cmd/internal/obj: switch to one global Aconv

Aconv is the pretty-printer for instruction opcodes like AMOVQ.
There was one for each architecture.
Make the space of A names have a different region for each architecture,
much as we did for the registers, so a single global Aconv function can
do the work. Each architecture registers its region as a slice of names
at a given offset.

The global names like CALL and JMP are now defined only once.

The A values are used for indexing tables, so make it easy to do the
indexing by making the offset maskable.

Remove a bunch of now-duplicated architecture-specific code.

Change-Id: Ib15647b7145a1c089e21e36543691a19e146b60e
Reviewed-on: https://go-review.googlesource.com/6620
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

19 files changed, 521 insertions, 600 deletions

diff --git a/src/cmd/internal/obj/arm/5.out.go b/src/cmd/internal/obj/arm/5.out.go
index d4b0170e58..91e96874f0 100644
--- a/src/cmd/internal/obj/arm/5.out.go
+++ b/src/cmd/internal/obj/arm/5.out.go
@@ -145,7 +145,7 @@ const (
 )
 
 const (
-	AAND = obj.A_ARCHSPECIFIC + iota
+	AAND = obj.ABaseARM + obj.A_ARCHSPECIFIC + iota
 	AEOR
 	ASUB
 	ARSB
diff --git a/src/cmd/internal/obj/arm/anames5.go b/src/cmd/internal/obj/arm/anames5.go
index f00cf17760..9f50df3239 100644
--- a/src/cmd/internal/obj/arm/anames5.go
+++ b/src/cmd/internal/obj/arm/anames5.go
@@ -1,26 +1,9 @@
 package arm
 
+import "cmd/internal/obj"
+
 var Anames = []string{
-	"XXX",
-	"CALL",
-	"CHECKNIL",
-	"DATA",
-	"DUFFCOPY",
-	"DUFFZERO",
-	"END",
-	"FUNCDATA",
-	"GLOBL",
-	"JMP",
-	"NOP",
-	"PCDATA",
-	"RET",
-	"TEXT",
-	"TYPE",
-	"UNDEF",
-	"USEFIELD",
-	"VARDEF",
-	"VARKILL",
-	"AND",
+	obj.A_ARCHSPECIFIC: "AND",
 	"EOR",
 	"SUB",
 	"RSB",
diff --git a/src/cmd/internal/obj/arm/asm5.go b/src/cmd/internal/obj/arm/asm5.go
index 064cbe26f1..10cca25172 100644
--- a/src/cmd/internal/obj/arm/asm5.go
+++ b/src/cmd/internal/obj/arm/asm5.go
@@ -39,7 +39,7 @@ import (
 )
 
 type Optab struct {
-	as       uint8
+	as       uint16
 	a1       uint8
 	a2       int8
 	a3       uint8
@@ -268,7 +268,7 @@ var pool struct {
 	extra uint32
 }
 
-var oprange [ALAST]Oprang
+var oprange [ALAST & obj.AMask]Oprang
 
 var xcmp [C_GOK + 1][C_GOK + 1]uint8
 
@@ -580,7 +580,7 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
 		return
 	}
 
-	if oprange[AAND].start == nil {
+	if oprange[AAND&obj.AMask].start == nil {
 		buildop(ctxt)
 	}
 
@@ -1207,14 +1207,14 @@ func oplook(ctxt *obj.Link, p *obj.Prog) *Optab {
 	if p.Reg != 0 {
 		a2 = C_REG
 	}
-	r := int(p.As)
+	r := p.As & obj.AMask
 	o := oprange[r].start
 	if o == nil {
 		o = oprange[r].stop /* just generate an error */
 	}
 
 	if false { /*debug['O']*/
-		fmt.Printf("oplook %v %v %v %v\n", Aconv(int(p.As)), DRconv(a1), DRconv(a2), DRconv(a3))
+		fmt.Printf("oplook %v %v %v %v\n", obj.Aconv(int(p.As)), DRconv(a1), DRconv(a2), DRconv(a3))
 		fmt.Printf("\t\t%d %d\n", p.From.Type, p.To.Type)
 	}
 
@@ -1335,6 +1335,10 @@ func (x ocmp) Less(i, j int) bool {
 	return false
 }
 
+func opset(a, b0 uint16) {
+	oprange[a&obj.AMask] = oprange[b0]
+}
+
 func buildop(ctxt *obj.Link) {
 	var n int
 
@@ -1356,67 +1360,66 @@ func buildop(ctxt *obj.Link) {
 	}
 
 	sort.Sort(ocmp(optab[:n]))
-	var r int
 	for i := 0; i < n; i++ {
-		r = int(optab[i].as)
-		oprange[r].start = optab[i:]
-		for int(optab[i].as) == r {
+		r0 := optab[i].as & obj.AMask
+		oprange[r0].start = optab[i:]
+		for optab[i].as&obj.AMask == r0 {
 			i++
 		}
-		oprange[r].stop = optab[i:]
+		oprange[r0].stop = optab[i:]
 		i--
 
-		switch r {
+		switch r0 {
 		default:
-			ctxt.Diag("unknown op in build: %v", Aconv(r))
+			ctxt.Diag("unknown op in build: %v", obj.Aconv(int(optab[i].as)))
 			log.Fatalf("bad code")
 
 		case AADD:
-			oprange[AAND] = oprange[r]
-			oprange[AEOR] = oprange[r]
-			oprange[ASUB] = oprange[r]
-			oprange[ARSB] = oprange[r]
-			oprange[AADC] = oprange[r]
-			oprange[ASBC] = oprange[r]
-			oprange[ARSC] = oprange[r]
-			oprange[AORR] = oprange[r]
-			oprange[ABIC] = oprange[r]
+			opset(AAND, r0)
+			opset(AEOR, r0)
+			opset(ASUB, r0)
+			opset(ARSB, r0)
+			opset(AADC, r0)
+			opset(ASBC, r0)
+			opset(ARSC, r0)
+			opset(AORR, r0)
+			opset(ABIC, r0)
 
 		case ACMP:
-			oprange[ATEQ] = oprange[r]
-			oprange[ACMN] = oprange[r]
+			opset(ATEQ, r0)
+			opset(ACMN, r0)
 
 		case AMVN:
 			break
 
 		case ABEQ:
-			oprange[ABNE] = oprange[r]
-			oprange[ABCS] = oprange[r]
-			oprange[ABHS] = oprange[r]
-			oprange[ABCC] = oprange[r]
-			oprange[ABLO] = oprange[r]
-			oprange[ABMI] = oprange[r]
-			oprange[ABPL] = oprange[r]
-			oprange[ABVS] = oprange[r]
-			oprange[ABVC] = oprange[r]
-			oprange[ABHI] = oprange[r]
-			oprange[ABLS] = oprange[r]
-			oprange[ABGE] = oprange[r]
-			oprange[ABLT] = oprange[r]
-			oprange[ABGT] = oprange[r]
-			oprange[ABLE] = oprange[r]
+			opset(ABNE, r0)
+			opset(ABCS, r0)
+			opset(ABHS, r0)
+			opset(ABCC, r0)
+			opset(ABLO, r0)
+			opset(ABMI, r0)
+			opset(ABPL, r0)
+			opset(ABVS, r0)
+			opset(ABVC, r0)
+			opset(ABHI, r0)
+			opset(ABLS, r0)
+			opset(ABGE, r0)
+			opset(ABLT, r0)
+			opset(ABGT, r0)
+			opset(ABLE, r0)
 
 		case ASLL:
-			oprange[ASRL] = oprange[r]
-			oprange[ASRA] = oprange[r]
+			opset(ASRL, r0)
+			opset(ASRA, r0)
 
 		case AMUL:
-			oprange[AMULU] = oprange[r]
+			opset(AMULU, r0)
 
 		case ADIV:
-			oprange[AMOD] = oprange[r]
-			oprange[AMODU] = oprange[r]
-			oprange[ADIVU] = oprange[r]
+			opset(AMOD, r0)
+			opset(AMODU, r0)
+			opset(ADIVU, r0)
 
 		case AMOVW,
 			AMOVB,
@@ -1428,7 +1431,7 @@ func buildop(ctxt *obj.Link) {
 			break
 
 		case ASWPW:
-			oprange[ASWPBU] = oprange[r]
+			opset(ASWPBU, r0)
 
 		case AB,
 			ABL,
@@ -1448,42 +1451,42 @@ func buildop(ctxt *obj.Link) {
 			break
 
 		case AADDF:
-			oprange[AADDD] = oprange[r]
-			oprange[ASUBF] = oprange[r]
-			oprange[ASUBD] = oprange[r]
-			oprange[AMULF] = oprange[r]
-			oprange[AMULD] = oprange[r]
-			oprange[ADIVF] = oprange[r]
-			oprange[ADIVD] = oprange[r]
-			oprange[ASQRTF] = oprange[r]
-			oprange[ASQRTD] = oprange[r]
-			oprange[AMOVFD] = oprange[r]
-			oprange[AMOVDF] = oprange[r]
-			oprange[AABSF] = oprange[r]
-			oprange[AABSD] = oprange[r]
+			opset(AADDD, r0)
+			opset(ASUBF, r0)
+			opset(ASUBD, r0)
+			opset(AMULF, r0)
+			opset(AMULD, r0)
+			opset(ADIVF, r0)
+			opset(ADIVD, r0)
+			opset(ASQRTF, r0)
+			opset(ASQRTD, r0)
+			opset(AMOVFD, r0)
+			opset(AMOVDF, r0)
+			opset(AABSF, r0)
+			opset(AABSD, r0)
 
 		case ACMPF:
-			oprange[ACMPD] = oprange[r]
+			opset(ACMPD, r0)
 
 		case AMOVF:
-			oprange[AMOVD] = oprange[r]
+			opset(AMOVD, r0)
 
 		case AMOVFW:
-			oprange[AMOVDW] = oprange[r]
+			opset(AMOVDW, r0)
 
 		case AMOVWF:
-			oprange[AMOVWD] = oprange[r]
+			opset(AMOVWD, r0)
 
 		case AMULL:
-			oprange[AMULAL] = oprange[r]
-			oprange[AMULLU] = oprange[r]
-			oprange[AMULALU] = oprange[r]
+			opset(AMULAL, r0)
+			opset(AMULLU, r0)
+			opset(AMULALU, r0)
 
 		case AMULWT:
-			oprange[AMULWB] = oprange[r]
+			opset(AMULWB, r0)
 
 		case AMULAWT:
-			oprange[AMULAWB] = oprange[r]
+			opset(AMULAWB, r0)
 
 		case AMULA,
 			ALDREX,
@@ -2660,7 +2663,7 @@ func opbra(ctxt *obj.Link, a int, sc int) uint32 {
 		return 0xe<<28 | 0x5<<25
 	}
 
