Пример #1
0
Файл: gsubr.go Проект: rsc/tmp
func gclean() {
	for _, r := range Thearch.ReservedRegs {
		reg[r-Thearch.REGMIN]--
	}

	for r := Thearch.REGMIN; r <= Thearch.REGMAX; r++ {
		n := reg[r-Thearch.REGMIN]
		if n != 0 {
			Yyerror("reg %v left allocated", obj.Rconv(r))
			if Debug['v'] != 0 {
				Regdump()
			}
		}
	}

	for r := Thearch.FREGMIN; r <= Thearch.FREGMAX; r++ {
		n := reg[r-Thearch.REGMIN]
		if n != 0 {
			Yyerror("reg %v left allocated", obj.Rconv(r))
			if Debug['v'] != 0 {
				Regdump()
			}
		}
	}
}
Пример #2
0
Файл: gsubr.go Проект: rsc/tmp
func Regdump() {
	if Debug['v'] == 0 {
		fmt.Printf("run compiler with -v for register allocation sites\n")
		return
	}

	dump := func(r int) {
		stk := regstk[r-Thearch.REGMIN]
		if len(stk) == 0 {
			return
		}
		fmt.Printf("reg %v allocated at:\n", obj.Rconv(r))
		fmt.Printf("\t%s\n", strings.Replace(strings.TrimSpace(string(stk)), "\n", "\n\t", -1))
	}

	for r := Thearch.REGMIN; r <= Thearch.REGMAX; r++ {
		if reg[r-Thearch.REGMIN] != 0 {
			dump(r)
		}
	}
	for r := Thearch.FREGMIN; r <= Thearch.FREGMAX; r++ {
		if reg[r-Thearch.REGMIN] == 0 {
			dump(r)
		}
	}
}
Пример #3
0
Файл: reg.go Проект: rsc/tmp
func regopt(firstp *obj.Prog) {
	mergetemp(firstp)

	/*
	 * control flow is more complicated in generated go code
	 * than in generated c code.  define pseudo-variables for
	 * registers, so we have complete register usage information.
	 */
	var nreg int
	regnames := Thearch.Regnames(&nreg)

	nvar = nreg
	for i := 0; i < nreg; i++ {
		vars[i] = Var{}
	}
	for i := 0; i < nreg; i++ {
		if regnodes[i] == nil {
			regnodes[i] = newname(Lookup(regnames[i]))
		}
		vars[i].node = regnodes[i]
	}

	regbits = Thearch.Excludedregs()
	externs = zbits
	params = zbits
	consts = zbits
	addrs = zbits
	ivar = zbits
	ovar = zbits

	/*
	 * pass 1
	 * build aux data structure
	 * allocate pcs
	 * find use and set of variables
	 */
	g := Flowstart(firstp, func() interface{} { return new(Reg) })
	if g == nil {
		for i := 0; i < nvar; i++ {
			vars[i].node.Opt = nil
		}
		return
	}

	firstf := g.Start

	for f := firstf; f != nil; f = f.Link {
		p := f.Prog
		if p.As == obj.AVARDEF || p.As == obj.AVARKILL {
			continue
		}

		// Avoid making variables for direct-called functions.
		if p.As == obj.ACALL && p.To.Type == obj.TYPE_MEM && p.To.Name == obj.NAME_EXTERN {
			continue
		}

		// from vs to doesn't matter for registers.
		r := f.Data.(*Reg)
		r.use1.b[0] |= p.Info.Reguse | p.Info.Regindex
		r.set.b[0] |= p.Info.Regset

		bit := mkvar(f, &p.From)
		if bany(&bit) {
			if p.Info.Flags&LeftAddr != 0 {
				setaddrs(bit)
			}
			if p.Info.Flags&LeftRead != 0 {
				for z := 0; z < BITS; z++ {
					r.use1.b[z] |= bit.b[z]
				}
			}
			if p.Info.Flags&LeftWrite != 0 {
				for z := 0; z < BITS; z++ {
					r.set.b[z] |= bit.b[z]
				}
			}
		}

