[llvm] [DA] use NSW arithmetic (PR #116632)

[Michael Kruse via llvm-commits]

Meinersbur wrote:

Can you update the description? "make sure the SCEVs are marked as non wrap arithmetic" doesn't match to the current code diff.

For adding NSW, I crafted some example:
```
for (uint32_t i = 0x02; i < min((uint32_t)n,2); i+= 0x7FFFFFFF) {
   if (i == 0x02)
    A[0x80000001] = 42;
  else if (i == 0x80000001)
    use(A[i]);
}
```
there should be a RAW dependencies from (i==0 to i==0x80000001). The AddRec for `i` should be marked as non-self-wrapping (and NUW) due to the restricted trip count. If we create a new AddRec for the subscript of `A[i]` with NSW, SCEV might the only valid value for `i` is `i==0`, because for `i==1` the value `0x02 + 1*0x7FFFFFFF` is wrapping a signed integer. DependenceInfo therefore might conclude there is no dependency ⚡



https://github.com/llvm/llvm-project/pull/116632