[LLVMdev] PassManager

[Vikram Adve]

On Nov 8, 2006, at 8:32 PM, Chris Lattner wrote:

> On Wed, 8 Nov 2006, Vikram Adve wrote:
>> ... you would relax that policy for cases where the pass wants
>> control over its order of visitation.  In fact , some passes (e.g.,
>> loop tiling) may want to do two or more transforms on a set of loops
>> at a time.  E.g., loop tiling needs to do strip-mining on a loop,
>> then interchange one of the resulting loops with *some* outer loop
>> (which one depends on the pattern of accesses in the code).  It would
>> be nice for the LPM to have the flexibility to accommodate such
>> passes better than just requiring them to always work at the
>> outermost loop level.
>
> I think that the design will handle this.  This isn't a matter of  
> changing
> order of iteration.  This is a matter of making sure that the new  
> loops
> that are created get revisited.  This is exactly what the worklist is
> design for.
>
> In any case, Devang has plenty of things to do to the current pass mgr
> and the current loop optimizations before we start worrying about new
> optzns.  When that happens we'll have experience from moving the  
> extant
> loop optimizers over to guide the right design.


Yes, I agree.  Let's talk about this when he gets to the stage of  
writing the LPM or adding new loop optimizations.

--Vikram
http://www.cs.uiuc.edu/~vadve
http://llvm.cs.uiuc.edu/