reader.go

			kv := ir.NewKeyExpr(r.pos(), r.expr(), nil)
			*elemp, elemp = kv, &kv.Value
		}

		*elemp = wrapName(r.pos(), r.expr())
	}

	lit := typecheck.Expr(ir.NewCompLitExpr(pos, ir.OCOMPLIT, typ, elems))
	if rtype != nil {
		lit := lit.(*ir.CompLitExpr)
		lit.RType = rtype
	}
	if typ0.IsPtr() {
		lit = typecheck.Expr(typecheck.NodAddrAt(pos, lit))
		lit.SetType(typ0)
	}
	return lit
}

func wrapName(pos src.XPos, x ir.Node) ir.Node {
	// These nodes do not carry line numbers.
	// Introduce a wrapper node to give them the correct line.
	switch ir.Orig(x).Op() {
	case ir.OTYPE, ir.OLITERAL:
		if x.Sym() == nil {
			break
		}
		fallthrough
	case ir.ONAME, ir.ONONAME, ir.ONIL:
		p := ir.NewParenExpr(pos, x)
		p.SetImplicit(true)
		return p
	}
	return x
}

func (r *reader) funcLit() ir.Node {
	r.Sync(pkgbits.SyncFuncLit)

	// The underlying function declaration (including its parameters'
	// positions, if any) need to remain the original, uninlined
	// positions. This is because we track inlining-context on nodes so
	// we can synthesize the extra implied stack frames dynamically when
	// generating tracebacks, whereas those stack frames don't make
	// sense *within* the function literal. (Any necessary inlining
	// adjustments will have been applied to the call expression
	// instead.)
	//
	// This is subtle, and getting it wrong leads to cycles in the
	// inlining tree, which lead to infinite loops during stack
	// unwinding (#46234, #54625).
	//
	// Note that we *do* want the inline-adjusted position for the
	// OCLOSURE node, because that position represents where any heap
	// allocation of the closure is credited (#49171).
	r.suppressInlPos++
	pos := r.pos()
	xtype2 := r.signature(types.LocalPkg, nil)
	r.suppressInlPos--

	fn := ir.NewClosureFunc(pos, r.curfn != nil)
	clo := fn.OClosure
	clo.SetPos(r.inlPos(pos)) // see comment above
	ir.NameClosure(clo, r.curfn)

	setType(fn.Nname, xtype2)
	typecheck.Func(fn)
	setType(clo, fn.Type())

	fn.ClosureVars = make([]*ir.Name, 0, r.Len())
	for len(fn.ClosureVars) < cap(fn.ClosureVars) {
		ir.NewClosureVar(r.pos(), fn, r.useLocal())
	}
	if param := r.dictParam; param != nil {
		// If we have a dictionary parameter, capture it too. For
		// simplicity, we capture it last and unconditionally.
		ir.NewClosureVar(param.Pos(), fn, param)
	}

	r.addBody(fn, nil)

	// TODO(mdempsky): Remove hard-coding of typecheck.Target.
	return ir.UseClosure(clo, typecheck.Target)
}

func (r *reader) exprList() []ir.Node {
	r.Sync(pkgbits.SyncExprList)
	return r.exprs()
}

func (r *reader) exprs() []ir.Node {
	r.Sync(pkgbits.SyncExprs)
	nodes := make([]ir.Node, r.Len())
	if len(nodes) == 0 {
		return nil // TODO(mdempsky): Unclear if this matters.
	}
	for i := range nodes {
		nodes[i] = r.expr()
	}
	return nodes
}

// dictWord returns an expression to return the specified
// uintptr-typed word from the dictionary parameter.
func (r *reader) dictWord(pos src.XPos, idx int) ir.Node {
	base.AssertfAt(r.dictParam != nil, pos, "expected dictParam in %v", r.curfn)
	return typecheck.Expr(ir.NewIndexExpr(pos, r.dictParam, ir.NewBasicLit(pos, constant.MakeInt64(int64(idx)))))
}

