I've been thinking about trying out the x32 ABI.
Not to be confused with x86-32 and x86-64, x32 is a Linux-specific ABI designed to combine the computational efficiency of x86-64 with the memory efficiency of x86-32.
x32 uses the x86-64 instruction set, allowing for more registers and faster instructions, while using 32-bit pointers and 32-bit integers, allowing for a smaller memory footprint.
Smaller memory footprint also means that the CPU cache is more effective and less memory bandwidth is required.
Various benchmarks I've seen 'round the 'net show that x32 provides up to 40% less memory consumption and 10% faster performance (especially for pointer-heavy applications like Java) compared to x86-64
However, x32 has a couple disadvantages:
Applications are limited to up to 3GiB of virtual memory space each, like x86-32.
Most applications that have assembly optimizations wont work, or at least those parts wouldn't be optimized, unless the developers specifically add x32 support.
It is quite esoteric, and therefore more prone to bugs, due to the lack of users for testing.
There's a chance it'll be removed in the kernel some time in the near future. (There were talks of removing it back in 2018, but it didn't go anywhere)
As far as I'm aware, only glibc has proper support for x32. Musl has preliminary experimental support for it, but I doubt it'll ever get finish due to the obscurity of it.
