cmd/compile: fix Node.Etype overloading

Add helper methods that validate n.Op and convert to/from the
appropriate type.

Notably, there was a lot of code in walk.go that thought setting
Etype=1 on an OADDR node affected escape analysis.

Passes toolstash-check.

TBR=marvin

Change-Id: Ieae7c67225c1459c9719f9e6a748a25b975cf758
Reviewed-on: https://go-review.googlesource.com/99535Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/alg.go

@@ -233,7 +233,6 @@ func genhash(sym *types.Sym, t *types.Type) {
 		nx := nod(OINDEX, np, ni)
 		nx.SetBounded(true)
 		na := nod(OADDR, nx, nil)
-		na.Etype = 1 // no escape to heap
 		call.List.Append(na)
 		call.List.Append(nh)
 		n.Nbody.Append(nod(OAS, nh, call))
@@ -258,7 +257,6 @@ func genhash(sym *types.Sym, t *types.Type) {
 				call := nod(OCALL, hashel, nil)
 				nx := nodSym(OXDOT, np, f.Sym) // TODO: fields from other packages?
 				na := nod(OADDR, nx, nil)
-				na.Etype = 1 // no escape to heap
 				call.List.Append(na)
 				call.List.Append(nh)
 				fn.Nbody.Append(nod(OAS, nh, call))
@@ -274,7 +272,6 @@ func genhash(sym *types.Sym, t *types.Type) {
 			call := nod(OCALL, hashel, nil)
 			nx := nodSym(OXDOT, np, f.Sym) // TODO: fields from other packages?
 			na := nod(OADDR, nx, nil)
-			na.Etype = 1 // no escape to heap
 			call.List.Append(na)
 			call.List.Append(nh)
 			call.List.Append(nodintconst(size))
@@ -518,9 +515,7 @@ func eqfield(p *Node, q *Node, field *types.Sym) *Node {
 // 	memequal(&p.field, &q.field [, size])
 func eqmem(p *Node, q *Node, field *types.Sym, size int64) *Node {
 	nx := nod(OADDR, nodSym(OXDOT, p, field), nil)
-	nx.Etype = 1 // does not escape
 	ny := nod(OADDR, nodSym(OXDOT, q, field), nil)
-	ny.Etype = 1 // does not escape
 	nx = typecheck(nx, Erv)
 	ny = typecheck(ny, Erv)
 

src/cmd/compile/internal/gc/bexport.go

@@ -1461,7 +1461,7 @@ func (p *exporter) expr(n *Node) {
 		p.exprList(n.List)
 
 	case OCMPSTR, OCMPIFACE:
-		p.op(Op(n.Etype))
+		p.op(n.SubOp())
 		p.pos(n)
 		p.expr(n.Left)
 		p.expr(n.Right)
@@ -1527,7 +1527,7 @@ func (p *exporter) stmt(n *Node) {
 	case OASOP:
 		p.op(OASOP)
 		p.pos(n)
-		p.int(int(n.Etype))
+		p.op(n.SubOp())
 		p.expr(n.Left)
 		if p.bool(!n.Implicit()) {
 			p.expr(n.Right)

src/cmd/compile/internal/gc/bimport.go

@@ -1124,7 +1124,7 @@ func (p *importer) node() *Node {
 
 	case OASOP:
 		n := nodl(p.pos(), OASOP, nil, nil)
-		n.Etype = types.EType(p.int())
+		n.SetSubOp(p.op())
 		n.Left = p.expr()
 		if !p.bool() {
 			n.Right = nodintconst(1)

src/cmd/compile/internal/gc/fmt.go

@@ -926,7 +926,7 @@ func (n *Node) stmtfmt(s fmt.State, mode fmtMode) {
 
 	case OASOP:
 		if n.Implicit() {
-			if Op(n.Etype) == OADD {
+			if n.SubOp() == OADD {
 				mode.Fprintf(s, "%v++", n.Left)
 			} else {
 				mode.Fprintf(s, "%v--", n.Left)
@@ -934,7 +934,7 @@ func (n *Node) stmtfmt(s fmt.State, mode fmtMode) {
 			break
 		}
 