-	ctxt.Diag("bad bra %v", Aconv(a))
+	ctxt.Diag("bad bra %v", obj.Aconv(a))
 	prasm(ctxt.Curp)
 	return 0
 }
@@ -2780,7 +2783,7 @@ func ofsr(ctxt *obj.Link, a int, r int, v int32, b int, sc int, p *obj.Prog) uin
 
 	switch a {
 	default:
-		ctxt.Diag("bad fst %v", Aconv(a))
+		ctxt.Diag("bad fst %v", obj.Aconv(a))
 		fallthrough
 
 	case AMOVD:
diff --git a/src/cmd/internal/obj/arm/list5.go b/src/cmd/internal/obj/arm/list5.go
index 60caedebc1..0625cffcf9 100644
--- a/src/cmd/internal/obj/arm/list5.go
+++ b/src/cmd/internal/obj/arm/list5.go
@@ -79,57 +79,16 @@ func Pconv(p *obj.Prog) string {
 	var str string
 	if a == obj.ADATA {
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v/%d,%v",
-			p.Pc, p.Line(), Aconv(a), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(a), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
 	} else if p.As == obj.ATEXT {
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%d,%v",
-			p.Pc, p.Line(), Aconv(a), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(a), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
 	} else if p.Reg == 0 {
 		str = fmt.Sprintf("%.5d (%v)\t%v%s\t%v,%v",
-			p.Pc, p.Line(), Aconv(a), sc, obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(a), sc, obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
 	} else {
 		str = fmt.Sprintf("%.5d (%v)\t%v%s\t%v,%v,%v",
-			p.Pc, p.Line(), Aconv(a), sc, obj.Dconv(p, &p.From), Rconv(int(p.Reg)), obj.Dconv(p, &p.To))
-	}
-
-	var fp string
-	fp += str
-	return fp
-}
-
-func Aconv(a int) string {
-	s := "???"
-	if a >= obj.AXXX && a < ALAST {
-		s = Anames[a]
-	}
-	var fp string
-	fp += s
-	return fp
-}
-
-func RAconv(a *obj.Addr) string {
-	str := fmt.Sprintf("GOK-reglist")
-	switch a.Type {
-	case obj.TYPE_CONST:
-		if a.Reg != 0 {
-			break
-		}
-		if a.Sym != nil {
-			break
-		}
-		v := int(a.Offset)
-		str = ""
-		for i := 0; i < NREG; i++ {
-			if v&(1<<uint(i)) != 0 {
-				if str == "" {
-					str += "[R"
-				} else {
-					str += ",R"
-				}
-				str += fmt.Sprintf("%d", i)
-			}
-		}
-
-		str += "]"
+			p.Pc, p.Line(), obj.Aconv(a), sc, obj.Dconv(p, &p.From), Rconv(int(p.Reg)), obj.Dconv(p, &p.To))
 	}
 
 	var fp string
@@ -139,6 +98,7 @@ func RAconv(a *obj.Addr) string {
 
 func init() {
 	obj.RegisterRegister(obj.RBaseARM, MAXREG, Rconv)
+	obj.RegisterOpcode(obj.ABaseARM, Anames)
 }
 
 func Rconv(r int) string {
diff --git a/src/cmd/internal/obj/i386/8.out.go b/src/cmd/internal/obj/i386/8.out.go
index ab58cc1f0c..6e4fca186a 100644
--- a/src/cmd/internal/obj/i386/8.out.go
+++ b/src/cmd/internal/obj/i386/8.out.go
@@ -33,7 +33,7 @@ package i386
 import "cmd/internal/obj"
 
 const (
-	AAAA = obj.A_ARCHSPECIFIC + iota
+	AAAA = obj.ABase386 + obj.A_ARCHSPECIFIC + iota
 	AAAD
 	AAAM
 	AAAS
diff --git a/src/cmd/internal/obj/i386/anames8.go b/src/cmd/internal/obj/i386/anames8.go
index ebf2e5e65a..60245634ca 100644
--- a/src/cmd/internal/obj/i386/anames8.go
+++ b/src/cmd/internal/obj/i386/anames8.go
@@ -1,29 +1,12 @@
 package i386
 
+import "cmd/internal/obj"
+
 /*
  * this is the ranlib header
  */
 var Anames = []string{
-	"XXX",
-	"CALL",
-	"CHECKNIL",
-	"DATA",
-	"DUFFCOPY",
-	"DUFFZERO",
-	"END",
-	"FUNCDATA",
-	"GLOBL",
-	"JMP",
-	"NOP",
-	"PCDATA",
-	"RET",
-	"TEXT",
-	"TYPE",
-	"UNDEF",
-	"USEFIELD",
-	"VARDEF",
-	"VARKILL",
-	"AAA",
+	obj.A_ARCHSPECIFIC: "AAA",
 	"AAD",
 	"AAM",
 	"AAS",
diff --git a/src/cmd/internal/obj/i386/asm8.go b/src/cmd/internal/obj/i386/asm8.go
index 112e839c16..8ad2304f27 100644
--- a/src/cmd/internal/obj/i386/asm8.go
+++ b/src/cmd/internal/obj/i386/asm8.go
@@ -58,7 +58,7 @@ type ytab struct {
 	zoffset uint8
 }
 
-var opindex [ALAST + 1]*Optab
+var opindex [(ALAST + 1) & obj.AMask]*Optab
 
 const (
 	Yxxx = 0 + iota
@@ -1331,12 +1331,11 @@ func span8(ctxt *obj.Link, s *obj.LSym) {
 }
 
 func instinit() {
-	var c int
 
 	for i := 1; optab[i].as != 0; i++ {
-		c = int(optab[i].as)
+		c := optab[i].as & obj.AMask
 		if opindex[c] != nil {
-			log.Fatalf("phase error in optab: %d (%v)", i, Aconv(c))
+			log.Fatalf("phase error in optab: %d (%v)", i, obj.Aconv(int(optab[i].as)))
 		}
 		opindex[c] = &optab[i]
 	}
@@ -1969,7 +1968,7 @@ const (
 
 var ymovtab = []uint8{
 	/* push */
-	APUSHL,
+	APUSHL & obj.AMask,
 	Ycs,
 	Ynone,
 	0,
@@ -1977,7 +1976,7 @@ var ymovtab = []uint8{
 	E,
 	0,
 	0,
-	APUSHL,
+	APUSHL & obj.AMask,
 	Yss,
 	Ynone,
 	0,
@@ -1985,7 +1984,7 @@ var ymovtab = []uint8{
 	E,
 	0,
 	0,
-	APUSHL,
+	APUSHL & obj.AMask,
 	Yds,
 	Ynone,
 	0,
@@ -1993,7 +1992,7 @@ var ymovtab = []uint8{
 	E,
 	0,
 	0,
-	APUSHL,
+	APUSHL & obj.AMask,
 	Yes,
 	Ynone,
 	0,
@@ -2001,7 +2000,7 @@ var ymovtab = []uint8{
 	E,
 	0,
 	0,
-	APUSHL,
+	APUSHL & obj.AMask,
 	Yfs,
 	Ynone,
 	0,
@@ -2009,7 +2008,7 @@ var ymovtab = []uint8{
 	0xa0,
 	E,
 	0,
-	APUSHL,
+	APUSHL & obj.AMask,
 	Ygs,
 	Ynone,
 	0,
@@ -2017,7 +2016,7 @@ var ymovtab = []uint8{
 	0xa8,
 	E,
 	0,
-	APUSHW,
+	APUSHW & obj.AMask,
 	Ycs,
 	Ynone,
 	0,
@@ -2025,7 +2024,7 @@ var ymovtab = []uint8{
 	0x0e,
 	E,
 	0,
-	APUSHW,
+	APUSHW & obj.AMask,
 	Yss,
 	Ynone,
 	0,
@@ -2033,7 +2032,7 @@ var ymovtab = []uint8{
 	0x16,
 	E,
 	0,
-	APUSHW,
+	APUSHW & obj.AMask,
 	Yds,
 	Ynone,
 	0,
@@ -2041,7 +2040,7 @@ var ymovtab = []uint8{
 	0x1e,
 	E,
 	0,
-	APUSHW,
+	APUSHW & obj.AMask,
 	Yes,
 	Ynone,
 	0,
@@ -2049,7 +2048,7 @@ var ymovtab = []uint8{
 	0x06,
 	E,
 	0,
-	APUSHW,
+	APUSHW & obj.AMask,
 	Yfs,
 	Ynone,
 	0,
@@ -2057,7 +2056,7 @@ var ymovtab = []uint8{
 	0x0f,
 	0xa0,
 	E,
-	APUSHW,
+	APUSHW & obj.AMask,
 	Ygs,
 	Ynone,
 	0,
@@ -2067,7 +2066,7 @@ var ymovtab = []uint8{
 	E,
 
