cblas_gemm_s8s8s32 not support？

Dear sir，

I hava a question：

I read the oneDNN code， that seams cblas_gemm_s8s8s32（） is not implemented，just cblas_gemm_s8u8s32，why？

Because ISA of intel （AVX2？）has not special instructions that can execute multiplying or adding  operation when the two vectors have the same data type (either s8/s8 or u8/u8)？

Thank you！