Hash :
cc1d7f5c
Author :
Date :
2020-08-01T17:47:20
Improve the support of atomics
This change:
* Starts using GCC's and clang's `__atomic_*` intrinsics instead of the
`__sync_*` ones, since the former supercede the latter (and can be
safely replaced by their equivalent `__atomic_*` version with the
sequentially consistent model).
* Makes `git_atomic64`'s value `volatile`. Otherwise, this will make
ThreadSanitizer complain.
* Adds ways to load the values from atomics. As it turns out,
unsynchronized read are okay only in some architectures, but if we
want to be correct (and make ThreadSanitizer happy), those loads
should also be performed with the atomic builtins.
* Fixes two ThreadSanitizer warnings, as a proof-of-concept that this
works:
- Avoid directly accessing `git_refcount`'s `owner` directly, and
instead makes all callers go through the `GIT_REFCOUNT_*()` macros,
which also use the atomic utilities.
- Makes `pool_system_page_size()` race-free.
Part of: #5592