		// Compute used register for reg
		if p.Info.Flags&RegRead != 0 {
			r.use1.b[0] |= Thearch.RtoB(int(p.Reg))
		}

		// Currently we never generate three register forms.
		// If we do, this will need to change.
		if p.From3.Type != obj.TYPE_NONE {
			Fatal("regopt not implemented for from3")
		}

		bit = mkvar(f, &p.To)
		if bany(&bit) {
			if p.Info.Flags&RightAddr != 0 {
				setaddrs(bit)
			}
			if p.Info.Flags&RightRead != 0 {
				for z := 0; z < BITS; z++ {
					r.use2.b[z] |= bit.b[z]
				}
			}
			if p.Info.Flags&RightWrite != 0 {
				for z := 0; z < BITS; z++ {
					r.set.b[z] |= bit.b[z]
				}
			}
		}
	}

	for i := 0; i < nvar; i++ {
		v := &vars[i]
		if v.addr != 0 {
			bit := blsh(uint(i))
			for z := 0; z < BITS; z++ {
				addrs.b[z] |= bit.b[z]
			}
		}

		if Debug['R'] != 0 && Debug['v'] != 0 {
			fmt.Printf("bit=%2d addr=%d et=%v w=%-2d s=%v + %d\n", i, v.addr, Econv(int(v.etype), 0), v.width, v.node, v.offset)
		}
	}

	if Debug['R'] != 0 && Debug['v'] != 0 {
		Dumpit("pass1", firstf, 1)
	}

	/*
	 * pass 2
	 * find looping structure
	 */
	flowrpo(g)

	if Debug['R'] != 0 && Debug['v'] != 0 {
		Dumpit("pass2", firstf, 1)
	}

	/*
	 * pass 2.5
	 * iterate propagating fat vardef covering forward
	 * r->act records vars with a VARDEF since the last CALL.
	 * (r->act will be reused in pass 5 for something else,
	 * but we'll be done with it by then.)
	 */
	active := 0

	for f := firstf; f != nil; f = f.Link {
		f.Active = 0
		r := f.Data.(*Reg)
		r.act = zbits
	}

	for f := firstf; f != nil; f = f.Link {
		p := f.Prog
		if p.As == obj.AVARDEF && Isfat(((p.To.Node).(*Node)).Type) && ((p.To.Node).(*Node)).Opt != nil {
			active++
			walkvardef(p.To.Node.(*Node), f, active)
		}
	}

	/*
	 * pass 3
	 * iterate propagating usage
	 * 	back until flow graph is complete
	 */
	var f1 *Flow
	var i int
	var f *Flow
loop1:
	change = 0

	for f = firstf; f != nil; f = f.Link {
		f.Active = 0
	}
	for f = firstf; f != nil; f = f.Link {
		if f.Prog.As == obj.ARET {
			prop(f, zbits, zbits)
		}
	}

	/* pick up unreachable code */
loop11:
	i = 0

	for f = firstf; f != nil; f = f1 {
		f1 = f.Link
		if f1 != nil && f1.Active != 0 && f.Active == 0 {
			prop(f, zbits, zbits)
			i = 1
		}
	}

	if i != 0 {
		goto loop11
	}
	if change != 0 {
		goto loop1
	}

	if Debug['R'] != 0 && Debug['v'] != 0 {
		Dumpit("pass3", firstf, 1)
	}

	/*
	 * pass 4
	 * iterate propagating register/variable synchrony
	 * 	forward until graph is complete
	 */
loop2:
	change = 0

	for f = firstf; f != nil; f = f.Link {
		f.Active = 0
	}
	synch(firstf, zbits)
	if change != 0 {
		goto loop2
	}

