From: Luke Kenneth Casson Leighton Date: Fri, 6 Apr 2018 17:37:21 +0000 (+0100) Subject: partial update X-Git-Tag: convert-csv-opcode-to-binary~5741 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=263f1191ec5774557f26ff5092087707e68bc23e;p=libreriscv.git partial update --- diff --git a/simple_v_extension.mdwn b/simple_v_extension.mdwn index 96aec47ea..3ace324b5 100644 --- a/simple_v_extension.mdwn +++ b/simple_v_extension.mdwn @@ -1,25 +1,30 @@ # SIMD / Simple-V Extension Proposal This proposal exists so as to be able to satisfy several disparate -requirements: area-conscious designs and performance-conscious designs. +requirements: power-conscious, area-conscious, and performance-conscious +designs all pull an ISA and its implementation in different conflicting +directions, as do the specific intended uses for any given implementation. + Also, the existing P (SIMD) proposal and the V (Vector) proposals, whilst each extremely powerful in their own right and clearly desirable, are also: * Clearly independent in their origins (Cray and AndeStar v3 respectively) -* Both contain duplication of pre-existing RISC-V instructions +* Both contain partial duplication of pre-existing RISC-V instructions + (an undesirable characteristic) * Both have independent and disparate methods for introducing parallelism at the instruction level. * Both require that their respective parallelism paradigm be implemented along-side their respective functionality *or not at all*. -* Both independently have methods for introducing parallelism that could, - if separated, benefit *other areas of RISC-V not just DSP and Floating-point*. +* Both independently have methods for introducing parallelism that + could, if separated, benefit + *other areas of RISC-V not just DSP or Floating-point respectively*. Therefore it makes a huge amount of sense to have a means and method of introducing instruction parallelism in a flexible way that provides implementors with the option to choose exactly where they wish to offer performance improvements and where they wish to optimise for power -and area. If that can be offered even on a per-operation basis that +and/or area. If that can be offered even on a per-operation basis that would provide even more flexibility. # Analysis and discussion of Vector vs SIMD