 	/* pop */
-	APOPL,
+	APOPL & obj.AMask,
 	Ynone,
 	Yds,
 	0,
@@ -2075,7 +2074,7 @@ var ymovtab = []uint8{
 	E,
 	0,
 	0,
-	APOPL,
+	APOPL & obj.AMask,
 	Ynone,
 	Yes,
 	0,
@@ -2083,7 +2082,7 @@ var ymovtab = []uint8{
 	E,
 	0,
 	0,
-	APOPL,
+	APOPL & obj.AMask,
 	Ynone,
 	Yss,
 	0,
@@ -2091,7 +2090,7 @@ var ymovtab = []uint8{
 	E,
 	0,
 	0,
-	APOPL,
+	APOPL & obj.AMask,
 	Ynone,
 	Yfs,
 	0,
@@ -2099,7 +2098,7 @@ var ymovtab = []uint8{
 	0xa1,
 	E,
 	0,
-	APOPL,
+	APOPL & obj.AMask,
 	Ynone,
 	Ygs,
 	0,
@@ -2107,7 +2106,7 @@ var ymovtab = []uint8{
 	0xa9,
 	E,
 	0,
-	APOPW,
+	APOPW & obj.AMask,
 	Ynone,
 	Yds,
 	0,
@@ -2115,7 +2114,7 @@ var ymovtab = []uint8{
 	0x1f,
 	E,
 	0,
-	APOPW,
+	APOPW & obj.AMask,
 	Ynone,
 	Yes,
 	0,
@@ -2123,7 +2122,7 @@ var ymovtab = []uint8{
 	0x07,
 	E,
 	0,
-	APOPW,
+	APOPW & obj.AMask,
 	Ynone,
 	Yss,
 	0,
@@ -2131,7 +2130,7 @@ var ymovtab = []uint8{
 	0x17,
 	E,
 	0,
-	APOPW,
+	APOPW & obj.AMask,
 	Ynone,
 	Yfs,
 	0,
@@ -2139,7 +2138,7 @@ var ymovtab = []uint8{
 	0x0f,
 	0xa1,
 	E,
-	APOPW,
+	APOPW & obj.AMask,
 	Ynone,
 	Ygs,
 	0,
@@ -2149,7 +2148,7 @@ var ymovtab = []uint8{
 	E,
 
 	/* mov seg */
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yes,
 	Yml,
 	1,
@@ -2157,7 +2156,7 @@ var ymovtab = []uint8{
 	0,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Ycs,
 	Yml,
 	1,
@@ -2165,7 +2164,7 @@ var ymovtab = []uint8{
 	1,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yss,
 	Yml,
 	1,
@@ -2173,7 +2172,7 @@ var ymovtab = []uint8{
 	2,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yds,
 	Yml,
 	1,
@@ -2181,7 +2180,7 @@ var ymovtab = []uint8{
 	3,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yfs,
 	Yml,
 	1,
@@ -2189,7 +2188,7 @@ var ymovtab = []uint8{
 	4,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Ygs,
 	Yml,
 	1,
@@ -2197,7 +2196,7 @@ var ymovtab = []uint8{
 	5,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Yes,
 	2,
@@ -2205,7 +2204,7 @@ var ymovtab = []uint8{
 	0,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Ycs,
 	2,
@@ -2213,7 +2212,7 @@ var ymovtab = []uint8{
 	1,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Yss,
 	2,
@@ -2221,7 +2220,7 @@ var ymovtab = []uint8{
 	2,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Yds,
 	2,
@@ -2229,7 +2228,7 @@ var ymovtab = []uint8{
 	3,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Yfs,
 	2,
@@ -2237,7 +2236,7 @@ var ymovtab = []uint8{
 	4,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Ygs,
 	2,
@@ -2247,7 +2246,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* mov cr */
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ycr0,
 	Yml,
 	3,
@@ -2255,7 +2254,7 @@ var ymovtab = []uint8{
 	0x20,
 	0,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ycr2,
 	Yml,
 	3,
@@ -2263,7 +2262,7 @@ var ymovtab = []uint8{
 	0x20,
 	2,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ycr3,
 	Yml,
 	3,
@@ -2271,7 +2270,7 @@ var ymovtab = []uint8{
 	0x20,
 	3,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ycr4,
 	Yml,
 	3,
@@ -2279,7 +2278,7 @@ var ymovtab = []uint8{
 	0x20,
 	4,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ycr0,
 	4,
@@ -2287,7 +2286,7 @@ var ymovtab = []uint8{
 	0x22,
 	0,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ycr2,
 	4,
@@ -2295,7 +2294,7 @@ var ymovtab = []uint8{
 	0x22,
 	2,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ycr3,
 	4,
@@ -2303,7 +2302,7 @@ var ymovtab = []uint8{
 	0x22,
 	3,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ycr4,
 	4,
@@ -2313,7 +2312,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* mov dr */
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ydr0,
 	Yml,
 	3,
@@ -2321,7 +2320,7 @@ var ymovtab = []uint8{
 	0x21,
 	0,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ydr6,
 	Yml,
 	3,
@@ -2329,7 +2328,7 @@ var ymovtab = []uint8{
 	0x21,
 	6,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ydr7,
 	Yml,
 	3,
@@ -2337,7 +2336,7 @@ var ymovtab = []uint8{
 	0x21,
 	7,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ydr0,
 	4,
@@ -2345,7 +2344,7 @@ var ymovtab = []uint8{
 	0x23,
 	0,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ydr6,
 	4,
@@ -2353,7 +2352,7 @@ var ymovtab = []uint8{
 	0x23,
 	6,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ydr7,
 	4,
@@ -2363,7 +2362,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* mov tr */
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ytr6,
 	Yml,
 	3,
@@ -2371,7 +2370,7 @@ var ymovtab = []uint8{
 	0x24,
 	6,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ytr7,
 	Yml,
 	3,
@@ -2379,7 +2378,7 @@ var ymovtab = []uint8{
 	0x24,
 	7,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ytr6,
 	4,
@@ -2387,7 +2386,7 @@ var ymovtab = []uint8{
 	0x26,
 	6,
 	E,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ytr7,
 	4,
@@ -2397,7 +2396,7 @@ var ymovtab = []uint8{
 	E,
 
 	/* lgdt, sgdt, lidt, sidt */
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ym,
 	Ygdtr,
 	4,
@@ -2405,7 +2404,7 @@ var ymovtab = []uint8{
 	0x01,
 	2,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ygdtr,
 	Ym,
 	3,
@@ -2413,7 +2412,7 @@ var ymovtab = []uint8{
 	0x01,
 	0,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ym,
 	Yidtr,
 	4,
@@ -2421,7 +2420,7 @@ var ymovtab = []uint8{
 	0x01,
 	3,
 	0,
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yidtr,
 	Ym,
 	3,
@@ -2431,7 +2430,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* lldt, sldt */
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Yldtr,
 	4,
@@ -2439,7 +2438,7 @@ var ymovtab = []uint8{
 	0x00,
 	2,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yldtr,
 	Yml,
 	3,
@@ -2449,7 +2448,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* lmsw, smsw */
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Ymsw,
 	4,
@@ -2457,7 +2456,7 @@ var ymovtab = []uint8{
 	0x01,
 	6,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Ymsw,
 	Yml,
 	3,
@@ -2467,7 +2466,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* ltr, str */
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Ytask,
 	4,
@@ -2475,7 +2474,7 @@ var ymovtab = []uint8{
 	0x00,
 	3,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Ytask,
 	Yml,
 	3,
@@ -2485,7 +2484,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* load full pointer */
-	AMOVL,
+	AMOVL & obj.AMask,
 	Yml,
 	Ycol,
 	5,
@@ -2493,7 +2492,7 @@ var ymovtab = []uint8{
 	0,
 	0,
 	0,
-	AMOVW,
+	AMOVW & obj.AMask,
 	Yml,
 	Ycol,
 	5,
@@ -2503,7 +2502,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* double shift */
-	ASHLL,
+	ASHLL & obj.AMask,
 	Ycol,
 	Yml,
 	6,
@@ -2511,7 +2510,7 @@ var ymovtab = []uint8{
 	0xa5,
 	0,
 	0,
-	ASHRL,
+	ASHRL & obj.AMask,
 	Ycol,
 	Yml,
 	6,
@@ -2521,7 +2520,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* extra imul */
-	AIMULW,
+	AIMULW & obj.AMask,
 	Yml,
 	Yrl,
 	7,
@@ -2529,7 +2528,7 @@ var ymovtab = []uint8{
 	0xaf,
 	0,
 	0,
-	AIMULL,
+	AIMULL & obj.AMask,
 	Yml,
 	Yrl,
 	7,
@@ -2539,7 +2538,7 @@ var ymovtab = []uint8{
 	0,
 
