[Bug tree-optimization/106019] New: Surprising SLP failure on trivial code

[amonakov at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106019

            Bug ID: 106019
           Summary: Surprising SLP failure on trivial code
           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: amonakov at gcc dot gnu.org
  Target Milestone: ---

In the following code, 'f' is not SLP-vectorized, but 'g' is. From a brief look
at slp2 dump, looks like dependence analysis for p[i] vs. p[i+1] fails?

void f(double *p, long i)
{
    p[i+0] += 1;
    p[i+1] += 1;
}
void g(double *p, long i)
{
    double *q = p + i;
    q[0] += 1;
    q[1] += 1;
}