Re: Time to merge scratch/correct-warning-pos into master, perhaps?

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: David Engster <deng@randomsample.de>,  Eli Zaretskii <eliz@gnu.org>,
>  larsi@gnus.org,  mattiase@acm.org,  gregory@heytings.org,
>  emacs-devel@gnu.org
> Date: Sun, 20 Feb 2022 18:02:01 -0500
> 
> > I think I'm just trying to get some sort of handle on how much the code
> > has slowed down because of EQ.  Obviously, making EQ into a function
> > (rather than an inline function) will have distorted things, but it
> > seems the easiest way of measuring something at the moment.
> 
> I understand, but it's still going to be hard to figure out what the
> result means.  Let's say you find that the new non-inlined EQ is 20%
> slower than the old non-inlined EQ, what does it tell us about the
> inlined versions?

That they are ~20% slower.  Moreover, it hopefully will tell us which
part(s) of EQ are more expensive, and thus allow to try making it
faster.

> It's quite possible that more than 50% of the time spent in the
> non-inlined EQ is spent in the "function call overhead" (the jumps
> themselves, the forced placement into specific registers, the need to
> reify a condition code into a boolean stored in a register, the
> impossibility to move code around the call to EQ because the compiler
> doesn't know it's a pure function, ...)?

That time should be the same in the old and the new EQ.