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wasmtime/crates/jit
Alex Crichton 348c597a8e Remove global state for trap registration (#909)
* Remove global state for trap registration

There's a number of changes brought about in this commit, motivated by a
few things. One motivation was to remove an instance of using
`lazy_static!` in an effort to remove global state and encapsulate it
wherever possible. A second motivation came when investigating a
slowly-compiling wasm module (a bit too slowly) where a good chunk of
time was spent in managing trap registrations.

The specific change made here is that `TrapRegistry` is now stored
inside of a `Compiler` instead of inside a global. Additionally traps
are "bulk registered" for a module rather than one-by-one. This form of
bulk-registration allows optimizing the locks used here, where a lock is
only held for a module at-a-time instead of once-per-function.

With these changes the "unregister" logic has also been tweaked a bit
here and there to continue to work. As a nice side effect the `Compiler`
type now has one fewer field that requires actual mutability and has
been updated for multi-threaded compilation, nudging us closer to a
world where we can support multi-threaded compilation. Yay!

In terms of performance improvements, a local wasm test file that
previously took 3 seconds to compile is now 10% faster to compile,
taking ~2.7 seconds now.

* Perform trap resolution after unwinding

This avoids taking locks in signal handlers which feels a bit iffy...

* Remove `TrapRegistration::dummy()`

Avoid an case where you're trying to lookup trap information from a
dummy module for something that happened in a different module.

* Tweak some comments
2020-02-06 12:40:50 -06:00
..
2020-02-06 12:25:32 -06:00
2019-11-08 06:35:40 -08:00
2019-11-08 06:35:40 -08:00

This is the wasmtime-jit crate, which contains JIT-based execution for wasm, using the wasm ABI defined by wasmtime-environ and the runtime support provided by wasmtime-runtime.