Golang gc.Node類代碼示例

func ginscmp(op gc.Op, t *gc.Type, n1, n2 *gc.Node, likely int) *obj.Prog {
	if gc.Isint[t.Etype] && n1.Op == gc.OLITERAL && n2.Op != gc.OLITERAL {
		// Reverse comparison to place constant last.
		op = gc.Brrev(op)
		n1, n2 = n2, n1
	}

	var r1, r2, g1, g2 gc.Node
	gc.Regalloc(&r1, t, n1)
	gc.Regalloc(&g1, n1.Type, &r1)
	gc.Cgen(n1, &g1)
	gmove(&g1, &r1)
	if gc.Isint[t.Etype] && gc.Isconst(n2, gc.CTINT) {
		ginscon2(optoas(gc.OCMP, t), &r1, n2.Int())
	} else {
		gc.Regalloc(&r2, t, n2)
		gc.Regalloc(&g2, n1.Type, &r2)
		gc.Cgen(n2, &g2)
		gmove(&g2, &r2)
		rawgins(optoas(gc.OCMP, t), &r1, &r2)
		gc.Regfree(&g2)
		gc.Regfree(&r2)
	}
	gc.Regfree(&g1)
	gc.Regfree(&r1)
	return gc.Gbranch(optoas(op, t), nil, likely)
}

func ginscmp(op gc.Op, t *gc.Type, n1, n2 *gc.Node, likely int) *obj.Prog {
	if gc.Isint[t.Etype] && n1.Op == gc.OLITERAL && n1.Int() == 0 && n2.Op != gc.OLITERAL {
		op = gc.Brrev(op)
		n1, n2 = n2, n1
	}
	var r1, r2, g1, g2 gc.Node
	gc.Regalloc(&r1, t, n1)
	gc.Regalloc(&g1, n1.Type, &r1)
	gc.Cgen(n1, &g1)
	gmove(&g1, &r1)
	if gc.Isint[t.Etype] && n2.Op == gc.OLITERAL && n2.Int() == 0 {
		gins(arm.ACMP, &r1, n2)
	} else {
		gc.Regalloc(&r2, t, n2)
		gc.Regalloc(&g2, n1.Type, &r2)
		gc.Cgen(n2, &g2)
		gmove(&g2, &r2)
		gins(optoas(gc.OCMP, t), &r1, &r2)
		gc.Regfree(&g2)
		gc.Regfree(&r2)
	}
	gc.Regfree(&g1)
	gc.Regfree(&r1)
	return gc.Gbranch(optoas(op, t), nil, likely)
}

/*
 * generate division.
 * generates one of:
 *	res = nl / nr
 *	res = nl % nr
 * according to op.
 */
func dodiv(op gc.Op, nl *gc.Node, nr *gc.Node, res *gc.Node) {
	t := nl.Type

	t0 := t

	if t.Width < 8 {
		if gc.Issigned[t.Etype] {
			t = gc.Types[gc.TINT64]
		} else {
			t = gc.Types[gc.TUINT64]
		}
	}

	a := optoas(gc.ODIV, t)

	var tl gc.Node
	gc.Regalloc(&tl, t0, nil)
	var tr gc.Node
	gc.Regalloc(&tr, t0, nil)
	if nl.Ullman >= nr.Ullman {
		gc.Cgen(nl, &tl)
		gc.Cgen(nr, &tr)
	} else {
		gc.Cgen(nr, &tr)
		gc.Cgen(nl, &tl)
	}

	if t != t0 {
		// Convert
		tl2 := tl

		tr2 := tr
		tl.Type = t
		tr.Type = t
		gmove(&tl2, &tl)
		gmove(&tr2, &tr)
	}

	// Handle divide-by-zero panic.
	p1 := ginsbranch(mips.ABNE, nil, &tr, nil, 0)
	if panicdiv == nil {
		panicdiv = gc.Sysfunc("panicdivide")
	}
	gc.Ginscall(panicdiv, -1)
	gc.Patch(p1, gc.Pc)

	gins3(a, &tr, &tl, nil)
	gc.Regfree(&tr)
	if op == gc.ODIV {
		var lo gc.Node
		gc.Nodreg(&lo, gc.Types[gc.TUINT64], mips.REG_LO)
		gins(mips.AMOVV, &lo, &tl)
	} else { // remainder in REG_HI
		var hi gc.Node
		gc.Nodreg(&hi, gc.Types[gc.TUINT64], mips.REG_HI)
		gins(mips.AMOVV, &hi, &tl)
	}
	gmove(&tl, res)
	gc.Regfree(&tl)
}

