[turbofan] Improve CheckedInt32Mod lowering.

The CheckedInt32Mod lowering in the EffectControlLinearizer wasn't
playing well with subsequent optimizations in the MachineOperatorReducer
especially due to the use of Int32Mod, which introduces another (floating)
diamond in the MachineOperatorReducer. Switching to Uint32Mod and explicit
sign handling fixes the problem, plus we also do the mask trick in the
case where the left hand side is negative now.

With this change the performance on the benchmark mentioned in the bug
report goes from

  console.timeEnd: binary, 1872.346000
  console.timeEnd: modulo, 5967.464000
  console.timeEnd: binary, 6006.789000
  console.timeEnd: modulo, 6293.496000
  console.timeEnd: binary, 5969.264000
  console.timeEnd: modulo, 6291.874000


  console.timeEnd: binary, 1876.464000
  console.timeEnd: modulo, 5846.643000
  console.timeEnd: binary, 5962.545000
  console.timeEnd: modulo, 5972.639000
  console.timeEnd: binary, 5958.221000
  console.timeEnd: modulo, 5973.171000

so even the peak performance of the modulus is now mostly the same as
the binary bitwise and.

Bug: v8:8069
Change-Id: Iaf3828fc0f6c53352367e8bf6c42534f8b13bfb3
Reviewed-on: https://chromium-review.googlesource.com/1180971
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55211}
2 files changed
tree: 25a6a136f6d05e0a41f308cac964adbda58c1317
  1. benchmarks/
  2. build_overrides/
  3. custom_deps/
  4. docs/
  5. gni/
  6. include/
  7. infra/
  8. samples/
  9. src/
  10. test/
  11. testing/
  12. third_party/
  13. tools/
  14. .clang-format
  15. .editorconfig
  16. .git-blame-ignore-revs
  17. .gitattributes
  18. .gitignore
  19. .gn
  20. .vpython
  21. .ycm_extra_conf.py
  23. BUILD.gn
  24. ChangeLog
  26. codereview.settings
  27. DEPS
  29. LICENSE.fdlibm
  30. LICENSE.strongtalk
  31. LICENSE.v8
  32. LICENSE.valgrind
  33. OWNERS
  34. PRESUBMIT.py
  35. README.md
  36. snapshot_toolchain.gni

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/*


Please follow the instructions mentioned on the V8 wiki.