Mitch expressed a preference to not have `#ifdef`s in platform agnostic
code, this change tries to accomodate this.
I am not attached to the method this CL proposes, so if anyone has a
suggestion, I am open.
We move the platform specific member of the mutex into its own platform
specific class that the main `Mutex` class inherits from. Functions are
implemented in their respective platform specific compilation units.
For Fuchsia, we use the sync APIs, as those are also the ones being
used in Scudo.
Differential Revision: https://reviews.llvm.org/D90351
Summary:
See D60593 for further information.
This patch pulls out the mutex implementation and the required definitions file.
We implement our own mutex for GWP-ASan currently, because:
1. We must be compatible with the sum of the most restrictive elements of the supporting allocator's build system. Current targets for GWP-ASan include Scudo (on Linux and Fuchsia), and bionic (on Android).
2. Scudo specifies `-nostdlib++ -nonodefaultlibs`, meaning we can't use `std::mutex` or `mtx_t`.
3. We can't use `sanitizer_common`'s mutex, as the supporting allocators cannot afford the extra maintenance (Android, Fuchsia) and code size (Fuchsia) overheads that this would incur.
In future, we would like to implement a shared base mutex for GWP-ASan, Scudo and sanitizer_common. This will likely happen when both GWP-ASan and Scudo standalone are not in the development phase, at which point they will have stable requirements.
Reviewers: vlad.tsyrklevich, morehouse, jfb
Reviewed By: morehouse
Subscribers: dexonsmith, srhines, cfe-commits, kubamracek, mgorny, cryptoad, jfb, #sanitizers, llvm-commits, vitalybuka, eugenis
Tags: #sanitizers, #llvm, #clang
Differential Revision: https://reviews.llvm.org/D61923
llvm-svn: 362138
Mitch Phillips