// gins is called by the front end.
// It synthesizes some multiple-instruction sequences
// so the front end can stay simpler.
func gins(as int, f, t *gc.Node) *obj.Prog {
	if as >= obj.A_ARCHSPECIFIC {
		if x, ok := f.IntLiteral(); ok {
			ginscon(as, x, t)
			return nil // caller must not use
		}
	}
	return rawgins(as, f, t)
}

/*
 * n is a 64-bit value.  fill in lo and hi to refer to its 32-bit halves.
 */
func split64(n *gc.Node, lo *gc.Node, hi *gc.Node) {
	if !gc.Is64(n.Type) {
		gc.Fatalf("split64 %v", n.Type)
	}

	if nsclean >= len(sclean) {
		gc.Fatalf("split64 clean")
	}
	sclean[nsclean].Op = gc.OEMPTY
	nsclean++
	switch n.Op {
	default:
		switch n.Op {
		default:
			var n1 gc.Node
			if !dotaddable(n, &n1) {
				gc.Igen(n, &n1, nil)
				sclean[nsclean-1] = n1
			}

			n = &n1

		case gc.ONAME:
			if n.Class == gc.PPARAMREF {
				var n1 gc.Node
				gc.Cgen(n.Name.Heapaddr, &n1)
				sclean[nsclean-1] = n1
				n = &n1
			}

			// nothing
		case gc.OINDREG:
			break
		}

		*lo = *n
		*hi = *n
		lo.Type = gc.Types[gc.TUINT32]
		if n.Type.Etype == gc.TINT64 {
			hi.Type = gc.Types[gc.TINT32]
		} else {
			hi.Type = gc.Types[gc.TUINT32]
		}
		hi.Xoffset += 4

	case gc.OLITERAL:
		var n1 gc.Node
		n.Convconst(&n1, n.Type)
		i := n1.Int()
		gc.Nodconst(lo, gc.Types[gc.TUINT32], int64(uint32(i)))
		i >>= 32
		if n.Type.Etype == gc.TINT64 {
			gc.Nodconst(hi, gc.Types[gc.TINT32], int64(int32(i)))
		} else {
			gc.Nodconst(hi, gc.Types[gc.TUINT32], int64(uint32(i)))
		}
	}
}

func dotaddable(n *gc.Node, n1 *gc.Node) bool {
	if n.Op != gc.ODOT {
		return false
	}

	var oary [10]int64
	var nn *gc.Node
	o := gc.Dotoffset(n, oary[:], &nn)
	if nn != nil && nn.Addable && o == 1 && oary[0] >= 0 {
		*n1 = *nn
		n1.Type = n.Type
		n1.Xoffset += oary[0]
		return true
	}

	return false
}

func restx(x *gc.Node, oldx *gc.Node) {
	if oldx.Op != 0 {
		x.Type = gc.Types[gc.TINT64]
		gc.SetReg(int(x.Reg), int(oldx.Etype))
		gmove(oldx, x)
		gc.Regfree(oldx)
	}
}

/*
 * register dr is one of the special ones (AX, CX, DI, SI, etc.).
 * we need to use it.  if it is already allocated as a temporary
 * (r > 1; can only happen if a routine like sgen passed a
 * special as cgen's res and then cgen used regalloc to reuse
 * it as its own temporary), then move it for now to another
 * register.  caller must call restx to move it back.
 * the move is not necessary if dr == res, because res is
 * known to be dead.
 */
func savex(dr int, x *gc.Node, oldx *gc.Node, res *gc.Node, t *gc.Type) {
	r := uint8(gc.GetReg(dr))

