cmd/gc: implement method values

R=ken2, ken
CC=golang-dev
https://golang.org/cl/7546052

src/cmd/5g/gsubr.c

@@ -543,6 +543,7 @@ ismem(Node *n)
 	case OINDREG:
 	case ONAME:
 	case OPARAM:
+	case OCLOSUREVAR:
 		return 1;
 	}
 	return 0;
@@ -1163,11 +1164,11 @@ gregshift(int as, Node *lhs, int32 stype, Node *reg, Node *rhs)
 // Generate an instruction referencing *n
 // to force segv on nil pointer dereference.
 void
-checkref(Node *n)
+checkref(Node *n, int force)
 {
 	Node m1, m2;
 
-	if(n->type->type->width < unmappedzero)
+	if(!force && isptr[n->type->etype] && n->type->type->width < unmappedzero)
 		return;
 
 	regalloc(&m1, types[TUINTPTR], n);
@@ -1209,8 +1210,6 @@ checkoffset(Addr *a, int canemitcode)
 void
 naddr(Node *n, Addr *a, int canemitcode)
 {
-	Prog *p;
-
 	a->type = D_NONE;
 	a->name = D_NONE;
 	a->reg = NREG;
@@ -1283,16 +1282,9 @@ naddr(Node *n, Addr *a, int canemitcode)
 		break;
 	
 	case OCLOSUREVAR:
-		if(!canemitcode)
-			fatal("naddr OCLOSUREVAR cannot emit code");
-		p = gins(AMOVW, N, N);
-		p->from.type = D_OREG;
-		p->from.reg = 7;
-		p->from.offset = n->xoffset;
-		p->to.type = D_REG;
-		p->to.reg = 1;
-		a->type = D_REG;
-		a->reg = 1;
+		a->type = D_OREG;
+		a->reg = 7;
+		a->offset = n->xoffset;
 		a->sym = S;
 		break;		
 

src/cmd/6g/gsubr.c

@@ -555,6 +555,7 @@ ismem(Node *n)
 	case OINDREG:
 	case ONAME:
 	case OPARAM:
+	case OCLOSUREVAR:
 		return 1;
 	case OADDR:
 		if(flag_largemodel)
@@ -1057,11 +1058,11 @@ gins(int as, Node *f, Node *t)
 // Generate an instruction referencing *n
 // to force segv on nil pointer dereference.
 void
-checkref(Node *n)
+checkref(Node *n, int force)
 {
 	Node m;
 
-	if(n->type->type->width < unmappedzero)
+	if(!force && isptr[n->type->etype] && n->type->type->width < unmappedzero)
 		return;
 
 	regalloc(&m, types[TUINTPTR], n);
@@ -1098,8 +1099,6 @@ checkoffset(Addr *a, int canemitcode)
 void
 naddr(Node *n, Addr *a, int canemitcode)
 {
-	Prog *p;
-
 	a->scale = 0;
 	a->index = D_NONE;
 	a->type = D_NONE;
@@ -1163,14 +1162,9 @@ naddr(Node *n, Addr *a, int canemitcode)
 		break;
 	
 	case OCLOSUREVAR:
-		if(!canemitcode)
-			fatal("naddr OCLOSUREVAR cannot emit code");
-		p = gins(AMOVQ, N, N);
-		p->from.type = D_DX+D_INDIR;
-		p->from.offset = n->xoffset;
-		p->to.type = D_BX;
-		a->type = D_BX;
+		a->type = D_DX+D_INDIR;
 		a->sym = S;
+		a->offset = n->xoffset;
 		break;
 	
 	case OCFUNC:

src/cmd/8g/gsubr.c

@@ -1150,6 +1150,7 @@ ismem(Node *n)
 	case OINDREG:
 	case ONAME:
 	case OPARAM:
+	case OCLOSUREVAR:
 		return 1;
 	}
 	return 0;
@@ -2160,11 +2161,11 @@ gins(int as, Node *f, Node *t)
 // Generate an instruction referencing *n
 // to force segv on nil pointer dereference.
 void
-checkref(Node *n)
+checkref(Node *n, int force)
 {
 	Node m;
 
