[eridius]

They do? I admit I'm not an expert on either x86 or ARM assembly, but I've never seen code that used a saturating arithmetic instruction, and the saturating math in Rust is implemented using checked arithmetic as opposed to any kind of llvm intrinsic for saturating math. Looking at the LLVM docs I don't see any kind of intrinsic for saturating math either (checked math uses llvm.sadd.with.overflow.* and friends).

[yoklov]

It's part of the vector ISAs for both. x86 does as part of SSE (or SSE2, or MMX, etc, I don't remember). ARM it's part of the DSP extensions.