A recent change in Ardour that used int128_t did not break on ARM nor did it break on unoptimized x86_64 builds, but did break on optimized x86_64 builds. That's just one example of the sort of platform-specific madness that may need to be faced and chased down.
Just providing a link to stackoverflow discussion that seems to relate to this, as I was curious about the details. Looks like it was undefined behavior relating to casting pointers.