// rttiWord is like dictWord, but converts it to *byte (the type used
// internally to represent *runtime._type and *runtime.itab).
func (r *reader) rttiWord(pos src.XPos, idx int) ir.Node {
	return typecheck.Expr(ir.NewConvExpr(pos, ir.OCONVNOP, types.NewPtr(types.Types[types.TUINT8]), r.dictWord(pos, idx)))
}

// rtype reads a type reference from the element bitstream, and
// returns an expression of type *runtime._type representing that
// type.
func (r *reader) rtype(pos src.XPos) ir.Node {
	_, rtype := r.rtype0(pos)
	return rtype
}

func (r *reader) rtype0(pos src.XPos) (typ *types.Type, rtype ir.Node) {
	r.Sync(pkgbits.SyncRType)
	if r.Bool() { // derived type
		idx := r.Len()
		info := r.dict.rtypes[idx]
		typ = r.p.typIdx(info, r.dict, true)
		rtype = r.rttiWord(pos, r.dict.rtypesOffset()+idx)
		return
	}

	typ = r.typ()
	rtype = reflectdata.TypePtrAt(pos, typ)
	return
}

// varDictIndex populates name.DictIndex if name is a derived type.
func (r *reader) varDictIndex(name *ir.Name) {
	if r.Bool() {
		idx := 1 + r.dict.rtypesOffset() + r.Len()
		if int(uint16(idx)) != idx {
			base.FatalfAt(name.Pos(), "DictIndex overflow for %v: %v", name, idx)
		}
		name.DictIndex = uint16(idx)
	}
}

func (r *reader) itab(pos src.XPos) (typ *types.Type, typRType ir.Node, iface *types.Type, ifaceRType ir.Node, itab ir.Node) {
	if r.Bool() { // derived types
		idx := r.Len()
		info := r.dict.itabs[idx]
		typ = r.p.typIdx(info.typ, r.dict, true)
		typRType = r.rttiWord(pos, r.dict.itabsOffset()+3*idx)
		iface = r.p.typIdx(info.iface, r.dict, true)
		ifaceRType = r.rttiWord(pos, r.dict.itabsOffset()+3*idx+1)
		itab = r.rttiWord(pos, r.dict.itabsOffset()+3*idx+2)
		return
	}

	typ = r.typ()
	iface = r.typ()
	if iface.IsInterface() {
		typRType = reflectdata.TypePtrAt(pos, typ)
		ifaceRType = reflectdata.TypePtrAt(pos, iface)
		if !typ.IsInterface() && !iface.IsEmptyInterface() {
			lsym := reflectdata.ITabLsym(typ, iface)
			itab = typecheck.LinksymAddr(pos, lsym, types.Types[types.TUINT8])
		}
	}
	return
}

// convRTTI returns expressions appropriate for populating an
// ir.ConvExpr's TypeWord and SrcRType fields, respectively.
func (r *reader) convRTTI(pos src.XPos) (typeWord, srcRType ir.Node) {
	r.Sync(pkgbits.SyncConvRTTI)
	src, srcRType0, dst, dstRType, itab := r.itab(pos)
	if !dst.IsInterface() {
		return
	}

	// See reflectdata.ConvIfaceTypeWord.
	switch {
	case dst.IsEmptyInterface():
		if !src.IsInterface() {
			typeWord = srcRType0 // direct eface construction
		}
	case !src.IsInterface():
		typeWord = itab // direct iface construction
	default:
		typeWord = dstRType // convI2I
	}

	// See reflectdata.ConvIfaceSrcRType.
	if !src.IsInterface() {
		srcRType = srcRType0
	}

	return
}

func (r *reader) exprType() ir.Node {
	r.Sync(pkgbits.SyncExprType)
	pos := r.pos()

	var typ *types.Type
	var rtype, itab ir.Node

	if r.Bool() {
		typ, rtype, _, _, itab = r.itab(pos)
		if typ.IsInterface() {
			itab = nil
		} else {
			rtype = nil // TODO(mdempsky): Leave set?
		}
	} else {
		typ, rtype = r.rtype0(pos)

		if !r.Bool() { // not derived
			// TODO(mdempsky): ir.TypeNode should probably return a typecheck'd node.
			n := ir.TypeNode(typ)
			n.SetTypecheck(1)
			return n
		}
	}

