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nodejs / llnode

An lldb plugin for Node.js and V8, which enables inspection of JavaScript states for insights into Node.js processes and their core dumps.
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Upcoming metadata changes in V8 7.7 #287

Closed cjihrig closed 1 year ago

cjihrig commented 5 years ago

The V8 7.7 update requires the following adjustments to the postmortem debugging metadata constants:

Refs: https://github.com/nodejs/node/pull/28918

mmarchini commented 4 years ago

Interesting, the type of those fields didn't change, but they are all prefixed by __int. Is the metadata generated for Torque classes prefixed by the the metadata type instead of the field type? That's probably not a good idea, if a field type changes it wouldn't reflect on the metadata name, and we wouldn't have a way to check the type on llnode...

mmarchini commented 4 years ago

class_Symbol__name__Object was removed as well, I'm guessing in this version. Still investigating.

mmarchini commented 4 years ago

So I renamed the String metadata back to their previous names in: https://chromium-review.googlesource.com/c/v8/v8/+/1847783. I also added the missing metadata for symbols. Will update the tests once this is merged to core.

mmarchini commented 4 years ago

If the above gets merged, no changes will be necessary on llnode for 7.7 (and then we can close this issue). I already have patches to fix 7.2, 7.4 and 7.6 (I haven't opened PRs with all of them yet because some are blocked by #303), so once the metadata lands upstream and is backported to core, we'll have llnode working on Node.js v12 :)

No9 commented 1 year ago

@cjihrig We discussed the issue of breaking changes in a recent diagnostics meeting. Is there a process around how these breaking changes are identified and flagged to llnode or do we just rely on the good will of folks like yourself?

cjihrig commented 1 year ago

There used to be a test in core that verified the existence of the metadata used by llnode. However, that test was removed in https://github.com/nodejs/node/commit/9a0aaa610706bfe7aeb2234b085cdcb912403c90. After that, I think @mmarchini had her own way of detecting the breaking changes. You'll definitely want some automated way to detect the breaking changes because they happen frequently with V8 updates.

No9 commented 1 year ago

Cheers @cjihrig - I'll close this and captured your recommendation here https://github.com/nodejs/llnode/issues/412