github.com/mdempsky/go@v0.0.0-20151201204031-5dd372bd1e70/src/cmd/internal/obj/x86/asm6.go

// Inferno utils/6l/span.c
// http://code.google.com/p/inferno-os/source/browse/utils/6l/span.c
//
//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
//	Portions Copyright © 1997-1999 Vita Nuova Limited
//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
//	Portions Copyright © 2004,2006 Bruce Ellis
//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
//	Portions Copyright © 2009 The Go Authors.  All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package x86

import (
	"cmd/internal/obj"
	"fmt"
	"log"
	"strings"
)

// Instruction layout.

const (
	// Loop alignment constants:
	// want to align loop entry to LoopAlign-byte boundary,
	// and willing to insert at most MaxLoopPad bytes of NOP to do so.
	// We define a loop entry as the target of a backward jump.
	//
	// gcc uses MaxLoopPad = 10 for its 'generic x86-64' config,
	// and it aligns all jump targets, not just backward jump targets.
	//
	// As of 6/1/2012, the effect of setting MaxLoopPad = 10 here
	// is very slight but negative, so the alignment is disabled by
	// setting MaxLoopPad = 0. The code is here for reference and
	// for future experiments.
	//
	LoopAlign  = 16
	MaxLoopPad = 0
	FuncAlign  = 16
)

type Optab struct {
	as     int16
	ytab   []ytab
	prefix uint8
	op     [23]uint8
}

type ytab struct {
	from    uint8
	from3   uint8
	to      uint8
	zcase   uint8
	zoffset uint8
}

type Movtab struct {
	as   int16
	ft   uint8
	f3t  uint8
	tt   uint8
	code uint8
	op   [4]uint8
}

const (
	Yxxx = iota
	Ynone
	Yi0 // $0
	Yi1 // $1
	Yi8 // $x, x fits in int8
	Yu8 // $x, x fits in uint8
	Yu7 // $x, x in 0..127 (fits in both int8 and uint8)
	Ys32
	Yi32
	Yi64
	Yiauto
	Yal
	Ycl
	Yax
	Ycx
	Yrb
	Yrl
	Yrl32 // Yrl on 32-bit system
	Yrf
	Yf0
	Yrx
	Ymb
	Yml
	Ym
	Ybr
	Ycs
	Yss
	Yds
	Yes
	Yfs
	Ygs
	Ygdtr
	Yidtr
	Yldtr
	Ymsw
	Ytask
	Ycr0
	Ycr1
	Ycr2
	Ycr3
	Ycr4
	Ycr5
	Ycr6
	Ycr7
	Ycr8
	Ydr0
	Ydr1
	Ydr2
	Ydr3
	Ydr4
	Ydr5
	Ydr6
	Ydr7
	Ytr0
	Ytr1
	Ytr2
	Ytr3
	Ytr4
	Ytr5
	Ytr6
	Ytr7
	Ymr
	Ymm
	Yxr
	Yxm
	Ytls
	Ytextsize
	Yindir
	Ymax
)

const (
	Zxxx = iota
	Zlit
	Zlitm_r
	Z_rp
	Zbr
	Zcall
	Zcallcon
	Zcallduff
	Zcallind
	Zcallindreg
	Zib_
	Zib_rp
	Zibo_m
	Zibo_m_xm
	Zil_
	Zil_rp
	Ziq_rp
	Zilo_m
	Zjmp
	Zjmpcon
	Zloop
	Zo_iw
	Zm_o
	Zm_r
	Zm2_r
	Zm_r_xm
	Zm_r_xm_vex
	Zm_r_i_xm
	Zm_r_3d
	Zm_r_xm_nr
	Zr_m_xm_nr
	Zibm_r /* mmx1,mmx2/mem64,imm8 */
	Zmb_r
	Zaut_r
	Zo_m
	Zo_m64
	Zpseudo
	Zr_m
	Zr_m_xm
	Zr_m_xm_vex
	Zr_r_r_vex
	Zrp_
	Z_ib
	Z_il
	Zm_ibo
	Zm_ilo
	Zib_rr
	Zil_rr
	Zclr
	Zbyte
	Zmax
)

const (
	Px    = 0
	Px1   = 1    // symbolic; exact value doesn't matter
	P32   = 0x32 /* 32-bit only */
	Pe    = 0x66 /* operand escape */
	Pm    = 0x0f /* 2byte opcode escape */
	Pq    = 0xff /* both escapes: 66 0f */
	Pb    = 0xfe /* byte operands */
	Pf2   = 0xf2 /* xmm escape 1: f2 0f */
	Pf3   = 0xf3 /* xmm escape 2: f3 0f */
	Pq3   = 0x67 /* xmm escape 3: 66 48 0f */
	Pvex1 = 0xc5 /* 66.0f escape, vex encoding */
	Pvex2 = 0xc6 /* f3.0f escape, vex encoding */
	Pvex3 = 0xc7 /* 66.0f38 escape, vex encoding */
	Pw    = 0x48 /* Rex.w */
	Pw8   = 0x90 // symbolic; exact value doesn't matter
	Py    = 0x80 /* defaults to 64-bit mode */
	Py1   = 0x81 // symbolic; exact value doesn't matter
	Py3   = 0x83 // symbolic; exact value doesn't matter

	Rxw = 1 << 3 /* =1, 64-bit operand size */
	Rxr = 1 << 2 /* extend modrm reg */
	Rxx = 1 << 1 /* extend sib index */
	Rxb = 1 << 0 /* extend modrm r/m, sib base, or opcode reg */
)

var ycover [Ymax * Ymax]uint8

var reg [MAXREG]int

var regrex [MAXREG + 1]int

var ynone = []ytab{
	{Ynone, Ynone, Ynone, Zlit, 1},
}

var ytext = []ytab{
	{Ymb, Ynone, Ytextsize, Zpseudo, 0},
	{Ymb, Yi32, Ytextsize, Zpseudo, 1},
}

var ynop = []ytab{
	{Ynone, Ynone, Ynone, Zpseudo, 0},
	{Ynone, Ynone, Yiauto, Zpseudo, 0},
	{Ynone, Ynone, Yml, Zpseudo, 0},
	{Ynone, Ynone, Yrf, Zpseudo, 0},
	{Ynone, Ynone, Yxr, Zpseudo, 0},
	{Yiauto, Ynone, Ynone, Zpseudo, 0},
	{Yml, Ynone, Ynone, Zpseudo, 0},
	{Yrf, Ynone, Ynone, Zpseudo, 0},
	{Yxr, Ynone, Ynone, Zpseudo, 1},
}

var yfuncdata = []ytab{
	{Yi32, Ynone, Ym, Zpseudo, 0},
}

var ypcdata = []ytab{
	{Yi32, Ynone, Yi32, Zpseudo, 0},
}

var yxorb = []ytab{
	{Yi32, Ynone, Yal, Zib_, 1},
	{Yi32, Ynone, Ymb, Zibo_m, 2},
	{Yrb, Ynone, Ymb, Zr_m, 1},
	{Ymb, Ynone, Yrb, Zm_r, 1},
}

var yxorl = []ytab{
	{Yi8, Ynone, Yml, Zibo_m, 2},
	{Yi32, Ynone, Yax, Zil_, 1},
	{Yi32, Ynone, Yml, Zilo_m, 2},
	{Yrl, Ynone, Yml, Zr_m, 1},
	{Yml, Ynone, Yrl, Zm_r, 1},
}

var yaddl = []ytab{
	{Yi8, Ynone, Yml, Zibo_m, 2},
	{Yi32, Ynone, Yax, Zil_, 1},
	{Yi32, Ynone, Yml, Zilo_m, 2},
	{Yrl, Ynone, Yml, Zr_m, 1},
	{Yml, Ynone, Yrl, Zm_r, 1},
}

var yincb = []ytab{
	{Ynone, Ynone, Ymb, Zo_m, 2},
}

var yincw = []ytab{
	{Ynone, Ynone, Yml, Zo_m, 2},
}

var yincl = []ytab{
	{Ynone, Ynone, Yrl, Z_rp, 1},
	{Ynone, Ynone, Yml, Zo_m, 2},
}

var yincq = []ytab{
	{Ynone, Ynone, Yml, Zo_m, 2},
}

var ycmpb = []ytab{
	{Yal, Ynone, Yi32, Z_ib, 1},
	{Ymb, Ynone, Yi32, Zm_ibo, 2},
	{Ymb, Ynone, Yrb, Zm_r, 1},
	{Yrb, Ynone, Ymb, Zr_m, 1},
}

var ycmpl = []ytab{
	{Yml, Ynone, Yi8, Zm_ibo, 2},
	{Yax, Ynone, Yi32, Z_il, 1},
	{Yml, Ynone, Yi32, Zm_ilo, 2},
	{Yml, Ynone, Yrl, Zm_r, 1},
	{Yrl, Ynone, Yml, Zr_m, 1},
}

var yshb = []ytab{
	{Yi1, Ynone, Ymb, Zo_m, 2},
	{Yi32, Ynone, Ymb, Zibo_m, 2},
	{Ycx, Ynone, Ymb, Zo_m, 2},
}

var yshl = []ytab{
	{Yi1, Ynone, Yml, Zo_m, 2},
	{Yi32, Ynone, Yml, Zibo_m, 2},
	{Ycl, Ynone, Yml, Zo_m, 2},
	{Ycx, Ynone, Yml, Zo_m, 2},
}

var ytestb = []ytab{
	{Yi32, Ynone, Yal, Zib_, 1},
	{Yi32, Ynone, Ymb, Zibo_m, 2},
	{Yrb, Ynone, Ymb, Zr_m, 1},
	{Ymb, Ynone, Yrb, Zm_r, 1},
}

var ytestl = []ytab{
	{Yi32, Ynone, Yax, Zil_, 1},
	{Yi32, Ynone, Yml, Zilo_m, 2},
	{Yrl, Ynone, Yml, Zr_m, 1},
	{Yml, Ynone, Yrl, Zm_r, 1},
}

var ymovb = []ytab{
	{Yrb, Ynone, Ymb, Zr_m, 1},
	{Ymb, Ynone, Yrb, Zm_r, 1},
	{Yi32, Ynone, Yrb, Zib_rp, 1},
	{Yi32, Ynone, Ymb, Zibo_m, 2},
}

var ymbs = []ytab{
	{Ymb, Ynone, Ynone, Zm_o, 2},
}

var ybtl = []ytab{
	{Yi8, Ynone, Yml, Zibo_m, 2},
	{Yrl, Ynone, Yml, Zr_m, 1},
}

var ymovw = []ytab{
	{Yrl, Ynone, Yml, Zr_m, 1},
	{Yml, Ynone, Yrl, Zm_r, 1},
	{Yi0, Ynone, Yrl, Zclr, 1},
	{Yi32, Ynone, Yrl, Zil_rp, 1},
	{Yi32, Ynone, Yml, Zilo_m, 2},
	{Yiauto, Ynone, Yrl, Zaut_r, 2},
}

var ymovl = []ytab{
	{Yrl, Ynone, Yml, Zr_m, 1},
	{Yml, Ynone, Yrl, Zm_r, 1},
	{Yi0, Ynone, Yrl, Zclr, 1},
	{Yi32, Ynone, Yrl, Zil_rp, 1},
	{Yi32, Ynone, Yml, Zilo_m, 2},
	{Yml, Ynone, Ymr, Zm_r_xm, 1}, // MMX MOVD
	{Ymr, Ynone, Yml, Zr_m_xm, 1}, // MMX MOVD
	{Yml, Ynone, Yxr, Zm_r_xm, 2}, // XMM MOVD (32 bit)
	{Yxr, Ynone, Yml, Zr_m_xm, 2}, // XMM MOVD (32 bit)
	{Yiauto, Ynone, Yrl, Zaut_r, 2},
}

var yret = []ytab{
	{Ynone, Ynone, Ynone, Zo_iw, 1},
	{Yi32, Ynone, Ynone, Zo_iw, 1},
}

var ymovq = []ytab{
	// valid in 32-bit mode
	{Ym, Ynone, Ymr, Zm_r_xm_nr, 1},  // 0x6f MMX MOVQ (shorter encoding)
	{Ymr, Ynone, Ym, Zr_m_xm_nr, 1},  // 0x7f MMX MOVQ
	{Yxr, Ynone, Ymr, Zm_r_xm_nr, 2}, // Pf2, 0xd6 MOVDQ2Q
	{Yxm, Ynone, Yxr, Zm_r_xm_nr, 2}, // Pf3, 0x7e MOVQ xmm1/m64 -> xmm2
	{Yxr, Ynone, Yxm, Zr_m_xm_nr, 2}, // Pe, 0xd6 MOVQ xmm1 -> xmm2/m64

	// valid only in 64-bit mode, usually with 64-bit prefix
	{Yrl, Ynone, Yml, Zr_m, 1},      // 0x89
	{Yml, Ynone, Yrl, Zm_r, 1},      // 0x8b
	{Yi0, Ynone, Yrl, Zclr, 1},      // 0x31
	{Ys32, Ynone, Yrl, Zilo_m, 2},   // 32 bit signed 0xc7,(0)
	{Yi64, Ynone, Yrl, Ziq_rp, 1},   // 0xb8 -- 32/64 bit immediate
	{Yi32, Ynone, Yml, Zilo_m, 2},   // 0xc7,(0)
	{Ymm, Ynone, Ymr, Zm_r_xm, 1},   // 0x6e MMX MOVD
	{Ymr, Ynone, Ymm, Zr_m_xm, 1},   // 0x7e MMX MOVD
	{Yml, Ynone, Yxr, Zm_r_xm, 2},   // Pe, 0x6e MOVD xmm load
	{Yxr, Ynone, Yml, Zr_m_xm, 2},   // Pe, 0x7e MOVD xmm store
	{Yiauto, Ynone, Yrl, Zaut_r, 1}, // 0 built-in LEAQ
}

var ym_rl = []ytab{
	{Ym, Ynone, Yrl, Zm_r, 1},
}

var yrl_m = []ytab{
	{Yrl, Ynone, Ym, Zr_m, 1},
}

var ymb_rl = []ytab{
	{Ymb, Ynone, Yrl, Zmb_r, 1},
}

var yml_rl = []ytab{
	{Yml, Ynone, Yrl, Zm_r, 1},
}

var yrl_ml = []ytab{
	{Yrl, Ynone, Yml, Zr_m, 1},
}

var yml_mb = []ytab{
	{Yrb, Ynone, Ymb, Zr_m, 1},
	{Ymb, Ynone, Yrb, Zm_r, 1},
}

var yrb_mb = []ytab{
	{Yrb, Ynone, Ymb, Zr_m, 1},
}

var yxchg = []ytab{
	{Yax, Ynone, Yrl, Z_rp, 1},
	{Yrl, Ynone, Yax, Zrp_, 1},
	{Yrl, Ynone, Yml, Zr_m, 1},
	{Yml, Ynone, Yrl, Zm_r, 1},
}

var ydivl = []ytab{
	{Yml, Ynone, Ynone, Zm_o, 2},
}

var ydivb = []ytab{
	{Ymb, Ynone, Ynone, Zm_o, 2},
}

var yimul = []ytab{
	{Yml, Ynone, Ynone, Zm_o, 2},
	{Yi8, Ynone, Yrl, Zib_rr, 1},
	{Yi32, Ynone, Yrl, Zil_rr, 1},
	{Yml, Ynone, Yrl, Zm_r, 2},
}

var yimul3 = []ytab{
	{Yi8, Yml, Yrl, Zibm_r, 2},
}

var ybyte = []ytab{
	{Yi64, Ynone, Ynone, Zbyte, 1},
}

var yin = []ytab{
	{Yi32, Ynone, Ynone, Zib_, 1},
	{Ynone, Ynone, Ynone, Zlit, 1},
}

var yint = []ytab{
	{Yi32, Ynone, Ynone, Zib_, 1},
}

var ypushl = []ytab{
	{Yrl, Ynone, Ynone, Zrp_, 1},
	{Ym, Ynone, Ynone, Zm_o, 2},
	{Yi8, Ynone, Ynone, Zib_, 1},
	{Yi32, Ynone, Ynone, Zil_, 1},
}

var ypopl = []ytab{
	{Ynone, Ynone, Yrl, Z_rp, 1},
	{Ynone, Ynone, Ym, Zo_m, 2},
}

var ybswap = []ytab{
	{Ynone, Ynone, Yrl, Z_rp, 2},
}

var yscond = []ytab{
	{Ynone, Ynone, Ymb, Zo_m, 2},
}

var yjcond = []ytab{
	{Ynone, Ynone, Ybr, Zbr, 0},
	{Yi0, Ynone, Ybr, Zbr, 0},
	{Yi1, Ynone, Ybr, Zbr, 1},
}

var yloop = []ytab{
	{Ynone, Ynone, Ybr, Zloop, 1},
}

var ycall = []ytab{
	{Ynone, Ynone, Yml, Zcallindreg, 0},
	{Yrx, Ynone, Yrx, Zcallindreg, 2},
	{Ynone, Ynone, Yindir, Zcallind, 2},
	{Ynone, Ynone, Ybr, Zcall, 0},
	{Ynone, Ynone, Yi32, Zcallcon, 1},
}

var yduff = []ytab{
	{Ynone, Ynone, Yi32, Zcallduff, 1},
}

var yjmp = []ytab{
	{Ynone, Ynone, Yml, Zo_m64, 2},
	{Ynone, Ynone, Ybr, Zjmp, 0},
	{Ynone, Ynone, Yi32, Zjmpcon, 1},
}

var yfmvd = []ytab{
	{Ym, Ynone, Yf0, Zm_o, 2},
	{Yf0, Ynone, Ym, Zo_m, 2},
	{Yrf, Ynone, Yf0, Zm_o, 2},
	{Yf0, Ynone, Yrf, Zo_m, 2},
}

var yfmvdp = []ytab{
	{Yf0, Ynone, Ym, Zo_m, 2},
	{Yf0, Ynone, Yrf, Zo_m, 2},
}

var yfmvf = []ytab{
	{Ym, Ynone, Yf0, Zm_o, 2},
	{Yf0, Ynone, Ym, Zo_m, 2},
}

var yfmvx = []ytab{
	{Ym, Ynone, Yf0, Zm_o, 2},
}

var yfmvp = []ytab{
	{Yf0, Ynone, Ym, Zo_m, 2},
}

var yfcmv = []ytab{
	{Yrf, Ynone, Yf0, Zm_o, 2},
}

var yfadd = []ytab{
	{Ym, Ynone, Yf0, Zm_o, 2},
	{Yrf, Ynone, Yf0, Zm_o, 2},
	{Yf0, Ynone, Yrf, Zo_m, 2},
}

var yfaddp = []ytab{
	{Yf0, Ynone, Yrf, Zo_m, 2},
}

var yfxch = []ytab{
	{Yf0, Ynone, Yrf, Zo_m, 2},
	{Yrf, Ynone, Yf0, Zm_o, 2},
}

var ycompp = []ytab{
	{Yf0, Ynone, Yrf, Zo_m, 2}, /* botch is really f0,f1 */
}

var ystsw = []ytab{
	{Ynone, Ynone, Ym, Zo_m, 2},
	{Ynone, Ynone, Yax, Zlit, 1},
}

var ystcw = []ytab{
	{Ynone, Ynone, Ym, Zo_m, 2},
	{Ym, Ynone, Ynone, Zm_o, 2},
}

var ysvrs = []ytab{
	{Ynone, Ynone, Ym, Zo_m, 2},
	{Ym, Ynone, Ynone, Zm_o, 2},
}

var ymm = []ytab{
	{Ymm, Ynone, Ymr, Zm_r_xm, 1},
	{Yxm, Ynone, Yxr, Zm_r_xm, 2},
}

var yxm = []ytab{
	{Yxm, Ynone, Yxr, Zm_r_xm, 1},
}

var yxcvm1 = []ytab{
	{Yxm, Ynone, Yxr, Zm_r_xm, 2},
	{Yxm, Ynone, Ymr, Zm_r_xm, 2},
}

var yxcvm2 = []ytab{
	{Yxm, Ynone, Yxr, Zm_r_xm, 2},
	{Ymm, Ynone, Yxr, Zm_r_xm, 2},
}

/*
var yxmq = []ytab{
	{Yxm, Ynone, Yxr, Zm_r_xm, 2},
}
*/

var yxr = []ytab{
	{Yxr, Ynone, Yxr, Zm_r_xm, 1},
}

var yxr_ml = []ytab{
	{Yxr, Ynone, Yml, Zr_m_xm, 1},
}

var yxr_ml_vex = []ytab{
	{Yxr, Ynone, Yml, Zr_m_xm_vex, 1},
}

var yml_xr_vex = []ytab{
	{Yml, Ynone, Yxr, Zm_r_xm_vex, 1},
	{Yxr, Ynone, Yxr, Zm_r_xm_vex, 1},
}

var yxm_xm_xm = []ytab{
	{Yxr, Yxr, Yxr, Zr_r_r_vex, 1},
	{Yxm, Yxr, Yxr, Zr_r_r_vex, 1},
}

var ymr = []ytab{
	{Ymr, Ynone, Ymr, Zm_r, 1},
}

var ymr_ml = []ytab{
	{Ymr, Ynone, Yml, Zr_m_xm, 1},
}

var yxcmp = []ytab{
	{Yxm, Ynone, Yxr, Zm_r_xm, 1},
}

var yxcmpi = []ytab{
	{Yxm, Yxr, Yi8, Zm_r_i_xm, 2},
}

var yxmov_vex = []ytab{
	{Yxm, Ynone, Yxr, Zm_r_xm_vex, 1},
	{Yxr, Ynone, Yxm, Zr_m_xm_vex, 1},
}

var yxmov = []ytab{
	{Yxm, Ynone, Yxr, Zm_r_xm, 1},
	{Yxr, Ynone, Yxm, Zr_m_xm, 1},
}

var yxcvfl = []ytab{
	{Yxm, Ynone, Yrl, Zm_r_xm, 1},
}

var yxcvlf = []ytab{
	{Yml, Ynone, Yxr, Zm_r_xm, 1},
}

var yxcvfq = []ytab{
	{Yxm, Ynone, Yrl, Zm_r_xm, 2},
}

var yxcvqf = []ytab{
	{Yml, Ynone, Yxr, Zm_r_xm, 2},
}

var yps = []ytab{
	{Ymm, Ynone, Ymr, Zm_r_xm, 1},
	{Yi8, Ynone, Ymr, Zibo_m_xm, 2},
	{Yxm, Ynone, Yxr, Zm_r_xm, 2},
	{Yi8, Ynone, Yxr, Zibo_m_xm, 3},
}

var yxrrl = []ytab{
	{Yxr, Ynone, Yrl, Zm_r, 1},
}

var ymfp = []ytab{
	{Ymm, Ynone, Ymr, Zm_r_3d, 1},
}

var ymrxr = []ytab{
	{Ymr, Ynone, Yxr, Zm_r, 1},
	{Yxm, Ynone, Yxr, Zm_r_xm, 1},
}

var ymshuf = []ytab{
	{Yi8, Ymm, Ymr, Zibm_r, 2},
}

var ymshufb = []ytab{
	{Yxm, Ynone, Yxr, Zm2_r, 2},
}

var yxshuf = []ytab{
	{Yu8, Yxm, Yxr, Zibm_r, 2},
}

var yextrw = []ytab{
	{Yu8, Yxr, Yrl, Zibm_r, 2},
}

var yinsrw = []ytab{
	{Yu8, Yml, Yxr, Zibm_r, 2},
}

var yinsr = []ytab{
	{Yu8, Ymm, Yxr, Zibm_r, 3},
}

var ypsdq = []ytab{
	{Yi8, Ynone, Yxr, Zibo_m, 2},
}

var ymskb = []ytab{
	{Yxr, Ynone, Yrl, Zm_r_xm, 2},
	{Ymr, Ynone, Yrl, Zm_r_xm, 1},
}

