x86 Instruction Set Reference

UD2 - Undefined Instruction

Opcode Mnemonic Description
0F 0B UD2 Raise invalid opcode exception.
Description

Generates an invalid opcode. This instruction is provided for software testing to explicitly generate an invalid opcode. The opcode for this instruction is reserved for this purpose.

Other than raising the invalid opcode exception, this instruction is the same as the NOP instruction.
Operation 
Exception(UD); //Generates invalid opcode exception
Flags affected

None.