switch e := e.(type) {
	case *ast.BinaryExpr:
		if int(e.Op) < len(op2str2) {
			return op2str2[e.Op]
		}
	case *ast.UnaryExpr:
		if int(e.Op) < len(op2str1) {
			return op2str1[e.Op]
		}
	}
	return ""
}

var op2str1 = [...]string{
	token.XOR: "bitwise complement",
}

// This is only used for operations that may cause overflow.
var op2str2 = [...]string{
	token.ADD: "addition",

		op := int(e.Op)
		if e.Y == nil {
			if op < len(op2str1) {
				return op2str1[op]
			}
		} else {
			if op < len(op2str2) {
				return op2str2[op]
			}
		}
	}
	return ""
}

var op2str1 = [...]string{
	syntax.Xor: "bitwise complement",
}

// This is only used for operations that may cause overflow.
var op2str2 = [...]string{
	syntax.Add: "addition",

		if isRegShiftOrExt(&p.To) {
			// extended or shifted offset register.
			c.checkShiftAmount(p, &p.To)

			o1 = c.opstrr(p, p.As, true)
			o1 |= c.encRegShiftOrExt(p, &p.To, p.To.Index) /* includes reg, op, etc */
		} else {
			// (Rn)(Rm), no extension or shift.
			o1 = c.opstrr(p, p.As, false)
			o1 |= uint32(p.To.Index&31) << 16
		}
		o1 |= uint32(p.To.Reg&31) << 5
		rf := int(p.From.Reg)

}

// Create description of operation that could not be converted.
static std::string GetOpDescriptionForDebug(Operation* inst) {
  const int kLargeElementsAttr = 16;
  std::string op_str;
  llvm::raw_string_ostream os(op_str);
  inst->getName().print(os);
  os << "(";
  if (!inst->getOperandTypes().empty()) {
    bool first = true;
    for (Type operand_type : inst->getOperandTypes()) {

	op_STPX    uint32 = 0xB211 // FORMAT_S          STORE PREFIX
	op_STRAG   uint32 = 0xE502 // FORMAT_SSE        STORE REAL ADDRESS
	op_STRL    uint32 = 0xC40F // FORMAT_RIL2       STORE RELATIVE LONG (32)
	op_STRV    uint32 = 0xE33E // FORMAT_RXY1       STORE REVERSED (32)
	op_STRVG   uint32 = 0xE32F // FORMAT_RXY1       STORE REVERSED (64)