 	/* load TLS base pointer */
-	AMOVL,
+	AMOVL & obj.AMask,
 	Ytls,
 	Yrl,
 	8,
@@ -2712,7 +2711,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
 
 	ft := int(p.Ft) * Ymax
 	tt := int(p.Tt) * Ymax
-	o := opindex[p.As]
+	o := opindex[p.As&obj.AMask]
 
 	z := 0
 	var a *obj.Addr
@@ -3163,7 +3162,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
 domov:
 	var pp obj.Prog
 	for t := []byte(ymovtab); t[0] != 0; t = t[8:] {
-		if p.As == int16(t[0]) {
+		if p.As&obj.AMask == int16(t[0]) {
 			if ycover[ft+int(t[1])] != 0 {
 				if ycover[tt+int(t[2])] != 0 {
 					switch t[3] {
diff --git a/src/cmd/internal/obj/i386/list8.go b/src/cmd/internal/obj/i386/list8.go
index f843006bdb..f62253976b 100644
--- a/src/cmd/internal/obj/i386/list8.go
+++ b/src/cmd/internal/obj/i386/list8.go
@@ -47,21 +47,21 @@ func Pconv(p *obj.Prog) string {
 	switch p.As {
 	case obj.ADATA:
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v/%d,%v",
-			p.Pc, p.Line(), Aconv(int(p.As)), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(int(p.As)), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
 
 	case obj.ATEXT:
 		if p.From3.Offset != 0 {
 			str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%d,%v",
-				p.Pc, p.Line(), Aconv(int(p.As)), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
+				p.Pc, p.Line(), obj.Aconv(int(p.As)), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
 			break
 		}
 
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%v",
-			p.Pc, p.Line(), Aconv(int(p.As)), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(int(p.As)), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
 
 	default:
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%v",
-			p.Pc, p.Line(), Aconv(int(p.As)), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(int(p.As)), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
 
 		// TODO(rsc): This special case is for SHRQ $32, AX:DX, which encodes as
 		//	SHRQ $32(DX*0), AX
@@ -76,10 +76,6 @@ func Pconv(p *obj.Prog) string {
 	return fp
 }
 
-func Aconv(i int) string {
-	return Anames[i]
-}
-
 var Register = []string{
 	"AL", /* [REG_AL] */
 	"CL",
@@ -154,6 +150,7 @@ var Register = []string{
 
 func init() {
 	obj.RegisterRegister(obj.RBase386, obj.RBase386+len(Register), Rconv)
+	obj.RegisterOpcode(obj.ABase386, Anames)
 }
 
 func Rconv(r int) string {
diff --git a/src/cmd/internal/obj/link.go b/src/cmd/internal/obj/link.go
index 4bac11e3fe..95c9886ab2 100644
--- a/src/cmd/internal/obj/link.go
+++ b/src/cmd/internal/obj/link.go
@@ -424,6 +424,10 @@ const (
 // These are the portable opcodes, common to all architectures.
 // Each architecture defines many more arch-specific opcodes,
 // with values starting at A_ARCHSPECIFIC.
+// Each architecture adds an offset to this so each machine has
+// distinct space for its instructions. The offset is a power of
+// two so it can be masked to return to origin zero.
+// See the definitions of ABase386 etc.
 const (
 	AXXX = 0 + iota
 	ACALL
@@ -570,30 +574,4 @@ const (
 	LinkExternal
 )
 
-// asm5.c
-
-// asm6.c
-
-// asm8.c
-
-// asm9.c
-
-// data.c
-
-// go.c
-
-// ld.c
-
-// list[5689].c
-
-// obj.c
-
-// objfile.c
-
-// pass.c
-
-// pcln.c
-
-// sym.c
-
 var linkbasepointer int
diff --git a/src/cmd/internal/obj/ppc64/9.out.go b/src/cmd/internal/obj/ppc64/9.out.go
index 3030455bbd..d3d54fda79 100644
--- a/src/cmd/internal/obj/ppc64/9.out.go
+++ b/src/cmd/internal/obj/ppc64/9.out.go
@@ -218,7 +218,7 @@ const (
 )
 
 const (
-	AADD = obj.A_ARCHSPECIFIC + iota
+	AADD = obj.ABasePPC64 + obj.A_ARCHSPECIFIC + iota
 	AADDCC
 	AADDV
 	AADDVCC
diff --git a/src/cmd/internal/obj/ppc64/anames9.go b/src/cmd/internal/obj/ppc64/anames9.go
index 9d755dedbc..057256a430 100644
--- a/src/cmd/internal/obj/ppc64/anames9.go
+++ b/src/cmd/internal/obj/ppc64/anames9.go
@@ -1,29 +1,9 @@
 package ppc64
 
-/*
- * this is the ranlib header
- */
+import "cmd/internal/obj"
+
 var Anames = []string{
-	"XXX",
-	"CALL",
-	"CHECKNIL",
-	"DATA",
-	"DUFFCOPY",
-	"DUFFZERO",
-	"END",
-	"FUNCDATA",
-	"GLOBL",
-	"JMP",
-	"NOP",
-	"PCDATA",
-	"RET",
-	"TEXT",
-	"TYPE",
-	"UNDEF",
-	"USEFIELD",
-	"VARDEF",
-	"VARKILL",
-	"ADD",
+	obj.A_ARCHSPECIFIC: "ADD",
 	"ADDCC",
 	"ADDV",
 	"ADDVCC",
diff --git a/src/cmd/internal/obj/ppc64/asm9.go b/src/cmd/internal/obj/ppc64/asm9.go
index 16d1626727..30d7d835f1 100644
--- a/src/cmd/internal/obj/ppc64/asm9.go
+++ b/src/cmd/internal/obj/ppc64/asm9.go
@@ -402,7 +402,7 @@ type Oprang struct {
 	stop  []Optab
 }
 
-var oprange [ALAST]Oprang
+var oprange [ALAST & obj.AMask]Oprang
 
 var xcmp [C_NCLASS][C_NCLASS]uint8
 
@@ -414,7 +414,7 @@ func span9(ctxt *obj.Link, cursym *obj.LSym) {
 	ctxt.Cursym = cursym
 	ctxt.Autosize = int32(p.To.Offset + 8)
 
-	if oprange[AANDN].start == nil {
+	if oprange[AANDN&obj.AMask].start == nil {
 		buildop(ctxt)
 	}
 
@@ -744,13 +744,13 @@ func oplook(ctxt *obj.Link, p *obj.Prog) *Optab {
 	}
 
 	//print("oplook %P %d %d %d %d\n", p, a1, a2, a3, a4);
-	r := int(p.As)
+	r0 := p.As & obj.AMask
 
-	o := oprange[r].start
+	o := oprange[r0].start
 	if o == nil {
-		o = oprange[r].stop /* just generate an error */
+		o = oprange[r0].stop /* just generate an error */
 	}
-	e := oprange[r].stop
+	e := oprange[r0].stop
 	c1 := xcmp[a1][:]
 	c3 := xcmp[a3][:]
 	c4 := xcmp[a4][:]
@@ -767,7 +767,7 @@ func oplook(ctxt *obj.Link, p *obj.Prog) *Optab {
 		}
 	}
 
-	ctxt.Diag("illegal combination %v %v %v %v %v", Aconv(int(p.As)), DRconv(a1), DRconv(a2), DRconv(a3), DRconv(a4))
+	ctxt.Diag("illegal combination %v %v %v %v %v", obj.Aconv(int(p.As)), DRconv(a1), DRconv(a2), DRconv(a3), DRconv(a4))
 	prasm(p)
 	if o == nil {
 		o = optab
@@ -887,6 +887,9 @@ func (x ocmp) Less(i, j int) bool {
 	}
 	return false
 }
+func opset(a, b0 int16) {
+	oprange[a&obj.AMask] = oprange[b0]
+}
 
 func buildop(ctxt *obj.Link) {
 	var n int
@@ -901,356 +904,355 @@ func buildop(ctxt *obj.Link) {
 	for n = 0; optab[n].as != obj.AXXX; n++ {
 	}
 	sort.Sort(ocmp(optab[:n]))
-	var r int
 	for i := 0; i < n; i++ {
-		r = int(optab[i].as)
-		oprange[r].start = optab[i:]
-		for int(optab[i].as) == r {
+		r0 := optab[i].as & obj.AMask
+		oprange[r0].start = optab[i:]
+		for optab[i].as&obj.AMask == r0 {
 			i++
 		}
-		oprange[r].stop = optab[i:]
+		oprange[r0].stop = optab[i:]
 		i--
 
-		switch r {
+		switch r0 {
 		default:
-			ctxt.Diag("unknown op in build: %v", Aconv(r))
+			ctxt.Diag("unknown op in build: %v", obj.Aconv(int(optab[i].as)))
 			log.Fatalf("bad code")
 
 		case ADCBF: /* unary indexed: op (b+a); op (b) */
-			oprange[ADCBI] = oprange[r]
+			opset(ADCBI, r0)
 
-			oprange[ADCBST] = oprange[r]
-			oprange[ADCBT] = oprange[r]
-			oprange[ADCBTST] = oprange[r]
-			oprange[ADCBZ] = oprange[r]
-			oprange[AICBI] = oprange[r]
+			opset(ADCBST, r0)
+			opset(ADCBT, r0)
+			opset(ADCBTST, r0)
+			opset(ADCBZ, r0)
+			opset(AICBI, r0)
 
 		case AECOWX: /* indexed store: op s,(b+a); op s,(b) */
-			oprange[ASTWCCC] = oprange[r]
+			opset(ASTWCCC, r0)
 
