[Bug tree-optimization/67323] New: Use non-unit stride loads by preference when applicable

["michael.collison at linaro dot org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67323

            Bug ID: 67323
           Summary: Use non-unit stride loads by preference when
                    applicable
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: michael.collison at linaro dot org
  Target Milestone: ---

On arm targets the following code fails to generate a vld3:

struct pixel {
  char r,g,b;
};

void 
t2(int len, struct pixel * __restrict p, struct pixel * __restrict x)
{
  len = len & ~31;
  for (int i = 0; i < len; i++){
      p[i].r = x[i].r * 2;
      p[i].g = x[i].g * 3;
      p[i].b = x[i].b * 4;
  }
}

Yes the same code with line 11 changed to:

p[i].g = x[i].g;

does generate a vld3.