	if Debug['R'] != 0 && Debug['v'] != 0 {
		Dumpit("pass4", firstf, 1)
	}

	/*
	 * pass 4.5
	 * move register pseudo-variables into regu.
	 */
	mask := uint64((1 << uint(nreg)) - 1)
	for f := firstf; f != nil; f = f.Link {
		r := f.Data.(*Reg)
		r.regu = (r.refbehind.b[0] | r.set.b[0]) & mask
		r.set.b[0] &^= mask
		r.use1.b[0] &^= mask
		r.use2.b[0] &^= mask
		r.refbehind.b[0] &^= mask
		r.refahead.b[0] &^= mask
		r.calbehind.b[0] &^= mask
		r.calahead.b[0] &^= mask
		r.regdiff.b[0] &^= mask
		r.act.b[0] &^= mask
	}

	if Debug['R'] != 0 && Debug['v'] != 0 {
		Dumpit("pass4.5", firstf, 1)
	}

	/*
	 * pass 5
	 * isolate regions
	 * calculate costs (paint1)
	 */
	var bit Bits
	if f := firstf; f != nil {
		r := f.Data.(*Reg)
		for z := 0; z < BITS; z++ {
			bit.b[z] = (r.refahead.b[z] | r.calahead.b[z]) &^ (externs.b[z] | params.b[z] | addrs.b[z] | consts.b[z])
		}
		if bany(&bit) && f.Refset == 0 {
			// should never happen - all variables are preset
			if Debug['w'] != 0 {
				fmt.Printf("%v: used and not set: %v\n", f.Prog.Line(), &bit)
			}
			f.Refset = 1
		}
	}

	for f := firstf; f != nil; f = f.Link {
		(f.Data.(*Reg)).act = zbits
	}
	nregion = 0
	region = region[:0]
	var rgp *Rgn
	for f := firstf; f != nil; f = f.Link {
		r := f.Data.(*Reg)
		for z := 0; z < BITS; z++ {
			bit.b[z] = r.set.b[z] &^ (r.refahead.b[z] | r.calahead.b[z] | addrs.b[z])
		}
		if bany(&bit) && f.Refset == 0 {
			if Debug['w'] != 0 {
				fmt.Printf("%v: set and not used: %v\n", f.Prog.Line(), &bit)
			}
			f.Refset = 1
			Thearch.Excise(f)
		}

		for z := 0; z < BITS; z++ {
			bit.b[z] = LOAD(r, z) &^ (r.act.b[z] | addrs.b[z])
		}
		for bany(&bit) {
			i = bnum(bit)
			change = 0
			paint1(f, i)
			biclr(&bit, uint(i))
			if change <= 0 {
				continue
			}
			if nregion >= MaxRgn {
				nregion++
				continue
			}

			region = append(region, Rgn{
				enter: f,
				cost:  int16(change),
				varno: int16(i),
			})
			nregion++
		}
	}

	if false && Debug['v'] != 0 && strings.Contains(Curfn.Nname.Sym.Name, "Parse") {
		Warn("regions: %d\n", nregion)
	}
	if nregion >= MaxRgn {
		if Debug['v'] != 0 {
			Warn("too many regions: %d\n", nregion)
		}
		nregion = MaxRgn
	}

	sort.Sort(rcmp(region[:nregion]))

