[Libre-soc-dev] svp64

Luke Kenneth Casson Leighton lkcl at lkcl.net
Wed Dec 16 09:39:34 GMT 2020


ok went through the new additions, jacob, and you probably saw
already, just a summary:

* 2pred DEST SUBVL.  evaluated, conclusion: no.  makes no sense.
mv.vec covers it.  details here
  https://libre-soc.org/openpower/sv/svp_rewrite/svp64/discussion/

* 2pred and 1pred are so different that they really need separate
tables.  actually a case could be made for having 3:
  - dest, src1, src2, src3  (2 bit for reg expansion)
  - dest, src1, src2          ( 3 bit for reg expansion)
  - dest, src                    (2/3 bit - TODO decide - extra stuff
for dest elwidth etc)

* two tables R_EXTRA2 and R_EXTRA3
  - TODO, should these be part of 2 tables

* i really, REALLY do not understand the naming.  it is flat-out
impossible for me, due to what i am increasingly beginning to
recognise (after "only" 40 years) is a form of dyslexia, to interpret
the names.  the old SVPrefix meaning which referred to bits was dead
easy.

* reduction of table names by reducing verbosity of descriptions.  i
use a very small screen for viewing the wiki pages: editing and just
reviewing is a pain.  the more words, the harder it is to understand.

i think that's everything, meeting in 20 mins.

l.



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