var ymskb_vex = []ytab{
	{Yxr, Ynone, Yrl, Zm_r_xm_vex, 2},
}

var ycrc32l = []ytab{
	{Yml, Ynone, Yrl, Zlitm_r, 0},
}

var yprefetch = []ytab{
	{Ym, Ynone, Ynone, Zm_o, 2},
}

var yaes = []ytab{
	{Yxm, Ynone, Yxr, Zlitm_r, 2},
}

var yaes2 = []ytab{
	{Yu8, Yxm, Yxr, Zibm_r, 2},
}

var yxbegin = []ytab{
	{Ynone, Ynone, Ybr, Zjmp, 1},
}

var yxabort = []ytab{
	{Yu8, Ynone, Ynone, Zib_, 1},
}

/*
 * You are doasm, holding in your hand a Prog* with p->as set to, say, ACRC32,
 * and p->from and p->to as operands (Addr*).  The linker scans optab to find
 * the entry with the given p->as and then looks through the ytable for that
 * instruction (the second field in the optab struct) for a line whose first
 * two values match the Ytypes of the p->from and p->to operands.  The function
 * oclass in span.c computes the specific Ytype of an operand and then the set
 * of more general Ytypes that it satisfies is implied by the ycover table, set
 * up in instinit.  For example, oclass distinguishes the constants 0 and 1
 * from the more general 8-bit constants, but instinit says
 *
 *        ycover[Yi0*Ymax + Ys32] = 1;
 *        ycover[Yi1*Ymax + Ys32] = 1;
 *        ycover[Yi8*Ymax + Ys32] = 1;
 *
 * which means that Yi0, Yi1, and Yi8 all count as Ys32 (signed 32)
 * if that's what an instruction can handle.
 *
 * In parallel with the scan through the ytable for the appropriate line, there
 * is a z pointer that starts out pointing at the strange magic byte list in
 * the Optab struct.  With each step past a non-matching ytable line, z
 * advances by the 4th entry in the line.  When a matching line is found, that
 * z pointer has the extra data to use in laying down the instruction bytes.
 * The actual bytes laid down are a function of the 3rd entry in the line (that
 * is, the Ztype) and the z bytes.
 *
 * For example, let's look at AADDL.  The optab line says:
 *        { AADDL,        yaddl,  Px, 0x83,(00),0x05,0x81,(00),0x01,0x03 },
 *
 * and yaddl says
 *        uchar   yaddl[] =
 *        {
 *                Yi8,    Yml,    Zibo_m, 2,
 *                Yi32,   Yax,    Zil_,   1,
 *                Yi32,   Yml,    Zilo_m, 2,
 *                Yrl,    Yml,    Zr_m,   1,
 *                Yml,    Yrl,    Zm_r,   1,
 *                0
 *        };
 *
 * so there are 5 possible types of ADDL instruction that can be laid down, and
 * possible states used to lay them down (Ztype and z pointer, assuming z
 * points at {0x83,(00),0x05,0x81,(00),0x01,0x03}) are:
 *
 *        Yi8, Yml -> Zibo_m, z (0x83, 00)
 *        Yi32, Yax -> Zil_, z+2 (0x05)
 *        Yi32, Yml -> Zilo_m, z+2+1 (0x81, 0x00)
 *        Yrl, Yml -> Zr_m, z+2+1+2 (0x01)
 *        Yml, Yrl -> Zm_r, z+2+1+2+1 (0x03)
 *
 * The Pconstant in the optab line controls the prefix bytes to emit.  That's
 * relatively straightforward as this program goes.
 *
 * The switch on t[2] in doasm implements the various Z cases.  Zibo_m, for
 * example, is an opcode byte (z[0]) then an asmando (which is some kind of
 * encoded addressing mode for the Yml arg), and then a single immediate byte.
 * Zilo_m is the same but a long (32-bit) immediate.
 */
var optab =
/*	as, ytab, andproto, opcode */
[]Optab{
	{obj.AXXX, nil, 0, [23]uint8{}},
	{AAAA, ynone, P32, [23]uint8{0x37}},
	{AAAD, ynone, P32, [23]uint8{0xd5, 0x0a}},
	{AAAM, ynone, P32, [23]uint8{0xd4, 0x0a}},
	{AAAS, ynone, P32, [23]uint8{0x3f}},
	{AADCB, yxorb, Pb, [23]uint8{0x14, 0x80, 02, 0x10, 0x10}},
	{AADCL, yxorl, Px, [23]uint8{0x83, 02, 0x15, 0x81, 02, 0x11, 0x13}},
	{AADCQ, yxorl, Pw, [23]uint8{0x83, 02, 0x15, 0x81, 02, 0x11, 0x13}},
	{AADCW, yxorl, Pe, [23]uint8{0x83, 02, 0x15, 0x81, 02, 0x11, 0x13}},
	{AADDB, yxorb, Pb, [23]uint8{0x04, 0x80, 00, 0x00, 0x02}},
	{AADDL, yaddl, Px, [23]uint8{0x83, 00, 0x05, 0x81, 00, 0x01, 0x03}},
	{AADDPD, yxm, Pq, [23]uint8{0x58}},
	{AADDPS, yxm, Pm, [23]uint8{0x58}},
	{AADDQ, yaddl, Pw, [23]uint8{0x83, 00, 0x05, 0x81, 00, 0x01, 0x03}},
	{AADDSD, yxm, Pf2, [23]uint8{0x58}},
	{AADDSS, yxm, Pf3, [23]uint8{0x58}},
	{AADDW, yaddl, Pe, [23]uint8{0x83, 00, 0x05, 0x81, 00, 0x01, 0x03}},
	{AADJSP, nil, 0, [23]uint8{}},
	{AANDB, yxorb, Pb, [23]uint8{0x24, 0x80, 04, 0x20, 0x22}},
	{AANDL, yxorl, Px, [23]uint8{0x83, 04, 0x25, 0x81, 04, 0x21, 0x23}},
	{AANDNPD, yxm, Pq, [23]uint8{0x55}},
	{AANDNPS, yxm, Pm, [23]uint8{0x55}},
	{AANDPD, yxm, Pq, [23]uint8{0x54}},
	{AANDPS, yxm, Pq, [23]uint8{0x54}},
	{AANDQ, yxorl, Pw, [23]uint8{0x83, 04, 0x25, 0x81, 04, 0x21, 0x23}},
	{AANDW, yxorl, Pe, [23]uint8{0x83, 04, 0x25, 0x81, 04, 0x21, 0x23}},
	{AARPL, yrl_ml, P32, [23]uint8{0x63}},
	{ABOUNDL, yrl_m, P32, [23]uint8{0x62}},
	{ABOUNDW, yrl_m, Pe, [23]uint8{0x62}},
	{ABSFL, yml_rl, Pm, [23]uint8{0xbc}},
	{ABSFQ, yml_rl, Pw, [23]uint8{0x0f, 0xbc}},
	{ABSFW, yml_rl, Pq, [23]uint8{0xbc}},
	{ABSRL, yml_rl, Pm, [23]uint8{0xbd}},
	{ABSRQ, yml_rl, Pw, [23]uint8{0x0f, 0xbd}},
	{ABSRW, yml_rl, Pq, [23]uint8{0xbd}},
	{ABSWAPL, ybswap, Px, [23]uint8{0x0f, 0xc8}},
	{ABSWAPQ, ybswap, Pw, [23]uint8{0x0f, 0xc8}},
	{ABTCL, ybtl, Pm, [23]uint8{0xba, 07, 0xbb}},
	{ABTCQ, ybtl, Pw, [23]uint8{0x0f, 0xba, 07, 0x0f, 0xbb}},
	{ABTCW, ybtl, Pq, [23]uint8{0xba, 07, 0xbb}},
	{ABTL, ybtl, Pm, [23]uint8{0xba, 04, 0xa3}},
	{ABTQ, ybtl, Pw, [23]uint8{0x0f, 0xba, 04, 0x0f, 0xa3}},
	{ABTRL, ybtl, Pm, [23]uint8{0xba, 06, 0xb3}},
	{ABTRQ, ybtl, Pw, [23]uint8{0x0f, 0xba, 06, 0x0f, 0xb3}},
	{ABTRW, ybtl, Pq, [23]uint8{0xba, 06, 0xb3}},
	{ABTSL, ybtl, Pm, [23]uint8{0xba, 05, 0xab}},
	{ABTSQ, ybtl, Pw, [23]uint8{0x0f, 0xba, 05, 0x0f, 0xab}},
	{ABTSW, ybtl, Pq, [23]uint8{0xba, 05, 0xab}},
	{ABTW, ybtl, Pq, [23]uint8{0xba, 04, 0xa3}},
	{ABYTE, ybyte, Px, [23]uint8{1}},
	{obj.ACALL, ycall, Px, [23]uint8{0xff, 02, 0xff, 0x15, 0xe8}},
	{ACDQ, ynone, Px, [23]uint8{0x99}},
	{ACLC, ynone, Px, [23]uint8{0xf8}},
	{ACLD, ynone, Px, [23]uint8{0xfc}},
	{ACLI, ynone, Px, [23]uint8{0xfa}},
	{ACLTS, ynone, Pm, [23]uint8{0x06}},
	{ACMC, ynone, Px, [23]uint8{0xf5}},
	{ACMOVLCC, yml_rl, Pm, [23]uint8{0x43}},
	{ACMOVLCS, yml_rl, Pm, [23]uint8{0x42}},
	{ACMOVLEQ, yml_rl, Pm, [23]uint8{0x44}},
	{ACMOVLGE, yml_rl, Pm, [23]uint8{0x4d}},
	{ACMOVLGT, yml_rl, Pm, [23]uint8{0x4f}},
	{ACMOVLHI, yml_rl, Pm, [23]uint8{0x47}},
	{ACMOVLLE, yml_rl, Pm, [23]uint8{0x4e}},
	{ACMOVLLS, yml_rl, Pm, [23]uint8{0x46}},
	{ACMOVLLT, yml_rl, Pm, [23]uint8{0x4c}},
	{ACMOVLMI, yml_rl, Pm, [23]uint8{0x48}},
	{ACMOVLNE, yml_rl, Pm, [23]uint8{0x45}},
	{ACMOVLOC, yml_rl, Pm, [23]uint8{0x41}},
	{ACMOVLOS, yml_rl, Pm, [23]uint8{0x40}},
	{ACMOVLPC, yml_rl, Pm, [23]uint8{0x4b}},
	{ACMOVLPL, yml_rl, Pm, [23]uint8{0x49}},
	{ACMOVLPS, yml_rl, Pm, [23]uint8{0x4a}},
	{ACMOVQCC, yml_rl, Pw, [23]uint8{0x0f, 0x43}},
	{ACMOVQCS, yml_rl, Pw, [23]uint8{0x0f, 0x42}},
	{ACMOVQEQ, yml_rl, Pw, [23]uint8{0x0f, 0x44}},
	{ACMOVQGE, yml_rl, Pw, [23]uint8{0x0f, 0x4d}},
	{ACMOVQGT, yml_rl, Pw, [23]uint8{0x0f, 0x4f}},
	{ACMOVQHI, yml_rl, Pw, [23]uint8{0x0f, 0x47}},
	{ACMOVQLE, yml_rl, Pw, [23]uint8{0x0f, 0x4e}},
	{ACMOVQLS, yml_rl, Pw, [23]uint8{0x0f, 0x46}},
	{ACMOVQLT, yml_rl, Pw, [23]uint8{0x0f, 0x4c}},
	{ACMOVQMI, yml_rl, Pw, [23]uint8{0x0f, 0x48}},
	{ACMOVQNE, yml_rl, Pw, [23]uint8{0x0f, 0x45}},
	{ACMOVQOC, yml_rl, Pw, [23]uint8{0x0f, 0x41}},
	{ACMOVQOS, yml_rl, Pw, [23]uint8{0x0f, 0x40}},
	{ACMOVQPC, yml_rl, Pw, [23]uint8{0x0f, 0x4b}},
	{ACMOVQPL, yml_rl, Pw, [23]uint8{0x0f, 0x49}},
	{ACMOVQPS, yml_rl, Pw, [23]uint8{0x0f, 0x4a}},
	{ACMOVWCC, yml_rl, Pq, [23]uint8{0x43}},
	{ACMOVWCS, yml_rl, Pq, [23]uint8{0x42}},
	{ACMOVWEQ, yml_rl, Pq, [23]uint8{0x44}},
	{ACMOVWGE, yml_rl, Pq, [23]uint8{0x4d}},
	{ACMOVWGT, yml_rl, Pq, [23]uint8{0x4f}},
	{ACMOVWHI, yml_rl, Pq, [23]uint8{0x47}},
	{ACMOVWLE, yml_rl, Pq, [23]uint8{0x4e}},
	{ACMOVWLS, yml_rl, Pq, [23]uint8{0x46}},
	{ACMOVWLT, yml_rl, Pq, [23]uint8{0x4c}},
	{ACMOVWMI, yml_rl, Pq, [23]uint8{0x48}},
	{ACMOVWNE, yml_rl, Pq, [23]uint8{0x45}},
	{ACMOVWOC, yml_rl, Pq, [23]uint8{0x41}},
	{ACMOVWOS, yml_rl, Pq, [23]uint8{0x40}},
	{ACMOVWPC, yml_rl, Pq, [23]uint8{0x4b}},
	{ACMOVWPL, yml_rl, Pq, [23]uint8{0x49}},
	{ACMOVWPS, yml_rl, Pq, [23]uint8{0x4a}},
	{ACMPB, ycmpb, Pb, [23]uint8{0x3c, 0x80, 07, 0x38, 0x3a}},
	{ACMPL, ycmpl, Px, [23]uint8{0x83, 07, 0x3d, 0x81, 07, 0x39, 0x3b}},
	{ACMPPD, yxcmpi, Px, [23]uint8{Pe, 0xc2}},
	{ACMPPS, yxcmpi, Pm, [23]uint8{0xc2, 0}},
	{ACMPQ, ycmpl, Pw, [23]uint8{0x83, 07, 0x3d, 0x81, 07, 0x39, 0x3b}},
	{ACMPSB, ynone, Pb, [23]uint8{0xa6}},
	{ACMPSD, yxcmpi, Px, [23]uint8{Pf2, 0xc2}},
	{ACMPSL, ynone, Px, [23]uint8{0xa7}},
	{ACMPSQ, ynone, Pw, [23]uint8{0xa7}},
	{ACMPSS, yxcmpi, Px, [23]uint8{Pf3, 0xc2}},
	{ACMPSW, ynone, Pe, [23]uint8{0xa7}},
	{ACMPW, ycmpl, Pe, [23]uint8{0x83, 07, 0x3d, 0x81, 07, 0x39, 0x3b}},
	{ACOMISD, yxcmp, Pe, [23]uint8{0x2f}},
	{ACOMISS, yxcmp, Pm, [23]uint8{0x2f}},
	{ACPUID, ynone, Pm, [23]uint8{0xa2}},
	{ACVTPL2PD, yxcvm2, Px, [23]uint8{Pf3, 0xe6, Pe, 0x2a}},
	{ACVTPL2PS, yxcvm2, Pm, [23]uint8{0x5b, 0, 0x2a, 0}},
	{ACVTPD2PL, yxcvm1, Px, [23]uint8{Pf2, 0xe6, Pe, 0x2d}},
	{ACVTPD2PS, yxm, Pe, [23]uint8{0x5a}},
	{ACVTPS2PL, yxcvm1, Px, [23]uint8{Pe, 0x5b, Pm, 0x2d}},
	{ACVTPS2PD, yxm, Pm, [23]uint8{0x5a}},
	{API2FW, ymfp, Px, [23]uint8{0x0c}},
	{ACVTSD2SL, yxcvfl, Pf2, [23]uint8{0x2d}},
	{ACVTSD2SQ, yxcvfq, Pw, [23]uint8{Pf2, 0x2d}},
	{ACVTSD2SS, yxm, Pf2, [23]uint8{0x5a}},
	{ACVTSL2SD, yxcvlf, Pf2, [23]uint8{0x2a}},
	{ACVTSQ2SD, yxcvqf, Pw, [23]uint8{Pf2, 0x2a}},
	{ACVTSL2SS, yxcvlf, Pf3, [23]uint8{0x2a}},
	{ACVTSQ2SS, yxcvqf, Pw, [23]uint8{Pf3, 0x2a}},
	{ACVTSS2SD, yxm, Pf3, [23]uint8{0x5a}},
	{ACVTSS2SL, yxcvfl, Pf3, [23]uint8{0x2d}},
	{ACVTSS2SQ, yxcvfq, Pw, [23]uint8{Pf3, 0x2d}},
	{ACVTTPD2PL, yxcvm1, Px, [23]uint8{Pe, 0xe6, Pe, 0x2c}},
	{ACVTTPS2PL, yxcvm1, Px, [23]uint8{Pf3, 0x5b, Pm, 0x2c}},
	{ACVTTSD2SL, yxcvfl, Pf2, [23]uint8{0x2c}},
	{ACVTTSD2SQ, yxcvfq, Pw, [23]uint8{Pf2, 0x2c}},
	{ACVTTSS2SL, yxcvfl, Pf3, [23]uint8{0x2c}},
	{ACVTTSS2SQ, yxcvfq, Pw, [23]uint8{Pf3, 0x2c}},
	{ACWD, ynone, Pe, [23]uint8{0x99}},
	{ACQO, ynone, Pw, [23]uint8{0x99}},
	{ADAA, ynone, P32, [23]uint8{0x27}},
	{ADAS, ynone, P32, [23]uint8{0x2f}},
	{obj.ADATA, nil, 0, [23]uint8{}},
	{ADECB, yincb, Pb, [23]uint8{0xfe, 01}},
	{ADECL, yincl, Px1, [23]uint8{0x48, 0xff, 01}},
	{ADECQ, yincq, Pw, [23]uint8{0xff, 01}},
	{ADECW, yincw, Pe, [23]uint8{0xff, 01}},
	{ADIVB, ydivb, Pb, [23]uint8{0xf6, 06}},
	{ADIVL, ydivl, Px, [23]uint8{0xf7, 06}},
	{ADIVPD, yxm, Pe, [23]uint8{0x5e}},
	{ADIVPS, yxm, Pm, [23]uint8{0x5e}},
	{ADIVQ, ydivl, Pw, [23]uint8{0xf7, 06}},
	{ADIVSD, yxm, Pf2, [23]uint8{0x5e}},
	{ADIVSS, yxm, Pf3, [23]uint8{0x5e}},
	{ADIVW, ydivl, Pe, [23]uint8{0xf7, 06}},
	{AEMMS, ynone, Pm, [23]uint8{0x77}},
	{AENTER, nil, 0, [23]uint8{}}, /* botch */
	{AFXRSTOR, ysvrs, Pm, [23]uint8{0xae, 01, 0xae, 01}},
	{AFXSAVE, ysvrs, Pm, [23]uint8{0xae, 00, 0xae, 00}},
	{AFXRSTOR64, ysvrs, Pw, [23]uint8{0x0f, 0xae, 01, 0x0f, 0xae, 01}},
	{AFXSAVE64, ysvrs, Pw, [23]uint8{0x0f, 0xae, 00, 0x0f, 0xae, 00}},
	{obj.AGLOBL, nil, 0, [23]uint8{}},
	{AHLT, ynone, Px, [23]uint8{0xf4}},
	{AIDIVB, ydivb, Pb, [23]uint8{0xf6, 07}},
	{AIDIVL, ydivl, Px, [23]uint8{0xf7, 07}},
	{AIDIVQ, ydivl, Pw, [23]uint8{0xf7, 07}},
	{AIDIVW, ydivl, Pe, [23]uint8{0xf7, 07}},
	{AIMULB, ydivb, Pb, [23]uint8{0xf6, 05}},
	{AIMULL, yimul, Px, [23]uint8{0xf7, 05, 0x6b, 0x69, Pm, 0xaf}},
	{AIMULQ, yimul, Pw, [23]uint8{0xf7, 05, 0x6b, 0x69, Pm, 0xaf}},
	{AIMULW, yimul, Pe, [23]uint8{0xf7, 05, 0x6b, 0x69, Pm, 0xaf}},
	{AIMUL3Q, yimul3, Pw, [23]uint8{0x6b, 00}},
	{AINB, yin, Pb, [23]uint8{0xe4, 0xec}},
	{AINCB, yincb, Pb, [23]uint8{0xfe, 00}},
	{AINCL, yincl, Px1, [23]uint8{0x40, 0xff, 00}},
	{AINCQ, yincq, Pw, [23]uint8{0xff, 00}},
	{AINCW, yincw, Pe, [23]uint8{0xff, 00}},
	{AINL, yin, Px, [23]uint8{0xe5, 0xed}},
	{AINSB, ynone, Pb, [23]uint8{0x6c}},
	{AINSL, ynone, Px, [23]uint8{0x6d}},
	{AINSW, ynone, Pe, [23]uint8{0x6d}},
	{AINT, yint, Px, [23]uint8{0xcd}},
	{AINTO, ynone, P32, [23]uint8{0xce}},
	{AINW, yin, Pe, [23]uint8{0xe5, 0xed}},
	{AIRETL, ynone, Px, [23]uint8{0xcf}},
	{AIRETQ, ynone, Pw, [23]uint8{0xcf}},
	{AIRETW, ynone, Pe, [23]uint8{0xcf}},
	{AJCC, yjcond, Px, [23]uint8{0x73, 0x83, 00}},
	{AJCS, yjcond, Px, [23]uint8{0x72, 0x82}},
	{AJCXZL, yloop, Px, [23]uint8{0xe3}},
	{AJCXZW, yloop, Px, [23]uint8{0xe3}},
	{AJCXZQ, yloop, Px, [23]uint8{0xe3}},
	{AJEQ, yjcond, Px, [23]uint8{0x74, 0x84}},
	{AJGE, yjcond, Px, [23]uint8{0x7d, 0x8d}},
	{AJGT, yjcond, Px, [23]uint8{0x7f, 0x8f}},
	{AJHI, yjcond, Px, [23]uint8{0x77, 0x87}},
	{AJLE, yjcond, Px, [23]uint8{0x7e, 0x8e}},
	{AJLS, yjcond, Px, [23]uint8{0x76, 0x86}},
	{AJLT, yjcond, Px, [23]uint8{0x7c, 0x8c}},
	{AJMI, yjcond, Px, [23]uint8{0x78, 0x88}},
	{obj.AJMP, yjmp, Px, [23]uint8{0xff, 04, 0xeb, 0xe9}},
	{AJNE, yjcond, Px, [23]uint8{0x75, 0x85}},
	{AJOC, yjcond, Px, [23]uint8{0x71, 0x81, 00}},
	{AJOS, yjcond, Px, [23]uint8{0x70, 0x80, 00}},
	{AJPC, yjcond, Px, [23]uint8{0x7b, 0x8b}},
	{AJPL, yjcond, Px, [23]uint8{0x79, 0x89}},
	{AJPS, yjcond, Px, [23]uint8{0x7a, 0x8a}},
	{ALAHF, ynone, Px, [23]uint8{0x9f}},
	{ALARL, yml_rl, Pm, [23]uint8{0x02}},
	{ALARW, yml_rl, Pq, [23]uint8{0x02}},
	{ALDMXCSR, ysvrs, Pm, [23]uint8{0xae, 02, 0xae, 02}},
	{ALEAL, ym_rl, Px, [23]uint8{0x8d}},
	{ALEAQ, ym_rl, Pw, [23]uint8{0x8d}},
	{ALEAVEL, ynone, P32, [23]uint8{0xc9}},
	{ALEAVEQ, ynone, Py, [23]uint8{0xc9}},
	{ALEAVEW, ynone, Pe, [23]uint8{0xc9}},
	{ALEAW, ym_rl, Pe, [23]uint8{0x8d}},
	{ALOCK, ynone, Px, [23]uint8{0xf0}},
	{ALODSB, ynone, Pb, [23]uint8{0xac}},
	{ALODSL, ynone, Px, [23]uint8{0xad}},
	{ALODSQ, ynone, Pw, [23]uint8{0xad}},
	{ALODSW, ynone, Pe, [23]uint8{0xad}},
	{ALONG, ybyte, Px, [23]uint8{4}},
	{ALOOP, yloop, Px, [23]uint8{0xe2}},
	{ALOOPEQ, yloop, Px, [23]uint8{0xe1}},
	{ALOOPNE, yloop, Px, [23]uint8{0xe0}},
	{ALSLL, yml_rl, Pm, [23]uint8{0x03}},
	{ALSLW, yml_rl, Pq, [23]uint8{0x03}},
	{AMASKMOVOU, yxr, Pe, [23]uint8{0xf7}},
	{AMASKMOVQ, ymr, Pm, [23]uint8{0xf7}},
	{AMAXPD, yxm, Pe, [23]uint8{0x5f}},
	{AMAXPS, yxm, Pm, [23]uint8{0x5f}},
	{AMAXSD, yxm, Pf2, [23]uint8{0x5f}},
	{AMAXSS, yxm, Pf3, [23]uint8{0x5f}},
	{AMINPD, yxm, Pe, [23]uint8{0x5d}},
	{AMINPS, yxm, Pm, [23]uint8{0x5d}},
	{AMINSD, yxm, Pf2, [23]uint8{0x5d}},
	{AMINSS, yxm, Pf3, [23]uint8{0x5d}},
	{AMOVAPD, yxmov, Pe, [23]uint8{0x28, 0x29}},
	{AMOVAPS, yxmov, Pm, [23]uint8{0x28, 0x29}},
	{AMOVB, ymovb, Pb, [23]uint8{0x88, 0x8a, 0xb0, 0xc6, 00}},
	{AMOVBLSX, ymb_rl, Pm, [23]uint8{0xbe}},
	{AMOVBLZX, ymb_rl, Pm, [23]uint8{0xb6}},
	{AMOVBQSX, ymb_rl, Pw, [23]uint8{0x0f, 0xbe}},
	{AMOVBQZX, ymb_rl, Pm, [23]uint8{0xb6}},
	{AMOVBWSX, ymb_rl, Pq, [23]uint8{0xbe}},
	{AMOVBWZX, ymb_rl, Pq, [23]uint8{0xb6}},
	{AMOVO, yxmov, Pe, [23]uint8{0x6f, 0x7f}},
	{AMOVOU, yxmov, Pf3, [23]uint8{0x6f, 0x7f}},
	{AMOVHLPS, yxr, Pm, [23]uint8{0x12}},
	{AMOVHPD, yxmov, Pe, [23]uint8{0x16, 0x17}},
	{AMOVHPS, yxmov, Pm, [23]uint8{0x16, 0x17}},
	{AMOVL, ymovl, Px, [23]uint8{0x89, 0x8b, 0x31, 0xb8, 0xc7, 00, 0x6e, 0x7e, Pe, 0x6e, Pe, 0x7e, 0}},
	{AMOVLHPS, yxr, Pm, [23]uint8{0x16}},
	{AMOVLPD, yxmov, Pe, [23]uint8{0x12, 0x13}},
	{AMOVLPS, yxmov, Pm, [23]uint8{0x12, 0x13}},
	{AMOVLQSX, yml_rl, Pw, [23]uint8{0x63}},
	{AMOVLQZX, yml_rl, Px, [23]uint8{0x8b}},
	{AMOVMSKPD, yxrrl, Pq, [23]uint8{0x50}},
	{AMOVMSKPS, yxrrl, Pm, [23]uint8{0x50}},
	{AMOVNTO, yxr_ml, Pe, [23]uint8{0xe7}},
	{AMOVNTPD, yxr_ml, Pe, [23]uint8{0x2b}},
	{AMOVNTPS, yxr_ml, Pm, [23]uint8{0x2b}},
	{AMOVNTQ, ymr_ml, Pm, [23]uint8{0xe7}},
	{AMOVQ, ymovq, Pw8, [23]uint8{0x6f, 0x7f, Pf2, 0xd6, Pf3, 0x7e, Pe, 0xd6, 0x89, 0x8b, 0x31, 0xc7, 00, 0xb8, 0xc7, 00, 0x6e, 0x7e, Pe, 0x6e, Pe, 0x7e, 0}},
	{AMOVQOZX, ymrxr, Pf3, [23]uint8{0xd6, 0x7e}},
	{AMOVSB, ynone, Pb, [23]uint8{0xa4}},
	{AMOVSD, yxmov, Pf2, [23]uint8{0x10, 0x11}},
	{AMOVSL, ynone, Px, [23]uint8{0xa5}},
	{AMOVSQ, ynone, Pw, [23]uint8{0xa5}},
	{AMOVSS, yxmov, Pf3, [23]uint8{0x10, 0x11}},
	{AMOVSW, ynone, Pe, [23]uint8{0xa5}},
	{AMOVUPD, yxmov, Pe, [23]uint8{0x10, 0x11}},
	{AMOVUPS, yxmov, Pm, [23]uint8{0x10, 0x11}},
	{AMOVW, ymovw, Pe, [23]uint8{0x89, 0x8b, 0x31, 0xb8, 0xc7, 00, 0}},
	{AMOVWLSX, yml_rl, Pm, [23]uint8{0xbf}},
	{AMOVWLZX, yml_rl, Pm, [23]uint8{0xb7}},
	{AMOVWQSX, yml_rl, Pw, [23]uint8{0x0f, 0xbf}},
	{AMOVWQZX, yml_rl, Pw, [23]uint8{0x0f, 0xb7}},
	{AMULB, ydivb, Pb, [23]uint8{0xf6, 04}},
	{AMULL, ydivl, Px, [23]uint8{0xf7, 04}},
	{AMULPD, yxm, Pe, [23]uint8{0x59}},
	{AMULPS, yxm, Ym, [23]uint8{0x59}},
	{AMULQ, ydivl, Pw, [23]uint8{0xf7, 04}},
	{AMULSD, yxm, Pf2, [23]uint8{0x59}},
	{AMULSS, yxm, Pf3, [23]uint8{0x59}},
	{AMULW, ydivl, Pe, [23]uint8{0xf7, 04}},
	{ANEGB, yscond, Pb, [23]uint8{0xf6, 03}},
	{ANEGL, yscond, Px, [23]uint8{0xf7, 03}},
	{ANEGQ, yscond, Pw, [23]uint8{0xf7, 03}},
	{ANEGW, yscond, Pe, [23]uint8{0xf7, 03}},
	{obj.ANOP, ynop, Px, [23]uint8{0, 0}},
	{ANOTB, yscond, Pb, [23]uint8{0xf6, 02}},
	{ANOTL, yscond, Px, [23]uint8{0xf7, 02}}, // TODO(rsc): yscond is wrong here.
	{ANOTQ, yscond, Pw, [23]uint8{0xf7, 02}},
	{ANOTW, yscond, Pe, [23]uint8{0xf7, 02}},
	{AORB, yxorb, Pb, [23]uint8{0x0c, 0x80, 01, 0x08, 0x0a}},
	{AORL, yxorl, Px, [23]uint8{0x83, 01, 0x0d, 0x81, 01, 0x09, 0x0b}},
	{AORPD, yxm, Pq, [23]uint8{0x56}},
	{AORPS, yxm, Pm, [23]uint8{0x56}},
	{AORQ, yxorl, Pw, [23]uint8{0x83, 01, 0x0d, 0x81, 01, 0x09, 0x0b}},
	{AORW, yxorl, Pe, [23]uint8{0x83, 01, 0x0d, 0x81, 01, 0x09, 0x0b}},
	{AOUTB, yin, Pb, [23]uint8{0xe6, 0xee}},
	{AOUTL, yin, Px, [23]uint8{0xe7, 0xef}},
	{AOUTSB, ynone, Pb, [23]uint8{0x6e}},
	{AOUTSL, ynone, Px, [23]uint8{0x6f}},
	{AOUTSW, ynone, Pe, [23]uint8{0x6f}},
	{AOUTW, yin, Pe, [23]uint8{0xe7, 0xef}},
	{APACKSSLW, ymm, Py1, [23]uint8{0x6b, Pe, 0x6b}},
	{APACKSSWB, ymm, Py1, [23]uint8{0x63, Pe, 0x63}},
	{APACKUSWB, ymm, Py1, [23]uint8{0x67, Pe, 0x67}},
	{APADDB, ymm, Py1, [23]uint8{0xfc, Pe, 0xfc}},
	{APADDL, ymm, Py1, [23]uint8{0xfe, Pe, 0xfe}},
	{APADDQ, yxm, Pe, [23]uint8{0xd4}},
	{APADDSB, ymm, Py1, [23]uint8{0xec, Pe, 0xec}},
	{APADDSW, ymm, Py1, [23]uint8{0xed, Pe, 0xed}},
	{APADDUSB, ymm, Py1, [23]uint8{0xdc, Pe, 0xdc}},
	{APADDUSW, ymm, Py1, [23]uint8{0xdd, Pe, 0xdd}},
	{APADDW, ymm, Py1, [23]uint8{0xfd, Pe, 0xfd}},
	{APAND, ymm, Py1, [23]uint8{0xdb, Pe, 0xdb}},
	{APANDN, ymm, Py1, [23]uint8{0xdf, Pe, 0xdf}},
	{APAUSE, ynone, Px, [23]uint8{0xf3, 0x90}},
	{APAVGB, ymm, Py1, [23]uint8{0xe0, Pe, 0xe0}},
	{APAVGW, ymm, Py1, [23]uint8{0xe3, Pe, 0xe3}},
	{APCMPEQB, ymm, Py1, [23]uint8{0x74, Pe, 0x74}},
	{APCMPEQL, ymm, Py1, [23]uint8{0x76, Pe, 0x76}},
	{APCMPEQW, ymm, Py1, [23]uint8{0x75, Pe, 0x75}},
	{APCMPGTB, ymm, Py1, [23]uint8{0x64, Pe, 0x64}},
	{APCMPGTL, ymm, Py1, [23]uint8{0x66, Pe, 0x66}},
	{APCMPGTW, ymm, Py1, [23]uint8{0x65, Pe, 0x65}},
	{APEXTRW, yextrw, Pq, [23]uint8{0xc5, 00}},
	{APF2IL, ymfp, Px, [23]uint8{0x1d}},
	{APF2IW, ymfp, Px, [23]uint8{0x1c}},
