Golang gc.Cgen函數代碼示例

func ginscmp(op int, t *gc.Type, n1, n2 *gc.Node, likely int) *obj.Prog {
	if gc.Isint[t.Etype] && n1.Op == gc.OLITERAL && 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 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 gc.Op, 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 {
		nl, nr = nr, nl
	}

	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
}

/*
 * 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 t.IsSigned() {
			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)
}

/*
 * 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 && gc.Smallintconst(n1) && n2.Op != gc.OLITERAL {
		// Reverse comparison to place constant last.
		op = gc.Brrev(op)
		n1, n2 = n2, n1
	}
	// General case.
	var r1, r2, g1, g2 gc.Node
	if n1.Op == gc.ONAME && n1.Class&gc.PHEAP == 0 || n1.Op == gc.OINDREG {
		r1 = *n1
	} else {
		gc.Regalloc(&r1, t, n1)
		gc.Regalloc(&g1, n1.Type, &r1)
		gc.Cgen(n1, &g1)
		gmove(&g1, &r1)
	}
	if n2.Op == gc.OLITERAL && gc.Isint[t.Etype] && gc.Smallintconst(n2) {
		r2 = *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)
	if r1.Op == gc.OREGISTER {
		gc.Regfree(&g1)
		gc.Regfree(&r1)
	}
	if r2.Op == gc.OREGISTER {
		gc.Regfree(&g2)
		gc.Regfree(&r2)
	}
	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)
		gcmp(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 an addressable node in res, containing the value of n.
 * n is an array index, and might be any size; res width is <= 32-bit.
 * returns Prog* to patch to panic call.
 */
func igenindex(n *gc.Node, res *gc.Node, bounded bool) *obj.Prog {
	if !gc.Is64(n.Type) {
		if n.Addable && (gc.Simtype[n.Etype] == gc.TUINT32 || gc.Simtype[n.Etype] == gc.TINT32) {
			// nothing to do.
			*res = *n
		} else {
			gc.Tempname(res, gc.Types[gc.TUINT32])
			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)
	gc.Tempname(res, gc.Types[gc.TUINT32])
	gmove(&lo, res)
	if bounded {
		splitclean()
		return nil
	}

	var zero gc.Node
	gc.Nodconst(&zero, gc.Types[gc.TINT32], 0)
	gins(x86.ACMPL, &hi, &zero)
	splitclean()
	return gc.Gbranch(x86.AJNE, nil, +1)
}

/*
 * 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.Fatalf("cgen_hmul %v", t)
	}

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

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

	// General case.
	var r1, r2, g1, g2 gc.Node

	// A special case to make write barriers more efficient.
	// Comparing the first field of a named struct can be done directly.
	base := n1
	if n1.Op == gc.ODOT && n1.Left.Type.Etype == gc.TSTRUCT && n1.Left.Type.Type.Sym == n1.Right.Sym {
		base = n1.Left
	}

	if base.Op == gc.ONAME && base.Class&gc.PHEAP == 0 || n1.Op == gc.OINDREG {
		r1 = *n1
	} else {
		gc.Regalloc(&r1, t, n1)
		gc.Regalloc(&g1, n1.Type, &r1)
		gc.Cgen(n1, &g1)
		gmove(&g1, &r1)
	}
	if n2.Op == gc.OLITERAL && gc.Isint[t.Etype] || n2.Op == gc.OADDR && n2.Left.Op == gc.ONAME && n2.Left.Class == gc.PEXTERN {
		r2 = *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)
	if r1.Op == gc.OREGISTER {
		gc.Regfree(&g1)
		gc.Regfree(&r1)
	}
	if r2.Op == gc.OREGISTER {
		gc.Regfree(&g2)
		gc.Regfree(&r2)
	}
	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.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)))
		}
	}
}

/*
 * generate floating-point operation.
 */
func cgen_float(n *gc.Node, res *gc.Node) {
	nl := n.Left
	switch n.Op {
	case gc.OEQ,
		gc.ONE,
		gc.OLT,
		gc.OLE,
		gc.OGE:
		p1 := gc.Gbranch(obj.AJMP, nil, 0)
		p2 := gc.Pc
		gmove(gc.Nodbool(true), res)
		p3 := gc.Gbranch(obj.AJMP, nil, 0)
		gc.Patch(p1, gc.Pc)
		gc.Bgen(n, true, 0, p2)
		gmove(gc.Nodbool(false), res)
		gc.Patch(p3, gc.Pc)
		return

	case gc.OPLUS:
		gc.Cgen(nl, res)
		return

	case gc.OCONV:
		if gc.Eqtype(n.Type, nl.Type) || gc.Noconv(n.Type, nl.Type) {
			gc.Cgen(nl, res)
			return
		}

		var n2 gc.Node
		gc.Tempname(&n2, n.Type)
		var n1 gc.Node
		gc.Mgen(nl, &n1, res)
		gmove(&n1, &n2)
		gmove(&n2, res)
		gc.Mfree(&n1)
		return
	}

	if gc.Thearch.Use387 {
		cgen_float387(n, res)
	} else {
		cgen_floatsse(n, res)
	}
}

func ginscmp(op gc.Op, t *gc.Type, n1, n2 *gc.Node, likely int) *obj.Prog {
	if t.IsInteger() && n1.Op == gc.OLITERAL && gc.Smallintconst(n1) && n2.Op != gc.OLITERAL {
		// Reverse comparison to place constant last.
		op = gc.Brrev(op)
		n1, n2 = n2, n1
	}
	// General case.
	var r1, r2, g1, g2 gc.Node

