Common cache line sizes are 32, 64 and 128 bytes. On x86_64 the standard
cache line size is 64B. Even though this is not architecturally required,
all the x86_64implementations stick to it. Some AArch64 processors also
follow the x86_64 style with 64B cachelines. However, on Apple M1
devices, the underlying hardware is using a 128B cache line size. Quote
from Apple Developer documentation [1]:
"Some features of Apple silicon are decidedly different than those of
Intel-based Mac computers, and may impact your code if you don't fetch
them dynamically. These features include:
* Cache line sizes are different. Fetch the hw.cachelinesize setting
using sysctl."
M1 cache lines are double of what is commonly used by x86_64 and other
Arm implementation. The cache line sizes for Arm depend on implementations,
not architectures. For example, TI AM57x (Cortex-A15) uses 64B cache
line while TI AM437x (Cortex-A9) uses 32B cache line. And, there are
even Arm implementations with cache line sizes configurable at boot time.
This patch attempts to detect L1 cache size at compile time. For Aarch64
hosts, the build process would collect system information and determine
L1 cache line size. At present, both macOS and Linux are supported. For
Arm targets, the software packages are usually cross-compiled, and
developers should specify the appropriate MI_CACHE_LINE setting in
advance.
64B is the default cache line size if none of the above is able to set.
[1] https://developer.apple.com/documentation/apple-silicon/addressing-architectural-differences-in-your-macos-code
The standard way of cmake install to a destination folder is the following pattern:
```shell
cd <BUILD_DIR>
cmake <SRC_DIR>
cmake --build <BUILD_DIR>
cmake --install <BUILD_DIR> --prefix <INSTALL_DIR>
```
Right now, the `<INSTALL_DIR>` folder passed in cmake --install command is ignored,
and always installed into `C:/Program Files(x86)/...`, which is the default
`CMAKE_INSTALL_PREFIX` value passed at the `cmake <SRC_DIR>` call.
Thus, it is not possible to install the binaries into different folders
without rerun the cmake/build process.
The important thing here is, the cmake variable `CMAKE_INSTALL_PREFIX`
is supposed to be passed at `cmake --install` time with the `--prefix` argument.
In cmake file, `install` with relative path will use that prefix automaticlly.
And it is the best practice to not include CMAKE_INSTALL_PREFIX
in the `install(... DESTINATION )` argument:
```
In particular, there is no need to make paths absolute by prepending
CMAKE_INSTALL_PREFIX; this prefix is used by default if the DESTINATION is a relative path.
```
referenced from: https://cmake.org/cmake/help/latest/command/install.html
Currently warnings / errors are enabled by default in debug build.
Otherwise they could be enabled only via environmental variable or
API option call. Add possibility to specify the default during the
build time. This simplifies e.g. integration of the library into
bigger projects as no source changes would be required.
xmalloc is a non-standard extension forcing malloc() to
abort should the memory allocation failed instead of returning a
null pointer. Such functionality is quite useful as it provides one
single point of error handling if the caller of malloc() does not
check the result (as it often does!) and segfault is ocurring somewhere
else. If more fine-grained control is necessary one could register a custom
error handler, however, this might not be an option while interposing.
