Golang gc.Gbranch函數代碼示例

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)
}

/*
 * 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 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 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 branch
// n1, n2 are registers
func ginsbranch(as int, t *gc.Type, n1, n2 *gc.Node, likely int) *obj.Prog {
	p := gc.Gbranch(as, t, likely)
	gc.Naddr(&p.From, n1)
	if n2 != nil {
		p.Reg = n2.Reg
	}
	return p
}

/*
 * 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)
	}
}

/*
 * 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) {
	// Have to be careful about handling
	// most negative int divided by -1 correctly.
	// The hardware will trap.
	// Also the byte divide instruction needs AH,
	// which we otherwise don't have to deal with.
	// Easiest way to avoid for int8, int16: use int32.
	// For int32 and int64, use explicit test.
	// Could use int64 hw for int32.
	t := nl.Type

	t0 := t
	check := false
	if gc.Issigned[t.Etype] {
		check = true
		if gc.Isconst(nl, gc.CTINT) && nl.Int() != -(1<<uint64(t.Width*8-1)) {
			check = false
		} else if gc.Isconst(nr, gc.CTINT) && nr.Int() != -1 {
			check = false
		}
	}

	if t.Width < 4 {
		if gc.Issigned[t.Etype] {
			t = gc.Types[gc.TINT32]
		} else {
			t = gc.Types[gc.TUINT32]
		}
		check = false
	}

	a := optoas(op, t)

	var n3 gc.Node
	gc.Regalloc(&n3, t0, nil)
	var ax gc.Node
	var oldax gc.Node
	if nl.Ullman >= nr.Ullman {
		savex(x86.REG_AX, &ax, &oldax, res, t0)
		gc.Cgen(nl, &ax)
		gc.Regalloc(&ax, t0, &ax) // mark ax live during cgen
		gc.Cgen(nr, &n3)
		gc.Regfree(&ax)
	} else {
		gc.Cgen(nr, &n3)
		savex(x86.REG_AX, &ax, &oldax, res, t0)
		gc.Cgen(nl, &ax)
	}

	if t != t0 {
		// Convert
		ax1 := ax

		n31 := n3
		ax.Type = t
		n3.Type = t
		gmove(&ax1, &ax)
		gmove(&n31, &n3)
	}

	var n4 gc.Node
	if gc.Nacl {
		// Native Client does not relay the divide-by-zero trap
		// to the executing program, so we must insert a check
		// for ourselves.
		gc.Nodconst(&n4, t, 0)

		gins(optoas(gc.OCMP, t), &n3, &n4)
		p1 := gc.Gbranch(optoas(gc.ONE, t), nil, +1)
		if panicdiv == nil {
			panicdiv = gc.Sysfunc("panicdivide")
		}
		gc.Ginscall(panicdiv, -1)
		gc.Patch(p1, gc.Pc)
	}

	var p2 *obj.Prog
	if check {
		gc.Nodconst(&n4, t, -1)
		gins(optoas(gc.OCMP, t), &n3, &n4)
		p1 := gc.Gbranch(optoas(gc.ONE, t), nil, +1)
		if op == gc.ODIV {
			// a / (-1) is -a.
			gins(optoas(gc.OMINUS, t), nil, &ax)

			gmove(&ax, res)
		} else {
			// a % (-1) is 0.
			gc.Nodconst(&n4, t, 0)

			gmove(&n4, res)
		}

//.........這裏部分代碼省略.........

//.........這裏部分代碼省略.........

				//	MOVW	bl<<(v-32), ah
				gshift(arm.AMOVW, &bl, arm.SHIFT_LL, int32(v-32), &ah)
			} else if v == 32 {
				gins(arm.AEOR, &al, &al)
				gins(arm.AMOVW, &bl, &ah)
			} else if v > 0 {
				//	MOVW	bl<<v, al
				gshift(arm.AMOVW, &bl, arm.SHIFT_LL, int32(v), &al)

				//	MOVW	bh<<v, ah
				gshift(arm.AMOVW, &bh, arm.SHIFT_LL, int32(v), &ah)

