4 ms·

That's not a useful notion of type. If I cannot tell statically by inspecting a register name nor dynamically by inspecting a bit pattern whether a given regist

That's not a useful notion of type. If I cannot tell statically by inspecting a register name nor dynamically by inspecting a bit pattern whether a given register holds a pointer or an integer or a floating-point value, that's pretty much the definition of "untyped".

naasking 9y ago
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.
- tom_mellior 9y ago
  > 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? But sure, call this a type system if you must. It's just a very very weak one, so weak as to be almost entirely useless. (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.)
  - naasking 9y ago
    > It's just a very very weak one, so weak as to be almost entirely useless. 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.
    - tom_mellior 9y ago
      >> It's for architectural reasons. > No, it's for architectural reasons. You win, I guess?
      - naasking 9y ago
        I'm not sure who you're quoting, but I never even used the word "architecture". I don't even know what that's supposed to mean.
        tom_mellior 9y ago
        You try to explain CPU architecture to me, then claim you don't know what CPU architecture is? OK, maybe you don't win, in any case I'll stop here.
        naasking 9y ago
        "Architectural reasons" is nonsense. "Architecture" isn't a set of reasons justifying anything, rather it's the other way around: we design architecture for specific reasons. Your claims that we do things for "architectural reasons" don't have any clear meaning. I said the actual reasons are performance. I don't think I'm the one being unclear.

naasking 9y ago

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.

tom_mellior 9y ago
> 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? But sure, call this a type system if you must. It's just a very very weak one, so weak as to be almost entirely useless. (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.)
- naasking 9y ago
  > It's just a very very weak one, so weak as to be almost entirely useless. 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.
  - tom_mellior 9y ago
    >> It's for architectural reasons. > No, it's for architectural reasons. You win, I guess?
    - naasking 9y ago
      I'm not sure who you're quoting, but I never even used the word "architecture". I don't even know what that's supposed to mean.
      - tom_mellior 9y ago
        You try to explain CPU architecture to me, then claim you don't know what CPU architecture is? OK, maybe you don't win, in any case I'll stop here.
        naasking 9y ago
        "Architectural reasons" is nonsense. "Architecture" isn't a set of reasons justifying anything, rather it's the other way around: we design architecture for specific reasons. Your claims that we do things for "architectural reasons" don't have any clear meaning. I said the actual reasons are performance. I don't think I'm the one being unclear.