Re: "Mini" tags to reduce the number of op codes

Stephen Fuld wrote:
<snip>

I think this all works fine for a single compilation unit, as the compiler certainly knows the type of the data.  But what happens with separate compilations?  The called function probably doesn’t know the tag value for callee saved registers.  Fortunately, the My 66000 architecture comes to the rescue here.  You would modify the Enter and Exit instructions to save/restore the tag bits of the registers they are saving or restoring in the same data structure it uses for the registers (yes, it adds 32 bits to that structure – minimal cost).  The same mechanism works for interrupts that take control away from a running process.

I had missed this until now:: The stack remains 64-bit aligned at all times,
so if you add 32-bits to the stack you actually add 64-bits to the stack.
Given this, you an effectively use a 2-bit tag {integral, floating, pointing,
describing}. The difference between pointing and describing is that pointing
is C-like, while describing is dope-vector-like. {{Although others may find
something else to put in the 4-th slot.}}

Any comments are welcome.