cmd/asm: add VSRI instruction on ARM64

This change provides VSRI instruction for ChaCha20Poly1305 implementation.

Change-Id: Ifee727b6f3982b629b44a67cac5bbe87ca59027b
Reviewed-on: https://go-review.googlesource.com/109342
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/asm/internal/asm/testdata/arm64.s

@@ -100,6 +100,13 @@ TEXT	foo(SB), DUPOK|NOSPLIT, $-8
 	VSHL	$8, V1.H8, V2.H8                // 2254184f
 	VSHL	$2, V1.B8, V2.B8                // 22540a0f
 	VSHL	$2, V1.B16, V2.B16              // 22540a4f
+	VSRI	$56, V1.D2, V2.D2               // 2244486f
+	VSRI	$24, V1.S4, V2.S4               // 2244286f
+	VSRI	$24, V1.S2, V2.S2               // 2244282f
+	VSRI	$8, V1.H4, V2.H4                // 2244182f
+	VSRI	$8, V1.H8, V2.H8                // 2244186f
+	VSRI	$2, V1.B8, V2.B8                // 22440e2f
+	VSRI	$2, V1.B16, V2.B16              // 22440e6f
 	MOVD	(R2)(R6.SXTW), R4               // 44c866f8
 	MOVD	(R3)(R6), R5                    // MOVD	(R3)(R6*1), R5                  // 656866f8
 	MOVD	(R2)(R6), R4                    // MOVD	(R2)(R6*1), R4                  // 446866f8

src/cmd/internal/obj/arm64/a.out.go

@@ -897,6 +897,7 @@ const (
 	AVRBIT
 	AVUSHR
 	AVSHL
+	AVSRI
 	ALAST
 	AB  = obj.AJMP
 	ABL = obj.ACALL

src/cmd/internal/obj/arm64/anames.go

@@ -399,5 +399,6 @@ var Anames = []string{
 	"VRBIT",
 	"VUSHR",
 	"VSHL",
+	"VSRI",
 	"LAST",
 }

src/cmd/internal/obj/arm64/asm7.go

@@ -2386,6 +2386,7 @@ func buildop(ctxt *obj.Link) {
 
 		case AVUSHR:
 			oprangeset(AVSHL, t)
+			oprangeset(AVSRI, t)
 
 		case AVREV32:
 			oprangeset(AVRBIT, t)
@@ -4319,18 +4320,19 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 
 		imm := 0
 
-		if p.As == AVUSHR {
+		switch p.As {
+		case AVUSHR, AVSRI:
 			imm = esize*2 - shift
 			if imm < esize || imm > imax {
 				c.ctxt.Diag("shift out of range: %v", p)
 			}
-		}
-
-		if p.As == AVSHL {
+		case AVSHL:
 			imm = esize + shift
 			if imm > imax {
 				c.ctxt.Diag("shift out of range: %v", p)
 			}
+		default:
+			c.ctxt.Diag("invalid instruction %v\n", p)
 		}
 
 		o1 = c.opirr(p, p.As)
@@ -5310,6 +5312,9 @@ func (c *ctxt7) opirr(p *obj.Prog, a obj.As) uint32 {
 
 	case AVSHL:
 		return 0x1E<<23 | 21<<10
+
+	case AVSRI:
+		return 0x5E<<23 | 17<<10
 	}
 
 	c.ctxt.Diag("%v: bad irr %v", p, a)