	// save current ax and dx if they are live
	// and not the destination
	*oldx = gc.Node{}

	gc.Nodreg(x, t, dr)
	if r > 1 && !gc.Samereg(x, res) {
		gc.Regalloc(oldx, gc.Types[gc.TINT64], nil)
		x.Type = gc.Types[gc.TINT64]
		gmove(x, oldx)
		x.Type = t
		// TODO(marvin): Fix Node.EType type union.
		oldx.Etype = gc.EType(r) // squirrel away old r value
		gc.SetReg(dr, 1)
	}
}

func bignodes() {
	if bignodes_did {
		return
	}
	bignodes_did = true

	gc.Nodconst(&zerof, gc.Types[gc.TINT64], 0)
	zerof.Convconst(&zerof, gc.Types[gc.TFLOAT64])

	var i big.Int
	i.SetInt64(1)
	i.Lsh(&i, 63)
	var bigi gc.Node

	gc.Nodconst(&bigi, gc.Types[gc.TUINT64], 0)
	bigi.SetBigInt(&i)
	bigi.Convconst(&two63f, gc.Types[gc.TFLOAT64])

	gc.Nodconst(&bigi, gc.Types[gc.TUINT64], 0)
	i.Lsh(&i, 1)
	bigi.SetBigInt(&i)
	bigi.Convconst(&two64f, gc.Types[gc.TFLOAT64])
}

/*
 * generate move:
 *	t = f
 * hard part is conversions.
 */
func gmove(f *gc.Node, t *gc.Node) {
	if gc.Debug['M'] != 0 {
		fmt.Printf("gmove %v -> %v\n", gc.Nconv(f, obj.FmtLong), gc.Nconv(t, obj.FmtLong))
	}

	ft := gc.Simsimtype(f.Type)
	tt := gc.Simsimtype(t.Type)
	cvt := t.Type

	if gc.Iscomplex[ft] || gc.Iscomplex[tt] {
		gc.Complexmove(f, t)
		return
	}

	// cannot have two memory operands
	var a int
	if gc.Ismem(f) && gc.Ismem(t) {
		goto hard
	}

	// convert constant to desired type
	if f.Op == gc.OLITERAL {
		var con gc.Node
		f.Convconst(&con, t.Type)
		f = &con
		ft = tt // so big switch will choose a simple mov

		// some constants can't move directly to memory.
		if gc.Ismem(t) {
			// float constants come from memory.
			if gc.Isfloat[tt] {
				goto hard
			}

			// 64-bit immediates are really 32-bit sign-extended
			// unless moving into a register.
			if gc.Isint[tt] {
				if i := con.Int(); int64(int32(i)) != i {
					goto hard
				}
			}
		}
	}

	// value -> value copy, only one memory operand.
	// figure out the instruction to use.
	// break out of switch for one-instruction gins.
	// goto rdst for "destination must be register".
	// goto hard for "convert to cvt type first".
	// otherwise handle and return.

	switch uint32(ft)<<16 | uint32(tt) {
	default:
		gc.Fatalf("gmove %v -> %v", gc.Tconv(f.Type, obj.FmtLong), gc.Tconv(t.Type, obj.FmtLong))

		/*
		 * integer copy and truncate
		 */
	case gc.TINT8<<16 | gc.TINT8, // same size
		gc.TINT8<<16 | gc.TUINT8,
		gc.TUINT8<<16 | gc.TINT8,
		gc.TUINT8<<16 | gc.TUINT8,
		gc.TINT16<<16 | gc.TINT8,
		// truncate
		gc.TUINT16<<16 | gc.TINT8,
		gc.TINT32<<16 | gc.TINT8,
		gc.TUINT32<<16 | gc.TINT8,
		gc.TINT64<<16 | gc.TINT8,
		gc.TUINT64<<16 | gc.TINT8,
		gc.TINT16<<16 | gc.TUINT8,
		gc.TUINT16<<16 | gc.TUINT8,
		gc.TINT32<<16 | gc.TUINT8,
		gc.TUINT32<<16 | gc.TUINT8,
		gc.TINT64<<16 | gc.TUINT8,
		gc.TUINT64<<16 | gc.TUINT8:
		a = x86.AMOVB

