[LLVMdev] RFC: Pass Manager Redux (original) (raw)

Chandler Carruth chandlerc at gmail.com
Fri Jul 13 02:44:14 PDT 2012

On Wed, Jul 11, 2012 at 11:49 PM, Florian Brandner <flbr at imm.dtu.dk> wrote:

On Wed July 11 2012 11:50:01 Chandler Carruth wrote: > - What else did I miss? > > > Things that are totally out of scope: pass registration, the current pass order and structure, the fundamental interface of mapping from a pass to an analysis, etc. This is really about pass management and scheduling. >

Hi Chandler, I understand why the pass registration and the pass order/structure is out of scope for your work. However, as others have already noted, there are problems that are somewhat related to how pass scheduling works. From my perspective, the current way we specify the pass order/structure is too much spread all over different places.

Really? It seems fairly reasonable to me: the PassManagerBuilder has the canonical bits for a reasonable optimization pipeline combined with extension hooks that clients can use to inject custom passes into reasonable places in the pipeline.

I don't see a huge problem here, and so I'd like to keep the scope narrow. If you do see problems, i would build on top of the hopefully cleaner version. =]

One idea, for instance, could be to extend tablegen to specify pass pipelines,

I don't think this is useful. We can define reasonable and clear natural C++ interfaces for this.

Another important point are passes in the backend. Currently we have some

severe limitations there (for instance, all codegen passes have to be function passes). It would be great if the full flexibility of the pass scheduling framework could be preserved even in the backend.

I agree that backend passes are important, but don't want to go there for this effort. It's just not in scope at all. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20120713/f49f9d3a/attachment.html>

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