[llvm-dev] [RFC] Tablegen-erated GlobalISel Combine Rules

[David Greene via llvm-dev]

Quentin Colombet <quentin.colombet at gmail.com> writes:

>     And are there any realistic alternatives for declarative
>     representations combines?
>
> Realistic I would have thought we can use the syntax we already have
> for SDISel.
> In other words, people wouldn’t have to learn yet another way of doing
> combines and when we are ready we can move everything (isel +
> combines) in one go.

I don't think I'd want to see things go that way.  Current SDISel
patterns are very limited and impose a lot of hacky workarounds for
not-too-uncommon things.  If anything, I anticipate migrating isel to
what Daniel outlines rather than migrating combine to SDISel and then
migrating to yet another thing after that.

                        -David