1 files changed, 188 insertions, 2 deletions
diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index d2fe575ffd..3a496816cc 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -16,6 +16,7 @@ import (
 	"cmd/compile/internal/deadcode"
 	"cmd/compile/internal/dwarfgen"
 	"cmd/compile/internal/ir"
+	"cmd/compile/internal/reflectdata"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
@@ -419,7 +420,7 @@ func (r *reader) interfaceType() *types.Type {
 	if len(fields) == 0 {
 		return types.Types[types.TINTER] // empty interface
 	}
-	return types.NewInterface(tpkg, fields)
+	return r.needWrapper(types.NewInterface(tpkg, fields))
 }
 
 func (r *reader) structType() *types.Type {
@@ -440,7 +441,7 @@ func (r *reader) structType() *types.Type {
 		}
 		fields[i] = f
 	}
-	return types.NewStruct(tpkg, fields)
+	return r.needWrapper(types.NewStruct(tpkg, fields))
 }
 
 func (r *reader) signature(tpkg *types.Pkg, recv *types.Field) *types.Type {
@@ -597,6 +598,10 @@ func (pr *pkgReader) objIdx(idx int, implicits, explicits []*types.Type) ir.Node
 			typ.Methods().Set(methods)
 		}
 
+		if !typ.IsPtr() {
+			r.needWrapper(typ)
+		}
+
 		return name
 
 	case objVar:
@@ -2015,3 +2020,184 @@ func usedLocals(body []ir.Node) ir.NameSet {
 	})
 	return used
 }
+
+// @@@ Method wrappers
+
+// needWrapperTypes lists types for which we may need to generate
+// method wrappers.
+var needWrapperTypes []*types.Type
+
+func (r *reader) needWrapper(typ *types.Type) *types.Type {
+	// TODO(mdempsky): Be more judicious about generating wrappers.
+	// For now, generating all possible wrappers is simple and correct,
+	// but potentially wastes a lot of time/space.
+
+	if typ.IsPtr() {
+		base.Fatalf("bad pointer type: %v", typ)
+	}
+
+	needWrapperTypes = append(needWrapperTypes, typ)
+	return typ
+}
+
+func (r *reader) wrapTypes(target *ir.Package) {
+	// always generate a wrapper for error.Error (#29304)
+	r.needWrapper(types.ErrorType)
+
+	seen := make(map[string]*types.Type)
+	for _, typ := range needWrapperTypes {
+		if typ.Sym() == nil {
+			key := typ.ShortString()
+			if prev := seen[key]; prev != nil {
+				if !types.Identical(typ, prev) {
+					base.Fatalf("collision: types %v and %v have short string %q", typ, prev, key)
+				}
+				continue
+			}
+			seen[key] = typ
+		}
+
+		r.wrapType(typ, target)
+	}
+
+	needWrapperTypes = nil
+}
+
+func (r *reader) wrapType(typ *types.Type, target *ir.Package) {
+	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)
+		}
+
+		r.methodWrapper(0, typ, meth, target)
+
+		// For non-interface types, we also want *T wrappers.
+		if !typ.IsInterface() {
+			r.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() {
+				r.methodWrapper(2, typ, meth, target)
+			}
+		}
+	}
+}
+
+func (r *reader) 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)
+	assert(!sym.Siggen())
+	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 := ir.NewFunc(pos)
+	fn.SetDupok(true)   // TODO(mdempsky): Leave unset for local, non-generic wrappers?
+	fn.SetWrapper(true) // TODO(mdempsky): Leave unset for tail calls?
+
+	fn.Nname = ir.NewNameAt(pos, sym)
+	ir.MarkFunc(fn.Nname)
+	fn.Nname.Func = fn
+	fn.Nname.Defn = fn
+
+	sig := newWrapperType(wrapper, method.Type)
+	r.setType(fn.Nname, sig)
+
+	// TODO(mdempsky): De-duplicate with similar logic in funcargs.
+	defParams := func(class ir.Class, params ...*types.Field) {
+		for _, param := range params {
+			name := ir.NewNameAt(param.Pos, param.Sym)
+			name.Class = class
+			r.setType(name, param.Type)
+
+			name.Curfn = fn
+			fn.Dcl = append(fn.Dcl, name)
+
+			param.Nname = name
+		}
+	}
+
+	defParams(ir.PPARAM, sig.Recv())
+	defParams(ir.PPARAM, sig.Params().FieldSlice()...)
+	defParams(ir.PPARAMOUT, sig.Results().FieldSlice()...)
+
+	var recv ir.Node = sig.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))
+	}
+
+	// Add implicit derefs, as necessary. typecheck will add one deref,
+	// but not-in-heap types will need another for their **T wrappers.
+	for i := 0; i < derefs; i++ {
+		recv = Implicit(ir.NewStarExpr(pos, recv))
+	}
+
+	args := make([]ir.Node, sig.NumParams())
+	for i, param := range sig.Params().FieldSlice() {
+		args[i] = param.Nname.(*ir.Name)
+	}
+
+	fn.Body.Append(newTailCall(pos, method, recv, args))
+
+	target.Decls = append(target.Decls, fn)
+}
+
+// newWrapperType returns a copy of the given signature type, but with
+// the receiver parameter type substituted with wrapper.
+func newWrapperType(wrapper, sig *types.Type) *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
+	}
+
+	recv := types.NewField(sig.Recv().Pos, typecheck.Lookup(".this"), wrapper)
+	params := clone(sig.Params().FieldSlice())
+	results := clone(sig.Results().FieldSlice())
+
+	return types.NewSignature(types.NoPkg, recv, nil, params, results)
+}
+
+func newTailCall(pos src.XPos, method *types.Field, recv ir.Node, args []ir.Node) ir.Node {
+	// TODO(mdempsky): Support creating OTAILCALL, when possible. See reflectdata.methodWrapper.
+	// Not urgent though, because tail calls are currently incompatible with regabi anyway.
+
+	call := ir.NewCallExpr(pos, ir.OCALL, ir.NewSelectorExpr(pos, ir.OXDOT, recv, method.Sym), args)
+	call.IsDDD = method.Type.IsVariadic()
+
+	if method.Type.NumResults() == 0 {
+		return call
+	}
+
+	ret := ir.NewReturnStmt(pos, nil)
+	ret.Results = []ir.Node{call}
+	return ret
+}