	{API2FL, ymfp, Px, [23]uint8{0x0d}},
	{APFACC, ymfp, Px, [23]uint8{0xae}},
	{APFADD, ymfp, Px, [23]uint8{0x9e}},
	{APFCMPEQ, ymfp, Px, [23]uint8{0xb0}},
	{APFCMPGE, ymfp, Px, [23]uint8{0x90}},
	{APFCMPGT, ymfp, Px, [23]uint8{0xa0}},
	{APFMAX, ymfp, Px, [23]uint8{0xa4}},
	{APFMIN, ymfp, Px, [23]uint8{0x94}},
	{APFMUL, ymfp, Px, [23]uint8{0xb4}},
	{APFNACC, ymfp, Px, [23]uint8{0x8a}},
	{APFPNACC, ymfp, Px, [23]uint8{0x8e}},
	{APFRCP, ymfp, Px, [23]uint8{0x96}},
	{APFRCPIT1, ymfp, Px, [23]uint8{0xa6}},
	{APFRCPI2T, ymfp, Px, [23]uint8{0xb6}},
	{APFRSQIT1, ymfp, Px, [23]uint8{0xa7}},
	{APFRSQRT, ymfp, Px, [23]uint8{0x97}},
	{APFSUB, ymfp, Px, [23]uint8{0x9a}},
	{APFSUBR, ymfp, Px, [23]uint8{0xaa}},
	{APINSRW, yinsrw, Pq, [23]uint8{0xc4, 00}},
	{APINSRD, yinsr, Pq, [23]uint8{0x3a, 0x22, 00}},
	{APINSRQ, yinsr, Pq3, [23]uint8{0x3a, 0x22, 00}},
	{APMADDWL, ymm, Py1, [23]uint8{0xf5, Pe, 0xf5}},
	{APMAXSW, yxm, Pe, [23]uint8{0xee}},
	{APMAXUB, yxm, Pe, [23]uint8{0xde}},
	{APMINSW, yxm, Pe, [23]uint8{0xea}},
	{APMINUB, yxm, Pe, [23]uint8{0xda}},
	{APMOVMSKB, ymskb, Px, [23]uint8{Pe, 0xd7, 0xd7}},
	{APMULHRW, ymfp, Px, [23]uint8{0xb7}},
	{APMULHUW, ymm, Py1, [23]uint8{0xe4, Pe, 0xe4}},
	{APMULHW, ymm, Py1, [23]uint8{0xe5, Pe, 0xe5}},
	{APMULLW, ymm, Py1, [23]uint8{0xd5, Pe, 0xd5}},
	{APMULULQ, ymm, Py1, [23]uint8{0xf4, Pe, 0xf4}},
	{APOPAL, ynone, P32, [23]uint8{0x61}},
	{APOPAW, ynone, Pe, [23]uint8{0x61}},
	{APOPFL, ynone, P32, [23]uint8{0x9d}},
	{APOPFQ, ynone, Py, [23]uint8{0x9d}},
	{APOPFW, ynone, Pe, [23]uint8{0x9d}},
	{APOPL, ypopl, P32, [23]uint8{0x58, 0x8f, 00}},
	{APOPQ, ypopl, Py, [23]uint8{0x58, 0x8f, 00}},
	{APOPW, ypopl, Pe, [23]uint8{0x58, 0x8f, 00}},
	{APOR, ymm, Py1, [23]uint8{0xeb, Pe, 0xeb}},
	{APSADBW, yxm, Pq, [23]uint8{0xf6}},
	{APSHUFHW, yxshuf, Pf3, [23]uint8{0x70, 00}},
	{APSHUFL, yxshuf, Pq, [23]uint8{0x70, 00}},
	{APSHUFLW, yxshuf, Pf2, [23]uint8{0x70, 00}},
	{APSHUFW, ymshuf, Pm, [23]uint8{0x70, 00}},
	{APSHUFB, ymshufb, Pq, [23]uint8{0x38, 0x00}},
	{APSLLO, ypsdq, Pq, [23]uint8{0x73, 07}},
	{APSLLL, yps, Py3, [23]uint8{0xf2, 0x72, 06, Pe, 0xf2, Pe, 0x72, 06}},
	{APSLLQ, yps, Py3, [23]uint8{0xf3, 0x73, 06, Pe, 0xf3, Pe, 0x73, 06}},
	{APSLLW, yps, Py3, [23]uint8{0xf1, 0x71, 06, Pe, 0xf1, Pe, 0x71, 06}},
	{APSRAL, yps, Py3, [23]uint8{0xe2, 0x72, 04, Pe, 0xe2, Pe, 0x72, 04}},
	{APSRAW, yps, Py3, [23]uint8{0xe1, 0x71, 04, Pe, 0xe1, Pe, 0x71, 04}},
	{APSRLO, ypsdq, Pq, [23]uint8{0x73, 03}},
	{APSRLL, yps, Py3, [23]uint8{0xd2, 0x72, 02, Pe, 0xd2, Pe, 0x72, 02}},
	{APSRLQ, yps, Py3, [23]uint8{0xd3, 0x73, 02, Pe, 0xd3, Pe, 0x73, 02}},
	{APSRLW, yps, Py3, [23]uint8{0xd1, 0x71, 02, Pe, 0xd1, Pe, 0x71, 02}},
	{APSUBB, yxm, Pe, [23]uint8{0xf8}},
	{APSUBL, yxm, Pe, [23]uint8{0xfa}},
	{APSUBQ, yxm, Pe, [23]uint8{0xfb}},
	{APSUBSB, yxm, Pe, [23]uint8{0xe8}},
	{APSUBSW, yxm, Pe, [23]uint8{0xe9}},
	{APSUBUSB, yxm, Pe, [23]uint8{0xd8}},
	{APSUBUSW, yxm, Pe, [23]uint8{0xd9}},
	{APSUBW, yxm, Pe, [23]uint8{0xf9}},
	{APSWAPL, ymfp, Px, [23]uint8{0xbb}},
	{APUNPCKHBW, ymm, Py1, [23]uint8{0x68, Pe, 0x68}},
	{APUNPCKHLQ, ymm, Py1, [23]uint8{0x6a, Pe, 0x6a}},
	{APUNPCKHQDQ, yxm, Pe, [23]uint8{0x6d}},
	{APUNPCKHWL, ymm, Py1, [23]uint8{0x69, Pe, 0x69}},
	{APUNPCKLBW, ymm, Py1, [23]uint8{0x60, Pe, 0x60}},
	{APUNPCKLLQ, ymm, Py1, [23]uint8{0x62, Pe, 0x62}},
	{APUNPCKLQDQ, yxm, Pe, [23]uint8{0x6c}},
	{APUNPCKLWL, ymm, Py1, [23]uint8{0x61, Pe, 0x61}},
	{APUSHAL, ynone, P32, [23]uint8{0x60}},
	{APUSHAW, ynone, Pe, [23]uint8{0x60}},
	{APUSHFL, ynone, P32, [23]uint8{0x9c}},
	{APUSHFQ, ynone, Py, [23]uint8{0x9c}},
	{APUSHFW, ynone, Pe, [23]uint8{0x9c}},
	{APUSHL, ypushl, P32, [23]uint8{0x50, 0xff, 06, 0x6a, 0x68}},
	{APUSHQ, ypushl, Py, [23]uint8{0x50, 0xff, 06, 0x6a, 0x68}},
	{APUSHW, ypushl, Pe, [23]uint8{0x50, 0xff, 06, 0x6a, 0x68}},
	{APXOR, ymm, Py1, [23]uint8{0xef, Pe, 0xef}},
	{AQUAD, ybyte, Px, [23]uint8{8}},
	{ARCLB, yshb, Pb, [23]uint8{0xd0, 02, 0xc0, 02, 0xd2, 02}},
	{ARCLL, yshl, Px, [23]uint8{0xd1, 02, 0xc1, 02, 0xd3, 02, 0xd3, 02}},
	{ARCLQ, yshl, Pw, [23]uint8{0xd1, 02, 0xc1, 02, 0xd3, 02, 0xd3, 02}},
	{ARCLW, yshl, Pe, [23]uint8{0xd1, 02, 0xc1, 02, 0xd3, 02, 0xd3, 02}},
	{ARCPPS, yxm, Pm, [23]uint8{0x53}},
	{ARCPSS, yxm, Pf3, [23]uint8{0x53}},
	{ARCRB, yshb, Pb, [23]uint8{0xd0, 03, 0xc0, 03, 0xd2, 03}},
	{ARCRL, yshl, Px, [23]uint8{0xd1, 03, 0xc1, 03, 0xd3, 03, 0xd3, 03}},
	{ARCRQ, yshl, Pw, [23]uint8{0xd1, 03, 0xc1, 03, 0xd3, 03, 0xd3, 03}},
	{ARCRW, yshl, Pe, [23]uint8{0xd1, 03, 0xc1, 03, 0xd3, 03, 0xd3, 03}},
	{AREP, ynone, Px, [23]uint8{0xf3}},
	{AREPN, ynone, Px, [23]uint8{0xf2}},
	{obj.ARET, ynone, Px, [23]uint8{0xc3}},
	{ARETFW, yret, Pe, [23]uint8{0xcb, 0xca}},
	{ARETFL, yret, Px, [23]uint8{0xcb, 0xca}},
	{ARETFQ, yret, Pw, [23]uint8{0xcb, 0xca}},
	{AROLB, yshb, Pb, [23]uint8{0xd0, 00, 0xc0, 00, 0xd2, 00}},
	{AROLL, yshl, Px, [23]uint8{0xd1, 00, 0xc1, 00, 0xd3, 00, 0xd3, 00}},
	{AROLQ, yshl, Pw, [23]uint8{0xd1, 00, 0xc1, 00, 0xd3, 00, 0xd3, 00}},
	{AROLW, yshl, Pe, [23]uint8{0xd1, 00, 0xc1, 00, 0xd3, 00, 0xd3, 00}},
	{ARORB, yshb, Pb, [23]uint8{0xd0, 01, 0xc0, 01, 0xd2, 01}},
	{ARORL, yshl, Px, [23]uint8{0xd1, 01, 0xc1, 01, 0xd3, 01, 0xd3, 01}},
	{ARORQ, yshl, Pw, [23]uint8{0xd1, 01, 0xc1, 01, 0xd3, 01, 0xd3, 01}},
	{ARORW, yshl, Pe, [23]uint8{0xd1, 01, 0xc1, 01, 0xd3, 01, 0xd3, 01}},
	{ARSQRTPS, yxm, Pm, [23]uint8{0x52}},
	{ARSQRTSS, yxm, Pf3, [23]uint8{0x52}},
	{ASAHF, ynone, Px1, [23]uint8{0x9e, 00, 0x86, 0xe0, 0x50, 0x9d}}, /* XCHGB AH,AL; PUSH AX; POPFL */
	{ASALB, yshb, Pb, [23]uint8{0xd0, 04, 0xc0, 04, 0xd2, 04}},
	{ASALL, yshl, Px, [23]uint8{0xd1, 04, 0xc1, 04, 0xd3, 04, 0xd3, 04}},
	{ASALQ, yshl, Pw, [23]uint8{0xd1, 04, 0xc1, 04, 0xd3, 04, 0xd3, 04}},
	{ASALW, yshl, Pe, [23]uint8{0xd1, 04, 0xc1, 04, 0xd3, 04, 0xd3, 04}},
	{ASARB, yshb, Pb, [23]uint8{0xd0, 07, 0xc0, 07, 0xd2, 07}},
	{ASARL, yshl, Px, [23]uint8{0xd1, 07, 0xc1, 07, 0xd3, 07, 0xd3, 07}},
	{ASARQ, yshl, Pw, [23]uint8{0xd1, 07, 0xc1, 07, 0xd3, 07, 0xd3, 07}},
	{ASARW, yshl, Pe, [23]uint8{0xd1, 07, 0xc1, 07, 0xd3, 07, 0xd3, 07}},
	{ASBBB, yxorb, Pb, [23]uint8{0x1c, 0x80, 03, 0x18, 0x1a}},
	{ASBBL, yxorl, Px, [23]uint8{0x83, 03, 0x1d, 0x81, 03, 0x19, 0x1b}},
	{ASBBQ, yxorl, Pw, [23]uint8{0x83, 03, 0x1d, 0x81, 03, 0x19, 0x1b}},
	{ASBBW, yxorl, Pe, [23]uint8{0x83, 03, 0x1d, 0x81, 03, 0x19, 0x1b}},
	{ASCASB, ynone, Pb, [23]uint8{0xae}},
	{ASCASL, ynone, Px, [23]uint8{0xaf}},
	{ASCASQ, ynone, Pw, [23]uint8{0xaf}},
	{ASCASW, ynone, Pe, [23]uint8{0xaf}},
	{ASETCC, yscond, Pb, [23]uint8{0x0f, 0x93, 00}},
	{ASETCS, yscond, Pb, [23]uint8{0x0f, 0x92, 00}},
	{ASETEQ, yscond, Pb, [23]uint8{0x0f, 0x94, 00}},
	{ASETGE, yscond, Pb, [23]uint8{0x0f, 0x9d, 00}},
	{ASETGT, yscond, Pb, [23]uint8{0x0f, 0x9f, 00}},
	{ASETHI, yscond, Pb, [23]uint8{0x0f, 0x97, 00}},
	{ASETLE, yscond, Pb, [23]uint8{0x0f, 0x9e, 00}},
	{ASETLS, yscond, Pb, [23]uint8{0x0f, 0x96, 00}},
	{ASETLT, yscond, Pb, [23]uint8{0x0f, 0x9c, 00}},
	{ASETMI, yscond, Pb, [23]uint8{0x0f, 0x98, 00}},
	{ASETNE, yscond, Pb, [23]uint8{0x0f, 0x95, 00}},
	{ASETOC, yscond, Pb, [23]uint8{0x0f, 0x91, 00}},
	{ASETOS, yscond, Pb, [23]uint8{0x0f, 0x90, 00}},
	{ASETPC, yscond, Pb, [23]uint8{0x0f, 0x9b, 00}},
	{ASETPL, yscond, Pb, [23]uint8{0x0f, 0x99, 00}},
	{ASETPS, yscond, Pb, [23]uint8{0x0f, 0x9a, 00}},
	{ASHLB, yshb, Pb, [23]uint8{0xd0, 04, 0xc0, 04, 0xd2, 04}},
	{ASHLL, yshl, Px, [23]uint8{0xd1, 04, 0xc1, 04, 0xd3, 04, 0xd3, 04}},
	{ASHLQ, yshl, Pw, [23]uint8{0xd1, 04, 0xc1, 04, 0xd3, 04, 0xd3, 04}},
	{ASHLW, yshl, Pe, [23]uint8{0xd1, 04, 0xc1, 04, 0xd3, 04, 0xd3, 04}},
	{ASHRB, yshb, Pb, [23]uint8{0xd0, 05, 0xc0, 05, 0xd2, 05}},
	{ASHRL, yshl, Px, [23]uint8{0xd1, 05, 0xc1, 05, 0xd3, 05, 0xd3, 05}},
	{ASHRQ, yshl, Pw, [23]uint8{0xd1, 05, 0xc1, 05, 0xd3, 05, 0xd3, 05}},
	{ASHRW, yshl, Pe, [23]uint8{0xd1, 05, 0xc1, 05, 0xd3, 05, 0xd3, 05}},
	{ASHUFPD, yxshuf, Pq, [23]uint8{0xc6, 00}},
	{ASHUFPS, yxshuf, Pm, [23]uint8{0xc6, 00}},
	{ASQRTPD, yxm, Pe, [23]uint8{0x51}},
	{ASQRTPS, yxm, Pm, [23]uint8{0x51}},
	{ASQRTSD, yxm, Pf2, [23]uint8{0x51}},
	{ASQRTSS, yxm, Pf3, [23]uint8{0x51}},
	{ASTC, ynone, Px, [23]uint8{0xf9}},
	{ASTD, ynone, Px, [23]uint8{0xfd}},
	{ASTI, ynone, Px, [23]uint8{0xfb}},
	{ASTMXCSR, ysvrs, Pm, [23]uint8{0xae, 03, 0xae, 03}},
	{ASTOSB, ynone, Pb, [23]uint8{0xaa}},
	{ASTOSL, ynone, Px, [23]uint8{0xab}},
	{ASTOSQ, ynone, Pw, [23]uint8{0xab}},
	{ASTOSW, ynone, Pe, [23]uint8{0xab}},
	{ASUBB, yxorb, Pb, [23]uint8{0x2c, 0x80, 05, 0x28, 0x2a}},
	{ASUBL, yaddl, Px, [23]uint8{0x83, 05, 0x2d, 0x81, 05, 0x29, 0x2b}},
	{ASUBPD, yxm, Pe, [23]uint8{0x5c}},
	{ASUBPS, yxm, Pm, [23]uint8{0x5c}},
	{ASUBQ, yaddl, Pw, [23]uint8{0x83, 05, 0x2d, 0x81, 05, 0x29, 0x2b}},
	{ASUBSD, yxm, Pf2, [23]uint8{0x5c}},
	{ASUBSS, yxm, Pf3, [23]uint8{0x5c}},
	{ASUBW, yaddl, Pe, [23]uint8{0x83, 05, 0x2d, 0x81, 05, 0x29, 0x2b}},
	{ASWAPGS, ynone, Pm, [23]uint8{0x01, 0xf8}},
	{ASYSCALL, ynone, Px, [23]uint8{0x0f, 0x05}}, /* fast syscall */
	{ATESTB, ytestb, Pb, [23]uint8{0xa8, 0xf6, 00, 0x84, 0x84}},
	{ATESTL, ytestl, Px, [23]uint8{0xa9, 0xf7, 00, 0x85, 0x85}},
	{ATESTQ, ytestl, Pw, [23]uint8{0xa9, 0xf7, 00, 0x85, 0x85}},
	{ATESTW, ytestl, Pe, [23]uint8{0xa9, 0xf7, 00, 0x85, 0x85}},
	{obj.ATEXT, ytext, Px, [23]uint8{}},
	{AUCOMISD, yxcmp, Pe, [23]uint8{0x2e}},
	{AUCOMISS, yxcmp, Pm, [23]uint8{0x2e}},
	{AUNPCKHPD, yxm, Pe, [23]uint8{0x15}},
	{AUNPCKHPS, yxm, Pm, [23]uint8{0x15}},
	{AUNPCKLPD, yxm, Pe, [23]uint8{0x14}},
	{AUNPCKLPS, yxm, Pm, [23]uint8{0x14}},
	{AVERR, ydivl, Pm, [23]uint8{0x00, 04}},
	{AVERW, ydivl, Pm, [23]uint8{0x00, 05}},
	{AWAIT, ynone, Px, [23]uint8{0x9b}},
	{AWORD, ybyte, Px, [23]uint8{2}},
	{AXCHGB, yml_mb, Pb, [23]uint8{0x86, 0x86}},
	{AXCHGL, yxchg, Px, [23]uint8{0x90, 0x90, 0x87, 0x87}},
	{AXCHGQ, yxchg, Pw, [23]uint8{0x90, 0x90, 0x87, 0x87}},
	{AXCHGW, yxchg, Pe, [23]uint8{0x90, 0x90, 0x87, 0x87}},
	{AXLAT, ynone, Px, [23]uint8{0xd7}},
	{AXORB, yxorb, Pb, [23]uint8{0x34, 0x80, 06, 0x30, 0x32}},
	{AXORL, yxorl, Px, [23]uint8{0x83, 06, 0x35, 0x81, 06, 0x31, 0x33}},
	{AXORPD, yxm, Pe, [23]uint8{0x57}},
	{AXORPS, yxm, Pm, [23]uint8{0x57}},
	{AXORQ, yxorl, Pw, [23]uint8{0x83, 06, 0x35, 0x81, 06, 0x31, 0x33}},
	{AXORW, yxorl, Pe, [23]uint8{0x83, 06, 0x35, 0x81, 06, 0x31, 0x33}},
	{AFMOVB, yfmvx, Px, [23]uint8{0xdf, 04}},
	{AFMOVBP, yfmvp, Px, [23]uint8{0xdf, 06}},
	{AFMOVD, yfmvd, Px, [23]uint8{0xdd, 00, 0xdd, 02, 0xd9, 00, 0xdd, 02}},
	{AFMOVDP, yfmvdp, Px, [23]uint8{0xdd, 03, 0xdd, 03}},
	{AFMOVF, yfmvf, Px, [23]uint8{0xd9, 00, 0xd9, 02}},
	{AFMOVFP, yfmvp, Px, [23]uint8{0xd9, 03}},
	{AFMOVL, yfmvf, Px, [23]uint8{0xdb, 00, 0xdb, 02}},
	{AFMOVLP, yfmvp, Px, [23]uint8{0xdb, 03}},
	{AFMOVV, yfmvx, Px, [23]uint8{0xdf, 05}},
	{AFMOVVP, yfmvp, Px, [23]uint8{0xdf, 07}},
	{AFMOVW, yfmvf, Px, [23]uint8{0xdf, 00, 0xdf, 02}},
	{AFMOVWP, yfmvp, Px, [23]uint8{0xdf, 03}},
	{AFMOVX, yfmvx, Px, [23]uint8{0xdb, 05}},
	{AFMOVXP, yfmvp, Px, [23]uint8{0xdb, 07}},
	{AFCMOVCC, yfcmv, Px, [23]uint8{0xdb, 00}},
	{AFCMOVCS, yfcmv, Px, [23]uint8{0xda, 00}},
	{AFCMOVEQ, yfcmv, Px, [23]uint8{0xda, 01}},
	{AFCMOVHI, yfcmv, Px, [23]uint8{0xdb, 02}},
	{AFCMOVLS, yfcmv, Px, [23]uint8{0xda, 02}},
	{AFCMOVNE, yfcmv, Px, [23]uint8{0xdb, 01}},
	{AFCMOVNU, yfcmv, Px, [23]uint8{0xdb, 03}},
	{AFCMOVUN, yfcmv, Px, [23]uint8{0xda, 03}},
	{AFCOMB, nil, 0, [23]uint8{}},
	{AFCOMBP, nil, 0, [23]uint8{}},
	{AFCOMD, yfadd, Px, [23]uint8{0xdc, 02, 0xd8, 02, 0xdc, 02}},  /* botch */
	{AFCOMDP, yfadd, Px, [23]uint8{0xdc, 03, 0xd8, 03, 0xdc, 03}}, /* botch */
	{AFCOMDPP, ycompp, Px, [23]uint8{0xde, 03}},
	{AFCOMF, yfmvx, Px, [23]uint8{0xd8, 02}},
	{AFCOMFP, yfmvx, Px, [23]uint8{0xd8, 03}},
	{AFCOMI, yfmvx, Px, [23]uint8{0xdb, 06}},
	{AFCOMIP, yfmvx, Px, [23]uint8{0xdf, 06}},
	{AFCOML, yfmvx, Px, [23]uint8{0xda, 02}},
	{AFCOMLP, yfmvx, Px, [23]uint8{0xda, 03}},
	{AFCOMW, yfmvx, Px, [23]uint8{0xde, 02}},
	{AFCOMWP, yfmvx, Px, [23]uint8{0xde, 03}},
	{AFUCOM, ycompp, Px, [23]uint8{0xdd, 04}},
	{AFUCOMI, ycompp, Px, [23]uint8{0xdb, 05}},
	{AFUCOMIP, ycompp, Px, [23]uint8{0xdf, 05}},
	{AFUCOMP, ycompp, Px, [23]uint8{0xdd, 05}},
	{AFUCOMPP, ycompp, Px, [23]uint8{0xda, 13}},
	{AFADDDP, yfaddp, Px, [23]uint8{0xde, 00}},
	{AFADDW, yfmvx, Px, [23]uint8{0xde, 00}},
	{AFADDL, yfmvx, Px, [23]uint8{0xda, 00}},
	{AFADDF, yfmvx, Px, [23]uint8{0xd8, 00}},
	{AFADDD, yfadd, Px, [23]uint8{0xdc, 00, 0xd8, 00, 0xdc, 00}},
	{AFMULDP, yfaddp, Px, [23]uint8{0xde, 01}},
	{AFMULW, yfmvx, Px, [23]uint8{0xde, 01}},
	{AFMULL, yfmvx, Px, [23]uint8{0xda, 01}},
	{AFMULF, yfmvx, Px, [23]uint8{0xd8, 01}},
	{AFMULD, yfadd, Px, [23]uint8{0xdc, 01, 0xd8, 01, 0xdc, 01}},
	{AFSUBDP, yfaddp, Px, [23]uint8{0xde, 05}},
	{AFSUBW, yfmvx, Px, [23]uint8{0xde, 04}},
	{AFSUBL, yfmvx, Px, [23]uint8{0xda, 04}},
	{AFSUBF, yfmvx, Px, [23]uint8{0xd8, 04}},
	{AFSUBD, yfadd, Px, [23]uint8{0xdc, 04, 0xd8, 04, 0xdc, 05}},
	{AFSUBRDP, yfaddp, Px, [23]uint8{0xde, 04}},
	{AFSUBRW, yfmvx, Px, [23]uint8{0xde, 05}},
	{AFSUBRL, yfmvx, Px, [23]uint8{0xda, 05}},
	{AFSUBRF, yfmvx, Px, [23]uint8{0xd8, 05}},
	{AFSUBRD, yfadd, Px, [23]uint8{0xdc, 05, 0xd8, 05, 0xdc, 04}},
	{AFDIVDP, yfaddp, Px, [23]uint8{0xde, 07}},
	{AFDIVW, yfmvx, Px, [23]uint8{0xde, 06}},
	{AFDIVL, yfmvx, Px, [23]uint8{0xda, 06}},
	{AFDIVF, yfmvx, Px, [23]uint8{0xd8, 06}},
	{AFDIVD, yfadd, Px, [23]uint8{0xdc, 06, 0xd8, 06, 0xdc, 07}},
	{AFDIVRDP, yfaddp, Px, [23]uint8{0xde, 06}},
	{AFDIVRW, yfmvx, Px, [23]uint8{0xde, 07}},
	{AFDIVRL, yfmvx, Px, [23]uint8{0xda, 07}},
	{AFDIVRF, yfmvx, Px, [23]uint8{0xd8, 07}},
	{AFDIVRD, yfadd, Px, [23]uint8{0xdc, 07, 0xd8, 07, 0xdc, 06}},
	{AFXCHD, yfxch, Px, [23]uint8{0xd9, 01, 0xd9, 01}},
	{AFFREE, nil, 0, [23]uint8{}},
	{AFLDCW, ystcw, Px, [23]uint8{0xd9, 05, 0xd9, 05}},
	{AFLDENV, ystcw, Px, [23]uint8{0xd9, 04, 0xd9, 04}},
	{AFRSTOR, ysvrs, Px, [23]uint8{0xdd, 04, 0xdd, 04}},
	{AFSAVE, ysvrs, Px, [23]uint8{0xdd, 06, 0xdd, 06}},
	{AFSTCW, ystcw, Px, [23]uint8{0xd9, 07, 0xd9, 07}},
	{AFSTENV, ystcw, Px, [23]uint8{0xd9, 06, 0xd9, 06}},
	{AFSTSW, ystsw, Px, [23]uint8{0xdd, 07, 0xdf, 0xe0}},
	{AF2XM1, ynone, Px, [23]uint8{0xd9, 0xf0}},
	{AFABS, ynone, Px, [23]uint8{0xd9, 0xe1}},
	{AFCHS, ynone, Px, [23]uint8{0xd9, 0xe0}},
	{AFCLEX, ynone, Px, [23]uint8{0xdb, 0xe2}},
	{AFCOS, ynone, Px, [23]uint8{0xd9, 0xff}},
	{AFDECSTP, ynone, Px, [23]uint8{0xd9, 0xf6}},
	{AFINCSTP, ynone, Px, [23]uint8{0xd9, 0xf7}},
	{AFINIT, ynone, Px, [23]uint8{0xdb, 0xe3}},
	{AFLD1, ynone, Px, [23]uint8{0xd9, 0xe8}},
	{AFLDL2E, ynone, Px, [23]uint8{0xd9, 0xea}},
	{AFLDL2T, ynone, Px, [23]uint8{0xd9, 0xe9}},
	{AFLDLG2, ynone, Px, [23]uint8{0xd9, 0xec}},
	{AFLDLN2, ynone, Px, [23]uint8{0xd9, 0xed}},
	{AFLDPI, ynone, Px, [23]uint8{0xd9, 0xeb}},
	{AFLDZ, ynone, Px, [23]uint8{0xd9, 0xee}},
	{AFNOP, ynone, Px, [23]uint8{0xd9, 0xd0}},
	{AFPATAN, ynone, Px, [23]uint8{0xd9, 0xf3}},
	{AFPREM, ynone, Px, [23]uint8{0xd9, 0xf8}},
	{AFPREM1, ynone, Px, [23]uint8{0xd9, 0xf5}},
	{AFPTAN, ynone, Px, [23]uint8{0xd9, 0xf2}},
	{AFRNDINT, ynone, Px, [23]uint8{0xd9, 0xfc}},
	{AFSCALE, ynone, Px, [23]uint8{0xd9, 0xfd}},
	{AFSIN, ynone, Px, [23]uint8{0xd9, 0xfe}},
	{AFSINCOS, ynone, Px, [23]uint8{0xd9, 0xfb}},
	{AFSQRT, ynone, Px, [23]uint8{0xd9, 0xfa}},
	{AFTST, ynone, Px, [23]uint8{0xd9, 0xe4}},
	{AFXAM, ynone, Px, [23]uint8{0xd9, 0xe5}},
	{AFXTRACT, ynone, Px, [23]uint8{0xd9, 0xf4}},
	{AFYL2X, ynone, Px, [23]uint8{0xd9, 0xf1}},
	{AFYL2XP1, ynone, Px, [23]uint8{0xd9, 0xf9}},
	{ACMPXCHGB, yrb_mb, Pb, [23]uint8{0x0f, 0xb0}},
	{ACMPXCHGL, yrl_ml, Px, [23]uint8{0x0f, 0xb1}},
	{ACMPXCHGW, yrl_ml, Pe, [23]uint8{0x0f, 0xb1}},
	{ACMPXCHGQ, yrl_ml, Pw, [23]uint8{0x0f, 0xb1}},
	{ACMPXCHG8B, yscond, Pm, [23]uint8{0xc7, 01}},
	{AINVD, ynone, Pm, [23]uint8{0x08}},
	{AINVLPG, ymbs, Pm, [23]uint8{0x01, 07}},
	{ALFENCE, ynone, Pm, [23]uint8{0xae, 0xe8}},
	{AMFENCE, ynone, Pm, [23]uint8{0xae, 0xf0}},
	{AMOVNTIL, yrl_ml, Pm, [23]uint8{0xc3}},
	{AMOVNTIQ, yrl_ml, Pw, [23]uint8{0x0f, 0xc3}},
	{ARDMSR, ynone, Pm, [23]uint8{0x32}},
	{ARDPMC, ynone, Pm, [23]uint8{0x33}},
	{ARDTSC, ynone, Pm, [23]uint8{0x31}},
	{ARSM, ynone, Pm, [23]uint8{0xaa}},
	{ASFENCE, ynone, Pm, [23]uint8{0xae, 0xf8}},
	{ASYSRET, ynone, Pm, [23]uint8{0x07}},
	{AWBINVD, ynone, Pm, [23]uint8{0x09}},
	{AWRMSR, ynone, Pm, [23]uint8{0x30}},
	{AXADDB, yrb_mb, Pb, [23]uint8{0x0f, 0xc0}},
	{AXADDL, yrl_ml, Px, [23]uint8{0x0f, 0xc1}},
	{AXADDQ, yrl_ml, Pw, [23]uint8{0x0f, 0xc1}},
	{AXADDW, yrl_ml, Pe, [23]uint8{0x0f, 0xc1}},
	{ACRC32B, ycrc32l, Px, [23]uint8{0xf2, 0x0f, 0x38, 0xf0, 0}},
	{ACRC32Q, ycrc32l, Pw, [23]uint8{0xf2, 0x0f, 0x38, 0xf1, 0}},
	{APREFETCHT0, yprefetch, Pm, [23]uint8{0x18, 01}},
	{APREFETCHT1, yprefetch, Pm, [23]uint8{0x18, 02}},
	{APREFETCHT2, yprefetch, Pm, [23]uint8{0x18, 03}},
	{APREFETCHNTA, yprefetch, Pm, [23]uint8{0x18, 00}},
	{AMOVQL, yrl_ml, Px, [23]uint8{0x89}},
	{obj.AUNDEF, ynone, Px, [23]uint8{0x0f, 0x0b}},
	{AAESENC, yaes, Pq, [23]uint8{0x38, 0xdc, 0}},
	{AAESENCLAST, yaes, Pq, [23]uint8{0x38, 0xdd, 0}},
	{AAESDEC, yaes, Pq, [23]uint8{0x38, 0xde, 0}},
	{AAESDECLAST, yaes, Pq, [23]uint8{0x38, 0xdf, 0}},
	{AAESIMC, yaes, Pq, [23]uint8{0x38, 0xdb, 0}},
	{AAESKEYGENASSIST, yaes2, Pq, [23]uint8{0x3a, 0xdf, 0}},
	{AROUNDPD, yaes2, Pq, [23]uint8{0x3a, 0x09, 0}},
	{AROUNDPS, yaes2, Pq, [23]uint8{0x3a, 0x08, 0}},
	{AROUNDSD, yaes2, Pq, [23]uint8{0x3a, 0x0b, 0}},
	{AROUNDSS, yaes2, Pq, [23]uint8{0x3a, 0x0a, 0}},
	{APSHUFD, yxshuf, Pq, [23]uint8{0x70, 0}},
	{APCLMULQDQ, yxshuf, Pq, [23]uint8{0x3a, 0x44, 0}},
	{AVZEROUPPER, ynone, Px, [23]uint8{0xc5, 0xf8, 0x77}},
	{AMOVHDU, yxmov_vex, Pvex2, [23]uint8{0x6f, 0x7f}},
	{AMOVNTHD, yxr_ml_vex, Pvex1, [23]uint8{0xe7}},
	{AMOVHDA, yxmov_vex, Pvex1, [23]uint8{0x6f, 0x7f}},
	{AVPCMPEQB, yxm_xm_xm, Pvex1, [23]uint8{0x74, 0x74}},
	{AVPXOR, yxm_xm_xm, Pvex1, [23]uint8{0xef, 0xef}},
	{AVPMOVMSKB, ymskb_vex, Pvex1, [23]uint8{0xd7}},
	{AVPAND, yxm_xm_xm, Pvex1, [23]uint8{0xdb, 0xdb}},
	{AVPBROADCASTB, yml_xr_vex, Pvex3, [23]uint8{0x78, 0x78}},
	{AVPTEST, yml_xr_vex, Pvex3, [23]uint8{0x17, 0x17}},
	{AXACQUIRE, ynone, Px, [23]uint8{0xf2}},
	{AXRELEASE, ynone, Px, [23]uint8{0xf3}},
	{AXBEGIN, yxbegin, Px, [23]uint8{0xc7, 0xf8}},
	{AXABORT, yxabort, Px, [23]uint8{0xc6, 0xf8}},
	{AXEND, ynone, Px, [23]uint8{0x0f, 01, 0xd5}},
	{AXTEST, ynone, Px, [23]uint8{0x0f, 01, 0xd6}},
	{obj.AUSEFIELD, ynop, Px, [23]uint8{0, 0}},
	{obj.ATYPE, nil, 0, [23]uint8{}},
	{obj.AFUNCDATA, yfuncdata, Px, [23]uint8{0, 0}},
	{obj.APCDATA, ypcdata, Px, [23]uint8{0, 0}},
	{obj.ACHECKNIL, nil, 0, [23]uint8{}},
	{obj.AVARDEF, nil, 0, [23]uint8{}},
	{obj.AVARKILL, nil, 0, [23]uint8{}},
	{obj.ADUFFCOPY, yduff, Px, [23]uint8{0xe8}},
	{obj.ADUFFZERO, yduff, Px, [23]uint8{0xe8}},
	{obj.AEND, nil, 0, [23]uint8{}},
	{0, nil, 0, [23]uint8{}},
}

