Auto-detect for 128-bit 4-way SSE2

SVN rev 150 has some code to try to auto-detect whether to use 4-way SSE2.  We need this because it’s only faster on certain newer CPUs that have 128-bit SSE2 and not ones with 64-bit SSE2.

It uses the CPUID instruction to get the CPU brand, family, model number and stepping.  That’s the easy part.  Knowing what to do with the model number is the hard part.  I was not able to find any table of family, model and stepping numbers for CPUs.  I had to go by various random reports I saw.

Here’s what I ended up with:

Code:  // We need Intel Nehalem or AMD K10 or better for 128bit SSE2
  // Nehalem = i3/i5/i7 and some Xeon
  // K10 = Opterons with 4 or more cores, Phenom, Phenom II, Athlon II
  //  Intel Core i5  family 6, model 26 or 30
  //  Intel Core i7  family 6, model 26 or 30
  //  Intel Core i3  family 6, model 37
  //  AMD Phenom    family 16, model 10
  bool fUseSSE2 = ((fIntel && nFamily * 10000 + nModel >=  60026) ||
                   (fAMD   && nFamily * 10000 + nModel >= 160010));

I saw some sporadic inconsistent model numbers for AMD CPUs, so I’m not sure if this will catch all capable AMDs.

If it’s wrong, you can still override it with -4way or -4way=0.

It prints what it finds in debug.log.  Search on CPUID.

This is only enabled if built with GCC.

Since the function CallCPUID function contains x86 assembler, it breaks the build on other architectures. I’ve changed line 2770 in main.cpp to

#if defined(GNUC) && defined(CRYPTOPP_X86_ASM_AVAILABLE)

to make it compile again, at least on ARM.

I wonder if we could get the VIA C7 code included with an autodetect in the standard clients? Or is this just too rare a beast to trouble the main code over? The C7 does work with the standard clients with regular pentium or sse2 code albeit slower.

There should be an interface to the hashing handler (or even a full miner per implementation)

+1. In case someone wants FPGA/whatever specific accelerator he has.

Quote from: teknohog on September 09, 2010, 07:32:05 PM

Since the function CallCPUID function contains x86 assembler, it breaks the build on other architectures. I’ve changed line 2770 in main.cpp to

#if defined(GNUC) && defined(CRYPTOPP_X86_ASM_AVAILABLE)

to make it compile again, at least on ARM. Added in SVN rev 152