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Re: Making 'eq' == 'eql' in bignum branch

From: Pip Cet
Subject: Re: Making 'eq' == 'eql' in bignum branch
Date: Fri, 10 Aug 2018 15:43:00 +0000

On Fri, Aug 10, 2018 at 3:15 PM Stefan Monnier <address@hidden> wrote:
> > That sounds promising! However, I wonder whether NaN-boxing isn't the
> > right thing to do once we have bignums (on platforms that support it,
> > by limiting pointers to 48 bits like x86-64 does). I'm doing that in
> NaN boxing implies 64bit boxes, which on 32bit platforms imposes
> a non-negligible overhead.

Sorry, I don't understand. I don't see how any of this applies to
32-bit platforms with 32-bit EMACS_INTs. On those, we cannot have
float immediates or NaN boxing.

> So, I think it'd end up costing
> significantly more than the tentative patch with which Paul and I have
> been playing.

I think we only have a benchmark for 61-bit floats, which would mean
giving up IEEE compliance and surprising the occasional user who wants
it. That's a very high price to pay for saving a few GCs.

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