2 ms·

> There's a pile of different SIMD ("SSE") instruction sets, and it's pretty much anybody's guess what the system your program is running on is likely to have.

> There's a pile of different SIMD ("SSE") instruction sets, and it's pretty much anybody's guess what the system your program is running on is likely to have. It is nowhere near that bad. There are three lineages of chips--Intel Atoms (/E-cores), Xeons (/P-cores), and AMD's chips--and within each lineage, a newer chip is a strict superset of the features of the previous chip. The exception to this rule are the features that are so bad that no one uses them (most notably MPX), and AVX-512 which landed in the desktop P-cores before big-little happened, where they were turned off because the E-cores don't support AVX-512. If your computer isn't over a decade old, it's not a guess which SSE instruction sets your hardware has--it has all of the SSE instruction sets.

hajile 2y ago
Where can I find FMA4 in modern AMD CPUs? What about 3dNow? XOP? Even SSE isn't guaranteed as Intel chips never implemented SSE4a. AVX-512 is especially weird. Cannon lake implemented VBMI, but not Cooper or Cascade Lake only for it to reappear on Ice, Tiger, and Rocket lake then disappear on Alder Lake and reappear on Sapphire Rapids. BF16 was in Cooper Lake only to disappear for Ice, Tiger, rocket, and Alder lake before reappearing again on Sapphire Rapids.
snvzz 2y ago
>and AVX-512 which landed in the desktop P-cores before big-little happened, where they were turned off because the E-cores don't support AVX-512. x86-64v4 requires avx-512. In short, they utterly fucked up.