Golang gc.Node類代碼示例

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)
}

/*
 * call to n has already been generated.
 * generate:
 *	res = &return value from call.
 */
func cgen_aret(n *gc.Node, res *gc.Node) {
	t := n.Left.Type
	if gc.Isptr[t.Etype] {
		t = t.Type
	}

	var flist gc.Iter
	fp := gc.Structfirst(&flist, gc.Getoutarg(t))
	if fp == nil {
		gc.Fatal("cgen_aret: nil")
	}

	var nod1 gc.Node
	nod1.Op = gc.OINDREG
	nod1.Val.U.Reg = x86.REG_SP
	nod1.Addable = 1

	nod1.Xoffset = fp.Width
	nod1.Type = fp.Type

	if res.Op != gc.OREGISTER {
		var nod2 gc.Node
		regalloc(&nod2, gc.Types[gc.Tptr], res)
		gins(x86.ALEAL, &nod1, &nod2)
		gins(x86.AMOVL, &nod2, res)
		regfree(&nod2)
	} else {
		gins(x86.ALEAL, &nod1, res)
	}
}

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)
}

/*
 * 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.Fatal("split64 %v", gc.Tconv(n.Type, 0))
	}

	if nsclean >= len(sclean) {
		gc.Fatal("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.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
		gc.Convconst(&n1, n.Type, &n.Val)
		i := gc.Mpgetfix(n1.Val.U.Xval)
		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 intLiteral(n *gc.Node) (x int64, ok bool) {
	switch {
	case n == nil:
		return
	case gc.Isconst(n, gc.CTINT):
		return n.Int(), true
	case gc.Isconst(n, gc.CTBOOL):
		return int64(obj.Bool2int(n.Bool())), true
	}
	return
}

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
}

/*
 * 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
	}
}

func restx(x *gc.Node, oldx *gc.Node) {
	if oldx.Op != 0 {
		x.Type = gc.Types[gc.TINT64]
		reg[x.Reg] = uint8(oldx.Ostk)
		gmove(oldx, x)
		gc.Regfree(oldx)
	}
}

func restx(x *gc.Node, oldx *gc.Node) {
	gc.Regfree(x)

	if oldx.Op != 0 {
		x.Type = gc.Types[gc.TINT32]
		gmove(oldx, x)
	}
}

/*
 * generate function call;
 *	proc=0	normal call
 *	proc=1	goroutine run in new proc
 *	proc=2	defer call save away stack
 */
func cgen_call(n *gc.Node, proc int) {
	if n == nil {
		return
	}

	var afun gc.Node
	if n.Left.Ullman >= gc.UINF {
		// if name involves a fn call
		// precompute the address of the fn
		gc.Tempname(&afun, gc.Types[gc.Tptr])

		cgen(n.Left, &afun)
	}

	gc.Genlist(n.List) // assign the args
	t := n.Left.Type

	// call tempname pointer
	if n.Left.Ullman >= gc.UINF {
		var nod gc.Node
		regalloc(&nod, gc.Types[gc.Tptr], nil)
		gc.Cgen_as(&nod, &afun)
		nod.Type = t
		ginscall(&nod, proc)
		regfree(&nod)
		return
	}

	// call pointer
	if n.Left.Op != gc.ONAME || n.Left.Class != gc.PFUNC {
		var nod gc.Node
		regalloc(&nod, gc.Types[gc.Tptr], nil)
		gc.Cgen_as(&nod, n.Left)
		nod.Type = t
		ginscall(&nod, proc)
		regfree(&nod)
		return
	}

	// call direct
	n.Left.Method = 1

	ginscall(n.Left, proc)
}

/*
 * call to n has already been generated.
 * generate:
 *	res = return value from call.
 */
func cgen_callret(n *gc.Node, res *gc.Node) {
	t := n.Left.Type
	if t.Etype == gc.TPTR32 || t.Etype == gc.TPTR64 {
		t = t.Type
	}

	var flist gc.Iter
	fp := gc.Structfirst(&flist, gc.Getoutarg(t))
	if fp == nil {
		gc.Fatal("cgen_callret: nil")
	}

	var nod gc.Node
	nod.Op = gc.OINDREG
	nod.Val.U.Reg = x86.REG_SP
	nod.Addable = 1

	nod.Xoffset = fp.Width
	nod.Type = fp.Type
	gc.Cgen_as(res, &nod)
}

func fixlargeoffset(n *gc.Node) {
	if n == nil {
		return
	}
	if n.Op != gc.OINDREG {
		return
	}
	if -4096 <= n.Xoffset && n.Xoffset < 4096 {
		return
	}
	a := gc.Node(*n)
	a.Op = gc.OREGISTER
	a.Type = gc.Types[gc.Tptr]
	a.Xoffset = 0
	gc.Cgen_checknil(&a)
	ginscon(optoas(gc.OADD, gc.Types[gc.Tptr]), n.Xoffset, &a)
	n.Xoffset = 0
}

/*
 * peep.c
 */
func mgen(n *gc.Node, n1 *gc.Node, rg *gc.Node) {
	n1.Op = gc.OEMPTY

	if n.Addable != 0 {
		*n1 = *n
		if n1.Op == gc.OREGISTER || n1.Op == gc.OINDREG {
			reg[n.Val.U.Reg]++
		}
		return
	}

	gc.Tempname(n1, n.Type)
	cgen(n, n1)
	if n.Type.Width <= int64(gc.Widthptr) || gc.Isfloat[n.Type.Etype] {
		n2 := *n1
		regalloc(n1, n.Type, rg)
		gmove(&n2, n1)
	}
}