				//	OR		bl>>(32-v), ah
				gshift(arm.AORR, &bl, arm.SHIFT_LR, int32(32-v), &ah)
			} else {
				gins(arm.AMOVW, &bl, &al)
				gins(arm.AMOVW, &bh, &ah)
			}

			goto olsh_break
		}

		gc.Regalloc(&s, gc.Types[gc.TUINT32], nil)
		gc.Regalloc(&creg, gc.Types[gc.TUINT32], nil)
		if gc.Is64(r.Type) {
			// shift is >= 1<<32
			var cl gc.Node
			var ch gc.Node
			split64(r, &cl, &ch)

			gmove(&ch, &s)
			gins(arm.ATST, &s, nil)
			p6 = gc.Gbranch(arm.ABNE, nil, 0)
			gmove(&cl, &s)
			splitclean()
		} else {
			gmove(r, &s)
			p6 = nil
		}

		gins(arm.ATST, &s, nil)

		// shift == 0
		p1 = gins(arm.AMOVW, &bl, &al)

		p1.Scond = arm.C_SCOND_EQ
		p1 = gins(arm.AMOVW, &bh, &ah)
		p1.Scond = arm.C_SCOND_EQ
		p2 = gc.Gbranch(arm.ABEQ, nil, 0)

		// shift is < 32
		gc.Nodconst(&n1, gc.Types[gc.TUINT32], 32)

		gmove(&n1, &creg)
		gins(arm.ACMP, &s, &creg)

		//	MOVW.LO		bl<<s, al
		p1 = gregshift(arm.AMOVW, &bl, arm.SHIFT_LL, &s, &al)

		p1.Scond = arm.C_SCOND_LO

		//	MOVW.LO		bh<<s, ah
		p1 = gregshift(arm.AMOVW, &bh, arm.SHIFT_LL, &s, &ah)

		p1.Scond = arm.C_SCOND_LO

//.........這裏部分代碼省略.........
		gc.TFLOAT64<<16 | gc.TUINT8:
		cvt = gc.Types[gc.TINT32]

		goto hard

		// convert via int64.
	case gc.TFLOAT32<<16 | gc.TUINT32,
		gc.TFLOAT64<<16 | gc.TUINT32:
		cvt = gc.Types[gc.TINT64]

		goto hard

		// algorithm is:
	//	if small enough, use native float64 -> int64 conversion.
	//	otherwise, subtract 2^63, convert, and add it back.
	case gc.TFLOAT32<<16 | gc.TUINT64,
		gc.TFLOAT64<<16 | gc.TUINT64:
		a := x86.ACVTTSS2SQ

		if ft == gc.TFLOAT64 {
			a = x86.ACVTTSD2SQ
		}
		bignodes()
		var r1 gc.Node
		gc.Regalloc(&r1, gc.Types[ft], nil)
		var r2 gc.Node
		gc.Regalloc(&r2, gc.Types[tt], t)
		var r3 gc.Node
		gc.Regalloc(&r3, gc.Types[ft], nil)
		var r4 gc.Node
		gc.Regalloc(&r4, gc.Types[tt], nil)
		gins(optoas(gc.OAS, f.Type), f, &r1)
		gins(optoas(gc.OCMP, f.Type), &bigf, &r1)
		p1 := gc.Gbranch(optoas(gc.OLE, f.Type), nil, +1)
		gins(a, &r1, &r2)
		p2 := gc.Gbranch(obj.AJMP, nil, 0)
		gc.Patch(p1, gc.Pc)
		gins(optoas(gc.OAS, f.Type), &bigf, &r3)
		gins(optoas(gc.OSUB, f.Type), &r3, &r1)
		gins(a, &r1, &r2)
		gins(x86.AMOVQ, &bigi, &r4)
		gins(x86.AXORQ, &r4, &r2)
		gc.Patch(p2, gc.Pc)
		gmove(&r2, t)
		gc.Regfree(&r4)
		gc.Regfree(&r3)
		gc.Regfree(&r2)
		gc.Regfree(&r1)
		return

		/*
		 * integer to float
		 */
	case gc.TINT32<<16 | gc.TFLOAT32:
		a = x86.ACVTSL2SS

		goto rdst

	case gc.TINT32<<16 | gc.TFLOAT64:
		a = x86.ACVTSL2SD
		goto rdst

	case gc.TINT64<<16 | gc.TFLOAT32:
		a = x86.ACVTSQ2SS
		goto rdst

func clearfat(nl *gc.Node) {
	/* clear a fat object */
	if gc.Debug['g'] != 0 {
		fmt.Printf("clearfat %v (%v, size: %d)\n", nl, nl.Type, nl.Type.Width)
	}

	w := uint64(uint64(nl.Type.Width))

