src/cmd/compile/internal/gc/gsubr.go - go - Git at Google

 // Derived from Inferno utils/6c/txt.c
 // http://code.google.com/p/inferno-os/source/browse/utils/6c/txt.c
 //
 //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
 //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
 //	Portions Copyright © 1997-1999 Vita Nuova Limited
 //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
 //	Portions Copyright © 2004,2006 Bruce Ellis
 //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
 //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
 //	Portions Copyright © 2009 The Go Authors.  All rights reserved.
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
 // in the Software without restriction, including without limitation the rights
 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 // copies of the Software, and to permit persons to whom the Software is
 // furnished to do so, subject to the following conditions:
 //
 // The above copyright notice and this permission notice shall be included in
 // all copies or substantial portions of the Software.
 //
 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.

 package gc

 import (
 	"cmd/internal/obj"
 	"fmt"
 	"runtime"
 	"strings"
 )

 var ddumped int

 var dfirst *obj.Prog

 var dpc *obj.Prog

 /*
  * Is this node a memory operand?
  */
 func Ismem(n *Node) bool {
 	switch n.Op {
 	case OITAB,
 		OSPTR,
 		OLEN,
 		OCAP,
 		OINDREG,
 		ONAME,
 		OPARAM,
 		OCLOSUREVAR:
 		return true

 	case OADDR:
 		return Thearch.Thechar == '6' || Thearch.Thechar == '9' // because 6g uses PC-relative addressing; TODO(rsc): not sure why 9g too
 	}

 	return false
 }

 func Samereg(a *Node, b *Node) bool {
 	if a == nil || b == nil {
 		return false
 	}
 	if a.Op != OREGISTER {
 		return false
 	}
 	if b.Op != OREGISTER {
 		return false
 	}
 	if a.Reg != b.Reg {
 		return false
 	}
 	return true
 }

 func Gbranch(as int, t *Type, likely int) *obj.Prog {
 	p := Prog(as)
 	p.To.Type = obj.TYPE_BRANCH
 	p.To.Val = nil
 	if as != obj.AJMP && likely != 0 && Thearch.Thechar != '9' && Thearch.Thechar != '7' {
 		p.From.Type = obj.TYPE_CONST
 		p.From.Offset = int64(obj.Bool2int(likely > 0))
 	}

 	if Debug['g'] != 0 {
 		fmt.Printf("%v\n", p)
 	}

 	return p
 }

 func Prog(as int) *obj.Prog {
 	var p *obj.Prog

 	if as == obj.ADATA || as == obj.AGLOBL {
 		if ddumped != 0 {
 			Fatalf("already dumped data")
 		}
 		if dpc == nil {
 			dpc = Ctxt.NewProg()
 			dfirst = dpc
 		}

 		p = dpc
 		dpc = Ctxt.NewProg()
 		p.Link = dpc
 	} else {
 		p = Pc
 		Pc = Ctxt.NewProg()
 		Clearp(Pc)
 		p.Link = Pc
 	}

 	if lineno == 0 {
 		if Debug['K'] != 0 {
 			Warn("prog: line 0")
 		}
 	}

 	p.As = int16(as)
 	p.Lineno = lineno
 	return p
 }

 func Nodreg(n *Node, t *Type, r int) {
 	if t == nil {
 		Fatalf("nodreg: t nil")
 	}

 	*n = Node{}
 	n.Op = OREGISTER
 	n.Addable = true
 	ullmancalc(n)
 	n.Reg = int16(r)
 	n.Type = t
 }

 func Nodindreg(n *Node, t *Type, r int) {
 	Nodreg(n, t, r)
 	n.Op = OINDREG
 }

 func Afunclit(a *obj.Addr, n *Node) {
 	if a.Type == obj.TYPE_ADDR && a.Name == obj.NAME_EXTERN {
 		a.Type = obj.TYPE_MEM
 		a.Sym = Linksym(n.Sym)
 	}
 }

 func Clearp(p *obj.Prog) {
 	obj.Nopout(p)
 	p.As = obj.AEND
 	p.Pc = int64(pcloc)
 	pcloc++
 }

 func dumpdata() {
 	ddumped = 1
 	if dfirst == nil {
 		return
 	}
 	newplist()
 	*Pc = *dfirst
 	Pc = dpc
 	Clearp(Pc)
 }

 // Fixup instructions after allocauto (formerly compactframe) has moved all autos around.
 func fixautoused(p *obj.Prog) {
 	for lp := &p; ; {
 		p = *lp
 		if p == nil {
 			break
 		}
 		if p.As == obj.ATYPE && p.From.Node != nil && p.From.Name == obj.NAME_AUTO && !((p.From.Node).(*Node)).Used {
 			*lp = p.Link
 			continue
 		}

 		if (p.As == obj.AVARDEF || p.As == obj.AVARKILL) && p.To.Node != nil && !((p.To.Node).(*Node)).Used {
 			// Cannot remove VARDEF instruction, because - unlike TYPE handled above -
 			// VARDEFs are interspersed with other code, and a jump might be using the
 			// VARDEF as a target. Replace with a no-op instead. A later pass will remove
 			// the no-ops.
 			obj.Nopout(p)

 			continue
 		}

 		if p.From.Name == obj.NAME_AUTO && p.From.Node != nil {
 			p.From.Offset += stkdelta[p.From.Node.(*Node)]
 		}

 		if p.To.Name == obj.NAME_AUTO && p.To.Node != nil {
 			p.To.Offset += stkdelta[p.To.Node.(*Node)]
 		}

 		lp = &p.Link
 	}
 }

 func ggloblnod(nam *Node) {
 	p := Thearch.Gins(obj.AGLOBL, nam, nil)
 	p.Lineno = nam.Lineno
 	p.From.Sym.Gotype = Linksym(ngotype(nam))
 	p.To.Sym = nil
 	p.To.Type = obj.TYPE_CONST
 	p.To.Offset = nam.Type.Width
 	p.From3 = new(obj.Addr)
 	if nam.Name.Readonly {
 		p.From3.Offset = obj.RODATA
 	}
 	if nam.Type != nil && !haspointers(nam.Type) {
 		p.From3.Offset |= obj.NOPTR
 	}
 }

