From: Luke Kenneth Casson Leighton Date: Fri, 6 Apr 2018 16:51:38 +0000 (+0100) Subject: partial update X-Git-Tag: convert-csv-opcode-to-binary~5745 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ca8b41296aa3e736ee04415f797251a59747bb88;p=libreriscv.git partial update --- diff --git a/simple_v_extension.mdwn b/simple_v_extension.mdwn index 9cb80ab9a..c592a598c 100644 --- a/simple_v_extension.mdwn +++ b/simple_v_extension.mdwn @@ -69,6 +69,12 @@ This has some extremely useful properties, without being particularly burdensome to implementations, given that instruction decode already has to direct the operation to a correctly-sized width ALU engine, anyway. +Not least: in places where an ISA was previously constrained (due for +whatever reason, including limitations of the available operand spcace), +implicit bit-width allows the meaning of certain operations to be +type-overloaded *without* pollution or alteration of frozen and immutable +instructions, in a fully backwards-compatible fashion. + ## Implicit and explicit type-conversion The Draft 2.3 V-extension proposal has (deprecated) polymorphism to help @@ -117,7 +123,13 @@ follows: * Implicit vs explicit type-conversion: explicit * Implicit vs explicit inner loops: implicit - +In particular: variable-length vectors came out on top because of the +high setup, teardown and corner-cases associated with the fixed width +of SIMD. Implicit bit-width helps to extend the ISA to escape from +former limitations and restrictions (in a backwards-compatible fashion), +and implicit (zero-overhead) loops provide a means to keep pipelines +potentially 100% occupied *without* requiring a super-scalar or out-of-order +architecture. # References