	if Debug['R'] != 0 && Debug['v'] != 0 {
		Dumpit("pass5", firstf, 1)
	}

	/*
	 * pass 6
	 * determine used registers (paint2)
	 * replace code (paint3)
	 */
	if Debug['R'] != 0 && Debug['v'] != 0 {
		fmt.Printf("\nregisterizing\n")
	}
	var usedreg uint64
	var vreg uint64
	for i := 0; i < nregion; i++ {
		rgp = &region[i]
		if Debug['R'] != 0 && Debug['v'] != 0 {
			fmt.Printf("region %d: cost %d varno %d enter %d\n", i, rgp.cost, rgp.varno, rgp.enter.Prog.Pc)
		}
		bit = blsh(uint(rgp.varno))
		usedreg = paint2(rgp.enter, int(rgp.varno), 0)
		vreg = allreg(usedreg, rgp)
		if rgp.regno != 0 {
			if Debug['R'] != 0 && Debug['v'] != 0 {
				v := &vars[rgp.varno]
				fmt.Printf("registerize %v+%d (bit=%2d et=%v) in %v usedreg=%#x vreg=%#x\n", v.node, v.offset, rgp.varno, Econv(int(v.etype), 0), obj.Rconv(int(rgp.regno)), usedreg, vreg)
			}

			paint3(rgp.enter, int(rgp.varno), vreg, int(rgp.regno))
		}
	}

	/*
	 * free aux structures. peep allocates new ones.
	 */
	for i := 0; i < nvar; i++ {
		vars[i].node.Opt = nil
	}
	Flowend(g)
	firstf = nil

	if Debug['R'] != 0 && Debug['v'] != 0 {
		// Rebuild flow graph, since we inserted instructions
		g := Flowstart(firstp, nil)
		firstf = g.Start
		Dumpit("pass6", firstf, 0)
		Flowend(g)
		firstf = nil
	}

	/*
	 * pass 7
	 * peep-hole on basic block
	 */
	if Debug['R'] == 0 || Debug['P'] != 0 {
		Thearch.Peep(firstp)
	}

	/*
	 * eliminate nops
	 */
	for p := firstp; p != nil; p = p.Link {
		for p.Link != nil && p.Link.As == obj.ANOP {
			p.Link = p.Link.Link
		}
		if p.To.Type == obj.TYPE_BRANCH {
			for p.To.Val.(*obj.Prog) != nil && p.To.Val.(*obj.Prog).As == obj.ANOP {
				p.To.Val = p.To.Val.(*obj.Prog).Link
			}
		}
	}

	if Debug['R'] != 0 {
		if Ostats.Ncvtreg != 0 || Ostats.Nspill != 0 || Ostats.Nreload != 0 || Ostats.Ndelmov != 0 || Ostats.Nvar != 0 || Ostats.Naddr != 0 || false {
			fmt.Printf("\nstats\n")
		}

		if Ostats.Ncvtreg != 0 {
			fmt.Printf("\t%4d cvtreg\n", Ostats.Ncvtreg)
		}
		if Ostats.Nspill != 0 {
			fmt.Printf("\t%4d spill\n", Ostats.Nspill)
		}
		if Ostats.Nreload != 0 {
			fmt.Printf("\t%4d reload\n", Ostats.Nreload)
		}
		if Ostats.Ndelmov != 0 {
			fmt.Printf("\t%4d delmov\n", Ostats.Ndelmov)
		}
		if Ostats.Nvar != 0 {
			fmt.Printf("\t%4d var\n", Ostats.Nvar)
		}
		if Ostats.Naddr != 0 {
			fmt.Printf("\t%4d addr\n", Ostats.Naddr)
		}

		Ostats = OptStats{}
	}
}
Пример #4
0
Файл: fmt.go Проект: rsc/tmp
func nodedump(n *Node, flag int) string {
	if n == nil {
		return ""
	}

	recur := flag&obj.FmtShort == 0

	var buf bytes.Buffer
	if recur {
		indent(&buf)
		if dumpdepth > 10 {
			buf.WriteString("...")
			return buf.String()
		}

		if n.Ninit != nil {
			fmt.Fprintf(&buf, "%v-init%v", Oconv(int(n.Op), 0), n.Ninit)
			indent(&buf)
		}
	}

	switch n.Op {
	default:
		fmt.Fprintf(&buf, "%v%v", Oconv(int(n.Op), 0), Jconv(n, 0))

