f537d77845
This introduces a new flag --async-stack-traces, which enables zero-cost async stack traces. This enriches the non-standard Error.stack property with async stack frames computed from walking up the promise chains and collecting all the await suspension points along the way. In Error.stack these async frames are marked with "async" to make it possible to distinguish them from regular frames, for example: ``` Error: Some error message at bar (<anonymous>) at async foo (<anonymous>) ``` It's zero-cost because no additional information is collected during the execution of the program, but only the information already present in the promise chains is used to reconstruct an approximation of the async stack in case of an exception. But this approximation is limited to suspension points at await's in async functions. This depends on a recent ECMAScript specification change, flagged behind --harmony-await-optimization and implied the --async-stack-traces flag. Without this change there's no way to get from the outer promise of an async function to the rest of the promise chain, since the link is broken by the indirection introduced by await. For async functions the special outer promise, named .promise in the Parser desugaring, is now forcible allocated to stack slot 0 during scope resolution, to make it accessible to the stack frame construction logic. Note that this first prototype doesn't yet work fully support async generators and might have other limitations. Bug: v8:7522 Ref: nodejs/node#11865 Change-Id: I0cc8e3cdfe45dab56d3d506be2d25907409b01a9 Design-Document: http://bit.ly/v8-zero-cost-async-stack-traces Reviewed-on: https://chromium-review.googlesource.com/c/1256762 Commit-Queue: Benedikt Meurer <bmeurer@chromium.org> Reviewed-by: Adam Klein <adamk@chromium.org> Reviewed-by: Yang Guo <yangguo@chromium.org> Cr-Commit-Position: refs/heads/master@{#56363} |
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benchmarks | ||
build_overrides | ||
custom_deps | ||
docs | ||
gni | ||
include | ||
infra | ||
samples | ||
src | ||
test | ||
testing | ||
third_party | ||
tools | ||
.clang-format | ||
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.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.