[turbofan] Introduce a new MapGuard operator.

The MapGuard node sits in the effect chain as a hint for other
optimization passes that a certain value has a certain (set of)
map(s) guarded by checks on the control chain. This is useful
to learn from explicit control flow inserted for polymorphic
property accesses, and then used as part of the polymorphic
inlining.

This change improves the score on the Octane/DeltaBlue benchmark
by around 7-8% and the score on the Octane/Richards benchmark by
like 3% on average.

Bug: v8:5267
Change-Id: Id0b0b2c72e6a9342d5750a0d62cf6be6fb8c5916
Also-By: jarin@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/620586
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47417}
11 files changed
tree: 4fffd4cfb87dcc4f26dbac0b8763f254ace3272d
  1. benchmarks/
  2. build_overrides/
  3. docs/
  4. gni/
  5. gypfiles/
  6. include/
  7. infra/
  8. samples/
  9. src/
  10. test/
  11. testing/
  12. third_party/
  13. tools/
  14. .clang-format
  15. .editorconfig
  16. .gitignore
  17. .gn
  18. .ycm_extra_conf.py
  19. AUTHORS
  20. BUILD.gn
  21. ChangeLog
  22. CODE_OF_CONDUCT.md
  23. codereview.settings
  24. DEPS
  25. LICENSE
  26. LICENSE.fdlibm
  27. LICENSE.strongtalk
  28. LICENSE.v8
  29. LICENSE.valgrind
  30. Makefile
  31. Makefile.android
  32. OWNERS
  33. PRESUBMIT.py
  34. README.md
  35. snapshot_toolchain.gni
  36. WATCHLISTS
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://github.com/v8/v8/wiki

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 on the V8 wiki.