Sourceless vm.Script compilation/load

[danielgindi]

Is your feature request related to a problem? Please describe.
Not exactly a problem, but a capability that I'd like to have in Node.js out of the box (Otherwise we need to recompile it).

Describe the solution you'd like
Currently pkg is adding a flag "sourceless" that allows compiling a vm.Script without requiring keeping the sources around. When you load the compiled script, it works and has no JS sources attached.
It does so with this patch:
https://github.com/zeit/pkg-fetch/blob/master/patches/node.v10.4.1.cpp.patch

There's much more going on in the patch, like adding pkg's bootstrap code, or using its wrapped fs/child_process functions, which is not the issue here and is not of interest for this feature request.

A cleaner patch file, exported to a gist by me can be found here: v10.x v11.x

Describe alternatives you've considered
I've tried passing dummy scripts to new vm.Script when loading the cached data, but the cachedData is rejected.
It also has the culprit of CPU compatibility, as by default node only loads the cachedData if the CPU features matches exactly, for performance reasons. Whereas pkg allows loading as long as the current CPU has at least the features of the CPU it compiled on. So it has binary compatibility, but may not use new CPU features.

I'm aware of the fact that loading sourceless compiled scripts will have some kind of a performance hit, but it's acceptable in cases where you want to have complete obfuscation, or if you want to avoid the load/parse/compile time of a huge JS script, or any other case where you might want/need to transport binaries instead of sources.

[bnoordhuis]

Any feature request that requires changes to V8 should be contributed to that project first. We'll eventually pick them up when we upgrade or, if necessary, they could be back-ported.

[danielgindi]

@bnoordhuis I'm much less familiar with V8's codebase. What's the procedure there?

[devsnek]

https://www.chromium.org/developers/contributing-code

https://v8.dev/docs/contribute

[danielgindi]

https://chromium-review.googlesource.com/c/v8/v8/+/1462961

[danielgindi]

v8's contribution process is terrible. You have to have a whole suite of tools (that do not work out of the box) just to submit a PR. And then you have to select the people who are supposed to review it. How the hell would I know? I ended up selecting some "recommended" names...

[hashseed]

Fwiw you never really submitted your CL for review. It is still "work in progress". I just happened to come across it to give some comments.

[danielgindi]

@hashseed What do you mean? I did it like in the "How to contribute" guide...

[danielgindi]

@hashseed Also I did fix some of the issues there, and commented on other comments you had

[TimothyGu]

@danielgindi You have to hit the “Start Review” button.

[danielgindi]

I see. Thank you. I was under the impression that "Start Review" is for the reviewer... Amazing UX.

@hashseed I've rebased on master to resolve the conflicts as the code was touched in the same area, but I do not know how commit 6cb174b4 affects it as they removed the cpu features sanity check (was it moved somewhere else?).