As       As        // assembler opcode
	Reg      int16     // 2nd source operand
	RegTo2   int16     // 2nd destination operand
	Mark     uint16    // bitmask of arch-specific items
	Optab    uint16    // arch-specific opcode index
	Scond    uint8     // bits that describe instruction suffixes (e.g. ARM conditions, RISCV Rounding Mode)
	Back     uint8     // for x86 back end: backwards branch state

				// same check.
				shift = 7
			}
			p.From.Type = obj.TYPE_REG
			p.From.Reg = int16(REG_LSL + r + (shift&7)<<5)
			p.From.Offset = 0
		}
	}
}

func nocache(p *obj.Prog) {
	p.Optab = 0
	p.From.Class = 0
	p.To.Class = 0
}

var unaryDst = map[obj.As]bool{
	AWORD:  true,
	ADWORD: true,
	ABL:    true,
	AB:     true,
	ACLREX: true,
}

			p.As = AANDISCC
			p.From.Offset >>= 16
		}

	// To maintain backwards compatibility, we accept some 4 argument usage of
	// several opcodes which was likely not intended, but did work. These are not
	// added to optab to avoid the chance this behavior might be used with newer
	// instructions.
	//
	// Rewrite argument ordering like "ADDEX R3, $3, R4, R5" into
	//                                "ADDEX R3, R4, $3, R5"

	// function symbol names are prefixed here with '.' to avoid
	// a dependency on the reflect package.
	syms = make(map[string]any, len(md.ptab))
	for _, ptab := range md.ptab {
		symName := resolveNameOff(unsafe.Pointer(md.types), ptab.name)
		t := toRType((*_type)(unsafe.Pointer(md.types))).typeOff(ptab.typ) // TODO can this stack of conversions be simpler?
		var val any
		valp := (*[2]unsafe.Pointer)(unsafe.Pointer(&val))

	slice(itablinkSym, nitablinks)

	// The ptab slice
	if ptab := ldr.Lookup("go:plugin.tabs", 0); ptab != 0 && ldr.AttrReachable(ptab) {
		ldr.SetAttrLocal(ptab, true)
		if ldr.SymType(ptab) != sym.SRODATA {
			panic(fmt.Sprintf("go:plugin.tabs is %v, not SRODATA", ldr.SymType(ptab)))
		}
		nentries := uint64(len(ldr.Data(ptab)) / 8) // sizeof(nameOff) + sizeof(typeOff)
		slice(ptab, nentries)
	} else {
		nilSlice()
	}

		// Trigger panic for method on nil interface now.
		// Otherwise it happens in the wrapper and is confusing.
		n.X = cheapExpr(n.X, init)
		n.X = walkExpr(n.X, nil)

		tab := ir.NewUnaryExpr(base.Pos, ir.OITAB, n.X)
		check := ir.NewUnaryExpr(base.Pos, ir.OCHECKNIL, tab)
		init.Append(typecheck.Stmt(check))
	}

	typ := typecheck.MethodValueType(n)

	clos := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, typ, nil)

	// so that a debugger-user sees the stop before the panic, and can examine the value.
	case OpAddr, OpLocalAddr, OpOffPtr, OpStructSelect, OpPhi, OpITab, OpIData,
		OpIMake, OpStringMake, OpSliceMake, OpStructMake0, OpStructMake1, OpStructMake2, OpStructMake3, OpStructMake4,
		OpConstBool, OpConst8, OpConst16, OpConst32, OpConst64, OpConst32F, OpConst64F, OpSB, OpSP,

// from an interface's descriptor word (whether a *runtime._type or
// *runtime.itab pointer).
func typeHashFieldOf(pos src.XPos, itab *ir.UnaryExpr) *ir.SelectorExpr {
	if itab.Op() != ir.OITAB {
		base.Fatalf("expected OITAB, got %v", itab.Op())
	}
	var hashField *types.Field
	if itab.X.Type().IsEmptyInterface() {
		// runtime._type's hash field
		if rtypeHashField == nil {

			n.SetType(nil)
			return n
		}
	}
	return n
}

// tcITab typechecks an OITAB node.
func tcITab(n *ir.UnaryExpr) ir.Node {
	n.X = Expr(n.X)
	t := n.X.Type()
	if t == nil {
		n.SetType(nil)
		return n
	}
	if !t.IsInterface() {
		base.Fatalf("OITAB of %v", t)
	}
	n.SetType(types.NewPtr(types.Types[types.TUINTPTR]))
	return n
}

			ir.OAND, ir.OANDNOT, ir.OLSH, ir.OOR, ir.ORSH, ir.OXOR, ir.OCOMPLEX, ir.OMAKEFACE,
			ir.OADDR, ir.OBITNOT, ir.ONOT, ir.OPLUS,
			ir.OCAP, ir.OIMAG, ir.OLEN, ir.OREAL,
			ir.OCONVNOP, ir.ODOT,
			ir.OCFUNC, ir.OIDATA, ir.OITAB, ir.OSPTR,
			ir.OBYTES2STRTMP, ir.OGETG, ir.OGETCALLERPC, ir.OGETCALLERSP, ir.OSLICEHEADER, ir.OSTRINGHEADER:
			// ok: operations that don't require function calls.
			// Expand as needed.
		}

		return false