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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/98829] Different results with -O3 and custom quiet NaN
Date: Wed, 27 Jan 2021 16:42:03 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98829

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Your custom quiet NaN is not a quiet NaN, but signaling NaN.
And, as documented, -fno-signaling-nans is the default.
If you change your custom signaling NaN into a quiet NaN,
static constexpr std::uint64_t kCustomNaN =3D 0x7ff8000000000000 | kMagicNu=
mber;
or if you compile with -fsignaling-nans, this works fine, so I'd say this is
just a user error.=