Add a --symbolicate-wasm arg to profiler-edit.#6008
Merged
Conversation
mstange
force-pushed
the
symbolicate-wasm-script
branch
from
52ba22e to
ab1e4b6
Compare
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #6008 +/- ##
==========================================
- Coverage 83.82% 83.79% -0.03%
==========================================
Files 328 329 +1
Lines 34255 34395 +140
Branches 9572 9618 +46
==========================================
+ Hits 28713 28821 +108
- Misses 5114 5145 +31
- Partials 428 429 +1 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
|
mstange
force-pushed
the
symbolicate-wasm-script
branch
3 times, most recently
from
0202adf to
be15b28
Compare
mstange
force-pushed
the
symbolicate-wasm-script
branch
2 times, most recently
from
a70577c to
a8608c4
Compare
canova
approved these changes
May 11, 2026
Member
canova
left a comment
canova
left a comment
There was a problem hiding this comment.
Nice, thanks for adding some tests! I added a bunch of nits to make things a bit clearer, but otherwise I don't see any issues.
This also made me look into the wasm spec a bit and learn more about it, so I think it was a good use of time 😄
This also made me think more about the source map support that I've been working on. These 2 things seem like solving it for 2 different use cases, so it seems very interesting. I didn't know about the name section in the wasm spec. I wonder how devtools handles it (or if it does). It looks like it's mostly looking at the dwarf info for now, but need to look deeper.
Comment on lines
+229
to
+256
| const symbolicateWasm: WasmSymbolicationCliSpec[] = []; | ||
| const rawWasmArg = argv['symbolicate-wasm']; | ||
| let wasmArgs: unknown[]; | ||
| if (rawWasmArg === undefined) { | ||
| wasmArgs = []; | ||
| } else if (Array.isArray(rawWasmArg)) { | ||
| wasmArgs = rawWasmArg; | ||
| } else { | ||
| wasmArgs = [rawWasmArg]; | ||
| } | ||
| for (const arg of wasmArgs) { | ||
| if (typeof arg !== 'string' || arg === '') { | ||
| throw new Error('--symbolicate-wasm requires a value'); | ||
| } | ||
| // Accept "<url>=<path>" if the LHS looks like a URL, otherwise treat the | ||
| // whole string as a path and infer the URL from the profile. Split on | ||
| // the last `=` so URLs containing `=` (e.g. in query strings) survive | ||
| // intact; this assumes file paths don't contain `=`. | ||
| const eqIndex = arg.lastIndexOf('='); | ||
| if (eqIndex !== -1 && /^[a-z]+:\/\//i.test(arg.slice(0, eqIndex))) { | ||
| symbolicateWasm.push({ | ||
| url: arg.slice(0, eqIndex), | ||
| path: arg.slice(eqIndex + 1), | ||
| }); | ||
| } else { | ||
| symbolicateWasm.push({ path: arg }); | ||
| } | ||
| } |
Member
There was a problem hiding this comment.
Not for this PR, but now that we have commander in the package.json, we can possibly simplify these things by using it.
| // Parses the function-name subsection of a wasm "name" custom section and | ||
| // returns a map from function index to name. Returns an empty map if the | ||
| // module has no name section. The function index space includes imports | ||
| // (imports come first) — same numbering used in `wasm-function[N]` strings. |
Member
There was a problem hiding this comment.
Oh can we add a link to the Firefox source code where we generate this N number?
Contributor
Author
There was a problem hiding this comment.
mstange
force-pushed
the
symbolicate-wasm-script
branch
from
a8608c4 to
f845b5b
Compare
This allows applying wasm symbols to existing profiles that were captured with a stripped wasm bundle. The script looks for functions with names of the shape `wasm-function[123]`, which is what Firefox uses when the wasm file doesn't have a names section. Usage: ``` yarn build-node-tools && \ node node-tools-dist/profiler-edit.js -i input.json.gz \ --symbolicate-wasm http://host/a.wasm=./a-unstripped.wasm \ --symbolicate-wasm http://host/b.wasm=./b-unstripped.wasm \ -o out.json.gz ```
mstange
force-pushed
the
symbolicate-wasm-script
branch
from
f845b5b to
b4054d5
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
This allows applying wasm symbols to existing profiles that were captured with a stripped wasm bundle.
The script looks for functions with names of the shape
wasm-function[123], which is what Firefox uses when the wasm file doesn't have a names section.Usage:
I've successfully used it to turn https://share.firefox.dev/4f9O7oh into https://share.firefox.dev/4nd6GKk .