lrint / lrintf functions

lrint / lrintf functions

[Erik de Castro Lopo]

Hi all,

I am currently using the above two C99 functions. If I turn off optimisation
( -O0) I get an error stating that the functions can't be found. If optimisation
is turned on everything is fine.

On my Linux system, these function are in <bits/mathinline.h> which is 
automatically included when I include <math.h>. With optimisation switch off 
it looks like the compiler fails to compile in a static version of the lrint 
and lrintf functions.

Is this the fault of gcc, the C library of something else?

Using Linux 2.4.10 kernel, gcc-2.95, glibc-2.2.4.

Thanks in advance,
Erik
-- 
+-----------------------------------------------------------+
  Erik de Castro Lopo  nospam@mega-nerd.com (Yes it's valid)
+-----------------------------------------------------------+
"I ran it on my DeathStation 9000 and demons flew out of my nose." --Kaz

Re: lrint / lrintf functions (slipping OT)

[Tim Prince]

----- Original Message -----
From: "Erik de Castro Lopo" <nospam@mega-nerd.com>
To: <gcc@gcc.gnu.org>
Sent: Saturday, October 20, 2001 7:29 PM
Subject: lrint / lrintf functions


> Hi all,
>
> I am currently using the above two C99 functions. If I turn off
optimisation
> ( -O0) I get an error stating that the functions can't be
found. If optimisation
> is turned on everything is fine.
>
> On my Linux system, these function are in <bits/mathinline.h>
which is
> automatically included when I include <math.h>. With
optimisation switch off
> it looks like the compiler fails to compile in a static version
of the lrint
> and lrintf functions.
Last I looked, glibc had its math.h set up not to include
<mathinline.h> when -O0 or -Os is selected.
>
> Is this the fault of gcc, the C library of something else?
>
> Using Linux 2.4.10 kernel, gcc-2.95, glibc-2.2.4.
I believe I recall that the C standard used to require the
availability of an external copy of each standard function, so
this would be a bug in glibc, even if gcc were to have a complete
internal implementation.
No, don't blame the kernel, or gcc; modify your glibc setup to do
it the way you want.  Can't you make a linkable version (using
options which invoke the inlines) like:

#include <math.h>
long int (lrint)(double x){return lrint(x);}

Hand optimize the .s file if you like, but I see advantages in
assuring that the in-lines and the external linkable versions
should be more consistent than they currently are. This is not to
deny that the external versions require more error checking than
the in-lines. All OT for gcc, even though the organizational
disconnect between the compiler and the library is contrary to
the standards.  But, glibc won't change unless a number of
influential users have demonstrated and agree upon an
improvement.

I'm considering doing a more complete libm of my own (GPL of
course), at least all the functions where I find something
lacking in one of the libraries commonly used with gcc, but I
don't expect anyone to adopt it.
>
> Thanks in advance,
> Erik

Re: lrint / lrintf functions (slipping OT)

[Erik de Castro Lopo]

It really blew my mind when "Tim Prince" <tprince@computer.org> said:

> 
> I believe I recall that the C standard used to require the
> availability of an external copy of each standard function, so
> this would be a bug in glibc, even if gcc were to have a complete
> internal implementation.

I'm embarassed to admit it but I raised a bug against Debian's libc6.
The maintainer and I had a bit of back an forth we realised that when
I switched optimisation off I have to add -lm to the link command.

Like I said, I am embarrased :-).

Erik
-- 
+-----------------------------------------------------------+
  Erik de Castro Lopo  nospam@mega-nerd.com (Yes it's valid)
+-----------------------------------------------------------+
#!/bin/sh
unzip ; strip; touch ; finger ; mount ; gasp ; 
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Re: lrint / lrintf functions

[mike stump]

> Date: Sun, 21 Oct 2001 12:29:31 +1000
> From: Erik de Castro Lopo <nospam@mega-nerd.com>
> To: gcc@gcc.gnu.org

> I am currently using the above two C99 functions. If I turn off optimisation
> ( -O0) I get an error stating that the functions can't be found.

> Is this the fault of gcc, the C library of something else?

If a symbol that should be defined in your C library, isn't, then
usually it is a library problem.