-	if(n->type->type->width < unmappedzero)
+	if(!force && isptr[n->type->etype] && n->type->type->width < unmappedzero)
 		return;
 
 	regalloc(&m, types[TUINTPTR], n);
@@ -2201,8 +2202,6 @@ checkoffset(Addr *a, int canemitcode)
 void
 naddr(Node *n, Addr *a, int canemitcode)
 {
-	Prog *p;
-
 	a->scale = 0;
 	a->index = D_NONE;
 	a->type = D_NONE;
@@ -2239,13 +2238,8 @@ naddr(Node *n, Addr *a, int canemitcode)
 		break;
 
 	case OCLOSUREVAR:
-		if(!canemitcode)
-			fatal("naddr OCLOSUREVAR cannot emit code");
-		p = gins(AMOVL, N, N);
-		p->from.type = D_DX+D_INDIR;
-		p->from.offset = n->xoffset;
-		p->to.type = D_BX;
-		a->type = D_BX;
+		a->type = D_DX+D_INDIR;
+		a->offset = n->xoffset;
 		a->sym = S;
 		break;
 

src/cmd/gc/closure.c

@@ -255,26 +255,166 @@ walkclosure(Node *func, NodeList **init)
 	return clos;
 }
 
-// Special case for closures that get called in place.
-// Optimize runtime.closure(X, __func__xxxx_, .... ) away
-// to __func__xxxx_(Y ....).
-// On entry, expect n->op == OCALL, n->left->op == OCLOSURE.
+static Node *makepartialcall(Node*, Type*, Node*);
+
 void
-walkcallclosure(Node *n, NodeList **init)
+typecheckpartialcall(Node *fn, Node *sym)
+{
+	switch(fn->op) {
+	case ODOTINTER:
+	case ODOTMETH:
+		break;
+	default:
+		fatal("invalid typecheckpartialcall");
+	}
+
+	// Create top-level function.
+	fn->nname = makepartialcall(fn, fn->type, sym);
+	fn->op = OCALLPART;
+	fn->type = fn->right->type;
+}
+
+static Node*
+makepartialcall(Node *fn, Type *t0, Node *meth)
 {
-	USED(init);
-	if (n->op != OCALLFUNC || n->left->op != OCLOSURE) {
-		dump("walkcallclosure", n);
-		fatal("abuse of walkcallclosure");
+	Node *ptr, *n, *call, *xtype, *xfunc, *cv;
+	Type *rcvrtype, *basetype, *t;
+	NodeList *body, *l, *callargs, *retargs;
+	char *p;
+	Sym *sym;
+	int i;
+
+	// TODO: names are not right
+	rcvrtype = fn->left->type;
+	if(exportname(meth->sym->name))
+		p = smprint("%-hT.%s·fm", rcvrtype, meth->sym->name);
+	else
+		p = smprint("%-hT.(%-S)·fm", rcvrtype, meth->sym);
+	basetype = rcvrtype;
+	if(isptr[rcvrtype->etype])
+		basetype = basetype->type;
+	if(basetype->sym == S)
+		fatal("missing base type for %T", rcvrtype);
+
+	sym = pkglookup(p, basetype->sym->pkg);
+	free(p);
+	if(sym->flags & SymUniq)
+		return sym->def;
+	sym->flags |= SymUniq;
+
+	xtype = nod(OTFUNC, N, N);
+	i = 0;
+	l = nil;
+	callargs = nil;
+	xfunc = nod(ODCLFUNC, N, N);
+	for(t = getinargx(t0)->type; t; t = t->down) {
+		snprint(namebuf, sizeof namebuf, "a%d", i++);
+		n = newname(lookup(namebuf));
+		n->class = PPARAM;
+		xfunc->dcl = list(xfunc->dcl, n);
+		callargs = list(callargs, n);
+		l = list(l, nod(ODCLFIELD, n, typenod(t->type)));
 	}
+	xtype->list = l;
+	i = 0;
+	l = nil;
+	retargs = nil;
+	for(t = getoutargx(t0)->type; t; t = t->down) {
+		snprint(namebuf, sizeof namebuf, "r%d", i++);
+		n = newname(lookup(namebuf));
+		n->class = PPARAMOUT;
+		xfunc->dcl = list(xfunc->dcl, n);
+		retargs = list(retargs, n);
+		l = list(l, nod(ODCLFIELD, n, typenod(t->type)));
+	}
+	xtype->rlist = l;
 