	case OREGISTER, OINDREG:
		fmt.Fprintf(&buf, "%v-%v%v", Oconv(int(n.Op), 0), obj.Rconv(int(n.Reg)), Jconv(n, 0))

	case OLITERAL:
		fmt.Fprintf(&buf, "%v-%v%v", Oconv(int(n.Op), 0), Vconv(&n.Val, 0), Jconv(n, 0))

	case ONAME, ONONAME:
		if n.Sym != nil {
			fmt.Fprintf(&buf, "%v-%v%v", Oconv(int(n.Op), 0), n.Sym, Jconv(n, 0))
		} else {
			fmt.Fprintf(&buf, "%v%v", Oconv(int(n.Op), 0), Jconv(n, 0))
		}
		if recur && n.Type == nil && n.Ntype != nil {
			indent(&buf)
			fmt.Fprintf(&buf, "%v-ntype%v", Oconv(int(n.Op), 0), n.Ntype)
		}

	case OASOP:
		fmt.Fprintf(&buf, "%v-%v%v", Oconv(int(n.Op), 0), Oconv(int(n.Etype), 0), Jconv(n, 0))

	case OTYPE:
		fmt.Fprintf(&buf, "%v %v%v type=%v", Oconv(int(n.Op), 0), n.Sym, Jconv(n, 0), n.Type)
		if recur && n.Type == nil && n.Ntype != nil {
			indent(&buf)
			fmt.Fprintf(&buf, "%v-ntype%v", Oconv(int(n.Op), 0), n.Ntype)
		}
	}

	if n.Sym != nil && n.Op != ONAME {
		fmt.Fprintf(&buf, " %v G%d", n.Sym, n.Vargen)
	}

	if n.Type != nil {
		fmt.Fprintf(&buf, " %v", n.Type)
	}

	if recur {
		if n.Left != nil {
			buf.WriteString(Nconv(n.Left, 0))
		}
		if n.Right != nil {
			buf.WriteString(Nconv(n.Right, 0))
		}
		if n.List != nil {
			indent(&buf)
			fmt.Fprintf(&buf, "%v-list%v", Oconv(int(n.Op), 0), n.List)
		}

		if n.Rlist != nil {
			indent(&buf)
			fmt.Fprintf(&buf, "%v-rlist%v", Oconv(int(n.Op), 0), n.Rlist)
		}

		if n.Ntest != nil {
			indent(&buf)
			fmt.Fprintf(&buf, "%v-test%v", Oconv(int(n.Op), 0), n.Ntest)
		}

		if n.Nbody != nil {
			indent(&buf)
			fmt.Fprintf(&buf, "%v-body%v", Oconv(int(n.Op), 0), n.Nbody)
		}

		if n.Nelse != nil {
			indent(&buf)
			fmt.Fprintf(&buf, "%v-else%v", Oconv(int(n.Op), 0), n.Nelse)
		}

		if n.Nincr != nil {
			indent(&buf)
			fmt.Fprintf(&buf, "%v-incr%v", Oconv(int(n.Op), 0), n.Nincr)
		}
	}

	return buf.String()
}
Пример #5
0
Файл: fmt.go Проект: rsc/tmp
func exprfmt(n *Node, prec int) string {
	for n != nil && n.Implicit && (n.Op == OIND || n.Op == OADDR) {
		n = n.Left
	}

	if n == nil {
		return "<N>"
	}

	nprec := opprec[n.Op]
	if n.Op == OTYPE && n.Sym != nil {
		nprec = 8
	}

	if prec > nprec {
		return fmt.Sprintf("(%v)", n)
	}

	switch n.Op {
	case OPAREN:
		return fmt.Sprintf("(%v)", n.Left)

	case ODDDARG:
		return "... argument"

	case OREGISTER:
		return obj.Rconv(int(n.Reg))

