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Seth Brenith 0921e8f28b Reland "Add postmortem debugging helper library"
This is a reland of 517ab73fd7

Updates since original: now compressed pointers passed to the function
GetObjectProperties are required to be sign-extended. Previously, the
function allowed zero-extended values, but that led to ambiguity on
pointers like 0x88044919: is it compressed or is the heap range actually
centered on 0x100000000?

Original change's description:
> 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}

Bug: v8:9376
Change-Id: I866a1cc9d4c34bfe10c7b98462451fe69763cf3f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1717090
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#63008}
2019-07-31 14:30:19 +00:00
benchmarks Add missing owners files 2019-05-31 07:21:01 +00:00
build_overrides [build] Dynamically decide if to use system xcode 2019-07-29 08:20:24 +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 Reland "Add postmortem debugging helper library" 2019-07-31 14:30:19 +00:00
include "Reland x3 [arraybuffer] Rearchitect backing store ownership" 2019-07-31 14:13:59 +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 Reland "Add postmortem debugging helper library" 2019-07-31 14:30:19 +00:00
test Reland "Add postmortem debugging helper library" 2019-07-31 14:30:19 +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 Reland "Add postmortem debugging helper library" 2019-07-31 14:30:19 +00:00
.clang-format
.clang-tidy [tool] Remove unfixed clang-tidy warnings to ease use. 2018-10-26 07:40:32 +00:00
.editorconfig
.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 [build] Dynamically decide if to use system xcode 2019-07-29 08:20:24 +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 random number generator seeding update for macOS 2019-07-26 11:55:01 +00:00
BUILD.gn Reland "Add postmortem debugging helper library" 2019-07-31 14:30:19 +00:00
ChangeLog [release] Merge ChangeLog back to master 2018-12-07 15:41:59 +00:00
CODE_OF_CONDUCT.md
codereview.settings
COMMON_OWNERS [OWNERS] Add solanes@ to COMMON_OWNERS 2019-05-22 13:50:51 +00:00
DEPS Update wasm-spec. 2019-07-31 04:55:35 +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
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.