Right, so it's trained on this text, from the BUGFIX-66 page where that code appears: Bug 47: Bit Extraction Misguided By Mask This is Guy L. Steele Jr.'s

Right, so it's trained on this text, from the BUGFIX-66 page where that code appears: Bug 47: Bit Extraction Misguided By Mask This is Guy L. Steele Jr.'s parallel suffix algorithm for bit extraction (U.S. Patent 6715066). Bits of x that correspond to 1-bits in m are shifted low and made consecutive, preserving relative order. The method masks x with m to isolate such bits and then repeatedly shifts 1- bits of x low by powers of two. A 1-bit in x with n less significant 0-bits in m is shifted low by a series of powers of two that sum to n. And it's trained on the patent, too. But there's something very clever happening in the repeated prefix sums of the holes, and that's the magic that makes it work. Does it understand how repetition of this works to achieve the extraction? odd := holes odd ^= odd << 1 odd ^= odd << 2 odd ^= odd << 4 odd ^= odd << 8 odd ^= odd << 16 odd ^= odd << 32 holes &^= odd What's happening to holes when this piece of code is repeated over and over? Does it really understand the algorithm (i.e., the magic of the code sequence above) or is it just recognizing the "bit extraction code" from its training data, and executing it like a machine? That's my question.