cmd/internal/obj/arm64: add ASIMD shift instructions

Add support for ASIMD shift instructions. These use the ASIMDSHF
encoding class from the ARM architecture specification, where the
shift amount is encoded as an immediate derived from the element size.
Also add ASIMD shifts-by-vector (3-register form) where the shift
amount comes from a second vector register. These use the ASIMDSAME
encoding class.

New instructions by group:

  Shift by immediate (signed):  VSSHR, VSRSHR
  Shift by immediate (saturating): VSQSHL, VUQSHL
  Narrowing shift by immediate: VSHRN, VSHRN2
  Shift by vector (3-reg):     VSSHL, VUSHL, VSQSHL, VUQSHL

Change-Id: I039cc16bc01980b04e6940cc1d4670faf5fa7e3c
Reviewed-on: https://go-review.googlesource.com/c/go/+/762180
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

3 files changed, 75 insertions, 5 deletions

diff --git a/src/cmd/internal/obj/arm64/a.out.go b/src/cmd/internal/obj/arm64/a.out.go
index fdc42eabaa..56f68756fd 100644
--- a/src/cmd/internal/obj/arm64/a.out.go
+++ b/src/cmd/internal/obj/arm64/a.out.go
@@ -1161,7 +1161,13 @@ const (
 	AVREV32
 	AVREV64
 	AVSHL
+	AVSHRN
+	AVSHRN2
 	AVSLI
+	AVSQSHL
+	AVSSHL
+	AVUSHL
+	AVUQSHL
 	AVSRI
 	AVST1
 	AVST2
@@ -1180,6 +1186,8 @@ const (
 	AVUSHLL
 	AVUSHLL2
 	AVUSHR
+	AVSRSHR
+	AVSSHR
 	AVUSRA
 	AVUXTL
 	AVUXTL2
diff --git a/src/cmd/internal/obj/arm64/anames.go b/src/cmd/internal/obj/arm64/anames.go
index 04986e1748..e40c043edd 100644
--- a/src/cmd/internal/obj/arm64/anames.go
+++ b/src/cmd/internal/obj/arm64/anames.go
@@ -517,7 +517,13 @@ var Anames = []string{
 	"VREV32",
 	"VREV64",
 	"VSHL",
+	"VSHRN",
+	"VSHRN2",
 	"VSLI",
+	"VSQSHL",
+	"VSSHL",
+	"VUSHL",
+	"VUQSHL",
 	"VSRI",
 	"VST1",
 	"VST2",
@@ -536,6 +542,8 @@ var Anames = []string{
 	"VUSHLL",
 	"VUSHLL2",
 	"VUSHR",
+	"VSRSHR",
+	"VSSHR",
 	"VUSRA",
 	"VUXTL",
 	"VUXTL2",
diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index ecc62251a0..0d8c1f417e 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/src/cmd/internal/obj/arm64/asm7.go
@@ -542,7 +542,9 @@ var optab = []Optab{
 	{AVEXT, C_VCON, C_ARNG, C_ARNG, C_ARNG, C_NONE, 94, 4, 0, 0, 0},
 	{AVTBL, C_ARNG, C_NONE, C_LIST, C_ARNG, C_NONE, 100, 4, 0, 0, 0},
 	{AVUSHR, C_VCON, C_ARNG, C_NONE, C_ARNG, C_NONE, 95, 4, 0, 0, 0},
+	{AVSQSHL, C_VCON, C_ARNG, C_NONE, C_ARNG, C_NONE, 95, 4, 0, 0, 0},
 	{AVZIP1, C_ARNG, C_ARNG, C_NONE, C_ARNG, C_NONE, 72, 4, 0, 0, 0},
+	{AVSQSHL, C_ARNG, C_ARNG, C_NONE, C_ARNG, C_NONE, 72, 4, 0, 0, 0},
 	{AVUSHLL, C_VCON, C_ARNG, C_NONE, C_ARNG, C_NONE, 102, 4, 0, 0, 0},
 	{AVUXTL, C_ARNG, C_NONE, C_NONE, C_ARNG, C_NONE, 102, 4, 0, 0, 0},
 	{AVUADDW, C_ARNG, C_ARNG, C_NONE, C_ARNG, C_NONE, 105, 4, 0, 0, 0},
@@ -3217,6 +3219,8 @@ func buildop(ctxt *obj.Link) {
 			oprangeset(AVBIT, t)
 			oprangeset(AVCMTST, t)
 			oprangeset(AVCMHI, t)
+			oprangeset(AVSSHL, t)
+			oprangeset(AVUSHL, t)
 			oprangeset(AVCMHS, t)
 			oprangeset(AVUMAX, t)
 			oprangeset(AVUMIN, t)
@@ -3277,6 +3281,13 @@ func buildop(ctxt *obj.Link) {
 			oprangeset(AVSRI, t)
 			oprangeset(AVSLI, t)
 			oprangeset(AVUSRA, t)
+			oprangeset(AVSSHR, t)
+			oprangeset(AVSRSHR, t)
+			oprangeset(AVSHRN, t)
+			oprangeset(AVSHRN2, t)
+
+		case AVSQSHL:
+			oprangeset(AVUQSHL, t)
 