	case OLITERAL: // this is a bit of a mess
		if fmtmode == FErr {
			if n.Orig != nil && n.Orig != n {
				return exprfmt(n.Orig, prec)
			}
			if n.Sym != nil {
				return Sconv(n.Sym, 0)
			}
		}
		if n.Val.Ctype == CTNIL && n.Orig != nil && n.Orig != n {
			return exprfmt(n.Orig, prec)
		}
		if n.Type != nil && n.Type != Types[n.Type.Etype] && n.Type != idealbool && n.Type != idealstring {
			// Need parens when type begins with what might
			// be misinterpreted as a unary operator: * or <-.
			if Isptr[n.Type.Etype] || (n.Type.Etype == TCHAN && n.Type.Chan == Crecv) {
				return fmt.Sprintf("(%v)(%v)", n.Type, Vconv(&n.Val, 0))
			} else {
				return fmt.Sprintf("%v(%v)", n.Type, Vconv(&n.Val, 0))
			}
		}

		return Vconv(&n.Val, 0)

		// Special case: name used as local variable in export.
	// _ becomes ~b%d internally; print as _ for export
	case ONAME:
		if fmtmode == FExp && n.Sym != nil && n.Sym.Name[0] == '~' && n.Sym.Name[1] == 'b' {
			return "_"
		}
		if fmtmode == FExp && n.Sym != nil && !isblank(n) && n.Vargen > 0 {
			return fmt.Sprintf("%v·%d", n.Sym, n.Vargen)
		}

		// Special case: explicit name of func (*T) method(...) is turned into pkg.(*T).method,
		// but for export, this should be rendered as (*pkg.T).meth.
		// These nodes have the special property that they are names with a left OTYPE and a right ONAME.
		if fmtmode == FExp && n.Left != nil && n.Left.Op == OTYPE && n.Right != nil && n.Right.Op == ONAME {
			if Isptr[n.Left.Type.Etype] {
				return fmt.Sprintf("(%v).%v", n.Left.Type, Sconv(n.Right.Sym, obj.FmtShort|obj.FmtByte))
			} else {
				return fmt.Sprintf("%v.%v", n.Left.Type, Sconv(n.Right.Sym, obj.FmtShort|obj.FmtByte))
			}
		}
		fallthrough

		//fallthrough
	case OPACK, ONONAME:
		return Sconv(n.Sym, 0)

	case OTYPE:
		if n.Type == nil && n.Sym != nil {
			return Sconv(n.Sym, 0)
		}
		return Tconv(n.Type, 0)

	case OTARRAY:
		if n.Left != nil {
			return fmt.Sprintf("[]%v", n.Left)
		}
		var f string
		f += fmt.Sprintf("[]%v", n.Right)
		return f // happens before typecheck

	case OTMAP:
		return fmt.Sprintf("map[%v]%v", n.Left, n.Right)

	case OTCHAN:
		switch n.Etype {
		case Crecv:
			return fmt.Sprintf("<-chan %v", n.Left)

		case Csend:
			return fmt.Sprintf("chan<- %v", n.Left)

		default:
			if n.Left != nil && n.Left.Op == OTCHAN && n.Left.Sym == nil && n.Left.Etype == Crecv {
				return fmt.Sprintf("chan (%v)", n.Left)
			} else {
				return fmt.Sprintf("chan %v", n.Left)
			}
		}

	case OTSTRUCT:
		return "<struct>"

	case OTINTER:
		return "<inter>"

	case OTFUNC:
		return "<func>"

	case OCLOSURE:
		if fmtmode == FErr {
			return "func literal"
		}
		if n.Nbody != nil {
			return fmt.Sprintf("%v { %v }", n.Type, n.Nbody)
		}
		return fmt.Sprintf("%v { %v }", n.Type, n.Closure.Nbody)

	case OCOMPLIT:
		ptrlit := n.Right != nil && n.Right.Implicit && n.Right.Type != nil && Isptr[n.Right.Type.Etype]
		if fmtmode == FErr {
			if n.Right != nil && n.Right.Type != nil && !n.Implicit {
				if ptrlit {
					return fmt.Sprintf("&%v literal", n.Right.Type.Type)
				} else {
					return fmt.Sprintf("%v literal", n.Right.Type)
				}
			}

