7f58ced72e
While the overall goal of this commit is to change deoptimization entries into builtins, there are multiple related things happening: - Deoptimization entries, formerly stubs (i.e. Code objects generated at runtime, guaranteed to be immovable), have been converted into builtins. The major restriction is that we now need to preserve the kRootRegister, which was formerly used on most architectures to pass the deoptimization id. The solution differs based on platform. - Renamed DEOPT_ENTRIES_OR_FOR_TESTING code kind to FOR_TESTING. - Removed heap/ support for immovable Code generation. - Removed the DeserializerData class (no longer needed). - arm64: to preserve 4-byte deopt exits, introduced a new optimization in which the final jump to the deoptimization entry is generated once per Code object, and deopt exits can continue to emit a near-call. - arm,ia32,x64: change to fixed-size deopt exits. This reduces exit sizes by 4/8, 5, and 5 bytes, respectively. On arm the deopt exit size is reduced from 12 (or 16) bytes to 8 bytes by using the same strategy as on arm64 (recalc deopt id from return address). Before: e300a002 movw r10, <id> e59fc024 ldr ip, [pc, <entry offset>] e12fff3c blx ip After: e59acb35 ldr ip, [r10, <entry offset>] e12fff3c blx ip On arm64 the deopt exit size remains 4 bytes (or 8 bytes in same cases with CFI). Additionally, up to 4 builtin jumps are emitted per Code object (max 32 bytes added overhead per Code object). Before: 9401cdae bl <entry offset> After: # eager deoptimization entry jump. f95b1f50 ldr x16, [x26, <eager entry offset>] d61f0200 br x16 # lazy deoptimization entry jump. f95b2b50 ldr x16, [x26, <lazy entry offset>] d61f0200 br x16 # the deopt exit. 97fffffc bl <eager deoptimization entry jump offset> On ia32 the deopt exit size is reduced from 10 to 5 bytes. Before: bb00000000 mov ebx,<id> e825f5372b call <entry> After: e8ea2256ba call <entry> On x64 the deopt exit size is reduced from 12 to 7 bytes. Before: 49c7c511000000 REX.W movq r13,<id> e8ea2f0700 call <entry> After: 41ff9560360000 call [r13+<entry offset>] Bug: v8:8661,v8:8768 Change-Id: I13e30aedc360474dc818fecc528ce87c3bfeed42 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2465834 Commit-Queue: Jakob Gruber <jgruber@chromium.org> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org> Reviewed-by: Tobias Tebbi <tebbi@chromium.org> Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Cr-Commit-Position: refs/heads/master@{#70597} |
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| custom_deps | ||
| docs | ||
| gni | ||
| include | ||
| infra | ||
| samples | ||
| src | ||
| test | ||
| testing | ||
| third_party | ||
| tools | ||
| .clang-format | ||
| .clang-tidy | ||
| .editorconfig | ||
| .flake8 | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .gn | ||
| .vpython | ||
| .ycm_extra_conf.py | ||
| AUTHORS | ||
| BUILD.gn | ||
| CODE_OF_CONDUCT.md | ||
| codereview.settings | ||
| COMMON_OWNERS | ||
| DEPS | ||
| ENG_REVIEW_OWNERS | ||
| INFRA_OWNERS | ||
| INTL_OWNERS | ||
| LICENSE | ||
| LICENSE.fdlibm | ||
| LICENSE.strongtalk | ||
| LICENSE.v8 | ||
| MIPS_OWNERS | ||
| OWNERS | ||
| PPC_OWNERS | ||
| PRESUBMIT.py | ||
| README.md | ||
| S390_OWNERS | ||
| 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.