VPGATHERDQ X2, 664(X2*8), X7    // ERROR "mask, index, and destination registers should be distinct"
	VPGATHERDQ X2, 664(X7*8), X2    // ERROR "mask, index, and destination registers should be distinct"
	VPGATHERDQ X7, 664(X2*8), X2    // ERROR "mask, index, and destination registers should be distinct"
	// Non-X0 for Yxr0 should produce an error

		// Test AVX512 suffixes.
		{"VADDPD.A X0, X1, X2", `unknown suffix "A"`},
		{"VADDPD.A.A X0, X1, X2", `unknown suffix "A"; duplicate suffix "A"`},
		{"VADDPD.A.A.A X0, X1, X2", `unknown suffix "A"; duplicate suffix "A"`},
		{"VADDPD.A.B X0, X1, X2", `unknown suffix "A"; unknown suffix "B"`},
		{"VADDPD.Z.A X0, X1, X2", `Z suffix should be the last; unknown suffix "A"`},
		{"VADDPD.Z.Z X0, X1, X2", `Z suffix should be the last; duplicate suffix "Z"`},

	{"g", "R14"},
	{"SI", "SI"},
	{"SP", "SP"},
	{"X0", "X0"},
	{"X1", "X1"},
	{"X10", "X10"},
	{"X11", "X11"},
	{"X12", "X12"},
	{"X13", "X13"},
	{"X14", "X14"},
	{"X15", "X15"},
	{"X2", "X2"},
	{"X3", "X3"},
	{"X4", "X4"},
	{"X5", "X5"},
	{"X6", "X6"},
	{"X7", "X7"},
	{"X8", "X8"},
	{"X9", "X9"},
	{"_expand_key_128<>(SB)", "_expand_key_128<>(SB)"},
	{"_seek<>(SB)", "_seek<>(SB)"},

Thus the length and capacity of a slice literal are the maximum
element index plus one. A slice literal has the form
</p>

<pre>
[]T{x1, x2, … xn}
</pre>

<p>
and is shorthand for a slice operation applied to an array:
</p>

<pre>
tmp := [n]T{x1, x2, … xn}
tmp[0 : n]
</pre>

<p>
Within a composite literal of array, slice, or map type <code>T</code>,

			x1 := p.getConstant(prog, op, &a[1])
			x2 := int64(p.getRegister(prog, op, &a[2]))
			x3 := int64(p.getRegister(prog, op, &a[3]))
			x4 := int64(p.getRegister(prog, op, &a[4]))
			x5 := p.getConstant(prog, op, &a[5])
			// Cond is handled specially for this instruction.
			offset, MRC, ok := arch.ARMMRCOffset(op, cond, x0, x1, x2, x3, x4, x5)
			if !ok {
				p.errorf("unrecognized condition code .%q", cond)

Thus the length and capacity of a slice literal are the maximum
element index plus one. A slice literal has the form
</p>

<pre>
[]T{x1, x2, … xn}
</pre>

<p>
and is shorthand for a slice operation applied to an array:
</p>

<pre>
tmp := [n]T{x1, x2, … xn}
tmp[0 : n]
</pre>

<p>
Within a composite literal of array, slice, or map type <code>T</code>,