			return "composite literal"
		}

		if fmtmode == FExp && ptrlit {
			// typecheck has overwritten OIND by OTYPE with pointer type.
			return fmt.Sprintf("(&%v{ %v })", n.Right.Type.Type, Hconv(n.List, obj.FmtComma))
		}

		return fmt.Sprintf("(%v{ %v })", n.Right, Hconv(n.List, obj.FmtComma))

	case OPTRLIT:
		if fmtmode == FExp && n.Left.Implicit {
			return Nconv(n.Left, 0)
		}
		return fmt.Sprintf("&%v", n.Left)

	case OSTRUCTLIT:
		if fmtmode == FExp { // requires special handling of field names
			var f string
			if n.Implicit {
				f += "{"
			} else {
				f += fmt.Sprintf("(%v{", n.Type)
			}
			for l := n.List; l != nil; l = l.Next {
				f += fmt.Sprintf(" %v:%v", Sconv(l.N.Left.Sym, obj.FmtShort|obj.FmtByte), l.N.Right)

				if l.Next != nil {
					f += ","
				} else {
					f += " "
				}
			}

			if !n.Implicit {
				f += "})"
				return f
			}
			f += "}"
			return f
		}
		fallthrough

	case OARRAYLIT, OMAPLIT:
		if fmtmode == FErr {
			return fmt.Sprintf("%v literal", n.Type)
		}
		if fmtmode == FExp && n.Implicit {
			return fmt.Sprintf("{ %v }", Hconv(n.List, obj.FmtComma))
		}
		return fmt.Sprintf("(%v{ %v })", n.Type, Hconv(n.List, obj.FmtComma))

	case OKEY:
		if n.Left != nil && n.Right != nil {
			if fmtmode == FExp && n.Left.Type != nil && n.Left.Type.Etype == TFIELD {
				// requires special handling of field names
				return fmt.Sprintf("%v:%v", Sconv(n.Left.Sym, obj.FmtShort|obj.FmtByte), n.Right)
			} else {
				return fmt.Sprintf("%v:%v", n.Left, n.Right)
			}
		}

		if n.Left == nil && n.Right != nil {
			return fmt.Sprintf(":%v", n.Right)
		}
		if n.Left != nil && n.Right == nil {
			return fmt.Sprintf("%v:", n.Left)
		}
		return ":"

	case OXDOT,
		ODOT,
		ODOTPTR,
		ODOTINTER,
		ODOTMETH,
		OCALLPART:
		var f string
		f += exprfmt(n.Left, nprec)
		if n.Right == nil || n.Right.Sym == nil {
			f += ".<nil>"
			return f
		}
		f += fmt.Sprintf(".%v", Sconv(n.Right.Sym, obj.FmtShort|obj.FmtByte))
		return f

	case ODOTTYPE, ODOTTYPE2:
		var f string
		f += exprfmt(n.Left, nprec)
		if n.Right != nil {
			f += fmt.Sprintf(".(%v)", n.Right)
			return f
		}
		f += fmt.Sprintf(".(%v)", n.Type)
		return f

	case OINDEX,
		OINDEXMAP,
		OSLICE,
		OSLICESTR,
		OSLICEARR,
		OSLICE3,
		OSLICE3ARR:
		var f string
		f += exprfmt(n.Left, nprec)
		f += fmt.Sprintf("[%v]", n.Right)
		return f

	case OCOPY, OCOMPLEX:
		return fmt.Sprintf("%v(%v, %v)", Oconv(int(n.Op), obj.FmtSharp), n.Left, n.Right)