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

	c := uint64(w % 8) // bytes
	q := uint64(w / 8) // dwords

	if gc.Reginuse(ppc64.REGRT1) {
		gc.Fatalf("%v in use during clearfat", obj.Rconv(ppc64.REGRT1))
	}

	var r0 gc.Node
	gc.Nodreg(&r0, gc.Types[gc.TUINT64], ppc64.REGZERO)
	var dst gc.Node
	gc.Nodreg(&dst, gc.Types[gc.Tptr], ppc64.REGRT1)
	gc.Regrealloc(&dst)
	gc.Agen(nl, &dst)

	var boff uint64
	if q > 128 {
		p := gins(ppc64.ASUB, nil, &dst)
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = 8

		var end gc.Node
		gc.Regalloc(&end, gc.Types[gc.Tptr], nil)
		p = gins(ppc64.AMOVD, &dst, &end)
		p.From.Type = obj.TYPE_ADDR
		p.From.Offset = int64(q * 8)

		p = gins(ppc64.AMOVDU, &r0, &dst)
		p.To.Type = obj.TYPE_MEM
		p.To.Offset = 8
		pl := (*obj.Prog)(p)

		p = gins(ppc64.ACMP, &dst, &end)
		gc.Patch(gc.Gbranch(ppc64.ABNE, nil, 0), pl)

		gc.Regfree(&end)

		// The loop leaves R3 on the last zeroed dword
		boff = 8
	} else if q >= 4 {
		p := gins(ppc64.ASUB, nil, &dst)
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = 8
		f := (*gc.Node)(gc.Sysfunc("duffzero"))
		p = gins(obj.ADUFFZERO, nil, f)
		gc.Afunclit(&p.To, f)

		// 4 and 128 = magic constants: see ../../runtime/asm_ppc64x.s
		p.To.Offset = int64(4 * (128 - q))

		// duffzero leaves R3 on the last zeroed dword
		boff = 8
	} else {
		var p *obj.Prog
		for t := uint64(0); t < q; t++ {
			p = gins(ppc64.AMOVD, &r0, &dst)
			p.To.Type = obj.TYPE_MEM
			p.To.Offset = int64(8 * t)
		}

		boff = 8 * q
	}

	var p *obj.Prog
	for t := uint64(0); t < c; t++ {
		p = gins(ppc64.AMOVB, &r0, &dst)
		p.To.Type = obj.TYPE_MEM
		p.To.Offset = int64(t + boff)
	}

	gc.Regfree(&dst)
}

//.........這裏部分代碼省略.........

		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)
		gc.Agenr(n, &src, nil)
	}

	var tmp gc.Node
	gc.Regalloc(&tmp, gc.Types[gc.TUINT32], nil)

	// set up end marker
	var nend gc.Node

	if c >= 4 {
		gc.Regalloc(&nend, gc.Types[gc.TUINT32], nil)

		p := gins(arm.AMOVW, &src, &nend)
		p.From.Type = obj.TYPE_ADDR
		if dir < 0 {
			p.From.Offset = int64(dir)
		} else {
			p.From.Offset = w
		}
	}

	// move src and dest to the end of block if necessary
	if dir < 0 {
		p := gins(arm.AMOVW, &src, &src)
		p.From.Type = obj.TYPE_ADDR
		p.From.Offset = w + int64(dir)

		p = gins(arm.AMOVW, &dst, &dst)
		p.From.Type = obj.TYPE_ADDR
		p.From.Offset = w + int64(dir)
	}

	// move
	if c >= 4 {
		p := gins(op, &src, &tmp)
		p.From.Type = obj.TYPE_MEM
		p.From.Offset = int64(dir)
		p.Scond |= arm.C_PBIT
		ploop := p

		p = gins(op, &tmp, &dst)
		p.To.Type = obj.TYPE_MEM
		p.To.Offset = int64(dir)
		p.Scond |= arm.C_PBIT

		p = gins(arm.ACMP, &src, nil)
		raddr(&nend, p)

		gc.Patch(gc.Gbranch(arm.ABNE, nil, 0), ploop)
		gc.Regfree(&nend)
	} else {
		var p *obj.Prog
		for ; c > 0; c-- {
			p = gins(op, &src, &tmp)
			p.From.Type = obj.TYPE_MEM
			p.From.Offset = int64(dir)
			p.Scond |= arm.C_PBIT

			p = gins(op, &tmp, &dst)
			p.To.Type = obj.TYPE_MEM
			p.To.Offset = int64(dir)
			p.Scond |= arm.C_PBIT
		}
	}

