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Message-ID: <alpine.LNX.2.20.1603050906560.31711@monopod.intra.ispras.ru>
Date: Sat, 5 Mar 2016 09:14:57 +0300 (MSK)
From: Alexander Monakov <amonakov@...ras.ru>
To: musl@...ts.openwall.com
Subject: Re: [RFC PATCH] micro-optimize __procfdname
On Sat, 5 Mar 2016, Rich Felker wrote:
> > make it really obvious that __procfdname_impl fills in reverse; it might be a
> > very minor size optimization. I don't mind dropping this add adjusting buf
> > with '+= procfdbufsize - 1' in the callee.
>
> Yes, making it obvious what's going on is nice too.
I'm going to keep that adjustment in the macro for now, then.
> Actually it would be even nicer if we could use a compound literal
> inside the macro as the buffer, but that would pessimize with
> unnecessary initialization and eliminate a lot of the code-size
> benefit, I think.
Yep, I did consider that and arrived to a similar conclusion. Well, there's an
option of using alloca as long as no use is in a loop, but that's a bit uglier,
and as I recall it wasn't optimized to a static stack allocation.
I forgot to ask before, shouldn't __procfdname_impl have a visibility
annotation?
And likewise for other internal functions. There are some internal functions
without hidden/internal visibility annotation, visible outside of libc.so.
That seems unintended and slightly harmful.
Alexander
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