	dt := ir.NewDynamicType(pos, rtype)
	dt.ITab = itab
	return typed(typ, dt)
}

func (r *reader) op() ir.Op {
	r.Sync(pkgbits.SyncOp)
	return ir.Op(r.Len())
}

// @@@ Package initialization

func (r *reader) pkgInit(self *types.Pkg, target *ir.Package) {
	cgoPragmas := make([][]string, r.Len())
	for i := range cgoPragmas {
		cgoPragmas[i] = r.Strings()
	}
	target.CgoPragmas = cgoPragmas

	r.pkgDecls(target)

	r.Sync(pkgbits.SyncEOF)
}

func (r *reader) pkgDecls(target *ir.Package) {
	r.Sync(pkgbits.SyncDecls)
	for {
		switch code := codeDecl(r.Code(pkgbits.SyncDecl)); code {
		default:
			panic(fmt.Sprintf("unhandled decl: %v", code))

		case declEnd:
			return

		case declFunc:
			names := r.pkgObjs(target)
			assert(len(names) == 1)
			target.Decls = append(target.Decls, names[0].Func)

		case declMethod:
			typ := r.typ()
			_, sym := r.selector()

			method := typecheck.Lookdot1(nil, sym, typ, typ.Methods(), 0)
			target.Decls = append(target.Decls, method.Nname.(*ir.Name).Func)

		case declVar:
			pos := r.pos()
			names := r.pkgObjs(target)
			values := r.exprList()

			if len(names) > 1 && len(values) == 1 {
				as := ir.NewAssignListStmt(pos, ir.OAS2, nil, values)
				for _, name := range names {
					as.Lhs.Append(name)
					name.Defn = as
				}
				target.Decls = append(target.Decls, as)
			} else {
				for i, name := range names {
					as := ir.NewAssignStmt(pos, name, nil)
					if i < len(values) {
						as.Y = values[i]
					}
					name.Defn = as
					target.Decls = append(target.Decls, as)
				}
			}

			if n := r.Len(); n > 0 {
				assert(len(names) == 1)
				embeds := make([]ir.Embed, n)
				for i := range embeds {
					embeds[i] = ir.Embed{Pos: r.pos(), Patterns: r.Strings()}
				}
				names[0].Embed = &embeds
				target.Embeds = append(target.Embeds, names[0])
			}

		case declOther:
			r.pkgObjs(target)
		}
	}
}

func (r *reader) pkgObjs(target *ir.Package) []*ir.Name {
	r.Sync(pkgbits.SyncDeclNames)
	nodes := make([]*ir.Name, r.Len())
	for i := range nodes {
		r.Sync(pkgbits.SyncDeclName)

		name := r.obj().(*ir.Name)
		nodes[i] = name

		sym := name.Sym()
		if sym.IsBlank() {
			continue
		}

		switch name.Class {
		default:
			base.FatalfAt(name.Pos(), "unexpected class: %v", name.Class)

		case ir.PEXTERN:
			target.Externs = append(target.Externs, name)

		case ir.PFUNC:
			assert(name.Type().Recv() == nil)

			// TODO(mdempsky): Cleaner way to recognize init?
			if strings.HasPrefix(sym.Name, "init.") {
				target.Inits = append(target.Inits, name.Func)
			}
		}

		if types.IsExported(sym.Name) {
			assert(!sym.OnExportList())
			target.Exports = append(target.Exports, name)
			sym.SetOnExportList(true)
		}

		if base.Flag.AsmHdr != "" {
			assert(!sym.Asm())
			target.Asms = append(target.Asms, name)
			sym.SetAsm(true)
		}
	}

	return nodes
}

// @@@ Inlining

var inlgen = 0

// InlineCall implements inline.NewInline by re-reading the function
// body from its Unified IR export data.
func InlineCall(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
	// TODO(mdempsky): Turn callerfn into an explicit parameter.
	callerfn := ir.CurFunc

	pri, ok := bodyReaderFor(fn)
	if !ok {
		// TODO(mdempsky): Reconsider this diagnostic's wording, if it's
		// to be included in Go 1.20.
		if base.Flag.LowerM != 0 {
			base.WarnfAt(call.Pos(), "cannot inline call to %v: missing inline body", fn)
		}
		return nil
	}

	if fn.Inl.Body == nil {
		expandInline(fn, pri)
	}

	r := pri.asReader(pkgbits.RelocBody, pkgbits.SyncFuncBody)

