[libre-riscv-dev] Instruction sorta-prefixes for easier high-register access

[Jacob Lifshay]

On Fri, Jan 18, 2019, 09:39 Hendrik Boom <hendrik at topoi.pooq.com wrote:

> On Fri, Jan 18, 2019 at 01:49:39AM -0800, Jacob Lifshay wrote:
> > On Fri, Jan 18, 2019, 01:33 Luke Kenneth Casson Leighton <lkcl at lkcl.net
> > wrote:
> >
> > > hi jacob, a brief thought / reply, more later:
> > >
> > > * prefixes on instructions gives an opportunity to do key-hole
> > > analysis, assessing if the prefixes can be removed and use the CSR
> > > stack instead.
> > >
> > Haven't heard of key-hole analysis before -- wikipedia didn't seem to
> have
> > anything relevant
>
> Would that be what the compiler-writers here call peephole optimisation?
>
Maybe. From what I recall, LLVM uses a tree-based pattern matcher for
instruction selection, so mostly doesn't need peephole optimization.

>
> -- hendrik
>
> _______________________________________________
> libre-riscv-dev mailing list
> libre-riscv-dev at lists.libre-riscv.org
> http://lists.libre-riscv.org/mailman/listinfo/libre-riscv-dev
>