cmd/internal/obj/loong64: add {V,XV}DIV{B/H/W/V}[U] and {V,XV}MOD{B/H/W/V}[U] instructions support

Go asm syntax:
	 VDIV{B/H/W/V}[U]	VK, VJ, VD
	XVDIV{B/H/W/V}[U]	XK, XJ, XD
	 VMOD{B/H/W/V}[U]	VK, VJ, VD
	XVMOD{B/H/W/V}[U]	XK, XJ, XD

Equivalent platform assembler syntax:
	 vdiv.{b/h/w/d}[u]	vd, vj, vk
	xvdiv.{b/h/w/d}[u]	xd, xj, xk
	 vmod.{b/h/w/d}[u]	vd, vj, vk
	xvmod.{b/h/w/d}[u]	xd, xj, xk

Change-Id: I3676721c3c415de0f2ebbd480ecd1b2400a28dba
Reviewed-on: https://go-review.googlesource.com/c/go/+/636376
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/asm/internal/asm/testdata/loong64enc1.s

@@ -801,3 +801,37 @@ lable2:
 	XVMUHHU		X3, X2, X1	// 418c8874
 	XVMUHWU		X3, X2, X1	// 410c8974
 	XVMUHVU		X3, X2, X1	// 418c8974
+
+	// [X]VDIV{B/H/W/V}[U] and [X]VMOD{B/H/W/V}[U] instructions
+	VDIVB		V1, V2, V3	// 4304e070
+	VDIVH		V1, V2, V3	// 4384e070
+	VDIVW		V1, V2, V3	// 4304e170
+	VDIVV		V1, V2, V3	// 4384e170
+	VDIVBU		V1, V2, V3	// 4304e470
+	VDIVHU		V1, V2, V3	// 4384e470
+	VDIVWU		V1, V2, V3	// 4304e570
+	VDIVVU		V1, V2, V3	// 4384e570
+	VMODB		V1, V2, V3	// 4304e270
+	VMODH		V1, V2, V3	// 4384e270
+	VMODW		V1, V2, V3	// 4304e370
+	VMODV		V1, V2, V3	// 4384e370
+	VMODBU		V1, V2, V3	// 4304e670
+	VMODHU		V1, V2, V3	// 4384e670
+	VMODWU		V1, V2, V3	// 4304e770
+	VMODVU		V1, V2, V3	// 4384e770
+	XVDIVB		X3, X2, X1	// 410ce074
+	XVDIVH		X3, X2, X1	// 418ce074
+	XVDIVW		X3, X2, X1	// 410ce174
+	XVDIVV		X3, X2, X1	// 418ce174
+	XVDIVBU		X3, X2, X1	// 410ce474
+	XVDIVHU		X3, X2, X1	// 418ce474
+	XVDIVWU		X3, X2, X1	// 410ce574
+	XVDIVVU		X3, X2, X1	// 418ce574
+	XVMODB		X3, X2, X1	// 410ce274
+	XVMODH		X3, X2, X1	// 418ce274
+	XVMODW		X3, X2, X1	// 410ce374
+	XVMODV		X3, X2, X1	// 418ce374
+	XVMODBU		X3, X2, X1	// 410ce674
+	XVMODHU		X3, X2, X1	// 418ce674
+	XVMODWU		X3, X2, X1	// 410ce774
+	XVMODVU		X3, X2, X1	// 418ce774

src/cmd/internal/obj/loong64/a.out.go

@@ -824,6 +824,40 @@ const (
 	AVSEQV
 	AXVSEQV
 
+	// LSX and LASX integer div and mod instructions
+	AVDIVB
+	AVDIVH
+	AVDIVW
+	AVDIVV
+	AVDIVBU
+	AVDIVHU
+	AVDIVWU
+	AVDIVVU
+	AVMODB
+	AVMODH
+	AVMODW
+	AVMODV
+	AVMODBU
+	AVMODHU
+	AVMODWU
+	AVMODVU
+	AXVDIVB
+	AXVDIVH
+	AXVDIVW
+	AXVDIVV
+	AXVDIVBU
+	AXVDIVHU
+	AXVDIVWU
+	AXVDIVVU
+	AXVMODB
+	AXVMODH
+	AXVMODW
+	AXVMODV
+	AXVMODBU
+	AXVMODHU
+	AXVMODWU
+	AXVMODVU
+
 	// LSX and LASX shift operation instructions
 	AVSLLB
 	AVSLLH

src/cmd/internal/obj/loong64/anames.go

@@ -333,6 +333,38 @@ var Anames = []string{
 	"XVSEQW",
 	"VSEQV",
 	"XVSEQV",
+	"VDIVB",
+	"VDIVH",
+	"VDIVW",
+	"VDIVV",
+	"VDIVBU",
+	"VDIVHU",
+	"VDIVWU",
+	"VDIVVU",
+	"VMODB",
+	"VMODH",
+	"VMODW",
+	"VMODV",
+	"VMODBU",
+	"VMODHU",
+	"VMODWU",
+	"VMODVU",
+	"XVDIVB",
+	"XVDIVH",
+	"XVDIVW",
+	"XVDIVV",
+	"XVDIVBU",
+	"XVDIVHU",
+	"XVDIVWU",
+	"XVDIVVU",
+	"XVMODB",
+	"XVMODH",
+	"XVMODW",
+	"XVMODV",
+	"XVMODBU",
+	"XVMODHU",
+	"XVMODWU",
+	"XVMODVU",
 	"VSLLB",
 	"VSLLH",
 	"VSLLW",

