[Libre-soc-dev] LD/ST Elwidth Overrides

[Jacob Lifshay]

On Wed, Sep 1, 2021, 07:52 lkcl <luke.leighton at gmail.com> wrote:

> * operation width ld=64 lw=32 lh=16 lb=8
> * src elwidth override applies to memory, dflt/32/16/8
> * dest elwidth override applies to the register
>    receiving the data being read.
>


I realized that it would be more useful to let the src elwidth override
apply to the index register for lbzx (and all ld/st indexed instructions)
instead of using the src elwidth to change the memory access size, which is
redundant:
https://libre-soc.org/irclog/%23libre-soc.2021-09-01.log.html#t2021-09-01T17:54:16

Note that how I'm proposing is exactly how gather/scatter works on x86 and
Arm and probably waay more...it's also useful for doing webassembly
load/stores in one instruction, rather than 3 (explained in irclog link).

Jacob

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