Llvm.Opcode

`sig type t = Invalid | Ret | Br | Switch | IndirectBr | Invoke | Invalid2 | Unreachable | Add | FAdd | Sub | FSub | Mul | FMul | UDiv | SDiv | FDiv | URem | SRem | FRem | Shl | LShr | AShr | And | Or | Xor | Alloca | Load | Store | GetElementPtr | Trunc | ZExt | SExt | FPToUI | FPToSI | UIToFP | SIToFP | FPTrunc | FPExt | PtrToInt | IntToPtr | BitCast | ICmp | FCmp | PHI | Call | Select | UserOp1 | UserOp2 | VAArg | ExtractElement | InsertElement | ShuffleVector | ExtractValue | InsertValue | Fence | AtomicCmpXchg | AtomicRMW | Resume | LandingPad end`