[libre-riscv-dev] power pc

[Luke Kenneth Casson Leighton]

On Wednesday, October 30, 2019, Luke Kenneth Casson Leighton <lkcl at lkcl.net>
wrote:

> Oh I got word that something called Power VLE exists. Needs investigating.


314-68105 is the Freescale document number.

Apparently what they do is mark individual pages as VLE or non-VLE with a
single bit (not found the reference to how big "pages" are yet)

Hm.

So there could potentially be a lot of unnecessary branches back and forth
between pages of different types, where instructions that don't fit into
VLE have to jump out, make the 32 bit instruction then jump back. Or make
it a stack-based function call.

Yuk! :)

However... if we were to do length-limited *runs* of VLE-encoded
instructions...

hmmmm.

L.




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