This commit changes the codegen for error messages for failed memcpys.
This no longer generates a stack frame and correctly tail calls the
error messages generator.
It also turns the error messages on in Release builds. This will lead
to better adoption experience.
See src/snmalloc/README.md for an explanation of the layers.
Some other cleanups on the way:
Fine-grained stats support is now gone.
It's been broken for two years, it depends on iostream (which then
causes linker failures with libstdc++) and it's collecting the wrong
stats for the new design. After discussion with @mjp41, it's better to
remove it and introduce new stats support later, rather than keep broken
code in the main branch.
Tracing was controlled with a preprocessor macro, now there's also a
CMake option.
Expose a memcpy.h that contains all of the bits of memcpy and clean up
the bounds checks header so that versions with both read and write
checks can coexist.
* Improve testing of memcpy including adding perf test.
* Change remaining_bytes to be branch free.
Use reciprocal division followed by multiply to remove a branch.