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

/*
 * generate shift according to op, one of:
 *	res = nl << nr
 *	res = nl >> nr
 */
func cgen_shift(op gc.Op, bounded bool, nl *gc.Node, nr *gc.Node, res *gc.Node) {
	if nl.Type.Width > 4 {
		gc.Fatalf("cgen_shift %v", nl.Type)
	}

	w := int(nl.Type.Width * 8)

	a := optoas(op, nl.Type)

	if nr.Op == gc.OLITERAL {
		var n2 gc.Node
		gc.Tempname(&n2, nl.Type)
		gc.Cgen(nl, &n2)
		var n1 gc.Node
		gc.Regalloc(&n1, nl.Type, res)
		gmove(&n2, &n1)
		sc := uint64(nr.Int())
		if sc >= uint64(nl.Type.Width*8) {
			// large shift gets 2 shifts by width-1
			gins(a, ncon(uint32(w)-1), &n1)

			gins(a, ncon(uint32(w)-1), &n1)
		} else {
			gins(a, nr, &n1)
		}
		gmove(&n1, res)
		gc.Regfree(&n1)
		return
	}

	var oldcx gc.Node
	var cx gc.Node
	gc.Nodreg(&cx, gc.Types[gc.TUINT32], x86.REG_CX)
	if gc.GetReg(x86.REG_CX) > 1 && !gc.Samereg(&cx, res) {
		gc.Tempname(&oldcx, gc.Types[gc.TUINT32])
		gmove(&cx, &oldcx)
	}

	var n1 gc.Node
	var nt gc.Node
	if nr.Type.Width > 4 {
		gc.Tempname(&nt, nr.Type)
		n1 = nt
	} else {
		gc.Nodreg(&n1, gc.Types[gc.TUINT32], x86.REG_CX)
		gc.Regalloc(&n1, nr.Type, &n1) // to hold the shift type in CX
	}

	var n2 gc.Node
	if gc.Samereg(&cx, res) {
		gc.Regalloc(&n2, nl.Type, nil)
	} else {
		gc.Regalloc(&n2, nl.Type, res)
	}
	if nl.Ullman >= nr.Ullman {
		gc.Cgen(nl, &n2)
		gc.Cgen(nr, &n1)
	} else {
		gc.Cgen(nr, &n1)
		gc.Cgen(nl, &n2)
	}

	// test and fix up large shifts
	if bounded {
		if nr.Type.Width > 4 {
			// delayed reg alloc
			gc.Nodreg(&n1, gc.Types[gc.TUINT32], x86.REG_CX)

			gc.Regalloc(&n1, gc.Types[gc.TUINT32], &n1) // to hold the shift type in CX
			var lo gc.Node
			var hi gc.Node
			split64(&nt, &lo, &hi)
			gmove(&lo, &n1)
			splitclean()
		}
	} else {
		var p1 *obj.Prog
		if nr.Type.Width > 4 {
			// delayed reg alloc
			gc.Nodreg(&n1, gc.Types[gc.TUINT32], x86.REG_CX)

			gc.Regalloc(&n1, gc.Types[gc.TUINT32], &n1) // to hold the shift type in CX
			var lo gc.Node
			var hi gc.Node
			split64(&nt, &lo, &hi)
			gmove(&lo, &n1)
			gins(optoas(gc.OCMP, gc.Types[gc.TUINT32]), &hi, ncon(0))
			p2 := gc.Gbranch(optoas(gc.ONE, gc.Types[gc.TUINT32]), nil, +1)
			gins(optoas(gc.OCMP, gc.Types[gc.TUINT32]), &n1, ncon(uint32(w)))
			p1 = gc.Gbranch(optoas(gc.OLT, gc.Types[gc.TUINT32]), nil, +1)
			splitclean()
			gc.Patch(p2, gc.Pc)
		} else {
			gins(optoas(gc.OCMP, nr.Type), &n1, ncon(uint32(w)))
			p1 = gc.Gbranch(optoas(gc.OLT, gc.Types[gc.TUINT32]), nil, +1)
//.........這裏部分代碼省略.........

func bgen_float(n *gc.Node, wantTrue bool, likely int, to *obj.Prog) {
	nl := n.Left
	nr := n.Right
	op := n.Op
	if !wantTrue {
		// brcom is not valid on floats when NaN is involved.
		p1 := gc.Gbranch(obj.AJMP, nil, 0)
		p2 := gc.Gbranch(obj.AJMP, nil, 0)
		gc.Patch(p1, gc.Pc)

