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denoland-deno/ext/ffi
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Aapo Alasuutari 19e4e821d5
fix(ext/ffi): Fix usize and isize FFI callback parameters missing match arm (#16172) 
Mea culpa. Back when I re-introduced parameter and return value types to
FFI callbacks I failed to properly account for the change in match arm
logic. As a result, usize and isize parameters in FFI callbacks
currently enter the branch meant for void only.

This PR changes the match arms to all be explicit, making sure that void
is the only arm marked unreachable and that it stays that way.
2022-10-07 10:20:18 +05:30
..
00_ffi.js feat(ext/ffi): Support bool FFI type (#15754) 2022-09-05 08:56:52 +05:30
Cargo.toml chore: forward v1.26.1 release commit to main (#16178) 2022-10-06 16:49:40 -04:00
fast_call.rs feat(ext/ffi): Implement FFI fast-call trampoline with Dynasmrt (#15305) 2022-09-07 12:23:56 +05:30
lib.rs fix(ext/ffi): Fix usize and isize FFI callback parameters missing match arm (#16172) 2022-10-07 10:20:18 +05:30
README.md fix(ext/ffi): trampoline for fast calls (#15139) 2022-07-12 06:33:05 +05:30

README.md

deno_ffi

This crate implements dynamic library ffi.

Performance

Deno FFI calls have extremely low overhead (~1ns on M1 16GB RAM) and perform on par with native code. Deno leverages V8 fast api calls and JIT compiled bindings to achieve these high speeds.

Deno.dlopen generates an optimized and a fallback path. Optimized paths are triggered when V8 decides to optimize the function, hence call through the Fast API. Fallback paths handle types like function callbacks and implement proper error handling for unexpected types, that is not supported in Fast calls.

Optimized calls enter a JIT compiled function "trampoline" that translates Fast API values directly for symbol calls. JIT compilation itself is super fast, thanks to tinycc. Currently, the optimized path is only supported on Linux and MacOS.

To run benchmarks:

target/release/deno bench --allow-ffi --allow-read --unstable ./test_ffi/tests/bench.js