 func ggloblsym(s *Sym, width int32, flags int16) {
 	p := Thearch.Gins(obj.AGLOBL, nil, nil)
 	p.From.Type = obj.TYPE_MEM
 	p.From.Name = obj.NAME_EXTERN
 	p.From.Sym = Linksym(s)
 	if flags&obj.LOCAL != 0 {
 		p.From.Sym.Local = true
 		flags &= ^obj.LOCAL
 	}
 	p.To.Type = obj.TYPE_CONST
 	p.To.Offset = int64(width)
 	p.From3 = new(obj.Addr)
 	p.From3.Offset = int64(flags)
 }

 func gjmp(to *obj.Prog) *obj.Prog {
 	p := Gbranch(obj.AJMP, nil, 0)
 	if to != nil {
 		Patch(p, to)
 	}
 	return p
 }

 func gtrack(s *Sym) {
 	p := Thearch.Gins(obj.AUSEFIELD, nil, nil)
 	p.From.Type = obj.TYPE_MEM
 	p.From.Name = obj.NAME_EXTERN
 	p.From.Sym = Linksym(s)
 }

 func gused(n *Node) {
 	Thearch.Gins(obj.ANOP, n, nil) // used
 }

 func Isfat(t *Type) bool {
 	if t != nil {
 		switch t.Etype {
 		case TSTRUCT, TARRAY, TSTRING,
 			TINTER: // maybe remove later
 			return true
 		}
 	}

 	return false
 }

 // Sweep the prog list to mark any used nodes.
 func markautoused(p *obj.Prog) {
 	for ; p != nil; p = p.Link {
 		if p.As == obj.ATYPE || p.As == obj.AVARDEF || p.As == obj.AVARKILL {
 			continue
 		}

 		if p.From.Node != nil {
 			((p.From.Node).(*Node)).Used = true
 		}

 		if p.To.Node != nil {
 			((p.To.Node).(*Node)).Used = true
 		}
 	}
 }

 // Naddr rewrites a to refer to n.
 // It assumes that a is zeroed on entry.
 func Naddr(a *obj.Addr, n *Node) {
 	if n == nil {
 		return
 	}

 	if n.Type != nil && n.Type.Etype != TIDEAL {
 		// TODO(rsc): This is undone by the selective clearing of width below,
 		// to match architectures that were not as aggressive in setting width
 		// during naddr. Those widths must be cleared to avoid triggering
 		// failures in gins when it detects real but heretofore latent (and one
 		// hopes innocuous) type mismatches.
 		// The type mismatches should be fixed and the clearing below removed.
 		dowidth(n.Type)

 		a.Width = n.Type.Width
 	}

 	switch n.Op {
 	default:
 		a := a // copy to let escape into Ctxt.Dconv
 		Debug['h'] = 1
 		Dump("naddr", n)
 		Fatalf("naddr: bad %v %v", Oconv(int(n.Op), 0), Ctxt.Dconv(a))

 	case OREGISTER:
 		a.Type = obj.TYPE_REG
 		a.Reg = n.Reg
 		a.Sym = nil
 		if Thearch.Thechar == '8' { // TODO(rsc): Never clear a->width.
 			a.Width = 0
 		}

 	case OINDREG:
 		a.Type = obj.TYPE_MEM
 		a.Reg = n.Reg
 		a.Sym = Linksym(n.Sym)
 		a.Offset = n.Xoffset
 		if a.Offset != int64(int32(a.Offset)) {
 			Yyerror("offset %d too large for OINDREG", a.Offset)
 		}
 		if Thearch.Thechar == '8' { // TODO(rsc): Never clear a->width.
 			a.Width = 0
 		}

 		// n->left is PHEAP ONAME for stack parameter.
 	// compute address of actual parameter on stack.
 	case OPARAM:
 		a.Etype = Simtype[n.Left.Type.Etype]

 		a.Width = n.Left.Type.Width
 		a.Offset = n.Xoffset
 		a.Sym = Linksym(n.Left.Sym)
 		a.Type = obj.TYPE_MEM
 		a.Name = obj.NAME_PARAM
 		a.Node = n.Left.Orig

 	case OCLOSUREVAR:
 		if !Curfn.Func.Needctxt {
 			Fatalf("closurevar without needctxt")
 		}
 		a.Type = obj.TYPE_MEM
 		a.Reg = int16(Thearch.REGCTXT)
 		a.Sym = nil
 		a.Offset = n.Xoffset

 	case OCFUNC:
 		Naddr(a, n.Left)
 		a.Sym = Linksym(n.Left.Sym)

 	case ONAME:
 		a.Etype = 0
 		if n.Type != nil {
 			a.Etype = Simtype[n.Type.Etype]
 		}
 		a.Offset = n.Xoffset
 		s := n.Sym
 		a.Node = n.Orig

