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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/115374] fmod() in x86_64 -O3 not using return value from the
 glibc's implementation if x87 FPU fprem returns NaN
Date: Thu, 06 Jun 2024 19:32:14 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115374

--- Comment #8 from Uro=C5=A1 Bizjak <ubizjak at gmail dot com> ---
When compiling the following testcase:

--cut here--
#include <math.h>

double
__attribute__((noinline))
do_fmod (double x, double y)
{
  return fmod(x, y);
}
--cut here--

one can find in _.265t.optimized:

__attribute__((noinline))
double do_fmod (double x, double y)
{
  double _5;

  <bb 2> [local count: 1073741824]:
  _5 =3D .FMOD (x_2(D), y_3(D));
  if (_5 =3D=3D _5)
    goto <bb 4>; [99.95%]
  else
    goto <bb 3>; [0.05%]

  <bb 3> [local count: 536864]:
  fmod (x_2(D), y_3(D));

  <bb 4> [local count: 1073741824]:
  return _5;

}=