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Seth Brenith 517ab73fd7 Add postmortem debugging helper library
This change begins to implement the functionality described in
https://docs.google.com/document/d/1evHnb1uLlSbvHAAsmOXyc25x3uh1DjgNa8u1RHvwVhk/edit#
for investigating V8 state in crash dumps.

This change adds a new library, v8_debug_helper, for providing platform-
agnostic assistance with postmortem debugging. This library can be used
by extensions built for debuggers such as WinDbg or lldb. Its public API
is described by debug-helper.h; currently the only method it exposes is
GetObjectProperties, but we'd like to add more functionality over time.
The API surface is restricted to plain C-style structs and pointers, so
that it's easy to link from a debugger extension built with a different
toolchain.

This change also adds a new cctest file to exercise some basic
interaction with the new library.

The API function GetObjectProperties takes an object pointer (which
could be compressed, or weak, or a SMI), and returns a string
description of the object and a list of properties the object contains.
For now, the list of properties is entirely based on Torque object
definitions, but we expect to add custom properties in future updates so
that it can be easier to make sense of complex data structures such as
dictionaries.

GetObjectProperties does several things that are intended to generate
somewhat useful results even in cases where memory may be corrupt or
unavailable:
- The caller may optionally provide a type string which will be used if
  the memory for the object's Map is inaccessible.
- All object pointers are compared against the list of known objects
  generated by mkgrokdump. The caller may optionally provide the
  pointers for the first pages of various heap spaces, to avoid spurious
  matches. If those pointers are not provided, then any matches are
  prefixed with "maybe" in the resulting description string, such as
  "maybe UndefinedValue (0x4288000341 <Oddball>)".

Bug: v8:9376

Change-Id: Iebf3cc2dea3133c7811bcefcdf38d9458b02fded
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1628012
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62882}
2019-07-23 20:02:16 +00:00
benchmarks Add missing owners files 2019-05-31 07:21:01 +00:00
build_overrides Clean up infra owners 2019-05-15 11:18:43 +00:00
custom_deps Clean up infra owners 2019-05-15 11:18:43 +00:00
docs Add OWNERS for docs/ 2019-05-15 12:06:15 +00:00
gni Add postmortem debugging helper library 2019-07-23 20:02:16 +00:00
include Revert "Reland "Reland "[arraybuffer] Rearchitect backing store ownership""" 2019-07-23 12:25:16 +00:00
infra [test] Add bytecode-expectation test 2019-07-22 08:48:36 +00:00
samples [cleanup] Drop some occurrences of Isolate::Current 2019-06-26 19:39:21 +00:00
src Add postmortem debugging helper library 2019-07-23 20:02:16 +00:00
test Add postmortem debugging helper library 2019-07-23 20:02:16 +00:00
testing Add missing owners files 2019-05-31 07:21:01 +00:00
third_party [DevTools] Roll inspector_protocol (V8). 2019-07-03 10:41:47 +00:00
tools Add postmortem debugging helper library 2019-07-23 20:02:16 +00:00
.clang-format [clang-format] Don't derive pointer alignment 2017-01-17 09:28:19 +00:00
.clang-tidy [tool] Remove unfixed clang-tidy warnings to ease use. 2018-10-26 07:40:32 +00:00
.editorconfig Add .editorconfig 2017-07-28 13:39:24 +00:00
.flake8 Add .flake8 to allow for python style checking. 2019-07-19 21:44:03 +00:00
.git-blame-ignore-revs Add recent code rewrite to .git-blame-ignore-revs 2019-05-23 10:38:45 +00:00
.gitattributes .gitattributes: Mark minified emscripten js files as -diff 2018-09-19 16:27:10 +00:00
.gitignore [wasm-c-api] Un-.gitignore third_party/wasm-api/ 2019-06-17 08:52:37 +00:00
.gn v8: Stop setting secondary_source. 2019-05-13 16:06:53 +00:00
.vpython [tools] Implement confidence-based number of runs 2019-05-09 09:42:28 +00:00
.ycm_extra_conf.py [ycm] Switch from gnu++11 to gnu++14 2017-11-27 07:48:21 +00:00
AUTHORS Update v8 to run on iPhone 2019-07-16 07:31:39 +00:00
BUILD.gn Add postmortem debugging helper library 2019-07-23 20:02:16 +00:00
ChangeLog [release] Merge ChangeLog back to master 2018-12-07 15:41:59 +00:00
CODE_OF_CONDUCT.md Explicitly state that the Chromium Code of Conduct also applies to V8 2016-03-02 09:51:24 +00:00
codereview.settings Make Gerrit the default code review for V8 2017-06-30 17:37:37 +00:00
COMMON_OWNERS [OWNERS] Add solanes@ to COMMON_OWNERS 2019-05-22 13:50:51 +00:00
DEPS Update V8 DEPS. 2019-07-22 03:33:15 +00:00
ENG_REVIEW_OWNERS Add eng review owners as escalation path 2019-05-15 19:12:10 +00:00
INFRA_OWNERS Clean up infra owners 2019-05-15 11:18:43 +00:00
INTL_OWNERS Add missing owners files 2019-05-31 07:21:01 +00:00
LICENSE [wasm] Draft version of C/C++ Wasm API 2019-04-17 16:00:26 +00:00
LICENSE.fdlibm Add LICENSE.fdlibm for all the fdlibm imported sources. 2016-06-09 07:17:03 +00:00
LICENSE.strongtalk
LICENSE.v8
LICENSE.valgrind
MIPS_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
OWNERS Add .flake8 to allow for python style checking. 2019-07-19 21:44:03 +00:00
PPC_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
PRESUBMIT.py Reland "Move logging and diagnostics related source files" 2019-05-20 09:54:57 +00:00
README.md [docs] Change links from old wiki to v8.dev 2019-03-07 12:13:30 +00:00
S390_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
WATCHLISTS Move remaining files in src/ 2019-05-24 18:24:36 +00:00

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://v8.dev/docs

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 at v8.dev/docs/contribute.