	// TODO(mdempsky): This still feels clumsy. Can we do better?
	tmpfn := ir.NewFunc(fn.Pos())
	tmpfn.Nname = ir.NewNameAt(fn.Nname.Pos(), callerfn.Sym())
	tmpfn.Closgen = callerfn.Closgen
	defer func() { callerfn.Closgen = tmpfn.Closgen }()

	setType(tmpfn.Nname, fn.Type())
	r.curfn = tmpfn

	r.inlCaller = callerfn
	r.inlCall = call
	r.inlFunc = fn
	r.inlTreeIndex = inlIndex
	r.inlPosBases = make(map[*src.PosBase]*src.PosBase)

	r.closureVars = make([]*ir.Name, len(r.inlFunc.ClosureVars))
	for i, cv := range r.inlFunc.ClosureVars {
		r.closureVars[i] = cv.Outer
	}
	if len(r.closureVars) != 0 && r.hasTypeParams() {
		r.dictParam = r.closureVars[len(r.closureVars)-1] // dictParam is last; see reader.funcLit
	}

	r.funcargs(fn)

	r.delayResults = fn.Inl.CanDelayResults

	r.retlabel = typecheck.AutoLabel(".i")
	inlgen++

	init := ir.TakeInit(call)

	// For normal function calls, the function callee expression
	// may contain side effects. Make sure to preserve these,
	// if necessary (#42703).
	if call.Op() == ir.OCALLFUNC {
		inline.CalleeEffects(&init, call.X)
	}

	var args ir.Nodes
	if call.Op() == ir.OCALLMETH {
		base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
	}
	args.Append(call.Args...)

	// Create assignment to declare and initialize inlvars.
	as2 := ir.NewAssignListStmt(call.Pos(), ir.OAS2, r.inlvars, args)
	as2.Def = true
	var as2init ir.Nodes
	for _, name := range r.inlvars {
		if ir.IsBlank(name) {
			continue
		}
		// TODO(mdempsky): Use inlined position of name.Pos() instead?
		name := name.(*ir.Name)
		as2init.Append(ir.NewDecl(call.Pos(), ir.ODCL, name))
		name.Defn = as2
	}
	as2.SetInit(as2init)
	init.Append(typecheck.Stmt(as2))

	if !r.delayResults {
		// If not delaying retvars, declare and zero initialize the
		// result variables now.
		for _, name := range r.retvars {
			// TODO(mdempsky): Use inlined position of name.Pos() instead?
			name := name.(*ir.Name)
			init.Append(ir.NewDecl(call.Pos(), ir.ODCL, name))
			ras := ir.NewAssignStmt(call.Pos(), name, nil)
			init.Append(typecheck.Stmt(ras))
		}
	}

	// Add an inline mark just before the inlined body.
	// This mark is inline in the code so that it's a reasonable spot
	// to put a breakpoint. Not sure if that's really necessary or not
	// (in which case it could go at the end of the function instead).
	// Note issue 28603.
	init.Append(ir.NewInlineMarkStmt(call.Pos().WithIsStmt(), int64(r.inlTreeIndex)))

	nparams := len(r.curfn.Dcl)

	ir.WithFunc(r.curfn, func() {
		if !r.syntheticBody(call.Pos()) {
			assert(r.Bool()) // have body

			r.curfn.Body = r.stmts()
			r.curfn.Endlineno = r.pos()
		}

		// TODO(mdempsky): This shouldn't be necessary. Inlining might
		// read in new function/method declarations, which could
		// potentially be recursively inlined themselves; but we shouldn't
		// need to read in the non-inlined bodies for the declarations
		// themselves. But currently it's an easy fix to #50552.
		readBodies(typecheck.Target)

		deadcode.Func(r.curfn)

