[llvm-dev] RFC/bikeshedding: Separation of instruction and pattern definitions in LLVM backends

[John Leidel via llvm-dev]

I agree with David's sentiment.  The second method appears to be easier to
follow.  IMHO, this would be easier for external users that desire to
modify the backend for their own custom extensions/instructions.

On Fri, Aug 18, 2017 at 5:05 AM, David Chisnall <David.Chisnall at cl.cam.ac.uk
> wrote:

> On 18 Aug 2017, at 10:55, Alex Bradbury <asb at asbradbury.org> wrote:
> >
> > I've demonstrated both the "conventional" approach
> > <https://gist.github.com/asb/0c61ebc131076c6186052c29968a49
> 1d#file-riscvinstrinfo_conventional-td>
> > and the "separate patterns" approach
> > <https://gist.github.com/asb/0c61ebc131076c6186052c29968a49
> 1d#file-riscvinstrinfo_separate_pats-td>.
> > Obviously once patterns and pseudo-instructions are separated out, you
> may
> > want to move them to a different .td file.
> >
> > Does anyone have strong views on these sort of choices one way or
> another?
>
> I do find the second easier to follow, though both are a lot easier to
> read than the MIPS back end.
>
> David
>
>
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