I've watched the SSA-related parts of these lectures and, despite the low video quality, I've found the quality of the content to be very high. Lecture notes can be found here: https://nptel.ac.in/courses/106108052
These instructions were not intentionally designed and put in there in secret. They're simply an unintended consequence of the "don't care" states of the instruction decoding logic.
The decoder is the part of the CPU that maps instruction opcodes to a set of control signals. For example "LDA absolute" (opcode 0xA5) would activate the "put the result in A" signal on its last cycle while "LDX absolute" (opcode 0xA6) would activate the "put the result in X" signal. The undocumented "LAX absolute" (opcode 0xA7) simply activates both because of the decoder logic's internal wiring, causing the result to be put in both registers. For other undocumented opcodes, the "do both of these things" logic is less recognizable but it's always there. Specifically disallowing these illegal states (to make them NOPs or raise an exception, for instance) would require more die space and push the price up.
See here[1] for example to get a sense of how opcode bits form certain patterns when arranged in a specific way.
That’s where link-time optimization enters the picture. It’s expensive but tolerable for production builds of small projects and feasible for mid-sized ones.
I'm sure it could also perform definition merging like you suggest but I can't think of a way of triggering it at the moment without also triggering their complete elision.
What a respectfully and humbly written comparison page. Ditto for their Supabase comparison. I can't rate the objectivity since I know very little about TrailBase but they got my attention now. It brings me such joy to see such a writeup in a world where humility is perceived as weakness. Kudos.
As a person who knows next to nothing about how the brain or the genes that configure it work, I tend to think of this in terms of 80s video games like River Raid. The level data for these games, if stored naively, would fill the computer's available memory many times over. So they just store a pseudorandom number generator seed along with a few other parameters. Coupled with a few rules to make the level playable, it can generate a seemingly impossible number of levels with very little stored data.
Maybe the genes just encode a few crucial rules and the rest just emerge from that.
Oh, and I know even less about how the universe works. But I tend to think of it in the same terms: Emergent phenomena stemming from simple rules à la Game of Life.
Ever since I read about Rodney Brooks and his idea of the Subsumption architecture I've been convinced that something like this is going on in our minds - likely with some other mechanisms too. It just clicks for me - I'm mostly likely completely wrong, but it's a pretty cool idea, and I've used it to create some really interesting simulations.
It's all about context, isn't it? "Humans vs. animals" is an important distinction to make in some contexts and useless in others. Insisting on the fact that humans are also animals if we're talking about, say, "language in humans vs. animals" is unproductive. It just makes discussions harder by forcing everyone to add "_non-human_ animals" to every mention. But if we're talking about, say, cellular biology, it's unproductive to force everyone to write "human and animal cells" instead of just "animal cells".
Similarly, distinguishing between transpilers and compilers might be important in some contexts and useless in others. Transpilers are source-to-source compilers, a subset of compilers. Whether it matters depends on the context.
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