wasmtime / PR #9052 s390x: Support tail calls · git-wasmtime

Stream: git-wasmtime

Topic: wasmtime / PR #9052 s390x: Support tail calls

Wasmtime GitHub notifications bot (Jul 31 2024 at 15:11):

uweigand requested elliottt for a review on PR #9052.

Wasmtime GitHub notifications bot (Jul 31 2024 at 15:11):

uweigand opened PR #9052 from uweigand:s390x-tailcall to bytecodealliance:main:

This adds support for a newly defined tail-call ABI for s390x as well as supporting tail calls themselves.

We now use the tail-call ABI by default for Wasmtime, and enable tail calls by default.

This also allows getting rid of a number of special case and test exclusions for s390x.

Fixes: https://github.com/bytecodealliance/wasmtime/issues/6530

Wasmtime GitHub notifications bot (Jul 31 2024 at 15:11):

uweigand requested wasmtime-compiler-reviewers for a review on PR #9052.

Wasmtime GitHub notifications bot (Jul 31 2024 at 15:11):

uweigand requested wasmtime-core-reviewers for a review on PR #9052.

Wasmtime GitHub notifications bot (Jul 31 2024 at 17:44):

github-actions[bot] commented on PR #9052:

Subscribe to Label Action

cc @cfallin, @fitzgen

<details>
This issue or pull request has been labeled: "cranelift", "cranelift:area:machinst", "isle", "wasmtime:api", "wasmtime:config"

Thus the following users have been cc'd because of the following labels:

cfallin: isle

fitzgen: isle

To subscribe or unsubscribe from this label, edit the <code>.github/subscribe-to-label.json</code> configuration file.

Learn more.
</details>

Wasmtime GitHub notifications bot (Jul 31 2024 at 17:44):

github-actions[bot] commented on PR #9052:

Label Messager: wasmtime:config

It looks like you are changing Wasmtime's configuration options. Make sure to
complete this check list:

[ ] If you added a new Config method, you wrote extensive documentation for
it.

<details>

Our documentation should be of the following form:

```text
Short, simple summary sentence.

More details. These details can be multiple paragraphs. There should be
information about not just the method, but its parameters and results as
well.

Is this method fallible? If so, when can it return an error?

Can this method panic? If so, when does it panic?

Example

Optional example here.
```

</details>

[ ] If you added a new Config method, or modified an existing one, you
ensured that this configuration is exercised by the fuzz targets.

<details>

For example, if you expose a new strategy for allocating the next instance
slot inside the pooling allocator, you should ensure that at least one of our
fuzz targets exercises that new strategy.

Often, all that is required of you is to ensure that there is a knob for this
configuration option in [wasmtime_fuzzing::Config][fuzzing-config] (or one
of its nested structs).

Rarely, this may require authoring a new fuzz target to specifically test this
configuration. See [our docs on fuzzing][fuzzing-docs] for more details.

</details>

[ ] If you are enabling a configuration option by default, make sure that it
has been fuzzed for at least two weeks before turning it on by default.

[fuzzing-config]: https://github.com/bytecodealliance/wasmtime/blob/ca0e8d0a1d8cefc0496dba2f77a670571d8fdcab/crates/fuzzing/src/generators.rs#L182-L194
[fuzzing-docs]: https://docs.wasmtime.dev/contributing-fuzzing.html

<details>

To modify this label's message, edit the <code>.github/label-messager/wasmtime-config.md</code> file.

To add new label messages or remove existing label messages, edit the
<code>.github/label-messager.json</code> configuration file.

Learn more.

</details>

Wasmtime GitHub notifications bot (Aug 01 2024 at 18:27):

fitzgen submitted PR review:

Nice!

I didn't evaluate the details of the calling convention, as s390x isn't my area of expertise, but everything looks great in general, and I was very pleased to see the updates to the runtests and fuzzgen. Couple nitpick-y suggestions below, but I think this is basically good to go.

Thanks, Ulrich!!

Wasmtime GitHub notifications bot (Aug 01 2024 at 18:27):

fitzgen submitted PR review:

Nice!

I didn't evaluate the details of the calling convention, as s390x isn't my area of expertise, but everything looks great in general, and I was very pleased to see the updates to the runtests and fuzzgen. Couple nitpick-y suggestions below, but I think this is basically good to go.

Thanks, Ulrich!!

Wasmtime GitHub notifications bot (Aug 01 2024 at 18:27):

fitzgen created PR review comment:

What cases is this matching? I think it might be better to explicitly list them, rather than using _, so that if more MemArg variants are added in the future we don't forget to consider/update this case.

Wasmtime GitHub notifications bot (Aug 01 2024 at 18:27):

fitzgen created PR review comment:

We don't always have a return area pointer, so I think this should return an Option<Reg> and let callers do the unwrap if they have knowledge of why it definitely exists in their specific case.
    /// Get the return area pointer register, if any.
    pub fn ret_area_ptr(&self) -> Option<Reg> {
        self.ret_area_ptr
    }

Wasmtime GitHub notifications bot (Aug 01 2024 at 18:27):

fitzgen created PR review comment:

Can we add some documentation for what the nominal SP is and what its relation to the actual SP is? This was something that I always forgot the nitty-gritty details of in the old system, so if we are bringing part of it back, I think it would be helpful to have comments spelling those things out.

Wasmtime GitHub notifications bot (Aug 01 2024 at 18:27):

fitzgen created PR review comment:

\o/

Wasmtime GitHub notifications bot (Aug 01 2024 at 18:27):

fitzgen created PR review comment:

And then this external constructor could be called unwrap_abi_ret_area_ptr or some such.

Wasmtime GitHub notifications bot (Aug 01 2024 at 19:31):

uweigand updated PR #9052.

Wasmtime GitHub notifications bot (Aug 01 2024 at 19:40):

uweigand updated PR #9052.

Wasmtime GitHub notifications bot (Aug 01 2024 at 19:58):

uweigand commented on PR #9052:

Thanks for the review, @fitzgen ! The latest version should address all review comments.

Wasmtime GitHub notifications bot (Aug 01 2024 at 20:06):

fitzgen submitted PR review:

Thanks!

Wasmtime GitHub notifications bot (Aug 01 2024 at 20:22):

fitzgen merged PR #9052.

Last updated: Dec 23 2024 at 13:07 UTC