var opindex [(ALAST + 1) & obj.AMask]*Optab

// isextern reports whether s describes an external symbol that must avoid pc-relative addressing.
// This happens on systems like Solaris that call .so functions instead of system calls.
// It does not seem to be necessary for any other systems. This is probably working
// around a Solaris-specific bug that should be fixed differently, but we don't know
// what that bug is. And this does fix it.
func isextern(s *obj.LSym) bool {
	// All the Solaris dynamic imports from libc.so begin with "libc_".
	return strings.HasPrefix(s.Name, "libc_")
}

// single-instruction no-ops of various lengths.
// constructed by hand and disassembled with gdb to verify.
// see http://www.agner.org/optimize/optimizing_assembly.pdf for discussion.
var nop = [][16]uint8{
	{0x90},
	{0x66, 0x90},
	{0x0F, 0x1F, 0x00},
	{0x0F, 0x1F, 0x40, 0x00},
	{0x0F, 0x1F, 0x44, 0x00, 0x00},
	{0x66, 0x0F, 0x1F, 0x44, 0x00, 0x00},
	{0x0F, 0x1F, 0x80, 0x00, 0x00, 0x00, 0x00},
	{0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
	{0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
}

// Native Client rejects the repeated 0x66 prefix.
// {0x66, 0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
func fillnop(p []byte, n int) {
	var m int

	for n > 0 {
		m = n
		if m > len(nop) {
			m = len(nop)
		}
		copy(p[:m], nop[m-1][:m])
		p = p[m:]
		n -= m
	}
}

func naclpad(ctxt *obj.Link, s *obj.LSym, c int32, pad int32) int32 {
	obj.Symgrow(ctxt, s, int64(c)+int64(pad))
	fillnop(s.P[c:], int(pad))
	return c + pad
}

func spadjop(ctxt *obj.Link, p *obj.Prog, l int, q int) int {
	if p.Mode != 64 || ctxt.Arch.Ptrsize == 4 {
		return l
	}
	return q
}

func span6(ctxt *obj.Link, s *obj.LSym) {
	ctxt.Cursym = s

	if s.P != nil {
		return
	}

	if ycover[0] == 0 {
		instinit()
	}

	var v int32
	for p := ctxt.Cursym.Text; p != nil; p = p.Link {
		if p.To.Type == obj.TYPE_BRANCH {
			if p.Pcond == nil {
				p.Pcond = p
			}
		}
		if p.As == AADJSP {
			p.To.Type = obj.TYPE_REG
			p.To.Reg = REG_SP
			v = int32(-p.From.Offset)
			p.From.Offset = int64(v)
			p.As = int16(spadjop(ctxt, p, AADDL, AADDQ))
			if v < 0 {
				p.As = int16(spadjop(ctxt, p, ASUBL, ASUBQ))
				v = -v
				p.From.Offset = int64(v)
			}

			if v == 0 {
				p.As = obj.ANOP
			}
		}
	}

	var q *obj.Prog
	for p := s.Text; p != nil; p = p.Link {
		p.Back = 2 // use short branches first time through
		q = p.Pcond
		if q != nil && (q.Back&2 != 0) {
			p.Back |= 1 // backward jump
			q.Back |= 4 // loop head
		}

		if p.As == AADJSP {
			p.To.Type = obj.TYPE_REG
			p.To.Reg = REG_SP
			v = int32(-p.From.Offset)
			p.From.Offset = int64(v)
			p.As = int16(spadjop(ctxt, p, AADDL, AADDQ))
			if v < 0 {
				p.As = int16(spadjop(ctxt, p, ASUBL, ASUBQ))
				v = -v
				p.From.Offset = int64(v)
			}

			if v == 0 {
				p.As = obj.ANOP
			}
		}
	}

	n := 0
	var bp []byte
	var c int32
	var i int
	var loop int32
	var m int
	var p *obj.Prog
	for {
		loop = 0
		for i = 0; i < len(s.R); i++ {
			s.R[i] = obj.Reloc{}
		}
		s.R = s.R[:0]
		s.P = s.P[:0]
		c = 0
		for p = s.Text; p != nil; p = p.Link {
			if ctxt.Headtype == obj.Hnacl && p.Isize > 0 {
				var deferreturn *obj.LSym

				if deferreturn == nil {
					deferreturn = obj.Linklookup(ctxt, "runtime.deferreturn", 0)
				}

				// pad everything to avoid crossing 32-byte boundary
				if c>>5 != (c+int32(p.Isize)-1)>>5 {
					c = naclpad(ctxt, s, c, -c&31)
				}

				// pad call deferreturn to start at 32-byte boundary
				// so that subtracting 5 in jmpdefer will jump back
				// to that boundary and rerun the call.
				if p.As == obj.ACALL && p.To.Sym == deferreturn {
					c = naclpad(ctxt, s, c, -c&31)
				}

				// pad call to end at 32-byte boundary
				if p.As == obj.ACALL {
					c = naclpad(ctxt, s, c, -(c+int32(p.Isize))&31)
				}

				// the linker treats REP and STOSQ as different instructions
				// but in fact the REP is a prefix on the STOSQ.
				// make sure REP has room for 2 more bytes, so that
				// padding will not be inserted before the next instruction.
				if (p.As == AREP || p.As == AREPN) && c>>5 != (c+3-1)>>5 {
					c = naclpad(ctxt, s, c, -c&31)
				}

				// same for LOCK.
				// various instructions follow; the longest is 4 bytes.
				// give ourselves 8 bytes so as to avoid surprises.
				if p.As == ALOCK && c>>5 != (c+8-1)>>5 {
					c = naclpad(ctxt, s, c, -c&31)
				}
			}

			if (p.Back&4 != 0) && c&(LoopAlign-1) != 0 {
				// pad with NOPs
				v = -c & (LoopAlign - 1)

				if v <= MaxLoopPad {
					obj.Symgrow(ctxt, s, int64(c)+int64(v))
					fillnop(s.P[c:], int(v))
					c += v
				}
			}

			p.Pc = int64(c)

