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[Bug c++/57484] 'std::numeric_limits< T >::signaling_NaN()' signaling-bit is incorrect for x86 32-bit.
- From: "daniel.kruegler at googlemail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Sat, 01 Jun 2013 15:32:09 +0000
- Subject: [Bug c++/57484] 'std::numeric_limits< T >::signaling_NaN()' signaling-bit is incorrect for x86 32-bit.
- Auto-submitted: auto-generated
- References: <bug-57484-4 at http dot gcc dot gnu dot org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57484
--- Comment #4 from Daniel KrÃgler <daniel.kruegler at googlemail dot com> ---
(In reply to Charles L. Wilcox from comment #3)
> Signaling NaN for type "f" in hex is "7fe00000".
I agree, this one doesn't look right to me, because that looks indeed like a
valid qNaN bit pattern only.
> Quiet NaN for type "f" in hex is "7fc00000".
OK.
> Signaling NaN for type "d" in hex is "7ffc000000000000".
Similar problem here: Only a qNaN
> Quiet NaN for type "d" in hex is "7ff8000000000000".
OK.
> $ g++ -Wall -Wextra test-signaling-nan.cpp -m64
> Signaling NaN for type "f" in hex is "7fa00000".
> Quiet NaN for type "f" in hex is "7fc00000".
> Signaling NaN for type "d" in hex is "7ff4000000000000".
> Quiet NaN for type "d" in hex is "7ff8000000000000".
All OK.
> The resulting values on 32-bit vs. 64-bit are different, and I believe the
> 64-bit values are the correct ones.
I agree.