MSVC 19.11 (A.K.A. VS 15.3)'s C++ standard library implements P0154R1
(http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0154r1.html)
which defines two new constants within the <new> header, std::hardware_destructive_interference_size
and std::hardware_constructive_interference_size.
std::hardware_destructive_interference_size defines the minimum
recommended offset between two concurrently-accessed objects to avoid
performance degradation due to contention introduced by the
implementation (with the lower-bound being at least alignof(max_align_t)).
In other words, the minimum offset between objects necessary to avoid
false-sharing.
std::hardware_constructive_interference_size on the other hand defines
the maximum recommended size of contiguous memory occupied by two
objects accessed wth temporal locality by concurrent threads (also
defined to be at least alignof(max_align_t)). In other words the maximum
size to promote true-sharing.
So we can simply use this facility to determine the ideal alignment
size. Unfortunately, only MSVC supports this right now, so we need to
enclose it within an ifdef for the time being.
Multi-line doc comments still need the '<' after the ///, otherwise it's
treated as a regular comment and makes the original doc comment broken
in viewers, IDEs, etc. While we're at it, also fix some typos in the
comments.
The previous form of initializing done here is a C-ism, an empty set of
braces is sufficient for initializing (and doesn't potentially cause
missing brace warnings, given the first member of the struct is a COORD
struct).
Previously core itself was the library containing the code to gather
common information (build info, CPU info, and OS info), however all of
this isn't core-dependent and can be moved to the common code and use
the common interfaces. We can then just call those functions from the
core instead.
This will allow replacing our CPU detection with Xbyak's which has
better detection facilities than ours. It also keeps more
architecture-dependent code in common instead of core.
These currently aren't used and contain commented out source code that
corresponds to Dolphin's JIT. Given our CPU code is organized quite
differently, we shouldn't be keeping this around (at the moment it just
adds to compile times marginally).
The filter is returned via const reference, so this was making a
pointless copy of the entire filter every time a message was being
pushed into the logger instance.
Weiyi Wang