-		mode.Fprintf(s, "%v %#v= %v", n.Left, Op(n.Etype), n.Right)
+		mode.Fprintf(s, "%v %#v= %v", n.Left, n.SubOp(), n.Right)
 
 	case OAS2:
 		if n.Colas() && !complexinit {
@@ -1274,7 +1274,7 @@ func (n *Node) exprfmt(s fmt.State, prec int, mode fmtMode) {
 		mode.Fprintf(s, "map[%v]%v", n.Left, n.Right)
 
 	case OTCHAN:
-		switch types.ChanDir(n.Etype) {
+		switch n.TChanDir() {
 		case types.Crecv:
 			mode.Fprintf(s, "<-chan %v", n.Left)
 
@@ -1282,7 +1282,7 @@ func (n *Node) exprfmt(s fmt.State, prec int, mode fmtMode) {
 			mode.Fprintf(s, "chan<- %v", n.Left)
 
 		default:
-			if n.Left != nil && n.Left.Op == OTCHAN && n.Left.Sym == nil && types.ChanDir(n.Left.Etype) == types.Crecv {
+			if n.Left != nil && n.Left.Op == OTCHAN && n.Left.Sym == nil && n.Left.TChanDir() == types.Crecv {
 				mode.Fprintf(s, "chan (%v)", n.Left)
 			} else {
 				mode.Fprintf(s, "chan %v", n.Left)
@@ -1517,8 +1517,7 @@ func (n *Node) exprfmt(s fmt.State, prec int, mode fmtMode) {
 
 	case OCMPSTR, OCMPIFACE:
 		n.Left.exprfmt(s, nprec, mode)
-		// TODO(marvin): Fix Node.EType type union.
-		mode.Fprintf(s, " %#v ", Op(n.Etype))
+		mode.Fprintf(s, " %#v ", n.SubOp())
 		n.Right.exprfmt(s, nprec+1, mode)
 
 	default:
@@ -1593,7 +1592,7 @@ func (n *Node) nodedump(s fmt.State, flag FmtFlag, mode fmtMode) {
 		}
 
 	case OASOP:
-		mode.Fprintf(s, "%v-%v%j", n.Op, Op(n.Etype), n)
+		mode.Fprintf(s, "%v-%v%j", n.Op, n.SubOp(), n)
 
 	case OTYPE:
 		mode.Fprintf(s, "%v %v%j type=%v", n.Op, n.Sym, n, n.Type)

src/cmd/compile/internal/gc/inl.go

@@ -1005,7 +1005,6 @@ func mkinlcall1(n, fn *Node, isddd bool) *Node {
 	}
 
 	retlabel := autolabel(".i")
-	retlabel.Etype = 1 // flag 'safe' for escape analysis (no backjumps)
 
 	inlgen++
 

src/cmd/compile/internal/gc/noder.go

@@ -654,7 +654,7 @@ func (p *noder) expr(expr syntax.Expr) *Node {
 		return p.nod(expr, OTMAP, p.typeExpr(expr.Key), p.typeExpr(expr.Value))
 	case *syntax.ChanType:
 		n := p.nod(expr, OTCHAN, p.typeExpr(expr.Elem), nil)
-		n.Etype = types.EType(p.chanDir(expr.Dir))
+		n.SetTChanDir(p.chanDir(expr.Dir))
 		return n
 
 	case *syntax.TypeSwitchGuard:
@@ -902,7 +902,7 @@ func (p *noder) stmtFall(stmt syntax.Stmt, fallOK bool) *Node {
 		if stmt.Op != 0 && stmt.Op != syntax.Def {
 			n := p.nod(stmt, OASOP, p.expr(stmt.Lhs), p.expr(stmt.Rhs))
 			n.SetImplicit(stmt.Rhs == syntax.ImplicitOne)
-			n.Etype = types.EType(p.binOp(stmt.Op))
+			n.SetSubOp(p.binOp(stmt.Op))
 			return n
 		}
 

