AMD Zen 4 Cost Table & Tuning Patches Posted For The GCC Compiler

Back in October AMD sent out their initial Zen 4 "znver4" enablement for the GCC compiler. That initial Zen 4 support was since merged for GCC 13 but that initial enablement carried over the cost tables from Zen 3 and didn't do much in the way of tuning but rather just flipping on the new instructions supported by the Ryzen 7000 series and EPYC 9004 series processors. Today there is finally some juicy tuning patches being sent out for GCC...