[x64] Implement partial constant pool for x64.

Partial constant pool aims at reducing code size and only takes effect for shareable constants.
Different from ARM’s constant pool, partial constant pool does not emit constant pools at the end of each code object. Instead, it keeps the first shareable constant inlined in the instructions and uses rip-relative memory loadings for the same constants in subsequent instructions. These rip-relative memory loadings will target at the position of the first inlined constant. For example:

  REX.W movq r10,0x7f9f75a32c20	  ; 10 bytes
  …
  REX.W movq r10,0x7f9f75a32c20	  ; 10 bytes
  …
turns into

  REX.W movq r10,0x7f9f75a32c20	  ; 10 bytes
  …
  REX.W movq r10,[rip+0xffffff96] ; 7 bytes
  …


Change-Id: I25a417f6d82da96024989bddf0451d7df9340c00
Reviewed-on: https://chromium-review.googlesource.com/1082231
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Shiyu Zhang <shiyu.zhang@intel.com>
Cr-Commit-Position: refs/heads/master@{#54963}
5 files changed
tree: 40257b4d0a62e9bcfd4e43481af77ed1c5ed83cf
  1. .clang-format
  2. .editorconfig
  3. .git-blame-ignore-revs
  4. .gitattributes
  5. .gitignore
  6. .gn
  7. .vpython
  8. .ycm_extra_conf.py
  9. AUTHORS
  10. BUILD.gn
  11. CODE_OF_CONDUCT.md
  12. ChangeLog
  13. DEPS
  14. LICENSE
  15. LICENSE.fdlibm
  16. LICENSE.strongtalk
  17. LICENSE.v8
  18. LICENSE.valgrind
  19. OWNERS
  20. PRESUBMIT.py
  21. README.md
  22. WATCHLISTS
  23. benchmarks/
  24. build_overrides/
  25. codereview.settings
  26. custom_deps/
  27. docs/
  28. gni/
  29. include/
  30. infra/
  31. samples/
  32. snapshot_toolchain.gni
  33. src/
  34. test/
  35. testing/
  36. third_party/
  37. 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://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.