			// process forward jumps to p
			for q = p.Rel; q != nil; q = q.Forwd {
				v = int32(p.Pc - (q.Pc + int64(q.Mark)))
				if q.Back&2 != 0 { // short
					if v > 127 {
						loop++
						q.Back ^= 2
					}

					if q.As == AJCXZL || q.As == AXBEGIN {
						s.P[q.Pc+2] = byte(v)
					} else {
						s.P[q.Pc+1] = byte(v)
					}
				} else {
					bp = s.P[q.Pc+int64(q.Mark)-4:]
					bp[0] = byte(v)
					bp = bp[1:]
					bp[0] = byte(v >> 8)
					bp = bp[1:]
					bp[0] = byte(v >> 16)
					bp = bp[1:]
					bp[0] = byte(v >> 24)
				}
			}

			p.Rel = nil

			p.Pc = int64(c)
			asmins(ctxt, p)
			m = -cap(ctxt.Andptr) + cap(ctxt.And[:])
			if int(p.Isize) != m {
				p.Isize = uint8(m)
				loop++
			}

			obj.Symgrow(ctxt, s, p.Pc+int64(m))
			copy(s.P[p.Pc:][:m], ctxt.And[:m])
			p.Mark = uint16(m)
			c += int32(m)
		}

		n++
		if n > 20 {
			ctxt.Diag("span must be looping")
			log.Fatalf("loop")
		}
		if loop == 0 {
			break
		}
	}

	if ctxt.Headtype == obj.Hnacl {
		c = naclpad(ctxt, s, c, -c&31)
	}

	// Pad functions with trap instruction, to catch invalid jumps
	if c&(FuncAlign-1) != 0 {
		v = -c & (FuncAlign - 1)
		obj.Symgrow(ctxt, s, int64(c)+int64(v))
		for i := c; i < c+v; i++ {
			// 0xCC is INT $3 - breakpoint instruction
			s.P[i] = uint8(0xCC)
		}
		c += v
	}
	s.Size = int64(c)

	if false { /* debug['a'] > 1 */
		fmt.Printf("span1 %s %d (%d tries)\n %.6x", s.Name, s.Size, n, 0)
		var i int
		for i = 0; i < len(s.P); i++ {
			fmt.Printf(" %.2x", s.P[i])
			if i%16 == 15 {
				fmt.Printf("\n  %.6x", uint(i+1))
			}
		}

		if i%16 != 0 {
			fmt.Printf("\n")
		}

		for i := 0; i < len(s.R); i++ {
			r := &s.R[i]
			fmt.Printf(" rel %#.4x/%d %s%+d\n", uint32(r.Off), r.Siz, r.Sym.Name, r.Add)
		}
	}
}

func instinit() {
	var c int

	for i := 1; optab[i].as != 0; i++ {
		c = int(optab[i].as)
		if opindex[c&obj.AMask] != nil {
			log.Fatalf("phase error in optab: %d (%v)", i, obj.Aconv(c))
		}
		opindex[c&obj.AMask] = &optab[i]
	}

	for i := 0; i < Ymax; i++ {
		ycover[i*Ymax+i] = 1
	}

	ycover[Yi0*Ymax+Yi8] = 1
	ycover[Yi1*Ymax+Yi8] = 1
	ycover[Yu7*Ymax+Yi8] = 1

	ycover[Yi0*Ymax+Yu7] = 1
	ycover[Yi1*Ymax+Yu7] = 1

	ycover[Yi0*Ymax+Yu8] = 1
	ycover[Yi1*Ymax+Yu8] = 1
	ycover[Yu7*Ymax+Yu8] = 1

	ycover[Yi0*Ymax+Ys32] = 1
	ycover[Yi1*Ymax+Ys32] = 1
	ycover[Yu7*Ymax+Ys32] = 1
	ycover[Yu8*Ymax+Ys32] = 1
	ycover[Yi8*Ymax+Ys32] = 1

	ycover[Yi0*Ymax+Yi32] = 1
	ycover[Yi1*Ymax+Yi32] = 1
	ycover[Yu7*Ymax+Yi32] = 1
	ycover[Yu8*Ymax+Yi32] = 1
	ycover[Yi8*Ymax+Yi32] = 1
	ycover[Ys32*Ymax+Yi32] = 1

	ycover[Yi0*Ymax+Yi64] = 1
	ycover[Yi1*Ymax+Yi64] = 1
	ycover[Yu7*Ymax+Yi64] = 1
	ycover[Yu8*Ymax+Yi64] = 1
	ycover[Yi8*Ymax+Yi64] = 1
	ycover[Ys32*Ymax+Yi64] = 1
	ycover[Yi32*Ymax+Yi64] = 1

	ycover[Yal*Ymax+Yrb] = 1
	ycover[Ycl*Ymax+Yrb] = 1
	ycover[Yax*Ymax+Yrb] = 1
	ycover[Ycx*Ymax+Yrb] = 1
	ycover[Yrx*Ymax+Yrb] = 1
	ycover[Yrl*Ymax+Yrb] = 1 // but not Yrl32

	ycover[Ycl*Ymax+Ycx] = 1

	ycover[Yax*Ymax+Yrx] = 1
	ycover[Ycx*Ymax+Yrx] = 1

	ycover[Yax*Ymax+Yrl] = 1
	ycover[Ycx*Ymax+Yrl] = 1
	ycover[Yrx*Ymax+Yrl] = 1
	ycover[Yrl32*Ymax+Yrl] = 1

	ycover[Yf0*Ymax+Yrf] = 1

	ycover[Yal*Ymax+Ymb] = 1
	ycover[Ycl*Ymax+Ymb] = 1
	ycover[Yax*Ymax+Ymb] = 1
	ycover[Ycx*Ymax+Ymb] = 1
	ycover[Yrx*Ymax+Ymb] = 1
	ycover[Yrb*Ymax+Ymb] = 1
	ycover[Yrl*Ymax+Ymb] = 1 // but not Yrl32
	ycover[Ym*Ymax+Ymb] = 1

	ycover[Yax*Ymax+Yml] = 1
	ycover[Ycx*Ymax+Yml] = 1
	ycover[Yrx*Ymax+Yml] = 1
	ycover[Yrl*Ymax+Yml] = 1
	ycover[Yrl32*Ymax+Yml] = 1
	ycover[Ym*Ymax+Yml] = 1

	ycover[Yax*Ymax+Ymm] = 1
	ycover[Ycx*Ymax+Ymm] = 1
	ycover[Yrx*Ymax+Ymm] = 1
	ycover[Yrl*Ymax+Ymm] = 1
	ycover[Yrl32*Ymax+Ymm] = 1
	ycover[Ym*Ymax+Ymm] = 1
	ycover[Ymr*Ymax+Ymm] = 1

	ycover[Ym*Ymax+Yxm] = 1
	ycover[Yxr*Ymax+Yxm] = 1

	for i := 0; i < MAXREG; i++ {
		reg[i] = -1
		if i >= REG_AL && i <= REG_R15B {
			reg[i] = (i - REG_AL) & 7
			if i >= REG_SPB && i <= REG_DIB {
				regrex[i] = 0x40
			}
			if i >= REG_R8B && i <= REG_R15B {
				regrex[i] = Rxr | Rxx | Rxb
			}
		}

		if i >= REG_AH && i <= REG_BH {
			reg[i] = 4 + ((i - REG_AH) & 7)
		}
		if i >= REG_AX && i <= REG_R15 {
			reg[i] = (i - REG_AX) & 7
			if i >= REG_R8 {
				regrex[i] = Rxr | Rxx | Rxb
			}
		}

		if i >= REG_F0 && i <= REG_F0+7 {
			reg[i] = (i - REG_F0) & 7
		}
		if i >= REG_M0 && i <= REG_M0+7 {
			reg[i] = (i - REG_M0) & 7
		}
		if i >= REG_X0 && i <= REG_X0+15 {
			reg[i] = (i - REG_X0) & 7
			if i >= REG_X0+8 {
				regrex[i] = Rxr | Rxx | Rxb
			}
		}

		if i >= REG_CR+8 && i <= REG_CR+15 {
			regrex[i] = Rxr
		}
	}
}

var isAndroid = (obj.Getgoos() == "android")

func prefixof(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) int {
	if a.Reg < REG_CS && a.Index < REG_CS { // fast path
		return 0
	}
	if a.Type == obj.TYPE_MEM && a.Name == obj.NAME_NONE {
		switch a.Reg {
		case REG_CS:
			return 0x2e

		case REG_DS:
			return 0x3e

		case REG_ES:
			return 0x26

		case REG_FS:
			return 0x64

		case REG_GS:
			return 0x65

		case REG_TLS:
			// NOTE: Systems listed here should be only systems that
			// support direct TLS references like 8(TLS) implemented as
			// direct references from FS or GS. Systems that require
			// the initial-exec model, where you load the TLS base into
			// a register and then index from that register, do not reach
			// this code and should not be listed.
			if p.Mode == 32 {
				switch ctxt.Headtype {
				default:
					if isAndroid {
						return 0x65 // GS
					}
					log.Fatalf("unknown TLS base register for %s", obj.Headstr(ctxt.Headtype))

				case obj.Hdarwin,
					obj.Hdragonfly,
					obj.Hfreebsd,
					obj.Hnetbsd,
					obj.Hopenbsd:
					return 0x65 // GS
				}
			}

			switch ctxt.Headtype {
			default:
				log.Fatalf("unknown TLS base register for %s", obj.Headstr(ctxt.Headtype))

			case obj.Hlinux:
				if isAndroid {
					return 0x64 // FS
				}

				if ctxt.Flag_shared != 0 {
					log.Fatalf("unknown TLS base register for linux with -shared")
				} else {
					return 0x64 // FS
				}

			case obj.Hdragonfly,
				obj.Hfreebsd,
				obj.Hnetbsd,
				obj.Hopenbsd,
				obj.Hsolaris:
				return 0x64 // FS

			case obj.Hdarwin:
				return 0x65 // GS
			}
		}
	}

	if p.Mode == 32 {
		if a.Index == REG_TLS && ctxt.Flag_shared != 0 {
			// When building for inclusion into a shared library, an instruction of the form
			//     MOVL 0(CX)(TLS*1), AX
			// becomes
			//     mov %gs:(%ecx), %eax
			// which assumes that the correct TLS offset has been loaded into %ecx (today
			// there is only one TLS variable -- g -- so this is OK). When not building for
			// a shared library the instruction it becomes
			//     mov 0x0(%ecx), $eax
			// and a R_TLS_LE relocation, and so does not require a prefix.
			if a.Offset != 0 {
				ctxt.Diag("cannot handle non-0 offsets to TLS")
			}
			return 0x65 // GS
		}
		return 0
	}

	switch a.Index {
	case REG_CS:
		return 0x2e

	case REG_DS:
		return 0x3e

	case REG_ES:
		return 0x26

	case REG_TLS:
		if ctxt.Flag_shared != 0 {
			// When building for inclusion into a shared library, an instruction of the form
			//     MOV 0(CX)(TLS*1), AX
			// becomes
			//     mov %fs:(%rcx), %rax
			// which assumes that the correct TLS offset has been loaded into %rcx (today
			// there is only one TLS variable -- g -- so this is OK). When not building for
			// a shared library the instruction does not require a prefix.
			if a.Offset != 0 {
				log.Fatalf("cannot handle non-0 offsets to TLS")
			}
			return 0x64
		}

	case REG_FS:
		return 0x64

	case REG_GS:
		return 0x65
	}

	return 0
}

func oclass(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) int {
	switch a.Type {
	case obj.TYPE_NONE:
		return Ynone

	case obj.TYPE_BRANCH:
		return Ybr

	case obj.TYPE_INDIR:
		if a.Name != obj.NAME_NONE && a.Reg == REG_NONE && a.Index == REG_NONE && a.Scale == 0 {
			return Yindir
		}
		return Yxxx

	case obj.TYPE_MEM:
		return Ym

	case obj.TYPE_ADDR:
		switch a.Name {
		case obj.NAME_GOTREF:
			ctxt.Diag("unexpected TYPE_ADDR with NAME_GOTREF")
			return Yxxx

		case obj.NAME_EXTERN,
			obj.NAME_STATIC:
			if a.Sym != nil && isextern(a.Sym) || (p.Mode == 32 && ctxt.Flag_shared == 0) {
				return Yi32
			}
			return Yiauto // use pc-relative addressing

		case obj.NAME_AUTO,
			obj.NAME_PARAM:
			return Yiauto
		}

		// TODO(rsc): DUFFZERO/DUFFCOPY encoding forgot to set a->index
		// and got Yi32 in an earlier version of this code.
		// Keep doing that until we fix yduff etc.
		if a.Sym != nil && strings.HasPrefix(a.Sym.Name, "runtime.duff") {
			return Yi32
		}

		if a.Sym != nil || a.Name != obj.NAME_NONE {
			ctxt.Diag("unexpected addr: %v", obj.Dconv(p, a))
		}
		fallthrough

		// fall through

	case obj.TYPE_CONST:
		if a.Sym != nil {
			ctxt.Diag("TYPE_CONST with symbol: %v", obj.Dconv(p, a))
		}

		v := a.Offset
		if p.Mode == 32 {
			v = int64(int32(v))
		}
		if v == 0 {
			return Yi0
		}
		if v == 1 {
			return Yi1
		}
		if v >= 0 && v <= 127 {
			return Yu7
		}
		if v >= 0 && v <= 255 {
			return Yu8
		}
		if v >= -128 && v <= 127 {
			return Yi8
		}
		if p.Mode == 32 {
			return Yi32
		}
		l := int32(v)
		if int64(l) == v {
			return Ys32 /* can sign extend */
		}
		if v>>32 == 0 {
			return Yi32 /* unsigned */
		}
		return Yi64

	case obj.TYPE_TEXTSIZE:
		return Ytextsize
	}

	if a.Type != obj.TYPE_REG {
		ctxt.Diag("unexpected addr1: type=%d %v", a.Type, obj.Dconv(p, a))
		return Yxxx
	}

	switch a.Reg {
	case REG_AL:
		return Yal

	case REG_AX:
		return Yax

		/*
			case REG_SPB:
		*/
	case REG_BPB,
		REG_SIB,
		REG_DIB,
		REG_R8B,
		REG_R9B,
		REG_R10B,
		REG_R11B,
		REG_R12B,
		REG_R13B,
		REG_R14B,
		REG_R15B:
		if ctxt.Asmode != 64 {
			return Yxxx
		}
		fallthrough

	case REG_DL,
		REG_BL,
		REG_AH,
		REG_CH,
		REG_DH,
		REG_BH:
		return Yrb

	case REG_CL:
		return Ycl

	case REG_CX:
		return Ycx

	case REG_DX, REG_BX:
		return Yrx

	case REG_R8, /* not really Yrl */
		REG_R9,
		REG_R10,
		REG_R11,
		REG_R12,
		REG_R13,
		REG_R14,
		REG_R15:
		if ctxt.Asmode != 64 {
			return Yxxx
		}
		fallthrough

	case REG_SP, REG_BP, REG_SI, REG_DI:
		if p.Mode == 32 {
			return Yrl32
		}
		return Yrl

	case REG_F0 + 0:
		return Yf0

	case REG_F0 + 1,
		REG_F0 + 2,
		REG_F0 + 3,
		REG_F0 + 4,
		REG_F0 + 5,
		REG_F0 + 6,
		REG_F0 + 7:
		return Yrf

	case REG_M0 + 0,
		REG_M0 + 1,
		REG_M0 + 2,
		REG_M0 + 3,
		REG_M0 + 4,
		REG_M0 + 5,
		REG_M0 + 6,
		REG_M0 + 7:
		return Ymr

	case REG_X0 + 0,
		REG_X0 + 1,
		REG_X0 + 2,
		REG_X0 + 3,
		REG_X0 + 4,
		REG_X0 + 5,
		REG_X0 + 6,
		REG_X0 + 7,
		REG_X0 + 8,
		REG_X0 + 9,
		REG_X0 + 10,
		REG_X0 + 11,
		REG_X0 + 12,
		REG_X0 + 13,
		REG_X0 + 14,
		REG_X0 + 15:
		return Yxr

	case REG_CS:
		return Ycs
	case REG_SS:
		return Yss
	case REG_DS:
		return Yds
	case REG_ES:
		return Yes
	case REG_FS:
		return Yfs
	case REG_GS:
		return Ygs
	case REG_TLS:
		return Ytls

	case REG_GDTR:
		return Ygdtr
	case REG_IDTR:
		return Yidtr
	case REG_LDTR:
		return Yldtr
	case REG_MSW:
		return Ymsw
	case REG_TASK:
		return Ytask

	case REG_CR + 0:
		return Ycr0
	case REG_CR + 1:
		return Ycr1
	case REG_CR + 2:
		return Ycr2
	case REG_CR + 3:
		return Ycr3
	case REG_CR + 4:
		return Ycr4
	case REG_CR + 5:
		return Ycr5
	case REG_CR + 6:
		return Ycr6
	case REG_CR + 7:
		return Ycr7
	case REG_CR + 8:
		return Ycr8

	case REG_DR + 0:
		return Ydr0
	case REG_DR + 1:
		return Ydr1
	case REG_DR + 2:
		return Ydr2
	case REG_DR + 3:
		return Ydr3
	case REG_DR + 4:
		return Ydr4
	case REG_DR + 5:
		return Ydr5
	case REG_DR + 6:
		return Ydr6
	case REG_DR + 7:
		return Ydr7

	case REG_TR + 0:
		return Ytr0
	case REG_TR + 1:
		return Ytr1
	case REG_TR + 2:
		return Ytr2
	case REG_TR + 3:
		return Ytr3
	case REG_TR + 4:
		return Ytr4
	case REG_TR + 5:
		return Ytr5
	case REG_TR + 6:
		return Ytr6
	case REG_TR + 7:
		return Ytr7
	}

	return Yxxx
}

func asmidx(ctxt *obj.Link, scale int, index int, base int) {
	var i int

	switch index {
	default:
		goto bad

	case REG_NONE:
		i = 4 << 3
		goto bas

	case REG_R8,
		REG_R9,
		REG_R10,
		REG_R11,
		REG_R12,
		REG_R13,
		REG_R14,
		REG_R15:
		if ctxt.Asmode != 64 {
			goto bad
		}
		fallthrough

	case REG_AX,
		REG_CX,
		REG_DX,
		REG_BX,
		REG_BP,
		REG_SI,
		REG_DI:
		i = reg[index] << 3
	}

	switch scale {
	default:
		goto bad

	case 1:
		break

	case 2:
		i |= 1 << 6

	case 4:
		i |= 2 << 6

	case 8:
		i |= 3 << 6
	}

bas:
	switch base {
	default:
		goto bad

	case REG_NONE: /* must be mod=00 */
		i |= 5

	case REG_R8,
		REG_R9,
		REG_R10,
		REG_R11,
		REG_R12,
		REG_R13,
		REG_R14,
		REG_R15:
		if ctxt.Asmode != 64 {
			goto bad
		}
		fallthrough

	case REG_AX,
		REG_CX,
		REG_DX,
		REG_BX,
		REG_SP,
		REG_BP,
		REG_SI,
		REG_DI:
		i |= reg[base]
	}

	ctxt.Andptr[0] = byte(i)
	ctxt.Andptr = ctxt.Andptr[1:]
	return

bad:
	ctxt.Diag("asmidx: bad address %d/%d/%d", scale, index, base)
	ctxt.Andptr[0] = 0
	ctxt.Andptr = ctxt.Andptr[1:]
	return
}

func put4(ctxt *obj.Link, v int32) {
	ctxt.Andptr[0] = byte(v)
	ctxt.Andptr[1] = byte(v >> 8)
	ctxt.Andptr[2] = byte(v >> 16)
	ctxt.Andptr[3] = byte(v >> 24)
	ctxt.Andptr = ctxt.Andptr[4:]
}

func relput4(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
	var rel obj.Reloc

	v := vaddr(ctxt, p, a, &rel)
	if rel.Siz != 0 {
		if rel.Siz != 4 {
			ctxt.Diag("bad reloc")
		}
		r := obj.Addrel(ctxt.Cursym)
		*r = rel
		r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
	}

	put4(ctxt, int32(v))
}

func put8(ctxt *obj.Link, v int64) {
	ctxt.Andptr[0] = byte(v)
	ctxt.Andptr[1] = byte(v >> 8)
	ctxt.Andptr[2] = byte(v >> 16)
	ctxt.Andptr[3] = byte(v >> 24)
	ctxt.Andptr[4] = byte(v >> 32)
	ctxt.Andptr[5] = byte(v >> 40)
	ctxt.Andptr[6] = byte(v >> 48)
	ctxt.Andptr[7] = byte(v >> 56)
	ctxt.Andptr = ctxt.Andptr[8:]
}

/*
static void
relput8(Prog *p, Addr *a)
{
	vlong v;
	Reloc rel, *r;

	v = vaddr(ctxt, p, a, &rel);
	if(rel.siz != 0) {
		r = addrel(ctxt->cursym);
		*r = rel;
		r->siz = 8;
		r->off = p->pc + ctxt->andptr - ctxt->and;
	}
	put8(ctxt, v);
}
*/
func vaddr(ctxt *obj.Link, p *obj.Prog, a *obj.Addr, r *obj.Reloc) int64 {
	if r != nil {
		*r = obj.Reloc{}
	}

	switch a.Name {
	case obj.NAME_STATIC,
		obj.NAME_GOTREF,
		obj.NAME_EXTERN:
		s := a.Sym
		if r == nil {
			ctxt.Diag("need reloc for %v", obj.Dconv(p, a))
			log.Fatalf("reloc")
		}

		if a.Name == obj.NAME_GOTREF {
			r.Siz = 4
			r.Type = obj.R_GOTPCREL
		} else if isextern(s) || (p.Mode != 64 && ctxt.Flag_shared == 0) {
			r.Siz = 4
			r.Type = obj.R_ADDR
		} else {
			r.Siz = 4
			r.Type = obj.R_PCREL
		}

		r.Off = -1 // caller must fill in
		r.Sym = s
		r.Add = a.Offset

		return 0
	}

	if (a.Type == obj.TYPE_MEM || a.Type == obj.TYPE_ADDR) && a.Reg == REG_TLS {
		if r == nil {
			ctxt.Diag("need reloc for %v", obj.Dconv(p, a))
			log.Fatalf("reloc")
		}

		if ctxt.Flag_shared == 0 || isAndroid {
			r.Type = obj.R_TLS_LE
			r.Siz = 4
			r.Off = -1 // caller must fill in
			r.Add = a.Offset
		}
		return 0
	}

	return a.Offset
}

func asmandsz(ctxt *obj.Link, p *obj.Prog, a *obj.Addr, r int, rex int, m64 int) {
	var base int
	var rel obj.Reloc

	rex &= 0x40 | Rxr
	v := int32(a.Offset)
	rel.Siz = 0

	switch a.Type {
	case obj.TYPE_ADDR:
		if a.Name == obj.NAME_NONE {
			ctxt.Diag("unexpected TYPE_ADDR with NAME_NONE")
		}
		if a.Index == REG_TLS {
			ctxt.Diag("unexpected TYPE_ADDR with index==REG_TLS")
		}
		goto bad

	case obj.TYPE_REG:
		if a.Reg < REG_AL || REG_X0+15 < a.Reg {
			goto bad
		}
		if v != 0 {
			goto bad
		}
		ctxt.Andptr[0] = byte(3<<6 | reg[a.Reg]<<0 | r<<3)
		ctxt.Andptr = ctxt.Andptr[1:]
		ctxt.Rexflag |= regrex[a.Reg]&(0x40|Rxb) | rex
		return
	}

	if a.Type != obj.TYPE_MEM {
		goto bad
	}

	if a.Index != REG_NONE && a.Index != REG_TLS {
		base := int(a.Reg)
		switch a.Name {
		case obj.NAME_EXTERN,
			obj.NAME_GOTREF,
			obj.NAME_STATIC:
			if !isextern(a.Sym) && p.Mode == 64 {
				goto bad
			}
			if p.Mode == 32 && ctxt.Flag_shared != 0 {
				base = REG_CX
			} else {
				base = REG_NONE
			}
			v = int32(vaddr(ctxt, p, a, &rel))

		case obj.NAME_AUTO,
			obj.NAME_PARAM:
			base = REG_SP
		}

		ctxt.Rexflag |= regrex[int(a.Index)]&Rxx | regrex[base]&Rxb | rex
		if base == REG_NONE {
			ctxt.Andptr[0] = byte(0<<6 | 4<<0 | r<<3)
			ctxt.Andptr = ctxt.Andptr[1:]
			asmidx(ctxt, int(a.Scale), int(a.Index), base)
			goto putrelv
		}

		if v == 0 && rel.Siz == 0 && base != REG_BP && base != REG_R13 {
			ctxt.Andptr[0] = byte(0<<6 | 4<<0 | r<<3)
			ctxt.Andptr = ctxt.Andptr[1:]
			asmidx(ctxt, int(a.Scale), int(a.Index), base)
			return
		}

		if v >= -128 && v < 128 && rel.Siz == 0 {
			ctxt.Andptr[0] = byte(1<<6 | 4<<0 | r<<3)
			ctxt.Andptr = ctxt.Andptr[1:]
			asmidx(ctxt, int(a.Scale), int(a.Index), base)
			ctxt.Andptr[0] = byte(v)
			ctxt.Andptr = ctxt.Andptr[1:]
			return
		}

		ctxt.Andptr[0] = byte(2<<6 | 4<<0 | r<<3)
		ctxt.Andptr = ctxt.Andptr[1:]
		asmidx(ctxt, int(a.Scale), int(a.Index), base)
		goto putrelv
	}

	base = int(a.Reg)
	switch a.Name {
	case obj.NAME_STATIC,
		obj.NAME_GOTREF,
		obj.NAME_EXTERN:
		if a.Sym == nil {
			ctxt.Diag("bad addr: %v", p)
		}
		if p.Mode == 32 && ctxt.Flag_shared != 0 {
			base = REG_CX
		} else {
			base = REG_NONE
		}
		v = int32(vaddr(ctxt, p, a, &rel))

	case obj.NAME_AUTO,
		obj.NAME_PARAM:
		base = REG_SP
	}

	if base == REG_TLS {
		v = int32(vaddr(ctxt, p, a, &rel))
	}

	ctxt.Rexflag |= regrex[base]&Rxb | rex
	if base == REG_NONE || (REG_CS <= base && base <= REG_GS) || base == REG_TLS {
		if (a.Sym == nil || !isextern(a.Sym)) && base == REG_NONE && (a.Name == obj.NAME_STATIC || a.Name == obj.NAME_EXTERN || a.Name == obj.NAME_GOTREF) || p.Mode != 64 {
			if a.Name == obj.NAME_GOTREF && (a.Offset != 0 || a.Index != 0 || a.Scale != 0) {
				ctxt.Diag("%v has offset against gotref", p)
			}
			ctxt.Andptr[0] = byte(0<<6 | 5<<0 | r<<3)
			ctxt.Andptr = ctxt.Andptr[1:]
			goto putrelv
		}