 		//if(a->node >= (Node*)&n)
 		//	fatal("stack node");
 		if s == nil {
 			s = Lookup(".noname")
 		}
 		if n.Name.Method {
 			if n.Type != nil {
 				if n.Type.Sym != nil {
 					if n.Type.Sym.Pkg != nil {
 						s = Pkglookup(s.Name, n.Type.Sym.Pkg)
 					}
 				}
 			}
 		}

 		a.Type = obj.TYPE_MEM
 		switch n.Class {
 		default:
 			Fatalf("naddr: ONAME class %v %d\n", n.Sym, n.Class)

 		case PEXTERN:
 			a.Name = obj.NAME_EXTERN

 		case PAUTO:
 			a.Name = obj.NAME_AUTO

 		case PPARAM, PPARAMOUT:
 			a.Name = obj.NAME_PARAM

 		case PFUNC:
 			a.Name = obj.NAME_EXTERN
 			a.Type = obj.TYPE_ADDR
 			a.Width = int64(Widthptr)
 			s = funcsym(s)
 		}

 		a.Sym = Linksym(s)

 	case OLITERAL:
 		if Thearch.Thechar == '8' {
 			a.Width = 0
 		}
 		switch n.Val().Ctype() {
 		default:
 			Fatalf("naddr: const %v", Tconv(n.Type, obj.FmtLong))

 		case CTFLT:
 			a.Type = obj.TYPE_FCONST
 			a.Val = mpgetflt(n.Val().U.(*Mpflt))

 		case CTINT, CTRUNE:
 			a.Sym = nil
 			a.Type = obj.TYPE_CONST
 			a.Offset = Mpgetfix(n.Val().U.(*Mpint))

 		case CTSTR:
 			datagostring(n.Val().U.(string), a)

 		case CTBOOL:
 			a.Sym = nil
 			a.Type = obj.TYPE_CONST
 			a.Offset = int64(obj.Bool2int(n.Val().U.(bool)))

 		case CTNIL:
 			a.Sym = nil
 			a.Type = obj.TYPE_CONST
 			a.Offset = 0
 		}

 	case OADDR:
 		Naddr(a, n.Left)
 		a.Etype = uint8(Tptr)
 		if Thearch.Thechar != '5' && Thearch.Thechar != '7' && Thearch.Thechar != '9' { // TODO(rsc): Do this even for arm, ppc64.
 			a.Width = int64(Widthptr)
 		}
 		if a.Type != obj.TYPE_MEM {
 			a := a // copy to let escape into Ctxt.Dconv
 			Fatalf("naddr: OADDR %v (from %v)", Ctxt.Dconv(a), Oconv(int(n.Left.Op), 0))
 		}
 		a.Type = obj.TYPE_ADDR

 		// itable of interface value
 	case OITAB:
 		Naddr(a, n.Left)

 		if a.Type == obj.TYPE_CONST && a.Offset == 0 {
 			break // itab(nil)
 		}
 		a.Etype = uint8(Tptr)
 		a.Width = int64(Widthptr)

 		// pointer in a string or slice
 	case OSPTR:
 		Naddr(a, n.Left)

 		if a.Type == obj.TYPE_CONST && a.Offset == 0 {
 			break // ptr(nil)
 		}
 		a.Etype = Simtype[Tptr]
 		a.Offset += int64(Array_array)
 		a.Width = int64(Widthptr)

 		// len of string or slice
 	case OLEN:
 		Naddr(a, n.Left)

 		if a.Type == obj.TYPE_CONST && a.Offset == 0 {
 			break // len(nil)
 		}
 		a.Etype = Simtype[TUINT]
 		a.Offset += int64(Array_nel)
 		if Thearch.Thechar != '5' { // TODO(rsc): Do this even on arm.
 			a.Width = int64(Widthint)
 		}

 		// cap of string or slice
 	case OCAP:
 		Naddr(a, n.Left)

 		if a.Type == obj.TYPE_CONST && a.Offset == 0 {
 			break // cap(nil)
 		}
 		a.Etype = Simtype[TUINT]
 		a.Offset += int64(Array_cap)
 		if Thearch.Thechar != '5' { // TODO(rsc): Do this even on arm.
 			a.Width = int64(Widthint)
 		}
 	}
 	return
 }

 func newplist() *obj.Plist {
 	pl := obj.Linknewplist(Ctxt)

 	Pc = Ctxt.NewProg()
 	Clearp(Pc)
 	pl.Firstpc = Pc

 	return pl
 }

 func nodarg(t *Type, fp int) *Node {
 	var n *Node

 	// entire argument struct, not just one arg
 	if t.Etype == TSTRUCT && t.Funarg {
 		n = Nod(ONAME, nil, nil)
 		n.Sym = Lookup(".args")
 		n.Type = t
 		var savet Iter
 		first := Structfirst(&savet, &t)
 		if first == nil {
 			Fatalf("nodarg: bad struct")
 		}
 		if first.Width == BADWIDTH {
 			Fatalf("nodarg: offset not computed for %v", t)
 		}
 		n.Xoffset = first.Width
 		n.Addable = true
 		goto fp
 	}

 	if t.Etype != TFIELD {
 		Fatalf("nodarg: not field %v", t)
 	}

 	if fp == 1 {
 		var n *Node
 		for l := Curfn.Func.Dcl; l != nil; l = l.Next {
 			n = l.N
 			if (n.Class == PPARAM || n.Class == PPARAMOUT) && !isblanksym(t.Sym) && n.Sym == t.Sym {
 				return n
 			}
 		}
 	}

 	n = Nod(ONAME, nil, nil)
 	n.Type = t.Type
 	n.Sym = t.Sym

 	if t.Width == BADWIDTH {
 		Fatalf("nodarg: offset not computed for %v", t)
 	}
 	n.Xoffset = t.Width
 	n.Addable = true
 	n.Orig = t.Nname

