Stream: git-wasmtime

Topic: wasmtime / PR #13630 Add a tunable to remove symbols from...

Wasmtime GitHub notifications bot (Jun 13 2026 at 00:19):

alexcrichton opened PR #13630 from alexcrichton:remove-symbolt-able to bytecodealliance:main:

This commit adds a tunable option via -Dsymbols={y,n} or Config::debug_symbols to disable generation of symbols in output *.cwasm artifacts. This can help minimize the size of an artifact to the absolute bare minimum in some scenarios.

This additionally adds documentation of how to build a minimal *.cwasm with all the various options that can be used which affect the output artifact.

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Wasmtime GitHub notifications bot (Jun 13 2026 at 00:19):

alexcrichton requested fitzgen for a review on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 00:19):

alexcrichton requested wasmtime-core-reviewers for a review on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 00:19):

alexcrichton requested wasmtime-fuzz-reviewers for a review on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 00:19):

alexcrichton requested wasmtime-compiler-reviewers for a review on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 00:19):

alexcrichton requested wasmtime-default-reviewers for a review on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 00:19):

alexcrichton edited PR #13630:

This commit adds a tunable option via -Dsymbols={y,n} or Config::debug_symbols to disable generation of symbols in output *.cwasm artifacts. This can help minimize the size of an artifact to the absolute bare minimum in some scenarios.

This additionally adds documentation of how to build a minimal *.cwasm with all the various options that can be used which affect the output artifact.

Closes #10286

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Wasmtime GitHub notifications bot (Jun 13 2026 at 02:35):

github-actions[bot] added the label fuzzing on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 02:35):

github-actions[bot] added the label wasmtime:api on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 02:35):

github-actions[bot] added the label wasmtime:config on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 02:35):

github-actions[bot] added the label wasmtime:docs on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 02:35):

github-actions[bot] added the label winch on PR #13630.

Wasmtime GitHub notifications bot (Jun 13 2026 at 02:35):

github-actions[bot] commented on PR #13630:

Subscribe to Label Action

cc @fitzgen, @saulecabrera

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This issue or pull request has been labeled: "fuzzing", "wasmtime:api", "wasmtime:config", "wasmtime:docs", "winch"

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• saulecabrera: winch

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Wasmtime GitHub notifications bot (Jun 13 2026 at 04:04):

github-actions[bot] commented on PR #13630:

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

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Wasmtime GitHub notifications bot (Jun 13 2026 at 17:55):

alexcrichton updated PR #13630.

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:26):

:speech_balloon: fitzgen created PR review comment:

Maybe note at the start of this paragraph that these are implementation details that are subject to change at any time and should never be relied upon by embedders?

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:26):

:thumbs_up: fitzgen submitted PR review:

r=me with below addressed

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:26):

:speech_balloon: fitzgen created PR review comment:

Not obvious why it might look like that, suggest explicitly adding "because it removed ~24.75M of binary size when compiling the .wasm to .cwasm" or some such

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:26):

:speech_balloon: fitzgen created PR review comment:

Link to https://webassembly.github.io/spec/core/appendix/custom.html#name-section perhaps?

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:26):

:speech_balloon: fitzgen created PR review comment:

I would rephrase "not optimized for this use case" as we have in fact been doing a lot of optimizations for this use case of the last year. It is not tuned for that use case by default, but that is pretty different from being "not optimized for" the use case (which I imagine would make many folks disregard Wasmtime for their use case).

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:26):

:speech_balloon: fitzgen created PR review comment:

Is there some canonical page we can link to for minimizing Rust's binary size? Otherwise this will feel like arcane magical incantations to folks who aren't familiar with rustc flags (which is most people).

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:26):

:speech_balloon: fitzgen created PR review comment:

* Pass `-Dsymbols=n` to diasble symbols used for debugging/profiling in the
  output artifact.

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:26):

:speech_balloon: fitzgen created PR review comment:

Again, I worry that we are sharing implementation details that we don't want people to rely on. Like we can say the same thing but be more vague:

Wasmtime's .cwasm artifacts are designed to integrate with the system's native profiler and other developer tools like wasmtime objdump by default, but this information isn't needed to actually run the program and is safe to remove.

Wasmtime GitHub notifications bot (Jun 15 2026 at 16:30):

:speech_balloon: fitzgen created PR review comment:

I think all these will want to be shell-session instead of bash

Wasmtime GitHub notifications bot (Jun 15 2026 at 17:58):

alexcrichton updated PR #13630.

Wasmtime GitHub notifications bot (Jun 15 2026 at 17:59):

alexcrichton commented on PR #13630:

All excellent suggestions, thanks!

Wasmtime GitHub notifications bot (Jun 15 2026 at 18:11):

alexcrichton added PR #13630 Add a tunable to remove symbols from *.cwasm files to the merge queue.

Wasmtime GitHub notifications bot (Jun 15 2026 at 18:27):

alexcrichton has enabled auto merge for PR #13630.

Wasmtime GitHub notifications bot (Jun 15 2026 at 18:36):

:check: alexcrichton merged PR #13630.

Wasmtime GitHub notifications bot (Jun 15 2026 at 18:36):

alexcrichton removed PR #13630 Add a tunable to remove symbols from *.cwasm files from the merge queue.

Last updated: Jul 29 2026 at 05:03 UTC