-	// New arg list for n. First the closure-args
-	// and then the original parameter list.
-	n->list = concat(n->left->enter, n->list);
-	n->left = n->left->closure->nname;
-	dowidth(n->left->type);
-	n->type = getoutargx(n->left->type);
-	// for a single valued function, pull the field type out of the struct
-	if (n->type && n->type->type && !n->type->type->down)
-		n->type = n->type->type->type;
+	xfunc->dupok = 1;
+	xfunc->nname = newname(sym);
+	xfunc->nname->sym->flags |= SymExported; // disable export
+	xfunc->nname->ntype = xtype;
+	xfunc->nname->defn = xfunc;
+	declare(xfunc->nname, PFUNC);
+	
+	// Declare and initialize variable holding receiver.
+	body = nil;
+	cv = nod(OCLOSUREVAR, N, N);
+	cv->xoffset = widthptr;
+	cv->type = rcvrtype;
+	ptr = nod(ONAME, N, N);
+	ptr->sym = lookup("rcvr");
+	ptr->class = PAUTO;
+	ptr->addable = 1;
+	ptr->ullman = 1;
+	ptr->used = 1;
+	ptr->curfn = xfunc;
+	xfunc->dcl = list(xfunc->dcl, ptr);
+	if(isptr[rcvrtype->etype] || isinter(rcvrtype)) {
+		ptr->ntype = typenod(rcvrtype);
+		body = list(body, nod(OAS, ptr, cv));
+	} else {
+		ptr->ntype = typenod(ptrto(rcvrtype));
+		body = list(body, nod(OAS, ptr, nod(OADDR, cv, N)));
+	}
+
+	call = nod(OCALL, nod(OXDOT, ptr, meth), N);
+	call->list = callargs;
+	if(t0->outtuple == 0) {
+		body = list(body, call);
+	} else {
+		n = nod(OAS2, N, N);
+		n->list = retargs;
+		n->rlist = list1(call);
+		body = list(body, n);
+		n = nod(ORETURN, N, N);
+		body = list(body, n);
+	}
+
+	xfunc->nbody = body;
+
+	typecheck(&xfunc, Etop);
+	sym->def = xfunc;
+	xtop = list(xtop, xfunc);
+
+	return xfunc;
+}
+
+Node*
+walkpartialcall(Node *n, NodeList **init)
+{
+	Node *clos, *typ;
+
+	// Create closure in the form of a composite literal.
+	// For x.M with receiver (x) type T, the generated code looks like:
+	//
+	//	clos = &struct{F uintptr; R T}{M.T·f, x}
+	//
+	// Like walkclosure above.
+	
+	if(isinter(n->left->type)) {
+		n->left = cheapexpr(n->left, init);
+		checknotnil(n->left, init);
+	}
+
+	typ = nod(OTSTRUCT, N, N);
+	typ->list = list1(nod(ODCLFIELD, newname(lookup("F")), typenod(types[TUINTPTR])));
+	typ->list = list(typ->list, nod(ODCLFIELD, newname(lookup("R")), typenod(n->left->type)));
+
+	clos = nod(OCOMPLIT, N, nod(OIND, typ, N));
+	clos->esc = n->esc;
+	clos->right->implicit = 1;
+	clos->list = list1(nod(OCFUNC, n->nname->nname, N));
+	clos->list = list(clos->list, n->left);
+
+	// Force type conversion from *struct to the func type.
+	clos = nod(OCONVNOP, clos, N);
+	clos->type = n->type;
+
+	typecheck(&clos, Erv);
+	// typecheck will insert a PTRLIT node under CONVNOP,
+	// tag it with escape analysis result.
+	clos->left->esc = n->esc;
+	walkexpr(&clos, init);
+
+	return clos;
 }

src/cmd/gc/gen.c

@@ -491,6 +491,9 @@ gen(Node *n)
 	case ORETURN:
 		cgen_ret(n);
 		break;
+	
+	case OCHECKNOTNIL:
+		checkref(n->left, 1);
 	}
 
 ret:
@@ -807,7 +810,7 @@ cgen_slice(Node *n, Node *res)
 	if(n->op == OSLICEARR) {
 		if(!isptr[n->left->type->etype])
 			fatal("slicearr is supposed to work on pointer: %+N\n", n);
-		checkref(n->left);
+		checkref(n->left, 0);
 	}
 
