[libcxx-commits] [PATCH] D115368: [NFC][libcxxabi] Re-organized inheritance structure to remove CRTP in cxa_guard

[Daniel McIntosh via Phabricator via libcxx-commits]

DanielMcIntosh-IBM created this revision.
DanielMcIntosh-IBM added reviewers: ldionne, EricWF, nicholas, jroelofs.
DanielMcIntosh-IBM requested review of this revision.
Herald added a project: libc++abi.
Herald added a subscriber: libcxx-commits.
Herald added a reviewer: libc++abi.

Currently, the `InitByte...` classes inherit from `GuardObject` so they can
access the `base_address`, `init_byte_address` and `thread_id_address`. Then,
since `GuardObject` needs to call `acquire`/`release`/`abort_init_byte`, it uses
the curiously recurring template pattern (CRTP). This is rather messy.

Instead, we'll have `GuardObject` contain an instance of `InitByte`, and pass it
the addresses it needs in the constructor. `GuardObject` doesn't need the
addresses anyways, so it makes more sense for `InitByte` to keep them instead of
`GuardObject`. Then, `GuardObject` can call `acquire`/`release`/`abort` as one
of `InitByte`'s member functions.

Organizing things this way not only gets rid of the use of the CRTP, but also
improves separation of concerns a bit since the `InitByte` classes are no longer
indirectly responsible for things because of their inheritance from
`GuardObject`. This means we no longer have strange things like calling
`InitByteFutex.cxa_guard_acquire`, instead we call
`GuardObject<InitByteFutex>.cxa_guard_acquire`.

This is the 4th of 5 changes to overhaul cxa_guard.
See D108343 <https://reviews.llvm.org/D108343> for what the final result will be and more details on why
cxa_guard is getting overhauled.

Depends on D115367 <https://reviews.llvm.org/D115367>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D115368

Files:
  libcxxabi/src/cxa_guard_impl.h
  libcxxabi/test/guard_test_basic.pass.cpp

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D115368.392848.patch
Type: text/x-patch
Size: 18288 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/libcxx-commits/attachments/20211208/4a6ecb76/attachment-0001.bin>