Optimization of PDSCH precoding operation
x86/aarch64 optimizations for precoding, more complete timing reporting in
nr_dlsim. Timing report in nr_dlsim now shows the total PDSCH generation time
and is broken down into Layer mapping, resource mapping and precoding.
The optimizations for x86 are basically reorganizing loops (for AVX512,AVX2,
NEON but not SSE2) to minimize repetitive instructions when formatting of the
precoder weights, and creation of inline functions for complex multiply-add.
AVX512 optimization was added. requiring AVX512BW. Detection of up to 4 PRBs
with common PMI for efficiency with AVX512 (was 2 in develop for AVX2).
For aarch64, native coding of the precoder to avoid inefficient SIMDe
translations for this operation.
nr_dlsim now uses default precoding indices depending on the scenario instead
of 0 which doesn't do precoding at all.
See merge request description for nr_dlsim test results.