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User-Agent: Mozilla/4.77 [en] (X11; U; Linux 2.4.2-2 i586)

Description of problem:
nextafter(x,y) and friends are supposed to return the next representable
number after X in the direction of Y (unless Y is NaN).  The double and
float versions work correctly, but on the i386 port, the long double
version will instead return Y if Y is +-infinity.


How reproducible:
Always

Steps to Reproduce:
Compile and run the following program:

#include <stdio.h>
#define __USE_ISOC99 1
#include <math.h>

int
main ()
{
  long double delta;

  delta = nextafterl (1.0L, INFINITY) - 1.0L;
  printf ("1ulp = %Lg*2^exp\n", delta);
  return (delta < 0.0L);
}


Actual Results:  1ulp = inf*2^exp


Expected Results:  1ulp = 1.0842e-19*2^exp


Additional info:

I've glanced at glibc-2.2.3/sysdeps/i386/fpu/s_nextafterl.c, but I can't
tell which block of code is being executed, much less where the bug could
be hiding.

In my own port of the function, I simply check the sign of X against (x <
y) (after checking that X and Y are ordered and unequal) and
increment/decrement X accordingly.  There are a few special border cases
depending on the value of X, but the code works regardless of the value of
Y.