Support for production profiles

[zacharyfmarion]

Adds support for properly symbolicating production profiles taken with hermes. In production mode, hermes produces a slightly different profile format, where instead of line + column information it has funcVirtAddr and offset. As far as I can tell you can easily map this back to line and column by doing:

{
  line: 1, // always 1 for production hermes builds for now according to metro
  column: funcVirtAddr + offset + 1,
}

References:

• metro-symbolicate
• sentry-react-native

Profiles taken with react-native-release-profiler. An example profile + sourcemap can be found here.

Demo

Speedscope now has first class support for both the raw and transformed hermes profile formats, it was used for the comparisons:

Before:

After:

[zacharyfmarion]

@saphal1998 would you mind taking a look at this when you get a chance?

[saphal1998]

Hey @zacharyfmarion I don't currently have the permission to publish this package, I think @grabbou might be a better person to coordinate this with, but these changes do seem great and thank you so much for raising this PR :)

[zacharyfmarion]

Okay thanks! FYI there is also an ongoing thread here about this change: https://github.com/facebook/hermes/discussions/1226#discussioncomment-8074520

[Szymon20000]

@zacharyfmarion I've added that code to the react-native-release-profiler https://github.com/margelo/react-native-release-profiler/pull/1