		// Replace any "return" statements within the function body.
		var edit func(ir.Node) ir.Node
		edit = func(n ir.Node) ir.Node {
			if ret, ok := n.(*ir.ReturnStmt); ok {
				n = typecheck.Stmt(r.inlReturn(ret))
			}
			ir.EditChildren(n, edit)
			return n
		}
		edit(r.curfn)
	})

	body := ir.Nodes(r.curfn.Body)

	// Quirkish: We need to eagerly prune variables added during
	// inlining, but removed by deadcode.FuncBody above. Unused
	// variables will get removed during stack frame layout anyway, but
	// len(fn.Dcl) ends up influencing things like autotmp naming.

	used := usedLocals(body)

	for i, name := range r.curfn.Dcl {
		if i < nparams || used.Has(name) {
			name.Curfn = callerfn
			callerfn.Dcl = append(callerfn.Dcl, name)

			// Quirkish. TODO(mdempsky): Document why.
			if name.AutoTemp() {
				name.SetEsc(ir.EscUnknown)

				if base.Flag.GenDwarfInl != 0 {
					name.SetInlLocal(true)
				} else {
					name.SetPos(r.inlCall.Pos())
				}
			}
		}
	}

	body.Append(ir.NewLabelStmt(call.Pos(), r.retlabel))

	res := ir.NewInlinedCallExpr(call.Pos(), body, append([]ir.Node(nil), r.retvars...))
	res.SetInit(init)
	res.SetType(call.Type())
	res.SetTypecheck(1)

	// Inlining shouldn't add any functions to todoBodies.
	assert(len(todoBodies) == 0)

	return res
}

// inlReturn returns a statement that can substitute for the given
// return statement when inlining.
func (r *reader) inlReturn(ret *ir.ReturnStmt) *ir.BlockStmt {
	pos := r.inlCall.Pos()

	block := ir.TakeInit(ret)

	if results := ret.Results; len(results) != 0 {
		assert(len(r.retvars) == len(results))

		as2 := ir.NewAssignListStmt(pos, ir.OAS2, append([]ir.Node(nil), r.retvars...), ret.Results)

		if r.delayResults {
			for _, name := range r.retvars {
				// TODO(mdempsky): Use inlined position of name.Pos() instead?
				name := name.(*ir.Name)
				block.Append(ir.NewDecl(pos, ir.ODCL, name))
				name.Defn = as2
			}
		}

		block.Append(as2)
	}

	block.Append(ir.NewBranchStmt(pos, ir.OGOTO, r.retlabel))
	return ir.NewBlockStmt(pos, block)
}

// expandInline reads in an extra copy of IR to populate
// fn.Inl.{Dcl,Body}.
func expandInline(fn *ir.Func, pri pkgReaderIndex) {
	// TODO(mdempsky): Remove this function. It's currently needed by
	// dwarfgen/dwarf.go:preInliningDcls, which requires fn.Inl.Dcl to
	// create abstract function DIEs. But we should be able to provide it
	// with the same information some other way.

	fndcls := len(fn.Dcl)
	topdcls := len(typecheck.Target.Decls)

	tmpfn := ir.NewFunc(fn.Pos())
	tmpfn.Nname = ir.NewNameAt(fn.Nname.Pos(), fn.Sym())
	tmpfn.ClosureVars = fn.ClosureVars

	{
		r := pri.asReader(pkgbits.RelocBody, pkgbits.SyncFuncBody)
		setType(tmpfn.Nname, fn.Type())

		// Don't change parameter's Sym/Nname fields.
		r.funarghack = true

		r.funcBody(tmpfn)

		ir.WithFunc(tmpfn, func() {
			deadcode.Func(tmpfn)
		})
	}

	used := usedLocals(tmpfn.Body)

	for _, name := range tmpfn.Dcl {
		if name.Class != ir.PAUTO || used.Has(name) {
			name.Curfn = fn
			fn.Inl.Dcl = append(fn.Inl.Dcl, name)
		}
	}
	fn.Inl.Body = tmpfn.Body

	// Double check that we didn't change fn.Dcl by accident.
	assert(fndcls == len(fn.Dcl))

	// typecheck.Stmts may have added function literals to
	// typecheck.Target.Decls. Remove them again so we don't risk trying
	// to compile them multiple times.
	typecheck.Target.Decls = typecheck.Target.Decls[:topdcls]
}

