if i >= 0 { // float PR
		return OpArgFloatReg, i
	}
	return OpArgIntReg, int64(r)
}

type selKey struct {
	from          *Value // what is selected from
	offsetOrIndex int64  // whatever is appropriate for the selector
	size          int64
	typ           *types.Type
}

type expandState struct {
	f       *Func

		// type literal. For example, given "type Int = int" (#50190),
		// it would be incorrect to format "struct{ Int }" as either
		// "struct{ int }" or "struct{ Int int }", because those each
		// represent other, distinct types.
		//
		// So for the purpose of LinkString (i.e., fmtTypeID), we use
		// the non-standard syntax "struct{ Int = int }" to represent
		// embedded fields that have been renamed through the use of
		// type aliases.

		if expr == nil {
			expr = cond
		} else {
			expr = ir.NewLogicalExpr(base.Pos, andor, expr, cond)
		}
	}
	cmpl = safeExpr(cmpl, init)
	cmpr = safeExpr(cmpr, init)
	if t.IsStruct() {
		conds, _ := compare.EqStruct(t, cmpl, cmpr)
		if n.Op() == ir.OEQ {
			for _, cond := range conds {
				and(cond)
			}
		} else {
			for _, cond := range conds {
				notCond := ir.NewUnaryExpr(base.Pos, ir.ONOT, cond)

// when a type's width should be known, we call CheckSize
// to compute it.  during a declaration like
//
//	type T *struct { next T }
//
// it is necessary to defer the calculation of the struct width
// until after T has been initialized to be a pointer to that struct.
// similarly, during import processing structs may be used
// before their definition.  in those situations, calling
// DeferCheckSize() stops width calculations until

		// not supported on SSA variables.
		// TODO: allow if all indexes are constant.
		if t.NumElem() <= 1 {
			return CanSSA(t.Elem())
		}
		return false
	case types.TSTRUCT:
		if t.NumFields() > MaxStruct {
			return false
		}
		for _, t1 := range t.Fields() {
			if !CanSSA(t1.Type) {
				return false
			}
		}
		return true
	default:
		return true
	}

		}
	}

	return ir.OXXX, ""
}

// Code to resolve elided DOTs in embedded types.

// A dlist stores a pointer to a TFIELD Type embedded within
// a TSTRUCT or TINTER Type.
type dlist struct {
	field *types.Field
}

// dotpath computes the unique shortest explicit selector path to fully qualify
// a selection expression x.f, where x is of type t and f is the symbol s.

	case types.TSTRING:
		// struct { byte *str; int len; }
		clobberPtr(b, v, offset)

	case types.TINTER:
		// struct { Itab *tab; void *data; }
		// or, when isnilinter(t)==true:
		// struct { Type *type; void *data; }
		clobberPtr(b, v, offset)
		clobberPtr(b, v, offset+int64(types.PtrSize))

	case types.TSLICE:
		// struct { byte *array; int len; int cap; }

// index'th field of the given expression, which must be of struct or
// pointer-to-struct type.
func DotField(pos src.XPos, x ir.Node, index int) *ir.SelectorExpr {
	op, typ := ir.ODOT, x.Type()
	if typ.IsPtr() {
		op, typ = ir.ODOTPTR, typ.Elem()
	}
	if !typ.IsStruct() {
		base.FatalfAt(pos, "DotField of non-struct: %L", x)
	}

	// TODO(mdempsky): This is the backend's responsibility.

	types.TFLOAT32:    "float32",
	types.TFLOAT64:    "float64",
	types.TBOOL:       "bool",
	types.TSTRING:     "string",
	types.TPTR:        "pointer",
	types.TUNSAFEPTR:  "unsafe.Pointer",
	types.TSTRUCT:     "struct",
	types.TINTER:      "interface",
	types.TCHAN:       "chan",
	types.TMAP:        "map",
	types.TARRAY:      "array",
	types.TSLICE:      "slice",
	types.TFUNC:       "func",
	types.TNIL:        "nil",

        IN 3: R{ } offset: 40 typ: struct { float64; struct { [2]int64; struct {} }; struct {} }
        IN 4: R{ } offset: 80 typ: struct { float64; struct { [2]int64; struct {} }; struct {} }
        OUT 0: R{ } offset: 120 typ: struct { float64; struct { [2]int64; struct {} }; struct {} }
        OUT 1: R{ } offset: 160 typ: [2]bool
        OUT 2: R{ } offset: 168 typ: struct { float64; struct { [2]int64; struct {} }; struct {} }