 	if(isnil(n->left)) {

src/cmd/gc/go.h

@@ -452,6 +452,7 @@ enum
 	OCALLFUNC,	// f()
 	OCALLMETH,	// t.Method()
 	OCALLINTER,	// err.Error()
+	OCALLPART,	// t.Method (without ())
 	OCAP,	// cap
 	OCLOSE,	// close
 	OCLOSURE,	// f = func() { etc }
@@ -564,6 +565,7 @@ enum
 	OITAB,	// itable word of an interface value.
 	OCLOSUREVAR, // variable reference at beginning of closure function
 	OCFUNC,	// reference to c function pointer (not go func value)
+	OCHECKNOTNIL, // emit code to ensure pointer/interface not nil
 
 	// arch-specific registers
 	OREGISTER,	// a register, such as AX.
@@ -989,7 +991,8 @@ Node*	closurebody(NodeList *body);
 void	closurehdr(Node *ntype);
 void	typecheckclosure(Node *func, int top);
 Node*	walkclosure(Node *func, NodeList **init);
-void	walkcallclosure(Node *n, NodeList **init);
+void	typecheckpartialcall(Node*, Node*);
+Node*	walkpartialcall(Node*, NodeList**);
 
 /*
  *	const.c
@@ -1419,7 +1422,8 @@ EXTERN	Node*	nodfp;
 int	anyregalloc(void);
 void	betypeinit(void);
 void	bgen(Node *n, int true, int likely, Prog *to);
-void	checkref(Node*);
+void	checkref(Node *n, int force);
+void	checknotnil(Node*, NodeList**);
 void	cgen(Node*, Node*);
 void	cgen_asop(Node *n);
 void	cgen_call(Node *n, int proc);

src/cmd/gc/inl.c

@@ -357,7 +357,7 @@ inlnode(Node **np)
 		}
 
 	case OCLOSURE:
-		// TODO do them here (or earlier) instead of in walkcallclosure,
+		// TODO do them here (or earlier),
 		// so escape analysis can avoid more heapmoves.
 		return;
 	}

src/cmd/gc/subr.c

@@ -3723,3 +3723,17 @@ isbadimport(Strlit *path)
 	}
 	return 0;
 }
+
+void
+checknotnil(Node *x, NodeList **init)
+{
+	Node *n;
+	
+	if(isinter(x->type)) {
+		x = nod(OITAB, x, N);
+		typecheck(&x, Erv);
+	}
+	n = nod(OCHECKNOTNIL, x, N);
+	n->typecheck = 1;
+	*init = list(*init, n);
+}

src/cmd/gc/typecheck.c

@@ -732,6 +732,7 @@ reswitch:
 			yyerror("rhs of . must be a name");	// impossible
 			goto error;
 		}
+		r = n->right;
 
 		if(n->left->op == OTYPE) {
 			if(!looktypedot(n, t, 0)) {
@@ -775,7 +776,12 @@ reswitch:
 		switch(n->op) {
 		case ODOTINTER:
 		case ODOTMETH:
-			ok |= Ecall;
+			if(top&Ecall)
+				ok |= Ecall;
+			else {
+				typecheckpartialcall(n, r);
+				ok |= Erv;
+			}
 			break;
 		default:
 			ok |= Erv;
@@ -1694,10 +1700,6 @@ ret:
 		yyerror("%N is not a type", n);
 		goto error;
 	}
-	if((ok & Ecall) && !(top & Ecall)) {
-		yyerror("method %N is not an expression, must be called", n);
-		goto error;
-	}
 	// TODO(rsc): simplify
 	if((top & (Ecall|Erv|Etype)) && !(top & Etop) && !(ok & (Erv|Etype|Ecall))) {
 		yyerror("%N used as value", n);
@@ -2560,6 +2562,7 @@ islvalue(Node *n)
 		// fall through
 	case OIND:
 	case ODOTPTR:
+	case OCLOSUREVAR:
 		return 1;
 	case ODOT:
 		return islvalue(n->left);

src/cmd/gc/walk.c

@@ -184,6 +184,7 @@ walkstmt(Node **np)
 	case OLABEL:
 	case ODCLCONST:
 	case ODCLTYPE:
+	case OCHECKNOTNIL:
 		break;
 
