<random>: Optimized divisionless implementation of minstd_rand, minstd_rand0

[mirounga]

I have traced the optimization to the following paper:

Carta, David F. "Two fast implementations of the “minimal standard” random number generator." Communications of the ACM 33, no. 1 (1990): 87-88.

BEFORE:

Benchmark Time CPU Iterations

BM_lcg 4.44 ns 4.45 ns 154482759

AFTER:

Benchmark Time CPU Iterations

BM_lcg 2.09 ns 2.09 ns 344615385

Double the speed

[StephanTLavavej]

Thanks! I pushed a conflict-free merge with main (as we had updated Google Benchmark), followed by commits to simplify the code and expand the comment.

We merge PRs simultaneously to our GitHub and MSVC-internal repos in a semi-manual process, batched up to save time. Your PR will be part of the next batch; I'll post comments here as I prepare it for merging, likely next week.

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

[StephanTLavavej]

Thanks again for this performance improvement! This should ship in VS 2022 17.14 Preview 3. 😻 🚀 🎉