const (
	BIG = 2048 - 8
)

const (
	/* mark flags */
	LABEL = 1 << iota
	LEAF
	FLOAT
	BRANCH
	LOAD
	FCMP
	SYNC
	LIST
	FOLL
	NOSCHED
)

const (
	// optab is sorted based on the order of these constants
	// and the first match is chosen.
	// The more specific class needs to come earlier.
	C_NONE   = iota + 1 // starting from 1, leave unclassified Addr's class as 0

	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"

//	VTHING ymm2/m256, ymmV, ymm1
//
// The opcode array in the corresponding Optab entry
// should contain the (VEX prefixes, opcode byte) pair
// for each of the two forms.
// For example, the entries for VPXOR are:
//
//	VPXOR xmm2/m128, xmmV, xmm1
//	VEX.NDS.128.66.0F.WIG EF /r
//
//	VPXOR ymm2/m256, ymmV, ymm1
//	VEX.NDS.256.66.0F.WIG EF /r
//
// Produce this optab entry:
//

	// 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 {