cmd/internal/obj/s390x: fix m6 field encoding for VSTRC instruction on s390x

M6 field for all extended mnemonics of VSTRC set to zero
This fixes VSTRC codegen to emit correctly  and added testcases for all
the extended mnemonics.

Fixes #69216

Change-Id: I2a1b7fb61d6bd6444286eab56a506225c90b75e7
Reviewed-on: https://go-review.googlesource.com/c/go/+/612315
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
Reviewed-by: Vishwanatha HD <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>

Author: srinivas-pokala

src/cmd/asm/internal/asm/testdata/s390x.s

@@ -520,7 +520,20 @@ TEXT main·foo(SB),DUPOK|NOSPLIT,$16-0 // TEXT main.foo(SB), DUPOK|NOSPLIT, $16-
 	VSUMQF	V4, V5, V6              // e76450002067
 	VSUMQG	V19, V20, V21           // e75340003e67
 	VSUMB	V7, V8, V9              // e79780000064
-	VSUMH	V22, V23, V24           // e78670001e64
+	VSUMH	V22, V23, V24		// e78670001e64
+	VSTRC	V18, V20, V22, V24	// e78240006f8a
+	VSTRCB	V18, V20, V22, V24	// e78240006f8a
+	VSTRCH	V18, V20, V22, V24	// e78241006f8a
+	VSTRCF	V18, V20, V22, V24	// e78242006f8a
+	VSTRCBS V18, V20, V22, V24	// e78240106f8a
+	VSTRCHS V18, V20, V22, V24	// e78241106f8a
+	VSTRCFS V18, V20, V22, V24	// e78242106f8a
+	VSTRCZB V18, V20, V22, V24	// e78240206f8a
+	VSTRCZH V18, V20, V22, V24	// e78241206f8a
+	VSTRCZF V18, V20, V22, V24	// e78242206f8a
+	VSTRCZBS V18, V20, V22, V24	// e78240306f8a
+	VSTRCZHS V18, V20, V22, V24	// e78241306f8a
+	VSTRCZFS V18, V20, V22, V24	// e78242306f8a
 
 	RET
 	RET	foo(SB)

src/cmd/internal/obj/s390x/asmz.go

@@ -1450,6 +1450,7 @@ func buildop(ctxt *obj.Link) {
 			opset(AVMALOB, r)
 			opset(AVMALOH, r)
 			opset(AVMALOF, r)
+			opset(AVSTRC, r)
 			opset(AVSTRCB, r)
 			opset(AVSTRCH, r)
 			opset(AVSTRCF, r)
@@ -4346,8 +4347,7 @@ func (c *ctxtz) asmout(p *obj.Prog, asm *[]byte) {
 		zVRRc(op, uint32(p.To.Reg), uint32(v2), uint32(p.From.Reg), m6, m5, m4, asm)
 
 	case 120: // VRR-d
-		op, m6, _ := vop(p.As)
-		m5 := singleElementMask(p.As)
+		op, m6, m5 := vop(p.As)
 		v1 := uint32(p.To.Reg)
 		v2 := uint32(p.From.Reg)
 		v3 := uint32(p.Reg)

src/cmd/internal/obj/s390x/vector.go

@@ -45,8 +45,14 @@ func vop(as obj.As) (opcode, es, cs uint32) {
 		return op_VAC, 0, 0
 	case AVACQ:
 		return op_VAC, 4, 0
-	case AVMSLG, AVMSLEG, AVMSLOG, AVMSLEOG:
+	case AVMSLG:
 		return op_VMSL, 3, 0
+	case AVMSLEG:
+		return op_VMSL, 3, 8
+	case AVMSLOG:
+		return op_VMSL, 3, 4
+	case AVMSLEOG:
+		return op_VMSL, 3, 12
 	case AVACCC:
 		return op_VACCC, 0, 0
 	case AVACCCQ:
@@ -1058,12 +1064,6 @@ func singleElementMask(as obj.As) uint32 {
 		AWFTCIDB,
 		AWFIDB:
 		return 8
-	case AVMSLEG:
-		return 8
-	case AVMSLOG:
-		return 4
-	case AVMSLEOG:
-		return 12
 	}
 	return 0
 }