Earlier quoted context omitted.
Dynamic type testing or introspection is not an essential feature of type systems. The fact is, your computing machine is typed. You can not deference a floating point register as an address, for instance.
> Dynamic type testing or introspection is not an essential feature of type systems. I didn't say so. An essential feature of type systems is being able to determine the types of (many) values, statically or dynamically. > You can not deference a floating point register as an address, for instance. So you'd agree that architectures that don't make a distinction between integer and floating point registers are untyped…
Weak and strong aren't meaningful terms. A machine ISA might have an inexpressive type system and/or an unsound type system (because it conflates addresses and integers).
> And the reason floating point registers are often separate from integer registers is not to provide this kind of "type safety", it's due to history and architecture.
No, the reason is performance. And we get performance by making statically known distinctions between datatypes, which is what the original poster asked about.
Intermingling the integer and floating point circuitry so they access the same register file would never improve performance over keeping them separate. You'd need longer wires to place them both near the same register files to minimize signal latency, an the added signal delay alone ensures lower performance.