story was for Intel.

There's no hope for Core/Core2 then.  They only have half the SSE2 hardware.

Strange that Intel has 3 128bit units, but AMD with 2 128bit units is the faster one.
  • AMD K10: 2 128bit units
  • intel nehalem: 3 128bit units
This probably explains why hyperthreading increases performance with -4way.  If three SSE2 units is excessive, then hyperthreading would help keep them all busy.
The simplification is intentional.  There will only be more than one thash[7]=0 in one out of 134,217,728 cases.  It only makes it 0.0000007% slower.