Stream: git-wasmtime

Topic: wasmtime / Issue #1940 wasm2obj: exported function names

Wasmtime GitHub notifications bot (Jun 29 2020 at 22:57):

cdisselkoen opened Issue #1940:

Not sure if this is a bug, my own user error, or just a not-implemented-yet.

I have the following minimal Wasm example (hello.wat):

(module
  (func (export "helloFunc") (result i32) (i32.const 42))
)

wasm2obj seems to not respect the declared export function name:

(Linux)
> wasmtime wasm2obj hello.wat hello.o
> nm hello.o
0000000000000000 D _vmcontext_init
0000000000000000 T _wasm_function_0

(macOS)
> wasmtime wasm2obj hello.wat hello.o
> nm hello.o
000000000000000e D __vmcontext_init
0000000000000000 T __wasm_function_0

Instead of _wasm_function_0, I was expecting helloFunc.

This behavior is still the same with the following hello.wat declaring the export a different way:

(module
  (func (result i32) (i32.const 42))
  (export "helloFunc" (func 0))
)

I've tested this on Wasmtime master as of this writing, which is commit c91a9313b. As shown above, I observed this behavior on both Linux and macOS.

Wasmtime GitHub notifications bot (Jun 29 2020 at 23:36):

abrown commented on Issue #1940:

@yurydelendik?

Wasmtime GitHub notifications bot (Jun 30 2020 at 00:53):

cdisselkoen commented on Issue #1940:

Not knowing what I'm doing, my first attempt to fix this (https://github.com/PLSysSec/wasmtime-blade/commit/7494c43099831d581f78909cc5ad13bbf62ec39f) failed to make any difference in my testing.

Wasmtime GitHub notifications bot (Jun 30 2020 at 13:12):

yurydelendik commented on Issue #1940:

Not sure if this is a bug, my own user error, or just a not-implemented-yet.

There is no specification in which form wasm2obj shall produce its output. Currently, wasmtime just packages machine code into object file containers, and adds unique symbols (such as "_wasmtime_0") to mark starts of the functions. AFAIK wasm2obj is used only by developers to troubleshot internals of wasmtime and no intent to be used by end user.

Wasmtime GitHub notifications bot (Jun 30 2020 at 13:14):

yurydelendik edited a comment on Issue #1940:

Not sure if this is a bug, my own user error, or just a not-implemented-yet.

There is no specification in which form wasm2obj shall produce its output. Currently, wasmtime just packages machine code into object file containers, and adds unique symbols (such as _wasm_function_0) to mark starts of the functions. AFAIK wasm2obj is used only by developers to troubleshot internals of wasmtime and no intent to be used by end user.

Wasmtime GitHub notifications bot (Jun 30 2020 at 17:11):

cdisselkoen commented on Issue #1940:

Sure, that sounds reasonable. In that case I can close this issue as it sounds like it's out of scope?

I think Lucet will probably be the tool I'm looking for, even for simple examples (non-WASI code, no external calls).

Wasmtime GitHub notifications bot (Jun 30 2020 at 20:41):

yurydelendik commented on Issue #1940:

In that case I can close this issue as it sounds like it's out of scope?

Yes. Also you may just re-purpose this issue as feature request -- I expect we change the behavior of wasm2obj to be more user friendly.

Wasmtime GitHub notifications bot (Jun 30 2020 at 20:57):

cdisselkoen commented on Issue #1940:

Ok, I will leave this as-is then and let maintainers choose whether to close or edit to a feature request.

Last updated: Dec 23 2024 at 13:07 UTC