Allow seeing different assembly code for the same function by mstange · Pull Request #5349 · firefox-devtools/profiler

mstange · 2025-01-30T22:04:10Z

Production | Deploy preview - Double-click the first row in the call tree and then click the asm button

If a JS function is JIT compiled multiple times, then it's currently impossible to see the assembly code for each compilation. If you double-click the call node for the function, the assembly view shows an arbitrary compilation. It doesn't even try to find the one with the highest sample count. The same is true for functions that were inlined into multiple different functions.

This PR allows navigating between the different compilations.

I'll make a separate PR to pick the native symbol with the highest sample count.

codecov · 2026-01-08T09:14:49Z

Codecov Report

❌ Patch coverage is 95.83333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 85.75%. Comparing base (ac4bb14) to head (c3eaddf).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
...mponents/app/AssemblyViewNativeSymbolNavigator.tsx	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5349      +/-   ##
==========================================
+ Coverage   85.71%   85.75%   +0.04%     
==========================================
  Files         317      318       +1     
  Lines       31216    31240      +24     
  Branches     8499     8600     +101     
==========================================
+ Hits        26756    26790      +34     
+ Misses       4030     4020      -10     
  Partials      430      430

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A small behavior-neutral change that I've extracted from #5349.

…iew (#5759) [Production](https://share.firefox.dev/4qXrKoY) | [Deploy preview](https://deploy-preview-5759--perf-html.netlify.app/public/f2eatktw200exzsbzps5xg0gpjkb785cjj1yz8r/calltree/?globalTrackOrder=a0978465312&hiddenGlobalTracks=0w8a&hiddenLocalTracksByPid=46164-0w3~46165-0~46175-0~46171-0~46589-0~46180-0~46588-0~46174-0~46168-01~46177-0&range=m29020&thread=e&transforms=ff-1037~ff-1046&v=12) Fixes #5758 and cleans things up a bit. Having the samples passed to `getBottomBoxInfoForCallNode` will also make it easier to address the TODO about picking the native symbol with the highest sample count, but I'll do that in a separate PR (or probably as part of #5349).

mstange · 2026-01-22T03:42:35Z

This is now ready for review.

canova

Nice! Looks good to me, but can we also make the x of y text in the UI localizable?

canova · 2026-01-23T13:06:07Z

src/components/app/AssemblyViewNativeSymbolNavigator.tsx

+    return (
+      <>
+        <h3 className="bottom-box-title-trailer">
+          {index !== null && count > 1 ? `${index + 1} of ${count}` : ''}


Can we also make the x of y string localizable?

Oh right! Added a commit for that.

canova · 2026-01-23T13:08:28Z

src/components/app/AssemblyViewNativeSymbolNavigator.tsx

+    return (
+      <>
+        <h3 className="bottom-box-title-trailer">
+          {index !== null && count > 1 ? `${index + 1} of ${count}` : ''}


Also, index !== null shouldn't be reachable now thanks to the early return above. We can remove it.

Ah yes, fixed.

flodolo

Nazım is correct, we shouldn't have hardcoded English text.

canova

Thanks!

