(truncation towards zero).
</li>
<li>
When converting an integer or floating-point number to a floating-point type,
or a complex number to another complex type, the result value is rounded
to the precision specified by the destination type.
For instance, the value of a variable <code>x</code> of type <code>float32</code>
may be stored using additional precision beyond that of an IEEE 754 32-bit number,

	VPGATHERQQ Y2, (BP)(X2*2), Y2   // ERROR "mask, index, and destination registers should be distinct"
	VPGATHERQQ Y2, (BP)(X2*2), Y7   // ERROR "mask, index, and destination registers should be distinct"
	VPGATHERQQ Y2, (BP)(X7*2), Y2   // ERROR "mask, index, and destination registers should be distinct"
	VPGATHERQQ Y7, (BP)(X2*2), Y2   // ERROR "mask, index, and destination registers should be distinct"

	ADDSW	$0x10001000100011, R6, RSP                       // ERROR "illegal destination register"
	SUBS	$0xff, R6, RSP                                   // ERROR "illegal destination register"
	SUBS	$0xffff0, R6, RSP                                // ERROR "illegal destination register"
	SUBS	$0x1000100010001000, R6, RSP                     // ERROR "illegal destination register"

	STREX	R1, (R0), R1       // ERROR "cannot use same register as both source and destination"
	STREX	R1, (R0), R0       // ERROR "cannot use same register as both source and destination"
	STREXD	R0, (R2), R0       // ERROR "cannot use same register as both source and destination"
	STREXD	R0, (R2), R1       // ERROR "cannot use same register as both source and destination"

func append(slice []Type, elems ...Type) []Type

// The copy built-in function copies elements from a source slice into a
// destination slice. (As a special case, it also will copy bytes from a
// string to a slice of bytes.) The source and destination may overlap. Copy
// returns the number of elements copied, which will be the minimum of
// len(src) and len(dst).
func copy(dst, src []Type) int

		return
	}
	a.Reg = r1
	if r2 != 0 {
		// TODO: Consistency in the encoding would be nice here.
		if p.arch.InFamily(sys.ARM, sys.ARM64) {
			// Special form
			// ARM: destination register pair (R1, R2).
			// ARM64: register pair (R1, R2) for LDP/STP.
			if prefix != 0 || scale != 0 {
				p.errorf("illegal address mode for register pair")
				return
			}
			a.Type = obj.TYPE_REGREG

					p.errorf("invalid addressing modes for 1st or 3rd operand to %s instruction, must be register pair", op)
					return
				}
				// For ARM64 CASP-like instructions, its 2nd destination operand is register pair(Rt, Rt+1) that can
				// not fit into prog.RegTo2, so save it to the prog.RestArgs.
				prog.AddRestDest(a[2])
			default:
				prog.From = a[0]
				prog.Reg = p.getRegister(prog, op, &a[1])

a source <code>src</code> to a destination <code>dst</code> and returns the
number of elements copied.
The <a href="#Core_types">core types</a> of both arguments must be slices
with <a href="#Type_identity">identical</a> element type.
The number of elements copied is the minimum of
<code>len(src)</code> and <code>len(dst)</code>.
As a special case, if the destination's core type is <code>[]byte</code>,

<li>
<code>[R0,g,R12-R15]</code>: For multi-register instructions, the set comprising
<code>R0</code>, <code>g</code>, and <code>R12</code> through <code>R15</code> inclusive.
</li>

<li>
<code>(R5, R6)</code>: Destination register pair.
</li>

</ul>

<h3 id="arm64">ARM64</h3>

<p>
<code>R18</code> is the "platform register", reserved on the Apple platform.

		return true
	}
	return false
}

// IsARM64CASP reports whether the op (as defined by an arm64.A*
// constant) is one of the CASP-like instructions, and its 2nd
// destination is a register pair that require special handling.
func IsARM64CASP(op obj.As) bool {
	switch op {
	case arm64.ACASPD, arm64.ACASPW:
		return true
	}
	return false
}