Popcount CPU instruction (2019)
On the PS3 SPU cores, the best &quot;does everything&quot; instruction was the single &quot;rotate and mask&quot; series of instructions which was the underlying implementation of all rotates, shifts, and bitfield extraction instructions. That architecture is still my favourite years on - every register was vectorised by default, and the instruction was the minimalistic set to achieve a lot of unusual operations that were incredibly useful for graphics or signal processing work. Often you couldn&#x27;t find an exact instruction to do what you wanted, but if you studied the documentation long enough, you&#x27;d find one that generalised it and actually did do what you wanted, as well as gracefully handling loads of other edge cases you hadn&#x27;t thought of - for instance the various instructions to create shuffle masks so that lots of byte&#x2F;word&#x2F;long re-ordering operations could be done with the single shuffle instruction, which could be used to emulate unaligned memory access using aligned-only memory accesses.<p>Not exactly weird, but on the PowerPC side &quot;eieio&quot;, is my most favourite name for an instruction on any architecture - without fail, every time I come across it, I start humming Old McDonald!