[llvm] [MCA] Do not allocate space for DependenceEdge by default in DependencyGraphNode (NFC) (PR #125080)

[Min-Yih Hsu via llvm-commits]

https://github.com/mshockwave approved this pull request.

> Number of  | Number of nodes with
> edges      | this # of edges
> ---------------------------------
>          0 | 8239447
>          1 | 464252
>          2 | 6164
>          3 | 6783
>          4 | 939
>          5 | 500
>          6 | 545
>          7 | 116
>          8 | 2
>          9 | 1
>         10 | 1

This is an interesting distribution. If my math is correct ~95% of the nodes have no out-going edges. Thus I  think this is a reasonable change.

https://github.com/llvm/llvm-project/pull/125080