-			oprange[ASTDCCC] = oprange[r]
+			opset(ASTDCCC, r0)
 
 		case AREM: /* macro */
-			oprange[AREMCC] = oprange[r]
+			opset(AREMCC, r0)
 
-			oprange[AREMV] = oprange[r]
-			oprange[AREMVCC] = oprange[r]
+			opset(AREMV, r0)
+			opset(AREMVCC, r0)
 
 		case AREMU:
-			oprange[AREMU] = oprange[r]
-			oprange[AREMUCC] = oprange[r]
-			oprange[AREMUV] = oprange[r]
-			oprange[AREMUVCC] = oprange[r]
+			opset(AREMU, r0)
+			opset(AREMUCC, r0)
+			opset(AREMUV, r0)
+			opset(AREMUVCC, r0)
 
 		case AREMD:
-			oprange[AREMDCC] = oprange[r]
-			oprange[AREMDV] = oprange[r]
-			oprange[AREMDVCC] = oprange[r]
+			opset(AREMDCC, r0)
+			opset(AREMDV, r0)
+			opset(AREMDVCC, r0)
 
 		case AREMDU:
-			oprange[AREMDU] = oprange[r]
-			oprange[AREMDUCC] = oprange[r]
-			oprange[AREMDUV] = oprange[r]
-			oprange[AREMDUVCC] = oprange[r]
+			opset(AREMDU, r0)
+			opset(AREMDUCC, r0)
+			opset(AREMDUV, r0)
+			opset(AREMDUVCC, r0)
 
 		case ADIVW: /* op Rb[,Ra],Rd */
-			oprange[AMULHW] = oprange[r]
+			opset(AMULHW, r0)
 
-			oprange[AMULHWCC] = oprange[r]
-			oprange[AMULHWU] = oprange[r]
-			oprange[AMULHWUCC] = oprange[r]
-			oprange[AMULLWCC] = oprange[r]
-			oprange[AMULLWVCC] = oprange[r]
-			oprange[AMULLWV] = oprange[r]
-			oprange[ADIVWCC] = oprange[r]
-			oprange[ADIVWV] = oprange[r]
-			oprange[ADIVWVCC] = oprange[r]
-			oprange[ADIVWU] = oprange[r]
-			oprange[ADIVWUCC] = oprange[r]
-			oprange[ADIVWUV] = oprange[r]
-			oprange[ADIVWUVCC] = oprange[r]
-			oprange[AADDCC] = oprange[r]
-			oprange[AADDCV] = oprange[r]
-			oprange[AADDCVCC] = oprange[r]
-			oprange[AADDV] = oprange[r]
-			oprange[AADDVCC] = oprange[r]
-			oprange[AADDE] = oprange[r]
-			oprange[AADDECC] = oprange[r]
-			oprange[AADDEV] = oprange[r]
-			oprange[AADDEVCC] = oprange[r]
-			oprange[ACRAND] = oprange[r]
-			oprange[ACRANDN] = oprange[r]
-			oprange[ACREQV] = oprange[r]
-			oprange[ACRNAND] = oprange[r]
-			oprange[ACRNOR] = oprange[r]
-			oprange[ACROR] = oprange[r]
-			oprange[ACRORN] = oprange[r]
-			oprange[ACRXOR] = oprange[r]
-			oprange[AMULHD] = oprange[r]
-			oprange[AMULHDCC] = oprange[r]
-			oprange[AMULHDU] = oprange[r]
-			oprange[AMULHDUCC] = oprange[r]
-			oprange[AMULLD] = oprange[r]
-			oprange[AMULLDCC] = oprange[r]
-			oprange[AMULLDVCC] = oprange[r]
-			oprange[AMULLDV] = oprange[r]
-			oprange[ADIVD] = oprange[r]
-			oprange[ADIVDCC] = oprange[r]
-			oprange[ADIVDVCC] = oprange[r]
-			oprange[ADIVDV] = oprange[r]
-			oprange[ADIVDU] = oprange[r]
-			oprange[ADIVDUCC] = oprange[r]
-			oprange[ADIVDUVCC] = oprange[r]
-			oprange[ADIVDUCC] = oprange[r]
+			opset(AMULHWCC, r0)
+			opset(AMULHWU, r0)
+			opset(AMULHWUCC, r0)
+			opset(AMULLWCC, r0)
+			opset(AMULLWVCC, r0)
+			opset(AMULLWV, r0)
+			opset(ADIVWCC, r0)
+			opset(ADIVWV, r0)
+			opset(ADIVWVCC, r0)
+			opset(ADIVWU, r0)
+			opset(ADIVWUCC, r0)
+			opset(ADIVWUV, r0)
+			opset(ADIVWUVCC, r0)
+			opset(AADDCC, r0)
+			opset(AADDCV, r0)
+			opset(AADDCVCC, r0)
+			opset(AADDV, r0)
+			opset(AADDVCC, r0)
+			opset(AADDE, r0)
+			opset(AADDECC, r0)
+			opset(AADDEV, r0)
+			opset(AADDEVCC, r0)
+			opset(ACRAND, r0)
+			opset(ACRANDN, r0)
+			opset(ACREQV, r0)
+			opset(ACRNAND, r0)
+			opset(ACRNOR, r0)
+			opset(ACROR, r0)
+			opset(ACRORN, r0)
+			opset(ACRXOR, r0)
+			opset(AMULHD, r0)
+			opset(AMULHDCC, r0)
+			opset(AMULHDU, r0)
+			opset(AMULHDUCC, r0)
+			opset(AMULLD, r0)
+			opset(AMULLDCC, r0)
+			opset(AMULLDVCC, r0)
+			opset(AMULLDV, r0)
+			opset(ADIVD, r0)
+			opset(ADIVDCC, r0)
+			opset(ADIVDVCC, r0)
+			opset(ADIVDV, r0)
+			opset(ADIVDU, r0)
+			opset(ADIVDUCC, r0)
+			opset(ADIVDUVCC, r0)
+			opset(ADIVDUCC, r0)
 
 		case AMOVBZ: /* lbz, stz, rlwm(r/r), lhz, lha, stz, and x variants */
-			oprange[AMOVH] = oprange[r]
+			opset(AMOVH, r0)
 
-			oprange[AMOVHZ] = oprange[r]
+			opset(AMOVHZ, r0)
 
 		case AMOVBZU: /* lbz[x]u, stb[x]u, lhz[x]u, lha[x]u, sth[u]x, ld[x]u, std[u]x */
-			oprange[AMOVHU] = oprange[r]
+			opset(AMOVHU, r0)
 
-			oprange[AMOVHZU] = oprange[r]
-			oprange[AMOVWU] = oprange[r]
-			oprange[AMOVWZU] = oprange[r]
-			oprange[AMOVDU] = oprange[r]
-			oprange[AMOVMW] = oprange[r]
+			opset(AMOVHZU, r0)
+			opset(AMOVWU, r0)
+			opset(AMOVWZU, r0)
+			opset(AMOVDU, r0)
+			opset(AMOVMW, r0)
 
 		case AAND: /* logical op Rb,Rs,Ra; no literal */
-			oprange[AANDN] = oprange[r]
+			opset(AANDN, r0)
 
-			oprange[AANDNCC] = oprange[r]
-			oprange[AEQV] = oprange[r]
-			oprange[AEQVCC] = oprange[r]
-			oprange[ANAND] = oprange[r]
-			oprange[ANANDCC] = oprange[r]
-			oprange[ANOR] = oprange[r]
-			oprange[ANORCC] = oprange[r]
-			oprange[AORCC] = oprange[r]
-			oprange[AORN] = oprange[r]
-			oprange[AORNCC] = oprange[r]
-			oprange[AXORCC] = oprange[r]
+			opset(AANDNCC, r0)
+			opset(AEQV, r0)
+			opset(AEQVCC, r0)
+			opset(ANAND, r0)
+			opset(ANANDCC, r0)
+			opset(ANOR, r0)
+			opset(ANORCC, r0)
+			opset(AORCC, r0)
+			opset(AORN, r0)
+			opset(AORNCC, r0)
+			opset(AXORCC, r0)
 
 		case AADDME: /* op Ra, Rd */
-			oprange[AADDMECC] = oprange[r]
+			opset(AADDMECC, r0)
 
-			oprange[AADDMEV] = oprange[r]
-			oprange[AADDMEVCC] = oprange[r]
-			oprange[AADDZE] = oprange[r]
-			oprange[AADDZECC] = oprange[r]
-			oprange[AADDZEV] = oprange[r]
-			oprange[AADDZEVCC] = oprange[r]
-			oprange[ASUBME] = oprange[r]
-			oprange[ASUBMECC] = oprange[r]
-			oprange[ASUBMEV] = oprange[r]
-			oprange[ASUBMEVCC] = oprange[r]
-			oprange[ASUBZE] = oprange[r]
-			oprange[ASUBZECC] = oprange[r]
-			oprange[ASUBZEV] = oprange[r]
-			oprange[ASUBZEVCC] = oprange[r]
+			opset(AADDMEV, r0)
+			opset(AADDMEVCC, r0)
+			opset(AADDZE, r0)
+			opset(AADDZECC, r0)
+			opset(AADDZEV, r0)
+			opset(AADDZEVCC, r0)
+			opset(ASUBME, r0)
+			opset(ASUBMECC, r0)
+			opset(ASUBMEV, r0)
+			opset(ASUBMEVCC, r0)
+			opset(ASUBZE, r0)
+			opset(ASUBZECC, r0)
+			opset(ASUBZEV, r0)
+			opset(ASUBZEVCC, r0)
 
 		case AADDC:
-			oprange[AADDCCC] = oprange[r]
+			opset(AADDCCC, r0)
 
 		case ABEQ:
-			oprange[ABGE] = oprange[r]
-			oprange[ABGT] = oprange[r]
-			oprange[ABLE] = oprange[r]
-			oprange[ABLT] = oprange[r]
-			oprange[ABNE] = oprange[r]
-			oprange[ABVC] = oprange[r]
-			oprange[ABVS] = oprange[r]
+			opset(ABGE, r0)
+			opset(ABGT, r0)
+			opset(ABLE, r0)
+			opset(ABLT, r0)
+			opset(ABNE, r0)
+			opset(ABVC, r0)
+			opset(ABVS, r0)
 
 		case ABR:
-			oprange[ABL] = oprange[r]
+			opset(ABL, r0)
 
 		case ABC:
-			oprange[ABCL] = oprange[r]
+			opset(ABCL, r0)
 
 		case AEXTSB: /* op Rs, Ra */
-			oprange[AEXTSBCC] = oprange[r]
+			opset(AEXTSBCC, r0)
 