 	case OBLOCK:
@@ -396,13 +397,28 @@ walkexpr(Node **np, NodeList **init)
 	case OIMAG:
 	case ODOTMETH:
 	case ODOTINTER:
+		walkexpr(&n->left, init);
+		goto ret;
+
 	case OIND:
+		if(n->left->type->type->width == 0) {
+			n->left = cheapexpr(n->left, init);
+			checknotnil(n->left, init);
+		}
 		walkexpr(&n->left, init);
 		goto ret;
 
 	case ODOT:
+		usefield(n);
+		walkexpr(&n->left, init);
+		goto ret;
+
 	case ODOTPTR:
 		usefield(n);
+		if(n->op == ODOTPTR && n->left->type->type->width == 0) {
+			n->left = cheapexpr(n->left, init);
+			checknotnil(n->left, init);
+		}
 		walkexpr(&n->left, init);
 		goto ret;
 
@@ -524,13 +540,6 @@ walkexpr(Node **np, NodeList **init)
 		if(n->list && n->list->n->op == OAS)
 			goto ret;
 
-		/*
-		if(n->left->op == OCLOSURE) {
-			walkcallclosure(n, init);
-			t = n->left->type;
-		}
-		*/
-
 		walkexpr(&n->left, init);
 		walkexprlist(n->list, init);
 
@@ -1321,6 +1330,10 @@ walkexpr(Node **np, NodeList **init)
 	case OCLOSURE:
 		n = walkclosure(n, init);
 		goto ret;
+	
+	case OCALLPART:
+		n = walkpartialcall(n, init);
+		goto ret;
 	}
 	fatal("missing switch %O", n->op);
 

