j"1LAnZuoQdcKCkpDBKQMCgziGMoPC4VQUckM<div class="post">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.<br/><br/>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.<br/><br/>Here's what I ended up with:<br/><div class="codeheader">Code:</div><div class="code"> // We need Intel Nehalem or AMD K10 or better for 128bit SSE2<br/> // Nehalem = i3/i5/i7 and some Xeon<br/> // K10 = Opterons with 4 or more cores, Phenom, Phenom II, Athlon II<br/> // Intel Core i5 family 6, model 26 or 30<br/> // Intel Core i7 family 6, model 26 or 30<br/> // Intel Core i3 family 6, model 37<br/> // AMD Phenom family 16, model 10<br/> bool fUseSSE2 = ((fIntel && nFamily * 10000 + nModel >= 60026) ||<br/> (fAMD && nFamily * 10000 + nModel >= 160010));<br/></div><br/>I saw some sporadic inconsistent model numbers for AMD CPUs, so I'm not sure if this will catch all capable AMDs.<br/><br/>If it's wrong, you can still override it with -4way or -4way=0.<br/><br/>It prints what it finds in debug.log. Search on CPUID.<br/><br/>This is only enabled if built with GCC.</div> text/html
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