[llvm-commits] value range analysis based on scalar-evolutions

[Chris Lattner]

On Jun 1, 2008, at 8:54 PM, Nick Lewycky wrote:

> I've implemented an analysis pass that uses SCEV to determine value  
> ranges of integer-typed registers.
>
> Currently it maintains a map of Value* to ConstantRange*, which is  
> rather inelegant. I was thinking we could have one analysis which  
> would do that and others that would update the central analysis.
>
> I also implemented an optz'n pass based on it, but it hardly  
> optimized anything and as such is not included in this patch.

Hey Nick,

Are you still working on this?  It looks like a really interesting  
approach.  As Dan says, it would be best if it were lazy (computing  
ranges when queried instead of in runOnFunction), but otherwise it  
would be nice to go in the tree.

-Chris