 	// Rewrite argument named _ to __,
 	// or else the assignment to _ will be
 	// discarded during code generation.
 fp:
 	if isblank(n) {
 		n.Sym = Lookup("__")
 	}

 	switch fp {
 	case 0: // output arg
 		n.Op = OINDREG

 		n.Reg = int16(Thearch.REGSP)
 		if HasLinkRegister() {
 			n.Xoffset += int64(Ctxt.Arch.Ptrsize)
 		}

 	case 1: // input arg
 		n.Class = PPARAM

 	case 2: // offset output arg
 		Fatalf("shouldn't be used")
 	}

 	n.Typecheck = 1
 	return n
 }

 func Patch(p *obj.Prog, to *obj.Prog) {
 	if p.To.Type != obj.TYPE_BRANCH {
 		Fatalf("patch: not a branch")
 	}
 	p.To.Val = to
 	p.To.Offset = to.Pc
 }

 func unpatch(p *obj.Prog) *obj.Prog {
 	if p.To.Type != obj.TYPE_BRANCH {
 		Fatalf("unpatch: not a branch")
 	}
 	q, _ := p.To.Val.(*obj.Prog)
 	p.To.Val = nil
 	p.To.Offset = 0
 	return q
 }

 var reg [100]int       // count of references to reg
 var regstk [100][]byte // allocation sites, when -v is given

 func GetReg(r int) int {
 	return reg[r-Thearch.REGMIN]
 }
 func SetReg(r, v int) {
 	reg[r-Thearch.REGMIN] = v
 }

 func ginit() {
 	for r := range reg {
 		reg[r] = 1
 	}

 	for r := Thearch.REGMIN; r <= Thearch.REGMAX; r++ {
 		reg[r-Thearch.REGMIN] = 0
 	}
 	for r := Thearch.FREGMIN; r <= Thearch.FREGMAX; r++ {
 		reg[r-Thearch.REGMIN] = 0
 	}

 	for _, r := range Thearch.ReservedRegs {
 		reg[r-Thearch.REGMIN] = 1
 	}
 }

 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 {
 			if Debug['v'] != 0 {
 				Regdump()
 			}
 			Yyerror("reg %v left allocated", obj.Rconv(r))
 		}
 	}

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

 func Anyregalloc() bool {
 	n := 0
 	for r := Thearch.REGMIN; r <= Thearch.REGMAX; r++ {
 		if reg[r-Thearch.REGMIN] == 0 {
 			n++
 		}
 	}
 	return n > len(Thearch.ReservedRegs)
 }

 /*
  * allocate register of type t, leave in n.
  * if o != N, o may be reusable register.
  * caller must Regfree(n).
  */
 func Regalloc(n *Node, t *Type, o *Node) {
 	if t == nil {
 		Fatalf("regalloc: t nil")
 	}
 	et := int(Simtype[t.Etype])
 	if Ctxt.Arch.Regsize == 4 && (et == TINT64 || et == TUINT64) {
 		Fatalf("regalloc 64bit")
 	}

 	var i int
 Switch:
 	switch et {
 	default:
 		Fatalf("regalloc: unknown type %v", t)

 	case TINT8, TUINT8, TINT16, TUINT16, TINT32, TUINT32, TINT64, TUINT64, TPTR32, TPTR64, TBOOL:
 		if o != nil && o.Op == OREGISTER {
 			i = int(o.Reg)
 			if Thearch.REGMIN <= i && i <= Thearch.REGMAX {
 				break Switch
 			}
 		}
 		for i = Thearch.REGMIN; i <= Thearch.REGMAX; i++ {
 			if reg[i-Thearch.REGMIN] == 0 {
 				break Switch
 			}
 		}
 		Flusherrors()
 		Regdump()
 		Fatalf("out of fixed registers")

 	case TFLOAT32, TFLOAT64:
 		if Thearch.Use387 {
 			i = Thearch.FREGMIN // x86.REG_F0
 			break Switch
 		}
 		if o != nil && o.Op == OREGISTER {
 			i = int(o.Reg)
 			if Thearch.FREGMIN <= i && i <= Thearch.FREGMAX {
 				break Switch
 			}
 		}
 		for i = Thearch.FREGMIN; i <= Thearch.FREGMAX; i++ {
 			if reg[i-Thearch.REGMIN] == 0 { // note: REGMIN, not FREGMIN
 				break Switch
 			}
 		}
 		Flusherrors()
 		Regdump()
 		Fatalf("out of floating registers")

 	case TCOMPLEX64, TCOMPLEX128:
 		Tempname(n, t)
 		return
 	}

 	ix := i - Thearch.REGMIN
 	if reg[ix] == 0 && Debug['v'] > 0 {
 		if regstk[ix] == nil {
 			regstk[ix] = make([]byte, 4096)
 		}
 		stk := regstk[ix]
 		n := runtime.Stack(stk[:cap(stk)], false)
 		regstk[ix] = stk[:n]
 	}
 	reg[ix]++
 	Nodreg(n, t, i)
 }

 func Regfree(n *Node) {
 	if n.Op == ONAME {
 		return
 	}
 	if n.Op != OREGISTER && n.Op != OINDREG {
 		Fatalf("regfree: not a register")
 	}
 	i := int(n.Reg)
 	if i == Thearch.REGSP {
 		return
 	}
 	switch {
 	case Thearch.REGMIN <= i && i <= Thearch.REGMAX,
 		Thearch.FREGMIN <= i && i <= Thearch.FREGMAX:
 		// ok
 	default:
 		Fatalf("regfree: reg out of range")
 	}

 	i -= Thearch.REGMIN
 	if reg[i] <= 0 {
 		Fatalf("regfree: reg not allocated")
 	}
 	reg[i]--
 	if reg[i] == 0 {
 		regstk[i] = regstk[i][:0]
 	}
 }

 // Reginuse reports whether r is in use.
 func Reginuse(r int) bool {
 	switch {
 	case Thearch.REGMIN <= r && r <= Thearch.REGMAX,
 		Thearch.FREGMIN <= r && r <= Thearch.FREGMAX:
 		// ok
 	default:
 		Fatalf("reginuse: reg out of range")
 	}

 	return reg[r-Thearch.REGMIN] > 0
 }

 // Regrealloc(n) undoes the effect of Regfree(n),
 // so that a register can be given up but then reclaimed.
 func Regrealloc(n *Node) {
 	if n.Op != OREGISTER && n.Op != OINDREG {
 		Fatalf("regrealloc: not a register")
 	}
 	i := int(n.Reg)
 	if i == Thearch.REGSP {
 		return
 	}
 	switch {
 	case Thearch.REGMIN <= i && i <= Thearch.REGMAX,
 		Thearch.FREGMIN <= i && i <= Thearch.FREGMAX:
 		// ok
 	default:
 		Fatalf("regrealloc: reg out of range")
 	}

 	i -= Thearch.REGMIN
 	if reg[i] == 0 && Debug['v'] > 0 {
 		if regstk[i] == nil {
 			regstk[i] = make([]byte, 4096)
 		}
 		stk := regstk[i]
 		n := runtime.Stack(stk[:cap(stk)], false)
 		regstk[i] = stk[:n]
 	}
 	reg[i]++
 }

