pan/bi: Implement f2f16{_rtz, _rtne}

Float conversions with explicit rounding modes are required for OpenCL,
as well as for Vulkan with the VK_KHR_16bit_storage extension (mandatory
in Vulkan 1.1). Since the hardware conversion instructions allow
configuring the round mode, this is easy to support :-)

Fixes test_half.vstore_half_rtz.

Signed-off-by: Alyssa Rosenzweig <>
Part-of: <!17262>
44 jobs for !17262 with bi/f2f16_rtz in 15 minutes and 59 seconds (queued for 3 seconds)
latest merge request