src/cmd/compile/internal/gc/order.go

@@ -526,15 +526,14 @@ func (o *Order) stmt(n *Node) {
 		n.Left = o.safeExpr(n.Left)
 		tmp1 := treecopy(n.Left, src.NoXPos)
 		if tmp1.Op == OINDEXMAP {
-			tmp1.Etype = 0 // now an rvalue not an lvalue
+			tmp1.SetIndexMapLValue(false)
 		}
 		tmp1 = o.copyExpr(tmp1, n.Left.Type, false)
-		// TODO(marvin): Fix Node.EType type union.
-		n.Right = nod(Op(n.Etype), tmp1, n.Right)
+		n.Right = nod(n.SubOp(), tmp1, n.Right)
 		n.Right = typecheck(n.Right, Erv)
 		n.Right = o.expr(n.Right, nil)
-		n.Etype = 0
 		n.Op = OAS
+		n.ResetAux()
 		o.mapAssign(n)
 		o.cleanTemp(t)
 
@@ -1015,7 +1014,7 @@ func (o *Order) expr(n, lhs *Node) *Node {
 		n.Right = o.expr(n.Right, nil)
 		needCopy := false
 
-		if n.Etype == 0 && instrumenting {
+		if !n.IndexMapLValue() && instrumenting {
 			// Race detector needs the copy so it can
 			// call treecopy on the result.
 			needCopy = true
@@ -1031,7 +1030,7 @@ func (o *Order) expr(n, lhs *Node) *Node {
 		// the map index, because the map access is going to
 		// be forced to happen immediately following this
 		// conversion (by the ordercopyexpr a few lines below).
-		if n.Etype == 0 && n.Right.Op == OARRAYBYTESTR {
+		if !n.IndexMapLValue() && n.Right.Op == OARRAYBYTESTR {
 			n.Right.Op = OARRAYBYTESTRTMP
 			needCopy = true
 		}

src/cmd/compile/internal/gc/syntax.go

@@ -56,7 +56,61 @@ type Node struct {
 	Esc uint16 // EscXXX
 
 	Op  Op
-	Etype types.EType // op for OASOP, etype for OTYPE, exclam for export, 6g saved reg, ChanDir for OTCHAN, for OINDEXMAP 1=LHS,0=RHS
+	aux uint8
+}
+
+func (n *Node) ResetAux() {
+	n.aux = 0
+}
+
+func (n *Node) SubOp() Op {
+	switch n.Op {
+	case OASOP, OCMPIFACE, OCMPSTR, ONAME:
+	default:
+		Fatalf("unexpected op: %v", n.Op)
+	}
+	return Op(n.aux)
+}
+
+func (n *Node) SetSubOp(op Op) {
+	switch n.Op {
+	case OASOP, OCMPIFACE, OCMPSTR, ONAME:
+	default:
+		Fatalf("unexpected op: %v", n.Op)
+	}
+	n.aux = uint8(op)
+}
+
+func (n *Node) IndexMapLValue() bool {
+	if n.Op != OINDEXMAP {
+		Fatalf("unexpected op: %v", n.Op)
+	}
+	return n.aux != 0
+}
+
+func (n *Node) SetIndexMapLValue(b bool) {
+	if n.Op != OINDEXMAP {
+		Fatalf("unexpected op: %v", n.Op)
+	}
+	if b {
+		n.aux = 1
+	} else {
+		n.aux = 0
+	}
+}
+
+func (n *Node) TChanDir() types.ChanDir {
+	if n.Op != OTCHAN {
+		Fatalf("unexpected op: %v", n.Op)
+	}
+	return types.ChanDir(n.aux)
+}
+
+func (n *Node) SetTChanDir(dir types.ChanDir) {
+	if n.Op != OTCHAN {
+		Fatalf("unexpected op: %v", n.Op)
+	}
+	n.aux = uint8(dir)
 }
 