-			oprange[AEXTSH] = oprange[r]
-			oprange[AEXTSHCC] = oprange[r]
-			oprange[ACNTLZW] = oprange[r]
-			oprange[ACNTLZWCC] = oprange[r]
-			oprange[ACNTLZD] = oprange[r]
-			oprange[AEXTSW] = oprange[r]
-			oprange[AEXTSWCC] = oprange[r]
-			oprange[ACNTLZDCC] = oprange[r]
+			opset(AEXTSH, r0)
+			opset(AEXTSHCC, r0)
+			opset(ACNTLZW, r0)
+			opset(ACNTLZWCC, r0)
+			opset(ACNTLZD, r0)
+			opset(AEXTSW, r0)
+			opset(AEXTSWCC, r0)
+			opset(ACNTLZDCC, r0)
 
 		case AFABS: /* fop [s,]d */
-			oprange[AFABSCC] = oprange[r]
+			opset(AFABSCC, r0)
 
-			oprange[AFNABS] = oprange[r]
-			oprange[AFNABSCC] = oprange[r]
-			oprange[AFNEG] = oprange[r]
-			oprange[AFNEGCC] = oprange[r]
-			oprange[AFRSP] = oprange[r]
-			oprange[AFRSPCC] = oprange[r]
-			oprange[AFCTIW] = oprange[r]
-			oprange[AFCTIWCC] = oprange[r]
-			oprange[AFCTIWZ] = oprange[r]
-			oprange[AFCTIWZCC] = oprange[r]
-			oprange[AFCTID] = oprange[r]
-			oprange[AFCTIDCC] = oprange[r]
-			oprange[AFCTIDZ] = oprange[r]
-			oprange[AFCTIDZCC] = oprange[r]
-			oprange[AFCFID] = oprange[r]
-			oprange[AFCFIDCC] = oprange[r]
-			oprange[AFRES] = oprange[r]
-			oprange[AFRESCC] = oprange[r]
-			oprange[AFRSQRTE] = oprange[r]
-			oprange[AFRSQRTECC] = oprange[r]
-			oprange[AFSQRT] = oprange[r]
-			oprange[AFSQRTCC] = oprange[r]
-			oprange[AFSQRTS] = oprange[r]
-			oprange[AFSQRTSCC] = oprange[r]
+			opset(AFNABS, r0)
+			opset(AFNABSCC, r0)
+			opset(AFNEG, r0)
+			opset(AFNEGCC, r0)
+			opset(AFRSP, r0)
+			opset(AFRSPCC, r0)
+			opset(AFCTIW, r0)
+			opset(AFCTIWCC, r0)
+			opset(AFCTIWZ, r0)
+			opset(AFCTIWZCC, r0)
+			opset(AFCTID, r0)
+			opset(AFCTIDCC, r0)
+			opset(AFCTIDZ, r0)
+			opset(AFCTIDZCC, r0)
+			opset(AFCFID, r0)
+			opset(AFCFIDCC, r0)
+			opset(AFRES, r0)
+			opset(AFRESCC, r0)
+			opset(AFRSQRTE, r0)
+			opset(AFRSQRTECC, r0)
+			opset(AFSQRT, r0)
+			opset(AFSQRTCC, r0)
+			opset(AFSQRTS, r0)
+			opset(AFSQRTSCC, r0)
 
 		case AFADD:
-			oprange[AFADDS] = oprange[r]
-			oprange[AFADDCC] = oprange[r]
-			oprange[AFADDSCC] = oprange[r]
-			oprange[AFDIV] = oprange[r]
-			oprange[AFDIVS] = oprange[r]
-			oprange[AFDIVCC] = oprange[r]
-			oprange[AFDIVSCC] = oprange[r]
-			oprange[AFSUB] = oprange[r]
-			oprange[AFSUBS] = oprange[r]
-			oprange[AFSUBCC] = oprange[r]
-			oprange[AFSUBSCC] = oprange[r]
+			opset(AFADDS, r0)
+			opset(AFADDCC, r0)
+			opset(AFADDSCC, r0)
+			opset(AFDIV, r0)
+			opset(AFDIVS, r0)
+			opset(AFDIVCC, r0)
+			opset(AFDIVSCC, r0)
+			opset(AFSUB, r0)
+			opset(AFSUBS, r0)
+			opset(AFSUBCC, r0)
+			opset(AFSUBSCC, r0)
 
 		case AFMADD:
-			oprange[AFMADDCC] = oprange[r]
-			oprange[AFMADDS] = oprange[r]
-			oprange[AFMADDSCC] = oprange[r]
-			oprange[AFMSUB] = oprange[r]
-			oprange[AFMSUBCC] = oprange[r]
-			oprange[AFMSUBS] = oprange[r]
-			oprange[AFMSUBSCC] = oprange[r]
-			oprange[AFNMADD] = oprange[r]
-			oprange[AFNMADDCC] = oprange[r]
-			oprange[AFNMADDS] = oprange[r]
-			oprange[AFNMADDSCC] = oprange[r]
-			oprange[AFNMSUB] = oprange[r]
-			oprange[AFNMSUBCC] = oprange[r]
-			oprange[AFNMSUBS] = oprange[r]
-			oprange[AFNMSUBSCC] = oprange[r]
-			oprange[AFSEL] = oprange[r]
-			oprange[AFSELCC] = oprange[r]
+			opset(AFMADDCC, r0)
+			opset(AFMADDS, r0)
+			opset(AFMADDSCC, r0)
+			opset(AFMSUB, r0)
+			opset(AFMSUBCC, r0)
+			opset(AFMSUBS, r0)
+			opset(AFMSUBSCC, r0)
+			opset(AFNMADD, r0)
+			opset(AFNMADDCC, r0)
+			opset(AFNMADDS, r0)
+			opset(AFNMADDSCC, r0)
+			opset(AFNMSUB, r0)
+			opset(AFNMSUBCC, r0)
+			opset(AFNMSUBS, r0)
+			opset(AFNMSUBSCC, r0)
+			opset(AFSEL, r0)
+			opset(AFSELCC, r0)
 
 		case AFMUL:
-			oprange[AFMULS] = oprange[r]
-			oprange[AFMULCC] = oprange[r]
-			oprange[AFMULSCC] = oprange[r]
+			opset(AFMULS, r0)
+			opset(AFMULCC, r0)
+			opset(AFMULSCC, r0)
 
 		case AFCMPO:
-			oprange[AFCMPU] = oprange[r]
+			opset(AFCMPU, r0)
 
 		case AMTFSB0:
-			oprange[AMTFSB0CC] = oprange[r]
-			oprange[AMTFSB1] = oprange[r]
-			oprange[AMTFSB1CC] = oprange[r]
+			opset(AMTFSB0CC, r0)
+			opset(AMTFSB1, r0)
+			opset(AMTFSB1CC, r0)
 
 		case ANEG: /* op [Ra,] Rd */
-			oprange[ANEGCC] = oprange[r]
+			opset(ANEGCC, r0)
 
-			oprange[ANEGV] = oprange[r]
-			oprange[ANEGVCC] = oprange[r]
+			opset(ANEGV, r0)
+			opset(ANEGVCC, r0)
 
 		case AOR: /* or/xor Rb,Rs,Ra; ori/xori $uimm,Rs,Ra; oris/xoris $uimm,Rs,Ra */
-			oprange[AXOR] = oprange[r]
+			opset(AXOR, r0)
 
 		case ASLW:
-			oprange[ASLWCC] = oprange[r]
-			oprange[ASRW] = oprange[r]
-			oprange[ASRWCC] = oprange[r]
+			opset(ASLWCC, r0)
+			opset(ASRW, r0)
+			opset(ASRWCC, r0)
 
 		case ASLD:
-			oprange[ASLDCC] = oprange[r]
-			oprange[ASRD] = oprange[r]
-			oprange[ASRDCC] = oprange[r]
+			opset(ASLDCC, r0)
+			opset(ASRD, r0)
+			opset(ASRDCC, r0)
 
 		case ASRAW: /* sraw Rb,Rs,Ra; srawi sh,Rs,Ra */
-			oprange[ASRAWCC] = oprange[r]
+			opset(ASRAWCC, r0)
 
 		case ASRAD: /* sraw Rb,Rs,Ra; srawi sh,Rs,Ra */
-			oprange[ASRADCC] = oprange[r]
+			opset(ASRADCC, r0)
 
 		case ASUB: /* SUB Ra,Rb,Rd => subf Rd,ra,rb */
-			oprange[ASUB] = oprange[r]
+			opset(ASUB, r0)
 