test/method5.go

+// run
+
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// Concrete types implementing M method.
+// Smaller than a word, word-sized, larger than a word.
+// Value and pointer receivers.
+
+type Tinter interface {
+	M(int, byte) (byte, int)
+}
+
+type Tsmallv byte
+
+func (v Tsmallv) M(x int, b byte) (byte, int) { return b, x+int(v) }
+
+type Tsmallp byte
+
+func (p *Tsmallp) M(x int, b byte) (byte, int) { return b, x+int(*p) }
+
+type Twordv uintptr
+
+func (v Twordv) M(x int, b byte) (byte, int) { return b, x+int(v) }
+
+type Twordp uintptr
+
+func (p *Twordp) M(x int, b byte) (byte, int) { return b, x+int(*p) }
+
+type Tbigv [2]uintptr
+
+func (v Tbigv) M(x int, b byte) (byte, int) { return b, x+int(v[0])+int(v[1]) }
+
+type Tbigp [2]uintptr
+
+func (p *Tbigp) M(x int, b byte) (byte, int) { return b, x+int(p[0])+int(p[1]) }
+
+// Again, with an unexported method.
+
+type tsmallv byte
+
+func (v tsmallv) m(x int, b byte) (byte, int) { return b, x+int(v) }
+
+type tsmallp byte
+
+func (p *tsmallp) m(x int, b byte) (byte, int) { return b, x+int(*p) }
+
+type twordv uintptr
+
+func (v twordv) m(x int, b byte) (byte, int) { return b, x+int(v) }
+
+type twordp uintptr
+
+func (p *twordp) m(x int, b byte) (byte, int) { return b, x+int(*p) }
+
+type tbigv [2]uintptr
+
+func (v tbigv) m(x int, b byte) (byte, int) { return b, x+int(v[0])+int(v[1]) }
+
+type tbigp [2]uintptr
+
+func (p *tbigp) m(x int, b byte) (byte, int) { return b, x+int(p[0])+int(p[1]) }
+
+type tinter interface {
+	m(int, byte) (byte, int)
+}
+
+// Embedding via pointer.
+
+type T1 struct {
+	T2
+}
+
+type T2 struct {
+	*T3
+}
+
+type T3 struct {
+	*T4
+}
+
+type T4 struct {
+}
+
+func (t4 T4) M(x int, b byte) (byte, int) { return b, x+40 }
+
+var failed = false
+
+func CheckI(name string, i Tinter, inc int) {
+	b, x := i.M(1000, 99)
+	if b != 99 || x != 1000+inc {
+		failed = true
+		print(name, ".M(1000, 99) = ", b, ", ", x, " want 99, ", 1000+inc, "\n")
+	}
+	
+	CheckF("(i="+name+")", i.M, inc)
+}
+
+func CheckF(name string, f func(int, byte) (byte, int), inc int) {
+	b, x := f(1000, 99)
+	if b != 99 || x != 1000+inc {
+		failed = true
+		print(name, "(1000, 99) = ", b, ", ", x, " want 99, ", 1000+inc, "\n")
+	}
+}
+
+func checkI(name string, i tinter, inc int) {
+	b, x := i.m(1000, 99)
+	if b != 99 || x != 1000+inc {
+		failed = true
+		print(name, ".m(1000, 99) = ", b, ", ", x, " want 99, ", 1000+inc, "\n")
+	}
+	
+	checkF("(i="+name+")", i.m, inc)
+}
+
+func checkF(name string, f func(int, byte) (byte, int), inc int) {
+	b, x := f(1000, 99)
+	if b != 99 || x != 1000+inc {
+		failed = true
+		print(name, "(1000, 99) = ", b, ", ", x, " want 99, ", 1000+inc, "\n")
+	}
+}
+
+func shouldPanic(f func()) {
+	defer func() {
+		if recover() == nil {
+			panic("not panicking")
+		}
+	}()
+	f()
+}
+
+func shouldNotPanic(f func()) {
+	f()
+}
+
+func main() {
+	sv := Tsmallv(1)
+	CheckI("sv", sv, 1)
+	CheckF("sv.M", sv.M, 1)
+	CheckF("(&sv).M", (&sv).M, 1)
+	psv := &sv
+	CheckI("psv", psv, 1)
+	CheckF("psv.M", psv.M, 1)
+	CheckF("(*psv).M", (*psv).M, 1)
+
+	sp := Tsmallp(2)
+	CheckI("&sp", &sp, 2)
+	CheckF("sp.M", sp.M, 2)
+	CheckF("(&sp).M", (&sp).M, 2)
+	psp := &sp
+	CheckI("psp", psp, 2)
+	CheckF("psp.M", psp.M, 2)
+	CheckF("(*psp).M", (*psp).M, 2)
+
+	wv := Twordv(3)
+	CheckI("wv", wv, 3)
+	CheckF("wv.M", wv.M, 3)
+	CheckF("(&wv).M", (&wv).M, 3)
+	pwv := &wv
+	CheckI("pwv", pwv, 3)
+	CheckF("pwv.M", pwv.M, 3)
+	CheckF("(*pwv).M", (*pwv).M, 3)
+
+	wp := Twordp(4)
+	CheckI("&wp", &wp, 4)
