[Libre-soc-dev] [RFC] SVP64 Branches (contd)

lkcl luke.leighton at gmail.com
Thu Aug 26 22:59:01 BST 2021

On August 26, 2021 3:48:06 PM UTC, lkcl <luke.leighton at gmail.com> wrote:
>after realising that CTR can be used to save instructions in tight
>Vector loops by not needing an explicit GPR subtraction, comparison,
>and etc etc, i also realised that there are even more possible modes
>that might be useful.

again we are running out of bits, or have to start overloading even more fields from the 24 bit RM.


does it make sense for CTR to *always* be decremented "per element"?

this would kinda match with the whole Sub-PC thing: CTR counts elements not SVP64 instructions.

are there any circumstances where you would want to count *batches*? i.e. the number of SVP64 Branch Instructions

and, if so, is it sufficient to simply pre-multiply CTR by VL, such that, again, CTR may be decremented by "number of elements", not "number of times sv.bc is called"?


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