[torque] Introduce @abstract annotation for Torque classes

This annotation indicates that the class itself is not instantiated,
and does not have its own instance type: The instance types that
logically belong to the class are the instance types of the derived
classes.

Currently, we need the indication @dirtyInstantiatedAbstractClass
for several classes that are used as both, abstract base classes
and concrete classes. The prime example is JSObject which is the
base for many other classes, and also serves as the class to allocate
plain JSObjects. The annotation is purposefully ugly because in the
future we should refactor code to make it unnecessary.

Another annotation we introduce is @hasSameInstanceTypeAsParent,
which indicates another design pattern that currently occurs in the
code-base: Some Torque classes have the same instance types as their
parent class, but rename some fields, or possibly have a different map.
In such cases, the parent class is not abstract and the derived classes
can be seen as refinements of this class (that, for example, narrows the
type of a field). In the future, Torque should accomodate this pattern
better, but at moment we are content with just indicating where it is
used.

Bug: v8:7793
Change-Id: I1892dcc7325250df75d80308bf3d767d6d43bcc2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1607761
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61495}
19 files changed
tree: 9d8732d2fa227d78e669cc5a2a3434ddd23fe41f
  1. .clang-format
  2. .clang-tidy
  3. .editorconfig
  4. .git-blame-ignore-revs
  5. .gitattributes
  6. .gitignore
  7. .gn
  8. .vpython
  9. .ycm_extra_conf.py
  10. AUTHORS
  11. BUILD.gn
  12. CODE_OF_CONDUCT.md
  13. ChangeLog
  14. DEPS
  15. LICENSE
  16. LICENSE.fdlibm
  17. LICENSE.strongtalk
  18. LICENSE.v8
  19. LICENSE.valgrind
  20. OWNERS
  21. PRESUBMIT.py
  22. README.md
  23. WATCHLISTS
  24. benchmarks/
  25. build_overrides/
  26. codereview.settings
  27. custom_deps/
  28. docs/
  29. gni/
  30. include/
  31. infra/
  32. samples/
  33. snapshot_toolchain.gni
  34. src/
  35. test/
  36. testing/
  37. third_party/
  38. tools/
README.md

V8 JavaScript Engine

V8 is Google's open source JavaScript engine.

V8 implements ECMAScript as specified in ECMA-262.

V8 is written in C++ and is used in Google Chrome, the open source browser from Google.

V8 can run standalone, or can be embedded into any C++ application.

V8 Project page: https://v8.dev/docs

Getting the Code

Checkout depot tools, and run

    fetch v8

This will checkout V8 into the directory v8 and fetch all of its dependencies. To stay up to date, run

    git pull origin
    gclient sync

For fetching all branches, add the following into your remote configuration in .git/config:

    fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
    fetch = +refs/tags/*:refs/tags/*

Contributing

Please follow the instructions mentioned at v8.dev/docs/contribute.