Fix Half NaN definition and test.

The `half_float` test was failing with `-mcpu=cortex-a55` (native `__fp16`) due
to a bad NaN bit-pattern comparison (in the case of casting a float to `__fp16`,
the signaling `NaN` is quieted). There was also an inconsistency between
`numeric_limits<half>::quiet_NaN()` and `NumTraits::quiet_NaN()`.  Here we
correct the inconsistency and compare NaNs according to the IEEE 754
definition.

Also modified the `bfloat16_float` test to match.

Tested with `cortex-a53` and `cortex-a55`.

1 files changed, 2 insertions, 2 deletions

diff --git a/Eigen/src/Core/arch/Default/Half.h b/Eigen/src/Core/arch/Default/Half.h
index 4dde91365..d6ddff59c 100644
--- a/Eigen/src/Core/arch/Default/Half.h
+++ b/Eigen/src/Core/arch/Default/Half.h
@@ -200,7 +200,7 @@ struct numeric_limits<Eigen::half> {
   static Eigen::half round_error() { return Eigen::half(0.5); }
   static Eigen::half infinity() { return Eigen::half_impl::raw_uint16_to_half(0x7c00); }
   static Eigen::half quiet_NaN() { return Eigen::half_impl::raw_uint16_to_half(0x7e00); }
-  static Eigen::half signaling_NaN() { return Eigen::half_impl::raw_uint16_to_half(0x7e00); }
+  static Eigen::half signaling_NaN() { return Eigen::half_impl::raw_uint16_to_half(0x7d00); }
   static Eigen::half denorm_min() { return Eigen::half_impl::raw_uint16_to_half(0x1); }
 };
 
@@ -744,7 +744,7 @@ template<> struct NumTraits<Eigen::half>
     return half_impl::raw_uint16_to_half(0x7c00);
   }
   EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR static EIGEN_STRONG_INLINE Eigen::half quiet_NaN() {
-    return half_impl::raw_uint16_to_half(0x7c01);
+    return half_impl::raw_uint16_to_half(0x7e00);
   }
 };