// usedLocals returns a set of local variables that are used within body.
func usedLocals(body []ir.Node) ir.NameSet {
	var used ir.NameSet
	ir.VisitList(body, func(n ir.Node) {
		if n, ok := n.(*ir.Name); ok && n.Op() == ir.ONAME && n.Class == ir.PAUTO {
			used.Add(n)
		}
	})
	return used
}

// @@@ Method wrappers

// needWrapperTypes lists types for which we may need to generate
// method wrappers.
var needWrapperTypes []*types.Type

// haveWrapperTypes lists types for which we know we already have
// method wrappers, because we found the type in an imported package.
var haveWrapperTypes []*types.Type

// needMethodValueWrappers lists methods for which we may need to
// generate method value wrappers.
var needMethodValueWrappers []methodValueWrapper

// haveMethodValueWrappers lists methods for which we know we already
// have method value wrappers, because we found it in an imported
// package.
var haveMethodValueWrappers []methodValueWrapper

type methodValueWrapper struct {
	rcvr   *types.Type
	method *types.Field
}

func (r *reader) needWrapper(typ *types.Type) {
	if typ.IsPtr() {
		return
	}

	// If a type was found in an imported package, then we can assume
	// that package (or one of its transitive dependencies) already
	// generated method wrappers for it.
	if r.importedDef() {
		haveWrapperTypes = append(haveWrapperTypes, typ)
	} else {
		needWrapperTypes = append(needWrapperTypes, typ)
	}
}

// importedDef reports whether r is reading from an imported and
// non-generic element.
//
// If a type was found in an imported package, then we can assume that
// package (or one of its transitive dependencies) already generated
// method wrappers for it.
//
// Exception: If we're instantiating an imported generic type or
// function, we might be instantiating it with type arguments not
// previously seen before.
//
// TODO(mdempsky): Distinguish when a generic function or type was
// instantiated in an imported package so that we can add types to
// haveWrapperTypes instead.
func (r *reader) importedDef() bool {
	return r.p != localPkgReader && !r.hasTypeParams()
}

func MakeWrappers(target *ir.Package) {
	// Only unified IR emits its own wrappers.
	if base.Debug.Unified == 0 {
		return
	}

	// always generate a wrapper for error.Error (#29304)
	needWrapperTypes = append(needWrapperTypes, types.ErrorType)

	seen := make(map[string]*types.Type)

	for _, typ := range haveWrapperTypes {
		wrapType(typ, target, seen, false)
	}
	haveWrapperTypes = nil

	for _, typ := range needWrapperTypes {
		wrapType(typ, target, seen, true)
	}
	needWrapperTypes = nil

	for _, wrapper := range haveMethodValueWrappers {
		wrapMethodValue(wrapper.rcvr, wrapper.method, target, false)
	}
	haveMethodValueWrappers = nil

	for _, wrapper := range needMethodValueWrappers {
		wrapMethodValue(wrapper.rcvr, wrapper.method, target, true)
	}
	needMethodValueWrappers = nil
}

func wrapType(typ *types.Type, target *ir.Package, seen map[string]*types.Type, needed bool) {
	key := typ.LinkString()
	if prev := seen[key]; prev != nil {
		if !types.Identical(typ, prev) {
			base.Fatalf("collision: types %v and %v have link string %q", typ, prev, key)
		}
		return
	}
	seen[key] = typ

	if !needed {
		// Only called to add to 'seen'.
		return
	}

	if !typ.IsInterface() {
		typecheck.CalcMethods(typ)
	}
	for _, meth := range typ.AllMethods().Slice() {
		if meth.Sym.IsBlank() || !meth.IsMethod() {
			base.FatalfAt(meth.Pos, "invalid method: %v", meth)
		}

		methodWrapper(0, typ, meth, target)

		// For non-interface types, we also want *T wrappers.
		if !typ.IsInterface() {
			methodWrapper(1, typ, meth, target)

