[Libre-soc-bugs] [Bug 1117] daxpy cookbook example

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=1117

--- Comment #5 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
a quick re-read to ensure that before approving the
RED RFP that it looks good for NLnet to review and
accept, i added this additional paragraph which helps
explain and justify the huge number (30+ !) of LD/ST
Post-Increment Update instructions that Libre-SOC is
proposing.

their value is enormous, they get added to every high-end
ISA but Power lacks them as they take up a HELL of a lot
of Opcode space, and Power ISA is under significant opcode
pressure.

hm just spotted a spelling error... fixed.

https://git.libre-soc.org/?p=libreriscv.git;a=commitdiff;h=c56745a2ad3

 of the next batch.

+If  `sv.lfdup` was not available, `sv.lfdu` could be used to the same
+effect, but RA would have to be *pre-subtracted by one element*, outside
+of the loop. Due to the compactness of this highly hardware-parallelizable
+algorithm, that one additinal instruction would increase the implementation
+code size by 5 percent! This helps explain why Post-Increment Update
+Load/Store instructions are so important.

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