Golang gc.Regalloc函數代碼示例

/*
 * generate array index into res.
 * n might be any size; res is 32-bit.
 * returns Prog* to patch to panic call.
 */
func cgenindex(n *gc.Node, res *gc.Node, bounded bool) *obj.Prog {
	if !gc.Is64(n.Type) {
		gc.Cgen(n, res)
		return nil
	}

	var tmp gc.Node
	gc.Tempname(&tmp, gc.Types[gc.TINT64])
	gc.Cgen(n, &tmp)
	var lo gc.Node
	var hi gc.Node
	split64(&tmp, &lo, &hi)
	gmove(&lo, res)
	if bounded {
		splitclean()
		return nil
	}

	var n1 gc.Node
	gc.Regalloc(&n1, gc.Types[gc.TINT32], nil)
	var n2 gc.Node
	gc.Regalloc(&n2, gc.Types[gc.TINT32], nil)
	var zero gc.Node
	gc.Nodconst(&zero, gc.Types[gc.TINT32], 0)
	gmove(&hi, &n1)
	gmove(&zero, &n2)
	gins(arm.ACMP, &n1, &n2)
	gc.Regfree(&n2)
	gc.Regfree(&n1)
	splitclean()
	return gc.Gbranch(arm.ABNE, nil, -1)
}

func ginscmp(op int, 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)
}

func ginscmp(op int, 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)
}

/*
 * generate high multiply
 *  res = (nl * nr) >> wordsize
 */
func cgen_hmul(nl *gc.Node, nr *gc.Node, res *gc.Node) {
	if nl.Ullman < nr.Ullman {
		tmp := nl
		nl = nr
		nr = tmp
	}

	t := nl.Type
	w := int(t.Width * 8)
	var n1 gc.Node
	gc.Regalloc(&n1, t, res)
	gc.Cgen(nl, &n1)
	var n2 gc.Node
	gc.Regalloc(&n2, t, nil)
	gc.Cgen(nr, &n2)
	switch gc.Simtype[t.Etype] {
	case gc.TINT8,
		gc.TINT16:
		gins(optoas(gc.OMUL, t), &n2, &n1)
		gshift(arm.AMOVW, &n1, arm.SHIFT_AR, int32(w), &n1)

	case gc.TUINT8,
		gc.TUINT16:
		gins(optoas(gc.OMUL, t), &n2, &n1)
		gshift(arm.AMOVW, &n1, arm.SHIFT_LR, int32(w), &n1)

		// perform a long multiplication.
	case gc.TINT32,
		gc.TUINT32:
		var p *obj.Prog
		if gc.Issigned[t.Etype] {
			p = gins(arm.AMULL, &n2, nil)
		} else {
			p = gins(arm.AMULLU, &n2, nil)
		}

		// n2 * n1 -> (n1 n2)
		p.Reg = n1.Reg

		p.To.Type = obj.TYPE_REGREG
		p.To.Reg = n1.Reg
		p.To.Offset = int64(n2.Reg)

	default:
		gc.Fatal("cgen_hmul %v", t)
	}

	gc.Cgen(&n1, res)
	gc.Regfree(&n1)
	gc.Regfree(&n2)
}

/*
 * generate
 *	as n, $c (CMP/CMPU)
 */
func ginscon2(as int, n2 *gc.Node, c int64) {
	var n1 gc.Node

	gc.Nodconst(&n1, gc.Types[gc.TINT64], c)

	switch as {
	default:
		gc.Fatal("ginscon2")

	case ppc64.ACMP:
		if -ppc64.BIG <= c && c <= ppc64.BIG {
			rawgins(as, n2, &n1)
			return
		}

	case ppc64.ACMPU:
		if 0 <= c && c <= 2*ppc64.BIG {
			rawgins(as, n2, &n1)
			return
		}
	}