-			oprange[ASUBCC] = oprange[r]
-			oprange[ASUBV] = oprange[r]
-			oprange[ASUBVCC] = oprange[r]
-			oprange[ASUBCCC] = oprange[r]
-			oprange[ASUBCV] = oprange[r]
-			oprange[ASUBCVCC] = oprange[r]
-			oprange[ASUBE] = oprange[r]
-			oprange[ASUBECC] = oprange[r]
-			oprange[ASUBEV] = oprange[r]
-			oprange[ASUBEVCC] = oprange[r]
+			opset(ASUBCC, r0)
+			opset(ASUBV, r0)
+			opset(ASUBVCC, r0)
+			opset(ASUBCCC, r0)
+			opset(ASUBCV, r0)
+			opset(ASUBCVCC, r0)
+			opset(ASUBE, r0)
+			opset(ASUBECC, r0)
+			opset(ASUBEV, r0)
+			opset(ASUBEVCC, r0)
 
 		case ASYNC:
-			oprange[AISYNC] = oprange[r]
-			oprange[APTESYNC] = oprange[r]
-			oprange[ATLBSYNC] = oprange[r]
+			opset(AISYNC, r0)
+			opset(APTESYNC, r0)
+			opset(ATLBSYNC, r0)
 
 		case ARLWMI:
-			oprange[ARLWMICC] = oprange[r]
-			oprange[ARLWNM] = oprange[r]
-			oprange[ARLWNMCC] = oprange[r]
+			opset(ARLWMICC, r0)
+			opset(ARLWNM, r0)
+			opset(ARLWNMCC, r0)
 
 		case ARLDMI:
-			oprange[ARLDMICC] = oprange[r]
+			opset(ARLDMICC, r0)
 
 		case ARLDC:
-			oprange[ARLDCCC] = oprange[r]
+			opset(ARLDCCC, r0)
 
 		case ARLDCL:
-			oprange[ARLDCR] = oprange[r]
-			oprange[ARLDCLCC] = oprange[r]
-			oprange[ARLDCRCC] = oprange[r]
+			opset(ARLDCR, r0)
+			opset(ARLDCLCC, r0)
+			opset(ARLDCRCC, r0)
 
 		case AFMOVD:
-			oprange[AFMOVDCC] = oprange[r]
-			oprange[AFMOVDU] = oprange[r]
-			oprange[AFMOVS] = oprange[r]
-			oprange[AFMOVSU] = oprange[r]
+			opset(AFMOVDCC, r0)
+			opset(AFMOVDU, r0)
+			opset(AFMOVS, r0)
+			opset(AFMOVSU, r0)
 
 		case AECIWX:
-			oprange[ALWAR] = oprange[r]
-			oprange[ALDAR] = oprange[r]
+			opset(ALWAR, r0)
+			opset(ALDAR, r0)
 
 		case ASYSCALL: /* just the op; flow of control */
-			oprange[ARFI] = oprange[r]
+			opset(ARFI, r0)
 
-			oprange[ARFCI] = oprange[r]
-			oprange[ARFID] = oprange[r]
-			oprange[AHRFID] = oprange[r]
+			opset(ARFCI, r0)
+			opset(ARFID, r0)
+			opset(AHRFID, r0)
 
 		case AMOVHBR:
-			oprange[AMOVWBR] = oprange[r]
+			opset(AMOVWBR, r0)
 
 		case ASLBMFEE:
-			oprange[ASLBMFEV] = oprange[r]
+			opset(ASLBMFEV, r0)
 
 		case ATW:
-			oprange[ATD] = oprange[r]
+			opset(ATD, r0)
 
 		case ATLBIE:
-			oprange[ASLBIE] = oprange[r]
-			oprange[ATLBIEL] = oprange[r]
+			opset(ASLBIE, r0)
+			opset(ATLBIEL, r0)
 
 		case AEIEIO:
-			oprange[ASLBIA] = oprange[r]
+			opset(ASLBIA, r0)
 
 		case ACMP:
-			oprange[ACMPW] = oprange[r]
+			opset(ACMPW, r0)
 
 		case ACMPU:
-			oprange[ACMPWU] = oprange[r]
+			opset(ACMPWU, r0)
 
 		case AADD,
 			AANDCC, /* and. Rb,Rs,Ra; andi. $uimm,Rs,Ra; andis. $uimm,Rs,Ra */
@@ -2954,7 +2956,7 @@ func oprrr(ctxt *obj.Link, a int) int32 {
 		return int32(OPVCC(31, 316, 0, 1))
 	}
 
-	ctxt.Diag("bad r/r opcode %v", Aconv(a))
+	ctxt.Diag("bad r/r opcode %v", obj.Aconv(a))
 	return 0
 }
 
@@ -3076,7 +3078,7 @@ func opirr(ctxt *obj.Link, a int) int32 {
 		return int32(OPVCC(27, 0, 0, 0)) /* XORIU */
 	}
 
-	ctxt.Diag("bad opcode i/r %v", Aconv(a))
+	ctxt.Diag("bad opcode i/r %v", obj.Aconv(a))
 	return 0
 }
 
@@ -3125,7 +3127,7 @@ func opload(ctxt *obj.Link, a int) int32 {
 		return int32(OPVCC(46, 0, 0, 0)) /* lmw */
 	}
 
-	ctxt.Diag("bad load opcode %v", Aconv(a))
+	ctxt.Diag("bad load opcode %v", obj.Aconv(a))
 	return 0
 }
 
@@ -3184,7 +3186,7 @@ func oploadx(ctxt *obj.Link, a int) int32 {
 		return int32(OPVCC(31, 53, 0, 0)) /* ldux */
 	}
 
-	ctxt.Diag("bad loadx opcode %v", Aconv(a))
+	ctxt.Diag("bad loadx opcode %v", obj.Aconv(a))
 	return 0
 }
 
@@ -3234,7 +3236,7 @@ func opstore(ctxt *obj.Link, a int) int32 {
 		return int32(OPVCC(62, 0, 0, 1)) /* stdu */
 	}
 
-	ctxt.Diag("unknown store opcode %v", Aconv(a))
+	ctxt.Diag("unknown store opcode %v", obj.Aconv(a))
 	return 0
 }
 
@@ -3292,6 +3294,6 @@ func opstorex(ctxt *obj.Link, a int) int32 {
 		return int32(OPVCC(31, 181, 0, 0)) /* stdux */
 	}
 
-	ctxt.Diag("unknown storex opcode %v", Aconv(a))
+	ctxt.Diag("unknown storex opcode %v", obj.Aconv(a))
 	return 0
 }
diff --git a/src/cmd/internal/obj/ppc64/list9.go b/src/cmd/internal/obj/ppc64/list9.go
index 6c62fad7a3..f9de6f34a6 100644
--- a/src/cmd/internal/obj/ppc64/list9.go
+++ b/src/cmd/internal/obj/ppc64/list9.go
@@ -59,14 +59,14 @@ func Pconv(p *obj.Prog) string {
 	str := ""
 	if a == obj.ADATA {
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v/%d,%v",
-			p.Pc, p.Line(), Aconv(a), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(a), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
 	} else if a == obj.ATEXT || a == obj.AGLOBL {
 		if p.From3.Offset != 0 {
 			str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%d,%v",
-				p.Pc, p.Line(), Aconv(a), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
+				p.Pc, p.Line(), obj.Aconv(a), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
 		} else {
 			str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%v",
-				p.Pc, p.Line(), Aconv(a), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
+				p.Pc, p.Line(), obj.Aconv(a), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
 		}
 	} else {
 		if p.Mark&NOSCHED != 0 {
@@ -74,24 +74,24 @@ func Pconv(p *obj.Prog) string {
 		}
 		if p.Reg == 0 && p.From3.Type == obj.TYPE_NONE {
 			str += fmt.Sprintf("%.5d (%v)\t%v\t%v,%v",
-				p.Pc, p.Line(), Aconv(a), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
+				p.Pc, p.Line(), obj.Aconv(a), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
 		} else if a != obj.ATEXT && p.From.Type == obj.TYPE_MEM {
 			off := ""
 			if p.From.Offset != 0 {
 				off = fmt.Sprintf("%d", p.From.Offset)
 			}
 			str += fmt.Sprintf("%.5d (%v)\t%v\t%s(%v+%v),%v",
-				p.Pc, p.Line(), Aconv(a), off, Rconv(int(p.From.Reg)), Rconv(int(p.Reg)), obj.Dconv(p, &p.To))
+				p.Pc, p.Line(), obj.Aconv(a), off, Rconv(int(p.From.Reg)), Rconv(int(p.Reg)), obj.Dconv(p, &p.To))
 		} else if p.To.Type == obj.TYPE_MEM {
 			off := ""
 			if p.From.Offset != 0 {
 				off = fmt.Sprintf("%d", p.From.Offset)
 			}
 			str += fmt.Sprintf("%.5d (%v)\t%v\t%v,%s(%v+%v)",
-				p.Pc, p.Line(), Aconv(a), obj.Dconv(p, &p.From), off, Rconv(int(p.To.Reg)), Rconv(int(p.Reg)))
+				p.Pc, p.Line(), obj.Aconv(a), obj.Dconv(p, &p.From), off, Rconv(int(p.To.Reg)), Rconv(int(p.Reg)))
 		} else {
 			str += fmt.Sprintf("%.5d (%v)\t%v\t%v",
-				p.Pc, p.Line(), Aconv(a), obj.Dconv(p, &p.From))
+				p.Pc, p.Line(), obj.Aconv(a), obj.Dconv(p, &p.From))
 			if p.Reg != 0 {
 				str += fmt.Sprintf(",%v", Rconv(int(p.Reg)))
 			}
@@ -113,18 +113,9 @@ func Pconv(p *obj.Prog) string {
 	return fp
 }
 