 		case AVREV32:
 			oprangeset(AVCNT, t)
@@ -5431,14 +5442,15 @@ func (c *ctxt7) asmout(p *obj.Prog, out []uint32) (count int) {
 		af := int((p.Reg >> 5) & 15)
 		shift := int(p.From.Offset)
 
-		if af != at {
+		if af != at && p.As != AVSHRN && p.As != AVSHRN2 {
 			c.ctxt.Diag("invalid arrangement on op Vn.<T>, Vd.<T>: %v", p)
+			at = af
 		}
 
 		var Q uint32
 		var imax, esize int
 
-		switch af {
+		switch at {
 		case ARNG_8B, ARNG_4H, ARNG_2S:
 			Q = 0
 		case ARNG_16B, ARNG_8H, ARNG_4S, ARNG_2D:
@@ -5447,29 +5459,44 @@ func (c *ctxt7) asmout(p *obj.Prog, out []uint32) (count int) {
 			c.ctxt.Diag("invalid arrangement on op Vn.<T>, Vd.<T>: %v", p)
 		}
 
-		switch af {
+		atwice := -1
+		switch at {
 		case ARNG_8B, ARNG_16B:
 			imax = 15
 			esize = 8
+			atwice = ARNG_8H
 		case ARNG_4H, ARNG_8H:
 			imax = 31
 			esize = 16
+			atwice = ARNG_4S
 		case ARNG_2S, ARNG_4S:
 			imax = 63
 			esize = 32
+			atwice = ARNG_2D
 		case ARNG_2D:
 			imax = 127
 			esize = 64
 		}
 
+		switch p.As {
+		case AVSHRN:
+			if Q != 0 || atwice != af {
+				c.ctxt.Diag("invalid arrangement on op: %v", p)
+			}
+		case AVSHRN2:
+			if Q != 1 || atwice != af {
+				c.ctxt.Diag("invalid arrangement on op: %v", p)
+			}
+		}
+
 		imm := 0
 		switch p.As {
-		case AVUSHR, AVSRI, AVUSRA:
+		case AVUSHR, AVSRI, AVUSRA, AVSSHR, AVSRSHR, AVSHRN, AVSHRN2:
 			imm = esize*2 - shift
 			if imm < esize || imm > imax {
 				c.ctxt.Diag("shift out of range: %v", p)
 			}
-		case AVSHL, AVSLI:
+		case AVSHL, AVSLI, AVSQSHL, AVUQSHL:
 			imm = esize + shift
 			if imm > imax {
 				c.ctxt.Diag("shift out of range: %v", p)
@@ -6538,9 +6565,21 @@ func (c *ctxt7) oprrr(p *obj.Prog, a obj.As, rd, rn, rm int16) uint32 {
 	case AVSUB:
 		op = ASIMDSAME(1, 0, 0x10)
 
+	case AVSSHL:
+		op = ASIMDSAME(0, 0, 0x8)
+
+	case AVUSHL:
+		op = ASIMDSAME(1, 0, 0x8)
+
 	case AVADDP:
 		op = ASIMDSAME(0, 0, 0x17)
 
+	case AVSQSHL:
+		op = ASIMDSAME(0, 0, 0x9)
+
+	case AVUQSHL:
+		op = ASIMDSAME(1, 0, 0x9)
+
 	case AVAND:
 		op = ASIMDSAME(0, 0, 0x03)
 
@@ -6895,9 +6934,24 @@ func (c *ctxt7) opirr(p *obj.Prog, a obj.As) uint32 {
 	case AVUSHR:
 		return ASIMDSHF(1, 0x00)
 
+	case AVSSHR:
+		return ASIMDSHF(0, 0x00)
+
+	case AVSRSHR:
+		return ASIMDSHF(0, 0x04)
+
 	case AVSHL:
 		return ASIMDSHF(0, 0x0A)
 
+	case AVSQSHL:
+		return ASIMDSHF(0, 0xE)
+
+	case AVUQSHL:
+		return ASIMDSHF(1, 0xE)
+
+	case AVSHRN, AVSHRN2:
+		return ASIMDSHF(0, 0x10)
+
 	case AVSRI:
 		return ASIMDSHF(1, 0x08)