[debug] Update code-coverage / type-profile to work with lazy feedback

Precise code-coverage, collecting type profile and logging function events
need feedback vectors. This cl allocates feedback vector eagerly when any of
these features are required. When the code-coverage mode changes to anything
other than best case, this scans over the entire heap and allocates feedback
vectors for the required functions.

For best case code coverage we use interrupt budget field on the feedback
cell to infer if a function has executed. We still use the invocation count
on the feedback vector if feedback vector is available.

Bug: v8:8394
Change-Id: Ia0e656aaaa024d6d893a5badafc9a42ce36e9ea3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1601143
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61410}
2 files changed
tree: 66961f30089136c495b9986beafc00fec06367b7
  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
  11. BUILD.gn
  13. ChangeLog
  14. DEPS
  16. LICENSE.fdlibm
  17. LICENSE.strongtalk
  18. LICENSE.v8
  19. LICENSE.valgrind
  20. OWNERS
  21. PRESUBMIT.py
  22. README.md
  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/

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/*


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