Function mangle_hw_name 

pub fn mangle_hw_name(direction: HardwareAccessType, address: &[i128]) -> String

Builds the synthetic global name (__PI_…, __M_…, __G_…) that the pre-processor emits for hardware-bound variables. Single source of truth: every code path that needs to refer to one of these synthetic globals must call this function so that DWARF symbols, initializer rewrites, and external mappings stay in lockstep.