		// No need to avoid re-genning ninit.
		bgen_float(n, true, -likely, p2)

		gc.Patch(gc.Gbranch(obj.AJMP, nil, 0), to)
		gc.Patch(p2, gc.Pc)
		return
	}

	if gc.Thearch.Use387 {
		op = gc.Brrev(op) // because the args are stacked
		if op == gc.OGE || op == gc.OGT {
			// only < and <= work right with NaN; reverse if needed
			nl, nr = nr, nl
			op = gc.Brrev(op)
		}

		var ax, n2, tmp gc.Node
		gc.Nodreg(&tmp, nr.Type, x86.REG_F0)
		gc.Nodreg(&n2, nr.Type, x86.REG_F0+1)
		gc.Nodreg(&ax, gc.Types[gc.TUINT16], x86.REG_AX)
		if gc.Simsimtype(nr.Type) == gc.TFLOAT64 {
			if nl.Ullman > nr.Ullman {
				gc.Cgen(nl, &tmp)
				gc.Cgen(nr, &tmp)
				gins(x86.AFXCHD, &tmp, &n2)
			} else {
				gc.Cgen(nr, &tmp)
				gc.Cgen(nl, &tmp)
			}
			gins(x86.AFUCOMPP, &tmp, &n2)
		} else {
			// TODO(rsc): The moves back and forth to memory
			// here are for truncating the value to 32 bits.
			// This handles 32-bit comparison but presumably
			// all the other ops have the same problem.
			// We need to figure out what the right general
			// solution is, besides telling people to use float64.
			var t1 gc.Node
			gc.Tempname(&t1, gc.Types[gc.TFLOAT32])

			var t2 gc.Node
			gc.Tempname(&t2, gc.Types[gc.TFLOAT32])
			gc.Cgen(nr, &t1)
			gc.Cgen(nl, &t2)
			gmove(&t2, &tmp)
			gins(x86.AFCOMFP, &t1, &tmp)
		}
		gins(x86.AFSTSW, nil, &ax)
		gins(x86.ASAHF, nil, nil)
	} else {
		// Not 387
		if !nl.Addable {
			nl = gc.CgenTemp(nl)
		}
		if !nr.Addable {
			nr = gc.CgenTemp(nr)
		}

		var n2 gc.Node
		gc.Regalloc(&n2, nr.Type, nil)
		gmove(nr, &n2)
		nr = &n2

		if nl.Op != gc.OREGISTER {
			var n3 gc.Node
			gc.Regalloc(&n3, nl.Type, nil)
			gmove(nl, &n3)
			nl = &n3
		}

		if op == gc.OGE || op == gc.OGT {
			// only < and <= work right with NopN; reverse if needed
			nl, nr = nr, nl
			op = gc.Brrev(op)
		}

		gins(foptoas(gc.OCMP, nr.Type, 0), nl, nr)
		if nl.Op == gc.OREGISTER {
			gc.Regfree(nl)
		}
		gc.Regfree(nr)
	}

	switch op {
	case gc.OEQ:
		// neither NE nor P
		p1 := gc.Gbranch(x86.AJNE, nil, -likely)
		p2 := gc.Gbranch(x86.AJPS, nil, -likely)
		gc.Patch(gc.Gbranch(obj.AJMP, nil, 0), to)
		gc.Patch(p1, gc.Pc)
//.........這裏部分代碼省略.........

/*
 * generate comparison of nl, nr, both 64-bit.
 * nl is memory; nr is constant or memory.
 */
func cmp64(nl *gc.Node, nr *gc.Node, op gc.Op, likely int, to *obj.Prog) {
	var lo1 gc.Node
	var hi1 gc.Node
	var lo2 gc.Node
	var hi2 gc.Node
	var r1 gc.Node
	var r2 gc.Node

	split64(nl, &lo1, &hi1)
	split64(nr, &lo2, &hi2)

	// compare most significant word;
	// if they differ, we're done.
	t := hi1.Type

	gc.Regalloc(&r1, gc.Types[gc.TINT32], nil)
	gc.Regalloc(&r2, gc.Types[gc.TINT32], nil)
	gins(arm.AMOVW, &hi1, &r1)
	gins(arm.AMOVW, &hi2, &r2)
	gins(arm.ACMP, &r1, &r2)
	gc.Regfree(&r1)
	gc.Regfree(&r2)

	var br *obj.Prog
	switch op {
	default:
		gc.Fatalf("cmp64 %v %v", gc.Oconv(int(op), 0), t)

