half_float test fails with modern CPU features enabled

Submitted by Hans Johnson

Assigned to Nobody

Link to original bugzilla bug (#1780)
Version: 3.4 (development)
Operating system: Linux

Description

Created attachment 963
A script that demonstrates compiler flags that begin to fail for the half_float test

This unit test fails with compiler support of any of the following features
which are part of the "-march=ivybridge" architecture settings.

-target-feature +fsgsbase -target-feature +rdrnd -target-feature +f16c

VERIFY_IS_EQUAL( std::numeric_limits<half>::signaling_NaN().x, half(std::numeric_limits<float>::signaling_NaN()).x );

The failure is documented for both Mac/clang and Linux/gcc builds.

Using the "-mtune=native -march=native" compiler flags on recently (i.e. ~5 years ago) released CPU's demonstrates this issue.

Attachment 963, "A script that demonstrates compiler flags that begin to fail for the half_float test":
build_half_float.sh