-func Aconv(a int) string {
-	s := "???"
-	if a >= obj.AXXX && a < ALAST {
-		s = Anames[a]
-	}
-	var fp string
-	fp += s
-	return fp
-}
-
 func init() {
 	obj.RegisterRegister(obj.RBasePPC64, REG_DCR0+1024, Rconv)
+	obj.RegisterOpcode(obj.ABasePPC64, Anames)
 }
 
 func Rconv(r int) string {
diff --git a/src/cmd/internal/obj/util.go b/src/cmd/internal/obj/util.go
index a3c88a2b8a..d626793475 100644
--- a/src/cmd/internal/obj/util.go
+++ b/src/cmd/internal/obj/util.go
@@ -491,3 +491,68 @@ func regListConv(list int) string {
 	str += "]"
 	return str
 }
+
+/*
+	Each architecture defines an instruction (A*) space as a unique
+	integer range.
+	Global opcodes like CALL start at 0; the architecture-specific ones
+	start at a distinct, big-maskable offsets.
+	Here is the list of architectures and the base of their opcode spaces.
+*/
+
+const (
+	ABase386 = (1 + iota) << 12
+	ABaseARM
+	ABaseAMD64
+	ABasePPC64
+	AMask = 1<<12 - 1 // AND with this to use the opcode as an array index.
+)
+
+type opSet struct {
+	lo    int
+	names []string
+}
+
+// Not even worth sorting
+var aSpace []opSet
+
+// RegisterOpcode binds a list of instruction names
+// to a given instruction number range.
+func RegisterOpcode(lo int, Anames []string) {
+	aSpace = append(aSpace, opSet{lo, Anames})
+}
+
+func Aconv(a int) string {
+	if a < A_ARCHSPECIFIC {
+		return Anames[a]
+	}
+	for i := range aSpace {
+		as := &aSpace[i]
+		if as.lo <= a && a < as.lo+len(as.names) {
+			return as.names[a-as.lo]
+		}
+	}
+	return fmt.Sprintf("A???%d", a)
+}
+
+var Anames = []string{
+	"XXX",
+	"CALL",
+	"CHECKNIL",
+	"DATA",
+	"DUFFCOPY",
+	"DUFFZERO",
+	"END",
+	"FUNCDATA",
+	"GLOBL",
+	"JMP",
+	"NOP",
+	"PCDATA",
+	"RET",
+	"TEXT",
+	"TYPE",
+	"UNDEF",
+	"USEFIELD",
+	"VARDEF",
+	"VARKILL",
+}
diff --git a/src/cmd/internal/obj/x86/6.out.go b/src/cmd/internal/obj/x86/6.out.go
index 82f9291d61..45af1d65cc 100644
--- a/src/cmd/internal/obj/x86/6.out.go
+++ b/src/cmd/internal/obj/x86/6.out.go
@@ -36,7 +36,7 @@ import "cmd/internal/obj"
  *	amd64
  */
 const (
-	AAAA = obj.A_ARCHSPECIFIC + iota
+	AAAA = obj.ABaseAMD64 + obj.A_ARCHSPECIFIC + iota
 	AAAD
 	AAAM
 	AAAS
diff --git a/src/cmd/internal/obj/x86/anames6.go b/src/cmd/internal/obj/x86/anames6.go
index fca730bf9d..5839b23112 100644
--- a/src/cmd/internal/obj/x86/anames6.go
+++ b/src/cmd/internal/obj/x86/anames6.go
@@ -1,29 +1,12 @@
 package x86
 
+import "cmd/internal/obj"
+
 /*
  * this is the ranlib header
  */
 var Anames = []string{
-	"XXX",
-	"CALL",
-	"CHECKNIL",
-	"DATA",
-	"DUFFCOPY",
-	"DUFFZERO",
-	"END",
-	"FUNCDATA",
-	"GLOBL",
-	"JMP",
-	"NOP",
-	"PCDATA",
-	"RET",
-	"TEXT",
-	"TYPE",
-	"UNDEF",
-	"USEFIELD",
-	"VARDEF",
-	"VARKILL",
-	"AAA",
+	obj.A_ARCHSPECIFIC: "AAA",
 	"AAD",
 	"AAM",
 	"AAS",
diff --git a/src/cmd/internal/obj/x86/asm6.go b/src/cmd/internal/obj/x86/asm6.go
index cb7d524c63..07ae72f3f0 100644
--- a/src/cmd/internal/obj/x86/asm6.go
+++ b/src/cmd/internal/obj/x86/asm6.go
@@ -1435,7 +1435,7 @@ var optab =
 	Optab{0, nil, 0, [23]uint8{}},
 }
 
-var opindex [ALAST + 1]*Optab
+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.
@@ -1708,10 +1708,10 @@ func instinit() {
 
 	for i := 1; optab[i].as != 0; i++ {
 		c = int(optab[i].as)
-		if opindex[c] != nil {
-			log.Fatalf("phase error in optab: %d (%v)", i, Aconv(c))
+		if opindex[c&obj.AMask] != nil {
+			log.Fatalf("phase error in optab: %d (%v)", i, obj.Aconv(c))
 		}
-		opindex[c] = &optab[i]
+		opindex[c&obj.AMask] = &optab[i]
 	}
 
 	for i := 0; i < Ymax; i++ {
@@ -2758,7 +2758,7 @@ func mediaop(ctxt *obj.Link, o *Optab, op int, osize int, z int) int {
 func doasm(ctxt *obj.Link, p *obj.Prog) {
 	ctxt.Curp = p // TODO
 
-	o := opindex[p.As]
+	o := opindex[p.As&obj.AMask]
 
 	if o == nil {
 		ctxt.Diag("asmins: missing op %v", p)
diff --git a/src/cmd/internal/obj/x86/list6.go b/src/cmd/internal/obj/x86/list6.go
index b2a7a7a24a..6b7d65cbae 100644
--- a/src/cmd/internal/obj/x86/list6.go
+++ b/src/cmd/internal/obj/x86/list6.go
@@ -59,21 +59,21 @@ func Pconv(p *obj.Prog) string {
 	switch p.As {
 	case obj.ADATA:
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v/%d,%v",
-			p.Pc, p.Line(), Aconv(int(p.As)), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(int(p.As)), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
 
 	case obj.ATEXT:
 		if p.From3.Offset != 0 {
 			str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%d,%v",
-				p.Pc, p.Line(), Aconv(int(p.As)), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
+				p.Pc, p.Line(), obj.Aconv(int(p.As)), obj.Dconv(p, &p.From), p.From3.Offset, obj.Dconv(p, &p.To))
 			break
 		}
 
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%v",
-			p.Pc, p.Line(), Aconv(int(p.As)), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(int(p.As)), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
 
 	default:
 		str = fmt.Sprintf("%.5d (%v)\t%v\t%v,%v",
-			p.Pc, p.Line(), Aconv(int(p.As)), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
+			p.Pc, p.Line(), obj.Aconv(int(p.As)), obj.Dconv(p, &p.From), obj.Dconv(p, &p.To))
 
 		// TODO(rsc): This special case is for SHRQ $32, AX:DX, which encodes as
 		//	SHRQ $32(DX*0), AX
@@ -88,10 +88,6 @@ func Pconv(p *obj.Prog) string {
 	return fp
 }
 
-func Aconv(i int) string {
-	return Anames[i]
-}
-
 var Register = []string{
 	"AL", /* [D_AL] */
 	"CL",
@@ -210,6 +206,7 @@ var Register = []string{
 
 func init() {
 	obj.RegisterRegister(REG_AL, REG_AL+len(Register), Rconv)
+	obj.RegisterOpcode(obj.ABaseAMD64, Anames)
 }
 
 func Rconv(r int) string {
diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index 434a120bd6..2b1c3a2cc1 100644
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -895,7 +895,7 @@ func pushpop(a int) bool {
 	return false
 }
 
-func relinv(a int) int {
+func relinv(a int16) int16 {
 	switch a {
 	case AJEQ:
 		return AJNE
@@ -931,7 +931,7 @@ func relinv(a int) int {
 		return AJOS
 	}
 
-	log.Fatalf("unknown relation: %s", Anames[a])
+	log.Fatalf("unknown relation: %s", obj.Aconv(int(a)))
 	return 0
 }
 
@@ -1001,7 +1001,7 @@ loop:
 					continue
 				}
 
-				q.As = int16(relinv(int(q.As)))
+				q.As = relinv(q.As)
 				p = q.Pcond
 				q.Pcond = q.Link
 				q.Link = p
@@ -1054,7 +1054,7 @@ loop:
 				 * expect conditional jump to be taken.
 				 * rewrite so that's the fall-through case.
 				 */
-				p.As = int16(relinv(a))
+				p.As = relinv(int16(a))
 
 				q = p.Link
 				p.Link = p.Pcond
@@ -1064,7 +1064,7 @@ loop:
 			q = p.Link
 			if q.Mark != 0 {
 				if a != ALOOP {
-					p.As = int16(relinv(a))
+					p.As = relinv(int16(a))
 					p.Link = p.Pcond
 					p.Pcond = q
 				}