	case gc.TINT16<<16 | gc.TINT16, // same size
		gc.TINT16<<16 | gc.TUINT16,
		gc.TUINT16<<16 | gc.TINT16,
		gc.TUINT16<<16 | gc.TUINT16,
		gc.TINT32<<16 | gc.TINT16,
		// truncate
		gc.TUINT32<<16 | gc.TINT16,
		gc.TINT64<<16 | gc.TINT16,
		gc.TUINT64<<16 | gc.TINT16,
		gc.TINT32<<16 | gc.TUINT16,
		gc.TUINT32<<16 | gc.TUINT16,
		gc.TINT64<<16 | gc.TUINT16,
		gc.TUINT64<<16 | gc.TUINT16:
		a = x86.AMOVW

	case gc.TINT32<<16 | gc.TINT32, // same size
		gc.TINT32<<16 | gc.TUINT32,
		gc.TUINT32<<16 | gc.TINT32,
//.........這裏部分代碼省略.........

/*
 * generate code to compute address of n,
 * a reference to a (perhaps nested) field inside
 * an array or struct.
 * return 0 on failure, 1 on success.
 * on success, leaves usable address in a.
 *
 * caller is responsible for calling sudoclean
 * after successful sudoaddable,
 * to release the register used for a.
 */
func sudoaddable(as int, n *gc.Node, a *obj.Addr) bool {
	if n.Type == nil {
		return false
	}

	*a = obj.Addr{}

	switch n.Op {
	case gc.OLITERAL:
		if !gc.Isconst(n, gc.CTINT) {
			break
		}
		v := n.Int()
		if v >= 32000 || v <= -32000 {
			break
		}
		switch as {
		default:
			return false

		case x86.AADDB,
			x86.AADDW,
			x86.AADDL,
			x86.AADDQ,
			x86.ASUBB,
			x86.ASUBW,
			x86.ASUBL,
			x86.ASUBQ,
			x86.AANDB,
			x86.AANDW,
			x86.AANDL,
			x86.AANDQ,
			x86.AORB,
			x86.AORW,
			x86.AORL,
			x86.AORQ,
			x86.AXORB,
			x86.AXORW,
			x86.AXORL,
			x86.AXORQ,
			x86.AINCB,
			x86.AINCW,
			x86.AINCL,
			x86.AINCQ,
			x86.ADECB,
			x86.ADECW,
			x86.ADECL,
			x86.ADECQ,
			x86.AMOVB,
			x86.AMOVW,
			x86.AMOVL,
			x86.AMOVQ:
			break
		}

		cleani += 2
		reg := &clean[cleani-1]
		reg1 := &clean[cleani-2]
		reg.Op = gc.OEMPTY
		reg1.Op = gc.OEMPTY
		gc.Naddr(a, n)
		return true

	case gc.ODOT,
		gc.ODOTPTR:
		cleani += 2
		reg := &clean[cleani-1]
		reg1 := &clean[cleani-2]
		reg.Op = gc.OEMPTY
		reg1.Op = gc.OEMPTY
		var nn *gc.Node
		var oary [10]int64
		o := gc.Dotoffset(n, oary[:], &nn)
		if nn == nil {
			sudoclean()
			return false
		}

		if nn.Addable && o == 1 && oary[0] >= 0 {
			// directly addressable set of DOTs
			n1 := *nn

			n1.Type = n.Type
			n1.Xoffset += oary[0]
			gc.Naddr(a, &n1)
			return true
		}

		gc.Regalloc(reg, gc.Types[gc.Tptr], nil)
//.........這裏部分代碼省略.........

func blockcopy(n, res *gc.Node, osrc, odst, w int64) {
	// determine alignment.
	// want to avoid unaligned access, so have to use
	// smaller operations for less aligned types.
	// for example moving [4]byte must use 4 MOVB not 1 MOVW.
	align := int(n.Type.Align)

	var op int
	switch align {
	default:
		gc.Fatalf("sgen: invalid alignment %d for %v", align, n.Type)

	case 1:
		op = arm.AMOVB

	case 2:
		op = arm.AMOVH

	case 4:
		op = arm.AMOVW
	}

	if w%int64(align) != 0 {
		gc.Fatalf("sgen: unaligned size %d (align=%d) for %v", w, align, n.Type)
	}
	c := int32(w / int64(align))

	if osrc%int64(align) != 0 || odst%int64(align) != 0 {
		gc.Fatalf("sgen: unaligned offset src %d or dst %d (align %d)", osrc, odst, align)
	}

