[llvm-dev] [RFC] Introducing classes for the codegen driven by new pass manager

[Chen, Yuanfang via llvm-dev]

Thanks Matt. That's really helpful. Seems like I need to rethink the pass registration a little bit.

________________________________________
From: Matt Arsenault <whatmannerofburgeristhis at gmail.com> on behalf of Matt Arsenault <arsenm2 at gmail.com>
Sent: Wednesday, July 15, 2020 9:43 AM
To: Chen, Yuanfang
Cc: Robinson, Paul; llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] [RFC] Introducing classes for the codegen driven by new pass manager



> On Jul 15, 2020, at 12:39, Chen, Yuanfang <Yuanfang.Chen at sony.com> wrote:
>
> Indeed, but there is a distinction about their position in the pipeline. We run opt & codegen pipeline separately, “codegen” IR passes run with other “codegen” IR passes. The same goes for regular IR passes.
>
> Do you run “codegen” IR passes with regular IR passes? If so, do you mind sharing the use cases? I might have missed this use case.

I suppose there are 3 cases:

1. IR passes that are run in the codegen pipeline, but also run in the regular optimization pipeline. For example, AMDGPU runs SROA and a few other “noncodegen” IR passes as part of codegen. These obviously are both.
2. Reducing testcases. I extract the IR at some point in the codegen pipeline, and want to see what happens if I ran other passes at that point.
3. Experiments to see if there is value in moving a codegen IR pass earlier in the pipeline, into the non-codegen IR passes

-Matt