cmd/internal/obj: remove ACHECKNIL

Updates #16357.

Change-Id: I35f938d675ca5c31f65c4419ee0732bbc593b5cb
Reviewed-on: https://go-review.googlesource.com/29368
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/amd64/prog.go

@@ -29,7 +29,6 @@ var progtable = [x86.ALAST & obj.AMask]obj.ProgInfo{
 	obj.APCDATA:   {Flags: gc.Pseudo},
 	obj.AUNDEF:    {Flags: gc.Break},
 	obj.AUSEFIELD: {Flags: gc.OK},
-	obj.ACHECKNIL: {Flags: gc.LeftRead},
 	obj.AVARDEF:   {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARKILL:  {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARLIVE:  {Flags: gc.Pseudo | gc.LeftRead},

src/cmd/compile/internal/arm/prog.go

@@ -28,7 +28,6 @@ var progtable = [arm.ALAST & obj.AMask]obj.ProgInfo{
 	obj.APCDATA:   {Flags: gc.Pseudo},
 	obj.AUNDEF:    {Flags: gc.Break},
 	obj.AUSEFIELD: {Flags: gc.OK},
-	obj.ACHECKNIL: {Flags: gc.LeftRead},
 	obj.AVARDEF:   {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARKILL:  {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARLIVE:  {Flags: gc.Pseudo | gc.LeftRead},

src/cmd/compile/internal/arm64/prog.go

@@ -31,7 +31,6 @@ var progtable = [arm64.ALAST & obj.AMask]obj.ProgInfo{
 	obj.APCDATA:   {Flags: gc.Pseudo},
 	obj.AUNDEF:    {Flags: gc.Break},
 	obj.AUSEFIELD: {Flags: gc.OK},
-	obj.ACHECKNIL: {Flags: gc.LeftRead},
 	obj.AVARDEF:   {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARKILL:  {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARLIVE:  {Flags: gc.Pseudo | gc.LeftRead},

src/cmd/compile/internal/mips64/prog.go

@@ -31,7 +31,6 @@ var progtable = [mips.ALAST & obj.AMask]obj.ProgInfo{
 	obj.APCDATA:   {Flags: gc.Pseudo},
 	obj.AUNDEF:    {Flags: gc.Break},
 	obj.AUSEFIELD: {Flags: gc.OK},
-	obj.ACHECKNIL: {Flags: gc.LeftRead},
 	obj.AVARDEF:   {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARKILL:  {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARLIVE:  {Flags: gc.Pseudo | gc.LeftRead},

src/cmd/compile/internal/ppc64/prog.go

@@ -31,7 +31,6 @@ var progtable = [ppc64.ALAST & obj.AMask]obj.ProgInfo{
 	obj.APCDATA:   {Flags: gc.Pseudo},
 	obj.AUNDEF:    {Flags: gc.Break},
 	obj.AUSEFIELD: {Flags: gc.OK},
-	obj.ACHECKNIL: {Flags: gc.LeftRead},
 	obj.AVARDEF:   {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARKILL:  {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARLIVE:  {Flags: gc.Pseudo | gc.LeftRead},

src/cmd/compile/internal/s390x/prog.go

@@ -24,7 +24,6 @@ var progtable = [s390x.ALAST & obj.AMask]obj.ProgInfo{
 	obj.APCDATA & obj.AMask:   {Flags: gc.Pseudo},
 	obj.AUNDEF & obj.AMask:    {Flags: gc.Break},
 	obj.AUSEFIELD & obj.AMask: {Flags: gc.OK},
-	obj.ACHECKNIL & obj.AMask: {Flags: gc.LeftRead},
 	obj.AVARDEF & obj.AMask:   {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARKILL & obj.AMask:  {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARLIVE & obj.AMask:  {Flags: gc.Pseudo | gc.LeftRead},

src/cmd/compile/internal/x86/prog.go

@@ -37,7 +37,6 @@ var progtable = [x86.ALAST & obj.AMask]obj.ProgInfo{
 	obj.APCDATA:   {Flags: gc.Pseudo},
 	obj.AUNDEF:    {Flags: gc.Break},
 	obj.AUSEFIELD: {Flags: gc.OK},
-	obj.ACHECKNIL: {Flags: gc.LeftRead},
 	obj.AVARDEF:   {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARKILL:  {Flags: gc.Pseudo | gc.RightWrite},
 	obj.AVARLIVE:  {Flags: gc.Pseudo | gc.LeftRead},

src/cmd/internal/obj/link.go

@@ -271,7 +271,6 @@ type As int16
 const (
 	AXXX As = iota
 	ACALL
-	ACHECKNIL
 	ADUFFCOPY
 	ADUFFZERO
 	AEND

src/cmd/internal/obj/util.go

@@ -472,7 +472,6 @@ func (a As) String() string {
 var Anames = []string{
 	"XXX",
 	"CALL",
-	"CHECKNIL",
 	"DUFFCOPY",
 	"DUFFZERO",
 	"END",

src/cmd/internal/obj/x86/asm6.go

@@ -1742,7 +1742,6 @@ var optab =
 	{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}},