Swift ABI Resilience

on YouTube ↗01h 02m

" summary

Swift implements a concrete ABI resilience model: per-module resilience domains that let library-internal code use direct layouts while consumers use runtime metadata (cached at load) like the value witness table to compute size/offset/stride, with LLVM support for dynamic stack layout and outlining; opt-outs exist (e.g. fixed layout or forced inlining) for performance. Tradeoffs: a heavier runtime, runtime bookkeeping, tricky generics and the cost only appears when crossing domain boundaries.

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" chapters (6)

1. 0:00Introduction
2. 3:55ABI resilience meaning
3. 12:52Prioritizing ABI stability
4. 22:15C++ ABI stability signals
5. 34:59Swift ABI resilience approach
6. 53:42Q&A

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