			// For not-in-heap types, *T is a scalar, not pointer shaped,
			// so the interface wrappers use **T.
			if typ.NotInHeap() {
				methodWrapper(2, typ, meth, target)
			}
		}
	}
}

func methodWrapper(derefs int, tbase *types.Type, method *types.Field, target *ir.Package) {
	wrapper := tbase
	for i := 0; i < derefs; i++ {
		wrapper = types.NewPtr(wrapper)
	}

	sym := ir.MethodSym(wrapper, method.Sym)
	base.Assertf(!sym.Siggen(), "already generated wrapper %v", sym)
	sym.SetSiggen(true)

	wrappee := method.Type.Recv().Type
	if types.Identical(wrapper, wrappee) ||
		!types.IsMethodApplicable(wrapper, method) ||
		!reflectdata.NeedEmit(tbase) {
		return
	}

	// TODO(mdempsky): Use method.Pos instead?
	pos := base.AutogeneratedPos

	fn := newWrapperFunc(pos, sym, wrapper, method)

	var recv ir.Node = fn.Nname.Type().Recv().Nname.(*ir.Name)

	// For simple *T wrappers around T methods, panicwrap produces a
	// nicer panic message.
	if wrapper.IsPtr() && types.Identical(wrapper.Elem(), wrappee) {
		cond := ir.NewBinaryExpr(pos, ir.OEQ, recv, types.BuiltinPkg.Lookup("nil").Def.(ir.Node))
		then := []ir.Node{ir.NewCallExpr(pos, ir.OCALL, typecheck.LookupRuntime("panicwrap"), nil)}
		fn.Body.Append(ir.NewIfStmt(pos, cond, then, nil))
	}

	// typecheck will add one implicit deref, if necessary,
	// but not-in-heap types require more for their **T wrappers.
	for i := 1; i < derefs; i++ {
		recv = Implicit(ir.NewStarExpr(pos, recv))
	}

	addTailCall(pos, fn, recv, method)

	finishWrapperFunc(fn, target)
}

func wrapMethodValue(recvType *types.Type, method *types.Field, target *ir.Package, needed bool) {
	sym := ir.MethodSymSuffix(recvType, method.Sym, "-fm")
	if sym.Uniq() {
		return
	}
	sym.SetUniq(true)

	// TODO(mdempsky): Use method.Pos instead?
	pos := base.AutogeneratedPos

	fn := newWrapperFunc(pos, sym, nil, method)
	sym.Def = fn.Nname

	// Declare and initialize variable holding receiver.
	recv := ir.NewHiddenParam(pos, fn, typecheck.Lookup(".this"), recvType)

	if !needed {
		typecheck.Func(fn)
		return
	}

	addTailCall(pos, fn, recv, method)

	finishWrapperFunc(fn, target)
}

func newWrapperFunc(pos src.XPos, sym *types.Sym, wrapper *types.Type, method *types.Field) *ir.Func {
	fn := ir.NewFunc(pos)
	fn.SetDupok(true) // TODO(mdempsky): Leave unset for local, non-generic wrappers?

	name := ir.NewNameAt(pos, sym)
	ir.MarkFunc(name)
	name.Func = fn
	name.Defn = fn
	fn.Nname = name

	sig := newWrapperType(wrapper, method)
	setType(name, sig)

	// TODO(mdempsky): De-duplicate with similar logic in funcargs.
	defParams := func(class ir.Class, params *types.Type) {
		for _, param := range params.FieldSlice() {
			name := ir.NewNameAt(param.Pos, param.Sym)
			name.Class = class
			setType(name, param.Type)

			name.Curfn = fn
			fn.Dcl = append(fn.Dcl, name)

			param.Nname = name
		}
	}

	defParams(ir.PPARAM, sig.Recvs())
	defParams(ir.PPARAM, sig.Params())
	defParams(ir.PPARAMOUT, sig.Results())

	return fn
}

func finishWrapperFunc(fn *ir.Func, target *ir.Package) {
	typecheck.Func(fn)

	ir.WithFunc(fn, func() {
		typecheck.Stmts(fn.Body)
	})

	// We generate wrappers after the global inlining pass,
	// so we're responsible for applying inlining ourselves here.
	inline.InlineCalls(fn)

