Joey Gouly (Mar 12 2020 at 10:40): Joey Gouly (Mar 12 2020 at 10:40):With WASI, some calls from wasm will end up running non-wasm code, right? Is it possible to know from the cranelift side, which of the calls those will be? I guess that the RelocationSink might be able to give that info? I think I'd also need to know the signature of the function too.
Dan Gohman (Mar 12 2020 at 13:17):While it's theoretically possible to specialize calls to known imports like WASI, right now we don't, so all calls to wasm imports look the same from Cranelift's perspective.
Joey Gouly (Mar 12 2020 at 13:26):Dan Gohman said:
While it's theoretically possible to specialize calls to known imports like WASI, right now we don't, so all calls to wasm imports look the same from Cranelift's perspective.
Do you know what kind of steps it would take? Would there need to be changes in cranelift? Or just in wasmtime?
Joey Gouly (Mar 12 2020 at 13:27):I don't think I'd need to change codegen, just get the information on the side
Dan Gohman (Mar 12 2020 at 13:29):The tricky part is that import resolution isn't normally performed until instantiation time, which is after Cranelift has run.
Dan Gohman (Mar 12 2020 at 13:31):And while the end-user side of this is still being worked on, at the engine level, imports to functions with WASI names could be interoposed by other wasm modules.
Dan Gohman (Mar 12 2020 at 13:34):So, we could have a mode where we tell Cranelift it can assume that some APIs won't be interoposed if we needed to.
Joey Gouly (Mar 12 2020 at 13:34):The goal would be a list of function addresses and signatures that are not wasm compiled code, I don't really care if it's a wasi function or not
Dan Gohman (Mar 12 2020 at 13:35):Those addresses aren't computed until instantiation time.
Joey Gouly (Mar 12 2020 at 13:35):that's fine, would just want them before the code is run
Dan Gohman (Mar 12 2020 at 13:37):Ah, ok. See resolve_imports in crates/jit/src/imports.rs
Joey Gouly (Mar 12 2020 at 13:40):Oh, looks like it has the address and signature there, nice!
Joey Gouly (Mar 12 2020 at 13:41):Oh wait, these imports could be from other wasm modules, right?
Dan Gohman (Mar 12 2020 at 13:41):Yes
Joey Gouly (Mar 12 2020 at 13:42):I guess I could collect all the addresses and try work out the address of all wasm functions, and remove them from that set
Dan Gohman (Mar 12 2020 at 13:44):Can you say more about your use case?
Joey Gouly (Mar 12 2020 at 13:44):I'll PM you
clearloop (Jan 13 2021 at 14:41):Hi there, would anybody check issue#2578?
https://github.com/bytecodealliance/wasmtime/issues/2578
clearloop (Jan 14 2021 at 04:10):Is there any example of converting a fn with &[Val] as parameters into a Func?
fitzgen (he/him) (Jan 19 2021 at 18:55):@clearloop https://docs.rs/wasmtime/0.21.0/wasmtime/struct.Func.html#method.new should do the trick
Last updated: Oct 23 2024 at 20:03 UTC