 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)
 		}
 	}
 }
	// Derived from Inferno utils/6c/txt.c
	// http://code.google.com/p/inferno-os/source/browse/utils/6c/txt.c
	//
	// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
	// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
	// Portions Copyright © 1997-1999 Vita Nuova Limited
	// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
	// Portions Copyright © 2004,2006 Bruce Ellis
	// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
	// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
	// Portions Copyright © 2009 The Go Authors. All rights reserved.
	//
	// Permission is hereby granted, free of charge, to any person obtaining a copy
	// of this software and associated documentation files (the "Software"), to deal
	// in the Software without restriction, including without limitation the rights
	// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	// copies of the Software, and to permit persons to whom the Software is
	// furnished to do so, subject to the following conditions:
	//
	// The above copyright notice and this permission notice shall be included in
	// all copies or substantial portions of the Software.
	//
	// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	// THE SOFTWARE.

	package gc

	import (
	"cmd/internal/obj"
	"fmt"
	"runtime"
	"strings"
	)

	var ddumped int

	var dfirst *obj.Prog

	var dpc *obj.Prog

	/*
	* Is this node a memory operand?
	*/
	func Ismem(n *Node) bool {
	switch n.Op {
	case OITAB,
	OSPTR,
	OLEN,
	OCAP,
	OINDREG,
	ONAME,
	OPARAM,
	OCLOSUREVAR:
	return true

	case OADDR:
	return Thearch.Thechar == '6' \|\| Thearch.Thechar == '9' // because 6g uses PC-relative addressing; TODO(rsc): not sure why 9g too
	}

	return false
	}

	func Samereg(a Node, b Node) bool {
	if a == nil \|\| b == nil {
	return false
	}
	if a.Op != OREGISTER {
	return false
	}
	if b.Op != OREGISTER {
	return false
	}
	if a.Reg != b.Reg {
	return false
	}
	return true
	}

	func Gbranch(as int, t Type, likely int) obj.Prog {
	p := Prog(as)
	p.To.Type = obj.TYPE_BRANCH
	p.To.Val = nil
	if as != obj.AJMP && likely != 0 && Thearch.Thechar != '9' && Thearch.Thechar != '7' {
	p.From.Type = obj.TYPE_CONST
	p.From.Offset = int64(obj.Bool2int(likely > 0))
	}

	if Debug['g'] != 0 {
	fmt.Printf("%v\n", p)
	}

	return p
	}

	func Prog(as int) *obj.Prog {
	var p *obj.Prog

	if as == obj.ADATA \|\| as == obj.AGLOBL {
	if ddumped != 0 {
	Fatalf("already dumped data")
	}
	if dpc == nil {
	dpc = Ctxt.NewProg()
	dfirst = dpc
	}

	p = dpc
	dpc = Ctxt.NewProg()
	p.Link = dpc
	} else {
	p = Pc
	Pc = Ctxt.NewProg()
	Clearp(Pc)
	p.Link = Pc
	}

	if lineno == 0 {
	if Debug['K'] != 0 {
	Warn("prog: line 0")
	}
	}

	p.As = int16(as)
	p.Lineno = lineno
	return p
	}

	func Nodreg(n Node, t Type, r int) {
	if t == nil {
	Fatalf("nodreg: t nil")
	}

	*n = Node{}
	n.Op = OREGISTER
	n.Addable = true
	ullmancalc(n)
	n.Reg = int16(r)
	n.Type = t
	}

	func Nodindreg(n Node, t Type, r int) {
	Nodreg(n, t, r)
	n.Op = OINDREG
	}

	func Afunclit(a obj.Addr, n Node) {
	if a.Type == obj.TYPE_ADDR && a.Name == obj.NAME_EXTERN {
	a.Type = obj.TYPE_MEM
	a.Sym = Linksym(n.Sym)
	}
	}

	func Clearp(p *obj.Prog) {
	obj.Nopout(p)
	p.As = obj.AEND
	p.Pc = int64(pcloc)
	pcloc++
	}

	func dumpdata() {
	ddumped = 1
	if dfirst == nil {
	return
	}
	newplist()
	Pc = dfirst
	Pc = dpc
	Clearp(Pc)
	}

	// Fixup instructions after allocauto (formerly compactframe) has moved all autos around.
	func fixautoused(p *obj.Prog) {
	for lp := &p; ; {
	p = *lp
	if p == nil {
	break
	}
	if p.As == obj.ATYPE && p.From.Node != nil && p.From.Name == obj.NAME_AUTO && !((p.From.Node).(*Node)).Used {
	*lp = p.Link
	continue
	}

	if (p.As == obj.AVARDEF \|\| p.As == obj.AVARKILL) && p.To.Node != nil && !((p.To.Node).(*Node)).Used {
	// Cannot remove VARDEF instruction, because - unlike TYPE handled above -
	// VARDEFs are interspersed with other code, and a jump might be using the
	// VARDEF as a target. Replace with a no-op instead. A later pass will remove
	// the no-ops.
	obj.Nopout(p)

	continue
	}

	if p.From.Name == obj.NAME_AUTO && p.From.Node != nil {
	p.From.Offset += stkdelta[p.From.Node.(*Node)]
	}