 func (n *Node) IsSynthetic() bool {

src/cmd/compile/internal/gc/typecheck.go

@@ -263,7 +263,7 @@ func typecheck1(n *Node, top int) *Node {
 		// n.Sym is a field/method name, not a variable.
 	default:
 		if n.Sym != nil {
-			if n.Op == ONAME && n.Etype != 0 && top&Ecall == 0 {
+			if n.Op == ONAME && n.SubOp() != 0 && top&Ecall == 0 {
 				yyerror("use of builtin %v not in function call", n.Sym)
 				n.Type = nil
 				return n
@@ -300,7 +300,7 @@ func typecheck1(n *Node, top int) *Node {
 		if n.Name.Decldepth == 0 {
 			n.Name.Decldepth = decldepth
 		}
-		if n.Etype != 0 {
+		if n.SubOp() != 0 {
 			ok |= Ecall
 			break
 		}
@@ -428,11 +428,11 @@ func typecheck1(n *Node, top int) *Node {
 		if l.Type.NotInHeap() {
 			yyerror("chan of go:notinheap type not allowed")
 		}
-		t := types.NewChan(l.Type, types.ChanDir(n.Etype)) // TODO(marvin): Fix Node.EType type union.
+		t := types.NewChan(l.Type, n.TChanDir())
 		n.Op = OTYPE
 		n.Type = t
 		n.Left = nil
-		n.Etype = 0
+		n.ResetAux()
 
 	case OTSTRUCT:
 		ok |= Etype
@@ -540,7 +540,7 @@ func typecheck1(n *Node, top int) *Node {
 				return n
 			}
 			// TODO(marvin): Fix Node.EType type union.
-			op = Op(n.Etype)
+			op = n.SubOp()
 		} else {
 			ok |= Erv
 			n.Left = typecheck(n.Left, Erv)
@@ -712,9 +712,9 @@ func typecheck1(n *Node, top int) *Node {
 
 		if et == TSTRING {
 			if iscmp[n.Op] {
-				// TODO(marvin): Fix Node.EType type union.
-				n.Etype = types.EType(n.Op)
+				ot := n.Op
 				n.Op = OCMPSTR
+				n.SetSubOp(ot)
 			} else if n.Op == OADD {
 				// create OADDSTR node with list of strings in x + y + z + (w + v) + ...
 				n.Op = OADDSTR
@@ -743,9 +743,9 @@ func typecheck1(n *Node, top int) *Node {
 			} else if r.Op == OLITERAL && r.Val().Ctype() == CTNIL {
 			} else // leave alone for back end
 			if r.Type.IsInterface() == l.Type.IsInterface() {
-				// TODO(marvin): Fix Node.EType type union.
-				n.Etype = types.EType(n.Op)
+				ot := n.Op
 				n.Op = OCMPIFACE
+				n.SetSubOp(ot)
 			}
 		}
 
@@ -1026,13 +1026,13 @@ func typecheck1(n *Node, top int) *Node {
 			}
 
 		case TMAP:
-			n.Etype = 0
 			n.Right = defaultlit(n.Right, t.Key())
 			if n.Right.Type != nil {
 				n.Right = assignconv(n.Right, t.Key(), "map index")
 			}
 			n.Type = t.Val()
 			n.Op = OINDEXMAP
+			n.ResetAux()
 		}
 
 	case ORECV:
@@ -1088,10 +1088,6 @@ func typecheck1(n *Node, top int) *Node {
 			return n
 		}
 		n.Right = assignconv(r, t.Elem(), "send")
-
-		// TODO: more aggressive
-		n.Etype = 0
-
 		n.Type = nil
 
 	case OSLICE, OSLICE3:
@@ -1177,15 +1173,13 @@ func typecheck1(n *Node, top int) *Node {
 
 		l := n.Left
 
-		if l.Op == ONAME && l.Etype != 0 {
-			// TODO(marvin): Fix Node.EType type union.
-			if n.Isddd() && Op(l.Etype) != OAPPEND {
+		if l.Op == ONAME && l.SubOp() != 0 {
+			if n.Isddd() && l.SubOp() != OAPPEND {
 				yyerror("invalid use of ... with builtin %v", l)
 			}
 
 			// builtin: OLEN, OCAP, etc.
-			// TODO(marvin): Fix Node.EType type union.
-			n.Op = Op(l.Etype)
+			n.Op = l.SubOp()
 			n.Left = n.Right
 			n.Right = nil
 			n = typecheck1(n, top)
@@ -3214,7 +3208,7 @@ func checkassign(stmt *Node, n *Node) {
 		return
 	}
 	if n.Op == OINDEXMAP {
-		n.Etype = 1
+		n.SetIndexMapLValue(true)
 		return
 	}
 