src/cmd/internal/obj/loong64/asm.go

@@ -1567,6 +1567,22 @@ func buildop(ctxt *obj.Link) {
 			opset(AVMUHHU, r0)
 			opset(AVMUHWU, r0)
 			opset(AVMUHVU, r0)
+			opset(AVDIVB, r0)
+			opset(AVDIVH, r0)
+			opset(AVDIVW, r0)
+			opset(AVDIVV, r0)
+			opset(AVMODB, r0)
+			opset(AVMODH, r0)
+			opset(AVMODW, r0)
+			opset(AVMODV, r0)
+			opset(AVDIVBU, r0)
+			opset(AVDIVHU, r0)
+			opset(AVDIVWU, r0)
+			opset(AVDIVVU, r0)
+			opset(AVMODBU, r0)
+			opset(AVMODHU, r0)
+			opset(AVMODWU, r0)
+			opset(AVMODVU, r0)
 
 		case AXVSEQB:
 			opset(AXVSEQH, r0)
@@ -1592,6 +1608,22 @@ func buildop(ctxt *obj.Link) {
 			opset(AXVMUHHU, r0)
 			opset(AXVMUHWU, r0)
 			opset(AXVMUHVU, r0)
+			opset(AXVDIVB, r0)
+			opset(AXVDIVH, r0)
+			opset(AXVDIVW, r0)
+			opset(AXVDIVV, r0)
+			opset(AXVMODB, r0)
+			opset(AXVMODH, r0)
+			opset(AXVMODW, r0)
+			opset(AXVMODV, r0)
+			opset(AXVDIVBU, r0)
+			opset(AXVDIVHU, r0)
+			opset(AXVDIVWU, r0)
+			opset(AXVDIVVU, r0)
+			opset(AXVMODBU, r0)
+			opset(AXVMODHU, r0)
+			opset(AXVMODWU, r0)
+			opset(AXVMODVU, r0)
 
 		case AVANDB:
 			opset(AVORB, r0)
@@ -2874,6 +2906,70 @@ func (c *ctxt0) oprrr(a obj.As) uint32 {
 		return 0x0EA50 << 15 // xvandn.v
 	case AXVORNV:
 		return 0x0EA51 << 15 // xvorn.v
+	case AVDIVB:
+		return 0xe1c0 << 15 // vdiv.b
+	case AVDIVH:
+		return 0xe1c1 << 15 // vdiv.h
+	case AVDIVW:
+		return 0xe1c2 << 15 // vdiv.w
+	case AVDIVV:
+		return 0xe1c3 << 15 // vdiv.d
+	case AVMODB:
+		return 0xe1c4 << 15 // vmod.b
+	case AVMODH:
+		return 0xe1c5 << 15 // vmod.h
+	case AVMODW:
+		return 0xe1c6 << 15 // vmod.w
+	case AVMODV:
+		return 0xe1c7 << 15 // vmod.d
+	case AVDIVBU:
+		return 0xe1c8 << 15 // vdiv.bu
+	case AVDIVHU:
+		return 0xe1c9 << 15 // vdiv.hu
+	case AVDIVWU:
+		return 0xe1ca << 15 // vdiv.wu
+	case AVDIVVU:
+		return 0xe1cb << 15 // vdiv.du
+	case AVMODBU:
+		return 0xe1cc << 15 // vmod.bu
+	case AVMODHU:
+		return 0xe1cd << 15 // vmod.hu
+	case AVMODWU:
+		return 0xe1ce << 15 // vmod.wu
+	case AVMODVU:
+		return 0xe1cf << 15 // vmod.du
+	case AXVDIVB:
+		return 0xe9c0 << 15 // xvdiv.b
+	case AXVDIVH:
+		return 0xe9c1 << 15 // xvdiv.h
+	case AXVDIVW:
+		return 0xe9c2 << 15 // xvdiv.w
+	case AXVDIVV:
+		return 0xe9c3 << 15 // xvdiv.d
+	case AXVMODB:
+		return 0xe9c4 << 15 // xvmod.b
+	case AXVMODH:
+		return 0xe9c5 << 15 // xvmod.h
+	case AXVMODW:
+		return 0xe9c6 << 15 // xvmod.w
+	case AXVMODV:
+		return 0xe9c7 << 15 // xvmod.d
+	case AXVDIVBU:
+		return 0xe9c8 << 15 // xvdiv.bu
+	case AXVDIVHU:
+		return 0xe9c9 << 15 // xvdiv.hu
+	case AXVDIVWU:
+		return 0xe9ca << 15 // xvdiv.wu
+	case AXVDIVVU:
+		return 0xe9cb << 15 // xvdiv.du
+	case AXVMODBU:
+		return 0xe9cc << 15 // xvmod.bu
+	case AXVMODHU:
+		return 0xe9cd << 15 // xvmod.hu
+	case AXVMODWU:
+		return 0xe9ce << 15 // xvmod.wu
+	case AXVMODVU:
+		return 0xe9cf << 15 // xvmod.du
 	case AVSLLB:
 		return 0xe1d0 << 15 // vsll.b
 	case AVSLLH: