feat(asm): encode the arm64 SVE gather loads and scatter stores

Assisted-by: GLM 5.3

asm/extension_test.go

@@ -360,12 +360,32 @@ func TestExtensionNamesARM64(t *testing.T) {
 		"ZFADDAH",
 		"ZFADDAS",
 		"ZFADDAD",
+		// The gather loads and scatter stores: plain, sign-extended and
+		// first-fault loads, and the stores, in first-occurrence order.
+		"ZLD1B",
+		"ZLD1D",
+		"ZLD1H",
+		"ZLD1SB",
+		"ZLD1SH",
+		"ZLD1SW",
+		"ZLD1W",
+		"ZLDFF1B",
+		"ZLDFF1D",
+		"ZLDFF1H",
+		"ZLDFF1SB",
+		"ZLDFF1SH",
+		"ZLDFF1SW",
+		"ZLDFF1W",
+		"ZST1B",
+		"ZST1D",
+		"ZST1H",
+		"ZST1W",
 	}
 	got := ExtensionNames(arch.ARM64)
 	if strings.Join(got, ",") != strings.Join(want, ",") {
 		t.Errorf("ExtensionNames(ARM64) = %v, want %v", got, want)
 	}
-	if n := len(arch.Extensions(arch.ARM64)); n != 251 {
-		t.Errorf("the family registers %d instructions, want 251", n)
+	if n := len(arch.Extensions(arch.ARM64)); n != 381 {
+		t.Errorf("the family registers %d instructions, want 381", n)
 	}
 }