	// MOV n1 into register first
	var ntmp gc.Node
	gc.Regalloc(&ntmp, gc.Types[gc.TINT64], nil)

	rawgins(ppc64.AMOVD, &n1, &ntmp)
	rawgins(as, n2, &ntmp)
	gc.Regfree(&ntmp)
}

/*
 * generate
 *	as $c, n
 */
func ginscon(as int, c int64, n2 *gc.Node) {
	var n1 gc.Node

	switch as {
	case x86.AADDL,
		x86.AMOVL,
		x86.ALEAL:
		gc.Nodconst(&n1, gc.Types[gc.TINT32], c)

	default:
		gc.Nodconst(&n1, gc.Types[gc.TINT64], c)
	}

	if as != x86.AMOVQ && (c < -(1<<31) || c >= 1<<31) {
		// cannot have 64-bit immediate in ADD, etc.
		// instead, MOV into register first.
		var ntmp gc.Node
		gc.Regalloc(&ntmp, gc.Types[gc.TINT64], nil)

		gins(x86.AMOVQ, &n1, &ntmp)
		gins(as, &ntmp, n2)
		gc.Regfree(&ntmp)
		return
	}

	gins(as, &n1, n2)
}

/*
 * generate
 *	as $c, n
 */
func ginscon(as int, c int64, n *gc.Node) {
	var n1 gc.Node
	gc.Nodconst(&n1, gc.Types[gc.TINT32], c)
	var n2 gc.Node
	gc.Regalloc(&n2, gc.Types[gc.TINT32], nil)
	gmove(&n1, &n2)
	gins(as, &n2, n)
	gc.Regfree(&n2)
}

/*
 * generate byte multiply:
 *	res = nl * nr
 * there is no 2-operand byte multiply instruction so
 * we do a full-width multiplication and truncate afterwards.
 */
func cgen_bmul(op int, nl *gc.Node, nr *gc.Node, res *gc.Node) bool {
	if optoas(op, nl.Type) != x86.AIMULB {
		return false
	}

	// largest ullman on left.
	if nl.Ullman < nr.Ullman {
		tmp := nl
		nl = nr
		nr = tmp
	}

	// generate operands in "8-bit" registers.
	var n1b gc.Node
	gc.Regalloc(&n1b, nl.Type, res)

	gc.Cgen(nl, &n1b)
	var n2b gc.Node
	gc.Regalloc(&n2b, nr.Type, nil)
	gc.Cgen(nr, &n2b)

	// perform full-width multiplication.
	t := gc.Types[gc.TUINT64]

	if gc.Issigned[nl.Type.Etype] {
		t = gc.Types[gc.TINT64]
	}
	var n1 gc.Node
	gc.Nodreg(&n1, t, int(n1b.Reg))
	var n2 gc.Node
	gc.Nodreg(&n2, t, int(n2b.Reg))
	a := optoas(op, t)
	gins(a, &n2, &n1)

	// truncate.
	gmove(&n1, res)

	gc.Regfree(&n1b)
	gc.Regfree(&n2b)
	return true
}

func gencmp0(n *gc.Node, t *gc.Type, o int, likely int, to *obj.Prog) {
	var n1 gc.Node

	gc.Regalloc(&n1, t, nil)
	gc.Cgen(n, &n1)
	a := optoas(gc.OCMP, t)
	if a != arm.ACMP {
		var n2 gc.Node
		gc.Nodconst(&n2, t, 0)
		var n3 gc.Node
		gc.Regalloc(&n3, t, nil)
		gmove(&n2, &n3)
		gins(a, &n1, &n3)
		gc.Regfree(&n3)
	} else {
		gins(arm.ATST, &n1, nil)
	}
	a = optoas(o, t)
	gc.Patch(gc.Gbranch(a, t, likely), to)
	gc.Regfree(&n1)
}

