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Manos Koukoutos 52f6529634 [wasm-gc] Change ValueType representation to account for new types
Motivation:
Changes to the typed function references and gc proposals solidified
the notion of heap type, clarified nullable vs. non-nullable reference
types, and introduced rtts, which contain an integer depth field in
addition to a heap type. This required us to overhaul our ValueType
representation, which results in extensive changes.

To keep this CL "small", we do not try to implement the binary encoding
as described in the proposals, but rather devise a simpler one of our
own (see below). Also, we do not try to implement additional
functionality for the new types.

Changes:
- Introduce HeapType. Move heap types from ValueType to HeapType.
- Introduce Nullability for reference types.
- Rework ValueType helper methods.
- Introduce rtts in ValueType with an integer depth field. Include depth
  in the ValueType encoding.
- Make the constructor of ValueType private, instead expose static
  functions which explicitly state what they create.
- Change every switch statement on ValueType::Kind. Sometimes, we need
  nested switches.
- Introduce temporary constants in ValueTypeCode for nullable types,
  use them for decoding.
- In WasmGlobalObject, split 'flags' into 'raw_type' and 'is_mutable'.
- Change IsSubtypeOfRef to IsSubtypeOfHeap and implement changes in
  subtyping.
- kWasmFuncRef initializers are now non-nullable. Initializers are
  only required to be subtypes of the declared global type.
- Change tests and fuzzers as needed.

Bug: v8:7748
Change-Id: If41f783bd4128443b07e94188cea7dd53ab0bfa5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2247657
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68408}
2020-06-18 12:04:08 +00:00
build_overrides tracing: Enable using Perfetto client library from Chromium 2020-05-11 11:17:57 +00:00
custom_deps Use relative paths to OWNERS files 2019-08-12 13:52:52 +00:00
docs Add OWNERS for docs/ 2019-05-15 12:06:15 +00:00
gni Integrate fuzzilli into v8 2020-06-03 09:53:24 +00:00
include Revert "cppgc: Properly clear (Weak)Peristent and WeakMember pointers" 2020-06-17 18:20:46 +00:00
infra Migrate v8_linux64_msan_rel to next-gen format 2020-05-15 14:13:12 +00:00
samples cppgc: Introduce AllocationHandle 2020-06-10 23:11:20 +00:00
src [wasm-gc] Change ValueType representation to account for new types 2020-06-18 12:04:08 +00:00
test [wasm-gc] Change ValueType representation to account for new types 2020-06-18 12:04:08 +00:00
testing Roll v8/third_party/googletest/src/ 10b1902d8..e3f0319d8 (43 commits) 2020-04-15 07:23:10 +00:00
third_party [torque] format namespaces without indentation 2020-05-12 14:06:17 +00:00
tools [tools] Map search bar feature added, map id changed from int to string 2020-06-18 11:09:21 +00:00
.clang-format
.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 [infra] Update .git-blame-ignore-revs 2020-03-03 12:59:13 +00:00
.gitattributes .gitattributes: Mark minified emscripten js files as -diff 2018-09-19 16:27:10 +00:00
.gitignore Add third_party/jsoncpp/source to .gitignore 2020-04-29 07:20:41 +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 Fix ycm config for headers without source 2019-12-09 11:59:21 +00:00
AUTHORS [tools] Map search bar feature added, map id changed from int to string 2020-06-18 11:09:21 +00:00
BUILD.gn Reland "cppgc,heap: Implement atomic unified heap GC" 2020-06-17 11:02:38 +00:00
CODE_OF_CONDUCT.md
codereview.settings
COMMON_OWNERS [owners] Add thibaudm and ecmziegler to COMMON_OWNERS 2020-05-20 18:41:54 +00:00
DEPS Roll test262 2020-06-18 09:39:51 +00:00
ENG_REVIEW_OWNERS Add eng review owners as escalation path 2019-05-15 19:12:10 +00:00
INFRA_OWNERS Remove myself from owners 2019-12-12 14:22:32 +00:00
INTL_OWNERS add ftang as owner 2020-04-24 19:19:36 +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 syg@chromium.org as DEPS owner for test262 rolls 2019-09-17 19:29:11 +00:00
PPC_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
PRESUBMIT.py Remove the #undef check from the Presubmit for .cc files 2020-01-24 15:24:51 +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 Stop watching for API changes in WATCHLISTS 2020-04-08 07:06:45 +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.