dependence analysis

I am looking at analyzing llvm IR and discovering some data dependence between values. I presently have code that looks like

i32 %5 = …
i32 %6 = sub i32 %5 , 1

Is there a method in llvm that I can query to find out that these differ by 1 always ? or do i need to write such a method myself for this functionality.

Thanks a lot for your help

Aparna

Graduate Student
University of Maryland, College Park