#13953: Incorrectly handled bfloat16 -0.0 in ttnn.signbit

[atatuzunerTT]

Ticket

Link to Github Issue

Problem description

-0.0 Incorrectly handled as 0.0 in ttnn.signbit. bfloat16 data format should preserve -0.0 values through the unpacker, math, packer pipeline. However, -0.0 in bfloat16 format gets passed into the kernel as 0.0 and signbit reads this as a positive value.

The detailed reasoning is as follows. When unpacking to the Dest register, bfloat16 values are first packed into Src registers and then moved to Dest. When moving these values from Src, -0.0 is interpreted as 0.0 and src zero flags are set. This leads to -0.0 values not being moved, but instead, zeroes being written into relevant locations in Dest.

What's changed

Disabled src zero flags for eltwise unary/sfpu operations. -0.0 values are now moved to Dest instead of written with zeroes.

Checklist

• All post commit CI passes
• Blackhole Post commit CI passes (if applicable)