[mercury-users] 64-bit ints on 32-bit platforms

Michael Day mikeday at yeslogic.com
Fri Oct 16 18:08:24 AEDT 2009

Hi Zoltan,

> Yes. But the Mercury implementation does not do any such thing, for a very
> simple reason: it would take a lot of work to implement such a capability,
> and the benefit is simply too low. And the benefit is shrinking every day
> as the proportion of 64 bit machines in the world is increasing.

In theory yes, although there are still a lot of 32-bit machines left :)

Hopefully this problem won't reoccur with 128-bit values on 64-bit 
machines. (unless people want support for the SSE instructions that 
manipulate four floats simultaneously?)

> By "cost", you mean performance, so that is correct. However, the cost
> in programming work of doing what you want would be very high, since the
> implication "if a value is unboxed, then its gets stored in a single virtual
> machine register which is the same size as an actual machine register" is
> embedded very deeply in the compiler and the runtime.



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