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Re: bignum branch

From: Paul Eggert
Subject: Re: bignum branch
Date: Mon, 16 Jul 2018 12:02:34 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1

Eli Zaretskii wrote:
Not sure what you mean by "our GMP substitute source code".  Do you
mean mini-gmp?  I didn't yet look at it, and so I don't know what that
means in practice.  (Someone said it's less efficient than GMP?)

Yes, I meant mini-gmp. And yes, it'd be less efficient than real GMP, something we'd have to live with on 32-bit-long hosts until GMP gets its act together (which I hope wouldn't take that long). I don't think the efficiency loss would be major, as bignums aren't commonly used.

There's no need to wait anyway.  We should condition use of GMP on
EMACS_INT being not wider than the appropriate GMP type (I guess
mp_bitcnt_t?), and then if and when GMP learns to support 64-bit
Windows, things will "just work".

Tom's idea is to just assume GMP in almost all the source code (and to compile and use mini-gmp as a substitute if libgmp is not available), as this simplifies a lot of things. For example, Elisp code won't have to worry about integer overflow, which is a significant win. If this approach performs well enough, I'd prefer its simplicity.

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