ABI compatibility tool

[hashseed]

ABI stability is a hard requirement when upgrading V8 within the same Node branch. This is so that native modules that uses V8 APIs and built for a particular Node branch do not need to be rebuilt.

So far, we've been mostly ensured ABI stability through intensive eyeballing of changes to deps/v8/include/*.h and by running CITGM. This is tedious and could yield false positives.

I have played around a bit with this ABI compliance checker, requiring some tweaking of V8's build files and an additional GN arg (use_debug_fission = false).

Using that tool is fairly inconvenient, very slow (took me like some 20 minutes), and the result is not all that useful. It is a good start, but

• does not find differences in the constants in v8.h.
• includes changes to all header files in v8, not just ones in v8/include.

I'm neither an expert on DWARF nor on binary compatibility, so some contribution and help here would be greatly appreciated. Alternative here is to wait until every native module has migrated to n-api, but in the meantime...

[vsnehil92]

I would like to work on this issue. Please @hashseed can you give me guidance on this

[hashseed]

Thanks for the interest!

There is not a lot of guidance that I can offer besides the small set of rules described here for ABI compatibility.

I was imagining something either based on the ABI compliance checker mentioned above, or something based on nm or objdump.

[bmsdave]

@vsnehil92 do you need help with this task? I can't imagine how to approach it) but the problem seems interesting)
If you want, I can try to help.

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