	if p.To.Name == obj.NAME_AUTO && p.To.Node != nil {
	p.To.Offset += stkdelta[p.To.Node.(*Node)]
	}

	lp = &p.Link
	}
	}

	func ggloblnod(nam *Node) {
	p := Thearch.Gins(obj.AGLOBL, nam, nil)
	p.Lineno = nam.Lineno
	p.From.Sym.Gotype = Linksym(ngotype(nam))
	p.To.Sym = nil
	p.To.Type = obj.TYPE_CONST
	p.To.Offset = nam.Type.Width
	p.From3 = new(obj.Addr)
	if nam.Name.Readonly {
	p.From3.Offset = obj.RODATA
	}
	if nam.Type != nil && !haspointers(nam.Type) {
	p.From3.Offset \|= obj.NOPTR
	}
	}

	func ggloblsym(s *Sym, width int32, flags int16) {
	p := Thearch.Gins(obj.AGLOBL, nil, nil)
	p.From.Type = obj.TYPE_MEM
	p.From.Name = obj.NAME_EXTERN
	p.From.Sym = Linksym(s)
	if flags&obj.LOCAL != 0 {
	p.From.Sym.Local = true
	flags &= ^obj.LOCAL
	}
	p.To.Type = obj.TYPE_CONST
	p.To.Offset = int64(width)
	p.From3 = new(obj.Addr)
	p.From3.Offset = int64(flags)
	}

	func gjmp(to obj.Prog) obj.Prog {
	p := Gbranch(obj.AJMP, nil, 0)
	if to != nil {
	Patch(p, to)
	}
	return p
	}

	func gtrack(s *Sym) {
	p := Thearch.Gins(obj.AUSEFIELD, nil, nil)
	p.From.Type = obj.TYPE_MEM
	p.From.Name = obj.NAME_EXTERN
	p.From.Sym = Linksym(s)
	}

	func gused(n *Node) {
	Thearch.Gins(obj.ANOP, n, nil) // used
	}

	func Isfat(t *Type) bool {
	if t != nil {
	switch t.Etype {
	case TSTRUCT, TARRAY, TSTRING,
	TINTER: // maybe remove later
	return true
	}
	}

	return false
	}

	// Sweep the prog list to mark any used nodes.
	func markautoused(p *obj.Prog) {
	for ; p != nil; p = p.Link {
	if p.As == obj.ATYPE \|\| p.As == obj.AVARDEF \|\| p.As == obj.AVARKILL {
	continue
	}

	if p.From.Node != nil {
	((p.From.Node).(*Node)).Used = true
	}

	if p.To.Node != nil {
	((p.To.Node).(*Node)).Used = true
	}
	}
	}

	// Naddr rewrites a to refer to n.
	// It assumes that a is zeroed on entry.
	func Naddr(a obj.Addr, n Node) {
	if n == nil {
	return
	}

	if n.Type != nil && n.Type.Etype != TIDEAL {
	// TODO(rsc): This is undone by the selective clearing of width below,
	// to match architectures that were not as aggressive in setting width
	// during naddr. Those widths must be cleared to avoid triggering
	// failures in gins when it detects real but heretofore latent (and one
	// hopes innocuous) type mismatches.
	// The type mismatches should be fixed and the clearing below removed.
	dowidth(n.Type)

	a.Width = n.Type.Width
	}

	switch n.Op {
	default:
	a := a // copy to let escape into Ctxt.Dconv
	Debug['h'] = 1
	Dump("naddr", n)
	Fatalf("naddr: bad %v %v", Oconv(int(n.Op), 0), Ctxt.Dconv(a))

	case OREGISTER:
	a.Type = obj.TYPE_REG
	a.Reg = n.Reg
	a.Sym = nil
	if Thearch.Thechar == '8' { // TODO(rsc): Never clear a->width.
	a.Width = 0
	}

	case OINDREG:
	a.Type = obj.TYPE_MEM
	a.Reg = n.Reg
	a.Sym = Linksym(n.Sym)
	a.Offset = n.Xoffset
	if a.Offset != int64(int32(a.Offset)) {
	Yyerror("offset %d too large for OINDREG", a.Offset)
	}
	if Thearch.Thechar == '8' { // TODO(rsc): Never clear a->width.
	a.Width = 0
	}

	// n->left is PHEAP ONAME for stack parameter.
	// compute address of actual parameter on stack.
	case OPARAM:
	a.Etype = Simtype[n.Left.Type.Etype]

	a.Width = n.Left.Type.Width
	a.Offset = n.Xoffset
	a.Sym = Linksym(n.Left.Sym)
	a.Type = obj.TYPE_MEM
	a.Name = obj.NAME_PARAM
	a.Node = n.Left.Orig

	case OCLOSUREVAR:
	if !Curfn.Func.Needctxt {
	Fatalf("closurevar without needctxt")
	}
	a.Type = obj.TYPE_MEM
	a.Reg = int16(Thearch.REGCTXT)
	a.Sym = nil
	a.Offset = n.Xoffset

	case OCFUNC:
	Naddr(a, n.Left)
	a.Sym = Linksym(n.Left.Sym)

	case ONAME:
	a.Etype = 0
	if n.Type != nil {
	a.Etype = Simtype[n.Type.Etype]
	}
	a.Offset = n.Xoffset
	s := n.Sym
	a.Node = n.Orig

