V8 x64 backend doesn't emit ABI compliant stack frames

On 64 bit Windows, the OS stack walking does not work because the V8 x64
backend doesn't emit unwinding info and also because it doesn't emit ABI
compliant stack frames. See
for more details.

This problem can be fixed by observing that V8 frames usually all have the same
prolog and epilog:

push rbp,
mov rbp, rsp
pop rbp
ret N

and that it is possible to define XDATA (UNWIND_CODEs) that specify how Windows
should walk through V8 frames. Furthermore, since V8 Code objects are all
allocated in the same code-range for an Isolate, it is possible to register a
single PDATA/XDATA entry to cover stack walking for all the code generated
inside that code-range.

This PR contains changes required to enable stack walking on Win64:

EmbeddedFileWriter now adds assembler directives to the builtins
snapshot source file (embedded.cc) to emit additional entries in the .pdata and
in the .xdata section of the V8 executable. This takes care of stack walking
for embedded builtins. (The case of non-embedded builtins is not supported).
The x64 Assembler has been modified to collect the information required to emit
this unwind info for builtins.

Stack walking for jitted code is handled is Isolate.cpp, by registering
dynamically PDATA/XDATA for the whole code-range address space every time a new
Isolate is initialized, and by unregistering them when the Isolate is

Stack walking for WASM jitted code is handled is the same way in
wasm::NativeModule (wasm/wasm-code-manager.cpp).

It is important to note that Crashpad and Breakpad are already registering
PDATA/XDATA to manage and report unhandled exceptions (but not for embedded
builtins). Since it is not possible to register multiple PDATA entries for the
same address range, a new function is added to the V8 API:
SetUnhandledExceptionCallback() can be used by an embedder to register its own
unhandled exception handler for exceptions that arise in v8-generated code.
V8 embedders should be modified accordingly (code for this is in a separate PR
in the Chromium repository:

All these changes are experimental, behind:

the 'v8_win64_unwinding_info' build flag, and
the '--win64-unwinding-info' runtime flag.

Bug: v8:3598
Change-Id: Iea455ab6d0e2bf1c556aa1cf870841d44ab6e4b1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1469329
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Paolo Severini <paolosev@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#60330}
23 files changed
tree: 90296a917b20ee15f0bbfcd3c4bc3068ba791e78
  1. benchmarks/
  2. build_overrides/
  3. custom_deps/
  4. docs/
  5. gni/
  6. include/
  7. infra/
  8. samples/
  9. src/
  10. test/
  11. testing/
  12. third_party/
  13. tools/
  14. .clang-format
  15. .clang-tidy
  16. .editorconfig
  17. .git-blame-ignore-revs
  18. .gitattributes
  19. .gitignore
  20. .gn
  21. .vpython
  22. .ycm_extra_conf.py
  24. BUILD.gn
  25. ChangeLog
  27. codereview.settings
  28. DEPS
  30. LICENSE.fdlibm
  31. LICENSE.strongtalk
  32. LICENSE.v8
  33. LICENSE.valgrind
  34. OWNERS
  35. PRESUBMIT.py
  36. README.md
  37. snapshot_toolchain.gni

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/*


Please follow the instructions mentioned at v8.dev/docs/contribute.