alt Hacker NewsHot take: NX bit is shit W^X is shit. proper JIT is having objects written as needed, and cache line flushing is full bullshit, we need self modifying code as a first class citizen and with modern techiques we can have it work and not be crazy slow, it is currently cuz shits fucked, but we can do better.
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RiverCrochet • today at 3:22 AM
L take. RAM is too slow for self-modifying code to be anywhere but F tier. This isn't 6502 land.
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Disallowing smc is a significant perf/power win. For cpus that run a large variety of large code (e.g. a web browser or ux stack), being able to cache a large instruction footprint and fetch/decode it quickly is important. Having to have the icache snoop data writes and entangle the i-fetch with the store buffer machinery would be a huge penalty to pay for a niche use case. Unlike loads, which are a small fraction of instructions to disambiguate with stores, you'd have to disambiguate every single instruction.
JIT is important to Apple platforms, and they seem to manage to make it work well enough even with the need for explicit invalidation.