Lots of exciting changes 🎉: [arai-a] Put radio buttons into labels (#5738) [DaniPopes] Update comment for "unique-string" (#5741) [Karan Pradhan] Hide tooltip filter button in non-sticky tooltips and add hideFilterButton tests (#5718) [arai-a] Add a menu to copy the Marker Table as text (#5732) [arai-a] Make the entire list item clickable for the "Full Range" (#5742) [Markus Stange] Move symbol table demangling out of SymbolStore into SymbolProvider (#5746) [Markus Stange] Remove SVG asset imports from profile-data.ts (#5747) [arai-a] Do not apply sticky tooltip on double click (#5754) [arai-a] Skip the ChartCanvas redraw on the Viewport's internal default state usage (#5744) [Markus Stange] Stop blindly extracting uint8array.buffer after calling compress() (#5753) [Markus Stange] In the assembly view state, refer to the current symbol by index (#5755) [Markus Stange] Fix "scroll to hotspot" functionality in the source view + assembly view (#5759) [Markus Stange] Keep the colorField markerSchema field when processing profiles in the gecko format (#5760) [Markus Stange] Implement dark mode (#5740) [Markus Stange] Fix light-mode colors (#5765) [Markus Stange] Tweak dark mode colours. (#5767) [Nazım Can Altınova] Enable some basic type-aware lints (#5775) [Markus Stange] Allow seeing different assembly code for the same function (#5349) [fatadel] Refine tree view a11y (#5779) [fatadel] Align double-click behavior of stack chart with flame graph (#5782) [Markus Stange] Split gz.ts properly into node and browser variants (#5764) [Markus Stange] Simplify and optimize the computation of per-call-node line and address timings (#5770) [Nazım Can Altınova] Move the dark mode toggle to devtools console (#5783) [Nazım Can Altınova] 🔃 Sync: l10n -> main (Jan 27, 2026) (#5785) [Nazım Can Altınova] Improve Chrome importer marker payload logic (#5717) [Markus Stange] Add a Focus Self transform (#5774) [Nazım Can Altınova] Enable the Turkish locale in production (#5786) And huge thanks to our localizers 🎉 : be: Mikalai Udodau de: Ger de: Michael Köhler el: Jim Spentzos en-CA: chutten en-CA: Saurabh en-GB: Ian Neal en-GB: Saurabh es-CL: ravmn fy-NL, nl: Fjoerfoks fr: Skywarp fr: Théo Chevalier fur: Fabio Tomat fy-NL: Fjoerfoks ia: Melo46 it: Francesco Lodolo [:flod] nl: Fjoerfoks nl: Mark Heijl pt-BR: Marcelo Ghelman ru: berry ru: Valery Ledovskoy sv-SE: Andreas Pettersson tr: Grk zh-CN: Olvcpr423 zh-CN: wxie zh-TW: Pin-guang Chen

mstange force-pushed the assembly-view-prev-next branch from 49d95a4 to 139d000 Compare January 31, 2025 05:06

mstange force-pushed the assembly-view-prev-next branch from 139d000 to 74b06df Compare February 14, 2025 04:16

mstange force-pushed the assembly-view-prev-next branch from 74b06df to 39b83d2 Compare February 24, 2025 00:23

mstange force-pushed the assembly-view-prev-next branch from 39b83d2 to 7ea21d4 Compare July 10, 2025 17:55

mstange force-pushed the assembly-view-prev-next branch from 7ea21d4 to 4112ac4 Compare January 8, 2026 09:12

mstange mentioned this pull request Jan 12, 2026

In the assembly view state, refer to the current symbol by index #5755

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mstange force-pushed the assembly-view-prev-next branch 2 times, most recently from f88be1c to 8ecd06e Compare January 14, 2026 20:37

mstange mentioned this pull request Jan 14, 2026

Fix "scroll to hotspot" functionality in the source view + assembly view #5759

Merged

mstange added a commit that referenced this pull request Jan 19, 2026

In the assembly view state, refer to the current symbol by index (#5755)

dd46268

A small behavior-neutral change that I've extracted from #5349.

mstange force-pushed the assembly-view-prev-next branch from 8ecd06e to 1a8f46a Compare January 22, 2026 03:41

mstange marked this pull request as ready for review January 22, 2026 03:42

mstange requested a review from a team as a code owner January 22, 2026 03:42

mstange requested a review from canova January 22, 2026 03:42

mstange self-assigned this Jan 22, 2026

mstange changed the title ~~[Deploy preview] Allow seeing different assembly code for the same function~~ Allow seeing different assembly code for the same function Jan 22, 2026

flodolo approved these changes Jan 23, 2026

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canova reviewed Jan 23, 2026

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flodolo requested changes Jan 23, 2026

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mstange force-pushed the assembly-view-prev-next branch from 1a8f46a to 4a535bc Compare January 23, 2026 15:41

Add prev/next buttons in the assembly view.

f9029f0

mstange force-pushed the assembly-view-prev-next branch from 4a535bc to 65dfc52 Compare January 23, 2026 15:42

mstange requested a review from flodolo January 23, 2026 15:43

flodolo approved these changes Jan 23, 2026

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canova approved these changes Jan 23, 2026

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Make the "x of y" text above the assembly view localizable.

c3eaddf

mstange force-pushed the assembly-view-prev-next branch from 65dfc52 to c3eaddf Compare January 23, 2026 16:21

mstange enabled auto-merge January 23, 2026 16:22

mstange merged commit e927183 into firefox-devtools:main Jan 23, 2026
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canova mentioned this pull request Jan 27, 2026

Deploy January 27, 2026 #5787

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Allow seeing different assembly code for the same function#5349

Allow seeing different assembly code for the same function#5349
mstange merged 2 commits intofirefox-devtools:mainfrom
mstange:assembly-view-prev-next

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