Vector TG minutes for 2020/8/7 meeting


Krste Asanovic
 

Date: 2020/8/7
Task Group: Vector Extension
Chair: Krste Asanovic
Co-Chair: Roger Espasa
Number of Attendees: ~22
Current issues on github: https://github.com/riscv/riscv-v-spec

Issues discussed:

#549 Whole register move under big-endian memory system

Discussion was around whether we needed to add EEW to whole-register
vector store also to help with big-endian register spills/fills on
wider vector machines with internal data rearrangment, which otherwise
might have to always use bytes then rearrange on use. It was noted
that current whole-register move instructions are asymmetric with only
loads having EEW encoded. Extensive discussion was around how much to
accomodate big-endian in design. The group was to review how
big-endian worked in general to see if alternative might reduce this
impact.

#550 "V" versus embedded profiles

Group discussed a proposal on how to provide abbreviated Z instruction
subset names to accomodate common ISA configurations in embedded
platforms. Group expressed a desire to separate integer max element
width from floating-point max element width. Also, some
configurations might not want to support all operations at the widest
element width (e.g., no multiply/divide at largest integer width,
only add/sub/accumulate). Group also have general discussion about
whether more general ISA profile format was needed.

# Categorizing issues

The group reviewed the list of outstanding issues and categorized into
before 1.0, and after 1.0, and also tagged some as toolchain issues.
Group encourages all to review the tags, and to also help close out
issues that are for 1.0 release.

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