[Bug target/68494] New: [ARM] Use vector multiply by lane

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68494

            Bug ID: 68494
           Summary: [ARM] Use vector multiply by lane
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: michael.collison at linaro dot org
  Target Milestone: ---

The following test case should utilize vector multiply by a single lane.

short taps[4];

void fir_t5(int len, short * __restrict p, short *__restrict x, short
*__restrict taps)
{
  len = len & ~31;
  for (int i = 0; i < len; i++)
    {
      int tmp = 0;
      for (int j = 0; j < NTAPS; j++)
        {
          tmp += x[i - j] * taps[j];
        }

      p[i] = tmp;
    }
}