[Bug tree-optimization/104579] New: vectorizer failed to reduce max & index search together

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104579

            Bug ID: 104579
           Summary: vectorizer failed to reduce max & index search
                    together
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: crazylht at gmail dot com
  Target Milestone: ---

int max (int *src, int n, int *position)
{
  int maxInt;
  int maxIndex;
  int i;

  maxInt = src[0];
  maxIndex = 0;
  for (i = 1; i < n; i++) {
    if (maxInt < src[i]) {
      maxInt = src[i];
      maxIndex = i;
    }
  }
  *position = maxIndex;
  return (maxInt);
}

GCC can reduce max and index search separately, but not together.