vsdg: nullary operation helper templates
vsdg: nullary operation helper templates

Provide two auxiliary helpers to implement nullary operators representing
a "value constant" and a "symbolic constant" within a specific domain.

Signed-off-by: Nico Reißmann <d8255cca0642bdc1e6f9b45da9cb618d308e389b@gmail.com>

phate/jive,phate/jive,phate/jive