cmd/internal/obj: refactor arm64 ASIMD instruction encoding

Refactor arm64 ASIMD opcodes to use common helper routines named
after their instruction classes from the arm64 XML specification.

Add helper routines like ASIMDSAME for instructions with encoding
class "asimdsame" in arm64 encodingindex.xml. Helper arguments
follow the bitfield order in the speficication tables.

For example, the CMEQ instruction entry:

  <tr class="instructiontable" encname="CMEQ_asimdsame_only"...>
     <td bitwidth="1" class="bitfield">1</td>
     <td bitwidth="2" class="bitfield"></td>
     <td bitwidth="5" class="bitfield">10001</td>
     <td class="iformname" iformid="CMEQ_advsimd_reg">CMEQ (register)</td>
     <td class="enctags">Vector</td>
  </tr>

Now corresponds to ASIMDSAME(1, 0, 0x11), where each argument
matches the correspoding bitfield value in the table.

Change-Id: I024f3eba552906a865841bc1a296f14e3fca73f5
Reviewed-on: https://go-review.googlesource.com/c/go/+/719280
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

1 files changed, 68 insertions, 44 deletions

diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index d8d63b19ba..2c35734f26 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/src/cmd/internal/obj/arm64/asm7.go
@@ -281,6 +281,30 @@ func MOVCONST(d int64, s int, rt int) uint32 {
 	return uint32(((d>>uint(s*16))&0xFFFF)<<5) | uint32(s)&3<<21 | uint32(rt&31)
 }
 
+func ASIMDALL(u, size, opcode uint32) uint32 {
+	return u<<29 | 0x7<<25 | size<<22 | 3<<20 | opcode<<12 | 1<<11
+}
+
+func ASIMDDIFF(u, opcode uint32) uint32 {
+	return u<<29 | 0x7<<25 | 1<<21 | opcode<<12
+}
+
+func ASIMDMISC(u, size, opcode uint32) uint32 {
+	return u<<29 | 0x7<<25 | size<<22 | 1<<21 | opcode<<12 | 1<<11
+}
+
+func ASIMDPERM(opcode uint32) uint32 {
+	return 0x7<<25 | opcode<<12 | 1<<11
+}
+
+func ASIMDSAME(u, size, opcode uint32) uint32 {
+	return u<<29 | 0x7<<25 | size<<22 | 1<<21 | opcode<<11 | 1<<10
+}
+
+func ASIMDSHF(u, opcode uint32) uint32 {
+	return u<<29 | 0xF<<24 | opcode<<11 | 1<<10
+}
+
 const (
 	// Optab.flag
 	LFROM        = 1 << iota // p.From uses constant pool
@@ -5664,8 +5688,11 @@ func (c *ctxt7) asmout(p *obj.Prog, out []uint32) (count int) {
 			af = uint8((p.From.Reg >> 5) & 15)
 			shift = 0
 		}
+		var Q uint32
+		if p.As == AVUXTL2 || p.As == AVUSHLL2 {
+			Q = 1
+		}
 
-		Q := (o1 >> 30) & 1
 		var immh, width uint8
 		switch pack(Q, af, at) {
 		case pack(0, ARNG_8B, ARNG_8H):
@@ -5686,7 +5713,7 @@ func (c *ctxt7) asmout(p *obj.Prog, out []uint32) (count int) {
 		if !(0 <= shift && shift <= int(width-1)) {
 			c.ctxt.Diag("shift amount out of range: %v\n", p)
 		}
-		o1 |= uint32(immh)<<19 | uint32(shift)<<16 | uint32(rf&31)<<5 | uint32(p.To.Reg&31)
+		o1 |= Q<<30 | uint32(immh)<<19 | uint32(shift)<<16 | uint32(rf&31)<<5 | uint32(p.To.Reg&31)
 
 	case 103: /* VEOR3/VBCAX Va.B16, Vm.B16, Vn.B16, Vd.B16 */
 		ta := (p.From.Reg >> 5) & 15
@@ -6424,73 +6451,73 @@ func (c *ctxt7) oprrr(p *obj.Prog, a obj.As, rd, rn, rm int16) uint32 {
 		op = FPOP1S(0, 0, 3, 5)
 
 	case AVADD:
-		op = 7<<25 | 1<<21 | 1<<15 | 1<<10
+		op = ASIMDSAME(0, 0, 0x10)
 
 	case AVSUB:
-		op = 0x17<<25 | 1<<21 | 1<<15 | 1<<10
+		op = ASIMDSAME(1, 0, 0x10)
 
 	case AVADDP:
-		op = 7<<25 | 1<<21 | 1<<15 | 15<<10
+		op = ASIMDSAME(0, 0, 0x17)
 
 	case AVAND:
-		op = 7<<25 | 1<<21 | 7<<10
+		op = ASIMDSAME(0, 0, 0x03)
 
 	case AVBCAX:
 		op = 0xCE<<24 | 1<<21
 
 	case AVCMEQ:
-		op = 1<<29 | 0x71<<21 | 0x23<<10
+		op = ASIMDSAME(1, 0, 0x11)
 
 	case AVCNT:
-		op = 0xE<<24 | 0x10<<17 | 5<<12 | 2<<10
+		op = ASIMDMISC(0, 0, 0x05)
 
 	case AVZIP1:
-		op = 0xE<<24 | 3<<12 | 2<<10
+		op = ASIMDPERM(0x3)
 
 	case AVZIP2:
-		op = 0xE<<24 | 1<<14 | 3<<12 | 2<<10
+		op = ASIMDPERM(0x7)
 
 	case AVEOR:
-		op = 1<<29 | 0x71<<21 | 7<<10
+		op = ASIMDSAME(1, 0, 0x03)
 
