Wasn't xoshiro256+ mostly weak in the lower bits, and recommended to use to generate floating point numbers?
I suppose that this is probably indicative of a more fundamental weakness, but for reference the upper bits should be way higher quality that the Messene Twister (As that one fails PractRand while the upper bits of xoshiro256+ don't IIRC)
Yes, but it is also weak in terms of seed correlation, which makes xoshiro256+x8 weak in many more bits.
That said, there are certainly use-cases for it! I just like the idea that we can have our cake and eat it too: something closer to the Pareto frontier, that doesn’t have those caveats, and yet is faster.
I suppose that this is probably indicative of a more fundamental weakness, but for reference the upper bits should be way higher quality that the Messene Twister (As that one fails PractRand while the upper bits of xoshiro256+ don't IIRC)