@@ -3705,7 +3699,7 @@ func typecheckdef(n *Node) {
 			break
 		}
 		if n.Name.Defn == nil {
-			if n.Etype != 0 { // like OPRINTN
+			if n.SubOp() != 0 { // like OPRINTN
 				break
 			}
 			if nsavederrors+nerrors > 0 {

src/cmd/compile/internal/gc/universe.go

@@ -114,16 +114,15 @@ func lexinit() {
 	}
 
 	for _, s := range builtinFuncs {
-		// TODO(marvin): Fix Node.EType type union.
 		s2 := builtinpkg.Lookup(s.name)
 		s2.Def = asTypesNode(newname(s2))
-		asNode(s2.Def).Etype = types.EType(s.op)
+		asNode(s2.Def).SetSubOp(s.op)
 	}
 
 	for _, s := range unsafeFuncs {
 		s2 := unsafepkg.Lookup(s.name)
 		s2.Def = asTypesNode(newname(s2))
-		asNode(s2.Def).Etype = types.EType(s.op)
+		asNode(s2.Def).SetSubOp(s.op)
 	}
 
 	types.Idealstring = types.New(TSTRING)

src/cmd/compile/internal/gc/walk.go

@@ -557,7 +557,7 @@ opswitch:
 		n.Right = walkexpr(n.Right, init)
 		t := n.Left.Type
 		n.SetBounded(bounded(n.Right, 8*t.Width))
-		if Debug['m'] != 0 && n.Etype != 0 && !Isconst(n.Right, CTINT) {
+		if Debug['m'] != 0 && n.Bounded() && !Isconst(n.Right, CTINT) {
 			Warn("shift bounds check elided")
 		}
 
@@ -767,7 +767,6 @@ opswitch:
 		} else {
 			n1 = nod(OADDR, n.List.First(), nil)
 		}
-		n1.Etype = 1 // addr does not escape
 		fn := chanfn("chanrecv2", 2, r.Left.Type)
 		ok := n.List.Second()
 		call := mkcall1(fn, ok.Type, init, r.Left, n1)
@@ -1158,7 +1157,7 @@ opswitch:
 		map_ := n.Left
 		key := n.Right
 		t := map_.Type
-		if n.Etype == 1 {
+		if n.IndexMapLValue() {
 			// This m[k] expression is on the left-hand side of an assignment.
 			fast := mapfast(t)
 			if fast == mapslow {
@@ -1235,9 +1234,8 @@ opswitch:
 
 	case OCMPSTR:
 		// s + "badgerbadgerbadger" == "badgerbadgerbadger"
-		if (Op(n.Etype) == OEQ || Op(n.Etype) == ONE) && Isconst(n.Right, CTSTR) && n.Left.Op == OADDSTR && n.Left.List.Len() == 2 && Isconst(n.Left.List.Second(), CTSTR) && strlit(n.Right) == strlit(n.Left.List.Second()) {
-			// TODO(marvin): Fix Node.EType type union.
-			r := nod(Op(n.Etype), nod(OLEN, n.Left.List.First(), nil), nodintconst(0))
+		if (n.SubOp() == OEQ || n.SubOp() == ONE) && Isconst(n.Right, CTSTR) && n.Left.Op == OADDSTR && n.Left.List.Len() == 2 && Isconst(n.Left.List.Second(), CTSTR) && strlit(n.Right) == strlit(n.Left.List.Second()) {
+			r := nod(n.SubOp(), nod(OLEN, n.Left.List.First(), nil), nodintconst(0))
 			n = finishcompare(n, r, init)
 			break
 		}
@@ -1255,7 +1253,7 @@ opswitch:
 			ncs = n.Left
 		}
 		if cs != nil {
-			cmp := Op(n.Etype)
+			cmp := n.SubOp()
 			// maxRewriteLen was chosen empirically.
 			// It is the value that minimizes cmd/go file size
 			// across most architectures.
@@ -1294,7 +1292,6 @@ opswitch:
 				if len(s) > 0 {
 					ncs = safeexpr(ncs, init)
 				}
-				// TODO(marvin): Fix Node.EType type union.
 				r := nod(cmp, nod(OLEN, ncs, nil), nodintconst(int64(len(s))))
 				remains := len(s)
 				for i := 0; remains > 0; {
@@ -1344,8 +1341,7 @@ opswitch:
 		}
 
 		var r *Node
-		// TODO(marvin): Fix Node.EType type union.
-		if Op(n.Etype) == OEQ || Op(n.Etype) == ONE {
+		if n.SubOp() == OEQ || n.SubOp() == ONE {
 			// prepare for rewrite below
 			n.Left = cheapexpr(n.Left, init)
 			n.Right = cheapexpr(n.Right, init)
@@ -1363,8 +1359,7 @@ opswitch:
 