		// cmp hi
	// bne L
	// cmp lo
	// beq to
	// L:
	case gc.OEQ:
		br = gc.Gbranch(arm.ABNE, nil, -likely)

		// cmp hi
	// bne to
	// cmp lo
	// bne to
	case gc.ONE:
		gc.Patch(gc.Gbranch(arm.ABNE, nil, likely), to)

		// cmp hi
	// bgt to
	// blt L
	// cmp lo
	// bge to (or bgt to)
	// L:
	case gc.OGE,
		gc.OGT:
		gc.Patch(gc.Gbranch(optoas(gc.OGT, t), nil, likely), to)

		br = gc.Gbranch(optoas(gc.OLT, t), nil, -likely)

		// cmp hi
	// blt to
	// bgt L
	// cmp lo
	// ble to (or jlt to)
	// L:
	case gc.OLE,
		gc.OLT:
		gc.Patch(gc.Gbranch(optoas(gc.OLT, t), nil, likely), to)

		br = gc.Gbranch(optoas(gc.OGT, t), nil, -likely)
	}

	// compare least significant word
	t = lo1.Type

	gc.Regalloc(&r1, gc.Types[gc.TINT32], nil)
	gc.Regalloc(&r2, gc.Types[gc.TINT32], nil)
	gins(arm.AMOVW, &lo1, &r1)
	gins(arm.AMOVW, &lo2, &r2)
	gins(arm.ACMP, &r1, &r2)
	gc.Regfree(&r1)
	gc.Regfree(&r2)

	// jump again
	gc.Patch(gc.Gbranch(optoas(op, t), nil, likely), to)

	// point first branch down here if appropriate
	if br != nil {
		gc.Patch(br, gc.Pc)
	}

	splitclean()
	splitclean()
}

//.........這裏部分代碼省略.........
			gins(x86.AFMOVLP, &r1, t)
		} else {
			gins(x86.AFMOVVP, &r1, t)
		}
		gins(x86.AFLDCW, &t1, nil)
		return

	case gc.TFLOAT32<<16 | gc.TUINT64,
		gc.TFLOAT64<<16 | gc.TUINT64:
		if !gc.Ismem(f) {
			cvt = f.Type
			goto hardmem
		}

		bignodes()
		var f0 gc.Node
		gc.Nodreg(&f0, gc.Types[ft], x86.REG_F0)
		var f1 gc.Node
		gc.Nodreg(&f1, gc.Types[ft], x86.REG_F0+1)
		var ax gc.Node
		gc.Nodreg(&ax, gc.Types[gc.TUINT16], x86.REG_AX)

		if ft == gc.TFLOAT32 {
			gins(x86.AFMOVF, f, &f0)
		} else {
			gins(x86.AFMOVD, f, &f0)
		}

		// if 0 > v { answer = 0 }
		gins(x86.AFMOVD, &zerof, &f0)
		gins(x86.AFUCOMP, &f0, &f1)
		gins(x86.AFSTSW, nil, &ax)
		gins(x86.ASAHF, nil, nil)
		p1 := gc.Gbranch(optoas(gc.OGT, gc.Types[tt]), nil, 0)

		// if 1<<64 <= v { answer = 0 too }
		gins(x86.AFMOVD, &two64f, &f0)

		gins(x86.AFUCOMP, &f0, &f1)
		gins(x86.AFSTSW, nil, &ax)
		gins(x86.ASAHF, nil, nil)
		p2 := gc.Gbranch(optoas(gc.OGT, gc.Types[tt]), nil, 0)
		gc.Patch(p1, gc.Pc)
		gins(x86.AFMOVVP, &f0, t) // don't care about t, but will pop the stack
		var thi gc.Node
		var tlo gc.Node
		split64(t, &tlo, &thi)
		gins(x86.AMOVL, ncon(0), &tlo)
		gins(x86.AMOVL, ncon(0), &thi)
		splitclean()
		p1 = gc.Gbranch(obj.AJMP, nil, 0)
		gc.Patch(p2, gc.Pc)

		// in range; algorithm is:
		//	if small enough, use native float64 -> int64 conversion.
		//	otherwise, subtract 2^63, convert, and add it back.

		// set round to zero mode during conversion
		var t1 gc.Node
		memname(&t1, gc.Types[gc.TUINT16])

		var t2 gc.Node
		memname(&t2, gc.Types[gc.TUINT16])
		gins(x86.AFSTCW, nil, &t1)
		gins(x86.AMOVW, ncon(0xf7f), &t2)
		gins(x86.AFLDCW, &t2, nil)