[Bug tree-optimization/46722] New: [4.6 Regression] Missed fma for x*x + y

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46722

           Summary: [4.6 Regression] Missed fma for x*x + y
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: rgue...@gcc.gnu.org


double foo(double x, double y)
{
  return x*x + y;
}

no longer generates fused multiply-add instructions.  This is because
we canonicalize x*x to pow(x, 2) which we do not recognize during
FMA detection.