	// The body of wrapper function after inlining may reveal new ir.OMETHVALUE node,
	// we don't know whether wrapper function has been generated for it or not, so
	// generate one immediately here.
	ir.VisitList(fn.Body, func(n ir.Node) {
		if n, ok := n.(*ir.SelectorExpr); ok && n.Op() == ir.OMETHVALUE {
			wrapMethodValue(n.X.Type(), n.Selection, target, true)
		}
	})

	target.Decls = append(target.Decls, fn)
}

// newWrapperType returns a copy of the given signature type, but with
// the receiver parameter type substituted with recvType.
// If recvType is nil, newWrapperType returns a signature
// without a receiver parameter.
func newWrapperType(recvType *types.Type, method *types.Field) *types.Type {
	clone := func(params []*types.Field) []*types.Field {
		res := make([]*types.Field, len(params))
		for i, param := range params {
			sym := param.Sym
			if sym == nil || sym.Name == "_" {
				sym = typecheck.LookupNum(".anon", i)
			}
			res[i] = types.NewField(param.Pos, sym, param.Type)
			res[i].SetIsDDD(param.IsDDD())
		}
		return res
	}

	sig := method.Type

	var recv *types.Field
	if recvType != nil {
		recv = types.NewField(sig.Recv().Pos, typecheck.Lookup(".this"), recvType)
	}
	params := clone(sig.Params().FieldSlice())
	results := clone(sig.Results().FieldSlice())

	return types.NewSignature(types.NoPkg, recv, nil, params, results)
}

func addTailCall(pos src.XPos, fn *ir.Func, recv ir.Node, method *types.Field) {
	sig := fn.Nname.Type()
	args := make([]ir.Node, sig.NumParams())
	for i, param := range sig.Params().FieldSlice() {
		args[i] = param.Nname.(*ir.Name)
	}

	// TODO(mdempsky): Support creating OTAILCALL, when possible. See reflectdata.methodWrapper.
	// Not urgent though, because tail calls are currently incompatible with regabi anyway.

	fn.SetWrapper(true) // TODO(mdempsky): Leave unset for tail calls?

	dot := ir.NewSelectorExpr(pos, ir.OXDOT, recv, method.Sym)
	call := typecheck.Call(pos, dot, args, method.Type.IsVariadic()).(*ir.CallExpr)

	if method.Type.NumResults() == 0 {
		fn.Body.Append(call)
		return
	}

	ret := ir.NewReturnStmt(pos, nil)
	ret.Results = []ir.Node{call}
	fn.Body.Append(ret)
}

func setBasePos(pos src.XPos) {
	// Set the position for any error messages we might print (e.g. too large types).
	base.Pos = pos
}

// dictParamName is the name of the synthetic dictionary parameter
// added to shaped functions.
//
// N.B., this variable name is known to Delve:
// https://github.com/go-delve/delve/blob/cb91509630529e6055be845688fd21eb89ae8714/pkg/proc/eval.go#L28
const dictParamName = ".dict"

// shapeSig returns a copy of fn's signature, except adding a
// dictionary parameter and promoting the receiver parameter (if any)
// to a normal parameter.
//
// The parameter types.Fields are all copied too, so their Nname
// fields can be initialized for use by the shape function.
func shapeSig(fn *ir.Func, dict *readerDict) *types.Type {
	sig := fn.Nname.Type()
	oldRecv := sig.Recv()

	var recv *types.Field
	if oldRecv != nil {
		recv = types.NewField(oldRecv.Pos, oldRecv.Sym, oldRecv.Type)
	}

	params := make([]*types.Field, 1+sig.Params().Fields().Len())
	params[0] = types.NewField(fn.Pos(), fn.Sym().Pkg.Lookup(dictParamName), types.NewPtr(dict.varType()))
	for i, param := range sig.Params().Fields().Slice() {
		d := types.NewField(param.Pos, param.Sym, param.Type)
		d.SetIsDDD(param.IsDDD())
		params[1+i] = d
	}

	results := make([]*types.Field, sig.Results().Fields().Len())
	for i, result := range sig.Results().Fields().Slice() {
		results[i] = types.NewField(result.Pos, result.Sym, result.Type)
	}

	return types.NewSignature(types.LocalPkg, recv, nil, params, results)
}