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Re: Building Emacs on MSYS2


From: Óscar Fuentes
Subject: Re: Building Emacs on MSYS2
Date: Fri, 15 Apr 2016 22:17:15 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.92 (gnu/linux)

Stefan Monnier <address@hidden> writes:

>> I was just saying that Emacs wide integers are the default on 64 bit
>> platforms.
>
> No: --with-wide-int was introduced so that Emacs can use integers which
> are twice the size of pointers (at the cost of making Lisp_Object twice
> the size, hence wasting space for all non-integer values).

AFAIK that was the reasoning when 64 bit platforms were not prevalent
and 32 bit the norm.

> I.e. on
> a 64bit system, this would mean that the Lisp_Object type is 128bit
> wide, which would be a waste.
>
> Luckily for that script you quoted, on 64bit hosts, we basically
> ignore --with-wide-int, so even though it goes to extra trouble to
> set --with-wide-int on amd64 we disregard this "preposterous request".

Hence effectively --with-wide-int is a method for ensuring that a 64 bit
type is used for storing Emacs integers. But as on 64 bit platforms
Emacs already uses a 64 bit type for that, there is no observable
difference from the POV of the user among passing --with-wide-int=yes to
the configure script and not doing it. Which is in line with what you
quoted from my previous message.

Now, can be agree on that I'm right and stop this pointless discussion
:-)




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