06ba822ead
This adds support for integrity level transitions (preventExtensions,
seal and freeze) to MapUpdater and Map::TryUpdate.
In both cases, we first try to detect whether there were integrity
level transitions in the transition tree to the old map and make note
of the most restrictive integrity transition and the map just before
the transition (integrity-source-map). Then we find an appropriate root
(based on integrity-source-map's elements kind) and replay the
transitions based on the integrity-source-map's descriptor
array. Finally, if we saw an integrity level transition in
the beginning, we will find-or-create that transition (on the
updated version of integrity-source-map).
For the following micro-benchmark, we get about 10x speedup.
```
function C() {
this.x = 1;
Object.seal(this);
this.x = 0.1;
}
const start = Date.now();
for (let i = 0; i < 1e7; i++) {
new C();
}
console.log("Reconfigure sealed: " + (Date.now() - start));
```
Before:
> Reconfigure sealed: 5202
After:
> Reconfigure sealed: 479
Bug: v8:8538
Change-Id: If695be7469d8b6ccd44ac4528be8aa34b65b3e4d
Reviewed-on: https://chromium-review.googlesource.com/c/1442640
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59295}
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| benchmarks | ||
| build_overrides | ||
| custom_deps | ||
| docs | ||
| gni | ||
| include | ||
| infra | ||
| samples | ||
| src | ||
| test | ||
| testing | ||
| third_party | ||
| tools | ||
| .clang-format | ||
| .clang-tidy | ||
| .editorconfig | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .gn | ||
| .vpython | ||
| .ycm_extra_conf.py | ||
| AUTHORS | ||
| BUILD.gn | ||
| ChangeLog | ||
| CODE_OF_CONDUCT.md | ||
| codereview.settings | ||
| DEPS | ||
| LICENSE | ||
| LICENSE.fdlibm | ||
| LICENSE.strongtalk | ||
| LICENSE.v8 | ||
| LICENSE.valgrind | ||
| OWNERS | ||
| PRESUBMIT.py | ||
| README.md | ||
| snapshot_toolchain.gni | ||
| WATCHLISTS | ||
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.