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

[Paul Eggert]

On 07/31/2018 09:12 AM, Eli Zaretskii wrote:
> I take it we agree that if someone writes a Lisp program which does FP
> calculations, their chance of having a lot of such values would be
> quite low, yes?  So we should put such use cases aside.

Nobody should want to write such a program since Emacs is not intended 
for and does not perform well with heavy-duty FP calculations. So I 
agree that we shouldn't worry about such programs; we should focus on 
"real-world Emacs", so to speak.

> One way of estimating what happens in the majority of uses is to find
> Emacs APIs other than numerical calculations that can return floats,
> and try to analyze what kind of floats will be the result.  Like
> file-system-info and file-attributes, for example.

These should be fine on a 64-bit platform. file-system-info invariably 
yields floating-point numbers with the bottom three bits zero, due to 
how modern file systems are built (their sizes are multiples of powers 
of two). file-attributes returns an exact value unless your file is 
larger than 2**61 bytes (2 EiB), and once we get to the rare files 
larger than that we should be using bignums anyway. (The same could be 
said for file-system-info, of course.)

> How faster, in absolute numbers and in percents, will your build
> finish with the proposed changes?

I won't know unless I take the time to code it up.