Memory Dependency Analysis

Hello all,
I’m using the DependenceAnalysisWrapperPass to compute memory dependencies between instructions. However, for the following code, it finds no dependencies at all.
Is this Pass working?

define i32 @foo(i32 %a, float %b) {
%1 = alloca i32, align 4
store i32 %a, i32* %1, align 4
%2 = load i32, i32* %1, align 4
ret i32 %2
}

I also noticed that there is a MemoryDependenceAnalysis Pass. Which one should I use?

Thanks,
Juan