da7322c05f
With very few exceptions, this verifies all skipped write-barriers in CSA and Torque, showing that the MemoryOptimizer together with some type information on the stored value are enough to avoid unsafe skipped write-barriers. Changes to CSA: SKIP_WRITE_BARRIER and Store*NoWriteBarrier are verified by the MemoryOptimizer by default. Type information about the stored values (TNode<Smi>) is exploited to safely skip write barriers for stored Smi values. In some cases, the code is re-structured to make it easier to consume for the MemoryOptimizer (manual branch and load elimination). Changes to the MemoryOptimizer: Improve the MemoryOptimizer to remove write barriers: - When the store happens to a CSA-generated InnerAllocate, by ignoring Bitcasts and additions. - When the stored value is the HeapConstant of an immortal immovable root. - When the stored value is a SmiConstant (recognized by BitcastToTaggedSigned). - Fast C-calls are treated as non-allocating. - Runtime calls can be white-listed as non-allocating. Remaining missing cases: - C++-style iterator loops with inner pointers. - Inner allocates that are reloaded from a field where they were just stored (for example an elements backing store). Load elimination would fix that. - Safe stored value types that cannot be expressed in CSA (e.g., Smi|Hole). We could handle that in Torque. - Double-aligned allocations, which are not lowered in the MemoryOptimizer but in CSA. Drive-by change: Avoid Smi suffix for StoreFixedArrayElement since this can be handled by overload resolution (in Torque and C++). R=jarin@chromium.org TBR=mvstanton@chromium.org Change-Id: I0af9b710673f350e0fe81c2e59f37da93c024b7c Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1571414 Commit-Queue: Tobias Tebbi <tebbi@chromium.org> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org> Cr-Commit-Position: refs/heads/master@{#61016} |
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| 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://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.