[Libre-soc-dev] cray-style vector of 40 years setting VL=0 at runtime

lkcl luke.leighton at gmail.com
Mon Oct 3 11:54:03 BST 2022

jacob i've started the review / audit process, we need to go through the ENTIRETY of SV and i do mean absolutely all of it if you want VL=1 on scalar reg usage.  i cannot possibly or reasonably be expected to complete such a massive task on my own, you will need to help out (anyone else is also welcome).  i began the review here:


the first two major changed behaviours are non-zero'd predication and REMAP, especially Indexed REMAP. these would be two *legitimate* use-cases i have found so far where VL>1 with sv all-scalar could be used.

alternative assembler will need to be demonstrated to achieve the desired effect, and/or an assessment of how likely the use-case is in the first place, then description of workarounds.

if this sounds like one hell of a lot of work that's because it is.


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