Function logos_add_i64 

pub fn logos_add_i64(a: i64, b: i64) -> i64

Fused NARROWED exact ops (overflow ruling v2, stage 2): emitted when a single exact op’s result narrows straight back to i64 — the dominant hot-loop shape. The fast path is one checked op on machine integers (no LogosInt materialization, so the value lives in a register and LLVM’s induction reasoning survives); overflow raises the same loud canonical error the logos_*_exact(..).expect_i64("Int") chain raises, byte for byte (the printed value is the exact result).