 	case AVEOR3:
 		op = 0xCE << 24
 
 	case AVORR:
-		op = 7<<25 | 5<<21 | 7<<10
-
-	case AVREV16:
-		op = 3<<26 | 2<<24 | 1<<21 | 3<<11
+		op = ASIMDSAME(0, 2, 0x03)
 
 	case AVRAX1:
 		op = 0xCE<<24 | 3<<21 | 1<<15 | 3<<10
 
+	case AVREV16:
+		op = ASIMDMISC(0, 0, 0x01)
+
 	case AVREV32:
-		op = 11<<26 | 2<<24 | 1<<21 | 1<<11
+		op = ASIMDMISC(1, 0, 0x00)
 
 	case AVREV64:
-		op = 3<<26 | 2<<24 | 1<<21 | 1<<11
+		op = ASIMDMISC(0, 0, 0x00)
 
 	case AVMOV:
 		op = 7<<25 | 5<<21 | 7<<10
 
 	case AVADDV:
-		op = 7<<25 | 3<<20 | 3<<15 | 7<<11
+		op = ASIMDALL(0, 0, 0x1B)
 
 	case AVUADDLV:
-		op = 1<<29 | 7<<25 | 3<<20 | 7<<11
+		op = ASIMDALL(1, 0, 0x03)
 
 	case AVFMLA:
-		op = 7<<25 | 0<<23 | 1<<21 | 3<<14 | 3<<10
+		op = ASIMDSAME(0, 0, 0x19)
 
 	case AVFMLS:
-		op = 7<<25 | 1<<23 | 1<<21 | 3<<14 | 3<<10
+		op = ASIMDSAME(0, 2, 0x19)
 
 	case AVPMULL, AVPMULL2:
-		op = 0xE<<24 | 1<<21 | 0x38<<10
+		op = ASIMDDIFF(0, 0xE)
 
 	case AVRBIT:
-		op = 0x2E<<24 | 1<<22 | 0x10<<17 | 5<<12 | 2<<10
+		op = ASIMDMISC(1, 1, 0x05)
 
 	case AVLD1, AVLD2, AVLD3, AVLD4:
 		op = 3<<26 | 1<<22
@@ -6502,37 +6529,37 @@ func (c *ctxt7) oprrr(p *obj.Prog, a obj.As, rd, rn, rm int16) uint32 {
 		op = 0xD<<24 | 3<<21
 
 	case AVBIF:
-		op = 1<<29 | 7<<25 | 7<<21 | 7<<10
+		op = ASIMDSAME(1, 3, 0x03)
 
 	case AVBIT:
-		op = 1<<29 | 0x75<<21 | 7<<10
+		op = ASIMDSAME(1, 2, 0x03)
 
 	case AVBSL:
-		op = 1<<29 | 0x73<<21 | 7<<10
+		op = ASIMDSAME(1, 1, 0x03)
 
 	case AVCMTST:
-		op = 0xE<<24 | 1<<21 | 0x23<<10
+		op = ASIMDSAME(0, 0, 0x11)
 
 	case AVUMAX:
-		op = 1<<29 | 7<<25 | 1<<21 | 0x19<<10
+		op = ASIMDSAME(1, 0, 0x0C)
 
 	case AVUMIN:
-		op = 1<<29 | 7<<25 | 1<<21 | 0x1b<<10
+		op = ASIMDSAME(1, 0, 0x0D)
 
 	case AVUZP1:
-		op = 7<<25 | 3<<11
+		op = ASIMDPERM(0x1)
 
 	case AVUZP2:
-		op = 7<<25 | 1<<14 | 3<<11
+		op = ASIMDPERM(0x5)
 
 	case AVUADDW, AVUADDW2:
-		op = 0x17<<25 | 1<<21 | 1<<12
+		op = ASIMDDIFF(1, 0x1)
 
 	case AVTRN1:
-		op = 7<<25 | 5<<11
+		op = ASIMDPERM(0x2)
 
 	case AVTRN2:
-		op = 7<<25 | 1<<14 | 5<<11
+		op = ASIMDPERM(0x6)
 
 	default:
 		c.ctxt.Diag("%v: bad rrr %d %v", p, a, a)
@@ -6733,28 +6760,25 @@ func (c *ctxt7) opirr(p *obj.Prog, a obj.As) uint32 {
 		return 0x2E<<24 | 0<<23 | 0<<21 | 0<<15
 
 	case AVUSHR:
-		return 0x5E<<23 | 1<<10
+		return ASIMDSHF(1, 0x00)
 
 	case AVSHL:
-		return 0x1E<<23 | 21<<10
+		return ASIMDSHF(0, 0x0A)
 
 	case AVSRI:
-		return 0x5E<<23 | 17<<10
+		return ASIMDSHF(1, 0x08)
 
 	case AVSLI:
-		return 0x5E<<23 | 21<<10
-
-	case AVUSHLL, AVUXTL:
-		return 1<<29 | 15<<24 | 0x29<<10
+		return ASIMDSHF(1, 0x0A)
 
-	case AVUSHLL2, AVUXTL2:
-		return 3<<29 | 15<<24 | 0x29<<10
+	case AVUSHLL, AVUXTL, AVUSHLL2, AVUXTL2:
+		return ASIMDSHF(1, 0x14)
 
 	case AVXAR:
 		return 0xCE<<24 | 1<<23
 
 	case AVUSRA:
-		return 1<<29 | 15<<24 | 5<<10
+		return ASIMDSHF(1, 0x02)
 
 	case APRFM:
 		return 0xf9<<24 | 2<<22