[wasm][gc] Fix NativeModule::GetCode for nonexisting code

{NativeModule::GetCode} can actually return {nullptr} if no code was
compiled yet for a function, e.g. in asm.js where we use lazy
compilation. In that case, we must not try to increment the ref count
on the nonexisting code object.

We had a few errors recently that were hard to reproduce because we do
not have a flag to enable code logging. Clusterfuzz managed to
accomplish this by passing --trace-ic.
In order to test bugs in code logging properly, this CL introduces a
new runtime function called "EnableCodeLoggingForTesting". It registers
a noop {CodeEventListener} and enables code logging in the wasm engine.
We should whitelist this flag in ClusterFuzz to potentially flush out
more bugs.

R=mstarzinger@chromium.org
CC=frgossen@chromium.org

Bug: v8:8217, chromium:961129, chromium:961245, chromium:961128
Change-Id: I2f97c109db70b41531d58580b71f6781beeb8dcb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1602700
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61404}
4 files changed
tree: 5a4f6d989bd6b6f12a88c826489d7b7170fca006
  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.