Don't generate silly matching code like this:

 if (N1.getOpcode() == ISD::ADD &&
     ...)
   if (... &&
       (N1.getNumOperands() == 1 || !isNonImmUse(N1.Val, N10.Val))) &&
       ...)

TableGen knows N1 must have more than one operand.

llvm-svn: 26592