From owner-freebsd-mips@freebsd.org  Mon Nov 13 22:52:34 2017
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From: Khilan Gudka <Khilan.Gudka@cl.cam.ac.uk>
Date: Mon, 13 Nov 2017 22:52:10 +0000
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Subject: fabs(-0.0) returns -0.0
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Sender: Khilan Gudka <kg365@hermes.cam.ac.uk>
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Hi,

The implementation of fabs(3) for MIPS (at least) appears to not be giving
the right answer for when -0 is passed, as it returns -0 instead of +0. The
implementation of fabs is:

double fabs(double x) {
  if (x < 0)
    return -x;
  return x;
}

The if-test fails for -0 and thus it is returned. Is this a known issue? A
simple fix would be to return x+0.0 instead of just x.

The implication of this is that other functions which rely on fabs, such as
hypot, also return -0. For example, hypot(-0.0, 0.0) returns -0 instead of
+0.

Thanks,
Khilan