The ability to invoke other operation lists belongs in the new CallOp.
While we're here, make MacroOp.Add use a pointer receiver to match the
other methods.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
We'd like to improve the API of Flex, Stack and similar layouts
that use MacroOps internall. Unfortunately, the
func (m MacroOp) Add(o *Ops)
method causes the MacroOp to be allocated on the heap, ruining the
nice garbage-free property of layouts.
Fortunately, layouts don't need the feature that caused the heap
allocation: invoking operation lists different than the current.
CallOp separates the invoke-different-list semantic from MacroOp,
in preparation for removing the feature from MacroOp.
Signed-off-by: Elias Naur <mail@eliasnaur.com>