	// if we are copying forward on the stack and
	// the src and dst overlap, then reverse direction
	dir := align
	if osrc < odst && int64(odst) < int64(osrc)+w {
		dir = -dir
	}

	if op == arm.AMOVW && !gc.Nacl && dir > 0 && c >= 4 && c <= 128 {
		var r0 gc.Node
		r0.Op = gc.OREGISTER
		r0.Reg = arm.REG_R0
		var r1 gc.Node
		r1.Op = gc.OREGISTER
		r1.Reg = arm.REG_R0 + 1
		var r2 gc.Node
		r2.Op = gc.OREGISTER
		r2.Reg = arm.REG_R0 + 2

		var src gc.Node
		gc.Regalloc(&src, gc.Types[gc.Tptr], &r1)
		var dst gc.Node
		gc.Regalloc(&dst, gc.Types[gc.Tptr], &r2)
		if n.Ullman >= res.Ullman {
			// eval n first
			gc.Agen(n, &src)

			if res.Op == gc.ONAME {
				gc.Gvardef(res)
			}
			gc.Agen(res, &dst)
		} else {
			// eval res first
			if res.Op == gc.ONAME {
				gc.Gvardef(res)
			}
			gc.Agen(res, &dst)
			gc.Agen(n, &src)
		}

		var tmp gc.Node
		gc.Regalloc(&tmp, gc.Types[gc.Tptr], &r0)
		f := gc.Sysfunc("duffcopy")
		p := gins(obj.ADUFFCOPY, nil, f)
		gc.Afunclit(&p.To, f)

		// 8 and 128 = magic constants: see ../../runtime/asm_arm.s
		p.To.Offset = 8 * (128 - int64(c))

		gc.Regfree(&tmp)
		gc.Regfree(&src)
		gc.Regfree(&dst)
		return
	}

	var dst gc.Node
	var src gc.Node
	if n.Ullman >= res.Ullman {
		gc.Agenr(n, &dst, res) // temporarily use dst
		gc.Regalloc(&src, gc.Types[gc.Tptr], nil)
		gins(arm.AMOVW, &dst, &src)
		if res.Op == gc.ONAME {
			gc.Gvardef(res)
		}
		gc.Agen(res, &dst)
	} else {
		if res.Op == gc.ONAME {
			gc.Gvardef(res)
		}
		gc.Agenr(res, &dst, res)
//.........這裏部分代碼省略.........

/*
 * attempt to generate 64-bit
 *	res = n
 * return 1 on success, 0 if op not handled.
 */
func cgen64(n *gc.Node, res *gc.Node) {
	if res.Op != gc.OINDREG && res.Op != gc.ONAME {
		gc.Dump("n", n)
		gc.Dump("res", res)
		gc.Fatalf("cgen64 %v of %v", gc.Oconv(int(n.Op), 0), gc.Oconv(int(res.Op), 0))
	}

	switch n.Op {
	default:
		gc.Fatalf("cgen64 %v", gc.Oconv(int(n.Op), 0))

	case gc.OMINUS:
		gc.Cgen(n.Left, res)
		var hi1 gc.Node
		var lo1 gc.Node
		split64(res, &lo1, &hi1)
		gins(x86.ANEGL, nil, &lo1)
		gins(x86.AADCL, ncon(0), &hi1)
		gins(x86.ANEGL, nil, &hi1)
		splitclean()
		return

	case gc.OCOM:
		gc.Cgen(n.Left, res)
		var lo1 gc.Node
		var hi1 gc.Node
		split64(res, &lo1, &hi1)
		gins(x86.ANOTL, nil, &lo1)
		gins(x86.ANOTL, nil, &hi1)
		splitclean()
		return

