[llvm] [DA] Fix the check between Subscript and Size after delinearization (PR #151326)

[Michael Kruse via llvm-commits]

================
@@ -719,12 +719,14 @@ for.end:                                          ; preds = %for.body
 ;;    for(int j = 0; j < M; j+=1)
 ;;      A[M*N + M*i + j] = 2;
 
+; FIXME: Currently failing to infer %M being positive.
----------------
Meinersbur wrote:

Looks like header guards for `%M` being negative are not present. There is one for `%N` though, but seems `for.body.us` is executed at least once with negative `%M`

https://github.com/llvm/llvm-project/pull/151326