		/* temporary */
		ctxt.Andptr[0] = byte(0<<6 | 4<<0 | r<<3)
		ctxt.Andptr = ctxt.Andptr[1:] /* sib present */
		ctxt.Andptr[0] = 0<<6 | 4<<3 | 5<<0
		ctxt.Andptr = ctxt.Andptr[1:] /* DS:d32 */
		goto putrelv
	}

	if base == REG_SP || base == REG_R12 {
		if v == 0 {
			ctxt.Andptr[0] = byte(0<<6 | reg[base]<<0 | r<<3)
			ctxt.Andptr = ctxt.Andptr[1:]
			asmidx(ctxt, int(a.Scale), REG_NONE, base)
			return
		}

		if v >= -128 && v < 128 {
			ctxt.Andptr[0] = byte(1<<6 | reg[base]<<0 | r<<3)
			ctxt.Andptr = ctxt.Andptr[1:]
			asmidx(ctxt, int(a.Scale), REG_NONE, base)
			ctxt.Andptr[0] = byte(v)
			ctxt.Andptr = ctxt.Andptr[1:]
			return
		}

		ctxt.Andptr[0] = byte(2<<6 | reg[base]<<0 | r<<3)
		ctxt.Andptr = ctxt.Andptr[1:]
		asmidx(ctxt, int(a.Scale), REG_NONE, base)
		goto putrelv
	}

	if REG_AX <= base && base <= REG_R15 {
		if a.Index == REG_TLS && ctxt.Flag_shared == 0 {
			rel = obj.Reloc{}
			rel.Type = obj.R_TLS_LE
			rel.Siz = 4
			rel.Sym = nil
			rel.Add = int64(v)
			v = 0
		}

		if v == 0 && rel.Siz == 0 && base != REG_BP && base != REG_R13 {
			ctxt.Andptr[0] = byte(0<<6 | reg[base]<<0 | r<<3)
			ctxt.Andptr = ctxt.Andptr[1:]
			return
		}

		if v >= -128 && v < 128 && rel.Siz == 0 {
			ctxt.Andptr[0] = byte(1<<6 | reg[base]<<0 | r<<3)
			ctxt.Andptr[1] = byte(v)
			ctxt.Andptr = ctxt.Andptr[2:]
			return
		}

		ctxt.Andptr[0] = byte(2<<6 | reg[base]<<0 | r<<3)
		ctxt.Andptr = ctxt.Andptr[1:]
		goto putrelv
	}

	goto bad

putrelv:
	if rel.Siz != 0 {
		if rel.Siz != 4 {
			ctxt.Diag("bad rel")
			goto bad
		}

		r := obj.Addrel(ctxt.Cursym)
		*r = rel
		r.Off = int32(ctxt.Curp.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
	}

	put4(ctxt, v)
	return

bad:
	ctxt.Diag("asmand: bad address %v", obj.Dconv(p, a))
	return
}

func asmand(ctxt *obj.Link, p *obj.Prog, a *obj.Addr, ra *obj.Addr) {
	asmandsz(ctxt, p, a, reg[ra.Reg], regrex[ra.Reg], 0)
}

func asmando(ctxt *obj.Link, p *obj.Prog, a *obj.Addr, o int) {
	asmandsz(ctxt, p, a, o, 0, 0)
}

func bytereg(a *obj.Addr, t *uint8) {
	if a.Type == obj.TYPE_REG && a.Index == REG_NONE && (REG_AX <= a.Reg && a.Reg <= REG_R15) {
		a.Reg += REG_AL - REG_AX
		*t = 0
	}
}

func unbytereg(a *obj.Addr, t *uint8) {
	if a.Type == obj.TYPE_REG && a.Index == REG_NONE && (REG_AL <= a.Reg && a.Reg <= REG_R15B) {
		a.Reg += REG_AX - REG_AL
		*t = 0
	}
}

const (
	E = 0xff
)

var ymovtab = []Movtab{
	/* push */
	{APUSHL, Ycs, Ynone, Ynone, 0, [4]uint8{0x0e, E, 0, 0}},
	{APUSHL, Yss, Ynone, Ynone, 0, [4]uint8{0x16, E, 0, 0}},
	{APUSHL, Yds, Ynone, Ynone, 0, [4]uint8{0x1e, E, 0, 0}},
	{APUSHL, Yes, Ynone, Ynone, 0, [4]uint8{0x06, E, 0, 0}},
	{APUSHL, Yfs, Ynone, Ynone, 0, [4]uint8{0x0f, 0xa0, E, 0}},
	{APUSHL, Ygs, Ynone, Ynone, 0, [4]uint8{0x0f, 0xa8, E, 0}},
	{APUSHQ, Yfs, Ynone, Ynone, 0, [4]uint8{0x0f, 0xa0, E, 0}},
	{APUSHQ, Ygs, Ynone, Ynone, 0, [4]uint8{0x0f, 0xa8, E, 0}},
	{APUSHW, Ycs, Ynone, Ynone, 0, [4]uint8{Pe, 0x0e, E, 0}},
	{APUSHW, Yss, Ynone, Ynone, 0, [4]uint8{Pe, 0x16, E, 0}},
	{APUSHW, Yds, Ynone, Ynone, 0, [4]uint8{Pe, 0x1e, E, 0}},
	{APUSHW, Yes, Ynone, Ynone, 0, [4]uint8{Pe, 0x06, E, 0}},
	{APUSHW, Yfs, Ynone, Ynone, 0, [4]uint8{Pe, 0x0f, 0xa0, E}},
	{APUSHW, Ygs, Ynone, Ynone, 0, [4]uint8{Pe, 0x0f, 0xa8, E}},

	/* pop */
	{APOPL, Ynone, Ynone, Yds, 0, [4]uint8{0x1f, E, 0, 0}},
	{APOPL, Ynone, Ynone, Yes, 0, [4]uint8{0x07, E, 0, 0}},
	{APOPL, Ynone, Ynone, Yss, 0, [4]uint8{0x17, E, 0, 0}},
	{APOPL, Ynone, Ynone, Yfs, 0, [4]uint8{0x0f, 0xa1, E, 0}},
	{APOPL, Ynone, Ynone, Ygs, 0, [4]uint8{0x0f, 0xa9, E, 0}},
	{APOPQ, Ynone, Ynone, Yfs, 0, [4]uint8{0x0f, 0xa1, E, 0}},
	{APOPQ, Ynone, Ynone, Ygs, 0, [4]uint8{0x0f, 0xa9, E, 0}},
	{APOPW, Ynone, Ynone, Yds, 0, [4]uint8{Pe, 0x1f, E, 0}},
	{APOPW, Ynone, Ynone, Yes, 0, [4]uint8{Pe, 0x07, E, 0}},
	{APOPW, Ynone, Ynone, Yss, 0, [4]uint8{Pe, 0x17, E, 0}},
	{APOPW, Ynone, Ynone, Yfs, 0, [4]uint8{Pe, 0x0f, 0xa1, E}},
	{APOPW, Ynone, Ynone, Ygs, 0, [4]uint8{Pe, 0x0f, 0xa9, E}},

	/* mov seg */
	{AMOVW, Yes, Ynone, Yml, 1, [4]uint8{0x8c, 0, 0, 0}},
	{AMOVW, Ycs, Ynone, Yml, 1, [4]uint8{0x8c, 1, 0, 0}},
	{AMOVW, Yss, Ynone, Yml, 1, [4]uint8{0x8c, 2, 0, 0}},
	{AMOVW, Yds, Ynone, Yml, 1, [4]uint8{0x8c, 3, 0, 0}},
	{AMOVW, Yfs, Ynone, Yml, 1, [4]uint8{0x8c, 4, 0, 0}},
	{AMOVW, Ygs, Ynone, Yml, 1, [4]uint8{0x8c, 5, 0, 0}},
	{AMOVW, Yml, Ynone, Yes, 2, [4]uint8{0x8e, 0, 0, 0}},
	{AMOVW, Yml, Ynone, Ycs, 2, [4]uint8{0x8e, 1, 0, 0}},
	{AMOVW, Yml, Ynone, Yss, 2, [4]uint8{0x8e, 2, 0, 0}},
	{AMOVW, Yml, Ynone, Yds, 2, [4]uint8{0x8e, 3, 0, 0}},
	{AMOVW, Yml, Ynone, Yfs, 2, [4]uint8{0x8e, 4, 0, 0}},
	{AMOVW, Yml, Ynone, Ygs, 2, [4]uint8{0x8e, 5, 0, 0}},

	/* mov cr */
	{AMOVL, Ycr0, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 0, 0}},
	{AMOVL, Ycr2, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 2, 0}},
	{AMOVL, Ycr3, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 3, 0}},
	{AMOVL, Ycr4, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 4, 0}},
	{AMOVL, Ycr8, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 8, 0}},
	{AMOVQ, Ycr0, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 0, 0}},
	{AMOVQ, Ycr2, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 2, 0}},
	{AMOVQ, Ycr3, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 3, 0}},
	{AMOVQ, Ycr4, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 4, 0}},
	{AMOVQ, Ycr8, Ynone, Yml, 3, [4]uint8{0x0f, 0x20, 8, 0}},
	{AMOVL, Yml, Ynone, Ycr0, 4, [4]uint8{0x0f, 0x22, 0, 0}},
	{AMOVL, Yml, Ynone, Ycr2, 4, [4]uint8{0x0f, 0x22, 2, 0}},
	{AMOVL, Yml, Ynone, Ycr3, 4, [4]uint8{0x0f, 0x22, 3, 0}},
	{AMOVL, Yml, Ynone, Ycr4, 4, [4]uint8{0x0f, 0x22, 4, 0}},
	{AMOVL, Yml, Ynone, Ycr8, 4, [4]uint8{0x0f, 0x22, 8, 0}},
	{AMOVQ, Yml, Ynone, Ycr0, 4, [4]uint8{0x0f, 0x22, 0, 0}},
	{AMOVQ, Yml, Ynone, Ycr2, 4, [4]uint8{0x0f, 0x22, 2, 0}},
	{AMOVQ, Yml, Ynone, Ycr3, 4, [4]uint8{0x0f, 0x22, 3, 0}},
	{AMOVQ, Yml, Ynone, Ycr4, 4, [4]uint8{0x0f, 0x22, 4, 0}},
	{AMOVQ, Yml, Ynone, Ycr8, 4, [4]uint8{0x0f, 0x22, 8, 0}},

	/* mov dr */
	{AMOVL, Ydr0, Ynone, Yml, 3, [4]uint8{0x0f, 0x21, 0, 0}},
	{AMOVL, Ydr6, Ynone, Yml, 3, [4]uint8{0x0f, 0x21, 6, 0}},
	{AMOVL, Ydr7, Ynone, Yml, 3, [4]uint8{0x0f, 0x21, 7, 0}},
	{AMOVQ, Ydr0, Ynone, Yml, 3, [4]uint8{0x0f, 0x21, 0, 0}},
	{AMOVQ, Ydr6, Ynone, Yml, 3, [4]uint8{0x0f, 0x21, 6, 0}},
	{AMOVQ, Ydr7, Ynone, Yml, 3, [4]uint8{0x0f, 0x21, 7, 0}},
	{AMOVL, Yml, Ynone, Ydr0, 4, [4]uint8{0x0f, 0x23, 0, 0}},
	{AMOVL, Yml, Ynone, Ydr6, 4, [4]uint8{0x0f, 0x23, 6, 0}},
	{AMOVL, Yml, Ynone, Ydr7, 4, [4]uint8{0x0f, 0x23, 7, 0}},
	{AMOVQ, Yml, Ynone, Ydr0, 4, [4]uint8{0x0f, 0x23, 0, 0}},
	{AMOVQ, Yml, Ynone, Ydr6, 4, [4]uint8{0x0f, 0x23, 6, 0}},
	{AMOVQ, Yml, Ynone, Ydr7, 4, [4]uint8{0x0f, 0x23, 7, 0}},

	/* mov tr */
	{AMOVL, Ytr6, Ynone, Yml, 3, [4]uint8{0x0f, 0x24, 6, 0}},
	{AMOVL, Ytr7, Ynone, Yml, 3, [4]uint8{0x0f, 0x24, 7, 0}},
	{AMOVL, Yml, Ynone, Ytr6, 4, [4]uint8{0x0f, 0x26, 6, E}},
	{AMOVL, Yml, Ynone, Ytr7, 4, [4]uint8{0x0f, 0x26, 7, E}},

	/* lgdt, sgdt, lidt, sidt */
	{AMOVL, Ym, Ynone, Ygdtr, 4, [4]uint8{0x0f, 0x01, 2, 0}},
	{AMOVL, Ygdtr, Ynone, Ym, 3, [4]uint8{0x0f, 0x01, 0, 0}},
	{AMOVL, Ym, Ynone, Yidtr, 4, [4]uint8{0x0f, 0x01, 3, 0}},
	{AMOVL, Yidtr, Ynone, Ym, 3, [4]uint8{0x0f, 0x01, 1, 0}},
	{AMOVQ, Ym, Ynone, Ygdtr, 4, [4]uint8{0x0f, 0x01, 2, 0}},
	{AMOVQ, Ygdtr, Ynone, Ym, 3, [4]uint8{0x0f, 0x01, 0, 0}},
	{AMOVQ, Ym, Ynone, Yidtr, 4, [4]uint8{0x0f, 0x01, 3, 0}},
	{AMOVQ, Yidtr, Ynone, Ym, 3, [4]uint8{0x0f, 0x01, 1, 0}},

	/* lldt, sldt */
	{AMOVW, Yml, Ynone, Yldtr, 4, [4]uint8{0x0f, 0x00, 2, 0}},
	{AMOVW, Yldtr, Ynone, Yml, 3, [4]uint8{0x0f, 0x00, 0, 0}},

	/* lmsw, smsw */
	{AMOVW, Yml, Ynone, Ymsw, 4, [4]uint8{0x0f, 0x01, 6, 0}},
	{AMOVW, Ymsw, Ynone, Yml, 3, [4]uint8{0x0f, 0x01, 4, 0}},

	/* ltr, str */
	{AMOVW, Yml, Ynone, Ytask, 4, [4]uint8{0x0f, 0x00, 3, 0}},
	{AMOVW, Ytask, Ynone, Yml, 3, [4]uint8{0x0f, 0x00, 1, 0}},

	/* load full pointer - unsupported
	Movtab{AMOVL, Yml, Ycol, 5, [4]uint8{0, 0, 0, 0}},
	Movtab{AMOVW, Yml, Ycol, 5, [4]uint8{Pe, 0, 0, 0}},
	*/

	/* double shift */
	{ASHLL, Yi8, Yrl, Yml, 6, [4]uint8{0xa4, 0xa5, 0, 0}},
	{ASHLL, Ycl, Yrl, Yml, 6, [4]uint8{0xa4, 0xa5, 0, 0}},
	{ASHLL, Ycx, Yrl, Yml, 6, [4]uint8{0xa4, 0xa5, 0, 0}},
	{ASHRL, Yi8, Yrl, Yml, 6, [4]uint8{0xac, 0xad, 0, 0}},
	{ASHRL, Ycl, Yrl, Yml, 6, [4]uint8{0xac, 0xad, 0, 0}},
	{ASHRL, Ycx, Yrl, Yml, 6, [4]uint8{0xac, 0xad, 0, 0}},
	{ASHLQ, Yi8, Yrl, Yml, 6, [4]uint8{Pw, 0xa4, 0xa5, 0}},
	{ASHLQ, Ycl, Yrl, Yml, 6, [4]uint8{Pw, 0xa4, 0xa5, 0}},
	{ASHLQ, Ycx, Yrl, Yml, 6, [4]uint8{Pw, 0xa4, 0xa5, 0}},
	{ASHRQ, Yi8, Yrl, Yml, 6, [4]uint8{Pw, 0xac, 0xad, 0}},
	{ASHRQ, Ycl, Yrl, Yml, 6, [4]uint8{Pw, 0xac, 0xad, 0}},
	{ASHRQ, Ycx, Yrl, Yml, 6, [4]uint8{Pw, 0xac, 0xad, 0}},
	{ASHLW, Yi8, Yrl, Yml, 6, [4]uint8{Pe, 0xa4, 0xa5, 0}},
	{ASHLW, Ycl, Yrl, Yml, 6, [4]uint8{Pe, 0xa4, 0xa5, 0}},
	{ASHLW, Ycx, Yrl, Yml, 6, [4]uint8{Pe, 0xa4, 0xa5, 0}},
	{ASHRW, Yi8, Yrl, Yml, 6, [4]uint8{Pe, 0xac, 0xad, 0}},
	{ASHRW, Ycl, Yrl, Yml, 6, [4]uint8{Pe, 0xac, 0xad, 0}},
	{ASHRW, Ycx, Yrl, Yml, 6, [4]uint8{Pe, 0xac, 0xad, 0}},

	/* load TLS base */
	{AMOVL, Ytls, Ynone, Yrl, 7, [4]uint8{0, 0, 0, 0}},
	{AMOVQ, Ytls, Ynone, Yrl, 7, [4]uint8{0, 0, 0, 0}},
	{0, 0, 0, 0, 0, [4]uint8{}},
}

func isax(a *obj.Addr) bool {
	switch a.Reg {
	case REG_AX, REG_AL, REG_AH:
		return true
	}

	if a.Index == REG_AX {
		return true
	}
	return false
}

func subreg(p *obj.Prog, from int, to int) {
	if false { /* debug['Q'] */
		fmt.Printf("\n%v\ts/%v/%v/\n", p, Rconv(from), Rconv(to))
	}

	if int(p.From.Reg) == from {
		p.From.Reg = int16(to)
		p.Ft = 0
	}

	if int(p.To.Reg) == from {
		p.To.Reg = int16(to)
		p.Tt = 0
	}

	if int(p.From.Index) == from {
		p.From.Index = int16(to)
		p.Ft = 0
	}

	if int(p.To.Index) == from {
		p.To.Index = int16(to)
		p.Tt = 0
	}

	if false { /* debug['Q'] */
		fmt.Printf("%v\n", p)
	}
}

func mediaop(ctxt *obj.Link, o *Optab, op int, osize int, z int) int {
	switch op {
	case Pm, Pe, Pf2, Pf3:
		if osize != 1 {
			if op != Pm {
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
			}
			ctxt.Andptr[0] = Pm
			ctxt.Andptr = ctxt.Andptr[1:]
			z++
			op = int(o.op[z])
			break
		}
		fallthrough

	default:
		if -cap(ctxt.Andptr) == -cap(ctxt.And) || ctxt.And[-cap(ctxt.Andptr)+cap(ctxt.And[:])-1] != Pm {
			ctxt.Andptr[0] = Pm
			ctxt.Andptr = ctxt.Andptr[1:]
		}
	}

	ctxt.Andptr[0] = byte(op)
	ctxt.Andptr = ctxt.Andptr[1:]
	return z
}

var bpduff1 = []byte{
	0x48, 0x89, 0x6c, 0x24, 0xf0, // MOVQ BP, -16(SP)
	0x48, 0x8d, 0x6c, 0x24, 0xf0, // LEAQ -16(SP), BP
}

var bpduff2 = []byte{
	0x48, 0x8b, 0x6d, 0x00, // MOVQ 0(BP), BP
}

// Assemble vex prefix, from 3 operands and prefix.
// For details about vex prefix see:
// https://en.wikipedia.org/wiki/VEX_prefix#Technical_description
func vexprefix(ctxt *obj.Link, to *obj.Addr, from *obj.Addr, from3 *obj.Addr, pref uint8) {
	rexR := regrex[to.Reg]
	rexB := regrex[from.Reg]
	rexX := regrex[from.Index]
	var prefBit uint8
	// This will go into VEX.PP field.
	if pref == Pvex1 || pref == Pvex3 {
		prefBit = 1
	} else if pref == Pvex2 {
		prefBit = 2
	} // TODO add Pvex0

	if rexX == 0 && rexB == 0 && pref != Pvex3 { // 2-byte vex prefix
		// In 2-byte case, first byte is always C5
		ctxt.Andptr[0] = 0xc5
		ctxt.Andptr = ctxt.Andptr[1:]

		if from3 == nil {
			// If this is a 2-operand instruction fill VEX.VVVV with 1111
			// We are also interested only in 256-bit version, so VEX.L=1
			ctxt.Andptr[0] = 0x7c
		} else {
			// VEX.L=1
			ctxt.Andptr[0] = 0x4
			// VEX.VVVV (bits 3:6) is a inversed register number
			ctxt.Andptr[0] |= byte((^(from3.Reg - REG_X0))<<3) & 0x78
		}

		// VEX encodes REX.R as inversed upper bit
		if rexR == 0 {
			ctxt.Andptr[0] |= 0x80
		}
		ctxt.Andptr[0] |= prefBit
		ctxt.Andptr = ctxt.Andptr[1:]
	} else { // 3-byte case
		// First byte is always C$
		ctxt.Andptr[0] = 0xc4
		ctxt.Andptr = ctxt.Andptr[1:]

		// Encode VEX.mmmmm with prefix value, assume 0F,
		// which encodes as 1, unless 0F38 was specified with pvex3.
		ctxt.Andptr[0] = 0x1 // TODO handle 0F3A
		if pref == Pvex3 {
			ctxt.Andptr[0] = 0x2
		}

		// REX.[RXB] are inverted and encoded in 3 upper bits
		if rexR == 0 {
			ctxt.Andptr[0] |= 0x80
		}
		if rexX == 0 {
			ctxt.Andptr[0] |= 0x40
		}
		if rexB == 0 {
			ctxt.Andptr[0] |= 0x20
		}
		ctxt.Andptr = ctxt.Andptr[1:]

		// Fill VEX.VVVV, same as 2-operand VEX instruction.
		if from3 == nil {
			ctxt.Andptr[0] = 0x7c
		} else {
			ctxt.Andptr[0] = 0x4
			ctxt.Andptr[0] |= byte((^(from3.Reg - REG_X0))<<3) & 0x78
		}
		ctxt.Andptr[0] |= prefBit
		ctxt.Andptr = ctxt.Andptr[1:]
	}
}

func doasm(ctxt *obj.Link, p *obj.Prog) {
	ctxt.Curp = p // TODO

	o := opindex[p.As&obj.AMask]

	if o == nil {
		ctxt.Diag("asmins: missing op %v", p)
		return
	}

	pre := prefixof(ctxt, p, &p.From)
	if pre != 0 {
		ctxt.Andptr[0] = byte(pre)
		ctxt.Andptr = ctxt.Andptr[1:]
	}
	pre = prefixof(ctxt, p, &p.To)
	if pre != 0 {
		ctxt.Andptr[0] = byte(pre)
		ctxt.Andptr = ctxt.Andptr[1:]
	}

	// TODO(rsc): This special case is for SHRQ $3, AX:DX,
	// which encodes as SHRQ $32(DX*0), AX.
	// Similarly SHRQ CX, AX:DX is really SHRQ CX(DX*0), AX.
	// Change encoding generated by assemblers and compilers and remove.
	if (p.From.Type == obj.TYPE_CONST || p.From.Type == obj.TYPE_REG) && p.From.Index != REG_NONE && p.From.Scale == 0 {
		p.From3 = new(obj.Addr)
		p.From3.Type = obj.TYPE_REG
		p.From3.Reg = p.From.Index
		p.From.Index = 0
	}