	//if(a->node >= (Node*)&n)
	// fatal("stack node");
	if s == nil {
	s = Lookup(".noname")
	}
	if n.Name.Method {
	if n.Type != nil {
	if n.Type.Sym != nil {
	if n.Type.Sym.Pkg != nil {
	s = Pkglookup(s.Name, n.Type.Sym.Pkg)
	}
	}
	}
	}

	a.Type = obj.TYPE_MEM
	switch n.Class {
	default:
	Fatalf("naddr: ONAME class %v %d\n", n.Sym, n.Class)

	case PEXTERN:
	a.Name = obj.NAME_EXTERN

	case PAUTO:
	a.Name = obj.NAME_AUTO

	case PPARAM, PPARAMOUT:
	a.Name = obj.NAME_PARAM

	case PFUNC:
	a.Name = obj.NAME_EXTERN
	a.Type = obj.TYPE_ADDR
	a.Width = int64(Widthptr)
	s = funcsym(s)
	}

	a.Sym = Linksym(s)

	case OLITERAL:
	if Thearch.Thechar == '8' {
	a.Width = 0
	}
	switch n.Val().Ctype() {
	default:
	Fatalf("naddr: const %v", Tconv(n.Type, obj.FmtLong))

	case CTFLT:
	a.Type = obj.TYPE_FCONST
	a.Val = mpgetflt(n.Val().U.(*Mpflt))

	case CTINT, CTRUNE:
	a.Sym = nil
	a.Type = obj.TYPE_CONST
	a.Offset = Mpgetfix(n.Val().U.(*Mpint))

	case CTSTR:
	datagostring(n.Val().U.(string), a)

	case CTBOOL:
	a.Sym = nil
	a.Type = obj.TYPE_CONST
	a.Offset = int64(obj.Bool2int(n.Val().U.(bool)))

	case CTNIL:
	a.Sym = nil
	a.Type = obj.TYPE_CONST
	a.Offset = 0
	}

	case OADDR:
	Naddr(a, n.Left)
	a.Etype = uint8(Tptr)
	if Thearch.Thechar != '5' && Thearch.Thechar != '7' && Thearch.Thechar != '9' { // TODO(rsc): Do this even for arm, ppc64.
	a.Width = int64(Widthptr)
	}
	if a.Type != obj.TYPE_MEM {
	a := a // copy to let escape into Ctxt.Dconv
	Fatalf("naddr: OADDR %v (from %v)", Ctxt.Dconv(a), Oconv(int(n.Left.Op), 0))
	}
	a.Type = obj.TYPE_ADDR

	// itable of interface value
	case OITAB:
	Naddr(a, n.Left)

	if a.Type == obj.TYPE_CONST && a.Offset == 0 {
	break // itab(nil)
	}
	a.Etype = uint8(Tptr)
	a.Width = int64(Widthptr)

	// pointer in a string or slice
	case OSPTR:
	Naddr(a, n.Left)

	if a.Type == obj.TYPE_CONST && a.Offset == 0 {
	break // ptr(nil)
	}
	a.Etype = Simtype[Tptr]
	a.Offset += int64(Array_array)
	a.Width = int64(Widthptr)

	// len of string or slice
	case OLEN:
	Naddr(a, n.Left)

	if a.Type == obj.TYPE_CONST && a.Offset == 0 {
	break // len(nil)
	}
	a.Etype = Simtype[TUINT]
	a.Offset += int64(Array_nel)
	if Thearch.Thechar != '5' { // TODO(rsc): Do this even on arm.
	a.Width = int64(Widthint)
	}

	// cap of string or slice
	case OCAP:
	Naddr(a, n.Left)

	if a.Type == obj.TYPE_CONST && a.Offset == 0 {
	break // cap(nil)
	}
	a.Etype = Simtype[TUINT]
	a.Offset += int64(Array_cap)
	if Thearch.Thechar != '5' { // TODO(rsc): Do this even on arm.
	a.Width = int64(Widthint)
	}
	}
	return
	}

	func newplist() *obj.Plist {
	pl := obj.Linknewplist(Ctxt)

	Pc = Ctxt.NewProg()
	Clearp(Pc)
	pl.Firstpc = Pc

	return pl
	}

	func nodarg(t Type, fp int) Node {
	var n *Node

	// entire argument struct, not just one arg
	if t.Etype == TSTRUCT && t.Funarg {
	n = Nod(ONAME, nil, nil)
	n.Sym = Lookup(".args")
	n.Type = t
	var savet Iter
	first := Structfirst(&savet, &t)
	if first == nil {
	Fatalf("nodarg: bad struct")
	}
	if first.Width == BADWIDTH {
	Fatalf("nodarg: offset not computed for %v", t)
	}
	n.Xoffset = first.Width
	n.Addable = true
	goto fp
	}

	if t.Etype != TFIELD {
	Fatalf("nodarg: not field %v", t)
	}

	if fp == 1 {
	var n *Node
	for l := Curfn.Func.Dcl; l != nil; l = l.Next {
	n = l.N
	if (n.Class == PPARAM \|\| n.Class == PPARAMOUT) && !isblanksym(t.Sym) && n.Sym == t.Sym {
	return n
	}
	}
	}

	n = Nod(ONAME, nil, nil)
	n.Type = t.Type
	n.Sym = t.Sym

	if t.Width == BADWIDTH {
	Fatalf("nodarg: offset not computed for %v", t)
	}
	n.Xoffset = t.Width
	n.Addable = true
	n.Orig = t.Nname

	// Rewrite argument named _ to __,
	// or else the assignment to _ will be
	// discarded during code generation.
	fp:
	if isblank(n) {
	n.Sym = Lookup("__")
	}

	switch fp {
	case 0: // output arg
	n.Op = OINDREG

	n.Reg = int16(Thearch.REGSP)
	if HasLinkRegister() {
	n.Xoffset += int64(Ctxt.Arch.Ptrsize)
	}

	case 1: // input arg
	n.Class = PPARAM

	case 2: // offset output arg
	Fatalf("shouldn't be used")
	}

	n.Typecheck = 1
	return n
	}

	func Patch(p obj.Prog, to obj.Prog) {
	if p.To.Type != obj.TYPE_BRANCH {
	Fatalf("patch: not a branch")
	}
	p.To.Val = to
	p.To.Offset = to.Pc
	}