/*
 * generate:
 *	res = n;
 * simplifies and calls gmove.
 */
func cgen(n *gc.Node, res *gc.Node) {
	//print("cgen %N(%d) -> %N(%d)\n", n, n->addable, res, res->addable);
	if gc.Debug['g'] != 0 {
		gc.Dump("\ncgen-n", n)
		gc.Dump("cgen-res", res)
	}

	if n == nil || n.Type == nil {
		return
	}

	if res == nil || res.Type == nil {
		gc.Fatal("cgen: res nil")
	}

	for n.Op == gc.OCONVNOP {
		n = n.Left
	}

	switch n.Op {
	case gc.OSLICE,
		gc.OSLICEARR,
		gc.OSLICESTR,
		gc.OSLICE3,
		gc.OSLICE3ARR:
		if res.Op != gc.ONAME || res.Addable == 0 {
			var n1 gc.Node
			gc.Tempname(&n1, n.Type)
			gc.Cgen_slice(n, &n1)
			cgen(&n1, res)
		} else {
			gc.Cgen_slice(n, res)
		}
		return

	case gc.OEFACE:
		if res.Op != gc.ONAME || res.Addable == 0 {
			var n1 gc.Node
			gc.Tempname(&n1, n.Type)
			gc.Cgen_eface(n, &n1)
			cgen(&n1, res)
		} else {
			gc.Cgen_eface(n, res)
		}
		return
	}

	if n.Ullman >= gc.UINF {
		if n.Op == gc.OINDREG {
			gc.Fatal("cgen: this is going to misscompile")
		}
		if res.Ullman >= gc.UINF {
			var n1 gc.Node
			gc.Tempname(&n1, n.Type)
			cgen(n, &n1)
			cgen(&n1, res)
			return
		}
	}

	if gc.Isfat(n.Type) {
		if n.Type.Width < 0 {
			gc.Fatal("forgot to compute width for %v", gc.Tconv(n.Type, 0))
		}
		sgen(n, res, n.Type.Width)
		return
	}

	if res.Addable == 0 {
		if n.Ullman > res.Ullman {
			var n1 gc.Node
			regalloc(&n1, n.Type, res)
			cgen(n, &n1)
			if n1.Ullman > res.Ullman {
				gc.Dump("n1", &n1)
				gc.Dump("res", res)
				gc.Fatal("loop in cgen")
			}

			cgen(&n1, res)
			regfree(&n1)
			return
		}

		var f int
		if res.Ullman >= gc.UINF {
			goto gen
		}

		if gc.Complexop(n, res) {
			gc.Complexgen(n, res)
			return
		}

		f = 1 // gen thru register
//.........這裏部分代碼省略.........

func clearfat(nl *gc.Node) {
	/* clear a fat object */
	if gc.Debug['g'] != 0 {
		gc.Dump("\nclearfat", nl)
	}

	w := uint32(nl.Type.Width)

	// Avoid taking the address for simple enough types.
	if gc.Componentgen(nil, nl) {
		return
	}

	c := w % 4 // bytes
	q := w / 4 // quads

	if q < 4 {
		// Write sequence of MOV 0, off(base) instead of using STOSL.
		// The hope is that although the code will be slightly longer,
		// the MOVs will have no dependencies and pipeline better
		// than the unrolled STOSL loop.
		// NOTE: Must use agen, not igen, so that optimizer sees address
		// being taken. We are not writing on field boundaries.
		var n1 gc.Node
		gc.Regalloc(&n1, gc.Types[gc.Tptr], nil)

		gc.Agen(nl, &n1)
		n1.Op = gc.OINDREG
		var z gc.Node
		gc.Nodconst(&z, gc.Types[gc.TUINT64], 0)
		for {
			tmp14 := q
			q--
			if tmp14 <= 0 {
				break
			}
			n1.Type = z.Type
			gins(x86.AMOVL, &z, &n1)
			n1.Xoffset += 4
		}

		gc.Nodconst(&z, gc.Types[gc.TUINT8], 0)
		for {
			tmp15 := c
			c--
			if tmp15 <= 0 {
				break
			}
			n1.Type = z.Type
			gins(x86.AMOVB, &z, &n1)
			n1.Xoffset++
		}

		gc.Regfree(&n1)
		return
	}

	var n1 gc.Node
	gc.Nodreg(&n1, gc.Types[gc.Tptr], x86.REG_DI)
	gc.Agen(nl, &n1)
	gconreg(x86.AMOVL, 0, x86.REG_AX)

	if q > 128 || (q >= 4 && gc.Nacl) {
		gconreg(x86.AMOVL, int64(q), x86.REG_CX)
		gins(x86.AREP, nil, nil)   // repeat
		gins(x86.ASTOSL, nil, nil) // STOL AL,*(DI)+
	} else if q >= 4 {
		p := gins(obj.ADUFFZERO, nil, nil)
		p.To.Type = obj.TYPE_ADDR
		p.To.Sym = gc.Linksym(gc.Pkglookup("duffzero", gc.Runtimepkg))

		// 1 and 128 = magic constants: see ../../runtime/asm_386.s
		p.To.Offset = 1 * (128 - int64(q))
	} else {
		for q > 0 {
			gins(x86.ASTOSL, nil, nil) // STOL AL,*(DI)+
			q--
		}
	}

	for c > 0 {
		gins(x86.ASTOSB, nil, nil) // STOB AL,*(DI)+
		c--
	}
}