[Libre-soc-dev] opcode allocation pressure

Jacob Lifshay programmerjake at gmail.com
Fri Sep 2 08:30:20 BST 2022

On Fri, Sep 2, 2022 at 12:16 AM Jacob Lifshay <programmerjake at gmail.com> wrote:
> If you look through PowerISA v3.1B appendix F, which is all the
> instructions sorted by version, you can see that the last instruction
> added that reserves half of XO like that was added back in the
> original PPC, *every* instruction added since then either uses the

turns out I'm mistaken, the most recent A-FORM instruction added that
wastes half of XO is fre, added in v2.02. My point still stands,
though, every instruction added since v2.02 was released in early 2005
doesn't use A-FORM unless it has 4 regs, because A-FORM wastes half of
XO for <= 3-regs.



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