> I tested it was working by counting the bits and someone critizised it for not using popcount
replyPSA: Rust exposes the popcnt intrinsic via the `count_ones` method on integer types: https://doc.rust-lang.org/std/primitive.u32.html#method.coun...
Looks like that was added about 3 years after I wrote my test code.
replyAccording to the docs there, it was stabilized in 1.0, then stabilized in const contexts in 1.32. Were you testing this in 2012?
replyI had a similar experience implementing simd instructions in my emulator, where I needed to break apart a 64-bit value into four eight-bit values, do an operation on each value, then pack it back together. My first implementation did it with all the bit shifts you’d expect, but my second one used two helpers to unpack into an array, map on the array to a second array, and pack the array again. The optimized output was basically the same.
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