	// TODO(rsc): This special case is for PINSRQ etc, CMPSD etc.
	// Change encoding generated by assemblers and compilers (if any) and remove.
	switch p.As {
	case AIMUL3Q, APEXTRW, APINSRW, APINSRD, APINSRQ, APSHUFHW, APSHUFL, APSHUFW, ASHUFPD, ASHUFPS, AAESKEYGENASSIST, APSHUFD, APCLMULQDQ:
		if p.From3Type() == obj.TYPE_NONE {
			p.From3 = new(obj.Addr)
			*p.From3 = p.From
			p.From = obj.Addr{}
			p.From.Type = obj.TYPE_CONST
			p.From.Offset = p.To.Offset
			p.To.Offset = 0
		}
	case ACMPSD, ACMPSS, ACMPPS, ACMPPD:
		if p.From3Type() == obj.TYPE_NONE {
			p.From3 = new(obj.Addr)
			*p.From3 = p.To
			p.To = obj.Addr{}
			p.To.Type = obj.TYPE_CONST
			p.To.Offset = p.From3.Offset
			p.From3.Offset = 0
		}
	}

	if p.Ft == 0 {
		p.Ft = uint8(oclass(ctxt, p, &p.From))
	}
	if p.Tt == 0 {
		p.Tt = uint8(oclass(ctxt, p, &p.To))
	}

	ft := int(p.Ft) * Ymax
	f3t := Ynone * Ymax
	if p.From3 != nil {
		f3t = oclass(ctxt, p, p.From3) * Ymax
	}
	tt := int(p.Tt) * Ymax

	xo := obj.Bool2int(o.op[0] == 0x0f)
	z := 0
	var a *obj.Addr
	var l int
	var op int
	var q *obj.Prog
	var r *obj.Reloc
	var rel obj.Reloc
	var v int64
	for i := range o.ytab {
		yt := &o.ytab[i]
		if ycover[ft+int(yt.from)] != 0 && ycover[f3t+int(yt.from3)] != 0 && ycover[tt+int(yt.to)] != 0 {
			switch o.prefix {
			case Px1: /* first option valid only in 32-bit mode */
				if ctxt.Mode == 64 && z == 0 {
					z += int(yt.zoffset) + xo
					continue
				}
			case Pq: /* 16 bit escape and opcode escape */
				ctxt.Andptr[0] = Pe
				ctxt.Andptr = ctxt.Andptr[1:]

				ctxt.Andptr[0] = Pm
				ctxt.Andptr = ctxt.Andptr[1:]

			case Pq3: /* 16 bit escape, Rex.w, and opcode escape */
				ctxt.Andptr[0] = Pe
				ctxt.Andptr = ctxt.Andptr[1:]

				ctxt.Andptr[0] = Pw
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = Pm
				ctxt.Andptr = ctxt.Andptr[1:]

			case Pf2, /* xmm opcode escape */
				Pf3:
				ctxt.Andptr[0] = byte(o.prefix)
				ctxt.Andptr = ctxt.Andptr[1:]

				ctxt.Andptr[0] = Pm
				ctxt.Andptr = ctxt.Andptr[1:]

			case Pm: /* opcode escape */
				ctxt.Andptr[0] = Pm
				ctxt.Andptr = ctxt.Andptr[1:]

			case Pe: /* 16 bit escape */
				ctxt.Andptr[0] = Pe
				ctxt.Andptr = ctxt.Andptr[1:]

			case Pw: /* 64-bit escape */
				if p.Mode != 64 {
					ctxt.Diag("asmins: illegal 64: %v", p)
				}
				ctxt.Rexflag |= Pw

			case Pw8: /* 64-bit escape if z >= 8 */
				if z >= 8 {
					if p.Mode != 64 {
						ctxt.Diag("asmins: illegal 64: %v", p)
					}
					ctxt.Rexflag |= Pw
				}

			case Pb: /* botch */
				if p.Mode != 64 && (isbadbyte(&p.From) || isbadbyte(&p.To)) {
					goto bad
				}
				// NOTE(rsc): This is probably safe to do always,
				// but when enabled it chooses different encodings
				// than the old cmd/internal/obj/i386 code did,
				// which breaks our "same bits out" checks.
				// In particular, CMPB AX, $0 encodes as 80 f8 00
				// in the original obj/i386, and it would encode
				// (using a valid, shorter form) as 3c 00 if we enabled
				// the call to bytereg here.
				if p.Mode == 64 {
					bytereg(&p.From, &p.Ft)
					bytereg(&p.To, &p.Tt)
				}

			case P32: /* 32 bit but illegal if 64-bit mode */
				if p.Mode == 64 {
					ctxt.Diag("asmins: illegal in 64-bit mode: %v", p)
				}

			case Py: /* 64-bit only, no prefix */
				if p.Mode != 64 {
					ctxt.Diag("asmins: illegal in %d-bit mode: %v", p.Mode, p)
				}

			case Py1: /* 64-bit only if z < 1, no prefix */
				if z < 1 && p.Mode != 64 {
					ctxt.Diag("asmins: illegal in %d-bit mode: %v", p.Mode, p)
				}

			case Py3: /* 64-bit only if z < 3, no prefix */
				if z < 3 && p.Mode != 64 {
					ctxt.Diag("asmins: illegal in %d-bit mode: %v", p.Mode, p)
				}
			}

			if z >= len(o.op) {
				log.Fatalf("asmins bad table %v", p)
			}
			op = int(o.op[z])
			if op == 0x0f {
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				z++
				op = int(o.op[z])
			}

			switch yt.zcase {
			default:
				ctxt.Diag("asmins: unknown z %d %v", yt.zcase, p)
				return

			case Zpseudo:
				break

			case Zlit:
				for ; ; z++ {
					op = int(o.op[z])
					if op == 0 {
						break
					}
					ctxt.Andptr[0] = byte(op)
					ctxt.Andptr = ctxt.Andptr[1:]
				}

			case Zlitm_r:
				for ; ; z++ {
					op = int(o.op[z])
					if op == 0 {
						break
					}
					ctxt.Andptr[0] = byte(op)
					ctxt.Andptr = ctxt.Andptr[1:]
				}
				asmand(ctxt, p, &p.From, &p.To)

			case Zmb_r:
				bytereg(&p.From, &p.Ft)
				fallthrough

				/* fall through */
			case Zm_r:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]

				asmand(ctxt, p, &p.From, &p.To)

			case Zm2_r:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = byte(o.op[z+1])
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.From, &p.To)

			case Zm_r_xm:
				mediaop(ctxt, o, op, int(yt.zoffset), z)
				asmand(ctxt, p, &p.From, &p.To)

			case Zm_r_xm_vex:
				ctxt.Vexflag = 1
				vexprefix(ctxt, &p.To, &p.From, nil, o.prefix)
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.From, &p.To)

			case Zm_r_xm_nr:
				ctxt.Rexflag = 0
				mediaop(ctxt, o, op, int(yt.zoffset), z)
				asmand(ctxt, p, &p.From, &p.To)

			case Zm_r_i_xm:
				mediaop(ctxt, o, op, int(yt.zoffset), z)
				asmand(ctxt, p, &p.From, p.From3)
				ctxt.Andptr[0] = byte(p.To.Offset)
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zm_r_3d:
				ctxt.Andptr[0] = 0x0f
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = 0x0f
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.From, &p.To)
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zibm_r:
				for {
					tmp1 := z
					z++
					op = int(o.op[tmp1])
					if op == 0 {
						break
					}
					ctxt.Andptr[0] = byte(op)
					ctxt.Andptr = ctxt.Andptr[1:]
				}
				asmand(ctxt, p, p.From3, &p.To)
				ctxt.Andptr[0] = byte(p.From.Offset)
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zaut_r:
				ctxt.Andptr[0] = 0x8d
				ctxt.Andptr = ctxt.Andptr[1:] /* leal */
				if p.From.Type != obj.TYPE_ADDR {
					ctxt.Diag("asmins: Zaut sb type ADDR")
				}
				p.From.Type = obj.TYPE_MEM
				asmand(ctxt, p, &p.From, &p.To)
				p.From.Type = obj.TYPE_ADDR

			case Zm_o:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmando(ctxt, p, &p.From, int(o.op[z+1]))

			case Zr_m:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.To, &p.From)

			case Zr_m_xm_vex:
				ctxt.Vexflag = 1
				vexprefix(ctxt, &p.From, &p.To, nil, o.prefix)
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.To, &p.From)

			case Zr_r_r_vex:
				ctxt.Vexflag = 1
				vexprefix(ctxt, &p.To, &p.From, p.From3, o.prefix)
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.From, &p.To)

			case Zr_m_xm:
				mediaop(ctxt, o, op, int(yt.zoffset), z)
				asmand(ctxt, p, &p.To, &p.From)

			case Zr_m_xm_nr:
				ctxt.Rexflag = 0
				mediaop(ctxt, o, op, int(yt.zoffset), z)
				asmand(ctxt, p, &p.To, &p.From)

			case Zo_m:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmando(ctxt, p, &p.To, int(o.op[z+1]))

			case Zcallindreg:
				r = obj.Addrel(ctxt.Cursym)
				r.Off = int32(p.Pc)
				r.Type = obj.R_CALLIND
				r.Siz = 0
				fallthrough

			case Zo_m64:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmandsz(ctxt, p, &p.To, int(o.op[z+1]), 0, 1)

			case Zm_ibo:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmando(ctxt, p, &p.From, int(o.op[z+1]))
				ctxt.Andptr[0] = byte(vaddr(ctxt, p, &p.To, nil))
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zibo_m:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmando(ctxt, p, &p.To, int(o.op[z+1]))
				ctxt.Andptr[0] = byte(vaddr(ctxt, p, &p.From, nil))
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zibo_m_xm:
				z = mediaop(ctxt, o, op, int(yt.zoffset), z)
				asmando(ctxt, p, &p.To, int(o.op[z+1]))
				ctxt.Andptr[0] = byte(vaddr(ctxt, p, &p.From, nil))
				ctxt.Andptr = ctxt.Andptr[1:]

			case Z_ib, Zib_:
				if yt.zcase == Zib_ {
					a = &p.From
				} else {
					a = &p.To
				}
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				if p.As == AXABORT {
					ctxt.Andptr[0] = byte(o.op[z+1])
					ctxt.Andptr = ctxt.Andptr[1:]
				}
				ctxt.Andptr[0] = byte(vaddr(ctxt, p, a, nil))
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zib_rp:
				ctxt.Rexflag |= regrex[p.To.Reg] & (Rxb | 0x40)
				ctxt.Andptr[0] = byte(op + reg[p.To.Reg])
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = byte(vaddr(ctxt, p, &p.From, nil))
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zil_rp:
				ctxt.Rexflag |= regrex[p.To.Reg] & Rxb
				ctxt.Andptr[0] = byte(op + reg[p.To.Reg])
				ctxt.Andptr = ctxt.Andptr[1:]
				if o.prefix == Pe {
					v = vaddr(ctxt, p, &p.From, nil)
					ctxt.Andptr[0] = byte(v)
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = byte(v >> 8)
					ctxt.Andptr = ctxt.Andptr[1:]
				} else {
					relput4(ctxt, p, &p.From)
				}

			case Zo_iw:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				if p.From.Type != obj.TYPE_NONE {
					v = vaddr(ctxt, p, &p.From, nil)
					ctxt.Andptr[0] = byte(v)
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = byte(v >> 8)
					ctxt.Andptr = ctxt.Andptr[1:]
				}

			case Ziq_rp:
				v = vaddr(ctxt, p, &p.From, &rel)
				l = int(v >> 32)
				if l == 0 && rel.Siz != 8 {
					//p->mark |= 0100;
					//print("zero: %llux %v\n", v, p);
					ctxt.Rexflag &^= (0x40 | Rxw)

					ctxt.Rexflag |= regrex[p.To.Reg] & Rxb
					ctxt.Andptr[0] = byte(0xb8 + reg[p.To.Reg])
					ctxt.Andptr = ctxt.Andptr[1:]
					if rel.Type != 0 {
						r = obj.Addrel(ctxt.Cursym)
						*r = rel
						r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
					}

					put4(ctxt, int32(v))
				} else if l == -1 && uint64(v)&(uint64(1)<<31) != 0 { /* sign extend */

					//p->mark |= 0100;
					//print("sign: %llux %v\n", v, p);
					ctxt.Andptr[0] = 0xc7
					ctxt.Andptr = ctxt.Andptr[1:]

					asmando(ctxt, p, &p.To, 0)
					put4(ctxt, int32(v)) /* need all 8 */
				} else {
					//print("all: %llux %v\n", v, p);
					ctxt.Rexflag |= regrex[p.To.Reg] & Rxb

					ctxt.Andptr[0] = byte(op + reg[p.To.Reg])
					ctxt.Andptr = ctxt.Andptr[1:]
					if rel.Type != 0 {
						r = obj.Addrel(ctxt.Cursym)
						*r = rel
						r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
					}

					put8(ctxt, v)
				}

			case Zib_rr:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.To, &p.To)
				ctxt.Andptr[0] = byte(vaddr(ctxt, p, &p.From, nil))
				ctxt.Andptr = ctxt.Andptr[1:]

			case Z_il, Zil_:
				if yt.zcase == Zil_ {
					a = &p.From
				} else {
					a = &p.To
				}
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				if o.prefix == Pe {
					v = vaddr(ctxt, p, a, nil)
					ctxt.Andptr[0] = byte(v)
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = byte(v >> 8)
					ctxt.Andptr = ctxt.Andptr[1:]
				} else {
					relput4(ctxt, p, a)
				}

			case Zm_ilo, Zilo_m:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				if yt.zcase == Zilo_m {
					a = &p.From
					asmando(ctxt, p, &p.To, int(o.op[z+1]))
				} else {
					a = &p.To
					asmando(ctxt, p, &p.From, int(o.op[z+1]))
				}

				if o.prefix == Pe {
					v = vaddr(ctxt, p, a, nil)
					ctxt.Andptr[0] = byte(v)
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = byte(v >> 8)
					ctxt.Andptr = ctxt.Andptr[1:]
				} else {
					relput4(ctxt, p, a)
				}

			case Zil_rr:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.To, &p.To)
				if o.prefix == Pe {
					v = vaddr(ctxt, p, &p.From, nil)
					ctxt.Andptr[0] = byte(v)
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = byte(v >> 8)
					ctxt.Andptr = ctxt.Andptr[1:]
				} else {
					relput4(ctxt, p, &p.From)
				}

			case Z_rp:
				ctxt.Rexflag |= regrex[p.To.Reg] & (Rxb | 0x40)
				ctxt.Andptr[0] = byte(op + reg[p.To.Reg])
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zrp_:
				ctxt.Rexflag |= regrex[p.From.Reg] & (Rxb | 0x40)
				ctxt.Andptr[0] = byte(op + reg[p.From.Reg])
				ctxt.Andptr = ctxt.Andptr[1:]

			case Zclr:
				ctxt.Rexflag &^= Pw
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				asmand(ctxt, p, &p.To, &p.To)

			case Zcallcon, Zjmpcon:
				if yt.zcase == Zcallcon {
					ctxt.Andptr[0] = byte(op)
					ctxt.Andptr = ctxt.Andptr[1:]
				} else {
					ctxt.Andptr[0] = byte(o.op[z+1])
					ctxt.Andptr = ctxt.Andptr[1:]
				}
				r = obj.Addrel(ctxt.Cursym)
				r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
				r.Type = obj.R_PCREL
				r.Siz = 4
				r.Add = p.To.Offset
				put4(ctxt, 0)

			case Zcallind:
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = byte(o.op[z+1])
				ctxt.Andptr = ctxt.Andptr[1:]
				r = obj.Addrel(ctxt.Cursym)
				r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
				r.Type = obj.R_ADDR
				r.Siz = 4
				r.Add = p.To.Offset
				r.Sym = p.To.Sym
				put4(ctxt, 0)

			case Zcall, Zcallduff:
				if p.To.Sym == nil {
					ctxt.Diag("call without target")
					log.Fatalf("bad code")
				}

				if yt.zcase == Zcallduff && ctxt.Flag_dynlink {
					ctxt.Diag("directly calling duff when dynamically linking Go")
				}

				if obj.Framepointer_enabled != 0 && yt.zcase == Zcallduff && p.Mode == 64 {
					// Maintain BP around call, since duffcopy/duffzero can't do it
					// (the call jumps into the middle of the function).
					// This makes it possible to see call sites for duffcopy/duffzero in
					// BP-based profiling tools like Linux perf (which is the
					// whole point of obj.Framepointer_enabled).
					// MOVQ BP, -16(SP)
					// LEAQ -16(SP), BP
					copy(ctxt.Andptr, bpduff1)
					ctxt.Andptr = ctxt.Andptr[len(bpduff1):]
				}
				ctxt.Andptr[0] = byte(op)
				ctxt.Andptr = ctxt.Andptr[1:]
				r = obj.Addrel(ctxt.Cursym)
				r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
				r.Sym = p.To.Sym
				r.Add = p.To.Offset
				r.Type = obj.R_CALL
				r.Siz = 4
				put4(ctxt, 0)

				if obj.Framepointer_enabled != 0 && yt.zcase == Zcallduff && p.Mode == 64 {
					// Pop BP pushed above.
					// MOVQ 0(BP), BP
					copy(ctxt.Andptr, bpduff2)
					ctxt.Andptr = ctxt.Andptr[len(bpduff2):]
				}

			// TODO: jump across functions needs reloc
			case Zbr, Zjmp, Zloop:
				if p.As == AXBEGIN {
					ctxt.Andptr[0] = byte(op)
					ctxt.Andptr = ctxt.Andptr[1:]
				}
				if p.To.Sym != nil {
					if yt.zcase != Zjmp {
						ctxt.Diag("branch to ATEXT")
						log.Fatalf("bad code")
					}

					ctxt.Andptr[0] = byte(o.op[z+1])
					ctxt.Andptr = ctxt.Andptr[1:]
					r = obj.Addrel(ctxt.Cursym)
					r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
					r.Sym = p.To.Sym
					r.Type = obj.R_PCREL
					r.Siz = 4
					put4(ctxt, 0)
					break
				}

				// Assumes q is in this function.
				// TODO: Check in input, preserve in brchain.

				// Fill in backward jump now.
				q = p.Pcond

				if q == nil {
					ctxt.Diag("jmp/branch/loop without target")
					log.Fatalf("bad code")
				}

				if p.Back&1 != 0 {
					v = q.Pc - (p.Pc + 2)
					if v >= -128 && p.As != AXBEGIN {
						if p.As == AJCXZL {
							ctxt.Andptr[0] = 0x67
							ctxt.Andptr = ctxt.Andptr[1:]
						}
						ctxt.Andptr[0] = byte(op)
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = byte(v)
						ctxt.Andptr = ctxt.Andptr[1:]
					} else if yt.zcase == Zloop {
						ctxt.Diag("loop too far: %v", p)
					} else {
						v -= 5 - 2
						if p.As == AXBEGIN {
							v--
						}
						if yt.zcase == Zbr {
							ctxt.Andptr[0] = 0x0f
							ctxt.Andptr = ctxt.Andptr[1:]
							v--
						}

						ctxt.Andptr[0] = byte(o.op[z+1])
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = byte(v)
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = byte(v >> 8)
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = byte(v >> 16)
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = byte(v >> 24)
						ctxt.Andptr = ctxt.Andptr[1:]
					}

					break
				}

				// Annotate target; will fill in later.
				p.Forwd = q.Rel

				q.Rel = p
				if p.Back&2 != 0 && p.As != AXBEGIN { // short
					if p.As == AJCXZL {
						ctxt.Andptr[0] = 0x67
						ctxt.Andptr = ctxt.Andptr[1:]
					}
					ctxt.Andptr[0] = byte(op)
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = 0
					ctxt.Andptr = ctxt.Andptr[1:]
				} else if yt.zcase == Zloop {
					ctxt.Diag("loop too far: %v", p)
				} else {
					if yt.zcase == Zbr {
						ctxt.Andptr[0] = 0x0f
						ctxt.Andptr = ctxt.Andptr[1:]
					}
					ctxt.Andptr[0] = byte(o.op[z+1])
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = 0
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = 0
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = 0
					ctxt.Andptr = ctxt.Andptr[1:]
					ctxt.Andptr[0] = 0
					ctxt.Andptr = ctxt.Andptr[1:]
				}

				break

			/*
				v = q->pc - p->pc - 2;
				if((v >= -128 && v <= 127) || p->pc == -1 || q->pc == -1) {
					*ctxt->andptr++ = op;
					*ctxt->andptr++ = v;
				} else {
					v -= 5-2;
					if(yt.zcase == Zbr) {
						*ctxt->andptr++ = 0x0f;
						v--;
					}
					*ctxt->andptr++ = o->op[z+1];
					*ctxt->andptr++ = v;
					*ctxt->andptr++ = v>>8;
					*ctxt->andptr++ = v>>16;
					*ctxt->andptr++ = v>>24;
				}
			*/

			case Zbyte:
				v = vaddr(ctxt, p, &p.From, &rel)
				if rel.Siz != 0 {
					rel.Siz = uint8(op)
					r = obj.Addrel(ctxt.Cursym)
					*r = rel
					r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
				}

				ctxt.Andptr[0] = byte(v)
				ctxt.Andptr = ctxt.Andptr[1:]
				if op > 1 {
					ctxt.Andptr[0] = byte(v >> 8)
					ctxt.Andptr = ctxt.Andptr[1:]
					if op > 2 {
						ctxt.Andptr[0] = byte(v >> 16)
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = byte(v >> 24)
						ctxt.Andptr = ctxt.Andptr[1:]
						if op > 4 {
							ctxt.Andptr[0] = byte(v >> 32)
							ctxt.Andptr = ctxt.Andptr[1:]
							ctxt.Andptr[0] = byte(v >> 40)
							ctxt.Andptr = ctxt.Andptr[1:]
							ctxt.Andptr[0] = byte(v >> 48)
							ctxt.Andptr = ctxt.Andptr[1:]
							ctxt.Andptr[0] = byte(v >> 56)
							ctxt.Andptr = ctxt.Andptr[1:]
						}
					}
				}
			}

			return
		}
		z += int(yt.zoffset) + xo
	}
	for mo := ymovtab; mo[0].as != 0; mo = mo[1:] {
		var pp obj.Prog
		var t []byte
		if p.As == mo[0].as {
			if ycover[ft+int(mo[0].ft)] != 0 && ycover[f3t+int(mo[0].f3t)] != 0 && ycover[tt+int(mo[0].tt)] != 0 {
				t = mo[0].op[:]
				switch mo[0].code {
				default:
					ctxt.Diag("asmins: unknown mov %d %v", mo[0].code, p)

				case 0: /* lit */
					for z = 0; t[z] != E; z++ {
						ctxt.Andptr[0] = t[z]
						ctxt.Andptr = ctxt.Andptr[1:]
					}

				case 1: /* r,m */
					ctxt.Andptr[0] = t[0]
					ctxt.Andptr = ctxt.Andptr[1:]

					asmando(ctxt, p, &p.To, int(t[1]))

				case 2: /* m,r */
					ctxt.Andptr[0] = t[0]
					ctxt.Andptr = ctxt.Andptr[1:]

					asmando(ctxt, p, &p.From, int(t[1]))

				case 3: /* r,m - 2op */
					ctxt.Andptr[0] = t[0]
					ctxt.Andptr = ctxt.Andptr[1:]

					ctxt.Andptr[0] = t[1]
					ctxt.Andptr = ctxt.Andptr[1:]
					asmando(ctxt, p, &p.To, int(t[2]))
					ctxt.Rexflag |= regrex[p.From.Reg] & (Rxr | 0x40)

				case 4: /* m,r - 2op */
					ctxt.Andptr[0] = t[0]
					ctxt.Andptr = ctxt.Andptr[1:]

					ctxt.Andptr[0] = t[1]
					ctxt.Andptr = ctxt.Andptr[1:]
					asmando(ctxt, p, &p.From, int(t[2]))
					ctxt.Rexflag |= regrex[p.To.Reg] & (Rxr | 0x40)

				case 5: /* load full pointer, trash heap */
					if t[0] != 0 {
						ctxt.Andptr[0] = t[0]
						ctxt.Andptr = ctxt.Andptr[1:]
					}
					switch p.To.Index {
					default:
						goto bad

					case REG_DS:
						ctxt.Andptr[0] = 0xc5
						ctxt.Andptr = ctxt.Andptr[1:]

					case REG_SS:
						ctxt.Andptr[0] = 0x0f
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = 0xb2
						ctxt.Andptr = ctxt.Andptr[1:]

					case REG_ES:
						ctxt.Andptr[0] = 0xc4
						ctxt.Andptr = ctxt.Andptr[1:]

					case REG_FS:
						ctxt.Andptr[0] = 0x0f
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = 0xb4
						ctxt.Andptr = ctxt.Andptr[1:]

					case REG_GS:
						ctxt.Andptr[0] = 0x0f
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = 0xb5
						ctxt.Andptr = ctxt.Andptr[1:]
					}

					asmand(ctxt, p, &p.From, &p.To)

				case 6: /* double shift */
					if t[0] == Pw {
						if p.Mode != 64 {
							ctxt.Diag("asmins: illegal 64: %v", p)
						}
						ctxt.Rexflag |= Pw
						t = t[1:]
					} else if t[0] == Pe {
						ctxt.Andptr[0] = Pe
						ctxt.Andptr = ctxt.Andptr[1:]
						t = t[1:]
					}

					switch p.From.Type {
					default:
						goto bad

					case obj.TYPE_CONST:
						ctxt.Andptr[0] = 0x0f
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = t[0]
						ctxt.Andptr = ctxt.Andptr[1:]
						asmandsz(ctxt, p, &p.To, reg[p.From3.Reg], regrex[p.From3.Reg], 0)
						ctxt.Andptr[0] = byte(p.From.Offset)
						ctxt.Andptr = ctxt.Andptr[1:]

					case obj.TYPE_REG:
						switch p.From.Reg {
						default:
							goto bad

						case REG_CL, REG_CX:
							ctxt.Andptr[0] = 0x0f
							ctxt.Andptr = ctxt.Andptr[1:]
							ctxt.Andptr[0] = t[1]
							ctxt.Andptr = ctxt.Andptr[1:]
							asmandsz(ctxt, p, &p.To, reg[p.From3.Reg], regrex[p.From3.Reg], 0)
						}
					}

