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<p>Dear Joachim,<br>
</p>
<div style="color: rgb(40, 40, 40);"><font size="2"><span style="font-size:10pt">
<div class="PlainText"><br>
> Some of this may not be true, but to my knowledge (part of) that<br>
> interface reading code is (or was?) used by haddock when generating<br>
> its .haddock file.</div>
<div class="PlainText"><br>
</div>
<div class="PlainText">Ah, well, I didn't know this. How does haddock use this code? If Haddock uses the GHC-API to do this; problem solved, because we're back at the specific compiler version that generated it. Otherwise... we may be in trouble.<br>
<br>
> Why? You can just serialize Uniques always as 64 bit numbers, even on<br>
> 32-bit systems. This way, the data format is the same across<br>
> architectures, with little cost.</div>
<div class="PlainText"><br>
</div>
<div class="PlainText">Ah, the cost is this; if we start relying on the 64-bitness for uniqueness (which may well happen; there are categories - currently characters - used only for four compile-time known Uniques, waisting 30 - 8 - 2 = 20 bits), this will
break the 32-bit compilers. Arguably, their breakage should reject the change leading to the waisted Uniques. Seems a risk, though. Similarly to how currently Uniques are 64-bits, but serialised as 30. Alternatively, 32-bit GHC could use 64-bit Uniques, but
that is going to give you quite the performance hit (speculating here).<br>
<br>
> But that would only work on 64 bit systems, right?<br>
<br>
</div>
<div class="PlainText">Yes, this approach to a parallel GHC would only work on 64-bit machines. The idea is, I guess, that we're not going to see a massive demand for parallel GHC running on multi-core 32-bit systems. In other words; 32-bit systems wouldn't
get a parallel GHC.<br>
</div>
<div class="PlainText"><br>
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<div class="PlainText">Regards,<br>
</div>
<div class="PlainText">Philip<br>
</div>
<div class="PlainText"><br>
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