Reuse index calculation.
Adjusted baseline code path to AVX (Intel and non-Intel processors).
More accurate keyword fixup (C99, C++, etc.).
Hinted unaligned LOAD/STORE instructions. Use macro instead of relying on inline keyword.
Distinct between masked and non-masked LOAD/STORE instructions; this is not necessary in terms of performance but perhaps for clarity. Using non-temporal LOAD/STORE instructions for the result matrix gives 5-10% better performance.