				// NOTE: The systems listed here are the ones that use the "TLS initial exec" model,
				// where you load the TLS base register into a register and then index off that
				// register to access the actual TLS variables. Systems that allow direct TLS access
				// are handled in prefixof above and should not be listed here.
				case 7: /* mov tls, r */
					if p.Mode == 64 && p.As != AMOVQ || p.Mode == 32 && p.As != AMOVL {
						ctxt.Diag("invalid load of TLS: %v", p)
					}

					if p.Mode == 32 {
						// NOTE: The systems listed here are the ones that use the "TLS initial exec" model,
						// where you load the TLS base register into a register and then index off that
						// register to access the actual TLS variables. Systems that allow direct TLS access
						// are handled in prefixof above and should not be listed here.
						switch ctxt.Headtype {
						default:
							log.Fatalf("unknown TLS base location for %s", obj.Headstr(ctxt.Headtype))

						case obj.Hlinux,
							obj.Hnacl:
							if ctxt.Flag_shared != 0 {
								// Note that this is not generating the same insns as the other cases.
								//     MOV TLS, R_to
								// becomes
								//     call __x86.get_pc_thunk.cx
								//     movl (gotpc + g@gotntpoff)(%ecx),$R_To
								// which is encoded as
								//     call __x86.get_pc_thunk.cx
								//     movq 0(%ecx), R_to
								// and R_CALL & R_TLS_IE relocs. This all assumes the only tls variable we access
								// is g, which we can't check here, but will when we assemble the second
								// instruction.
								ctxt.Andptr[0] = 0xe8
								ctxt.Andptr = ctxt.Andptr[1:]
								r = obj.Addrel(ctxt.Cursym)
								r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
								r.Type = obj.R_CALL
								r.Siz = 4
								r.Sym = obj.Linklookup(ctxt, "__x86.get_pc_thunk.cx", 0)
								put4(ctxt, 0)

								ctxt.Andptr[0] = 0x8B
								ctxt.Andptr = ctxt.Andptr[1:]
								ctxt.Andptr[0] = byte(2<<6 | reg[REG_CX] | (reg[p.To.Reg] << 3))
								ctxt.Andptr = ctxt.Andptr[1:]
								r = obj.Addrel(ctxt.Cursym)
								r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
								r.Type = obj.R_TLS_IE
								r.Siz = 4
								r.Add = 2
								put4(ctxt, 0)
							} else {
								// ELF TLS base is 0(GS).
								pp.From = p.From

								pp.From.Type = obj.TYPE_MEM
								pp.From.Reg = REG_GS
								pp.From.Offset = 0
								pp.From.Index = REG_NONE
								pp.From.Scale = 0
								ctxt.Andptr[0] = 0x65
								ctxt.Andptr = ctxt.Andptr[1:] // GS
								ctxt.Andptr[0] = 0x8B
								ctxt.Andptr = ctxt.Andptr[1:]
								asmand(ctxt, p, &pp.From, &p.To)
							}
						case obj.Hplan9:
							if ctxt.Plan9privates == nil {
								ctxt.Plan9privates = obj.Linklookup(ctxt, "_privates", 0)
							}
							pp.From = obj.Addr{}
							pp.From.Type = obj.TYPE_MEM
							pp.From.Name = obj.NAME_EXTERN
							pp.From.Sym = ctxt.Plan9privates
							pp.From.Offset = 0
							pp.From.Index = REG_NONE
							ctxt.Andptr[0] = 0x8B
							ctxt.Andptr = ctxt.Andptr[1:]
							asmand(ctxt, p, &pp.From, &p.To)

						case obj.Hwindows:
							// Windows TLS base is always 0x14(FS).
							pp.From = p.From

							pp.From.Type = obj.TYPE_MEM
							pp.From.Reg = REG_FS
							pp.From.Offset = 0x14
							pp.From.Index = REG_NONE
							pp.From.Scale = 0
							ctxt.Andptr[0] = 0x64
							ctxt.Andptr = ctxt.Andptr[1:] // FS
							ctxt.Andptr[0] = 0x8B
							ctxt.Andptr = ctxt.Andptr[1:]
							asmand(ctxt, p, &pp.From, &p.To)
						}
						break
					}

					switch ctxt.Headtype {
					default:
						log.Fatalf("unknown TLS base location for %s", obj.Headstr(ctxt.Headtype))

					case obj.Hlinux:
						if ctxt.Flag_shared == 0 {
							log.Fatalf("unknown TLS base location for linux without -shared")
						}
						// Note that this is not generating the same insn as the other cases.
						//     MOV TLS, R_to
						// becomes
						//     movq g@gottpoff(%rip), R_to
						// which is encoded as
						//     movq 0(%rip), R_to
						// and a R_TLS_IE reloc. This all assumes the only tls variable we access
						// is g, which we can't check here, but will when we assemble the second
						// instruction.
						ctxt.Rexflag = Pw | (regrex[p.To.Reg] & Rxr)

						ctxt.Andptr[0] = 0x8B
						ctxt.Andptr = ctxt.Andptr[1:]
						ctxt.Andptr[0] = byte(0x05 | (reg[p.To.Reg] << 3))
						ctxt.Andptr = ctxt.Andptr[1:]
						r = obj.Addrel(ctxt.Cursym)
						r.Off = int32(p.Pc + int64(-cap(ctxt.Andptr)+cap(ctxt.And[:])))
						r.Type = obj.R_TLS_IE
						r.Siz = 4
						r.Add = -4
						put4(ctxt, 0)

					case obj.Hplan9:
						if ctxt.Plan9privates == nil {
							ctxt.Plan9privates = obj.Linklookup(ctxt, "_privates", 0)
						}
						pp.From = obj.Addr{}
						pp.From.Type = obj.TYPE_MEM
						pp.From.Name = obj.NAME_EXTERN
						pp.From.Sym = ctxt.Plan9privates
						pp.From.Offset = 0
						pp.From.Index = REG_NONE
						ctxt.Rexflag |= Pw
						ctxt.Andptr[0] = 0x8B
						ctxt.Andptr = ctxt.Andptr[1:]
						asmand(ctxt, p, &pp.From, &p.To)

					case obj.Hsolaris: // TODO(rsc): Delete Hsolaris from list. Should not use this code. See progedit in obj6.c.
						// TLS base is 0(FS).
						pp.From = p.From

						pp.From.Type = obj.TYPE_MEM
						pp.From.Name = obj.NAME_NONE
						pp.From.Reg = REG_NONE
						pp.From.Offset = 0
						pp.From.Index = REG_NONE
						pp.From.Scale = 0
						ctxt.Rexflag |= Pw
						ctxt.Andptr[0] = 0x64
						ctxt.Andptr = ctxt.Andptr[1:] // FS
						ctxt.Andptr[0] = 0x8B
						ctxt.Andptr = ctxt.Andptr[1:]
						asmand(ctxt, p, &pp.From, &p.To)

					case obj.Hwindows:
						// Windows TLS base is always 0x28(GS).
						pp.From = p.From

						pp.From.Type = obj.TYPE_MEM
						pp.From.Name = obj.NAME_NONE
						pp.From.Reg = REG_GS
						pp.From.Offset = 0x28
						pp.From.Index = REG_NONE
						pp.From.Scale = 0
						ctxt.Rexflag |= Pw
						ctxt.Andptr[0] = 0x65
						ctxt.Andptr = ctxt.Andptr[1:] // GS
						ctxt.Andptr[0] = 0x8B
						ctxt.Andptr = ctxt.Andptr[1:]
						asmand(ctxt, p, &pp.From, &p.To)
					}
				}
				return
			}
		}
	}
	goto bad

bad:
	if p.Mode != 64 {
		/*
		 * here, the assembly has failed.
		 * if its a byte instruction that has
		 * unaddressable registers, try to
		 * exchange registers and reissue the
		 * instruction with the operands renamed.
		 */
		pp := *p

		unbytereg(&pp.From, &pp.Ft)
		unbytereg(&pp.To, &pp.Tt)

		z := int(p.From.Reg)
		if p.From.Type == obj.TYPE_REG && z >= REG_BP && z <= REG_DI {
			// TODO(rsc): Use this code for x86-64 too. It has bug fixes not present in the amd64 code base.
			// For now, different to keep bit-for-bit compatibility.
			if p.Mode == 32 {
				breg := byteswapreg(ctxt, &p.To)
				if breg != REG_AX {
					ctxt.Andptr[0] = 0x87
					ctxt.Andptr = ctxt.Andptr[1:] /* xchg lhs,bx */
					asmando(ctxt, p, &p.From, reg[breg])
					subreg(&pp, z, breg)
					doasm(ctxt, &pp)
					ctxt.Andptr[0] = 0x87
					ctxt.Andptr = ctxt.Andptr[1:] /* xchg lhs,bx */
					asmando(ctxt, p, &p.From, reg[breg])
				} else {
					ctxt.Andptr[0] = byte(0x90 + reg[z])
					ctxt.Andptr = ctxt.Andptr[1:] /* xchg lsh,ax */
					subreg(&pp, z, REG_AX)
					doasm(ctxt, &pp)
					ctxt.Andptr[0] = byte(0x90 + reg[z])
					ctxt.Andptr = ctxt.Andptr[1:] /* xchg lsh,ax */
				}
				return
			}

			if isax(&p.To) || p.To.Type == obj.TYPE_NONE {
				// We certainly don't want to exchange
				// with AX if the op is MUL or DIV.
				ctxt.Andptr[0] = 0x87
				ctxt.Andptr = ctxt.Andptr[1:] /* xchg lhs,bx */
				asmando(ctxt, p, &p.From, reg[REG_BX])
				subreg(&pp, z, REG_BX)
				doasm(ctxt, &pp)
				ctxt.Andptr[0] = 0x87
				ctxt.Andptr = ctxt.Andptr[1:] /* xchg lhs,bx */
				asmando(ctxt, p, &p.From, reg[REG_BX])
			} else {
				ctxt.Andptr[0] = byte(0x90 + reg[z])
				ctxt.Andptr = ctxt.Andptr[1:] /* xchg lsh,ax */
				subreg(&pp, z, REG_AX)
				doasm(ctxt, &pp)
				ctxt.Andptr[0] = byte(0x90 + reg[z])
				ctxt.Andptr = ctxt.Andptr[1:] /* xchg lsh,ax */
			}
			return
		}

		z = int(p.To.Reg)
		if p.To.Type == obj.TYPE_REG && z >= REG_BP && z <= REG_DI {
			// TODO(rsc): Use this code for x86-64 too. It has bug fixes not present in the amd64 code base.
			// For now, different to keep bit-for-bit compatibility.
			if p.Mode == 32 {
				breg := byteswapreg(ctxt, &p.From)
				if breg != REG_AX {
					ctxt.Andptr[0] = 0x87
					ctxt.Andptr = ctxt.Andptr[1:] /* xchg rhs,bx */
					asmando(ctxt, p, &p.To, reg[breg])
					subreg(&pp, z, breg)
					doasm(ctxt, &pp)
					ctxt.Andptr[0] = 0x87
					ctxt.Andptr = ctxt.Andptr[1:] /* xchg rhs,bx */
					asmando(ctxt, p, &p.To, reg[breg])
				} else {
					ctxt.Andptr[0] = byte(0x90 + reg[z])
					ctxt.Andptr = ctxt.Andptr[1:] /* xchg rsh,ax */
					subreg(&pp, z, REG_AX)
					doasm(ctxt, &pp)
					ctxt.Andptr[0] = byte(0x90 + reg[z])
					ctxt.Andptr = ctxt.Andptr[1:] /* xchg rsh,ax */
				}
				return
			}

			if isax(&p.From) {
				ctxt.Andptr[0] = 0x87
				ctxt.Andptr = ctxt.Andptr[1:] /* xchg rhs,bx */
				asmando(ctxt, p, &p.To, reg[REG_BX])
				subreg(&pp, z, REG_BX)
				doasm(ctxt, &pp)
				ctxt.Andptr[0] = 0x87
				ctxt.Andptr = ctxt.Andptr[1:] /* xchg rhs,bx */
				asmando(ctxt, p, &p.To, reg[REG_BX])
			} else {
				ctxt.Andptr[0] = byte(0x90 + reg[z])
				ctxt.Andptr = ctxt.Andptr[1:] /* xchg rsh,ax */
				subreg(&pp, z, REG_AX)
				doasm(ctxt, &pp)
				ctxt.Andptr[0] = byte(0x90 + reg[z])
				ctxt.Andptr = ctxt.Andptr[1:] /* xchg rsh,ax */
			}
			return
		}
	}

	ctxt.Diag("doasm: notfound ft=%d tt=%d %v %d %d", p.Ft, p.Tt, p, oclass(ctxt, p, &p.From), oclass(ctxt, p, &p.To))
	return
}

// byteswapreg returns a byte-addressable register (AX, BX, CX, DX)
// which is not referenced in a.
// If a is empty, it returns BX to account for MULB-like instructions
// that might use DX and AX.
func byteswapreg(ctxt *obj.Link, a *obj.Addr) int {
	cand := 1
	canc := cand
	canb := canc
	cana := canb

	if a.Type == obj.TYPE_NONE {
		cand = 0
		cana = cand
	}

	if a.Type == obj.TYPE_REG || ((a.Type == obj.TYPE_MEM || a.Type == obj.TYPE_ADDR) && a.Name == obj.NAME_NONE) {
		switch a.Reg {
		case REG_NONE:
			cand = 0
			cana = cand

		case REG_AX, REG_AL, REG_AH:
			cana = 0

		case REG_BX, REG_BL, REG_BH:
			canb = 0

		case REG_CX, REG_CL, REG_CH:
			canc = 0

		case REG_DX, REG_DL, REG_DH:
			cand = 0
		}
	}

	if a.Type == obj.TYPE_MEM || a.Type == obj.TYPE_ADDR {
		switch a.Index {
		case REG_AX:
			cana = 0

		case REG_BX:
			canb = 0

		case REG_CX:
			canc = 0

		case REG_DX:
			cand = 0
		}
	}

	if cana != 0 {
		return REG_AX
	}
	if canb != 0 {
		return REG_BX
	}
	if canc != 0 {
		return REG_CX
	}
	if cand != 0 {
		return REG_DX
	}

	ctxt.Diag("impossible byte register")
	log.Fatalf("bad code")
	return 0
}

func isbadbyte(a *obj.Addr) bool {
	return a.Type == obj.TYPE_REG && (REG_BP <= a.Reg && a.Reg <= REG_DI || REG_BPB <= a.Reg && a.Reg <= REG_DIB)
}

var naclret = []uint8{
	0x5e, // POPL SI
	// 0x8b, 0x7d, 0x00, // MOVL (BP), DI - catch return to invalid address, for debugging
	0x83,
	0xe6,
	0xe0, // ANDL $~31, SI
	0x4c,
	0x01,
	0xfe, // ADDQ R15, SI
	0xff,
	0xe6, // JMP SI
}

var naclret8 = []uint8{
	0x5d, // POPL BP
	// 0x8b, 0x7d, 0x00, // MOVL (BP), DI - catch return to invalid address, for debugging
	0x83,
	0xe5,
	0xe0, // ANDL $~31, BP
	0xff,
	0xe5, // JMP BP
}

var naclspfix = []uint8{0x4c, 0x01, 0xfc} // ADDQ R15, SP

var naclbpfix = []uint8{0x4c, 0x01, 0xfd} // ADDQ R15, BP

var naclmovs = []uint8{
	0x89,
	0xf6, // MOVL SI, SI
	0x49,
	0x8d,
	0x34,
	0x37, // LEAQ (R15)(SI*1), SI
	0x89,
	0xff, // MOVL DI, DI
	0x49,
	0x8d,
	0x3c,
	0x3f, // LEAQ (R15)(DI*1), DI
}

var naclstos = []uint8{
	0x89,
	0xff, // MOVL DI, DI
	0x49,
	0x8d,
	0x3c,
	0x3f, // LEAQ (R15)(DI*1), DI
}

func nacltrunc(ctxt *obj.Link, reg int) {
	if reg >= REG_R8 {
		ctxt.Andptr[0] = 0x45
		ctxt.Andptr = ctxt.Andptr[1:]
	}
	reg = (reg - REG_AX) & 7
	ctxt.Andptr[0] = 0x89
	ctxt.Andptr = ctxt.Andptr[1:]
	ctxt.Andptr[0] = byte(3<<6 | reg<<3 | reg)
	ctxt.Andptr = ctxt.Andptr[1:]
}

func asmins(ctxt *obj.Link, p *obj.Prog) {
	ctxt.Andptr = ctxt.And[:]
	ctxt.Asmode = int(p.Mode)

	if p.As == obj.AUSEFIELD {
		r := obj.Addrel(ctxt.Cursym)
		r.Off = 0
		r.Siz = 0
		r.Sym = p.From.Sym
		r.Type = obj.R_USEFIELD
		return
	}

	if ctxt.Headtype == obj.Hnacl && p.Mode == 32 {
		switch p.As {
		case obj.ARET:
			copy(ctxt.Andptr, naclret8)
			ctxt.Andptr = ctxt.Andptr[len(naclret8):]
			return

		case obj.ACALL,
			obj.AJMP:
			if p.To.Type == obj.TYPE_REG && REG_AX <= p.To.Reg && p.To.Reg <= REG_DI {
				ctxt.Andptr[0] = 0x83
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = byte(0xe0 | (p.To.Reg - REG_AX))
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = 0xe0
				ctxt.Andptr = ctxt.Andptr[1:]
			}

		case AINT:
			ctxt.Andptr[0] = 0xf4
			ctxt.Andptr = ctxt.Andptr[1:]
			return
		}
	}

	if ctxt.Headtype == obj.Hnacl && p.Mode == 64 {
		if p.As == AREP {
			ctxt.Rep++
			return
		}

		if p.As == AREPN {
			ctxt.Repn++
			return
		}

		if p.As == ALOCK {
			ctxt.Lock++
			return
		}

		if p.As != ALEAQ && p.As != ALEAL {
			if p.From.Index != obj.TYPE_NONE && p.From.Scale > 0 {
				nacltrunc(ctxt, int(p.From.Index))
			}
			if p.To.Index != obj.TYPE_NONE && p.To.Scale > 0 {
				nacltrunc(ctxt, int(p.To.Index))
			}
		}

		switch p.As {
		case obj.ARET:
			copy(ctxt.Andptr, naclret)
			ctxt.Andptr = ctxt.Andptr[len(naclret):]
			return

		case obj.ACALL,
			obj.AJMP:
			if p.To.Type == obj.TYPE_REG && REG_AX <= p.To.Reg && p.To.Reg <= REG_DI {
				// ANDL $~31, reg
				ctxt.Andptr[0] = 0x83
				ctxt.Andptr = ctxt.Andptr[1:]

				ctxt.Andptr[0] = byte(0xe0 | (p.To.Reg - REG_AX))
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = 0xe0
				ctxt.Andptr = ctxt.Andptr[1:]

				// ADDQ R15, reg
				ctxt.Andptr[0] = 0x4c
				ctxt.Andptr = ctxt.Andptr[1:]

				ctxt.Andptr[0] = 0x01
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = byte(0xf8 | (p.To.Reg - REG_AX))
				ctxt.Andptr = ctxt.Andptr[1:]
			}

			if p.To.Type == obj.TYPE_REG && REG_R8 <= p.To.Reg && p.To.Reg <= REG_R15 {
				// ANDL $~31, reg
				ctxt.Andptr[0] = 0x41
				ctxt.Andptr = ctxt.Andptr[1:]

				ctxt.Andptr[0] = 0x83
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = byte(0xe0 | (p.To.Reg - REG_R8))
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = 0xe0
				ctxt.Andptr = ctxt.Andptr[1:]

				// ADDQ R15, reg
				ctxt.Andptr[0] = 0x4d
				ctxt.Andptr = ctxt.Andptr[1:]

				ctxt.Andptr[0] = 0x01
				ctxt.Andptr = ctxt.Andptr[1:]
				ctxt.Andptr[0] = byte(0xf8 | (p.To.Reg - REG_R8))
				ctxt.Andptr = ctxt.Andptr[1:]
			}

		case AINT:
			ctxt.Andptr[0] = 0xf4
			ctxt.Andptr = ctxt.Andptr[1:]
			return

		case ASCASB,
			ASCASW,
			ASCASL,
			ASCASQ,
			ASTOSB,
			ASTOSW,
			ASTOSL,
			ASTOSQ:
			copy(ctxt.Andptr, naclstos)
			ctxt.Andptr = ctxt.Andptr[len(naclstos):]

		case AMOVSB, AMOVSW, AMOVSL, AMOVSQ:
			copy(ctxt.Andptr, naclmovs)
			ctxt.Andptr = ctxt.Andptr[len(naclmovs):]
		}

		if ctxt.Rep != 0 {
			ctxt.Andptr[0] = 0xf3
			ctxt.Andptr = ctxt.Andptr[1:]
			ctxt.Rep = 0
		}

		if ctxt.Repn != 0 {
			ctxt.Andptr[0] = 0xf2
			ctxt.Andptr = ctxt.Andptr[1:]
			ctxt.Repn = 0
		}

		if ctxt.Lock != 0 {
			ctxt.Andptr[0] = 0xf0
			ctxt.Andptr = ctxt.Andptr[1:]
			ctxt.Lock = 0
		}
	}

	ctxt.Rexflag = 0
	ctxt.Vexflag = 0
	and0 := ctxt.Andptr
	ctxt.Asmode = int(p.Mode)
	doasm(ctxt, p)
	if ctxt.Rexflag != 0 && ctxt.Vexflag == 0 {
		/*
		 * as befits the whole approach of the architecture,
		 * the rex prefix must appear before the first opcode byte
		 * (and thus after any 66/67/f2/f3/26/2e/3e prefix bytes, but
		 * before the 0f opcode escape!), or it might be ignored.
		 * note that the handbook often misleadingly shows 66/f2/f3 in `opcode'.
		 */
		if p.Mode != 64 {
			ctxt.Diag("asmins: illegal in mode %d: %v (%d %d)", p.Mode, p, p.Ft, p.Tt)
		}
		n := -cap(ctxt.Andptr) + cap(and0)
		var c int
		var np int
		for np = 0; np < n; np++ {
			c = int(and0[np])
			if c != 0xf2 && c != 0xf3 && (c < 0x64 || c > 0x67) && c != 0x2e && c != 0x3e && c != 0x26 {
				break
			}
		}

		copy(and0[np+1:], and0[np:n])
		and0[np] = byte(0x40 | ctxt.Rexflag)
		ctxt.Andptr = ctxt.Andptr[1:]
	}

	n := -cap(ctxt.Andptr) + cap(ctxt.And[:])
	var r *obj.Reloc
	for i := len(ctxt.Cursym.R) - 1; i >= 0; i-- {
		r = &ctxt.Cursym.R[i:][0]
		if int64(r.Off) < p.Pc {
			break
		}
		if ctxt.Rexflag != 0 {
			r.Off++
		}
		if r.Type == obj.R_PCREL {
			if p.Mode == 64 || p.As == obj.AJMP || p.As == obj.ACALL {
				// PC-relative addressing is relative to the end of the instruction,
				// but the relocations applied by the linker are relative to the end
				// of the relocation. Because immediate instruction
				// arguments can follow the PC-relative memory reference in the
				// instruction encoding, the two may not coincide. In this case,
				// adjust addend so that linker can keep relocating relative to the
				// end of the relocation.
				r.Add -= p.Pc + int64(n) - (int64(r.Off) + int64(r.Siz))
			} else if p.Mode == 32 {
				// On 386 PC-relative addressing (for non-call/jmp instructions)
				// assumes that the previous instruction loaded the PC of the end
				// of that instruction into CX, so the adjustment is relative to
				// that.
				r.Add += int64(r.Off) - p.Pc + int64(r.Siz)
			}
		}
		if r.Type == obj.R_GOTPCREL && p.Mode == 32 {
			// On 386, R_GOTPCREL makes the same assumptions as R_PCREL.
			r.Add += int64(r.Off) - p.Pc + int64(r.Siz)
		}

	}

	if p.Mode == 64 && ctxt.Headtype == obj.Hnacl && p.As != ACMPL && p.As != ACMPQ && p.To.Type == obj.TYPE_REG {
		switch p.To.Reg {
		case REG_SP:
			copy(ctxt.Andptr, naclspfix)
			ctxt.Andptr = ctxt.Andptr[len(naclspfix):]

		case REG_BP:
			copy(ctxt.Andptr, naclbpfix)
			ctxt.Andptr = ctxt.Andptr[len(naclbpfix):]
		}
	}
}