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From: "joseph at codesourcery dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/103683] Redundant !__builtin_isnan not
 removed with -fno-signaling-nans
Date: Tue, 14 Dec 2021 00:05:12 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103683

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery =
dot com> ---
(x > 1) is expected to raise invalid for a quiet NaN, so the two functions=
=20
are different in the absence of -fno-trapping-math, whether or not=20
signaling NaNs are enabled.

((!__builtin_isnan (x)) && x > 1) is equivalent to __builtin_isgreater (x,=
=20
1.0) and could be optimized accordingly for -fno-signaling-nans, however.=
=20=20
(With signaling NaNs, you have the issue that the first expression doesn't=
=20
raise invalid for a signaling NaN but the second does.)=