 			// quick check of len before full compare for == or !=.
 			// memequal then tests equality up to length len.
-			// TODO(marvin): Fix Node.EType type union.
-			if Op(n.Etype) == OEQ {
+			if n.SubOp() == OEQ {
 				// len(left) == len(right) && memequal(left, right, len)
 				r = nod(OANDAND, nod(OEQ, llen, rlen), r)
 			} else {
@@ -1375,8 +1370,7 @@ opswitch:
 		} else {
 			// sys_cmpstring(s1, s2) :: 0
 			r = mkcall("cmpstring", types.Types[TINT], init, conv(n.Left, types.Types[TSTRING]), conv(n.Right, types.Types[TSTRING]))
-			// TODO(marvin): Fix Node.EType type union.
-			r = nod(Op(n.Etype), r, nodintconst(0))
+			r = nod(n.SubOp(), r, nodintconst(0))
 		}
 
 		n = finishcompare(n, r, init)
@@ -1677,9 +1671,8 @@ opswitch:
 
 		// Check itable/type before full compare.
 		// Note: short-circuited because order matters.
-		// TODO(marvin): Fix Node.EType type union.
 		var cmp *Node
-		if Op(n.Etype) == OEQ {
+		if n.SubOp() == OEQ {
 			cmp = nod(OANDAND, nod(OEQ, lt, rt), call)
 		} else {
 			cmp = nod(OOROR, nod(ONE, lt, rt), nod(ONOT, call, nil))
@@ -2955,14 +2948,12 @@ func appendslice(n *Node, init *Nodes) *Node {
 	// s = s[:n]
 	nt := nod(OSLICE, s, nil)
 	nt.SetSliceBounds(nil, nn, nil)
-	nt.Etype = 1
 	l = append(l, nod(OAS, s, nt))
 
 	if l1.Type.Elem().HasHeapPointer() {
 		// copy(s[len(l1):], l2)
 		nptr1 := nod(OSLICE, s, nil)
 		nptr1.SetSliceBounds(nod(OLEN, l1, nil), nil, nil)
-		nptr1.Etype = 1
 		nptr2 := l2
 		Curfn.Func.setWBPos(n.Pos)
 		fn := syslook("typedslicecopy")
@@ -2976,7 +2967,6 @@ func appendslice(n *Node, init *Nodes) *Node {
 		// copy(s[len(l1):], l2)
 		nptr1 := nod(OSLICE, s, nil)
 		nptr1.SetSliceBounds(nod(OLEN, l1, nil), nil, nil)
-		nptr1.Etype = 1
 		nptr2 := l2
 
 		var ln Nodes
@@ -3095,7 +3085,6 @@ func walkappend(n *Node, init *Nodes, dst *Node) *Node {
 
 	nx = nod(OSLICE, ns, nil) // ...s[:n+argc]
 	nx.SetSliceBounds(nil, nod(OADD, nn, na), nil)
-	nx.Etype = 1
 	l = append(l, nod(OAS, ns, nx)) // s = s[:n+argc]
 
 	ls = n.List.Slice()[1:]
@@ -3320,13 +3309,11 @@ func walkcompare(n *Node, init *Nodes) *Node {
 		// eq algs take pointers
 		pl := temp(types.NewPtr(t))
 		al := nod(OAS, pl, nod(OADDR, cmpl, nil))
-		al.Right.Etype = 1 // addr does not escape
 		al = typecheck(al, Etop)
 		init.Append(al)
 
 		pr := temp(types.NewPtr(t))
 		ar := nod(OAS, pr, nod(OADDR, cmpr, nil))
-		ar.Right.Etype = 1 // addr does not escape
 		ar = typecheck(ar, Etop)
 		init.Append(ar)