[m-dev.] question about 32 bit machines

[Michael Day]

Hi Zoltan,

> The different treatment of int64/uint64s from floats is just because
> we haven't implemented their unpacked representation yet. However, I have
> a question: should we have unpacked 64 bit arguments on 32 bit systems at all?
> Given the relative rarity of 32 bit systems *and* the relative rarity of code
> that not only uses floats, int64s or uint64s but also spends a significant fraction
> of its runtime on operations on them, I am wondering whether a policy of
> "always box 64 bit primitive values into 32 bit words on 32 bit systems when
> putting them into a structure" would be good enough. It would certainly
> simplify the relevant parts of the compiler.

One program that spends a significant fraction of its runtime in 
operations on floats is Prince, which is why we were interested in the 
unboxing optimisation. Although 64-bit machines have become the new 
standard, we still have many customers using 32-bit machines, and they 
have the tightest address space requirements, so it would be nice to 
keep this optimisation if we can.

Michael

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