// res = runtime.getg()
func getg(res *gc.Node) {
	var n1 gc.Node
	gc.Regalloc(&n1, res.Type, res)
	mov := optoas(gc.OAS, gc.Types[gc.Tptr])
	p := gins(mov, nil, &n1)
	p.From.Type = obj.TYPE_REG
	p.From.Reg = x86.REG_TLS
	p = gins(mov, nil, &n1)
	p.From = p.To
	p.From.Type = obj.TYPE_MEM
	p.From.Index = x86.REG_TLS
	p.From.Scale = 1
	gmove(&n1, res)
	gc.Regfree(&n1)
}

func savex(dr int, x *gc.Node, oldx *gc.Node, res *gc.Node, t *gc.Type) {
	r := int(reg[dr])
	gc.Nodreg(x, gc.Types[gc.TINT32], dr)

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

	if r > 0 && !gc.Samereg(x, res) {
		gc.Tempname(oldx, gc.Types[gc.TINT32])
		gmove(x, oldx)
	}

	gc.Regalloc(x, t, x)
}

/*
 * generate byte multiply:
 *	res = nl * nr
 * there is no 2-operand byte multiply instruction so
 * we do a full-width multiplication and truncate afterwards.
 */
func cgen_bmul(op int, nl *gc.Node, nr *gc.Node, res *gc.Node) bool {
	if optoas(op, nl.Type) != x86.AIMULB {
		return false
	}

	// copy from byte to full registers
	t := gc.Types[gc.TUINT32]

	if gc.Issigned[nl.Type.Etype] {
		t = gc.Types[gc.TINT32]
	}

	// largest ullman on left.
	if nl.Ullman < nr.Ullman {
		tmp := nl
		nl = nr
		nr = tmp
	}

	var nt gc.Node
	gc.Tempname(&nt, nl.Type)
	gc.Cgen(nl, &nt)
	var n1 gc.Node
	gc.Regalloc(&n1, t, res)
	gc.Cgen(nr, &n1)
	var n2 gc.Node
	gc.Regalloc(&n2, t, nil)
	gmove(&nt, &n2)
	a := optoas(op, t)
	gins(a, &n2, &n1)
	gc.Regfree(&n2)
	gmove(&n1, res)
	gc.Regfree(&n1)

	return true
}

/*
 * 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 := int(reg[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
		oldx.Ostk = int32(r) // squirrel away old r value
		reg[dr] = 1
	}
}

/*
 * generate
 *	as $c, n
 */
func ginscon(as int, c int64, n2 *gc.Node) {
	var n1 gc.Node

	gc.Nodconst(&n1, gc.Types[gc.TINT64], c)

	if as != ppc64.AMOVD && (c < -ppc64.BIG || c > ppc64.BIG) || n2.Op != gc.OREGISTER || as == ppc64.AMULLD {
		// cannot have more than 16-bit of immediate in ADD, etc.
		// instead, MOV into register first.
		var ntmp gc.Node
		gc.Regalloc(&ntmp, gc.Types[gc.TINT64], nil)

		rawgins(ppc64.AMOVD, &n1, &ntmp)
		rawgins(as, &ntmp, n2)
		gc.Regfree(&ntmp)
		return
	}

	rawgins(as, &n1, n2)
}

/*
 * generate high multiply:
 *   res = (nl*nr) >> width
 */
func cgen_hmul(nl *gc.Node, nr *gc.Node, res *gc.Node) {
	var n1 gc.Node
	var n2 gc.Node
	var ax gc.Node
	var dx gc.Node

	t := nl.Type
	a := optoas(gc.OHMUL, t)

	// gen nl in n1.
	gc.Tempname(&n1, t)

	gc.Cgen(nl, &n1)

	// gen nr in n2.
	gc.Regalloc(&n2, t, res)

	gc.Cgen(nr, &n2)

	// multiply.
	gc.Nodreg(&ax, t, x86.REG_AX)

	gmove(&n2, &ax)
	gins(a, &n1, nil)
	gc.Regfree(&n2)

	if t.Width == 1 {
		// byte multiply behaves differently.
		gc.Nodreg(&ax, t, x86.REG_AH)

		gc.Nodreg(&dx, t, x86.REG_DX)
		gmove(&ax, &dx)
	}

	gc.Nodreg(&dx, t, x86.REG_DX)
	gmove(&dx, res)
}