cmd/internal/obj/x86: add ADDSUBPS/PD

These are the last instructions missing to complete SSE3 support.

For reference what was missing was found by a tool [1]:

$ x86db-gogen list --extension SSE3 --not-known
ADDSUBPD xmmreg,xmmrm [rm: 66 0f d0 /r] PRESCOTT,SSE3,SO
ADDSUBPS xmmreg,xmmrm [rm: f2 0f d0 /r] PRESCOTT,SSE3,SO

[1] https://github.com/dlespiau/x86db

Fixes #20293

Change-Id: Ib5a91bf64dcc5282cdb60eae740ae52b4db16ebd
Reviewed-on: https://go-review.googlesource.com/42990
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>

src/cmd/asm/internal/asm/testdata/amd64enc.s

@@ -212,22 +212,22 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$0
 	ADDSS (R11), X11                        // f3450f581b
 	ADDSS X2, X11                           // f3440f58da
 	ADDSS X11, X11                          // f3450f58db
-	//TODO: ADDSUBPD (BX), X2               // 660fd013
-	//TODO: ADDSUBPD (R11), X2              // 66410fd013
-	//TODO: ADDSUBPD X2, X2                 // 660fd0d2
-	//TODO: ADDSUBPD X11, X2                // 66410fd0d3
-	//TODO: ADDSUBPD (BX), X11              // 66440fd01b
-	//TODO: ADDSUBPD (R11), X11             // 66450fd01b
-	//TODO: ADDSUBPD X2, X11                // 66440fd0da
-	//TODO: ADDSUBPD X11, X11               // 66450fd0db
-	//TODO: ADDSUBPS (BX), X2               // f20fd013
-	//TODO: ADDSUBPS (R11), X2              // f2410fd013
-	//TODO: ADDSUBPS X2, X2                 // f20fd0d2
-	//TODO: ADDSUBPS X11, X2                // f2410fd0d3
-	//TODO: ADDSUBPS (BX), X11              // f2440fd01b
-	//TODO: ADDSUBPS (R11), X11             // f2450fd01b
-	//TODO: ADDSUBPS X2, X11                // f2440fd0da
-	//TODO: ADDSUBPS X11, X11               // f2450fd0db
+	ADDSUBPD (BX), X2                       // 660fd013
+	ADDSUBPD (R11), X2                      // 66410fd013
+	ADDSUBPD X2, X2                         // 660fd0d2
+	ADDSUBPD X11, X2                        // 66410fd0d3
+	ADDSUBPD (BX), X11                      // 66440fd01b
+	ADDSUBPD (R11), X11                     // 66450fd01b
+	ADDSUBPD X2, X11                        // 66440fd0da
+	ADDSUBPD X11, X11                       // 66450fd0db
+	ADDSUBPS (BX), X2                       // f20fd013
+	ADDSUBPS (R11), X2                      // f2410fd013
+	ADDSUBPS X2, X2                         // f20fd0d2
+	ADDSUBPS X11, X2                        // f2410fd0d3
+	ADDSUBPS (BX), X11                      // f2440fd01b
+	ADDSUBPS (R11), X11                     // f2450fd01b
+	ADDSUBPS X2, X11                        // f2440fd0da
+	ADDSUBPS X11, X11                       // f2450fd0db
 	//TODO: ADOXL (BX), DX                  // f30f38f613
 	//TODO: ADOXL (R11), DX                 // f3410f38f613
 	//TODO: ADOXL DX, DX                    // f30f38f6d2

src/cmd/internal/obj/x86/a.out.go

@@ -524,6 +524,8 @@ const (
 	AADDPS
 	AADDSD
 	AADDSS
+	AADDSUBPD
+	AADDSUBPS
 	AANDNL
 	AANDNQ
 	AANDNPD

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

@@ -467,6 +467,8 @@ var Anames = []string{
 	"ADDPS",
 	"ADDSD",
 	"ADDSS",
+	"ADDSUBPD",
+	"ADDSUBPS",
 	"ANDNL",
 	"ANDNQ",
 	"ANDNPD",

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

@@ -969,6 +969,8 @@ var optab =
 	{AADDQ, yaddl, Pw, [23]uint8{0x83, 00, 0x05, 0x81, 00, 0x01, 0x03}},
 	{AADDSD, yxm, Pf2, [23]uint8{0x58}},
 	{AADDSS, yxm, Pf3, [23]uint8{0x58}},
+	{AADDSUBPD, yxm, Pq, [23]uint8{0xd0}},
+	{AADDSUBPS, yxm, Pf2, [23]uint8{0xd0}},
 	{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}},