[LLVMdev] alias-aware scheduling

Chris Lattner sabre at nondot.org
Tue Dec 19 15:42:51 PST 2006

On Tue, 19 Dec 2006, Evan Cheng wrote:
> As you have seen there is transformations in dag combiner to
> eliminate the unnecessary chain operands. It's not turned on by
> default. Are you not getting satisfactory results by turning it on?

The code in the dag combiner does some simple things, but doesn't yet make 
use of the AliasAnalysis interface.  We haven't had a chance to pursue it 
fully (been distracted with other things) but at the time it wasn't turned 
on due to slow compile-time issues.  If the code was adequately throttled 
back, I think this wouldn't be an issue.

Independent of approach though, I think it is best to do the 
disambiguation before the scheduler.  This allows the dag combiner to take 
advantage of information exposed by the disambiguation (e.g. redundant 
loads get squashed, exposing arithmetic identities, etc).

Dan, what do you think of this idea?



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