Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 14 Jan 2020 22:53:41 +0300 (MSK)
From: Alexander Monakov <>
Subject: Re: Q: dealing with missing removal of excess precision

On Tue, 14 Jan 2020, Rich Felker wrote:

> > otoh it would be nice if there was a way to tell the compiler not to
> > remove it (e.g. in case the asm already took care of it) even in c99
> > standard mode.
> Perhaps this happens if the output constraint is tied to a float
> rather than a long double?

Precisely. That's what previously posted patches do, and they match
existing hand-tuned assembly.

I misspoke when saying that Glibc might return a value with excess precision.
I was looking at fmod-like functions and missed a slightly subtle point that
fprem does not introduce excess precision. So I don't actually have any
example where Glibc might misbehave in that regard.


Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.