[Libre-soc-dev] [RFC] SVP64 on branch instructions
luke.leighton at gmail.com
Fri Aug 6 10:01:17 BST 2021
On August 4, 2021 5:45:19 PM UTC, lkcl <luke.leighton at gmail.com> wrote:
>i've therefore put re-purposing of AA as Rc back.in, sigh.
i just realised / remembered that there are some spare bits in the RM EXTRA2/3 area that can be used rather than make life hell (and create critical dependencies) in RM MODE.
for other instructions including LD/ST the EXTRA2/3 area is often entirely taken up, so trying to reuse it for Mode bits is inappropriate.
however Branches are so specific (only 2) that we *know*, from examining the register profile of Branches, that they will not use the high area of EXTRA2/3, or in fact the ELWIDTH area either (which may be a better choice, EXTRA2/3 is quite complex decoding, and adding extra MUXes into it is not something done lightly)
i will rework things today.
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