[Libre-soc-dev] planning next OPF ISA WG RFC: ls003, biginteger?

[lkcl]

On Thu, Mar 2, 2023 at 5:38 PM Jacob Lifshay <programmerjake at gmail.com> wrote:

> dsld/dsrd are no longer hard to use,

great.

> however they still have the issue that they unnecessarily write to `overflow`,

no, they don't. it's conditional. Rc=1.

> making them much slower than necessary

no, they're not.

> because of having to read/write SO,

no, they don't. read the RFC.

> which means you can't run multiple instructions in parallel unless
> you have special dependency hardware for SO.

which is optional in the SFFS subset. and therefore not
our problem.

> also, their overflow output is inconsistent with other powerisa shift instructions.

luckily we're not doing "other power isa shift instructions".

> i think we should just remove their overflow output, since that matches other powerisa unsigned shift instructions.

a large portion of the objections you raise are invalid, so i'm
leaving it in.

the ISA WG can always object and give reasons why it should
not be in.

l.