		// binary operators.
	// common setup below.
	case gc.OADD,
		gc.OSUB,
		gc.OMUL,
		gc.OLROT,
		gc.OLSH,
		gc.ORSH,
		gc.OAND,
		gc.OOR,
		gc.OXOR:
		break
	}

	l := n.Left
	r := n.Right
	if !l.Addable {
		var t1 gc.Node
		gc.Tempname(&t1, l.Type)
		gc.Cgen(l, &t1)
		l = &t1
	}

	if r != nil && !r.Addable {
		var t2 gc.Node
		gc.Tempname(&t2, r.Type)
		gc.Cgen(r, &t2)
		r = &t2
	}

	var ax gc.Node
	gc.Nodreg(&ax, gc.Types[gc.TINT32], x86.REG_AX)
	var cx gc.Node
	gc.Nodreg(&cx, gc.Types[gc.TINT32], x86.REG_CX)
	var dx gc.Node
	gc.Nodreg(&dx, gc.Types[gc.TINT32], x86.REG_DX)

	// Setup for binary operation.
	var hi1 gc.Node
	var lo1 gc.Node
	split64(l, &lo1, &hi1)

	var lo2 gc.Node
	var hi2 gc.Node
	if gc.Is64(r.Type) {
		split64(r, &lo2, &hi2)
	}

	// Do op.  Leave result in DX:AX.
	switch n.Op {
	// TODO: Constants
	case gc.OADD:
		gins(x86.AMOVL, &lo1, &ax)

		gins(x86.AMOVL, &hi1, &dx)
		gins(x86.AADDL, &lo2, &ax)
		gins(x86.AADCL, &hi2, &dx)

		// TODO: Constants.
	case gc.OSUB:
		gins(x86.AMOVL, &lo1, &ax)

		gins(x86.AMOVL, &hi1, &dx)
//.........這裏部分代碼省略.........

func clearfat_tail(n1 *gc.Node, b int64) {
	if b >= 16 {
		var vec_zero gc.Node
		gc.Regalloc(&vec_zero, gc.Types[gc.TFLOAT64], nil)
		gins(x86.AXORPS, &vec_zero, &vec_zero)

		for b >= 16 {
			gins(x86.AMOVUPS, &vec_zero, n1)
			n1.Xoffset += 16
			b -= 16
		}

		// MOVUPS X0, off(base) is a few bytes shorter than MOV 0, off(base)
		if b != 0 {
			n1.Xoffset -= 16 - b
			gins(x86.AMOVUPS, &vec_zero, n1)
		}

		gc.Regfree(&vec_zero)
		return
	}

	// Write sequence of MOV 0, off(base) instead of using STOSQ.
	// The hope is that although the code will be slightly longer,
	// the MOVs will have no dependencies and pipeline better
	// than the unrolled STOSQ loop.
	var z gc.Node
	gc.Nodconst(&z, gc.Types[gc.TUINT64], 0)
	if b >= 8 {
		n1.Type = z.Type
		gins(x86.AMOVQ, &z, n1)
		n1.Xoffset += 8
		b -= 8

		if b != 0 {
			n1.Xoffset -= 8 - b
			gins(x86.AMOVQ, &z, n1)
		}
		return
	}

	if b >= 4 {
		gc.Nodconst(&z, gc.Types[gc.TUINT32], 0)
		n1.Type = z.Type
		gins(x86.AMOVL, &z, n1)
		n1.Xoffset += 4
		b -= 4

		if b != 0 {
			n1.Xoffset -= 4 - b
			gins(x86.AMOVL, &z, n1)
		}
		return
	}

	if b >= 2 {
		gc.Nodconst(&z, gc.Types[gc.TUINT16], 0)
		n1.Type = z.Type
		gins(x86.AMOVW, &z, n1)
		n1.Xoffset += 2
		b -= 2
	}

	gc.Nodconst(&z, gc.Types[gc.TUINT8], 0)
	for b > 0 {
		n1.Type = z.Type
		gins(x86.AMOVB, &z, n1)
		n1.Xoffset++
		b--
	}

}

func memname(n *gc.Node, t *gc.Type) {
	gc.Tempname(n, t)
	n.Sym = gc.Lookup("." + n.Sym.Name[1:]) // keep optimizer from registerizing
	n.Orig.Sym = n.Sym
}