[LLVMdev] PassManager

[Chris Lattner]

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.

-Chris

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