http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57484
--- Comment #19 from Charles L. Wilcox <zxClhzAApX1EdJwQANqrjLERmFeURQVy at
cynd dot net> ---
(In reply to Uroš Bizjak from comment #11)
> On an x86 target using the legacy x87 instructions and the 80-bit registers,
> a load of a 64-bit or 32-bit value in memory into the 80-bit registers
> counts as a format conversion and an signaling NaN input will turn into a
> quiet NaN in the register format.
Does this mean if a 80-bit sNaN was generated and loaded into a register it was
still have the signaling bit set correctly? And if so, could this value then
be down-converted to a 32 or 64-bit float? In C++:
float float32_snan const
= static_cast< float >( std::numeric_limits< long double
>::signaling_NaN() );
double float64_snan const
= static_cast< double >( std::numeric_limits< long double
>::signaling_NaN() );
Or, is the "cast" here a format conversion, causing the signaling NaN to
convert to a quiet NAN?