	// A special case to make write barriers more efficient.
	// Comparing the first field of a named struct can be done directly.
	base := n1
	if n1.Op == gc.ODOT && n1.Left.Type.IsStruct() && n1.Left.Type.Field(0).Sym == n1.Sym {
		base = n1.Left
	}

	if base.Op == gc.ONAME && base.Class != gc.PAUTOHEAP || n1.Op == gc.OINDREG {
		r1 = *n1
	} else {
		gc.Regalloc(&r1, t, n1)
		gc.Regalloc(&g1, n1.Type, &r1)
		gc.Cgen(n1, &g1)
		gmove(&g1, &r1)
	}
	if n2.Op == gc.OLITERAL && t.IsInteger() && gc.Smallintconst(n2) {
		r2 = *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)
	if r1.Op == gc.OREGISTER {
		gc.Regfree(&g1)
		gc.Regfree(&r1)
	}
	if r2.Op == gc.OREGISTER {
		gc.Regfree(&g2)
		gc.Regfree(&r2)
	}
	return gc.Gbranch(optoas(op, t), nil, likely)
}

/*
 * generate high multiply:
 *   res = (nl*nr) >> width
 */
func cgen_hmul(nl *gc.Node, nr *gc.Node, res *gc.Node) {
	// largest ullman on left.
	if nl.Ullman < nr.Ullman {
		nl, nr = nr, nl
	}

	t := nl.Type
	w := t.Width * 8
	var n1 gc.Node
	gc.Cgenr(nl, &n1, res)
	var n2 gc.Node
	gc.Cgenr(nr, &n2, nil)
	switch gc.Simtype[t.Etype] {
	case gc.TINT8,
		gc.TINT16,
		gc.TINT32:
		gins3(optoas(gc.OMUL, t), &n2, &n1, nil)
		var lo gc.Node
		gc.Nodreg(&lo, gc.Types[gc.TUINT64], mips.REG_LO)
		gins(mips.AMOVV, &lo, &n1)
		p := gins(mips.ASRAV, nil, &n1)
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = w

	case gc.TUINT8,
		gc.TUINT16,
		gc.TUINT32:
		gins3(optoas(gc.OMUL, t), &n2, &n1, nil)
		var lo gc.Node
		gc.Nodreg(&lo, gc.Types[gc.TUINT64], mips.REG_LO)
		gins(mips.AMOVV, &lo, &n1)
		p := gins(mips.ASRLV, nil, &n1)
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = w

	case gc.TINT64,
		gc.TUINT64:
		if t.IsSigned() {
			gins3(mips.AMULV, &n2, &n1, nil)
		} else {
			gins3(mips.AMULVU, &n2, &n1, nil)
		}
		var hi gc.Node
		gc.Nodreg(&hi, gc.Types[gc.TUINT64], mips.REG_HI)
		gins(mips.AMOVV, &hi, &n1)

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

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

// floating-point.  387 (not SSE2)
func cgen_float387(n *gc.Node, res *gc.Node) {
	var f0 gc.Node
	var f1 gc.Node

	nl := n.Left
	nr := n.Right
	gc.Nodreg(&f0, nl.Type, x86.REG_F0)
	gc.Nodreg(&f1, n.Type, x86.REG_F0+1)
	if nr != nil {
		// binary
		if nl.Ullman >= nr.Ullman {
			gc.Cgen(nl, &f0)
			if nr.Addable {
				gins(foptoas(n.Op, n.Type, 0), nr, &f0)
			} else {
				gc.Cgen(nr, &f0)
				gins(foptoas(n.Op, n.Type, Fpop), &f0, &f1)
			}
		} else {
			gc.Cgen(nr, &f0)
			if nl.Addable {
				gins(foptoas(n.Op, n.Type, Frev), nl, &f0)
			} else {
				gc.Cgen(nl, &f0)
				gins(foptoas(n.Op, n.Type, Frev|Fpop), &f0, &f1)
			}
		}

		gmove(&f0, res)
		return
	}

	// unary
	gc.Cgen(nl, &f0)

	if n.Op != gc.OCONV && n.Op != gc.OPLUS {
		gins(foptoas(n.Op, n.Type, 0), nil, nil)
	}
	gmove(&f0, res)
	return
}

/*
 * 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
}