	func unpatch(p obj.Prog) obj.Prog {
	if p.To.Type != obj.TYPE_BRANCH {
	Fatalf("unpatch: not a branch")
	}
	q, _ := p.To.Val.(*obj.Prog)
	p.To.Val = nil
	p.To.Offset = 0
	return q
	}

	var reg [100]int // count of references to reg
	var regstk [100][]byte // allocation sites, when -v is given

	func GetReg(r int) int {
	return reg[r-Thearch.REGMIN]
	}
	func SetReg(r, v int) {
	reg[r-Thearch.REGMIN] = v
	}

	func ginit() {
	for r := range reg {
	reg[r] = 1
	}

	for r := Thearch.REGMIN; r <= Thearch.REGMAX; r++ {
	reg[r-Thearch.REGMIN] = 0
	}
	for r := Thearch.FREGMIN; r <= Thearch.FREGMAX; r++ {
	reg[r-Thearch.REGMIN] = 0
	}

	for _, r := range Thearch.ReservedRegs {
	reg[r-Thearch.REGMIN] = 1
	}
	}

	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 {
	if Debug['v'] != 0 {
	Regdump()
	}
	Yyerror("reg %v left allocated", obj.Rconv(r))
	}
	}

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

	func Anyregalloc() bool {
	n := 0
	for r := Thearch.REGMIN; r <= Thearch.REGMAX; r++ {
	if reg[r-Thearch.REGMIN] == 0 {
	n++
	}
	}
	return n > len(Thearch.ReservedRegs)
	}

	/*
	* allocate register of type t, leave in n.
	* if o != N, o may be reusable register.
	* caller must Regfree(n).
	*/
	func Regalloc(n Node, t Type, o *Node) {
	if t == nil {
	Fatalf("regalloc: t nil")
	}
	et := int(Simtype[t.Etype])
	if Ctxt.Arch.Regsize == 4 && (et == TINT64 \|\| et == TUINT64) {
	Fatalf("regalloc 64bit")
	}

	var i int
	Switch:
	switch et {
	default:
	Fatalf("regalloc: unknown type %v", t)

	case TINT8, TUINT8, TINT16, TUINT16, TINT32, TUINT32, TINT64, TUINT64, TPTR32, TPTR64, TBOOL:
	if o != nil && o.Op == OREGISTER {
	i = int(o.Reg)
	if Thearch.REGMIN <= i && i <= Thearch.REGMAX {
	break Switch
	}
	}
	for i = Thearch.REGMIN; i <= Thearch.REGMAX; i++ {
	if reg[i-Thearch.REGMIN] == 0 {
	break Switch
	}
	}
	Flusherrors()
	Regdump()
	Fatalf("out of fixed registers")

	case TFLOAT32, TFLOAT64:
	if Thearch.Use387 {
	i = Thearch.FREGMIN // x86.REG_F0
	break Switch
	}
	if o != nil && o.Op == OREGISTER {
	i = int(o.Reg)
	if Thearch.FREGMIN <= i && i <= Thearch.FREGMAX {
	break Switch
	}
	}
	for i = Thearch.FREGMIN; i <= Thearch.FREGMAX; i++ {
	if reg[i-Thearch.REGMIN] == 0 { // note: REGMIN, not FREGMIN
	break Switch
	}
	}
	Flusherrors()
	Regdump()
	Fatalf("out of floating registers")

	case TCOMPLEX64, TCOMPLEX128:
	Tempname(n, t)
	return
	}

	ix := i - Thearch.REGMIN
	if reg[ix] == 0 && Debug['v'] > 0 {
	if regstk[ix] == nil {
	regstk[ix] = make([]byte, 4096)
	}
	stk := regstk[ix]
	n := runtime.Stack(stk[:cap(stk)], false)
	regstk[ix] = stk[:n]
	}
	reg[ix]++
	Nodreg(n, t, i)
	}

	func Regfree(n *Node) {
	if n.Op == ONAME {
	return
	}
	if n.Op != OREGISTER && n.Op != OINDREG {
	Fatalf("regfree: not a register")
	}
	i := int(n.Reg)
	if i == Thearch.REGSP {
	return
	}
	switch {
	case Thearch.REGMIN <= i && i <= Thearch.REGMAX,
	Thearch.FREGMIN <= i && i <= Thearch.FREGMAX:
	// ok
	default:
	Fatalf("regfree: reg out of range")
	}

	i -= Thearch.REGMIN
	if reg[i] <= 0 {
	Fatalf("regfree: reg not allocated")
	}
	reg[i]--
	if reg[i] == 0 {
	regstk[i] = regstk[i][:0]
	}
	}

	// Reginuse reports whether r is in use.
	func Reginuse(r int) bool {
	switch {
	case Thearch.REGMIN <= r && r <= Thearch.REGMAX,
	Thearch.FREGMIN <= r && r <= Thearch.FREGMAX:
	// ok
	default:
	Fatalf("reginuse: reg out of range")
	}

	return reg[r-Thearch.REGMIN] > 0
	}

	// Regrealloc(n) undoes the effect of Regfree(n),
	// so that a register can be given up but then reclaimed.
	func Regrealloc(n *Node) {
	if n.Op != OREGISTER && n.Op != OINDREG {
	Fatalf("regrealloc: not a register")
	}
	i := int(n.Reg)
	if i == Thearch.REGSP {
	return
	}
	switch {
	case Thearch.REGMIN <= i && i <= Thearch.REGMAX,
	Thearch.FREGMIN <= i && i <= Thearch.FREGMAX:
	// ok
	default:
	Fatalf("regrealloc: reg out of range")
	}

	i -= Thearch.REGMIN
	if reg[i] == 0 && Debug['v'] > 0 {
	if regstk[i] == nil {
	regstk[i] = make([]byte, 4096)
	}
	stk := regstk[i]
	n := runtime.Stack(stk[:cap(stk)], false)
	regstk[i] = stk[:n]
	}
	reg[i]++
	}

	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)
	}
	}
	}