M12: Zero-copy to_binary via resource binary - #22
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to_binary now returns a BEAM resource binary aliasing the MLX Metal buffer directly, eliminating the memcpy that previously copied every tensor's bytes into a BEAM-heap binary. The resource binary pins a fresh Tensor resource so the MLX buffer survives until the binary is GC'd. from_binary zero-copy is deferred to M12.5 — MLX's allocator::Buffer stores an MTL::Buffer* on Metal, so wrapping a BEAM heap pointer is unsound without MTL::Device::newBufferWithBytesNoCopy. Also adds EMILY_ASAN=1 Makefile flag (requires sanitizer-enabled OTP) and a deferred ASan CI note (macOS SIP blocks DYLD_INSERT_LIBRARIES).
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Summary
to_binarynow returns a BEAM resource binary aliasing MLX Metal storage directly — no memcpy. The binary pins aTensorresource so the MLX buffer survives until the binary is GC'd.from_binaryzero-copy deferred to M12.5 (MLX'sallocator::BufferstoresMTL::Buffer*on Metal; wrapping a BEAM heap pointer is unsound withoutMTL::Device::newBufferWithBytesNoCopy).EMILY_ASAN=1Makefile flag for sanitizer-enabled OTP builds. ASan CI job deferred (macOS SIP blocksDYLD_INSERT_LIBRARIES; requires OTP built with--enable-sanitizers=address).Test plan
mix precommit— 285 tests, 0 failuresmix test --only conformance— 17 conformance tests (Qwen3, ViT, Whisper, DistilBERT)*_fulltags — 311 tests, 0 failures (including training convergence)to_binarycalls🤖 Generated with Claude Code