Summary:
This PR addresses some build and functional issues on MSVC targets, as a step towards an eventual goal of having RocksDB build successfully for Windows on ARM64.
Addressed issues include:
- BitsSetToOne and CountTrailingZeroBits do not compile on non-x64 MSVC targets. A fallback implementation of BitsSetToOne when Intel intrinsics are not available is added, based on the C++20 `<bit>` popcount implementation in Microsoft's STL.
- The implementation of FloorLog2 for MSVC targets (including x64) gives incorrect results. The unit test easily detects this, but CircleCI is currently configured to only run a specific set of tests for Windows CMake builds, so this seems to have been unnoticed.
- AsmVolatilePause does not use YieldProcessor on Windows ARM64 targets, even though it is available.
- When CondVar::TimedWait calls Microsoft STL's condition_variable::wait_for, it can potentially trigger a bug (just recently fixed in the upcoming VS 16.8's STL) that deadlocks various tests that wait for a timer to execute, since `Timer::Run` doesn't get a chance to execute before being blocked by the test function acquiring the mutex.
- In c_test, `GetTempDir` assumes a POSIX-style temp path.
- `NormalizePath` did not eliminate consecutive POSIX-style path separators on Windows, resulting in test failures in e.g., wal_manager_test.
- Various other test failures.
In a followup PR I hope to modify CircleCI's config.yml to invoke all RocksDB unit tests in Windows CMake builds with CTest, instead of the current use of `run_ci_db_test.ps1` which requires individual tests to be specified and is missing many of the existing tests.
Notes from peterd: FloorLog2 is not yet used in production code (it's for something in progress). I also added a few more inexpensive platform-dependent tests to Windows CircleCI runs. And included facebook/folly#1461
Koby Kahane
3e745053b7