// amd64:"ADDQ\t\\$3"
  // amd64:`ADDQ\t\$3`

and they'll match this assembly line:

  ADDQ	$3

Negative matches can be specified using a - before the quoted regexp.
For example:

  func MoveSmall() {
  	   x := [...]byte{1, 2, 3, 4, 5, 6, 7}
  	   copy(x[1:], x[:]) // arm64:-".*memmove"
  }

verifies that NO memmove call is present in the assembly generated for
the copy() line.