clmulh

Bits<5> xs2 = $encoding[24:20];
Bits<5> xs1 = $encoding[19:15];
Bits<5> xd = $encoding[11:7];

XReg xs1_val = X[xs1];
XReg xs2_val = X[xs2];
XReg output = 0;
for (U32 i = 1; i <= xlen(); i++) {
  output = (xs2_val : output;
}
X[xd] = output;