+	CheckF("wp.M", wp.M, 4)
+	CheckF("(&wp).M", (&wp).M, 4)
+	pwp := &wp
+	CheckI("pwp", pwp, 4)
+	CheckF("pwp.M", pwp.M, 4)
+	CheckF("(*pwp).M", (*pwp).M, 4)
+
+	bv := Tbigv([2]uintptr{5, 6})
+	pbv := &bv
+	CheckI("bv", bv, 11)
+	CheckF("bv.M", bv.M, 11)
+	CheckF("(&bv).M", (&bv).M, 11)
+	CheckI("pbv", pbv, 11)
+	CheckF("pbv.M", pbv.M, 11)
+	CheckF("(*pbv).M", (*pbv).M, 11)
+	
+	bp := Tbigp([2]uintptr{7,8})
+	CheckI("&bp", &bp, 15)
+	CheckF("bp.M", bp.M, 15)
+	CheckF("(&bp).M", (&bp).M, 15)
+	pbp := &bp
+	CheckI("pbp", pbp, 15)
+	CheckF("pbp.M", pbp.M, 15)
+	CheckF("(*pbp).M", (*pbp).M, 15)
+
+	_sv := tsmallv(1)
+	checkI("_sv", _sv, 1)
+	checkF("_sv.m", _sv.m, 1)
+	checkF("(&_sv).m", (&_sv).m, 1)
+	_psv := &_sv
+	checkI("_psv", _psv, 1)
+	checkF("_psv.m", _psv.m, 1)
+	checkF("(*_psv).m", (*_psv).m, 1)
+
+	_sp := tsmallp(2)
+	checkI("&_sp", &_sp, 2)
+	checkF("_sp.m", _sp.m, 2)
+	checkF("(&_sp).m", (&_sp).m, 2)
+	_psp := &_sp
+	checkI("_psp", _psp, 2)
+	checkF("_psp.m", _psp.m, 2)
+	checkF("(*_psp).m", (*_psp).m, 2)
+
+	_wv := twordv(3)
+	checkI("_wv", _wv, 3)
+	checkF("_wv.m", _wv.m, 3)
+	checkF("(&_wv).m", (&_wv).m, 3)
+	_pwv := &_wv
+	checkI("_pwv", _pwv, 3)
+	checkF("_pwv.m", _pwv.m, 3)
+	checkF("(*_pwv).m", (*_pwv).m, 3)
+
+	_wp := twordp(4)
+	checkI("&_wp", &_wp, 4)
+	checkF("_wp.m", _wp.m, 4)
+	checkF("(&_wp).m", (&_wp).m, 4)
+	_pwp := &_wp
+	checkI("_pwp", _pwp, 4)
+	checkF("_pwp.m", _pwp.m, 4)
+	checkF("(*_pwp).m", (*_pwp).m, 4)
+
+	_bv := tbigv([2]uintptr{5, 6})
+	_pbv := &_bv
+	checkI("_bv", _bv, 11)
+	checkF("_bv.m", _bv.m, 11)
+	checkF("(&_bv).m", (&_bv).m, 11)
+	checkI("_pbv", _pbv, 11)
+	checkF("_pbv.m", _pbv.m, 11)
+	checkF("(*_pbv).m", (*_pbv).m, 11)
+	
+	_bp := tbigp([2]uintptr{7,8})
+	checkI("&_bp", &_bp, 15)
+	checkF("_bp.m", _bp.m, 15)
+	checkF("(&_bp).m", (&_bp).m, 15)
+	_pbp := &_bp
+	checkI("_pbp", _pbp, 15)
+	checkF("_pbp.m", _pbp.m, 15)
+	checkF("(*_pbp).m", (*_pbp).m, 15)
+	
+	t4 := T4{}
+	t3 := T3{&t4}
+	t2 := T2{&t3}
+	t1 := T1{t2}
+	CheckI("t4", t4, 40)
+	CheckI("&t4", &t4, 40)
+	CheckI("t3", t3, 40)
+	CheckI("&t3", &t3, 40)
+	CheckI("t2", t2, 40)
+	CheckI("&t2", &t2, 40)
+	CheckI("t1", t1, 40)
+	CheckI("&t1", &t1, 40)
+	
+	// x.M panics if x is an interface type and is nil,
+	// or if x.M expands to (*x).M where x is nil,
+	// or if x.M expands to x.y.z.w.M where something
+	// along the evaluation of x.y.z.w is nil.
+	var f func(int, byte) (byte, int)
+	shouldPanic(func() { psv = nil; f = psv.M })
+	shouldPanic(func() { pwv = nil; f = pwv.M })
+	shouldPanic(func() { pbv = nil; f = pbv.M })
+	shouldPanic(func() { var i Tinter; f = i.M })
+	shouldPanic(func() { _psv = nil; f = _psv.m })
+	shouldPanic(func() { _pwv = nil; f = _pwv.m })
+	shouldPanic(func() { _pbv = nil; f = _pbv.m })
+	shouldPanic(func() { var _i tinter; f = _i.m })
+	shouldPanic(func() { var t1 T1; f = t1.M })
+	shouldPanic(func() { var t2 T2; f = t2.M })
+	shouldPanic(func() { var t3 *T3; f = t3.M })
+	shouldPanic(func() { var t3 T3; f = t3.M })
+
+	if f != nil {
+		panic("something set f")
+	}
+	
+	// x.M does not panic if x is a nil pointer and
+	// M is a method with a pointer receiver.
+	shouldNotPanic(func() { psp = nil; f = psp.M })
+	shouldNotPanic(func() { pwp = nil; f = pwp.M })
+	shouldNotPanic(func() { pbp = nil; f = pbp.M })
+	shouldNotPanic(func() { _psp = nil; f = _psp.m })
+	shouldNotPanic(func() { _pwp = nil; f = _pwp.m })
+	shouldNotPanic(func() { _pbp = nil; f = _pbp.m })
+	shouldNotPanic(func() { var t4 T4; f = t4.M })
+	if f == nil {
+		panic("nothing set f")
+	}
+}