	case OCONV,
		OCONVIFACE,
		OCONVNOP,
		OARRAYBYTESTR,
		OARRAYRUNESTR,
		OSTRARRAYBYTE,
		OSTRARRAYRUNE,
		ORUNESTR:
		if n.Type == nil || n.Type.Sym == nil {
			return fmt.Sprintf("(%v)(%v)", n.Type, n.Left)
		}
		if n.Left != nil {
			return fmt.Sprintf("%v(%v)", n.Type, n.Left)
		}
		return fmt.Sprintf("%v(%v)", n.Type, Hconv(n.List, obj.FmtComma))

	case OREAL,
		OIMAG,
		OAPPEND,
		OCAP,
		OCLOSE,
		ODELETE,
		OLEN,
		OMAKE,
		ONEW,
		OPANIC,
		ORECOVER,
		OPRINT,
		OPRINTN:
		if n.Left != nil {
			return fmt.Sprintf("%v(%v)", Oconv(int(n.Op), obj.FmtSharp), n.Left)
		}
		if n.Isddd {
			return fmt.Sprintf("%v(%v...)", Oconv(int(n.Op), obj.FmtSharp), Hconv(n.List, obj.FmtComma))
		}
		return fmt.Sprintf("%v(%v)", Oconv(int(n.Op), obj.FmtSharp), Hconv(n.List, obj.FmtComma))

	case OCALL, OCALLFUNC, OCALLINTER, OCALLMETH, OGETG:
		var f string
		f += exprfmt(n.Left, nprec)
		if n.Isddd {
			f += fmt.Sprintf("(%v...)", Hconv(n.List, obj.FmtComma))
			return f
		}
		f += fmt.Sprintf("(%v)", Hconv(n.List, obj.FmtComma))
		return f

	case OMAKEMAP, OMAKECHAN, OMAKESLICE:
		if n.List != nil { // pre-typecheck
			return fmt.Sprintf("make(%v, %v)", n.Type, Hconv(n.List, obj.FmtComma))
		}
		if n.Right != nil {
			return fmt.Sprintf("make(%v, %v, %v)", n.Type, n.Left, n.Right)
		}
		if n.Left != nil && (n.Op == OMAKESLICE || !isideal(n.Left.Type)) {
			return fmt.Sprintf("make(%v, %v)", n.Type, n.Left)
		}
		return fmt.Sprintf("make(%v)", n.Type)

		// Unary
	case OPLUS,
		OMINUS,
		OADDR,
		OCOM,
		OIND,
		ONOT,
		ORECV:
		var f string
		if n.Left.Op == n.Op {
			f += fmt.Sprintf("%v ", Oconv(int(n.Op), obj.FmtSharp))
		} else {
			f += Oconv(int(n.Op), obj.FmtSharp)
		}
		f += exprfmt(n.Left, nprec+1)
		return f

		// Binary
	case OADD,
		OAND,
		OANDAND,
		OANDNOT,
		ODIV,
		OEQ,
		OGE,
		OGT,
		OLE,
		OLT,
		OLSH,
		OMOD,
		OMUL,
		ONE,
		OOR,
		OOROR,
		ORSH,
		OSEND,
		OSUB,
		OXOR:
		var f string
		f += exprfmt(n.Left, nprec)

		f += fmt.Sprintf(" %v ", Oconv(int(n.Op), obj.FmtSharp))
		f += exprfmt(n.Right, nprec+1)
		return f

	case OADDSTR:
		var f string
		for l := n.List; l != nil; l = l.Next {
			if l != n.List {
				f += " + "
			}
			f += exprfmt(l.N, nprec)
		}

		return f

	case OCMPSTR, OCMPIFACE:
		var f string
		f += exprfmt(n.Left, nprec)
		f += fmt.Sprintf(" %v ", Oconv(int(n.Etype), obj.FmtSharp))
		f += exprfmt(n.Right, nprec+1)
		return f
	}

	return fmt.Sprintf("<node %v>", Oconv(int(n.Op), 0))
}