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Title: src,ffi: create fast-call metadata Symbols lazily by mcollina · Pull Request #66015 · nodejs/node · GitHub

Open Graph Title: src,ffi: create fast-call metadata Symbols lazily by mcollina · Pull Request #66015 · nodejs/node

X Title: src,ffi: create fast-call metadata Symbols lazily by mcollina · Pull Request #66015 · nodejs/node

Description: The FFI fast-call wrappers key per-function metadata on raw FFI functions using two per-isolate Symbols (kFastArguments / kFastBufferInvoke) that were declared in src/env_properties.h. Everything in env_properties.h is allocated while the startup snapshot is built, so each Symbol advances the isolate's identity-hash RNG before Object.prototype / Function.prototype receive their snapshot identity hashes. In the snapshot produced for Node 26.4.0+ this shifted those hashes so a function map (a function whose length was redefined) and a plain-object map (an object literal with an accessor) collide in V8's 64-slot NormalizedMapCache. Every store into such objects then misses the inline cache, and the repro reported in the linked issue is roughly 7x slower. Create the two Symbols lazily in the FFI binding's Initialize, on the first run of internalBinding('ffi') at runtime, instead of declaring them in env_properties.h. They are therefore not allocated during snapshot serialization and no longer bias the snapshot's prototype identity hashes. Their export, property layout, and the fast-call feature behavior are unchanged. Fixes #66011 Ai generated, humanly reviewed.

Open Graph Description: The FFI fast-call wrappers key per-function metadata on raw FFI functions using two per-isolate Symbols (kFastArguments / kFastBufferInvoke) that were declared in src/env_properties.h. Everything i...

X Description: The FFI fast-call wrappers key per-function metadata on raw FFI functions using two per-isolate Symbols (kFastArguments / kFastBufferInvoke) that were declared in src/env_properties.h. Everything i...

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